WorldWideScience

Sample records for surface hydrological cycle

  1. The observed sensitivity of the global hydrological cycle to changes in surface temperature

    International Nuclear Information System (INIS)

    Arkin, Phillip A; Janowiak, John; Smith, Thomas M; Sapiano, Mathew R P

    2010-01-01

    Climate models project large changes in global surface temperature in coming decades that are expected to be accompanied by significant changes in the global hydrological cycle. Validation of model simulations is essential to support their use in decision making, but observing the elements of the hydrological cycle is challenging, and model-independent global data sets exist only for precipitation. We compute the sensitivity of the global hydrological cycle to changes in surface temperature using available global precipitation data sets and compare the results against the sensitivities derived from model simulations of 20th century climate. The implications of the results for the global climate observing system are discussed.

  2. The Water Cycle from Space: Use of Satellite Data in Land Surface Hydrology and Water Resource Management

    Science.gov (United States)

    Laymon, Charles; Blankenship, Clay; Khan, Maudood; Limaye, Ashutosh; Hornbuckle, Brian; Rowlandson, Tracy

    2010-01-01

    This slide presentation reviews how our understanding of the water cycle is enhanced by our use of satellite data, and how this informs land surface hydrology and water resource management. It reviews how NASA's current and future satellite missions will provide Earth system data of unprecedented breadth, accuracy and utility for hydrologic analysis.

  3. The earth's hydrological cycle

    CERN Document Server

    Bonnet, R-M; Calisto, M; Destouni, G; Gurney, R; Johannessen, J; Kerr, Y; Lahoz, WA; Rast, M

    2014-01-01

    This book gives a comprehensive presentation of our present understanding of the Earth's Hydrological cycle and the problems, consequences and impacts that go with this topic. Water is a central component in the Earth's system. It is indispensable for life on Earth in its present form and influences virtually every aspect of our planet's life support system. On relatively short time scales, atmospheric water vapor interacts with the atmospheric circulation and is crucial in forming the Earth's climate zones. Water vapor is the most powerful of the greenhouse gases and serves to enhance the tropospheric temperature. The dominant part of available water on Earth resides in the oceans. Parts are locked up in the land ice on Greenland and Antarctica and a smaller part is estimated to exist as groundwater. If all the ice over the land and all the glaciers were to melt, the sea level would rise by some 80 m. In comparison, the total amount of water vapor in the atmosphere is small; it amounts to ~ 25 kg/m2, or the ...

  4. Relationship among soil surface properties, hydrology and nitrogen cycling along a climatological gradient in drylands

    Science.gov (United States)

    Zaady, E.; Segoli, M.; Eldridge, D. J.; Groffman, P. M.; Boeken, B.; Shachak, M.

    2009-04-01

    Primary production and nutrient cycling in dryland systems are limited by water supply. There are two groups of primary producers, high biomass production plants and low biomass producing organisms found in biological soil crusts (BSC's), which control energy flow, nutrient cycling and hydrology. Biological or biogenic soil crusts are common in the world's drylands, from dry sub-humid to hyper-arid systems. The crusts are formed by communities of microphytes, mainly cyanobacteria, green algae, mosses, and lichens. The extracellular polysaccharide materials produced by the crust organisms attach soil particles, creating a solid horizontal layer of crust. Biological soil crusts modify soil quality by (1) aggregating soil particles, thereby reducing wind and water erosion; (2) reducing water infiltration, causing overland water run-off; and (3) N fixation and C sequestration. Dryland landscapes are two phase mosaic composed of BSC and high production patches. Development or loss of BSC may trigger changes in the spatial distribution of the patch types and therefore transitions between functional and degraded ecosystem states. We present a conceptual model depicting the function of each patch type and the link between them. Taking into account the contrast between low and high vegetation cover of dryland systems and their role in controlling soil nitrogen and water flows. The model describes the functioning of dryland systems with low biomass producing crust organisms cover, low rainfall, low top soil water and production, which cause low infiltration rate, low N uptake, nitrate accumulation, high evaporation and runoff. This leads to leaching of nitrates, oxygen depletion with high anaerobic conditions, high denitrification rates and N loss, resulting in low plant cover and soil organic matter i.e., degraded soil. It also depicts the functioning of the high production plants under low rainfall regimes resulting in low rates of N and energy flows. The model shows that

  5. Hydrological land surface modelling

    DEFF Research Database (Denmark)

    Ridler, Marc-Etienne Francois

    Recent advances in integrated hydrological and soil-vegetation-atmosphere transfer (SVAT) modelling have led to improved water resource management practices, greater crop production, and better flood forecasting systems. However, uncertainty is inherent in all numerical models ultimately leading...... temperature are explored in a multi-objective calibration experiment to optimize the parameters in a SVAT model in the Sahel. The two satellite derived variables were effective at constraining most land-surface and soil parameters. A data assimilation framework is developed and implemented with an integrated...... and disaster management. The objective of this study is to develop and investigate methods to reduce hydrological model uncertainty by using supplementary data sources. The data is used either for model calibration or for model updating using data assimilation. Satellite estimates of soil moisture and surface...

  6. An observational and modeling study of impacts of bark beetle-caused tree mortality on surface energy and hydrological cycles

    Science.gov (United States)

    Fei Chen; Guo Zhang; Michael Barlage; Ying Zhang; Jeffrey A. Hicke; Arjan Meddens; Guangsheng Zhou; William J. Massman; John Frank

    2015-01-01

    Bark beetle outbreaks have killed billions of trees and affected millions of hectares of forest during recent decades. The objective of this study was to quantify responses of surface energy and hydrologic fluxes 2-3 yr following a spruce beetle outbreak using measurements and modeling. The authors used observations at the Rocky Mountains Glacier Lakes Ecosystem...

  7. Modeling the hydrological cycle on Mars

    Directory of Open Access Journals (Sweden)

    Ghada Machtoub

    2012-03-01

    Full Text Available The study provides a detailed analysis of the hydrological cycle on Mars simulated with a newly developed microphysical model, incorporated in a spectral Mars General Circulation Model. The modeled hydrological cycle is compared well with simulations of other global climate models. The simulated seasonal migration ofwater vapor, circulation instability, and the high degree of temporal variability of localized water vapor outbursts are shown closely consistent with recent observations. The microphysical parameterization provides a significant improvement in the modeling of ice clouds evolved over the tropics and major ancient volcanoes on Mars. The most significant difference between the simulations presented here and other GCM results is the level at which the water ice clouds are found. The model findings also support interpretation of observed thermal anomalies in the Martian tropics during northern spring and summer seasons.

  8. Heavy metals in the hydrological cycle

    International Nuclear Information System (INIS)

    Astruc, M.; Lester, J.N.

    1988-01-01

    An integrated approach to the problems associated with heavy metals in the hydrological cycle is presented. Research and practical experience from a broad spectrum of disciplines are drawn together concentrating on the following themes: water quality, domestic and industrial wastes, sludge and dredge materials, soil interactions, effects on aquatic ecosystems, organometallics (with particular reference to tin compounds), speciation, the marine environment and health effects. One paper is within INIS scope and is processed separately. (U.K.)

  9. Assimilation of remote sensing observations into a continuous distributed hydrological model: impacts on the hydrologic cycle

    Science.gov (United States)

    Laiolo, Paola; Gabellani, Simone; Campo, Lorenzo; Cenci, Luca; Silvestro, Francesco; Delogu, Fabio; Boni, Giorgio; Rudari, Roberto

    2015-04-01

    The reliable estimation of hydrological variables (e.g. soil moisture, evapotranspiration, surface temperature) in space and time is of fundamental importance in operational hydrology to improve the forecast of the rainfall-runoff response of catchments and, consequently, flood predictions. Nowadays remote sensing can offer a chance to provide good space-time estimates of several hydrological variables and then improve hydrological model performances especially in environments with scarce in-situ data. This work investigates the impact of the assimilation of different remote sensing products on the hydrological cycle by using a continuous physically based distributed hydrological model. Three soil moisture products derived by ASCAT (Advanced SCATterometer) are used to update the model state variables. The satellite-derived products are assimilated into the hydrological model using different assimilation techniques: a simple nudging and the Ensemble Kalman Filter. Moreover two assimilation strategies are evaluated to assess the impact of assimilating the satellite products at model spatial resolution or at the satellite scale. The experiments are carried out for three Italian catchments on multi year period. The benefits on the model predictions of discharge, LST, evapotranspiration and soil moisture dynamics are tested and discussed.

  10. The impact of runoff and surface hydrology on Titan's climate

    Science.gov (United States)

    Faulk, Sean; Lora, Juan; Mitchell, Jonathan

    2017-10-01

    Titan’s surface liquid distribution has been shown by general circulation models (GCMs) to greatly influence the hydrological cycle. Simulations from the Titan Atmospheric Model (TAM) with imposed polar methane “wetlands” reservoirs realistically produce many observed features of Titan’s atmosphere, whereas “aquaplanet” simulations with a global methane ocean are not as successful. In addition, wetlands simulations, unlike aquaplanet simulations, demonstrate strong correlations between extreme rainfall behavior and observed geomorphic features, indicating the influential role of precipitation in shaping Titan’s surface. The wetlands configuration is, in part, motivated by Titan’s large-scale topography featuring low-latitude highlands and high-latitude lowlands, with the implication being that methane may concentrate in the high-latitude lowlands by way of runoff and subsurface flow. However, the extent to which topography controls the surface liquid distribution and thus impacts the global hydrological cycle by driving surface and subsurface flow is unclear. Here we present TAM simulations wherein the imposed wetlands reservoirs are replaced by a surface runoff scheme that allows surface liquid to self-consistently redistribute under the influence of topography. To isolate the singular impact of surface runoff on Titan’s climatology, we run simulations without parameterizations of subsurface flow and topography-atmosphere interactions. We discuss the impact of surface runoff on the surface liquid distribution over seasonal timescales and compare the resulting hydrological cycle to observed cloud and surface features, as well as to the hydrological cycles of the TAM wetlands and aquaplanet simulations. While still idealized, this more realistic representation of Titan’s hydrology provides new insight into the complex interaction between Titan’s atmosphere and surface, demonstrates the influence of surface runoff on Titan’s global climate

  11. Evaluating the hydrological consistency of satellite based water cycle components

    KAUST Repository

    Lopez Valencia, Oliver Miguel

    2016-06-15

    Advances in multi-satellite based observations of the earth system have provided the capacity to retrieve information across a wide-range of land surface hydrological components and provided an opportunity to characterize terrestrial processes from a completely new perspective. Given the spatial advantage that space-based observations offer, several regional-to-global scale products have been developed, offering insights into the multi-scale behaviour and variability of hydrological states and fluxes. However, one of the key challenges in the use of satellite-based products is characterizing the degree to which they provide realistic and representative estimates of the underlying retrieval: that is, how accurate are the hydrological components derived from satellite observations? The challenge is intrinsically linked to issues of scale, since the availability of high-quality in-situ data is limited, and even where it does exist, is generally not commensurate to the resolution of the satellite observation. Basin-scale studies have shown considerable variability in achieving water budget closure with any degree of accuracy using satellite estimates of the water cycle. In order to assess the suitability of this type of approach for evaluating hydrological observations, it makes sense to first test it over environments with restricted hydrological inputs, before applying it to more hydrological complex basins. Here we explore the concept of hydrological consistency, i.e. the physical considerations that the water budget impose on the hydrologic fluxes and states to be temporally and spatially linked, to evaluate the reproduction of a set of large-scale evaporation (E) products by using a combination of satellite rainfall (P) and Gravity Recovery and Climate Experiment (GRACE) observations of storage change, focusing on arid and semi-arid environments, where the hydrological flows can be more realistically described. Our results indicate no persistent hydrological

  12. Green roof impact on the hydrological cycle components

    Science.gov (United States)

    Lamera, Carlotta; Rulli, Maria Cristina; Becciu, Gianfranco; Rosso, Renzo

    2013-04-01

    In the last decades the importance of storm water management in urban areas has increased considerably, due to both urbanization extension and to a greater concern for environment pollution. Traditional storm water control practices, based on the "all to the sewer" attitude, rely on conveyance to route storm water runoff from urban impervious surfaces towards the nearby natural water bodies. In recent years, infiltration facilities are receiving an increasing attention, due to their particular efficiency in restoring a balance in hydrological cycle quite equal to quite pre-urbanization condition. In particular, such techniques are designed to capture, temporarily retain and infiltrate storm water, promote evapotranspiration and harvest water at the source, encouraging in general evaporation, evapotranspiration, groundwater recharge and the re-use of storm water. Green roofs are emerging as an increasingly popular Sustainable Urban Drainage Systems (SUDS) technique for urban storm water management. Indeed, they are able to operate hydrologic control over storm water runoff: they allow a significant reduction of peak flows and runoff volumes collected by drainage system, with a consequent reduction of flooding events and pollution masses discharges by CSO. Furthermore green roofs have a positive influence on the microclimate in urban areas by helping in lower urban air temperatures and mitigate the heat island effect. Last but not least, they have the advantage of improving the thermal insulation of buildings, with significant energy savings. A detailed analysis of the hydrological dynamics, connected both with the characteristics of the climatic context and with the green roof technical design, is essential in order to obtain a full characterization of the hydrologic behavior of a green roof system and its effects on the urban water cycle components. The purpose of this paper is to analysis the hydrological effects and urban benefits of the vegetation cover of a

  13. eWaterCycle: A global operational hydrological forecasting model

    Science.gov (United States)

    van de Giesen, Nick; Bierkens, Marc; Donchyts, Gennadii; Drost, Niels; Hut, Rolf; Sutanudjaja, Edwin

    2015-04-01

    Development of an operational hyper-resolution hydrological global model is a central goal of the eWaterCycle project (www.ewatercycle.org). This operational model includes ensemble forecasts (14 days) to predict water related stress around the globe. Assimilation of near-real time satellite data is part of the intended product that will be launched at EGU 2015. The challenges come from several directions. First, there are challenges that are mainly computer science oriented but have direct practical hydrological implications. For example, we aim to make use as much as possible of existing standards and open-source software. For example, different parts of our system are coupled through the Basic Model Interface (BMI) developed in the framework of the Community Surface Dynamics Modeling System (CSDMS). The PCR-GLOBWB model, built by Utrecht University, is the basic hydrological model that is the engine of the eWaterCycle project. Re-engineering of parts of the software was needed for it to run efficiently in a High Performance Computing (HPC) environment, and to be able to interface using BMI, and run on multiple compute nodes in parallel. The final aim is to have a spatial resolution of 1km x 1km, which is currently 10 x 10km. This high resolution is computationally not too demanding but very memory intensive. The memory bottleneck becomes especially apparent for data assimilation, for which we use OpenDA. OpenDa allows for different data assimilation techniques without the need to build these from scratch. We have developed a BMI adaptor for OpenDA, allowing OpenDA to use any BMI compatible model. To circumvent memory shortages which would result from standard applications of the Ensemble Kalman Filter, we have developed a variant that does not need to keep all ensemble members in working memory. At EGU, we will present this variant and how it fits well in HPC environments. An important step in the eWaterCycle project was the coupling between the hydrological and

  14. Global operational hydrological forecasts through eWaterCycle

    Science.gov (United States)

    van de Giesen, Nick; Bierkens, Marc; Donchyts, Gennadii; Drost, Niels; Hut, Rolf; Sutanudjaja, Edwin

    2015-04-01

    Central goal of the eWaterCycle project (www.ewatercycle.org) is the development of an operational hyper-resolution hydrological global model. This model is able to produce 14 day ensemble forecasts based on a hydrological model and operational weather data (presently NOAA's Global Ensemble Forecast System). Special attention is paid to prediction of situations in which water related issues are relevant, such as floods, droughts, navigation, hydropower generation, and irrigation stress. Near-real time satellite data will be assimilated in the hydrological simulations, which is a feature that will be presented for the first time at EGU 2015. First, we address challenges that are mainly computer science oriented but have direct practical hydrological implications. An important feature in this is the use of existing standards and open-source software to the maximum extent possible. For example, we use the Community Surface Dynamics Modeling System (CSDMS) approach to coupling models (Basic Model Interface (BMI)). The hydrological model underlying the project is PCR-GLOBWB, built by Utrecht University. This is the motor behind the predictions and state estimations. Parts of PCR-GLOBWB have been re-engineered to facilitate running it in a High Performance Computing (HPC) environment, run parallel on multiple nodes, as well as to use BMI. Hydrological models are not very CPU intensive compared to, say, atmospheric models. They are, however, memory hungry due to the localized processes and associated effective parameters. To accommodate this memory need, especially in an ensemble setting, a variation on the traditional Ensemble Kalman Filter was developed that needs much less on-chip memory. Due to the operational nature, the coupling of the hydrological model with hydraulic models is very important. The idea is not to run detailed hydraulic routing schemes over the complete globe but to have on-demand simulation prepared off-line with respect to topography and

  15. The hydrological cycle and its influence on climate

    Energy Technology Data Exchange (ETDEWEB)

    Chahine, M T [California Institute of Technology, Pasadena, CA (USA). Jet Propulsion Laboratory

    1992-10-01

    The uncertainties in assessing the effects of global-scale perturbations to the climate system are due primarily to an inadequate understanding of the hydrological cycle - the cycling of water in the oceans, atmosphere and biosphere. Overcoming this problem necessitates new ways of regarding a field traditionally divided amongst several disciplines, as well as new instrumentation and methods of data collection. The author aims to provide an appraisal of current theoretical and observational understanding of the roles of the hydrological cycle in the climate system, and its intimate connection to the energy cycle. An attempt is made to show why the hydrological cycle has emerged as the central element in studies of climate change, and to anticipate the main advances expected in modelling observations in the coming decade, along with areas where improvements will still be required. 62 refs., 3 figs., 1 tab.

  16. A Watershed Scale Life Cycle Assessment Framework for Hydrologic Design

    Science.gov (United States)

    Tavakol-Davani, H.; Tavakol-Davani, PhD, H.; Burian, S. J.

    2017-12-01

    Sustainable hydrologic design has received attention from researchers with different backgrounds, including hydrologists and sustainability experts, recently. On one hand, hydrologists have been analyzing ways to achieve hydrologic goals through implementation of recent environmentally-friendly approaches, e.g. Green Infrastructure (GI) - without quantifying the life cycle environmental impacts of the infrastructure through the ISO Life Cycle Assessment (LCA) method. On the other hand, sustainability experts have been applying the LCA to study the life cycle impacts of water infrastructure - without considering the important hydrologic aspects through hydrologic and hydraulic (H&H) analysis. In fact, defining proper system elements for a watershed scale urban water sustainability study requires both H&H and LCA specialties, which reveals the necessity of performing an integrated, interdisciplinary study. Therefore, the present study developed a watershed scale coupled H&H-LCA framework to bring the hydrology and sustainability expertise together to contribute moving the current wage definition of sustainable hydrologic design towards onto a globally standard concept. The proposed framework was employed to study GIs for an urban watershed in Toledo, OH. Lastly, uncertainties associated with the proposed method and parameters were analyzed through a robust Monte Carlo simulation using parallel processing. Results indicated the necessity of both hydrologic and LCA components in the design procedure in order to achieve sustainability.

  17. Critical impact of vegetation physiology on the continental hydrologic cycle in response to increasing CO2

    Science.gov (United States)

    Lemordant, Léo; Gentine, Pierre; Swann, Abigail S.; Cook, Benjamin I.; Scheff, Jacob

    2018-04-01

    Predicting how increasing atmospheric CO2 will affect the hydrologic cycle is of utmost importance for a range of applications ranging from ecological services to human life and activities. A typical perspective is that hydrologic change is driven by precipitation and radiation changes due to climate change, and that the land surface will adjust. Using Earth system models with decoupled surface (vegetation physiology) and atmospheric (radiative) CO2 responses, we here show that the CO2 physiological response has a dominant role in evapotranspiration and evaporative fraction changes and has a major effect on long-term runoff compared with radiative or precipitation changes due to increased atmospheric CO2. This major effect is true for most hydrological stress variables over the largest fraction of the globe, except for soil moisture, which exhibits a more nonlinear response. This highlights the key role of vegetation in controlling future terrestrial hydrologic response and emphasizes that the carbon and water cycles are intimately coupled over land.

  18. Strong hydrological control on nutrient cycling of subtropical rainforests

    Science.gov (United States)

    Lin, T. C.; Chang, C. T.; Huang, J. C.; Wang, L.; Lin, N. H.

    2016-12-01

    Forest nutrient cycling is strongly controlled by both biological and hydrological factors. However, based on a close examination of earlier reports, we highlight the role of hydrological control on nutrient cycling at a global scale and is more important at humid tropical and subtropical forests. we analyzed the nutrient budget of precipitation input and stream water output from 1994 to 2013 in a subtropical forest in Taiwan and conducted a data synthesis using results from 32 forests across the globe. The results revealed that monthly input and output of ions were positively correlated with water quantity, indicating hydrological control on nutrient cycling. Hydrological control is also evident from the greater ions export via stream water during the warm and wet growing season. The synthesis also illustrates that strong hydrological control leads to lower nitrogen retention and greater net loss of base cations in humid regions, particularly in the humid tropical and subtropical forests. Our result is of great significance in an era of global climate change because climate change could directly affect ecosystem nutrient cycling particularly in the tropics through changes in patterns of precipitation regime.

  19. Land-surface modelling in hydrological perspective

    DEFF Research Database (Denmark)

    Overgaard, Jesper; Rosbjerg, Dan; Butts, M.B.

    2006-01-01

    The purpose of this paper is to provide a review of the different types of energy-based land-surface models (LSMs) and discuss some of the new possibilities that will arise when energy-based LSMs are combined with distributed hydrological modelling. We choose to focus on energy-based approaches......, and the difficulties inherent in various evaluation procedures are presented. Finally, the dynamic coupling of hydrological and atmospheric models is explored, and the perspectives of such efforts are discussed......., because in comparison to the traditional potential evapotranspiration models, these approaches allow for a stronger link to remote sensing and atmospheric modelling. New opportunities for evaluation of distributed land-surface models through application of remote sensing are discussed in detail...

  20. Soil as the Central Link in the Hydrological Cycle

    Science.gov (United States)

    Hillel, D.

    2005-05-01

    We present an overview of the function fulfilled by the soil in the chain of processes constituting the hydrological cycle in the terrestrial domain. Considering the height of the atmosphere, the thickness of the earth's rock mantle, and the depth of the ocean, we note that the soil is amazingly thin -- typically not much more than one meter thick. Yet, with its sponge-like porosity, internal surface area, and finite capacities to absorb, store, and transmit water and solutes, the soil determines the fate of precipitation reaching the ground surface - whether it flows over the land as runoff, is detained and made available to plant roots, or seeps downward to an aquifer. Without the soil as a buffer, rainfall would produce violent floods rather than sustained stream-flow. The soil also acts as a living filter, in which dissolved and suspended constituents are retained or transmuted into nutrients for the continual regeneration of life. Energy as well as matter is in constant flux as solar radiation is absorbed by the soil and growing plants and as heat is exchanged in evaporation and condensation as well as in biochemical reactions. Plant leaves absorb carbon dioxide from the air and synthesize it with soil-derived water to form the primary compounds of life, while oxygen emitted by the leaves makes the air breathable for animals, which in turn fertilize the plants. However unique in form and function, the soil is not an isolated body but interacts with the overlying atmosphere and underlying strata, and with surface and underground bodies of water. Especially important is the interrelation between the soil and the climate, enhancing or mitigating the greenhouse effect via the soil's uptake or release of radiatively active gases (carbon dioxide, methane, and nitrous oxide). For all these reasons, it is vital that we give full consideration to the soil's role in the context of hydrology. The problem to overcome, however, is the disjunct between the characteristic

  1. A post-Cassini view of Titan's methane-based hydrologic cycle

    Science.gov (United States)

    Hayes, Alexander G.; Lorenz, Ralph D.; Lunine, Jonathan I.

    2018-05-01

    The methane-based hydrologic cycle on Saturn's largest moon, Titan, is an extreme analogue to Earth's water cycle. Titan is the only planetary body in the Solar System, other than Earth, that is known to have an active hydrologic cycle. With a surface pressure of 1.5 bar and temperatures of 90 to 95 K, methane and ethane condense out of a nitrogen-based atmosphere and flow as liquids on the moon's surface. Exchange processes between atmospheric, surface and subsurface reservoirs produce methane and ethane cloud systems, as well as erosional and depositional landscapes that have strikingly similar forms to their terrestrial counterparts. Over its 13-year exploration of the Saturn system, the Cassini-Huygens mission revealed that Titan's hydrocarbon-based hydrology is driven by nested methane cycles that operate over a range of timescales, including geologic, orbital (for example, Croll-Milankovitch cycles), seasonal and that of a single convective storm. In this Review Article, we describe the dominant exchange processes that operate over these timescales and present a post-Cassini view of Titan's methane-based hydrologic system.

  2. Surface Velocities and Hydrology at Engabreen

    DEFF Research Database (Denmark)

    Messerli, Alexandra

    complicates comparisons with other surface-oriented glaciohydrological studies. One major aim of this thesis is to provide a longer record of surface velocity, enabling a more complete understanding of the glacial hydro-mechanical relationship at Engabreen. In order to extend the velocity dataset here, a time...... the lower tongue of Engabreen are analysed in detail alongside the hydro-meteorological time-series. The higher temporal resolution of the GPS allows the effect of short-term hydrological forcings on ice flow to be assessed. Two key events: the spring-speed up event (P1a) and a short-term rain induced event...

  3. Water Vapor Tracers as Diagnostics of the Regional Hydrologic Cycle

    Science.gov (United States)

    Bosilovich, Michael G.; Schubert, Siegfried D.; Einaudi, Franco (Technical Monitor)

    2001-01-01

    Numerous studies suggest that local feedback of surface evaporation on precipitation, or recycling, is a significant source of water for precipitation. Quantitative results on the exact amount of recycling have been difficult to obtain in view of the inherent limitations of diagnostic recycling calculations. The current study describes a calculation of the amount of local and remote geographic sources of surface evaporation for precipitation, based on the implementation of three-dimensional constituent tracers of regional water vapor sources (termed water vapor tracers, WVT) in a general circulation model. The major limitation on the accuracy of the recycling estimates is the veracity of the numerically simulated hydrological cycle, though we note that this approach can also be implemented within the context of a data assimilation system. In the WVT approach, each tracer is associated with an evaporative source region for a prognostic three-dimensional variable that represents a partial amount of the total atmospheric water vapor. The physical processes that act on a WVT are determined in proportion to those that act on the model's prognostic water vapor. In this way, the local and remote sources of water for precipitation can be predicted within the model simulation, and can be validated against the model's prognostic water vapor. As a demonstration of the method, the regional hydrologic cycles for North America and India are evaluated for six summers (June, July and August) of model simulation. More than 50% of the precipitation in the Midwestern United States came from continental regional sources, and the local source was the largest of the regional tracers (14%). The Gulf of Mexico and Atlantic regions contributed 18% of the water for Midwestern precipitation, but further analysis suggests that the greater region of the Tropical Atlantic Ocean may also contribute significantly. In most North American continental regions, the local source of precipitation is

  4. The Influence of Runoff and Surface Hydrology on Titan's Weather and Climate

    Science.gov (United States)

    Faulk, S.; Lora, J. M.; Mitchell, J.; Moon, S.

    2017-12-01

    Titan's surface liquid distribution has been shown by general circulation models (GCMs) to greatly influence the hydrological cycle, producing characteristic weather and seasonal climate patterns. Simulations from the Titan Atmospheric Model (TAM) with imposed polar methane "wetlands" reservoirs realistically produce observed cloud features and temperature profiles of Titan's atmosphere, whereas "aquaplanet" simulations with a global methane ocean are not as successful. In addition, wetlands simulations, unlike aquaplanet simulations, demonstrate strong correlations between extreme rainfall behavior and observed geomorphic features, indicating the influential role of precipitation in shaping Titan's surface. The wetlands configuration is, in part, motivated by Titan's large-scale topography featuring low-latitude highlands and high-latitude lowlands, with the implication being that methane may concentrate in the high-latitude lowlands by way of runoff and subsurface flow of a global or regional methane table. However, the extent to which topography controls the surface liquid distribution and thus impacts the global hydrological cycle by driving surface and subsurface flow is unclear. Here we present TAM simulations wherein the imposed wetlands reservoirs are replaced by a surface runoff scheme that allows surface liquid to self-consistently redistribute under the influence of topography. We discuss the impact of surface runoff on the surface liquid distribution over seasonal timescales and compare the resulting hydrological cycle to observed cloud and surface features, as well as to the hydrological cycles of the TAM wetlands and aquaplanet simulations. While still idealized, this more realistic representation of Titan's hydrology provides new insight into the complex interaction between Titan's atmosphere and surface, demonstrates the influence of surface runoff on Titan's global climate, and lays the groundwork for further surface hydrology developments in Titan

  5. Hydrological effects on carbon cycles of Canada's forests and wetlands

    International Nuclear Information System (INIS)

    Ju, Weimin; Chen, Jing M.; Black, T. Andrew; Barr, Alan G.; Mccaughey, Harry; Roulet, Nigel T.

    2006-01-01

    The hydrological cycle has significant effects on the terrestrial carbon (C) balance through its controls on photosynthesis and C decomposition. A detailed representation of the water cycle in terrestrial C cycle models is essential for reliable estimates of C budgets. However, it is challenging to accurately describe the spatial and temporal variations of soil water, especially for regional and global applications. Vertical and horizontal movements of soil water should be included. To constrain the hydrology-related uncertainty in modelling the regional C balance, a three-dimensional hydrological module was incorporated into the Integrated Terrestrial Ecosystem Carbon-budget model (InTEC V3.0). We also added an explicit parameterization of wetlands. The inclusion of the hydrological module considerably improved the model's ability to simulate C content and balances in different ecosystems. Compared with measurements at five flux-tower sites, the model captured 85% and 82% of the variations in volumetric soil moisture content in the 0-10 cm and 10-30 cm depths during the growing season and 84% of the interannual variability in the measured C balance. The simulations showed that lateral subsurface water redistribution is a necessary mechanism for simulating water table depth for both poorly drained forest and peatland sites. Nationally, soil C content and their spatial variability are significantly related to drainage class. Poorly drained areas are important C sinks at the regional scale, however, their soil C content and balances are difficult to model and may have been inadequately represented in previous C cycle models. The InTEC V3.0 model predicted an annual net C uptake by Canada's forests and wetlands for the period 1901-1998 of 111.9 Tg C/yr, which is 41.4 Tg C/yr larger than our previous estimate (InTEC V2.0). The increase in the net C uptake occurred mainly in poorly drained regions and resulted from the inclusion of a separate wetland parameterization

  6. Human Impacts on the Hydrologic Cycle: Comparing Global Climate Change and Local Water Management

    Science.gov (United States)

    Ferguson, I. M.; Maxwell, R. M.

    2010-12-01

    Anthropogenic climate change is significantly altering the hydrologic cycle at global and regional scales, with potentially devastating impacts on water resources. Recent studies demonstrate that hydrologic response to climate change will depend on local-scale feedbacks between groundwater, surface water, and land surface processes. These studies suggest that local water management practices that alter the quantity and distribution of water in the terrestrial system—e.g., groundwater pumping and irrigation—may also feed back across the hydrologic cycle, with impacts on land-atmosphere fluxes and thus weather and climate. Here we use an integrated hydrologic model to compare the impacts of large-scale climate change and local water management practices on water and energy budgets at local and watershed scales. We consider three climate scenarios (hot, hot+wet, and hot+dry) and three management scenarios (pumping only, irrigation only, and pumping+irrigation). Results demonstrate that impacts of local water management on basin-integrated groundwater storage, evapotranspiration, and stream discharge are comparable to those of changing climate conditions. However, impacts of climate change are shown to have a smaller magnitude and greater spatial extent, while impacts of pumping and irrigation are shown to have a greater magnitude but are local to areas where pumping and irrigation occur. These results have important implications regarding the scales of human impacts on both water resources and climate and the sustainability of water resources.

