WorldWideScience

Sample records for arid mine-impacted catchments

  1. Identifying Catchment-Scale Predictors of Coal Mining Impacts on New Zealand Stream Communities

    Science.gov (United States)

    Clapcott, Joanne E.; Goodwin, Eric O.; Harding, Jon S.

    2016-03-01

    Coal mining activities can have severe and long-term impacts on freshwater ecosystems. At the individual stream scale, these impacts have been well studied; however, few attempts have been made to determine the predictors of mine impacts at a regional scale. We investigated whether catchment-scale measures of mining impacts could be used to predict biological responses. We collated data from multiple studies and analyzed algae, benthic invertebrate, and fish community data from 186 stream sites, including un-mined streams, and those associated with 620 mines on the West Coast of the South Island, New Zealand. Algal, invertebrate, and fish richness responded to mine impacts and were significantly higher in un-mined compared to mine-impacted streams. Changes in community composition toward more acid- and metal-tolerant species were evident for algae and invertebrates, whereas changes in fish communities were significant and driven by a loss of nonmigratory native species. Consistent catchment-scale predictors of mining activities affecting biota included the time post mining (years), mining density (the number of mines upstream per catchment area), and mining intensity (tons of coal production per catchment area). Mining was associated with a decline in stream biodiversity irrespective of catchment size, and recovery was not evident until at least 30 years after mining activities have ceased. These catchment-scale predictors can provide managers and regulators with practical metrics to focus on management and remediation decisions.

  2. Rapid dissolution of soluble uranyl phases in arid, mine-impacted catchments near Church Rock, NM.

    Science.gov (United States)

    deLemos, Jamie L; Bostick, Benjamin C; Quicksall, Andrew N; Landis, Joshua D; George, Christine C; Slagowski, Naomi L; Rock, Tommy; Brugge, Doug; Lewis, Johnnye; Durant, John L

    2008-06-01

    We tested the hypothesis that runoff of uranium-bearing particles from mining waste disposal areas was a significant mechanism for redistribution of uranium in the northeastern part of the Upper Puerco River watershed (New Mexico). However, our results were not consistent with this hypothesis. Analysis of > 100 sediment and suspended sediment samples collected adjacent to and downstream from uranium source areas indicated that uranium levels in the majority of the samples were not elevated above background. Samples collected within 50 m of a known waste disposal site were subjected to detailed geochemical characterization. Uranium in these samples was found to be highly soluble; treatment with synthetic pore water for 24 h caused dissolution of 10--50% of total uranium in the samples. Equilibrium uranium concentrations in pore water were > 4.0 mg/L and were sustained in repeated wetting events, effectively depleting soluble uranium from the solid phase. The dissolution rate of uranium appeared to be controlled by solid-phase diffusion of uranium from within uranium-bearing mineral particles. X-ray adsorption spectroscopy indicated the presence of a soluble uranyl silicate, and possibly a uranyl phosphate. These phases were exhausted in transported sediment suggesting that uranium was readily mobilized from sediments in the Upper Puerco watershed and transported in the dissolved load. These results could have significance for uranium risk assessment as well as mining waste management and cleanup efforts.

  3. Potential of green infrastructure to restore predevelopment water budget of a semi-arid urban catchment

    Science.gov (United States)

    Feng, Youcan; Burian, Steven; Pomeroy, Christine

    2016-11-01

    This paper presents a study of the potential for green infrastructure (GI) to restore the predevelopment hydrologic cycle in a semi-arid urban catchment. Simulations of stormwater runoff from a 0.11-km2 urban catchment in Salt Lake City, Utah, USA for predeveloped (Natural Hydrology, NH), developed (Baseline, BL), and developed with GI (Green Infrastructure, GI) conditions were executed for a one-year period. The study was repeated for a relatively dry year, wet year, and an average year based on precipitation amounts in the year. Bioretention and green roofs were chosen for the GI plan. Results showed that the water budget of the catchment with the GI plan implemented more closely matches the NH water budget compared to the BL scenario, for all three years (dry, wet, average). The BL and GI scenarios showed more significant modifications to the water budget than what has been found by studies in humid climates. Compared to the BL condition, GI annually reduces surface runoff by 35%, 45%, and 43% and restores evapotranspiration by 18%, 19%, and 25% for the dry, average, wet years, respectively. Based on the introduced water budget restoration coefficient (WBRC), the water budget of the study catchment was restored by the GI plan to 90%, 90%, and 82% of the predevelopment state in the dry, average, and wet years, respectively. By comparing the WBRC estimated for other studies, it is further inferred that the water budget is more significantly affected by development and GI restoration in semi-arid than humid climates, but the differences lessen as the precipitation amount increases.

  4. Application of spatially varying storage capacity model for runoff parameterization in semi-arid catchment

    Institute of Scientific and Technical Information of China (English)

    Li-liang REN; Gui-zuo WANG; Fang LU; Tian-fang FANG

    2009-01-01

    This paper introduces the method of designation of water storage capacity for each grid cell within a catchment, which considers topography, vegetation and soil synthetically. For the purpose of hydrological process simulation in semi-arid regions, a spatially varying storage capacity (VSC) model was developed based on the spatial distribution of water storage capacity and the vertical hybrid runoff mechanism. To verify the applicability of the VSC model, both the VSC model and a hybrid runoff model were used to simulate daily runoff processes in the catchment upstream of the Dianzi hydrological station from 1973 to 1979. The results showed that the annual average Nash-Sutcliffe coefficient was 0.80 for the VSC model, and only 0.67 for the hybrid runoff model. The higher annual average Nash-Sutcliffe coefficient of the VSC model means that this hydrological model can better simulate daily runoff processes in semi-arid regions. Furthermore, as a distributed hydrological model, the VSC model can be applied in regional water resource management.

  5. Application of spatially varying storage capacity model for runoff parameterization in semi-arid catchment

    Directory of Open Access Journals (Sweden)

    Li-liang REN

    2009-06-01

    Full Text Available This paper introduces the method of designation of water storage capacity for each grid cell within a catchment, which considers topography, vegetation and soil synthetically. For the purpose of hydrological process simulation in semi-arid regions, a spatially varying storage capacity (VSC model was developed based on the spatial distribution of water storage capacity and the vertical hybrid runoff mechanism. To verify the applicability of the VSC model, both the VSC model and a hybrid runoff model were used to simulate daily runoff processes in the catchment upstream of the Dianzi hydrological station from 1973 to 1979. The results showed that the annual average Nash-Sutcliffe coefficient was 0.80 for the VSC model, and only 0.67 for the hybrid runoff model. The higher annual average Nash-Sutcliffe coefficient of the VSC model means that this hydrological model can better simulate daily runoff processes in semi-arid regions. Furthermore, as a distributed hydrological model, the VSC model can be applied in regional water resource management.

  6. What happens after the catchment caught the storm? Hydrological processes at the small, semi-arid Weatherley catchment, South-Africa

    Directory of Open Access Journals (Sweden)

    S. Uhlenbrook

    2005-01-01

    Full Text Available The knowledge of water flow pathways and residence times in a catchment are essential for predicting the hydrological response to a rain storm event. Different experimental techniques are available to study these processes, which are briefly reviewed in this paper. To illustrate this, recent findings from the Weatherley catchment a 1.5 km2 semi-arid headwater in South-Africa, are reported in this paper. Beside classical hydrometric measurements of precipitation and runoff different experimental techniques were applied to explore flow paths (i.e. soil moisture and groundwater measurements, natural tracers, and 2-D electrical resistivity tomographies (ERT.

  7. Predicting forested catchment evapotranspiration and streamflow from stand sapwood area and Aridity Index

    Science.gov (United States)

    Lane, Patrick

    2016-04-01

    Estimating the water balance of ungauged catchments has been the subject of decades of research. An extension of the fundamental problem of estimating the hydrology is then understanding how do changes in catchment attributes affect the water balance component? This is a particular issue in forest hydrology where vegetation exerts such a strong influence on evapotranspiration (ET), and consequent streamflow (Q). Given the primacy of trees in the water balance, and the potential for change to species and density through logging, fire, pests and diseases and drought, methods that directly relate ET/Q to vegetation structure, species, and stand density are very powerful. Plot studies on tree water use routinely use sapwood area (SA) to calculate transpiration and upscale to the stand/catchment scale. Recent work in south eastern Australian forests have found stand-wide SA to be linearly correlated (R2 = 0.89) with long term mean annual loss (P-Q), and hence, long term mean annual catchment streamflow. Robust relationships can be built between basal area (BA), tree density and stand SA. BA and density are common forest inventory measurements. Until now, no research has related the fundamental stand attribute of SA to streamflow. The data sets include catchments that have been thinned and with varying age classes. Thus far these analyses have been for energy limited systems in wetter forest types. SA has proven to be a more robust biometric than leaf area index which varies seasonally. That long term ET/Q is correlated with vegetation conforms to the Budyko framework. Use of a downscaled (20 m) Aridity Index (AI) has shown distinct correlations with stand SA, and therefore T. Structural patterns at a the hillslope scale not only correlate with SA and T, but also with interception (I) and forest floor evaporation (Es). These correlations between AI and I and Es have given R2 > 0.8. The result of these studies suggest an ability to estimate mean annual ET fluxes at sub

  8. Integrated Modelling of Climate Change Impacts in an Irrigated, Semi-arid Catchment

    Science.gov (United States)

    Haslauer, C. P.; von Gunten, D.; Wöhling, T.; Rudolph, D. L.; Cirpka, O. A.

    2015-12-01

    Predicting the impacts of climate change on hydrological processes is a central challenge for water management. Commonly, studies on climate-change effects focus on surface flow and feed-backs between surface and subsurface flows are neglected frequently. Furthermore, changes in hydrological processes are generally not distributed realistically. Integrated catchment models, based on partial-differential-equations, have the potential of overcoming these difficulties. However, these models are complicated to use in realistic settings, notably because of their long simulation time. In this presentation, we demonstrate a successful application of an integrated catchment model (HydroGeoSphere) in a semi-arid catchment in north-east Spain. The study area recently underwent a transition to irrigated agriculture, which is reflected in our model evaluations conducted under varying irrigation conditions. To accelerate model calibration, we developed a novel calibration method based on a hierarchy of computational grids. The climate scenarios for the region are based on four regional climate models, which are downscaled using a weather generator. These scenarios are used to estimate climate change impacts on hydrologic parameters in different irrigation settings. The effects of climate change strongly depend on the presence of irrigation. Water table depth and low flows are more sensitive to climate change when irrigation is present, while peak flows exhibit a more pronounced response to climate in scenarios without irrigation. In addition to the climatic means, we examined the impacts of changes in drought conditions. We compare the outcomes of droughts predicted by our hydrological model with simpler approaches based on drought indices. We show that drought indices oversimplify future hydrological impacts of droughts and can result in biased estimation of drought impacts, especially if drought indices do not take temperature changes into account.

  9. Establishing the Ecological Status of Mining-Impacted Freshwaters from Abrud River Catchment Area Using Benthic Diatom Communities (Ros, ia MontanÄă, Romania)

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    Olenici, Adriana; Baciu, Calin; Momeu, Laura; Cozma, Alexandra; Brahaita, Dorian; Pop, Cristian; Lazar, Laura; Popita, Gabriela; Teodosiu, Gabriela

    2015-04-01

    Keywords: diatom communities, indicator species, mine waters, water quality, Romania. Diatoms are a very distinct group of algae, identifiable under the light microscope by their yellow - brown coloration and by the presence of a thick silica cell wall. The potential for freshwater organisms to reflect changes in environmental conditions was first noted by Kolenati (1848) and Cohn (1853), who observed that biota in polluted waters were different from those in non-polluted situations. Diatoms are widely used to monitor river pollution because they are sensitive to water chemistry, especially to ionic content, pH, dissolved organic matter and nutrients. Wide geographic distribution and well-studied ecology of most diatom species are mentioned as major advantages of using diatoms as indicator organisms. At the same time water quality has begun to deteriorate increasingly, mainly as a result of the physical, chemical and bacteriological alterations, and the aquatic ecosystems are evermore affected by various types of pollution, the anthropic one being almost always included. A good example is Abrud River and its main tributaries (Roșia Montană and surrounding areas, Romania), which has suffered along the years because of the mining waters discharge. In this context, this study presents data on benthic diatom communities from the Abrud River catchment area. Sixteen sites have been sampled seasonal and the best represented diatom genera were Navicula, Nitzschia, Cymbella, Gomphonema, Achnantes, Surirella and Fragilaria. Qualitatively, the number of diatom species exhibited significant variation among sampling sites, also suggesting seasonal dynamics. For instance, in some sampling sites, algal assemblages were absent, as diatom communities were strongly affected by acid mine waters, released from old mining works and waste rocks depots. Some dominant taxa have been observed as well, suggesting critical saprobic levels of the Abrud River and some of its tributaries. The

  10. Assessment of overland flow variation and blue water production in a farmed semi-arid water harvesting catchment

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    Mekki, I.; Albergel, J.; Ben Mechlia, N.; Voltz, M.

    Upgrading agriculture in semi-arid areas and ensuring its sustainability require an optimal management of rainfall partition between blue and green waters in the farmed water harvesting catchment. The main objective of this study is to analyze the influence of heterogeneous land use on the spatial and temporal variation of rainfall partitioning and blue water production within a typical farmed catchment located in north-eastern Tunisia. The catchment has an area of 2.6 km 2 and comprises at its outlet a dam, which retains the runoff water in a reservoir. Overland flow and soil water balance components were monitored during two cropping seasons (2000/2001 and 2001/2002) on a network of eleven plots of 2 m 2 each with different land use and soil characteristics. The hydrological balances of both the catchment and reservoir have been monitored since 1994. Observed data showed a very large temporal and spatial variability of overland flow within the catchment reflecting the great importance of total rainfall as well as land use. During the 2001/2002 season the results showed a large variation of the number of observed runoff events, from 27 to 39, and of the annual overland flow depths, from 8 mm (under vineyard on calcaric cambisols) up to 43 mm (under shrubs-pasture on haplic regosols), between the plots. The annual runoff amounts were moderate; they always corresponded to less than 15% of the annual rainfall amount whatever the observation scale. It was also observed that changes in land use in years with similar rainfall could lead to significant differences in blue water flow. An attempt for predicting the overland flow by the general linear regression approach showed an r2 of 31%, the predictors used are the class of soil infiltration capacity, the initial moisture saturation ratio of the soil surface layer and the total rainfall amounts. These experimental results indicate that the variation in land use in a semi-arid catchment is a main factor of variation in

  11. Land degradation assessment by geo-spatially modeling different soil erodibility equations in a semi-arid catchment.

    Science.gov (United States)

    Saygın, Selen Deviren; Basaran, Mustafa; Ozcan, Ali Ugur; Dolarslan, Melda; Timur, Ozgur Burhan; Yilman, F Ebru; Erpul, Gunay

    2011-09-01

    Land degradation by soil erosion is one of the most serious problems and environmental issues in many ecosystems of arid and semi-arid regions. Especially, the disturbed areas have greater soil detachability and transportability capacity. Evaluation of land degradation in terms of soil erodibility, by using geostatistical modeling, is vital to protect and reclaim susceptible areas. Soil erodibility, described as the ability of soils to resist erosion, can be measured either directly under natural or simulated rainfall conditions, or indirectly estimated by empirical regression models. This study compares three empirical equations used to determine the soil erodibility factor of revised universal soil loss equation prediction technology based on their geospatial performances in the semi-arid catchment of the Saraykoy II Irrigation Dam located in Cankiri, Turkey. A total of 311 geo-referenced soil samples were collected with irregular intervals from the top soil layer (0-10 cm). Geostatistical analysis was performed with the point values of each equation to determine its spatial pattern. Results showed that equations that used soil organic matter in combination with the soil particle size better agreed with the variations in land use and topography of the catchment than the one using only the particle size distribution. It is recommended that the equations which dynamically integrate soil intrinsic properties with land use, topography, and its influences on the local microclimates, could be successfully used to geospatially determine sites highly susceptible to water erosion, and therefore, to select the agricultural and bio-engineering control measures needed.

  12. Perched groundwater-surface interactions and their consequences in stream flow generation in a semi-arid headwater catchment

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    Molenat, Jerome; Bouteffeha, Maroua; Raclot, Damien; Bouhlila, Rachida

    2013-04-01

    In semi-arid headwater catchment, it is usually admitted that stream flow comes predominantly from Hortonian overland flow (infiltration excess overland flow). Consequently, subsurface flow processes, and especially perched or shallow groundwater flow, have not been studied extensively. Here we made the assumption that perched groundwater flow could play a significant role in stream flow generation in semi-arid catchment. To test this assumption, we analyzed stream flow time series of a headwater catchment in the Tunisian Cap Bon region and quantified the flow fraction coming from groundwater discharge and that from overland flow. Furthermore, the dynamics of the perched groundwater was analyzed, by focusing on the different perched groundwater-surface interaction processes : diffuse and local infiltration, diffuse exfiltration, and direct groundwater discharge to the stream channel. This work is based on the 2.6 km² Kamech catchment (Tunisia), which belongs to the long term Mediterranean hydrological observatory OMERE (Voltz and Albergel, 2002). Results show that even though Hortonian overland flow was the main hydrological process governing the stream flow generation, groundwater discharge contribution to the stream channel annually accounted for from 10% to 20 % depending on the year. Furthermore, at some periods, rising of groundwater table to the soil surface in bottom land areas provided evidences of the occurrence of saturation excess overland flow processes during some storm events. Reference Voltz , M. and Albergel , J., 2002. OMERE : Observatoire Méditerranéen de l'Environnement Rural et de l'Eau - Impact des actions anthropiques sur les transferts de masse dans les hydrosystèmes méditerranéens ruraux. Proposition d'Observatoire de Recherche en Environnement, Ministère de la Recherche.

  13. Soil carbon storage in a small arid catchment in the Negev desert (Israel)

    Science.gov (United States)

    Hoffmann, Ulrike; Kuhn, Nikolaus

    2010-05-01

    The mineral soil represents a major pool in the global carbon cycle. The behavior of mineral soil as a carbon reservoir in global climate and environmental issues is far from fully understood and causes a serious lack of comparable data on mineral soil organic carbon (SOC) at regional scale. To improve our understanding of soil carbon sequestration, it is necessary to acquire regional estimates of soil carbon pools in different ecosystem types. So far, little attention has been given to Dryland ecosystems, but they are often considered as highly sensitive to environmental change, with large and rapid responses to even smallest changes of climate conditions. Due to this fact, Drylands, as an ecosystem with extensive surface area across the globe (6.15 billion ha), have been suggested as a potential component for major carbon storage. A priori reasoning suggests that regional spatial patterns of SOC density (kg/m²) in Drylands are mostly affected by vegetation, soil texture, landscape position, soil truncation, wind erosion/deposition and the effect of water supply. Particularly unassigned is the interaction between soil volume, geomorphic processes and SOC density on regional scale. This study aims to enhance our understanding of regional spatial variability in dependence on soil volume, topography and surface parameters in areas susceptible to environmental change. Soil samples were taken in small transects at different representative slope positions across a range of elevations, soil texture, vegetation types, and terrain positions in a small catchment (600 ha) in the Negev desert. Topographic variables were extracted from a high resolution (0.5m) digital elevation model. Subsequently, we estimated the soil volume by excavating the entire soil at the representative sampling position. The volume was then estimated by laser scanning before and after soil excavation. SOC concentration of the soil samples was determined by CHN-analyser. For each sample, carbon

  14. Observed variability of drought and aridity and its impact on the hydrological regime in the Barlad catchment (Romania)

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    Borcan, Mihaela; Cheval, Sorin; Chendes, Viorel

    2015-04-01

    The drought is a complex phenomenon with slow manifestation which engages, depending on its duration and intensity, a number of different components of the climatic, hydrologic, pedologic systems. This paper investigates the relationships between drought and aridity on one hand and hydrological regime, on the other hand, in Bârlad river basin, in the eastern part of Romania. Recent studies have revealed that both meteorological and hydrological drought events have a significant frequency and magnitude in the area, so that an important impact on the hydrological regime is likely to occur. For the next decades, climate change scenarios estimate increasing temperatures and relatively low decreasing of precipitation. Therefore, eventual changes in the aridity characteristics can be expected, and they might have a considerable impact on the water supply or agriculture in the Bârlad catchment. The analysis covers the period 1961-2013 and it is based on monthly data from meteorological and hydrological stations. Seasonal indices were calculated for characterising the drought (SPI, SFI, PDSI, PHDI) and aridity (UNEP, de Martonne, Pinna), while their temporal variability was further investigated in relations with specific hydrological parameters (monthly discharge time series). The spatial distribution of the selected indices was analysed in the same context using co-variables integrated in a GIS framework. The results show that the hydrological drought is influenced and determined mostly by the meteorological drought. The highest variability between the aridity indices has been identified for the summer season, where the time lag between the hydrological response to the meteorological impulse is up to 2 months. The work has been financed by the research project Changes in climate extremes and associated impact in hydrological events in Romania (CLIMHYDEX), Cod PN II-ID-2011-2-0073, sponsored by the National Authority for Scientific Research.

  15. Rainfall-Runoff Simulations in Arid Catchments in Sinai Peninsula, Egypt, using a Distributed Physically-based Hydrologic Model

    Science.gov (United States)

    Habib, E.; Elsayed, E. A.; Abdel-Motaleb, M.

    2008-05-01

    Egypt's Sinai Peninsula falls within an arid climatic belt that crosses northern Africa and southwestern Asia. Despite its aridity, Sinai is occasionally subjected to heavy rainfall causing flash floods, which are commonly characterized by sharp peak discharges with short durations. Several flash floods were recorded in south Sinai, which resulted in significant infrastructural damages, population displacement and, sometimes, loss of lives. Despite their hazardous effects, flash floods in Sinai, and other parts of southern Egypt, represent a potential resource for non-conventional fresh water sources. In order to mitigate flash flood damages and efficiently harvest the flash-flood highly needed fresh water, it is crucially important to accurately predict the occurrence of flash floods in terms of both timing and magnitude. Several studies have been implemented to develop hydrologic models for predicting flash floods in Sinai. In these studies, methodologies that are primarily conceptual, such as synthetic unit hydrographs, have shown little success at reproducing observed flood hydrographs. Physically-based distributed models provide an alternative approach for modeling food events in the Sinai arid environment. This study will examine the utility of a physically-based distributed hydrologic model (Gridded Surface-Subsurface Hydrologic Analysis, GSSHA) to simulate rainfall-runoff response in a small and a mid-size catchment in Sinai. GSSHA is a fully distributed-parameter, process-based hydrologic model that uses finite difference and finite volume methods to simulate different hydrologic processes. The watershed topographic and hydrologic properties are represented using Cartesian grids in the order of 100x100 m2. Overland hydraulic properties and soil hydraulic parameters were varied according to combined spatial classifications of soil type and land use maps. Field measurements of soil types and infiltration parameters were used to initially assign model

  16. Runoff controlling factors in various sized catchments in a semi-arid Mediterranean environment in Spain

    NARCIS (Netherlands)

    Wit, A.M.W. de

    2001-01-01

    Understanding land degradation in a semi-arid Mediterranean environment is very difficult because of the contributing factors: precipitation, infiltration vegetation cover and discontinuity of flow and the temporal and spatial levels of resolution at which these factors are acting. Therefore it is s

  17. Steam flow generation in semi-arid, forested and seasonally snow-covered catchments, Valles Caldera, New Mexico

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    Liu, F.; Bales, R. C.; Conklin, M. H.; Kostrzewski, J. M.

    2005-12-01

    Stream flow generation is poorly understood for semi-arid, forested and seasonally snow-covered catchments in southwest US. Here we report on initial results of a pioneer study on source waters and flowpaths using isotopic and geochemical tracers in two streams originated from Redondo Peak in Valles Caldera, New Mexico. The Valles Caldera is the latest collapse feature in the volcanic field and hosts high-temperature hydrothermal systems with several geothermal springs. It is currently covered by ponderosa pine in lower elevations and mixed conifer in higher elevations. Samples were collected from snow, hillslope groundwater, and stream water at Redondo Creek and La Jara Creek from December 2004 to July 2005. Using diagnostic tools of mixing models and end-member mixing analysis, it is suggested that stream water quantity and quality at Redondo Creek were primarily controlled by mixing of two end-members: hillslope subsurface water and geothermal springs. Hillslope subsurface water was sourced from snowmelt and then gradually released to stream flow through spring and summer. Infiltration-excess overland flow of snowmelt did not appear to occur. Contribution of hillslope subsurface water to stream flow was 90% on average from December 2004 to July 2005 and its percentage gradually increased from spring to summer with increase in discharge. Contribution of geothermal springs decreased on percentage over season with a peak (20%) in late march and lowest but relatively constant value (5%) through June and July. Stream flow generation at La Jara Creek was relatively simple, all from hillslope subsurface water. This information may improve our understanding of changes of hydrological and biogeochemical cycles in response to climate warming in these and similar catchments in southwest US.

  18. Challenges to estimate surface- and groundwater flow in arid regions: the Dead Sea catchment.

    Science.gov (United States)

    Siebert, Christian; Rödiger, Tino; Mallast, Ulf; Gräbe, Agnes; Guttman, Joseph; Laronne, Jonathan B; Storz-Peretz, Yael; Greenman, Anat; Salameh, Elias; Al-Raggad, Marwan; Vachtman, Dina; Ben Zvi, Arie; Ionescu, Danny; Brenner, Asher; Merz, Ralf; Geyer, Stefan

    2014-07-01

    The overall aim of the this study, which was conducted within the framework of the multilateral IWRM project SUMAR, was to expand the scientific basement to quantify surface- and groundwater fluxes towards the hypersaline Dead Sea. The flux significance for the arid vicinity around the Dead Sea is decisive not only for a sustainable management in terms of water availability for future generations but also for the resilience of the unique ecosystems along its coast. Coping with different challenges interdisciplinary methods like (i) hydrogeochemical fingerprinting, (ii) satellite and airborne-based thermal remote sensing, (iii) direct measurement with gauging station in ephemeral wadis and a first multilateral gauging station at the river Jordan, (iv) hydro-bio-geochemical approach at submarine and shore springs along the Dead Sea and (v) hydro(geo)logical modelling contributed to the overall aim. As primary results, we deduce that the following: (i) Within the drainage basins of the Dead Sea, the total mean annual precipitation amounts to 300 mm a(−1) west and to 179 mm a(−1) east of the lake, respectively. (ii) The total mean annual runoff volumes from side wadis (except the Jordan River) entering the Dead Sea is approximately 58–66 × 10(6) m(3) a(−1) (western wadis: 7–15 × 10(6) m(3) a(−1); eastern wadis: 51 × 10(6) m(3) a(−1)). (iii) The modelled groundwater discharge from the upper Cretaceous aquifers in both flanks of the Dead Sea towards the lake amounts to 177 × 10(6) m(3) a(−1). (iv) An unexpected abundance of life in submarine springs exists, which in turn explains microbial moderated geo-bio-chemical processes in the Dead Sea sediments, affecting the highly variable chemical composition of on- and offshore spring waters.The results of this work show a promising enhancement of describing and modelling the Dead Sea basin as a whole.

  19. Coupling Green-Ampt infiltration method and two-dimensional kinematic wave theory for flood forecast in semi-arid catchment

    Directory of Open Access Journals (Sweden)

    L.-L. Wang

    2011-08-01

    Full Text Available Due to the specific characteristics of semi-arid catchments, this paper aims to establish a grid-and-Green-Ampt-and-two-dimensional-kinematic-wave-based distributed hydrological physical model (Grid-GA-2D model coupling Green-Ampt infiltration method and two dimensional overland flow routing model based on kinematic wave theory for flood simulation and forecasting with using GIS technology and digital elevation model (DEM. Taking into consideration the soil moisture redistribution at hillslope, Green-Ampt infiltration physical method is applied for grid-based runoff generation and two-dimensional implicit finite difference kinematic wave model is introduced to solve depressions water storing for grid-based overland flow concentration routing in the Grid-GA-2D model. The Grid-GA-2D model, the Grid-GA model with coupling Green-Ampt infiltration method and one-dimension kinematic wave theory, and Shanbei model were employed to the upper Kongjiapo catchment in Qin River, a tributary of the Yellow River, with an area of 1454 km2 for flood simulation. Results show that two grid-based distributed hydrological models perform better in flood simulation and can be used for flood forecasting in semi-arid catchments. Comparing with the Grid-GA model, the flood peak simulation accuracy of the newly developed model is higher.

  20. Coupling Green-Ampt infiltration method and two-dimensional kinematic wave theory for flood forecast in semi-arid catchment

    Science.gov (United States)

    Wang, L.-L.; Chen, D.-H.; Li, Z.-J.; Zhao, L.-N.

    2011-08-01

    Due to the specific characteristics of semi-arid catchments, this paper aims to establish a grid-and-Green-Ampt-and-two-dimensional-kinematic-wave-based distributed hydrological physical model (Grid-GA-2D model) coupling Green-Ampt infiltration method and two dimensional overland flow routing model based on kinematic wave theory for flood simulation and forecasting with using GIS technology and digital elevation model (DEM). Taking into consideration the soil moisture redistribution at hillslope, Green-Ampt infiltration physical method is applied for grid-based runoff generation and two-dimensional implicit finite difference kinematic wave model is introduced to solve depressions water storing for grid-based overland flow concentration routing in the Grid-GA-2D model. The Grid-GA-2D model, the Grid-GA model with coupling Green-Ampt infiltration method and one-dimension kinematic wave theory, and Shanbei model were employed to the upper Kongjiapo catchment in Qin River, a tributary of the Yellow River, with an area of 1454 km2 for flood simulation. Results show that two grid-based distributed hydrological models perform better in flood simulation and can be used for flood forecasting in semi-arid catchments. Comparing with the Grid-GA model, the flood peak simulation accuracy of the newly developed model is higher.

  1. Reconstruction of the sediment flow regime in a semi-arid Mediterranean catchment using check dam sediment information.

    Science.gov (United States)

    Bussi, G.; Rodríguez, X.; Francés, F.; Benito, G.; Sánchez-Moya, Y.; Sopeña, A.

    2012-04-01

    When using hydrological and sedimentological models, lack of historical records is often one of the main problems to face, since observed data are essential for model validation. If gauged data are poor or absent, a source of additional proxy data may be the slack-water deposits accumulated in check dams. The aim of this work is to present the result of the reconstruction of the recent hydrological and sediment yield regime of a semi-arid Mediterranean catchment (Rambla del Poyo, Spain, 184 square km) by coupling palaeoflood techniques with a distributed hydrological and sediment cycle model, using as proxy data the sandy slack-water deposits accumulated upstream a small check dam (reservoir volume 2,500 square m) located in the headwater basin (drainage area 13 square km). The solid volume trapped into the reservoir has been estimated using differential GPS data and an interpolation technique. Afterwards, the total solid volume has been disaggregated into various layers (flood units), by means of a stratigraphical description of a depositional sequence in a 3.5 m trench made across the reservoir sediment deposit, taking care of identifying all flood units; the separation between flood units is indicated by a break in deposition. The sedimentary sequence shows evidence of 15 flood events that occurred after the dam construction (early '90). Not all events until the present are included; for the last ones, the stream velocity and energy conditions for generating slack-water deposits were not fulfilled due to the reservoir filling. The volume of each flood unit has been estimated making the hypothesis that layers have a simple pyramidal shape (or wedge); every volume represents an estimation of the sediments trapped into the reservoir corresponding to each flood event. The obtained results have been compared with the results of modeling a 20 year time series (1990 - 2009) with the distributed conceptual hydrological and sediment yield model TETIS-SED, in order to

  2. Implications of deep drainage through saline clay for groundwater recharge and sustainable cropping in a semi-arid catchment, Australia

    Directory of Open Access Journals (Sweden)

    W. A. Timms

    2011-11-01

    Full Text Available The magnitude and timing of deep drainage and salt leaching through clay soils is a critical issue for dryland agriculture in semi-arid regions (<500 mm yr−1 rainfall, such as parts of Australia's Murray-Darling Basin (MDB. In this unique study, hydrogeological measurements and estimations of the historic water balance of crops grown on overlying Grey Vertosols were combined to estimate the contribution of deep drainage below crop roots to recharge and salinization of shallow groundwater. Soil sampling at two sites on the alluvial flood plain of the Lower Namoi catchment revealed significant peaks in chloride concentrations at 0.8–1.2 m depth under perennial vegetation and at 2.0–2.5 m depth under continuous cropping indicating deep drainage and salt leaching since conversion to cropping. Total salt loads of 91–229 t ha−1 NaCl equivalent were measured for perennial vegetation and cropping, with salinity to ≥10 m depth that is not detected by shallow soil surveys. Groundwater salinity varied spatially from 910 to 2430 mS m−1 at 21 to 37 m depth (N = 5, whereas deeper groundwater was less saline (290 mS m−1 with use restricted to livestock and rural domestic supplies in this area. The Agricultural Production Systems Simulator (APSIM software package predicted deep drainage of 3.3–9.5 mm yr−1 (0.7–2.1% rainfall based on site records of grain yields, rainfall, salt leaching and soil properties. Predicted deep drainage was highly episodic, dependent on rainfall and antecedent, and over a 39 yr period was restricted mainly to the record wet winter of 1998. During the study period, groundwater levels were unresponsive to major rainfall events (70 and 190 mm total, and most piezometers at about 18 m depth remained dry. In this area, at this time, recharge negligible due to low rainfall and large potential evapotranspiration, transient hydrological conditionsafter changes

  3. Implications of deep drainage through saline clay for groundwater recharge and sustainable cropping in a semi-arid catchment, Australia

    Directory of Open Access Journals (Sweden)

    W. A. Timms

    2012-04-01

    Full Text Available The magnitude and timing of deep drainage and salt leaching through clay soils is a critical issue for dryland agriculture in semi-arid regions (<500 mm yr−1 rainfall, potential evapotranspiration >2000 mm yr−1 such as parts of Australia's Murray-Darling Basin (MDB. In this rare study, hydrogeological measurements and estimations of the historic water balance of crops grown on overlying Grey Vertosols were combined to estimate the contribution of deep drainage below crop roots to recharge and salinization of shallow groundwater. Soil sampling at two sites on the alluvial flood plain of the Lower Namoi catchment revealed significant peaks in chloride concentrations at 0.8–1.2 m depth under perennial vegetation and at 2.0–2.5 m depth under continuous cropping indicating deep drainage and salt leaching since conversion to cropping. Total salt loads of 91–229 t ha−1 NaCl equivalent were measured for perennial vegetation and cropping, with salinity to ≥ 10 m depth that was not detected by shallow soil surveys. Groundwater salinity varied spatially from 910 to 2430 mS m−1 at 21 to 37 m depth (N = 5, whereas deeper groundwater was less saline (290 mS m−1 with use restricted to livestock and rural domestic supplies in this area. The Agricultural Production Systems Simulator (APSIM software package predicted deep drainage of 3.3–9.5 mm yr−1 (0.7–2.1% rainfall based on site records of grain yields, rainfall, salt leaching and soil properties. Predicted deep drainage was highly episodic, dependent on rainfall and antecedent soil water content, and over a 39 yr period was restricted mainly to the record wet winter of 1998. During the study period, groundwater levels were unresponsive to major rainfall events (70 and 190 mm total, and most piezometers at about 18 m depth remained dry. In this area, at this time, recharge appears to be negligible due to low

  4. Topographic Controls on Spatial Patterns of Soil Texture and Moisture in a Semi-arid Montane Catchment with Aspect-Dependent Vegetation

    Science.gov (United States)

    Lehman, B. M.; Niemann, J. D.

    2008-12-01

    Soil moisture exerts significant control over the partitioning of latent and sensible energy fluxes, the magnitude of both vertical and lateral water fluxes, the physiological and water-use characteristics of vegetation, and nutrient cycling. Considerable progress has been made in determining how soil characteristics, topography, and vegetation influence spatial patterns of soil moisture in humid environments at the catchment, hillslope, and plant scales. However, understanding of the controls on soil moisture patterns beyond the plant scale in semi-arid environments remains more limited. This study examines the relationships between the spatial patterns of near surface soil moisture (upper 5 cm), terrain indices, and soil properties in a small, semi-arid, montane catchment. The 8 ha catchment, located in the Cache La Poudre River Canyon in north-central Colorado, has a total relief of 115 m and an average elevation of 2193 m. It is characterized by steep slopes and shallow, gravelly/sandy soils with scattered granite outcroppings. Depth to bedrock ranges from 0 m to greater than 1 m. Vegetation in the catchment is highly correlated with topographic aspect. In particular, north-facing hillslopes are predominately vegetated by ponderosa pines, while south-facing slopes are mostly vegetated by several shrub species. Soil samples were collected at a 30 m resolution to characterize soil texture and bulk density, and several datasets consisting of more than 300 point measurements of soil moisture were collected using time domain reflectometry (TDR) between Fall 2007 and Summer 2008 at a 15 m resolution. Results from soil textural analysis performed with sieving and the ASTM standard hydrometer method show that soil texture is finer on the north-facing hillslope than on the south-facing hillslope. Cos(aspect) is the best univariate predictor of silts, while slope is the best predictor of coarser fractions up to fine gravel. Bulk density increases with depth but shows no

  5. The influence of tillage on field scale water fluxes and maize yields in semi-arid environments: A case study of Potshini catchment, South Africa

    Science.gov (United States)

    Kosgei, J. R.; Jewitt, G. P. W.; Kongo, V. M.; Lorentz, S. A.

    Water is a limiting resource to crop production in arid and semi-arid lands (ASALs) and is responsible for substantial yield losses annually. These lands are often occupied by resource poor smallholder rainfed farmers who have little capacity to establish conventional irrigation infrastructure to mitigate recurrent droughts and dry spells. In situ water harvesting techniques in the form of conservation agriculture practices have been identified and promoted as measures that can improve soil water availability and thus enhance crop yields. Land use practices e.g. tillage influences mechanisms of lateral flow, infiltration, storage, redistribution and residence times of water at field scale. Such alterations in flow paths have not been adequately studied in ASALs where small perturbations at field scale upstream of a catchment may have significant effects downstream. Quantifying these fluxes enables better understanding of productive and non-productive water transition processes and thus to evaluate cropping and management systems. On this study the effects of tillage on water fluxes, soil physical properties and maize ( Zea mays L.) yields were examined at three sites in the Potshini catchment, South Africa. Measurements were made on plots under no-till ( NT) and conventional till ( CT) practices. Seasonal analysis indicated that nearly twice as much runoff was generated from CT treatments when compared to NT plots. However, this was not the case at the beginning of the season. The moisture content in the root zone was significantly higher in NT treatments. Maize yield was also higher in NT compared to CT plots.

  6. Assessment of vulnerability in karst aquifers using a quantitative integrated numerical model: catchment characterization and high resolution monitoring - Application to semi-arid regions- Lebanon.

    Science.gov (United States)

    Doummar, Joanna; Aoun, Michel; Andari, Fouad

    2016-04-01

    Karst aquifers are highly heterogeneous and characterized by a duality of recharge (concentrated; fast versus diffuse; slow) and a duality of flow which directly influences groundwater flow and spring responses. Given this heterogeneity in flow and infiltration, karst aquifers do not always obey standard hydraulic laws. Therefore the assessment of their vulnerability reveals to be challenging. Studies have shown that vulnerability of aquifers is highly governed by recharge to groundwater. On the other hand specific parameters appear to play a major role in the spatial and temporal distribution of infiltration on a karst system, thus greatly influencing the discharge rates observed at a karst spring, and consequently the vulnerability of a spring. This heterogeneity can only be depicted using an integrated numerical model to quantify recharge spatially and assess the spatial and temporal vulnerability of a catchment for contamination. In the framework of a three-year PEER NSF/USAID funded project, the vulnerability of a karst catchment in Lebanon is assessed quantitatively using a numerical approach. The aim of the project is also to refine actual evapotranspiration rates and spatial recharge distribution in a semi arid environment. For this purpose, a monitoring network was installed since July 2014 on two different pilot karst catchment (drained by Qachqouch Spring and Assal Spring) to collect high resolution data to be used in an integrated catchment numerical model with MIKE SHE, DHI including climate, unsaturated zone, and saturated zone. Catchment characterization essential for the model included geological mapping and karst features (e.g., dolines) survey as they contribute to fast flow. Tracer experiments were performed under different flow conditions (snow melt and low flow) to delineate the catchment area, reveal groundwater velocities and response to snowmelt events. An assessment of spring response after precipitation events allowed the estimation of the

  7. Scarce data in hydrology and hydrogeology: Estimation and modelling of groundwater recharge for a numerical groundwater flow model in a semi-arid to arid catchment

    Science.gov (United States)

    Gräbe, Agnes; Schulz, Stephan; Rödiger, Tino; Kolditz, Olaf

    2013-04-01

    Water resources are strongly limited in semi-arid to arid regions and groundwater constitutes often the only possibility for fresh water for the population and industry. An understanding of the hydrological processes and the estimation of magnitude of water balance parameters also includes the knowledge of processes of groundwater recharge. For the sustainable management of water resources, it is essential to estimate the potential groundwater recharge under the given climatic conditions. We would like to present the results of a hydrological model, which is based on the HRU- concept and intersected the parameters of climatic conditions, topography, geology, soil, vegetation and land use to calculate the groundwater recharge. This model was primarily developed for humid area applications and has now been adapted to the regional conditions in the semi-arid to arid region. It was quite a challenge to understand the hydrological processes in the semi-arid to arid study area and to implement those findings (e.g. routing [Schulz (in prep.)]) into the model structure. Thus we compared the existing approaches for groundwater recharge estimations (chloride mass balance [Marei et. al 2000], empirical relations such as rainfall and base flow-relation [Goldschmidt 1960; Guttman 2000; Hughes 2008; Issar 1993; Lerner 1990; De Vries et. al 2002]) with the results of our numerical model. References: De Vries, J. J., I. Simmers (2002): Groundwater recharge: an overview of processes and challenges. Hydrogeology Journal (2002) 10: 5-17. DOI 10.1007/s10040-001-0171-7. Guttman, J., 2000. Multi-Lateral Project B: Hydrogeology of the Eastern Aquifer in the Judea Hills and Jordan Valley. Mekorot Water Company, Report 468, p. 36. Hughes, A. G., M. M. Mansour, N. S. Robins (2008): Evaluation of distributed recharge in an upland semi-arid karst system: the West Bank Mountain Aquifer, Middle East. Hydrogeology Journal (2008) 16: 845-854. DOI 10.1007/s10040-008-0273-6 Issar, A. S. (1993

  8. Arid land irrigation in the United States Pacific Northwest for 2001 summarized for NHDPlus v2 catchments

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This spatial data set was created by the U.S. Geological Survey (USGS) to represent the area of arid land irrigation in the Pacific Northwest region of the United...

  9. Groundwater–surface water interactions, vegetation dependencies and implications for water resources management in the semi-arid Hailiutu River catchment, China – a synthesis

    Directory of Open Access Journals (Sweden)

    Y. Zhou

    2013-07-01

    Full Text Available During the last decades, large-scale land use changes took place in the Hailiutu River catchment, a semi-arid area in northwest China. These changes had significant impacts on the water resources in the area. Insights into groundwater and surface water interactions and vegetation-water dependencies help to understand these impacts and formulate sustainable water resources management policies. In this study, groundwater and surface water interactions were identified using the baseflow index at the catchment scale, and hydraulic and water temperature methods as well as event hydrograph separation techniques at the sub-catchment scale. The results show that almost 90% of the river discharge consists of groundwater. Vegetation dependencies on groundwater were analysed from the relationship between the Normalized Difference Vegetation Index (NDVI and groundwater depth at the catchment scale and along an ecohydrogeological cross-section, and by measuring the sap flow of different plants, soil water contents and groundwater levels at different research sites. The results show that all vegetation types, i.e. trees (willow (Salix matsudana and poplar (Populus simonii, bushes (salix – Salix psammophila, and agricultural crops (maize – Zea mays, depend largely on groundwater as the source for transpiration. The comparative analysis indicates that maize crops use the largest amount of water, followed by poplar trees, salix bushes, and willow trees. For sustainable water use with the objective of satisfying the water demand for socio-economical development and to prevent desertification and ecological impacts on streams, more water-use-efficient crops such as sorghum, barley or millet should be promoted to reduce the consumptive water use. Willow trees should be used as wind-breaks in croplands and along roads, and drought-resistant and less water-use intensive plants (for instance native bushes should be used to vegetate sand dunes.

  10. Afforestation using micro-catchment water harvesting system with microphytic crust treatment on semi-arid Loess Plateau: A preliminary result

    Institute of Scientific and Technical Information of China (English)

    YANG Xiao-hui; WANG Ke-qin; WANG Bin-rui; YU Chun-tang

    2005-01-01

    Water harvesting is one of main measures to solve water shortage resulting from less precipitation and erratically seasonal distribution in arid and semi-arid areas. Different types of anti-infiltration treatments including mechanical and chemical to micro-catchment and their runoff efficiencies had been reported. This paper, through 5 years experiment from 1992 to 1996, is aimed at studying the impacts of microcatchment water-harvesting system (MCWHS) with microphytic crust treatment on afforestation on semi-arid Loess Plateau. The results showed that after 3 years of crust inoculation, crust had covered majority of MCWHS and the function of water harvesting had also been demonstrated partially, there were significant difference in soil moisture of shallow soil layer in three typical spring stages between crust cover and control treatments (0.05 level), and about 0.9%-6.04% increase of monthly mean soil moisture within 1m soil layer in spring of late 3 years. The impact of severe spring drought can be alleviated effectively. In the meanwhile, as crust developed on the treated surface, there are significant differences (0.05 level) for tree height (H), diameter at breast height (DBH) and diameter at ground level (DGL) at the end of the study period (1996) with the increases by 22.38%, 17.34%, and 20.49% respectively compared with the control treatment. Microphytic crust, as one of biological infiltration-proof materials, may become the optimized option for revegetation in Chinese Great West Development Strategy due to its self-propagation, non-pollution to water qualities, long use duration and relatively cost effective. Further work should be focused on the selection of endemic crust species and their batch-culture in arid environment.

  11. Reliability of lumped hydrological modeling in a semi-arid mountainous catchment facing water-use changes

    Science.gov (United States)

    Hublart, Paul; Ruelland, Denis; García de Cortázar-Atauri, Inaki; Gascoin, Simon; Lhermitte, Stef; Ibacache, Antonio

    2016-09-01

    This paper explores the reliability of a hydrological modeling framework in a mesoscale (1515 km2) catchment of the dry Andes (30° S) where irrigation water use and snow sublimation represent a significant part of the annual water balance. To this end, a 20-year simulation period encompassing a wide range of climate and water-use conditions was selected to evaluate three types of integrated models referred to as A, B and C. These models share the same runoff generation and routing module but differ in their approach to snowmelt modeling and irrigation water use. Model A relies on a simple degree-day approach to estimate snowmelt rates and assumes that irrigation impacts can be neglected at the catchment scale. Model B ignores irrigation impacts just as Model A but uses an enhanced degree-day approach to account for the effects of net radiation and sublimation on melt rates. Model C relies on the same snowmelt routine as Model B but incorporates irrigation impacts on natural streamflow using a conceptual irrigation module. Overall, the reliability of probabilistic streamflow predictions was greatly improved with Model C, resulting in narrow uncertainty bands and reduced structural errors, notably during dry years. This model-based analysis also stressed the importance of considering sublimation in empirical snowmelt models used in the subtropics, and provided evidence that water abstractions from the unregulated river are impacting on the hydrological response of the system. This work also highlighted areas requiring additional research, including the need for a better conceptualization of runoff generation processes in the dry Andes.

  12. Determining the ecological water allocation in a hyper-arid catchment with increasing competition for water resources

    Science.gov (United States)

    Ling, Hongbo; Zhang, Pei; Xu, Hailiang; Zhang, Guangpeng

    2016-10-01

    Meeting ecological water requirement adequately plays a significant role in guaranteeing the stability of river basin ecosystems in arid lands. The amounts of water leaked through the riverbed and drawn by ecological brakes in Tarim River were ascertained. Based on data related to soil, hydrology, and vegetation of the river basin, the aims of this paper are to 1) analyse the variation in the size of soil particles and in hydraulic conductivity of four sections of the river; 2) calculate the amount of water that leaked from the riverbed and the percentage of ecological water requirement that can be guaranteed at different frequencies of water inflow; and 3) recommend - using a combination of particle size analysis, Darcy's Law, and GIS - the amount of water to be drawn from ecological brakes along both banks of the river for meeting ecological water requirement adequately. The results showed that 1) the size of soil particles in the riverbed ranged from 1.6 μm to 98.9 μm; 2) hydraulic conductivity followed the normal distribution from year to year but varied in spatial terms, that is across different section of the river; 3) riverbed leakage varied with water frequencies, being 11.36 × 108 m3, 10.62 × 108 m3, 9.84 × 108 m3, 9.32 × 108 m3, and 8.87 × 108 m3 at the frequencies of 10%, 25%, 50%, 75%, and 90%, respectively; 4) the distance over which the leakage contributed to meeting ecological water requirement in the south bank was greater than or equal to the distance in the north bank; and 5) water drawn from ecological brakes on the north bank exceeded that drawn from the brakes on the south bank by 10.89 × 108 m3-11.28 × 108 m3. Ecological water requirement of the desert riparian vegetation was met mainly from riverbed leakage in the south and by drawing from ecological brakes in the north. The present research not only offers a scientific method that could be used for developing suitable schemes for meeting ecological water requirement but also

  13. Comparison of meteorological forcing (WFDEI, AGRI4CAST) to in-situ observations in a semi arid catchment. The case of Merguellil in Tunisia.

    Science.gov (United States)

    Le Page, Michel; Gosset, Cindy; Oueslati, Ines; Calvez, Roger; Zribi, Mehrez; Lilli Chabaane, Zohra

    2015-04-01

    Meteorological forcing is essential to hydrological and hydro-geological modeling. In the case of the semi-arid catchment of Merguellil in Tunisia, long term time series are only available in the plain for a SYNOP station. Other meteorological stations have been installed since 2010. Therefore, this study aims at qualifying the reliability of the meteorological forcing necessary for an integrated model conception. We compare the meteorological data from 7 stations (sources: WMO and our own station), inside and around the Merguellil catchment, with daily gridded data at 25*25 km from AGRI4CAST and 50*50km from WFDEI. AGRI4CAST (Biaveti et al, 2008) is an interpolated dataset based on actual weather stations produced by the Joint Research Centre (JRC) for the Monitoring Agricultural Resources Unit (MARS). The WFDEI second version dataset (Weedon et al, 2014) has been generated using the same methodology as the widely used WATCH Forcing Data (WFD) by making use of the ERA-Interim reanalysis data. The studied meteorological variables are Rs, Tmoy, U2, P, RH and ET0, with the scores RMSE, bias and R pearson. Regarding the AGRI4CAST dataset, the scores are established over different periods according to variables based on stepping between the observed and interpolated data. The scores show good correlations between the observed temperatures, but with a spatial variability bound to the stations elevations. The moderate and interpolated radiations also show a good concordance indicating a good reliability. The R pearson score obtained for the values of relative humidity show a good correlation between the observations and the interpolations, however, the short periods of comparisons do not allow obtaining significant information and the RMSE and bias are important. Wind speed has an important negative bias for a majority of stations (positively for only one). Only one station shows concordances between the data. The study of the data indicates that we shall have to adjust

  14. Effectiveness of Conservation Measures in Reducing Runoff and Soil Loss Under Different Magnitude-Frequency Storms at Plot and Catchment Scales in the Semi-arid Agricultural Landscape.

    Science.gov (United States)

    Zhu, T X

    2016-03-01

    In this study, multi-year stormflow data collected at both catchment and plot scales on an event basis were used to evaluate the efficiency of conservation. At the catchment scale, soil loss from YDG, an agricultural catchment with no conservation measures, was compared with that from CZG, an agricultural catchment with an implementation of a range of conservation measures. With an increase of storm recurrence intervals in the order of 20 years, the mean event sediment yield was 639, 1721, 5779, 15191, 19627, and 47924 t/km(2) in YDG, and was 244, 767, 3077, 4679, 8388, and 15868 t/km(2) in CZG, which represented a reduction effectiveness of 61.8, 55.4, 46.7, 69.2, 57.2, and 66.8 %, respectively. Storm events with recurrence intervals greater than 2 years contributed about two-thirds of the total runoff and sediment in both YDG and CZG catchments. At the plot scale, soil loss from one cultivated slopeland was compared with that from five conservation plots. The mean event soil loss was 1622 t/km(2) on the cultivated slopeland, in comparison to 27.7 t/km(2) on the woodland plot, 213 t/km(2) on the grassland plot, 467 t/km(2) on the alfalfa plot, 236 t/km(2) on the terraceland plot, and 642 t/km(2) on the earthbank plot. Soil loss per unit area from all the plots was significantly less than that from the catchments for storms of all categories of recurrence intervals.

  15. Understanding key hydrological processes in a meso-scale semi-arid catchment in Tanzania by using a multi-method approach

    Science.gov (United States)

    Mul, M. L.; Savenije, H. H. G.; Uhlenbrook, S.

    2009-04-01

    Understanding hydrological processes in poorly or ungauged catchments is of utmost importance for the management of water resources. This paper shows that a high resolution time series of hydrological data (rainfall, evaporation and runoff) collected over a limited period of time (i.e. 1.5 years), can give a good picture of the hydrological processes occurring in a 25 km2 catchment in Tanzania (Vudee catchment). In addition, several techniques, incl. tracer and mapping studies, have been applied to identify flow paths and contribution from different sources. All this information was used for the development of a conceptual hydrological model. The conceptual model is based on the Lumped Elementary Watershed (LEW) concept, restructured for hourly time steps. An additional flux, representing the drainage into the neighbouring catchment, identified using a multi-method approach, increased the model performance significantly, particularly related to a recession curve occurring at high flows. This corroborates the assumption that there is water draining towards the neighbouring catchment. The model runs show that surface runoff only occurs during heavy rains or directly thereafter, which is consistent with results from hydrograph separation. Overall, the major part of the runoff is generated by groundwater. Moreover, the model shows that the unsaturated zone has a relatively large storage capacity. At the meso-scale, hydrological processes are governed by a sub-daily timescale. As a result, only a high resolution conceptual model is able to mimic the hydrological processes accurately. By applying the LEW model, incorporating the hydrological processes as observed in the catchment, a better understanding has been obtained of the dominant hydrological processes at this scale. This is a prerequisite for sustainable management of the water resources in a water scarce region.

  16. Effectiveness of Conservation Measures in Reducing Runoff and Soil Loss Under Different Magnitude-Frequency Storms at Plot and Catchment Scales in the Semi-arid Agricultural Landscape

    Science.gov (United States)

    Zhu, T. X.

    2016-03-01

    In this study, multi-year stormflow data collected at both catchment and plot scales on an event basis were used to evaluate the efficiency of conservation. At the catchment scale, soil loss from YDG, an agricultural catchment with no conservation measures, was compared with that from CZG, an agricultural catchment with an implementation of a range of conservation measures. With an increase of storm recurrence intervals in the order of 20 years, the mean event sediment yield was 639, 1721, 5779, 15191, 19627, and 47924 t/km2 in YDG, and was 244, 767, 3077, 4679, 8388, and 15868 t/km2 in CZG, which represented a reduction effectiveness of 61.8, 55.4, 46.7, 69.2, 57.2, and 66.8 %, respectively. Storm events with recurrence intervals greater than 2 years contributed about two-thirds of the total runoff and sediment in both YDG and CZG catchments. At the plot scale, soil loss from one cultivated slopeland was compared with that from five conservation plots. The mean event soil loss was 1622 t/km2 on the cultivated slopeland, in comparison to 27.7 t/km2 on the woodland plot, 213 t/km2 on the grassland plot, 467 t/km2 on the alfalfa plot, 236 t/km2 on the terraceland plot, and 642 t/km2 on the earthbank plot. Soil loss per unit area from all the plots was significantly less than that from the catchments for storms of all categories of recurrence intervals.

  17. Spatial rainfall variability and runoff response during an extreme event in a semi-arid catchment in the South Pare Mountains, Tanzania

    Directory of Open Access Journals (Sweden)

    M. L. Mul

    2008-09-01

    Full Text Available This paper describes an extreme flood event that occurred in the South Pare Mountains in northern Tanzania. A high spatial and temporal resolution data set was gathered in a previously ungauged catchment. This data was analysed using a multi-method approach, to gather information about the processes that resulted in the flood event. On 1 March 2006, extreme rainfall occurred in the Makanya catchment, (300 km2, where up to 100 mm were recorded in Bangalala village in only 3 h. Runoff was devastating, inundating large parts of the flood plain. The spatial variability of the rainfall during the event was very large, even in areas with the same altitude. The Vudee sub-catchment (25.8 km2 was in the centre of the rainfall event, receiving about 75 mm in 3 h divided over the two upstream tributaries: the Upper-Vudee and Ndolwa. The peak flow at the weir site has been determined using the slope-area method and gradually varied flow calculations, indicating a peak discharge of 32 m3 s−1. Rise and fall of the flood was very sharp, with the peak flow occurring just one hour after the peak of the rainfall. The flow receded to 1% of the maximum flow within 24 h. Hydrograph separation using hydrochemical parameters indicates that at the peak of the flow 50% was generated by direct surface runoff (also indicated by the large amount of sediments in the samples, whereas the recession originated from displaced groundwater (>90 %. The subsequent base flow in the river remained at 75 l s−1 for the rest of the season, which is substantially higher than the normal base flow observed during the previous rainy seasons (15 l s−1 indicating significant groundwater recharge during this extreme event.

  18. Accumulation of arsenic, lead, copper, and zinc, and synthesis of phytochelatins by indigenous plants of a mining impacted area.

    Science.gov (United States)

    Machado-Estrada, Blenda; Calderón, Jaqueline; Moreno-Sánchez, Rafael; Rodríguez-Zavala, José S

    2013-06-01

    Several native plants, able to grow in an unconfined mining impacted area that is now in close vicinity with urban areas, were evaluated for their ability to accumulate heavy metals. The main soil contaminants were As, Pb, Cu, and Zn. Sampling of the rhizospheric metal polluted soil showed that Euphorbia prostrata Aiton, Parthenium incanum Kunth, and Zinnia acerosa (DC.) A. Gray were able to grow in the presence of high amounts of mixtures of these elements. The plants accumulated the metals in the above ground parts and increased the synthesis of thiol molecules. E. prostrata showed the highest capacity for accumulation of the mixture of elements (588 μg g DW(-1)). Analysis of the thiol-molecules profile showed that these plants synthesized high amounts of long-chain phytochelatins, accompanied by low amounts of monothiol molecules, which may be related to their higher resistance to As and heavy metals. The three plants showed translocation factors from roots to leaves >1 for As, Pb, Cu, and Zn. Thus, by periodically removing aerial parts, these plants could be useful for the phytoremediation of semi-arid and arid mining impacted areas, in which metal hyper-accumulator plants are not able to grow.

  19. 77 FR 31353 - An Assessment of Potential Mining Impacts on Salmon Ecosystems of Bristol Bay, AK

    Science.gov (United States)

    2012-05-25

    ... AGENCY An Assessment of Potential Mining Impacts on Salmon Ecosystems of Bristol Bay, AK AGENCY... of Potential Mining Impacts on Salmon Ecosystems of Bristol Bay, Alaska'' (EPA-910-R-12-004a-d). The... draft ``An Assessment of Potential Mining Impacts on Salmon Ecosystems of Bristol Bay, Alaska''...

  20. 78 FR 34093 - An Assessment of Potential Mining Impacts on Salmon Ecosystems of Bristol Bay, Alaska

    Science.gov (United States)

    2013-06-06

    ... AGENCY An Assessment of Potential Mining Impacts on Salmon Ecosystems of Bristol Bay, Alaska AGENCY... the revised draft document titled, ``An Assessment of Potential Mining Impacts on Salmon Ecosystems of... Mining Impacts on Salmon Ecosystems of Bristol Bay, Alaska'' is available primarily via the Internet...

  1. A generic framework for the identification of hydrological droughts through the propagation of runoff generation mechanisms in semi-arid catchments

    Science.gov (United States)

    Paraskeuas, Ioannis; Vasiliades, Lampros; Loukas, Athanasios

    2015-04-01

    Hydrological drought characteristics have been extensively studied for the design of hydrotechnical projects and water resources planning and management during the last decade. Information on the magnitude and frequency of low flows is very important for hydrological drought analysis at operational level in public water supply systems. The objective of this study is to investigate the propagation of runoff generation mechanisms for the identification of hydrological droughts with the use of the HBV rainfall-runoff model. A methodological framework is developed based on the classical variable threshold method suitable for semiarid catchments where zero runoff occurs at summer months. The procedures included in the framework contain calibration and validation of the HBV model in lumped and semi-lumped modes based on the elevation zones of the study watershed for estimating the spatial distribution of rainfall into the runoff components for the whole watershed and each elevation zone. Then, the monthly variable threshold method is applied and the inter-event time and volume criterion was selected as a pooling method to derive independent deficits of the study variables. Two analyses are performed in the derived deficits. Firstly, a qualitative analysis is applied to identify the lags between the rainfall, the soil moisture, the runoff components (quick, intermediate and slow runoff) and the total discharge. The lag time between the occurrences in the different components is examined and analyzed through cross-correlation and event to event analyses. Secondly, a quantitative probabilistic analysis is applied in the derived deficit characteristics (volume and duration deficit) for each variable. The probabilistic analysis provides an overall characterization of the basin concerning the drought events and is orientated to long term drought management and infrastructure design such as reservoir management and regulation. Moreover, the drought events are being

  2. Evaluation of the SAFRAN-ISBA-RAPID hydrometeorological chain on a mountainous catchment in a semi-arid region. Case of the Rheraya (Marrakech, Morocco)

    Science.gov (United States)

    Szczypta, Camille; Gascoin, Simon; Habets, Florence; Saaidi, Amina; Berjamy, Brahim; Marchane, Ahmed; Boulet, Gilles; Hanich, Lahoucine; Jarlan, Lionel

    2015-04-01

    The water content of snow pack is an important resource for many watershed in semi-arid areas where downstream plains are dominated by irrigated agriculture. As part of the ANR Amethyst, this work is to develop, adapt and evaluate a hydro-meteorological forecasting chain for quantifying streamflows at the outlet of a mountainous watershed (Rheraya wadi, Marrakech region, Morocco), a pilot basin instrumented since 2003 as part of SudMed project. Two sets of atmospheric forcing were used: (1) The first was generated by spatializing meteorological data observed on 6 stations (Asni, Aremdt, Tachedert, Oukaimeden, Imskerbour and Neltner) using the semi-physical module Micromet (Liston and Elder, 2006) on the hydrological period September 2003 - August 2012; (2) the second is provided by the SAFRAN re-analysis, implemented by the Metoffice of Morocco (Casablanca, Morocco), during the period August 2004 - July 2008. These two sets were then used as inputs for the ISBA surface model, within the modeling platform SURFEX. Finally, runoff and drainage simulations derived from ISBA were forced into the hydrological model RAPID to predict streamflows. The flows predictions and the snow covered area (SCA) were compared respectively to the observations available for the 2003-2009 period and to the daily MODIS products of SCA. Despite time unsystematic lags and low biases on flow values, the initial results are encouraging due to topographical and hydro-complexity of the studied area. Despite a slight tendency to underestimate the SCA for the "Micromet" run and to over-estimate for the "Safran" run, SCA is well reproduced with a determination coefficient of r²=0.76 and r²=0.79, respectively. Given the complex topography of the basin, a sensitivity analysis to the size of the grid point (from 8 km to 250 m) was conducted. If the different simulated series of SCA are close from a resolution to another, streamflows simulations are, by contrast, highly sensitive to the resolution

  3. 78 FR 25266 - An Assessment of Potential Mining Impacts on Salmon Ecosystems of Bristol Bay, Alaska

    Science.gov (United States)

    2013-04-30

    ... AGENCY An Assessment of Potential Mining Impacts on Salmon Ecosystems of Bristol Bay, Alaska AGENCY... Assessment of Potential Mining Impacts on Salmon Ecosystems of Bristol Bay, Alaska'' (EPA-910-R-12-004Ba-c... on Salmon Ecosystems of Bristol Bay, Alaska'' is available primarily via the Internet on the...

  4. Assessment of arsenic speciation and bioaccessibility in mine-impacted materials

    Science.gov (United States)

    Mine-impacted materials were collected from Victoria, Australia and categorized into three source materials; tailings (n = 35), calcinated (n = 10) and grey slimes (n = 5). Arsenic (As) concentrations in these materials varied over several orders of magnitude (30-47,000 mg kg

  5. Understanding Hydrological Processes in an Ungauged Catchment in sub-Saharan Africa

    NARCIS (Netherlands)

    Mul, M.L.

    2009-01-01

    Ungauged catchments can be found in many parts of the world, but particularly in sub-Saharan Africa. Information collected in a gauged catchment and its regionalisation to ungauged areas is crucial for water resources assessment. Especially farmers in semi-arid areas are in need of such information.

  6. Metagenomic signatures of a tropical mining-impacted stream reveal complex microbial and metabolic networks.

    Science.gov (United States)

    Reis, Mariana P; Dias, Marcela F; Costa, Patrícia S; Ávila, Marcelo P; Leite, Laura R; de Araújo, Flávio M G; Salim, Anna C M; Bucciarelli-Rodriguez, Mônica; Oliveira, Guilherme; Chartone-Souza, Edmar; Nascimento, Andréa M A

    2016-10-01

    Bacteria from aquatic ecosystems significantly contribute to biogeochemical cycles, but details of their community structure in tropical mining-impacted environments remain unexplored. In this study, we analyzed a bacterial community from circumneutral-pH tropical stream sediment by 16S rRNA and shotgun deep sequencing. Carrapatos stream sediment, which has been exposed to metal stress due to gold and iron mining (21 [g Fe]/kg), revealed a diverse community, with predominance of Proteobacteria (39.4%), Bacteroidetes (12.2%), and Parcubacteria (11.4%). Among Proteobacteria, the most abundant reads were assigned to neutrophilic iron-oxidizing taxa, such as Gallionella, Sideroxydans, and Mariprofundus, which are involved in Fe cycling and harbor several metal resistance genes. Functional analysis revealed a large number of genes participating in nitrogen and methane metabolic pathways despite the low concentrations of inorganic nitrogen in the Carrapatos stream. Our findings provide important insights into bacterial community interactions in a mining-impacted environment.

  7. An appraisal of biological responses and network of environmental interactions in non-mining and mining impacted coastal waters

    Digital Repository Service at National Institute of Oceanography (India)

    Fernandes, C.E.G.; Malik, A; Jineesh, V.K.; Fernandes, S.O.; Das, A; Pandey, S.S.; Kanolkar, G.; Sujith, P.P.; Velip, D.; Shaikh, S.; Helekar, S.; Gonsalves, M.J.B.D.; Nair, S.; LokaBharathi, P.A

    iron brought from the hinterlands. We hypothesize that there could be a shift in biological response along with changes in network of interactions between environmental and biological variables in these mining and non-mining impacted regions, lying 160...

  8. Co-evolution of volcanic catchments in Japan

    Directory of Open Access Journals (Sweden)

    T. Yoshida

    2015-09-01

    Full Text Available Present day landscapes have evolved over time through interactions between the prevailing climates and geological settings. Understanding the linkage between spatial patterns of landforms, soils, and vegetation in landscapes and their hydrological response is critical to make quantitative predictions in ungaged basins. Catchment co-evolution is a theoretical framework that seeks to formulate hypotheses about the mechanisms and conditions that determine the historical development of catchments and how such evolution affects their hydrological response. In this study, we selected 14 volcanic catchments of different ages (from 0.225 to 82.2 Ma in Japan. We derived indices of landscape properties (drainage density as well as hydrological response (annual water balance, baseflow index, and flow duration curves and examined their relation with catchment age and climate (through the aridity index. We found significant correlation between drainage density and baseflow index with age, but not with climate. The age of the catchments was also significantly related to intra-annual flow variability. Younger catchments tend to have lower peak flows and higher low flows, while older catchments exhibit more flashy runoff. The decrease of baseflow with catchment age confirms previous studies that hypothesized that in volcanic landscapes the major flow pathways have changed over time, from deep groundwater flow to shallow subsurface flow. The drainage density of our catchments decreased with age, contrary to previous findings in similar volcanic catchments but of significant younger age than the ones explored here. In these younger catchments, an increase in drainage density with age was observed, and it was hypothesized that this was because of more landscape incision due to increasing near-surface lateral flow paths in more mature catchments. Our results suggests two hypotheses on the evolution of drainage density in matured catchments. One is that as

  9. Risk assessment test for lead bioaccessibility to waterfowl in mine-impacted soils

    Science.gov (United States)

    Furman, O.; Strawn, D.G.; Heinz, G.H.; Williams, B.

    2006-01-01

    Due to variations in soil physicochemical properties, species physiology, and contaminant speciation, Pb toxicity is difficult to evaluate without conducting in vivo dose-response studies. Such tests, however, are expensive and time consuming, making them impractical to use in assessment and management of contaminated environments. One possible alternative is to develop a physiologically based extraction test (PBET) that can be used to measure relative bioaccessibility. We developed and correlated a PBET designed to measure the bioaccessibility of Pb to waterfowl (W-PBET) in mine-impacted soils located in the Coeur d'Alene River Basin, Idaho. The W-PBET was also used to evaluate the impact of P amendments on Pb bioavailability. The W-PBET results were correlated to waterfowl-tissue Pb levels from a mallard duck [Anas platyrhynchos (L.)] feeding study. The W-PBET Pb concentrations were significantly less in the P-amended soils than in the unamended soils. Results from this study show that the W-PBET can be used to assess relative changes in Pb bioaccessibility to waterfowl in these mine-impacted soils, and therefore will be a valuable test to help manage and remediate contaminated soils.

  10. 77 FR 33213 - An Assessment of Potential Mining Impacts on Salmon Ecosystems of Bristol Bay, Alaska-Peer Review...

    Science.gov (United States)

    2012-06-05

    ... AGENCY An Assessment of Potential Mining Impacts on Salmon Ecosystems of Bristol Bay, Alaska--Peer Review... availability and public comment period. SUMMARY: EPA is announcing the peer review panel members assembled by... three week public comment period for the draft charge questions to be provided to the peer review...

  11. Dual assimilation of satellite soil moisture to improve flood prediction in ungauged catchments

    Science.gov (United States)

    This paper explores the use of active and passive satellite soil moisture products for improving stream flow prediction within 4 large (>5,000km2) semi-arid catchments. We use the probability distributed model (PDM) under a data-scarce scenario and aim at correcting two key controlling factors in th...

  12. Application of GIS-based SCS-CN method in West Bank catchments, Palestine

    Directory of Open Access Journals (Sweden)

    Sameer SHADEED

    2010-03-01

    Full Text Available Among the most basic challenges of hydrology are the prediction and quantification of catchment surface runoff. The runoff curve number (CN is a key factor in determining runoff in the SCS (Soil Conservation Service based hydrologic modeling method. The traditional SCS-CN method for calculating the composite curve number is very tedious and consumes a major portion of the hydrologic modeling time. Therefore, geographic information systems (GIS are now being used in combination with the SCS-CN method. This paper assesses the modeling of flow in West Bank catchments using the GIS-based SCS-CN method. The West Bank, Palestine, is characterized as an arid to semi-arid region with annual rainfall depths ranging between 100 mm in the vicinity of the Jordan River to 700 mm in the mountains extending across the central parts of the region. The estimated composite curve number for the entire West Bank is about 50 assuming dry conditions. This paper clearly demonstrates that the integration of GIS with the SCS-CN method provides a powerful tool for estimating runoff volumes in West Bank catchments, representing arid to semi-arid catchments of Palestine.

  13. Acidophilic algae isolated from mine-impacted environments and their roles in sustaining heterotrophic acidophiles

    Directory of Open Access Journals (Sweden)

    David Barrie Johnson

    2012-09-01

    Full Text Available Two acidophilic algae, identified as strains of Chlorella protothecoides var. acidicola and Euglena mutabilis, were isolated in pure culture from abandoned copper mines in Spain and Wales and grown in pH- and temperature-controlled bioreactors. The Chlorella isolate grew optimally at pH 2.5 and 30 ˚C, with a corresponding culture doubling time of 9 hours. The isolates displayed similar tolerance (10-50 mM to four transition metals tested. Growth of the algae in liquid media was paralleled with increasing concentrations of dissolved organic carbon (DOC. Glycolic acid was identified as a significant component (12- 14% of total DOC. Protracted incubation resulted in concentrations of glycolic acid declining in both cases, and glycolic acid added to a culture of Chlorella incubated in the dark was taken up by the alga (~100% within three days. Two monosaccharides were identified in cell-free liquors of each algal isolate: fructose and glucose (Chlorella, and mannitol and glucose (Euglena. These were rapidly metabolised by acidophilic heterotrophic bacteria (Acidiphilium and Acidobacterium spp. though only fructose was utilised by the more fastidious heterotroph Acidocella aromatica. The significance of algae in promoting the growth of iron- (and sulfate- reducing heterotrophic acidophiles that are important in remediating mine-impacted waters is discussed.

  14. Catchment conceptualisation for examining applicability of chloride mass balance method in an area of historical forest clearance

    OpenAIRE

    H. Guan; Love, A.; Simmons, C.T.; Ding, Z.; J. Hutson

    2009-01-01

    Among various approaches for estimating groundwater recharge, chloride mass balance (CMB) method is one of the most frequently used, in particular, for arid and semiarid regions. Widespread native vegetation clearance, common history in many areas globally, has changed land surface boundary condition, posing a question whether the current system has reached new chloride equilibrium for CMB application. To examine CMB applicability for catchments, conceptual catchment types of various chloride...

  15. Is aridity a high-order control on the hydro-geomorphic response of burned landscapes?

    Science.gov (United States)

    Sheridan, Gary; Van der Sant, Rene; Nyman, Petter; Lane, Patrick

    2015-04-01

    Fire results in hydro-geomorphic changes that are spatially variable and difficult to predict. In this study we compile 294 infiltration measurements, ten other soil, catchment runoff and erosion datasets, and a year of new data from 15 natural runoff plots across an aridity gradient from the eastern Victorian uplands in SE Australia. The results show that aridity (a function of the long term mean precipitation and net radiation) is associated with low post-fire infiltration capacities, increasing the chance of surface runoff, and strongly increasing the chance of debris flows. Runoff plots from the wettest site (aridity = 1.1) had an average runoff ratio of 0.3% compared with 33.6% for the most arid sites (aridity = 2.4). Post-fire debris flows were only observed in the more arid locations within the Victorian uplands, and resulted in erosion rates more than two orders of magnitude greater than non-debris flow processes. We therefore argue that in south eastern Australia aridity is a high-order control on the magnitude of post-wildfire hydro-geomorphic processes. The results from this Australian study may also help to provide insight into the landscape controls on post fire debris flows elsewhere. Aridity is a landscape-scale parameter that is mappable at a high resolution and therefore is a useful predictor of the spatial variability of the magnitude of post-fire hydro-geomorphic responses.

  16. Hydrological Impacts of Urbanization of Two Catchments in Harare, Zimbabwe

    Directory of Open Access Journals (Sweden)

    Webster Gumindoga

    2014-12-01

    Full Text Available By increased rural-urban migration in many African countries, the assessment of changes in catchment hydrologic responses due to urbanization is critical for water resource planning and management. This paper assesses hydrological impacts of urbanization on two medium-sized Zimbabwean catchments (Mukuvisi and Marimba for which changes in land cover by urbanization were determined through Landsat Thematic Mapper (TM images for the years 1986, 1994 and 2008. Impact assessments were done through hydrological modeling by a topographically driven rainfall-runoff model (TOPMODEL. A satellite remote sensing based ASTER 30 metre Digital Elevation Model (DEM was used to compute the Topographic Index distribution, which is a key input to the model. Results of land cover classification indicated that urban areas increased by more than 600 % in the Mukuvisi catchment and by more than 200 % in the Marimba catchment between 1986 and 2008. Woodlands decreased by more than 40% with a greater decrease in Marimba than Mukuvisi catchment. Simulations using TOPMODEL in Marimba and Mukuvisi catchments indicated streamflow increases of 84.8 % and 73.6 %, respectively, from 1980 to 2010. These increases coincided with decreases in woodlands and increases in urban areas for the same period. The use of satellite remote sensing data to observe urbanization trends in semi-arid catchments and to represent catchment land surface characteristics proved to be effective for rainfall-runoff modeling. Findings of this study are of relevance for many African cities, which are experiencing rapid urbanization but often lack planning and design.

  17. Geochemical control processes and potential sediment toxicity in a mine-impacted lake.

    Science.gov (United States)

    Adeleke, Solomon Babatunde; Svensson, Bo H; Yekta, Sepehr Shakeri; Adeleye, Michael Mayowa

    2016-03-01

    Geochemical parameters and major ion concentrations from sediments of a freshwater lake in the town of Åtvidaberg, southeastern, Sweden, were used to identify the geochemical processes that control the water chemistry. The lake sediments are anoxic, characterized by reduced sulfur and sulfidic minerals. The hypothesis tested is that in sulfidic-anaerobic contaminated sediments, the presence of redox potential changes creates a favorable condition for sulfide oxidation, resulting in the release of potentially toxic metals. The acid volatile sulfide (AVS) contents ranged from 5.5 μmol/g to 16 μmol/g of dry sediment. Comparison of total mine tailing metals (∑mine tailing metals) with simultaneously extracted metals (SEM) in sediments indicates that up to 20% of the ∑mine tailing metals are bound to the solid phase as AVS. Consequently, the AVS and SEM analysis classified all sediment samples as potentially toxic in terms of heavy metal concentrations (i.e., SEM to AVS ratio distribution > 1). Evaluation of hydrogeochemical data suggests that calcite dissolution, iron (III) oxyhydroxysulfate mineral jarosite (H-jarosite) precipitation, hematite precipitation, and siderite precipitation are the most prevailing geochemical processes that control the geochemical interactions between the water column and sediment in a mine-impacted lake. The geochemical processes were verified and quantified using a chemical equilibrium modeling program, Visual MINTEQ, Ver 3.1, beta. The identified geochemical processes create an environment in which the characteristics of sulfate-rich waters and acidic-iron produce the geochemical conditions for acid mine drainage and mobilization of toxic metals.

  18. An innovative carbonate coprecipitation process for the removal of zinc and manganese from mining impacted waters

    Science.gov (United States)

    Sibrell, P.L.; Chambers, M.A.; Deaguero, A.L.; Wildeman, T.R.; Reisman, D.J.

    2007-01-01

    Although mine drainage is usually thought of as acidic, there are many cases where the water is of neutral pH, but still contains metal species that can be harmful to human or aquatic animal health, such as manganese (Mn) and zinc (Zn). Typical treatment of mine drainage waters involves pH adjustment, but this often results in excessive sludge formation and removal of nontoxic species such as magnesium and calcium. Theoretical consideration of the stability of metal carbonate species suggests that the target metals could be removed from solution by coprecipitation with calcium carbonate. The U.S. Geological Survey has developed a limestone-based process for remediation of acid mine drainage that increases calcium carbonate saturation. This treatment could then be coupled with carbonate coprecipitation as an innovative method for removal of toxic metals from circumneutral mine drainage waters. The new process was termed the carbonate coprecipitation (CCP) process. The CCP process was tested at the laboratory scale using a synthetic mine water containing 50 mg/L each of Mn and Zn. Best results showed over 95% removal of both Mn and Zn in less than 2 h of contact in a limestone channel. The process was then tested on a sample of water from the Palmerton zinc superfund site, near Palmerton, Pennsylvania, containing over 300 mg/L Zn and 60 mg/L Mn. Treatment of this water resulted in removal of over 95% of the Zn and 40% of the Mn in the limestone channel configuration. Because of the potential economic advantages of the CCP process, further research is recommended for refinement of the process for the Palmerton water and for application to other mining impacted waters as well. ?? Mary Ann Liebert, Inc.

  19. Rainwater harvesting to alleviate water scarcity in dry conditions: A case study in Faria Catchment, Palestine

    Directory of Open Access Journals (Sweden)

    Sameer SHADEED

    2010-06-01

    Full Text Available In arid and semi-arid regions, the availability of adequate water of appropriate quality has become a limiting factor for development. This paper aims to evaluate the potential for rainwater harvesting in the arid to semi-arid Faria Catchment, in the West Bank, Palestine. Under current conditions, the supply-demand gap is increasing due to the increasing water demands of a growing population with hydrologically limited and uncertain supplies. By 2015, the gap is estimated to reach 4.5 × 106 m3. This study used the process-oriented and physically-based TRAIN-ZIN model to evaluate two different rainwater harvesting techniques during two rainfall events. The analysis shows that there is a theoretical potential for harvesting an additional 4 × 106 m3 of surface water over the entire catchment. Thus, it is essential to manage the potential available surface water supplies in the catchment to save water for dry periods when the supply-demand gap is comparatively high. Then a valuable contribution to bridging the supply-demand gap can be made.

  20. Evaluation of soil and water conservation measures in a semi-arid river basin in Tunisia using SWAT

    Science.gov (United States)

    The Merguellil catchment (Central Tunisia) is a typical Mediterranean semi-arid basin which suffers from regular water shortage aggravated by current droughts. During the recent decades the continuous construction of small and large dams and Soil and Water Conservation Works (i.e. Contour ridges) ha...

  1. Interaction of water components in the semi-arid Huasco and Limarí river basins, North Central Chile

    Directory of Open Access Journals (Sweden)

    G. Strauch

    2009-10-01

    Full Text Available For sustainable water resource management in semi-arid regions, sound information is required about interactions between the different components of the water system: rain/snow precipitation, surface/subsurface run-off, groundwater recharge. Exemplarily, the Huasco and Limarí river basins as water stressed river catchments have been studied by isotope and hydrochemical methods for (i the origin of water, (ii water quality, (iii relations of surface and groundwater.

    Applying the complex multi-isotopic and hydrochemical methodology to the water components of the Huasco and Limarí basins, a differentiation of water components concerning subsurface flow and river water along the catchment area and by anthropogenic impacts are detected. Sulphate and nitrate concentrations indicate remarkable input from mining and agricultural activities along the river catchment.

    The 2H-18O relations of river water and groundwater of both catchments point to the behaviour of river waters originated in an arid to semi-arid environment.

    Consequently, the groundwater from several production wells in the lower parts of the catchments is related to the rivers where the wells located, however, it can be distinguished from the river water. Using the hydrological water balance and the isotope mixing model, the interaction between surface and subsurface flows and river flow is estimated.

  2. Catchment-scale environmental controls of sediment-associated contaminant dispersal

    Science.gov (United States)

    Macklin, Mark

    2010-05-01

    Globally river sediment associated contaminants, most notably heavy metals, radionuclides, Polychlorinated Biphenyls (PCBs), Organochlorine pesticides (OCs) and phosphorous, constitute one the most significant long-term risks to ecosystems and human health. These can impact both urban and rural areas and, because of their prolonged environmental residence times, are major sources of secondary pollution if contaminated soil and sediment are disturbed by human activity or by natural processes such as water or wind erosion. River catchments are also the primary source of sediment-associated contaminants to the coastal zone, and to the ocean, and an understanding of the factors that control contaminated sediment fluxes and delivery in river systems is essential for effective environmental management and protection. In this paper the catchment-scale controls of sediment-associated contaminant dispersal are reviewed, including climate-related variations in flooding regime, land-use change, channel engineering, restoration and flood defence. Drawing on case studies from metal mining impacted catchments in Bolivia (Río Pilcomayo), Spain (Río Guadiamar), Romania (River Tisa) and the UK (River Swale) some improved methodologies for identifying, tracing, modelling and managing contaminated river sediments are proposed that could have more general application in similarly affected river systems worldwide.

  3. Water balance complexities in ephemeral catchments with different land uses: Insights from monitoring and distributed hydrologic modeling

    Science.gov (United States)

    Dean, J. F.; Camporese, M.; Webb, J. A.; Grover, S. P.; Dresel, P. E.; Daly, E.

    2016-06-01

    Although ephemeral catchments are widespread in arid and semiarid climates, the relationship of their water balance with climate, geology, topography, and land cover is poorly known. Here we use 4 years (2011-2014) of rainfall, streamflow, and groundwater level measurements to estimate the water balance components in two adjacent ephemeral catchments in south-eastern Australia, with one catchment planted with young eucalypts and the other dedicated to grazing pasture. To corroborate the interpretation of the observations, the physically based hydrological model CATHY was calibrated and validated against the data in the two catchments. The estimated water balances showed that despite a significant decline in groundwater level and greater evapotranspiration in the eucalypt catchment (104-119% of rainfall) compared with the pasture catchment (95-104% of rainfall), streamflow consistently accounted for 1-4% of rainfall in both catchments for the entire study period. Streamflow in the two catchments was mostly driven by the rainfall regime, particularly rainfall frequency (i.e., the number of rain days per year), while the downslope orientation of the plantation furrows also promoted runoff. With minimum calibration, the model was able to adequately reproduce the periods of flow in both catchments in all years. Although streamflow and groundwater levels were better reproduced in the pasture than in the plantation, model-computed water balance terms confirmed the estimates from the observations in both catchments. Overall, the interplay of climate, topography, and geology seems to overshadow the effect of land use in the study catchments, indicating that the management of ephemeral catchments remains highly challenging.

  4. Hydrological Catchment Similarity Assessment in Geum River Catchments, Korea

    Science.gov (United States)

    Ko, Ara; Park, Kisoon; Lee, Hyosang

    2013-04-01

    Similarity measure of catchments is essential for regionalization studies, which provide in depth analysis in hydrological response and flood estimations at ungauged catchments. However, this similarity measure is often biased to the selected catchments and is notclearly explained in hydrological sense. This study applied a type of hydrological similarity distance measure-Flood Estimation Handbook to 25 Geum river catchments, Korea. Three Catchment Characteristics, Area (A)-Annual precipitation (SAAR)-SCS Curve Number (CN), are used in Euclidian distance measures. Furthermore, six index of Flow Duration Curve (ILow:Q275/Q185, IDrought:Q355/Q185, IFlood:Qmax/Q185, IAbundant:Q95/Q185, IFloodDuration:Q10/Q355 and IRiverRegime:Qmax/Qmin) are applied to clustering analysis of SPSS. The catchments' grouping of hydrological similarity measures suggests three groups: H1 (Cheongseong, Gidae, Bukil, Oksan, Seockhwa, Habgang and Sangyeogyo), H2 (Cheongju, Guryong, Ugon, Boksu, Useong and Seokdong) and H3 (Muju, Yangganggyo and YongdamDam). The four catchments (Cheoncheon, Donghyang, DaecheongDam and Indong) are not grouped in this study. The clustering analysis of FDC provides four Groups; CFDC1 (Muju, YongdamDam, Yangganggyo, DaecheongDam, Cheongseong, Gidae, Seokhwa, Bukil, Habgang, Cheongju, Oksan, Yuseong and Guryong), CFDC2 (Cheoncheon, Donghyang, Boksu, Indong, Nonsan, Seokdong, Ugon, Simcheon, Useong and Sangyeogyo), CFDC3 (Songcheon) and CFDC4 (Tanbu). The six catchments (out of seven) of H1 are grouped in CFDC1, while Sangyeogyo is grouped in CFDC2. The four catchments (out of six) of H2 are also grouped in CFDC2, while Cheongju and Guryong are grouped in CFDC1. The catchments of H3 are categorized in CFDC1. The authors examine the results (H1, H2 and H3) of similarity measure based on catchment physical descriptors with results (CFDC1 and CFDC2) of clustering based on catchment hydrological response. The results of hydrological similarity measures are supported by

  5. Geochemical Processes Controlling the Generation and Environmental Impacts of Acid Mine Drainage in Semi Arid Conditions

    OpenAIRE

    Magombedze, Chris

    2006-01-01

    This study evaluates the geochemical processes that control the geochemistry of acid mine drainage in semi arid conditions. The central objective is to characterise and understand the evolution of acid mine drainage and its potential environmental impacts on the Mazowe River sub-catchment, in north east Zimbabwe. The work is based on a case study at three neighbouring metal sulphide mines, namely Trojan Nickel Mine, Mazowe Gold Mine and Iron Duke Pyrites.The methodology used in this research ...

  6. Predicting shifts in rainfall-runoff partitioning during multiyear drought: Roles of dry period and catchment characteristics

    Science.gov (United States)

    Saft, Margarita; Peel, Murray C.; Western, Andrew W.; Zhang, Lu

    2016-12-01

    While the majority of hydrological prediction methods assume that observed interannual variability explores the full range of catchment response dynamics, recent cases of prolonged climate drying suggest otherwise. During the ˜decade-long Millennium drought in south-eastern Australia significant shifts in hydrologic behavior were reported. Catchment rainfall-runoff partitioning changed from what was previously encountered during shorter droughts, with significantly less runoff than expected occurring in many catchments. In this article, we investigate the variability in the magnitude of shift in rainfall-runoff partitioning observed during the Millennium drought. We re-evaluate a large range of factors suggested to be responsible for the additional runoff reductions. Our results suggest that the shifts were mostly influenced by catchment characteristics related to predrought climate (aridity index and rainfall seasonality) and soil and groundwater storage dynamics (predrought interannual variability of groundwater storage and mean solum thickness). The shifts were amplified by seasonal rainfall changes during the drought (spring rainfall deficits). We discuss the physical mechanisms that are likely to be associated with these factors. Our results confirm that shifts in the annual rainfall-runoff relationship represent changes in internal catchment functioning, and emphasize the importance of cumulative multiyear changes in the catchment storage for runoff generation. Prolonged drying in some regions can be expected in the future, and our results provide an indication of which catchments characteristics are associated with catchments more susceptible to a shift in their runoff response behavior.

  7. The role of climatic and terrain attributes in estimating baseflow recession in tropical catchments

    Directory of Open Access Journals (Sweden)

    J. L. Peña-Arancibia

    2010-07-01

    Full Text Available The understanding of low flows in rivers is paramount more than ever as demand for water increases on a global scale. At the same time, limited streamflow data to investigate this phenomenon, particularly in the tropics, makes the provision of accurate estimations in ungauged areas an ongoing research need. This paper analysed the potential of climatic and terrain attributes of 167 tropical and sub-tropical unregulated catchments to predict baseflow recession rates. Climatic attributes included annual and seasonal indicators of rainfall and potential evapotranspiration. Terrain attributes included indicators of catchment shape, morphology, land cover, soils and geology. Stepwise regression was used to identify the best predictors for baseflow recession coefficients (kbf. Mean annual rainfall (MAR and aridity index (AI were found to explain 49% of the spatial variation of kbf. The rest of climatic indices plus average catchment slope (SLO and tree cover were also good predictors, but co-correlated with MAR. Catchment elongation (CE, a measure of catchment shape, was also found to be statistically significant, although weakly correlated. An analysis of clusters of catchments of smaller size, showed that in these areas, presumably with some similarity of soils and geology due to proximity, residuals of the regression could be explained by SLO and CE. The approach used provides a~potential alternative for kbf parameterisation in ungauged areas.

  8. Hydrological modeling of the semi-arid Andarax river basin in southern Spain

    DEFF Research Database (Denmark)

    Andersen, Flemming Hauge; Jensen, Karsten Høgh; Sandholt, Inge

      The 2,265 km2 Andarax river basin located in Southern Spain is one of the most arid regions in Europe with a mean annual precipitation of 250-350 mm, which mainly falls (70%) in autumn and winter. The terrain changes from sea level at the coast to more than 2,500 m in the Sierra Nevada Mountains....... Most of the precipitation falling in the mountainous areas, where the unit Triassic schists dominates, is converted into overland flow, which runs directly to the rivers. In areas with limestone most of the precipitation infiltrates and is subsequently routed through fractures before discharging...... availability in the delta region. Due to the high evapotranspiration in semi-arid or arid regions groundwater recharge can be as low as 1 % of the precipitation. Thus it is essential to accurately predict the seasonal and regional distribution of actual evapotranspiration (ET) within the river catchment...

  9. Evidence of Historical Mining Impacts on Saltmarshes from east Cornwall, UK

    Science.gov (United States)

    Iurian, Andra-Rada; Taylor, Alex; Millward, Geoff; Blake, William

    2016-04-01

    In landscapes with extensive mining history, saltmarshes can become sinks for contaminants that are vulnerable to release with sea-level rise and increased storminess. Given the prolonged residence time of heavy metals in the environment, data is urgently required to contextualise the impacts of past and present mining and pollution events and provide a baseline against which to assess Water Framework Directive (WFD) (2000/60/EC) compliance within an integrated catchment management framework. The geology of east Cornwall, UK (with intrusions of granite into the surrounding sedimentary rocks) was favourable for a prosperous mining industry, although large scale operations did not start until about 1830. Tin, cooper, lead and tungsten were the most important ores in the region. In order to quantify the spatial and temporal extent of contamination from past mining, sediment cores were collected from three saltmarshes, namely: Antony Marsh and Treluggan Marsh on the Lower Basin of River Lynher, and Port Eliot Marsh on the Lower Basin of River Tiddy. Core sections at 1 cm intervals were analysed by gamma-ray spectrometry for Pb-210, Ra-226, Cs-137 and Am-241, and the well-established Constant Rate of Supply (CRS) model was employed to derive Pb-210 geochronology with bomb-derived Cs-137 and Am-241 as independent chronological markers. The geochronological data provided the sedimentary accumulation and temporal context for the study. In terms of sediment quality with respect to mining pollution, core sections were analysed using Q-ICP-MS techniques and, additionally, WD-XRF instrumentation at Plymouth University. Measurements were performed for target elements that are normally associated with mining and smelting activities (e.g. Pb, Cu, Sn, Zn, Cr, Cd, etc.), and lithogenic elements (e.g. Fe, Al, Ti) that allow enrichment factors for the anthropogenically-derived elements to be determined. The grain size distribution was determined to identify storminess events and to

  10. The role of climatic and terrain attributes in estimating baseflow recession in tropical catchments

    Directory of Open Access Journals (Sweden)

    J. L. Peña-Arancibia

    2010-11-01

    Full Text Available The understanding of low flows in rivers is paramount more than ever as demand for water increases on a global scale. At the same time, limited streamflow data to investigate this phenomenon, particularly in the tropics, makes the provision of accurate estimations in ungauged areas an ongoing research need. This paper analysed the potential of climatic and terrain attributes of 167 tropical and sub-tropical unregulated catchments to predict baseflow recession rates. Daily streamflow data (m3 s–1 from the Global River Discharge Center (GRDC and a linear reservoir model were used to obtain baseflow recession coefficients (kbf for these catchments. Climatic attributes included annual and seasonal indicators of rainfall and potential evapotranspiration. Terrain attributes included indicators of catchment shape, morphology, land cover, soils and geology. Stepwise regression was used to identify the best predictors for baseflow recession coefficients. Mean annual rainfall (MAR and aridity index (AI were found to explain 49% of the spatial variation of kbf. The rest of climatic indices and the terrain indices average catchment slope (SLO and tree cover were also good predictors, but co-correlated with MAR. Catchment elongation (CE, a measure of catchment shape, was also found to be statistically significant, although weakly correlated. An analysis of clusters of catchments of smaller size, showed that in these areas, presumably with some similarity of soils and geology due to proximity, residuals of the regression could be explained by SLO and CE. The approach used provides a potential alternative for kbf parameterisation in ungauged catchments.

  11. Catchment areas for public transport

    DEFF Research Database (Denmark)

    Andersen, Jonas Lohmann Elkjær; Landex, Alex

    2008-01-01

    In the planning of public transport catchment areas of stops are often included to estimate potential number of travellers. There are different approaches to GIS-based catchment area analyses depending on the desired level of detail. The Circular Buffer approach is the fundamental, but also...... the simplest approach. The Service Area approach is based on searches in road networks and represents the actual feeder routes and is thereby a more detailed approach. The Service Area approach can be refined by adding additional resistance to certain points in the road network, e.g. stairways. Differences...... between the Circular Buffer approach and the Service Area approach are illustrated and a comparison between the sizes of the catchment areas is made. The strength of the Service Area approach and the impact on the catchment area when adding additional time resistance to crossing of stairways...

  12. On the operationalization of a spatially explicit evaluation of the complexity of land use trajectories in semi-arid Mediterranean agro-ecosystems

    DEFF Research Database (Denmark)

    Nainggolan, Doan

    This thesis aims to unpack the complexity of trajectories of land use change in semi-arid Mediterranean agro-ecosystems – illustrated using findings from the Torrealvilla catchment in south-eastern Spain. The research looks at multiple dimensions of land use change and addresses the past, present...

  13. Study on the change rule of groundwater level and its impacts on vegetation at arid mining area

    Institute of Scientific and Technical Information of China (English)

    LEI Shao-gang; BIAN Zheng-fu; ZHANG Ri-chen; LI Lin

    2007-01-01

    The shallow groundwater in Shendong mining area was broken because of large-scale underground mining activities. Selecting 32201 working-face as research area,analyzed the change rule of groundwater level and aquifer thickness under mining impact with a large number of water level observation data. Then, the impacts of groundwater level change on vegetation were analyzed by the relationship theory of arid area groundwater and vegetation. The results show that the aquifer structure and the water condition of supply flow and drainage are changed by the water proof mining. The groundwater level recovere only a little compared with the original groundwater level in two years. But the great change of groundwater level do not have notable influences on vegetation of this mining area, and further study indicates that there are certain conditions where groundwater level change impacted on vegetation. When the influence of groundwater level change was evaluated, the plant ecological water level, warning water level and spatial distribution character of original groundwater and mining-impacted groundwater-level change should be integrated.

  14. Requirements on catchment modelling for an optimized reservoir operation in water deficient regions

    Science.gov (United States)

    Froebrich, J.; Kirkby, M. J.; Reder, C.

    2002-12-01

    To provide long term water security in water deficient regions, the interaction of erosion, pollutant emission, the impact of irrigation areas, the characteristics of ephemeral streams and resulting water quality in reservoirs must be considered in water management plans. In many semiarid regions, reservoirs are the only source of water, the indispensable element required for human existence. By the year 2000 the world had built many small and > 45,000 large dams. In these reservoirs, water quality and quantity are affected both by climate change and catchment land use. Results of past projects indicate that the specific control of reservoirs can lead to a significant improvement of water quality, but reservoirs have already transformed the quantity and quality of surface waters in a remarkable manner. Reservoirs with their distinct behaviour as reactors could therefore be considered as key elements in semiarid and arid catchments, linking and transforming rivers and channels. Effective practical operation schemes require a thorough knowledge of spatial and temporal variation in water quality and quantity, and simulation models can be used to support the identification of most effective management potentials at catchment scale. We discuss here the particular requirements for water quality modelling at catchment scale in semiarid and arid regions. Results of reservoir water quality modelling are presented. The potential of catchment models like the PESERA model is demonstrated. Knowledge gaps, such as the consideration of ephemeral streams in catchment models, are addressed and fresh problem solving strategies are introduced. Erosion models like PESERA can provide important information on sediment transport and hence describing the carrier potentials for organic matter, heavy metals and pesticides from terrestrial areas into the water courses. The new EU-research project tempQsim will improve understanding of how the organic matter is transformed in river beds

  15. Comprehensive Management of the Heihe Catchment:A Success in Coupling Water-Ecological Setting with Local Economy

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    @@ In the arid regions of northwestern China, water is considered as the "life blood" of all living organisms and economic activities.An oasis will grow greener with ample supply of water, whereas the green will fade if water is in short supply. An inland river catchment constitutes an independent unit of ecological functions in which interactions and transformation occur between mountainous areas and plains, between oases and wastelands, and between ground surface runoffs and underground water. The sustainability of a catchment is deeply rooted in the coordination of hydrological, ecological and economical processes in a drainage basin.

  16. Aridity modulates N availability in arid and semiarid Mediterranean grasslands.

    Directory of Open Access Journals (Sweden)

    Manuel Delgado-Baquerizo

    Full Text Available While much is known about the factors that control each component of the terrestrial nitrogen (N cycle, it is less clear how these factors affect total N availability, the sum of organic and inorganic forms potentially available to microorganisms and plants. This is particularly true for N-poor ecosystems such as drylands, which are highly sensitive to climate change and desertification processes that can lead to the loss of soil nutrients such as N. We evaluated how different climatic, abiotic, plant and nutrient related factors correlate with N availability in semiarid Stipa tenacissima grasslands along a broad aridity gradient from Spain to Tunisia. Aridity had the strongest relationship with N availability, suggesting the importance of abiotic controls on the N cycle in drylands. Aridity appeared to modulate the effects of pH, plant cover and organic C (OC on N availability. Our results suggest that N transformation rates, which are largely driven by variations in soil moisture, are not the direct drivers of N availability in the studied grasslands. Rather, the strong relationship between aridity and N availability could be driven by indirect effects that operate over long time scales (decades to millennia, including both biotic (e.g. plant cover and abiotic (e.g. soil OC and pH. If these factors are in fact more important than short-term effects of precipitation on N transformation rates, then we might expect to observe a lagged decrease in N availability in response to increasing aridity. Nevertheless, our results suggest that the increase in aridity predicted with ongoing climate change will reduce N availability in the Mediterranean basin, impacting plant nutrient uptake and net primary production in semiarid grasslands throughout this region.

  17. 半干旱雨养农业区集雨补灌对马铃薯田水分运移的影响%Effects of Supplemental Irrigation Using Catchment Rainfall on Water Movement of Potato Field in Semi-arid Rainfed Areas

    Institute of Scientific and Technical Information of China (English)

    秦舒浩; 张俊莲; 王蒂; 刘震; 申鹏

    2011-01-01

    采用大田试验方法,研究集雨补灌对旱作马铃薯田水分运移规律和产量的影响。结果表明,对马铃薯有效的土壤水分主要分布在80 cm以上土层,苗期补灌45 mm处理水分利用效率(WUE)最高,且收获后不同土层中滞留的水分较少;在此基础上再增加补灌量,马铃薯产量增加不显著,WUE显著降低。集雨补灌增加了马铃薯棵间蒸发量(E)和植株蒸腾量(T),90 mm高额补灌处理在前、中期棵间蒸发量较高,收获后80 cm以下深层贮水量显著高于45 mm及45 mm以下补灌处理。45 mm与90 mm补灌处理植株蒸腾量差异不显著,马铃薯生长后期,苗期补灌与薯块膨大期补灌植株蒸腾量差异亦不显著;苗期45 mm补灌处理蒸腾量与蒸发量比率(T/E)比较高,其综合用水效率较高。%The effects of supplemental irrigation using catchment rainfall on water movement and production of rain-fed potato were studied by field experiments.The results showed that WUE of potato was higher in the supplemental irrigation treatment of 45 mm than other treatments at the seedling stage,and the storage of water in different soil depth was more least.With the increasing of irrigation amount,the production of potato was not increased significantly and WUE decreased significantly.The soil evaporation and transpiration among plants were increased by supplemental irrigation using catchment rainfall.The soil evaporation at prophase and metaphase state was higher in the supplemental irrigation treatment of 90 mm than 45 mm and under 45 mm treatment,at the same time,after harvest the water storage under 80 cm was higher significantly at the treatment of 90 mm.There was no difference of plant transpiration between 45 mm and 90 mm treatment,the same between the seedling and tuber expanding stage.WUE and IWUE were the highest under the 45 mm of irrigation at the seedling stage,because of the highest transpiration and evaporation rate.

  18. Assessment of Trace Metals in Soil, Vegetation and Rodents in Relation to Metal Mining Activities in an Arid Environment.

    Science.gov (United States)

    Méndez-Rodríguez, Lia C; Alvarez-Castañeda, Sergio Ticul

    2016-07-01

    Areas where abandoned metal-extraction mines are located contain large quantities of mineral wastes derived from environmentally unsafe mining practices. These wastes contain many pollutants, such as heavy metals, which could be released to the environment through weathering and leaching, hence becoming an important source of environmental metal pollution. This study evaluates differences in the levels of lead, iron, nickel, manganese, copper and cadmium in rodents sharing the same type of diet under different microhabitat use in arid areas with past mining activities. Samples of soil, roots, branches and seeds of Palo Adán (Fouquieria diguetii) and specimens of two rodent species (Chaetodipus arenarius and C. spinatus) were collected in areas with impact from past metal mining activities as well as from areas with no mining impact. Both rodent species mirrored nickel and iron levels in soil and seeds, as well as lead levels in soil; however, C. arenarius accumulated higher levels of manganese, copper and cadmium.

  19. New crops for arid lands.

    Science.gov (United States)

    Hinman, C W

    1984-09-28

    Five plants are described that could be grown commercially under arid conditions. Once the most valuable component has been obtained from each plant (rubber from guayule; seed oil from jojoba, buffalo gourd, and bladderpod; and resin from gumweed), the remaining material holds potential for useful products as well as fuel. It is difficult to realize the full potential of arid land plants, however, because of the complexities of developing the necessary agricultural and industrial infrastructure simultaneously. To do so, multicompany efforts or cooperative efforts between government and the private sector will be required.

  20. Technical Note: A comparison of model and empirical measures of catchment-scale effective energy and mass transfer

    Directory of Open Access Journals (Sweden)

    C. Rasmussen

    2013-09-01

    Full Text Available Recent work suggests that a coupled effective energy and mass transfer (EEMT term, which includes the energy associated with effective precipitation and primary production, may serve as a robust prediction parameter of critical zone structure and function. However, the models used to estimate EEMT have been solely based on long-term climatological data with little validation using direct empirical measures of energy, water, and carbon balances. Here we compare catchment-scale EEMT estimates generated using two distinct approaches: (1 EEMT modeled using the established methodology based on estimates of monthly effective precipitation and net primary production derived from climatological data, and (2 empirical catchment-scale EEMT estimated using data from 86 catchments of the Model Parameter Estimation Experiment (MOPEX and MOD17A3 annual net primary production (NPP product derived from Moderate Resolution Imaging Spectroradiometer (MODIS. Results indicated positive and significant linear correspondence (R2 = 0.75; P −2 yr−1. Modeled EEMT values were consistently greater than empirical measures of EEMT. Empirical catchment estimates of the energy associated with effective precipitation (EPPT were calculated using a mass balance approach that accounts for water losses to quick surface runoff not accounted for in the climatologically modeled EPPT. Similarly, local controls on primary production such as solar radiation and nutrient limitation were not explicitly included in the climatologically based estimates of energy associated with primary production (EBIO, whereas these were captured in the remotely sensed MODIS NPP data. These differences likely explain the greater estimate of modeled EEMT relative to the empirical measures. There was significant positive correlation between catchment aridity and the fraction of EEMT partitioned into EBIO (FBIO, with an increase in FBIO as a fraction of the total as aridity increases and percentage of

  1. Quantifying mountain block recharge by means of catchment-scale storage-discharge relationships

    Science.gov (United States)

    Ajami, Hoori; Troch, Peter A.; Maddock, Thomas, III; Meixner, Thomas; Eastoe, Chris

    2011-04-01

    Despite the importance of mountainous catchments for providing freshwater resources, especially in semi-arid regions, little is known about key hydrological processes such as mountain block recharge (MBR). Here we implement a data-based method informed by isotopic data to quantify MBR rates using recession flow analysis. We applied our hybrid method in a semi-arid sky island catchment in southern Arizona, United States. Sabino Creek is a 91 km2 catchment with its sources near the summit of the Santa Catalina Mountains northeast of Tucson. Southern Arizona's climate has two distinct wet seasons separated by prolonged dry periods. Winter frontal storms (November-March) provide about 50% of annual precipitation, and summers are dominated by monsoon convective storms from July to September. Isotope analyses of springs and surface water in the Sabino Creek catchment indicate that streamflow during dry periods is derived from groundwater storage in fractured bedrock. Storage-discharge relationships are derived from recession flow analysis to estimate changes in storage during wet periods. To provide reliable estimates, several corrections and improvements to classic base flow recession analysis are considered. These corrections and improvements include adaptive time stepping, data binning, and the choice of storage-discharge functions. Our analysis shows that (1) incorporating adaptive time steps to correct for streamflow measurement errors improves the coefficient of determination, (2) the quantile method is best for streamflow data binning, (3) the choice of the regression model is critical when the stage-discharge function is used to predict changes in bedrock storage beyond the maximum observed flow in the catchment, and (4) the use of daily or night-time hourly streamflow does not affect the form of the storage-discharge relationship but will impact MBR estimates because of differences in the observed range of streamflow in each series.

  2. A Synoptic Climatology of Heavy Rain Events in the Lake Eyre and Lake Frome Catchments

    Directory of Open Access Journals (Sweden)

    Michael John Pook

    2014-11-01

    Full Text Available The rare occasions when Lake Eyre in central, southern Australia fills with water excite great interest and produce major ecological responses. The filling of other smaller lakes such as Lake Frome, have less impact but can contribute important information about the current and past climates of these arid regions. Here, the dominant synoptic systems responsible for heavy rainfall over the catchments of Lake Eyre and Lake Frome since 1950 are identified and compared. Heavy rain events are defined as those where the mean catchment rainfall for 24 hours reaches a prescribed threshold. There were 25 such daily events at Lake Eyre and 28 in the Lake Frome catchment. The combination of a monsoon trough at mean sea level and a geopotential trough in the mid-troposphere was found to be the synoptic system responsible for the majority of the heavy rain events affecting Lake Eyre and one in five of the events at Lake Frome. Complex fronts where subtropical interactions occurred with Southern Ocean fronts also contributed over 20% of the heavy rainfall events in the Frome catchment. Surface troughs without upper air support were found to be associated with 10% or fewer of events in each catchment, indicating that mean sea level pressure analyses alone do not adequately capture the complexity of the heavy rainfall events. At least 80% of the heavy rain events across both catchments occurred when the Southern Oscillation Index (SOI was in its positive phase, and for Lake Frome, the SOI exceeded +10 on 60% of occasions, suggesting that the background atmospheric state in the Pacific Ocean was tilted towards La Niña. Hydrological modeling of the catchments suggests that the 12-month running mean of the soil moisture in a sub-surface layer provides a low frequency filter of the precipitation and matches measured lake levels relatively well.

  3. Microbial diversity in uranium mining-impacted soils as revealed by high-density 16S microarray and clone library.

    Science.gov (United States)

    Rastogi, Gurdeep; Osman, Shariff; Vaishampayan, Parag A; Andersen, Gary L; Stetler, Larry D; Sani, Rajesh K

    2010-01-01

    Microbial diversity was characterized in mining-impacted soils collected from two abandoned uranium mine sites, the Edgemont and the North Cave Hills, South Dakota, using a high-density 16S microarray (PhyloChip) and clone libraries. Characterization of the elemental compositions of soils by X-ray fluorescence spectroscopy revealed higher metal contamination including uranium at the Edgemont than at the North Cave Hills mine site. Microarray data demonstrated extensive phylogenetic diversity in soils and confirmed nearly all clone-detected taxonomic levels. Additionally, the microarray exhibited greater diversity than clone libraries at each taxonomic level at both the mine sites. Interestingly, the PhyloChip detected the largest number of taxa in Proteobacteria phylum for both the mine sites. However, clone libraries detected Acidobacteria and Bacteroidetes as the most numerically abundant phyla in the Edgemont and North Cave Hills mine sites, respectively. Several 16S rDNA signatures found in both the microarrays and clone libraries displayed sequence similarities with yet-uncultured bacteria representing a hitherto unidentified diversity. Results from this study demonstrated that highly diverse microbial populations were present in these uranium mine sites. Diversity indices indicated that microbial communities at the North Cave Hills mine site were much more diverse than those at the Edgemont mine site.

  4. Mycorrhiza and PGPB modulate maize biomass, nutrient uptake and metabolic pathways in maize grown in mining-impacted soil.

    Science.gov (United States)

    Dhawi, Faten; Datta, Rupali; Ramakrishna, Wusirika

    2015-12-01

    Abiotic stress factors including poor nutrient content and heavy metal contamination in soil, can limit plant growth and productivity. The main goal of our study was to evaluate element uptake, biomass and metabolic responses in maize roots growing in mining-impacted soil with the combination of arbuscular mycorrhiza (My) and plant growth promoting bacteria (PGPB/B). Maize plants subjected to PGPB, My and combined treatments showed a significant increase in biomass and uptake of some elements in shoot and root. Metabolite analysis identified 110 compounds that were affected ≥2-fold compared to control, with 69 metabolites upregulated in the My group, 53 metabolites in the My+B group and 47 metabolites in B group. Pathway analysis showed that impact on glyoxylate and dicarboxylate metabolism was common between My and My+B groups, whereas PGPB group showed a unique effect on fatty acid biosynthesis with significant increase in palmitic acid and stearic acid. Differential regulation of some metabolites by mycorrhizal treatment correlated with root biomass while PGPB regulated metabolites correlated with biomass increase in shoot. Overall, the combination of rhizospheric microorganisms used in our study significantly increased maize nutrient uptake and growth relative to control. The changes in metabolic pathways identified during the symbiotic interaction will improve our understanding of mechanisms involved in rhizospheric interactions that are responsible for increased growth and nutrient uptake in crop plants.

  5. Element mobility during pyrite weathering: implications for acid and heavy metal pollution at mining-impacted sites

    Science.gov (United States)

    Lu, Long; Wang, Rucheng; Chen, Fanrong; Xue, Jiyue; Zhang, Peihua; Lu, Jianjun

    2005-11-01

    Based on back scattered electron images and electron micro-probe analysis results, four alteration layers, including a transition layer, a reticulated ferric oxide layer, a nubby ferric oxide layer and a cellular ferric oxide layer, were identified in the naturally weathering products of pyrite. These layers represent a progressive alteration sequence of pyrite under weathering conditions. The cellular ferric oxide layer correlates with the strongest weathering phase and results from the dissolution of nubby ferric oxide by acidic porewater. Leaching coefficient was introduced to better express the response of element mobility to the degree of pyrite weathering. Its variation shows that the mobility of S, Co and Bi is stronger than As, Cu and Zn. Sulfur in pyrite is oxidized to sulfuric acid and sulfate that are basically released into to porewater, and heavy metals Co and Bi are evidently released by acid dissolution. As, Cu and Zn are enriched in ferric oxide by adsorption and by co-precipitation, but they would re-release to the environment via desorption or dissolution when porewater pH becomes low enough. Consequently, Co, Bi, As, Cu and Zn may pose a substantial impact on water quality. Considering that metal mobility and its concentration in mine waste are two important factors influencing heavy metal pollution at mining-impacted sites, Bi and Co are more important pollutants in this case.

  6. Hydrological forecasting in catchments with glaciers

    OpenAIRE

    Nahat, Angèle

    2015-01-01

    The runoff forecast is crucial in Norway because the country bases most of its electricity from hydropower. The hydrological model has thus been improved for years in order to foresee the runoff in the best possible way. In Norway, there are many catchments with extensive water storage: glaciers. Those catchments represent a significant part of the catchments where hydropower is produced. Therefore knowing the right amount of outflow from a catchment with glaciers is essential but more challe...

  7. Stability measures in arid ecosystems

    Science.gov (United States)

    Nosshi, M. I.; Brunsell, N. A.; Koerner, S.

    2015-12-01

    Stability, the capacity of ecosystems to persist in the face of change, has proven its relevance as a fundamental component of ecological theory. Here, we would like to explore meaningful and quantifiable metrics to define stability, with a focus on highly variable arid and semi-arid savanna ecosystems. Recognizing the importance of a characteristic timescale to any definition of stability, our metrics will be focused scales from annual to multi-annual, capturing different aspects of stability. Our three measures of stability, in increasing order of temporal scale, are: (1) Ecosystem resistance, quantified as the degree to which the system maintains its mean state in response to a perturbation (drought), based on inter-annual variability in Normalized Difference Vegetation Index (NDVI). (2) An optimization approach, relevant to arid systems with pulse dynamics, that models vegetation structure and function based on a trade off between the ability to respond to resource availability and avoid stress. (3) Community resilience, measured as species turnover rate (β diversity). Understanding the nature of stability in structurally-diverse arid ecosystems, which are highly variable, yields theoretical insight which has practical implications.

  8. Water balance modeling of Upper Blue Nile catchments using a top-down approach

    Directory of Open Access Journals (Sweden)

    S. Tekleab

    2011-07-01

    Full Text Available The water balances of twenty catchments in the Upper Blue Nile basin have been analyzed using a top-down modeling approach based on Budyko's hypotheses. The objective of this study is to obtain better understanding of water balance dynamics of upper Blue Nile catchments on annual and monthly time scales and on a spatial scale of meso scale to large scale. The water balance analysis using a Budyko-type curve at annual scale reveals that the aridity index does not exert a first order control in most of the catchments. This implies the need to increase model complexity to monthly time scale to include the effects of seasonal soil moisture dynamics. The dynamic water balance model used in this study predicts the direct runoff and other processes based on the limit concept; i.e. for dry environments since rainfall amount is small, the aridity index approaches to infinity or equivalently evaporation approaches rainfall and for wet environments where the rainfall amount is large, the aridity index approaches to zero and actual evaporation approaches the potential evaporation. The uncertainty of model parameters has been assessed using the GLUE (Generalized Likelihood Uncertainty Estimation methodology. The results show that the majority of the parameters are reasonably well identifiable. However, the baseflow recession constant was poorly identifiable. Parameter uncertainty and model structural errors could be the reason for the poorly identifiable parameter. Moreover, a multi-objective model calibration strategy has been employed to emphasize the different aspects of the hydrographs on low and high flows.

    The model has been calibrated and validated against observed streamflow time series and it shows good performance for the twenty study catchments in the upper Blue Nile. During the calibration period (1995–2000 the Nash and Sutcliffe efficiency (E NS for monthly flow prediction varied between 0.52 to 0.93 (dominated by

  9. Annual plants in arid and semi-arid desert regions

    Institute of Scientific and Technical Information of China (English)

    Xuehua LI; Xiaolan LI; Deming JIANG; Zhimin LIU; Qinghe YU

    2008-01-01

    Annual plants are the main vegetation in arid and semi-arid desert regions.Because of their unique traits,they are the optimal experimental subjects for eco-logical studies.In this article,we summarize annual plants' seed germination strategies,seedling adaptability mechanism to environments,seed dispersal,and soil seed banks.We also discuss the biotic and abiotic factors affecting the composition and dynamics of annual plant populations and communities.Because annual plants have important ecological functions in desert vegetation systems,this study on annual plants will be of great bene-fit to the conservation and restoration of desert ecosys-tems,the rational utilization of resources,and the sustainable development of desert regions.

  10. Stream-Sediment Geochemistry in Mining-Impacted Drainages of the Yankee Fork of the Salmon River, Custer County, Idaho

    Science.gov (United States)

    Frost, Thomas P.; Box, Stephen E.

    2009-01-01

    This reconnaissance study was undertaken at the request of the USDA Forest Service, Region 4, to assess the geochemistry, in particular the mercury and selenium contents, of mining-impacted sediments in the Yankee Fork of the Salmon River in Custer County Idaho. The Yankee Fork has been the site of hard-rock and placer mining, primarily for gold and silver, starting in the 1880s. Major dredge placer mining from the 1930s to 1950s in the Yankee Fork disturbed about a 10-kilometer reach. Mercury was commonly used in early hard-rock mining and placer operations for amalgamation and recovery of gold. During the late 1970s, feasibility studies were done on cyanide-heap leach recovery of gold from low-grade ores of the Sunbeam and related deposits. In the mid-1990s a major open-pit bulk-vat leach operation was started at the Grouse Creek Mine. This operation shut down when gold values proved to be lower than expected. Mercury in stream sediments in the Yankee Fork ranges from below 0.02 ppm to 7 ppm, with the highest values associated with old mill locations and lode and placer mines. Selenium ranges from below the detection limit for this study of 0.2 ppm to 4 ppm in Yankee Fork sediment samples. The generally elevated selenium content in the sediment samples reflect the generally high selenium contents in the volcanic rocks that underlie the Yankee Fork and the presence of gold and silver selenides in some of the veins that were exploited in the early phases of mining.

  11. Downscaled TRMM Rainfall Time-Series for Catchment Hydrology Applications

    Science.gov (United States)

    Tarnavsky, E.; Mulligan, M.

    2009-04-01

    Hydrology in semi-arid regions is controlled, to a large extent, by the spatial and temporal distribution of rainfall defined in terms of rainfall depth and intensity. Thus, appropriate representation of the space-time variability of rainfall is essential for catchment-scale hydrological models applied in semi-arid regions. While spaceborne platforms equipped with remote sensing instruments provide information on a range of variables for hydrological modelling, including rainfall, the necessary spatial and temporal detail is rarely obtained from a single dataset. This paper presents a new dynamic model of dryland hydrology, DryMOD, which makes best use of free, public-domain remote sensing data for representation of key variables with a particular focus on (a) simulation of spatial rainfall fields and (b) the hydrological response to rainfall, particularly in terms of rainfall-runoff partitioning. In DryMOD, rainfall is simulated using a novel approach combining 1-km spatial detail from a climatology derived from the TRMM 2B31 dataset (mean monthly rainfall) and 3-hourly temporal detail from time-series derived from the 0.25-degree gridded TRMM 3B42 dataset (rainfall intensity). This allows for rainfall simulation at the hourly time step, as well as accumulation of infiltration, recharge, and runoff at the monthly time step. In combination with temperature, topography, and soil data, rainfall-runoff and soil moisture dynamics are simulated over large dryland regions. In order to investigate the hydrological response to rainfall and variable catchment characteristics, the model is applied to two very different catchments in the drylands of North and West Africa. The results of the study demonstrate the use of remote sensing-based estimates of precipitation intensity and volume for the simulation of critical hydrological parameters. The model allows for better spatial planning of water harvesting activities, as well as for optimisation of agricultural activities

  12. The recharge process in alluvial strip aquifers in arid Namibia and implication for artificial recharge

    Science.gov (United States)

    Sarma, Diganta; Xu, Yongxin

    2016-10-01

    Alluvial strip aquifers associated with ephemeral rivers are important groundwater supply sources that sustain numerous settlements and ecological systems in arid Namibia. More than 70 % of the population in the nation's western and southern regions depend on alluvial aquifers associated with ephemeral rivers. Under natural conditions, recharge occurs through infiltration during flood events. Due to the characteristic spatial and temporal variability of rainfall in arid regions, recharge is irregular making the aquifers challenging to manage sustainably and they are often overexploited. This condition is likely to become more acute with increasing water demand and climate change, and artificial recharge has been projected as the apparent means of increasing reliability of supply. The article explores, through a case study and numerical simulation, the processes controlling infiltration, significance of surface water and groundwater losses, and possible artificial recharge options. It is concluded that recharge processes in arid alluvial aquifers differ significantly from those processes in subhumid systems and viability of artificial recharge requires assessment through an understanding of the natural recharge process and losses from the aquifer. It is also established that in arid-region catchments, infiltration through the streambed occurs at rates dependent on factors such as antecedent conditions, flow rate, flow duration, channel morphology, and sediment texture and composition. The study provides an important reference for sustainable management of alluvial aquifer systems in similar regions.

  13. Water balance modeling of Upper Blue Nile catchments using a top-down approach

    Directory of Open Access Journals (Sweden)

    S. Tekleab

    2010-09-01

    Full Text Available The hydrological behavior and functioning of twenty catchments in the Upper Blue Nile basin have been analyzed using a top-down modeling approach that is based on Budyko's hypotheses. The objective is to obtain better understanding of catchment response for prediction in ungauged catchments. The water balance analysis using Budyko-type curve at annual scale reveals that the aridity index does not exert a first order control in most of the catchments. This implies the need to increase model complexity to a monthly time scale to include the effects of seasonal soil moisture dynamics. The dynamic water balance model used in this study predicts the direct runoff and other processes based on limit concept. The uncertainty of model parameters has been assessed using the GLUE (Generalized Likelihood Uncertainty Estimation. The results show that the majority of the parameters are reasonably well identifiable. Moreover, a multi-objective model calibration strategy has been employed within the GLUE framework to emphasize the different aspects of the hydrographs on low and high flows. The model has been calibrated and validated against observed streamflow time series and it shows good performance for the twenty catchments of the upper Blue Nile. During the calibration period (1995–2000 the Nash and Sutcliffe coefficient of efficiency for monthly flow prediction varied between 0.52 to 0.93 during high flows, while it varied between 0.32 to 0.90 during low flows (logarithms of flow series. The model is parsimonious and it is suggested that the resulting parameters can be used to predict monthly stream flows in the ungauged catchments of the Upper Blue Nile basin, which accounts about 60% of total Nile basin flow.

  14. Do weirs affect the physical and geochemical mobility of toxic metals in mining-impacted floodplain sediments?

    Science.gov (United States)

    Bulcock, Amelia; Coleman, Alexandra; Whitfield, Elizabeth; Andres Lopez-Tarazon, Jose; Byrne, Patrick; Whitfield, Greg

    2015-04-01

    Weirs are common river structures designed to modify river channel hydraulics and hydrology for purposes of navigation, flood defence, irrigation and hydrometry. By design, weirs constrain natural flow processes and affect sediment flux and river channel forms leading to homogenous river habitats and reduced biodiversity. The recent movement towards catchment-wide river restoration, driven by the EU Water Framework Directive, has recognised weirs as a barrier to good ecological status. However, the removal of weirs to achieve more 'natural' river channels and flow processes is inevitably followed by a period of adjustment to the new flow regime and sediment flux. This period of adjustment can have knock-on effects that may increase flood risk, sedimentation and erosion until the river reaches a state of geomorphological equilibrium. Many catchments in the UK contain a legacy of toxic metals in floodplain sediments due to historic metal mining activities. The consequences of weir removal in these catchments may be to introduce 'stored' mine wastes into the river system with severe implications for water quality and biodiversity. The purpose of this study is to investigate the potential impact of a weir on the physical and geochemical mobilisation of mine wastes in the formerly mined River Twymyn catchment, Wales. Our initial investigations have shown floodplain and riverbed sediments to be grossly contaminated (up to 15,500 mg/kg Pb) compared to soil from a pre-mining Holocene terrace (180 mg/kg Pb). Geomorphological investigations also suggest that weir removal will re-establish more dynamic river channel processes resulting in lateral migration of the channel and erosion of contaminated floodplain sediments. These data will be used as a baseline for more detailed investigations of the potential impact of weirs on the physical and geochemical mobilisation of contaminated sediments. We have two specific objectives. (1) Geomorphological assessments will use unmanned

  15. Neighbourhood catchments: a new approach for achieving ownership and change in catchment and stream management.

    Science.gov (United States)

    Carroll, C; Rohde, K; Millar, G; Dougall, C; Stevens, S; Ritchie, R; Lewis, S

    2002-01-01

    The Neighbourhood Catchment approach integrates land and stream management practices at a property and through to a local catchment scale, links production and environmental goals, and is a building block to achieve ownership and change at a sub-catchment scale and larger. Research conducted in two 'focus' Neighbourhood Catchments has shown that land management practices that retain >30% soil cover reduce sediment movement to streams. The Neighbourhood Catchment approach engages both early and cautious adopters, and enables continuous improvement of resource management to take place, and be recorded at an individual property and local catchment scale.

  16. Calcul de la pluie sur le bassin versant du lac Titicaca pendant l'Holocène. Computation of the rainfall on Lake Titicaca catchment during the Holocene

    Science.gov (United States)

    Talbi, Amal; Coudrain, Anne; Ribstein, Pierre; Pouyaud, Bernard

    1999-08-01

    The water levels of a lake situated in an endorheic catchment make it possible to calculate the associated rainfall rate on the basis of the water balance over the whole catchment. Evolution during the Holocene of water levels in Lake Titicaca (Bolivia), previously published, shows that in the most arid period, between 8 000 yr and 4 000 yr BP, the average level was 50 m lower than today. The calculated rainfall associated with this low level is 635 ± 50 mm·yr -1 i.e. about 18 % lower than the present amount.

  17. Mitigating Climate Change in the Arid Lands of Namibia

    Science.gov (United States)

    Schneider, Martin B.; Sorensen, Marten

    2014-05-01

    Mitigating Climate Change in the Arid Lands of Namibia Namibia is the most arid country south of the Sahara, with scarce rainfall and perennial rivers only at its borders, > 80% of the area relies solely on groundwater. This has had devastating economic effects limiting opportunities for sustainable rural livelihoods that keep the population majority living below the World Bank poverty line (IFAD, 2013). A primary example of climatic variability which affects agrarian productivity is increased bush encroachment of Namibia's arid grazing land. The result has been a severe biodiversity loss, increased desertification and diminished water-use efficiency and underground water tables. Given these factors, Namibia's arid lands provide a unique opportunity to assess and test innovative / appropriate adaptation and mitigation strategies. Working toward sustainable management, restoration, and maintenance of balanced, resilient arid ecosystems in Namibia will also be a means to support and expand economic sectors incl. opportunities for job creation and potentially provide a model for similar arid regions. Main vegetation zones are: desert (46%), savannah (37%), and dry woodlands and forests (17%), i.e. management strategies currently used by rural communities. 2. Capture and assess cultural and gender dimensions of management strategies within stakeholder groups using participatory approaches. 3. Determine science-based alternatives for adaptive land management strategies and test their acceptability to local communities and within the current policy framework. 4. Integrate identified indigenous knowledge with appropriate science and new emerging technologies to develop a training toolkit of effective strategies relevant to all stakeholders. 5. Utilize training sessions, education workshops, curriculum revisions, and appropriate information and communication technologies (ICTs) including social media outlets to disseminate the toolkit strategies. 6. Apply a modified logic

  18. Effects of aridity in controlling the magnitude of runoff and erosion after wildfire

    Science.gov (United States)

    Noske, Philip J.; Nyman, Petter; Lane, Patrick N. J.; Sheridan, Gary J.

    2016-06-01

    This study represents a uniquely high-resolution observation of postwildfire runoff and erosion from dry forested uplands of SE Australia. We monitored runoff and sediment load, and temporal changes in soil surface properties from two (0.2-0.3 ha) dry forested catchments burned during the 2009 Black Saturday wildfire. Event-based surface runoff to rainfall ratios approached 0.45 during the first year postwildfire, compared to reported values forests were attributed to wildfire-induced soil water repellency and inherently low hydraulic conductivity. Mean ponded hydraulic conductivity ranged from 3 to 29 mm h-1, much lower than values commonly reported for wetter forest. Annual sediment yields peaked at 10 t ha-1 during the first year before declining dramatically to background levels, suggesting high-magnitude erosion processes may become limited by sediment availability on hillslopes. Small differences in aridity between equatorial and polar-facing catchments produced substantial differences in surface runoff and erosion, most likely due to higher infiltration and surface roughness on polar-facing slopes. In summary, the results show that postwildfire erosion processes in Eucalypt forests in south-east Australia are highly variable and that distinctive response domains within the region exist between different forest types, therefore regional generalizations are problematic. The large differences in erosion processes with relatively small changes in aridity have large implications for predicting hydrologic-driven geomorphic changes, land degradation, and water contamination through erosion after wildfire across the landscape.

  19. Associations between metals in residential environmental media and exposure biomarkers over time in infants living near a mining-impacted site

    Science.gov (United States)

    Zota, Ami R.; Riederer, Anne M.; Ettinger, Adrienne S.; Schaider, Laurel A.; Shine, James P.; Amarasiriwardena, Chitra J.; Wright, Robert O.; Spengler, John D.

    2017-01-01

    Infant exposures to metals are a concern for mining-impacted communities, although limited information is available to assess residential exposures over the first year of life. We measured lead (Pb), manganese, arsenic, and cadmium in indoor air, house dust, yard soil, and tap water from 53 infants’ homes near the Tar Creek Superfund Site (Oklahoma, USA) at two time points representing developmental stages before and during initial ambulation (age 0–6 and 6–12 months). We measured infant metal biomarkers in: umbilical cord blood (n = 53); 12- (n = 43) and 24- (n = 22) month blood; and hair at age 12 months (n = 39). We evaluated cross-sectional and longitudinal associations between infant residential and biomarker concentrations. A doubling of mean dust Pb concentration was consistently associated with 36–49% higher 12-month blood Pb adjusting for cord blood Pb (P≤ 0.05). Adjusted dust concentration explained 29–35% of blood Pb variance, and consistent associations with other media were not observed. Although concentrations in dust and blood were generally low, strong and consistent associations between dust and body burden suggest that house dust in mining-impacted communities may impact children’s health. These relationships were observed at a young age, typically before blood Pb levels peak and when children’s development may be particularly vulnerable to toxic insult. PMID:26648247

  20. Climatic and Catchment-Scale Predictors of Chinese Stream Insect Richness Differ between Taxonomic Groups.

    Science.gov (United States)

    Tonkin, Jonathan D; Shah, Deep Narayan; Kuemmerlen, Mathias; Li, Fengqing; Cai, Qinghua; Haase, Peter; Jähnig, Sonja C

    2015-01-01

    Little work has been done on large-scale patterns of stream insect richness in China. We explored the influence of climatic and catchment-scale factors on stream insect (Ephemeroptera, Plecoptera, Trichoptera; EPT) richness across mid-latitude China. We assessed the predictive ability of climatic, catchment land cover and physical structure variables on genus richness of EPT, both individually and combined, in 80 mid-latitude Chinese streams, spanning a 3899-m altitudinal gradient. We performed analyses using boosted regression trees and explored the nature of their influence on richness patterns. The relative importance of climate, land cover, and physical factors on stream insect richness varied considerably between the three orders, and while important for Ephemeroptera and Plecoptera, latitude did not improve model fit for any of the groups. EPT richness was linked with areas comprising high forest cover, elevation and slope, large catchments and low temperatures. Ephemeroptera favoured areas with high forest cover, medium-to-large catchment sizes, high temperature seasonality, and low potential evapotranspiration. Plecoptera richness was linked with low temperature seasonality and annual mean, and high slope, elevation and warm-season rainfall. Finally, Trichoptera favoured high elevation areas, with high forest cover, and low mean annual temperature, seasonality and aridity. Our findings highlight the variable role that catchment land cover, physical properties and climatic influences have on stream insect richness. This is one of the first studies of its kind in Chinese streams, thus we set the scene for more in-depth assessments of stream insect richness across broader spatial scales in China, but stress the importance of improving data availability and consistency through time.

  1. Where does blue water go in the semi-arid area of northern China under changing environments?

    Science.gov (United States)

    Ren, L.; Yuan, F.; Yong, B.; Jiang, S.; Yang, X.; Gong, L.; Ma, M.; Liu, Y.; Shen, H.

    2014-09-01

    River flow regimes in the semi-arid region of northern China show a decreasing trend in terms of quantity. River runoff (i.e. blue water) reduction within the Laohahe catchment, the source area of the Liaohe River basin, manifests the aridity that exists widely in northern China. According to the water balance equation, during the past half-century, observed streamflow records in the Laohahe catchment show that blue water was re-directed to green water flow (i.e. evapotranspiration) over annual and decadal time scales, whereas precipitation did not vary much. Human activities and land-use/land-cover changes are the fundamental reasons for such runoff change. In the studied catchment, extensive land reclamation for agriculture, water withdrawal from streams, and abstraction from aquifers for irrigation are the direct and main causes leading to the decrease in observed blue water. These factors further demonstrate that a land-use decision is also a decision about water. Therefore, there is a need for an integrated modelling framework to intrinsically link climate, hydrological, and agricultural models with social and economic analyses.

  2. Fluvial transport and surface enrichment of arsenic in semi-arid mining regions: examples from the Mojave Desert, California.

    Science.gov (United States)

    Kim, Christopher S; Stack, David H; Rytuba, James J

    2012-07-01

    As a result of extensive gold and silver mining in the Mojave Desert, southern California, mine wastes and tailings containing highly elevated arsenic (As) concentrations remain exposed at a number of former mining sites. Decades of weathering and erosion have contributed to the mobilization of As-enriched tailings, which now contaminate surrounding communities. Fluvial transport plays an intermittent yet important and relatively undocumented role in the migration and dispersal of As-contaminated mine wastes in semi-arid climates. Assessing the contribution of fluvial systems to tailings mobilization is critical in order to assess the distribution and long-term exposure potential of tailings in a mining-impacted environment. Extensive sampling, chemical analysis, and geospatial mapping of dry streambed (wash) sediments, tailings piles, alluvial fans, and rainwater runoff at multiple mine sites have aided the development of a conceptual model to explain the fluvial migration of mine wastes in semi-arid climates. Intense and episodic precipitation events mobilize mine wastes downstream and downslope as a series of discrete pulses, causing dispersion both down and lateral to washes with exponential decay behavior as distance from the source increases. Accordingly a quantitative model of arsenic concentrations in wash sediments, represented as a series of overlapping exponential power-law decay curves, results in the acceptable reproducibility of observed arsenic concentration patterns. Such a model can be transferable to other abandoned mine lands as a predictive tool for monitoring the fate and transport of arsenic and related contaminants in similar settings. Effective remediation of contaminated mine wastes in a semi-arid environment requires addressing concurrent changes in the amounts of potential tailings released through fluvial processes and the transport capacity of a wash.

  3. Hydropedological insights when considering catchment classification

    Directory of Open Access Journals (Sweden)

    J. Bouma

    2011-06-01

    Full Text Available Soil classification systems are analysed to explore the potential of developing classification systems for catchments. Soil classifications are useful to create systematic order in the overwhelming quantity of different soils in the world and to extrapolate data available for a given soil type to soils elsewhere with identical classifications. This principle also applies to catchments. However, to be useful, soil classifications have to be based on permanent characteristics as formed by the soil forming factors over often very long periods of time. When defining permanent catchment characteristics, discharge data would therefore appear to be less suitable. But permanent soil characteristics do not necessarily match with characteristics and parameters needed for functional soil characterization focusing, for example, on catchment hydrology. Hydropedology has made contributions towards the required functional characterization of soils as is illustrated for three recent hydrological catchment studies. However, much still needs to be learned about the physical behaviour of anisotropic, heterogeneous soils with varying soil structures during the year and about spatial and temporal variability. The suggestion is made therefore to first focus on improving simulation of catchment hydrology, possibly incorporating hydropedological expertise, before embarking on a catchment classification effort which involves major input of time and involves the risk of distraction. In doing so, we suggest to also define other characteristics for catchment performance than the traditionally measured discharge rates. Such characteristics may well be derived from societal issues being studied, as is illustrated for the Green Water Credits program.

  4. On predicting debris flows in arid mountain belts

    Science.gov (United States)

    Stolle, Amelie; Langer, Maria; Blöthe, Jan Henrik; Korup, Oliver

    2015-03-01

    The use of topographic metrics for estimating the susceptibility to, and reconstructing the characteristics of, debris flows has a long research tradition, although largely devoted to humid mountainous terrain. The exceptional 2010 monsoonal rainstorms in the high-altitude mountain desert of Ladakh and Zanskar, NW India, were a painful reminder of how susceptible arid regions are to rainfall-triggered flash floods, landslides, and debris flows. The rainstorms of August 4-6 triggered numerous debris flows, killing 182 people, devastating 607 houses, and more than 10 bridges around Ladakh's capital of Leh. The lessons from this disaster motivated us to revisit methods of predicting (a) flow parameters such as peak discharge and maximum velocity from field and remote sensing data, and (b) the susceptibility to debris flows from catchment morphometry. We focus on quantifying uncertainties tied to these approaches. Comparison of high-resolution satellite images pre- and post-dating the 2010 rainstorm reveals the extent of damage and catastrophic channel widening. Computations based on these geomorphic markers indicate maximum flow velocities of 1.6-6.7 m s- 1 with runout of up to ~ 10 km on several alluvial fans that sustain most of the region's settlements. We estimate median peak discharges of 310-610 m3 s- 1, which are largely consistent with previous estimates. Monte Carlo-based error propagation for a single given flow-reconstruction method returns a variance in discharge similar to one derived from juxtaposing several different flow reconstruction methods. We further compare discriminant analysis, classification tree modelling, and Bayesian logistic regression to predict debris-flow susceptibility from morphometric variables of 171 catchments in the Ladakh Range. These methods distinguish between fluvial and debris flow-prone catchments at similar success rates, but Bayesian logistic regression allows quantifying uncertainties and relationships between potential

  5. A Methodology to Assess and Evaluate Rainwater Harvesting Techniques in (Semi- Arid Regions

    Directory of Open Access Journals (Sweden)

    Ammar Adham

    2016-05-01

    Full Text Available Arid and semi-arid regions around the world face water scarcity problems due to lack of precipitation and unpredictable rainfall patterns. For thousands of years, rainwater harvesting (RWH techniques have been applied to cope with water scarcity. Researchers have used many different methodologies for determining suitable sites and techniques for RWH. However, limited attention has been given to the evaluation of RWH structure performance. The aim of this research was to design a scientifically-based, generally applicable methodology to better evaluate the performance of existing RWH techniques in (semi- arid regions. The methodology integrates engineering, biophysical and socio-economic criteria using the Analytical Hierarchy Process (AHP supported by the Geographic Information System (GIS. Jessour/Tabias are the most traditional RWH techniques in the Oum Zessar watershed in south-eastern Tunisia, which were used to test this evaluation tool. Fifty-eight RWH locations (14 jessr and 44 tabia in three main sub-catchments of the watershed were assessed and evaluated. Based on the criteria selected, more than 95% of the assessed sites received low or moderate suitability scores, with only two sites receiving high suitability scores. This integrated methodology, which is highly flexible, saves time and costs, is easy to adapt to different regions and can support designers and decision makers aiming to improve the performance of existing and new RWH sites.

  6. Shift of annual water balance in the Budyko space for catchments with groundwater-dependent evapotranspiration

    Science.gov (United States)

    Wang, Xu-Sheng; Zhou, Yangxiao

    2016-09-01

    The Budyko framework represents the general relationship between the evapotranspiration ratio (F) and the aridity index (φ) for the mean annual steady-state water balance at the catchment scale. It is interesting to investigate whether this standard F - φ space can also be applied to capture the shift of annual water balance in catchments with varying dryness. Previous studies have made significant progress in incorporating the storage effect into the Budyko framework for the non-steady conditions, whereas the role of groundwater-dependent evapotranspiration was not investigated. This study investigates how groundwater-dependent evapotranspiration causes the shift of the annual water balance in the standard Budyko space. A widely used monthly hydrological model, the ABCD model, is modified to incorporate groundwater-dependent evapotranspiration into the zone with a shallow water table and delayed groundwater recharge into the zone with a deep water table. This model is applied in six catchments in the Erdos Plateau, China, to estimate the actual annual evapotranspiration. Results show that the variations in the annual F value with the aridity index do not satisfy the standard Budyko formulas. The shift of the annual water balance in the standard Budyko space is a combination of the Budyko-type response in the deep groundwater zone and the quasi-energy limited condition in the shallow groundwater zone. Excess evapotranspiration (F > 1) could occur in dry years, which is contributed by the significant supply of groundwater for evapotranspiration. Use of groundwater for irrigation can increase the frequency of the F > 1 cases.

  7. Biodegradation of biphenyl and removal of 2-chlorobiphenyl by Pseudomonas sp. KM-04 isolated from PCBs-contaminated mine impacted soil

    Science.gov (United States)

    Nam, I.; Chon, C.; Kim, J.; Kim, Y.

    2013-12-01

    The aim of the present study is to remediate the PCBs contaminated mine soil using microcosm study. For that, the naturally occurring microorganisms are stimulated and enriched in soil itself by supplementing biphenyl as well as benzoic acid. As a result the biphenyl degrading organisms are induced to degrade the PCBs contamination. From the stimulated soil, the biphenyl degrading organisms are isolated and degraded metabolites are elucidated. Pseudomonas sp. strain KM-04 was isolated from PCBs-contaminated soil in a coal mine-impacted area, and identification of bacteria was done by sequencing the 16S rRNA gene analysis. The growth of Pseudomonas sp. strain KM-04 using biphenyl as the sole carbon source was investigated by culturing in 100-mL Erlenmeyer flasks containing 10 ml sterilized MSM and 10 μg/ml biphenyl, and the ability of KM-04 to remove biphenyl and 2-chlorobiphenyl from mine soil was investigated. Metabolite formation was confirmed by liquid chromatography/atmospheric pressure chemical ionization-mass spectrometric analysis. Pseudomonas sp. strain KM-04 uses biphenyl as a sole carbon and energy source, and resting cells convert biphenyl to its metabolic intermediates, including dihydroxybiphenyl, 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoic acid, and benzoic acid. Incubation of real soil collected from abandoned mine areas with resting cells of Pseudomonas sp. strain KM-04 for 10 days resulted in the 98.5 % of biphenyl and 82.3 % of 2-chlorobiphenyl in a slurry system. The ability of the Pseudomonas sp. strain KM-04 to bioremediate biphenyl and 2-chlorobiphenyl from abandoned mine soil was examined using soil microcosm studies under laboratory conditions. Treatment of mine soil with the Pseudomonas sp. strain KM-04 for 15 days resulted in 87.1 % reduction in biphenyl and 68.7 % in 2-chlorobiphenyl contents. The results suggest that Pseudomonas sp. strain KM-04 is a potential candidate for the biological removal of biphenyl and chlorinated derivatives

  8. Excess erosion and deposition in the catchments of Kamenichka and Radanjska river, Republic of Macedonia

    Directory of Open Access Journals (Sweden)

    Milevski Ivica

    2009-01-01

    Full Text Available One of the greatest environmental problems in the Republic of Macedonia is accelerated soil erosion caused by high human impact during last centuries on to the susceptible landscape. Natural factors itself are very suitable for development of such erosion: from mostly erodible rocks and soils on the mountainous slopes around the depressions, to the generally continental, semi-arid climate and slight vegetation cover. Because of that, there are sites with severe erosion and deposition like those in the catchments of Kamenichka River and Radanjska River, two torrential tributaries of Bregalnica. In these catchments there are varieties of erosion-related landforms: rills, gullies, badlands, landslides, as well as valley-type alluvial fans and huge alluvial plains. Such devastating accelerated erosion and deposition largely transformed original landscape, and represent significant environmental, social, and economic problem in local areas. Because of that, some measures of protection and conservation were taken from 1950-ties in both catchments. But it is obvious that the final effect of these measures is far of enough, so new efforts must be implemented to revitalizing these abandoned lands.

  9. Doing hydrology backwards in tropical humid catchments

    Science.gov (United States)

    Real Rangel, R.; Brena-Naranjo, J. A.; Pedrozo-Acuña, A.

    2015-12-01

    Top-down approaches in hydrology offer the possibility to predict water fluxes at the catchment scale based on the interpretation of the observed hydrological response at the catchment itself. Doing hydrology backwards (inferring precipitation and evapotranspiration rates at the catchment scale from streamflow measurements, see Kirchner (2009)) can be a useful methodology for estimating water fluxes at the catchment and regional scales. Previous studies using this inverse modeling approach have been performed in regions (UK, Switzerland, France, Eastern US) where energy-limited (in winter and early spring) and water-limited conditions (in summer) prevail during a large period of the year. However, such approach has not been tested in regions characterized by a quasi-constant supply of water and energy (e.g. humid tropics). The objective of this work is to infer annual rates of precipitation and evapotranspiration over the last decade in 10 catchments located in Mexico's tropical humid regions. Hourly discharge measurements during recession periods were analyzed and parameters for the nonlinear storage-discharge relationship of each catchment were derived. Results showed large variability in both catchment-scale precipitation and evapotranspiration rates among the selected study sites. Finally, a comparison was done between such estimates and those obtained from remotely-sensed data (TRMM for precipitation and MOD16 for evapotranspiration).