  7. The influence of topography on Titan’s atmospheric circulation and hydrologic cycle

    Science.gov (United States)

    Lora, Juan M.; Faulk, Sean; Mitchell, Jonathan

    2017-10-01

    Titan’s atmospheric circulation is a dominant driver of the global methane hydrologic cycle—producing weather and a seasonal climate cycle—while interactions between the surface and the troposphere strongly constrain regional climates, and contribute to the differentiation between Titan’s low latitude deserts and high latitude lake districts. Yet the influence of surface topography on the atmospheric circulation has only been studied in a few instances, and no published work has investigated the coupling between topographical forcing and Titan’s hydrologic cycle. In this work, we examine the impacts of global topography in the Titan Atmospheric Model (TAM), which includes a robust representation of the methane cycle. We focus in particular on the influence of large-scale topographical features on the atmospheric flow, atmospheric moisture transport, and cloud formation. High latitude transient weather systems have previously been identified as important contributors to global atmospheric methane transport, and here we examine whether topographically-forced stationary or quasi-permanent systems are also important, as they are in Earth’s hydrologic cycle.

  8. Effect of water table dynamics on land surface hydrologic memory

    Science.gov (United States)

    Lo, Min-Hui; Famiglietti, James S.

    2010-11-01

    The representation of groundwater dynamics in land surface models has received considerable attention in recent years. Most studies have found that soil moisture increases after adding a groundwater component because of the additional supply of water to the root zone. However, the effect of groundwater on land surface hydrologic memory (persistence) has not been explored thoroughly. In this study we investigate the effect of water table dynamics on National Center for Atmospheric Research Community Land Model hydrologic simulations in terms of land surface hydrologic memory. Unlike soil water or evapotranspiration, results show that land surface hydrologic memory does not always increase after adding a groundwater component. In regions where the water table level is intermediate, land surface hydrologic memory can even decrease, which occurs when soil moisture and capillary rise from groundwater are not in phase with each other. Further, we explore the hypothesis that in addition to atmospheric forcing, groundwater variations may also play an important role in affecting land surface hydrologic memory. Analyses show that feedbacks of groundwater on land surface hydrologic memory can be positive, negative, or neutral, depending on water table dynamics. In regions where the water table is shallow, the damping process of soil moisture variations by groundwater is not significant, and soil moisture variations are mostly controlled by random noise from atmospheric forcing. In contrast, in regions where the water table is very deep, capillary fluxes from groundwater are small, having limited potential to affect soil moisture variations. Therefore, a positive feedback of groundwater to land surface hydrologic memory is observed in a transition zone between deep and shallow water tables, where capillary fluxes act as a buffer by reducing high-frequency soil moisture variations resulting in longer land surface hydrologic memory.

  9. eWaterCycle: A high resolution global hydrological model

    Science.gov (United States)

    van de Giesen, Nick; Bierkens, Marc; Drost, Niels; Hut, Rolf; Sutanudjaja, Edwin

    2014-05-01

    In 2013, the eWaterCycle project was started, which has the ambitious goal to run a high resolution global hydrological model. Starting point was the PCR-GLOBWB built by Utrecht University. The software behind this model will partially be re-engineered in order to enable to run it in a High Performance Computing (HPC) environment. The aim is to have a spatial resolution of 1km x 1km. The idea is also to run the model in real-time and forecasting mode, using data assimilation. An on-demand hydraulic model will be available for detailed flow and flood forecasting in support of navigation and disaster management. The project faces a set of scientific challenges. First, to enable the model to run in a HPC environment, model runs were analyzed to examine on which parts of the program most CPU time was spent. These parts were re-coded in Open MPI to allow for parallel processing. Different parallelization strategies are thinkable. In our case, it was decided to use watershed logic as a first step to distribute the analysis. There is rather limited recent experience with HPC in hydrology and there is much to be learned and adjusted, both on the hydrological modeling side and the computer science side. For example, an interesting early observation was that hydrological models are, due to their localized parameterization, much more memory intensive than models of sister-disciplines such as meteorology and oceanography. Because it would be deadly to have to swap information between CPU and hard drive, memory management becomes crucial. A standard Ensemble Kalman Filter (enKF) would, for example, have excessive memory demands. To circumvent these problems, an alternative to the enKF was developed that produces equivalent results. This presentation shows the most recent results from the model, including a 5km x 5km simulation and a proof of concept for the new data assimilation approach. Finally, some early ideas about financial sustainability of an operational global

  10. The Swiss national network for isotopes in the hydrological cycle

    International Nuclear Information System (INIS)

    Schotterer, U.

    1998-01-01

    The network is based on the long-term stations of the Climate and Environmental Physics Group and includes 11 precipitation, 6 river and 3 ground water stations. For the isotope measurements the Universities of Bern (Climate and Environmental Physics Group, tritium and oxygen-18) and Lausanne (Institute for Mineralogy and Petrography, deuterium) are contracted on a year to year basis. Sampling instructions, collection and shipment of samples are within the responsibility of the Bern group. The sampling apart from monthly composites of precipitation includes also samples from surface and ground water. The isotope data are available by contacting the Swiss Hydrological and Geological Survey directly

  11. Quadrotor helicopter for surface hydrological measurements

    Science.gov (United States)

    Pagano, C.; Tauro, F.; Porfiri, M.; Grimaldi, S.

    2013-12-01

    Surface hydrological measurements are typically performed through user-assisted and intrusive field methodologies which can be inadequate to monitor remote and extended areas. In this poster, we present the design and development of a quadrotor helicopter equipped with digital acquisition system and image calibration units for surface flow measurements. This custom-built aerial vehicle is engineered to be lightweight, low-cost, highly customizable, and stable to guarantee optimal image quality. Quadricopter stability guarantees minimal vibrations during image acquisition and, therefore, improved accuracy in flow velocity estimation through large scale particle image velocimetry algorithms or particle tracking procedures. Stability during the vehicle pitching and rolling is achieved by adopting large arm span and high-wing configurations. Further, the vehicle framework is composed of lightweight aluminum and durable carbon fiber for optimal resilience. The open source Ardupilot microcontroller is used for remote control of the quadricopter. The microcontroller includes an inertial measurement unit (IMU) equipped with accelerometers and gyroscopes for stable flight through feedback control. The vehicle is powered by a 3 cell (11.1V) 3000 mAh Lithium-polymer battery. Electronic equipment and wiring are hosted into the hollow arms and on several carbon fiber platforms in the waterproof fuselage. Four 35A high-torque motors are supported at the far end of each arm with 10 × 4.7 inch propellers. Energy dissipation during landing is accomplished by four pivoting legs that, through the use of shock absorbers, prevent the impact energy from affecting the frame thus causing significant damage. The data capturing system consists of a GoPro Hero3 camera and in-house built camera gimbal and shock absorber damping device. The camera gimbal, hosted below the vehicle fuselage, is engineered to maintain the orthogonality of the camera axis with respect to the water surface by

  12. Nanosatellite Architectures for Improved Study of the Hydrologic Cycle

    Science.gov (United States)

    Blackwell, W. J.; Osaretin, I.; Cahoy, K.

    2012-12-01

    spacecraft spinning mechanism provides a 60 RPM cross-track scan as the satellite orbits the earth. Spatial, spectral, and radiometric performance is comparable to present state-of-the-art systems with costs exceeding $100M. The propulsion systems would be used to achieve formation flight (the satellites would be separated by approximately 500 ± 5 km) and to facilitate de-orbit. The cross-linked communication would provide: 1) reduced communications latency to ground, a key performance attribute that is currently lacking in present systems leading to suboptimal utilization of observations of dynamic meteorological events such as tropical cyclones and hurricanes, and 2) data-driven sensing whereby the lead sensor observes dynamic meteorological phenomena and sends a message to the following sensor to temporarily enable a very high resolution sensing mode (a higher sample rate, for example) to better capture the interesting event and preserve spacecraft resources for when they are most needed. The DOME constellation would allow global, high-resolution, persistent observations of the Earth's surface and atmosphere for studies of the hydrologic cycle and climate feedback processes.

  13. Improving the Amazonian Hydrologic Cycle in a Coupled Land-Atmosphere, Single Column Model

    Science.gov (United States)

    Harper, A. B.; Denning, S.; Baker, I.; Prihodko, L.; Branson, M.

    2006-12-01

    We have coupled a land-surface model, the Simple Biosphere Model (SiB3), to a single column of the Colorado State University General Circulation Model (CSU-GCM) in the Amazon River Basin. This is a preliminary step in the broader goal of improved simulation of Basin-wide hydrology. A previous version of the coupled model (SiB2) showed drought and catastrophic dieback of the Amazon rain forest. SiB3 includes updated soil hydrology and root physiology. Our test area for the coupled single column model is near Santarem, Brazil, where measurements from the km 83 flux tower in the Tapajos National Forest can be used to evaluate model output. The model was run for 2001 using NCEP2 Reanalysis as driver data. Preliminary results show that the updated biosphere model coupled to the GCM produces improved simulations of the seasonal cycle of surface water balance and precipitation. Comparisons of the diurnal and seasonal cycles of surface fluxes are also being made.

  14. Atmospheric Rivers across Multi-scales of the Hydrologic cycle

    Science.gov (United States)

    Hu, H.

    2017-12-01

    Atmospheric Rivers (ARs) are defined as filamentary structures with strong water vapor transport in the atmosphere, moving as much water as is discharged by the Amazon River. As a large-scale phenomenon, ARs are embedded in the planetary-scale Rossby waves and account for the majority of poleward moisture transport in the midlatitudes. On the other hand, AR is the fundamental physical mechanism leading to extreme basin-scale precipitation and flooding over the U.S. West Coast in the winter season. The moisture transported by ARs is forced to rise and generate precipitation when it impinges on the mountainous coastal lands. My goal is to build the connection between the multi-scale features associated with ARs with their impacts on local hydrology, with particular focus on the U.S. West Coast. Moving across the different scales I have: (1) examined the planetary-scale dynamics in the upper-troposphere, and established a robust relationship between the two regimes of Rossby wave breaking and AR-precipitation and streamflow along the West Coast; (2) quantified the contribution from the tropics/subtropics to AR-related precipitation intensity and found a significant modulation from the large-scale thermodynamics; (3) developed a water tracer tool in a land surface model to track the lifecycle of the water collected from AR precipitation over the terrestrial system, so that the role of catchment-scale factors in modulating ARs' hydrological consequences could be examined. Ultimately, the information gather from these studies will indicate how the dynamic and thermodynamic changes as a response to climate change could affect the local flooding and water resource, which would be helpful in decision making.

  15. Visualizing landscape hydrology as a means of education - The water cycle in a box

    Science.gov (United States)

    Lehr, Christian; Rauneker, Philipp; Fahle, Marcus; Hohenbrink, Tobias; Böttcher, Steven; Natkhin, Marco; Thomas, Björn; Dannowski, Ralf; Schwien, Bernd; Lischeid, Gunnar

    2016-04-01

    We used an aquarium to construct a physical model of the water cycle. The model can be used to visualize the movement of the water through the landscape from precipitation and infiltration via surface and subsurface flow to discharge into the sea. The model consists of two aquifers that are divided by a loamy aquitard. The 'geological' setting enables us to establish confining groundwater conditions and to demonstrate the functioning of artesian wells. Furthermore, small experiments with colored water as tracer can be performed to identify flow paths below the ground, simulate water supply problems like pollution of drinking water wells from inflowing contaminated groundwater or changes in subsurface flow direction due to changes in the predominant pressure gradients. Hydrological basics such as the connectivity of streams, lakes and the surrounding groundwater or the dependency of groundwater flow velocity from different substrates can directly be visualized. We used the model as an instructive tool in education and for public relations. We presented the model to different audiences from primary school pupils to laymen, students of hydrology up to university professors. The model was presented to the scientific community as part of the "Face of the Earth" exhibition at the EGU general assembly 2014. Independent of the antecedent knowledge of the audience, the predominant reactions were very positive. The model often acted as icebreaker to get a conversation on hydrological topics started. Because of the great interest, we prepared video material and a photo documentation on 1) the construction of the model and 2) the visualization of steady and dynamic hydrological situations. The videos will be published soon under creative common license and the collected material will be made accessible online. Accompanying documents will address professionals in hydrology as well as non-experts. In the PICO session, we will present details about the construction of the model

  16. Biological catalysis of the hydrological cycle: life's thermodynamic function

    Science.gov (United States)

    Michaelian, K.

    2011-01-01

    Darwinian theory depicts life as being overwhelmingly consumed by a fight for survival in a hostile environment. However, from a thermodynamic perspective, life is a dynamic out of equilibrium process, stabilizing and coevolving in concert with its abiotic environment. The living component of the biosphere on the surface of the Earth of greatest biomass, the plants and cyanobacteria, are involved in the transpiration of a vast amount of water. Transpiration is part of the global water cycle, and it is this cycle that distinguishes Earth from its apparently life barren neighboring planets, Venus and Mars. The dissipation of sunlight into heat by organic molecules in the biosphere and its coupling to the water cycle (as well as other abiotic processes), is by far the greatest entropy producing process occurring on Earth. Life, from this perspective, can be viewed as performing an important thermodynamic function; acting as a dynamic catalyst by aiding irreversible abiotic process such as the water cycle, hurricanes, and ocean and wind currents to produce entropy. The role of animals in this view is that of unwitting but dedicated servants of the plants and cyanobacteria, helping them to grow and to spread into initially inhospitable areas.

  17. Accelerated warming of the Southern Ocean and its impacts on the hydrological cycle and sea ice.

    Science.gov (United States)

    Liu, Jiping; Curry, Judith A

    2010-08-24

    The observed sea surface temperature in the Southern Ocean shows a substantial warming trend for the second half of the 20th century. Associated with the warming, there has been an enhanced atmospheric hydrological cycle in the Southern Ocean that results in an increase of the Antarctic sea ice for the past three decades through the reduced upward ocean heat transport and increased snowfall. The simulated sea surface temperature variability from two global coupled climate models for the second half of the 20th century is dominated by natural internal variability associated with the Antarctic Oscillation, suggesting that the models' internal variability is too strong, leading to a response to anthropogenic forcing that is too weak. With increased loading of greenhouse gases in the atmosphere through the 21st century, the models show an accelerated warming in the Southern Ocean, and indicate that anthropogenic forcing exceeds natural internal variability. The increased heating from below (ocean) and above (atmosphere) and increased liquid precipitation associated with the enhanced hydrological cycle results in a projected decline of the Antarctic sea ice.

  18. Strengthening of the hydrological cycle in future scenarios: atmospheric energy and water balance perspective

    Directory of Open Access Journals (Sweden)

    A. Alessandri

    2012-11-01

    Full Text Available Future climate scenarios experiencing global warming are expected to strengthen the hydrological cycle during the 21st century (21C. We analyze the strengthening of the global-scale increase in precipitation from the perspective of changes in whole atmospheric water and energy balances. By combining energy and water equations for the whole atmosphere, we obtain constraints for the changes in surface fluxes and partitioning at the surface between sensible and latent components. We investigate the differences in the strengthening of the hydrological cycle in two centennial simulations performed with an Earth system model forced with specified atmospheric concentration pathways. Alongside the Special Report on Emissions Scenario (SRES A1B, which is a medium-high non-mitigation scenario, we consider a new aggressive-mitigation scenario (E1 with reduced fossil fuel use for energy production aimed at stabilizing global warming below 2 K.

    Our results show that the mitigation scenario effectively constrains the global warming with a stabilization below 2 K with respect to the 1950–2000 historical period. On the other hand, the E1 precipitation does not follow the temperature field toward a stabilization path but continues to increase over the mitigation period. Quite unexpectedly, the mitigation scenario is shown to strengthen the hydrological cycle even more than SRES A1B till around 2070. We show that this is mostly a consequence of the larger increase in the negative radiative imbalance of atmosphere in E1 compared to A1B. This appears to be primarily related to decreased sulfate aerosol concentration in E1, which considerably reduces atmospheric absorption of solar radiation compared to A1B.

    The last decades of the 21C show a marked increase in global precipitation in A1B compared to E1, despite the fact that the two scenarios display almost the same overall increase of radiative imbalance with respect to the 20th century. Our

  19. Olkiluoto surface and near-surface hydrological modelling in 2010

    International Nuclear Information System (INIS)

    Karvonen, T.

    2011-08-01

    The modeling approaches carried out with the Olkiluoto surface hydrological model (SHYD) include palaeohydrological evolution of the Olkiluoto Island, examination of the boundary condition at the geosphere-biosphere interface zone, simulations related to infiltration experiment, prediction of the influence of ONKALO on hydraulic head in shallow and deep bedrock and optimisation of the shallow monitoring network. A so called short-term prediction system was developed for continuous updating of the estimated drawdowns caused by ONKALO. The palaeohydrological simulations were computed for a period starting from the time when the highest hills on Olkiluoto Island rose above sea level around 2 500 years ago. The input data needed in the model were produced by the UNTAMO-toolbox. The groundwater flow evolution is primarily driven by the postglacial land uplift and the uncertainty in the land uplift model is the biggest single factor that influences the accuracy of the results. The consistency of the boundary condition at the geosphere-biosphere interface zone (GBIZ) was studied during 2010. The comparison carried out during 2010 showed that pressure head profiles computed with the SHYD model and deep groundwater flow model FEFTRA are in good agreement with each other in the uppermost 100 m of the bedrock. This implies that flux profiles computed with the two approaches are close to each other and hydraulic heads computed at level z=0 m with the SHYD can be used as head boundary condition in the deep groundwater flow model FEFTRA. The surface hydrological model was used to analyse the results of the infiltration experiment. Increase in bedrock recharge inside WCA explains around 60-63 % from the amount of water pumped from OL-KR14 and 37-40 % of the water pumped from OL-KR14 flows towards pumping section via the hydrogeological zones. Pumping from OL-KR14 has only a minor effect on heads and fluxes in zones HZ19A and HZ19C compared to responses caused by leakages into

  20. Direct versus indirect effects of tropospheric humidity changes on the hydrologic cycle

    International Nuclear Information System (INIS)

    Sherwood, S C

    2010-01-01

    Abundant evidence indicates that tropospheric specific humidity increases in a warmer atmosphere, at rates roughly comparable to those at constant relative humidity. While the implications for the planetary energy budget and global warming are well recognized, it is the net atmospheric cooling (or surface heating) that controls the hydrologic cycle. Relative humidity influences this directly through gas-phase radiative transfer, and indirectly by affecting cloud cover (and its radiative effects) and convective heating. Simple calculations show that the two indirect impacts are larger than the direct impact by roughly one and two orders of magnitude respectively. Global or regional relative humidity changes could therefore have significant indirect impacts on energy and water cycles, especially by altering deep convection, even if they are too small to significantly affect global temperature. Studies of climate change should place greater emphasis on these indirect links, which may not be adequately represented in models.

  1. THE HYDROLOGIC CYCLE, UNIDIRECTIONAL CHARTER OF THE DISSOLVED SALTS AND SUSPENDED LOAD

    Directory of Open Access Journals (Sweden)

    Nicolae Florea

    2012-12-01

    Full Text Available In this paper it is underlined that the hydrologic cycle in nature, reversible and regenerating of fresh water, carries out also an unidirectional and irreversible circulation – by means of a fragment of the hydrologic cycle – of the dissolved salts and stream’s suspended load, entailed by the water drained from continents to ocean. The trend is to transfer soluble salts from land to ocean in the same time with the running water on land in the portion of the hydrologic cycle which refers to the water transfer from continents to ocean in order to equilibrate the annual water balance of the hydrologic cycle. But, one can realize here and there some local salt accumulations in salt soils or in salt lakes within areas without drainage in arid climate; these salts accumulations are cases of local hydrologic cycles „grafted” along the way of water on land (to ocean. The energy necessary to the hydrologic cycle in nature is delivered by the Sun, and the entropy remains at a low level as a consequence of the elimination in this cycle of water vapors with high entropy, and of the receiving of liquid or solid water with low entropy, so that the annual level of entropy is maintained at a low level.

  2. Partitioning the effects of Global Warming on the Hydrological Cycle with Stable Isotopes in Water Vapor

    Science.gov (United States)

    Dee, S. G.; Russell, J. M.; Nusbaumer, J. M.; Konecky, B. L.; Buenning, N. H.; Lee, J. E.; Noone, D.

    2016-12-01

    General circulation models (GCMs) suggest that much of the global hydrological cycle's response to anthropogenic warming will be caused by increased lower-tropospheric water vapor concentrations and associated feedbacks. However, fingerprinting changes in the global hydrological cycle due to anthropogenic warming remains challenging. Held and Soden (2006) predicted that as lower-tropospheric water vapor increases, atmospheric circulation will weaken as climate warms to maintain the surface energy budget. Unfortunately, the strength of this feedback and the fallout for other branches of the hydrological cycle is difficult to constrain in situ or with GCMs alone. We demonstrate the utility of stable hydrogen isotope ratios in atmospheric water vapor to quantitatively trace changes in atmospheric circulation and convective mass flux in a warming world. We compare water isotope-enabled GCM experiments for control (present-day) CO2 vs. high CO2(2x, 4x) atmospheres in two GCMs, IsoGSM and iCAM5. We evaluate changes in the distribution of water vapor, vertical velocity (omega), and the stream function between these experiments in order to identify spatial patterns of circulation change over the tropical Pacific (where vertical motion is strong) and map the δD of water vapor associated with atmospheric warming. We also probe the simulations to isolate isotopic signatures associated with water vapor residence time, precipitation efficiency, divergence, and cloud physics. We show that there are robust mechanisms that moisten the troposphere and weaken convective mass flux, and that these mechanisms can be tracked using the δD of water vapor. Further, we find that these responses are most pronounced in the upper troposphere. These findings provide a framework to develop new metrics for the detection of global warming impacts to the hydrological cycle. Further, currently available satellite missions measure δD in the atmospheric boundary layer, the free atmosphere, or the

  3. Hydrological Cycle in the Heihe River Basin and Its Implication for Water Resource Management in Endorheic Basins

    Science.gov (United States)

    Li, Xin; Cheng, Guodong; Ge, Yingchun; Li, Hongyi; Han, Feng; Hu, Xiaoli; Tian, Wei; Tian, Yong; Pan, Xiaoduo; Nian, Yanyun; Zhang, Yanlin; Ran, Youhua; Zheng, Yi; Gao, Bing; Yang, Dawen; Zheng, Chunmiao; Wang, Xusheng; Liu, Shaomin; Cai, Ximing

    2018-01-01

    Endorheic basins around the world are suffering from water and ecosystem crisis. To pursue sustainable development, quantifying the hydrological cycle is fundamentally important. However, knowledge gaps exist in how climate change and human activities influence the hydrological cycle in endorheic basins. We used an integrated ecohydrological model, in combination with systematic observations, to analyze the hydrological cycle in the Heihe River Basin, a typical endorheic basin in arid region of China. The water budget was closed for different landscapes, river channel sections, and irrigation districts of the basin from 2001 to 2012. The results showed that climate warming, which has led to greater precipitation, snowmelt, glacier melt, and runoff, is a favorable factor in alleviating water scarcity. Human activities, including ecological water diversion, cropland expansion, and groundwater overexploitation, have both positive and negative effects. The natural oasis ecosystem has been restored considerably, but the overuse of water in midstream and the use of environmental flow for agriculture in downstream have exacerbated the water stress, resulting in unfavorable changes in surface-ground water interactions and raising concerns regarding how to fairly allocate water resources. Our results suggest that the water resource management in the region should be adjusted to adapt to a changing hydrological cycle, cropland area must be reduced, and the abstraction of groundwater must be controlled. To foster long-term benefits, water conflicts should be handled from a broad socioeconomic perspective. The findings can provide useful information on endorheic basins to policy makers and stakeholders around the world.

  4. EDITORIAL: The Earth radiation balance as driver of the global hydrological cycle

    Science.gov (United States)

    Wild, Martin; Liepert, Beate

    2010-06-01

    Variations in the intensity of the global hydrological cycle can have far-reaching effects on living conditions on our planet. While climate change discussions often revolve around possible consequences of future temperature changes, the adaptation to changes in the hydrological cycle may pose a bigger challenge to societies and ecosystems. Floods and droughts are already today amongst the most damaging natural hazards, with floods being globally the most significant disaster type in terms of loss of human life (Jonkman 2005). From an economic perspective, changes in the hydrological cycle can impose great pressures and damages on a variety of industrial sectors, such as water management, urban planning, agricultural production and tourism. Despite their obvious environmental and societal importance, our understanding of the causes and magnitude of the variations of the hydrological cycle is still unsatisfactory (e.g., Ramanathan et al 2001, Ohmura and Wild 2002, Allen and Ingram 2002, Allan 2007, Wild et al 2008, Liepert and Previdi 2009). The link between radiation balance and hydrological cycle Globally, precipitation can be approximated by surface evaporation, since the variability of the atmospheric moisture storage is negligible. This is the case because the fluxes are an order of magnitude larger than the atmospheric storage (423 x 1012 m3 year-1 versus 13 x 1012 m3 according to Baumgartner and Reichel (1975)), the latter being determined by temperature (Clausius-Clapeyron). Hence the residence time of evaporated water in the atmosphere is not more than a few days, before it condenses and falls back to Earth in the form of precipitation. Any change in the globally averaged surface evaporation therefore implies an equivalent change in precipitation, and thus in the intensity of the global hydrological cycle. The process of evaporation requires energy, which it obtains from the surface radiation balance (also known as surface net radiation), composed of the

  5. Hydrologic connectivity to streams increases nitrogen and phosphorus inputs and cycling in soils of created and natural floodplain wetlands

    Science.gov (United States)

    Wolf, Kristin L.; Noe, Gregory; Ahn, Changwoo

    2013-01-01

    Greater connectivity to stream surface water may result in greater inputs of allochthonous nutrients that could stimulate internal nitrogen (N) and phosphorus (P) cycling in natural, restored, and created riparian wetlands. This study investigated the effects of hydrologic connectivity to stream water on soil nutrient fluxes in plots (n = 20) located among four created and two natural freshwater wetlands of varying hydrology in the Piedmont physiographic province of Virginia. Surface water was slightly deeper; hydrologic inputs of sediment, sediment-N, and ammonium were greater; and soil net ammonification, N mineralization, and N turnover were greater in plots with stream water classified as their primary water source compared with plots with precipitation or groundwater as their primary water source. Soil water-filled pore space, inputs of nitrate, and soil net nitrification, P mineralization, and denitrification enzyme activity (DEA) were similar among plots. Soil ammonification, N mineralization, and N turnover rates increased with the loading rate of ammonium to the soil surface. Phosphorus mineralization and ammonification also increased with sedimentation and sediment-N loading rate. Nitrification flux and DEA were positively associated in these wetlands. In conclusion, hydrologic connectivity to stream water increased allochthonous inputs that stimulated soil N and P cycling and that likely led to greater retention of sediment and nutrients in created and natural wetlands. Our findings suggest that wetland creation and restoration projects should be designed to allow connectivity with stream water if the goal is to optimize the function of water quality improvement in a watershed.

  6. Albedo enhancement of marine clouds to counteract global warming: impacts on the hydrological cycle

    Energy Technology Data Exchange (ETDEWEB)

    Bala, G. [Indian Institute of Science, Divecha Center for Climate Change, Bangalore (India); Indian Institute of Science, Center for Atmospheric and Oceanic Sciences, Bangalore (India); Caldeira, Ken; Cao, Long; Ban-Weiss, George; Shin, Ho-Jeong [Carnegie Institution, Department of Global Ecology, Stanford, CA (United States); Nemani, Rama [NASA Ames Research Center, Moffett Field, CA (United States)

    2011-09-15

    Recent studies have shown that changes in solar radiation affect the hydrological cycle more strongly than equivalent CO{sub 2} changes for the same change in global mean surface temperature. Thus, solar radiation management ''geoengineering'' proposals to completely offset global mean temperature increases by reducing the amount of absorbed sunlight might be expected to slow the global water cycle and reduce runoff over land. However, proposed countering of global warming by increasing the albedo of marine clouds would reduce surface solar radiation only over the oceans. Here, for an idealized scenario, we analyze the response of temperature and the hydrological cycle to increased reflection by clouds over the ocean using an atmospheric general circulation model coupled to a mixed layer ocean model. When cloud droplets are reduced in size over all oceans uniformly to offset the temperature increase from a doubling of atmospheric CO{sub 2}, the global-mean precipitation and evaporation decreases by about 1.3% but runoff over land increases by 7.5% primarily due to increases over tropical land. In the model, more reflective marine clouds cool the atmospheric column over ocean. The result is a sinking motion over oceans and upward motion over land. We attribute the increased runoff over land to this increased upward motion over land when marine clouds are made more reflective. Our results suggest that, in contrast to other proposals to increase planetary albedo, offsetting mean global warming by reducing marine cloud droplet size does not necessarily lead to a drying, on average, of the continents. However, we note that the changes in precipitation, evaporation and P-E are dominated by small but significant areas, and given the highly idealized nature of this study, a more thorough and broader assessment would be required for proposals of altering marine cloud properties on a large scale. (orig.)

  7. The potential roles of biological soil crusts in dryland hydrologic cycles

    Science.gov (United States)

    Belnap, J.

    2006-01-01

    Biological soil crusts (BSCs) are the dominant living cover in many drylands of the world. They possess many features that can influence different aspects of local hydrologic cycles, including soil porosity, absorptivity, roughness, aggregate stability, texture, pore formation, and water retention. The influence of biological soil crusts on these factors depends on their internal and external structure, which varies with climate, soil, and disturbance history. This paper presents the different types of biological soil crusts, discusses how crust type likely influences various aspects of the hydrologic cycle, and reviews what is known and not known about the influence of biological crusts on sediment production and water infiltration versus runoff in various drylands around the world. Most studies examining the effect of biological soil crusts on local hydrology are done by comparing undisturbed sites with those recently disturbed by the researchers. Unfortunately, this greatly complicates interpretation of the results. Applied disturbances alter many soil features such as soil texture, roughness, aggregate stability, physical crusting, porosity, and bulk density in ways that would not necessarily be the same if crusts were not naturally present. Combined, these studies show little agreement on how biological crusts affect water infiltration or runoff. However, when studies are separated by biological crust type and utilize naturally occurring differences among these types, results indicate that biological crusts in hyperarid regions reduce infiltration and increase runoff, have mixed effects in and regions, and increase infiltration and reduce runoff in semiarid cool and cold drylands. However, more studies are needed before broad generalizations can be made on how biological crusts affect infiltration and runoff. We especially need studies that control for sub-surface soil features such as bulk density, micro- and macropores, and biological crust structure. Unlike

  8. Assessment of variability in the hydrological cycle of the Loess Plateau, China: examining dependence structures of hydrological processes

    Science.gov (United States)

    Guo, A.; Wang, Y.

    2017-12-01

    Investigating variability in dependence structures of hydrological processes is of critical importance for developing an understanding of mechanisms of hydrological cycles in changing environments. In focusing on this topic, present work involves the following: (1) identifying and eliminating serial correlation and conditional heteroscedasticity in monthly streamflow (Q), precipitation (P) and potential evapotranspiration (PE) series using the ARMA-GARCH model (ARMA: autoregressive moving average; GARCH: generalized autoregressive conditional heteroscedasticity); (2) describing dependence structures of hydrological processes using partial copula coupled with the ARMA-GARCH model and identifying their variability via copula-based likelihood-ratio test method; and (3) determining conditional probability of annual Q under different climate scenarios on account of above results. This framework enables us to depict hydrological variables in the presence of conditional heteroscedasticity and to examine dependence structures of hydrological processes while excluding the influence of covariates by using partial copula-based ARMA-GARCH model. Eight major catchments across the Loess Plateau (LP) are used as study regions. Results indicate that (1) The occurrence of change points in dependence structures of Q and P (PE) varies across the LP. Change points of P-PE dependence structures in all regions almost fully correspond to the initiation of global warming, i.e., the early 1980s. (3) Conditional probabilities of annual Q under various P and PE scenarios are estimated from the 3-dimensional joint distribution of (Q, P and PE) based on the above change points. These findings shed light on mechanisms of the hydrological cycle and can guide water supply planning and management, particularly in changing environments.

  9. Description of climate, surface hydrology, and near-surface hydrogeology. Simpevarp 1.2

    International Nuclear Information System (INIS)

    Werner, Kent; Bosson, Emma; Berglund, Sten

    2005-04-01

    combination of site investigation data and generic/regional data. Furthermore, the use of data from other disciplines and models as supporting evidence is discussed and exemplified.The quantitative flow modelling is performed using two different tools, a GIS-based hydrological model and the process-based MIKE SHE model. The GIS model simulates steady-state flow conditions, and uses the specific discharge (must be estimated separately) and the Digital Elevation Model (DEM) as the only inputs. The MIKE SHE model simulates the whole transient hydrological cycle, including unsaturated flow and saturated groundwater flow, as well as surface water flow. The GIS-based flow modelling is performed for the whole regional model area. The results illustrate the overall surface and near-surface water flow pattern in the model area, as well as the distribution of recharge and discharge areas. The model is also used to compare model-calculated and real water courses, and model-calculated and field-checked catchment area boundaries. The MIKE SHE modelling is focused on the catchment area 'Simpevarp 7', where Lake Frisksjoen is located. This is also the area considered in the ecological systems modelling. The model is applied to quantify the water balance of the catchment area and to illustrate the three-dimensional groundwater flow system, from a depth of 150 m below sea level up to the ground surface. The hydraulic properties of the fractured rock and the pressure at the bottom boundary are imported from the Simpevarp 1.1 modelling of groundwater flow in the rock. In addition, the MIKE SHE modelling results illustrate the variations in the distribution of recharge and discharge areas during the year, using transient, high resolution data for a selected 'representative' year to describe the meteorological conditions. Based on the results from the conceptual, descriptive and quantitative flow modelling, uncertainties in the present model version are identified and discussed. The main

  10. Description of climate, surface hydrology, and near-surface hydrogeology. Simpevarp 1.2

    Energy Technology Data Exchange (ETDEWEB)

    Werner, Kent [SWECO VIAK AB/Golder Associates AB, Stockholm (Sweden); Bosson, Emma; Berglund, Sten [Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden)

    2005-04-01

    combination of site investigation data and generic/regional data. Furthermore, the use of data from other disciplines and models as supporting evidence is discussed and exemplified.The quantitative flow modelling is performed using two different tools, a GIS-based hydrological model and the process-based MIKE SHE model. The GIS model simulates steady-state flow conditions, and uses the specific discharge (must be estimated separately) and the Digital Elevation Model (DEM) as the only inputs. The MIKE SHE model simulates the whole transient hydrological cycle, including unsaturated flow and saturated groundwater flow, as well as surface water flow. The GIS-based flow modelling is performed for the whole regional model area. The results illustrate the overall surface and near-surface water flow pattern in the model area, as well as the distribution of recharge and discharge areas. The model is also used to compare model-calculated and real water courses, and model-calculated and field-checked catchment area boundaries. The MIKE SHE modelling is focused on the catchment area 'Simpevarp 7', where Lake Frisksjoen is located. This is also the area considered in the ecological systems modelling. The model is applied to quantify the water balance of the catchment area and to illustrate the three-dimensional groundwater flow system, from a depth of 150 m below sea level up to the ground surface. The hydraulic properties of the fractured rock and the pressure at the bottom boundary are imported from the Simpevarp 1.1 modelling of groundwater flow in the rock. In addition, the MIKE SHE modelling results illustrate the variations in the distribution of recharge and discharge areas during the year, using transient, high resolution data for a selected 'representative' year to describe the meteorological conditions. Based on the results from the conceptual, descriptive and quantitative flow modelling, uncertainties in the present model version are identified and

  11. Wetter subtropics in a warmer world: Contrasting past and future hydrological cycles

    Science.gov (United States)

    Burls, Natalie J.; Fedorov, Alexey V.

    2017-12-01

    During the warm Miocene and Pliocene Epochs, vast subtropical regions had enough precipitation to support rich vegetation and fauna. Only with global cooling and the onset of glacial cycles some 3 Mya, toward the end of the Pliocene, did the broad patterns of arid and semiarid subtropical regions become fully developed. However, current projections of future global warming caused by CO2 rise generally suggest the intensification of dry conditions over these subtropical regions, rather than the return to a wetter state. What makes future projections different from these past warm climates? Here, we investigate this question by comparing a typical quadrupling-of-CO2 experiment with a simulation driven by sea-surface temperatures closely resembling available reconstructions for the early Pliocene. Based on these two experiments and a suite of other perturbed climate simulations, we argue that this puzzle is explained by weaker atmospheric circulation in response to the different ocean surface temperature patterns of the Pliocene, specifically reduced meridional and zonal temperature gradients. Thus, our results highlight that accurately predicting the response of the hydrological cycle to global warming requires predicting not only how global mean temperature responds to elevated CO2 forcing (climate sensitivity) but also accurately quantifying how meridional sea-surface temperature patterns will change (structural climate sensitivity).

  12. Responses of the Tropical Atmospheric Circulation to Climate Change and Connection to the Hydrological Cycle

    Science.gov (United States)

    Ma, Jian; Chadwick, Robin; Seo, Kyong-Hwan; Dong, Changming; Huang, Gang; Foltz, Gregory R.; Jiang, Jonathan H.

    2018-05-01

    This review describes the climate change–induced responses of the tropical atmospheric circulation and their impacts on the hydrological cycle. We depict the theoretically predicted changes and diagnose physical mechanisms for observational and model-projected trends in large-scale and regional climate. The tropical circulation slows down with moisture and stratification changes, connecting to a poleward expansion of the Hadley cells and a shift of the intertropical convergence zone. Redistributions of regional precipitation consist of thermodynamic and dynamical components, including a strong offset between moisture increase and circulation weakening throughout the tropics. This allows other dynamical processes to dominate local circulation changes, such as a surface warming pattern effect over oceans and multiple mechanisms over land. To improve reliability in climate projections, more fundamental understandings of pattern formation, circulation change, and the balance of various processes redistributing land rainfall are suggested to be important.

  13. Towards an Improved Represenation of Reservoirs and Water Management in a Land Surface-Hydrology Model

    Science.gov (United States)

    Yassin, F.; Anis, M. R.; Razavi, S.; Wheater, H. S.

    2017-12-01

    Water management through reservoirs, diversions, and irrigation have significantly changed river flow regimes and basin-wide energy and water balance cycles. Failure to represent these effects limits the performance of land surface-hydrology models not only for streamflow prediction but also for the estimation of soil moisture, evapotranspiration, and feedbacks to the atmosphere. Despite recent research to improve the representation of water management in land surface models, there remains a need to develop improved modeling approaches that work in complex and highly regulated basins such as the 406,000 km2 Saskatchewan River Basin (SaskRB). A particular challenge for regional and global application is a lack of local information on reservoir operational management. To this end, we implemented a reservoir operation, water abstraction, and irrigation algorithm in the MESH land surface-hydrology model and tested it over the SaskRB. MESH is Environment Canada's Land Surface-hydrology modeling system that couples Canadian Land Surface Scheme (CLASS) with hydrological routing model. The implemented reservoir algorithm uses an inflow-outflow relationship that accounts for the physical characteristics of reservoirs (e.g., storage-area-elevation relationships) and includes simplified operational characteristics based on local information (e.g., monthly target volume and release under limited, normal, and flood storage zone). The irrigation algorithm uses the difference between actual and potential evapotranspiration to estimate irrigation water demand. This irrigation demand is supplied from the neighboring reservoirs/diversion in the river system. We calibrated the model enabled with the new reservoir and irrigation modules in a multi-objective optimization setting. Results showed that the reservoir and irrigation modules significantly improved the MESH model performance in generating streamflow and evapotranspiration across the SaskRB and that this our approach provides

  14. Land-surface modelling in hydrological perspective ? a review

    OpenAIRE

    Overgaard , J.; Rosbjerg , D.; Butts , M. B.

    2006-01-01

    International audience; The purpose of this paper is to provide a review of the different types of energy-based land-surface models (LSMs) and discuss some of the new possibilities that will arise when energy-based LSMs are combined with distributed hydrological modelling. We choose to focus on energy-based approaches, because in comparison to the traditional potential evapotranspiration models, these approaches allow for a stronger link to remote sensing and atmospheric modelling. New opport...

  15. Surface hydrologic investigations of the Columbia Plateau Region, Washington

    International Nuclear Information System (INIS)

    Leonhart, L.S.

    1979-07-01

    The Washington State portion of the Columbia Plateau is divided into six hydrologic sub-basins on the basis of the principal surface drainage systems present, structural and topographic relationships, and political and other considerations. Baseline descriptions of the surface water systems and resources are presented for the Columbia Plateau with emphasis on the Pasco Sub-basin. A preliminary evaluation of the hydrologic budget for each sub-basin is derived. For each sub-basin, recharge/discharge relationships arising from precipitation/evapotranspiration/runoff, stream losses and gains, and artificial mechanisms are determined on the basis of available data. The net exchange between surface and groundwater systems is evaluated and relative estimates of the net groundwater flow into or out of the sub-basin are obtained. An evaluation is made of hydrologic risk factors arising from: (1) tributary flooding in eastern Washington; and, (2) major flooding of the Columbia River within the Pasco Sub-basin. Scenarios are presented for credible natural and man-generated catastrophic events

  16. Surface hydrologic investigations of the Columbia Plateau region, Washington

    International Nuclear Information System (INIS)

    Leonhart, L.S.

    1979-01-01

    The Washington State portion of the Columbia Plateau is divided into six hydrologic sub-basins on the basis of the principal surface drainage systems present, structural and topographic relationships, and political and other considerations. Baseline descriptions of the surface water systems and resources are presented for the Columbia Plateau with emphasis on the Pasco Sub-basin. A preliminary evaluation of the hydrologic budget for each sub-basin is derived. For each sub-basin, recharge/discharge relationships arising from precipitation/evapotranspiration/runoff, stream losses and gains, and artificial mechanisms are determined on the basis of available data. The net exchange between surface and ground-water systems is evaluated and relative estimates of the net ground-water flow into or out of the sub-basin are obtained. An evaluation is made of hydrologic risk factors arising from: (1) tributary flooding in eastern Washington; and (2) major flooding of the Columbia River within the Pasco Sub-basin. Scenarios are presented for credible natural and man-generated catastrophic events

  17. Tritium and other environmental isotopes in the hydrological cycle

    Energy Technology Data Exchange (ETDEWEB)

    1967-04-01

    It is common knowledge that water world resources are being increasingly strained to meet the requirements of the growth of population, industry and agriculture. Nuclear techniques are being applied to the problem of water shortage in two quite different ways: in nuclear desalination, and in hydrological investigations and development. The use of isotopes in hydrological investigation is, however, not very widely known. One of the principal obstacles to the application of the environmental isotopes by the hydrologist is that there is relatively little information on the techniques in the literature. This report attempts to improve that situation - principally for tritium - by assembling information on such matters as the precipitation of tritium, its input into the ground-water, and sampling techniques. Refs, figs and tabs.

  18. Geochemical, hydrological, and biological cycling of energy residual. Research plan

    International Nuclear Information System (INIS)

    Wobber, F.J.

    1983-03-01

    Proposed research goals and specific research areas designed to provide a base of fundamental scientific information so that the geochemical, hydrological, and biophysical mechanisms that contribute to the transport and long term fate of energy residuals in natural systems can be understood are described. Energy development and production have resulted in a need for advanced scientific information on the geochemical transformations, transport rates, and potential for bioaccumulation of contaminants in subsurface environments

  19. The influence of the hydrologic cycle on the extent of sea ice with climatic implications

    Science.gov (United States)

    Dean, Ken; Gosink, Joan

    1991-01-01

    The role was analyzed of the hydrologic cycle on the distribution of sea ice, and its influence on forcings and fluxes between the marine environment and the atmosphere. River discharge plays a significant role in degrading the sea ice before any melting occurs elsewhere along the coast. The influence is considered of river discharge on the albedo, thermal balance, and distribution of sea ice. Quantitative atmospheric-hydrologic models are being developed to describe these processes in the coastal zone. Input for the models will come from satellite images, hydrologic data, and field observations. The resulting analysis provides a basis for the study of the significance of the hydrologic cycle throughout the Arctic Basin and its influence on the regional climate as a result of possible climatic scenarios. The area offshore from the Mackenzie River delta was selected as the study area.

  20. Surface and near-surface hydrological model of Olkiluoto island

    International Nuclear Information System (INIS)

    Karvonen, T.

    2008-04-01

    The aim of the study was to develop a 3D-model that calculates the overall water balance components of Olkiluoto Island in the present-day condition utilizing the existing extensive data sets available. The model links the unsaturated and saturated soil water in the overburden and groundwater in bedrock to a continuous pressure system. The parameterization of land use and vegetation was done in such a way that the model can later on be used for description of the past evolution of the overburden hydrology at the site and overburden's hydrological evolution in the future. Measured groundwater level in overburden tubes, pressure heads in shallow bedrock holes, snow depth, soil temperature, frost depth and discharge measurements were used in assessing the performance of the models in the calibration period (01.05.2001- 31.12.2005). Computed groundwater level variation can be characterized by variables ΔH MEAS and ΔH COMP , which are the difference between maximum and minimum measured and computed groundwater level value during the calibration period. Average ΔH MEAS for all tubes located in fine-textured till soil was 1.99 m and the corresponding computed value ΔH COMP was 1.83 m. Average ΔH MEAS for all tubes located in sandy till soil was 2.12 m and the corresponding computed value ΔH COMP was 1.93 m. The computed results indicate that in future studies it is necessary to divide the two most important soil types into several subclasses. In the present study the uncertainty and sensitivity analysis was carried out through a parameter uncertainty framework known as GLUE. According to the uncertainty analysis the average yearly runoff was around 175 mm a -1 and 50 % confidence limits were 155 and 195 mm a -1 . Measured average yearly runoff during the calibration period was 190 mm a -1 . Average yearly evapotranspiration estimate was 310 mm a -1 and the 50 % confidence limits were 290 and 330 mm a -1 . Average value for recharge through the bedrock system was 1

  1. Recent Acceleration of the Terrestrial Hydrologic Cycle in the U.S. Midwest

    Science.gov (United States)

    Yeh, Pat J.-F.; Wu, Chuanhao

    2018-03-01

    Most hydroclimatic trend studies considered only a subset of water budget variables; hence, the trend consistency and a holistic assessment of hydrologic changes across the entire water cycle cannot be evaluated. Here we use a unique 31 year (1983-2013) observed data set in Illinois (a representative region of the U.S. Midwest), including temperature (T), precipitation (P), evaporation (E), streamflow (R), soil moisture, and groundwater level (GWL), to estimate the trends and their sensitivity to different data periods and lengths. Both the Mann-Kendall trend test and the least squares linear method identify trends in close agreement. Despite no clear trends during 1983-2013, increasing trends are found in P (8.73-9.05 mm/year), E (6.87-7.47 mm/year), and R (1.57-3.54 mm/year) during 1992-2013, concurrently with a pronounced warming trend of 0.029-0.037 °C/year. However, terrestrial water storageis decreased by -2.0 mm/year (mainly due to declining GWL), suggesting that the increased R is caused by increased surface runoff rather than baseflow. Monthly analyses identify warming trends for all months except winter. In summer, P (E) exhibits an increasing (decreasing) trend, leading to increasing R, soil moisture, GWL, and terrestrial water storage. Most trends estimated for different subperiods are found to be sensitive to data lengths and periods. Overall, this study provides an internally consistent observed evidence on the intensification of the hydrologic cycle in response to recent climate warming in U.S. Midwest, in agreement with and well supported by several recent studies consistently reporting the increased P, R and E over the Midwest and Mississippi River basin.

  2. Hydrological cycle research by D & 18 O tracing in small watershed in the loess hilly region

    Directory of Open Access Journals (Sweden)

    Xu Xuexuan

    2013-12-01

    Full Text Available The objective of this study was to determine the mechanisms of the hydrologic cycle in the loess area in China. Sixty eight water samples from precipitation, soil water of the 0 – 4 m layer, surface water in the valley, ground water (spring and well were collected and the Deuterium (D and Oxygen – 18 (O of these water samples were analyzed to interpret the relationship among those waters in the watershed in the loess hilly region during 2005 – 2009. The results show that: the D & 18O of precipitation in Yangou was consistent with that of Xi'an, apparently the north migration of water vapor in Xi'an; according to the correlations among the differential waters in D & 18 O, confirmed that precipitation recharge could account for most of the sources of valley flow, with part of the recharge water going to soil water recharge. The D & 18O of groundwater were very close to that of precipitation, likely the soil preferential flow was dominant in groundwater recharge although the infiltration had a certain lag. Under the influence of rainfall and evaporation, the response of the soil moisture profile, and its D & 18O profile were different. The soil moisture had the strong influenced layer in the 0 60 cm range, a weak impacted layer in 60 160 cm, and a stable layer below 160 cm. It was shown that the soil evaporation depth could be up to 160 cm because the D & 18O changed in that depth. The study could increase our understanding of the magnitude and pattern of the hydrologic cycle, which should improve water resources management in the watershed scale.

  3. Assessment and Enhancement of MERRA Land Surface Hydrology Estimates

    Science.gov (United States)

    Reichle, Rolf H.; Koster, Randal D.; deLannoy, Gabrielle J. M.; Forman, Barton A.; Liu, Qing; Mahanama, Sarith P. P.; Toure, Ally

    2012-01-01

    The Modern-Era Retrospective analysis for Research and Applications (MERRA) is a state-ofthe-art reanalysis that provides, in addition to atmospheric fields, global estimates of soil moisture, latent heat flux, snow, and runoff for 1979-present. This study introduces a supplemental and improved set of land surface hydrological fields ("MERRA-Land") generated by re-running a revised version of the land component of the MERRA system. Specifically, the MERRA-Land estimates benefit from corrections to the precipitation forcing with the Global Precipitation Climatology Project pentad product (version 2.1) and from revised parameter values in the rainfall interception model, changes that effectively correct for known limitations in the MERRA surface meteorological forcings. The skill (defined as the correlation coefficient of the anomaly time series) in land surface hydrological fields from MERRA and MERRA-Land is assessed here against observations and compared to the skill of the state-of-the-art ERA-Interim (ERA-I) reanalysis. MERRA-Land and ERA-I root zone soil moisture skills (against in situ observations at 85 US stations) are comparable and significantly greater than that of MERRA. Throughout the northern hemisphere, MERRA and MERRA-Land agree reasonably well with in situ snow depth measurements (from 583 stations) and with snow water equivalent from an independent analysis. Runoff skill (against naturalized stream flow observations from 18 US basins) of MERRA and MERRA-Land is typically higher than that of ERA-I. With a few exceptions, the MERRA-Land data appear more accurate than the original MERRA estimates and are thus recommended for those interested in using MERRA output for land surface hydrological studies.

  4. Evaluating the hydrological consistency of satellite based water cycle components

    KAUST Repository

    Lopez Valencia, Oliver Miguel; Houborg, Rasmus; McCabe, Matthew

    2016-01-01

    observation. Basin-scale studies have shown considerable variability in achieving water budget closure with any degree of accuracy using satellite estimates of the water cycle. In order to assess the suitability of this type of approach for evaluating

  5. A Model-Model and Data-Model Comparison for the Early Eocene Hydrological Cycle

    Science.gov (United States)

    Carmichael, Matthew J.; Lunt, Daniel J.; Huber, Matthew; Heinemann, Malte; Kiehl, Jeffrey; LeGrande, Allegra; Loptson, Claire A.; Roberts, Chris D.; Sagoo, Navjit; Shields, Christine

    2016-01-01

    A range of proxy observations have recently provided constraints on how Earth's hydrological cycle responded to early Eocene climatic changes. However, comparisons of proxy data to general circulation model (GCM) simulated hydrology are limited and inter-model variability remains poorly characterised. In this work, we undertake an intercomparison of GCM-derived precipitation and P - E distributions within the extended EoMIP ensemble (Eocene Modelling Intercomparison Project; Lunt et al., 2012), which includes previously published early Eocene simulations performed using five GCMs differing in boundary conditions, model structure, and precipitation-relevant parameterisation schemes. We show that an intensified hydrological cycle, manifested in enhanced global precipitation and evaporation rates, is simulated for all Eocene simulations relative to the preindustrial conditions. This is primarily due to elevated atmospheric paleo-CO2, resulting in elevated temperatures, although the effects of differences in paleogeography and ice sheets are also important in some models. For a given CO2 level, globally averaged precipitation rates vary widely between models, largely arising from different simulated surface air temperatures. Models with a similar global sensitivity of precipitation rate to temperature (dP=dT ) display different regional precipitation responses for a given temperature change. Regions that are particularly sensitive to model choice include the South Pacific, tropical Africa, and the Peri-Tethys, which may represent targets for future proxy acquisition. A comparison of early and middle Eocene leaf-fossil-derived precipitation estimates with the GCM output illustrates that GCMs generally underestimate precipitation rates at high latitudes, although a possible seasonal bias of the proxies cannot be excluded. Models which warm these regions, either via elevated CO2 or by varying poorly constrained model parameter values, are most successful in simulating a

  6. The role of interception in the hydrological cycle

    NARCIS (Netherlands)

    Gerrits, A.M.J.

    2010-01-01

    Interception is the part of the rainfall that is intercepted by the earth’s surface and which subsequently evaporates. In this definition the earth’s surface includes everything that becomes wet after a rainfall event and that dries out soon after. It includes: vegetation, soil surface, litter,

  7. Can we Observe and Assess Whether the Global Hydrological Cycle is "Intensifying"?

    Science.gov (United States)

    Wood, E. F.; Sheffield, J.

    2012-12-01

    There is controversy over whether the hydrological cycle is "intensifying" (or "accelerating"), and if so how and where? Resolving this critical question is a central goal of both national (e.g. NASA's Energy and Water cycle Study: NEWS) and international (WCRP Global Energy and Water cycle Experiment: GEWEX) programs. Its resolution has significant implications for understanding changes in hydroclimatic states and variability, and in future water security at regional to global scales. Over the last decade a number of papers have addressed trends and change in specific water cycle variables with results that can best be described as inconclusive, regardless of the conclusions of specific papers. In this presentation a number of recent studies will be reviewed for their consistency in assessing whether collectively one can make conclusions regarding how the hydrologic cycle is changing. The presentation will also demonstrate a pathway for analyzing where to observe for the detection of change based on a NASA-supported, global, 1983-2009, terrestrial water cycle Earth System Data Record project being led by the author. Initial results will be presented and a discussion presented on the extent that the proposed strategy can be used to detect change in the terrestrial hydrological cycle.

  8. Hydrologic connectivity to streams increases nitrogen and phosphorus inputs and cycling in soils of created and natural floodplain wetlands.

    Science.gov (United States)

    Wolf, Kristin L; Noe, Gregory B; Ahn, Changwoo

    2013-07-01

    Greater connectivity to stream surface water may result in greater inputs of allochthonous nutrients that could stimulate internal nitrogen (N) and phosphorus (P) cycling in natural, restored, and created riparian wetlands. This study investigated the effects of hydrologic connectivity to stream water on soil nutrient fluxes in plots ( = 20) located among four created and two natural freshwater wetlands of varying hydrology in the Piedmont physiographic province of Virginia. Surface water was slightly deeper; hydrologic inputs of sediment, sediment-N, and ammonium were greater; and soil net ammonification, N mineralization, and N turnover were greater in plots with stream water classified as their primary water source compared with plots with precipitation or groundwater as their primary water source. Soil water-filled pore space, inputs of nitrate, and soil net nitrification, P mineralization, and denitrification enzyme activity (DEA) were similar among plots. Soil ammonification, N mineralization, and N turnover rates increased with the loading rate of ammonium to the soil surface. Phosphorus mineralization and ammonification also increased with sedimentation and sediment-N loading rate. Nitrification flux and DEA were positively associated in these wetlands. In conclusion, hydrologic connectivity to stream water increased allochthonous inputs that stimulated soil N and P cycling and that likely led to greater retention of sediment and nutrients in created and natural wetlands. Our findings suggest that wetland creation and restoration projects should be designed to allow connectivity with stream water if the goal is to optimize the function of water quality improvement in a watershed. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  9. A perturbed hydrological cycle during Oceanic Anoxic Event 2

    NARCIS (Netherlands)

    van Helmond, N.A.G.M.; Sluijs, A.; Reichart, G.J; Sinninghe Damsté, J.S.; Slomp, C.P.; Brinkhuis, H.

    2014-01-01

    The Late Cretaceous Oceanic Anoxic Event 2 (OAE2; ca. 94 Ma) was one of the largest global carbon cycle perturbations during the Phanerozoic. OAE2 represents an important, although extreme, case study for modern trends because widespread anoxia and enhanced organic carbon burial during OAE2 were

  10. Assimilation of ASCAT near-surface soil moisture into the French SIM hydrological model

    Science.gov (United States)

    Draper, C.; Mahfouf, J.-F.; Calvet, J.-C.; Martin, E.; Wagner, W.

    2011-06-01

    The impact of assimilating near-surface soil moisture into the SAFRAN-ISBA-MODCOU (SIM) hydrological model over France is examined. Specifically, the root-zone soil moisture in the ISBA land surface model is constrained over three and a half years, by assimilating the ASCAT-derived surface degree of saturation product, using a Simplified Extended Kalman Filter. In this experiment ISBA is forced with the near-real time SAFRAN analysis, which analyses the variables required to force ISBA from relevant observations available before the real time data cut-off. The assimilation results are tested against ISBA forecasts generated with a higher quality delayed cut-off SAFRAN analysis. Ideally, assimilating the ASCAT data will constrain the ISBA surface state to correct for errors in the near-real time SAFRAN forcing, the most significant of which was a substantial dry bias caused by a dry precipitation bias. The assimilation successfully reduced the mean root-zone soil moisture bias, relative to the delayed cut-off forecasts, by close to 50 % of the open-loop value. The improved soil moisture in the model then led to significant improvements in the forecast hydrological cycle, reducing the drainage, runoff, and evapotranspiration biases (by 17 %, 11 %, and 70 %, respectively). When coupled to the MODCOU hydrogeological model, the ASCAT assimilation also led to improved streamflow forecasts, increasing the mean discharge ratio, relative to the delayed cut off forecasts, from 0.68 to 0.76. These results demonstrate that assimilating near-surface soil moisture observations can effectively constrain the SIM model hydrology, while also confirming the accuracy of the ASCAT surface degree of saturation product. This latter point highlights how assimilation experiments can contribute towards the difficult issue of validating remotely sensed land surface observations over large spatial scales.

  11. Transfer of nuclides from the water phase to the sediments during normal and extraordinary hydrological cycles

    International Nuclear Information System (INIS)

    1985-07-01

    Atucha I and Atucha II nuclear power plants are located on the right margin of the Parana de las Palmas river. This river belongs to the Cuenca del Plata, whose 1982-1983 hydrologic cycle registered the greatest freshets of the century. Works and studies previously fixed had to be altered and investigations were adapted to the possibilities and the particular hydric conditions verified. Considerations on the transfer of nuclides between water and sediments are presented. The floods reduce the water-sediments contact time on the bed of the river. In outer areas, the waters labelled by the nuclear power plant effluent discharge favor the infiltration in alluvial soils, as well as the exchange with the sediments. The investigations carried out for the phase near to the discharge of liquid effluents (related to the critical group) made possible to prove the characteristics of the path of the liquid wastes released, the distribution coefficient and the fixation or penetrability of some nuclides in soils of the floody valley. In this manner, a balance of radioactive nuclides incorporated to soils and sediments from the neighbourhood of Atucha and the water-course of Parana de las Palmas river is obtained. The presence of 60 Co and 137 Cs in the floody soils on the right margin of this river was detected and measured during the greatest flood of the century. On the other hand, 144 Ce, 51 Cr, 106 Ru and 90 Sr have not been detected. The detection of artificial radioisotopes turns out to be impossible in normal hydrological years, even in the sorroundings of the nuclear power plant or the critical group (from the point of view of the surface waters, The Fishing Club, 3 km down stream). (M.E.L.) [es

  12. Impact of vegetation dynamics on hydrological processes in a semi-arid basin by using a land surface-hydrology coupled model

    Energy Technology Data Exchange (ETDEWEB)

    Jiao, Yang; Lei, Huimin; Yang, Dawen; Huang, Maoyi; Liu, Dengfeng; Yuan, Xing

    2017-08-01

    Land surface models (LSMs) are widely used to understand the interactions between hydrological processes and vegetation dynamics, which is important for the attribution and prediction of regional hydrological variations. However, most LSMs have large uncertainties in their representations of ecohydrological processes due to deficiencies in hydrological parameterizations. In this study, the Community Land Model version 4 (CLM4) LSM was modified with an advanced runoff generation and flow routing scheme, resulting in a new land surface-hydrology coupled model, CLM-GBHM. Both models were implemented in the Wudinghe River Basin (WRB), which is a semi-arid basin located in the middle reaches of the Yellow River, China. Compared with CLM, CLM-GBHM increased the Nash Sutcliffe efficiency for daily river discharge simulation (1965–1969) from 0.03 to 0.23 and reduced the relative bias in water table depth simulations (2010–2012) from 32.4% to 13.4%. The CLM-GBHM simulations with static, remotely sensed and model-predicted vegetation conditions showed that the vegetation in the WRB began to recover in the 2000s due to the Grain for Green Program but had not reached the same level of vegetation cover as regions in natural eco-hydrological equilibrium. Compared with a simulation using remotely sensed vegetation cover, the simulation with a dynamic vegetation model that considers only climate-induced change showed a 10.3% increase in evapotranspiration, a 47.8% decrease in runoff, and a 62.7% and 71.3% deceleration in changing trend of the outlet river discharge before and after the year 2000, respectively. This result suggests that both natural and anthropogenic factors should be incorporated in dynamic vegetation models to better simulate the eco-hydrological cycle.

  13. Water cycle meets media cycle: Hydrology engagement and social media in New Zealand

    Science.gov (United States)

    Collins, D. B.; Woods, R. A.

    2012-12-01

    The dispersal of scientific knowledge is an on-going challenge for the research community, particularly for the more applied disciplines such as hydrology. To a large degree this arises because key stakeholders do not readily follow the peer-reviewed scientific literature. Even publicly accessible technical reports may be out of sight from many in both the research and stakeholder communities. The challenge to science communication is further compounded by an increasing pressure to raise the hydrological literacy of the public, as water resource management decisions become increasingly collaborative. In these situations, the diversification of communication channels and more rapid interactions between stakeholders and scientists can be of great value. The use of social media in the communication and advancement of hydrological science in New Zealand is a case in point. Two such initiatives are described here: a hydrology blog and a crowd-sourcing data collection campaign using Facebook. The hydrology blog, Waiology (a variant of "hydrology" with the Greek prefix for water replaced by its Maori equivalent), was set up with two main goals in mind: to foster greater understanding and appreciation of hydrology among the New Zealand public, and to more rapidly share new hydrological knowledge within the New Zealand hydrological community. In part, it has also been an experiment to test whether this mode of engagement is worthwhile. Measuring the success of the initiative has proven difficult, but has led to a suite of metrics that collectively gauge popular and professional interest and use of the material. To name a few, this includes visit statistics (taking note of the institution of the visitor), subscriptions, and non-internet citations. Results indicate that, since the blog's inception in mid-2011, it has become a valued resource for the NZ hydrological community and an interesting website for the general public. The second example centered on the use of Facebook

  14. Inter-comparison of energy balance and hydrological models for land surface energy flux estimation over a whole river catchment

    DEFF Research Database (Denmark)

    Guzinski, R.; Nieto, H.; Stisen, S.

    2015-01-01

    Evapotranspiration (ET) is the main link between the natural water cycle and the land surface energy budget. Therefore water-balance and energy-balance approaches are two of the main methodologies for modelling this process. The water-balance approach is usually implemented as a complex....... The temporal patterns produced by the remote sensing and hydrological models are quite highly correlated (r ≈ 0.8). This indicates potential benefits to the hydrological modelling community of integrating spatial information derived through remote sensing methodology (contained in the ET maps...

  15. Hydrology

    Science.gov (United States)

    Sharp, John M.

    1977-01-01

    Lists many recent research projects in hydrology, including flow in fractured media, improvements in remote-sensing techniques, effects of urbanization on water resources, and developments in drainage basins. (MLH)

  16. Hydrology

    International Nuclear Information System (INIS)

    Obando G, E.

    1989-01-01

    Isotopical techniques are used in hydrology area for exploration, evaluation and exploration of water investigation. These techniques have been used successfully and are often the best or only means for providing certain hydrogeological parameters

  17. A critical assessment of the JULES land surface model hydrology for humid tropical environments

    Science.gov (United States)

    Zulkafli, Z.; Buytaert, W.; Onof, C.; Lavado, W.; Guyot, J. L.