  10. Mining-impacted sources of metal loading to an alpine stream based on a tracer-injection study, Clear Creek County, Colorado

    Science.gov (United States)

    Fey, David L.; Wirt, Laurie

    2007-01-01

    Base flow water in Leavenworth Creek, a tributary to South Clear Creek in Clear Creek County, Colorado, contains copper and zinc at levels toxic to aquatic life. The metals are predominantly derived from the historical Waldorf mine, and sources include an adit, a mine-waste dump, and mill-tailings deposits. Tracer-injection and water-chemistry synoptic studies were conducted during low-flow conditions to quantify metal loads of mining-impacted inflows and their relative contributions to nearby Leavenworth Creek. During the 2-year investigation, the adit was rerouted in an attempt to reduce metal loading to the stream. During the first year, a lithium-bromide tracer was injected continuously into the stream to achieve steady-state conditions prior to synoptic sampling. Synoptic samples were collected from Leavenworth Creek and from discrete surface inflows. One year later, synoptic sampling was repeated at selected sites to evaluate whether rerouting of the adit flow had improved water quality.

  11. Examination of catchment areas for public transport

    DEFF Research Database (Denmark)

    Landex, Alex; Hansen, Stephen; Andersen, Jonas Lohmann Elkjær

    2006-01-01

    The paper presents a method to examine the catchment areas for stops in high quality public transport systems based on the street network in the examined area. This is achieved by implementing the Service Area functions from the ArcGIS extension Network Analyst. The method is compared to a more...... or by making changes in the street network around the station. The paper also discusses the degree of realism in the used GIS networks and how it can affect the size of the catchment areas. It is concluded that the Service Area method improves the detail-level and accuracy in catchment area analyses...

  12. SCIENCES IN COLD AND ARID REGIONS

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Aims and Scope Sciences in Cold and Arid Regions, an international Engiish-language journal, is devoted to publishing the latest research achievements on the process and the pattern of Earth surface system in cold and arid regions. Researches in cold regions 1) emphasize particularly on the cold-region-characterized physical, chemical and biological processes and their interactions, and on the response of Cryosphere to Global change and Human activities as well as its effect to environment and the acclimatizable

  13. Exploring the physical controls of regional patterns of flow duration curves - Part 3: A catchment classification system based on regime curve indicators

    Science.gov (United States)

    Coopersmith, E.; Yaeger, M. A.; Ye, S.; Cheng, L.; Sivapalan, M.

    2012-11-01

    Predictions of hydrological responses in ungauged catchments can benefit from a classification scheme that can organize and pool together catchments that exhibit a level of hydrologic similarity, especially similarity in some key variable or signature of interest. Since catchments are complex systems with a level of self-organization arising from co-evolution of climate and landscape properties, including vegetation, there is much to be gained from developing a classification system based on a comparative study of a population of catchments across climatic and landscape gradients. The focus of this paper is on climate seasonality and seasonal runoff regime, as characterized by the ensemble mean of within-year variation of climate and runoff. The work on regime behavior is part of an overall study of the physical controls on regional patterns of flow duration curves (FDCs), motivated by the fact that regime behavior leaves a major imprint upon the shape of FDCs, especially the slope of the FDCs. As an exercise in comparative hydrology, the paper seeks to assess the regime behavior of 428 catchments from the MOPEX database simultaneously, classifying and regionalizing them into homogeneous or hydrologically similar groups. A decision tree is developed on the basis of a metric chosen to characterize similarity of regime behavior, using a variant of the Iterative Dichotomiser 3 (ID3) algorithm to form a classification tree and associated catchment classes. In this way, several classes of catchments are distinguished, in which the connection between the five catchments' regime behavior and climate and catchment properties becomes clearer. Only four similarity indices are entered into the algorithm, all of which are obtained from smoothed daily regime curves of climatic variables and runoff. Results demonstrate that climate seasonality plays the most significant role in the classification of US catchments, with rainfall timing and climatic aridity index playing somewhat

  14. Exploring the physical controls of regional patterns of flow duration curves - Part 3: A catchment classification system based on seasonality and runoff regime

    Science.gov (United States)

    Coopersmith, E.; Yaeger, M.; Ye, S.; Cheng, L.; Sivapalan, M.

    2012-06-01

    Predictions of hydrological responses in ungauged catchments can benefit from a classification scheme that can organize and pool together catchments that exhibit a level of hydrologic similarity, especially similarity in some key variable or signature of interest. Since catchments are complex systems with a level of self-organization arising from co-evolution of climate and landscape properties, including vegetation, there is much to be gained from developing a classification system based on a comparative study of a population of catchments across climatic and landscape gradients. The focus of this paper is on climate seasonality and seasonal runoff regime, as characterized by the ensemble mean of within-year variation of climate and runoff. The work on regime behavior is part of an overall study of the physical controls on regional patterns of Flow Duration Curves (FDCs), motivated by the fact that regime behavior leaves a major imprint upon the shape of FDCs, especially the slope of the FDCs. As an exercise in comparative hydrology, the paper seeks to assess the regime behavior of 428 catchments from the MOPEX database simultaneously, classifying and regionalizing them into homogeneous or hydrologically similar groups. A decision tree is developed on the basis of a metric chosen to characterize similarity of regime behavior, using a variant of the Iterative Dichotomiser (ID3) algorithm to form a classification tree and associated catchment classes. In this way, several classes of catchments are distinguished, in which the connection between the catchments' regime behavior and climate and catchment properties becomes self-evident. Only four similarity indices are entered into the algorithm, all of which are obtained from smoothed daily regime curves of climatic variables and runoff. Results demonstrate that climate seasonality plays the most significant role in the classification of US catchments, with rainfall timing and climatic aridity index playing somewhat

  15. Rainwater harvesting in arid and semi-arid zones (repr. 1997)

    NARCIS (Netherlands)

    Boers, Th.M.

    1994-01-01

    In arid and semi-arid regions, the scarcity of water can be alleviated by rainwater harvesting, which is defined as a method of inducing, collecting, storing, and conserving local surface runoff for agriculture. Rainwater harvesting can be applied with different systems, and this dissertation deals

  16. Catchment controls and human disturbances on the geomorphology of small Mediterranean estuarine systems

    Science.gov (United States)

    Estrany, Joan; Grimalt, Miquel

    2014-10-01

    Geographic signatures are physical and human-induced characteristics or processes that identify comparable or unique features of estuaries along latitudinal gradients. In Mediterranean areas, the microtidal regime and the strong seasonal and inter-annual contrasts cause an alternation between relatively high runoff and arid conditions. Furthermore, the long history of human settlement also increases the complexity in the study of these estuarine systems. This study investigates these signatures of the estuaries located within the Mallorcan eastern coast, which are geomorphologically homogeneous because of a similar bedrock geology and Holocene history. A multi-method approach focused on the integration of geomorphometry, hydraulics, historical sources and statistics was used. We explore the role played by catchment morphometric parameters, severe flash flood events and human disturbances in controlling the geomorphology of 10 beach-barrier enclosed, fluvial incised lagoons. Most of the lagoons discharge into 'calas', ranging in size from 1345 to 17,537 m2 and their related catchments are representative of the Mediterranean hydrological systems. Multiple regression models illustrate that the size, slope and drainage network development of the catchments explain the variance in length (r2 = 0.67), volume (r2 = 0.49), area (r2 = 0.64), circularity (r2 = 0.72) and average width (r2 = 0.81) of the lagoons. Depending on these catchment morphometric variables, the shape of the lagoons is also determined by the occurrence of catastrophic flash floods, which cause scouring and dredging, whereas the ordinary flood events and sea storms promote refilling and sedimentation. A historical analysis since 1850 documented 18 flood events, 5 of which were catastrophic with destructive effects along the catchments and large morphological changes in coastal lagoons. High intensity rainfall (up to 200 mm in 2 h), the geomorphometry of the catchments and the massive construction of

  17. Salinity shapes food webs in shallow lakes: implications for increasing aridity with climate change

    DEFF Research Database (Denmark)

    Vidal, Nicolas; Yu, Jinlei; Gutierrez, Maria Florencia

    2015-01-01

    A reduction in runoff and higher evaporation rates are expected to occur towards 2050 in arid and semiarid regions of the world, resulting in a reduction of water level and salinization of inland waters. Besides the natural process of catchment erosion, human activities such as irrigation of crops...... may also increase salinization. Reduced biodiversity in freshwater systems is the most commonly reported effect of salinization, which may have implications for food web structure and likely for ecosystem functioning as well. The objective of the study was to analyze the effects of salinity...... on community and food web structure in 24 lakes along a wide salinity gradient, from freshwater (0.5 g L-1) to hypersaline lakes (115 g L-1), in a semiarid region in North West China. Fish, zooplankton and macroinvertebrate communities were sampled during July 2014 for determination of taxonomy and size...

  18. Analyzing catchment behavior through catchment modeling in the Gilgel Abay, Upper Blue Nile River Basin, Ethiopia

    Directory of Open Access Journals (Sweden)

    S. Uhlenbrook

    2010-10-01

    Full Text Available Understanding catchment hydrological processes is essential for water resources management, in particular in data scarce regions. The Gilgel Abay catchment (a major tributary into Lake Tana, source of the Blue Nile is undergoing intensive plans for water management, which is part of larger development plans in the Blue Nile basin in Ethiopia. To obtain a better understanding of the water balance dynamics and runoff generation mechanisms and to evaluate model transferability, catchment modeling has been conducted using the conceptual hydrological model HBV. Accordingly, the catchment of the Gilgel Abay has been divided into two gauged sub-catchments (Upper Gilgel Abay and Koga and the un-gauged part of the catchment. All available data sets were tested for stationarity, consistency and homogeneity and the data limitations (quality and quantity are discussed. Manual calibration of the daily models for three different catchment representations, i.e. (i lumped, (ii lumped with multiple vegetation zones, and (iii semi-distributed with multiple vegetation and elevation zones, showed good to satisfactory model performances with Nash-Sutcliffe efficiencies Reff > 0.75 and > 0.6 for the Upper Gilgel Abay and Koga sub-catchments, respectively. Better model results could not be obtained with manual calibration, very likely due to the limited data quality and model insufficiencies. Increasing the computation time step to 15 and 30 days improved the model performance in both sub-catchments to Reff > 0.8. Model parameter transferability tests have been conducted by interchanging parameters sets between the two gauged sub-catchments. Results showed poor performances for the daily models (0.30 < Reff < 0.67, but better performances for the 15 and 30 days models, Reff > 0.80. The transferability tests together with a sensitivity analysis using Monte Carlo simulations (more than 1 million

  19. In Lieu of the Paired-Catchment Approach - Hydrologic Model Change Detection at the Catchment Scale

    Science.gov (United States)

    Zegre, N. P.

    2009-05-01

    Knowledge of the effects of forest management on hydrology primarily comes from paired-catchment studies conducted world-wide. While this approach has been useful for discerning changes in small experimental catchments and has contributed fundamental knowledge of the effects of forest and natural resources management on hydrology, results from experimental catchment studies exhibit temporal variability, have limited spatial inference, and lack insight into internal catchment processes. To address these limitations, traditional field experiments can be supplemented with numerical models to isolate the effects of disturbance on catchment behavior. Outlined in this study is an alternative method of change detection for daily time-series streamflow that integrates hydrologic modeling and statistical change detection methods used to discern the effects of contemporary forest management on the hydrology of western Oregon Cascades headwater catchments. In this study, a simple rainfall-runoff model was used to generate virtual reference catchments using attributes that reflect streamflow conditions absent of forest disturbance. Streamflow was simulated under three levels of model uncertainty using GLUE and were used to construct generalized least squares regression models to discern changes in hydrologic behavior. By considering processes within a single experimental catchment rather than the two spatially explicit catchments used in traditional paired experiments, it was possible to reduce unexplained variation and increase the likelihood of correctly detecting hydrologic effects following forest harvesting. In order to evaluate the stability of the hydrologic and statistical models and catchment behavior over time, the change detection method was applied to a contemporary reference catchment. By applying the change detection model to reference catchments, it was possible to eliminate unexpected variation as a cause for detected changes in observed hydrology. Further, it

  20. Before and After Integrated Catchment Management in a Headwater Catchment: Changes in Water Quality

    Science.gov (United States)

    Hughes, Andrew O.; Quinn, John M.

    2014-12-01

    Few studies have comprehensively measured the effect on water quality of catchment rehabilitation measures in comparison with baseline conditions. Here we have analyzed water clarity and nutrient concentrations and loads for a 13-year period in a headwater catchment within the western Waikato region, New Zealand. For the first 6 years, the entire catchment was used for hill-country cattle and sheep grazing. An integrated catchment management plan was implemented whereby cattle were excluded from riparian areas, the most degraded land was planted in Pinus radiata, channel banks were planted with poplar trees and the beef cattle enterprise was modified. The removal of cattle from riparian areas without additional riparian planting had a positive and rapid effect on stream water clarity. In contrast, the water clarity decreased in those sub-catchments where livestock was excluded but riparian areas were planted with trees and shrubs. We attribute the decrease in water clarity to a reduction in groundcover vegetation that armors stream banks against preparatory erosion processes. Increases in concentrations of forms of P and N were recorded. These increases were attributed to: (i) the reduction of instream nutrient uptake by macrophytes and periphyton due to increased riparian shading; (ii) uncontrolled growth of a nitrogen fixing weed (gorse) in some parts of the catchment, and (iii) the reduction in the nutrient attenuation capacity of seepage wetlands due to the decrease in their areal coverage in response to afforestation. Our findings highlight the complex nature of the water quality response to catchment rehabilitation measures.

  1. Catchment classification: empirical analysis of hydrologic similarity based on catchment function in the eastern USA

    Directory of Open Access Journals (Sweden)

    K. Sawicz

    2011-09-01

    Full Text Available Hydrologic similarity between catchments, derived from similarity in how catchments respond to precipitation input, is the basis for catchment classification, for transferability of information, for generalization of our hydrologic understanding and also for understanding the potential impacts of environmental change. An important question in this context is, how far can widely available hydrologic information (precipitation-temperature-streamflow data and generally available physical descriptors be used to create a first order grouping of hydrologically similar catchments? We utilize a heterogeneous dataset of 280 catchments located in the Eastern US to understand hydrologic similarity in a 6-dimensional signature space across a region with strong environmental gradients. Signatures are defined as hydrologic response characteristics that provide insight into the hydrologic function of catchments. A Bayesian clustering scheme is used to separate the catchments into 9 homogeneous classes, which enable us to interpret hydrologic similarity with respect to similarity in climatic and landscape attributes across this region. We finally derive several hypotheses regarding controls on individual signatures from the analysis performed here.

  2. Impacts of urbanization on nitrogen cycling and aerosol, surface and groundwater transport in semi-arid regions

    Science.gov (United States)

    Lohse, K. A.; Gallo, E.; Carlson, M.; Riha, K. M.; Brooks, P. D.; McIntosh, J. C.; Sorooshian, A.; Michalski, G. M.; Meixner, T.

    2011-12-01

    Semi-arid regions are experiencing disproportionate increases in human population and land transformation worldwide, taxing limited water resources and altering nitrogen (N) biogeochemistry. How the redistribution of water and N by urbanization affects semi-arid ecosystems and downstream water quality (e.g. drinking water) is unclear. Understanding these interactions and their feedbacks will be critical for developing science-based management strategies to sustain these limited resources. This is especially true in the US where some of the fastest growing urban areas are in semi-arid ecosystems, where N and water cycles are accelerated, and intimately coupled, and where runoff from urban ecosystems is actively managed to augment a limited water supply to the growing human population. Here we synthesize several ongoing studies from the Tucson Basin in Arizona and examine how increasing urban land cover is altering rainfall-runoff relationships, groundwater recharge, water quality, and long range transport of atmospheric N. Studies across 5 catchments varying in impervious land cover showed that only the least impervious catchment responded to antecedent moisture conditions while hydrologic responses were not statistically related to antecedent rainfall conditions at more impervious sites. Regression models indicated that rainfall depth, imperviousness, and their combined effect control discharge and runoff ratios (p < 0.01, r2 = 0.91 and 0.75, respectively). In contrast, runoff quality was not predictably related to imperviousness or catchment size. Rather, rainfall depth and duration, time since antecedent rainfall, and stream channel characteristics and infrastructure controlled runoff chemistry. Groundwater studies showed nonpoint source contamination of CFCs and associated nitrate in areas of rapid recharge along ephemeral channels. Aerosol measurements indicate that both long-range transport of N and N emissions from Tucson are being transported and deposited

  3. Evaluation of coal-mining impacts using numerical classification of benthic invertebrate data from streams draining a heavily mined basin in eastern Tennessee

    Science.gov (United States)

    Bradfield, A.D.

    1986-01-01

    Coal-mining impacts on Smoky Creek, eastern Tennessee were evaluated using water quality and benthic invertebrate data. Data from mined sites were also compared with water quality and invertebrate fauna found at Crabapple Branch, an undisturbed stream in a nearby basin. Although differences in water quality constituent concentrations and physical habitat conditions at sampling sites were apparent, commonly used measures of benthic invertebrate sample data such as number of taxa, sample diversity, number of organisms, and biomass were inadequate for determining differences in stream environments. Clustering algorithms were more useful in determining differences in benthic invertebrate community structure and composition. Normal (collections) and inverse (species) analyses based on presence-absence data of species of Ephemeroptera, Plecoptera, and Tricoptera were compared using constancy, fidelity, and relative abundance of species found at stations with similar fauna. These analyses identified differences in benthic community composition due to seasonal variations in invertebrate life histories. When data from a single season were examined, sites on tributary streams generally clustered separately from sites on Smoky Creek. These analyses compared with differences in water quality, stream size, and substrate characteristics between tributary sites and the more degraded main stem sites, indicated that numerical classification of invertebrate data can provide discharge-independent information useful in rapid evaluations of in-stream environmental conditions. (Author 's abstract)

  4. Organic amendments impact the availability of heavy metal(loid)s in mine-impacted soil and their phytoremediation by Penisitum americanum and Sorghum bicolor.

    Science.gov (United States)

    Nawab, Javed; Khan, Sardar; Aamir, Muhammad; Shamshad, Isha; Qamar, Zahir; Din, Islamud; Huang, Qing

    2016-02-01

    The amendment of contaminated soil with organic materials is considered to be an environmentally friendly technique to immobilize heavy metal(loid)s and minimize their subsequent bioaccumulation in plants. This study focuses on the effects of different amendment techniques, such as the use of activated carbons (granulated or powder) and farmyard manure at various application rates (2 and 5 %). These techniques were applied on heavy metal(loid)s such as Ni, Cr, Cd, Pb, Mn, Cu, Zn, Fe, Co, and Al that were present in mine-impacted soil and caused bioaccumulation in cultivated plants. The results showed that, compared with the control, almost all the techniques significantly (P ≤ 0.01) reduced the bioavailability of heavy metal(loid)s in the amended soil. The bioaccumulation of heavy metal(loid)s in Penisitum americanum and Sorghum bicolor was significantly (P ≤ 0.01) reduced with all techniques, while Zn and Cd concentrations increased with the use of farmyard manure. Also compared with the control, plant growth was significantly decreased with the use of activated carbons, particularly with powder activated carbons, while farmyard manure (at 5 %) significantly (P ≤ 0.01) increased plant growth. Among the amendment techniques, powdered activated carbons (at 5 %) were best at reducing the bioavailability of heavy metal(loid)s in soil and plant accumulation. However, it negatively affected the growth of selected plant species.

  5. Characterizing streamflow generation in Alpine catchments

    Science.gov (United States)

    Chiogna, Gabriele; Cano Paoli, Karina; Bellin, Alberto

    2016-04-01

    Developing effective hydrological models for streamflow generation in Alpine catchments is challenging due to the inherent complexity of the intertwined processes controlling water transfer from hillslopes to streams and along the river network. With water discharge as the sole observational variable it is impossible to differentiate between different streamflow sources, and modelling activity is often limited to simplified phenomenological rainfall-runoff models. This study focuses on quantifying streamflow sources at different temporal scales and the associated uncertainty by using natural tracer data (electrical conductivity, oxygen and hydrogen stable isotopes ratios) as observational variables supplementing streamflow measurements. We determine the spatial and temporal hydrological behavior and the mean residence time of water in the Vermigliana catchment, North-Eastern Italy and we separate contributions to streamflow originating from Presena and Presanella glaciers, both exerting a strong control on the hydrologic budget of the study site. Furthermore, we identify a seasonal control on the effect of storm events. The catchment responded rapidly to precipitation events in early autumn, it was unaffected by precipitation events in early spring, while runoff generation was enhanced by snow melting in late autumn. Air temperature is identified as the main controlling parameter, in addition to precipitation. Two-component mixing analysis showed that the relative contribution of new water, which can contribute up to 75% of total streamflow, is very rapid. Only two hours time-lag was observed between the beginning of the precipitation event and the emergence of a significant contribution of new water. These results evidence the relevance of mixing between pre-event and event water in the Vermigliana catchment, and in similar high elevation Alpine catchments. This study provides new insights on the dynamics of streamflow generation in Alpine catchments and a

  6. Conservation and restoration of degraded ecosystems in arid and semi-arid areas of northwest China

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In "West Development" of China, one of the most important activities is the Natural Forest Protection Program, designed to swiftly convert the focus of management and utilization of the natural forests from a timber orientation towards forest conservation, sustainable management and environmental protection. The project covered almost all the arid and semi-arid regions in Northwest region. Accompanying this great campaign this paper studied the conservation and restoration model of degraded ecosystems in arid and semi-arid lands in Northwest China. The past practices have resulted in considerably natural forest degradation and loss through land conversion (primarily for agriculture), over-harvesting, inadequate reforestation and lack of protection. The consequences have been the loss of soil and water resources, diminished timber production capacity on a sustainable basis, and environmental losses. This paper applied Aronson's restoration model and proposed the conservation, restoration, re-allocation and preservation program for the implementation of environmental improvement and natural forest conservation.

  7. Competing feedbacks drive state transitions during initial catchment evolution: Examples from post-mining landscape and ecosystems evolution

    Science.gov (United States)

    Hinz, Christoph; Wolfgang, Schaaf; Werner, Gerwin

    2014-05-01

    Within the context of severely disturbed landscapes with little or no ecological memory, such as post-mining landscapes, we propose a simple framework that explains the catchment evolution as a result of competing feedbacks influenced by the initial conditions and the atmospheric drivers such as rainfall intermittency and intensity. The first stage of the evolution is dominated by abiotic feedbacks triggered by rainfall and subsequent fluid flow causing particle mobilisation on the surface and in the subsurface leading to flow concentration or in some instances to densification of surface and subsurface substrates. Subsequently, abiotic-biotic feedbacks start to compete in the sense that biological activity generally stabilizes substrate by preventing particle mobilisation and hence contribute to converting the substrate to a habitat. We suggest that these competing feedbacks may generate alternative stable states in particular under semi-arid and arid climatic conditions, while in temperate often energy limited environments biological process "outcompete" abiotic processes leading to a stable state, in particular from the water balance point of view for comparable geomorphic situations. To illustrate this framework, we provide examples from post-mining landscapes, in which soil, water and vegetation was monitored. In case of arid regions in Australia, we provide evidence that the initial conditions of a mine waste disposal "locked" the system into a state that was limited by water and nutrient storage capacity while at the same time it was stable from a geomorphic point of view for the observation period. The cause of the system to be locked in, is the very high hydraulic conductivity of the substrate, that has not undergone any changes during the first years. In contrast to this case study, we illustrate how this framework explains the evolution of an artificial catchment (Hühnerwasser Catchment) in Lusatia (150 km southeast of Berlin, Germany). During the

  8. Adaptation to drought in arid and semi-arid environments: Case of the Zambezi Valley, Zimbabwe

    OpenAIRE

    Emmanuel Mavhura; Desmond Manatsa; Terence Mushore

    2015-01-01

    Small-scale rain-fed agriculture is the main livelihood in arid to semi-arid regions of subSaharan Africa. The area is characterised by erratic rainfall and frequent droughts, making the capacity for coping with temporal water shortages essential for smallholder farmers. Focusing on the Zambezi Valley, Zimbabwe, this study investigates the impact of drought on food security and the strategies used by smallholder farmers to cope with drought. We used meteorological data and interviews to exami...

  9. The International Workshop on Environmental Changes and Sustainable Development in Arid and Semi-arid Regions

    Institute of Scientific and Technical Information of China (English)

    Xiaoping Yang; Arthur Conacher

    2007-01-01

    @@ Arid regions,dominated by deserts,are characterized by a severe shortage of moisture,and a lack of perennial and integrated systems of drainage.Distributed over a very large range of temperatures,from the very hot to the very cold zones,arid regions cover about one third of the world's land surface and occur in every continent,including Antarctica.

  10. Aridity and decomposition processes in complex landscapes

    Science.gov (United States)

    Ossola, Alessandro; Nyman, Petter

    2015-04-01

    Decomposition of organic matter is a key biogeochemical process contributing to nutrient cycles, carbon fluxes and soil development. The activity of decomposers depends on microclimate, with temperature and rainfall being major drivers. In complex terrain the fine-scale variation in microclimate (and hence water availability) as a result of slope orientation is caused by differences in incoming radiation and surface temperature. Aridity, measured as the long-term balance between net radiation and rainfall, is a metric that can be used to represent variations in water availability within the landscape. Since aridity metrics can be obtained at fine spatial scales, they could theoretically be used to investigate how decomposition processes vary across complex landscapes. In this study, four research sites were selected in tall open sclerophyll forest along a aridity gradient (Budyko dryness index ranging from 1.56 -2.22) where microclimate, litter moisture and soil moisture were monitored continuously for one year. Litter bags were packed to estimate decomposition rates (k) using leaves of a tree species not present in the study area (Eucalyptus globulus) in order to avoid home-field advantage effects. Litter mass loss was measured to assess the activity of macro-decomposers (6mm litter bag mesh size), meso-decomposers (1 mm mesh), microbes above-ground (0.2 mm mesh) and microbes below-ground (2 cm depth, 0.2 mm mesh). Four replicates for each set of bags were installed at each site and bags were collected at 1, 2, 4, 7 and 12 months since installation. We first tested whether differences in microclimate due to slope orientation have significant effects on decomposition processes. Then the dryness index was related to decomposition rates to evaluate if small-scale variation in decomposition can be predicted using readily available information on rainfall and radiation. Decomposition rates (k), calculated fitting single pool negative exponential models, generally

  11. Aridity under conditions of increased CO2

    Science.gov (United States)

    Greve, Peter; Roderick, Micheal L.; Seneviratne, Sonia I.

    2016-04-01

    A string of recent of studies led to the wide-held assumption that aridity will increase under conditions of increasing atmospheric CO2 concentrations and associated global warming. Such results generally build upon analyses of changes in the 'aridity index' (the ratio of potential evaporation to precipitation) and can be described as a direct thermodynamic effect on atmospheric water demand due to increasing temperatures. However, there is widespread evidence that contradicts the 'warmer is more arid' interpretation, leading to the 'global aridity paradox' (Roderick et al. 2015, WRR). Here we provide a comprehensive assessment of modeled changes in a broad set of dryness metrics (primarily based on a range of measures of water availability) over a large range of realistic atmospheric CO2 concentrations. We use an ensemble of simulations from of state-of-the-art climate models to analyse both equilibrium climate experiments and transient historical simulations and future projections. Our results show that dryness is, under conditions of increasing atmospheric CO2 concentrations and related global warming, generally decreasing at global scales. At regional scales we do, however, identify areas that undergo changes towards drier conditions, located primarily in subtropical climate regions and the Amazon Basin. Nonetheless, the majority of regions, especially in tropical and mid- to northern high latitudes areas, display wetting conditions in a warming world. Our results contradict previous findings and highlight the need to comprehensively assess all aspects of changes in hydroclimatological conditions at the land surface. Roderick, M. L., P. Greve, and G. D. Farquhar (2015), On the assessment of aridity with changes in atmospheric CO2, Water Resour. Res., 51, 5450-5463

  12. CHARACTERISTICS OF ARIDITY CONDITIONS IN SOUTH DOBRUDJA

    Directory of Open Access Journals (Sweden)

    A. TISCOVSCHI

    2013-04-01

    Full Text Available Characteristics of Aridity Conditions in South Dobrudja. For most people, the arid and semi-arid lands are those where precipitation is low (less than 200 mm per year, and yet enough for supplying streams capable of temporarily carrying the debris resulted from weathering, but insufficient for encouraging the development of a vegetal cover meant to protect the soil blanket against eroding agents. The drought is a major and permanent climatic risk for the Dobrudja territory as a whole and for South Dobrudja in particular, a territory where hydrographic network is underdeveloped, streams are ephemeral, and semi-endorheic areas are well developed. When the period of moisture deficiency lasts longer, it can bring about a significant water imbalance, which results in crop losses or restrictions in water consumption, thus leading to a number of economic problems. Under the circumstances, the risk of aridity expansion is significant, this being the reason why a better water management system in Romania is urgently needed. In the last decades, the numerous specialty studies undertaken in the area have emphasized an intensification of the process of dryness, because atmospheric and pedological droughts have become more and more serious. Romania is a member of the United Nations Convention to Combat Desertification (UNCCD and the World Meteorological Organization (WMO. It actively participates within the drought management network and the Drought Management Center for Southeastern Europe, which comprises 11 countries. The scope is to work together and exchange experience with the neighboring countries that have recorded positive results and acquired a rich experience in terms of drought management. The employment of appropriate pluvial indices in identifying the areas prone to aridity may prove to be convenient tool for finding practical solutions meant to mitigate the impact of this phenomenon on the local communities living in South Dobrudja.

  13. Regional flow system delineation in arid karstic basins with sparse hydrogeologic data: Cuatro Cienegas Basin, Coahuila, Mexico

    Science.gov (United States)

    Wolaver, B. D.; Sharp, J. M.; Rodriguez, J. M.

    2006-12-01

    We develop procedures for the delineation of regional groundwater flow systems in arid, karstic basins with sparse hydrogeologic data using surface topography data, geologic mapping, permeability data, chloride concentrations of groundwater and precipitation, and measured discharge data. Aquifers are characterized using geographic information systems (GIS) for groundwater catchment delineation, an analytical model for interbasin flow evaluation, a chloride balance approach for recharge estimation, and a water budget for mapping contributing catchments over a 160,000 km2 region (24.87° to 28.70° north latitude and 100.68° west to 104.75° west longitude). The study area includes the Cuatro Cienegas Basin (CCB) of Coahuila, Mexico, a National Biosphere Reserve containing springs that support groundwater-dependent ecosystems and irrigated agriculture. Sustainable groundwater development is a key issue on the U.S. Mexico border. However, these procedures may be applicable in similar settings globally. We delineate groundwater catchments that contribute local and regional groundwater discharge to CCB springs and identify a large regional flow system includes mountain recharge from as both the Sierra Madre Oriental and Occidental.

  14. Analysis list: Arid1a [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Arid1a Adipocyte + mm9 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/target/Arid1a....1.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/target/Arid1a.5.tsv http://dbarchive.biosciencedbc.jp/...kyushu-u/mm9/target/Arid1a.10.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/colo/Arid1a.Adipocyte.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/colo/Adipocyte.gml ...

  15. Diatoms as a fingerprint of sub-catchment contributions to meso-scale catchment runoff

    Science.gov (United States)

    Klaus, Julian; Wetzel, Carlos E.; Martinez-Carreras, Nuria; Ector, Luc; Pfister, Laurent

    2014-05-01

    In recent years, calls were made for new eco-hydrological approaches to improve understanding of hydrological processes. Recently diatoms, one of the most common and diverse algal groups that can be easily transported by flowing water due to their small size (~10-200 µm), were used to detect the onset and cessation of surface runoff to small headwater streams and constrain isotopic and hydro-chemical hydrograph separation methods. While the method showed its potential in the hillslope-riparian zone-stream continuum of headwater catchments, the behavior of diatoms and their use for hydrological process research in meso-scale catchments remains uncertain. Diatoms can be a valuable support for isotope and hydro-chemical tracer methods when these become ambiguous with increasing scale. Distribution and abundance of diatom species is controlled by various environmental factors (pH, soil type, moisture conditions, exposition to sunlight, etc.). We therefore hypothesize that species abundance and composition can be used as a proxy for source areas. This presentation evaluates the potential for diatoms to trace source-areas in the nested meso-scale Attert River basin (250 km2, Luxembourg, Europe). We sampled diatom populations in streamwater during one flood event in Fall 2011 in 6 sub-catchments and the basin outlet - 17 to 28 samples/catchment for the different sampling locations. Diatoms were classified and counted in every individual sample. In total more than 400 diatom species were detected. Ordination analysis revealed a clear distinction between communities sampled in different sub-catchments. The species composition at the catchment outlet reflects a mixing of the diatom composition originating from different sub-catchments. This data suggests that diatoms indeed can reflect the geographic origin of stream water at the catchment outlet. The centroids of the ordination analysis might be linked to the physiographic characteristics (geology and land use) of the

  16. Water Use and Management in Semiarid Regions - A Distributed Modelling Approach in the Verlorenvlei Catchment, South Africa

    Science.gov (United States)

    Fleischer, Melanie; Kralisch, Sven; Fink, Manfred; Pfennig, Björn; Butchart-Kuhlmann, Daniel; Meinhardt, Markus; de Clercq, Willem

    2016-04-01

    Hydrological modelling is a useful method to predict water availability and environmental impacts in a range of climate and land use change scenarios. One of the major challenges to accurate predictions using hydrological modelling in semi-arid areas is the high temporal and spatial variability of rainfall events and the associated uncertainty of related process parameters. Limited and often unreliable climate observations can cause additional problems. These particular circumstances are well documented for many catchments in the world, including semi-arid parts of South Africa. An accurate assessment of water quality and quantity is however crucial for sustainable water resource management, which is often difficult under changing environmental conditions such as climate and land use change. This situation can be found in the Verlorenvlei catchment, a part of the Sandveld area located in the Western Cape region of South Africa. Extensive dry periods in combination with an increasing domestic water demand, expanding irrigation agriculture and expected reducing rainfall due to climate change present a challenging setup for water management in this region. The catchment is a highly sensitive area with one of the most important estuary systems in the Western Cape region, containing significant natural wetlands with high biodiversity and numerous endemic species. With very limited surface water resources, most settlements and irrigation systems in the region are mainly dependent on groundwater. As a result of the particular conditions, the use of improved management techniques, such as centre pivot irrigation and contour-bank farming, are necessary. The distributed, process-oriented hydrological modelling system JAMS/J2000 is used and evaluated to assess water availability within the catchment under different climate and land-use change scenarios. The first phase has involved configuring the model to accurately represent the specific natural conditions of the

  17. Catchment scale afforestation for mitigating flooding

    Science.gov (United States)

    Barnes, Mhari; Quinn, Paul; Bathurst, James; Birkinshaw, Stephen

    2016-04-01

    After the 2013-14 floods in the UK there were calls to 'forest the uplands' as a solution to reducing flood risk across the nation. At present, 1 in 6 homes in Britain are at risk of flooding and current EU legislation demands a sustainable, 'nature-based solution'. However, the role of forests as a natural flood management technique remains highly controversial, due to a distinct lack of robust evidence into its effectiveness in reducing flood risk during extreme events. SHETRAN, physically-based spatially-distributed hydrological models of the Irthing catchment and Wark forest sub-catchments (northern England) have been developed in order to test the hypothesis of the effect trees have on flood magnitude. The advanced physically-based models have been designed to model scale-related responses from 1, through 10, to 100km2, a first study of the extent to which afforestation and woody debris runoff attenuation features (RAFs) may help to mitigate floods at the full catchment scale (100-1000 km2) and on a national basis. Furthermore, there is a need to analyse the extent to which land management practices, and the installation of nature-based RAFs, such as woody debris dams, in headwater catchments can attenuate flood-wave movement, and potentially reduce downstream flood risk. The impacts of riparian planting and the benefits of adding large woody debris of several designs and on differing sizes of channels has also been simulated using advanced hydrodynamic (HiPIMS) and hydrological modelling (SHETRAN). With the aim of determining the effect forestry may have on flood frequency, 1000 years of generated rainfall data representative of current conditions has been used to determine the difference between current land-cover, different distributions of forest cover and the defining scenarios - complete forest removal and complete afforestation of the catchment. The simulations show the percentage of forestry required to have a significant impact on mitigating

  18. Groundwater and surface-water interactions and impacts of human activities in the Hailiutu catchment, northwest China

    Science.gov (United States)

    Yang, Zhi; Zhou, Yangxiao; Wenninger, Jochen; Uhlenbrook, Stefan; Wang, Xusheng; Wan, Li

    2017-02-01

    The interactions between groundwater and surface water have been significantly affected by human activities in the semi-arid Hailiutu catchment, northwest China. Several methods were used to investigate the spatial and temporal interactions between groundwater and surface water. Isotopic and chemical analyses of water samples determined that groundwater discharges to the Hailiutu River, and mass balance equations were employed to estimate groundwater seepage rates along the river using chemical profiles. The hydrograph separation method was used to estimate temporal variations of groundwater discharges to the river. A numerical groundwater model was constructed to simulate groundwater discharges along the river and to analyze effects of water use in the catchment. The simulated seepage rates along the river compare reasonably well with the seepage estimates derived from a chemical profile in 2012. The impacts of human activities (river-water diversion and groundwater abstraction) on the river discharge were analyzed by calculating the differences between the simulated natural groundwater discharge and the measured river discharge. Water use associated with the Hailiutu River increased from 1986 to 1991, reached its highest level from 1992 to 2000, and decreased from 2001 onwards. The reduction of river discharge might have negative impacts on the riparian ecosystem and the water availability for downstream users. The interactions between groundwater and surface water as well as the consequences of human activities should be taken into account when implementing sustainable water resources management in the Hailiutu catchment.

  19. Tectonic uplift and denudation rate influence soil chemical weathering intensity in a semi-arid environment, southeast Spain: physico-chemical and mineralogical evidence

    Science.gov (United States)

    Ameijeiras-Mariño, Yolanda; Opfergelt, Sophie; Schoonejans, Jérôme; Vanacker, Veerle; Sonnet, Philippe; Delmelle, Pierre

    2015-04-01

    Tectonic uplift is known to influence denudation rates. Denudation, including chemical weathering and physical erosion, affects soil production rates and weathering intensities. At topographic steady state, weathering can be transport- or weathering-limited. In the transport-limited regime, low denudation rates should lead to comparatively high weathering intensities, while in the weathering-limited case high denudation rates are associated with lower weathering intensities. Here, we test if this relationship applies to semi-arid environments where chemical weathering is generally slow. Three catchments (EST, FIL and CAB) were studied in the Internal Zone of the Betic Cordillera in southeast Spain, spanning a range of increasing uplift rates (10-170 mm/kyr) and increasing denudation rates (20-250 mm/kyr) from EST to CAB. In each catchment, two ridgetop soil profiles were sampled down to the bedrock. The three catchments have similar vegetation and climatic conditions, with precipitation of 250- 315 mm/yr and mean annual temperature of 15-17 °C. The mineralogy of the bedrock, as determined by XRD, is similar across the three catchments and is characterized by the presence of quartz, muscovite, clinochlore, biotite and plagioclase. This primary mineral assemblage is also found in the catchment soils, indicating that the soils studied derive from the same parent material. The soil clay-size fraction is dominated by kaolinite, vermiculite and illite. However, the proportions of the soil primary and secondary minerals vary between the catchment sites. The abundance of biotite decreases from CAB (14%) to EST (4%), whereas the quartz and clay contents show an opposite tendency (from 30 to 69% and 9.9 to 14.3%, respectively). Further, the abundance of vermiculite increases from CAB to EST. The results are interpreted in terms of increasing weathering intensity from CAB to EST by weathering of biotite into vermiculite and enrichment of soils on more weathering resistant

  20. Water balance modelling in a semi-arid environment with limited in-situ data: remote sensing coupled with satellite gravimetry, Lake Manyara, East African Rift, Tanzania

    Directory of Open Access Journals (Sweden)

    D. Deus

    2011-09-01

    Full Text Available Accurate and up to date information on the status and trends of water balance is needed to develop strategies for conservation and the sustainable management of water resources. The purpose of this research is to estimate water balance in a semi-arid environment with limited in-situ data by using a remote sensing approach. We focus on the Lake Manyara catchment, located within the East African Rift of northern Tanzania. We use remote sensing and a semi-distributed hydrological model to study the spatial and temporal variability of water balance parameters within Manyara catchment. Satellite gravimetry GRACE data is used to verify the trend of the water balance result. The results show high spatial and temporal variations and characteristics of a semi-arid climate with high evaporation and low rainfall. We observe that the Lake Manyara water balance and GRACE equivalent water depth show comparable trends a decrease after 2002 followed by a sharp increase in 2006–2007. Despite the small size of Lake Manyara, GRACE data are useful and show great potential for hydrological research on smaller un-gauged lakes and catchments in semi-arid environments. Our modelling confirms the importance of the 2006–2007 Indian Ocean Dipole fluctuation in replenishing the groundwater reservoirs of East Africa. The water balance information can be used for further analysis of lake variations in relation to soil erosion, climate and land cover/land use change as well as different lake management and conservation scenarios. We demonstrate that water balance modelling can be performed accurately using remote sensing data even in complex climatic settings.

  1. Biogeochemical redox cycling of arsenic in mine-impacted lake sediments and co-existing pore waters near Giant Mine, Yellowknife Bay, Canada

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, C.F. [Queen' s University, Department of Geological Sciences and Geological Engineering, Kingston, K7L 3N6 (Canada); Jamieson, H.E., E-mail: jamieson@geol.queensu.ca [Queen' s University, Department of Geological Sciences and Geological Engineering, Kingston, K7L 3N6 (Canada); Kyser, T.K. [Queen' s University, Department of Geological Sciences and Geological Engineering, Kingston, K7L 3N6 (Canada); Praharaj, T.; Fortin, D. [University of Ottawa, Department of Earth Sciences, Ottawa, K1A 3N5 (Canada)

    2010-02-15

    Lacustrine sediments, submerged tailings, and their pore waters have been collected at several sites in Yellowknife Bay, Great Slave Lake, Canada, in order to investigate the biogeochemical controls on the remobilization of As from mining-impacted materials under different depositional conditions. Radiometric dating confirms that a mid-core enrichment of Pb, Zn, Cu and Sb corresponds to the opening of a large Au mine 60 a ago. This was evident even in a relatively remote site. Arsenic was enriched at mid-core, coincident with mining activity, but clearly exhibited post-depositional mobility, migrating upwards towards the sediment water interface (SWI) as well as down-core. Deep-water (15 m) Yellowknife Bay sediments that contain buried mine waste are suboxic, relatively organic-rich and abundant in microbes with As in pore waters and sediments reaching 585 {mu}g/L and 1310 mg/kg, respectively. Late summer pore waters show equal proportions of As(III) and As(V) (16-415 {mu}g/L) whereas late winter pore waters are dominated by As(III) (284-947 {mu}g/L). This can be explained by As(III) desorption mechanisms associated with the conversion of FeS to FeS{sub 2} and the reduction of As(V) to As(III) through the oxidation of dissolved sulfide, both microbially-mediated processes. Processes affecting As cycling involve the attenuating efficiency of the oxic zone at the SWI, sediment redox heterogeneity and the reductive dissolution of Fe(hydr)oxides by labile organic matter, temporarily and spatially variable.

  2. Rainfall Characterization In An Arid Area

    OpenAIRE

    Bazaraa, A. S.; Ahmed, Shamim

    1991-01-01

    The objective of this work is to characterize the rainfall in Doha which lies in an arid region. The rainfall data included daily rainfall depth since 1962 and the hyetographs of the individual storms since 1976. The rainfall is characterized by high variability and severe thunderstorms which are of limited geographical extent. Four probability distributions were used to fit the maximum rainfall in 24 hours and the annual rainfall depth. The extreme value distribution was found to have the be...

  3. VOCs in Arid soils: Technology summary

    Energy Technology Data Exchange (ETDEWEB)

    1994-02-01

    The Volatile Organic Compounds In Arid Soils Integrated Demonstration (VOC-Arid ID) focuses on technologies to clean up volatile organic compounds and associated contaminants in soil and groundwater at arid sites. The initial host site is the 200 West Area at DOE`s Hanford site in southeastern Washington state. The primary VOC contaminant is carbon tetrachloride, in association with heavy metals and radionuclides. An estimated 580--920 metric tons of carbon tetrachloride were disposed of between 1955 and 1973, resulting in extensive soil and groundwater contamination. The VOC-Arid ID schedule has been divided into three phases of implementation. The phased approach provides for: rapid transfer of technologies to the Environmental Restoration (EM-40) programs once demonstrated; logical progression in the complexity of demonstrations based on improved understanding of the VOC problem; and leveraging of the host site EM-40 activities to reduce the overall cost of the demonstrations. During FY92 and FY93, the primary technology demonstrations within the ID were leveraged with an ongoing expedited response action at the Hanford 200 West Area, which is directed at vapor extraction of VOCs from the vadose (unsaturated) zone. Demonstration efforts are underway in the areas of subsurface characterization including: drilling and access improvements, off-gas and borehole monitoring of vadose zone VOC concentrations to aid in soil vapor extraction performance evaluation, and treatment of VOC-contaminated off-gas. These current demonstration efforts constitute Phase 1 of the ID and, because of the ongoing vadose zone ERA, can result in immediate transfer of successful technologies to EM-40.

  4. Development of catchment research, with particular attention to Plynlimon and its forerunner, the East African catchments

    Directory of Open Access Journals (Sweden)

    2007-01-01

    Full Text Available Dr J.S.G. McCulloch was deeply involved in the establishment of research catchments in East Africa and subsequently in the UK to investigate the hydrological consequences of changes in land use. Comparison of these studies provides an insight into how influential his inputs and direction have been in the progressive development of the philosophy, the instrumentation and the analytical techniques now employed in catchment research. There were great contrasts in the environments: tropical highland (high radiation, intense rainfall vs. temperate maritime (low radiation and frontal storms, contrasting soils and vegetation types, as well as the differing social and economic pressures in developing and developed nations. Nevertheless, the underlying scientific philosophy was common to both, although techniques had to be modified according to local conditions. As specialised instrumentation and analytical techniques were developed for the UK catchments many were also integrated into the East African studies. Many lessons were learned in the course of these studies and from the experiences of other studies around the world. Overall, a rigorous scientific approach was developed with widespread applicability. Beyond the basics of catchment selection and the quantification of the main components of the catchment water balance, this involved initiating parallel process studies to provide information on specific aspects of catchment behaviour. This information could then form the basis for models capable of extrapolation from the observed time series to other periods/hydrological events and, ultimately, the capability of predicting the consequences of changes in catchment land management to other areas in a range of climates.

  5. Aridity increases below-ground niche breadth in grass communities

    Science.gov (United States)

    Butterfield, Bradley J.; Bradford, John B.; Munson, Seth M.; Gremer, Jennifer R.

    2017-01-01

    Aridity is an important environmental filter in the assembly of plant communities worldwide. The extent to which root traits mediate responses to aridity, and how they are coordinated with leaf traits, remains unclear. Here, we measured variation in root tissue density (RTD), specific root length (SRL), specific leaf area (SLA), and seed size within and among thirty perennial grass communities distributed along an aridity gradient spanning 190–540 mm of climatic water deficit (potential minus actual evapotranspiration). We tested the hypotheses that traits exhibited coordinated variation (1) among species, as well as (2) among communities varying in aridity, and (3) functional diversity within communities declines with increasing aridity, consistent with the “stress-dominance” hypothesis. Across communities, SLA and RTD exhibited a coordinated response to aridity, shifting toward more conservative (lower SLA, higher RTD) functional strategies with increasing aridity. The response of SRL to aridity was more idiosyncratic and was independent of variation in SLA and RTD. Contrary to the stress-dominance hypothesis, the diversity of SRL values within communities increased with aridity, while none of the other traits exhibited significant diversity responses. These results are consistent with other studies that have found SRL to be independent of an SLA–RTD axis of functional variation and suggest that the dynamic nature of soil moisture in arid environments may facilitate a wider array of resource capture strategies associated with variation in SRL.

  6. Inverse distributed hydrological modelling of alpine catchments

    Directory of Open Access Journals (Sweden)

    H. Kunstmann

    2005-12-01

    Full Text Available Even in physically based distributed hydrological models, various remaining parameters must be estimated for each sub-catchment. This can involve tremendous effort, especially when the number of sub-catchments is large and the applied hydrological model is computationally expensive. Automatic parameter estimation tools can significantly facilitate the calibration process. Hence, we combined the nonlinear parameter estimation tool PEST with the distributed hydrological model WaSiM. PEST is based on the Gauss-Marquardt-Levenberg method, a gradient-based nonlinear parameter estimation algorithm. WaSiM is a fully distributed hydrological model using physically based algorithms for most of the process descriptions.

    WaSiM was applied to the alpine/prealpine Ammer River catchment (southern Germany, 710 km2 in a 100×100 m2 horizontal resolution. The catchment is heterogeneous in terms of geology, pedology and land use and shows a complex orography (the difference of elevation is around 1600 m. Using the developed PEST-WaSiM interface, the hydrological model was calibrated by comparing simulated and observed runoff at eight gauges for the hydrologic year 1997 and validated for the hydrologic year 1993. For each sub-catchment four parameters had to be calibrated: the recession constants of direct runoff and interflow, the drainage density, and the hydraulic conductivity of the uppermost aquifer. Additionally, five snowmelt specific parameters were adjusted for the entire catchment. Altogether, 37 parameters had to be calibrated. Additional a priori information (e.g. from flood hydrograph analysis narrowed the parameter space of the solutions and improved the non-uniqueness of the fitted values. A reasonable quality of fit was achieved. Discrepancies between modelled and observed runoff were also due to the small number of meteorological stations and corresponding interpolation artefacts in the orographically complex

  7. Runoff generation mechanism at two distinct headwater catchments - isotopic evidence

    Science.gov (United States)

    Dohnal, Michal; Votrubová, Jana; Šanda, Martin; Tesař, Miroslav; Vogel, Tomáš; Dušek, Jaromír

    2016-04-01

    Data from two headwater catchments indicate considerably different runoff formation mechanisms. The contributions of different surface and subsurface runoff mechanisms to the catchment discharge formation at these two small forested headwater catchments are studied with help of the natural isotopic signatures of the observed fluxes. The Uhlirska catchment (1.78 sq. km, Jizera Mts., Czech Republic) is situated in headwater area of Cerna Nisa stream. Deluviofluvial granitic sediments in the valley bottom areas (riparian zones/wetlands) are surrounded by gentle hillslopes with shallow soils developed on crystalline bedrock. The Liz catchment (0.99 sq. km, Bohemian Forest, Czech Republic) belongs to hillslope-type catchments without riparian zones situated in headwater area of Volynka River. The soil at Liz is developed on biotite paragneiss bedrock. Autocorrelation analysis of the measured catchment discharge rates reveals different hydrograph characteristics for each of the two catchments. Estimated autocorrelation lengths differ by an order of magnitude. Variations of oxygen-18 isotope concentrations in precipitation, groundwater and streamflow were analyzed. Several significant rainfall-runoff events at each of the two catchments were analyzed in detail. These events exhibit substantial difference in isotopic compositions of event and pre-event water, which facilitates hydrograph separation. Clockwise and counterclockwise hysteretic relationships between the stream discharge and its isotope concentration were identified. Results were confronted with the previously published concepts of the runoff formation at the catchments under study. The research was funded by the Czech Science Foundation, project No. 14-15201J.

  8. Calibration of a lumped nitrogen model in a Mediterranean forested catchment named Fuirosos, (Catalonia).

    Science.gov (United States)

    Medici, C.; Butturini, A.; Bernal, S.; Sabater, F.; Martin, M.; Wade, A.; Frances, F.

    2009-04-01

    Following the philosophy of the process-based INCA-N model (Wade et al., 2004), a recently developed hydrological model, LU4 was extended through the inclusion of processes representing the inorganic nitrogen cycle to create a new model of nitrogen dynamics LU4-N capable of application in Mediterranean systems, which share processes from both wet and arid/semiarid environments (Gallart et al., 2002). This new model represents an advance on the INCA-N model for which problems where observed when simulating the hydrology of Mediterranean catchments (Bernal et al., 2004). The LU4-N model integrates hydrological and N processes in catchment and simulates daily discharge and daily NO3-N and NH4-N concentration. The lumped hydrological model LU4 has been already applied to the Fuirosos catchment giving acceptable results (Medici et al., 2008). The model provides a simplified conceptualization of nitrogen cycle in soil and into the shallow perched saturated zone. It uses a zero order reaction kinetic equation to simulate the mineralization process and first order equation to simulate non-biological fixation, nitrification, denitrification, plant uptake and immobilization. The model structure includes a soil moisture threshold for all the considered soil biological processes. The model also includes two first order reaction equations to simulate the adsorption/desorption dynamic in soil. In the shallow perched aquifer, nitrification and denitrification are the only processes allowed to occur. The calibration period for the N-submodel was the same considered for the calibration of the hydrological model LU4 and it covers approximately three hydrological years (from October 1999 to August 2002). The LU4-N model was also tested against observed data recorded at Fuirosos from August 2002 to June 2003. The LU4-N model was able to match the observed daily pattern for the calibration period, while it was unable to match satisfactorily the daily observed ammonium concentration

  9. Catchment Engineering: A New Paradigm in Water Management

    Science.gov (United States)

    Quinn, P. F.; Burke, S.; O'Donnell, G. M.; Wilkinson, M.; Jonczyk, J.; Barber, N.; Nicholson, A.; Proactive Team

    2011-12-01

    Recent catchment initiatives have highlighted the need for new holistic approaches to sustainable water management. Here, a catchment engineering approach seeks to describe catchment 'function' (or role) as the principal driver for evaluating how it should be managed in the future. Catchment engineering does not seek to re-establish a natural system but seeks to work with natural processes in order to engineer landscapes so that multiple benefits accrue. This approach involves quantifying and assessing catchment change and impacts but most importantly suggests an urgent and proactive agenda for future planning. In particular, an interventionist approach to managing hydrological flow pathways across scale is proposed. It is already accepted that future management will require a range of scientific expertise and full engagement with stakeholders, namely the general public and policy makers. This inclusive concept under a catchment engineering agenda forces any consortia to commit to actively changing and perturbing the catchment system and thus learn, in situ, how to manage the environment for collective benefits. The shared cost, the design, the implementation, the evaluation and any subsequent modifications should involve all relevant parties in the consortia. This joint ownership of a 'hands on' interventionist agenda to catchment change is at the core of catchment engineering. In this paper we show a range of catchment engineering projects from the UK that have addressed multi-disciplinary approaches to flooding, pollution and ecosystem management whilst maintaining economic food production. Local scale demonstration activities, led by local champions, have proven to be an effective means of encouraging wider uptake. Catchment engineering is a concept that relies on all relevant parties within a catchment to take responsibility for the water quantity and quality that arises from the catchment. Further, any holistic solution requires a bottom up, problem solving

  10. Arid sites stakeholder participation in evaluating innovative technologies: VOC-Arid Site Integrated Demonstration

    Energy Technology Data Exchange (ETDEWEB)

    Peterson, T.S.; McCabe, G.H.; Brockbank, B.R. [and others

    1995-05-01

    Developing and deploying innovative environmental cleanup technologies is an important goal for the U.S. Department of Energy (DOE), which faces challenging remediation problems at contaminated sites throughout the United States. Achieving meaningful, constructive stakeholder involvement in cleanup programs, with the aim of ultimate acceptance of remediation decisions, is critical to meeting those challenges. DOE`s Office of Technology Development sponsors research and demonstration of new technologies, including, in the past, the Volatile Organic Compounds Arid Site Integrated Demonstration (VOC-Arid ID), hosted at the Hanford Site in Washington State. The purpose of the VOC-Arid ID has been to develop and demonstrate new technologies for remediating carbon tetrachloride and other VOC contamination in soils and ground water. In October 1994 the VOC-Arid ID became a part of the Contaminant Plume Containment and Remediation Focus Area (Plume Focus Area). The VOC Arid ID`s purpose of involving stakeholders in evaluating innovative technologies will now be carried on in the Plume Focus Area in cooperation with Site Technology Coordination Groups and Site Specific Advisory Boards. DOE`s goal is to demonstrate promising technologies once and deploy those that are successful across the DOE complex. Achieving that goal requires that the technologies be acceptable to the groups and individuals with a stake in DOE facility cleanup. Such stakeholders include groups and individuals with an interest in cleanup, including regulatory agencies, Native American tribes, environmental and civic interest groups, public officials, environmental technology users, and private citizens. This report documents the results of the stakeholder involvement program, which is an integral part of the VOC-Arid ID.

  11. Creating a catchment perspective for river restoration

    Science.gov (United States)

    Benda, L.; Miller, D.; Barquín, J.

    2011-03-01

    One of the major challenges in river restoration is to identify the natural fluvial landscape in catchments with a long history of river control. Intensive land use on valley floors often predates the earliest remote sensing: levees, dikes, dams, and other structures alter valley-floor morphology, river channels and flow regimes. Consequently, morphological patterns indicative of the fluvial landscape including multiple channels, extensive floodplains, wetlands, and fluvial-riparian and tributary-confluence dynamics can be obscured, and information to develop appropriate and cost effective river restoration strategies can be unavailable. This is the case in the Pas River catchment in northern Spain (650 km2), in which land use and development have obscured the natural fluvial landscape in many parts of the basin. To address this issue we coupled general principles of hydro-geomorphic processes with computer tools to characterize the fluvial landscape. Using a 5-m digital elevation model, valley-floor surfaces were mapped according to elevation above the channel and proximity to key geomorphic processes. The predicted fluvial landscape is patchily distributed according to topography, valley morphology, river network structure, and fan and terrace landforms. The vast majority of the fluvial landscape in the main segments of the Pas River catchment is presently masked by human infrastructure, with only 15% not impacted by river control structures and development. The reconstructed fluvial landscape provides a catchment scale context to support restoration planning, in which areas of potential ecological productivity and diversity could be targeted for in-channel, floodplain and riparian restoration projects.

  12. Groundwater recharge from point to catchment scale

    Science.gov (United States)

    Leterme, Bertrand; Di Ciacca, Antoine; Laloy, Eric; Jacques, Diederik

    2016-04-01

    Accurate estimation of groundwater recharge is a challenging task as only a few devices (if any) can measure it directly. In this study, we discuss how groundwater recharge can be calculated at different temporal and spatial scales in the Kleine Nete catchment (Belgium). A small monitoring network is being installed, that is aimed to monitor the changes in dominant processes and to address data availability as one goes from the point to the catchment scale. At the point scale, groundwater recharge is estimated using inversion of soil moisture and/or water potential data and stable isotope concentrations (Koeniger et al. 2015). At the plot scale, it is proposed to monitor the discharge of a small drainage ditch in order to calculate the field groundwater recharge. Electrical conductivity measurements are necessary to separate shallow from deeper groundwater contribution to the ditch discharge (see Di Ciacca et al. poster in session HS8.3.4). At this scale, two or three-dimensional process-based vadose zone models will be used to model subsurface flow. At the catchment scale though, using a mechanistic, process-based model to estimate groundwater recharge is debatable (because of, e.g., the presence of numerous drainage ditches, mixed land use pixels, etc.). We therefore investigate to which extent various types of surrogate models can be used to make the necessary upscaling from the plot scale to the scale of the whole Kleine Nete catchment. Ref. Koeniger P, Gaj M, Beyer M, Himmelsbach T (2015) Review on soil water isotope based groundwater recharge estimations. Hydrological Processes, DOI: 10.1002/hyp.10775

  13. Creating a catchment perspective for river restoration

    Directory of Open Access Journals (Sweden)

    L. Benda

    2011-03-01

    Full Text Available One of the major challenges in river restoration is to identify the natural fluvial landscape in catchments with a long history of river control. Intensive land use on valley floors often predates the earliest remote sensing: levees, dikes, dams, and other structures alter valley-floor morphology, river channels and flow regimes. Consequently, morphological patterns indicative of the fluvial landscape including multiple channels, extensive floodplains, wetlands, and fluvial-riparian and tributary-confluence dynamics can be obscured, and information to develop appropriate and cost effective river restoration strategies can be unavailable. This is the case in the Pas River catchment in northern Spain (650 km2, in which land use and development have obscured the natural fluvial landscape in many parts of the basin. To address this issue we coupled general principles of hydro-geomorphic processes with computer tools to characterize the fluvial landscape. Using a 5-m digital elevation model, valley-floor surfaces were mapped according to elevation above the channel and proximity to key geomorphic processes. The predicted fluvial landscape is patchily distributed according to topography, valley morphology, river network structure, and fan and terrace landforms. The vast majority of the fluvial landscape in the main segments of the Pas River catchment is presently masked by human infrastructure, with only 15% not impacted by river control structures and development. The reconstructed fluvial landscape provides a catchment scale context to support restoration planning, in which areas of potential ecological productivity and diversity could be targeted for in-channel, floodplain and riparian restoration projects.

  14. Analysis list: ARID3A [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available ARID3A Blood,Liver + hg19 http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/target/ARID3A.1.tsv http:...//dbarchive.biosciencedbc.jp/kyushu-u/hg19/target/ARID3A.5.tsv http://dbarchive.biosciencedb...c.jp/kyushu-u/hg19/target/ARID3A.10.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/colo/ARID3A.Blood.tsv,http:...//dbarchive.biosciencedbc.jp/kyushu-u/hg19/colo/ARID3A.Liver.tsv http://db...archive.biosciencedbc.jp/kyushu-u/hg19/colo/Blood.gml,http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/colo/Liver.gml ...

  15. Hydrodynamics of Mine Impact Burial

    Science.gov (United States)

    2002-09-01

    differential equations of the form: dq =a q+b (a 0) dt ⋅ ≠ (152) The analytical solution will take the form, (Cannon 1967) and ( Boyce and... Diprima 1997): (153) ( ) ( ) ( )q t =q 0 +b t a=0⋅ This represents ordinary integration in a single variable, . Otherwise: q =f(t) ( ) ( ) (a...ft 2 0 1 q t dt=q 0 t+ b t a=0 2 ⋅ ⋅∫ ) (155) The system of first order, linear ordinary differential equations have solutions of form, ( Boyce

  16. Similarity and scale in catchment storm response

    Science.gov (United States)

    Wood, Eric F.; Sivapalan, Murugesu; Beven, Keith

    1993-01-01

    Until recently, very little progress had been made in understanding the relationship between small-scale variability of topography, soil, and rainfalls and the storm response seen at the catchment scale. The work reviewed here represents the first attempt at a systematic theoretical framework for such understanding in the context of surface runoff generation by different processes. The parameterization of hydrological processes over a range of scales is examined, and the concept of the 'representative elementary area' (REA) is introduced. The REA is a fundamental scale for catchment modeling at which continuum assumptions can be applied for the spatially variable controls and parameters, and spatial patterns no longer have to be considered explicitly. The investigation of scale leads into the concept of hydrologic similarity in which the effects of the environmental controls on runoff generation and flood frequency response be investigated independently of catchment scale. The paper reviews the authors' initial results and hopefully will motivate others to also investigate the issues of hydrologic scale and similarity.

  17. Temporal and spatial dynamics of carbon and nitrogen in headwater snow-dominated catchments, Jemez Mountains, New Mexico

    Science.gov (United States)

    Dannemann, F. K.; Zapata, X.; McIntosh, J. C.; Perdrial, J. N.; Brooks, P. D.; Chorover, J.; Lohse, K. A.; Fricke, H. C.

    2011-12-01

    The concentration and availability of stream nutrients, particularly dissolved organic carbon (DOC) and nitrogen species, determine aquatic system productivity, and are important indicators of catchment hydrobiogeochemical processes. In semi-arid montane areas, such as the Valles Caldera National Preserve located within the Jemez River Basin, NM, an understanding of the relationship between discharge and nutrient concentrations is particularly important. Although the annual hydrograph is dominated (~40%) by spring snowmelt, similar to well studies sites in the northern Rockies, the JRB region receives a much larger percentage of precipitation associated with summer rainfall, and consequently may provide insight into how more northerly catchments will respond to changing climate. This study focuses on four headwater catchments: History Grove, La Jara, Upper Jaramillo and Upper Redondo, over two water years (2009 to 2011) to examine how nutrient concentrations vary as a function of hillslope aspect, catchment hydrologic responses, seasonality, and discharge. Stream water grab samples were collected on a monthly to weekly basis from 2009 to 2011 and analyzed for inorganic carbon (DIC), dissolved organic carbon (DOC) and nitrogen species (total dissolved nitrogen (DN), NO3, NO2, NH4). DOC and DN concentrations in stream waters from all 4 catchments are positively correlated, indicating a tight coupling of carbon and nitrogen. During dry periods (September to February) stream waters have high DIC (4.8-7.6 mg/L), and low DOC (1.6-2.7 mg/L) and DN (<0.3 mg/L) concentrations, indicating that stream water is dominated by groundwater inputs. In contrast, during spring snowmelt (March-May) stream waters have high DOC (2.9-6.2 mg/L) and DN (0.2-0.5mg/L) concentrations and low DIC (3.1-4.5mg/L) values; the majority of DN is comprised of organic-N. These results suggest flushing of shallow soil waters during snowmelt periods. High DIC (5.8-6.3mg/L), and low DOC (1.7-4.0mg/L) and

  18. Coupling stable isotope and satellite to inform a snow accumulation and melt model for data poor, semi-arid watersheds

    Science.gov (United States)

    Hublart, Paul; Sproles, Eric; Soulsby, Chris; Tetzlaff, Doerthe; Hevía, Andres

    2016-04-01

    At the most basic level watersheds catch, store, and release water. In semi-arid northern central Chile (29°-32°) snow and glacier melt dominate these basic hydrological stages. In this region precipitation is typically limited to three to five events per year that falls as snow in the High Cordillera at elevations above 3000 m a.s.l. The rugged topography and steep gradient makes snowfall rates highly variable in space and time. Despite its critical importance for water supply, high elevation meteorological data and measurements of snowpack are scarce due to limited winter access above 3000 m a.s.l. Due to the critically limited understanding of catch, store, and release processes most conceptual watershed models for this region remain speculative, are prone to over-parameterization, and greatly inhibits hydrological prediction in the region. Focused on two headwater watersheds of the Elqui River basin (1615-6040 m a.s.l., 429-566 km2) this study couples stable isotope and Moderate Resolution Imaging Spectrometer (MODIS) data to develop an improved conceptual model of how semi-arid mountain watersheds catch, store, and release water. MODIS snow-cover and land surface temperature data are used to inform an enhanced temperature-index Snow Accumulation and Melt (SAM) model. The use of remotely-sensed temperature data as input to this model is evaluated by comparison with an interpolated dataset derived from a few available meteorological stations. The outputs from the SAM model are used as inputs to a conceptual catchment model including two water stores (one standing for surface/subsurface processes and the other for deeper groundwater storage). The model is calibrated and evaluated from a Bayesian perspective using discharge data measured at the catchment outlets over a 15-year period (2000-2015). Stable isotope data collected during 2015-2016 is applied to better constrain model outputs. The combination of MODIS-based and isotope-based information proves very

  19. Analysis list: Arid3a [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Arid3a Pluripotent stem cell + mm9 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/target/Ari...d3a.1.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/target/Arid3a.5.tsv http://dbarchive.biosc...iencedbc.jp/kyushu-u/mm9/target/Arid3a.10.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/colo/Arid3a.Pluri...potent_stem_cell.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/colo/Pluripotent_stem_cell.gml ...

  20. Incorporating flood event analyses and catchment structures into model development

    Science.gov (United States)

    Oppel, Henning; Schumann, Andreas

    2016-04-01

    The space-time variability in catchment response results from several hydrological processes which differ in their relevance in an event-specific way. An approach to characterise this variance consists in comparisons between flood events in a catchment and between flood responses of several sub-basins in such an event. In analytical frameworks the impact of space and time variability of rainfall on runoff generation due to rainfall excess can be characterised. Moreover the effect of hillslope and channel network routing on runoff timing can be specified. Hence, a modelling approach is needed to specify the runoff generation and formation. Knowing the space-time variability of rainfall and the (spatial averaged) response of a catchment it seems worthwhile to develop new models based on event and catchment analyses. The consideration of spatial order and the distribution of catchment characteristics in their spatial variability and interaction with the space-time variability of rainfall provides additional knowledge about hydrological processes at the basin scale. For this purpose a new procedure to characterise the spatial heterogeneity of catchments characteristics in their succession along the flow distance (differentiated between river network and hillslopes) was developed. It was applied to study of flood responses at a set of nested catchments in a river basin in eastern Germany. In this study the highest observed rainfall-runoff events were analysed, beginning at the catchment outlet and moving upstream. With regard to the spatial heterogeneities of catchment characteristics, sub-basins were separated by new algorithms to attribute runoff-generation, hillslope and river network processes. With this procedure the cumulative runoff response at the outlet can be decomposed and individual runoff features can be assigned to individual aspects of the catchment. Through comparative analysis between the sub-catchments and the assigned effects on runoff dynamics new

  1. Acid rain project biosurveys of streams in the Wastwater catchment

    OpenAIRE

    Prigg, R.F.

    1985-01-01

    This is the Acid rain project biosurveys of streams in the Wastwater catchment produced by the North West Water Authority in 1985. This report forms part of a series on component biological investigations, identified by location or topic, within the acid rain project. Reporting of the Wastwater catchment data would not have been given priority ordinarily, but it has been brought forward to coincide with J. Robinson's reporting of his investigations of land use and liming in the catchment. Thi...

  2. Hyporheic flow pattern based on the coupling of regional and stream scales: Case of Krycklan Catchment area

    Science.gov (United States)

    Mojarrad, Morteza; Wörman, Anders; Riml, Joakim

    2016-04-01

    Water resources intense development within the past century has had an enormous impact on hydrological systems especially on rivers and groundwater resources. A river basin is a flow system involving the interaction between surface water and groundwater. This interaction occurs in terrestrial and coastal zone and even in arid and semi-arid areas, where surface water overlie on a permeable sediment. A key zone for the interaction between surface water and groundwater is the hyporheic zone, which forms by stream water that in- and exfiltrating in the permeable sediments surrounding the river corridor. Groundwater and hyporheic flows arise due to different range of topographical scales and their relative importance is investigated in this study. Krycklan is a well-monitored research catchment in which the data collection for more than 90 years has comprised hydrology, biochemistry, and aquatic ecology. The catchment is located in a boreal area of northern Sweden. The head-water streams begin in mountainous area and fall to the Baltic Sea near the city of Umea. In this paper, COMSOL Multi-physics simulation software has been used to model the subsurface flow of the whole Krycklan catchment in order to reach a comprehensive understanding of large-scale groundwater circulation and its impact of the stream hyporheic flows. The model statement is based on the 3D Laplace equation, which has been applied independently on two ranges of topographical scales to obtain a superimposed solution. Steady state simulation has been done based on the simplified assumption of constant boundary conditions of the groundwater surface and otherwise non-flow boundaries. The hydraulic head of the groundwater surface was taken as the topography, which apply as an approximation in wet climate with shallow soil layers. The results demonstrated how the ratio of the topographical amplitudes on different scales affect the size (depth) and fragmentation of the hyporheic zone. "Fragmentation" was

  3. Remote Sensing Parameterization of Land Surface Heat Fluxes over Arid and Semi-arid Areas

    Institute of Scientific and Technical Information of China (English)

    马耀明; 王介民; 黄荣辉; 卫国安; MassimoMENENTI; 苏中波; 胡泽勇; 高峰; 文军

    2003-01-01

    Dealing with the regional land surfaces heat fluxes over inhomogeneous land surfaces in arid and semi-arid areas is an important but not an easy issue. In this study, one parameterization method based on satellite remote sensing and field observations is proposed and tested for deriving the regional land surface heat fluxes over inhomogeneous landscapes. As a case study, the method is applied to the Dunhuang experimental area and the HEIFE (Heihe River Field Experiment, 1988-1994) area. The Dunhuang area is selected as a basic experimental area for the Chinese National Key Programme for Developing Basic Sciences: Research on the Formation Mecbanism and Prediction Theory of Severe Climate Disaster in China (G1998040900, 1999-2003). The four scenes of Landsat TM data used in this study are 3 June 2000,22 August 2000, and 29 January 2001 for the Dunhuang area and 9 July 1991 for the HEIFE area. The regional distributions of land surface variables, vegetation variables, and heat fluxes over inhomogeneous landscapes in arid and semi-arid areas are obtained in this study.

  4. Catchment-scale evaluation of pollution potential of urban snow at two residential catchments in southern Finland.

    Science.gov (United States)

    Sillanpää, Nora; Koivusalo, Harri

    2013-01-01

    Despite the crucial role of snow in the hydrological cycle in cold climate conditions, monitoring studies of urban snow quality often lack discussions about the relevance of snow in the catchment-scale runoff management. In this study, measurements of snow quality were conducted at two residential catchments in Espoo, Finland, simultaneously with continuous runoff measurements. The results of the snow quality were used to produce catchment-scale estimates of areal snow mass loads (SML). Based on the results, urbanization reduced areal snow water equivalent but increased pollutant accumulation in snow: SMLs in a medium-density residential catchment were two- to four-fold higher in comparison with a low-density residential catchment. The main sources of pollutants were related to vehicular traffic and road maintenance, but also pet excrement increased concentrations to a high level. Ploughed snow can contain 50% of the areal pollutant mass stored in snow despite its small surface area within a catchment.