    2013-03-01

    Global land surface models (LSMs) such as the Joint UK Land Environment Simulator (JULES) are originally developed to provide surface boundary conditions for climate models. They are increasingly used for hydrological simulation, for instance to simulate the impacts of land use changes and other perturbations on the water cycle. This study investigates how well such models represent the major hydrological fluxes at the relevant spatial and temporal scales - an important question for reliable model applications in poorly understood, data-scarce environments. The JULES-LSM is implemented in a 360 000 km2 humid tropical mountain basin of the Peruvian Andes-Amazon at 12-km grid resolution, forced with daily satellite and climate reanalysis data. The simulations are evaluated using conventional discharge-based evaluation methods, and by further comparing the magnitude and internal variability of the basin surface fluxes such as evapotranspiration, throughfall, and surface and subsurface runoff of the model with those observed in similar environments elsewhere. We find reasonably positive model efficiencies and high correlations between the simulated and observed streamflows, but high root-mean-square errors affecting the performance in smaller, upper sub-basins. We attribute this to errors in the water balance and JULES-LSM's inability to model baseflow. We also found a tendency to under-represent the high evapotranspiration rates of the region. We conclude that strategies to improve the representation of tropical systems to be (1) addressing errors in the forcing and (2) incorporating local wetland and regional floodplain in the subsurface representation.

  18. Influence of cloud radiative effects on tropical circulation and hydrological cycle in the Mid-Holocene

    Science.gov (United States)

    Izumi, Kenji; Kageyama, Masa; Bony, Sandrine; Braconnot, Pascale

    2016-04-01

    Paleoenvironmental data in particular, vegetation and lake-status at mid-Holocene (6,000 years ago) in Sahara shows that African monsoon extended much further north than today. Much of this change results from the changes in insolation driven by precession of the Earth's orbit, but in the state-of-the-art climate models, this factor alone is insufficient to explain the magnitude of the change. Previous studies showed that ocean and vegetation feedbacks affect the mid-Holocene monsoon and that the incorporation of these feedbacks in models improves the simulation of the hydrological cycle. However, it is not sufficient to reduce the discrepancies between simulated and reconstructed surface climates. In this study, we investigate the extent to which the simulation of cloud-radiative effects matters for the simulation of paleo-climatic changes, and past changes in the position and strength of the tropical rain belts in particular. This is done by running a general circulation model with and without clouds-radiation interactions using the IPSL model. The impact of cloud -radiative effects, which prevents the precipitation band to move north, on the tropical circulation and precipitation changes in mid-Holocene experiments will be discussed. Additionally, we will show the simulated effects of land cover change over Sahara.

  19. Regional Hydrological Cycle over the Red Sea in ERA-Interim

    KAUST Repository

    Zolina, Olga

    2016-09-30

    The major sources of atmospheric moisture over the Red Sea are analyzed using ERA-Interim for the 1979-2013 period. The vertical structure of moisture transports across the coastlines has been computed separately for the western and eastern coasts of the Red Sea. The vertical structure of the moisture transport from the Red Sea to the continents is dominated by a breeze-like circulation in the near-surface layer and the Arabian high above 850 hPa. The lower-layer, breeze-like circulation is acting to export the moisture to the northwest of Africa and to the Arabian Peninsula and contributes about 80% of the moisture exports from the Red Sea, dominating over the transport in the upper layer, where the moisture is advected to the Arabian Peninsula in the northern part of the sea and to the African continent in the southern part. Integrated moisture divergence over the Red Sea decreased from the early 1980s to 1997 and then increased until the 2010s. Associated changes in the moisture export were provided primarily by the increasing intensity of the breeze-associated transports. The transports above the boundary layer, while being strong across the western and the eastern coasts, have a smaller effect on the net moisture export. The interannual variability of the moisture export in the near-surface layer was found to be closely correlated with the variability in sea surface temperature, especially in summer. Implications of the observed changes in the moisture advection for the hydrological cycle of the Middle East are discussed.

  20. Regional Hydrological Cycle over the Red Sea in ERA-Interim

    KAUST Repository

    Zolina, Olga; Dufour, Ambroise; Gulev, Sergey K.; Stenchikov, Georgiy L.

    2016-01-01

    The major sources of atmospheric moisture over the Red Sea are analyzed using ERA-Interim for the 1979-2013 period. The vertical structure of moisture transports across the coastlines has been computed separately for the western and eastern coasts of the Red Sea. The vertical structure of the moisture transport from the Red Sea to the continents is dominated by a breeze-like circulation in the near-surface layer and the Arabian high above 850 hPa. The lower-layer, breeze-like circulation is acting to export the moisture to the northwest of Africa and to the Arabian Peninsula and contributes about 80% of the moisture exports from the Red Sea, dominating over the transport in the upper layer, where the moisture is advected to the Arabian Peninsula in the northern part of the sea and to the African continent in the southern part. Integrated moisture divergence over the Red Sea decreased from the early 1980s to 1997 and then increased until the 2010s. Associated changes in the moisture export were provided primarily by the increasing intensity of the breeze-associated transports. The transports above the boundary layer, while being strong across the western and the eastern coasts, have a smaller effect on the net moisture export. The interannual variability of the moisture export in the near-surface layer was found to be closely correlated with the variability in sea surface temperature, especially in summer. Implications of the observed changes in the moisture advection for the hydrological cycle of the Middle East are discussed.

  1. Integrating remotely sensed surface water extent into continental scale hydrology.

    Science.gov (United States)

    Revilla-Romero, Beatriz; Wanders, Niko; Burek, Peter; Salamon, Peter; de Roo, Ad

    2016-12-01

    In hydrological forecasting, data assimilation techniques are employed to improve estimates of initial conditions to update incorrect model states with observational data. However, the limited availability of continuous and up-to-date ground streamflow data is one of the main constraints for large-scale flood forecasting models. This is the first study that assess the impact of assimilating daily remotely sensed surface water extent at a 0.1° × 0.1° spatial resolution derived from the Global Flood Detection System (GFDS) into a global rainfall-runoff including large ungauged areas at the continental spatial scale in Africa and South America. Surface water extent is observed using a range of passive microwave remote sensors. The methodology uses the brightness temperature as water bodies have a lower emissivity. In a time series, the satellite signal is expected to vary with changes in water surface, and anomalies can be correlated with flood events. The Ensemble Kalman Filter (EnKF) is a Monte-Carlo implementation of data assimilation and used here by applying random sampling perturbations to the precipitation inputs to account for uncertainty obtaining ensemble streamflow simulations from the LISFLOOD model. Results of the updated streamflow simulation are compared to baseline simulations, without assimilation of the satellite-derived surface water extent. Validation is done in over 100 in situ river gauges using daily streamflow observations in the African and South American continent over a one year period. Some of the more commonly used metrics in hydrology were calculated: KGE', NSE, PBIAS%, R 2 , RMSE, and VE. Results show that, for example, NSE score improved on 61 out of 101 stations obtaining significant improvements in both the timing and volume of the flow peaks. Whereas the validation at gauges located in lowland jungle obtained poorest performance mainly due to the closed forest influence on the satellite signal retrieval. The conclusion is that

  2. Impact of the assimilation of satellite soil moisture and LST on the hydrological cycle

    Science.gov (United States)

    Laiolo, Paola; Gabellani, Simone; Delogu, Fabio; Silvestro, Francesco; Rudari, Roberto; Campo, Lorenzo; Boni, Giorgio

    2014-05-01

    The reliable estimation of hydrological variables (e.g. soil moisture, evapotranspiration, surface temperature) in space and time is of fundamental importance in operational hydrology to improve the forecast of the rainfall-runoff response of catchments and, consequently, flood predictions. Nowadays remote sensing can offer a chance to provide good space-time estimates of several hydrological variables and then improve hydrological model performances especially in environments with scarce ground based data. The aim of this work is to investigate the impacts on the performances of a distributed hydrological model (Continuum) of the assimilation of satellite-derived soil moisture products and Land Surface (LST). In this work three different soil moisture (SM) products, derived by ASCAT sensor, are used. These data are provided by the EUMETSAT's H-SAF (Satellite Application Facility on Support to Operational Hydrology and Water Management) program. The considered soil moisture products are: large scale surface soil moisture (SM OBS 1 - H07), small scale surface soil moisture (SM OBS 2 - H08) and profile index in the roots region (SM DAS 2 - H14). These data are compared with soil moisture estimated by Continuum model on the Orba catchment (800 km2), in the northern part of Italy, for the period July 2012-June 2013. Different assimilation experiments have been performed. The first experiment consists in the assimilation of the SM products by using a simple Nudging technique; the second one is the assimilation of only LST data, derived from MSG satellite, and the third is the assimilation of both SM products and LST. The benefits on the model predictions of discharge, LST and soil moisture dynamics were tested.

  3. Hydrology

    Science.gov (United States)

    Brutsaert, Wilfried

    2005-08-01

    Water in its different forms has always been a source of wonder, curiosity and practical concern for humans everywhere. Hydrology - An Introduction presents a coherent introduction to the fundamental principles of hydrology, based on the course that Wilfried Brutsaert has taught at Cornell University for the last thirty years. Hydrologic phenomena are dealt with at spatial and temporal scales at which they occur in nature. The physics and mathematics necessary to describe these phenomena are introduced and developed, and readers will require a working knowledge of calculus and basic fluid mechanics. The book will be invaluable as a textbook for entry-level courses in hydrology directed at advanced seniors and graduate students in physical science and engineering. In addition, the book will be more broadly of interest to professional scientists and engineers in hydrology, environmental science, meteorology, agronomy, geology, climatology, oceanology, glaciology and other earth sciences. Emphasis on fundamentals Clarification of the underlying physical processes Applications of fluid mechanics in the natural environment

  4. Comparison of several hydrological cycle parameters in Croatia for two periods

    International Nuclear Information System (INIS)

    Pandzic, Kreso; Trninic, Dusan

    2004-01-01

    Comparison of several hydrological cycle parameter averages for two periods in Croatia is considered. Parameters are: yearly averages of: 2m air temperature, precipitation amounts, potential and real evapotranspiration amounts. A basic period (1951-1980) and period for comparison (1981-1997) have been chosen. (These periods accepted at The First Sub-Regional Expert Meeting on the 'Assesment of Climate Change Impacts on the Hydrological Cycles in South-Eastern Europe' held in Sofia (Bulgaria) 17-20 February 1999.) Differences between two period averages for 30 weather stations have been calculated. Temperature differences and those for potential evaporation are positive while for precipitation they are mainly negative. Real evaporation differences for two periods are an exception i.e. they are positive in continental but negative in Mediterranean part of Croatia. These results agree with global warming trend. (Author)

  5. Influence of spatial variations of microtopography and infiltration on surface runoff and field scale hydrological connectivity

    NARCIS (Netherlands)

    Appels, W.M.; Bogaart, P.W.; Zee, van der S.E.A.T.M.

    2011-01-01

    Surface runoff on agricultural fields arises when rainfall exceeds infiltration. Excess water ponding in and flowing through local microtopography increases the hydrological connectivity of fields. In turn, an increased level of hydrological connectivity leads to a higher surface runoff flux at the

  6. Dynamic contact angle cycling homogenizes heterogeneous surfaces.

    Science.gov (United States)

    Belibel, R; Barbaud, C; Mora, L

    2016-12-01

    In order to reduce restenosis, the necessity to develop the appropriate coating material of metallic stent is a challenge for biomedicine and scientific research over the past decade. Therefore, biodegradable copolymers of poly((R,S)-3,3 dimethylmalic acid) (PDMMLA) were prepared in order to develop a new coating exhibiting different custom groups in its side chain and being able to carry a drug. This material will be in direct contact with cells and blood. It consists of carboxylic acid and hexylic groups used for hydrophilic and hydrophobic character, respectively. The study of this material wettability and dynamic surface properties is of importance due to the influence of the chemistry and the potential motility of these chemical groups on cell adhesion and polymer kinetic hydrolysis. Cassie theory was used for the theoretical correction of contact angles of these chemical heterogeneous surfaces coatings. Dynamic Surface Analysis was used as practical homogenizer of chemical heterogeneous surfaces by cycling during many cycles in water. In this work, we confirmed that, unlike receding contact angle, advancing contact angle is influenced by the difference of only 10% of acidic groups (%A) in side-chain of polymers. It linearly decreases with increasing acidity percentage. Hysteresis (H) is also a sensitive parameter which is discussed in this paper. Finally, we conclude that cycling provides real information, thus avoiding theoretical Cassie correction. H(10)is the most sensible parameter to %A. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. A surface hydrology model for regional vector borne disease models

    Science.gov (United States)

    Tompkins, Adrian; Asare, Ernest; Bomblies, Arne; Amekudzi, Leonard

    2016-04-01

    Small, sun-lit temporary pools that form during the rainy season are important breeding sites for many key mosquito vectors responsible for the transmission of malaria and other diseases. The representation of this surface hydrology in mathematical disease models is challenging, due to their small-scale, dependence on the terrain and the difficulty of setting soil parameters. Here we introduce a model that represents the temporal evolution of the aggregate statistics of breeding sites in a single pond fractional coverage parameter. The model is based on a simple, geometrical assumption concerning the terrain, and accounts for the processes of surface runoff, pond overflow, infiltration and evaporation. Soil moisture, soil properties and large-scale terrain slope are accounted for using a calibration parameter that sets the equivalent catchment fraction. The model is calibrated and then evaluated using in situ pond measurements in Ghana and ultra-high (10m) resolution explicit simulations for a village in Niger. Despite the model's simplicity, it is shown to reproduce the variability and mean of the pond aggregate water coverage well for both locations and validation techniques. Example malaria simulations for Uganda will be shown using this new scheme with a generic calibration setting, evaluated using district malaria case data. Possible methods for implementing regional calibration will be briefly discussed.

  8. Hydrologic Science and Satellite Measurements of Surface Water (Invited)

    Science.gov (United States)

    Alsdorf, D. E.; Mognard, N. M.; Lettenmaier, D. P.

    2010-12-01

    While significant advances continue to be made for satellite measurements of surface waters, important science and application opportunities remain. Examples include the following: (1) Our current methods of measuring floodwater dynamics are either sparsely distributed or temporally inadequate. As an example, flood depths are measured by using high water marks, which capture only the peak of the flood wave, not its temporal variability. (2) Discharge is well measured at individual points along stream networks using in-situ gauges, but these do not capture within-reach hydraulic variability such as the water surface slope changes on the rising and falling limbs of flood waves. (3) Just a 1.0 mm/day error in ET over the Congo Basin translates to a 35,000 m3/s discharge error. Knowing the discharge of the Congo River and its many tributaries should significantly improve our understanding of the water balance throughout the basin. The Congo is exemplary of many other basins around the globe. (4) Arctic hydrology is punctuated by millions of unmeasured lakes. Globally, there might be as many as 30 million lakes larger than a hectare. Storage changes in these lakes are nearly unknown, but in the Arctic such changes are likely an indication of global warming. (5) Well over 100 rivers cross international boundaries, yet the sharing of water data is poor. Overcoming this helps to better manage the entire river basin while also providing a better assessment of potential water related disasters. The Surface Water and Ocean Topography (SWOT, http://swot.jpl.nasa.gov/) mission is designed to meet these needs by providing global measurements of surface water hydrodynamics. SWOT will allow estimates of discharge in rivers wider than 100m (50m goal) and storage changes in water bodies larger than 250m by 250m (and likely as small as one hectare).

  9. Hydrologic Remote Sensing and Land Surface Data Assimilation

    Directory of Open Access Journals (Sweden)

    Hamid Moradkhani

    2008-05-01

    Full Text Available Accurate, reliable and skillful forecasting of key environmental variables such as soil moisture and snow are of paramount importance due to their strong influence on many water resources applications including flood control, agricultural production and effective water resources management which collectively control the behavior of the climate system. Soil moisture is a key state variable in land surface–atmosphere interactions affecting surface energy fluxes, runoff and the radiation balance. Snow processes also have a large influence on land-atmosphere energy exchanges due to snow high albedo, low thermal conductivity and considerable spatial and temporal variability resulting in the dramatic change on surface and ground temperature. Measurement of these two variables is possible through variety of methods using ground-based and remote sensing procedures. Remote sensing, however, holds great promise for soil moisture and snow measurements which have considerable spatial and temporal variability. Merging these measurements with hydrologic model outputs in a systematic and effective way results in an improvement of land surface model prediction. Data Assimilation provides a mechanism to combine these two sources of estimation. Much success has been attained in recent years in using data from passive microwave sensors and assimilating them into the models. This paper provides an overview of the remote sensing measurement techniques for soil moisture and snow data and describes the advances in data assimilation techniques through the ensemble filtering, mainly Ensemble Kalman filter (EnKF and Particle filter (PF, for improving the model prediction and reducing the uncertainties involved in prediction process. It is believed that PF provides a complete representation of the probability distribution of state variables of interests (according to sequential Bayes law and could be a strong alternative to EnKF which is subject to some

  10. Hydrologic Remote Sensing and Land Surface Data Assimilation.

    Science.gov (United States)

    Moradkhani, Hamid

    2008-05-06

    Accurate, reliable and skillful forecasting of key environmental variables such as soil moisture and snow are of paramount importance due to their strong influence on many water resources applications including flood control, agricultural production and effective water resources management which collectively control the behavior of the climate system. Soil moisture is a key state variable in land surface-atmosphere interactions affecting surface energy fluxes, runoff and the radiation balance. Snow processes also have a large influence on land-atmosphere energy exchanges due to snow high albedo, low thermal conductivity and considerable spatial and temporal variability resulting in the dramatic change on surface and ground temperature. Measurement of these two variables is possible through variety of methods using ground-based and remote sensing procedures. Remote sensing, however, holds great promise for soil moisture and snow measurements which have considerable spatial and temporal variability. Merging these measurements with hydrologic model outputs in a systematic and effective way results in an improvement of land surface model prediction. Data Assimilation provides a mechanism to combine these two sources of estimation. Much success has been attained in recent years in using data from passive microwave sensors and assimilating them into the models. This paper provides an overview of the remote sensing measurement techniques for soil moisture and snow data and describes the advances in data assimilation techniques through the ensemble filtering, mainly Ensemble Kalman filter (EnKF) and Particle filter (PF), for improving the model prediction and reducing the uncertainties involved in prediction process. It is believed that PF provides a complete representation of the probability distribution of state variables of interests (according to sequential Bayes law) and could be a strong alternative to EnKF which is subject to some limitations including the linear

  11. Hydrologi

    DEFF Research Database (Denmark)

    Burcharth, Hans F.

    Hydro1ogi er den videnskab, der omhand1er jordens vand, dets forekomst, cirku1ation og forde1ing, dets kemiske og fysiske egenskaber samt indvirkning på omgivelserne, herunder dets relation ti1 alt liv på jorden. Således lyder en b1andt mange definitioner på begrebet hydrologi, og som man kan se...

  12. Modeling SST gradient changes, the hydrological cycle response, and deep water formation in the North Pacific

    Science.gov (United States)

    Burls, N.; Ford, H. L.; Fedorov, A. V.; Jahn, A.; Jacobs, P.

    2017-12-01

    The absence of deep-water formation and a deep meridional overturning cell in the modern North Pacific has been attributed to the relatively fresh surface conditions in the subarctic. These conditions are, in turn, best explained by the local excess of precipitation over evaporation in the northern Pacific due to net moisture transport from the Atlantic to the Pacific and/or moisture transport associated with the Asian monsoon. Some studies link the lack of deep-water formation in the Pacific directly to its occurrence in the Atlantic via the Atlantic-Pacific seesaw effect and idealized experiments indicate that the smaller width of the Atlantic predisposes it to higher salinity and deep-water formation. We have conducted a series of coupled model experiments across which global mean temperatures and large-scale meridional SST gradients are varied. We perturb either atmospheric CO2 concentrations or the meridional gradient in cloud radiative forcing and run each experiment out to 3000 years so that the deep ocean has equilibrated. As the strength of the meridional temperature gradient decreases across our experiments, a Pacific Meridional Overturning Circulation develops. The strength of this Pacific Meridional Overturning Circulation generally increases as the gradient weakens. In one of these experiments where the meridional SST gradient most closely resembles Pliocene reconstructions, a PMOC exists of comparable in strength to the modern AMOC. We will describe how the hydrological cycle response to reduced meridional SST gradients acts to increase the strength of the PMOC across our sensitivity experiments. Additionally, we will discuss our effort to include carbon isotopes in our Pliocene-like simulation for data-model comparisons. Calcium carbonate accumulation data from Subarctic North Pacific Site 882 and new and previously published carbon isotope records from the Pacific appear to support our modelling results suggesting that weaker meridonal SST gradients

  13. Gridded Surface Subsurface Hydrologic Analysis (GSSHA) User's Manual; Version 1.43 for Watershed Modeling System 6.1

    National Research Council Canada - National Science Library

    Downer, Charles W; Ogden, Fred L

    2006-01-01

    The need to simulate surface water flows in watersheds with diverse runoff production mechanisms has led to the development of the physically-based hydrologic model Gridded Surface Subsurface Hydrologic Analysis (GSSHA...

  14. Impacts of climate change on the hydrological cycle over France and associated uncertainties

    Science.gov (United States)

    Dayon, Gildas; Boé, Julien; Martin, Éric; Gailhard, Joël

    2018-05-01

    This study deals with the evolution of the hydrological cycle over France during the 21st century. A large multi-member, multi-scenario, and multi-model ensemble of climate projections is downscaled with a new statistical method to drive a physically-based hydrological model with recent improvements. For a business-as-usual scenario, annual precipitation changes generally remain small, except over southern France, where decreases close to 20% are projected. Annual streamflows roughly decrease by 10% (±20%) on the Seine, by 20% (±20%) on the Loire, by 20% (±15%) on the Rhone and by 40% (±15%) on the Garonne. Attenuation measures, as implied by the other scenarios analyzed, lead to less severe changes. However, even with a scenario generally compatible with a limitation of global warming to two degrees, some notable impacts may still occur, with for example a decrease in summer river flows close to 25% for the Garonne.

  15. Iron cycling at corroding carbon steel surfaces

    Science.gov (United States)

    Lee, Jason S.; McBeth, Joyce M.; Ray, Richard I.; Little, Brenda J.; Emerson, David

    2013-01-01

    Surfaces of carbon steel (CS) exposed to mixed cultures of iron-oxidizing bacteria (FeOB) and dissimilatory iron-reducing bacteria (FeRB) in seawater media under aerobic conditions were rougher than surfaces of CS exposed to pure cultures of either type of microorganism. The roughened surface, demonstrated by profilometry, is an indication of loss of metal from the surface. In the presence of CS, aerobically grown FeOB produced tight, twisted helical stalks encrusted with iron oxides. When CS was exposed anaerobically in the presence of FeRB, some surface oxides were removed. However, when the same FeOB and FeRB were grown together in an aerobic medium, FeOB stalks were less encrusted with iron oxides and appeared less tightly coiled. These observations suggest that iron oxides on the stalks were reduced and solubilized by the FeRB. Roughened surfaces of CS and denuded stalks were replicated with three culture combinations of different species of FeOB and FeRB under three experimental conditions. Measurements of electrochemical polarization resistance established different rates of corrosion of CS in aerobic and anaerobic media, but could not differentiate rate differences between sterile controls and inoculated exposures for a given bulk concentration of dissolved oxygen. Similarly, total iron in the electrolyte could not be used to differentiate treatments. The experiments demonstrate the potential for iron cycling (oxidation and reduction) on corroding CS in aerobic seawater media. PMID:24093730

  16. Water Cycle Dynamics in a Changing Environment: Advancing Hydrologic Science through Synthesis

    Science.gov (United States)

    Sivapalan, M.; Kumar, P.; Rhoads, B. L.; Wuebbles, D.

    2007-12-01

    As one ponders a changing environment -- climate, hydrology, land use, biogeochemical cycles, human dynamics -- there is an increasing need to understand the long term evolution of the linked component systems (e.g., climatic, hydrologic and ecological) through conceptual and quantitative models. The most challenging problem toward this goal is to understand and incorporate the rich dynamics of multiple linked systems with weak and strong coupling, and with many internal variables that exhibit multi-scale interactions. The richness of these interactions leads to fluctuations in one variable that in turn drive the dynamics of other related variables. The key question then becomes: Do these complexities lend an inherently stochastic character to the system, rendering deterministic prediction and modeling of limited value, or do they translate into constrained self- organization through which emerges order, and a limited group of "active" processes (that may change from time to time) that determine the general evolution of the system through a series of structured states with a distinct signature? This is a grand challenge for predictability and therefore requires community effort. The interconnectivity and hence synthesis of knowledge across the fields should be natural for hydrologists since the global water cycle and its regional manifestations directly correspond to the information flows for mass and energy transformations across the media, and across the disciplines. Further, the rich history of numerical, conceptual and stochastic modeling in hydrology provides the training and breadth for addressing the multi- scale, complex system dynamics challenges posed by the evolution question. Theory and observational analyses that necessitate stepping back from the existing knowledge paradigms and looking at the integrated system are needed. In this talk we will present the outlines of a new NSF-funded community effort that attempts to forge inter- disciplinary

  17. Changes in northeast African hydrology and vegetation associated with Pliocene–Pleistocene sapropel cycles

    Science.gov (United States)

    Rose, Cassaundra; Polissar, Pratigya J.; Tierney, Jessica E.; Filley, Timothy

    2016-01-01

    East African climate change since the Late Miocene consisted of persistent shorter-term, orbital-scale wet–dry cycles superimposed upon a long-term trend towards more open, grassy landscapes. Either or both of these modes of palaeoclimate variability may have influenced East African mammalian evolution, yet the interrelationship between these secular and orbital palaeoclimate signals remains poorly understood. Here, we explore whether the long-term secular climate change was also accompanied by significant changes at the orbital-scale. We develop northeast African hydroclimate and vegetation proxy data for two 100 kyr-duration windows near 3.05 and 1.75 Ma at ODP Site 967 in the eastern Mediterranean basin, where sedimentation is dominated by eastern Sahara dust input and Nile River run-off. These two windows were selected because they have comparable orbital configurations and bracket an important increase in East African C4 grasslands. We conducted high-resolution (2.5 kyr sampling) multiproxy biomarker, H- and C-isotopic analyses of plant waxes and lignin phenols to document orbital-scale changes in hydrology, vegetation and woody cover for these two intervals. Both intervals are dominated by large-amplitude, precession-scale (approx. 20 kyr) changes in northeast African vegetation and rainfall/run-off. The δ13Cwax values and lignin phenol composition record a variable but consistently C4 grass-dominated ecosystem for both intervals (50–80% C4). Precessional δDwax cycles were approximately 20–30‰ in peak-to-peak amplitude, comparable with other δDwax records of the Early Holocene African Humid Period. There were no significant differences in the means or variances of the δDwax or δ13Cwax data for the 3.05 and 1.75 Ma intervals studied, suggesting that the palaeohydrology and palaeovegetation responses to precessional forcing were similar for these two periods. Data for these two windows suggest that the eastern Sahara did not experience the

  18. Emerging Technologies for Integrating Multi-Scale Observations of the Hydrologic Cycle

    Science.gov (United States)

    Logan, W. S.; Potter, K. W.; Wood, E. F.

    2007-12-01

    The results are presented of a recent National Research Council study on examining the potential for integrating spaceborne observations with complementary airborne and ground-based observations to gain holistic understanding of hydrologic and related biogeochemical and ecological processes and to help support water and related land-resource management. The study was motivated by the interrelated challenges of population growth, global climate change, and regional changes in land use and land management that will increasingly stress water resources around the world. Meeting these challenges will require significant improvement in our management of water resources, which in turn will require improvements in our capacity to understand and quantify the hydrologic cycle and its interactions with the natural and built environment. Recent and potential future technological innovations in sensors (in-situ, airborne, and space-borne) and sensor networks, cyber-infrastructure, data assimilation, modeling, and decision-support tools offer unprecedented opportunities to improve our capacity to observe, understand, and manage hydrologic systems. The committee investigated a number of aspects to turning this potential into a reality. These included development and field deployment of land-based chemical and biological sensors; the role of airborne remote sensing; interagency gaps between the steps of sensor development, demonstration, and operational deployment; the coordination of federal responsibilities for measurement, monitoring and modeling; and getting the new information to those who can use it. A variety of case studies were used to illustrate the needs and opportunities for new measurement capacity, including hydrologic monitoring in the Everglades, water quantity and quality in the Southern High Plains, malaria in Sub-Saharan Africa, hydroclimatic research in the Arctic, hydrologic extremes and water quality in the Neuse River watershed, and mountain hydrology in the

  19. Characterizing the Surface Connectivity of Depressional Wetlands: Linking Remote Sensing and Hydrologic Modeling Approaches

    Science.gov (United States)

    Christensen, J.; Evenson, G. R.; Vanderhoof, M.; Wu, Q.; Golden, H. E.; Lane, C.

    2017-12-01

    Surface connectivity of wetlands in the 700,000 km2 Prairie Pothole Region of North America (PPR) can occur through fill-spill and fill-merge mechanisms, with some wetlands eventually spilling into stream/river systems. These wetland-to-wetland and wetland-to-stream connections vary both spatially and temporally in PPR watersheds and are important to understanding hydrologic and biogeochemical processes in the landscape. To explore how to best characterize spatial and temporal variability in aquatic connectivity, we compared three approaches, 1) hydrological modeling alone, 2) remotely-sensed data alone, and 3) integrating remotely-sensed data into a hydrological model. These approaches were tested in the Pipestem Creek Watershed, North Dakota across a drought to deluge cycle (1990-2011). A Soil and Water Assessment Tool (SWAT) model was modified to include the water storage capacity of individual non-floodplain wetlands identified in the National Wetland Inventory (NWI) dataset. The SWAT-NWI model simulated the water balance and storage of each wetland and the temporal variability of their hydrologic connections between wetlands during the 21-year study period. However, SWAT-NWI only accounted for fill-spill, and did not allow for the expansion and merging of wetlands situated within larger depressions. Alternatively, we assessed the occurrence of fill-merge mechanisms using inundation maps derived from Landsat images on 19 cloud-free days during the 21 years. We found fill-merge mechanisms to be prevalent across the Pipestem watershed during times of deluge. The SWAT-NWI model was then modified to use LiDAR-derived depressions that account for the potential maximum depression extent, including the merging of smaller wetlands. The inundation maps were used to evaluate the ability of the SWAT-depression model to simulate fill-merge dynamics in addition to fill-spill dynamics throughout the study watershed. Ultimately, using remote sensing to inform and validate

  20. Surface hydrology of drainage basins disturbed by surface mining and reclamation, central Pennsylvania

    International Nuclear Information System (INIS)

    Ritter, J.B.

    1990-01-01

    Infilration capacity of newly reclaimed minesoils is uniformly low (< 1 cm/hr) and generally increases (up to 6 cm/hr) with age, the magnitude of increase being dependent on soil characteristics and vegetation. In drainage basins with lower rates of infiltration recovery (< 2 cm/hr), infiltration-excess overland flow is the dominant runoff process. Increased peek runoff rate and stream power in the basins are sufficient to initiate drainage network evolution, with phases of network expansion and abstraction. In contrast, in basins where infiltration recovery is greater than 2 cm/hr, the hydrologic system is initially dominated by infiltration-excess overland flow but evolves toward a system dominated by saturation overland flow. Drainage development is limited to skeletal network initiation and elongation and occurs during the early period of infiltration-excess dominated flow conditions. Total runoff remains essentially constant due to increased proportions of return flow, reflected in the extended and less steep recession limb of saturation-dominated storm hydrographs. The results of this study are applicable to hydrologic prediction for purposes of surface mine permitting and reclamation design. Previously limited availability of rainfall-runoff data from watersheds disturbed by surface mining preclude adequate calibration of empirical methods, such as the runoff curve number method, or evaluation of a more sophisticated approach, such as the use of distributed hydrologic models, for hydrologic prediction. Runoff curve numbers calibrated by means of rainfall-runoff data from the study drainage basins indicate that presently accepted methods of determining curve numbers, using pre-mine soil classification, underestimate total runoff by as much as 50%

  1. Field Investigation and Modeling Development for Hydrological and Carbon Cycles in Southwest Karst Region of China

    Science.gov (United States)

    Hu, X. B.

    2017-12-01

    It is required to understanding water cycle and carbon cycle processes for water resource management and pollution prevention and global warming influence in southwest karst region of China. Lijiang river basin is selected as our study region. Interdisciplinary field and laboratory experiments with various technologies are conducted to characterize the karst aquifers in detail. Key processes in the karst water cycle and carbon cycle are determined. Based on the MODFLOW-CFP model, new watershed flow and carbon cycle models are developed coupled subsurface and surface water flow models. Our study focus on the karst springshed in Mao village, the mechanisms coupling carbon cycle and water cycle are explored. This study provides basic theory and simulation method for water resource management and groundwater pollution prevention in China karst region.

  2. Evaluation of Airborne Lidar Elevation Surfaces for Propagation of Coastal Inundation: The Importance of Hydrologic Connectivity

    Directory of Open Access Journals (Sweden)

    Sandra Poppenga

    2015-09-01

    Full Text Available Detailed information about coastal inundation is vital to understanding dynamic and populated areas that are impacted by storm surge and flooding. To understand these natural hazard risks, lidar elevation surfaces are frequently used to model inundation in coastal areas. A single-value surface method is sometimes used to inundate areas in lidar elevation surfaces that are below a specified elevation value. However, such an approach does not take into consideration hydrologic connectivity between elevation grids cells resulting in inland areas that should be hydrologically connected to the ocean, but are not. Because inland areas that should drain to the ocean are hydrologically disconnected by raised features in a lidar elevation surface, simply raising the water level to propagate coastal inundation will lead to inundation uncertainties. We took advantage of this problem to identify hydrologically disconnected inland areas to point out that they should be considered for coastal inundation, and that a lidar-based hydrologic surface should be developed with hydrologic connectivity prior to inundation analysis. The process of achieving hydrologic connectivity with hydrologic-enforcement is not new, however, the application of hydrologically-enforced lidar elevation surfaces for improved coastal inundation mapping as approached in this research is innovative. In this article, we propagated a high-resolution lidar elevation surface in coastal Staten Island, New York to demonstrate that inland areas lacking hydrologic connectivity to the ocean could potentially be included in inundation delineations. For inland areas that were hydrologically disconnected, we evaluated if drainage to the ocean was evident, and calculated an area exceeding 11 ha (~0.11 km2 that could be considered in inundation delineations. We also assessed land cover for each inland area to determine the type of physical surfaces that would be potentially impacted if the inland areas

  3. Evaluation of airborne lidar elevation surfaces for propagation of coastal inundation: the importance of hydrologic connectivity

    Science.gov (United States)

    Poppenga, Sandra K.; Worstell, Bruce B.

    2015-01-01

    Detailed information about coastal inundation is vital to understanding dynamic and populated areas that are impacted by storm surge and flooding. To understand these natural hazard risks, lidar elevation surfaces are frequently used to model inundation in coastal areas. A single-value surface method is sometimes used to inundate areas in lidar elevation surfaces that are below a specified elevation value. However, such an approach does not take into consideration hydrologic connectivity between elevation grids cells resulting in inland areas that should be hydrologically connected to the ocean, but are not. Because inland areas that should drain to the ocean are hydrologically disconnected by raised features in a lidar elevation surface, simply raising the water level to propagate coastal inundation will lead to inundation uncertainties. We took advantage of this problem to identify hydrologically disconnected inland areas to point out that they should be considered for coastal inundation, and that a lidar-based hydrologic surface should be developed with hydrologic connectivity prior to inundation analysis. The process of achieving hydrologic connectivity with hydrologic-enforcement is not new, however, the application of hydrologically-enforced lidar elevation surfaces for improved coastal inundation mapping as approached in this research is innovative. In this article, we propagated a high-resolution lidar elevation surface in coastal Staten Island, New York to demonstrate that inland areas lacking hydrologic connectivity to the ocean could potentially be included in inundation delineations. For inland areas that were hydrologically disconnected, we evaluated if drainage to the ocean was evident, and calculated an area exceeding 11 ha (~0.11 km2) that could be considered in inundation delineations. We also assessed land cover for each inland area to determine the type of physical surfaces that would be potentially impacted if the inland areas were considered as

  4. Historical upscaling of the socio-hydrological cycle: Three cases from the Mediterranean Spain

    Science.gov (United States)

    Macian-Sorribes, Hector; Pulido-Velazquez, Manuel; Sanchis-Ibor, Carles

    2015-04-01

    local level to the basin level, based on collaborative actions through multistakeholder partnerships and agreements. Irrigation development has played a major role in the evolutionary trend of the hydro-social cycle in the three basins, determining water demands and uses, and boosting institutional building. Following the main historical institutional milestones and examining the historical changes in water uses, remarkable differences can be found among the three cases, enhancing the high sensitivity of the hydrological processes with respect to socio-economic factors. Therefore, comparing them is adequate to find out those high-sensitive factors and the way they provoke the differences between the basins. The casual loop created a basin closure - basin reopening cycle. Basin closures were associated to increasing demands by population growth, irrigation and immigration, causing drought vulnerability. Basin reopenings corresponded to the building of regulation facilities (reservoirs, canals), the availability of new water sources (groundwater, regenerated water), or a change in the management strategies (conjunctive use). During basin closure, users fought during droughts but united to prevent new users' access to water. During reopenings, water use quickly increased, leading to basin closures. User conflicts were solved by user agreement in water sharing or by law requirement, establishing a new management policy. New-user conflicts were solved when the basin reopened again and those potential users gained access to water.

  5. A new perspective on the regional hydrologic cycle over North and South America

    Science.gov (United States)

    Weng, Shu-Ping

    The GEOS-1 vertically-integrated 3-hr moisture flux reanalyses and hourly-gridded United States station precipitation plus a satellite-based, 6-hr global precipitation estimate were employed to investigate the impacts of nocturnal low-level jets (LLJs) on the regional hydrological cycle over the central United States (Part I) and the subtropical plains of South America (Part II). Research stressed the influences of upper-level synoptic-scale waves (i.e., synoptic-scale forcings) upon the regional hydrologic processes, which were explored by the impacts associated with the occurrence of LLJ. Besides the conventional budget analysis, the adopted `synoptic-forcing approach' was proven illustrative in describing these impacts through the down-scaling process of LLJs. In Part 1, the major findings include: (1)the seasonal-averaged hydrological cycle over the Great Plains is strongly affected by the occurrence of GPLLJ, (2)the synoptic-scale forcing provided by the upper-level propagating jet (ULJ) streams is essential in generating the large-scale precipitation after the GPLLJ forms from the diurnal boundary layer process, (3)without the dynamic coupling between the ULJ and LLJ, the impact of LLJ on the hydrological cycle is demonstrated to be less important, and (4)the importance of synoptic-scale forcings in preconditioning the setting of wet/dry seasons in the interannual variability of rainfall anomaly is further illustrated by examining the changes of intensity as well as the occurrence frequency between the different types of LLJ. In Part II of this study, it was found that the occurrence of Andean LLJ represents a transient episode that detours the climatic rainfall activity along the South Atlantic Convergent Zone (SACZ) to the subtropical plains (Brazilian Nordeste) in its southwestern (northeastern) flank. The appearance of a seesaw pattern in the rainfall and flux convergence anomalies along the southeastern portion of South America, which is spatially in

  6. From drought to flooding: understanding the abrupt 2010-11 hydrological annual cycle in the Amazonas River and tributaries

    Science.gov (United States)

    Carlo Espinoza, Jhan; Ronchail, Josyane; Loup Guyot, Jean; Junquas, Clementine; Drapeau, Guillaume; Martinez, Jean Michel; Santini, William; Vauchel, Philippe; Lavado, Waldo; Ordoñez, Julio; Espinoza, Raúl

    2012-06-01

    In this work we document and analyze the hydrological annual cycles characterized by a rapid transition between low and high flows in the Amazonas River (Peruvian Amazon) and we show how these events, which may impact vulnerable riverside residents, are related to regional climate variability. Our analysis is based on comprehensive discharge, rainfall and average suspended sediment data sets. Particular attention is paid to the 2010-11 hydrological year, when an unprecedented abrupt transition from the extreme September 2010 drought (8300 m3 s-1) to one of the four highest discharges in April 2011 (49 500 m3 s-1) was recorded at Tamshiyacu (Amazonas River). This unusual transition is also observed in average suspended sediments. Years with a rapid increase in discharge are characterized by negative sea surface temperature anomalies in the central equatorial Pacific during austral summer, corresponding to a La Niña-like mode. It originates a geopotential height wave train over the subtropical South Pacific and southeastern South America, with a negative anomaly along the southern Amazon and the southeastern South Atlantic convergence zone region. As a consequence, the monsoon flux is retained over the Amazon and a strong convergence of humidity occurs in the Peruvian Amazon basin, favoring high rainfall and discharge. These features are also reported during the 2010-11 austral summer, when an intense La Niña event characterized the equatorial Pacific.

  7. From drought to flooding: understanding the abrupt 2010–11 hydrological annual cycle in the Amazonas River and tributaries

    International Nuclear Information System (INIS)

    Espinoza, Jhan Carlo; Ronchail, Josyane; Drapeau, Guillaume; Guyot, Jean Loup; Martinez, Jean Michel; Santini, William; Vauchel, Philippe; Espinoza, Raúl; Junquas, Clementine; Lavado, Waldo; Ordoñez, Julio

    2012-01-01

    In this work we document and analyze the hydrological annual cycles characterized by a rapid transition between low and high flows in the Amazonas River (Peruvian Amazon) and we show how these events, which may impact vulnerable riverside residents, are related to regional climate variability. Our analysis is based on comprehensive discharge, rainfall and average suspended sediment data sets. Particular attention is paid to the 2010–11 hydrological year, when an unprecedented abrupt transition from the extreme September 2010 drought (8300 m 3 s −1 ) to one of the four highest discharges in April 2011 (49 500 m 3 s −1 ) was recorded at Tamshiyacu (Amazonas River). This unusual transition is also observed in average suspended sediments. Years with a rapid increase in discharge are characterized by negative sea surface temperature anomalies in the central equatorial Pacific during austral summer, corresponding to a La Niña-like mode. It originates a geopotential height wave train over the subtropical South Pacific and southeastern South America, with a negative anomaly along the southern Amazon and the southeastern South Atlantic convergence zone region. As a consequence, the monsoon flux is retained over the Amazon and a strong convergence of humidity occurs in the Peruvian Amazon basin, favoring high rainfall and discharge. These features are also reported during the 2010–11 austral summer, when an intense La Niña event characterized the equatorial Pacific. (letter)

  8. The Annual Glaciohydrology Cycle in the Ablation Zone of the Greenland Ice Sheet: Part 1. Hydrology Model

    Science.gov (United States)

    Colgan, William; Rajaram, Harihar; Anderson, Robert; Steffen. Konrad; Phillips, Thomas; Zwally, H. Jay; Abdalati, Waleed

    2012-01-01

    We apply a novel one-dimensional glacier hydrology model that calculates hydraulic head to the tidewater-terminating Sermeq Avannarleq flowline of the Greenland ice sheet. Within a plausible parameter space, the model achieves a quasi-steady-state annual cycle in which hydraulic head oscillates close to flotation throughout the ablation zone. Flotation is briefly achieved during the summer melt season along a approx.17 km stretch of the approx.50 km of flowline within the ablation zone. Beneath the majority of the flowline, subglacial conduit storage closes (i.e. obtains minimum radius) during the winter and opens (i.e. obtains maximum radius) during the summer. Along certain stretches of the flowline, the model predicts that subglacial conduit storage remains open throughout the year. A calculated mean glacier water residence time of approx.2.2 years implies that significant amounts of water are stored in the glacier throughout the year. We interpret this residence time as being indicative of the timescale over which the glacier hydrologic system is capable of adjusting to external surface meltwater forcings. Based on in situ ice velocity observations, we suggest that the summer speed-up event generally corresponds to conditions of increasing hydraulic head during inefficient subglacial drainage. Conversely, the slowdown during fall generally corresponds to conditions of decreasing hydraulic head during efficient subglacial drainage.

  9. Integrating remotely sensed surface water extent into continental scale hydrology

    NARCIS (Netherlands)

    Revilla-Romero, Beatriz; Wanders, Niko; Burek, Peter; Salamon, Peter; de Roo, Ad

    2016-01-01

    In hydrological forecasting, data assimilation techniques are employed to improve estimates of initial conditions to update incorrect model states with observational data. However, the limited availability of continuous and up-to-date ground streamflow data is one of the main constraints for

  10. Hydrological processes obtained on the plot scale under four simulated rainfall tests during the cycle of different crop systems

    Directory of Open Access Journals (Sweden)

    Ildegardis Bertol

    2014-04-01

    Full Text Available The cropping system influences the interception of water by plants, water storage in depressions on the soil surface, water infiltration into the soil and runoff. The aim of this study was to quantify some hydrological processes under no tillage cropping systems at the edge of a slope, in 2009 and 2010, in a Humic Dystrudept soil, with the following treatments: corn, soybeans, and common beans alone; and intercropped corn and common bean. Treatments consisted of four simulated rainfall tests at different times, with a planned intensity of 64 mm h-1 and 90 min duration. The first test was applied 18 days after sowing, and the others at 39, 75 and 120 days after the first test. Different times of the simulated rainfall and stages of the crop cycle affected soil water content prior to the rain, and the time runoff began and its peak flow and, thus, the surface hydrological processes. The depth of the runoff and the depth of the water intercepted by the crop + soil infiltration + soil surface storage were affected by the crop systems and the rainfall applied at different times. The corn crop was the most effective treatment for controlling runoff, with a water loss ratio of 0.38, equivalent to 75 % of the water loss ratio exhibited by common bean (0.51, the least effective treatment in relation to the others. Total water loss by runoff decreased linearly with an increase in the time that runoff began, regardless of the treatment; however, soil water content on the gravimetric basis increased linearly from the beginning to the end of the rainfall.

  11. Soil Surface Runoff Scheme for Improving Land-Hydrology and Surface Fluxes in Simple SiB (SSiB)

    Science.gov (United States)

    Sud, Y. C.; Mocko, David M.

    1999-01-01

    Evapotranspiration on land is hard to measure and difficult to simulate. On the scale of a GCM grid, there is large subgrid-scale variability of orography, soil moisture, and vegetation. Our hope is to be able to tune the biophysical constants of vegetation and soil parameters to get the most realistic space-averaged diurnal cycle of evaporation and its climatology. Field experiments such as First ISLSCP Field Experiment (FIFE), Boreal Ecosystem-Atmosphere Study (BOREAS), and LBA help a great deal in improving our evapotranspiration schemes. However, these improvements have to be matched with, and coupled to, consistent improvement in land-hydrology; otherwise, the runoff problems will intrinsically reflect on the soil moisture and evapotranspiration errors. Indeed, a realistic runoff simulation also ensures a reasonable evapotranspiration simulation provided the precipitation forcing is reliable. We have been working on all of the above problems to improve the simulated hydrologic cycle. Through our participation in the evaluation and intercomparison of land-models under the behest of Global Soil Wetness Project (GSWP), we identified a few problems with Simple SiB (SSIB; Xue et al., 1991) hydrology in regions of significant snowmelt. Sud and Mocko (1999) show that inclusion of a separate snowpack model, with its own energy budget and fluxes with the atmosphere aloft and soil beneath, helps to ameliorate some of the deficiencies of delayed snowmelt and excessive spring season runoff. Thus, much more realistic timing of melt water generation was simulated with the new snowpack model in the subsequent GSWP re-evaluations using 2 years of ISLSCP Initiative I forcing data for 1987 and 1988. However, we noted an overcorrection of the low meltwater infiltration of SSiB. While the improvement in snowmelt timing was found everywhere, the snowmelt infiltration has became excessive in some regions, e.g., Lena river basin. This leads to much reduced runoff in many basins as

  12. A flexible hydrological warning system in Denmark for real-time surface water and groundwater simulations

    Science.gov (United States)

    He, Xin; Stisen, Simon; Wiese, Marianne B.; Jørgen Henriksen, Hans

    2015-04-01

    In Denmark, increasing focus on extreme weather events has created considerable demand for short term forecasts and early warnings in relation to groundwater and surface water flooding. The Geological Survey of Denmark and Greenland (GEUS) has setup, calibrated and applied a nationwide water resources model, the DK-Model, primarily for simulating groundwater and surface water flows and groundwater levels during the past 20 years. So far, the DK-model has only been used in offline historical and future scenario simulations. Therefore, challenges arise in operating such a model for online forecasts and early warnings, which requires access to continuously updated observed climate input data and forecast data of precipitation, temperature and global radiation for the next 48 hours or longer. GEUS has a close collaboration with the Danish Meteorological Institute in order to test and enable this data input for the DK model. Due to the comprehensive physical descriptions of the DK-Model, the simulation results can potentially be any component of the hydrological cycle within the models domain. Therefore, it is important to identify which results need to be updated and saved in the real-time mode, since it is not computationally economical to save every result considering the heavy load of data. GEUS have worked closely with the end-users and interest groups such as water planners and emergency managers from the municipalities, water supply and waste water companies, consulting companies and farmer organizations, in order to understand their possible needs for real time simulation and monitoring of the nationwide water cycle. This participatory process has been supported by a web based questionnaire survey, and a workshop that connected the model developers and the users. For qualifying the stakeholder engagement, GEUS has selected a representative catchment area (Skjern River) for testing and demonstrating a prototype of the web based hydrological warning system at the

  13. Increasing the reliability of the Olkiluoto surface and near-surface hydrological model

    International Nuclear Information System (INIS)

    Karvonen, T.

    2009-05-01

    The aim of the study was to improve the reliability of the Olkiluoto surface hydrological model that calculates the overall water balance components of Olkiluoto Island. ONKALO and Korvensuo reservoir were added as explicit structures to the model. The model links the unsaturated and saturated soil water in the overburden and groundwater in bedrock to a continuous pressure system. With the model it is possible to evaluate the influence of water leaking to ONKALO on groundwater level in overburden soils and pressure head in shallow bedrock drillholes. Anisotropy was added to the surface hydrological model and several model runs were carried out using anisotropy factors 1, 5 and 10. Anisotropy factor of 10 is used in the 2008 version of the deep hydrogeological model and the same anisotropy will be used in future calculations of the surface hydrological model to ensure consistency of the parameter values in the two models. The correspondence between measured and computed groundwater levels has been improved due to new soil type delineation and the calibration of the soil water retention curve parameters. Computed groundwater level variation can be characterized by a measure ΔH COMP , which is difference between maximum and minimum value during the calibration period. Average ΔH COMP in groundwater tubes was 1.98 m and the corresponding measured value ΔH MEAS was 2.08 m, i.e. the difference between measured and computed value was around 0.1 m (0.16 m in the 2007 version). Temporal variation (difference between maximum and minimum pressure head) was simulated well also in most of the shallow bedrock drillholes. ONKALO was added to the 2008 version of the Olkiluoto surface hydrological model. Influence of ONKALO is taken into account by giving the total discharge as input data from existing measurements or from calculations of the deep hydrogeological model of the Olkiluoto Island. The computed results show that ONKALO has a temporal effect on groundwater level in

  14. Olkiluoto surface hydrological modelling: Update 2012 including salt transport modelling

    International Nuclear Information System (INIS)

    Karvonen, T.

    2013-11-01

    Posiva Oy is responsible for implementing a final disposal program for spent nuclear fuel of its owners Teollisuuden Voima Oyj and Fortum Power and Heat Oy. The spent nuclear fuel is planned to be disposed at a depth of about 400-450 meters in the crystalline bedrock at the Olkiluoto site. Leakages located at or close to spent fuel repository may give rise to the upconing of deep highly saline groundwater and this is a concern with regard to the performance of the tunnel backfill material after the closure of the tunnels. Therefore a salt transport sub-model was added to the Olkiluoto surface hydrological model (SHYD). The other improvements include update of the particle tracking algorithm and possibility to estimate the influence of open drillholes in a case where overpressure in inflatable packers decreases causing a hydraulic short-circuit between hydrogeological zones HZ19 and HZ20 along the drillhole. Four new hydrogeological zones HZ056, HZ146, BFZ100 and HZ039 were added to the model. In addition, zones HZ20A and HZ20B intersect with each other in the new structure model, which influences salinity upconing caused by leakages in shafts. The aim of the modelling of long-term influence of ONKALO, shafts and repository tunnels provide computational results that can be used to suggest limits for allowed leakages. The model input data included all the existing leakages into ONKALO (35-38 l/min) and shafts in the present day conditions. The influence of shafts was computed using eight different values for total shaft leakage: 5, 11, 20, 30, 40, 50, 60 and 70 l/min. The selection of the leakage criteria for shafts was influenced by the fact that upconing of saline water increases TDS-values close to the repository areas although HZ20B does not intersect any deposition tunnels. The total limit for all leakages was suggested to be 120 l/min. The limit for HZ20 zones was proposed to be 40 l/min: about 5 l/min the present day leakages to access tunnel, 25 l/min from

  15. Olkiluoto surface hydrological modelling: Update 2012 including salt transport modelling

    Energy Technology Data Exchange (ETDEWEB)

    Karvonen, T. [WaterHope, Helsinki (Finland)

    2013-11-15

    Posiva Oy is responsible for implementing a final disposal program for spent nuclear fuel of its owners Teollisuuden Voima Oyj and Fortum Power and Heat Oy. The spent nuclear fuel is planned to be disposed at a depth of about 400-450 meters in the crystalline bedrock at the Olkiluoto site. Leakages located at or close to spent fuel repository may give rise to the upconing of deep highly saline groundwater and this is a concern with regard to the performance of the tunnel backfill material after the closure of the tunnels. Therefore a salt transport sub-model was added to the Olkiluoto surface hydrological model (SHYD). The other improvements include update of the particle tracking algorithm and possibility to estimate the influence of open drillholes in a case where overpressure in inflatable packers decreases causing a hydraulic short-circuit between hydrogeological zones HZ19 and HZ20 along the drillhole. Four new hydrogeological zones HZ056, HZ146, BFZ100 and HZ039 were added to the model. In addition, zones HZ20A and HZ20B intersect with each other in the new structure model, which influences salinity upconing caused by leakages in shafts. The aim of the modelling of long-term influence of ONKALO, shafts and repository tunnels provide computational results that can be used to suggest limits for allowed leakages. The model input data included all the existing leakages into ONKALO (35-38 l/min) and shafts in the present day conditions. The influence of shafts was computed using eight different values for total shaft leakage: 5, 11, 20, 30, 40, 50, 60 and 70 l/min. The selection of the leakage criteria for shafts was influenced by the fact that upconing of saline water increases TDS-values close to the repository areas although HZ20B does not intersect any deposition tunnels. The total limit for all leakages was suggested to be 120 l/min. The limit for HZ20 zones was proposed to be 40 l/min: about 5 l/min the present day leakages to access tunnel, 25 l/min from

  16. The use of remotely sensed soil moisture data in large-scale models of the hydrological cycle

    Science.gov (United States)

    Salomonson, V. V.; Gurney, R. J.; Schmugge, T. J.

    1985-01-01

    Manabe (1982) has reviewed numerical simulations of the atmosphere which provided a framework within which an examination of the dynamics of the hydrological cycle could be conducted. It was found that the climate is sensitive to soil moisture variability in space and time. The challenge arises now to improve the observations of soil moisture so as to provide up-dated boundary condition inputs to large scale models including the hydrological cycle. Attention is given to details regarding the significance of understanding soil moisture variations, soil moisture estimation using remote sensing, and energy and moisture balance modeling.

  17. Plot-scale field experiment of surface hydrologic processes with EOS implications

    Science.gov (United States)

    Laymon, Charles A.; Macari, Emir J.; Costes, Nicholas C.

    1992-01-01

    Plot-scale hydrologic field studies were initiated at NASA Marshall Space Flight Center to a) investigate the spatial and temporal variability of surface and subsurface hydrologic processes, particularly as affected by vegetation, and b) develop experimental techniques and associated instrumentation methodology to study hydrologic processes at increasingly large spatial scales. About 150 instruments, most of which are remotely operated, have been installed at the field site to monitor ground atmospheric conditions, precipitation, interception, soil-water status, and energy flux. This paper describes the nature of the field experiment, instrumentation and sampling rationale, and presents preliminary findings.

  18. The assessment of the influence of different natural conditions on the particular processes of the hydrological cycle within a river basin

    Czech Academy of Sciences Publication Activity Database

    Šípek, Václav; Němečková, Soňa

    2011-01-01

    Roč. 13, - (2011), s. 6904 ISSN 1607-7962. [European Geosciences Union General Assembly 2011. 03.04.2011-08.04.2011, Vienna] R&D Projects: GA AV ČR IAA300600901 Institutional research plan: CEZ:AV0Z20600510 Keywords : hydrological modelling * hydrological cycle * SWIM model Subject RIV: DA - Hydrology ; Limnology

  19. Soil macropores: Control on infiltration, hillslope and surface hydrology on a reclaimed surface-mined watershed

    International Nuclear Information System (INIS)

    Guebert, M.D.; Gardner, T.W.

    1992-01-01

    The hydrologic response of a surface-mined watershed in central Pennsylvania is controlled by rapid macropore flow within the unsaturated man-made topsoil. Newly reclaimed surface-mined watersheds in central Pennsylvania exhibit low steady-state infiltration rates (1--2 cm/hr) and produce runoff dominated by infiltration-excess overland flow. However, within four years after reclamation, infiltration rates on some mine surfaces approach premined rates (8 cm/hr). As infiltration rate increases, the volume of infiltrated water increases, but the total porosity of minesoil matrix remains constant. There is little change in the surface discharge volume, indicating that infiltrated water continues to contribute to the basin surface discharge by the processes of throughflow and return flow. Throughflow in the topsoil horizon occurs in rapid response to rainfall input, producing large volumes of water with throughflow rates closely related to rainfall rates and with throughflow peaks following rainfall peaks by only minutes. Increased return flow alters the shape of the surface runoff hydrograph by slightly lagging behind infiltration excess overland flow. These changes in the shape of the surface runoff hydrograph reduce the potential for severe gully erosion on the reclaimed site. In addition, throughflow water remains predominantly in the topsoil horizon, and therefore has limited contact with potentially acid-producing backfill. Better understanding of macropore flow processes in reclaimed minesoils will help investigators evaluate past strategies and develop new reclamation techniques that will minimize the short-term surface erosional effects of mining and reclamation, while optimizing the long-term effluent and groundwater quality

  20. Sensitivity of the hydrologic cycle in Tana river basin to climate change

    International Nuclear Information System (INIS)

    Mutua, F.M.

    1998-01-01

    The Tana River basin in Kenya has four distinct climates along it's gradient from cool humid in mount Kenya region through arid and semi arid in the lower plains to semi humid coastal climate. From the highlands of mount Kenya to the plateau on the lowlands, the river traverses some sections which have high potential for hydro-electric power generation. The government has constructed water reovirus to collect water for electricity generation. The influence of the reovirus have also caused climate modification. The aim of the study was to investigate the sensitivity of the river flows in the Tana river to climate change. The study indicates that, as long as temperature increment of up to 2 degrees centigrade are accompanied by positive changes (greater than 10%) in rainfall over the basin, then the hydrologic cycle adjust itself accordingly to give a positive response (increased runoff) in terms of the river at the outlet

  1. Development and Validation of Water Vapor Tracers as Diagnostics for the Atmospheric Hydrologic Cycle

    Science.gov (United States)

    Bosilovich, Michael G.; Schubert, Siegfried D.; Einaudi, Franco (Technical Monitor)

    2000-01-01

    Understanding of the local and remote sources of water vapor can be a valuable diagnostic in understanding the regional atmospheric hydrologic cycle. In the present study, we have implemented passive tracers as prognostic variables to follow water vapor evaporated in predetermined regions until the water tracer precipitates. The formulation of the sources and sinks of tracer water is generally proportional to the prognostic water vapor variable. Because all water has been accounted for in tracers, the water vapor variable provides the validation of the tracer water and the formulation of the sources and sinks. The tracers have been implemented in a GEOS General Circulation Model (GCM) simulation consisting of several summer periods to determine the source regions of precipitation for the United States and India. The recycling of water and interannual variability of the sources of water will be examined. Potential uses in GCM sensitivity studies, predictability studies and data assimilation will be discussed.

  2. Biomass Burning, Land-Cover Change, and the Hydrological Cycle in Northern Sub-Saharan Africa

    Science.gov (United States)

    Ichoku, Charles; Ellison, Luke T.; Willmot, K. Elena; Matsui, Toshihisa; Dezfuli, Amin K.; Gatebe, Charles K.; Wang, Jun; Wilcox, Eric M.; Lee, Jejung; Adegoke, Jimmy; hide

    2016-01-01

    The Northern Sub-Saharan African (NSSA) region, which accounts for 20%-25%of the global carbon emissions from biomass burning, also suffers from frequent drought episodes and other disruptions to the hydrological cycle whose adverse societal impacts have been widely reported during the last several decades. This paper presents a conceptual framework of the NSSA regional climate system components that may be linked to biomass burning, as well as detailed analyses of a variety of satellite data for 2001-2014 in conjunction with relevant model-assimilated variables. Satellite fire detections in NSSA show that the vast majority (greater than 75%) occurs in the savanna and woody savanna land-cover types. Starting in the 2006-2007 burning season through the end of the analyzed data in 2014, peak burning activity showed a net decrease of 2-7% /yr in different parts of NSSA, especially in the savanna regions. However, fire distribution shows appreciable coincidence with land-cover change. Although there is variable mutual exchange of different land cover types, during 2003-2013, cropland increased at an estimated rate of 0.28% /yr of the total NSSA land area, with most of it (0.18% /yr) coming from savanna.During the last decade, conversion to croplands increased in some areas classified as forests and wetlands, posing a threat to these vital and vulnerable ecosystems. Seasonal peak burning is anti-correlated with annual water-cycle indicators such as precipitation, soil moisture, vegetation greenness, and evapotranspiration, except in humid West Africa (5 deg-10 deg latitude),where this anti-correlation occurs exclusively in the dry season and burning virtually stops when monthly mean precipitation reaches 4 mm/d. These results provide observational evidence of changes in land-cover and hydrological variables that are consistent with feedbacks from biomass burning in NSSA, and encourage more synergistic modeling and observational studies that can elaborate this feedback

  3. Anomalies of hydrological cycle components during the 2007 heat wave in Bulgaria

    Science.gov (United States)

    Mircheva, Biliana; Tsekov, Milen; Meyer, Ulrich; Guerova, Guergana

    2017-12-01

    Heat waves have large adverse social, economic and environmental effects which include increased mortality, transport restrictions and a decreased agricultural production. The estimated economic losses of the 2007 heat wave in South-east Europe exceed 2 billion EUR with 19 000 hospitalisation in Romania only. Understanding the changes of the hydrological cycle components is essential for early forecasting of heat wave occurrence. Valuable insight of two components of the hydrological cycle, namely Integrated Water Vapour (IWV) and Terrestrial Water Storage Anomaly (TWSA), is now possible using observations from Global Navigation Satellite System (GNSS) and Gravity Recovery And Climate Experiment (GRACE) mission. In this study anomalies of temperature, precipitation, IWV and TWS in 2007 are compared to 2003-2013 period for Sofia, Bulgaria. In 2007, positive temperature anomalies are observed in January, February and July. There are negative IWV and precipitation anomalies in July 2007 that coincides with the heat wave in Bulgaria. TWSA in 2007 are negative in January, May and from July to October being largest in August. Long-term trends of: 1) temperatures have a local maximum in March 2007, 2) TWSA has a local minimum in May 2007, 3) IWV has a local minimum in September 2007, and 4) precipitation has a local maximum in July 2007. The TWSA interannual trends in Bulgaria, Hungary and Poland show similar behaviour as indicated by cross correlation coefficients of 0.9 and 0.7 between Bulgaria and Hungary and Bulgaria and Poland respectively. ALADIN-Climate describes the anomalies of temperature and IWV more successfully than those of precipitation and TWS.

  4. Quantifying watershed surface depression storage: determination and application in a hydrologic model

    Science.gov (United States)

    Joseph K. O. Amoah; Devendra M. Amatya; Soronnadi. Nnaji

    2012-01-01

    Hydrologic models often require correct estimates of surface macro-depressional storage to accurately simulate rainfall–runoff processes. Traditionally, depression storage is determined through model calibration or lumped with soil storage components or on an ad hoc basis. This paper investigates a holistic approach for estimating surface depressional storage capacity...