  5. Large landslides lie low: Vertical domains of denudation processes in the arid Himalaya-Karakoram orogen

    Science.gov (United States)

    Blöthe, Jan Henrik

    2014-05-01

    Large bedrock landslides (defined here as affecting >0.1 km2 in planform area) are thought to substantially contribute to denuding active mountain belts, and limiting the growth of topographic relief produced by concurrent tectonic uplift and fluvial or glacial incision. While most research on large landslides has focused on tectonically active, humid mountain belts with varying degrees of rainstorm and earthquake activity, lesser attention has been devoted to arid mountain belts. Especially in the Himalaya, where high denudation rates are commonly associated with high landslide activity, previous work has largely ignored landslide processes in the arid compartments of the orogen. This was motivation for us to compile a landslide inventory covering the arid Himalaya-Karakoram of NW India and N Pakistan within the Indus catchment. Our data set contains 493 rock-slope failures that we compiled from published studies and mapping from remote sensing imagery. Using an empirical volume-area scaling approach we estimate the total landslide volume at >250 km3. This is more than thousand times the contemporary annual sediment load in the Indus River. We analyse the distribution of these volumetrically significant landslides with respect to the regional hypsometry, contemporary glacier cover, and the distribution of rock glaciers. We find that large bedrock landslides in the arid Himalaya-Karakoram region preferentially detach near or from below the study area's median elevation, while glaciers and rock glaciers occupy higher elevations almost exclusively. This trend holds true for both the study area and parts thereof. The largest and highest-lying landslides occur in the Karakoram mountains, where local relief exceeds 6 km, and >90% of the landslide areas lie below the region's median elevation. Our analysis reveals a hitherto unrecognized vertical layering of denudation processes, with landslides chiefly operating below the median elevation, whereas mass transport by

  6. Extreme Rainfall Impacts in Fractured Permeable Catchments

    Science.gov (United States)

    Ireson, A. M.; Butler, A. P.

    2009-12-01

    Serious groundwater flooding events have occurred on Chalk catchments in both the UK and north west Europe in the last decade, causing substantial amounts of disruption and economic damage. These fractured, permeable catchments are characterized by low surface runoff, high baseflow indices and strongly attenuated streamflow hydrographs. They have a general resilience to drought and pluvial/fluvial flooding. The small pore size of the Chalk matrix (~ 1 µm) exerts a high suction, such that dynamic storage is primarily due to the fractures, and amounts to ~ 1% of the total volume. As a result, under sustained rainfall the water table can rise up to exceptional levels leading to surface water emergence from springs and valleys. Floodwater may slowly drain with the topography, or, in localized depressions, it may simply pond until the groundwater levels decline. In winter 2000/1, a sequence of individually unexceptional rainfall events over several months led to large scale flooding in the Pang catchment, Berkshire, UK. By contrast, an extreme rainfall event on 20th July 2007 in the same catchment caused a very rapid response at the water table, but due to the antecedent conditions did not lead to flooding. The objective of this study is to quantify how the water table in a fractured permeable catchment responds to different types of rainfall, and the implications of this for groundwater flooding. We make use of measurements from the Pang catchment, including: rainfall (tipping bucket gauges); actual evaporation (eddy flux correlation); soil water content (profile probes and neutron probes); near surface matric potential (tensiometers and equitensiometers); deep (>10m) matric potential (deep jacking tensiometers); and water table elevation (piezometers). Conventional treatment of recharge in Chalk aquifers considers a fixed bypass component of rainfall, normally 15%, to account for the role of the fractures. However, interpretation of the field data suggest three modes

  7. Lithogenic and cosmogenic tracers in catchment hydrology

    Energy Technology Data Exchange (ETDEWEB)

    Nimz, G.J.

    1995-01-01

    A variety of physical processes affect solute concentrations within catchment waters. The isotopic compositions of the solutes can indicate which processes have determined the observed concentrations. These processes together constitute the physical history of the water, which is one of the primary concerns in hydrology. Many groundwater solutes are derived as a result of interaction between the water and the rock and/or soil within the system. These are termed {open_quotes}lithogenic{close_quotes} solutes. The isotopic compositions of these solutes provide information regarding rock-water interactions. Many other solutes have their isotopic compositions determined both internally and externally to the catchment system. Important members of this group include solutes that have isotopic compositions produced by atomic particle interactions with other nuclides. The source of the atomic particles can be cosmic radiation (producing {open_quotes}cosmogenic{close_quotes} nuclides in the atmosphere and land surface), anthropogenic nuclear reactions (producing {open_quotes}thermonuclear{close_quotes} nuclides), or radioactive and fission decay of naturally-occurring elements, such as U and Th (producing {open_quotes}in-situ{close_quotes} lithogenic nuclides in the deep subsurface). Current language usage often combines all of the atomic particle-produced nuclides under the heading {open_quotes}cosmogenic nuclides{close_quotes}, and for simplicity we will often follow that usage, although always clearly indicating which variety is being discussed. This paper addresses the processes that affect the lithogenic and cosmogenic solute compositions in groundwater, and how these compositions can therefore be used in integrative ways to understand the physical history of groundwater within a catchment system.

  8. Describing Ecosystem Complexity through Integrated Catchment Modeling

    Science.gov (United States)

    Shope, C. L.; Tenhunen, J. D.; Peiffer, S.

    2011-12-01

    Land use and climate change have been implicated in reduced ecosystem services (ie: high quality water yield, biodiversity, and agricultural yield. The prediction of ecosystem services expected under future land use decisions and changing climate conditions has become increasingly important. Complex policy and management decisions require the integration of physical, economic, and social data over several scales to assess effects on water resources and ecology. Field-based meteorology, hydrology, soil physics, plant production, solute and sediment transport, economic, and social behavior data were measured in a South Korean catchment. A variety of models are being used to simulate plot and field scale experiments within the catchment. Results from each of the local-scale models provide identification of sensitive, local-scale parameters which are then used as inputs into a large-scale watershed model. We used the spatially distributed SWAT model to synthesize the experimental field data throughout the catchment. The approach of our study was that the range in local-scale model parameter results can be used to define the sensitivity and uncertainty in the large-scale watershed model. Further, this example shows how research can be structured for scientific results describing complex ecosystems and landscapes where cross-disciplinary linkages benefit the end result. The field-based and modeling framework described is being used to develop scenarios to examine spatial and temporal changes in land use practices and climatic effects on water quantity, water quality, and sediment transport. Development of accurate modeling scenarios requires understanding the social relationship between individual and policy driven land management practices and the value of sustainable resources to all shareholders.

  9. Evaluation of TOPLATS on three Mediterranean catchments

    Science.gov (United States)

    Loizu, Javier; Álvarez-Mozos, Jesús; Casalí, Javier; Goñi, Mikel

    2016-08-01

    Physically based hydrological models are complex tools that provide a complete description of the different processes occurring on a catchment. The TOPMODEL-based Land-Atmosphere Transfer Scheme (TOPLATS) simulates water and energy balances at different time steps, in both lumped and distributed modes. In order to gain insight on the behavior of TOPLATS and its applicability in different conditions a detailed evaluation needs to be carried out. This study aimed to develop a complete evaluation of TOPLATS including: (1) a detailed review of previous research works using this model; (2) a sensitivity analysis (SA) of the model with two contrasted methods (Morris and Sobol) of different complexity; (3) a 4-step calibration strategy based on a multi-start Powell optimization algorithm; and (4) an analysis of the influence of simulation time step (hourly vs. daily). The model was applied on three catchments of varying size (La Tejeria, Cidacos and Arga), located in Navarre (Northern Spain), and characterized by different levels of Mediterranean climate influence. Both Morris and Sobol methods showed very similar results that identified Brooks-Corey Pore Size distribution Index (B), Bubbling pressure (ψc) and Hydraulic conductivity decay (f) as the three overall most influential parameters in TOPLATS. After calibration and validation, adequate streamflow simulations were obtained in the two wettest catchments, but the driest (Cidacos) gave poor results in validation, due to the large climatic variability between calibration and validation periods. To overcome this issue, an alternative random and discontinuous method of cal/val period selection was implemented, improving model results.

  10. Uses of tree legumes in semi-arid regions

    Energy Technology Data Exchange (ETDEWEB)

    Felker, P.

    1980-01-01

    Uses of tree legumes in semi-arid and arid regions are reviewed. This review is divided into sections according to the following general use categories: fuels; human food; livestock food; to increase yields of crops grown beneath their canopies;and control of desertification. (MHR)

  11. Developing inorganic carbon-based radiocarbon chronologies for Holocene lake sediments in arid NW China

    Science.gov (United States)

    Zhang, Jiawu; Ma, Xueyang; Qiang, Mingrui; Huang, Xiaozhong; Li, Shuang; Guo, Xiaoyan; Henderson, Andrew C. G.; Holmes, Jonathan A.; Chen, Fahu

    2016-07-01

    Inorganic carbonates are often used to establish radiocarbon (14C) chronologies for lake sediments when terrestrial plant remains (TPR) are rare or when bulk organic matter is insufficient for dating, a problem that is common for many lakes in arid regions. However, the reservoir effect (RE), as well as old carbon contributed from the lakes catchment make it difficult to establish reliable chronologies. Here we present a systematic study of inorganic 14C ages of two lake-sediment sequences, one from a small-enclosed saline lake - Lake Gahai in Qaidam Basin, and the other from a large freshwater lake - Lake Bosten in Xinjiang. Modern dissolved inorganic carbon (DIC) of the lakes, paleo-lake sediments exposed in the catchment, and mollusk shells in core sediments from Lake Gahai were dated to assess the RE and the contribution of pre-aged carbon to the old ages in the cores. We propose a statistical regression to assess more than one RE for the 14C carbonate ages within our sedimentary sequences. Old radiocarbon ages contributed by detrital carbonates were assessed by comparing the ages of mollusk shells with those of carbonates at the same sediment depths. We established the RE of the authigenic component and assessed detrital old carbon contributions to our two sites, and this was used to correct the 14C ages. Based on this approach, we developed age models for both cores, and tested them using 210Pb ages in both cores and TPR-based 14C-ages recovered from Lake Bosten. We further tested our age models by comparing carbonate-based oxygen isotope (δ18O) records from both lakes to an independently-dated regional speleothem δ18O record. Our results suggest if sedimentary sequences are densely dated and the RE and the contribution of old carbon from detrital carbonates can be ascertained, robust chronological frameworks based on carbonate-based 14C determinations can be established.

  12. Design of a Rainwater Catchment System

    OpenAIRE

    Neil Cammardella

    2011-01-01

    Certain dimensions of a rainwater catchment and storage system were optimized using climatological and sociological data. Using only daily demand and average daily rain fall data, the following dimensions were optimized: 1) The horizontal roof area needed to collect the daily demand of water, 2) The tank size needed to store all the water collected during a heavy rain event, 3) When full, how long the tank will be able to provide water without rain, and 4) The diameter of the outlet flow orif...

  13. Groundwater seepage controls salinity in a hydrologically terminal basin of semi-arid northwest Australia

    Science.gov (United States)

    Skrzypek, Grzegorz; Dogramaci, Shawan; Rouillard, Alexandra; Grierson, Pauline F.

    2016-11-01

    Very small groundwater outflows have the potential to significantly impact the hydrochemistry and salt accumulation processes of notionally terminal basins in arid environments. However, this limited groundwater outflow can be very difficult to quantify using classical water budget calculations due to large uncertainties in estimates of evaporation and evapotranspiration rates from the surface of dry lake beds. In this study, we used a dimensionless time evaporation model to estimate the range of groundwater outflow required to maintain salinity levels observed at the Fortescue Marsh (FM), one of the largest wetlands of semi-arid northwest Australia (∼1100 km2). The groundwater outflow from aquifers underlying the FM to the Lower Fortescue catchment is constrained by an extremely low hydraulic gradient of flood water is fresh to brackish, and salt efflorescences are very sparse and evident only when the FM is dry. We show that if the FM was 100% "leakage free" i.e., a true terminal basin, groundwater would have achieved halite saturation (>300 g/L) after ∼45 ka. We calculated that only a very small seepage of ∼2G L/yr (∼0.03% of the FM water volume) is sufficient to maintain current salinity conditions. The minimum time required to develop the current hydrochemical groundwater composition under the FM ranges from ∼60 to ∼165 ka. We conclude that a dimensionless time evaporation model versus inflow over outflow ratio model is likely more suitable than classical water budget calculations for determining outflow from large saline lakes and to estimate groundwater seepage from hydrologically terminal basins.

  14. CHARACTERISTICS AND CONSTRUCTION OF LANDSCAPE???ECOLOGY IN ARID REGIONS

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    This paper analyzes the characteristics of the landscape structures and landacape ecological processes in arid regions of China. Landscape structure is simplicity and homogeneity with the pattern of desert-oasis-river and canal corridor. The spatial distribution of landscape heterogeneity mosaics is relatively dependent on water resources. In arid regions,the landscape changes rapidly and extensively because of the sensitive landscape ecosystems and fragile regional ecosystems.For the sustainable development of arid regions, the theories and methods for the eco-environmental construction and the strategies of ecological construction in the arid regions were proposed in the view of landscape ecology. Keynote subjects of landscape ecology were also discussed. The paper points out that protecting and increasing landscape diversity and heterogeneity are critical to control ecological safety in arid regions.

  15. Flood prevention dams for arid regions at a micro-scale sub-catchment, case study: Tabuk, Saudi Arabia.

    Science.gov (United States)

    Abushandi, Eyad

    2016-12-01

    Unexpected flash flooding is one of the periodic hydrological problems affecting the city of Tabuk in Saudi Arabia. The region has high potential for floods as it suffers high rainfall intensity in a short time and also has high urbanization rates and topographic complexity. Constructing flood prevention dams is one option to solve this problem. A cost-effective design requires a detailed feasibility study and analysis for the selection of suitable sites. The aim of this study was to develop a method for selecting a suitable site for flood protection dams in the Abu Saba'a district, the most affected part of the city of Tabuk during the flash flood in January 2013. Spatial analysis was applied using Landsat Thematic Mapper images and Shuttle Radar Topography Mission digital elevation model to select a site in the Abu Saba'a area. A simple model using ArcGIS was built including all suggested parameters. The results showed the best site for a dam was 2 km distance backfrom the area, where all parameter values matched. The results showed that the dynamic properties of land cover can affect site selection. It is therefore suggested that more field and hydrological data should be gathered for greater accuracy.

  16. Possible climate change impacts on water resources availability in a large semi-arid catchment in Northeast Brazil.

    NARCIS (Netherlands)

    Bronstert, Axel; Güntner, Andreas; Araújo, de José Carlos; Jaeger, Annekathrin; Krol, Maarten

    2005-01-01

    The semiarid region of Northeast Brazil is characterized by water scarcity, vulnerability of natural resources, and pronounced climatic variability. An integrated model has been developed to simulate this complex situation with an emphasis on a large-scale representation of hydrological processes an

  17. The role of macropore flow from plot to catchment scale : a study in a semi-arid area

    NARCIS (Netherlands)

    van Schaik, N.L.M.B.

    2010-01-01

    Desertification and landscape degradation is a worldwide problem, which is expected to grow in time due to unsustainable land use and climate change. In view of these problems, knowledge of the interaction between vegetation, soil moisture and surface runoff, with subsequent erosion risk is essentia

  18. The current bioenergy production potential of semi-arid and arid regions in sub-Saharan Africa

    NARCIS (Netherlands)

    Wicke, B.; Smeets, E.M.W.; Watson, H.; Faaij, A.P.C.

    2011-01-01

    This article assesses the current technical and economic potential of three bioenergy production systems (cassava ethanol, jatropha oil and fuelwood) in semi-arid and arid regions of eight sub-Saharan African countries. The results indicate that the availability of land for energy production ranges

  19. Multi-scale field investigation of water flow pathways and residence times in mountainous catchments

    Science.gov (United States)

    Lyon, S. W.; Troch, P. A.; Desilets, S. E.

    2006-12-01

    The "sky islands" of Arizona and New Mexico in the southwestern United States form a unique complex of about 27 mountain ranges whose ecosystems support many perennial and ephemeral streams in an arid climate. Among these sky islands are the Santa Catalina Mountains near Tucson, AZ, with a peak elevation of 9157 ft at Mt. Lemmon. Sabino Canyon Creek is the main stream which runs on the south face of the mountain range. It usually flows from July through April with an average daily flow of approximately 0.28 m3/s (10 cfs). However, flash floods are common both during summer as a result of intense monsoon rains and during spring because of rapid snowmelt. During these events, flow increases rapidally, reaching peak flows up to 480 m3/s (16,000 cfs, July 2006). Characterizing water flow pathways and residence times in these complex catchments is important for improving flash flood warning systems, estimating mountain front recharge, managing forest and wild fires, and understanding ecosystem functions. In the summer of 2006, we set up an extensive hydrometrical and hydro-chemical monitoring network in Sabino Canyon Creek, comprising 40 tipping bucket rain gauges (two of which were equipped to automatically collect rainwater samples), 5 automatic surface water level stations (three of which were equipped with auto samplers), and 8 manual soil lysimeters. In addition, several rain and stream water grab samples were collected manually during intensive rain events. Water samples are analyzed for major ions and liquid water isotopic concentration (2H and 18O) in rain, soil, ground and surface water. The data allows for a detailed reconstruction of water flow pathways and residence times at 3 different catchment scales (2 km2, 8 km2, and 91 km2) during the recorded flow events, including the highest monsoon rainfall-runoff event ever recorded in these mountains.

  20. A detailed study on Catchment delineation for Urban areas

    Science.gov (United States)

    Sharma, B.; B M, A.; Lohani, B.; Jain, A.

    2015-12-01

    Urban flood modelling is carried out for predicting, analysing and planning of floods in urban areas. Catchment information is an important input for urban flood modelling. Automatic catchment delineation at gully gratings for urban areas using appropriate software packages/methods along with an appropriate set of input data and parameters is still a research challenge. Considering the above, the aim of this study is to (i) identify the best suitable software for automatic catchment delineation by considering gully grating as outlet (ii) understand the effect of resolution of DEM on catchments delineated (iii) understand whether to consider DEM or DSM for catchment delineation (iv) study the effect of grid based and TIN based DEM. In this study catchment delineation has been investigated considering IIT Kanpur as a study site. LiDAR data are used to generate DEM/DSM of the study area. A comparative study of catchment delineation has been carried out between ArcHydro 10.1, BASINS 4.1, ArcSWAT, WMS 7.1, and HEC-GeoHMS approaches. Catchments have been delineated for different drainage threshold areas using gully grating points as outlets and their effects have been compared for the aforementioned software. In order to understand the effect of resolution of data, DEMs of 1m and 5m resolution have been generated and compared against each other. Effects of building ridge lines and their contribution to catchment delineation has been studied by generating a DSM of 1m resolution, and comparing the results with catchments delineated using 1m DEM. In order to assess the effects of the types of DEM over catchment delineation, a grid based DEM and TIN based DEM are compared against each other using WMS 7.1 software. The results for the catchment delineation using various software illustrate that ArcHydro 10.1 performs better than any other aforementioned software. Also, it is noted that varied drainage threshold area parameters, resolutions of DEM, selection of DEM

  1. Catchment Systems Engineering: A New Paradigm in Water Management

    Science.gov (United States)

    Quinn, P. F.; Wilkinson, M. E.; Burke, S.; O'Donnell, G. M.; Jonczyk, J.; Barber, N.; Nicholson, A.

    2012-04-01

    Recent catchment initiatives have highlighted the need for new holistic approaches to sustainable water management. Catchment Systems Engineering seeks to describe catchment the function (or role) as the principal driver for evaluating how it should be managed in the future. Catchment Systems Engineering does not seek to re-establish a natural system but rather works with natural processes in order to engineer landscapes to accrue multiple benefits. The approach involves quantifying and assessing catchment change, impacts and most importantly, suggests an urgent and proactive agenda for future planning. In particular, an interventionist approach to managing hydrological flow pathways across scale is proposed. It is already accepted that future management will require a range of scientific expertise and full engagement with stakeholders. This inclusive concept under a Catchment Systems Engineering agenda forces any consortia to commit to actively changing and perturbing the catchment system and thus learn, in situ, how to manage the environment for collective benefits. The shared cost, the design, the implementation, the evaluation and any subsequent modifications should involve all relevant parties in the consortia. This joint ownership of a 'hands on' interventionist agenda to catchment change is at the core of Catchment Systems Engineering. In this paper we show a range of catchment engineering projects from the UK that have addressed multi-disciplinary approaches to flooding, pollution and ecosystem management, whilst maintaining economic food production. Examples using soft engineered features such as wetlands, ponds, woody debris dams and infiltration zones will be shown. Local scale demonstration activities, led by local champions, have proven to be an effective means of encouraging wider uptake. Evidence that impacts can be achieved at local catchment scale will be introduced. Catchment Systems Engineering is a concept that relies on all relevant parties

  2. Assessment of Runoff Contributing Catchment Areas in Rainfall Runoff Modelling

    DEFF Research Database (Denmark)

    Thorndahl, Søren Liedtke; Johansen, C.; Schaarup-Jensen, Kjeld

    2005-01-01

    to determine with significant precision the hydrological reduction factor is implemented to account all hydrological losses except the initial loss. This paper presents an inconsistency between calculations of the hydrological reduction factor, based on measurements of rainfall and runoff, and till now...... recommended literary values for residential areas. It is proven by comparing rainfall-runoff measurements from four different residential catchments that the literary values of the hydrological reduction factor are over-estimated for this type of catchments. In addition, different catchment descriptions...... are presented in order to investigate how the hydrological reduction factor depends on the level of detail regarding the catchment description. When applying a total survey of the catchment area, including all possible impervious surfaces, a hydrological reduction factor of approximately 0.5 for residential...

  3. Assessment of runoff contributing catchment areas in rainfall runoff modelling

    DEFF Research Database (Denmark)

    Thorndahl, Søren; Johansen, C.; Schaarup-Jensen, Kjeld

    2006-01-01

    to determine with significant precision the hydrological reduction factor is implemented to account all hydrological losses except the initial loss. This paper presents an inconsistency between calculations of the hydrological reduction factor, based on measurements of rainfall and runoff, and till now...... recommended literature values for residential areas. It is proven by comparing rainfall-runoff measurements from four different residential catchments that the literature values of the hydrological reduction factor are over-estimated for this type of catchment. In addition, different catchment descriptions...... are presented in order to investigate how the hydrological reduction factor depends on the level of detail regarding the catchment description. When applying a total survey of the catchment area, including all possible impervious surfaces, a hydrological reduction factor of approximately 0.5 for residential...

  4. Organic textile waste as a resource for sustainable agriculture in arid and semi-arid areas.

    Science.gov (United States)

    Eriksson, Bo G

    2017-03-01

    New vegetation in barren areas offers possibilities for sequestering carbon in the soil. Arid and semi-arid areas (ASAs) are candidates for new vegetation. The possibility of agriculture in ASAs is reviewed, revealing the potential for cultivation by covering the surface with a layer of organic fibres. This layer collects more water from humidity in the air than does the uncovered mineral surface, and creates a humid environment that promotes microbial life. One possibility is to use large amounts of organic fibres for soil enhancement in ASAs. In the context of the European Commission Waste Framework Directive, the possibility of using textile waste from Sweden is explored. The costs for using Swedish textile waste are high, but possible gains are the sale of agricultural products and increased land prices as well as environmental mitigation. The findings suggest that field research on such agriculture in ASAs should start as soon as possible.

  5. Downstream mixing of sediment and tracers in agricultural catchments: Evidence of changing sediment sources and fluvial processes?

    Science.gov (United States)

    Ralph, Timothy; Wethered, Adam; Smith, Hugh; Heijnis, Henk

    2014-05-01

    Land clearance, soil tillage and grazing in agricultural catchments have liberated sediment and altered hydrological connectivity between hillslopes and channels, leading to increased sediment availability, mobilisation and delivery to rivers. The type and amount of sediment supplied to rivers is critical for fluvial geomorphology and aquatic ecosystem health. Contemporary sediment dynamics are routinely investigated using environmental radionuclides such as caesium-137 (Cs-137) and excess lead-210 (Pb-210ex), which can provide information regarding sediment source types and fluvial processes if sediment sources can be distinguished from one another and mixing models applied to representative samples. However, downstream transport, mixing and dilution of radionuclide-labelled sediment (especially from sources with low initial concentrations) can obliterate the tracer signal; sometimes before anything of geomorphological importance happens in the catchment. Can these findings be used as evidence of sediment source variations and fluvial processes when the limits of detection (of Cs-137 in particular) are being exceeded so rapidly downstream? Sediment sources and downstream sediment dynamics were investigated in Coolbaggie Creek, a major supplier of sediment to the Macquarie River in an agricultural catchment with temperate to semi-arid climate in Australia. Radionuclides were used to discriminate between the banks and gullies (Cs-137 1.45 +/- 0.47 Bq/kg; Pb-210ex 4.67 +/- 1.93 Bq/kg). Within the trunk stream, suspended sediment, organic matter and Cs-137 and Pb-210ex concentrations declined downstream. Results from a mixing model suggest that agricultural topsoils account for 95% of fine sediment entering the channel in the upper reach (200 m2) downstream, with channel expansion and gullies contributing fine sediment to the system. A lack of topsoil being supplied to the channel suggests minimal lateral connectivity between the catchment and the trunk stream in all

  6. Determine the optimum spectral reflectance of juniper and pistachio in arid and semi-arid region

    Science.gov (United States)

    Fadaei, Hadi; Suzuki, Rikie

    2012-11-01

    Arid and semi-arid areas of northeast Iran cover about 3.4 million ha are populated by two main tree species, the broadleaf Pistacia vera. L (pistachio) and the conifer Juniperus excelsa ssp. polycarpos (Persian juniper). Natural stands of pistachio in Iran are not only environmentally important but genetically essential as seed sources for pistachio production in orchards. In this study, we estimated the optimum spectral reflectance of juniper forests and natural pistachio stands using remote sensing to help in the sustainable management and production of pistachio in Iran. In this research spectral reflectance are able to specify of multispectral from Advanced Land Observing Satellite (ALOS) that provided by JAXA. These data included PRISM is a panchromatic radiometer with a 2.5 m spatial resolution at nadir, has one band with a wavelength of 0.52-0.77 μm and AVNIR-2 is a visible and near infrared radiometer for observing land and coastal zones with a 10 m spatial resolution at nadir, has four multispectral bands: blue (0.42-0.50 μm), green (0.52-0.60 μm), red (0.61-0.69 μm), and near infrared (0.76-0.89 μm). Total ratio vegetation index (TRVI) of optimum spectral reflectance of juniper and pistachio have been evaluated. The result of TRVI for Pistachio and juniper were (R2= 0.71 and 0.55). I hope this research can provide decision of managers to helping sustainable management for arid and semi-arid regions in Iran.

  7. Novel biogeochemical fingerprinting approaches to sediment source apportionment in catchments (Invited)

    Science.gov (United States)

    Dungait, J.; Puttock, A.; Beniston, J. W.; Brazier, R. E.; Lal, R.; Collins, A.

    2013-12-01

    Apportioning the source of organic carbon in eroding sediments is important to constrain the scale of transport processes and to assess the impact of anthropogenic activity on environmental quality. Established biogeochemical techniques are used to trace organic inputs typically derived directly or indirectly from plants into soils, sediments and water using lipid biomarkers. Recently, advances in bulk and compound specific stable 13C isotope analyses have provided novel ways of exploring the source and residence times of organic matter in soils using the natural abundance stable 13C isotope signature of C3 and C4 plant end member values. However, the application of biogeochemical source tracing technologies at the molecular level at field to catchment scales has been slow to develop because of perceived problems with dilution of molecular-scale signals. This paper describes the results of recent experiments in natural and agricultural environments in the UK (Collins et al., 2013; Dungait et al., 2013) and United States (Puttock et al., 2012; Beniston et al., submitted) that have successfully applied new biogeochemical fingerprinting techniques using stable 13C isotope approaches and complementary modelling approaches to explore the transport of particulate and sediment-bound organic carbon at a range of scales from the small plot (m2) to field (ha) and small catchment (10's ha). References Beniston et al (submitted) The effects of crop residue removal on soil erosion and macronutrient dynamics on soils under no till for 42 years. Biogeosciences Collins et al (2013) Catchment source contributions to the sediment-bound organic matter degrading salmonid spawning gravels in a lowland river, southern England. Science of the Total Environment 456-457, 181-195. Dungait et al (2013) Microbial responses to the erosional redistribution of soil organic carbon in arable fields. Soil Biology and Biochemistry 60, 195-201. Puttock et al (2012) Stable carbon isotope analysis of

  8. Surface-groundwater interactions in hard rocks in Sardon Catchment of western Spain: an integrated modeling approach

    Science.gov (United States)

    Hassan, S.M. Tanvir; Lubczynski, Maciek W.; Niswonger, Richard G.; Zhongbo, Su

    2014-01-01

    The structural and hydrological complexity of hard rock systems (HRSs) affects dynamics of surface–groundwater interactions. These complexities are not well described or understood by hydrogeologists because simplified analyses typically are used to study HRSs. A transient, integrated hydrologic model (IHM) GSFLOW (Groundwater and Surface water FLOW) was calibrated and post-audited using 18 years of daily groundwater head and stream discharge data to evaluate the surface–groundwater interactions in semi-arid, ∼80 km2 granitic Sardon hilly catchment in Spain characterized by shallow water table conditions, relatively low storage, dense drainage networks and frequent, high intensity rainfall. The following hydrological observations for the Sardon Catchment, and more generally for HRSs were made: (i) significant bi-directional vertical flows occur between surface water and groundwater throughout the HRSs; (ii) relatively large groundwater recharge represents 16% of precipitation (P, 562 mm.y−1) and large groundwater exfiltration (∼11% of P) results in short groundwater flow paths due to a dense network of streams, low permeability and hilly topographic relief; deep, long groundwater flow paths constitute a smaller component of the water budget (∼1% of P); quite high groundwater evapotranspiration (∼5% of P and ∼7% of total evapotranspiration); low permeability and shallow soils are the main reasons for relatively large components of Hortonian flow and interflow (15% and 11% of P, respectively); (iii) the majority of drainage from the catchment leaves as surface water; (iv) declining 18 years trend (4.44 mm.y−1) of groundwater storage; and (v) large spatio-temporal variability of water fluxes. This IHM study of HRSs provides greater understanding of these relatively unknown hydrologic systems that are widespread throughout the world and are important for water resources in many regions.

  9. The Effect of Converting Combined Sewer Catchments to Separate Sewer Catchments

    DEFF Research Database (Denmark)

    Schaarup-Jensen, Kjeld; Rasmussen, Michael R.; Thorndahl, Søren Liedtke

    2011-01-01

    The overall objective of this paper is to contribute to the standing debate concerning the advantages of separate sewer systems compared to traditional combined sewers. By a case study this investigation reveals that a transformation of one fourth of a given total area from being combined to become...... separate sewer catchments decreases the amounts of storm water and pollutants diverted to the waste water treatment plant (WWTP) or as combined sewer overflows (CSO). But this happens at the expense of an increase in amounts of storm water and pollutants diverted to local receiving waters when detention...... ponds are not built-in the new separate sewer systems. If a total catchment area transformation – instead of only one fourth – is put through, the consequences could be fatal for receiving waters if no retention of pollutants is integrated in such a transformation....

  10. Long-term aridity changes in the western United States.

    Science.gov (United States)

    Cook, Edward R; Woodhouse, Connie A; Eakin, C Mark; Meko, David M; Stahle, David W

    2004-11-01

    The western United States is experiencing a severe multiyear drought that is unprecedented in some hydroclimatic records. Using gridded drought reconstructions that cover most of the western United States over the past 1200 years, we show that this drought pales in comparison to an earlier period of elevated aridity and epic drought in AD 900 to 1300, an interval broadly consistent with the Medieval Warm Period. If elevated aridity in the western United States is a natural response to climate warming, then any trend toward warmer temperatures in the future could lead to a serious long-term increase in aridity over western North America.

  11. Comparison of drought occurrence in selected Slovak and Czech catchments

    Science.gov (United States)

    Fendekova, Miriam; Fendek, Marian; Porubska, Diana; Hanel, Martin; Horacek, Stanislav; Martinkova, Marta; Vizina, Adam

    2014-05-01

    The presented study is focused on the analysis and comparison of hydrological drought occurrence, development and duration in six small to middle sized catchments in the Czech Republic (CZ) and Slovakia. The main questions to be answered are: (1) are there correlations between the physical conditions in the catchments and drought occurrence, and (2) does the spatial trend of drought occurrence exist. The Žitava catchment is located in the central western part of Slovakia having runoff dominated by rainfall with the contribution of snow melting during the spring period. The Belá River catchment is located on the contact of Západné and Vysoké Tatry Mts. in the north of Slovakia. The runoff is snow to snow-rain combined type. The Ľupčianka catchment is located on the northern slopes of the Nízke Tatry Mts. in the northern part of the central Slovakia. The runoff regime is snow-rain combined in the upper part of the catchment, and of rain-snow type in the rest of catchment. The Rakovnický potok brook (CZ) has its spring in Rakovnická pahorkatina hilly land. Runoff is dominated by rainfall, quite heavily influenced by water uptakes in the catchment. The Teplá River (CZ) originates in peat meadows in the western part of the Czech Republic. Runoff is dominated by rainfall. The Metuje catchment (CZ) is formed by Adršsbach-Teplické stěny Upland. The headwater part is typical by deeply incest valleys, table mountains and pseudokarst caves. The discharge is fed dominantly by groundwater. The streamflow drought was characterized using discharge data, the groundwater drought using the base flow values. The local minimum method was used for base flow separation. The threshold level method (Q80, BF80) and the sequent peak algorithm were used for calculation of drought duration in discharge and base flow time series. The data of the same three decades of the common period (1971 - 1980, 1981 - 1990 and 1991 - 2000) were used. The resulting base flow values along with

  12. Nitrate reduction in geologically heterogeneous catchments

    DEFF Research Database (Denmark)

    Refsgaard, Jens Christian; Auken, Esben; Bamberg, C.A.;

    2014-01-01

    In order to fulfil the requirements of the EU Water Framework Directive nitrate load from agricultural areas to surface water in Denmark needs to be reduced by about 40%. The regulations imposed until now have been uniform, i.e. the same restrictions for all areas independent of the subsurface...... conditions. Studies have shown that on a national basis about 2/3 of the nitrate leaching from the root zone is reduced naturally, through denitrification, in the subsurface before reaching the streams. Therefore, it is more cost-effective to identify robust areas, where nitrate leaching through the root...... the entire catchment. However, as distributed models often do not include local scale hydrogeological heterogeneities, they are typically not able to make accurate predictions at scales smaller than they are calibrated. We present a framework for assessing nitrate reduction in the subsurface...

  13. Modeling of matters removal from swampy catchment

    Science.gov (United States)

    Inishev, N. G.; Inisheva, L. I.

    2010-05-01

    This work shows the results of fixed study of geochemical conditions in the system of landscape oligotrophic profile at Vasyugan mire spurs, and also we make an approach to processes modelling of compounds removal from swampy catchment. During investigation of symbolic model of chemical matters removal from the surface of a catchment basin and their movement along the channel network it was taken into account that removal of chemical elements during the period of spring flood and rain high waters occur mainly with overland flow. During calculation of dissolved matters movement the following admissions take place: 1. The problem is solved at one-dimension set-up. Concentration of investigated components is taken as averaged one along the flow cross section or effective area of slope cross-section for overland runoff, i.e. it changes only lengthways and in time. 2. It is considered that dissolved matters spread due to movement of water and together with its particles. 3. Processes of water self-clarification are not considered. The model is calculated on the basis of discharge of the investigated ingredient, i.e. matter mass moving through the given flow cross-section into time unit. This is the peculiarity of the model. Matter removal together with water flow is determined if necessary. Everyday impurity consumptions and its concentration can be estimated at the outlet at the moment of time according to convolution integral. Estimation of overland runoff and water inflow into the channel network is based on the mathematic model of outflow formation from peatland areas which considers basic processes carrying out at catchment and basin channel network. Stored moisture estimation of snow cover is taken according to snow survey data before snow melting. Everyday water supply to the surface of water collection was determined according to the results of snow melt intensity estimation by the methods of temperature coefficient and water yield from snow (A.G. Kovzel). All

  14. Pesticide uses and transfers in urbanised catchments.

    Science.gov (United States)

    Blanchoud, Hélène; Farrugia, Frédéric; Mouchel, Jean Marie

    2004-05-01

    An investigation on herbicide uses in two semi-urban catchments was performed simultaneously with sampling campaigns at six stations inside both watersheds from April to July 1998. Urban uses of herbicides exceeded agricultural uses, and transfer coefficients were also higher in urban areas. Therefore, the most used product in urban areas (diuron) was by far the most contaminating product. Householders accounted for 30% of all uses. The highest measured diuron concentration in water surface was 8.7 microg l(-1) due to its use on impervious surfaces. Compared to EEC standards for drinking water production (0.1 microg l(-1)), it is clear that suburban uses of herbicides may severely endanger drinking water production from river water.

  15. Chemical weathering and runoff chemistry in a steep headwater catchment

    Science.gov (United States)

    Anderson, Suzanne Prestrud; Dietrich, William E.

    2001-07-01

    We present here deductions about the location, rate, and mechanisms of chemical weathering in a small catchment based on a catchment-scale sprinkling experiment. In this experiment demineralized water was applied at an approximately steady rate in the CB1 catchment in the Oregon Coast Range to reach and maintain a quasi-steady discharge for a period of 4 days. Because of nearly steady flow conditions within the catchment, the contribution to solute fluxes from soil and bedrock could be partitioned. One half of the solute flux from the catchment derived from colluvial soil, and one half from weathering in bedrock. This implies more intense weathering in the thin colluvium mantling the catchment than in the thick underlying weathered bedrock. The annual solute flux from the catchment, scaled to the annual runoff from the catchment, is 32 +/- 10 t km-2 year-1, equivalent to published chemical denudation rates for nearby rivers with drainage areas 106 times greater than the experiment site. Soil waters sampled during the sprinkling experiment had steady compositions following a period of transient water flow conditions, implying steady-state chemical evolution in the soil. The waters leached organic anions from shallow depths in the soil, which solubilized aluminium and iron, indicating that podzolization is occurring in these soils. Carbonate dissolution appears to be an important source of solutes from the bedrock, despite being present as only a minor phase in the rock. Water balance suggests that the residence time of water in the catchment is about 2 months, and that typical 24 h storms displace only a fraction of the stored water. A consequence is that runoff chemistry is dominated by old water, which imposes strong limits on the variability of runoff composition.

  16. Climate change adaptation via targeted ecosystem service provision: a sustainable land management strategy for the Segura catchment (SE Spain)

    Science.gov (United States)

    Zagaria, Cecilia; de Vente, Joris; Perez-Cutillas, Pedro

    2014-05-01

    Topical research investigating climate, land-use and management scenarios in the Segura catchment (SE Spain), depicts a landscape at high-risk of, quite literally, deserting agriculture. Land degradation in the semi-arid region of SE Spain is characterized by water shortage, high erosion rates and salinization, increasingly exacerbated by climatic changes, scarce vegetation cover and detrimental farming practices. Future climate scenarios predict increases in aridity, variability and intensity of rainfall events, leading to increasing pressure on scarce soil and water resources. This study conceptualized the impending crisis of agro-ecological systems of the Segura basin (18800 km2) as a crisis of ecosystem service deterioration. In light of existing land degradation drivers and future climate scenarios, the potential of Sustainable Land Management (SLM) strategies was evaluated to target three priority ecosystem services (water provision, sediment retention and carbon sequestration) as a means to achieve climate change adaptation and mitigation. A preceding thorough process of stakeholder engagement (as part of the EU funded DESIRE project) indicated five SLM technologies for potential implementation, all with a focus upon reducing soil erosion, increasing soil water holding capacity and soil organic matter content. These technologies have been tested for over four years in local experimental field plots, and have provided results on the local effects upon individual environmental parameters. Despite the growing emphasis witnessed in literature upon the context-specificity which characterizes adaptation solutions, the frequent analysis at the field scale is limited in both scope and utility. There is a need to investigate the effects of adaptive SLM solutions at wider, regional scales. Thus, this study modeled the cumulative effect of each of the five selected SLM technologies with InVEST, a spatial analyst tool designed for ecosystem service quantification and

  17. Biomarker evidence for increasing aridity in south-central India over the Holocene

    Science.gov (United States)

    Sarkar, S.; Wilkes, H.; Prasad, S.; Brauer, A.; Basavaiah, N.; Strecker, M. R.; Sachse, D.

    2012-12-01

    Summer monsoonal rainfall has played an important role in the development and sustenance of the largely agro-based economy in the Indian subcontinent in the recent past. A better understanding of past variations in monsoonal rainfall can therefore lead to an assessment of its potential impact on early human societies. However, our knowledge of spatiotemporal patterns of past monsoon strength, as inferred from proxy records, is limited due to the lack of high-resolution paleo-hydrological records from continental archives. Here, we reconstruct centennial-scale hydrological variability associated with changes in the intensity of the Indian Summer Monsoon based on a record of lipid biomarker abundances and compound-specific stable isotopic composition of a 10-m-long sediment core from saline-alkaline Lonar Lake, situated in the core 'monsoon zone' of south-central India. We identified three periods of distinct hydrology over the Holocene in south-central India. The period between 10.4 and 6.5 ka BP was characterized by a relatively high abundance of land-plant biomarkers, such as long-chain n-alkanes. The composition of these leaf-wax n-alkanes (weighted average of concentration of different chain-length n-alkanes, expressed as the ACL index) and their negative δ13C (-30‰ to -33 ‰) indicate the dominance of woody C3 vegetation in the catchment, and negative δD (-170‰ to -175‰) values argue for a wet period due to an intensified monsoon. Rapid fluctuations in abundance of both terrestrial and aquatic biomarkers between 6.5 and 4 ka BP indicate an unstable lake ecosystem, culminating in a transition to arid conditions. Higher ACL values and a pronounced shift to more positive δ13C values (up to -22‰) of leaf-wax n-alkanes over this period indicate a change of dominant vegetation to C4 grasses. Along with a 40‰ increase in leaf wax n-alkane δD values, which likely resulted from less rainfall and/or higher plant evapotranspiration, we interpret this period

  18. Characteristics of chemistry and stable isotopes in groundwater of the Chaobai River catchment, Beijing

    Energy Technology Data Exchange (ETDEWEB)

    Li, J. [Key Laboratory of Engineering Geomechanics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Liu, J.; Wang, X. [Hydrogeology and Engineering Geology Team of Beijing, Beijing 100037 (China); Pang, Z. [Key Laboratory of Engineering Geomechanics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029 (China)

    2013-07-01

    Environmental isotopes and chemical compositions are useful tools for the study of groundwater flow systems. Groundwater of the Chaobai River catchment, Beijing was sampled for chemical and stable isotopes analyses in 2005. Geochemical signatures evolve progressively from CaMg-HCO{sub 3} to NaK-HCO{sub 3}, and then to Na-HCO{sub 3} compositions as groundwater flows from the mountain to discharge areas. Groundwater can be divided into two groups on the basis of stable isotope compositions: ancient groundwater and modern groundwater. Modern groundwater (-9.90/00 to -6.60/00 for δ{sup 18}O) plots along a line with a slope of 4.0 on a δ{sup 2}H versus δ{sup 18}O diagram, reflecting evaporation during the process of recharge, whereas ancient groundwater samples (30 to 12 Ka.) are different in isotopic composition (-11.00/00 and -68.20/00 for δ{sup 18}O and δ{sup 2}H, respectively), reflecting the cold and arid climate in the last glacial period. The results have important implications for groundwater management in Beijing City. (authors)

  19. A catchment scale water balance model for FIFE

    Science.gov (United States)

    Famiglietti, J. S.; Wood, E. F.; Sivapalan, M.; Thongs, D. J.

    1992-01-01

    A catchment scale water balance model is presented and used to predict evaporation from the King's Creek catchment at the First ISLSCP Field Experiment site on the Konza Prairie, Kansas. The model incorporates spatial variability in topography, soils, and precipitation to compute the land surface hydrologic fluxes. A network of 20 rain gages was employed to measure rainfall across the catchment in the summer of 1987. These data were spatially interpolated and used to drive the model during storm periods. During interstorm periods the model was driven by the estimated potential evaporation, which was calculated using net radiation data collected at site 2. Model-computed evaporation is compared to that observed, both at site 2 (grid location 1916-BRS) and the catchment scale, for the simulation period from June 1 to October 9, 1987.

  20. Impacts of Climate Anomalies on the Vegetation Patterns in the Arid and Semi-Arid Zones of Uzbekistan

    Science.gov (United States)

    Dildora, Aralova; Toderich, Kristina; Dilshod, Gafurov

    2016-08-01

    Steadily rising temperature anomalies in last decades are causing changes in vegetation patterns for sensitive to climate change in arid and semi-arid dryland ecosystems. After desiccation of the Aral Sea, Uzbekistan has been left with the challenge to develop drought and heat stress monitoring system and tools (e.g., to monitor vegetation status and/crop pattern dynamics) with using remote sensing technologies in broad scale. This study examines several climate parameters, NDVI and drought indexes within geostatistical method to predict further vegetation status in arid and semi-arid zones of landscapes. This approaches aimed to extract and utilize certain variable environmental data (temperature and precipitation) for assessment and inter-linkages of vegetation cover dynamics, specifically related to predict degraded and recovered zones or desertification process in the drylands due to scarcity of water resources and high risks of climate anomalies in fragile ecosystem of Uzbekistan.

  1. Late glacial aridity in southern Rocky Mountains

    Energy Technology Data Exchange (ETDEWEB)

    Davis, O.K.; Pitblado, B.L. [Univ. of Arizona, Tucson, AZ (United States)

    1995-09-01

    While the slopes of the present-day Colorado Rocky Mountains are characterized by large stands of subalpine and montane conifers, the Rockies of the late glacial looked dramatically different. Specifically, pollen records suggest that during the late glacial, Artemisia and Gramineae predominated throughout the mountains of Colorado. At some point between 11,000 and 10,000 B.P., however, both Artemisia and grasses underwent a dramatic decline, which can be identified in virtually every pollen diagram produced for Colorado mountain sites, including Como Lake (Sangre de Cristo Mountains), Copley Lake and Splains; Gulch (near Crested Butte), Molas Lake (San Juan Mountains), and Redrock Lake (Boulder County). Moreover, the same pattern seems to hold for pollen spectra derived for areas adjacent to Colorado, including at sites in the Chuska Mountains of New Mexico and in eastern Wyoming. The implications of this consistent finding are compelling. The closest modem analogues to the Artemisia- and Gramineae-dominated late-glacial Colorado Rockies are found in the relatively arid northern Great Basin, which suggests that annual precipitation was much lower in the late-glacial southern Rocky Mountains than it was throughout the Holocene.

  2. Streamflow response of a small forested catchment on different timescales

    Directory of Open Access Journals (Sweden)

    A. Zabaleta

    2013-01-01

    Full Text Available The hydrological response of a catchment to rainfall on different timescales is result of a complex system involving a range of physical processes which may operate simultaneously and have different spatial and temporal influences. This paper presents the analysis of streamflow response of a small humid-temperate catchment (Aixola, 4.8 km2 in the Basque Country on different timescales and discusses the role of the controlling factors. Firstly, daily time series analysis was used to establish a hypothesis on the general functioning of the catchment through the relationship between precipitation and discharge on an annual and multiannual scale (2003–2008. Second, rainfall-runoff relationships and relationships among several hydrological variables, including catchment antecedent conditions, were explored at the event scale (222 events to check and improve the hypothesis. Finally, the evolution of electrical conductivity (EC during some of the monitored storm events (28 events was examined to identify the time origin of waters. Quick response of the catchment to almost all the rainfall events as well as a considerable regulation capacity was deduced from the correlation and spectral analyses. These results agree with runoff event scale data analysis; however, the event analysis revealed the non-linearity of the system, as antecedent conditions play a significant role in this catchment. Further, analysis at the event scale made possible to clarify factors controlling (precipitation, precipitation intensity and initial discharge the different aspects of the runoff response (runoff coefficient and discharge increase for this catchment. Finally, the evolution of EC of the waters enabled the time origin (event or pre-event waters of the quickflow to be established; specifically, the conductivity showed that pre-event waters usually represent a high percentage of the total discharge during runoff peaks. The importance of soil waters in the

  3. Rainfall, runoff and sediment transport in a Mediterranean mountainous catchment.

    Science.gov (United States)

    Tuset, J; Vericat, D; Batalla, R J

    2016-01-01

    The relation between rainfall, runoff, erosion and sediment transport is highly variable in Mediterranean catchments. Their relation can be modified by land use changes and climate oscillations that, ultimately, will control water and sediment yields. This paper analyses rainfall, runoff and sediment transport relations in a meso-scale Mediterranean mountain catchment, the Ribera Salada (NE Iberian Peninsula). A total of 73 floods recorded between November 2005 and November 2008 at the Inglabaga Sediment Transport Station (114.5 km(2)) have been analysed. Suspended sediment transport and flow discharge were measured continuously. Rainfall data was obtained by means of direct rain gauges and daily rainfall reconstructions from radar information. Results indicate that the annual sediment yield (2.3 t km(-1) y(-1) on average) and the flood-based runoff coefficients (4.1% on average) are low. The Ribera Salada presents a low geomorphological and hydrological activity compared with other Mediterranean mountain catchments. Pearson correlations between rainfall, runoff and sediment transport variables were obtained. The hydrological response of the catchment is controlled by the base flows. The magnitude of suspended sediment concentrations is largely correlated with flood magnitude, while sediment load is correlated with the amount of direct runoff. Multivariate analysis shows that total suspended load can be predicted by integrating rainfall and runoff variables. The total direct runoff is the variable with more weight in the equation. Finally, three main hydro-sedimentary phases within the hydrological year are defined in this catchment: (a) Winter, where the catchment produces only water and very little sediment; (b) Spring, where the majority of water and sediment is produced; and (c) Summer-Autumn, when little runoff is produced but significant amount of sediments is exported out of the catchment. Results show as land use and climate change may have an important

  4. Entomological studies for surveillance and prevention of dengue in arid and semi-arid districts of Rajasthan, India

    Directory of Open Access Journals (Sweden)

    Anil Purohit

    2008-05-01

    Full Text Available Background & objectives: Rajasthan is one of the dengue endemic states of India. Very few studies have been published on entomological aspects of dengue in this state. Owing to water scarcity, inhabitants in desert areas overstore domestic water which leads to the persistence of dengue vectors within the domestic premises. Area specific knowledge on breeding, key containers and seasonal rhythms of vector population is essential for preparing an effective prevention plan against dengue. Present paper reports results of entomological investigations on dengue vectors in arid and semi-arid districts of Rajasthan. Methods: Longitudinal studies were undertaken during 2004–06 in one arid and two semi-arid dengue endemic districts of Rajasthan. Adult and larval Aedes were collected from the randomly selected houses in representative towns and villages with associated details of container types and water storage practices of inhabitants. Results: In urban areas during all the seasons adult house index (AHI of Aedes aegypti was maximum in desert zone (25 and least in semi-arid area with saline river III (1. The difference of AHI during three seasons was statistically significant (c2 = 16.1, p <0.01 for urban; and c2 = 50.71, p < 0.001 for rural. Breeding of Ae. aegypti among urban settings was maximum in desert zone. During all the seasons cement tanks were the key breeding habitats for Ae. aegypti in desert as well as semi-arid areas. Interpretation & conclusion: Water storage habits during summer season emerged to be the risk factor of vector abundance in urban areas of arid and semi-arid settings. A carefully designed study of key containers targeting cement tanks as the primary habitats of mosquito control may lead to commendable results for dengue prevention.

  5. Keeping Sediment and Nutrients out of Streams in Arid/Semi-Arid Regions: Application of Low Impact Development/Green Infrastructure Practices

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    Yongping, Yuan

    2015-04-01

    Climatic and hydrological characteristics in the arid/semi-arid areas create unique challenges to soil, water and biodiversity conservation. These areas are environmentally sensitive, but very valuable for the ecosystems services they provide to society. Some of these areas are experiencing the fastest urbanization and now face multiple water resource challenges. Low Impact Development (LID)/Green Infrastructure (GI) practices are increasingly popular for reducing stormwater and nonpoint source pollution in many regions around the world. However, streamflow in the arid/semi-arid regions is largely dependent on seasonal, short term, and high intensity rainfall events. LID has not been very common in the arid/semi-arid regions due to a lack of performance evaluation, as well as the perception that LID may not be very useful for regions with little annual precipitation. This study focused on investigating the hydrologic and pollutant removal performance of LID/GI systems in arid/semi-arid climates. Ten types of practices were found in use in the Western/Southwestern U.S.: rainwater harvest systems, detention ponds, retention ponds, bioretention, media filters, porous pavements, vegetated swales/buffer/strips, green roofs, infiltration trenches, and integrated LIDs. This study compared the performance of these practices in terms of their effectiveness at pollutant removal and cost-effectiveness. This analysis provides insight into the future implementation of LID/GI in the arid/semi-arid areas. Key words: LID/GI, arid/semi-arid, effectiveness of pollutant removal, cost-effectiveness analysis

  6. Use of High Spatial Resolution Remote Sensing for Hydro-Geomorphologic Analysis of Medium-sized Arid Basins

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    Sadeh, Yuval; Blumberg, Dan G.; Cohen, Hai; Morin, Efrat; Maman, Shimrit

    2016-04-01

    Arid environments are often remote, expansive, difficult to access and especially vulnerable to flash flood hazards due to the poor understanding of the phenomenon and the lack of meteorological, geomorphological, and hydrological data. For many years, catchment characteristics have been observed using point-based measurements such as rain gauges and soil sample analysis; on the other hand, use of remote sensing technologies can provide spatially continuous hydrological parameters and variables. The advances in remote sensing technologies can provide new geo-spatial data using high spatial and temporal resolution for basin-scale geomorphological analysis and hydrological models. This study used high spatial resolution remote sensing for hydro-geomorphologic analysis of the arid medium size Rahaf watershed (76 km2), located in the Judean Desert, Israel. During the research a high resolution geomorphological map of Rahaf basin was created using WorldView-2 multispectral satellite imageries; surface roughness was estimated using SIR-C and COSMO-SkyMed Synthetic Aperture Radar (SAR) spaceborne sensors; and rainstorm characteristics were extracted using ground-based meteorological radar. The geomorphological mapping of Rahaf into 17 classes with good accuracy. The surface roughness extraction using SAR over the basin showed that the correlation between the COSMO-SkyMed backscatter coefficient and the surface roughness was very strong with an R2 of 0.97. This study showed that using x-band spaceborne sensors with high spatial resolution, such as COSMO-SkyMed, are more suitable for surface roughness evaluation in flat arid environments and should be in favor with longer wavelength operating sensors such as the SIR-C. The current study presents an innovative method to evaluate Manning's hydraulic roughness coefficient (n) in arid environments using radar backscattering. The weather radar rainfall data was calibrated using rain gauges located in the watershed. The

  7. Localized bedrock aquifer distribution explains discharge from a headwater catchment

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    Kosugi, Ken'ichirou; Fujimoto, Masamitsu; Katsura, Shin'ya; Kato, Hiroyuki; Sando, Yoshiki; Mizuyama, Takahisa

    2011-07-01

    Understanding a discharge hydrograph is one of the leading interests in catchment hydrology. Recent research has provided credible information on the importance of bedrock groundwater on discharge hydrographs from headwater catchments. However, intensive monitoring of bedrock groundwater is rare in mountains with steep topography. Hence, how bedrock groundwater controls discharge from a steep headwater catchment is in dispute. In this study, we conducted long-term hydrological observations using densely located bedrock wells in a headwater catchment underlain by granitic bedrock. The catchment has steep topography affected by diastrophic activities. Results showed a fairly regionalized distribution of bedrock aquifers within a scale of tens of meters, consisting of upper, middle, and lower aquifers, instead of a gradual and continuous decline in water level from ridge to valley bottom. This was presumably attributable to the unique bedrock structure; fault lines developed in the watershed worked to form divides between the bedrock aquifers. Spatial expanse of each aquifer and the interaction among aquifers were key factors to explain gentle and considerable variations in the base flow discharge and triple-peak discharge responses of the observed hydrograph. A simple model was developed to simulate the discharge hydrograph, which computed each of the contributions from the soil mantle groundwater, from the lower aquifer, and from the middle aquifer to the discharge. The modeling results generally succeeded in reproducing the observed hydrograph. Thus, this study demonstrated that understanding regionalized bedrock aquifer distribution is pivotal for explaining discharge hydrograph from headwater catchments that have been affected by diastrophic activities.

  8. Groundwater head controls nitrate export from an agricultural lowland catchment

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    Musolff, Andreas; Schmidt, Christian; Rode, Michael; Lischeid, Gunnar; Weise, Stephan M.; Fleckenstein, Jan H.

    2016-10-01

    Solute concentration variability is of fundamental importance for the chemical and ecological state of streams. It is often closely related to discharge variability and can be characterized in terms of a solute export regime. Previous studies, especially in lowland catchments, report that nitrate is often exported with an accretion pattern of increasing concentrations with increasing discharge. Several modeling approaches exist to predict the export regime of solutes from the spatial relationship of discharge generating zones with solute availability in the catchment. For a small agriculturally managed lowland catchment in central Germany, we show that this relationship is controlled by the depth to groundwater table and its temporal dynamics. Principal component analysis of groundwater level time series from wells distributed throughout the catchment allowed derivation of a representative groundwater level time series that explained most of the discharge variability. Groundwater sampling revealed consistently decreasing nitrate concentrations with an increasing thickness of the unsaturated zone. The relationships of depth to groundwater table to discharge and to nitrate concentration were parameterized and integrated to successfully model catchment discharge and nitrate export on the basis of groundwater level variations alone. This study shows that intensive and uniform agricultural land use likely results in a clear and consistent concentration-depth relationship of nitrate, which can be utilized in simple approaches to predict stream nitrate export dynamics at the catchment scale.

  9. A 500-year history of floods in the semi arid basins of south-eastern Spain

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    Sánchez García, Carlos; Schulte, Lothar; Peña, Juan Carlos; Carvalho, Filpe; Brembilla, Carla

    2016-04-01

    Floods are one of the natural hazards with higher incidence in the south-eastern Spain, the driest region in Europe, causing fatalities, damage of infrastructure and economic losses. Flash-floods in semi arid environments are related to intensive rainfall which can last from few hours to days. These floods are violent and destructive because of their high discharges, sediment transport and aggradation processes in the flood plain. Also during historical times floods affected the population in the south-eastern Spain causing sever damage or in some cases the complete destruction of towns. Our studies focus on the flood reconstruction from historical sources of the Almanzora, Aguas and Antas river basins, which have a surface between 260-2600 km2. We have also compiled information from the Andarax river and compared the flood series with the Guadalentín and Segura basins from previous studies (Benito et. al., 2010 y Machado et al., 2011). Flood intensities have been classified in four levels according to the type of damage: 1) ordinary floods that only affect agriculture plots; 2) extraordinary floods which produce some damage to buildings and hydraulic infrastructure; 3) catastrophic floods which caused sever damage, fatalities and partial or complete destruction of towns. A higher damage intensity of +1 magnitude was assigned when the event is recorded from more than one major sub-basin (stretches and tributaries such as Huércal-Overa basin) or catchment (e.g. Antas River). In total 102 incidences of damages and 89 floods were reconstructed in the Almanzora (2.611 km2), Aguas (539 km2), Antas (261 km2) and Andarax (2.100 km2) catchments. The Almanzora River was affected by 36 floods (1550-2012). The highest events for the Almanzora River were in 1580, 1879, 1973 and 2012 producing many fatalities and destruction of several towns. In addition, we identified four flood-clusters 1750-1780, 1870-1900, 1960-1977 and 1989-2012 which coincides with the periods of

  10. Predictability and prediction of summer rainfall in the arid and semi-arid regions of China

    Science.gov (United States)

    Xing, Wen; Wang, Bin

    2016-09-01

    Northwest China (NWC) is an arid and semi-arid region where climate variability and environmental changes are sensitive to precipitation. The present study explores sources and limits of predictability of summer precipitation over NWC using the predictable mode analysis (PMA) of percentage of rainfall anomaly data. Two major modes of NWC summer rainfall variability are identified which are tied to Eurasian continental scale precipitation variations. The first mode features wet northern China corresponding to dry central Siberia and wet Mongolia, which is mainly driven by tropical Pacific sea surface temperature anomalies (SSTA). The second mode features wet western China reflecting wet Central Asia and dry Ural-western Siberia, which strongly links to Indian Ocean SSTA. Anomalous land warming over Eurasia also provides important precursors for the two modes. The cross-validated hindcast results demonstrate these modes can be predicted with significant correlation skills, suggesting that they may be considered as predictable modes. The domain averaged temporal correlation coefficient (TCC) skill during 1979 to 2015 using 0-month (1-month) lead models is 0.39 (0.35), which is considerably higher than dynamical models' multi-model ensemble mean skill (-0.02). Maximum potential attainable prediction skills are also estimated and discussed. The result illustrates advantage of PMA in predicting rainfall over dry land areas and large room for dynamical model improvement. However, secular changes of predictors need to be detected continuously in order to make practical useful prediction.

  11. Adaptation to drought in arid and semi-arid environments: Case of the Zambezi Valley, Zimbabwe

    Directory of Open Access Journals (Sweden)

    Emmanuel Mavhura

    2015-02-01

    Full Text Available Small-scale rain-fed agriculture is the main livelihood in arid to semi-arid regions of subSaharan Africa. The area is characterised by erratic rainfall and frequent droughts, making the capacity for coping with temporal water shortages essential for smallholder farmers. Focusing on the Zambezi Valley, Zimbabwe, this study investigates the impact of drought on food security and the strategies used by smallholder farmers to cope with drought. We used meteorological data and interviews to examine the rainfall variability in the study area and the drought-coping mechanisms employed by smallholder famers respectively. The results show that there are various strategies used by smallholder farmers to cope with the impact of drought. These strategies include drought-tolerant crop production, crop variety diversification, purchasing cereals through asset sales, non-governmental organisations’ food aid and gathering wild fruit. However, consecutive droughts have resulted in high food insecurity and depletion of household assets during droughts. Smallholder farmers in the valley have also resorted to a number of measures taken before, during and after the drought. Still, these strategies are not robust enough to cope with this uncertainty

  12. Mountaintop Removal Mining and Catchment Hydrology

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    Andrew J. Miller

    2014-03-01

    Full Text Available Mountaintop mining and valley fill (MTM/VF coal extraction, practiced in the Central Appalachian region, represents a dramatic landscape-scale disturbance. MTM operations remove as much as 300 m of rock, soil, and vegetation from ridge tops to access deep coal seams and much of this material is placed in adjacent headwater streams altering landcover, drainage network, and topography. In spite of its scale, extent, and potential for continued use, the effects MTM/VF on catchment hydrology is poorly understood. Previous reviews focus on water quality and ecosystem health impacts, but little is known about how MTM/VF affects hydrology, particularly the movement and storage of water, hence the hydrologic processes that ultimately control flood generation, water chemistry, and biology. This paper aggregates the existing knowledge about the hydrologic impacts of MTM/VF to identify areas where further scientific investigation is needed. While contemporary surface mining generally increases peak and total runoff, the limited MTM/VF studies reveal significant variability in hydrologic response. Significant knowledge gaps relate to limited understanding of hydrologic processes in these systems. Until the hydrologic impact of this practice is better understood, efforts to reduce water quantity and quality problems and ecosystem degradation will be difficult to achieve.

  13. Guiding soil conservation strategy in headwater mediterranean catchments

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    Ben Slimane, Abir; Raclot, Damien; Evrard, Olivier; Sanaa, Mustapha; Lefèvre, Irène; Le Bissonnais, Yves

    2016-04-01

    Reservoir siltation due to water erosion is an important environmental issue in Mediterranean countries where storage of clear surface water is crucial for their economic and agricultural development. In order to reduce water erosion, this study aimed to design a methodology for guiding the implementation of efficient conservation strategies by identifying the dominant sediment sources in Mediterranean context. To this end, a fingerprinting method was combined with long-term field monitoring of catchment sediment yield in five headwater catchments (0.1-10 km2) equipped with a small reservoir between 1990 and 1995. The five catchments were chosen to cover the large diversity of environmental conditions found along the Tunisian Ridge and in the Cape Bon region. The fingerprinting techniques based on measurements of cesium-137 and Total Organic Carbon within the catchments and in reservoir sediment deposits successfully identified the contribution of rill/interrill and gully/channel erosion to sediment yield at the outlet of five small headwater catchments during the last 15-20 years. Results showed the very large variability of erosion processes among the selected catchments, with rill/interrill erosion contributions to sediment accumulated in outlet reservoirs ranging from 20 to 80%. Overall, rill/interrill erosion was the dominant process controlling reservoir siltation in three catchments whereas gully/channel erosion dominated in the other two catchments. This demonstrates that the dominant erosion process in the Mediterranean regions highly depends on the local environmental context. The lowest rill/interrill erosion contribution (2.2 Mg ha-1 yr-1) in the five catchments remained significantly higher than the tolerable soil loss indicating the severe levels reached by soil erosion along the Tunisian Ridge and in the Cape Bon region. This study also showed that although the implementation of improved topsoil management measures greatly reduced rill

  14. Nebkha patterns in semi-arid environments

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    Nield, J. M.; Gillies, J. A.; Nickling, W. G.

    2014-12-01

    In semi-arid supply-limited, environments, nehbka dunes typically form through ecogeomorphic feedbacks. The size, shape and orientation of these dunes are controlled by the interactions between vegetation growth and aeolian sedimentations processes. Once established, these dune patterns modify sediment transport and often form streets of bare surfaces between dune corridors. We examine typical dune and vegetation patterns that form with varying amounts of sediment availability and nebkha maturity at Jornada in the Chihuahuan Desert, New Mexico, USA using terrestrial laser scanning (TLS) to separate the plant and sand elements. Manual and automated TLS shrub height extractions compare well at all sites (p = 0.48-0.94) enabling the quantification of both solid and plant roughness element components in three dimensions. We find that there is a switch in orientation of the dune elements with respect to dominant wind direction from perpendicular to parallel as the landscape develops from an incipient to mature configuration and mesquite-nebkha streets are enhanced. As the nebkha dunes develop the surface coverage of bare sand increases and dune surfaces exceed the size of their companion shrubs. Roughness density also increases at the mature dune site. Individual shrub orientations remain similar at each site, but nebkhas typically host multiple shrub crowns at the mature site. Over a two year period up to 20 cm of erosion was measured on the upwind faces of the mature nebkha dunes, in agreement with the dominant annual wind direction. However, deposition patterns were more diffuse and influenced by the vegetation patterns. This study highlights the importance of ecogeomorphic interactions in shaping nebkha landscape patterns.

  15. Hydrological drought severity explained by climate and catchment characteristics

    Science.gov (United States)

    Van Loon, A. F.; Laaha, G.

    2015-07-01

    Impacts of a drought are generally dependent on the severity of the hydrological drought event, which can be expressed by streamflow drought duration or deficit volume. For prediction and the selection of drought sensitive regions, it is crucial to know how streamflow drought severity relates to climate and catchment characteristics. In this study we investigated controls on drought severity based on a comprehensive Austrian dataset consisting of 44 catchments with long time series of hydrometeorological data (on average around 50 year) and information on a large number of physiographic catchment characteristics. Drought analysis was performed with the variable threshold level method and various statistical tools were applied, i.e. bivariate correlation analysis, heatmaps, linear models based on multiple regression, varying slope models, and automatic stepwise regression. Results indicate that streamflow drought duration is primarily controlled by storage, quantified by the Base Flow Index or by a combination of catchment characteristics related to catchment storage and release, e.g. geology and land use. Additionally, the duration of dry spells in precipitation is important for streamflow drought duration. Hydrological drought deficit, however, is governed by average catchment wetness (represented by mean annual precipitation) and elevation (reflecting seasonal storage in the snow pack and glaciers). Our conclusion is that both drought duration and deficit are governed by a combination of climate and catchment control, but not in a similar way. Besides meteorological forcing, storage is important; storage in soils, aquifers, lakes, etc. influences drought duration and seasonal storage in snow and glaciers influences drought deficit. Consequently, the spatial variation of hydrological drought severity is highly dependent on terrestrial hydrological processes.

  16. Catchment systems science and management: from evidence to resilient landscapes

    Science.gov (United States)

    Quinn, Paul

    2014-05-01

    There is an urgent need to reassess both the scientific understanding and the policy making approaches taken to manage flooding, water scarcity and pollution in intensively utilised catchments. Many European catchments have been heavily modified and natural systems have largely disappeared. However, working with natural processes must still be at the core of any future management strategy. Many catchments have greatly reduced infiltration rates and buffering capacity and this process needs to be reversed. An interventionist and holistic approach to managing water quantity and quality at the catchment scale is urgently required through the active manipulation of natural flow processes. Both quantitative (field experiments and modelling) and qualitative evidence (local knowledge) is required to demonstrate that catchment have become 'unhealthy'. For example, dense networks of low cost instrumentation could provide this multiscale evidence and, coupled with stakeholder knowledge, build a comprehensive understanding of whole system function. Proactive Catchment System Management is an interventionist approach to altering the catchment scale runoff regime through the manipulation of landscape scale hydrological flow pathways. Many of the changes to hydrological processes cannot be detected at the catchment scale as the primary causes of flooding and pollution. Evidence shows it is the land cover and the soil that are paramount to any change. Local evidence shows us that intense agricultural practices reduce the infiltration capacity through soil degradation. The intrinsic buffering capacity has also been lost across the landscape. The emerging hydrological process is one in which the whole system responds too quickly (driven by near surface and overland flow processes). The bulk of the soil matrix is bypassed during storm events and there is little or no buffering capacity in the riparian areas or in headwater catchments. The prospect of lower intensity farming rates is

  17. Carbon redistribution by erosion processes in an intensively disturbed catchment

    Science.gov (United States)

    Boix-Fayos, Carolina; Martínez-Mena, María; Pérez Cutillas, Pedro; de Vente, Joris; Barberá, Gonzalo G.; Mosch, Wouter; Navarro Cano, Jose Antonio; Gaspar, Leticia; Navas, Ana

    2016-04-01

    Understanding how organic carbon moves with sediments along the fluvial system is crucial to close catchment scale carbon budgets. Especially challenging is the analysis of organic carbon dynamics during fluvial transport in heterogeneous, fragile and disturbed environments with ephemeral and intense hydrological pulses, typical of Mediterranean conditions. This paper explores the catchment scale organic carbon redistribution by lateral flows in extreme Mediterranean environmental conditions from a geomorphological perspective. The study area is a catchment (Cárcavo) in SE Spain with a semiarid climate, erodible lithologies, shallow soils, and highly disturbed by agricultural terraces, land levelling, reforestations and construction of check-dams. To increase understanding of erosion induced catchment scale organic carbon redistribution, we studied the subcatchments of 8 check-dams distributed along the catchment main channel in detail. We determined 137Cs, physicochemical characteristics and organic carbon pools of soils and sediments deposited behind each check-dam, performed spatial analysis of properties of the catchment and buffer areas around check-dams, and carried out geomorphological analysis of the slope-channel connections. Soils showed very low Total Organic Carbon (TOC) values oscillating between 15.2 and 4.4 g Kg-1 for forest and agricultural soils, respectively. Sediments mobilized by erosion were poor in TOC compared to the eroded (forest) soils (6.6±0.7 g Kg-1), and the redistribution of organic carbon through the catchment, especially of the Mineral Associated Organic Carbon (MAC) pool, showed the same pattern as clay particles and 137Cs. The TOC erosion rates (0.031±0.03 Mg ha-1 y-1) were comparable to others reported for subhumid Mediterranean catchments and to those modelled worldwide for pasture land. Those lateral fluxes were equivalent to 10.4 % of the TOC stock from the topsoil at the moment of the check-dam construction and

  18. Nitrogen attenuation along delivery pathways in agricultural catchments

    Science.gov (United States)

    McAleer, Eoin; Mellander, Per-Erik; Coxon, Catherine; Richards, Karl G.

    2014-05-01

    Hillslope hydrologic systems and in particular near-stream saturated zones are active sites of nitrogen (N) biogeochemical dynamics. The efficiency of N removal and the ratio of reaction products (nitrous oxide and dinitrogen) in groundwater is highly variable and depends upon aquifer hydrology, mineralogy, dissolved oxygen, energy sources and redox chemistry. There are large uncertainties in the closing of N budgets in agricultural catchments. Spatial and temporal variability in groundwater physico-chemistry, catchment hydrology and land-use gives rise to hotspots and hot moments of N attenuation. In addition the production, consumption and movement of denitrification products remains poorly understood. The focus of this study is to develop a holistic understanding of N dynamics in groundwater as it moves from the top of the hillslope to the stream. This includes saturated groundwater flow, exchange at the groundwater-surface water interface and hyporheic zone flow. This project is being undertaken in two ca. 10km2 Irish catchments, characterised by permeable soils. One catchment is dominated by arable land overlying slate bedrock and the other by grassland overlying sandstone. Multi-level monitoring wells have been installed at the upslope, midslope and bottom of each hillslope. The piezometers are screened to intercept the subsoil, weathered bedrock and competent bedrock zones. Groundwater samples for nitrate (NO3-N) nitrite (NO2-N), ammonium (NH4-N) and total nitrogen are collected on a monthly basis while dissolved gas concentrations are collected seasonally. Groundwater NO3-N profiles from monitoring data to date in both catchments differ markedly. Although the two catchments had similar 3 year mean concentrations of 6.89 mg/L (arable) and 6.24 mg/L (grassland), the grassland catchment had higher spatial and temporal variation. The arable catchment showed relatively homogenous NO3-N concentrations in all layers and zones (range: 1.2 - 12.13 mg/L, SD = 1.60 mg

  19. Debris flows and cosmogenic catchment wide denudation rates

    Science.gov (United States)

    Kober, F.; Hippe, K.; Salcher, B.; Ivy-Ochs, S.; Kubik, P. W.; Christl, M.; Wacker, L.

    2012-04-01

    One of the basic question in alpine Quantitative Geomorphology is: Are widely measured cosmogenic nuclide-derived denudation rates in alpine catchments truly representative for the whole catchment at any given time? Or in contrast can they vary markedly in response to extreme events and perturbations? And if such perturbations affect cosmogenic nuclide-derived denudation rates then what bias can occur when such denudation rates are compared with sediment yield or thermochronological data or to various morphometric parameters, such as slope, mean elevation or uplift rates as potential controlling factors? We present 10Be and 14C results measured in sand samples from an active river channel from a single catchment (upper Aare), in the Swiss Alps (up to monthly sampling between 2008 to 2011). Our goal was to establish a time series to see if extreme events (such as landslides or debris flows) do have a discernible effect on derived denudation rates. The admixture of sediment of debris flows in 2009, originating upstream of the sampling spot, began to have a marked effect on 10Be concentrations and thus catchment wide denudation rates that are assumed to be in a long-term range mode prior to 2009. In summer of 2010, several extreme debris flows were recorded in the studied catchment. Samples taken document a doubling of denudation rates over the values determined from 2008. These cosmogenic nuclide data clearly demonstrate the impact of episodic events on sediment flux and the related perturbation of catchment wide denudation rates. We have recently expanded this dataset into 2011, with i) a spatial sub-sampling of debris flow and non-debris flow catchment compartments and ii) including again a major debris flow event in early autumn 2011. These data will be presented at the conference. Never-the-less the fact that the CWDR's only doubled does suggest a certain robustness in the method beyond a certain catchment size. In addition to the 10Be data, in situ 14C

  20. Comparison of subsurface connectivity in Alpine headwater catchments

    Science.gov (United States)

    Zuecco, Giulia; Rinderer, Michael; van Meerveld, Ilja; Penna, Daniele; Borga, Marco

    2016-04-01

    Saturation at the soil-bedrock interface or the rise of shallow groundwater into more permeable soil layers results in subsurface stormflow and can lead to hillslope-stream connectivity. Despite the importance of subsurface connectivity for streamflow and streamwater chemistry, the factors controlling its spatial and temporal variability are still poorly understood. This study takes advantage of networks of spatially-distributed piezometers in five small (stream when shallow groundwater was observed in the piezometer and it was connected by the edges to the stream. Weights were given to each piezometer based on Thiessen polygons to determine the area of the catchment that was connected to the stream. For the Swiss pre-alpine catchments the duration that nodes were connected to the stream was significantly correlated to the local and upslope site characteristics, such as the topographic wetness index, local slope and curvature. For the dolomitic catchment with the largest riparian zone, the time that nodes were connected to the stream was correlated with downslope site characteristics, such as the vertical distance to the nearest stream. The temporal changes in the area of the catchment that was connected to the stream reflected the streamflow dynamics for all catchments. Subsurface connectivity increased during rainfall events but there was a short delay compared to streamflow, suggesting that other processes (e.g. direct channel precipitation, runoff from near stream saturated areas) contributed to streamflow at the beginning of the event. Groundwater levels declined later and slower than streamflow, resulting in complex but mainly anti-clockwise hysteretic relations between streamflow and the area that was connected to the stream. Threshold-like relations between maximum connectivity and total stormflow and between maximum connectivity and the sum of total rainfall plus antecedent rainfall were more evident for the dolomitic catchments, where the riparian zone is

  1. The ethics of socio-ecohydrological catchment management: towards hydrosolidarity

    Directory of Open Access Journals (Sweden)

    M. Falkenmark

    2002-01-01

    Full Text Available This paper attempts to clarify key biophysical issues and the problems involved in the ethics of socio-ecohydrological catchment management. The issue in managing complex systems is to live with unavoidable change while securing the capacity of the ecohydrological system of the catchment to sustain vital ecological goods and services, aquatic as well as terrestrial, on which humanity depends ultimately. Catchment management oriented to sustainability has to be based on ethical principles: human rights, international conventions, sustaining crucial ecological goods and services, and protecting ecosystem resilience, all of which have water linkages. Many weaknesses have to be identified, assessed and mitigated to improve the tools by which the ethical issues can be addressed and solved: a heritage of constraining tunnel vision in both science and management; inadequate shortcuts made in modern scientific system analyses (e.g. science addressing sustainability issues; simplistic technical-fix approaches to water and ecosystems in land/water/ecosystem management; conventional tools for evaluation of scientific quality with its focus on “doing the thing right” rather than “doing the right thing”. The new ethics have to incorporate principles that, on a catchment basis, allow for proper attention to the hungry and poor, upstream and downstream, to descendants, and to sites and habitats that need to be protected. Keywords: catchment, hydrosolidarity, ecosystem, water determinants, resilience, green water, blue water, sustainability science

  2. Minimizing the effects of filtering on catchment scale GRACE solutions

    Science.gov (United States)

    Dutt Vishwakarma, Bramha; Devaraju, Balaji; Sneeuw, Nico

    2016-08-01

    The Gravity Recovery and Climate Experiment (GRACE) satellite mission has provided time variable gravity information since its launch in 2002. Due to short-wavelength noise, the total water storage variations over a catchment observed from GRACE are usable only after filtering. Filtering smooths both the signal and the noise, inevitably changing the nature of the estimated total water storage change. The filtered estimates suffer from attenuation and leakage, which changes the signal characteristics. Several studies have mainly focused on correcting the changed amplitude with the aid of hydrological models. In this study, it is demonstrated that in addition to the amplitude loss, also significant phase change in the time series of total water storage over a region can occur. The phase change due to leakage from nearby catchments can be around 20° to 30° for catchments with moderate size, which makes it difficult to retrieve signal by only scaling. We propose a strategy to approach the true time series with improved phase and amplitude. The strategy is independent of any hydrological model. It is first demonstrated in a closed-loop environment over 32 catchments, where we show that the performance of our method is consistent and better than other model-dependent approaches. Then we also discuss the limitations of our approach. Finally we apply our method to the GRACE level 2 products for 32 catchments.

  3. Hydrological drought across the world: impact of climate and physical catchment structure

    Directory of Open Access Journals (Sweden)

    H. A. J. Van Lanen

    2012-10-01

    Full Text Available Large-scale hydrological drought studies have demonstrated spatial and temporal patterns in observed trends and considerable difference exists among global hydrological models in their ability to reproduce these patterns. A controlled modeling experiment has been set up to systematically explore the role of climate and physical catchment structure (soils and groundwater systems to better understand underlying drought-generating mechanisms. Daily climate data (1958–2001 of 1495 grid cells across the world were selected that represent Köppen-Geiger major climate types. These data were fed into a hydrological model. Nine realizations of physical catchment structure were defined for each grid cell, i.e. three soils with different soil moisture supply capacity and three groundwater systems (quickly-, intermediary- and slowly-responding. Hydrological drought characteristics (number, duration and standardized deficit volume were identified from time series of daily discharge. Summary statistics showed that the equatorial and temperate climate types (A- and C-climates had about twice as many drought events as the arid and polar types (B- and E-climates and the duration of more extreme droughts were about half the length. Soils were found to have a minor effect on hydrological drought characteristics, whereas groundwater systems had major impact. Groundwater systems strongly controlled the hydrological drought characteristics of all climate types, but particularly those of the wetter A-, C- and D-climates because of higher recharge. The median number of drought for quickly-responding groundwater systems was about three times higher than for slowly-responding systems, which substantially affected the duration, particularly of the more extreme drought events. Bivariate probability distributions of drought duration and standardized deficit for combinations of Köppen-Geiger climate, soil and groundwater system showed that responsiveness of groundwater

  4. Hydrological drought across the world: impact of climate and physical catchment structure

    Directory of Open Access Journals (Sweden)

    H. A. J. Van Lanen

    2013-05-01

    Full Text Available Large-scale hydrological drought studies have demonstrated spatial and temporal patterns in observed trends, and considerable difference exists among global hydrological models in their ability to reproduce these patterns. In this study a controlled modeling experiment has been set up to systematically explore the role of climate and physical catchment structure (soils and groundwater systems to better understand underlying drought-generating mechanisms. Daily climate data (1958–2001 of 1495 grid cells across the world were selected that represent Köppen–Geiger major climate types. These data were fed into a conceptual hydrological model. Nine realizations of physical catchment structure were defined for each grid cell, i.e., three soils with different soil moisture supply capacity and three groundwater systems (quickly, intermediately and slowly responding. Hydrological drought characteristics (number, duration and standardized deficit volume were identified from time series of daily discharge. Summary statistics showed that the equatorial and temperate climate types (A- and C-climates had about twice as many drought events as the arid and polar types (B- and E-climates, and the durations of more extreme droughts were about half the length. Selected soils under permanent grassland were found to have a minor effect on hydrological drought characteristics, whereas groundwater systems had major impact. Groundwater systems strongly controlled the hydrological drought characteristics of all climate types, but particularly those of the wetter A-, C- and D-climates because of higher recharge. The median number of droughts for quickly responding groundwater systems was about three times higher than for slowly responding systems. Groundwater systems substantially affected the duration, particularly of the more extreme drought events. Bivariate probability distributions of drought duration and standardized deficit for combinations of K

  5. Actinobacteria from arid and desert habitats: diversity and biological activity

    Directory of Open Access Journals (Sweden)

    Joachim eWink

    2016-01-01

    Full Text Available Abstract The lack of new antibiotics in the pharmaceutical pipeline guides more and more researchers to leave the classical isolation procedures and to look in special niches and ecosystems. Bioprospecting of extremophilic Actinobacteria through mining untapped strains and avoiding resiolation of known biomolecules is among the most promising strategies for this purpose. With this approach, members of acidtolerant, alkalitolerant, psychrotolerant, thermotolerant, halotolerant and xerotolerant Actinobacteria have been obtained from respective habitats. Among these, little survey exists on the diversity of Actinobacteria in arid areas, which are often adapted to relatively high temperatures, salt concentrations, and radiation. Therefore, arid and desert habitats are special ecosystems which can be recruited for the isolation of uncommon Actinobacteria with new metabolic capability.At the time of this writing, members of Streptomyces, Micromonospora, Saccharothrix, Streptosporangium, Cellulomonas, Amycolatopsis, Geodermatophilus, Lechevalieria, Nocardia and Actinomadura are reported from arid habitats. However, metagenomic data present dominant members of the communities in desiccating condition of areas with limited water availability that are not yet isolated. Furthermore, significant diverse types of polyketide synthase (PKS and nonribosomal peptide synthetase (NRPS genes are detected in xerophilic and xerotolerant Actinobacteria and some bioactive compounds are reported from them. Rather than pharmaceutically active metabolites, molecules with protection activity against drying such as Ectoin and Hydroxyectoin with potential application in industry and agriculture have also been identified from xerophilic Actinobacteria. In addition, numerous biologically active small molecules are expected to be discovered from arid adapted Actinobacteria in the future. In the current survey, the diversity and biotechnological potential of Actinobacteria

  6. Quantification of the Aridity Process in South-Western Romania

    Directory of Open Access Journals (Sweden)

    Daniel Peptenatu

    2013-05-01

    Full Text Available The report released by the Intergovernmental Committee for Climate Change indicates that Romania ranks among the top seven countries in Europe that would be strongly impacted by aridity in the next few years, with climate changes consisting in a rise of average annual temperatures by as much as 5°C. The research work was conducted in the South of the Oltenia South-Western Development Region, where more than 700,000 hectares of farmland is impacted by aridification, more than 100,000 hectares among them impacted by aridity. Research methodology encompassed the analysis of average annual temperatures over the time span data was available for, at three weather stations, an analysis of average annual precipitations, an analysis of the piezometric data, the evolution of land use as a result of the expansion of the aridity process. The assessment of the aridity process also involved taking into consideration the state of the vegetation by means of the normalized difference vegetation index (NDVI, used to assess the quality of the vegetal stratum, an important element in the complex analysis of the territory. The aridity process is an effect of global warming, and, based on the results of this study, the post-1990 escalation of its effects was brought about by socio-economic factors. The destruction of the irrigation systems and protective forest belts because of the uncertain situation of land ownership are the main factors that contributed to amplification of the effects of aridity on the efficiency of agricultural systems that nowadays are exposed to very high risks.

  7. A 1000-year chironomid-based salinity reconstruction from varved sediments of Sugan Lake, Qaidam Basin, arid Northwest China, and its palaeoclimatic significance

    Institute of Scientific and Technical Information of China (English)

    CHEN JianHui; CHEN FaHu; ZHANG EnLou; BROOKS Stephen J; ZHOU AiFeng; ZHANG JiaWu

    2009-01-01

    A 1000-year high-resolution (~10 years) chironomid record from varved sediments of Sugan Lake, Qaidam Basin on the northern Tibetan Plateau, is presented. The chironomid assemblages are mainly composed of the relatively high-saline-water taxa Psectrocladius barbimanus-type and Orthocladius/Cricotopus, and the relatively low-saline-water taxa Procladius and Psectrocladius sordidellus-type. Variations in the chironomid fauna and inferred salinities suggest that over the last millennium, the Sugan Lake catchment has alternated between contrasting climatic conditions, having a dry climate during the period 990-1550 AD, a relatively humid climate during the Little Ice Age (LIA) (1550-1840 AD), and a dry climate again from 1840 AD onwards. At the decadal to centennial scale, a wet event around 1200-1230 AD, interrupting the generally arid period (990-1550 AD), and a dry event around 1590-1700 AD, punctuating the generally humid period (1550-1840 AD), are clearly documented. Trends in the chironomid-based salinity time series indicate a highly unstable climate during the LIA when salinity fluctuations were of greater magnitude and higher frequency. The effective moisture evolution in the Sugan Lake catchment during the last millennium reconstructed by chironomid analysis is in broad agreement with previous palaeo-moisture data derived from other sites in arid Northwest China (ANC). The LIA, characterized by generally humid conditions over the west-erly-dominated ANC was distinctly different from that in monsoonal China, implying an "out-of-phase" relationship between moisture evolution in these two regions during the past 1000 years.

  8. Monitoring small reservoirs in semi-arid region by satellite SAR data

    Science.gov (United States)

    Nicolina Papa, Maria; Mitidieri, Francesco; Amitrano, Donato; Ruello, Giuseppe; Di Martino, Gerardo; Iodice, Antonio; Riccio, Daniele

    2016-04-01

    The work presents a novel tool for the monitoring of small reservoirs in semi-arid regions. The pilot project was developed in the Yatenga region, a Sahelian area in northern Burkina Faso. In semi-arid regions, small reservoirs are widely employed for facing seasonal variability in water availability due to the alternation of a rainy (3 months) and a dry (9 months) season. Beside their crucial importance, the small reservoirs are not appropriately monitored, they are often built for the initiative of small local communities and even basic data as their location and capacity are not available. Another major problem is linked to soil erosion due to water and consequent reservoirs' sedimentation that reduces the amount of available water and the life span of reservoirs. This lack of data prevents the implementation of strategies for the optimization of water resources management. It is therefore necessary to improve the data availability through the development of cost-effective monitoring techniques and to adapt the hydrological modeling to the limited available data. In this context the use if satellite data can highly contribute to the achievement of crucial information at low costs, high resolution in time and wide areas. In the present work, we used COSMO-SkyMed Stripmap (3m resolution) and Spotligth (1m resolution) Synthetic Aperture Radar (SAR) data acquired under the aegis of the 2007 Italian Space Agency Announcement of Opportunity and of the HydroCIDOT project. The shorelines of the reservoirs were extracted from the series of SAR images by employing an innovative change-detection framework. A digital elevation model (DEM) of the study area was obtained via standard interferometry processing of images acquired at the end of the dry season, when small reservoirs are completely empty, and information about the surface usually covered by water can be retrieved. The obtained DEM and shorelines were used for bathymetry extraction of reservoirs. For the

  9. New crops for arid lands. [Jojoba; Buffalo gourd; Bladderpod; Gumweed

    Energy Technology Data Exchange (ETDEWEB)

    Hinman, C.W.

    1984-09-28

    Five plants are described that could be grown commercially under arid conditions. Once the most valuable component has been obtained from each plant (rubber from guayule; seed oil from jojoba, buffalo gourd, and bladderpod; and resin from gumweed), the remaining material holds potential for useful products as well as fuel. It is difficult to realize the full potential of arid land plants, however, because of the complexities of developing the necessary agricultural and industrial infrastructure simultaneously. To do so, multicompany efforts or cooperative efforts between government and the private sector will be required.

  10. Potential of arid zone vegetation as a source of substrates

    Energy Technology Data Exchange (ETDEWEB)

    Bassham, J.A.

    1977-11-01

    Three aspects of the potential of vegetation in arid zones as a source of substrates are discussed. The first includes the limitations on efficiency of conversion of solar energy to the stored chemical energy of biomass in green plants, and the subsequent biochemical pathways of carbon dioxide fixation and biosynthesis. Second is the potential of plants endogenous to arid zones. Finally, the use of covered agriculture or controlled environmental agriculture (CEA) is considered both in its present form and in terms of possible extenion to the large scale production of stable crops. (JGB)

  11. Mediterranean semi-arid systems-sensitivity and adaptation

    Energy Technology Data Exchange (ETDEWEB)

    Lavee, H.; Sarah, P.

    2009-07-01

    The semi-arid areas of the Mediterranean are sensitive to climate change as they are located. In many cases, between two different systems, the arid system and the Mediterranean sub-humid system. A number of quick response ecogeomorphological variables were monitored along a climatic transect in Israel, running from west to east, covering an annual rainfall range of 700-100mm. The relationships of climatic conditions-available water soil properties overland flow erosion, were investigates. Soil samples were taken from open areas between shrubs and overland flow was monitored in posts of 7, 14 and 21 m in length (3m width). (Author)

  12. Workshop on environmental changes of arid regions convenes in Inner Mongolia

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ Hosted by the CAS Institute of Geology and Geophysics and the local government, the International Workshop on Environmental Changes and Sustainable Development in Arid and Semi-arid Regions was held recently in Alashan Left Banner, Inner Mongolia.

  13. Understanding processes that generate flash floods in the arid Judean Desert to the Dead Sea - a measurement network

    Science.gov (United States)

    Hennig, Hanna; Rödiger, Tino; Laronne, Jonathan B.; Geyer, Stefan; Merz, Ralf

    2016-04-01

    Flash floods in (semi-) arid regions are fascinating in their suddenness and can be harmful for humans, infrastructure, industry and tourism. Generated within minutes, an early warning system is essential. A hydrological model is required to quantify flash floods. Current models to predict flash floods are often based on simplified concepts and/or on concepts which were developed for humid regions. To more closely relate such models to local conditions, processes within catchments where flash floods occur require consideration. In this study we present a monitoring approach to decipher different flash flood generating processes in the ephemeral Wadi Arugot on the western side of the Dead Sea. To understand rainfall input a dense rain gauge network was installed. Locations of rain gauges were chosen based on land use, slope and soil cover. The spatiotemporal variation of rain intensity will also be available from radar backscatter. Level pressure sensors located at the outlet of major tributaries have been deployed to analyze in which part of the catchment water is generated. To identify the importance of soil moisture preconditions, two cosmic ray sensors have been deployed. At the outlet of the Arugot water is sampled and level is monitored. To more accurately determine water discharge, water velocity is measured using portable radar velocimetry. A first analysis of flash flood processes will be presented following the FLEX-Topo concept .(Savenije, 2010), where each landscape type is represented using an individual hydrological model according to the processes within the three hydrological response units: plateau, desert and outlet. References: Savenije, H. H. G.: HESS Opinions "Topography driven conceptual modelling (FLEX-Topo)", Hydrol. Earth Syst. Sci., 14, 2681-2692, doi:10.5194/hess-14-2681-2010, 2010.

  14. The role of upland wetlands in modulating snowmelt runoff in the semi-arid Andes

    Science.gov (United States)

    Hevia, Andres; Sproles, Eric; Soulsby, Chris; Tetzlaff, Doerthe

    2016-04-01

    The wetlands, or bofedales, of semi-arid northern central Chile (29°-32°S) provide a critical store of water that modulate spring snowmelt runoff. Water released from bofedales helps sustain flows throughout the dry portions of the year, providing fresh water to downstream residents and a robust tourist, agricultural, and mining economy. In the Río Claro watershed (30°S, 1515 km2, 800m to 5500 m a.s.l.) a series fourteen bofedales have formed at natural choke points in the valley bottoms of the headwater reaches. The highly erosive dynamic of this watershed provides ample sediment, and some of these bofedales are up to 30 m deep. Annual precipitation in the region is limited to 4-6 events annually that fall primarily as snow at elevations above 3500 m. The subsurface storage of the headwaters is limited by the steep terrain of the headwater catchments that are devoid of soils and primarily underlain by granite bedrock. Downstream, irrigated area has increased by 200% between 1985 and 2005, driven by the cultivation of table grapes for export. For over 70 years local water managers have flooded the bodfedales during spring runoff to augment late season flow when irrigation demand peaks. While this low-tech strategy has worked in the past, a recent 8-year drought has raised concerns over long-term water security. We apply geophysical and geographic measurements, water quality, and stable isotopic tracers to calculate the volume of water storage and residence times in the bofedales of Río Claro. This information will be used to evaluate the reliability of the bofedale system as compared to a proposed reservoir in the headwaters of the Río Claro. Additionally, estimating the storage and residence times of the will help reduce uncertainty for modeling efforts currently underway in Río Claro.

  15. The causes of flow regime shifts in the semi-arid Hailiutu River, Northwest China

    Directory of Open Access Journals (Sweden)

    Z. Yang

    2012-01-01

    Full Text Available Identifying the causes (climate vs. human activities for hydrological variability is a major challenge in hydrology. This paper examines the flow regime shifts, changes in the climatic variables such as precipitation, evaporation, temperature, and crop area in the semi-arid Hailiutu catchment in the middle section of the Yellow River by performing several statistical analyses. The Pettitt test, cumulative sum charts (CUSUM, regime shift index (RSI method, and harmonic analysis were carried out on annual, monthly, and daily discharges. Four major shifts in the flow regime have been detected in 1968, 1986, 1992 and 2001. Characteristics of the flow regime were analyzed in the five periods: 1957–1967, 1968–1985, 1986–1991, 1992–2000, and 2001–2007. From 1957 to 1967, the flow regime reflects quasi natural conditions of the high variability and larger amplitude of 6 months periodic fluctuations. The river peak flow was reduced by the construction of two reservoirs in the period 1968–1985. In the period of 1986–1991, the river discharge further decreased due to the combined influence of river diversions and increase of groundwater extractions for irrigation. In the fourth period of 1992–2000, the river discharge reached lowest flow and variation in corresponding to a large increase in crop area. The flow regime recovered, but not yet to natural status in the fifth period of 2001–2007. Climatic factors are found not likely responsible for the changes in the flow regime, but the changes in the flow regime are corresponding well to historical land use policy changes.

  16. The causes of flow regime shifts in the semi-arid Hailiutu River, Northwest China

    Directory of Open Access Journals (Sweden)

    Z. Yang

    2011-06-01

    Full Text Available Identifying the causes (climate vs. human activities for hydrological variability is a major challenge in hydrology. This paper examines the flow regime shifts, changes in the climatic variables such as precipitation, evaporation, temperature, and crop area in the semi-arid Hailiutu catchment in the middle section of the Yellow River by performing several statistical analyses. The Pettitt test, cumulative sum charts (CUSUM, regime shift index (RSI method, and harmonic analysis were carried out on annual, monthly, and daily discharges. Four major shifts in the flow regime have been detected in 1968, 1986, 1992 and 2001. Characteristics of the flow regime were analyzed in the five periods: 1957–1967, 1968–1985, 1986–1991, 1992–2000, and 2001–2007. From 1957 to 1967, the flow regime reflects quasi natural conditions with high variability and larger amplitude of 6 months periodic fluctuations. The river flow had been affected by the construction of two reservoirs in the period 1968–1985. In the period of 1986–1991, the river discharge decreased due to the combined influence of river diversions and increase of groundwater extractions for irrigation. In the fourth period of 1992–2000, the river discharge reached lowest flow values and variations corresponding to a large increase in crop area. The flow regime recovered, but not yet to natural status in the fifth period of 2001–2007. Climatic factors are not responsible for all these changes in the flow regime, but the changes are corresponding well to human activities.

  17. A PROPOSED NEW VEGETATION INDEX, THE TOTAL RATIO VEGETATION INDEX (TRVI, FOR ARID AND SEMI-ARID REGIONS

    Directory of Open Access Journals (Sweden)

    H. Fadaei

    2012-07-01

    Full Text Available Vegetation indices that provide important key to predict amount vegetation in forest such as percentage vegetation cover, aboveground biomass, and leaf-area index. Arid and semi-arid areas are not exempt of this rule. Arid and semi-arid areas of northeast Iran cover about 3.4 million ha and are populated by two main tree species, the broadleaf Pistacia vera (pistachio and the conifer Juniperus excelsa ssp. polycarpos (Persian juniper. Natural stands of pistachio in Iran are not only environmentally important but also genetically essential as seed sources for pistachio production in orchards. We investigated the relationships between tree density and vegetation indices in the arid and semi-arid regions in the northeast of Iran by analysing Advanced Land Observing Satellite (ALOS data PRISM is a panchromatic radiometer with a 2.5 m spatial resolution at nadir, and has one band with a wavelength of 0.52–0.77 μm (JAXA EORC. AVNIR-2 is a visible and near infrared radiometer for observing land and coastal zones with a 10 m spatial resolution at nadir, and has four multispectral bands: blue (0.42–0.50 μm, green (0.52–0.60 μm, red (0.61–0.69 μm, and near infrared (0.76–0.89 μm (JAXA EORC. In this study, we estimated various vegetation indices using maximum filtering algorithm (5×5 and examined. This study carried out of juniper forests and natural pistachio stand using Advanced Land Observing Satellite (ALOS and field inventories. Have been compared linear regression model of vegetation indices and proposed new vegetation index for arid and semi-arid regions. Also, we estimated the densities of juniper forests and natural pistachio stands using remote sensing to help in the sustainable management and production of pistachio in Iran. We present a new vegetation index for arid and semi-arid regions with sparse forest cover, the Total Ratio Vegetation Index (TRVI, and we investigate the relationship of the new index to tree density by

  18. Modelling a river catchment using an electrical circuit analogue

    Directory of Open Access Journals (Sweden)

    C. G. Collier

    1998-01-01

    Full Text Available An electrical circuit analogue of a river catchment is described from which is derived an hydrological model of river flow called the River Electrical Water Analogue Research and Development (REWARD model. The model is based upon an analytic solution to the equation governing the flow of electricity in an inductance-capacitance-resistance (LCR circuit. An interpretation of L, C and R in terms of catchment parameters and physical processes is proposed, and tested for the River Irwell catchment in northwest England. Hydrograph characteristics evaluated using the model are compared with observed hydrographs, confirming that the modelling approach does provide a reliable framework within which to investigate the impact of variations in model input data.

  19. Streamflow Characteristics of Two Forested Catchments in the Sopron Hills

    Directory of Open Access Journals (Sweden)

    GRIBOVSZKI, Zoltán

    2006-01-01

    Full Text Available One of the central issues in hydrology is today to establish a relationship between thehydrological and biological processes in ecosystems. One question of this theme is the vegetationimpact on the water budget of the catchment. Water use by vegetation can closely be linked tostreamflow patterns on a variety of time scales. At present many details of these connections arepoorly understood.Investigation on small catchments is the best way of studying hydrological processes in headwater,forested watersheds. In this paper drainage basin morphology and streamflow characteristics (baseflow and quick flow have been analysed under conditions of forest management in two neighbouringsmall forested catchments (the Farkas Valley and Vadkan Valley located in the prealpine hillsbordering to Austria on the basis of streamflow data collected during 2001.

  20. The hydrological response of catchments to simulated changes in climate

    Energy Technology Data Exchange (ETDEWEB)

    Viney, Neil R.; Sivapalan, Murugesu [Centre for Water Research, University of Western Australia, Nedlands, WA (Australia)

    1996-04-17

    The Large Scale Catchment Model has been developed to predict the responses in stream yield and salinity to changes in land use and climate in southwestern Western Australia. In this paper it is used to simulate, for one small forested catchment, the hydrological consequences that might be associated with a doubling of the atmospheric carbon dioxide concentration. The simulations assume that the region will experience a decrease in the amount of winter rainfall (with an increase in rainfall intensity) and an increase in potential evaporation. The results suggest that the assumed change in climate has the potential to lead to a 45% decrease in stream runoff in this catchment. About two-thirds of this decrease is associated with the reduction in rainfall; the remainder being associated with the increased potential evaporation. Furthermore, stream salinity is predicted to increase by about 8%, mostly in response to the enhanced evaporation regime

  1. Transit times of water particles in the vadose zone across catchment states and catchments functional units

    Science.gov (United States)

    Sprenger, Matthias; Weiler, Markus

    2014-05-01

    Understanding the water movement in the vadose zone and its associated transport of solutes are of major interest to reduce nutrient leaching, pollution transport or other risks to water quality. Soil physical models are widely used to asses such transport processes, while the site specific parameterization of these models remains challenging. Inverse modeling is a common method to adjust the soil physical parameters in a way that the observed water movement or soil water dynamics are reproduced by the simulation. We have shown that the pore water stable isotope concentration can serve as an additional fitting target to simulate the solute transport and water balance in the unsaturated zone. In the presented study, the Mualem- van Genuchten parameters for the Richards equation and diffusivity parameter for the convection-dispersion equation have been parameterized using the inverse model approach with Hydrus-1D for 46 experimental sites of different land use, topography, pedology and geology in the Attert basin in Luxembourg. With the best parameter set we simulated the transport of a conservative solute that was introduced via a pulse input at different points in time. Thus, the transit times in the upper 2 m of the soil for different catchment states could be inferred for each location. It has been shown that the time a particle needs to pass the -2 m depth plane highly varies from the systems state and the systems forcing during and after infiltration of that particle. Differences in transit times among the study sites within the Attert basin were investigated with regards to its governing factors to test the concept of functional units. The study shows the potential of pore water stable isotope concentration for residence times and transport analyses in the unsaturated zone leading to a better understanding of the time variable subsurface processes across the catchment.

  2. Susceptibility of Shallow Landslide in Fraser Hill Catchment, Pahang Malaysia

    Directory of Open Access Journals (Sweden)

    Wan Nor Azmin Sulaiman

    2010-01-01

    Full Text Available In tropical areas especially during monsoon seasons intense precipitation is the main caused that trigger the natural shallow landslide phenomena. This phenomenon can be disastrous and widespread in occurrence even in undisturbed forested catchment. In this paper, an attempt has been made to evaluate the susceptibility of natural hill slopes to failure for a popular hill resort area, the Fraser Hill Catchment under different rainfall regimes and soil thickness. A Digital Elevation Model (DEM was prepared for the 8.2 km2 catchment. A GIS based deterministic model was then applied to predict the spatial landslide occurrence within catchment. Model input parameters include bulk density, friction angle, cohesion and hydraulic conductivity were gathered through in situ and lab analysis as well as from previous soil analysis records. Landslides locations were recorded using GPS as well as previous air photos and satellite imagery to establish landslide source areas inventory. The landslide susceptibility map was produced under different precipitation event’s simulation to see the effects of precipitation to stability of the hill slopes of the catchment. The results were categorized into naturally unstable (Defended, Upper Threshold, Lower Threshold, marginal instability (Quasi Stable and stable area (Moderately Stable and Stable. Results of the simulation indicated notable change in precipitation effect on Defended area is between 10mm to 40mm range in a single storm event. However, when storm event is exceeded 120mm, the result on Defended area produced by the model tends to be constant further on. For area categorized as naturally unstable (Factor of Safety, SF<1, with 110 mm of precipitation in a single storm event and soil depth at 2 meters and 4 meters could affect 69.51% and 69.88% respectively of the catchment area fall under that class. In addition, the model was able to detect 4% more of the landslide inventory under shallower soil depth of

  3. Organic carbon efflux from a deciduous forest catchment in Korea

    Directory of Open Access Journals (Sweden)

    S. J. Kim

    2010-04-01

    Full Text Available Soil infiltration and surface discharge of precipitation are critical processes that affect the efflux of Dissolved Organic Carbon (DOC and Particulate Organic Carbon (POC in forested catchments. Concentrations of DOC and POC can be very high in the soil surface in most forest ecosystems and their efflux may not be negligible particularly under the monsoon climate. In East Asia, however, there are little data available to evaluate the role of such processes in forest carbon budget. In this paper, we address two basic questions: (1 how does stream discharge respond to storm events in a forest catchment? and (2 how much DOC and POC are exported from the catchment particularly during the summer monsoon period? To answer these questions, we collected hydrological data (e.g., precipitation, soil moisture, runoff discharge, groundwater level and conducted hydrochemical analyses (including DOC, POC, and six tracers in a deciduous forest catchment in Gwangneung National Arboretum in west-central Korea. Based on the end-member mixing analysis of the six storm events during the summer monsoon in 2005, the surface discharge was estimated as 30 to 80% of the total runoff discharge. The stream discharge responded to precipitation within 12 h during these storm events. The annual efflux of DOC and POC from the catchment was estimated as 0.04 and 0.05 t C ha−1 yr−1, respectively. Approximately 70% of the annual organic carbon efflux occurred during the summer monsoon period. Overall, the annual efflux of organic carbon was estimated to be about 10% of the Net Ecosystem carbon Exchange (NEE obtained by eddy covariance measurement at the same site. Considering the current trends of increasing intensity and amount of summer rainfall and the large interannual variability in NEE, ignoring the organic carbon efflux from forest catchments would result in an inaccurate estimation of the carbon sink strength of forest ecosystems in the monsoon

  4. Field-based study of connectivity in an agricultural catchment

    Science.gov (United States)

    Lexartza-Artza, I.; Wainwright, J.

    2009-12-01

    Field-based studies of hydrological connectivity can provide context-specific knowledge that might both help understand dynamic complex systems and contribute to other synthetic or modelling approaches. The importance of such an understanding of catchment processes and also of the knowledge of catchment connections with water bodies and the changes of concentration with scale for Integrated Catchment Management has been increasingly emphasized. To provide a holistic understanding, approaches to the study of connectivity need to include both structural and functional aspects of the system and must consider the processes taking place within and across different temporal and spatial scales. A semi-quantitative nested approach has been used to investigate connectivity and study the interactions and feedbacks between the factors influencing transfer processes in the Ingbirchworth Catchment, in the uplands of the River Don, England. A series of reconnaissance techniques have been combined with monitoring of aspects such as rainfall, runoff, sediment transfer and soil-moisture distribution from plot to catchment scale and with consideration of linkages between land and water bodies. The temporal aspect has also been considered, with a special focus on the temporal distribution of events and the influence of longer term catchment changes such as those in land use and management practices. A variability of responses has been observed in relation to the characteristics of events, land use and scale of observation, with elements traditionally considered as limiting or enhancing connectivity responding differently under changing conditions. Sediment redistribution, reshaping of structure and consequent reinforcing loops can be observed across all land uses and landscape units, but the relevance it terms of effective connectivity of highly connected patches varies as the scale is increased. The knowledge acquired can contribute to recognise emerging processes significant for

  5. Vulnerability of European freshwater catchments to climate change.

    Science.gov (United States)

    Markovic, Danijela; Carrizo, Savrina F; Kärcher, Oskar; Walz, Ariane; David, Jonathan N W

    2017-02-10

    Climate change is expected to exacerbate the current threats to freshwater ecosystems, yet multifaceted studies on the potential impacts of climate change on freshwater biodiversity at scales that inform management planning are lacking. The aim of this study was to fill this void through the development of a novel framework for assessing climate change vulnerability tailored to freshwater ecosystems. The three dimensions of climate change vulnerability are as follows: (i) exposure to climate change, (ii) sensitivity to altered environmental conditions and (iii) resilience potential. Our vulnerability framework includes 1685 freshwater species of plants, fishes, molluscs, odonates, amphibians, crayfish and turtles alongside key features within and between catchments, such as topography and connectivity. Several methodologies were used to combine these dimensions across a variety of future climate change models and scenarios. The resulting indices were overlaid to assess the vulnerability of European freshwater ecosystems at the catchment scale (18 783 catchments). The Balkan Lakes Ohrid and Prespa and Mediterranean islands emerge as most vulnerable to climate change. For the 2030s, we showed a consensus among the applied methods whereby up to 573 lake and river catchments are highly vulnerable to climate change. The anthropogenic disruption of hydrological habitat connectivity by dams is the major factor reducing climate change resilience. A gap analysis demonstrated that the current European protected area network covers climate change. Priority should be placed on enhancing stakeholder cooperation at the major basin scale towards preventing further degradation of freshwater ecosystems and maintaining connectivity among catchments. The catchments identified as most vulnerable to climate change provide preliminary targets for development of climate change conservation management and mitigation strategies.

  6. Multi-scale field investigation of water flow pathways and residence times in mountainous catchments during monsoon rainfall

    Science.gov (United States)

    Troch, P. A.; Lyon, S. W.; Desilets, S.

    2007-05-01

    The "sky islands" of Arizona and New Mexico in the southwestern United States form a unique complex of about 27 mountain ranges whose ecosystems support many perennial and ephemeral streams in an arid climate. Among these sky islands are the Santa Catalina Mountains near Tucson, AZ, with a peak elevation of 9157 ft at Mt. Lemmon. Sabino Canyon Creek is the main stream which runs on the south face of the mountain range. It usually flows from July through April with an average daily flow of approximately 0.28 m3/s (10 cfs). However, flash floods are common both during summer as a result of intense monsoon rains and during spring because of rapid snowmelt. During these events, flow increases drastically, reaching peak flows up to 480 m3/s (15,984 cfs, July 2006). Characterizing water flow pathways and residence times in these complex catchments is important for improving flash flood warning systems, estimating mountain front recharge, managing forest and wild fires, and understanding ecosystem functions. In the summer of 2006, we set up an extensive hydrometrical and hydro- chemical monitoring network in Sabino Canyon Creek, comprising 40 tipping bucket rain gauges (two of which were equipped to automatically collect rainwater samples), 5 automatic surface water level stations (three of which were equipped with auto samplers), and 8 manual soil lysimeters. In addition, several rain and stream water grab samples were collected manually during intensive rain events. Water samples are analyzed for major ions and liquid water isotopic concentration (2H and 18O) in rain, soil, ground and surface water. The data allows for a detailed reconstruction of water flow pathways and residence times at 3 different catchment scales (2 km2, 8 km2, and 91 km2) during the recorded flow events, including the highest monsoon rainfall-runoff event ever recorded in these mountains.

  7. Olive Mounds, Roman cisterns, erosion pins - potential to characterize erosion in a Mediterranean catchment in north Jordan.

    Science.gov (United States)

    Kraushaar, Sabine; Ollesch, Gregor; Siebert, Christian; Vogel, Hans-Jörg

    2013-04-01

    In the framework of a three years' time period of a PhD thesis it is luck to catch the "right" rain events for good general erosion approximations. Methods that (i) cover longer time periods, (ii) are not confined to constructed boundaries, and finally (iii) include all possible erosion processes are crucial for good average estimates of sediment yields from different landscapes. The aim of the study was to get a first understanding of erosion processes and sediment yields in a Mediterranean to semi-arid catchment in NW Jordan, wherefore different measurement methods were tested in the predominant landscape units: olive orchards (27%), fields (14%) and natural shrubs on steep slopes (~30%). One of the applied methods was the measurement of topographic olive mounds within 7 orchards with an average size of 800 m2 in synergy with tree-coring and age estimation of the orchards. Furthermore the OSL dating of deposited sediments in two roman cisterns adjacent to fields was conducted and the 9 erosion pin fields, each about 200m2 large, were installed on steep slopes with natural vegetation. The methods cover different time scales from 560 years for the fields, an average of 32 years for the olive orchards and up to two rainy seasons for the erosion pin fields. Results show that olive orchards on steep slopes (>10%) have the highest erosion potential in the region with 95±8 t ha-1year-1 followed by natural vegetated slopes with 37±4 t ha-1year-1 of dislocated material and fields with 1.22±0.06 t ha-1year-1 sediment yield. These spatially constrained outcomes are supported by geochemical sediment fingerprint results of lake sediments from the catchment and will be discussed in regard to the basic assumption that underlie the principle of measurement and the limitations of the methods.

  8. Effects of environmental conditions on soil salinity and arid region in Tunisia

    Energy Technology Data Exchange (ETDEWEB)

    Ben Ahmed, C.; Ben Rouina, B.; Boukhris, M.

    2009-07-01

    The shortage of water resources of good water quality is becoming an issue in the arid and semi arid regions. for this reason, the use of water resources of marginal quality such as treated wastewater and saline groundwater has become and important consideration, particularly in arid region in Tunisia, where large quantities of saline water are used for irrigation. (Author)

  9. Hydrologic Analysis of Ungauged Catchments For The Supply of Water For Irrigation On Railway Embankment Batters

    Science.gov (United States)

    Gyasi-Agyei, Y.; Nissen, D.

    Water has been identified as a key component to the success of grass establishment on railway embankment batters (side slope) within Central Queensland, Australia, to control erosion. However, the region under study being semi-arid experiences less than 600 mm average annual rainfall occurring on about 60 days of the year. Culverts and bridges are integral part of railway embankments. They are used to cross water courses, be it an ephemeral creek or just a surface runoff path. Surface runoff through an ungauged railway embankment culvert is diverted to a temporary excavated pond located at the downstream side of the hydraulic structure. The temporary excavated pond water is used to feed an automated drip irrigation system, with solar as a source of energy to drive a pump. Railway embankment batter erosion remediation is timed in the wet season when irrigation is used to supplement natural rainfall. Hydrologic analysis of ungauged catchments for sizing the temporary excavated pond is presented. It is based on scenarios of runoff coefficient and curve number, and mass curve (Rippl diagram). Three years of continuous rainfall data (1997/1998 -1999/2000) were used to design a pond. The performance of the designed pond was evaluated in a field experiment during the next wet season (2000/2001). It supplied adequate water for irrigation as predicted by the hydrologic analysis during the grass establishment. This helped to achieve 100% grass cover on the railway embankment batter within 12 weeks. The proposed irrigation system has been demonstrated t o be feasible and cost effective.

  10. Evaporation and concentration gradients created by episodic river recharge in a semi-arid zone aquifer: Insights from Cl-, δ18O, δ2H, and 3H

    Science.gov (United States)

    Meredith, K. T.; Hollins, S. E.; Hughes, C. E.; Cendón, D. I.; Chisari, R.; Griffiths, A.; Crawford, J.

    2015-10-01

    This study has significantly advanced our understanding of the origin of groundwater recharge in a semi-arid zone region of the Darling River catchment, Australia. The generally accepted hypothesis in arid zone environments in Australia that river water forms the primary groundwater recharge source has proven difficult to monitor. This is due to the time lags between large floods, the remoteness and expense of studying these hydrologically complex systems in detail. In addition, the highly episodic nature of dryland rivers complicates the interpretation of the groundwater signal. A range of hydrochemical tracers (chloride, oxygen-18, deuterium and tritium) measured in rain, river water, soil water and groundwater were used in this multi-year study to trace the pathways of groundwater recharge under wet and dry climatic conditions. The evaporation and Cl concentrations observed in the unsaturated zone confirmed that small volumetric inputs from periodic rainfall were not the major recharge mechanism. Sampling which included an overbank flooding event in March 2012 provided firm evidence for groundwater originating from high flow episodic river recharge. The use of long-term environmental data to understand how economically important water resources respond to climate change with increasing temperatures is considered essential for future sustainability.

  11. A disaggregating approach to describe overland flow occurrence within a catchment

    NARCIS (Netherlands)

    Vigiak, O.; Romanowicz, R.; van Loon, E.E.; Sterk, G.; Beven, K.J.

    2006-01-01

    A parametrically parsimonious, data-based model was built on observations at hillslope and catchment scale to simulate the distribution of overland flow within a small East African Highlands catchment (Kwalei, Tanzania). A rainfall-flow Data Based Mechanistic model identified catchment effective rai

  12. Constitution of a catchment virtual observatory for sharing flow and transport models outputs

    Science.gov (United States)

    Thomas, Zahra; Rousseau-Gueutin, Pauline; Kolbe, Tamara; Abbott, Benjamin W.; Marçais, Jean; Peiffer, Stefan; Frei, Sven; Bishop, Kevin; Pichelin, Pascal; Pinay, Gilles; de Dreuzy, Jean-Raynald

    2016-12-01

    Predicting hydrological catchment behavior based on measurable (and preferably widely available) catchment characteristics has been one of the main goals of hydrological modelling. Residence time distributions provide synoptic information about catchment functioning and can be useful metrics to predict their behaviors. Moreover, residence time distributions highlight a wide range of characteristic scales (spatial and temporal) and mixing processes. However, catchment-specific heterogeneity means that the link between residence time distributions and catchment characteristics is complex. Investigating this link for a wide range of catchments could reveal the role of topography, geology, land-use, climate and other factors in controlling catchment hydrology. Meaningful comparison is often challenging given the diversity of data and model structures and formats. To address this need, we are introducing a new virtual platform called Catchment virtual Observatory for Sharing flow and transport models outputs (COnSOrT). The goal of COnSOrT is to promote catchment intercomparison by sharing calibrated model outputs. Compiling commensurable results in COnSOrT will help evaluate model performance, quantify inter-catchment controls on hydrology, and identify research gaps and priorities in catchment science. Researchers interested in sharing or using calibrated model results are invited to participate in the virtual observatory. Participants may test post-processing methods on a wide range of catchment environments to evaluate the generality of their findings.

  13. Modelling Pesticide Leaching At Column, Field and Catchment Scales I. Analysis of Soil Variability At Field and Catchment Scales

    Science.gov (United States)

    Gärdenäs, A.; Jarvis, N.; Alavi, G.

    The spatial variability of soil characteristics was studied in a small agricultural catch- ment (Vemmenhög, 9 km2) at the field and catchment scales. This analysis serves as a basis for assumptions concerning upscaling approaches used to model pesticide leaching from the catchment with the MACRO model (Jarvis et al., this meeting). The work focused on the spatial variability of two key soil properties for pesticide fate in soil, organic carbon and clay content. The Vemmenhög catchment (9 km2) is formed in a glacial till deposit in southernmost Sweden. The landscape is undulating (30 - 65 m a.s.l.) and 95 % of the area is used for crop production (winter rape, winter wheat, sugar beet and spring barley). The climate is warm temperate. Soil samples for or- ganic C and texture were taken on a small regular grid at Näsby Farm, (144 m x 144 m, sampling distance: 6-24 m, 77 points) and on an irregular large grid covering the whole catchment (sampling distance: 333 m, 46 points). At the field scale, it could be shown that the organic C content was strongly related to landscape position and height (R2= 73 %, p organic C content of hollows in the landscape is so high that they contribute little to the total loss of pesticides (Jarvis et al., this meeting). Clay content is also related to landscape position, being larger at the hilltop locations resulting in lower near-saturated hydraulic conductivity. Hence, macropore flow can be expected to be more pronounced (see also Roulier & Jarvis, this meeting). The variability in organic C was similar for the field and catchment grids, which made it possible to krige the organic C content of the whole catchment using data from both grids and an uneven lag distance.

  14. Reflexive Water Management in Arid Regions: The Case of Iran

    NARCIS (Netherlands)

    Balali, M.R.; Keulartz, F.W.J.; Korthals, M.

    2009-01-01

    To illuminate the problems and perspectives of water management in Iran and comparable (semi-) arid Middle East and North Africa (MENA) countries, three paradigms can be distinguished: the traditional, the industrial and the reflexive paradigm. Each paradigm is characterised by its key technical sys

  15. Evaporation as the transport mechanism of metals in arid regions.

    Science.gov (United States)

    Lima, Ana T; Safar, Zeinab; Loch, J P Gustav

    2014-09-01

    Soils of arid regions are exposed to drought and drastic temperature oscillations throughout the year. Transport mechanisms in these soils are therefore very different from the ones in temperate regions, where rain dictates the fate of most elements in soils. Due to the low rainfall and high evaporation rates in arid regions, groundwater quality is not threatened and all soil contamination issues tend to be overlooked. But if soil contamination happens, where do contaminants go? This study tests the hypothesis of upward metal movement in soils when evaporation is the main transport mechanism. Laboratory evaporation tests were carried out with heavy metal spiked Saudi soil, using circulation of air as the driving force (Fig. 1). Main results show that loamy soil retains heavy metals quite well while evaporation drives heavy metals to the surface of a sandy soil. Evaporation transports heavy metals upward in sandy soils of arid regions, making them accumulate at the soil surface. Sand being the dominating type of soil in arid regions, soils can then be a potential source of contaminated aerosols and atmospheric pollution - a transboundary problem. Some other repercussions for this problem are foreseen, such as the public ingestion or inhalation of dust.

  16. Agave Lechuguilla as a Potential Biomass Source in Arid Areas

    Directory of Open Access Journals (Sweden)

    Ahmad Houri

    2016-03-01

    Full Text Available Biomass productivity presents a challenging problem in arid and semi-arid areas.  Despite a large need for energy in the form of solid biomass, liquid fuel or needs for animal feed, these regions remain largely unproductive.  A convenient way to overcome this challenge is to utilize plants with high water-use efficiency.  Agave lechuguilla is an example of a highly productive (3.8 tons ha-1 yr-1 desert plant that holds the potential for producing biomass with minimal water resources.  For this purpose, a global suitability map has been developed showing areas where this plant can be planted, and its productivity was assessed.  A Maxent model was used and was further refined by excluding protected areas and used lands (urban, agriculture, etc...  Productivity assessment provides a good way forward for prioritizing the regional utilization of this plant.   This study provides an initial analysis for the use of arid and semi-arid regions for biomass production.  Results indicate the potential generation of 93.8 million tons per year of dry biomass if the suitable areas were fully utilized.  The analytical method can be readily applied to other potential plant species to optimize the use of certain areas.

  17. Extreme climatic events shape arid and semiarid ecosystems

    NARCIS (Netherlands)

    Holmgren, M.; Stapp, P.; Dickman, C.; Gracia, C.; Graham, S.

    2006-01-01

    Climatic changes associated with the El Nino Southern Oscillation (ENSO) can have a dramatic impact on terrestrial ecosystems worldwide, but especially on arid and semiarid systems, where productivity is strongly limited by precipitation. Nearly two decades of research, including both short-term exp

  18. Interspecific facilitation and critical transitions in arid ecosystems

    NARCIS (Netherlands)

    Verwijmeren, Mart; Rietkerk, Max; Wassen, Martin J.; Smit, Christian

    2013-01-01

    Climate change and intensified land-use impose severe stress on arid ecosystems, resulting in relatively rapid degradation which is difficult to reverse. To prevent such critical transitions it is crucial to detect early warning signals. Increased patchiness' smaller and fewer vegetated patches is t

  19. Trends and responses to global change of China's arid regions

    Institute of Scientific and Technical Information of China (English)

    Weixi YANG

    2009-01-01

    Ⅰ analyzed and elaborated the trends in and responses to global change in arid regions of China, from the perspective of nine variables, i.e., temperature, precipitation, river runoff, melting glaciers, water level of lakes, wind power and evaporation, vegetation, oases, and desertification. The climate and hydrology data Ⅰ citedrepresent many years of observations. Ⅰ conclude that, since the 1980s, the climate in arid regions of China has clearly changed with rising temperatures and precipitation in most areas. Wind power and the number of galestorm days have continuously decreased, which resulted in an improvement of humid conditions and increases in river discharge and water levels of lakes. Simultaneously, vegetation also has improved and the process of deserti-fication has essentially been arrested. Although there are some unfavorable developments, such as decreased river flows or flow interruptions and downstream oases have suffered from degradation, these incidental cases should not distract our attention from the generally favorable trends during the middle and late 20th century. These discordant phenomena are not consequences of climate change but rather of unsuitable human activities. Despitea substantial increase in precipitation, the level of the original precipitation was so small that any increase in precipitation was still small. As a result, none of the fundamental conditions such as a scarcity of water resources and precipitation nor the landscape of drought-ridden deserts in the arid regions will change. The vulnerability of the eco-environmental system in the arid regions will not change fundamentally either in the near future.

  20. Local facilitation, bistability and transitions in arid ecosystems

    NARCIS (Netherlands)

    Kéfi, S.; Rietkerk, M.G.; Baalen, M. van; Loreau, M.

    2007-01-01

    Arid ecosystems are liable to undergo sudden discontinuous transitions from a vegetated to a desert state as a result of human pressure and climate change. A predictive framework about the conditions under which such transitions occur is lacking. Here, we derive and analyze a general model describin

  1. Simulation of water use and herbage growth in arid regions

    NARCIS (Netherlands)

    Keulen, van H.

    1975-01-01

    The and and semi-arid regions of the world, totalling about 30% of the land surface of the earth, are predominantly used for extensive grazing, as low and erratic rainfall presents too high a risk for arable farming. The population that can be sustained by the animal products -meat, milk or wool- is

  2. Improved climate risk simulations for rice in arid environments

    NARCIS (Netherlands)

    Oort, van P.A.J.; Vries, de M.; Yoshida, H.; Saito, K.

    2015-01-01

    We integrated recent research on cardinal temperatures for phenology and early leaf growth, spikelet formation, early morning flowering, transpirational cooling, and heat- and cold-induced sterility into an existing to crop growth model ORYZA2000. We compared for an arid environment observed potenti

  3. On dew and micrometeorology in an arid coastal ecosystem

    NARCIS (Netherlands)

    Heusinkveld, B.G.

    2008-01-01

    This study investigated intriguing aspects of dew within a sandy arid ecosystem situated in the NW Negev desert, Israel. The goal was to quantify dew formation and evaporation processes through sensor design, field measurements and modelling. To do this, two new sensors were developed. The first sen

  4. Evaporation as the transport mechanism of metals in arid regions

    KAUST Repository

    Lima, Ana T.

    2014-09-01

    Soils of arid regions are exposed to drought and drastic temperature oscillations throughout the year. Transport mechanisms in these soils are therefore very different from the ones in temperate regions, where rain dictates the fate of most elements in soils. Due to the low rainfall and high evaporation rates in arid regions, groundwater quality is not threatened and all soil contamination issues tend to be overlooked. But if soil contamination happens, where do contaminants go? This study tests the hypothesis of upward metal movement in soils when evaporation is the main transport mechanism. Laboratory evaporation tests were carried out with heavy metal spiked Saudi soil, using circulation of air as the driving force (Fig. 1). Main results show that loamy soil retains heavy metals quite well while evaporation drives heavy metals to the surface of a sandy soil. Evaporation transports heavy metals upward in sandy soils of arid regions, making them accumulate at the soil surface. Sand being the dominating type of soil in arid regions, soils can then be a potential source of contaminated aerosols and atmospheric pollution - a transboundary problem. Some other repercussions for this problem are foreseen, such as the public ingestion or inhalation of dust. © 2014 Elsevier Ltd.

  5. Isotope hydrology of catchment basins: lithogenic and cosmogenic isotopic systems

    Energy Technology Data Exchange (ETDEWEB)

    Nimz, G. J., LLNL

    1998-06-01

    A variety of physical processes affect solute concentrations within catchment waters. The isotopic compositions of the solutes can indicate which processes have determined the observed concentrations. These processes together constitute the physical history of the water. Many solutes in natural waters are derived from the interaction between the water and the rock and/or soil within the system - these are termed `lithogenic` solutes. The isotopic compositions of these solutes provide information regarding rock-water interactions. Many other solutes have their isotopic compositions determined both within and outside of the catchment - i.e., in addition to being derived from catchment rock and soil, they are solutes that are also transported into the catchment. Important members of this group include solutes that have isotopic compositions produced by atomic particle interactions with other nuclides. The source of the atomic particles can be cosmic radiation (producing `cosmogenic` nuclides in the atmosphere and land surface), anthropogenic nuclear reactions (producing `thermonuclear` nuclides), or radioactive and fission decay of naturally-occurring elements, principally {sup 238}U (producing `in-situ` lithogenic nuclides in the deep subsurface). Current language usage often combines all of the atomic particle-produced nuclides under the heading `cosmogenic nuclides`, and for simplicity we will often follow that usage here, although always indicating which variety is being discussed. This paper addresses the processes that affect the lithogenic and cosmogenic solute concentrations in catchment waters, and how the isotopic compositions of the solutes can be used in integrative ways to identify these processes, thereby revealing the physical history of the water within a catchment system. The concept of a `system` is important in catchment hydrology. A catchment is the smallest landscape unit that can both participate in all of the aspects of the hydrologic cycle and

  6. Process-based hydrological modeling using SWAT: The effect of permafrost on water resources in the large-scale river catchment Kharaa / Mongolia

    Science.gov (United States)

    Hülsmann, L.; Geyer, T.; Karthe, D.; Priess, J.; Schweitzer, C.

    2012-04-01

    In this study, the Soil Water Assessment Tool (SWAT) was applied to obtain a better understanding of hydrological processes in the semi-arid catchment of the Kharaa River in Northern Mongolia. The transient, physical-based model SWAT was set up using spatial datasets on soil, land use, climate, and stream network provided by the project "IWRM-MoMo" to (i.) simulate the water balance components of the basin and (ii.) to identify potential gaps in the input data. We found that the SWAT model satisfactorily reflects the hydrological processes in the catchment and simulates river runoff as a response to strong rainfall events as well as to snow and ice melt. To obtain correct runoff volumes during spring, permafrost has to be considered. Permafrost-influenced soils constrain water flow in the frozen layer, so that percolation out of the active layer is hampered (Woo 2011). This effect is reproduced in SWAT by assigning an impermeable layer in the subsurface to the areas dominated by permafrost. The simulations indicate that in these regions groundwater resources are limited as a consequence of impermeable ground ice. In addition, groundwater recharge rates in the catchment are generally low due to high evaporation rates (80-90 %). Consequently the base flow contribution is small. Further studies on the estimation of groundwater recharge rates should be carried out, since groundwater is an important resource for water supply. Model results indicate that the non-uniformity of the precipitation distribution was not sufficiently covered by the interpolated input data, so that precipitation and runoff volumes are partially over- or underestimated. Since precipitation defines the overall water availability in river catchments (Baumgartner 1982), additional climate records would considerably improve model outputs. As a consequence of large evapotranspiration losses, discharge as well as groundwater recharge estimates were identified to be highly sensitive to

  7. Response of the Nile and its catchment to millennial-scale climatic change since the LGM from Sr isotopes and major elements of East Mediterranean sediments

    Science.gov (United States)

    Box, M. R.; Krom, M. D.; Cliff, R. A.; Bar-Matthews, M.; Almogi-Labin, A.; Ayalon, A.; Paterne, M.

    2011-02-01

    Changes in 87Sr/ 86Sr and major element geochemistry, from two sediment cores (9509 and 9501) in the Eastern Mediterranean (EM), were used to resolve changes in sediment provenance and, hence, determine climate changes in the Nile catchment and Eastern Sahara desert over the past 25 ka. The sediment was described by a three end-member system comprising Blue Nile (BN; 87Sr/ 86Sr = 0.7506; Sr = 210 ppm), White Nile (WN; 87Sr/ 86Sr = 0.7094; Sr = 72.5 ppm) and Saharan dust (SD; 87Sr/ 86Sr = 0.7183; Sr = 99 ppm). The sedimentary record of these cores represents the suspended load carried down the Nile river and discharged into the S.E. Levantine basin and thus records palaeoclimatically controlled changes in erosion and transport in the catchment. During arid periods (0-5 ka BP) and prior to 11 ka BP, fluxes of BN sediment at 9509 (˜6 g/cm 2/yr & 10-12 g/cm 2/yr, respectively) were greater than during the peak of the African Humid Period (AHP) from 5 to 11 ka BP (15 g/cm 2/yr. In the Ethiopian Highlands (BN catchment) increases in the amount and duration of the monsoon during the AHP caused more vegetation to grow resulting in less soil erosion. In the WN catchment increased rainfall caused more catchment erosion and higher sediment flux through the Sudd marshes. The sedimentation rate in core 9509 increased during the AHP because of the greater importance of the WN sediment flux relative to the BN sediment flux. Saharan dust flux also decreased during the AHP reaching a minimum at ˜6 ka BP (core 9509) due to 'greening' of the Sahara desert. At the onset of S-1, the changes in Nile flow as determined by 87Sr/ 86Sr and climatic changes in the EM basin determined by δ 18O of planktonic foraminifera were simultaneous, confirming that such isotopic tracers cannot be used directly to determine the cause of the circulation changes in the EM at this time. The increase in the proportion of BN sediment at 9509 with a somewhat higher grain size during the H-1 period (15-17 ka

  8. The implications of geology, soils, and vegetation on landscape morphology: Inferences from semi-arid basins with complex vegetation patterns in Central New Mexico, USA

    Science.gov (United States)

    Yetemen, Omer; Istanbulluoglu, Erkan; Vivoni, Enrique R.

    2010-04-01

    This paper examines the relationship between land surface properties (e.g. soil, vegetation, and lithology) and landscape morphology quantified by the catchment descriptors: the slope-area (S-A) relation, curvature-area (C-A) relation, and the cumulative area distribution (CAD), in two semi-arid basins in central New Mexico. The first site is composed of several basins located in today's desert elevations with mesic north-facing and xeric south-facing hillslopes underlain by different lithological formations. The second site is a mountainous basin exhibiting vegetation gradients from shrublands in the lower elevations to grasslands and forests at higher elevations. All three land surface properties were found to have significant influences on the S-A and C- A relations, while the power-law exponents of the CADs for these properties did not show any significant deviations from the narrow range of universal scaling exponents reported in the literature. Among the three different surface properties we investigated, vegetation had the most profound impact on the catchment descriptors. In the S-A diagrams of the aspect-controlled ecosystems, we found steeper slopes in north-facing aspects than south-facing aspects for a given drainage area. In elevation-controlled ecosystems, forested landscapes exhibited the steepest slopes for the range of drainage areas examined, followed by shrublands and grasslands in all soil textures and lithologies. In the C-A diagrams, steeper slopes led to a higher degree of divergence on hillslopes and a higher degree of convergence in the valleys than shallower slopes. The influence of functional types of vegetation detected on observed topography provided some initial understanding of the potential impacts of life on the organization of topography. This finding also emphasizes the critical role of climate in catchment development. We suggest that climatic fluctuations that are capable of replacing vegetation communities could lead to highly

  9. Effects of land use/land cover and climate changes on surface runoff in a semi-humid and semi-arid transition zone in northwest China

    Science.gov (United States)

    Yin, Jing; He, Fan; Jiu Xiong, Yu; Qiu, Guo Yu

    2017-01-01

    Water resources, which are considerably affected by land use/land cover (LULC) and climate changes, are a key limiting factor in highly vulnerable ecosystems in arid and semi-arid regions. The impacts of LULC and climate changes on water resources must be assessed in these areas. However, conflicting results regarding the effects of LULC and climate changes on runoff have been reported in relatively large basins, such as the Jinghe River basin (JRB), which is a typical catchment (> 45 000 km2) located in a semi-humid and arid transition zone on the central Loess Plateau, northwest China. In this study, we focused on quantifying both the combined and isolated impacts of LULC and climate changes on surface runoff. We hypothesized that under climatic warming and drying conditions, LULC changes, which are primarily caused by intensive human activities such as the Grain for Green Program, will considerably alter runoff in the JRB. The Soil and Water Assessment Tool (SWAT) was adopted to perform simulations. The simulated results indicated that although runoff increased very little between the 1970s and the 2000s due to the combined effects of LULC and climate changes, LULC and climate changes affected surface runoff differently in each decade, e.g., runoff increased with increased precipitation between the 1970s and the 1980s (precipitation contributed to 88 % of the runoff increase). Thereafter, runoff decreased and was increasingly influenced by LULC changes, which contributed to 44 % of the runoff changes between the 1980s and 1990s and 71 % of the runoff changes between the 1990s and 2000s. Our findings revealed that large-scale LULC under the Grain for Green Program has had an important effect on the hydrological cycle since the late 1990s. Additionally, the conflicting findings regarding the effects of LULC and climate changes on runoff in relatively large basins are likely caused by uncertainties in hydrological simulations.

  10. Plant communities of the Soutpansberg Arid Northern Bushveld

    Directory of Open Access Journals (Sweden)

    Theo H.C. Mostert

    2009-01-01

    Full Text Available The Soutpansberg Arid Northern Bushveld is one of eight major vegetation types (MVT described for the Soutpansberg-Blouberg region. The plant communities of this MVT are described in detail. Main ecological drivers of the vegetation structure and species composition of these communities are discussed and some conservation recommendations are made. Phytosociological data from a subset of 72 Braun-Blanquet sample plots collected in the Soutpansberg Arid Northern Bushveld were classified using Two-way Indicator Species Analysis (TWINSPAN and ordinated using a Detrended Correspondence Analysis (DECORANA. The resulting classification was further refined with table-sorting procedures based on the Braun-Blanquet floristic-sociological approach to vegetation classification using the computer software MEGATAB and JUICE. Eight plant communities were identified and described as Commiphora tenuipetiolata-Adansonia digitata short open woodland, Ledebouria ovatifolia-Commiphora mollis short bushland, Phyllanthus reticulatus-Acacia nigrescens short bushland, Tinnea rhodesiana-Combretum apiculatum short bushland, Dichrostachys cinerea subsp. africana-Spirostachys africana low thickets, Themeda triandra-Pterocarpus rotundifolius short closed grassland on steep basaltic slopes, Cyperus albostriatus-Syzygium cordatum sandveld wetlands, and Sesamothamnus lugardii-Catophractes alexandri tall sparse shrubland. These plant communities are event-driven ecosystems, predominantly infl uenced by frequent droughts, exposure to desiccation and unpredictable rainfall events. The complex topography of the Soutpansberg further contributes to the aridity of these ecosystems. The classifi cation and ordination analyses show similar groupings in the vegetation of the Soutpansberg Arid Mountain Bushveld. This confi rms the usefulness of complimentary analysis, using both classifi cation and ordination methods on a single data set in order to examine patterns and to search for

  11. Causes of early Holocene desertification in arid central Asia

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Liya [Lanzhou University, Key Laboratory of Western China' s Environmental System, Lanzhou, Gansu (China); University of Kiel, Institute of Geosciences, Kiel (Germany); Chen, Fahu [Lanzhou University, Key Laboratory of Western China' s Environmental System, Lanzhou, Gansu (China); Morrill, Carrie [University of Colorado, Cooperative Institute for Research in Environmental Sciences, Boulder, CO (United States); NOAA' s National Climatic Data Center, Paleoclimatology Branch, Boulder, CO (United States); Otto-Bliesner, Bette L.; Rosenbloom, Nan [National Center for Atmospheric Research, Climate and Global Dynamics Division, Boulder, CO (United States)

    2012-04-15

    Paleoclimate records of effective moisture (precipitation minus evaporation, or P-E) show a dry (low effective moisture) period in mid-latitude arid/semi-arid central Asia during the early Holocene (11,000-8,000 years ago) relative to the middle and late Holocene, in contrast to evidence for greater-than-present precipitation at the same time in the south and east Asian monsoonal areas. To investigate the spatial differences in climate response over mid-latitude central Asia and monsoonal Asia we conducted a series of simulations with the Community Climate System Model version 3 coupled climate model for the early, middle and late Holocene. The simulations test the climatic impact of all important forcings for the early Holocene, including changes in orbital parameters, the presence of the remnant Laurentide ice sheet and deglacial freshening of the North Atlantic. Model results clearly show the early Holocene patterns indicated by proxy records, including both the decreased effective moisture in arid central Asia, which occurs in the model primarily during the winter months, and the increase in summer monsoon precipitation in south and east Asia. The model results suggest that dry conditions in the early Holocene in central Asia are closely related to decreased water vapor advection due to reduced westerly wind speed and less evaporation upstream from the Mediterranean, Black, and Caspian Seas in boreal winter. As an extra forcing to the early Holocene climate system, the Laurentide ice sheet and meltwater fluxes have a substantial cooling effect over high latitudes, especially just over and downstream of the ice sheets, but contribute only to a small degree to the early Holocene aridity in central Asia. Instead, most of the effective moisture signal can be explained by orbital forcing decreasing the early Holocene latitudinal temperature gradient and wintertime surface temperature. We find little evidence for regional subsidence related to a stronger summer Asian

  12. Arid land plants: promising new tools for economic development and basic research

    Energy Technology Data Exchange (ETDEWEB)

    Felker, P.

    1980-01-01

    An overview is presented of arid land plant development stressing products and plant physiological and ecological concepts unique to arid land plants. Integration of new arid land crops into polyculture management systems is suggested utilizing specialized plant functions, e.g., drought resistance, resistance to salinity, ability to fix nitrogen, frost tolerance and capability to produce a cash crop. Impacts on arid land plant productivity on political systems of developing countries are discussed and recommendations are presented for overcoming institutional constraints facing arid land plant development. (MHR)

  13. Impacts of climate change on nutrient cycling in semi-arid and arid ecosystems

    Energy Technology Data Exchange (ETDEWEB)

    Belnap, J. [National Biological Survey, Moab, UT (United States)

    1995-09-01

    Effective precipitation is a major factor in determining nutrient pathways in different ecosystems. Soil flora and fauna play a critical role in nutrient cycles of all ecosystems. Temperature, timing, and amounts of precipitation affect population composition, activity levels, biomass, and recovery rates from disturbance. Changes in these variables can result in very different inputs and outputs for different nutrients. As a result, areas with less effective precipitation have very different nutrient cycles than more mesic zones. Climate change, therefore, can profoundly affect the nutrient cycles of ecosystems. Nitrogen cycles may be especially sensitive to changes in temperature and to timing and amounts of precipitation. Rainfall contains varying amounts of nitrogen compounds. Changes in amounts of rainfall will change amounts of nitrogen available to these systems. Because rainfall is limited in semi-arid and regions, these systems tend to be more dependent on microbial populations for nitrogen input. Consequently, understanding the effects of climate change on these organisms is critical in understanding the overall effect on ecosystems.

  14. Agave: a biofuel feedstock for arid and semi-arid environments

    Energy Technology Data Exchange (ETDEWEB)

    Gross, Stephen; Martin, Jeffrey; Simpson, June; Wang, Zhong; Visel, Axel

    2011-05-31

    Efficient production of plant-based, lignocellulosic biofuels relies upon continued improvement of existing biofuel feedstock species, as well as the introduction of newfeedstocks capable of growing on marginal lands to avoid conflicts with existing food production and minimize use of water and nitrogen resources. To this end, specieswithin the plant genus Agave have recently been proposed as new biofuel feedstocks. Many Agave species are adapted to hot and arid environments generally unsuitable forfood production, yet have biomass productivity rates comparable to other second-generation biofuel feedstocks such as switchgrass and Miscanthus. Agavesachieve remarkable heat tolerance and water use efficiency in part through a Crassulacean Acid Metabolism (CAM) mode of photosynthesis, but the genes andregulatory pathways enabling CAM and thermotolerance in agaves remain poorly understood. We seek to accelerate the development of agave as a new biofuelfeedstock through genomic approaches using massively-parallel sequencing technologies. First, we plan to sequence the transcriptome of A. tequilana to provide adatabase of protein-coding genes to the agave research community. Second, we will compare transcriptome-wide gene expression of agaves under different environmentalconditions in order to understand genetic pathways controlling CAM, water use efficiency, and thermotolerance. Finally, we aim to compare the transcriptome of A.tequilana with that of other Agave species to gain further insight into molecular mechanisms underlying traits desirable for biofuel feedstocks. These genomicapproaches will provide sequence and gene expression information critical to the breeding and domestication of Agave species suitable for biofuel production.

  15. Multi-response calibration of a conceptual hydrological model in the semiarid catchment of Wadi al Arab, Jordan

    Science.gov (United States)

    Rödiger, T.; Geyer, S.; Mallast, U.; Merz, R.; Krause, P.; Fischer, C.; Siebert, C.

    2014-02-01

    A key factor for sustainable management of groundwater systems is the accurate estimation of groundwater recharge. Hydrological models are common tools for such estimations and widely used. As such models need to be calibrated against measured values, the absence of adequate data can be problematic. We present a nested multi-response calibration approach for a semi-distributed hydrological model in the semi-arid catchment of Wadi al Arab in Jordan, with sparsely available runoff data. The basic idea of the calibration approach is to use diverse observations in a nested strategy, in which sub-parts of the model are calibrated to various observation data types in a consecutive manner. First, the available different data sources have to be screened for information content of processes, e.g. if data sources contain information on mean values, spatial or temporal variability etc. for the entire catchment or only sub-catchments. In a second step, the information content has to be mapped to relevant model components, which represent these processes. Then the data source is used to calibrate the respective subset of model parameters, while the remaining model parameters remain unchanged. This mapping is repeated for other available data sources. In that study the gauged spring discharge (GSD) method, flash flood observations and data from the chloride mass balance (CMB) are used to derive plausible parameter ranges for the conceptual hydrological model J2000g. The water table fluctuation (WTF) method is used to validate the model. Results from modelling using a priori parameter values from literature as a benchmark are compared. The estimated recharge rates of the calibrated model deviate less than ±10% from the estimates derived from WTF method. Larger differences are visible in the years with high uncertainties in rainfall input data. The performance of the calibrated model during validation produces better results than applying the model with only a priori parameter

  16. Spatial pattern of nitrogen isotopes as an indicator of ecosystem responses to rainfall in semi-arid and arid grasslands

    Science.gov (United States)

    WANG, C.; Bai, E.; Liu, D.; Fang, T. Y.; Jiang, P.; Han, G. X.

    2013-12-01

    Nitrogen (N) is an essential element for plant growth, however, whether it is a limiting factor of plant growth in water-limited areas is still not clear. Here we examined spatial variations of plant and soil stable N isotopes along a 3200 km precipitation gradient and proposed a conceptual model to explain ecosystem responses to increasing precipitation in arid and semi-arid grasslands in China. Soil δ15N increased with increasing MAP in areas with MAP areas with 200 mm 200 mm. In areas with MAP nutrient cycling in arid and semi-arid areas. If future climate change leads to drier climate in dryland, the uncoupled plant and microbial response may cause more N losses and higher ecosystem vulnerability. 3 Soil organic carbon (Soil C, a), total nitrogen (Soil N, b), C/N (c) and δ15N (d) of study sites along a MAP gradient. Relationship between MAP and foliar δ15N (a) and root δ15N (b).