  5. The response of vegetation to rising CO2 concentrations plays an important role in future changes in the hydrological cycle

    Science.gov (United States)

    Hong, Tao; Dong, Wenjie; Ji, Dong; Dai, Tanlong; Yang, Shili; Wei, Ting

    2018-04-01

    The effects of increasing CO2 concentrations on plant and carbon cycle have been extensively investigated; however, the effects of changes in plants on the hydrological cycle are still not fully understood. Increases in CO2 modify the stomatal conductance and water use of plants, which may have a considerable effect on the hydrological cycle. Using the carbon-climate feedback experiments from CMIP5, we estimated the responses of plants and hydrological cycle to rising CO2 concentrations to double of pre-industrial levels without climate change forcing. The mode results show that rising CO2 concentrations had a significant influence on the hydrological cycle by changing the evaporation and transpiration of plants and soils. The increases in the area covered by plant leaves result in the increases in vegetation evaporation. Besides, the physiological effects of stomatal closure were stronger than the opposite effects of changes in plant structure caused by the increases in LAI (leaf area index), which results in the decrease of transpiration. These two processes lead to overall decreases in evaporation, and then contribute to increases in soil moisture and total runoff. In the dry areas, the stronger increase in LAI caused the stronger increases in vegetation evaporation and then lead to the overall decreases in P - E (precipitation minus evaporation) and soil moisture. However, the soil moisture in sub-arid and wet areas would increase, and this may lead to the soil moisture deficit worse in the future in the dry areas. This study highlights the need to consider the different responses of plants and the hydrological cycle to rising CO2 in dry and wet areas in future water resources management, especially in water-limited areas.

  6. Rapid emergence of subaerial landmasses and onset of a modern hydrologic cycle 2.5 billion years ago.

    Science.gov (United States)

    Bindeman, I N; Zakharov, D O; Palandri, J; Greber, N D; Dauphas, N; Retallack, G J; Hofmann, A; Lackey, J S; Bekker, A

    2018-05-01

    The history of the growth of continental crust is uncertain, and several different models that involve a gradual, decelerating, or stepwise process have been proposed 1-4 . Even more uncertain is the timing and the secular trend of the emergence of most landmasses above the sea (subaerial landmasses), with estimates ranging from about one billion to three billion years ago 5-7 . The area of emerged crust influences global climate feedbacks and the supply of nutrients to the oceans 8 , and therefore connects Earth's crustal evolution to surface environmental conditions 9-11 . Here we use the triple-oxygen-isotope composition of shales from all continents, spanning 3.7 billion years, to provide constraints on the emergence of continents over time. Our measurements show a stepwise total decrease of 0.08 per mille in the average triple-oxygen-isotope value of shales across the Archaean-Proterozoic boundary. We suggest that our data are best explained by a shift in the nature of water-rock interactions, from near-coastal in the Archaean era to predominantly continental in the Proterozoic, accompanied by a decrease in average surface temperatures. We propose that this shift may have coincided with the onset of a modern hydrological cycle owing to the rapid emergence of continental crust with near-modern average elevation and aerial extent roughly 2.5 billion years ago.

  7. Land surface modelling in hydrology and meteorology – lessons learned from the Baltic Basin

    Directory of Open Access Journals (Sweden)

    L. P. Graham

    2000-01-01

    Full Text Available By both tradition and purpose, the land parameterization schemes of hydrological and meteorological models differ greatly. Meteorologists are concerned primarily with solving the energy balance, whereas hydrologists are most interested in the water balance. Meteorological climate models typically have multi-layered soil parameterisation that solves temperature fluxes numerically with diffusive equations. The same approach is carried over to a similar treatment of water transport. Hydrological models are not usually so interested in soil temperatures, but must provide a reasonable representation of soil moisture to get runoff right. To treat the heterogeneity of the soil, many hydrological models use only one layer with a statistical representation of soil variability. Such a hydrological model can be used on large scales while taking subgrid variability into account. Hydrological models also include lateral transport of water – an imperative if' river discharge is to be estimated. The concept of a complexity chain for coupled modelling systems is introduced, together with considerations for mixing model components. Under BALTEX (Baltic Sea Experiment and SWECLIM (Swedish Regional Climate Modelling Programme, a large-scale hydrological model of runoff in the Baltic Basin is used to review atmospheric climate model simulations. This incorporates both the runoff record and hydrological modelling experience into atmospheric model development. Results from two models are shown. A conclusion is that the key to improved models may be less complexity. Perhaps the meteorological models should keep their multi-layered approach for modelling soil temperature, but add a simpler, yet physically consistent, hydrological approach for modelling snow processes and water transport in the soil. Keywords: land surface modelling; hydrological modelling; atmospheric climate models; subgrid variability; Baltic Basin

  8. Contribution of lateral terrestrial water flows to the regional hydrological cycle: A joint soil-atmospheric moisture tagging procedure with WRF-Hydro

    Science.gov (United States)

    Arnault, Joel; Wei, Jianhui; Zhang, Zhenyu; Wagner, Sven; Kunstmann, Harald

    2017-04-01

    Water resources management requires an accurate knowledge of the behavior of the regional hydrological cycle components, including precipitation, evapotranspiration, river discharge and soil water storage. Atmospheric models such as the Weather Research and Forecasting (WRF) model provide a tool to evaluate these components. The main drawback of these atmospheric models, however, is that the terrestrial segment of the hydrological cycle is reduced to vertical infiltration, and that lateral terrestrial water flows are neglected. Recent model developments have focused on coupled atmospheric-hydrological modeling systems, such as WRF-hydro, in order to take into account subsurface, overland and river flow. The aim of this study is to investigate the contribution of lateral terrestrial water flows to the regional hydrological cycle, with the help of a joint soil-atmospheric moisture tagging procedure. This procedure is the extended version of an existing atmospheric moisture tagging method developed in WRF and WRF-Hydro (Arnault et al. 2017). It is used to quantify the partitioning of precipitation into water stored in the soil, runoff, evapotranspiration, and potentially subsequent precipitation through regional recycling. An application to a high precipitation event on 23 June 2009 in the upper Danube river basin, Germany and Austria, is presented. Precipitating water during this day is tagged for the period 2009-2011. Its contribution to runoff and evapotranspiration decreases with time, but is still not negligible in the summer 2011. At the end of the study period, less than 5 % of the precipitating water on 23 June 2009 remains in the soil. The additionally resolved lateral terrestrial water flows in WRF-Hydro modify the partitioning between surface and underground runoff, in association with a slight increase of evapotranspiration and recycled precipitation. Reference: Arnault, J., R. Knoche, J. Wei, and H. Kunstmann (2016), Evaporation tagging and atmospheric

  9. Modeling large-scale human alteration of land surface hydrology and climate

    Science.gov (United States)

    Pokhrel, Yadu N.; Felfelani, Farshid; Shin, Sanghoon; Yamada, Tomohito J.; Satoh, Yusuke

    2017-12-01

    Rapidly expanding human activities have profoundly affected various biophysical and biogeochemical processes of the Earth system over a broad range of scales, and freshwater systems are now amongst the most extensively altered ecosystems. In this study, we examine the human-induced changes in land surface water and energy balances and the associated climate impacts using a coupled hydrological-climate model framework which also simulates the impacts of human activities on the water cycle. We present three sets of analyses using the results from two model versions—one with and the other without considering human activities; both versions are run in offline and coupled mode resulting in a series of four experiments in total. First, we examine climate and human-induced changes in regional water balance focusing on the widely debated issue of the desiccation of the Aral Sea in central Asia. Then, we discuss the changes in surface temperature as a result of changes in land surface energy balance due to irrigation over global and regional scales. Finally, we examine the global and regional climate impacts of increased atmospheric water vapor content due to irrigation. Results indicate that the direct anthropogenic alteration of river flow in the Aral Sea basin resulted in the loss of 510 km3 of water during the latter half of the twentieth century which explains about half of the total loss of water from the sea. Results of irrigation-induced changes in surface energy balance suggest a significant surface cooling of up to 3.3 K over 1° grids in highly irrigated areas but a negligible change in land surface temperature when averaged over sufficiently large global regions. Results from the coupled model indicate a substantial change in 2 m air temperature and outgoing longwave radiation due to irrigation, highlighting the non-local (regional and global) implications of irrigation. These results provide important insights on the direct human alteration of land surface

  10. Hydrological model for the transport of radioisotope in surface water

    International Nuclear Information System (INIS)

    Adoboah, E.K.

    2011-01-01

    The use of radioisotopes has gained grounds in Ghana as a result of the numerous benefits that could be derived from it. In Ghana, radioisotope materials are used for various purposes in a number of institutions. However, improper disposal of the waste poses threat to the environment. To evaluate the environmental impact of radioisotope pollution, mathematical models play a major role in predicting the pollution level in any medium. This study is concerned with the hydrological model for the transport of radioactive material in the river. The model was composed by employing partial differential equations, describing relevant physical processes evolution (water level, velocities and dissolved substances concentrations) that occurs in water bodies. The mass conservation and momentum laws, state equation and state transport equations are equation system basis. The explicit central difference scheme in space and a forward difference method in time were used for the evaluation of the generalized transport equation, the Advection-Dispersion Equation. A Matlab code was developed to predict the concentration of the radioactive contaminant at any particular time along the river and in a reservoir. The model was able to simulate accurately the various levels of radionuclide concentration changes in the flowing rivers as the flows are augmented by tributary inflows. (au)

  11. How well do CMIP5 Climate Models Reproduce the Hydrologic Cycle of the Colorado River Basin?

    Science.gov (United States)

    Gautam, J.; Mascaro, G.

    2017-12-01

    The Colorado River, which is the primary source of water for nearly 40 million people in the arid Southwestern states of the United States, has been experiencing an extended drought since 2000, which has led to a significant reduction in water supply. As the water demands increase, one of the major challenges for water management in the region has been the quantification of uncertainties associated with streamflow predictions in the Colorado River Basin (CRB) under potential changes of future climate. Hence, testing the reliability of model predictions in the CRB is critical in addressing this challenge. In this study, we evaluated the performances of 17 General Circulation Models (GCMs) from the Coupled Model Intercomparison Project Phase Five (CMIP5) and 4 Regional Climate Models (RCMs) in reproducing the statistical properties of the hydrologic cycle in the CRB. We evaluated the water balance components at four nested sub-basins along with the inter-annual and intra-annual changes of precipitation (P), evaporation (E), runoff (R) and temperature (T) from 1979 to 2005. Most of the models captured the net water balance fairly well in the most-upstream basin but simulated a weak hydrological cycle in the evaporation channel at the downstream locations. The simulated monthly variability of P had different patterns, with correlation coefficients ranging from -0.6 to 0.8 depending on the sub-basin and the models from same parent institution clustering together. Apart from the most-upstream sub-basin where the models were mainly characterized by a negative seasonal bias in SON (of up to -50%), most of them had a positive bias in all seasons (of up to +260%) in the other three sub-basins. The models, however, captured the monthly variability of T well at all sites with small inter-model variabilities and a relatively similar range of bias (-7 °C to +5 °C) across all seasons. Mann-Kendall test was applied to the annual P and T time-series where majority of the models

  12. The mid-cretaceous water bearer: Isotope mass balance quantification of the Albian hydrologic cycle

    Science.gov (United States)

    Ufnar, David F.; Gonzalez, Luis A.; Ludvigson, Greg A.; Brenner, Richard L.; Witzke, B.J.

    2002-01-01

    A latitudinal gradient in meteoric ??18O compositions compiled from paleosol sphaerosiderites throughout the Cretaceous Western Interior Basin (KWIB) (34-75??N paleolatitude) exhibits a steeper, more depleted trend than modern (predicted) values (3.0??? [34??N latitude] to 9.7??? [75??N] lighter). Furthermore, the sphaerosiderite meteoric ??18O latitudinal gradient is significantly steeper and more depleted (5.8??? [34??N] to 13.8??? [75??N] lighter) than a predicted gradient for the warm mid-Cretaceous using modern empirical temperature-??18O precipitation relationships. We have suggested that the steeper and more depleted (relative to the modern theoretical gradient) meteoric sphaerosiderite ??18O latitudinal gradient resulted from increased air mass rainout effects in coastal areas of the KWIB during the mid-Cretaceous. The sphaerosiderite isotopic data have been used to constrain a mass balance model of the hydrologic cycle in the northern hemisphere and to quantify precipitation rates of the equable 'greenhouse' Albian Stage in the KWIB. The mass balance model tracks the evolving isotopic composition of an air mass and its precipitation, and is driven by latitudinal temperature gradients. Our simulations indicate that significant increases in Albian precipitation (34-52%) and evaporation fluxes (76-96%) are required to reproduce the difference between modern and Albian meteoric siderite ??18O latitudinal gradients. Calculations of precipitation rates from model outputs suggest mid-high latitude precipitation rates greatly exceeded modern rates (156-220% greater in mid latitudes [2600-3300 mm/yr], 99% greater at high latitudes [550 mm/yr]). The calculated precipitation rates are significantly different from the precipitation rates predicted by some recent general circulation models (GCMs) for the warm Cretaceous, particularly in the mid to high latitudes. Our mass balance model by no means replaces GCMs. However, it is a simple and effective means of obtaining

  13. Challenges for understanding Antarctic surface hydrology and ice-shelf stability

    Science.gov (United States)

    Kingslake, J.; Bell, R. E.; Banwell, A. F.; Boghosian, A.; Spergel, J.; Trusel, L. D.

    2017-12-01

    It is widely hypothesized that surface meltwater can contribute to ice mass loss in Antarctica through its impact on ice-shelf stability. Meltwater potentially expedites ice-shelf calving by flowing into and enlarging existing crevasses, and could even trigger ice-shelf disintegration via stresses generated by melt ponds. When ice shelves collapse, the adjacent grounded ice accelerates and thins, which contributes to sea-level rise. How these mechanisms mediate the interactions between the atmosphere, the ocean and the ice sheet is the subject of long-standing research efforts. The drainage of water across the surface of the Antarctic Ice Sheet and its ice shelves is beginning to be recognized as another important aspect of the system. Recent studies have revealed that surface meltwater drainage is more widespread than previously thought and that surface hydrological systems in Antarctica may expand and proliferate this century. Contrasting hypotheses regarding the impact of the proliferation of drainage systems on ice-shelf stability have emerged. Surface drainage could deliver meltwater to vulnerable area or export meltwater from ice shelves entirely. Which behavior dominates may have a large impact on the future response of the Antarctic Ice Sheet to atmospheric warming. We will discuss these recent discoveries and hypotheses, as well as new detailed studies of specific areas where hydrological systems are well developed, such as Amery and Nimrod Ice Shelves. We will highlight analogies that can be drawn with Greenlandic (near-)surface hydrology and, crucially, where hydrological systems on the two ice sheets are very different, leading to potentially important gaps in our understanding. Finally, we will look ahead to the key questions that we argue will need to be if we are to determine the role Antarctic surface hydrology could play in the future of the ice sheet. These include: Where does meltwater pond today and how will this change this century? What

  14. Surface runoff in flat terrain: How field topography and runoff generating processes control hydrological connectivity

    NARCIS (Netherlands)

    Appels, W.M.; Bogaart, P.W.; Bogaart, P.W.; Zee, van der S.E.A.T.M.

    2016-01-01

    In flat lowland agricultural catchments in temperate climate zones with highly permeable sandy soils, surface runoff is a rare process with a large impact on the redistribution of sediments and solutes and stream water quality. We examine hydrological data obtained on two field sites in the

  15. Albedo enhancement over land to counteract global warming: impacts on hydrological cycle

    Energy Technology Data Exchange (ETDEWEB)

    Bala, Govindasamy; Nag, Bappaditya [Indian Institute of Science, Divecha Center for Climate Change and Center for Atmospheric and Oceanic Sciences, Bangalore (India)

    2012-09-15

    A recent modelling study has shown that precipitation and runoff over land would increase when the reflectivity of marine clouds is increased to counter global warming. This implies that large scale albedo enhancement over land could lead to a decrease in runoff over land. In this study, we perform simulations using NCAR CAM3.1 that have implications for Solar Radiation Management geoengineering schemes that increase the albedo over land. We find that an increase in reflectivity over land that mitigates the global mean warming from a doubling of CO{sub 2} leads to a large residual warming in the southern hemisphere and cooling in the northern hemisphere since most of the land is located in northern hemisphere. Precipitation and runoff over land decrease by 13.4 and 22.3%, respectively, because of a large residual sinking motion over land triggered by albedo enhancement over land. Soil water content also declines when albedo over land is enhanced. The simulated magnitude of hydrological changes over land are much larger when compared to changes over oceans in the recent marine cloud albedo enhancement study since the radiative forcing over land needed (-8.2 W m{sup -2}) to counter global mean radiative forcing from a doubling of CO{sub 2} (3.3 W m{sup -2}) is approximately twice the forcing needed over the oceans (-4.2 W m{sup -2}). Our results imply that albedo enhancement over oceans produce climates closer to the unperturbed climate state than do albedo changes on land when the consequences on land hydrology are considered. Our study also has important implications for any intentional or unintentional large scale changes in land surface albedo such as deforestation/afforestation/reforestation, air pollution, and desert and urban albedo modification. (orig.)

  16. A Lagrangian perspective of the hydrological cycle in the Congo River basin

    Directory of Open Access Journals (Sweden)

    R. Sorí

    2017-08-01

    Full Text Available The Lagrangian model FLEXPART is used to identify the moisture sources of the Congo River basin (CRB and investigate their role in the hydrological cycle. This model allows us to track atmospheric parcels while calculating changes in the specific humidity through the budget of evaporation minus precipitation. This method permits the annual-scale identification of five continental and four oceanic principal regions that provide moisture to the CRB from both hemispheres over the course of the year. The most important is the CRB, which provides more than 50 % of the total atmospheric moisture contribution to precipitation over itself. Additionally, both the land that extends to the east of the CRB and the eastern equatorial South Atlantic Ocean are very important sources, while the Red Sea source is merely important in the (E − P budget over the CRB despite its high evaporation rate. The moisture-sink patterns over the CRB in air masses that were tracked forward in time from all the sources follow the latitudinal rainfall migration and are mostly highly correlated with the pattern of the precipitation rate, ensuring a link between them. In wet (dry years, the contribution of moisture to precipitation from the CRB over itself increases (decreases. Despite the enhanced evaporative conditions over the basin during dry years, the vertically integrated moisture flux (VIMF divergence inhibits precipitation and suggests the transport of moisture from the CRB to remote regions.

  17. Water Vapor Tacers as Diagnostics of the Regional Atmospheric Hydrologic Cycle

    Science.gov (United States)

    Bosilovich, Michael G.; Schubert, Siegfried D.; Einaudi, Franco (Technical Monitor)

    2000-01-01

    Understanding of the local and remote sources of water vapor can be a valuable diagnostic in understanding the regional atmospheric hydrologic cycle, especially in North America where moisture transport and local evaporation are important sources of water for precipitation. In the present study, we have implemented passive tracers as prognostic variables to follow water vapor evaporated in predetermined regions until the water tracer precipitates. All evaporative sources of water are accounted for by tracers, and the water vapor variable provides the validation of the tracer water and the formulation of the sources and sinks. The Geostationary Operational Environmental Satellites General Circulation Model (GEOS GCM) is used to simulate several summer periods to determine the source regions of precipitation for the United States and India. Using this methodology, a detailed analysis of the recycling of water, interannual variability of the sources of water and links to the Great Plains low-level jet and North American monsoon will be presented. Potential uses in GCM sensitivity studies, predictability studies and data assimilation especially regarding the North American monsoon and GEWEX America Prediction Project (GAPP) will be discussed.

  18. Direct observations of rock moisture, a hidden component of the hydrologic cycle.

    Science.gov (United States)

    Rempe, Daniella M; Dietrich, William E

    2018-03-13

    Recent theory and field observations suggest that a systematically varying weathering zone, that can be tens of meters thick, commonly develops in the bedrock underlying hillslopes. Weathering turns otherwise poorly conductive bedrock into a dynamic water storage reservoir. Infiltrating precipitation typically will pass through unsaturated weathered bedrock before reaching groundwater and running off to streams. This invisible and difficult to access unsaturated zone is virtually unexplored compared with the surface soil mantle. We have proposed the term "rock moisture" to describe the exchangeable water stored in the unsaturated zone in weathered bedrock, purposely choosing a term parallel to, but distinct from, soil moisture, because weathered bedrock is a distinctly different material that is distributed across landscapes independently of soil thickness. Here, we report a multiyear intensive campaign of quantifying rock moisture across a hillslope underlain by a thick weathered bedrock zone using repeat neutron probe measurements in a suite of boreholes. Rock moisture storage accumulates in the wet season, reaches a characteristic upper value, and rapidly passes any additional rainfall downward to groundwater. Hence, rock moisture storage mediates the initiation and magnitude of recharge and runoff. In the dry season, rock moisture storage is gradually depleted by trees for transpiration, leading to a common lower value at the end of the dry season. Up to 27% of the annual rainfall is seasonally stored as rock moisture. Significant rock moisture storage is likely common, and yet it is missing from hydrologic and land-surface models used to predict regional and global climate.

  19. Direct observations of rock moisture, a hidden component of the hydrologic cycle

    Science.gov (United States)

    Rempe, Daniella M.; Dietrich, William E.

    2018-03-01

    Recent theory and field observations suggest that a systematically varying weathering zone, that can be tens of meters thick, commonly develops in the bedrock underlying hillslopes. Weathering turns otherwise poorly conductive bedrock into a dynamic water storage reservoir. Infiltrating precipitation typically will pass through unsaturated weathered bedrock before reaching groundwater and running off to streams. This invisible and difficult to access unsaturated zone is virtually unexplored compared with the surface soil mantle. We have proposed the term “rock moisture” to describe the exchangeable water stored in the unsaturated zone in weathered bedrock, purposely choosing a term parallel to, but distinct from, soil moisture, because weathered bedrock is a distinctly different material that is distributed across landscapes independently of soil thickness. Here, we report a multiyear intensive campaign of quantifying rock moisture across a hillslope underlain by a thick weathered bedrock zone using repeat neutron probe measurements in a suite of boreholes. Rock moisture storage accumulates in the wet season, reaches a characteristic upper value, and rapidly passes any additional rainfall downward to groundwater. Hence, rock moisture storage mediates the initiation and magnitude of recharge and runoff. In the dry season, rock moisture storage is gradually depleted by trees for transpiration, leading to a common lower value at the end of the dry season. Up to 27% of the annual rainfall is seasonally stored as rock moisture. Significant rock moisture storage is likely common, and yet it is missing from hydrologic and land-surface models used to predict regional and global climate.

  20. HESS Opinions "Biological catalysis of the hydrological cycle: life's thermodynamic function"

    Science.gov (United States)

    Michaelian, K.

    2012-08-01

    Darwinian theory depicts life as being overwhelmingly consumed by a fight for survival in a hostile environment. However, from a thermodynamic perspective, life is a dynamic, out of equilibrium process, stabilizing and coevolving in concert with its abiotic environment. The living components of the biosphere on the Earth's surface of greatest biomass, the plants and cyanobacteria, are involved in the transpiration of a vast amount of water. Transpiration is part of the global water cycle, and it is this cycle that distinguishes Earth from its apparently life-barren neighboring planets, Venus and Mars. The dissipation of sunlight into heat by organic molecules in the biosphere, and its coupling to the water cycle (as well as other abiotic processes), is by far the greatest entropy-producing process occurring on Earth. Life, from this perspective, can be viewed as performing an important thermodynamic function, acting as a dynamic catalyst by aiding irreversible abiotic processes such as the water cycle, hurricanes, and ocean and wind currents to produce entropy. The role of animals in this view is that of unwitting but dedicated servants of the plants and cyanobacteria, helping them to grow, and to spread into initially inhospitable areas.

  1. HESS Opinions "Biological catalysis of the hydrological cycle: life's thermodynamic function"

    Directory of Open Access Journals (Sweden)

    K. Michaelian

    2012-08-01

    Full Text Available Darwinian theory depicts life as being overwhelmingly consumed by a fight for survival in a hostile environment. However, from a thermodynamic perspective, life is a dynamic, out of equilibrium process, stabilizing and coevolving in concert with its abiotic environment. The living components of the biosphere on the Earth's surface of greatest biomass, the plants and cyanobacteria, are involved in the transpiration of a vast amount of water. Transpiration is part of the global water cycle, and it is this cycle that distinguishes Earth from its apparently life-barren neighboring planets, Venus and Mars. The dissipation of sunlight into heat by organic molecules in the biosphere, and its coupling to the water cycle (as well as other abiotic processes, is by far the greatest entropy-producing process occurring on Earth. Life, from this perspective, can be viewed as performing an important thermodynamic function, acting as a dynamic catalyst by aiding irreversible abiotic processes such as the water cycle, hurricanes, and ocean and wind currents to produce entropy. The role of animals in this view is that of unwitting but dedicated servants of the plants and cyanobacteria, helping them to grow, and to spread into initially inhospitable areas.

  2. Using n-alkane records to constrain carbon cycle - hydrological cycle coupling: Case study from the Northern Hemisphere mid-latitudes during the PETM

    Science.gov (United States)

    Krishnan, S.; Pagani, M.; Tipple, B. J.

    2010-12-01

    The early Eocene was a warmer world compared to the present and is characterized by rising temperatures interspersed with rapid hyperthermal events. During the largest of these rapid warming events; the Paleocene-Eocene Thermal Maximum (PETM), proxy records suggest that sea surface temperatures (SST) rose by 3-5 deg. C in the tropics (Zachos et al., 2003, Tripati and Elderfield, 2004), >5 deg. C in the Arctic (Sluijs et al., 2006) and perhaps has high as 9 deg. C in some sub-Antarctic regions (Kennett and Stott, 1991; Thomas et al., 1999). This warming is believed to be the result of massive input of 13C-depleted carbon into the ocean-atmosphere system, evidenced by the large negative carbon isotope excursion (CIE) and carbonate dissolution associated with the event. However, there are several questions regarding the exact mechanism of warming and feedbacks between the carbon cycle and climate. Did climate shift prior to the main event that led to the release of isotopically light carbon? Do we observe consistent leads or lags between changes in carbon isotopes and hydrological conditions during warm intervals? This study aims to reconstruct hydrological changes in the in the Northern Hemisphere mid-latitudes during the PETM using terrestrial biomarkers. Terrestrial biomarkers, such leaf-wax lipids stored in sediments, have the unique advantage of recording carbon and hydrogen isotopic compositions of atmospheric CO2 (modified by plant fractionation) and precipitation (modified by plant fractionation and evapotranspiration), allowing evaluation of the relative timing of carbon and hydrogen isotopic (i.e., climate) shifts. In this study, we compile and present three mid-latitude PETM records from the Northern Hemisphere, i.e. Alamedilla (Spain), Cicogna and Forada (Italy). The Cicogna and Forada sections are located in the Belluno basin (~12 km apart). Preliminary results do not indicate any significant pre-excursion hydrogen isotope changes at Cicogna, while at

  3. Hydrology of prairie wetlands: Understanding the integrated surface-water and groundwater processes

    Science.gov (United States)

    Hayashi, Masaki; van der Kamp, Garth; Rosenberry, Donald O.

    2016-01-01

    Wetland managers and policy makers need to make decisions based on a sound scientific understanding of hydrological and ecological functions of wetlands. This article presents an overview of the hydrology of prairie wetlands intended for managers, policy makers, and researchers new to this field (e.g., graduate students), and a quantitative conceptual framework for understanding the hydrological functions of prairie wetlands and their responses to changes in climate and land use. The existence of prairie wetlands in the semi-arid environment of the Prairie-Pothole Region (PPR) depends on the lateral inputs of runoff water from their catchments because mean annual potential evaporation exceeds precipitation in the PPR. Therefore, it is critically important to consider wetlands and catchments as highly integrated hydrological units. The water balance of individual wetlands is strongly influenced by runoff from the catchment and the exchange of groundwater between the central pond and its moist margin. Land-use practices in the catchment have a sensitive effect on runoff and hence the water balance. Surface and subsurface storage and connectivity among individual wetlands controls the diversity of pond permanence within a wetland complex, resulting in a variety of eco-hydrological functionalities necessary for maintaining the integrity of prairie-wetland ecosystems.

  4. The hydrological cycle in the high Pamir Mountains: how temperature and seasonal precipitation distribution influence stream flow in the Gunt catchment, Tajikistan

    Science.gov (United States)

    Pohl, E.; Knoche, M.; Gloaguen, R.; Andermann, C.; Krause, P.

    2014-12-01

    Complex climatic interactions control hydrological processes in high mountains that in their turn regulate the erosive forces shaping the relief. To unravel the hydrological cycle of a glaciated watershed (Gunt River) considered representative of the Pamirs' hydrologic regime we developed a remote sensing-based approach. At the boundary between two distinct climatic zones dominated by Westerlies and Indian summer monsoon, the Pamir is poorly instrumented and only a few in situ meteorological and hydrological data are available. We adapted a suitable conceptual distributed hydrological model (J2000g). Interpolations of the few available in situ data are inadequate due to strong, relief induced, spatial heterogeneities. Instead we use raster data, preferably from remote sensing sources depending on availability and validation. We evaluate remote sensing-based precipitation and temperature products. MODIS MOD11 surface temperatures show good agreement with in situ data, perform better than other products and represent a good proxy for air temperatures. For precipitation we tested remote sensing products as well as the HAR10 climate model data and the interpolation-based APHRODITE dataset. All products show substantial differences both in intensity and seasonal distribution with in-situ data. Despite low resolutions, the datasets are able to sustain high model efficiencies (NSE ≥0.85). In contrast to neighbouring regions in the Himalayas or the Hindukush, discharge is dominantly the product of snow and glacier melt and thus temperature is the essential controlling factor. 80% of annual precipitation is provided as snow in winter and spring contrasting peak discharges during summer. Hence, precipitation and discharge are negatively correlated and display complex hysteresis effects that allow to infer the effect of inter-annual climatic variability on river flow. We infer the existence of two subsurface reservoirs. The groundwater reservoir (providing 40% of annual

  5. Sensitivity studies on the impacts of Tibetan Plateau snowpack pollution on the Asian hydrological cycle and monsoon climate

    Science.gov (United States)

    Qian, Y.; Flanner, M.; Leung, R.; Wang, W.

    2012-04-01

    The Tibetan Plateau (TP) has long been identified to be critical in regulating the Asian monsoon climate and hydrological cycle. In this modeling study a series of numerical experiments with a global climate model are designed to simulate radiative effect of black carbon (BC) and dust in snow, and to assess the relative impacts of anthropogenic CO2 and carbonaceous particles in the atmosphere and snow on the snowpack over the TP and subsequent impacts on the Asian monsoon climate and hydrological cycle. Simulations results show a large BC content in snow over the TP, especially the southern slope. Because of the high aerosol content in snow and large incident solar radiation in the low latitude and high elevation, the TP exhibits the largest surface radiative flux changes induced by aerosols (e.g. BC, Dust) in snow compared to any other snow-covered regions in the world. Simulation results show that the aerosol-induced snow albedo perturbations generate surface radiative flux changes of 5-25 W m-2 during spring, with a maximum in April or May. BC-in-snow increases the surface air temperature by around 1.0oC averaged over the TP and reduces spring snowpack over the TP more than pre-industrial to present CO2 increase and carbonaceous particles in the atmosphere. As a result, runoff increases during late winter and early spring but decreases during late spring and early summer (i.e. a trend toward earlier melt dates). The snowmelt efficacy, defined as the snowpack reduction per unit degree of warming induced by the forcing agent, is 1-4 times larger for BC-in-snow than CO2 increase during April-July, indicating that BC-in-snow more efficiently accelerates snowmelt because the increased net solar radiation induced by reduced albedo melts the snow more efficiently than snow melt due to warming in the air. The TP also influences the South (SAM) and East (EAM) Asian monsoon through its dynamical and thermal forcing. Simulation results show that during boreal spring

  6. Sensitivity studies on the impacts of Tibetan Plateau snowpack pollution on the Asian hydrological cycle and monsoon climate

    Energy Technology Data Exchange (ETDEWEB)

    Qian, Yun; Flanner, M G; Leung, Lai-Yung R; Wang, Weiguo

    2011-03-02

    The Tibetan Plateau (TP), the highest and largest plateau in the world, has long been identified to be critical in regulating the Asian monsoon climate and hydrological cycle. The snowpack and glaciers over the TP provide fresh water to billions of people in Asian countries, but the TP glaciers have been retreating extensively at a speed faster than any other part of the world. In this study a series of experiments with a global climate model are designed to simulate black carbon (BC) and dust in snow and their radiative forcing and to assess the relative impacts of anthropogenic CO2 and carbonaceous particles in the atmosphere and snow, respectively, on the snowpack over the TP, as well as their subsequent impacts on the Asian monsoon climate and hydrological cycle. Results show a large BC content in snow over the TP, especially the southern slope, with concentration larger than 100 µk/kg. Because of the high aerosol content in snow and large incident solar radiation in the low latitude and high elevation, the TP exhibits the largest surface radiative forcing induced by aerosols (e.g. BC, Dust) in snow compared to other snow-covered regions in the world. The aerosol-induced snow albedo perturbations generate surface radiative forcing of 5-25 W m-2 during spring, with a maximum in April or May. BC-in-snow increases the surface air temperature by around 1.0°C averaged over the TP and reduces snowpack over the TP more than that induced by pre-industrial to present CO2 increase and carbonaceous particles in the atmosphere during spring. As a result, runoff increases during late winter and early spring but decreases during late spring and early summer (i.e. a trend toward earlier melt dates). The snowmelt efficacy, defined as the snowpack reduction per unit degree of warming induced by the forcing agent, is 1-4 times larger for BC-in-snow than CO2 increase during April-July, indicating that BC-in-snow more efficiently

  7. Linking freshwater tidal hydrology to carbon cycling in bottomland hardwood wetlands

    Science.gov (United States)

    Carl C. Trettin; Brooke J. Czwartacki; Craig J. Allan; Devendra M. Amatya

    2016-01-01

    Hydrology is recognized as one of the principal factors regulating soil biogeochemical processes in forested wetlands. However, the consequences of tidally mediated hydrology are seldom considered within forested wetlands that occur along tidal water bodies. These tidal water bodies may be either fresh or brackish, and the tidal streams function as a reservoir to...

  8. Regional Climate Simulations of the Hydrological Cycle in the Iberian Peninsula with a Coupled WRF-HYDRO Model

    Science.gov (United States)

    Rios-Entenza, A.; Miguez-Macho, G.

    2008-12-01

    Land-atmosphere water exchanges and heat fluxes play an important role in climate and particularly in controlling precipitation in water-limited regions. One of such regions is the Iberian Peninsula, and in this study we examine the relevance of water recycling in convective precipitation regimes of the Fall and Spring there, when rainfall is critical for agriculture and many other human activities. We conducted simulations with WRF-ARW model at 5 km horizontal resolution, using a 1500 km x 1500 km nested grid that covers the Iberian Peninsula, with a parent domain that uses spectral nudging in order to avoid the distortion of the large-scale circulation caused by the interaction of the modeled flow with the lateral boundaries of the nested grid. For land-surface interactions we coupled WRF with the LEAF-HYDRO land surface model, which includes water table dynamics. We use therefore a tool that simulates the entire water cycle, including the water table, which has been reported to be critical for soil moisture dynamics in semi-arid regions like the Iberian Peninsula. For each one of the events that we selected, we performed two simulations: a control one, where all land-atmosphere feedbacks are taken into account, and the experiment, where infiltration of the precipitated water into the soil was suppressed. In this manner we explore the role of upward latent and sensible heat fluxes and evapotranspiration in precipitation dynamics. Preliminary results suggest that water recycling is a key factor in extending convective precipitation during several days, and that the total new water added in the area as a whole is only a fraction of the total measured rainfall. An estimation of this fraction is very important to better understanding the water budget and for hydrological planning in this water-stressed region.

  9. Identification of land use and other anthropogenic impacts on nitrogen cycling using stable isotopes and distributed hydrologic modeling

    Science.gov (United States)

    O'Connell, M. T.; Macko, S. A.

    2017-12-01

    Reactive modeling of sources and processes affecting the concentration of NO3- and NH4+ in natural and anthropogenically influenced surface water can reveal unexpected characteristics of the systems. A distributed hydrologic model, TREX, is presented that provides opportunities to study multiscale effects of nitrogen inputs, outputs, and changes. The model is adapted to run on parallel computing architecture and includes the geochemical reaction module PhreeqcRM, which enables calculation of δ15N and δ18O from biologically mediated transformation reactions in addition to mixing and equilibration. Management practices intended to attenuate nitrate in surface and subsurface waters, in particular the establishment of riparian buffer zones, are variably effective due to spatial heterogeneity of soils and preferential flow through buffers. Accounting for this heterogeneity in a fully distributed biogeochemical model allows for more efficient planning and management practices. Highly sensitive areas within a watershed can be identified based on a number of spatially variable parameters, and by varying those parameters systematically to determine conditions under which those areas are under more or less critical stress. Responses can be predicted at various scales to stimuli ranging from local changes in cropping regimes to global shifts in climate. This work presents simulations of conditions showing low antecedent nitrogen retention versus significant contribution of old nitrate. Nitrogen sources are partitioned using dual isotope ratios and temporally varying concentrations. In these two scenarios, we can evaluate the efficiency of source identification based on spatially explicit information, and model effects of increasing urban land use on N biogeochemical cycling.

  10. Assessment of the effect of climate change on the hydrological cycle

    DEFF Research Database (Denmark)

    Karlsson, Ida Bjørnholt

    , implying that when doing a future impact study, hydrological predictions could be compromised when using hydrological models calibrated on present time series. The hydrological response to a future high-end emission scenario was also explored. The hydrological model simulations and drought indices analyses...... showed longer and dryer periods leading to enhanced root zone dryness, lowered river discharge, and decreasing groundwater head elevation increasing the risk of stream flow drought and crop failure. In contrast, wetter winters will lead to increased flood risks. Finally, the influence of choosing...... a specific impact study setup was also investigated by simulating and analysing results from three factors; four climate models in combinations with three hydrological models and four land use scenarios. Results showed that the climate model was the dominant uncertainty factor on stream flow and hydraulic...

  11. Representing Northern Peatland Hydrology and Biogeochemistry with ALM Land Surface Model

    Science.gov (United States)

    Shi, X.; Ricciuto, D. M.; Thornton, P. E.; Hanson, P. J.; Xu, X.; Mao, J.; Warren, J.; Yuan, F.; Norby, R. J.; Sebestyen, S.; Griffiths, N.; Weston, D. J.; Walker, A.

    2017-12-01

    Northern peatlands are likely to be important in future carbon cycle-climate feedbacks due to their large carbon pool and vulnerability to hydrological change. Predictive understanding of northern peatland hydrology is a necessary precursor to understanding the fate of massive carbon stores in these systems under the influence of present and future climate change. Current models have begun to address microtopographic controls on peatland hydrology, but none have included a prognostic calculation of peatland water table depth for a vegetated wetland, independent of prescribed regional water tables. Firstly, we introduce a new configuration of the land model (ALM) of Accelerated Climate model for Energy (ACME), which includes a fully prognostic water table calculation for a vegetated peatland. Secondly, we couple our new hydrology treatment with vertically structured soil organic matter pool, and the addition of components from methane biogeochemistry. Thirdly, we introduce a new PFT for mosses and implement the water content dynamics and physiology of mosses. We inform and test our model based on SPRUCE experiment to get the reasonable results for the seasonal dynamics water table depths, water content dynamics and physiology of mosses, and correct soil carbon profiles. Then, we use our new model structure to test the how the water table depth and CH4 emission will respond to elevated CO2 and different warming scenarios.

  12. Recent Trends of the Tropical Hydrological Cycle Inferred from Global Precipitation Climatology Project and International Satellite Cloud Climatology Project data

    Science.gov (United States)

    Zhou, Y. P.; Xu, Kuan-Man; Sud, Y. C.; Betts, A. K.

    2011-01-01

    Scores of modeling studies have shown that increasing greenhouse gases in the atmosphere impact the global hydrologic cycle; however, disagreements on regional scales are large, and thus the simulated trends of such impacts, even for regions as large as the tropics, remain uncertain. The present investigation attempts to examine such trends in the observations using satellite data products comprising Global Precipitation Climatology Project precipitation and International Satellite Cloud Climatology Project cloud and radiation. Specifically, evolving trends of the tropical hydrological cycle over the last 20-30 years were identified and analyzed. The results show (1) intensification of tropical precipitation in the rising regions of the Walker and Hadley circulations and weakening over the sinking regions of the associated overturning circulation; (2) poleward shift of the subtropical dry zones (up to 2deg/decade in June-July-August (JJA) in the Northern Hemisphere and 0.3-0.7deg/decade in June-July-August and September-October-November in the Southern Hemisphere) consistent with an overall broadening of the Hadley circulation; and (3) significant poleward migration (0.9-1.7deg/decade) of cloud boundaries of Hadley cell and plausible narrowing of the high cloudiness in the Intertropical Convergence Zone region in some seasons. These results support findings of some of the previous studies that showed strengthening of the tropical hydrological cycle and expansion of the Hadley cell that are potentially related to the recent global warming trends.

  13. Coupling hydrological and impact assessment models to explore nutrient cycling in freshwater systems

    Science.gov (United States)

    Bouwman, Lex; van Beek, Rens; Beusen, Arthur; Mogollón, José; Middelburg, Jack

    2016-04-01

    The IMAGE-Global Nutrient Model (GNM) is a new globally distributed, spatially explicit model in which the hydrology model PCR-GLOBWB is coupled to the integrated assessment model IMAGE to simulate nitrogen (N) and phosphorus (P) delivery, and then with a spiraling ecological approach to simulating instream biogeochemistry. Routing the water with dissolved and suspended N and P from upstream grid cells occurs simultaneous with N and P delivery to water bodies within grid cells from diffuse and point sources (wastewater). IMAGE-GNM describes the following diffuse sources associated with the water flow: surface runoff, shallow and deep groundwater, riparian zones. Depending on the landscape features, all these flows may be present within one grid cell. Furthermore, diffuse N and P inputs occur through allochtonous organic matter inputs via litterfall in (temporarily) inundated river floodplains, and atmospheric deposition. In the spiraling concept, the residence time of the water and nutrient uptake velocity determine N and P retention in water bodies. Validation of model results with observations yields acceptable agreement given the global scale of the uncalibrated model. Sensitivity analysis shows shifts in the importance of the different sources, with decreasing importance of natural sources and increasing influence of wastewater and agriculture. IMAGE-GNM can be employed to study the interaction between society and the environment over prolonged time periods. Here we show results for the full 20th century.

  14. Land surface water cycles observed with satellite sensors

    Science.gov (United States)

    Nghiem, Son V.; Njoku, E. G.; Brakenridge, G. R.; Kim, Y.

    2005-01-01

    Acceleration of the global water cycle may lead to increased global precipitation, faster evaporation and a consequent exacerbation of hydrologic extreme. In the U.S. national assessment of the potential consequences of climate variability and change, two GCMs (CGCM1 and HadCM2) show a large increase in precipitation in the future over the southwestern U.S. particularly during winter (Felzer and Heard, 1999). Increased precipitation potentially has important impacts on agricultural and water use in the southeast U.S. (Hatch et al., 1999) and in the central Great Plains (Nielsen, 1997). A hurricane model predicts a 40% precipitation increase for severe hurricanes affecting southeastern Florida, which provokes substantially greater flooding that could negate most of the benefits of present water-management practices in this basin (Gutowski et al., 1994). Thus, it is important to observe the hydroclimate on a continuous longterm basis to address the question of increased precipitation in the enhanced water cycle.

  15. Spatially explicit simulation of hydrologically controlled carbon and nitrogen cycles and associated feedback mechanisms in a boreal ecosystem

    Science.gov (United States)

    Govind, Ajit; Chen, Jing Ming; Ju, Weimin

    2009-06-01

    Ecosystem models that simulate biogeochemical processes usually ignore hydrological controls that govern them. It is quite possible that topographically driven water fluxes significantly influence the spatial distribution of C sources and sinks because of their large contribution to the local water balance. To investigate this, we simulated biogeochemical processes along with the associated feedback mechanisms in a boreal ecosystem using a spatially explicit hydroecological model, boreal ecosystem productivity simulator (BEPS)-TerrainLab V2.0, that has a tight coupling of ecophysiological, hydrological, and biogeochemical processes. First, the simulated dynamics of snowpack, soil temperature, net ecosystem productivity (NEP), and total ecosystem respiration (TER) were validated with high-frequency measurements for 2 years. The model was able to explain 80% of the variability in NEP and 84% of the variability in TER. Further, we investigated the influence of topographically driven subsurface base flow on soil C and N cycling and on the spatiotemporal patterns of C sources and sinks using three hydrological modeling scenarios that differed in hydrological conceptualizations. In general, the scenarios that had nonexplicit hydrological representation overestimated NEP, as opposed to the scenario that had an explicit (realistic) representation. The key processes controlling the NEP differences were attributed to the combined effects of variations in photosynthesis (due to changes in stomatal conductance and nitrogen (N) availability), heterotrophic respiration, and autotrophic respiration, all of which occur simultaneously affecting NEP. Feedback relationships were also found to exacerbate the differences. We identified six types of NEP differences (biases), of which the most commonly found was due to an underestimation of the existing C sources, highlighting the vulnerability of regional-scale ecosystem models that ignore hydrological processes.

  16. Effects of Land Cover Changes to the Quantity of Water Supply and Hydrologic Cycle using Water Balance Models

    Directory of Open Access Journals (Sweden)

    Caja CC

    2018-01-01

    Full Text Available The hydrologic cycle is a recurring consequence of different forms of movement of water and changes of its physical state on a given area of the earth. The land cover of a certain area is a significant factor affecting the watershed hydrology. This also affects the quantity of water supply within the watershed. This study assessed the impacts of the changing land cover of the Ipo watershed, a part of the Angat-Ipo-La Mesa water system which is the main source of Metro Manila’s water supply. The environmental impacts were assessed using the interaction of vegetation cover changes and the output flow rates in Ipo watershed. Using hydrologic modelling system, the hydrological balance using rainfall, vegetation and terrain data of the watershed was simulated. Over the years, there has been a decreasing land cover within the watershed caused mostly by deforestation and other human activities. This significant change in the land cover resulted to extreme increase in water discharge at all streams and rivers in the watershed and the water balance of the area were affected as saturation and shape of the land terrain changes.

  17. Introduction to special section on Uncertainty Assessment in Surface and Subsurface Hydrology : An overview of issues and challenges

    NARCIS (Netherlands)

    Montanari, A.; Shoemaker, C.A.; Van de Giesen, N.C.

    This paper introduces the Water Resources Research special section on Uncertainty Assessment in Surface and Subsurface Hydrology. Over the past years, hydrological literature has seen a large increase in the number of papers dealing with uncertainty. In this article, we present an overview of the

  18. Modeling the Hydrological Cycle in the Atmosphere of Mars: Influence of a Bimodal Size Distribution of Aerosol Nucleation Particles

    Science.gov (United States)

    Shaposhnikov, Dmitry S.; Rodin, Alexander V.; Medvedev, Alexander S.; Fedorova, Anna A.; Kuroda, Takeshi; Hartogh, Paul

    2018-02-01

    We present a new implementation of the hydrological cycle scheme into a general circulation model of the Martian atmosphere. The model includes a semi-Lagrangian transport scheme for water vapor and ice and accounts for microphysics of phase transitions between them. The hydrological scheme includes processes of saturation, nucleation, particle growth, sublimation, and sedimentation under the assumption of a variable size distribution. The scheme has been implemented into the Max Planck Institute Martian general circulation model and tested assuming monomodal and bimodal lognormal distributions of ice condensation nuclei. We present a comparison of the simulated annual variations, horizontal and vertical distributions of water vapor, and ice clouds with the available observations from instruments on board Mars orbiters. The accounting for bimodality of aerosol particle distribution improves the simulations of the annual hydrological cycle, including predicted ice clouds mass, opacity, number density, and particle radii. The increased number density and lower nucleation rates bring the simulated cloud opacities closer to observations. Simulations show a weak effect of the excess of small aerosol particles on the simulated water vapor distributions.

  19. [Effects of soil crusts on surface hydrology in the semiarid Loess hilly area].

    Science.gov (United States)

    Wei, Wei; Wen, Zhi; Chen, Li-Ding; Chen, Jin; Wu, Dong-Ping

    2012-11-01

    Soil crusts are distributed extensively in the Chinese Loess Plateau and play key roles in surface hydrological processes. In this study, a typical loess hilly region in Anjiagou catchment, Dingxi city, Gansu province was selected as the study region, and soil crusts in the catchment were investigated. Then, the hydrological effect of soil crusts was studied by using multi-sampling and hydrological monitoring experiments. Several key results were shown as follows. Firstly, compared with bared soil without crust cover, soil crusts can greatly reduce the bulk density, improve the porosity of soil, and raise the holding capacity of soil moisture which ranges from 1.4 to 1.9 times of that of bared soil. Secondly, the role of soil crust on rainfall interception was very significant. Moss crust was found to be strongest on rainfall interception, followed by synantectic crusts and lichen crusts. Bared soil without covering crusts was poorest in resisting rainfall splash. Thirdly, hydrological simulation experiments indicate that soil crusts play a certain positive role in promoting the water infiltration capacity, and the mean infiltration rate of the crusted soil was 2 times higher than that of the no-crust covered soils. While the accumulated infiltrated water amounts was also far higher than that of the bared soil.

  20. The atmospheric branch of the hydrological cycle over the Indus, Ganges, and Brahmaputra river basins

    Science.gov (United States)

    Sorí, Rogert; Nieto, Raquel; Drumond, Anita; Vicente-Serrano, Sergio M.; Gimeno, Luis

    2017-12-01

    The atmospheric branch of the hydrological cycle over the Indus, Ganges, and Brahmaputra river basins (IRB, GRB, and BRB respectively) in the South Asian region was investigated. The 3-dimensional model FLEXPART v9.0 was utilized. An important advantage of this model is that it permits the computation of the freshwater budget on air parcel trajectories both backward and forward in time from 0.1 to 1000 hPa in the atmospheric vertical column. The analysis was conducted for the westerly precipitation regime (WPR) (November-April) and the monsoonal precipitation regime (MPR) (May-October) in the period from 1981 to 2015. The main terrestrial and oceanic climatological moisture sources for the IRB, GRB, and BRB and their contribution to precipitation over the basins were identified. For the three basins, the most important moisture sources for precipitation are (i) in the continental regions, the land masses to the west of the basins (in this case called western Asia), the Indian region (IR), and the basin itself, and (ii) from the ocean, the utmost sources being the Indian Ocean (IO) and the Bay of Bengal (BB), and it is remarkable that despite the amount of moisture reaching the Indus and Ganges basins from land sources, the moisture supply from the IO seems to be first associated with the rapid increase or decrease in precipitation over the sources in the MPR. The technique of the composites was used to analyse how the moisture uptake values spatially vary from the sources (the budget of evaporation minus precipitation (E - P) was computed in a backward experiment from the basins) but during the pre-onset and pre-demise dates of the monsoonal rainfall over each basin; this confirmed that over the last days of the monsoon at the basins, the moisture uptake areas decrease in the IO. The Indian region, the Indian Ocean, the Bay of Bengal, and the basins themselves are the main sources of moisture responsible for negative (positive) anomalies of moisture contribution to

  1. The role of the hydrological cycle on the temporal patterns of macroinvertebrate assemblages in an Andean foothill stream in Colombia

    Directory of Open Access Journals (Sweden)

    María I. Ríos-Pulgarín

    2016-03-01

    Full Text Available The seasonal and interannual changes in the structure, composition and functional feeding groups of the macroinvertebrate assemblage of the Guarinó River, a torrential system located in the Colombian Andean foothills, were examined in relation to the physical and chemical environmental changes associated with the hydrological cycle and the El Niño-Niña/Southern Oscillation (ENSO between 2007 and 2010. Benthic samples were collected at three sites in the lower sections of the river. A total of 127 taxa were collected in the study, with the total taxonomic richness per site ranging from 82 to 96 taxa and benthos density averaging 5.41 ind. m-2. The density showed a tendency to decrease in periods of maximum river level and flow, particularly during La Niña phenomena, and to increase in dry periods, especially in the third year (2009-2010 during El Niño phenomena. The presence and abundance of taxa, functional feeding groups and life habits were regulated by environmental parameters associated with hydrological variability, derived of ENSO phenomena, especially flow rate values. The assemblage showed high taxonomic and functional diversity, which is characteristic of ecosystems affected by recurrent hydrological disturbances, exhibiting differentiated responses based on adaptive strategies against the local hydrologic regime that allow fast recovery under conditions like ENSO phenomena. Such responses include composition changes according to adaptations to different hydrological scenarios, the predominance of generalist trophic guilds and taxa with plasticity in their habits and range of environmental tolerance.

  2. Hydrologic cycle and dynamics of aquatic macrophytes in two intermittent rivers of the semi-arid region of Brazil

    Directory of Open Access Journals (Sweden)

    F. Pedro

    Full Text Available The dynamics of aquatic macrophytes in intermittent rivers is generally related to the characteristics of the resistance and resilience of plants to hydrologic disturbances of flood and drought. In the semi-arid region of Brazil, intermittent rivers and streams are affected by disturbances with variable intensity, frequency, and duration throughout their hydrologic cycles. The aim of the present study is to determine the occurrence and variation of biomass of aquatic macrophyte species in two intermittent rivers of distinct hydrologic regimes. Their dynamics were determined with respect to resistance and resilience responses of macrophytes to flood and drought events by estimating the variation of biomass and productivity throughout two hydrologic cycles. Twenty-one visits were undertaken in the rewetting, drying, and drought phases in a permanent puddle in the Avelós stream and two temporary puddles in the Taperoá river, state of Paraíba, Northeast Brazil. The sampling was carried out by using the square method. Floods of different magnitudes occurred during the present study in the river and in the stream. The results showed that floods and droughts are determining factors in the occurrence of macrophytes and in the structure of their aquatic communities. The species richness of the aquatic macrophyte communities was lower in the puddles of the river and stream subject to flood events, when compared to areas where the run-off water is retained. At the beginning of the recolonization process, the intensity of the floods was decisive in the productivity and biomass of the aquatic macrophytes in the Taperoá river and the Avelós stream. In intermediate levels of disturbance, the largest values of productivity and biomass and the shortest time for starting the recolonization process occurred.

  3. Combined use of stable isotopes and hydrologic modeling to better understand nutrient sources and cycling in highly altered systems (Invited)

    Science.gov (United States)

    Young, M. B.; Kendall, C.; Guerin, M.; Stringfellow, W. T.; Silva, S. R.; Harter, T.; Parker, A.

    2013-12-01

    The Sacramento and San Joaquin Rivers provide the majority of freshwater for the San Francisco Bay Delta. Both rivers are important sources of drinking and irrigation water for California, and play critical roles in the health of California fisheries. Understanding the factors controlling water quality and primary productivity in these rivers and the Delta is essential for making sound economic and environmental water management decisions. However, these highly altered surface water systems present many challenges for water quality monitoring studies due to factors such as multiple potential nutrient and contaminant inputs, dynamic source water inputs, and changing flow regimes controlled by both natural and engineered conditions. The watersheds for both rivers contain areas of intensive agriculture along with many other land uses, and the Sacramento River receives significant amounts of treated wastewater from the large population around the City of Sacramento. We have used a multi-isotope approach combined with mass balance and hydrodynamic modeling in order to better understand the dominant nutrient sources for each of these rivers, and to track nutrient sources and cycling within the complex Delta region around the confluence of the rivers. High nitrate concentrations within the San Joaquin River fuel summer algal blooms, contributing to low dissolved oxygen conditions. High δ15N-NO3 values combined with the high nitrate concentrations suggest that animal manure is a significant source of nitrate to the San Joaquin River. In contrast, the Sacramento River has lower nitrate concentrations but elevated ammonium concentrations from wastewater discharge. Downstream nitrification of the ammonium can be clearly traced using δ15N-NH4. Flow conditions for these rivers and the Delta have strong seasonal and inter-annual variations, resulting in significant changes in nutrient delivery and cycling. Isotopic measurements and estimates of source water contributions

  4. 30 CFR 817.57 - Hydrologic balance: Surface activities in or adjacent to perennial or intermittent streams.

    Science.gov (United States)

    2010-07-01

    ... PERMANENT PROGRAM PERFORMANCE STANDARDS-UNDERGROUND MINING ACTIVITIES § 817.57 Hydrologic balance: Surface... by roads, railroads, conveyors, pipelines, utilities, or similar facilities. You must comply with all...

  5. Climate and surface water hydrology baseline data for Aurora Mine EIA

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-12-31

    A climate and hydrology database was assembled to describe the existing climatic and surface water hydrological characteristics of the proposed Aurora Mine area in Leases 10, 12, 13, 31, and 34 east of the Athabasca River near Fort McKay. The study was based upon data available from the regional hydrometeorological monitoring network operated by the Governments of Canada and Alberta. The study also included the installation and monitoring of one climate station and five streamflow gauging stations on small watersheds in the area. The representative climatic and hydrologic characteristics of the area, including precipitation, evaporation, evapotranspiration, temperature and wind, were determined. Streamflow characteristics such as flood frequencies, low flow frequencies, water yield and flow durations representative of large gauged watersheds within the study area were also determined. The results offer a good basis for preliminary design of surface water management systems. It was recommended that the monitoring program should be continued to monitor potential environmental impacts of proposed development activities. 9 refs., 29 tabs., 32 figs.

  6. Aspects of studies on carbon cycle at ground surface

    International Nuclear Information System (INIS)

    Yamazawa, Hiromi; Kawai, Shintaro; Moriizumi, Jun; Iida, Takao

    2008-01-01

    Radiocarbon released from nuclear facilities into the atmosphere is readily involved in a ground surface carbon cycle, which has very large spatial and temporal variability. Most of the recent studies on the carbon cycle at the ground surface are concerned with global warming, to which the ground surface plays a crucial role as a sink and/or source of atmospheric carbon dioxide. In these studies, carbon isotopes are used as tracers to quantitatively evaluate behavior of carbon. From a view point of environmental safety of nuclear facilities, radiocarbon released from a facility should be traced in a specific spatial and temporal situation because carbon cycle is driven by biological activities which are spatially and temporally heterogeneous. With this background, this paper discusses aspects of carbon cycle studies by exemplifying an experimental study on carbon cycle in a forest and a numerical study on soil organic carbon formation. The first example is a typical global warming-related observational study in which radiocarbon is used as a tracer to illustrate how carbon behaves in diurnal to seasonal time scales. The second example is on behavior of bomb carbon incorporated in soil organic matter in a long-term period of decades. The discussion will cover conceptual modelling of carbon cycle from different aspects and importance of specifying time scales of interest. (author)

  7. Timeslice experiments for understanding regional climate projections: applications to the tropical hydrological cycle and European winter circulation

    Science.gov (United States)

    Chadwick, Robin; Douville, Hervé; Skinner, Christopher B.

    2017-11-01

    A set of atmosphere-only timeslice experiments are described, designed to examine the processes that cause regional climate change and inter-model uncertainty in coupled climate model responses to CO_2 forcing. The timeslice experiments are able to reproduce the pattern of regional climate change in the coupled models, and are applied here to two cases where inter-model uncertainty in future projections is large: the tropical hydrological cycle, and European winter circulation. In tropical forest regions, the plant physiological effect is the largest cause of hydrological cycle change in the two models that represent this process. This suggests that the CMIP5 ensemble mean may be underestimating the magnitude of water cycle change in these regions, due to the inclusion of models without the plant effect. SST pattern change is the dominant cause of precipitation and circulation change over the tropical oceans, and also appears to contribute to inter-model uncertainty in precipitation change over tropical land regions. Over Europe and the North Atlantic, uniform SST increases drive a poleward shift of the storm-track. However this does not consistently translate into an overall polewards storm-track shift, due to large circulation responses to SST pattern change, which varies across the models. Coupled model SST biases influence regional rainfall projections in regions such as the Maritime Continent, and so projections in these regions should be treated with caution.

  8. Evaluation of the hydrological cycle of MATCH driven by NCEP reanalysis data: comparison with GOME water vapor measurements

    Directory of Open Access Journals (Sweden)

    R. Lang

    2005-01-01

    Full Text Available This study examines two key parameters of the hydrological cycle, water vapor (WV and precipitation rates (PR, as modelled by the chemistry transport model MATCH (Model of Atmospheric Transport and Chemistry driven by National Centers for Environmental Prediction (NCEP reanalysis data (NRA. For model output evaluation we primarily employ WV total column data from the Global Ozone Monitoring Experiment (GOME on ERS-2, which is the only instrument capable measuring WV on a global scale and over all surface types with a substantial data record from 1995 to the present. We find that MATCH and NRA WV and PR distributions are closely related, but that significant regional differences in both parameters exist in magnitude and distribution patterns when compared to the observations. We also find that WV residual patterns between model and observations show remarkable similarities to residuals observed in the PR when comparing MATCH and NRA output to observations comprised by the Global Precipitation Climatology Project (GPCP. We conclude that deficiencies in model parameters shared by MATCH and NRA, like in the surface evaporation rates and regional transport patterns, are likely to lead to the observed differences. Monthly average regional differences between MATCH modelled WV columns and the observations can be as large as 2 cm, based on the analysis of three years. Differences in the global mean WV values are, however, below 0.1 cm. Regional differences in the PR between MATCH and GPCP can be above 0.5 cm per day and MATCH computes on average a higher PR than what has been observed. The lower water vapor content of MATCH is related to shorter model WV residence times by up to 1 day as compared to the observations. We find that MATCH has problems in modelling the WV content in regions of strong upward convection like, for example, along the Inter Tropical Convergence Zone, where it appears to be generally too dry as compared to the observations. We

  9. Differential response of carbon cycling to long-term nutrient input and altered hydrological conditions in a continental Canadian peatland

    Science.gov (United States)

    Berger, Sina; Praetzel, Leandra S. E.; Goebel, Marie; Blodau, Christian; Knorr, Klaus-Holger

    2018-02-01

    Peatlands play an important role in global carbon cycling, but their responses to long-term anthropogenically changed hydrologic conditions and nutrient infiltration are not well known. While experimental manipulation studies, e.g., fertilization or water table manipulations, exist on the plot scale, only few studies have addressed such factors under in situ conditions. Therefore, an ecological gradient from the center to the periphery of a continental Canadian peatland bordering a eutrophic water reservoir, as reflected by increasing nutrient input, enhanced water level fluctuations, and increasing coverage of vascular plants, was used for a case study of carbon cycling along a sequence of four differently altered sites. We monitored carbon dioxide (CO2) and methane (CH4) surface fluxes and dissolved inorganic carbon (DIC) and CH4 concentrations in peat profiles from April 2014 through September 2015. Moreover, we studied bulk peat and pore-water quality and we applied δ13C-CH4 and δ13C-CO2 stable isotope abundance analyses to examine dominant CH4 production and emission pathways during the growing season of 2015. We observed differential responses of carbon cycling at the four sites, presumably driven by abundances of plant functional types and vicinity to the reservoir. A shrub-dominated site in close vicinity to the reservoir was a comparably weak sink for CO2 (in 1.5 years: -1093 ± 794, in 1 year: +135 ± 281 g CO2 m-2; a net release) as compared to two graminoid-moss-dominated sites and a moss-dominated site (in 1.5 years: -1552 to -2260 g CO2 m-2, in 1 year: -896 to -1282 g CO2 m-2). Also, the shrub-dominated site featured notably low DIC pore-water concentrations and comparably 13C-enriched CH4 (δ13C- CH4: -57.81 ± 7.03 ‰) and depleted CO2 (δ13C-CO2: -15.85 ± 3.61 ‰) in a more decomposed peat, suggesting a higher share of CH4 oxidation and differences in predominant methanogenic pathways. In comparison to all other sites, the graminoid

  10. Eco-hydrological process simulations within an integrated surface water-groundwater model

    DEFF Research Database (Denmark)

    Butts, Michael; Loinaz, Maria Christina; Bauer-Gottwein, Peter

    2014-01-01

    Integrated water resources management requires tools that can quantify changes in groundwater, surface water, water quality and ecosystem health, as a result of changes in catchment management. To address these requirements we have developed an integrated eco-hydrological modelling framework...... that allows hydrologists and ecologists to represent the complex and dynamic interactions occurring between surface water, ground water, water quality and freshwater ecosystems within a catchment. We demonstrate here the practical application of this tool to two case studies where the interaction of surface...... water and ground water are important for the ecosystem. In the first, simulations are performed to understand the importance of surface water-groundwater interactions for a restored riparian wetland on the Odense River in Denmark as part of a larger investigation of water quality and nitrate retention...

  11. Climate change impacts on freshwater wetland hydrology and vegetation cover cycling along a regional aridity gradient

    Science.gov (United States)

    Global mean temperature may increase up to 6°C by the end of this century and together with precipitation change may steepen regional aridity gradients, impacting the hydrology, productivity, diversity, and ecosystem goods and services from freshwater wetlands, where the water balance is tightly cou...

  12. Primer: Using Watershed Modeling System (WMS) for Gridded Surface Subsurface Hydrologic Analysis (GSSHA) Data Development - WMS 6.1 and GSSHA 1.43C

    National Research Council Canada - National Science Library

    Downer, Charles

    2003-01-01

    This document is a primer for use of the Watershed Modeling System (WMS) interface with the physically based, distributed-parameter hydrologic model Gridded Surface Subsurface Hydrologic Analysis (GSSHA...