  17. Validation of humidex in evaluating heat stress in the outdoor jobs in arid and semi-arid climates of Iran

    Directory of Open Access Journals (Sweden)

    Hamid Reza Heidari

    2016-09-01

    Full Text Available Introduction: Regarding development of several thermal indices and limitations of each, in this research applicability and validity of temperature- humidity index (Humidex were examined against the standard heat index, Wet Bulb Globe Temperature -WBGT, as well as tympanic temperature of subjects. Material and Method:  This cross-sectional study was done on 163 subjects at spring and summer (2013 in outdoor jobs of arid and semi-arid climates of Iran. Environmental parameters as well as tympanic temperature of subjects were measured simultaneously and then heat indices were determined. Data were analyzed using linear correlation charts and Kappa coefficient of agreement by means of SPSS software version 20. Results: A strong correlation was obtained between WBGT and Humidex in both arid and semi-arid regions (r>0.98, while the correlation between Humidex and tympanic temperature was moderate (r=0.5-0.8. Based on the obtained Kappa value, the agreement coefficient between Humidex and WBGT was 0.878. This value was obtained equal to 0.226 for the Humidex and tympanic temperature. Conclusion: The results of this study showed that Humidex can be applied as an appropriate substitute for the WBGT index. However, if evaluation of environmental condition with low air temperature or very hot situation is considered, relying only on the Humidex results will not provide a realistic estimation of thermal strain imposed to individuals.

  18. Optimal catchment area and primary PCI centre volume revisited

    DEFF Research Database (Denmark)

    Schoos, Mikkel Malby; Pedersen, Frants; Holmvang, Lene;

    2015-01-01

    AIMS: The currently stated optimal catchment population for a pPCI centre is 300,000-1,100,000, resulting in 200-800 procedures/year. pPCI centres are increasing in number even within small geographic areas. We describe the organisation and quality of care after merging two high-volume centres...

  19. First Flush Effects in an Urban Catchment Area in Aalborg

    DEFF Research Database (Denmark)

    Larsen, Torben; Brpch, Kirsten; Andersen, Margit Riis

    1997-01-01

    The paper describes the results of measurements from a 2 year period on a 95 hectare urban catchment in Aalborg, Denmark. The results of the rain/discharge measurements include 160 storm events corresponding to an accumulated rain depth of totally 753 mm. The water quality measurements include 15...

  20. WWF Kikori Catchment Developmental Project, Papua New Guinea orchid survey

    NARCIS (Netherlands)

    Clements, M.A.; Harris, W.K.

    2002-01-01

    The World Wildlife Fund (Kikori Catchment Developmental Project, Papua New Guinea) has commenced field surveys of the Orchidaceae in the Lake Kutabu and Mt Bosavi areas of Papua New Guinea. The main purpose of the survey is to get a more accurate assessment of the orchids in the region. In a previou

  1. Modelling (flash) floods in a Dutch lowland catchment

    NARCIS (Netherlands)

    Brauer, C.C.; Teuling, A.J.; Overeem, A.; Velde, Y. van der; Hazenberg, P.; Warmerdam, P.M.M.; Kloosterman, P.; Uijlenhoet, R.

    2012-01-01

    On 26 August 2010 the eastern part of The Netherlands and the bordering part of Germany were struck by a series of rainfall events.We investigated the unprecedented flash flood triggered by this exceptionally heavy rainfall event (return period > 1000 years) in the 6.5 km2 Hupsel Brook catchment, wh

  2. Hydrological response of a small catchment burned by experimental fire

    NARCIS (Netherlands)

    Stoof, C.R.; Vervoort, R.W.; Iwema, J.; Elsen, van den H.G.M.; Ferreira, A.J.D.; Ritsema, C.J.

    2012-01-01

    Fire can considerably change hydrological processes, increasing the risk of extreme flooding and erosion events. Although hydrological processes are largely affected by scale, catchment-scale studies on the hydrological impact of fire in Europe are scarce, and nested approaches are rarely used. We p

  3. Examining the Potential Travellers in Catchment Areas for Public Transport

    DEFF Research Database (Denmark)

    Landex, Alex; Hansen, Stephen

    2006-01-01

    The paper presents a method to examine the catchment areas for stops in high quality public transport systems based on the actual street network in the examined area. This is achieved by implementing the service area functions from the ArcGIS extension Network Analyst. The method is compared...

  4. Discharge Water Quality Models of Storm Runoff in a Catchment

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The relationships between the water qualities of nitrogen and phosphorous contents in the discharge water and the discharge of storm runoff of an experimental catchment including terraced paddy field are analyzed based on experiment results of the catchment. By summarizing the currently related research on water quality models, the water quality models of different components of storm runoff of the catchment are presented and verified with the experiment data of water quality analyses and the corresponding discharge of the storm runoffs during 3 storms. Through estimating the specific discharge of storm runoff, the specific load of different components of nitrogen and phosphorus in the discharge water of the catchment can be forecasted by the models. It is found that the mathematical methods of linear regression are very useful for analysis of the relationship between the concentrations of nitrogen and phosphorus and the water discharge of storm runoff. It is also found that the most content of the nitrogen (75%) in the discharge water is organic, while half of the content (49%) of phosphorus in the discharge water is inorganic.

  5. The ethics of socio-ecohydrological catchment management: towards hydrosolidarity

    Science.gov (United States)

    Falkenmark, M.; Folke, Carl

    This paper attempts to clarify key biophysical issues and the problems involved in the ethics of socio-ecohydrological catchment management. The issue in managing complex systems is to live with unavoidable change while securing the capacity of the ecohydrological system of the catchment to sustain vital ecological goods and services, aquatic as well as terrestrial, on which humanity depends ultimately. Catchment management oriented to sustainability has to be based on ethical principles: human rights, international conventions, sustaining crucial ecological goods and services, and protecting ecosystem resilience, all of which have water linkages. Many weaknesses have to be identified, assessed and mitigated to improve the tools by which the ethical issues can be addressed and solved: a heritage of constraining tunnel vision in both science and management; inadequate shortcuts made in modern scientific system analyses (e.g. science addressing sustainability issues); simplistic technical-fix approaches to water and ecosystems in land/water/ecosystem management; conventional tools for evaluation of scientific quality with its focus on "doing the thing right" rather than "doing the right thing". The new ethics have to incorporate principles that, on a catchment basis, allow for proper attention to the hungry and poor, upstream and downstream, to descendants, and to sites and habitats that need to be protected.

  6. Longterm Measurements of Bedload-Transport in alpine Catchments

    Science.gov (United States)

    Achleitner, Stefan; Kammerlander, Johannes; Eichner, Bernhard; Schöber, Johannes; Chiari, Michael

    2016-04-01

    In recent years the necessity of predicting the long-term behavior of sediment transport has increased. On the one hand, the effects of technical measures (e.g. retaining measures, hydropower, etc.) in the natural system are to be evaluated. On the other hand long term ecological studies that are strongly linked to the sediment budgets and its variation are more and more evolving. The ACRP Project DevoBeta-CC addresses the dynamics of long term sediment transport dynamics and its temporal altering. The focus is put on smaller tributary catchments enabling the model development. In total the data from ten catchments connected to the hydropower station Kaunertal (Tyrol/Austria) and eleven catchments linked to the power plant group Sellrain-Silz (Tyrol/Austria) are available. The considered catchments vary regarding their characteristics such as size (3 km³ to 27 km²), glaciation (0 % to 53 %), mean catchment slope (53 % to 92 %) and mean channel gradient (4 % to 49 %). The main data basis are records from the water intake structures operated (partly since 1965) by the TIWAG (Tiroler Wasserkraft AG). The sedimentation dynamics and operational flushings of the connected settling basins are used to measure the transported sediments. Since 1985 even high resolution data (15min intervals) are available. At selected catchments, the operationally recorded data (flushings, load membrane measurements,...) are verified within measuring campaigns using bed load traps upstream. Further, the sedimentation dynamics and grain size distributions in the settling basins are evaluated. Therefor two water intakes were put temporally out of operation, allowing an improved measurement of settled volumes by means of terrestrial surveying. Uncertainty assessments reveal an overall accuracy of estimated annual bed load volumes lower than a factor of two. Additionally, the data set enables to address sediment transport at a sub-annual basis, hence, the presented data set is unique regarding

  7. Seasonal exports of phosphorus from intensively fertilised nested grassland catchments

    Institute of Scientific and Technical Information of China (English)

    Ciaran Lewis; Rashad Rafique; Nelius Foley; Paul Leahy; Gerard Morgan; John Albertson; Sandeep Kumar

    2013-01-01

    We carried out a one year (2002) study of phosphorus (P) loss from soil to water in three nested grassland catchments with known P input in chemical fertilizer and animal liquid slurry applications.Chemical fertilizer was applied to the grasslands between March and September and animal slurry was applied over the twelve months.The annual chemical P fertilizer applications for the 17 and 211 ha catchments were 16.4 and 23.7 kg P/ha respectively and the annual slurry applications were 10.7 and 14.0 kg P/ha,respectively.The annual total phosphorus (TP) export in stream-flow was 2.61,2.48 and 1.61 kg P/ha for the 17,211 and 1524 ha catchments,respectively,compared with a maximum permissible (by regulation) annual export of ca.0.35 kg P/ha.The export rate (ratio of P export to P in land applications) was 9.6% and 6.6% from the 17 and 211 ha catchments,respectively.On average,70% of stream flow and 85% of the P export occurred during the five wet months (October to February) indicating that when precipitation is much greater than evaporation,the hydrological conditions are most favourable for P export.However the soil quality and land use history may vary the results.Particulate P made up 22%,43% and 37% of the TP export at the 17,211 and 1524 ha catchment areas,respectively.As the chemical fertilizer was spread during the grass growth months (March to September),it has less immediate impact on stream water quality than the slurry applications.We also show that as the catchment scale increases,the P concentrations and P export decrease,confirming dilution due to increasing rural catchment size.In the longer term,the excess P from fertilizer maintains high soil P levels,an antecedent condition favourable to P loss from soil to water.This study confirms the significant negative water quality impact of excess P applications,particularly liquid animal slurry applications in wet winter months.The findings suggest that restricted P application in wet months can

  8. Sediment yield and connectivity in a gullied sandy catchment

    Science.gov (United States)

    Lucía, Ana; Francisco Martín-Duque, José; Laronne, Jonathan B.; Ángel Sanz-Santos, Miguel

    2014-05-01

    Badland areas are considered to have high connectivity of sediment at the catchment scale; however, little is known about processes occurring in gullies and badlands developed in sands. This type of gullies is quite common in the Central-Eastern Iberian Peninsula and is associated with historic mining. The sandy badlands also appear in both abandoned and traditionally reclaimed mines, generating on- and offsite environmental effects. Our aim is to quantify the rates of the different processes occurring in the sandy gullied catchments, as well as their coupling and connectivity at a catchment scale. This may allow application to improve reclamation practice in mines and quarries located in sandy materials. The study site is a small (1.32 ha) gullied catchment, the Barranca de los Pinos, which is located in the Northern Piedmont of the Guadarrama Mountains (Central Spain). The catchment area has been divided into Homogeneous Response Units (HRUs) attending to the dominant active process . The sediment produced in the different HRUs has been monitored by a variety of methods: repeat Terrestrial Laser Scanning of high gradient slopes, closed microplots in low gradient slopes and automatic (Reid type) slot bedload samplers and siphon samplers to monitor suspended sediment transport in the channel. During the 2010-11 monitoring period the sediment yield due to gravitational movements in high gradient slopes varied from 20 to 200 kg m-2y-1. In the low gradient slopes the splash and non-concentrated runoff generated 0.1 - 6 kg m-2y-1,while the channel yielded 7.44 ± 1.08 kg m-2y-1 with a very high proportion (>70%) of bedload. Despite the difficulties of extrapolating and comparing the results obtained at different spatial and temporal resolutions, annual patterns of erosion and transport of sediments within the sandy gullied catchments have been identified. These confirm that the transport of sediment in this catchment is limited by the capacity of flow events to

  9. Tritium-based age/streamflow relationships and catchment function

    Science.gov (United States)

    Stewart, M. K.; Morgenstern, U.

    2013-12-01

    Understanding runoff generation is important for management of freshwater systems. Determining transit time distributions (TTDs) of streamwaters and how they change with flow gives information on the flowpaths and water storages in catchments - fundamental for understanding the responses of streams to stressors such as pollution, land use change and climate change. This work uses tritium measurements on single samples to determine TTDs and how they change with flow. Such use of tritium is only practical so far in the Southern Hemisphere, because of its much-lower input of bomb-tritium in the 1960s. Another advantage of tritium is that it reveals the full spectrum of ages present in streams, whereas oxygen-18 or chloride variations only show younger ages (i.e. truncated TTDs). Case studies are presented for two New Zealand catchments, both with volcanic ash substrates. The first (Toenepi) is a dairy catchment near Hamilton, which shows well-constrained power law relationships between mean transit time (MTT) and flow, and between silica concentration and flow. Baseflow MTTs vary from 2.5 to 157 years. The second (Tutaeuaua) is a pastoral farming catchment near Taupo. Results for nested catchments along the stream also show power law relationships for both MTT and silica with flow. Baseflow MTTs vary from 1 to 11 years. Although the MTT data could be represented approximately by straight lines in log-log plots, hysteresis effects due to catchment wetness variations did disturb the relationships. Having TTDs from individual samples focusses attention on the nature of the water storages supplying the stream at the times of sampling. The flow record contains information on catchment function, which can enhance the value of the age data, provided such information can be satisfactorily interpreted. A new baseflow estimation method is used to determine the slow storage (aka groundwater) fraction in the stream. The age data is showing that slow storages have mean ages of

  10. Seasonal exports of phosphorus from intensively fertilised nested grassland catchments.

    Science.gov (United States)

    Lewis, Ciaran; Rafique, Rashad; Foley, Nelius; Leahy, Paul; Morgan, Gerard; Albertson, John; Kumar, Sandeep; Kiely, Gerard

    2013-09-01

    We carried out a one year (2002) study of phosphorus (P) loss from soil to water in three nested grassland catchments with known P input in chemical fertilizer and animal liquid slurry applications. Chemical fertilizer was applied to the grasslands between March and September and animal slurry was applied over the twelve months. The annual chemical P fertilizer applications for the 17 and 211 ha catchments were 16.4 and 23.7 kg P/ha respectively and the annual slurry applications were 10.7 and 14.0 kg P/ha, respectively. The annual total phosphorus (TP) export in stream-flow was 2.61, 2.48 and 1.61 kg P/ha for the 17, 211 and 1524 ha catchments, respectively, compared with a maximum permissible (by regulation) annual export of ca. 0.35 kg P/ha. The export rate (ratio of P export to P in land applications) was 9.6% and 6.6% from the 17 and 211 ha catchments, respectively. On average, 70% of stream flow and 85% of the P export occurred during the five wet months (October to February) indicating that when precipitation is much greater than evaporation, the hydrological conditions are most favourable for P export. However the soil quality and land use history may vary the results. Particulate P made up 22%, 43% and 37% of the TP export at the 17, 211 and 1524 ha catchment areas, respectively. As the chemical fertilizer was spread during the grass growth months (March to September), it has less immediate impact on stream water quality than the slurry applications. We also show that as the catchment scale increases, the P concentrations and P export decrease, confirming dilution due to increasing rural catchment size. In the longer term, the excess P from fertilizer maintains high soil P levels, an antecedent condition favourable to P loss from soil to water. This study confirms the significant negative water quality impact of excess P applications, particularly liquid animal slurry applications in wet winter months. The findings suggest that restricted P application in

  11. Crossing thresholds: Analysis of hazardous tipping points in alpine catchments

    Science.gov (United States)

    Lutzmann, Silke; Sass, Oliver

    2016-04-01

    Steep mountain channels or torrents in small alpine catchments are characterized by high geomorphic activity with sediment dynamics being inherently nonlinear and threshold-mediated. Localized, high intensity rainstorms can drive torrential systems past a tipping point resulting in a sudden onset of hazardous events like (flash-) flooding, heavy bedload transport or debris flows. Such responses exhibit an abrupt switch in the fluvial system's mode (e.g. transport / supply limited). Changes in functional connectivity may persist beyond the tipping point. Torrential hazards cause costly damage in the densely populated Alpine Region. Thus, there is a rising interest in potential effects of climate change on torrential sediment dynamics. Understanding critical conditions close to tipping points is important to reduce uncertainty in predicting sediment fluxes. In this study we aim at (i) establishing threshold precipitation characteristics for the Eastern Alps of Austria. Precipitation is hypothesized to be the main forcing factor of torrential events. (ii) How do thresholds vary in space and time? (iii) The effect of external triggers is strongly mediated by the internal disposition of catchments to respond. Which internal conditions are critical for susceptibility? (iv) Is there a change in magnitude or frequency in the recent past and what can be expected for the future? The 71 km2 catchment of the river Schöttlbach in the East Alpine Region of Styria (Austria) is monitored since a heavy precipitation event resulted in a catastrophic flood in July 2011. Sediment mobilization from slopes as well as within-channel storage and bedload transport are regularly measured using photogrammetric methods and sediment impact sensors. Thus, detailed knowledge exists on magnitude and spatial propagation of sediment waves through the catchment. The associated hydro-meteorological (pre-) conditions can be inferred from a dense station network. Changing bedload transport rates and

  12. Understanding catchment scale sediment sources using geochemical tracers

    Science.gov (United States)

    Ferreira, Carla S. S.; Walsh, Rory P. D.; Shakesby, Richard A.; Steenhuis, Tammo S.; Ferreira, António J. D.; Coelho, Celeste O. A.

    2013-04-01

    It is well-established that urbanization leads to increased erosion (at least locally) as well as enhanced overland flow and streamflow peaks. Less is known about how the spatial distribution of erosion sources and scale of increases in erosion vary with the nature of urbanization in different climatic and socio-economic settings. This is important in order to prevent or reduce adverse impacts of erosion on downstream sedimentation, channel siltation and shifting, and river pollution. This paper adopts a sediment fingerprinting approach to assess the impact of partial urbanization and associated land-use change on sediment sources within a peri-urban catchment (6 km2), Ribeira dos Covões on the outskirts of the city of Coimbra in central Portugal. Urban land-use has increased from just 6% in 1958 to 30% in 2009. The urban pattern includes some well-defined urban residential centres, but also areas of discontinuous urban sprawl, including educational, health and small industrial facilities, numerous new roads and an enterprise park is under construction on the upper part of the catchment. The catchment has a wet Mediterranean climate and the lithology comprises sandstone in the west and limestone in the east. Soil depth is generally >40cm. The average slope angle is 8° (maximum 47°). Altitude ranges from 30m to 205m. A sediment fingerprinting approach was adopted to help establish the relative importance of sediment inputs from different urban areas. During September 2012 current bed-sediment samples (0-3 cm depth) were collected from 11 channel sites along the main stream and in different tributaries. At sites where bed-sediment was deeper, additional samples were taken at 3cm intervals to a maximum depth of around 42cm. In addition, overbank sediment samples (0-3cm depth) were collected at 11 locations around the catchment. All samples were oven-dried (at 38°C) and different particle size fractions (0.125-2mm, 0.063-0.125mm and chemical elements analysed

  13. Phosphorus transformations along a large-scale climosequence in arid and semiarid grasslands of northern China

    Science.gov (United States)

    Feng, Jiao; Turner, Benjamin L.; Lü, Xiaotao; Chen, Zhenhua; Wei, Kai; Tian, Jihui; Wang, Chao; Luo, Wentao; Chen, Lijun

    2016-09-01

    The Walker and Syers model of phosphorus (P) transformations during long-term soil development has been verified along many chronosequences but has rarely been examined along climosequences, particularly in arid regions. We hypothesized that decreasing aridity would have similar effects on soil P transformations as time by increasing the rate of pedogenesis. To assess this, we examined P fractions in arid and semiarid grassland soils (0-10 cm) along a 3700 km aridity gradient in northern China (aridity between 0.43 and 0.97, calculated as 1 - [mean annual precipitation/potential evapotranspiration]). Primary mineral P declined as aridity decreased, although it still accounted for about 30% of the total P in the wettest sites. In contrast, the proportions of organic and occluded P increased as aridity decreased. These changes in soil P composition occurred in parallel with marked shifts in soil nutrient stoichiometry, with organic carbon:organic P and nitrogen:organic P ratios increasing with decreasing aridity. These results indicate increasing abundance of P relative to carbon or nitrogen along the climosequence. Overall, our results indicate a broad shift from abiotic to biotic control on P cycling at an aridity value of approximately 0.7 (corresponding to about 250 mm mean annual rainfall). We conclude that the Walker and Syers model can be extended to climosequences in arid and semiarid ecosystems and that the apparent decoupling of nutrient cycles in arid soils is a consequence of their pedogenic immaturity.

  14. Genomic and proteomic characterization of ARID1A chromatin remodeller in ampullary tumors

    Science.gov (United States)

    Nastase, Anca; Teo, Jin Yao; Heng, Hong Lee; Ng, Cedric Chuan Young; Myint, Swe Swe; Rajasegaran, Vikneswari; Loh, Jia Liang; Lee, Ser Yee; Ooi, London Lucien; Chung, Alexander Yaw Fui; Chow, Pierce Kah Hoe; Cheow, Peng Chung; Wan, Wei Keat; Azhar, Rafy; Khoo, Avery; Xiu, Sam Xin; Alkaff, Syed Muhammad Fahmy; Cutcutache, Ioana; Lim, Jing Quan; Ong, Choon Kiat; Herlea, Vlad; Dima, Simona; Duda, Dan G; Teh, Bin Tean; Popescu, Irinel; Lim, Tony Kiat Hon

    2017-01-01

    AT rich interactive domain 1A (ARID1A) is one of the most commonly mutated genes in a broad variety of tumors. The mechanisms that involve ARID1A in ampullary cancer progression remains elusive. Here, we evaluated the frequency of ARID1A and KRAS mutations in ampullary adenomas and adenocarcinomas and in duodenal adenocarcinomas from two cohorts of patients from Singapore and Romania, correlated with clinical and pathological tumor features, and assessed the functional role of ARID1A. In the ampullary adenocarcinomas, the frequency of KRAS and ARID1A mutations was 34.7% and 8.2% respectively, with a loss or reduction of ARID1A protein in 17.2% of the cases. ARID1A mutational status was significantly correlated with ARID1A protein expression level (P=0.023). There was a significant difference in frequency of ARID1A mutation between Romania and Singapore (2.7% versus 25%, P=0.04), suggestive of different etiologies. One somatic mutation was detected in the ampullary adenoma group. In vitro studies indicated the tumor suppressive role of ARID1A. Our results warrant further investigation of this chromatin remodeller as a potential early biomarker of the disease, as well as identification of therapeutic targets in ARID1A mutated ampullary cancers.

  15. Research Note:Determination of soil hydraulic properties using pedotransfer functions in a semi-arid basin, Turkey

    Directory of Open Access Journals (Sweden)

    M. Tombul

    2004-01-01

    Full Text Available Spatial and temporal variations in soil hydraulic properties such as soil moisture q(h and hydraulic conductivity K(q or K(h, may affect the performance of hydrological models. Moreover, the cost of determining soil hydraulic properties by field or laboratory methods makes alternative indirect methods desirable. In this paper, various pedotransfer functions (PTFs are used to estimate soil hydraulic properties for a small semi-arid basin (Kurukavak in the north-west of Turkey. The field measurements were a good fit with the retention curve derived using Rosetta SSC-BD for a loamy soil. To predict parameters to describe soil hydraulic characteristics, continuous PTFs such as Rosetta SSC-BD (Model H3 and SSC-BD-q33q1500 (Model H5 have been applied. Using soil hydraulic properties that vary in time and space, the characteristic curves for three soil types, loam, sandy clay loam and sandy loam have been developed. Spatial and temporal variations in soil moisture have been demonstrated on a plot and catchment scale for loamy soil. It is concluded that accurate site-specific measurements of the soil hydraulic characteristics are the only and probably the most promising method to progress in the future. Keywords: soil hydraulic properties, soil characteristic curves, PTFs

  16. Impact of Direct Soil Moisture and Revised Soil Moisture Index Methods on Hydrologic Predictions in an Arid Climate

    Directory of Open Access Journals (Sweden)

    Milad Jajarmizadeh

    2014-01-01

    Full Text Available The soil and water assessment tool (SWAT is a physically based model that is used extensively to simulate hydrologic processes in a wide range of climates around the world. SWAT uses spatial hydrometeorological data to simulate runoff through the computation of a retention curve number. The objective of the present study was to compare the performance of two approaches used for the calculation of curve numbers in SWAT, that is, the Revised Soil Moisture Index (SMI, which is based on previous meteorological conditions, and the Soil Moisture Condition II (SMCII, which is based on soil features for the prediction of flow. The results showed that the sensitive parameters for the SMI method are land-use and land-cover features. However, for the SMCII method, the soil and the channel are the sensitive parameters. The performances of the SMI and SMCII methods were analyzed using various indices. We concluded that the fair performance of the SMI method in an arid region may be due to the inherent characteristics of the method since it relies mostly on previous meteorological conditions and does not account for the soil features of the catchment.

  17. Modeling the Surface Water-Groundwater Interaction in Arid and Semi-Arid Regions Impacted by Agricultural Activities

    Science.gov (United States)

    Tian, Y.; Wu, B.; Zheng, Y.

    2013-12-01

    In many semi-arid and arid regions, interaction between surface water and groundwater plays an important role in the eco-hydrological system. The interaction is often complicated by agricultural activities such as surface water diversion, groundwater pumping, and irrigation. In existing surface water-groundwater integrated models, simulation of the interaction is often simplified, which could introduce significant simulation uncertainty under certain circumstance. In this study, GSFLOW, a USGS model coupling PRMS and MODFLOW, was improved to better characterize the surface water-groundwater interaction. The practices of water diversion from rivers, groundwater pumping and irrigation are explicitly simulated. In addition, the original kinematic wave routing method was replaced by a dynamic wave routing method. The improved model was then applied in Zhangye Basin (the midstream part of Heihe River Baisn), China, where the famous 'Silk Road' came through. It is a typical semi-arid region of the western China, with extensive agriculture in its oasis. The model was established and calibrated using the data in 2000-2008. A series of numerical experiments were conducted to evaluate the effect of those improvements. It has been demonstrated that with the improvements, the observed streamflow and groundwater level were better reproduced by the model. The improvements have a significant impact on the simulation of multiple fluxes associated with the interaction, such as groundwater discharge, riverbed seepage, infiltration, etc. Human activities were proved to be key elements of the water cycle in the study area. The study results have important implications to the water resources modeling and management in semi-arid and arid basins.

  18. Optimization of precipitation inputs for SWAT modeling in mountainous catchment

    Science.gov (United States)

    Tuo, Ye; Chiogna, Gabriele; Disse, Markus

    2016-04-01

    Precipitation is often the most important input data in hydrological models when simulating streamflow in mountainous catchment. The Soil and Water Assessment Tool (SWAT), a widely used hydrological model, only makes use of data from one precipitation gauging station which is nearest to the centroid of each subcatchment, eventually corrected using the band elevation method. This leads in general to inaccurate subcatchment precipitation representation, which results in unreliable simulation results in mountainous catchment. To investigate the impact of the precipitation inputs and consider the high spatial and temporal variability of precipitation, we first interpolated 21 years (1990-2010) of daily measured data using the Inverse Distance Weighting (IDW) method. Averaged IDW daily values have been calculated at the subcatchment scale to be further supplied as optimized precipitation inputs for SWAT. Both datasets (Measured data and IDW data) are applied to three Alpine subcatchments of the Adige catchment (North-eastern Italy, 12100 km2) as precipitation inputs. Based on the calibration and validation results, model performances are evaluated according to the Nash Sutchliffe Efficiency (NSE) and Coefficient of Determination (R2). For all three subcatchments, the simulation results with IDW inputs are better than the original method which uses measured inputs from the nearest station. This suggests that IDW method could improve the model performance in Alpine catchments to some extent. By taking into account and weighting the distance between precipitation records, IDW supplies more accurate precipitation inputs for each individual Alpine subcatchment, which would as a whole lead to an improved description of the hydrological behavior of the entire Adige catchment.

  19. Advancing catchment hydrology to deal with predictions under change

    Directory of Open Access Journals (Sweden)

    U. Ehret

    2013-07-01

    Full Text Available Throughout its historical development, hydrology as an engineering discipline and earth science has relied strongly on the assumption of long-term stationary boundary conditions and system configurations, which allowed for simplified and sectoral descriptions of the dynamics of hydrological systems. However, in the face of rapid and extensive global changes (of climate, land use etc. which affect all parts of the hydrological cycle, the general validity of this assumption appears doubtful. Likewise, so does the application of hydrological concepts based on stationarity to questions of hydrological change. The reason is that transient system behaviours often develop through feedbacks between the system constituents, and with the environment, generating effects that could often be neglected under stationary conditions. In this context, the aim of this paper is to present and discuss paradigms and theories potentially helpful to advancing hydrology towards the goal of understanding and predicting hydrological systems under change. For the sake of brevity we focus on catchment hydrology. We begin with a discussion of the general nature of explanation in hydrology and briefly review the history of catchment hydrology. We then propose and discuss several perspectives on catchments: as complex dynamical systems, self-organizing systems, co-evolving systems and open dissipative thermodynamic systems. We discuss the benefits of comparative hydrology and of taking an information-theoretic view of catchments, including the flow of information from data to models to predictions. In summary, we suggest that the combination of these closely related perspectives can serve as a paradigm for the further development of catchment hydrology to address predictions under change.

  20. Runoff Responses to Forest Thinning at Plot and Catchment Scales in a Headwater Catchment Draining Japanese Cypress Forest

    Science.gov (United States)

    We examined the effect of forest thinning on runoff generation at plot and catchment scales in headwater basins draining a Japanese cypress (Chamaecyparis obtusa) forest. We removed 58.3% of the stems (corresponding to 43.2% of the basal area) in the treated headwater basin (catc...

  1. Water balance and its intra-annual variability in a permafrost catchment: hydrological interactions between catchment, lake and talik

    Directory of Open Access Journals (Sweden)

    E. Bosson

    2013-07-01

    Full Text Available Few hydrological studies have been made in Greenland with focus on permafrost hydrology rather than on the glacial hydrology associated with the Greenland ice sheet. Understanding permafrost hydrology, and its reflection and propagation of hydroclimatic change and variability, however, can be a key to understand important climate change effects and feedbacks in arctic landscapes. This paper presents a new extensive and detailed hydrological dataset, with high temporal resolution of main hydrological parameters, for a permafrost catchment with a lake underlain by a talik close to the Greenland ice sheet in the Kangerlussuaq region, western Greenland. The paper describes the hydrological site investigations and data collection, and their synthesis and interpretation to develop a conceptual hydrological model. The catchment and lake water balances and their intra-annual variability, and uncertainty intervals for key water balance components, are quantified. The study incorporates all relevant hydrological processes within the catchment and, specifically, links the surface water system to both supra-permafrost and sub-permafrost groundwater. The dataset enabled water balance quantification with high degree of confidence. The measured hydraulic gradient between the lake and the groundwater in the talik shows this to be a groundwater recharging talik. Surface processes, dominated by evapotranspiration during the active flow period, and by snow dynamics during the frozen winter period, influence the temporal variation of groundwater pressure in the talik. This shows the hydrology in the catchment as being rather independent from external large-scale landscape features, including those of the close-by ice sheet.

  2. How should a rainfall-runoff model be parameterized in an almost ungauged catchment? A methodology tested on 609 catchments

    Science.gov (United States)

    Rojas-Serna, Claudia; Lebecherel, Laure; Perrin, Charles; Andréassian, Vazken; Oudin, Ludovic

    2016-06-01

    This paper examines catchments that are almost ungauged, i.e., catchments for which only a small number of point flow measurements are available. In these catchments, hydrologists may still need to simulate continuous streamflow time series using a rainfall-runoff model, and the methodology presented here allows using few point measurements for model parameterization. The method combines regional information (parameter sets of neighboring gauged stations) and local information (contributed by the point measurements) within a framework where the relative weight of each source of information is made dependent on the number of point measurements available. This approach is tested with two different hydrological models on a set of 609 catchments in France. The results show that on average a few flow measurements can significantly improve the simulation efficiency, and that 10 measurements can reduce the performance gap between the gauged and ungauged situations by more than 50%. The added value of regional information progressively decreases until being almost insignificant when sufficient flow measurements are available. Model parameters tend to come closer to the values obtained by calibration in fully gauged conditions as the number of point flow measurements increases.

  3. Climate Warming Threatens Semi-arid Forests in Inner Asia

    Science.gov (United States)

    WU, X.; Liu, H.; Qi, Z.; Li, X.

    2014-12-01

    A line of evidences reveal an increasing tree growth decline and tree mortality mainly attributable to climate warming and the warming-mediated changes in drought and other processes (such as fire and insect dynamics) in many parts of world tropical, temperate and boreal forests. However, the growth responses to climate change of the widely distributed semi-arid forests are unclear. Here, we synthetically investigate the tree growth patterns during past decades and its interannual response to climate variations in Inner Asia combining the ground truth field survey and samplings, remote sensing observations and climate data. We identified a pervasive tree growth decline since mid-1990s in semi-arid forests in Inner Asia. The widely observed tree growth decline is dominantly attributable to warming-induced water stress during pre- and early growing season. Tree growth of semi-arid forests in Inner Asia is particularly susceptible to spring warming and has been suffering a prolonged growth limitation in recent decades due to spring warming-mediated water conditions. Additionally, we identified a much slower growth rate in younger trees and a lack of tree regeneration in these semi-arid forests. The widely observed forest growth reduction and lack of tree regeneration over semi-arid forests in Inner Asia could predictably exert great effects on forest structure, regionally/globally biophysical and biochemical processes and the feedbacks between biosphere and atmosphere. Notably, further increases in forest stress and tree mortality could be reasonably expected, especially in context of the increase frequency and severity of high temperature and heat waves and changes in forest disturbances, potentially driving the eventual regional loss of current semi-arid forests. Given the potential risks of climate induced forest dieback, increased management attention to adaptation options for enhancing forest resistance and resilience to projected climate stress can be expected

  4. Climate warming threatens semi-arid forests in Inner Asia

    Science.gov (United States)

    WU, X.

    2015-12-01

    A line of evidences reveal an increasing tree growth decline and tree mortality mainly attributable to climate warming and the warming-mediated changes in drought and other processes in many parts of world tropical, temperate and boreal forests. However, the growth responses to climate change of the widely distributed semi-arid forests are unclear. Here, we synthetically investigate the tree growth patterns during past decades and its interannual response to climate variations in Inner Asia combining the ground truth field survey and samplings, remote sensing observations and climate data. We identified a pervasive tree growth decline since mid-1990s in semi-arid forests in Inner Asia. The widely observed tree growth decline is dominantly attributable to warming-induced water stress during pre- and early growing season. Tree growth of semi-arid forests in Inner Asia is particularly susceptible to spring warming and has been suffering a prolonged growth limitation in recent decades due to spring warming-mediated water conditions. Additionally, we identified a much slower growth rate in younger trees and a lack of tree regeneration in these semi-arid forests. The widely observed forest growth reduction and lack of tree regeneration over semi-arid forests in Inner Asia could predictably exert great effects on forest structure, regionally/globally biophysical and biochemical processes and the feedbacks between biosphere and atmosphere. Notably, further increases in forest stress and tree mortality could be reasonably expected, especially in context of the increase frequency and severity of high temperature and heat waves and changes in forest disturbances, potentially driving the eventual regional loss of current semi-arid forests. Given the potential risks of climate induced forest dieback, increased management attention to adaptation options for enhancing forest resistance and resilience to projected climate stress can be expected. However, the functionally realistic

  5. Chemical weathering in response to tectonic uplift and denudation rate in a semi-arid environment, southeast Spain

    Science.gov (United States)

    Ameijeiras-Mariño, Yolanda; Opfergelt, Sophie; Schoonejans, Jérôme; Vanacker, Veerle; Sonnet, Philippe; Delmelle, Pierre

    2014-05-01

    Soil thickness reflects the balance between soil production and denudation by chemical weathering and physical erosion. At topographic steady state, the soil weathering intensity is expected to be higher at low denudation rate (transport-limited) than at high denudation rate (weathering-limited). We tested this hypothesis for the first time in a semi-arid environment where chemical weathering processes are generally slow. The study site is the Internal Zone of the Betic Cordillera in Southeast Spain, Almeria province. The lithology is mainly mica-schist and quartzite with local presence of phyllite. Three catchments (EST, FIL, CAB) were selected upstream local faults along a gradient of increasing uplift rates (10-170 mm/kyr) and increasing denudation rates (20-250 mm/kyr), following the sequence ESTReserve in Bases (TRB = [Ca2+] + [Na+] + [K+] + [Mg2+]); the soil Fed/Fet ratio that reflects the formation of secondary Fe-oxides, and the Cation Exchange Capacity (CEC) that varies with the amount of secondary clay minerals and organic matter. The difference in TRB between the soil and the bedrock (ΔTRB = TRB soil - TRB bedrock) should be more negative as weathering increases, whereas the Fed/Fet ratio is expected to augment with the intensity of weathering. Since these soils have low organic carbon content, the CEC should increase with weathering degree. Our results indicate that the ΔTRB (cmolc.kg-1) is -8±14 (n=8), -79±2 (n=8) and -51±38 (n=9) for CAB, FIL and EST, respectively. The Fed/Fet ratio for CAB, FIL and EST is 0.20±0.05 (n=8), 0.20±0.03 (n=8) and 0.29±0.05 (n=9), respectively. The CEC (cmolc.kg-1) increases from 3.3±1.7 (n=8) to 8.2±1.3 (n=8) and 10.4±3.0 (n=9) from CAB to FIL and EST. Based on the CEC, and to a lesser extent the ΔTRB values, the soils from the CAB catchment appear less weathered than those from the two other catchments. However, using the Fed/Fet ratio, both CAB and FIL soils seem less weathered than EST. Overall, the

  6. Characterizing Runoff and Water Yield from Headwater Catchments in the Southern Sierra Nevada

    Science.gov (United States)

    Safeeq, M.; Hunsaker, C. T.

    2015-12-01

    In a mediterranean climate where much of the annual precipitation falls during winter, the snow-capped Sierra Nevada serves as the primary source of dry season runoff that supports agriculture, industries, urban, and other ecosystems. Increased warming has led to significant reductions in mountain snowpack accumulation and earlier snowmelt throughout the western United States where most of the snow accumulates at temperatures near the freezing point. As a result, declines in dry season runoff magnitude, earlier runoff timing, and altered flood risk have been reported across the region. An important question in this context is, how to best manage forested catchments for water and other ecosystem services? We depict the differences in hydrologic response of ten catchments in the Kings River Experimental Watersheds (KREW) research project using continuous precipitation, snow, and runoff data during 2004-2014. The size of these catchments ranges from 50 to 475 ha, and they span a 600-m elevation range in the rain snow transitional zone. In terms of soil, Shaver and Gerle-Cagwin dominate the lower elevation Providence catchments, and Cagwin soils dominate the higher elevation Bull catchments. The majority of these catchments have southwest aspect, moderate average slope (i.e. annual runoff ranges between 281 to 408 mm in Providence and 436 to 656 mm in Bull catchments despite no significant difference in precipitation among KREW's four meteorological stations. However, high elevation Bull catchments receive significantly more precipitation as snow than the low elevation Providence catchments. The average runoff ratio ranges from 18% to as high as 43% among different catchments, indicating that the catchment evapotranspiration exceeds the catchment runoff. Inter-catchment variability in runoff, runoff ratio, characteristics of runoff ratio-precipitation relationship (i.e. slope and intercept), and precipitation elasticity of runoff can be primarily explained by

  7. Development and use of bioenergy feedstocks for semi-arid and arid lands.

    Science.gov (United States)

    Cushman, John C; Davis, Sarah C; Yang, Xiaohan; Borland, Anne M

    2015-07-01

    Global climate change is predicted to increase heat, drought, and soil-drying conditions, and thereby increase crop sensitivity to water vapour pressure deficit, resulting in productivity losses. Increasing competition between agricultural freshwater use and municipal or industrial uses suggest that crops with greater heat and drought durability and greater water-use efficiency will be crucial for sustainable biomass production systems in the future. Agave (Agavaceae) and Opuntia (Cactaceae) represent highly water-use efficient bioenergy crops that could diversify bioenergy feedstock supply yet preserve or expand feedstock production into semi-arid, abandoned, or degraded agricultural lands, and reclaim drylands. Agave and Opuntia are crassulacean acid metabolism species that can achieve high water-use efficiencies and grow in water-limited areas with insufficient precipitation to support traditional C3 or C4 bioenergy crops. Both Agave and Opuntia have the potential to produce above-ground biomass rivalling that of C3 and C4 crops under optimal growing conditions. The low lignin and high amorphous cellulose contents of Agave and Opuntia lignocellulosic biomass will be less recalcitrant to deconstruction than traditional feedstocks, as confirmed by pretreatments that improve saccharification of Agave. Refined environmental productivity indices and geographical information systems modelling have provided estimates of Agave and Opuntia biomass productivity and terrestrial sequestration of atmospheric CO2; however, the accuracy of such modelling efforts can be improved through the expansion of field trials in diverse geographical settings. Lastly, life cycle analysis indicates that Agave would have productivity, life cycle energy, and greenhouse gas balances comparable or superior to those of traditional bioenergy feedstocks, but would be far more water-use efficient.

  8. Sediment budget for Rediu reservoir catchment, North-Eastern Romania

    Science.gov (United States)

    Todosi, Cristian; Niculita, Mihai

    2016-04-01

    Sediment budgets are a useful tool for geomorphologic analysis, catchment management and environmental assessment, despite the uncertainties related to their assessment. We present the sediment budget construction and validation for a small catchment of 9.5319 kmp (953.19 ha) situated in the North-Eastern part of Romania. The Rediu reservoir was built between 1986 and 1988, on Rediu valley, a left tributary of Bahlui river, north-west from Iasi city. The catchment of the reservoir has 6.5 km in length and 2.5 km in maximum width, the altitudes decreasing from 170 m in the northern part, to 52 m in the southern part. The valley is symmetric, the altitude of the hillslopes going between 200 m to 75 m in one km length, in the transversal section with the maximum width. The floodplain is narrow having between 20 m to 210 m (in the area of confluence with Breazu tributary). The mean slope of the catchment is 6.4 degree, the maximum slope being 24.6 degrees. The length of channels which show banks of up to 2 m is 19.98 km. The land is used predominantly as crops (58.1 %), 16.7 % being covered by pastures (from which over half are eroded), 11.5 % percent of the catchment being covered by planted forests, 9.2 % by rural constructions and roads, 2.9 % by hayfields, 1.5 % by lakes and 0.1 % by orchards. Beside the Rediu reservoir, there are three ponds (15 771, 1761 and 751 sqm) in the catchment. We considered the trap efficiency for the reservoir and the ponds to be 95%. Aerial images from 1963, 1978 , 1984, 2005, 2008, 2010, 2012 and 2014 were used to assess the state of geomorphological processes before and after the reservoir construction. After 1970 a gully system situated in Breazu tributary sub-catchment and several active landslides along the main valley left side were forested. Beside these processes, soil erosion and human impact by constructions are the main processes generating sediment in the study area. The sediment yields were quantified by estimating the

  9. How Sustainable are Engineered Rivers in Arid Lands?

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    Jurgen Schmandt

    2013-06-01

    Full Text Available Engineered rivers in arid lands play an important role in feeding the world’s growing population. Each continent has rivers that carry water from distant mountain sources to fertile soil downstream where rainfall is scarce. Over the course of the last century most rivers in arid lands have been equipped with large engineering structures that generate electric power and store water for agriculture and cities. This has changed the hydrology of the rivers. In this paper we discuss how climate variation, climate change, reservoir siltation, changes in land use and population growth will challenge the sustainability of engineered river systems over the course of the next few decades. We use the Rio Grande in North America, where we have worked with Mexican and American colleagues, to describe our methodology and results. Similar work is needed to study future water supply and demand in engineered rivers around the world.

  10. On coordinated development of oasis and environment in arid area

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Based upon the formation and evolution of oasis and the factors restricting the coordinated development of oasis economy and environment, this paper presents a goal of the development in coordination. It suggests that the sustainable survival and development of oasis could be ensured only if the oasis-desert and water source ecology are managed in a combined way to form a macro system. In light with the above mentioned, the approach to the development of economy and environment of oasis in arid area should depend upon the establishment of an oasis ecological and economic system, which suits the arid environment and promotes the efficiency of resource configuration, stabilizes economic increment and benefits ecological development.

  11. Arid lands plants as feedstocks for fuels and chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Hoffmann, J.J.

    1983-01-01

    The purpose of this paper is to review the recent research on arid-adapted plants that have potential as producers of fuels or chemicals. The major focus will be on plant species that appear to have commercial value. Research on guayule (Parthenium argentatum) and jojoba (Simmondsia chinensis) will be mentioned only briefly, since these plants have been discussed extensively in the literature, and excellent reviews are already in existence. In this review the literature on arid-adapted plants that have potential uses for solid fuels, liquid fuels, and chemical feedstocks is summarized, followed by an overview of the research directions and types of development that are needed in order for bio-energy production systems to reach the commercial stage. 127 references.

  12. Pollen transport in the Shiyang River drainage, arid China

    Institute of Scientific and Technical Information of China (English)

    ZHU Yan; XIE Yaowen; CHENG Bo; CHEN Fahu; ZHANG Jiawu

    2003-01-01

    In order to assess the contribution of the pollen transported by wind and fluvial flows to the pollen spectra in Shiyang River drainage, a typical small endorheic drainage in arid lands of northwest China, preliminary studies on modern pollen rain along two transects with 91 surface soil samples, 8 atmospheric samples, 30 modern fluvial flow samples and 50 riverbed mud samples, were carried out. Results show that dispersal agents (air, flowing water) have dissimilareffects on transport of pollen and the structure of pollen spectra. Fluvial flow has a stronger capacity than wind to transport large quantities of pollen overlong distances. Pollen transported by fluvial flow makes a large contribution to the pollen spectra of riverbed alluvial sediments. Paleoenvironmental reconstructions undertaken using pollen spectra from fluvial sediments in arid lands arestrongly influenced by pollen transport. Therefore, the sources, the transportation agents and the depositional condition of pollen should be systematically investigated before pollen assemblages are used to derive the environmental significance in such settings.

  13. Domesticated proboscidea parviflora: a potential oilseed crop for arid lands

    Energy Technology Data Exchange (ETDEWEB)

    Berry, J.; Bretting, P.K.; Nabhan, G.P.; Weber, C.

    1981-01-01

    Wild and domesticated Proboscidea parviflora were evaluated as oilseed crops for arid lands through chemical and biological analyses. Domesticated plants grown in the Sonoran desert bore seed containing 35-40 per cent oil and 23-27 per cent protein. Yield per hectare was estimated at 1000 kg of oil and 675 kg of protein, quantities which compare favourably with other crops. An ephemeral life cycle and certain characteristics of the fruit and seed allow this plant to grow in xeric habitats unsuitable for many other plants. Several Proboscidea species hybridize with P. parviflora and could be used in future crop breeding. Rapid germination and higher oil and protein content of seed make the domesticated P. parviflora superior to the wild form as a crop. Domesticated P. parviflora thus shows promise as an oilseed crop for the Sonoran Desert and possibly for other arid regions. (Refs. 22).

  14. Soil weathering rates in 21 catchments of the Canadian Shield

    Directory of Open Access Journals (Sweden)

    D. Houle

    2012-03-01

    Full Text Available Soil mineral weathering represents an essential source of nutrient base cation (Ca, Mg and K for forest growth in addition to provide a buffering power against precipitation acidity for soils and surface waters. Weathering rates of base cations were obtained for 21 catchments located within the temperate and the boreal forest of the Canadian Shield with the geochemical model PROFILE. Weathering rates ranged from 0.58 to 4.46 kmolc ha−1 yr−1 and their spatial variation within the studied area was mostly in agreement with spatial variations in soil mineralogy. Weathering rates of Ca and Mg were significantly correlated (r = 0.80 and 0.64 with their respective lake concentrations. Weathering rates of K and Na did not correlate with lake concentrations of K and Na. The modeled weathering rates for each catchment were also compared with estimations of net catchment exportations. The result show that modeled weathering rates of Ca were not significantly different than the net catchment exportations while modeled weathering rates of Mg were higher by 51%. Larger differences were observed for K and Na weathering rates that were significantly different than net catchment exportations being 6.9 and 2.2 times higher than net exportations, respectively. The results for K were expected given its high reactivity with biotic compartments and suggest that most of the K produced by weathering reactions was retained within soil catchments and/or above ground biomass. This explanation does not apply to Na, however, which is a conservative element in forest ecosystems because of the insignificant needs of Na for soil microorganisms and above ground vegetations. It raises concern about the liability of the PROFILE model to provide reliable values of Na weathering rates. Overall, we concluded that the PROFILE model is powerful enough to reproduce spatial geographical gradients in weathering rates for relatively large areas

  15. Tracer Cycles and Water Ages in Heterogeneous Catchments and Aquifers

    Science.gov (United States)

    Kirchner, J. W.; Jasechko, S.

    2015-12-01

    Estimates of catchment mean transit times are often based on seasonal cycles of stable isotope tracers in precipitation and streamflow. In many cases these transit time estimates are derived directly from sine-wave fitting to the observed seasonal isotope cycles. Broadly similar results are also obtained from time-domain convolutions or explicit tracer modeling, because here too the dominant tracer signal that these techniques seek to match is the seasonal isotopic cycle. Here I use simple benchmark tests to show that estimates of mean transit times based on seasonal tracer cycles will typically be wrong by several hundred percent, when applied to catchments with realistic degrees of spatial heterogeneity. This aggregation bias arises from the strong nonlinearity in the relationship between tracer cycle amplitude and mean travel time. A similar bias arises in estimates of mean transit times in nonstationary catchments. Since typical real-world catchments are both spatially heterogeneous and nonstationary, this analysis poses a fundamental challenge to tracer-based estimates of mean transit times. I propose an alternative storage metric, the fraction of "young water" in streamflow, defined as the fraction of runoff with transit times of less than roughly 0.2 years. I show that young water fractions are virtually free of aggregation bias; that is, they can be accurately estimated from tracer cycles in highly heterogeneous mixtures of subcatchments with strongly contrasting transit time distributions. They can also be reliably estimated in strongly nonstationary catchments. Young water fractions can be estimated separately for individual flow regimes, allowing direct determination of how shifts in hydraulic regime alter the fraction of water reaching the stream by fast flowpaths. One can also estimate the chemical composition of idealized "young water" and "old water" end-members, using relationships between young water fractions and solute concentrations across

  16. Soil weathering rates in 21 catchments of the Canadian Shield

    Directory of Open Access Journals (Sweden)

    D. Houle

    2011-06-01

    Full Text Available Soil mineral weathering represents an essential source of nutrient base cation (Ca, Mg and K for forest growth in addition to provide a buffering power against precipitation acidity for soils and surface waters. Weathering rates of base cations were obtained for 21 catchments located within the temperate and the boreal forest of the Canadian Shield with the geochemical model PROFILE. Weathering rates ranged from 0.58 to 4.46 kmolc ha−1 yr−1 and their spatial variation within the studied area was mostly in agreement with spatial variations in soil mineralogy. Weathering rates of Ca and Mg were significantly correlated (r = 0.80 and 0.64 with their respective lake concentrations. Weathering rates of K and Na did not correlate with lake concentrations of K and Na. The modeled weathering rates for each catchment were also compared with estimations of net catchment exportations. The result show that modeled weathering rates of Ca were not significantly different than the net catchment exportations while modeled weathering rates of Mg were higher by 51 %. Larger differences were observed for K and Na weathering rates that were significantly different than net catchment exportations being 6.9 and 2.2 times higher than net exportations, respectively. The results for K were expected given its high reactivity with biotic compartments and suggest that most of the K produced by weathering reactions was retained within soil catchments and/or above ground biomass. This explanation does not apply to Na, however, which is a conservative element in forest ecosystems because of the insignificant needs of Na for soil microorganisms and above ground vegetations. It raises concern about the liability of the PROFILE model to provide reliable values of Na weathering rates. Overall, we concluded that the PROFILE model is powerful enough to reproduce spatial geographical gradients in weathering rates for relatively large areas

  17. Assessing water quality trends in catchments with contrasting hydrological regimes

    Science.gov (United States)

    Sherriff, Sophie C.; Shore, Mairead; Mellander, Per-Erik

    2016-04-01

    Environmental resources are under increasing pressure to simultaneously achieve social, economic and ecological aims. Increasing demand for food production, for example, has expanded and intensified agricultural systems globally. In turn, greater risks of diffuse pollutant delivery (suspended sediment (SS) and Phosphorus (P)) from land to water due to higher stocking densities, fertilisation rates and soil erodibility has been attributed to deterioration of chemical and ecological quality of aquatic ecosystems. Development of sustainable and resilient management strategies for agro-ecosystems must detect and consider the impact of land use disturbance on water quality over time. However, assessment of multiple monitoring sites over a region is challenged by hydro-climatic fluctuations and the propagation of events through catchments with contrasting hydrological regimes. Simple water quality metrics, for example, flow-weighted pollutant exports have potential to normalise the impact of catchment hydrology and better identify water quality fluctuations due to land use and short-term climate fluctuations. This paper assesses the utility of flow-weighted water quality metrics to evaluate periods and causes of critical pollutant transfer. Sub-hourly water quality (SS and P) and discharge data were collected from hydrometric monitoring stations at the outlets of five small (~10 km2) agricultural catchments in Ireland. Catchments possess contrasting land uses (predominantly grassland or arable) and soil drainage (poorly, moderately or well drained) characteristics. Flow-weighted water quality metrics were calculated and evaluated according to fluctuations in source pressure and rainfall. Flow-weighted water quality metrics successfully identified fluctuations in pollutant export which could be attributed to land use changes through the agricultural calendar, i.e., groundcover fluctuations. In particular, catchments with predominantly poor or moderate soil drainage

  18. Safeguarding the provision of ecosystem services in catchment systems.

    Science.gov (United States)

    Everard, Mark

    2013-04-01

    A narrow technocentric focus on a few favored ecosystem services (generally provisioning services) has led to ecosystem degradation globally, including catchment systems and their capacities to support human well-being. Increasing recognition of the multiple benefits provided by ecosystems is slowly being translated into policy and some areas of practice, although there remains a significant shortfall in the incorporation of a systemic perspective into operation management and decision-making tools. Nevertheless, a range of ecosystem-based solutions to issues as diverse as flooding and green space provision in the urban environment offers hope for improving habitat and optimization of beneficial services. The value of catchment ecosystem processes and their associated services is also being increasingly recognized and internalized by the water industry, improving water quality and quantity through catchment land management rather than at greater expense in the treatment costs of contaminated water abstracted lower in catchments. Parallel recognition of the value of working with natural processes, rather than "defending" built assets when catchment hydrology is adversely affected by unsympathetic upstream development, is being progressively incorporated into flood risk management policy. This focus on wider catchment processes also yields a range of cobenefits for fishery, wildlife, amenity, flood risk, and other interests, which may be optimized if multiple stakeholders and their diverse value systems are included in decision-making processes. Ecosystem services, particularly implemented as a central element of the ecosystem approach, provide an integrated framework for building in these different perspectives and values, many of them formerly excluded, into commercial and resource management decision-making processes, thereby making tractable the integrative aspirations of sustainable development. This can help redress deeply entrenched inherited assumptions

  19. Spatial vegetation patterns and imminent desertification in Mediterranean arid ecosystems

    OpenAIRE

    2007-01-01

    Humans and climate affect ecosystems and their services, which may involve continuous and discontinuous transitions from one stable state to another. Discontinuous transitions are abrupt, irreversible and among the most catastrophic changes of ecosystems identified1. For terrestrial ecosystems, it has been hypothesized that vegetation patchiness could be used as a signature of imminent transitions. Here, we analyse how vegetation patchiness changes in arid ecosystems with different grazing pr...

  20. Evolutionary shifts in habitat aridity predict evaporative water loss across squamate reptiles.

    Science.gov (United States)

    Cox, Christian L; Cox, Robert M

    2015-09-01

    Aridity is an important determinant of species distributions, shaping both ecological and evolutionary diversity. Lizards and snakes are often abundant in deserts, suggesting a high potential for adaptation or acclimation to arid habitats. However, phylogenetic evidence indicates that squamate diversity in deserts may be more strongly tied to speciation within arid habitats than to convergent evolution following repeated colonization from mesic habitats. To assess the frequency of evolutionary transitions in habitat aridity while simultaneously testing for associated changes in water-balance physiology, we analyzed estimates of total evaporative water loss (EWL) for 120 squamate species inhabiting arid, semiarid, or mesic habitats. Phylogenetic reconstructions revealed that evolutionary transitions to and from semiarid habitats were much more common than those between arid and mesic extremes. Species from mesic habitats exhibited significantly higher EWL than those from arid habitats, while species from semiarid habitats had intermediate EWL. Phylogenetic comparative methods confirmed this association between habitat aridity and EWL despite phylogenetic signal in each. Thus, the historical colonization of arid habitats by squamates is repeatedly associated with adaptive changes in EWL. This physiological convergence, which may reflect both phenotypic plasticity and genetic adaptation, has likely contributed to the success of squamates in arid environments.

  1. Désertification des parcours arides au Maroc

    Directory of Open Access Journals (Sweden)

    Mahyou, H.

    2010-01-01

    Full Text Available Desertification of Arid Rangelands in Morocco. Rangeland or natural arid pastures of Morocco are ecosystems where there is a natural or seminatural vegetation composed of steppes, shrubs and grassland. They cover about 82% of the Moroccan arid lands. These areas represent livelihoods for thousands of people and protect the country from desertification. Despite the importance of the rangelands and the threat of desertification, it is surprising that up to date there is no comprehensive assessment of their condition and their evolution, hindering any plan for desertification alleviation. However, the available information on selected pilot areas shows that these rangelands are threatened by desertification. It's associated with biodiversity loss and contributes to climate change. The leading causes of land degradation are the human actions combined with climate. The establishment of a comprehensive surveillance system based on remote sensing, biophysics and socio-economic data must be envisaged to provide policymakers with an operational tool adapted to the spatio-temporal monitoring of desertification.

  2. Leaf protein concentrate as food supplement from arid zone plants.

    Science.gov (United States)

    Rathore, Mala

    2010-06-01

    In arid and semi-arid areas where prevalence of droughts and famines is a recurring feature, forest cover can in general make valuable contributions to food security and provide income to the rural poor. Protein and calorie malnutrition is widespread in these areas leading to high child mortality rate. Plant species can play an important role in overcoming this by being used as a source of leaf protein concentrate (LPC), a highly nutritious food. LPC should be considered seriously as it can serve as an additional protein source in the case of non-ruminants and man, especially in drought prone areas. The use of LPC in developing countries as an alternative protein source to fishmeal in broiler diet holds tremendous promise as it can substantially lower high cost of fishmeal and eventually the acute shortage of animal protein supply. Potential tropical plants for LPC production have been evaluated and selected for further research by United States Department of Agriculture. The present study was aimed to determine the potential of arid zone plants for preparation of LPC. Extraction characteristics of the several plant species have been studied and the quality of LPC prepared from them was investigated. Different fractions, chloroplastic and cytoplasmic proteins, were analyzed for their crude protein contents. Analysis of LPC shows considerable differences in their protein contents, which was found to range from 13.7 to 88.9%. Based on this, Achyranthes aspera and Tephrosia purpurea were found to be the best suited plants for LPC preparation.

  3. Saline dust storms and their ecological impacts in arid regions

    Institute of Scientific and Technical Information of China (English)

    Jilili; Abuduwaili

    2010-01-01

    In many arid and semiarid regions,saline playas represent a significant source of unconsoli-dated sediments available for aeolian transport,and severe saline dust storms occur frequently due to human disturbance.In this study,saline dust storms are reviewed systematically from the aspects of con-cept,general characteristics,conditions of occurrence,distribution and ecological impact.Our researches showed that saline dust storms are a kind of chemical dust storm originating in dry lake beds in arid and semiarid regions;large areas of unconsolidated saline playa sediments and frequent strong winds are the basic factors to saline dust storm occurrence;there are differentiation characteristics in deposition flux and chemical composition with wind-blown distance during saline dust storm diffusion;and saline dust storm diffusion to some extent increases glacier melt and results in soil salinization in arid regions.An under-standing of saline dust storms is important to guide disaster prevention and ecological rehabilitation.

  4. Changes in aridity in response to the global warming hiatus

    Science.gov (United States)

    Guan, Xiaodan; Huang, Jianping; Guo, Ruixia

    2017-02-01

    The global warming slowdown or warming hiatus, began around the year 2000 and has persisted for nearly 15 years. Most studies have focused on the interpretation of the hiatus in temperature. In this study, changes in a global aridity index (AI) were analyzed by using a newly developed dynamical adjustment method that can successfully identify and separate dynamically induced and radiatively forced aridity changes in the raw data. The AI and Palmer Drought Severity Index produced a wetting zone over the mid-to-high latitudes of the Northern Hemisphere in recent decades. The dynamical adjustment analysis suggested that this wetting zone occurred in response to the global warming hiatus. The dynamically induced AI (DAI) played a major role in the AI changes during the hiatus period, and its relationships with the North Atlantic Oscillation (NAO), Pacific Decadal Oscillation (PDO), and Atlantic Multi-decadal Oscillation (AMO) also indicated that different phases of the NAO, PDO, and AMO contributed to different performances of the DAI over the Northern Hemisphere. Although the aridity wetting over the mid-to-high latitudes may relieve long-term drying in certain regions, the hiatus is temporary, and so is the relief. Accelerated global warming will return when the NAO, PDO, and AMO revert to their opposite phases in the future, and the wetting zone is likely to disappear.

  5. Assessment of surface water resources availability using catchment modeling and the results of tracer studies in the meso-scale Migina Catchment, Rwanda

    NARCIS (Netherlands)

    Munyaneza, O.; Mukubwa, A.; Maskey, S.; Wenninger, J.W.; Uhlenbrook, S.

    2013-01-01

    In the last couple of years, different hydrological research projects were undertaken in the Migina catchment (243.2 km2), a tributary of the Kagera river in Southern Rwanda. These projects were aimed to understand hydrological processes of the catchment using analytical and experimental approaches

  6. Assessment of surface water resources availability using catchment modelling and the results of tracer studies in the mesoscale Migina Catchment, Rwanda

    NARCIS (Netherlands)

    Munyaneza, O.; Mukubwa, A.; Maskey, S.; Uhlenbrook, S.; Wenninger, J.W.

    2014-01-01

    In the present study, we developed a catchment hydrological model which can be used to inform water resources planning and decision making for better management of the Migina Catchment (257.4 km2). The semi-distributed hydrological model HEC-HMS (Hydrologic Engineering Center – the Hydrologic Modell

  7. Internally Drained Supraglacial River Catchments on the Southwest Greenland Ice Sheet

    Science.gov (United States)

    Yang, K.; Smith, L. C.; Chu, V. W.; Pitcher, L. H.; Gleason, C. J.

    2015-12-01

    Internally drained catchments are the hydrologic units on the Greenland ice sheet (GrIS) surface that collect and drain meltwater into moulins or supraglacial lakes without out flows. Understanding the spatial pattern of these internal catchments is critical, which can provide key information about how supraglacial meltwater is transported and released on the ice surface. This study proposed an automatic approach to detect supraglacial hydrologic features (rivers, lakes, moulins, and internal catchments) located at southwest GrIS from Landsat-8 OLI panchromatic imagery. A total of 800 internal catchments are delineated and the average catchment size (river network length) is found to increase with elevations. In addition, moulins are the prime way to drain internal catchments and the average moulin densities decrease with elevations. Adaptive depression area thresholds are calculated to achieve optimal match between DEM-modeled and image-detected internal catchment patterns. The pattern of these image-detected internal catchments also indicates that: 1) not all the DEM-modeled topographic depressions act as meltwater sinks; 2) moulin distribution greatly impacts the internal catchment patterns; and 3) topographic depressions can be connected downstream without being fully filled, changing the fragmentary of the internal catchments.

  8. Land use change and carbon cycle in arid and semi-arid lands of East and Central Asia

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Dramatic changes in land use have occurred in arid and semi-arid landsof Asia during the 20th century. Grassland conversion into croplands and ecosystem degradation is widespread due to the high growth rate of human population and political reforms of pastoral systems. Rangeland degradation made many parts of this region vulnerable to environmental and political changes. The collapse of the livestock sector in some states of central Asia, expansion of livestock inChina and intensive degradation of grasslands in China are examples of the responses of pastoral systems to these changes over the past decades. Carbon dynamics in this region is highly variable in space and time. Land use/cover changes with widespread reduction of forest and grasslands increased carbon emission from the region.

  9. Integrated flow and temperature modeling at the catchment scale

    DEFF Research Database (Denmark)

    Loinaz, Maria Christina; Davidsen, Hasse Kampp; Butts, Michael

    2013-01-01

    , the Silver Creek Basin in Idaho, where stream temperature affects the populations of fish and other aquatic organisms. The model calibration highlights the importance of spatially distributed flow dynamics in the catchment to accurately predict stream temperatures. The results also show the value...... of including temperature data in an integrated flow model calibration because temperature data provide additional constraints on the flow sources and volumes. Simulations show that a reduction of 10% in the groundwater flow to the Silver Creek Basin can cause average and maximum temperature increases in Silver...... Creek over 0.3°C and 1.5°C, respectively. In spring-fed systems like Silver Creek, it is clearly not feasible to separate river habitat restoration from upstream catchment and groundwater management....

  10. Kresoxim methyl deposition, drift and runoff in a vineyard catchment.

    Science.gov (United States)

    Lefrancq, M; Imfeld, G; Payraudeau, S; Millet, M

    2013-01-01

    Surface runoff and spray drift represent a primary mode of pesticide mobilisation from agricultural land to ecosystem. Though pesticide drift has mainly been studied at small scale (inverse weighting distance and ordinary kriging) and ranged between 53 g and 61 g (5.8 and 6.6% of the total mass applied). The amount of KM drifted on roads was 50 times larger than that in runoff water collected at the outlet of the catchment. Although KM application was carried out under regular operational and climatic conditions, its deposition on non-target surfaces may be significant and lead to pesticide runoff. These results can be anticipated as a starting point for assessing pesticide deposition during spray application and corresponding pesticide runoff in agricultural catchments.

  11. A conceptual glacio-hydrological model for high mountainous catchments

    Directory of Open Access Journals (Sweden)

    B. Schaefli

    2005-01-01

    Full Text Available In high mountainous catchments, the spatial precipitation and therefore the overall water balance is generally difficult to estimate. The present paper describes the structure and calibration of a semi-lumped conceptual glacio-hydrological model for the joint simulation of daily discharge and annual glacier mass balance that represents a better integrator of the water balance. The model has been developed for climate change impact studies and has therefore a parsimonious structure; it requires three input times series – precipitation, temperature and potential evapotranspiration – and has 7 parameters to calibrate. A multi-signal approach considering daily discharge and – if available – annual glacier mass balance has been developed for the calibration of these parameters. The model has been calibrated for three different catchments in the Swiss Alps having glaciation rates between 37% and 52%. It simulates well the observed daily discharge, the hydrological regime and some basic glaciological features, such as the annual mass balance.

  12. Use of remote sensing for hydrological parameterisation of Alpine catchments

    Directory of Open Access Journals (Sweden)

    H. Bach

    2003-01-01

    Full Text Available Physically-based water balance models require a realistic parameterisation of land surface characteristics of a catchment. Alpine areas are very complex with strong topographically-induced gradients of environmental conditions, which makes the hydrological parameterisation of Alpine catchments difficult. Within a few kilometres the water balance of a region (mountain peak or valley can differ completely. Hence, remote sensing is invaluable for retrieving hydrologically relevant land surface parameters. The assimilation of the retrieved information into the water balance model PROMET is demonstrated for the Toce basin in Piemonte/Northern Italy. In addition to land use, albedos and leaf area indices were derived from LANDSAT-TM imagery. Runoff, modelled by a water balance approach, agreed well with observations without calibration of the hydrological model. Keywords: PROMET, fuzzy logic based land use classification, albedo, leaf area index

  13. Restoring Landform Geodiversity in Modified Rivers and Catchments

    Science.gov (United States)

    Smith, Ben; Clifford, Nicholas

    2014-05-01

    Extensive human modification and exploitation has created degraded and simplified systems lacking many of the landforms which would characterise healthy, geodiverse rivers. As awareness of geodiversity grows we must look to ways not only to conserve geodiversity but to also restore or create landforms which contribute to geodiverse environments. River restoration, with lessons learned over the last 30 years and across multiple continents, has much to offer as an exemplar of how to understand, restore or create geodiversity. Although not mentioned explicitly, there is an implicit emphasis in the Water Framework Directive on the importance of landforms and geodiversity, with landform units and assemblages at the reach scale assumed to provide the physical template for a healthy aquatic ecosystem. The focus on hydromorphology has increased the importance of geomorphology within river restoration programmes. The dominant paradigm is to restore landforms in order to increase habitat heterogeneity and improve biodiversity within rivers. However, the process of landform restoration is also a goal in its own right in the context of geodiversity, and extensive compilations of restoration experiences allow an inventory and pattern of landform (re-) creation to be assembled, and an assessment of landform function as well as landform presence/absence to be made. Accordingly, this paper outlines three principal research questions: Which landforms are commonly reinstated in river restoration activities? How do these landforms function compared to natural equivalents and thus contribute to 'functional' geodiversity as compared to the 'aesthetic' geodiversity? How does landform diversity scale from reach to catchment and contribute to larger-scale geodiversity? Data from the UK National River Restoration Inventory and the RHS are combined to assess the frequency and spatial distribution of commonly created landforms in relation to catchment type and more local context. Analysis is

  14. Catchment Very-High Frequency Hydrochemistry: the Critex Chemical House

    Science.gov (United States)

    Floury, P.; Gaillardet, J.; Tallec, G.; Blanchouin, A.; Ansart, P.

    2015-12-01

    Exploring the variations of river quality at very high frequency is still a big challenge that has fundamental implications both for understanding catchment ecosystems and for water quality monitoring. Within the French Critical Zone program CRITEX, we have proposed to develop a prototype called "Chemical House", applying the "lab on field" concept to one of the stream of the Orgeval Critical Zone Observatory. The Orgeval catchment (45 km2) is part of the Critical Zone RBV ("Réseau des bassins versants") network. It is a typical temperate agricultural catchment that has been intensively monitored for the last 50 years for hydrology and nutrient chemistry. Agricultural inputs and land use are also finely monitored making Orgeval an ideal basin to test the response of the Critical Zone to agricultural forcing. Geology consists of a typical sedimentary basin of Cenozoic age with horizontal layers of limestones, silcrete and marls, covered by a thin loamy layer. Two main aquifers are present within the catchment: the Brie and the Champigny aquifers. Mean runoff is 780 mm/yr. The Chemical House is a fully automated lab and installed directly along the river, which performs measurement of all major dissolved elements such as Na, Cl, Mg, Ca, NO3, SO4 and K every half hour. It also records all physical parameters (Temperature, pH, conductivity, O2 dissolved, Turbidity) of the water every minute. Orgeval Chemical House started to measure river chemistry on June 12, 2015 and has successfully now recorded several months of data. We will present the architecture of the Chemical House and the first reproducibility and accuracy tests made during the summer drought 2015 period. Preliminary results show that the chemical house is recoding significant nychtemeral (day/night) cycles for each element. We also observe that each element has its own behaviour along a day. First results open great prospects.

  15. Hydrological response of a small catchment burned by experimental fire

    Directory of Open Access Journals (Sweden)

    C. R. Stoof

    2011-04-01

    Full Text Available Fire can considerably change hydrological processes, increasing the risk of extreme flooding and erosion events. Although hydrological processes are largely affected by scale, catchment-scale studies on the hydrological impact of fire are scarce, and nested approaches are rarely used. Taking a unique approach, we performed a catchment-scale experimental fire to improve insight into the drivers of fire impact on hydrology. In north-central Portugal, rainfall, canopy interception, streamflow and soil moisture were monitored in shrub-covered paired catchments pre- and post-fire. Post-fire runoff coefficients were higher than pre-fire, and fire changed the rainfall-streamflow relationship – although the increase in streamflow was only significant at the subcatchment-scale. Fire also increased the response of topsoil moisture to rainfall, and caused more rapid drying of topsoils after rain events. Since soil physical changes due to fire were not apparent, we suggest that changes resulting from vegetation removal played an important role in increasing streamflow after fire, namely: (1 increased effective rainfall and decreased transpiration – increasing the amount of water available for (subsurface runoff, (2 more rapid development of soil water repellency and decreased surface water storage – increasing overland flow risk, (3 more rapid breakdown of post-fire soil water repellency – increasing infiltration during extended rain events. Results stress that fire impact on hydrology is largely affected by scale, highlight the hydrological impact of fire on small scales, and emphasize the risk of overestimating fire impact when upscaling plot-scale studies to the catchment-scale. Finally, they increase understanding of the processes contributing to post-fire flooding and erosion events.

  16. Suspended sediment apportionment in a South-Korean mountain catchment

    Science.gov (United States)

    Birkholz, Axel; Meusburger, Katrin; Park, Ji-Hyung; Alewell, Christine

    2016-04-01

    Due to the rapid agricultural expansion and intensification during the last decades in South-Korea, large areas of hill slope forests were transformed to paddies and vegetable fields. The intensive agriculture and the easily erodible soils in our catchment are a major reason for the increased erosion causing suspended sediments to infiltrate into the close drinking water reservoir. The drinking water reservoir Lake Soyang provides water supply for over ten million people in Seoul. Landscape managers need to know the exact origin of these sediments before they can create landscape amelioration schemes. We applied a compound-specific stable isotope (CSSI) approach (Alewell et al., 2015) to apportion the sources of the suspended sediments between forest and agricultural soil contribution to the suspended sediments in a different catchment and applied the same approach to identify and quantify the different sources of the suspended sediments in the river(s) contributing to Lake Soyang. We sampled eight soil sites within the catchment considering the different landuse types forest, rice paddies, maize and vegetables. Suspended sediments were sampled at three outlets of the different sub-catchments. Soils and suspended sediments are analysed for bulk carbon and nitrogen isotopes, compound-specific carbon isotopes of plant-wax derived long-chain fatty acids and long-chain n-alkanes. Fatty acid and alkane isotopes are then used in mixing calculations and the mixing model software IsoSource to find out the contribution of the different source soils to the suspended sediments. We present first data of the source soils and the suspended sediments. C. Alewell, A. Birkholz, K. Meusburger, Y. Schindler-Wildhaber, L. Mabit, 2015. Sediment source attribution from multiple land use systems with CSIA. Biogeosciences Discuss. 12: 14245-14269.

  17. Creating a catchment scale perspective for river restoration

    Science.gov (United States)

    Benda, L.; Miller, D.; Barquín, J.

    2011-09-01

    One of the major challenges in river restoration is to identify the natural fluvial landscape in catchments with a long history of river control. Intensive land use on valley floors often predates the earliest remote sensing: levees, dikes, dams, and other structures alter valley-floor morphology, river channels and flow regimes. Consequently, morphological patterns indicative of the fluvial landscape including multiple channels, extensive floodplains, wetlands, and fluvial-riparian and tributary-confluence dynamics can be obscured, and information to develop appropriate and cost effective river restoration strategies can be unavailable. This is the case in the Pas River catchment in northern Spain (650 km2), in which land use and development have obscured the natural fluvial landscape in many parts of the basin. To address this issue we used computer tools to examine the spatial patterns of fluvial landscapes that are associated with five domains of hydro-geomorphic processes and landforms. Using a 5-m digital elevation model, valley-floor surfaces were mapped according to elevation above the channel and proximity to key geomorphic processes. The predicted fluvial landscape is patchily distributed according to hillslope and valley topography, river network structure, and channel elevation profiles. The vast majority of the fluvial landscape in the main segments of the Pas River catchment is presently masked by human infrastructure, with only 15% not impacted by river control structures and development. The reconstructed fluvial landscape provides a catchment scale context to support restoration planning, in which areas of potential ecological productivity and diversity could be targeted for in-channel, floodplain and riparian restoration projects.

  18. Geographically Isolated Wetlands and Catchment Hydrology: A Modified Model Analyses

    Science.gov (United States)

    Evenson, G.; Golden, H. E.; Lane, C.; D'Amico, E.

    2014-12-01

    Geographically isolated wetlands (GIWs), typically defined as depressional wetlands surrounded by uplands, support an array of hydrological and ecological processes. However, key research questions concerning the hydrological connectivity of GIWs and their impacts on downgradient surface waters remain unanswered. This is particularly important for regulation and management of these systems. For example, in the past decade United States Supreme Court decisions suggest that GIWs can be afforded protection if significant connectivity exists between these waters and traditional navigable waters. Here we developed a simulation procedure to quantify the effects of various spatial distributions of GIWs across the landscape on the downgradient hydrograph using a refined version of the Soil and Water Assessment Tool (SWAT), a catchment-scale hydrological simulation model. We modified the SWAT FORTRAN source code and employed an alternative hydrologic response unit (HRU) definition to facilitate an improved representation of GIW hydrologic processes and connectivity relationships to other surface waters, and to quantify their downgradient hydrological effects. We applied the modified SWAT model to an ~ 202 km2 catchment in the Coastal Plain of North Carolina, USA, exhibiting a substantial population of mapped GIWs. Results from our series of GIW distribution scenarios suggest that: (1) Our representation of GIWs within SWAT conforms to field-based characterizations of regional GIWs in most respects; (2) GIWs exhibit substantial seasonally-dependent effects upon downgradient base flow; (3) GIWs mitigate peak flows, particularly following high rainfall events; and (4) The presence of GIWs on the landscape impacts the catchment water balance (e.g., by increasing groundwater outflows). Our outcomes support the hypothesis that GIWs have an important catchment-scale effect on downgradient streamflow.

  19. Creating a catchment scale perspective for river restoration

    Directory of Open Access Journals (Sweden)

    L. Benda

    2011-09-01

    Full Text Available One of the major challenges in river restoration is to identify the natural fluvial landscape in catchments with a long history of river control. Intensive land use on valley floors often predates the earliest remote sensing: levees, dikes, dams, and other structures alter valley-floor morphology, river channels and flow regimes. Consequently, morphological patterns indicative of the fluvial landscape including multiple channels, extensive floodplains, wetlands, and fluvial-riparian and tributary-confluence dynamics can be obscured, and information to develop appropriate and cost effective river restoration strategies can be unavailable. This is the case in the Pas River catchment in northern Spain (650 km2, in which land use and development have obscured the natural fluvial landscape in many parts of the basin. To address this issue we used computer tools to examine the spatial patterns of fluvial landscapes that are associated with five domains of hydro-geomorphic processes and landforms. Using a 5-m digital elevation model, valley-floor surfaces were mapped according to elevation above the channel and proximity to key geomorphic processes. The predicted fluvial landscape is patchily distributed according to hillslope and valley topography, river network structure, and channel elevation profiles. The vast majority of the fluvial landscape in the main segments of the Pas River catchment is presently masked by human infrastructure, with only 15% not impacted by river control structures and development. The reconstructed fluvial landscape provides a catchment scale context to support restoration planning, in which areas of potential ecological productivity and diversity could be targeted for in-channel, floodplain and riparian restoration projects.

  20. Catchment-scale herbicides transport: Theory and application

    Science.gov (United States)

    Bertuzzo, E.; Thomet, M.; Botter, G.; Rinaldo, A.

    2013-02-01

    This paper proposes and tests a model which couples the description of hydrologic flow and transport of herbicides at catchment scales. The model accounts for streamflow components' age to characterize short and long term fluctuations of herbicide flux concentrations in stream waters, whose peaks exceeding a toxic threshold are key to exposure risk of aquatic ecosystems. The model is based on a travel time formulation of transport embedding a source zone that describes near surface herbicide dynamics. To this aim we generalize a recently proposed scheme for the analytical derivation of travel time distributions to the case of solutes that can be partially taken up by transpiration and undergo chemical degradation. The framework developed is evaluated by comparing modeled hydrographs and atrazine chemographs with those measured in the Aabach agricultural catchment (Switzerland). The model proves reliable in defining complex transport features shaped by the interplay of long term processes, related to the persistence of solute components in soils, and short term dynamics related to storm inter-arrivals. The effects of stochasticity in rainfall patterns and application dates on concentrations and loads in runoff are assessed via Monte Carlo simulations, highlighting the crucial role played by the first rainfall event occurring after herbicide application. A probabilistic framework for critical determinants of exposure risk to aquatic communities is defined. Modeling of herbicides circulation at catchment scale thus emerges as essential tools for ecological risk assessment.

  1. Potential possibilities of water retention in agricultural loess catchments

    Directory of Open Access Journals (Sweden)

    Zubala Tomasz

    2016-09-01

    Full Text Available The growing water deficit and the increased demand for water, as well as economic problems and inadequate spatial planning in many regions indicate a necessity of developing more effective rules of programming and realisation of works concerning the water management in small catchments. The paper presents a sample analysis of the possibilities of increasing water retention in the agricultural loess catchments with periodic streams. The scope of the study included the determination of physical parameters of selected sub-catchments (geometry, soil cover, land use, etc. and of the sources of threat to water resources, resulting from construction and geomorphological conditions. Pre-design assumptions of dammings were developed, taking into account anti-erosion protective measures, and treatments increasing the landscape retention of water were proposed. Creating surface retention objects should be an important source of water in simplified agroecosystems, especially in regions, where productivity to a great extent depends on natural weather conditions. Proper management of the fourth-order loess basin of the Ciemięga River (area of about 150 km2, the presence of 50 lateral valleys could give a temporary reservoir retention reaching 500 thousand m3. Farmers should be encouraged to seek “own water sources” (including the accumulation of water within wasteland, using appropriate economic instruments (tax reliefs for the documented volume of retained water, e.g. in small retention reservoirs.

  2. Sediment sources in the Upper Severn catchment: a fingerprinting approach

    Directory of Open Access Journals (Sweden)

    A. L. Collins

    1997-01-01

    Full Text Available Suspended sediment sources in the Upper Severn catchment are quantified using a composite fingerprinting technique combining statistically-verified signatures with a multivariate mixing model. Composite fingerprints are developed from a suite of diagnostic properties comprising trace metal (Fe, Mn, AI, heavy metal (Cu, Zn, Pb, Cr, Co, Ni, base cation (Na, Mg, Ca, K, organic (C, N, radiometric (137Cs, 210Pb, and other (total P determinands. A numerical mixing model, to compare the fingerprints of contemporary catchment source materials with those of fluvial suspended sediment in transit and those of recent overbank floodplain deposits, provides a means of quantifying present and past sediment sources respectively. Sources are classified in terms of eroding surface soils under different land uses and channel banks. Eroding surface soils are the most important source of the contemporary suspended sediment loads sampled at the Institute of Hydrology flow gauging stations at Plynlimon and at Abermule. The erosion of forest soils, associated with the autumn and winter commercial activities of the Forestry Commission, is particularly evident. Reconstruction of sediment provenance over the recent past using a sediment core from the active river floodpiain at Abermule, in conjunction with a 137Cs chronology, demonstrates the significance of recent phases of afforestation and deforestation for accelerated catchment soil erosion.

  3. Quantifying macropore recharge: Examples from a semi-arid area

    Science.gov (United States)

    Wood, W.W.; Rainwater, K.A.; Thompson, D.B.

    1997-01-01

    The purpose of this paper is to illustrate the significantly increased resolution of determining macropore recharge by combining physical, chemical, and isotopic methods of analysis. Techniques for quantifying macropore recharge were developed for both small-scale (1 to 10 km2) and regional-scale areas in and semi-arid areas. The Southern High Plains region of Texas and New Mexico was used as a representative field site to test these methods. Macropore recharge in small-scale areas is considered to be the difference between total recharge through floors of topographically dosed basins and interstitial recharge through the same area. On the regional scale, macropore recharge was considered to be the difference between regional average annual recharge and interstitial recharge measured in the unsaturated zone. Stable isotopic composition of ground water and precipitation was used us an independent estimate of macropore recharge on the regional scale. Results of this analysis suggest that in the Southern High Plains recharge flux through macropores is between 60 and 80 percent of the total 11 mm/y. Between 15 and 35 percent of the recharge occurs by interstitial recharge through the basin floors. Approximately 5 percent of the total recharge occurs as either interstitial or matrix recharge between the basin floors, representing approximately 95 percent of the area. The approach is applicable to other arid and semi-arid areas that focus rainfall into depressions or valleys.The purpose of this paper is to illustrate the significantly increased resolution of determining macropore recharge by combining physical, chemical, and isotopic methods of analysis. Techniques for quantifying macropore recharge were developed for both small-scale (1 to 10 km2) and regional-scale areas in arid and semi-arid areas. The Southern High Plains region of Texas and New Mexico was used as a representative field site to test these methods. Macropore recharge in small-scale areas is considered

  4. Spatial distribution and comparison of aridity indices in Extremadura, southwestern Spain

    Science.gov (United States)

    Moral, Francisco J.; Rebollo, Francisco J.; Paniagua, Luis L.; García-Martín, Abelardo; Honorio, Fulgencio

    2016-11-01

    In semi-arid lands with warm climates, aridity is a real hazard, with the threat of desertification because of greater precipitation variability and prolonged droughts. Aridity indices can be used to identify areas prone to desertification. The present study aimed to analyse the spatial distribution of aridity in Extremadura, southwestern Spain, using three indices: the De Martonne aridity index ( I DM), the Pinna combinative index ( I P), and the Food and Agriculture Organization (FAO) aridity index ( I F). Temperature, precipitation, and evapotranspiration data from 90 weather stations located throughout Extremadura and 27 along boundaries with at least 30-year length (within the 1980-2011 period) were used to compute each index at each station. The statistical properties of each aridity index were assessed, and later, they were mapped by means of an integrated geographic information system (GIS) and a multivariate geostatistical (regression-kriging) algorithm in which exhaustive secondary information on elevation was incorporated. Annual and seasonal I DM and I F, and annual I P-kriged maps were generated. According to annual I DM, the semi-arid and Mediterranean conditions are predominant in the region, covering about 70 % of the territory, while about 94 % of the areas are classified as dry and semi-dry Mediterranean based on annual I P and about 86 % are classified as semi-arid and dry categories based on annual I F. The most vulnerable to aridity are the natural regions located to the west, the south, and the southeast of Extremadura, especially during summer, when arid conditions are found across the region. Although the three aridity indices were highly correlated, displaying similar spatial patterns, I DM was preferred because it can better discriminate different climate conditions in Extremadura.

  5. ARID1A immunohistochemistry improves outcome prediction in invasive urothelial carcinoma of urinary bladder.

    Science.gov (United States)

    Faraj, Sheila F; Chaux, Alcides; Gonzalez-Roibon, Nilda; Munari, Enrico; Ellis, Carla; Driscoll, Tina; Schoenberg, Mark P; Bivalacqua, Trinity J; Shih, Ie-Ming; Netto, George J

    2014-11-01

    AT-rich interactive domain 1A (ARID1A) is tumor suppressor gene that interacts with BRG1 adenosine triphosphatase to form a SWI/SNF chromatin remodeling protein complex. Inactivation of ARID1A has been described in several neoplasms, including epithelial ovarian and endometrial carcinomas, and has been correlated with prognosis. In the current study, ARID1A expression in urothelial carcinoma (UC) of the bladder and its association with clinicopathological parameters and outcome are addressed. Five tissue microarrays were constructed from 136 cystectomy specimens performed for UC at our institution. Nuclear ARID1A staining was evaluated using immunohistochemistry. An H-score was calculated as the sum of the products of intensity (0-3) multiplied by extent of expression (0%-100%). Average H-score per case was used for statistical analysis. ARID1A expression was categorized in low and high using Youden index to define the cut point. ARID1A expression significantly increased from normal to noninvasive UC to invasive UC. For both tumor progression and cancer death, Youden index yielded an H-score of 288 as the optimal cut point for ARID1A expression. Low ARID1A expression showed a tendency for lower risk of tumor progression and cancer mortality. Adding ARID1A expression to pathologic features offers a better model for predicting outcome than pathologic features alone. Low ARID1A expression was more frequently seen in earlier stage disease. There was a tendency for low ARID1A expression to predict better outcome. More importantly, the findings indicate that adding ARID1A expression to pathologic features increases the goodness of fit of the predictive model.

  6. Estimation of soil moisture-thermal infrared emissivity relation in arid and semi-arid environments using satellite observations

    Science.gov (United States)

    Grazia Blasi, Maria; Masiello, Guido; Serio, Carmine; Venafra, Sara; Liuzzi, Giuliano; Dini, Luigi

    2016-04-01

    The retrieval of surface parameters is very important for various aspects concerning the climatological and meteorological context. At this purpose surface emissivity represents one of the most important parameters useful for different applications such as the estimation of climate changes and land cover features. It is known that thermal infrared (TIR) emissivity is affected by soil moisture, but there are very few works in literature on this issue. This study is aimed to analyze and find a relation between satellite soil moisture data and TIR emissivity focusing on arid and semi-arid environments. These two parameters, together with the land surface temperature, are fundamental for a better understanding of the physical phenomena implied in the soil-atmosphere interactions and the surface energy balance. They are also important in several fields of study, such as climatology, meteorology, hydrology and agriculture. In particular, there are several studies stating a correlation between soil moisture and the emissivity at 8-9 μm in desertic soils, which corresponds to the quartz Reststrahlen, a feature which is typical of sandy soils. We investigated several areas characterized by arid or semi-arid environments, focusing our attention on the Dahra desert (Senegal), and on the Negev desert (Israel). For the Dahra desert we considered both in situ, provided by the International Soil Moisture Network, and satellite soil moisture data, from ASCAT and AMSR-E sensors, for the whole year 2011. In the case of the Negev desert soil moisture data are derived from ASCAT observations and we computed a soil moisture index from a temporal series of SAR data acquired by the Cosmo-SkyMed constellation covering a period of six months, from June 2015 to November 2015. For both cases soil moisture data were related to the retrieved TIR emissivity from the geostationary satellite SEVIRI in three different spectral channels, at 8.7 μm, 10.8 μm and 12 μm. A Kalman filter physical

  7. Sediment transfer in coastal catchments exposed to typhoons: lessons learnt from catchments contaminated with Fukushima radioactive fallout

    Science.gov (United States)

    Evrard, Olivier; Laceby, J. Patrick; Onda, Yuichi; Lefèvre, Irène

    2016-04-01

    Several coastal catchments located in Northeastern Japan received significant radioactive fallout following the Fukushima nuclear accident in March 2011, with initial 137Cs activities exceeding 100 kBq m-2. Although radiocesium poses a considerable health risk for local populations, it also provides a relatively straightforward tracer to investigate sediment transfers in catchments exposed to spring floods and heavy typhoons in late summer and early fall. This study focused on two catchments (the Niida and Mano Rivers) covering a surface area of 450 km² that drain the main radioactive plume. A database of radiocesium activities measured in potential source samples (n=260) was used to model radiocesium dilution in 342 sediment deposit samples collected at 38 locations during 9 different sampling campaigns conducted every 6 months from Nov. 2011 to Nov. 2015. The dilution of the initial radiocesium contamination in sediment was individually calculated for each of the 342 samples using a distribution model. Results show that the proportion of heavily contaminated sediment increased from 27% to 39% after the occurrence of typhoons in 2013 (with rainfall amount exceeding 100 mm in 48 hours) and from 29% to 45% after the 2015 spring floods, illustrating the occurrence of soil erosion and resuspension of contaminated material stored in the river channel. In contrast, the occurrence of a very strong typhoon in September 2015 (up to 450 mm in 48h) led to the dilution and the flush of the contamination to the Pacific Ocean, with the proportion of heavily contaminated material decreasing from 45 to 21%. This case study in catchments impacted by the Fukushima accident illustrates their high reactivity to both human activities and rainfall. These results will improve our understanding of sediment transfers in similar coastal mountainous environments frequently exposed to heavy rainfall.

  8. High resolution modeling of a small urban catchment

    Science.gov (United States)

    Skouri-Plakali, Ilektra; Ichiba, Abdellah; Gires, Auguste; Tchiguirinskaia, Ioulia; Schertzer, Daniel

    2016-04-01

    Flooding is one of the most complex issues that urban environments have to deal with. In France, flooding remains the first natural risk with 72% of decrees state of natural disaster issued between October 1982 and mid-November 2014. Flooding is a result of meteorological extremes that are usually aggravated by the hydrological behavior of urban catchments and human factors. The continuing urbanization process is indeed changing the whole urban water cycle by limiting the infiltration and promoting runoff. Urban environments are very complex systems due to their extreme variability, the interference between human activities and natural processes but also the effect of the ongoing urbanization process that changes the landscape and hardly influences their hydrologic behavior. Moreover, many recent works highlight the need to simulate all urban water processes at their specific temporal and spatial scales. However, considering urban catchments heterogeneity still challenging for urban hydrology, even after advances noticed in term of high-resolution data collection and computational resources. This issue is more to be related to the architecture of urban models being used and how far these models are ready to take into account the extreme variability of urban catchments. In this work, high spatio-temporal resolution modeling is performed for a small and well-equipped urban catchment. The aim of this work is to identify urban modeling needs in terms of spatial and temporal resolution especially for a very small urban area (3.7 ha urban catchment located in the Perreux-sur-Marne city at the southeast of Paris) MultiHydro model was selected to carry out this work, it is a physical based and fully distributed model that interacts four existing modules each of them representing a portion of the water cycle in urban environments. MultiHydro was implemented at 10m, 5m and 2m resolution. Simulations were performed at different spatio-temporal resolutions and analyzed with

  9. CAOS: the nested catchment soil-vegetation-atmosphere observation platform

    Science.gov (United States)

    Weiler, Markus; Blume, Theresa

    2016-04-01

    Most catchment based observations linking hydrometeorology, ecohydrology, soil hydrology and hydrogeology are typically not integrated with each other and lack a consistent and appropriate spatial-temporal resolution. Within the research network CAOS (Catchments As Organized Systems), we have initiated and developed a novel and integrated observation platform in several catchments in Luxembourg. In 20 nested catchments covering three distinct geologies the subscale processes at the bedrock-soil-vegetation-atmosphere interface are being monitored at 46 sensor cluster locations. Each sensor cluster is designed to observe a variety of different fluxes and state variables above and below ground, in the saturated and unsaturated zone. The numbers of sensors are chosen to capture the spatial variability as well the average dynamics. At each of these sensor clusters three soil moisture profiles with sensors at different depths, four soil temperature profiles as well as matric potential, air temperature, relative humidity, global radiation, rainfall/throughfall, sapflow and shallow groundwater and stream water levels are measured continuously. In addition, most sensors also measure temperature (water, soil, atmosphere) and electrical conductivity. This setup allows us to determine the local water and energy balance at each of these sites. The discharge gauging sites in the nested catchments are also equipped with automatic water samplers to monitor water quality and water stable isotopes continuously. Furthermore, water temperature and electrical conductivity observations are extended to over 120 locations distributed across the entire stream network to capture the energy exchange between the groundwater, stream water and atmosphere. The measurements at the sensor clusters are complemented by hydrometeorological observations (rain radar, network of distrometers and dense network of precipitation gauges) and linked with high resolution meteorological models. In this

  10. Applying profile- and catchment-based mathematical models for evaluating the run-off from a Nordic catchment

    Directory of Open Access Journals (Sweden)

    Farkas Csilla

    2016-09-01

    Full Text Available Knowledge of hydrological processes and water balance elements are important for climate adaptive water management as well as for introducing mitigation measures aiming to improve surface water quality. Mathematical models have the potential to estimate changes in hydrological processes under changing climatic or land use conditions. These models, indeed, need careful calibration and testing before being applied in decision making. The aim of this study was to compare the capability of five different hydrological models to predict the runoff and the soil water balance elements of a small catchment in Norway. The models were harmonised and calibrated against the same data set. In overall, a good agreement between the measured and simulated runoff was obtained for the different models when integrating the results over a week or longer periods. Model simulations indicate that forest appears to be very important for the water balance in the catchment, and that there is a lack of information on land use specific water balance elements. We concluded that joint application of hydrological models serves as a good background for ensemble modelling of water transport processes within a catchment and can highlight the uncertainty of models forecast.

  11. Androgen Receptor Coactivator ARID4B Is Required for the Function of Sertoli Cells in Spermatogenesis.

    Science.gov (United States)

    Wu, Ray-Chang; Zeng, Yang; Pan, I-Wen; Wu, Mei-Yi

    2015-09-01

    Defects in spermatogenesis, a process that produces spermatozoa inside seminiferous tubules of the testis, result in male infertility. Spermatogenic progression is highly dependent on a microenvironment provided by Sertoli cells, the only somatic cells and epithelium of seminiferous tubules. However, genes that regulate such an important activity of Sertoli cells are poorly understood. Here, we found that AT-rich interactive domain 4B (ARID4B), is essential for the function of Sertoli cells to regulate spermatogenesis. Specifically, we generated Sertoli cell-specific Arid4b knockout (Arid4bSCKO) mice, and showed that the Arid4bSCKO male mice were completely infertile with impaired testis development and significantly reduced testis size. Importantly, severe structural defects accompanied by loss of germ cells and Sertoli cell-only phenotype were found in many seminiferous tubules of the Arid4bSCKO testes. In addition, maturation of Sertoli cells was significantly delayed in the Arid4bSCKO mice, associated with delayed onset of spermatogenesis. Spermatogenic progression was also defective, showing an arrest at the round spermatid stage in the Arid4bSCKO testes. Interestingly, we showed that ARID4B functions as a "coactivator" of androgen receptor and is required for optimal transcriptional activation of reproductive homeobox 5, an androgen receptor target gene specifically expressed in Sertoli cells and critical for spermatogenesis. Together, our study identified ARID4B to be a key regulator of Sertoli cell function important for male germ cell development.

  12. Review of several problems on the study of eco-hydrological processes in arid zones

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Ecosystem degradation is a common and cardinal environmental problem in arid zones. The change in the eco-hydrological processes is the basic cause responsible for such a problem. The study on the eco-hydrological processes in arid zones has become a forefront and focus of the eco-environmental research. Recent studies on eco-hydrological processes in arid zones show that the primary vegetation pattern and its eco-hydrological effect are of the most stable state of the ecosystem in arid zones. Special water absorption ways of plants in arid zones and the hydraulic lift and reverse hydraulic lift functions of some plants are the key mechanisms to maintain the stability of the ecosystem in arid zones. In the case of water shortage, ensuring ecological water requirement and maintaining proper ecological ground- water table are the prerequisite to keep healthful operation of the ecosystem in arid zones. The paper reviews some advances in the study of eco-hydrological processes in arid zones. It puts forward the concepts of critical ecological water requirement, optimal ecological water requirement and saturated ecological water requirement, and discusses their determination methods. It also emphasizes that the studies on natural vegetation pattern and eco-hydrological effect, on plants with hydraulic lift function, on water sources for plant absorption, on ecological water requirement and ecological groundwater table for different plant species should be strengthened to determine the species composition and pattern suitable for the restoration and reestablishment of vegetation in different arid zones in China.

  13. Forecasting the impact of global changes on the water resources of a mountainous catchment in the Chilean Andes

    Science.gov (United States)

    Ruelland, D.; Campéon, C.; Dezetter, A.; Jourde, H.

    2012-04-01

    This study aims to simulate the complex interrelationships between climate forcing, human pressure and dynamics of groundwater and surface water of the upper Elqui catchment (5 660 km2) in the Chilean Andes. The water resources of this mountainous, semi-arid catchment has been undergoing a growing pressure because of high climate variability and of the economic mutations of various sectors (agriculture, tourism), which have impacted water availability of the area. Due to the agriculture-based development in the region, water scarcity is thus a matter of great concern for this basin. Hydrological simulations were performed with a conceptual model that takes into account a shallow reservoir supplied by precipitation and feeding evapotranspiration, surface/sub-surface runoff and infiltration, and (ii) a deep reservoir fed by infiltration and generating the baseflow. A third reservoir, in which fluxes are controlled by temperature, has been introduced to account for the snowmelt regime of the catchment. A 30-year period (1979-2008) was chosen to capture long-term hydro-climatic variability due to alternating ENSO and LNSO events. Then water uses (dam functioning, agricultural and domestic withdrawals) were integrated into the model. The model was calibrated and validated with streamflow data on the basis of a multi-objective function that aggregates a variety of goodness-of-fit criteria. Prospective climatic and anthropogenic scenarios were finally elaborated and forced into the model in order to propose midterm (2050 horizon) simulations. The model correctly reproduces the observed discharge at the basin outlet. Depending on the modelling complexity, NSE coefficients are about 0.82-0.90 over the calibration period (1979-1990) and 0.78-0.84 over the validation period (1991-2008). The volume error between observation and simulation is lower than 15% over the whole period studied. The dynamics of both the water level in the deep conceptual reservoir and the water table

  14. Influence of geology, regolith and soil on fluid flow pathways in an upland catchment in central NSW, Australia

    Science.gov (United States)

    Bernardi, Tony

    2014-05-01

    Influence of geology, regolith and soil on fluid flow pathways in an upland catchment in central NSW, Australia. Tony Bernardi and Leah Moore Dryland Salinity Hazard Mitigation Program (DSHMP), University of Canberra, ACT 2601, AUSTRALIA The diversity of salt expression in central NSW has defied classification because salt expression, mobilisation and transport is highly variable and is typically site specific. Hydrological models are extensively used to simulate possible outcomes for a range of land use changes to mitigate the mobilisation and transport of salt into the streams or across the land surface. The ability of these models to mimic reality can be variable thereby reducing the confidence in the models outputs and uptake of strategic management changes by the community. This study focuses on a 250 ha semi-arid sub-catchment of Little River catchment in central west NSW in the Murray-Darling Basin, Australia. We propose that an understanding the structure of the landforms and configuration of rock, regolith and soil materials at the study site influences fluid flow pathways in the landscape and can be related to observed variations in the chemical composition and salinity of surface and aquifer water. Preliminary geological mapping of the site identified the dominant rock type as a pink and grey dacite and in localised mid-slope areas, a coarsely crystalline biotite-phyric granodiorite. Samples were taken at regular intervals from natural exposures in eroded stream banks and in excavations made during the installation of neutron moisture meter tubes. In order to establish mineral weathering pathways, samples were taken from the relatively unweathered core to the outer weathered 'onion skins' of corestones on both substrates, and then up through the regolith profile, including the soil zone, to the land surface. X-ray diffraction (XRD) analysis and X-ray fluorescence (XRF) was conducted on the rock and soil/saprock samples. Electromagnetic induction (EMI

  15. Factors controlling inter-catchment variation of mean transit time with consideration of temporal variability

    Science.gov (United States)

    Ma, Wenchao; Yamanaka, Tsutomu

    2016-03-01

    The catchment transit time, a lumped descriptor reflecting both time scale and spatial structure of catchment hydrology can provide useful insights into chemical/nuclear pollution risks within a catchment. Despite its importance, factors controlling spatial variation of mean transit time (MTT) are not yet well understood. In this study, we estimated time-variant MTTs for about ten years (2003-2012) in five mesoscale sub-catchments of the Fuji River catchment, central Japan, to establish the factors controlling their inter-catchment variation with consideration of temporal variability. For this purpose, we employed a lumped hydrological model that was calibrated and validated by hydrometric and isotopic tracer observations. Temporal variation patterns of estimated MTT were similar in all sub-catchments, but with differing amplitudes. Inter-catchment variation of MTT was greater in dry periods than wet periods, suggesting spatial variation of MTT is controlled by water 'stock' rather than by 'flow'. Although the long-term average MTT (LAMTT) in each catchment was correlated with mean slope, coverage of forest (or conversely, other land use types), coverage of sand-shale conglomerate, and groundwater storage, the multiple linear regression revealed that inter-catchment variation of LAMTT is principally controlled by the amount of groundwater storage. This is smaller in mountainous areas covered mostly by forests and greater in plain areas with less forest coverage and smaller slope. This study highlights the topographic control of MTT via groundwater storage, which might be a more important factor in mesoscale catchments, including both mountains and plains, rather than in smaller catchments dominated by mountainous topography.

  16. Progress in the identification of catchments with co-existent multiple steady states and finite resilience

    Science.gov (United States)

    Peterson, T. J.; Western, A. W.; Thyer, M. A.; Frost, A. J.

    2015-12-01

    Hydrology has implicitly assumed that catchments are infinitely resilient to droughts and floods. No matter the magnitude of the climatic disturbance, almost all hydrological models simulate full recovery and hence assume infinite resilience. Recent research shows that catchments can undergo fundamental change during major droughts and this change in behavior is not captured by rainfall-runoff models. To date, the field of hydrological resilience has relied on theoretical deterministic models or vague resilience concepts, with the identification of catchments with multiple steady states (henceforth, attractors) remaining elusive. This is primarily due to the challenges stochastic forcing introduces into quantifying disturbance and recovery, and because resilience theory does not adequately address stochastic forcing. Drawing from recent hydrological resilience theory on catchment disturbance and recovery, a data-driven hidden Markov model is proposed for identifying recovery to a different hydrological state following major climatic disturbances. Application to selected unregulated catchments within Victoria, Australia, shows that after the Millennium Drought (~1995-2010) some catchments are yet to recover and have persisted within a functionally different hydrological state compared to that prior to the drought. Conversely, some catchments fully recovered at the cessation of the drought. This provides the first known field evidence that some catchments may have multiple attractors. Additionally, catchments are shown to differ in their resistance to the drought, with some catchments switching to a drought state at the commencement of the meteorological drought while other catchments taking ~10 years to switch to a hydrological drought state. In addition to separating hydrological droughts from meteorological droughts, this research provides a pathway for quantifying catchment resilience and resistance to climatic disturbances.

  17. The "Teflon basin" myth: Snow-soil interactions in mountain catchments in the western US

    Science.gov (United States)

    Williams, M. W.; Cowie, R. M.

    2015-12-01

    In much of western North America, snow and snowmelt provide the primary means for storage of winter precipitation, effectively transferring water from the relatively wet winter season to the typically dry summers. A common assumption is that high-elevation catchments in the western United States behave like "Teflon basins" and that water released from seasonal storage in snow packs flows directly into streams with little or no interaction with underlying soils. Here I present information from a variety of catchments in the Colorado Front Range on snowmelt/soil interactions using isotopic, geochemical, nutrient and hydrometric data in 2- and 3- component hydrograph separations, along with end-member mixing analysis (EMMA). For most catchments we measured these parameters in weekly precipitation, the seasonal snowpack, snowmelt before contact with the ground, discharge, springs, soil solution, and groundwater. We ran EMMA at the catchment scale for catchments that represent the rain-snow transition zone in the montane forest, the seasonally snow covered sub-alpine to alpine transition zone, and a high-elevation alpine zone near the continental divide. In all catchments three end-members were the source waters for about 95% of discharge. Two end-members were the same in all catchments, snow and groundwater. For the alpine catchment talus springs was the third water source, while rain was the third water source in the two lower-elevation catchments. For all three catchments, soil solution plotted with stream waters along or near a line connecting the snow and groundwater end-members. Thus, for seasonally snow-covered catchments from montane to alpine ecosystems, snowmelt infiltrates underlying soils before snowmelt recharges groundwater reservoirs and contributes to surface flows. Seasonally snow-covered catchments are not Teflon basins. Rather, snowmelt infiltrates soils where solute concentrations are changed by biological and geochemical processes.

  18. Sediment transport in steep forested catchments - An assessment of scale and disturbance

    Science.gov (United States)

    Hancock, G. R.; Hugo, J.; Webb, A. A.; Turner, L.

    2017-04-01

    Stream sediment loads (both bedload and suspended sediment) are problematic to measure due to the time and equipment needed. There is a dearth of such data sets globally let alone for Australia. However, such data are needed to quantify sediment transport type and rates, landscape evolution, effect of human disturbance as well as patterns and temporal response. Here we present the findings from 8 steepslope forested catchments dominated by headwater streams (size range 15-100 ha) in south-eastern Australia where both bedload and suspended load have been measured over multiple years. The results demonstrate that suspended load is the dominant component and there is no consistent suspended to bedload ratio for the catchments. The suspended sediment to bedload ratio appears to be catchment specific. There was no relationship between total load (or bedload/suspended load) and average catchment slope, stream length, shape or any geomorphic descriptor. However catchment total load was found to be significantly related to catchment area. Of the 8 catchments examined here, 6 had been harvested for timber in previous decades (with large areas of forest removed) while 2 catchments had minimal disturbance (Control catchments). There was no difference in sediment loads from the harvested and Control catchments. The results demonstrate that although land disturbance had previously occurred the management practices employed in each catchment were effective in the long term. This provides confidence that the forest harvesting and subsequent management do not produce detrimental effects in the medium to long term. An assessment of erosion rates and likely soil production rates suggests that the catchments are eroding soil at the rate it is being produced.

  19. River water quality modelling in developing a catchment water safety plan

    OpenAIRE

    Vieira, J. M. Pereira; Pinho, José L. S.

    2014-01-01

    The primary aim of a catchment water safety plan is to reduce risks within the catchment to protect the quality of drinking water sources at the intake point. Even where effective arrangements for catchment management and control have been implemented, unexpected deterioration in raw water quality can pose a risk to treated drinking water quality. Thus potential sources of pollution impacting the area of influence of the intake should be identified and monitored. An important part of any catc...

  20. Examining the effects of forest thinning on runoff responses at different catchments scales in forested headwaters

    Science.gov (United States)

    Dung, B. X.; Gomi, T.; Onda, Y.; Kato, H.; Hiraoka, M.

    2012-12-01

    We conducted field observation in nested headwater catchments draining Japanese cypress (Chamaecyparis obtusa) and cedar (Cryptomeria japonica) forests at Tochigi prefectures for examining the effects of forest thinning on runoff generation at different catchment scales. 50% of the stems was removed with line thinning in catchment K2 (treatment catchment), while catchment K3 remained untreated as a control. We also monitored nested catchments within K2-1 (17.1 ha) as K2-2 (10.2 ha), K2-3 (3.7 ha) and K2-4 (5.1 ha), and within K3-1 (8.9 ha) as K3-2 (3.0 ha). Runoff from the catchments was monitored during the pre-thinning (from April, 2010 to May 2011), and the post-thinning periods (from June 2011 to July 2012). Paired-catchment and hydrograph separation analysis were used to evaluate the effects of forest thinning on runoff generation at different catchment scales. We developed the pre-thinning calibration equation for predicting post-thinning responses. Paired-catchment analysis revealed that annual catchment runoff increased 648 mm in K2-1, 414 mm in K2-2, 517 mm in K2-3 and 487 mm in K2-4 after the thinning. Both quick and delayed runoff components only increased significantly in the larger catchments of K2-1 and K2-2, while only delayed runoff components of smaller catchments (K2-3 and K2-4) increased significantly during the post-thinning period. Increases of quick runoff in large catchments could be associated with quick runoff response to soil surface compaction by line thinning and skid trail installation. Increases of delayed runoff in small catchment may be associated with increase in net precipitation and decrease in evapotranspiration. Our finding showed that changes in internal hydrological flow pathways and associated changes in runoff components due to forest harvesting differ depending on the catchment sizes.

  1. Sediment transport in steep forested catchments: the role of disturbance and scale

    Science.gov (United States)

    Hancock, Greg; Hugo, James; Webb, Ashley

    2016-04-01

    Sediment loads (both bedload and suspended sediment) are difficult to measure due to the time and equipment needed. However such data is needed to understand overall sediment transport rates, landscape evolution, effect of human disturbance as well as patterns and temporal response. There is a dearth of such data sets globally let along for Australia. Here we present the findings from 8 steep slope forested catchments dominated by headwater streams (size range 15-100 hectares) in south-eastern Australia where both bedload and suspended load have been measured over multiple years. The results demonstrate that suspended load is the dominant component. There appears to be no consistent suspended to bedload ratio for the catchments. The suspended sediment to bedload ratio appears to be catchment specific. There was no relationship between total load (or bedload/suspended load) and average catchment slope, stream length, shape or any geomorphic descriptor. Again this appears to be catchment specific. However catchment total load was found to be significantly related to catchment area and demonstrates strong log-log linear behaviour. Comparing these total loads with total load data from a nearby larger catchments (100km2 to 1000km2) demonstrates that there is a significant scaling relationship across all catchment sizes in this region. The scaling relationships found here are similar to those found globally and provide a unique insight into an understudied system. The data also provides the ability to assess sediment transport models and their reliability across different scales.

  2. Hydrological dynamics of a Mediterranean catchment in a global change context. (Romanyac catchment, Cap de Creus, Girona, Spain)

    Science.gov (United States)

    Latron, J.; Pardini, G.; Gispert, M.; Llorens, P.

    2009-04-01

    Mediterranean regions are characterized by unevenly distributed water resources, and consequently a more precise knowledge of the main hydrological processes and their variability and changes is crucial for a better management of water resources. However, the lack of hydrological information and data in most areas of the Mediterranean basin greatly difficult the analyses of changes in water resources at relevant scales. In this context, the Soil Science Unit GRCT48 from the University of Girona is conducting an integrated study of hydrological response, soil erosion and soil degradation processes in fragile Mediterranean areas undergoing changes in use and management. The study area is located in the Cap de Creus Peninsula (NE Spain), where land abandonment has been the outstanding characteristic over the last decades. The area is covered by terraced soils, most of them abandoned, and stands for a representative Mediterranean environment. Current land cover is a mosaic of areas with different shrubs according to wildfire occurrence. Residual patches of cork and pine trees are also present as well as small extensions of pastures. Finally some localized areas of vineyards and olive trees are still cultivated. The approach is based on the complementary use of plot and catchment scales to assess the effect of land cover and land use change on physical, chemical and biological parameters of soil quality and on rainfall-runoff-erosion relationships. Along the study period, observed rainfall-runoff response at the plot scale was highly variable among sites but also for a given environment, depending on antecedent wetness conditions and rainfall characteristics. Overall, surface runoff responses were low in all environments. Soil loss associated to rainfall-runoff events showed very large variations among sites, and also for a given site, between the different rainfall events. At the catchment scale, preliminary results obtained from the monitoring, of three catchments of

  3. Novel ideas for maximising dew collection to aid plant establishment to combat desertification and restore degraded dry and arid lands

    Science.gov (United States)

    Kotzen, Benz

    2014-05-01

    This paper focuses on the potential of dew to provide water to plants and potentially to people as well in remote and difficult to reach areas where rainfall and underground water cannot be harvested. The combat of desertification and the restoration of degraded and desertified dry and arid lands has never been more urgent. A key practical component of this strategy is the restoration of habitat with planting. But for habitat and planting to survive there needs to be an adequate supply of water. In most cases providing water to the plant's roots is vital. In some areas where habitats have been destroyed, sufficient water is immediately available, for example through seasonal rainfall, or it can be harvested to concentrate adequate supplies of water to the roots. However, in arid and hyper arid areas, as well as in some dryland areas, a consistent and adequate supply of water cannot be provided by any conventional proven method. Thus, as the need to combat desertification and to restore desertified dry and arid land increases, so the need to find novel methods of establishing and maintaining planting and thus habitat increases. In more traditional land management scenarios this can be achieved through manipulating landform on a micro and macro scale, for example, by creating catchments, thereby collecting precipitation and directing it to the plants. Where this cannot be done, other means of water supply are usually required. Bainbridge (2007) and others have shown that supplying water to plants is possible through a number of traditional methods, for example, using clay pots. But most of these techniques require an introduced source of water, for example, obtained through water harvesting methods or by delivering water to site in tanks and by water bowser. This can work but requires continuous manpower. It is expensive and can be physically prohibitive in areas where access is difficult and/or remote. The concept of using dew to supply water in drylands is not new

  4. On the Observed Ecohydrologic Dynamics of a Semiarid Catchment with Topographic Induced Microclimatic Controls

    Science.gov (United States)

    Gutierrez-Jurado, H. A.; Vivoni, E. R.; Bras, R. L.; Cikoski, C.; Harrison, B.; Istanbulluoglu, E.

    2009-12-01

    Understanding the impending effects of climate change on the cycling of water and its impacts on the structure of vegetation mosaics in semi-arid landscapes is critical for land conservation practices. In semiarid areas with complex terrain, the combination of elevation and aspect promotes variations in the water and surface energy balance, resulting in slopes with distinct ecologic, hydrologic and geomorphic properties. Therefore, quantifying the differential energy and water dynamics of the slopes can provide essential information on the potential effects of climate variability for semiarid landscapes. In this study, we use observations from a highly instrumented semiarid catchment in central New Mexico, to quantify the ecohydrologic dynamics of two distinct ecosystems: a Juniper (Juniperus monosperma) savanna on the north facing slope and a Creosote (Larrea tridentata) shrubland on the south facing slope. Using three years of data from a network of 40 soil moisture and temperature sensors arranged along transects, we examine the differential dynamics of the slopes. Furthermore, we use ~1.5 years of data from three Bowen Ratio Energy Balance systems (BREBs) to quantify the seasonal differences in evapotranspiration [ET] dynamics, and energy balance components (i.e. net radiation [Rn] ground heat flux [G], and sensible heat flux [H]) among the slopes. Finally, to close the water balance at the slopes we use one year of data from eight runoff plots in both slopes to assess the effect of vegetation on the rainfall-runoff relation. Results from the observation analyses show: similar long-term ET fluxes for the Juniper and Creosote ecosystems but longer soil moisture retention on the north facing slope soils; differences in the energy balance components show significant lower G in the Juniper system due to canopy shading. Finally, runoff production in the Creosote ecosystem is consistently more abundant and frequent than in the Juniper ecosystem throughout the year

  5. Karst catchments exhibited higher degradation stress from climate change than the non-karst catchments in southwest China: An ecohydrological perspective

    Science.gov (United States)

    Liu, Meixian; Xu, Xianli; Wang, Dingbao; Sun, Alexander Y.; Wang, Kelin

    2016-04-01

    Karst landform represents about 10% of the continental area and plays key roles in water supplies for almost a quarter of the global population. Knowledge of ecohydrological responses of karst landform to climate change is critical for both water resources management and ecological protection in these regions. This study investigated the effects of karst landform on the elasticity of actual evapotranspiration (derived by the Budyko equation), estimated the contribution of climate change and evaluated the implications, on the basis of 13 typical catchments that have different karst landform coverages in southwest China. Catchment properties, including the vegetation coverage, portion of karst landform (POK), drainage area, surface roughness, mean topographic wetness index, mean slope, and mean aspect, were selected to test the influencing factors for the elasticity of actual evapotranspiration. Results indicate that POK is the most influencing factor for the elasticity of actual evapotranspiration in this region. Moreover, the actual evapotranspiration in karst catchments is more sensitive to precipitation change and less sensitive to the potential evapotranspiration change than that in the non-karst catchments. On the other hand, the contribution of climate change to actual evapotranspiration was generally negative in this region. Furthermore, relatively large negative contributions mainly occurred in the karst-dominated catchments, suggesting that the karst catchments were exposed to higher degradation stress brought by the climate change than that in non-karst catchments.

  6. Understanding Hydrologic Processes in Semi-Arid Cold Climates

    Science.gov (United States)

    Barber, M. E.; Beutel, M.; Lamb, B.; Watts, R.

    2004-12-01

    Water shortages destabilize economies and ecosystems. These shortages are caused by complex interactions between climate variability, ecosystem processes, and increased demand from human activities. In the semi-arid region of the northwestern U.S., water availability during drought periods has already reached crisis levels and the problems are expected to intensify as the effects of global climate change and population growth continue to alter the supply and demand patterns. Many of the problems are critical to this region because hydropower, agriculture, navigation, fish and wildlife survival, water supply, tourism, environmental protection, and water-based recreation are vital to state economies and our way of life. In order to assess the spatial and temporal nature of hydrologic responses, consistent and comprehensive long-term data sets are needed. In response to these needs, we would like to propose the Spokane River drainage basin as a long-term hydrologic observatory. The Spokane River basin is located in eastern Washington and northern Idaho and is a tributary of the Columbia River. The watershed consists of several major surface water tributaries as well as natural and man-made lakes and reservoirs. With headwaters beginning in the Rocky Mountains, the drainage area is approximately 6,640 mi2. In addition to providing an excellent study area for examining many conventional water resource problems, the Spokane River watershed also presents a unique opportunity for investigating many of the hydrologic processes found in semi-arid cold climates. Snowfall in the watershed varies spatially between 35 inches near the mouth of the basin to over 112 inches at the headwaters. These varied hydrologic uses provide a unique opportunity to address many common challenges faced by water resource professionals. This broad array of issues encompasses science, engineering, agriculture, social sciences, economics, fisheries, and a host of other disciplines. In addition

  7. Improved climate risk simulations for rice in arid environments.

    Science.gov (United States)

    van Oort, Pepijn A J; de Vries, Michiel E; Yoshida, Hiroe; Saito, Kazuki

    2015-01-01

    We integrated recent research on cardinal temperatures for phenology and early leaf growth, spikelet formation, early morning flowering, transpirational cooling, and heat- and cold-induced sterility into an existing to crop growth model ORYZA2000. We compared for an arid environment observed potential yields with yields simulated with default ORYZA2000, with modified subversions of ORYZA2000 and with ORYZA_S, a model developed for the region of interest in the 1990s. Rice variety 'IR64' was sown monthly 15-times in a row in two locations in Senegal. The Senegal River Valley is located in the Sahel, near the Sahara desert with extreme temperatures during day and night. The existing subroutines underestimated cold stress and overestimated heat stress. Forcing the model to use observed spikelet number and phenology and replacing the existing heat and cold subroutines improved accuracy of yield simulation from EF = -0.32 to EF =0.70 (EF is modelling efficiency). The main causes of improved accuracy were that the new model subversions take into account transpirational cooling (which is high in arid environments) and early morning flowering for heat sterility, and minimum rather than average temperature for cold sterility. Simulations were less accurate when also spikelet number and phenology were simulated. Model efficiency was 0.14 with new heat and cold routines and improved to 0.48 when using new cardinal temperatures for phenology and early leaf growth. The new adapted subversion of ORYZA2000 offers a powerful analytic tool for climate change impact assessment and cropping calendar optimisation in arid regions.

  8. Improved climate risk simulations for rice in arid environments.

    Directory of Open Access Journals (Sweden)

    Pepijn A J van Oort

    Full Text Available We integrated recent research on cardinal temperatures for phenology and early leaf growth, spikelet formation, early morning flowering, transpirational cooling, and heat- and cold-induced sterility into an existing to crop growth model ORYZA2000. We compared for an arid environment observed potential yields with yields simulated with default ORYZA2000, with modified subversions of ORYZA2000 and with ORYZA_S, a model developed for the region of interest in the 1990s. Rice variety 'IR64' was sown monthly 15-times in a row in two locations in Senegal. The Senegal River Valley is located in the Sahel, near the Sahara desert with extreme temperatures during day and night. The existing subroutines underestimated cold stress and overestimated heat stress. Forcing the model to use observed spikelet number and phenology and replacing the existing heat and cold subroutines improved accuracy of yield simulation from EF = -0.32 to EF =0.70 (EF is modelling efficiency. The main causes of improved accuracy were that the new model subversions take into account transpirational cooling (which is high in arid environments and early morning flowering for heat sterility, and minimum rather than average temperature for cold sterility. Simulations were less accurate when also spikelet number and phenology were simulated. Model efficiency was 0.14 with new heat and cold routines and improved to 0.48 when using new cardinal temperatures for phenology and early leaf growth. The new adapted subversion of ORYZA2000 offers a powerful analytic tool for climate change impact assessment and cropping calendar optimisation in arid regions.

  9. Seasonal contribution of terrestrial organic matter and biological oxygen demand to the Baltic Sea from three contrasting river catchments

    DEFF Research Database (Denmark)

    Reader, H. E.; Stedmon, C. A.; Kritzberg, E. S.

    2014-01-01

    on the same order of magnitude for all three catchments. Biological oxygen demand (BOD) was used as a proxy for the lability of carbon in the system. The range of BOD values was similar for all three catchments, however, the ratio of BOD to DOC (an indication of the labile fraction) in Ume river was four...... times higher than in the southern two catchments. Total annual BOD loading to the Baltic Sea was twice as high in the northern catchment than in the two southern catchments. Lower winter temperatures and preservation of organic matter in the northern catchment combined with an intense spring flood help...

  10. Seasonal Variation in Hydrology Driving Shifts in Sources of Nitrate in an Agricultural Dominant Semi-arid Watershed

    Science.gov (United States)

    Moon Nielsen, L. G.; Orr, C. H.

    2010-12-01

    In the South Fork Palouse River in the semi-arid region of Eastern Washington State, surface water hydrology is driven by seasonal variation in precipitation, with peak surface water flow and highest Nitrate values observed from January to April, and lowest surface flows and corresponding lower Nitrate concentrations observed from June to August. Land-use in the watershed is predominantly non-irrigated cropland (82%) fertilized by synthetic fertilizer, with an additional 8% of land in urban areas. Due to the prevalence of anthropogenically influenced land in the watershed, Nitrate concentrations measured in streams here are chronically elevated above natural levels. Typically in an area that is dominated by agriculture, the source of Nitrate in surface waters draining agricultural land would be predicted to be synthetic fertilizer. However it is important to consider the impacts seasonal hydrological conditions can have upon Nitrate sources and flow paths. We investigated how Nitrate sources in Palouse streams and rivers changed seasonally to address the hypothesis that seasonal variation in precipitation shifts the dominant sources of Nitrate in surface waters. We based our determination of nitrogen source on the results from dual stable isotope analysis of Nitrate using the denitrifier method. Sampling was done at 7 locations of increasing catchment area along the South Fork Palouse River and tributary streams. Sampling site catchment area varied one order of magnitude from 70.9 to 717.4 km2. Surface waters at yearly low flow during the summer season indicated δ15N-Nitrate and δ18O-Nitrate ranging within generally accepted values to indicate Nitrate derived from animal and human waste. These can be attributed to waste water discharge from the urban areas in the watershed. Yearly hydrologic data suggests that during the winter season, increased precipitation causes a shift in δ15N-Nitrate and δ18O-Nitrate to values typically observed in sources derived from

  11. Controls of catchments` sub-storage contributions to dynamic water quality patterns in the stream network

    Science.gov (United States)

    Schuetz, Tobias; Maike Hegenauer, Anja

    2016-04-01

    Water quality is usually observed either continuously at a few stations within a catchment or with few snapshot sampling campaigns throughout the whole stream network. Although we know that the depletion of catchment sub-storages can vary throughout the stream network according to their actual water content (spatial variability of actual storage conditions can be caused amongst others by unevenly distributed rainfall, storage size or spatial differences in soil characteristics and land use), we know little about the impact of this process on spatial water quality patterns. For summer low flow recession periods, when stream water composition can be crucial for aquatic ecosystem conditions and the exceedance of water quality thresholds, knowledge on the controls of the dynamic interplay of catchment storages and stream water composition might improve water quality management and the implementation of corresponding mitigation measures. We studied this process throughout the stream network of a first-order agricultural headwater catchment in south-western Germany during two summer low flow recession periods. The underlying geology of the study area is a deep layer of aeolian loess, whilst the dominating soil is a silty calcaric regosol with gleizations in the colluvium. The land use in the catchment is dominated by viniculture (63 %) and arable crops (18 %). Due to the dense drainpipe network within the catchment we could identify 12 sub-catchments contributing during summer low flow recession periods to total stream discharge. We continuously observed discharge, electrical conductivity and water temperatures for 8 of the sub-catchments and at the catchment outlet. This data set was accomplished by 10 snapshot campaigns where we sampled for water temperatures, electrical conductivity, major ions, pH and O2 throughout the stream network. Using either discharge concentration relationships or time dependent functions, we derived continuous export rates for all measures in

  12. Temporal variations in runoff and soil loss in relation to soil conservation practices in catchments in Shiwaliks of lower Himalayas

    Directory of Open Access Journals (Sweden)

    S.S. Kukal

    2013-09-01

    Full Text Available The soil conservation strategies adopted in the catchments of Shiwaliks, the most fragile region in the Himalayan ecosystem, failed to serve their purpose after a few years of their execution. A study was carried out in four differentially-treated catchments to monitor the variation in runoff and soil loss. The treatments imposed during 1988 included fencing,planting native vegetation and engineering structures in catchment I ; planting native vegetation and fencing in catchment II ; fencing alone in catchment III in addition to an untreated catchment IV. The soil loss during the initial years (1989 – 1995 of imposition of the treatments was lowest (25. 2 t ha-1 in catchment I, treated to the maximum extent and highest (43. 3 t ha -1 in untreated catchment IV. During the later period (1996 – 2006 the trends reversed, i. e., catchment IV recorded the lowest (14. 1 t ha-1 soil loss whereas catchment I recorded the highest (23. 4 t ha-1 soil loss despite the fact that there was no change in the status of soil conservation or the characteristics of the catchments. The runoff was 71 % higher in untreated catchment than in treated catchments initially and this difference decreased to 27% during the later period.

  13. Aged Riverine Particulate Organic Carbon in Four UK Catchments

    Science.gov (United States)

    Adams, Jessica; Tipping, Edward; Bryant, Charlotte; Helliwell, Rachel; Toberman, Hannah; Quinton, John

    2016-04-01

    The riverine transport of particulate organic matter (POM) is a significant flux in the carbon cycle, and affects macronutrients and contaminants. We used radiocarbon to characterise POM at 9 riverine sites of four UK catchments (Avon, Conwy, Dee, Ribble) over a one-year period. High-discharge samples were collected on three or four occasions at each site. Suspended particulate matter (SPM) was obtained by centrifugation, and the samples were analysed for carbon isotopes. Concentrations of SPM and SPM organic carbon (OC) contents were also determined, and were found to have a significant negative correlation. For the 7 rivers draining predominantly rural catchments, PO14C values, expressed as percent modern carbon absolute (pMC), varied little among samplings at each site, and there was no significant difference in the average values among the sites. The overall average PO14C value for the 7 sites of 91.2 pMC corresponded to an average age of 680 14C years, but this value arises from the mixing of differently-aged components, and therefore significant amounts of organic matter older than the average value are present in the samples. Although topsoil erosion is probably the major source of the riverine POM, the average PO14C value is appreciably lower than topsoil values (which are typically 100 pMC). This is most likely explained by inputs of older subsoil OC from bank erosion, or the preferential loss of high-14C topsoil organic matter by mineralisation during riverine transport. The significantly lower average PO14C of samples from the River Calder (76.6 pMC), can be ascribed to components containing little or no radiocarbon, derived either from industrial sources or historical coal mining, and this effect is also seen in the River Ribble, downstream of its confluence with the Calder. At the global scale, the results significantly expand available information for PO14C in rivers draining catchments with low erosion rates.

  14. Soils as a buffer of contaminants in catchments

    Science.gov (United States)

    Evrard, Olivier

    2014-05-01

    Human activities deliver large quantities of contaminants into the environment through atmospheric emissions or direct releases. As many of those contaminants are particle-reactive, they bind strongly to the finest particles or on their organic matter fraction once they deposit onto soils. Contaminants may subsequently migrate in depth of the soil depending on their physico-chemical characteristics. They may also be redistributed along hillslopes in association with particles during soil erosion events and may be subsequently supplied to rivers, preventing to meet the international environmental targets (e.g. in the framework of the EU Water Framework Directive). In regions where soil erosion rates are low to moderate, a large quantity of particle-reactive contaminants may accumulate in soils that constitute a reservoir of pollutants that may be delivered to rivers during decades or centuries. This session will focus on the specific role played by soils as a reservoir of contaminants at the catchment scale. A better understanding of this role and a quantification of the persistence of contaminants in this reservoir will provide crucial insights to guide the implementation of efficient mitigation measures. Contributions to this session may address any aspect of particle-borne contaminant transfer at the catchment scale, with an emphasis on the role played by soils in their storage and transfer. Field-based or modeling studies may focus either on specific pollutants or on a wider range of substances, e.g. metals, radionuclides, organic contaminants. Key themes may include: • Contaminant budget at the hillslope vs. the catchment scales; • Evaluation of the contribution of the regional vs. local contamination sources; • Evaluation of the contaminant removal from soils by degradation vs. soil erosion; • Quantifying the persistence of contaminants in soils; • Discrimination between the legacy and the contemporary supply of contaminants to soils.

  15. The scaling method of specific catchment area from DEMs

    Institute of Scientific and Technical Information of China (English)

    YANG Xin; TANG Guoan; XlAO Chenchao; GAO Yiping; ZHU Shijie

    2011-01-01

    Specific Catchment Area (SCA) is defined as the upstream catchment area of a unit contour.As one of the key terrain parameters,it is widely used in the modeling of hydrology,soil erosion and ecological environment.However,SCA value changes significantly at different DEM resolutions,which inevitably affect terrain analysis results.SCA can be described as the ratio of Catchment Area (CA) and DEM grid length.In this paper,the scale effect of CA is firstly investigated.With Jiuyuangou Gully,a watershed about 70 km2 in northern Shaanxi Province of China,as the test area,it is found that the impacts of DEM scale on CA are different in spatial distribution.CA value in upslope location becomes bigger with the decrease of the DEM resolution.When the location is close to downstream areas the impact of DEM scale on CA is gradually weakening.The scale effect of CA can be concluded as a mathematic trend of exponential decline.Then,a downscaling model of SCA is put forward by introducing the scale factor and the location factor.The scaling model can realize the conversion of SCA value from a coarse DEM resolution to a finer one at pixel level.Experiment results show that the downscaled SCA was well revised,and consistent with SCA at the target resolution with respect to the statistical indexes,histogram and spatial distribution.With the advantages of no empirical parameters,the scaling model could be considered as a simple and objective model for SCA scaling in a rugged drainage area.

  16. Gully catchment as sediment sinks, not just a source

    Science.gov (United States)

    Larsen, Annegret; Heckmann, Tobias; Larsen, Joshua; Bork, Hans-Rudolf

    2016-04-01

    Catchment wide sediment fluxes have been modified throughout the Anthropocene, but it`s spatial and temporal dimension is still under debate. Here, we present a long-term sediment budget, highlighting the overlooked role of gullies as significant sediment sinks, and challenging the prevalent view of gullies as being exclusively conveyor belts of sediment. This is important, as sediment delivery from hillslopes to trunk streams represents a significant pathway of mass transfer in the landscape, with a large fraction facilitated by gully systems. In this study, we analysed the sediment mass balance and storage dynamics within a headwater gully catchment in central Europe over the last ~12 500 yrs. Human induced erosion resulted in hillslope erosion rates ~2.3 times higher than under naturally de-vegetated conditions during the Younger Dryas. However the total sediment inputs to the gully system (and therefore gully aggradation), were similar. Net gully storage has consistently increased to become the second largest term in the sediment budget after hillslope erosion (storage is ~45% and ~73% of inputs during two separate erosion and aggradation cycles). In terms of the depletion of gully sediment storage, the sediment mass balance shows that export beyond the gully fan was not significant until the last ~500 years, due to reduced gully fan accommodation space. The significance of storage effects on the gully sediment mass balance, particularly the export terms, means that it would be difficult to determine the influences of human impact and / or climatic changes from floodplain or lake sedimentary archives alone and that the sediment budgets of the headwater catchments from which they drain are more likely to provide these mechanistic links.

  17. The relative influence of climate and catchment properties on hydrological drought

    Science.gov (United States)

    Van Loon, Anne; Laaha, Gregor; Koffler, Daniel

    2014-05-01

    Studying hydrological drought (a below-normal water availability in groundwater, lakes and streams) is important to society and the ecosystem, but can also reveal interesting information about catchment functioning. This information can later be used for predicting drought in ungauged basins and to inform water management decisions. In this study, we used an extensive Austrian dataset of discharge measurements in clusters of catchments and combine this dataset with thematic information on climate and catchment properties. Our aim was to study the relative effects of climate and catchment characteristics on drought duration and deficit and on hydrological drought typology. Because the climate of the region is roughly uniform, our hypothesis was that the effect of differences of catchment properties would stand out. From time series of precipitation and discharge we identified droughts with the widely-used threshold level approach, defining a drought when a variable falls below a pre-defined threshold representing the regime. Drought characteristics that were analysed are drought duration and deficit. We also applied the typology of Van Loon & Van Lanen (2012). To explain differences in drought characteristics between catchments we did a correlation analysis with climate and catchment characteristics, based on Pearson correlation. We found very interesting patterns in the correlations of drought characteristics with climate and catchment properties: 1) Droughts with long duration (mean and maximum) and composite droughts are related to catchments with a high BFI (high baseflow) and a high percentage of shallow groundwater tables. 2) The deficit (mean and maximum) of both meteorological droughts and hydrological droughts is strongly related to catchment humidity, in this case quantified by average annual precipitation. 3) The hydrological drought types that are related to snow, i.e. cold snow season drought and snow melt drought, occur in catchments that are have a

  18. Response of sulphur dynamics in European catchments to decreasing sulphate deposition

    Directory of Open Access Journals (Sweden)

    A. Prechtel

    2001-01-01

    Full Text Available Following the decline in sulphur deposition in Europe, sulphate dynamics of catchments and the reversibility of anthropogenic acidification of soils and freshwaters became of major interest. Long-term trends in sulphate concentrations and fluxes in precipitation/throughfall and freshwaters of 20 European catchments were analysed to evaluate catchment response to decreasing sulphate deposition. Sulphate deposition in the catchments studied declined by 38-82% during the last decade. Sulphate concentrations in all freshwaters decreased significantly, but acidification reversal was clearly delayed in the German streams. In Scandinavian streams and Czech/Slovakian lakes sulphate concentrations responded quickly to decreased input. Sulphate fluxes in run-off showed no clear trend in Germany and Italy but decreased in Scandinavia, the Czech Republic and Slovakia. The decrease, however, was less than the decline in input fluxes. While long-term sulphate output fluxes from catchments were generally correlated to input fluxes, most catchments started a net release of sulphate during the early 1990s. Release of stored sulphate leads to a delay of acidification reversal and can be caused by four major processes. Desorption and excess mineralisation were regarded as the most important for the catchments investigated, while oxidation and weathering were of lesser importance for the long-term release of sulphate. Input from weathering has to be considered for the Italian catchments. Sulphate fluxes in German catchments, with deeply weathered soils and high soil storage capacity, responded more slowly to decreased deposition than catchments in Scandinavia and the Czech Republic/Slovakia, which have thin soils and relatively small sulphate storage. For predictions of acidification reversal, soil characteristics, sulphur pools and their dynamics have to be evaluated in future research. Keywords: acidification reversal, sulphur, sulphate release, Europe

  19. Assessment of LULC and climate change on the hydrology of Ashti Catchment, India using VIC model

    Indian Academy of Sciences (India)

    Narendra Hengade; T I Eldho

    2016-12-01

    The assessment of land use land cover (LULC) and climate change over the hydrology of a catchment has become inevitable and is an essential aspect to understand the water resources-related problems within the catchment. For large catchments, mesoscale models such as variable infiltration capacity (VIC) model are required for appropriate hydrological assessment. In this study, Ashti Catchment (sub-catchment of Godavari Basin in India) is considered as a case study to evaluate the impacts of LULC changes and rainfall trends on the hydrological variables using VIC model. The land cover data and rainfall trends for 40 years (1971−2010) were used as driving input parameters to simulate the hydrological changes over the Ashti Catchment and the results are compared with observed runoff. The good agreement between observed and simulated streamflows emphasises that the VIC model is able to evaluate the hydrological changes within the major catchment, satisfactorily. Further, the study shows that evapotranspiration is predominantly governed by the vegetation classes. Evapotranspiration is higher for the forest cover as compared to the evapotranspiration for shrubland/grassland, as the trees with deeper roots draws the soil moisture from the deeper soil layers. The results show that the spatial extent of change in rainfall trends is small as compared to the total catchment. The hydrological response of the catchment shows that small changes in monsoon rainfall predominantly contribute to runoff, which results in higher changes in runoff as the potential evapotranspiration within the catchments is achieved. The study also emphasises that the hydrological implications of climate change are not very significant on the Ashti Catchment, during the last 40 years (1971−2010).

  20. Assessment of LULC and climate change on the hydrology of Ashti Catchment, India using VIC model

    Science.gov (United States)

    Hengade, Narendra; Eldho, T. I.

    2016-12-01

    The assessment of land use land cover (LULC) and climate change over the hydrology of a catchment has become inevitable and is an essential aspect to understand the water resources-related problems within the catchment. For large catchments, mesoscale models such as variable infiltration capacity (VIC) model are required for appropriate hydrological assessment. In this study, Ashti Catchment (sub-catchment of Godavari Basin in India) is considered as a case study to evaluate the impacts of LULC changes and rainfall trends on the hydrological variables using VIC model. The land cover data and rainfall trends for 40 years (1971-2010) were used as driving input parameters to simulate the hydrological changes over the Ashti Catchment and the results are compared with observed runoff. The good agreement between observed and simulated streamflows emphasises that the VIC model is able to evaluate the hydrological changes within the major catchment, satisfactorily. Further, the study shows that evapotranspiration is predominantly governed by the vegetation classes. Evapotranspiration is higher for the forest cover as compared to the evapotranspiration for shrubland/grassland, as the trees with deeper roots draws the soil moisture from the deeper soil layers. The results show that the spatial extent of change in rainfall trends is small as compared to the total catchment. The hydrological response of the catchment shows that small changes in monsoon rainfall predominantly contribute to runoff, which results in higher changes in runoff as the potential evapotranspiration within the catchments is achieved. The study also emphasises that the hydrological implications of climate change are not very significant on the Ashti Catchment, during the last 40 years (1971-2010).

  1. Fit-for-purpose phosphorus management: do riparian buffers qualify in catchments with sandy soils?

    Science.gov (United States)

    Weaver, David; Summers, Robert

    2014-05-01

    Hillslope runoff and leaching studies, catchment-scale water quality measurements and P retention and release characteristics of stream bank and catchment soils were used to better understand reasons behind the reported ineffectiveness of riparian buffers for phosphorus (P) management in catchments with sandy soils from south-west Western Australia (WA). Catchment-scale water quality measurements of 60 % particulate P (PP) suggest that riparian buffers should improve water quality; however, runoff and leaching studies show 20 times more water and 2 to 3 orders of magnitude more P are transported through leaching than runoff processes. The ratio of filterable reactive P (FRP) to total P (TP) in surface runoff from the plots was 60 %, and when combined with leachate, 96 to 99 % of P lost from hillslopes was FRP, in contrast with 40 % measured as FRP at the large catchment scale. Measurements of the P retention and release characteristics of catchment soils (bank soil (bank soils suggest that catchment soils contain more P, are more P saturated and are significantly more likely to deliver FRP and TP in excess of water quality targets than stream bank soils. Stream bank soils are much more likely to retain P than contribute P to streams, and the in-stream mixing of FRP from the landscape with particulates from stream banks or stream beds is a potential mechanism to explain the change in P form from hillslopes (96 to 99 % FRP) to large catchments (40 % FRP). When considered in the context of previous work reporting that riparian buffers were ineffective for P management in this environment, these studies reinforce the notion that (1) riparian buffers are unlikely to provide fit-for-purpose P management in catchments with sandy soils, (2) most P delivered to streams in sandy soil catchments is FRP and travels via subsurface and leaching pathways and (3) large catchment-scale water quality measurements are not good indicators of hillslope P mobilisation and transport

  2. Carbon fluxes in an acid rain impacted boreal headwater catchment

    Science.gov (United States)

    Marx, Anne; Hintze, Simone; Jankovec, Jakub; Sanda, Martin; Dusek, Jaromir; Vogel, Tomas; van Geldern, Robert; Barth, Johannes A. C.

    2016-04-01

    Terrestrial carbon export via inland aquatic systems is a key process in the budget of the global carbon cycle. This includes loss of carbon to the atmosphere via gas evasion from rivers or reservoirs as well as carbon fixation in freshwater sediments. Headwater streams are the first endmembers of the transition of carbon between soils, groundwater and surface waters and the atmosphere. In order to quantify these processes the experimental catchment Uhlirska (1.78 km2) located in the northern Czech Republic was studied. Dissolved inorganic, dissolved organic and particulate organic carbon (DIC, DOC, POC) concentrations and isotopes were analyzed in ground-, soil -and stream waters between 2014 and 2015. In addition, carbon dioxide degassing was quantified via a stable isotope modelling approach. Results show a discharge-weighted total carbon export of 31.99 g C m-2 yr-1 of which CO2 degassing accounts 79 %. Carbon isotope ratios (δ13C) of DIC, DOC, and POC (in ‰ VPDB) ranged from -26.6 to -12.4 ‰ from -29.4 to -22.7 ‰ and from -30.6 to -26.6 ‰ respectively. The mean values for DIC are -21.8 ±3.8 ‰ -23.6 ±0.9 ‰ and -19.5 ±3.0 ‰ for soil, shallow ground and surface water compartments. For DOC, these compartments have mean values of -27.1 ±0.3 ‰ -27.0 ±0.8 ‰ and -27.4 ±0.7 ‰Ṁean POC value of shallow groundwaters and surface waters are -28.8 ±0.8 ‰ and -29.3 ±0.5 ‰ respectively. These isotope ranges indicate little turnover of organic material and predominant silicate weathering. The degassing of CO2 caused an enrichment of the δ13C-DIC values of up to 6.8 ‰ between a catchment gauge and the catchment outlet over a distance of 866 m. In addition, the Uhlirska catchment has only negligible natural sources of sulphate, yet SO42- accounts for 21 % of major stream water ions. This is most likely a remainder from acid rain impacts in the area.

  3. ECOLOGICAL ASPECTS OF BENTHIC COMMUNITIES FROM SOMESUL CALD CATCHMENT AREA

    Directory of Open Access Journals (Sweden)

    Karina Battes

    2001-01-01

    Full Text Available The present paper represents a preliminary study of periphyton and zoobenthos community from the Someşul Cald catchment area. Zoobenthos was sampled seasonally during 2000. Benthic community structure was similar at the five sampling sites. Thus, mayflies and chironomids recorded high numerical percentage abundances and densities. Oligochaetes, water mites and caddisflies were identified to species level. 38 Oligochaeta, 28 water mite and 12 caddis fly species were found in the sampling period. The samplings collected in the year 2001 included 80 algal species belonging to 5 phyla. Diatoms (Bacillariophyta dominated both qualitatively and quantitatively at all sampling sites.

  4. Seasonalstreamflow Generation At Variousspatial Scales On A Smallmediterranean Vineyard Catchment

    Science.gov (United States)

    Marofi, S.; Moussa, R.; Voltz, M.

    The importance of surface hydrological processes, under field and sub-catchment conditions, was examines on a small-cultivated watershed, located in South of France. Hydrological responses at different spatial scales were evaluated during the wetness and drier phases, which included the within-year and the long-term periods. The experimental design involved monitoring of surface runoff, streamflow and groundwaters behaviours, in response to rainfall events, during three hydrological cycles. In addition to the mean outlet of catchment and the two vineyard fields that have different situations, runoff was measured at 8 sub-catchments of site. Rainfall was monitored on continuous basis at 4 sites, and the water tables fluctuations also were recorded in more than 15 locations of catchment. During the experimentation period, more than 175 rainy events were observed. The dates analyse show that the regime of surface water, compound of three principals phases: (i) the phases of great flow circulation, (ii) the recession phases, and (iii) the phase without surface flow. The results also indicate that the annual runoff changes appreciably according to hydrological cycles and the rainfall variability. It varies from 28% to 50% of the total of precipitation. The inter-annual variations of the runoff also recovers that the annual runoff flow is insured for approximately 40% by the instantaneous floods, which occur the moment or a few hours only after precipitation, and about 60% by the recession periods, which take place for the long time after floods. The flood events were classified in three groups, differentiated by the initial water table levels and their occurrence period. The direct runoff and the baseflow calculation show that according to the type of flood, they change respectively from 7% to17% and 0% to 7% of precipitation. Comparing to the field areas, on average, the total runoff and direct runoff of the mean basin respectively are 46% and 35%. The water flow

  5. Aridity, desalination plants and tourism in the eastern Canary Islands

    Directory of Open Access Journals (Sweden)

    José-León García-Rodríguez

    2016-05-01

    Full Text Available The islands of Lanzarote and Fuerteventura are the easternmost of the Canary Islands, and are located on the southern edge of the temperate zone, in the subtropical anticyclone belt. With less than 150 mm of rainfall a year, they are classified as an arid zone. Their inhabitants have devised original agricultural systems to combat the aridity, although low yields have historically limited socio-economic development and population growth. These systems were used until the introduction of seawater desalination plants and the arrival of tourism in the last third of the twentieth century, which improved living standards for the local population but also led to a cultural transition. Nevertheless, these farming systems have left behind an important regional heritage, with an environmental and scenic value that has played an integral role in the latest phase of development. The systems have become a tourist attraction and have been central to the two islands being designated biosphere reserves by UNESCO. This article aims to analyse the main socioeconomic and land-use changes that have come about as a result of desalination technology.

  6. Uranium isotopes in carbonate aquifers of arid region setting

    DEFF Research Database (Denmark)

    Alshamsi, Dalal M.; Murad, Ahmed A.; Aldahan, Ala

    2013-01-01

    Groundwater in arid and semiarid regions is vital resource for many uses and therefore information about concentrations of uranium isotopes among other chemical parameters are necessary. In the study presented here, distribution of 238U and 235U in groundwater of four selected locations in the so......Groundwater in arid and semiarid regions is vital resource for many uses and therefore information about concentrations of uranium isotopes among other chemical parameters are necessary. In the study presented here, distribution of 238U and 235U in groundwater of four selected locations...... in the southern Arabian peninsula, namely at two locations within the United Arab Emirates (UAE) and two locations in Oman are discussed. The analyses of the uranium isotopes were performed using ICP-MS and the results indicated a range of concentrations for 235U and 238 U at 3–39 ng L-1 (average: 18 ng L-1......) and 429–5,293 ng L-1 (average: 2,508 ng L-1) respectively. These uranium concentrations are below the higher permissible WHO limit for drinking water and also comparable to averages found in groundwater from similar aquifers in Florida and Tunisia. Negative correlation between rainfall and uranium...

  7. Expansive Soil Properties in a Semi-Arid Region

    Directory of Open Access Journals (Sweden)

    MuawiaA. Dafalla

    2012-11-01

    Full Text Available The expansive soils in semi-arid regions are of great concern to design and geotechnical engineers. Range and variations of geotechnical properties of soils are very useful for appropriate design. Saudi Arabia; a semi arid region attracted the attention of researchers and practicing engineers over the last three decades following the rapid urbanizations in different parts of the country. Advanced testing equipments were made available for this study. The research group conducted joint visits with high officials from different municipality authorities to survey the problem and study the extent of damage to various structures. The areas visited included Al Ghatt, Al Zulfi, Al Hofuf, Um Al Sahik, Al Qatif, Tabuk, Tayma and Al Qaleeba. Single and two storey buildings, boundary walls, pavements and asphalt roads suffered significant damage in many parts of the visited locations. This paper presents the outcome of survey and a general review of previous works carried out for swelling clays in Saudi Arabia. Engineering properties for typical soil formation are presented.

  8. An Evaluation of Unsaturated Flow Models in an Arid Climate

    Energy Technology Data Exchange (ETDEWEB)

    Dixon, J. [Univ. of Nevada, Las Vegas, NV (United States)

    1999-12-01

    The objective of this study was to evaluate the effectiveness of two unsaturated flow models in arid regions. The area selected for the study was the Area 5 Radioactive Waste Management Site (RWMS) at the Nevada Test Site in Nye County, Nevada. The two models selected for this evaluation were HYDRUS-1D [Simunek et al., 1998] and the SHAW model [Flerchinger and Saxton, 1989]. Approximately 5 years of soil-water and atmospheric data collected from an instrumented weighing lysimeter site near the RWMS were used for building the models with actual initial and boundary conditions representative of the site. Physical processes affecting the site and model performance were explored. Model performance was based on a detailed sensitivity analysis and ultimately on storage comparisons. During the process of developing descriptive model input, procedures for converting hydraulic parameters for each model were explored. In addition, the compilation of atmospheric data collected at the site became a useful tool for developing predictive functions for future studies. The final model results were used to evaluate the capacities of the HYDRUS and SHAW models for predicting soil-moisture movement and variable surface phenomena for bare soil conditions in the arid vadose zone. The development of calibrated models along with the atmospheric and soil data collected at the site provide useful information for predicting future site performance at the RWMS.

  9. Lipid accumulation in prokaryotic microorganisms from arid habitats.

    Science.gov (United States)

    Hauschild, Philippa; Röttig, Annika; Madkour, Mohamed H; Al-Ansari, Ahmed M; Almakishah, Naief H; Steinbüchel, Alexander

    2017-03-01

    This review shall provide support for the suitability of arid environments as preferred location to search for unknown lipid-accumulative bacteria. Bacterial lipids are attracting more and more attention as sustainable replacement for mineral oil in fuel and plastic production. The development of prokaryotic microorganisms in arid desert habitats is affected by its harsh living conditions. Drought, nutrient limitation, strong radiation, and extreme temperatures necessitate effective adaption mechanisms. Accumulation of storage lipids as energy reserve and source of metabolic water represents a common adaption in desert animals and presumably in desert bacteria and archaea as well. Comparison of corresponding literature resulted in several bacterial species from desert habitats, which had already been described as lipid-accumulative elsewhere. Based on the gathered information, literature on microbial communities in hot desert, cold desert, and humid soil were analyzed on its content of lipid-accumulative bacteria. With more than 50% of the total community size in single studies, hot deserts appear to be more favorable for lipid-accumulative species then humid soil (≤20%) and cold deserts (≤17%). Low bacterial lipid accumulation in cold deserts is assumed to result from the influence of low temperatures on fatty acids and the increased necessity of permanent adaption methods.

  10. Soil microbial responses to nitrogen addition in arid ecosystems

    Directory of Open Access Journals (Sweden)

    Robert L Sinsabaugh

    2015-08-01

    Full Text Available The N cycle of arid ecosystems is influenced by low soil organic matter, high soil pH and extremes in water potential and temperature that lead to open canopies and development of biological soil crusts (biocrusts. We investigated the effects of N amendment on soil microbial dynamics in a Larrea tridentata-Ambrosia dumosa shrubland site in southern Nevada USA. Sites were fertilized with a NO3-NH4 mix at 0, 7, and 15 kg ha-1 yr-1 from March 2012 to March 2013. In March 2013, biocrust (0-0.5 cm and bulk soils (0-10 cm were collected beneath Ambrosia canopies and in the interspaces between plants. Biomass responses were assessed as bacterial and fungal SSU rRNA gene copy number and chlorophyll a concentration. Metabolic responses were measured by five ecoenzyme activities (EEA and rates of N transformation. By most measures, nutrient availability, microbial biomass and process rates were greater in soils beneath the shrub canopy compared to the interspace between plants, and greater in the surface biocrust horizon compared to the deeper 10 cm soil profile. Most measures responded positively to experimental N addition. Effect sizes were generally greater for bulk soil than biocrust. Results were incorporated into a meta-analysis of arid ecosystem responses to N.

  11. A methodology to assess and evaluate rainwater harvesting techniques in (semi-) arid regions

    NARCIS (Netherlands)

    Adham, Ammar; Riksen, Michel; Ouessar, Mohamed; Ritsema, Coen J.

    2016-01-01

    Arid and semi-arid regions around the world face water scarcity problems due to lack of precipitation and unpredictable rainfall patterns. For thousands of years, rainwater harvesting (RWH) techniques have been applied to cope with water scarcity. Researchers have used many different methodologie

  12. Resource flows, crops and soil fertility management in smallholder farming systems in semi-arid Zimbabwe

    NARCIS (Netherlands)

    Ncube, B.; Twomlow, S.J.; Dimes, J.P.; Wijk, van M.T.; Giller, K.E.

    2009-01-01

    Poor soil fertility and erratic rains are major constraints to crop production in semi-arid environments. In the smallholder farming systems of sub-Saharan Africa, these constraints are manifested in frequent crop failures and endemic food insecurity. We characterized a semi-arid smallholder farming

  13. Differences in the ARID-1 alpha expressions in squamous and adenosquamous carcinomas of uterine cervix.

    Science.gov (United States)

    Solakoglu Kahraman, Dudu; Diniz, Gulden; Sayhan, Sevil; Ayaz, Duygu; Uncel, Melek; Karadeniz, Tugba; Akman, Tulay; Ozdemir, Aykut

    2015-10-01

    AT-rich interactive domain 1A (ARID1A) is a tumor suppressor gene involved in chromatin remodeling which encodes ARID1A (BAF250a) protein. Recent studies have shown the loss of ARID1A expression in several types of tumors. This retrospective study was designed to evaluate the differences in tissue expressions of ARID1A in a spectrum of cervical neoplasms. Cervical intraepithelial neoplasms, invasive squamous or adenosquamous carcinomas were identified in 100 patients recently diagnosed as cervical neoplasms based on pathology databases. In this series, there were 29 low- and 29 high-grade cervical intraepithelial neoplasms, 27 squamous cell carcinomas, and 15 adenosquamous carcinomas. Mean age of the patients was 47.8 ± 13 years (20-80 years). It was determined that the expression of ARID1A was statistically significantly down-regulated in adenosquamous carcinomas when compared with non-invasive or invasive squamous cell carcinomas (p = 0.015). Lower levels of the ARID1A expression were detected in cases with adenosquamous carcinomas (60%), low- or high-grade squamous intraepithelial lesion (SIL) (31%), and squamous cell carcinomas (18.5%). Our findings have demonstrated the presence of a correlation between ARID1A expression and adenomatous differentiation of uterine squamous cell carcinomas. Therefore, ARID1A gene may suggestively have a role in the pathogenesis of cervical adenosquamous carcinomas.

  14. Analysis and evaluation of tillage on an alfisol ina semi-arid tropical region of India

    NARCIS (Netherlands)

    Klaij, M.C.

    1983-01-01

    Tillage field experiments were conducted on Alfisols in a semi-arid tropical environment in India. The research was conducted within the framework of the Farming Systems Research Program of the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT).To put the experiments into per

  15. Review and Synopsis of Natural and Human Controls on Fluvial Channel Processes in the Arid West

    Science.gov (United States)

    2007-09-01

    and other wet saline and alkaline soils: Problems identifying aquic conditions and hydric soils. In Aquic Conditions and Hydric Soils: The Problem...of-the-art of hydrology and hydrogeology in the arid and semi-arid areas of Africa. p. 255–266. Proceedings of the Sahel Forum 1989. Ouagadougou

  16. Impact of grazing on range plant community components under arid Mediterranean climate in northern Syria

    NARCIS (Netherlands)

    Niane, A.A.

    2013-01-01

    Keywords: Rotational grazing, full protection, continuous grazing species richness, species diversity, soil seed bank, Bayesian methods, Salsola vermiculata, seed longevity, rangeland management, Syria.   Rangelands represent 70% of the semi-arid and arid Mediterranean land mass. It is a n

  17. An overview of biodegradation of LNAPLs in coastal (semi)-arid environment

    NARCIS (Netherlands)

    Yadav, B.K.; Hassanizadeh, S.M.

    2011-01-01

    Contamination of soil and water due to the release of light non-aqueous phase liquids (LNAPLs) is a ubiquitous problem. The problem is more severe in arid and semi-arid coastal regions where most of the petroleum production and related refinery industries are located. Biological treatment of these o

  18. Modeling the distributed effects of forest thinning on the long-term water balance and streamflow extremes for a semi-arid basin in the southwestern US

    Science.gov (United States)

    Moreno, Hernan A.; Gupta, Hoshin V.; White, Dave D.; Sampson, David A.

    2016-03-01

    To achieve water resource sustainability in the water-limited southwestern US, it is critical to understand the potential effects of proposed forest thinning on the hydrology of semi-arid basins, where disturbances to headwater catchments can cause significant changes in the local water balance components and basinwise streamflows. In Arizona, the Four Forest Restoration Initiative (4FRI) is being developed with the goal of restoring 2.4 million acres of ponderosa pine along the Mogollon Rim. Using the physically based, spatially distributed triangulated irregular network (TIN)-based Real-time Integrated Basin Simulator (tRIBS) model, we examine the potential impacts of the 4FRI on the hydrology of Tonto Creek, a basin in the Verde-Tonto-Salt (VTS) system, which provides much of the water supply for the Phoenix metropolitan area. Long-term (20-year) simulations indicate that forest removal can trigger significant shifts in the spatiotemporal patterns of various hydrological components, causing increases in net radiation, surface temperature, wind speed, soil evaporation, groundwater recharge and runoff, at the expense of reductions in interception and shading, transpiration, vadose zone moisture and snow water equivalent, with south-facing slopes being more susceptible to enhanced atmospheric losses. The net effect will likely be increases in mean and maximum streamflow, particularly during El Niño events and the winter months, and chiefly for those scenarios in which soil hydraulic conductivity has been significantly reduced due to thinning operations. In this particular climate, forest thinning can lead to net loss of surface water storage by vegetation and snowpack, increasing the vulnerability of ecosystems and populations to larger and more frequent hydrologic extreme conditions on these semi-arid systems.

  19. Modeling the distributed effects of forest thinning on the long-term water balance and stream flow extremes for a semi-arid basin in the southwestern US

    Directory of Open Access Journals (Sweden)

    H. A. Moreno

    2015-10-01

    Full Text Available To achieve water resources sustainability in the water-limited Southwestern US, it is critical to understand the potential effects of proposed forest thinning on the hydrology of semi-arid basins, where disturbances to headwater catchments can cause significant changes in the local water balance components and basin-wise stream flows. In Arizona, the Four Forest Restoration Initiative (4FRI is being developed with the goal of restoring 2.4 million acres of ponderosa pine along the Mogollon Rim. Using the physically based, spatially distributed tRIBS model, we examine the potential impacts of the 4FRI on the hydrology of Tonto Creek, a basin in the Verde–Tonto–Salt (VTS system, which provides much of the water supply for the Phoenix Metropolitan Area. Long-term (20 year simulations indicate that forest removal can trigger significant shifts in the spatio-temporal patterns of various hydrological components, causing increases in net radiation, surface temperature, wind speed, soil evaporation, groundwater recharge, and runoff, at the expense of reductions in interception and shading, transpiration, vadose zone moisture and snow water equivalent, with south facing slopes being more susceptible to enhanced atmospheric losses. The net effect will likely be increases in mean and maximum stream flow, particularly during El Niño events and the winter months, and chiefly for those scenarios in which soil hydraulic conductivity has been significantly reduced due to thinning operations. In this particular climate, forest thinning can lead to net loss of surface water storage by vegetation and snow pack, increasing the vulnerability of ecosystems and populations to larger and more frequent hydrologic extreme conditions on these semi-arid systems.

  20. An extended modeling approach to assess climate change impacts on groundwater recharge and adaptation in arid areas

    Directory of Open Access Journals (Sweden)

    H. Hashemi

    2014-10-01

    Full Text Available The impact of future climate scenarios on surface and groundwater resources was simulated using a modeling approach for an artificial recharge area in arid southern Iran. Future climate data for the periods of 2010–2030 and 2030–2050 were acquired from the Canadian Global Coupled Model (CGCM 3.1 for scenarios A1B, A2, and B1. These scenarios were adapted to the studied region using the delta-change method. The modified version of the HBV model (Qbox was used to simulate runoff in a flash flood prone catchment. The model was calibrated and validated for the period 2002–2011 using daily discharge data. The projected climate variables were used to simulate future runoff. The rainfall–runoff model was then coupled to a calibrated groundwater flow and recharge model (MODFLOW to simulate future recharge and groundwater hydraulic head. The results of the rainfall–runoff modeling showed that under the B1 scenario the number of floods might increase in the area. This in turn calls for a proper management, as this is the only source of fresh water supply in the studied region. The results of the groundwater recharge modeling showed no significant difference between present and future recharge for all scenarios. Owing to that, four abstraction and recharge scenarios were assumed to simulate the groundwater level and recharged water in the studied aquifer. The results showed that the abstraction scenarios have the most substantial effect on the groundwater level and the continuation of current pumping rate would lead to a groundwater decline by 18 m up to 2050.

  1. Recharge and level change of shallow groundwater within the Lake Qinghai catchment%青海湖流域浅层地下水补给来源及其水位变化

    Institute of Scientific and Technical Information of China (English)

    金章东; 石岳威; 张飞

    2010-01-01

    inland shallow groundwater plays a key role in local drinking, irrigation and regional economic development, especially in semi-arid and arid areas. For the Lake Qinghai catchment, the recharge and table level of shallow groundwater are one of the most important essential factors for land ecology and vegetation conditions and for ongoing ecologic restoration tests on wetland, deserted and grass lands. Through an investigation of shallow groundwater table level in August 2009 and a comparison with that in august 2000, and analyses of hydrogen and oxygen isotopic compositions of shallow groundwater, river and rain water samples, the natural condition of isobaths of shallow groundwater table level within the Lake Qinghai catchment was demonstrated. The data indicate that precipitation is the major recharge source of shallow groundwater whose table levels are affected by precipitation amount and terrain, besides consumption by local residents.%地下水补给来源及水位变化是干旱–半干旱地区生态和植被的主要制约要素之一,也是开展流域生态和环境治理技术与试验示范的关键。通过青海湖流域2000年8月和2009年8月浅层地下水埋深的调查,以及地下水、河水和雨水氢氧同位素分析,揭示了青海湖流域浅层地下水埋深的基本状况,明确了大气降水是青海湖流域浅层地下水的主要补给来源,其水位变化受居民用水量的影响外,主要与降水量、地形密切相关。

  2. Impact of rhizobial populations and their host legumes on microbial activity in soils of arid regions in Tunisia

    Energy Technology Data Exchange (ETDEWEB)

    Fterich, A.; Mahdhi, M.; Mars, M.

    2009-07-01

    Nitrogen fixing legumes and their microsymbionts are a fundamental contributor to soil fertility and prevent their degradation in arid and semi arid ecosystems. In Tunisia, few data are available on the contribution of these legumes in microbial activity in the arid soil. In this objective, a study was undertaken on five leguminous species from different arid regions to evaluate their ability to regenerate microbiological processes of the soil: Genista saharea, Genista microcephala, Acacia tortilis sspr raddiana, Retama raetam and Prosopis stephaniana. (Author)

  3. Attributes for MRB_E2RF1 Catchments by Major River Basins in the Conterminous United States: Bedrock Geology

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This tabular data set represents the area of bedrock geology types in square meters compiled for every catchment of MRB_E2RF1 catchments for Major River Basins...

  4. Climate and Landuse Change Impacts on hydrological processes and soil erosion in a dry Mediterranean agro-forested catchment, southern Portugal

    Science.gov (United States)

    Santos, Juliana; Nunes, João Pedro; Sampaio, Elsa; Moreira, Madalena; Lima, Júlio; Jacinto, Rita; Corte-Real, João

    2014-05-01

    Climate change is expected to increase aridity in the Mediterranean rim of Europe, due to decreasing rainfall and increasing temperatures. This could lead to impacts on soil erosion, since the lower rainfall could nevertheless become concentrated in higher intensity events during the wet season, while the more arid conditions could reduce vegetation cover, also due to climate-induced land-use changes. In consequence, there is an interest in understanding how climate change will affect the interaction between the timing of extreme rainfall events, hydrological processes, vegetation growth, soil cover and soil erosion. To study this issue, the SWAT eco-hydrological model was applied to Guadalupe, an agro-forested catchment (446 ha) located close to the city of Évora, with a Mediterranean inland climate. The landcover is a mix of dispersed cork oak forests ("montado"), annual crops, and agroforesty regions where the cork oaks are associated with crops or pasture; this land cover is representative of the dry regions of southern Portugal and Spain. The catchment has been instrumented since 2011 with a hydrometric station (water discharge and suspended sediment concentration data) and a soil moisture measurement station. There is also observed data of actual evapotranspiration, LAI and biomass production (in pasture; from 1999 and 2008) and runoff data and sediment yield measured in six 16m2 plots. Water balance, vegetation growth, soil erosion and sediment yield in SWAT was calibrated with this dataset. This work will present the dataset, modeling process, results for impacts of climate and land-use change scenarios for vegetation growth, soil erosion and sediment export, considering the climate and socio-economic scenarios A1b and B1 (based on SRES storylines). Climate scenarios were created by statistical downscaling from Global Circulation Models (GCMs) for the period 2071-2100 (30 years). The reference period was 1971-2000 (30 years). The SWAT model was used to

  5. Patterns and Pathways of Evolving Catchment Response in a Medium-Sized Mediterranean Catchment on a Millennium Scale

    Science.gov (United States)

    van Beek, L. P. H.; Bierkens, M. F. P.

    2012-04-01

    The meso-scale landscape dynamics model, CALEROS, has been developed to simulate the interactions between climate, soil production and erosion, vegetation and land use on geomorphological to human time scales in Mediterranean environments. Starting from an initial landscape consisting of a DTM, soil distribution and underlying lithology, the landscape is free to develop in response to the imposed climate variability and seismicity. In addition to changes in soil distribution and bedrock lowering, this includes the establishment of vegetation as conditioned by a selection of plant functional types and, optionally, population and land use dynamics as conditioned by land use scenarios specifying technological and dietary constraints for different periods. As such CALEROS is well-suited to investigate the relative impacts of climate, land cover and human activities on the hydrological catchment response and the associated sediment fluxes due to soil erosion and mass movements. Here we use CALEROS to i) investigate the redistribution of water and sediment across the landscape in a medium-sized Mediterranean catchment (Contrada Maddalena; ~14km2, Calabria, Italy) and ii) to establish patterns of co-evolution in soil properties and vegetation under pristine and anthropogenically impacted conditions on a millennium-scale. Using summary statistics to describe the emergent properties and to verify them against observations, we then delineate areas of uniform morphology and describe the various pathways of development. This information allows us to identify elements of consistent hydrological response and the associated transfer of material across different scales. It also provides essential information on essential feedbacks and the resulting convergence or divergence in landscape development under the impact of climatic or seismic events or human intervention. Although the results are evidently conditioned by the physiographic setting of the study area and by the

  6. On the non-stationarity of hydrological response in anthropogenically unaffected catchments: an Australian perspective

    Science.gov (United States)

    Ajami, Hoori; Sharma, Ashish; Band, Lawrence E.; Evans, Jason P.; Tuteja, Narendra K.; Amirthanathan, Gnanathikkam E.; Bari, Mohammed A.

    2017-01-01

    Increases in greenhouse gas concentrations are expected to impact the terrestrial hydrologic cycle through changes in radiative forcings and plant physiological and structural responses. Here, we investigate the nature and frequency of non-stationary hydrological response as evidenced through water balance studies over 166 anthropogenically unaffected catchments in Australia. Non-stationarity of hydrologic response is investigated through analysis of long-term trend in annual runoff ratio (1984-2005). Results indicate that a significant trend (p < 0.01) in runoff ratio is evident in 20 catchments located in three main ecoregions of the continent. Runoff ratio decreased across the catchments with non-stationary hydrologic response with the exception of one catchment in northern Australia. Annual runoff ratio sensitivity to annual fractional vegetation cover was similar to or greater than sensitivity to annual precipitation in most of the catchments with non-stationary hydrologic response indicating vegetation impacts on streamflow. We use precipitation-productivity relationships as the first-order control for ecohydrologic catchment classification. A total of 12 out of 20 catchments present a positive precipitation-productivity relationship possibly enhanced by CO2 fertilization effect. In the remaining catchments, biogeochemical and edaphic factors may be impacting productivity. Results suggest vegetation dynamics should be considered in exploring causes of non-stationary hydrologic response.

  7. Engaging Dairy Farmers to Improve Water Quality in the Aorere Catchment of New Zealand

    Science.gov (United States)

    Robertson, Jodie; Edgar, Nick; Tyson, Ben

    2013-01-01

    In 2006, dairy farmers in the Aorere Catchment of New Zealand began to investigate allegations that they had a pollution problem affecting the viability of the community's shellfish industry. From 2007 to 2010, the New Zealand Landcare Trust's Aorere Catchment Project (ACP) helped farmers engage in actions to improve conditions in their waterways.…

  8. Prediction of hydrological reduction factor and initial loss in urban surface runoff from small ungauged catchments

    DEFF Research Database (Denmark)

    Arnbjerg-Nielsen, K.; Harremoës, P.

    1996-01-01

    in a catchment for the description of the rain input. A significant variation of the two parameters from one catchment to another has been found and the uncertainty of the two variables are evaluated. The uncertainty of the hydrological reduction factor and the initial loss should be taken into account...

  9. Ecohydrological modelling and integrated management planning in the catchment of the river Dommel

    NARCIS (Netherlands)

    Verkroost, A.W.M.; Olde Venterink, H.; Pieterse, N.M.; Schot, P.P.; Wassen, M.J.

    1998-01-01

    The EU-LIFE Dommel project aims at the development of methods for the combined use of landscape ecological models and socio-economic knowledge in the drawing up of integrated management plans for catchment areas of small trans-border rivers. These methods were developed and tested in the catchment a

  10. GIS-based Approaches to Catchment Area Analyses of Mass Transit

    DEFF Research Database (Denmark)

    Andersen, Jonas Lohmann Elkjær; Landex, Alex

    2009-01-01

    Catchment area analyses of stops or stations are used to investigate potential number of travelers to public transportation. These analyses are considered a strong decision tool in the planning process of mass transit especially railroads. Catchment area analyses are GIS-based buffer and overlay...

  11. Holocene floodplain sediment storage and hillslope erosion within the Rhine catchment

    NARCIS (Netherlands)

    Hoffmann, T.; Erkens, G.; Cohen, K.M.; Houben, P.; Seidel, J.; Dikau, R.

    2007-01-01

    The response of fluvial systems to land use and climate change varies depending on catchment size. While forcing-response mechanisms of small catchments are reasonably well understood, the response of larger drainage basins is less clear. In particular, the impact of land use and climate change on t

  12. Assessing Land Suitability for Rainwater Harvesting Using Geospatial Techniques: A Case Study of Njoro Catchment, Kenya

    Directory of Open Access Journals (Sweden)

    C. W. Maina

    2016-01-01

    Full Text Available Water demand increases as population increases leading to overexploitation of water resource. Consequently, there is need for improved water resources management complemented with rain water harvesting within the catchments. This study sought to assess land suitability for surface runoff harvesting using geospatial techniques. Land use/land cover maps of the area were derived from Landsat image. Land use and soils data were used in generating curve number map of the catchment. Lineaments greatly affect the storage depending on whether runoff is for surface storage or ground water recharge purposes. As a result, ArcGIS was used in delineating the lineaments from Digital Elevation Model (DEM of the catchment. Further, using weighted overlay the catchment was grouped into categories of restricted, not suitable, moderately suitable, suitable, or highly suitable. The study found that forest, agriculture, and built-up areas occupied about 39.42%, 36.32%, and 1.35% of catchment area, respectively. A large part of catchment was found to have curve number range of 82–89. About 50% of the catchment was found to fall within suitable and highly suitable categories. This implied that a great potential exists for rain water harvesting within the catchment.

  13. Catchment & sewer network simulation model to benchmark control strategies within urban wastewater systems

    DEFF Research Database (Denmark)

    Saagi, Ramesh; Flores Alsina, Xavier; Fu, Guangtao

    2016-01-01

    This paper aims at developing a benchmark simulation model to evaluate control strategies for the urban catchment and sewer network. Various modules describing wastewater generation in the catchment, its subsequent transport and storage in the sewer system are presented. Global/local overflow bas...

  14. Design for participation in ecologically sound management of South Africa's Mlazi River Catchment

    NARCIS (Netherlands)

    Auerbach, R.

    1999-01-01

    Without local participation, integrated catchment management and Landcare will not become a general reality in South Africa. With support from the South African Water Research Commission, the University of Natal's Farmer Support Group set up the Ntshongweni Catchment Management Programme (NCMP) as a

  15. Water balance modeling of Upper Blue Nile catchments using a top-down approach

    NARCIS (Netherlands)

    Tekleab, S.; Uhlenbrook, S.; Mohamed, Y.; Savenije, H.H.G.; Temesgen, M.; Wenninger, J.

    2011-01-01

    The water balances of twenty catchments in the Upper Blue Nile basin have been analyzed using a top-down modeling approach based on Budyko’s hypotheses. The objective of this study is to obtain better understanding of water balance dynamics of upper Blue Nile catchments on annual and monthly time sc

  16. Modelling long-term (300ka) upland catchment response to multiple lava damming events

    NARCIS (Netherlands)

    van Gorp, W.; Temme, A. J. A. M.; Veldkamp, A.; Schoorl, J. M.

    2015-01-01

    Landscapes respond in complex ways to external drivers such as base level change due to damming events. In this study, landscape evolution modelling was used to understand and analyse long-term catchment response to lava damming events. PalaeoDEM reconstruction of a small Turkish catchment (45km(2))

  17. Modelling long-term (300¿ka) upland catchment response to multiple lava damming events

    NARCIS (Netherlands)

    Gorp, van W.; Temme, A.J.A.M.; Veldkamp, A.; Schoorl, J.M.

    2015-01-01

    Landscapes respond in complex ways to external drivers such as base level change due to damming events. In this study, landscape evolution modelling was used to understand and analyse long-term catchment response to lava damming events. PalaeoDEM reconstruction of a small Turkish catchment (45¿km2)

  18. The use of GIS and remote sensing for the assessment of waterlogging in the dryland irrigated catchments of Farafra Oasis in Egypt

    Directory of Open Access Journals (Sweden)

    M. El Bastawesy

    2011-12-01

    Full Text Available This paper investigates the interplay of the hydrogeological characteristics, soil properties and recent land reclamation projects on the distribution of waterlogging and salinisation within the Farafra Oasis. The multi-temporal remote sensing data and field observations show that new reclaimed areas have been recently cultivated in distant areas from the old agricultural land. These new cultivations have developed widespread water logging, seepage channels and soil salinisation. Analyses of the Shuttle Radar Topography Mission (SRTM Digital Elevation Model (DEM showed that both old and new agricultural areas are located within same closed drainage basin. The fluvial channels of these catchments, which were developed during wet climatic pluvial have largely been obliterated by the prevailing aridity and often buried under aeolian deposits. However, the new cultivations have been developed on the fingertips of these fluvial channels, while the old fields occupy the low level playas. The soil of the new cultivated areas are mainly lithic with a high calcium carbonate content, thus limiting the downward percolation of excess irrigation water and therefore develop perched water table and seepage through the paleo-channels. The automatically extract drainage networks from DEM are resembling fluvial patterns and coincide with the seepage channels slowly heading toward old cultivation. The inactive alluvial channels and landforms have to be considered when planning for new cultivation in dryland catchments to better control waterlogging and salinisation hazard. It is highly recommended that newly developed seepage-channels have to be detected and intercepted before reaching old agriculture areas. Therefore, the "dry-drainage" concept can be implemented as the seepage water can be conveyed into a nearby playas reserved for evaporation.

  19. THE FORMATION OF THE OUTFLOW IN THE URBANISED CATCHMENT AREA ON THE EXAMPLE OF THE CATCHMENT OF STRZYŻA

    OpenAIRE

    Magda Sikora; Roman Cieśliński

    2015-01-01

    The aim of the study is to determine what influence made various forms of land use of catchment area on the size and variability of the outflow. Linking the flow rate with the forms of land use will determine which factors affect the runoff in the basin. The object of the research is Strzyża river basin situated within the administrative boundaries of the city of Gdańsk. It was found that streams flowing through urban areas, including the city of Gdańsk (river Strzyża), quickly react to any e...

  20. Investigating the water balance of on-farm techniques for improved crop productivity in rainfed systems: A case study of Makanya catchment, Tanzania

    Science.gov (United States)

    Makurira, H.; Savenije, H. H. G.; Uhlenbrook, S.; Rockström, J.; Senzanje, A.

    Water scarcity is a perennial problem in sub-Saharan agricultural systems where extreme rainfall events dominate agricultural seasons. Dry spell occurrences between and during seasons negatively impact on crop yields especially if such dry spells exceed 14 days. The impact of dry spells is felt more at smallholder farming scales where subsistence farming is the only source of livelihood for many households. This paper presents results from on-going research to improve rainfed water productivity in arid and semi-arid regions. The study site is the Makanya catchment in northern Tanzania where rainfall rarely exceeds 400 mm/season. Rainwater alone is not sufficient to support maize which is the preferred crop. The research introduced new soil and water conservation measures to promote water availability into the root zone. The introduced techniques include deep tillage, runoff diversion, fanya juus (infiltration trenches with bunds) and infiltration pits. The research aims at understanding the effectiveness of these interventions in increasing moisture availability within the root zone. Time domain reflectometry (TDR) was used to measure soil moisture twice weekly at 10 cm depth intervals up to depths of 2 m. Soil moisture fluctuated in the range 5-25% of volume with the beginning of the season recording the driest moisture levels and periods after good rainfall/runoff events recording the highest moisture levels. From the field observations made, a spreadsheet model was developed to simulate soil moisture variations during different maize growth stages. The results obtained show that the zones of greatest soil moisture concentrations are those around the trenches and bunds. Soil moisture is least at the centre of the plots. The study confirms the effectiveness of the introduced techniques to help concentrate the little available rainfall into green water flow paths. Indirect benefits from these improved techniques are the creation of fertile and moist zones around

  1. Advancing Land-Sea Conservation Planning: Integrating Modelling of Catchments, Land-Use Change, and River Plumes to Prioritise Catchment Management and Protection.

    Science.gov (United States)

    Álvarez-Romero, Jorge G; Pressey, Robert L; Ban, Natalie C; Brodie, Jon

    2015-01-01

    Human-induced changes to river loads of nutrients and sediments pose a significant threat to marine ecosystems. Ongoing land-use change can further increase these loads, and amplify the impacts of land-based threats on vulnerable marine ecosystems. Consequently, there is a need to assess these threats and prioritise actions to mitigate their impacts. A key question regarding prioritisation is whether actions in catchments to maintain coastal-marine water quality can be spatially congruent with actions for other management objectives, such as conserving terrestrial biodiversity. In selected catchments draining into the Gulf of California, Mexico, we employed Land Change Modeller to assess the vulnerability of areas with native vegetation to conversion into crops, pasture, and urban areas. We then used SedNet, a catchment modelling tool, to map the sources and estimate pollutant loads delivered to the Gulf by these catchments. Following these analyses, we used modelled river plumes to identify marine areas likely influenced by land-based pollutants. Finally, we prioritised areas for catchment management based on objectives for conservation of terrestrial biodiversity and objectives for water quality that recognised links between pollutant sources and affected marine areas. Our objectives for coastal-marine water quality were to reduce sediment and nutrient discharges from anthropic areas, and minimise future increases in coastal sedimentation and eutrophication. Our objectives for protection of terrestrial biodiversity covered species of vertebrates. We used Marxan, a conservation planning tool, to prioritise interventions and explore spatial differences in priorities for both objectives. Notable differences in the distributions of land values for terrestrial biodiversity and coastal-marine water quality indicated the likely need for trade-offs between catchment management objectives. However, there were priority areas that contributed to both sets of objectives. Our

  2. Hydrochemical heterogeneity in an upland catchment: further characterisation of the spatial, temporal and depth variations in soils, streams and groundwaters of the Plynlimon forested catchment, Wales

    Directory of Open Access Journals (Sweden)

    P. Shand

    2005-01-01

    Full Text Available The heterogeneous nature of upland hard-rock catchments in terms of geology, geomorphology, superficial deposits, soil type and land use gives rise to a range of hydrochemical characteristics in stream waters. This is further complicated by the large and often rapid changes in stream flow typical of storm events. The sources of solutes and flow pathways in hard-rock catchments are still poorly understood, in particular the role of bedrock groundwater. Spatial variations in water chemistry are presented for stream waters, soils and groundwaters in the forested Plynlimon catchment of Wales, UK. The results highlight a large degree of spatial heterogeneity in each of these systems. This has major implications for the application of end-member mixing analysis and presents serious problems for modelling in scaling up from study sites to catchment scale. However, such data provide important constraints on sources, flow pathways and residence times within individual catchment compartments, knowledge of which is essential for understanding how such catchments function. The characterisation of sub-surface waters in upland catchments requires a great deal of care during sampling as well as high spatial and temporal resolution of sampling, and further work is required to characterise the Plynlimon catchments fully. Nevertheless, the presence of an active and highly stratified groundwater system is considered important as a source of solutes and water to streams. It also provides a storage medium that is likely to make a major contribution to explaining the strongly damped rainfall Cl and d2H signals measured in the streams.

  3. Spatial and temporal patterns of off-slope sediment delivery for small catchments subject to shallow landslides within the Waipaoa catchment, New Zealand

    Science.gov (United States)

    Jones, Katie E.; Preston, Nicholas J.

    2012-03-01

    The Waipaoa catchment in New Zealand has one of the highest measured specific suspended sediment yields measured in New Zealand compared to basins of comparable size. A significant source of this sediment is from shallow landslides which are often triggered on a regional scale during large magnitude storm events, defined as ~ 200 mm rainfall within 72 h. The first step of this sediment cascade is removal of landslide material from the slope and into the fluvial system when the debris tail is in physical contact and hence considered connected. The difference between the volume of sediment liberated in the event and the volume remaining on the slope immediately following the event is termed the off-slope sediment delivery ratio. This value ranged from 0.12 to 0.28 for small sub-catchments within the Waipaoa catchment depending on catchment morphology, landslide and triggering event characteristics. In the Waipaoa catchment a decrease in the catchment sediment delivery ratio is observed as the sub-catchment size increased. A human induced process which may affect off-slope sediment delivery is regolith exhaustion, as scars move further upslope in response to removal of preferred weathered material during previous events on the lower sections of slope. However, it appears that temporal scar migration away from the channels is not prevalent. Therefore, the hypothesis that hillslope relaxation since deforestation is prevalent in this setting is considered null. Rather the temporal pattern to sediment delivery ratios supports the context of evolving catchment in response to deforestation in the Terrain Event Resistance Model.

  4. Dynamically Evolving Models for Dynamic Catchments: Application of the Locally Linear Dual EnKF to a Catchment with Land Use Change

    Science.gov (United States)

    Pathiraja, S. D.; Marshall, L. A.; Sharma, A.; Moradkhani, H.

    2015-12-01

    Catchments are dynamic, constantly undergoing change be it naturally or due to anthropogenic influences. Changes in land surface conditions such as disturbance due to bushfire or erosion, urbanisation, deforestation or afforestation will affect a catchment's hydrologic regime. Models calibrated to pre-change conditions will lead to biased streamflow predictions, unless the change is explicitly accounted for in the model. A modelling methodology that is capable of adjusting its form (for instance, through time varying parameters) as catchments undergo change is therefore needed. We developed a framework for automatically and objectively detecting time variations in model parameters using Data Assimilation. The so called Locally Linear Dual EnKF was previously tested against a range of synthetic case studies and shown to reproduce known temporal variations from assimilating streamflow observations only. In this study, we apply the Locally Linear Dual EnKF to the Wights and Salmon paired catchments in Western Australia. Both were initially forested and monitored for a 3 year period, after which Wights was fully cleared whilst Salmon remained unchanged. The lumped conceptual hydrologic model (PDM) was calibrated over the stationary period and the optimal parameterisation used to initialise the Locally Linear Dual EnKF. Resultant parameter trajectories for the Salmon catchment were relatively stationary, whilst parameters for the Wights catchment were automatically adjusted to produce greater flood peaks, sooner after rainfall, consistent with observations. A significant improvement in both streamflow prediction and catchment soil moisture was obtained with the Locally Linear Dual EnKF, compared to the time invariant parameter case. This application has demonstrated the usefulness of this framework for improving predictions in rapidly changing catchments.

  5. Risk of fire occurrence in arid and semi-arid ecosystems of Iran: an investigation using Bayesian belief networks.

    Science.gov (United States)

    Bashari, Hossein; Naghipour, Ali Asghar; Khajeddin, Seyed Jamaleddin; Sangoony, Hamed; Tahmasebi, Pejman

    2016-09-01

    Identifying areas that have a high risk of burning is a main component of fire management planning. Although the available tools can predict the fire risks, these are poor in accommodating uncertainties in their predictions. In this study, we accommodated uncertainty in wildfire prediction using Bayesian belief networks (BBNs). An influence diagram was developed to identify the factors influencing wildfire in arid and semi-arid areas of Iran, and it was populated with probabilities to produce a BBNs model. The behavior of the model was tested using scenario and sensitivity analysis. Land cover/use, mean annual rainfall, mean annual temperature, elevation, and livestock density were recognized as the main variables determining wildfire occurrence. The produced model had good accuracy as its ROC area under the curve was 0.986. The model could be applied in both predictive and diagnostic analysis for answering "what if" and "how" questions. The probabilistic relationships within the model can be updated over time using observation and monitoring data. The wildfire BBN model may be updated as new knowledge emerges; hence, it can be used to support the process of adaptive management.

  6. Modelling (flash) floods in a Dutch lowland catchment

    Science.gov (United States)

    Brauer, C. C.; Teuling, A. J.; Overeem, A.; van der Velde, Y.; Hazenberg, P.; Warmerdam, P. M. M.; Kloosterman, P.; Uijlenhoet, R.

    2012-04-01

    On 26 August 2010 the eastern part of The Netherlands and the bordering part of Germany were struck by a series of rainfall events. We investigated the unprecedented flash flood triggered by this exceptionally heavy rainfall event (return period > 1000 years) in the 6.5 km2 Hupsel Brook catchment, which has been the experimental watershed employed by Wageningen University since the 1960s. This study improved our understanding of the dynamics of such lowland flash floods and the results have been published in HESS (Brauer et al., 2011). During this extreme event some thresholds became apparent that do not play a role during average conditions and are not incorporated in rainfall-runoff models. We present a detailed analysis of this extreme event, focusing on (1) the measured soil moisture, groundwater and discharge response of the catchment, (2) the thresholds we found, (3) the manner in which these processes and thresholds are incorporated in some well-known conceptual hydrological models and (4) how well these models are able to simulate the rainfall-runoff processes during the 2010 flash flood.

  7. IMAGERY: A CASE STUDY IN KAYANGAN CATCHMENT AREA, YOGYAKARTA, INDONESIA

    Directory of Open Access Journals (Sweden)

    Ratih Fitria Putri

    2013-01-01

    Full Text Available The differential synthetic aperture radar in terferometry (DInSAR technique is applied to the ALOS PALSAR data to observe su rface displacement in Kayangan catchment area, Yogyakarta, Indonesia. Change detecti on is implemented to extract information on several landslides that occurred in the region in a time span between 2007 and 2009. The advanced DInSAR processing of im ages (2007–2009 has shown slight surface movements before the landslide events. These results are compared and validated with available GPS measurements. Our analysis reveals that Kayangan catchment area exhibits clear indication of surface displacements varying from 5.2 to 57.9 cm/year. The occurence of landslides has been analy zed in relation to the following terrain parameters; elevation, slope, distance to stream network, geology, landuse, and distance from road. Among these factors, it is found that 18% of landslides occur in elevation >100 m, 56% in slope 30–40°, 34% in <25 m distance to stream networks, 100% in kebobutak formation, 67% in mix garden of land use types, and 100% in <25 m distance from road. The landuse is the most in fluential factor, since there are only four types of landuse that can lead to lands lide occurrence, i.e., mixed garden, dryland agriculture, bush, and settlement. The analys is of land deformation is promising for assessing acceleration caused by a destabilizing anthropogenic change, and relationship between seasonal precipitation a nd deformation variability.

  8. Spatial Modelling of Sediment Transport over the Upper Citarum Catchment

    Directory of Open Access Journals (Sweden)

    Poerbandono

    2006-05-01

    Full Text Available This paper discusses set up of a spatial model applied in Geographic Information System (GIS environment for predicting annual erosion rate and sediment yield of a watershed. The study area is situated in the Upper Citarum Catchment of West Java. Annual sediment yield is considered as product of erosion rate and sediment delivery ratio to be modelled under similar modeling tool. Sediment delivery ratio is estimated on the basis of sediment resident time. The modeling concept is based on the calculation of water flow velocity through sub-catchment surface, which is controlled by topography, rainfall, soil characteristics and various types of land use. Relating velocity to known distance across digital elevation model, sediment resident time can be estimated. Data from relevance authorities are used. Bearing in mind limited knowledge of some governing factors due to lack of observation, the result has shown the potential of GIS for spatially modeling regional sediment transport. Validation of model result is carried out by evaluating measured and computed total sediment yield at the main outlet. Computed total sediment yields for 1994 and 2001 are found to be 1.96×106 and 2.10×106tons/year. They deviate roughly 54 and 8% with respect to those measured in the field. Model response due to land use change observed in 2001 and 1994 is also recognised. Under presumably constant rainfall depth, an increase of overall average annual erosion rate of 11% resulted in an increase of overall average sediment yield of 7%.

  9. Assessing pesticide exposure of the aquatic environment in tropical catchments

    Science.gov (United States)

    Weiss, Frederik; Zurbrügg, Christian; Eggen, Rik; Castillo, Luisa; Ruepert, Clemens; Stamm, Christian

    2015-04-01

    Today, pesticides are intensively used in agriculture across the globe. Worldwide about 2.4×106 tons of pesticides are used annually on 1.6×109 ha of arable land. This yields a global average use of pesticides of 1.53 kg ha-1 year-1. Available data suggest that the use in the agricultural sector will continue to grow. Recently it was estimated that within the last decade, the world pesticide market increased by 93% and the Brazilian market alone by 190%. Though pesticides are intensively used in many low and middle income countries (LAMICs), scientifically sound data of amounts and types of pesticide use and the resulting impact on water quality are lacking in many of these countries. Therefore it is highly relevant to: i) identify risk areas where pesticides affect environmental health, ii) understand the environmental behavior of pesticides in vulnerable tropical ecosystems; and iii) develop possible mitigation options to reduce their exposure to ecosystems and humans. Here we present a project that will focus on assessing pesticide exposure of the aquatic environment and humans in tropical catchments of LAMICs. A catchment in the Zarcero province in Costa Rica will be the test case. Pesticide exposure will be assessed by passive sampling. In order to cover a broad range of compounds of possible use, two sampling devices will be used: SDB membranes for collecting polar compounds and silicon sheets for accumulating apolar pesticides. Extracts will be subsequently analysed by GC-MSMS and LC-HRMS.

  10. Forest fire impact on the hydrological response in small catchment of NW Spain

    Directory of Open Access Journals (Sweden)

    J. Canceio-González

    2013-05-01

    Full Text Available Hydrological studies were carried out in two catchments (burnt and unburned, to determine the processes related to the streamflow changes and the possible effects on the runoff coefficients produced by a forest fire in the summer of 2007, which affected 50% of the area of one of the catchments. Comparative analysis of the changes in the monthly streamflow values revealed that during the wettest months, the runoff was higher in the burnt catchment during the first two years, and was very similar in both catchments during the third year. Calculation of the annual runoff coefficient confirmed these findings and showed that the differences between the coefficients in the catchments were negligible in the final year. In both cases, this can be explained by regeneration of the vegetation after fire.

  11. A Vector-based Method for the Extraction of Catchment from Grid DEMs

    Institute of Scientific and Technical Information of China (English)

    ZHU Qing; TIAN Yixiang

    2005-01-01

    The methodology of catchment extraction especially from regular grid digital elevation models (DEMs) is briefly reviewed.Then an efficient algorithm, which combines vector process and traditional neighbourhood raster process, is designed for extracting the catchments and subcatchments from depressionless DEMs.The catchment area of each river in the grid DEM data is identified and delineated, then is divided into subcatchments as required.Compared to traditional processes, this method for identifying catchments focuses on the boundaries instead of the area inside the catchments and avoids the boundary intersection phenomena.Last, the algorithm is tested with a set of DEMs of different sizes, and the result proves that the computation efficiency and accuracy are better than existent methods.

  12. Dissolved nutrient exports from natural and human-impacted Neotropical catchments

    DEFF Research Database (Denmark)

    Gücker, Björn; Silva, Ricky C. S.; Graeber, Daniel

    2016-01-01

    Aim Neotropical biomes are highly threatened by land-use changes, but the catchment-wide biogeochemical effects are poorly understood. Here, we aim to compare exports of dissolved nitrogen (N) and phosphorus (P) from natural and human-impacted catchments in the Neotropics. Location Neotropics....... Methods We measured streamwater nutrient concentrations and exports in 20 south-eastern Brazilian catchments with different land uses (natural Cerrado/semi-deciduous forest, pasture, intensive agriculture and urban areas) and conducted a meta-analysis on nutrient exports from Neotropical catchments, both...... natural and human-impacted. Results Organic forms dominated dissolved nutrient exports in central/south-east Brazil in both natural and human-dominated catchments. Our meta-analysis suggests that there is wide geographic variability in the natural dominance of organic versus inorganic nutrient exports...

  13. Examining the effects of forest thinning on hydrological processes at different catchment scales in forested headwater

    Science.gov (United States)

    Dung, Bui Xuan; Gomi, Takashi; Onda, Yuichi; Kato, Hiroaki; Hiraoka, Marino

    2013-04-01

    We conducted field observation in nested headwater catchments draining Japanese cypress (Chamaecyparis obtusa) and cedar (Cryptomeria japonica) forests at Tochigi prefecture for examining the effects of forest thinning on hydrological processes at different catchment scales. 50% of the stems was removed with line thinning in catchment K2 (treatment catchment), while catchment K3 remained untreated as a control. We monitored nested catchment within K2-1 (17.1 ha) as K2-2 (10.2 ha), K2-3 (3.7 ha) and K2-4 (5.1 ha), and within K3-1 (8.9 ha) as K3-2 (3.0 ha). Runoff from the catchments was monitored during the pre-thinning (from April, 2010 to May 2011), and the post-thinning periods (from June 2011 to December 2012). Paired-catchment and hydrograph separation analysis were used to evaluate the effects of forest thinning on hydrological processes at different catchment scales. We developed the pre-thinning calibration equation for predicting post-thinning behaviors. Paired catchment analysis revealed that annual catchment runoff increased 648 mm in K2-1, 414 mm in K2-2, 528 mm in K2-3, and 566 mm in K2-4 during the post-thinning period. Greater increase of flow in largest catchment (K2-1) was be due to the contribution of increased delayed flow from infiltrated water, reappearing as surface flow (i.e., quick flow) in the lower parts of the catchment, caused by harvested activities (logging, road, skid trail). Because both quick and delayed flows increased significantly in the larger catchments of K2-1 and K2-2, while only delayed flow of smaller catchments (K2-3 and K2-4) increased significantly during the post-thinning period. Delayed flow also increased greater in K2-3 and K2-4, smaller in K2-2 but greatest in K2-1. Moreover, the increasing contributions to runoff from deeper groundwater sources that are recharged in upslope subcatchments caused increase amount of flow. This was explained when increase of annual base flow (i.e., bedrock flow) of zero-order catchments

  14. Impermeability and Mining Impacts of Key Aquifuges for Shallowly Buried Coal Seams%浅埋煤层关键隔水层隔水性能及采动影响变化

    Institute of Scientific and Technical Information of China (English)

    蒋泽泉; 王建文; 王宏科

    2011-01-01

    The mining of shallowly buried coal seams has brought a series of ecological environmental problems; water conservation coal mining is the key issue in coal resource scientific mining in the northern Shaanxi and even whole Northwest China. Taking the Shennan mining area as an example, the paper studied impermeabilities of loess and red loam aquifuges and mining impacts on them.Coal seams in water conservation mining are covered with clay and sands; the overlying clay is the crucial aquifuge. Laboratory and field tests have demonstrated that: after the overlying clay is disturbed, water inflow will soar to rise rapidly and form fissure flow, that is went against to water conservation coal mining. When loess is subjected to the ground surface tension fissure developed shearing will be in broken state, permeability coefficient variation will appear as some orders of magnitude after mining; while the red loam is stand in the integral settlement zone, subjected to additional stress and is indicative of greater plastic deformation, permeability is reduced after mining, thus in favor of water conservation coal mining. To realize water conservation coal mining and keep clay bed undisturbed integrally, gob area stowing is advised to control surface subsidence and soil mass confining pressure. When surface subsidence is reduced, loess bed can keep undisturbed, and confining stress is existed, clay bed stability can also be kept.%陕北浅埋煤层开采引起了一系列的生态环境问题,保水采煤成为陕北乃至整个西北地区煤炭资源科学开采的关键.以神南矿区为例,研究了黄土、红土隔水层的隔水性及采煤对其隔水性的影响.神南矿区砂土基型煤层的保水开采的关键隔水层为上覆粘土层,室内、外试验显示:粘土层失稳后流量猛增形成裂隙流,不利于保水采煤;黄土受地面张裂隙发育的剪切作用处于破碎状态,采动后渗透系数表现为数个数量级的变化;红土处于

  15. An Integrated Lowland Catchment Model for the Upper Narew

    Science.gov (United States)

    Romanowicz, R.; Osuch, M.; Kiczko, A.; Napiórkowski, J. J.

    2009-04-01

    The aim of this work is the development of an integrated Data Based Mechanistic (DBM) rainfall-flow and flow-routing model suitable for scenario analysis of the Upper River Narew catchment in northeast Poland. This area encloses valuable wetland ecosystems of the Narew National Park (NPN). The available data include daily rainfall observations, temperature measurements and water level measurements at 7 gauging stations situated along the river reach and its tributaries (Bondary, Narewka, Narew, Ploski, Chraboły, Suraż and Żółtki). The modelling tool developed is formulated in MATLAB-SIMULINK language. It has a flexible, modular structure that can easily be extended by adding new features, such as a snow-melt module or a distributed routing module. The basic system structure includes rainfall-flow and flow routing modules, based on a Stochastic Transfer Function (STF) approach combined with nonlinear transformation of rainfall into effective rainfall. Most of the identified routing models have first-order dynamics. The best results were obtained for the neighbouring sub-reaches and there was no significant improvement of model performance if separate parallel inputs were used instead of an average sum. This result indicates that inflows from tributaries are highly cross-correlated. Moreover, there are many tributaries unaccounted for along the river, which change our perception of the flow dynamics at the downstream reach. Therefore, even though the flood peak travels in about 4-5 days from upstream to downstream (Bondary to Żółtki), the maximum advective delay obtained for the Suraż model with averaged flows from Bondary, Narewka and Orlanka on the input equals only 1 day. This model and the similar MISO model using parallel inputs are the only models suitable for flood forecasting. Models obtained without advective delay may be useful for scenario analysis. The STF models derived to describe the rainfall-flow processes in the sub-catchments of Narewka and

  16. Microbial source tracking and transfer hydrodynamics in rural catchments.

    Science.gov (United States)

    Murphy, Sinead; Bhreathnach, Niamh; O'Flaherty, Vincent; Jordan, Philip; Wuertz, Stefan

    2013-04-01

    In Ireland, bacterial pathogens from continual point source pollution and intermittent pollution from diffuse sources can impact both drinking water supplies and recreational waters. This poses a serious public health threat. Observing and establishing the source of faecal pollution is imperative for the protection of water quality and human health. Traditional culture methods to detect such pollution via faecal indicator bacteria have been widely utilised but do not decipher the source of pollution. To combat this, microbial source tracking, an important emerging molecular tool, is applied to detect host-specific markers in faecally contaminated waters. The aim of this study is to target ruminant and human-specific faecal Bacteroidales and Bacteroides 16S rRNA genes within rural river catchments in Ireland and investigate hydrological transfer dependencies. During storm events and non-storm periods, 1L untreated water samples, taken every 2 hours over a 48-hour time period at the spring (Cregduff) or outlet (Dunleer), and large (5-20L) untreated water samples were collected from two catchment sites. Cregduff is a spring emergence under a grassland karst landscape in Co. Mayo (west coast of Ireland) and Dunleer is a mixed landuse over till soils in Co. Louth (east coast). From a risk assessment point of view, the catchments are very different. Samples were filtered through 0.2µm nitrocellulose filters to concentrate bacterial cells which then underwent chemical extraction of total nucleic acids. Animal and human stool samples were also collected from the catchments to determine assay sensitivity and specificity following nucleic acid extraction. Aquifer response to seasonal events was assessed by monitoring coliforms and E. coli occurrence using the IDEXX Colisure® Quanti Tray®/2000 system in conjunction with chemical and hydrological parameters. Autoanalysers deployed at each catchment monitor multiple water parameters every 10 min such as phosphorus, nitrogen

  17. Hydrologic comparison between a lowland catchment (Kielstau, Germany and a mountainous catchment (XitaoXi, China using KIDS model in PCRaster

    Directory of Open Access Journals (Sweden)

    N. Fohrer

    2009-08-01

    Full Text Available The KIDS model (Kielstau Discharge Simulation model is a simple rainfall-runoff model developed originally for the Kielstau catchment. To extend its range of application we applied it to a completely different catchment, the XitaoXi catchment in China. Kielstau is a small (51 km2 lowland basin in Northern Germany, with large proportion of wetland area. And XitaoXi is a mesoscale (2271 km2 mountainous basin in the south of China. Both catchments differ greatly in size, topography, landuse, soil properties, and weather conditions. We compared two catchments in these features and stress on the analysis how the specific catchment characteristics could guide the adaptation of KIDS model and the parameter estimation for streamflow simulation. The Nash and Sutcliffe coefficient was 0.73 for Kielstau and 0.65 for XitaoXi. The results suggest that the application of KIDS model may require adjustments according to the specific physical background of the study basin.

  18. Groundwater as an emergency source for drought mitigation in the Crocodile River catchment, South Africa

    Directory of Open Access Journals (Sweden)

    F. E. F. Mussá

    2014-03-01

    and environmental damages to the society. In this study, we assess the drought intensity and severity and the groundwater potential to be used as a supplement source of water to mitigate drought impacts in the Crocodile River catchment, a water-stressed sub-catchment of the Incomati River catchment in South Africa. The research methodology consists mainly of three parts. First, the spatial and temporal variation of the meteorological and hydrological drought severity and intensity over the catchment were evaluated. The Standardized Precipitation Index (SPI was used to analyse the meteorological drought and the Standardized Runoff Index (SRI was used for the hydrological drought. Second, the water deficit in the catchment during the drought period was computed using a simple water balance method. Finally, a groundwater model was constructed in order to assess the feasibility of using groundwater as an emergency source for drought impact mitigation. Results show that the meteorological drought severity varies accordingly with the precipitation; the low rainfall areas are more vulnerable to severe meteorological droughts (lower and upper crocodile. Moreover, the most water stressed sub-catchments with high level of water uses but limited storage, such as the Kaap located in the middle catchment and the Lower Crocodile sub-catchments are those which are more vulnerable to severe hydrological droughts. The analysis of the potential groundwater use during droughts showed that a deficit of 97 Mm3 yr−1 could be supplied from groundwater without considerable adverse impacts on the river base flow and groundwater storage. Abstraction simulations for different scenarios of extremely severe droughts reveal that it is possible to use groundwater to cope with the droughts in the catchment. However, local groundwater exploitation in Nelspruit and White River sub-catchment will cause large drawdowns (> 10 m and high base flow reduction (> 20%. This case study shows that

  19. Catchment modeling and model transferability in upper Blue Nile Basin, Lake Tana, Ethiopia

    Directory of Open Access Journals (Sweden)

    A. S. Gragne

    2008-03-01

    Full Text Available Understanding spatial and temporal distribution of water resources has an important role for water resource management. To understand water balance dynamics and runoff generation mechanisms at the Gilgel Abay catchment (a major tributary into lake Tana, source of Blue Nile, Ethiopia and to evaluate model transferability, catchment modeling was conducted using the conceptual hydrological model HBV. The catchment of the Gigel Abay was sub-divided into two gauged sub-catchments (Upper Gilgel Abay, UGASC, and Koga, KSC and one ungauged sub-catchment.

    Manual calibration of the daily models for three different catchment representations (CRs: (i lumped, (ii lumped with multiple vegetation zones, and (iii semi-distributed with vegetations zone and elevation zones, showed good to satisfactory model performance (Nash-Sutcliffe efficiency values, Reff>0.75 and >0.6, respectively, for UGASC and KSC. The change of the time step to fifteen and thirty days resulted in very good model performances in both sub-catchments (Reff>0.8. The model parameter transferability tests conducted on the daily models showed poor performance in both sub-catchments, whereas the fifteen and thirty days models yielded high Reff values using transferred parameter sets. This together with the sensitivity analysis carried out after Monte Carlo simulations (1 000 000 model runs per CR explained the reason behind the difference in hydrologic behaviors of the two sub-catchments UGASC and KSC. The dissimilarity in response pattern of the sub-catchments was caused by the presence of dambos in KSC and differences in the topography between UGASC and KSC. Hence, transferring model parameters from the view of describing hydrological process was found to be not feasible for all models. On the other hand, from a water resources management perspective the results obtained by transferring parameters of the larger time step model were

  20. Isotopic fingerprints in a nested catchment setup with contrasting landscape properties

    Science.gov (United States)

    Klaus, Julian; Pfister, Laurent

    2016-04-01

    Physiographic characteristics control how catchments store, mix, and release water. These catchment properties, together with the hydro-meteorological conditions, also influence the transformation of the stable isotopic signal from precipitation to stream discharge. Several studies showed that catchments often exhibit a lower slope of the regression line between δOxygen-18 and δDeuterium of streamwater (Stream Evaporation Water Lines: SEWL) compared to the Local Meteoric Water Line (LMWL). We hypothesise that the combination of land use, geology, and topography is controlling the differences between the LMWL and SEWL. We test this in the nested river setup of the Attert catchment (250 sqkm), with 9 sub-catchment ranging from 0.45 sqkm to 161 sqkm. The different sub-catchments show remarkable different catchment characteristics in terms of geology and land use, while the hydro-meteorological forcing is rather uniform between the sub-catchments. We found that an elevation effect strongly controls the differences in mean δOxygen-18 and δDeuterium of streamflow between the catchments (-1.2‰ δD/100 m). Streamflow also shows remarkable evaporative enrichment, the slopes of the SEWL ranges from 3.2 to 5.1. Increasing fractions of sandstone geology and forest cover generally lead to lower slopes of the SEWL, while the extent of alluvial floodplain leads to slopes more similar to the MEWL. This contribution shows how different catchment properties influence the relationship δOxygen-18 and δDeuterium that is generally controlled by non-kinetic fractionation. Further work on the processes that lead to different slopes of the SEWL is needed.

  1. Permafrost conditions in peatlands regulate magnitude, timing, and chemical composition of catchment dissolved organic carbon export.

    Science.gov (United States)

    Olefeldt, David; Roulet, Nigel T

    2014-10-01

    Permafrost thaw in peatlands has the potential to alter catchment export of dissolved organic carbon (DOC) and thus influence downstream aquatic C cycling. Subarctic peatlands are often mosaics of different peatland types, where permafrost conditions regulate the hydrological setting of each type. We show that hydrological setting is key to observed differences in magnitude, timing, and chemical composition of DOC export between permafrost and nonpermafrost peatland types, and that these differences influence the export of DOC of larger catchments even when peatlands are minor catchment components. In many aspects, DOC export from a studied peatland permafrost plateau was similar to that of a forested upland catchment. Similarities included low annual export (2-3 g C m(-2) ) dominated by the snow melt period (~70%), and how substantial DOC export following storms required wet antecedent conditions. Conversely, nonpermafrost fens had higher DOC export (7 g C m(-2) ), resulting from sustained hydrological connectivity during summer. Chemical composition of catchment DOC export arose from the mixing of highly aromatic DOC from organic soils from permafrost plateau soil water and upland forest surface horizons with nonaromatic DOC from mineral soil groundwater, but was further modulated by fens. Increasing aromaticity from fen inflow to outlet was substantial and depended on both water residence time and water temperature. The role of fens as catchment biogeochemical hotspots was further emphasized by their capacity for sulfate retention. As a result of fen characteristics, a 4% fen cover in a mixed catchment was responsible for 34% higher DOC export, 50% higher DOC concentrations and ~10% higher DOC aromaticity at the catchment outlet during summer compared to a nonpeatland upland catchment. Expansion of fens due to thaw thus has potential to influence landscape C cycling by increasing fen capacity to act as biogeochemical hotspots, amplifying aquatic C cycling, and

  2. Proximate and ultimate controls on carbon and nutrient dynamics of small agricultural catchments

    Science.gov (United States)

    Thomas, Zahra; Abbott, Benjamin W.; Troccaz, Olivier; Baudry, Jacques; Pinay, Gilles

    2016-03-01

    Direct and indirect effects from human activity have dramatically increased nutrient loading to aquatic inland and estuarine ecosystems. Despite an abundance of studies investigating the impact of agricultural activity on water quality, our understanding of what determines the capacity of a watershed to remove or retain nutrients remains limited. The goal of this study was to identify proximate and ultimate controls on dissolved organic carbon and nutrient dynamics in small agricultural catchments by investigating the relationship between catchment characteristics, stream discharge, and water chemistry. We analyzed a 5-year, high-frequency water chemistry data set from three catchments in western France ranging from 2.3 to 10.8 km2. The relationship between hydrology and solute concentrations differed between the three catchments and was associated with hedgerow density, agricultural activity, and geology. The catchment with thicker soil and higher surface roughness had relatively invariant carbon and nutrient chemistry across hydrologic conditions, indicating high resilience to human disturbance. Conversely, the catchments with smoother, thinner soils responded to both intra- and interannual hydrologic variation with high concentrations of phosphate (PO43-) and ammonium (NH4+) in streams during low flow conditions and strong increases in dissolved organic carbon (DOC), sediment, and particulate organic matter during high flows. Despite contrasting agricultural activity between catchments, the physical context (geology, topography, and land-use configuration) appeared to be the most important determinant of catchment solute dynamics based on principle components analysis. The influence of geology and accompanying topographic and geomorphological factors on water quality was both direct and indirect because the distribution of agricultural activity in these catchments is largely a consequence of the geologic and topographic context. This link between inherent

  3. Estimation of nitrogen budgets for contrasting catchments at the landscape scale

    Directory of Open Access Journals (Sweden)

    E. Vogt

    2013-01-01

    Full Text Available A comprehensive assessment of nitrogen (N flows at the landscape scale is fundamental to understand spatial interactions in the N cascade and to inform the development of locally optimised N management strategies. To explore these interactions, complete N budgets were estimated for two contrasting hydrological catchments (dominated by agricultural grassland vs. semi-natural peat-dominated moorland, forming part of an intensively studied landscape in southern Scotland. Local scale atmospheric dispersion modelling and detailed farm and field inventories provided high resolution estimations of input fluxes. Direct agricultural inputs (i.e. grazing excreta, N2 fixation, organic and synthetic fertiliser accounted for most of the catchment N inputs, representing 82% in the grassland and 62% in the moorland catchment, while atmospheric deposition made a significant contribution, particularly in the moorland catchment, contributing 38% of the N inputs. The estimated catchment N budgets highlighted areas of key uncertainty, particularly N2 exchange and stream N export. The resulting N balances suggest that the study catchments have a limited capacity to store N within soils, vegetation and groundwater. The "catchment N retention", i.e. the amount of N which is either stored within the catchment or lost through atmospheric emissions, was estimated to be 13% of the net anthropogenic input in the moorland and 61% in the grassland catchment. These values contrast with regional scale estimates: Catchment retentions of net anthropogenic input estimated within Europe at the regional scale range from 50% to 90%, with an average of 82% (Billen et al., 2011. This study emphasises the need for detailed budget analyses to identify the N status of European landscapes.

  4. Urbanization increased metal levels in lake surface sediment and catchment topsoil of waterscape parks

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hong-Bo [Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China); Graduate University of Chinese Academy of Sciences, Beijing 100049 (China); Yu, Shen, E-mail: syu@iue.ac.cn [Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China); Li, Gui-Lin [Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China); Liu, Yi; Yu, Guang-Bin [Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China); Graduate University of Chinese Academy of Sciences, Beijing 100049 (China); Deng, Hong [Department of Environmental Sciences, Tiantong National Station of Forest Ecosystem, Key Laboratory of Urbanization and Ecological Restoration, East China Normal University, Shanghai 200062 (China); Wu, Sheng-Chun [State Key Laboratory in Marine Pollution, Biology and Chemistry Department, City University of Hong Kong, Hong Kong (China); Wong, Ming-Hung [Croucher Institute for Environmental Sciences, Hong Kong Baptist University, Hong Kong (China)

    2012-08-15

    Lake surface sediment is mainly derived from topsoil in its catchment. We hypothesized that distribution of anthropogenic metals would be homogenous in lake surface sediment and the lake's catchment topsoil. Anthropogenic metal distributions (cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn)) in fourteen waterscape parks were investigated in surface sediments and catchment topsoils and possible source homogeneity was tested using stable Pb isotopic ratio analysis. The parks were located along an urbanization gradient consisting of suburban (SU), developing urban (DIU), developed urban (DDU), and central urban core (CUC) areas in Shanghai, China. Results indicated that surface lake sediments and catchment topsoils in the CUC parks were highly contaminated by the investigated anthropogenic metals. Total metal contents in surface sediment and topsoil gradually increased along the urbanization gradient from the SU to CUC areas. Generally, the surface sediments had greater total metal contents than their catchment topsoils. These results suggest that urbanization drives the anthropogenic metal enrichment in both surface sediment and its catchment topsoil in the waterscape parks. Soil fine particles (< 63 {mu}m) and surface sediments had similar enrichment ratios of metals, suggesting that surface runoff might act as a carrier for metals transporting from catchment to lake. Stable Pb isotope ratio analysis revealed that the major anthropogenic Pb source in surface sediment was coal combustion as in the catchment topsoil. Urbanization also correlated with chemical fractionation of metals in both surface sediment and catchment topsoil. From the SU to the CUC parks, amounts of labile metal fractions increased while the residual fraction of those metals remained rather constant. In short, urbanization in Shanghai drives anthropogenic metal distribution in environmental matrices and the sources were homogenous. -- Highlights: Black-Right-Pointing-Pointer Obvious

  5. Water pulses and biogeochemical cycles in arid and semiarid ecosystems.

    Science.gov (United States)

    Austin, Amy T; Yahdjian, Laura; Stark, John M; Belnap, Jayne; Porporato, Amilcare; Norton, Urszula; Ravetta, Damián A; Schaeffer, Sean M

    2004-10-01

    The episodic nature of water availability in arid and semiarid ecosystems has significant consequences on belowground carbon and nutrient cycling. Pulsed water events directly control belowground processes through soil wet-dry cycles. Rapid soil microbial response to incident moisture availability often results in almost instantaneous C and N mineralization, followed by shifts in C/N of microbially available substrate, and an offset in the balance between nutrient immobilization and mineralization. Nitrogen inputs from biological soil crusts are also highly sensitive to pulsed rain events, and nitrogen losses, particularly gaseous losses due to denitrification and nitrate leaching, are tightly linked to pulses of water availability. The magnitude of the effect of water pulses on carbon and nutrient pools, however, depends on the distribution of resource availability and soil organisms, both of which are strongly affected by the spatial and temporal heterogeneity of vegetation cover, topographic position and soil texture. The 'inverse texture hypothesis' for net primary production in water-limited ecosystems suggests that coarse-textured soils have higher NPP than fine-textured soils in very arid zones due to reduced evaporative losses, while NPP is greater in fine-textured soils in higher rainfall ecosystems due to increased water-holding capacity. With respect to belowground processes, fine-textured soils tend to have higher water-holding capacity and labile C and N pools than coarse-textured soils, and often show a much greater flush of N mineralization. The result of the interaction of texture and pulsed rainfall events suggests a corollary hypothesis for nutrient turnover in arid and semiarid ecosystems with a linear increase of N mineralization in coarse-textured soils, but a saturating response for fine-textured soils due to the importance of soil C and N pools. Seasonal distribution of water pulses can lead to the accumulation of mineral N in the dry season

  6. Improvement of Surface Albedo Simulations over Arid Regions

    Institute of Scientific and Technical Information of China (English)

    BAO Yan; L(U) Shihua; ZHANG Yu; MENG Xianhong; YANG Shengpeng

    2008-01-01

    To improve the simulation of the surface radiation budget and related thermal processes in arid regions, three sophisticated surface albedo schemes designed for such regions were incorporated into the Biosphere-Atmosphere Transfer Scheme (BATS). Two of these schemes are functions of the solar zenith angle (SZA), where the first one has one adjustable parameter defined as SZA1 scheme, and the second one has two empir-ical parameters defined as SZA2 scheme. The third albedo scheme is a function of solar angle and soil water that were developed based on arid-region observations from the Dunhuang field experiment (DHEX) (defined as DH scheme). We evaluated the performance of the original and newly-incorporated albedo schemes within BATS using the in-situ data from the Oasis System Energy and Water Cycle Field Experiment that was carried out in JinTa, Gansu arid area (JTEX). The results indicate that a control run by the original version of the BATS generates a constant albedo, while the SZA1 and SZA2 schemes basically can reproduce the observed diurnal cycle of surface albedo, although these two schemes still underestimate the albedo when SZA is high in the early morning and late afternoon, and overestimate it when SZA is low during noontime. The SZA2 scheme has a better overall performance than the SZA1 scheme. In addition, BATS with the DH scheme slightly improves the albedo simulation in magnitude as compared to that from the control run, but a diurnal cycle of albedo is not produced by this scheme. The SZAl and SZA2 schemes significantly increase the surface absorbed solar radiation by nearly 70 W m~2, which further raises the ground temperature by 6 K and the sensible heat flux by 35 W m~2. The increased solar radiation, heat flux, and temperature are more consistent with the observations that those from the control run. However, a significant improv