  13. Description of surface hydrology and near-surface hydrogeology at Forsmark. Site descriptive modelling SDM. Site Forsmark

    International Nuclear Information System (INIS)

    Johansson, Per-Olof

    2008-12-01

    This report describes the modelling of the surface hydrology and near-surface hydrogeology that was performed for the final site descriptive model of Forsmark produced in the site investigation stage, SDM-Site Forsmark. The comprehensive investigation and monitoring programme forms a strong basis for the developed conceptual and descriptive model of the hydrological and near-surface hydrological system of the site investigation area. However, there are some remaining uncertainties regarding the interaction of deep and near-surface groundwater and surface water of importance for the understanding of the system: The groundwaters in till below Lake Eckarfjaerden, Lake Gaellbotraesket, Lake Fiskarfjaerden and Lake Bolundsfjaerden have high salinities. The hydrological and hydrochemical interpretations indicate that these waters are relict waters of mainly marine origin. From the perspective of the overall water balance, the water below the central parts of the lakes can be considered as stagnant. However, according to the hydrochemical interpretation, these waters also contain weak signatures of deep saline water. Rough chloride budget calculations for the Gaellbotraesket depression also raise the question of a possible upward flow of deep groundwater. No absolute conclusion can be drawn from the existing data analyses regarding the key question of whether there is a small ongoing upward flow of deep saline water. However, Lake Bolundsfjaerden is an exception where the clear downward flow gradient from the till to the bedrock excludes the possibility of an active deep saline source. The available data indicate that there are no discharge areas for flow systems involving deep bedrock groundwater in the northern part of the tectonic lens, where the repository is planned to be located (the so-called 'target area'). However, it can not be excluded that such discharge areas exist. Data indicate that the prevailing downward vertical flow gradients from the QD to the bedrock

  14. Description of surface hydrology and near-surface hydrogeology at Forsmark. Site descriptive modelling SDM. Site Forsmark

    Energy Technology Data Exchange (ETDEWEB)

    Johansson, Per-Olof (Artesia Grundvattenkonsult AB, Taeby (Sweden))

    2008-12-15

    This report describes the modelling of the surface hydrology and near-surface hydrogeology that was performed for the final site descriptive model of Forsmark produced in the site investigation stage, SDM-Site Forsmark. The comprehensive investigation and monitoring programme forms a strong basis for the developed conceptual and descriptive model of the hydrological and near-surface hydrological system of the site investigation area. However, there are some remaining uncertainties regarding the interaction of deep and near-surface groundwater and surface water of importance for the understanding of the system: The groundwaters in till below Lake Eckarfjaerden, Lake Gaellbotraesket, Lake Fiskarfjaerden and Lake Bolundsfjaerden have high salinities. The hydrological and hydrochemical interpretations indicate that these waters are relict waters of mainly marine origin. From the perspective of the overall water balance, the water below the central parts of the lakes can be considered as stagnant. However, according to the hydrochemical interpretation, these waters also contain weak signatures of deep saline water. Rough chloride budget calculations for the Gaellbotraesket depression also raise the question of a possible upward flow of deep groundwater. No absolute conclusion can be drawn from the existing data analyses regarding the key question of whether there is a small ongoing upward flow of deep saline water. However, Lake Bolundsfjaerden is an exception where the clear downward flow gradient from the till to the bedrock excludes the possibility of an active deep saline source. The available data indicate that there are no discharge areas for flow systems involving deep bedrock groundwater in the northern part of the tectonic lens, where the repository is planned to be located (the so-called 'target area'). However, it can not be excluded that such discharge areas exist. Data indicate that the prevailing downward vertical flow gradients from the QD to

  15. Leveraging this Golden Age of Remote Sensing and Modeling of Terrestrial Hydrology to Understand Water Cycling in the Water Availability Grand Challenge for North America

    Science.gov (United States)

    Painter, T. H.; Famiglietti, J. S.; Stephens, G. L.

    2016-12-01

    We live in a time of increasing strains on our global fresh water availability due to increasing population, warming climate, changes in precipitation, and extensive depletion of groundwater supplies. At the same time, we have seen enormous growth in capabilities to remotely sense the regional to global water cycle and model complex systems with physically based frameworks. The GEWEX Water Availability Grand Challenge for North America is poised to leverage this convergence of remote sensing and modeling capabilities to answer fundamental questions on the water cycle. In particular, we envision an experiment that targets the complex and resource-critical Western US from California to just into the Great Plains, constraining physically-based hydrologic modeling with the US and international remote sensing capabilities. In particular, the last decade has seen the implementation or soon-to-be launch of water cycle missions such as GRACE and GRACE-FO for groundwater, SMAP for soil moisture, GPM for precipitation, SWOT for terrestrial surface water, and the Airborne Snow Observatory for snowpack. With the advent of convection-resolving mesoscale climate and water cycle modeling (e.g. WRF, WRF-Hydro) and mesoscale models capable of quantitative assimilation of remotely sensed data (e.g. the JPL Western States Water Mission), we can now begin to test hypotheses on the nature and changes in the water cycle of the Western US from a physical standpoint. In turn, by fusing water cycle science, water management, and ecosystem management while addressing these hypotheses, this golden age of remote sensing and modeling can bring all fields into a markedly less uncertain state of present knowledge and decadal scale forecasts.

  16. Geochemical, hydrological and biological cycling of energy residuals. Research plan: subsurface transport program

    International Nuclear Information System (INIS)

    Wobber, F.J.

    1985-09-01

    Because natural processes associated with the release and the transport of organic compounds, trace metals, and radionuclides are incompletely understood, research in this area is critical if the long term scientific uncertainties about contaminant transport are to be resolved. The processes that control mobilization and attenuation of energy residuals in soils and geological strata, their hydrological transport to and within ground water regimes, and their accumulation in biological systems require research attention. A summary of DOE's core research program is described. It is designed to provide a base of fundamental scientific information so that the geochemical hydrological, and biophysical mechanics that contribute to the transport and long term fate of energy related contaminants in natural systems can be understood

  17. Stable isotope hydrology. Deuterium and oxygen-18 in the water cycle

    International Nuclear Information System (INIS)

    Gat, J.R.; Gonfiantini, R.

    1981-01-01

    This monograph is mainly intended for hydrologists, hydrogeologists and geochemists who want to become acquainted, rapidly but in some detail, with the theoretical background of stable isotope fractionation in natural physico-chemical processes involving fresh water, with the isotopic differences actually encountered in natural waters and with their use for practical hydrological purposes. Throughout the monograph, and in particular in the last chapter, a series of examples are discussed, giving the results obtained with stable isotope techniques in current hydrological and hydrogeological investigations or, more generally, in water resources exploration and assessment. One chapter is also dedicated to the techniques for measuring D/H and 18 O/ 16 O ratios in water

  18. Biological soil crust and disturbance controls on surface hydrology in a semi-arid ecosystem

    Science.gov (United States)

    Faist, Akasha M; Herrick, Jeffrey E.; Belnap, Jayne; Van Zee, Justin W; Barger, Nichole N

    2017-01-01

    Biological soil crust communities (biocrusts) play an important role in surface hydrologic processes in dryland ecosystems, and these processes may then be dramatically altered with soil surface disturbance. In this study, we examined biocrust hydrologic responses to disturbance at different developmental stages on sandy soils on the Colorado Plateau. Our results showed that all disturbance (trampling, scalping and trampling+scalping) of the early successional light cyanobacterial biocrusts generally reduced runoff. In contrast, trampling well-developed dark-cyano-lichen biocrusts increased runoff and sediment loss relative to intact controls. Scalping did not increase runoff, implying that soil aggregate structure was important to the infiltration process. Well-developed, intact dark biocrusts generally had lower runoff, low sediment loss, and highest aggregate stability whereas the less-developed light biocrusts were highest in runoff and sediment loss when compared to the controls. These results suggest the importance of maintaining the well-developed dark biocrusts, as they are beneficial for lowering runoff and reducing soil loss and redistribution on the landscape. These data also suggest that upslope patches of light biocrust may either support water transport to downslope vegetation patches or alternatively this runoff may place dark biocrust patches at risk of disruption and loss, given that light patches increase runoff and thus soil erosion potential.

  19. The development of a surface hydrology model for use in radiological safety assessments

    International Nuclear Information System (INIS)

    Little, R.H.; Ashton, J.

    1991-01-01

    A detailed understanding and quantification of geosphere and biosphere water movements is vital when assessing the impact of a radioactive waste repository. Not only is water important in the transport of radionuclides from the repository into the geosphere and hence into the biosphere, but it is also important in the transport of radionuclides within the biosphere and their transport to humans. Although geosphere water fluxes have traditionally been rigorously quantified, the quantification of biosphere water fluxes has been far less rigorous. In order to redress the balance, Associated Nuclear Services Ltd (ANS) have proposed to develop a surface hydrology model for use within radiological assessments undertaken by Her Majesty's Inspectorate of Pollution (HMIP) of the United Kingdom Department of the Environment (UKDoE). It is proposed that the deterministic, lumped, quasi-physical/semi-empirical approach of conceptual models should be adopted for the model. The model will be sufficiently flexible to be applicable to a wide range of catchments, as well as a variety of temporal and spatial scales. It is envisaged that the model will have a variety of uses within the HMIP assessment methodology including the identification of significant surface hydrological processes, the provision of input data for assessment codes and the study of the biosphere-geosphere interface. (17 refs., 4 figs.)

  20. Optimization in the nuclear fuel cycle II: Surface contamination

    International Nuclear Information System (INIS)

    Pereira, W.S.; Silva, A.X.; Lopes, J.M.; Carmo, A.S.; Fernandes, T.S.; Mello, C.R.; Kelecom, A.

    2017-01-01

    Optimization is one of the bases of radioprotection and aims to move doses away from the dose limit that is the borderline of acceptable radiological risk. This work aims to use the monitoring of surface contamination as a tool of the optimization process. 53 surface contamination points were analyzed at a nuclear fuel cycle facility. Three sampling points were identified with monthly mean values of contamination higher than 1 Bq ∙ cm -2 , points 28, 42 and 47. These points were indicated for the beginning of the optimization process

  1. Few-cycle surface plasmon enhanced electron acceleration

    International Nuclear Information System (INIS)

    Racz, P.; Lenner, M.; Kroo, N.; Farkas, Gy.; Dombi, P.; Takao Fuji; Krausz, F.; Irvine, S.E.; Elezzabi, A.Y.

    2010-01-01

    Complete text of publication follows. It is possible to generate high-quality ultrafast electron beams with keV energy based on surface plasmon-enhanced electron acceleration. The beam generated this way can be also used to investigate ultrafast phenomena in the plasmon field. For the better understanding of the temporal behavior of these ultrafast surface processes we carried out time-resolved experiments with 5.5 fs laser pulses for the first time. In this experiment, we executed an autocorrelation measurement with an ultra-broadband interferometer. By generating surface plasmons at the output of the interferometer, we measured the plasmonic photocurrent as a function of the delay between the interferometer arms. Figure (a) shows a typical measured result, and figure (b) shows the fourth order calculated autocorrelation function of the 5.5 fs long laser pulse, corresponding to the fourth order nonlinearity of the electron emission process. According to the correspondence of these two curves, we can also state that the length of the generated surface plasmon pulse is only 2-3 optical cycles. As a further experiment, we executed spectrally resolved measurements of the electron beam at higher intensities. According to these results, it is possible to reach electron beams with keV energy in the few-cycle regime too. It was found that the field strength of the surface plasmons is x 7 to x 30 higher than that of the focused laser pulse.

  2. Surface Hydrological Processes of Rock Glaciated Basins in the San Juan Mountains, Colorado

    Science.gov (United States)

    Mateo, E. I.

    2017-12-01

    Glaciers in the western United States have been examined in terms of their summer meltwater contributions to regional hydrological systems. In the San Juan Mountains of Colorado where glaciers do not and cannot exist due to a rising zero-degree isotherm, rock glaciers take the place of valley glaciers during the summer runoff period. Most of the rock glaciers in Colorado are located on a northerly slope aspect, however, there are multiple in the southwest region of the state that occur on different aspects. This study asked how slope aspect and rising air temperatures influenced the hydrological processes of streams below rock glaciers in the San Juan Mountains during the 2016 summer season. This project focused on three basins, Yankee Boy basin, Blue Lakes basin, and Mill Creek basin, which are adjacent to each other and share a common peak, Gilpin Peak. Findings of this one-season study showed that air temperature significantly influenced stream discharge below each rock glacier. Discharge and air temperature patterns indicate a possible air temperature threshold during late summer when rock glacier melt increased at a greater rate. The results also suggest that slope aspect of rock glacier basins influences stream discharge, but temperature and precipitation are likely larger components of the melt regimes. The continuation of data collection during the 2017 summer season has allowed for more detailed analysis of the relationship between air temperature and rock glacier melt. This continual expansion of the original dataset is crucial for understanding the hydrological processes of surface runoff below rock glaciers.

  3. Constraining the JULES land-surface model for different land-use types using citizen-science generated hydrological data

    Science.gov (United States)

    Chou, H. K.; Ochoa-Tocachi, B. F.; Buytaert, W.

    2017-12-01

    Community land surface models such as JULES are increasingly used for hydrological assessment because of their state-of-the-art representation of land-surface processes. However, a major weakness of JULES and other land surface models is the limited number of land surface parameterizations that is available. Therefore, this study explores the use of data from a network of catchments under homogeneous land-use to generate parameter "libraries" to extent the land surface parameterizations of JULES. The network (called iMHEA) is part of a grassroots initiative to characterise the hydrological response of different Andean ecosystems, and collects data on streamflow, precipitation, and several weather variables at a high temporal resolution. The tropical Andes are a useful case study because of the complexity of meteorological and geographical conditions combined with extremely heterogeneous land-use that result in a wide range of hydrological responses. We then calibrated JULES for each land-use represented in the iMHEA dataset. For the individual land-use types, the results show improved simulations of streamflow when using the calibrated parameters with respect to default values. In particular, the partitioning between surface and subsurface flows can be improved. But also, on a regional scale, hydrological modelling was greatly benefitted from constraining parameters using such distributed citizen-science generated streamflow data. This study demonstrates the modelling and prediction on regional hydrology by integrating citizen science and land surface model. In the context of hydrological study, the limitation of data scarcity could be solved indeed by using this framework. Improved predictions of such impacts could be leveraged by catchment managers to guide watershed interventions, to evaluate their effectiveness, and to minimize risks.

  4. Nuclear techniques in hydrology

    International Nuclear Information System (INIS)

    Bahadur, J.; Saxena, R.K.

    1974-01-01

    Several types of sealed radioactive sources, stable isotopes and water soluble radioactive tracers, used by different investigators, have been listed for studying the dynamic behaviour of water in nature. In general, all the facets of hydrological cycle, are amenable to these isotopic techniques. It is recommended that environmental isotopes data collection should be started for studying the water balance and also the interrelationships between surface and subsurface water in various rivers catchments with changing physical, geological and climatic parameters. (author)

  5. Hydrodynamic modeling of hydrologic surface connectivity within a coastal river-floodplain system

    Science.gov (United States)

    Castillo, C. R.; Guneralp, I.

    2017-12-01

    Hydrologic surface connectivity (HSC) within river-floodplain environments is a useful indicator of the overall health of riparian habitats because it allows connections amongst components/landforms of the riverine landscape system to be quantified. Overbank flows have traditionally been the focus for analyses concerned with river-floodplain connectivity, but recent works have identified the large significance from sub-bankfull streamflows. Through the use of morphometric analysis and a digital elevation model that is relative to the river water surface, we previously determined that >50% of the floodplain for Mission River on the Coastal Bend of Texas becomes connected to the river at streamflows well-below bankfull conditions. Guided by streamflow records, field-based inundation data, and morphometric analysis; we develop a two-dimensional hydrodynamic model for lower portions of Mission River Floodplain system. This model not only allows us to analyze connections induced by surface water inundation, but also other aspects of the hydrologic connectivity concept such as exchanges of sediment and energy between the river and its floodplain. We also aggregate hydrodynamic model outputs to an object/landform level in order to analyze HSC and associated attributes using measures from graph/network theory. Combining physically-based hydrodynamic models with object-based and graph theoretical analyses allow river-floodplain connectivity to be quantified in a consistent manner with measures/indicators commonly used in landscape analysis. Analyzes similar to ours build towards the establishment of a formal framework for analyzing river-floodplain interaction that will ultimately serve to inform the management of riverine/floodplain environments.

  6. Inverse modeling of hydrologic parameters using surface flux and runoff observations in the Community Land Model

    Science.gov (United States)

    Sun, Y.; Hou, Z.; Huang, M.; Tian, F.; Leung, L. Ruby

    2013-12-01

    This study demonstrates the possibility of inverting hydrologic parameters using surface flux and runoff observations in version 4 of the Community Land Model (CLM4). Previous studies showed that surface flux and runoff calculations are sensitive to major hydrologic parameters in CLM4 over different watersheds, and illustrated the necessity and possibility of parameter calibration. Both deterministic least-square fitting and stochastic Markov-chain Monte Carlo (MCMC)-Bayesian inversion approaches are evaluated by applying them to CLM4 at selected sites with different climate and soil conditions. The unknowns to be estimated include surface and subsurface runoff generation parameters and vadose zone soil water parameters. We find that using model parameters calibrated by the sampling-based stochastic inversion approaches provides significant improvements in the model simulations compared to using default CLM4 parameter values, and that as more information comes in, the predictive intervals (ranges of posterior distributions) of the calibrated parameters become narrower. In general, parameters that are identified to be significant through sensitivity analyses and statistical tests are better calibrated than those with weak or nonlinear impacts on flux or runoff observations. Temporal resolution of observations has larger impacts on the results of inverse modeling using heat flux data than runoff data. Soil and vegetation cover have important impacts on parameter sensitivities, leading to different patterns of posterior distributions of parameters at different sites. Overall, the MCMC-Bayesian inversion approach effectively and reliably improves the simulation of CLM under different climates and environmental conditions. Bayesian model averaging of the posterior estimates with different reference acceptance probabilities can smooth the posterior distribution and provide more reliable parameter estimates, but at the expense of wider uncertainty bounds.

  7. Hydrology and geochemistry of a surface coal mine in northwestern Colorado

    Science.gov (United States)

    Williams, R.S.; Clark, G.M.

    1994-01-01

    The hydrology and geochemistry of a reclaimed coal mine in northwestern Colorado were monitored during water years 1988 and 1989. Some data also were collected in water years 1987 and 1990. This report describes (1) the sources of hydrologic recharge to and discharge from reclaimed spoil, (2) the relative contributions of recharge to the reclaimed spoil aquifer from identified source waters and the rate of water movement from those sources to the reclaimed spoil, and (3) the geochemical reactions that control water quality in reclaimed spoil. The study area was at a dip-slope coal mine encompassing about 7 square miles with land slopes of varying aspect. The area was instrumented and monitored at five sites; two sites had unmined and reclaimed- spoil areas adjacent to each other and three sites were unmined. The mined areas had been reclaimed. Instrumentation at the study sites included 1 climate station, 3 rain gages, 19 soil-water access tubes, 2 lysimeters, 18 wells completed in bedrock, 7 wells completed in reclaimed spoil, and 2 surface- water gaging stations. The results of the study indicate that the reclaimed spoil is recharged from surface recharge and underburden aquifers. Discharge, as measured by lysimeters, was about 3 inches per year and occurred during and after snowmelt. Hydraulic-head measurements indicated a potential for ground-water movement from deeper to shallower aquifers. Water levels rose in the reclaimed-spoil aquifer and spring discharge at the toe of the spoil slopes increased rapidly in response to snowmelt. Water chemistry, stable isotopes, geochemical models, and mass-balance calculations indicate that surface recharge and the underburden aquifers each contribute about 50 percent of the water to the reclaimed-spoil aquifers. Geochemical information indicates that pyrite oxidation and dissolution of carbonate and efflorescent sulfate minerals control the water chemistry of the reclaimed-spoil aquifer.

  8. Improving student comprehension of the interconnectivity of the hydrologic cycle with a novel 'hydrology toolbox', integrated watershed model, and companion textbook

    Science.gov (United States)

    Huning, L. S.; Margulis, S. A.

    2013-12-01

    Concepts in introductory hydrology courses are often taught in the context of process-based modeling that ultimately is integrated into a watershed model. In an effort to reduce the learning curve associated with applying hydrologic concepts to real-world applications, we developed and incorporated a 'hydrology toolbox' that complements a new, companion textbook into introductory undergraduate hydrology courses. The hydrology toolbox contains the basic building blocks (functions coded in MATLAB) for an integrated spatially-distributed watershed model that makes hydrologic topics (e.g. precipitation, snow, radiation, evaporation, unsaturated flow, infiltration, groundwater, and runoff) more user-friendly and accessible for students. The toolbox functions can be used in a modular format so that students can study individual hydrologic processes and become familiar with the hydrology toolbox. This approach allows such courses to emphasize understanding and application of hydrologic concepts rather than computer coding or programming. While topics in introductory hydrology courses are often introduced and taught independently or semi-independently, they are inherently interconnected. These toolbox functions are therefore linked together at the end of the course to reinforce a holistic understanding of how these hydrologic processes are measured, interconnected, and modeled. They are integrated into a spatially-distributed watershed model or numerical laboratory where students can explore a range of topics such as rainfall-runoff modeling, urbanization, deforestation, watershed response to changes in parameters or forcings, etc. Model output can readily be visualized and analyzed by students to understand watershed response in a real river basin or a simple 'toy' basin. These tools complement the textbook, each of which has been well received by students in multiple hydrology courses with various disciplinary backgrounds. The same governing equations that students have

  9. Development and Application of Improved Long-Term Datasets of Surface Hydrology for Texas

    Directory of Open Access Journals (Sweden)

    Kyungtae Lee

    2017-01-01

    Full Text Available Freshwater availability and agricultural production are key factors for sustaining the fast growing population and economy in the state of Texas, which is the third largest state in terms of agricultural production in the United States. This paper describes a long-term (1918–2011 grid-based (1/8° surface hydrological dataset for Texas at a daily time step based on simulations from the Variable Infiltration Capacity (VIC hydrological model. The model was calibrated and validated against observed streamflow over 10 Texas river basins. The simulated soil moisture was also evaluated using in situ observations. Results suggest that there is a decreasing trend in precipitation and an increasing trend in temperature in most of the basins. Droughts and floods were reconstructed and analyzed. In particular, the spatially distributed severity and duration of major Texas droughts were compared to identify new characteristics. The modeled flood recurrence interval and the return period were also compared with observations. Results suggest the performance of extreme flood simulations needs further improvement. This dataset is expected to serve as a benchmark which may contribute to water resources management and to mitigating agricultural drought, especially in the context of understanding the effects of climate change on crop yield in Texas.

  10. Predictive occurrence models for coastal wetland plant communities: delineating hydrologic response surfaces with multinomial logistic regression

    Science.gov (United States)

    Snedden, Gregg A.; Steyer, Gregory D.

    2013-01-01

    Understanding plant community zonation along estuarine stress gradients is critical for effective conservation and restoration of coastal wetland ecosystems. We related the presence of plant community types to estuarine hydrology at 173 sites across coastal Louisiana. Percent relative cover by species was assessed at each site near the end of the growing season in 2008, and hourly water level and salinity were recorded at each site Oct 2007–Sep 2008. Nine plant community types were delineated with k-means clustering, and indicator species were identified for each of the community types with indicator species analysis. An inverse relation between salinity and species diversity was observed. Canonical correspondence analysis (CCA) effectively segregated the sites across ordination space by community type, and indicated that salinity and tidal amplitude were both important drivers of vegetation composition. Multinomial logistic regression (MLR) and Akaike's Information Criterion (AIC) were used to predict the probability of occurrence of the nine vegetation communities as a function of salinity and tidal amplitude, and probability surfaces obtained from the MLR model corroborated the CCA results. The weighted kappa statistic, calculated from the confusion matrix of predicted versus actual community types, was 0.7 and indicated good agreement between observed community types and model predictions. Our results suggest that models based on a few key hydrologic variables can be valuable tools for predicting vegetation community development when restoring and managing coastal wetlands.

  11. Predictive occurrence models for coastal wetland plant communities: Delineating hydrologic response surfaces with multinomial logistic regression

    Science.gov (United States)

    Snedden, Gregg A.; Steyer, Gregory D.

    2013-02-01

    Understanding plant community zonation along estuarine stress gradients is critical for effective conservation and restoration of coastal wetland ecosystems. We related the presence of plant community types to estuarine hydrology at 173 sites across coastal Louisiana. Percent relative cover by species was assessed at each site near the end of the growing season in 2008, and hourly water level and salinity were recorded at each site Oct 2007-Sep 2008. Nine plant community types were delineated with k-means clustering, and indicator species were identified for each of the community types with indicator species analysis. An inverse relation between salinity and species diversity was observed. Canonical correspondence analysis (CCA) effectively segregated the sites across ordination space by community type, and indicated that salinity and tidal amplitude were both important drivers of vegetation composition. Multinomial logistic regression (MLR) and Akaike's Information Criterion (AIC) were used to predict the probability of occurrence of the nine vegetation communities as a function of salinity and tidal amplitude, and probability surfaces obtained from the MLR model corroborated the CCA results. The weighted kappa statistic, calculated from the confusion matrix of predicted versus actual community types, was 0.7 and indicated good agreement between observed community types and model predictions. Our results suggest that models based on a few key hydrologic variables can be valuable tools for predicting vegetation community development when restoring and managing coastal wetlands.

  12. Identifying and Evaluating the Relationships that Control a Land Surface Model's Hydrological Behavior

    Science.gov (United States)

    Koster, Randal D.; Mahanama, Sarith P.

    2012-01-01

    The inherent soil moisture-evaporation relationships used in today 's land surface models (LSMs) arguably reflect a lot of guesswork given the lack of contemporaneous evaporation and soil moisture observations at the spatial scales represented by regional and global models. The inherent soil moisture-runoff relationships used in the LSMs are also of uncertain accuracy. Evaluating these relationships is difficult but crucial given that they have a major impact on how the land component contributes to hydrological and meteorological variability within the climate system. The relationships, it turns out, can be examined efficiently and effectively with a simple water balance model framework. The simple water balance model, driven with multi-decadal observations covering the conterminous United States, shows how different prescribed relationships lead to different manifestations of hydrological variability, some of which can be compared directly to observations. Through the testing of a wide suite of relationships, the simple model provides estimates for the underlying relationships that operate in nature and that should be operating in LSMs. We examine the relationships currently used in a number of different LSMs in the context of the simple water balance model results and make recommendations for potential first-order improvements to these LSMs.

  13. CO2 and the hydrologic cycle: Simulation of two Texas river basins

    International Nuclear Information System (INIS)

    King, K.W.; Srinivasan, R.; Arnold, J.G.; Williams, J.R.

    1994-01-01

    Increasing concentrations of CO 2 , in the atmosphere have been speculated to have a major effect on water supplies as well as other ecological characteristics. SWAT (Soil Water Assessment Tool) is a river basin scale hydrologic model that was modified to simulate the impact of CO 2 concentration on ET and biomass production. The model was utilized to analyze the impact of global climate change on two contrasting Texas basins. Climatic changes included doubling of CO 2 concentration from 330 ppm to 660 ppm and varying temperatures 0, ±2, and ±4 C from present values. Potential impacts of six hydrologic parameters including ET, potential ET, water yield, water stress, soil water, and biomass were simulated. CO 2 doubling had a more pronounced effect than did temperature variances. When temperature alone was varied, water yield at the outlet of the basins ranged from -4.4% to 6.5% for basin 1202 and from 2.9% to 26.7% for basin 1208. But, when coupled with an elevated CO 2 concentration, water yields increased in the range of 13.1% to 24.5% for basin 1202 and 5.6% to 33.7% for basin 1208. Rising CO 2 levels reduced ET for both basins, representing an enhanced water use efficiency. Seasonal fluctuations of soil water were a result of different growing periods and are evident from water stress encountered by the plant. With enriched CO 2 levels, increases in biomass production ranged from 6.9% to 47.4% and from 14.5 % to 31.4% for basins 1202 and 1208, respectively. 42 refs., 10 figs., 2 tabs

  14. On the appropriate definition of soil profile configuration and initial conditions for land surface-hydrology models in cold regions

    Science.gov (United States)

    Sapriza-Azuri, Gonzalo; Gamazo, Pablo; Razavi, Saman; Wheater, Howard S.

    2018-06-01

    Arctic and subarctic regions are amongst the most susceptible regions on Earth to global warming and climate change. Understanding and predicting the impact of climate change in these regions require a proper process representation of the interactions between climate, carbon cycle, and hydrology in Earth system models. This study focuses on land surface models (LSMs) that represent the lower boundary condition of general circulation models (GCMs) and regional climate models (RCMs), which simulate climate change evolution at the global and regional scales, respectively. LSMs typically utilize a standard soil configuration with a depth of no more than 4 m, whereas for cold, permafrost regions, field experiments show that attention to deep soil profiles is needed to understand and close the water and energy balances, which are tightly coupled through the phase change. To address this gap, we design and run a series of model experiments with a one-dimensional LSM, called CLASS (Canadian Land Surface Scheme), as embedded in the MESH (Modélisation Environmentale Communautaire - Surface and Hydrology) modelling system, to (1) characterize the effect of soil profile depth under different climate conditions and in the presence of parameter uncertainty; (2) assess the effect of including or excluding the geothermal flux in the LSM at the bottom of the soil column; and (3) develop a methodology for temperature profile initialization in permafrost regions, where the system has an extended memory, by the use of paleo-records and bootstrapping. Our study area is in Norman Wells, Northwest Territories of Canada, where measurements of soil temperature profiles and historical reconstructed climate data are available. Our results demonstrate a dominant role for parameter uncertainty, that is often neglected in LSMs. Considering such high sensitivity to parameter values and dependency on the climate condition, we show that a minimum depth of 20 m is essential to adequately represent

  15. Hydrological assessment of atmospheric forcing uncertainty in the Euro-Mediterranean area using a land surface model

    Science.gov (United States)

    Gelati, Emiliano; Decharme, Bertrand; Calvet, Jean-Christophe; Minvielle, Marie; Polcher, Jan; Fairbairn, David; Weedon, Graham P.

    2018-04-01

    Physically consistent descriptions of land surface hydrology are crucial for planning human activities that involve freshwater resources, especially in light of the expected climate change scenarios. We assess how atmospheric forcing data uncertainties affect land surface model (LSM) simulations by means of an extensive evaluation exercise using a number of state-of-the-art remote sensing and station-based datasets. For this purpose, we use the CO2-responsive ISBA-A-gs LSM coupled with the CNRM version of the Total Runoff Integrated Pathways (CTRIP) river routing model. We perform multi-forcing simulations over the Euro-Mediterranean area (25-75.5° N, 11.5° W-62.5° E, at 0.5° resolution) from 1979 to 2012. The model is forced using four atmospheric datasets. Three of them are based on the ERA-Interim reanalysis (ERA-I). The fourth dataset is independent from ERA-Interim: PGF, developed at Princeton University. The hydrological impacts of atmospheric forcing uncertainties are assessed by comparing simulated surface soil moisture (SSM), leaf area index (LAI) and river discharge against observation-based datasets: SSM from the European Space Agency's Water Cycle Multi-mission Observation Strategy and Climate Change Initiative projects (ESA-CCI), LAI of the Global Inventory Modeling and Mapping Studies (GIMMS), and Global Runoff Data Centre (GRDC) river discharge. The atmospheric forcing data are also compared to reference datasets. Precipitation is the most uncertain forcing variable across datasets, while the most consistent are air temperature and SW and LW radiation. At the monthly timescale, SSM and LAI simulations are relatively insensitive to forcing uncertainties. Some discrepancies with ESA-CCI appear to be forcing-independent and may be due to different assumptions underlying the LSM and the remote sensing retrieval algorithm. All simulations overestimate average summer and early-autumn LAI. Forcing uncertainty impacts on simulated river discharge are

  16. Coupled Monitoring and Inverse Modeling to Investigate Surface - Subsurface Hydrological and Thermal Dynamics in the Arctic Tundra

    Science.gov (United States)

    Tran, A. P.; Dafflon, B.; Hubbard, S. S.; Bisht, G.; Peterson, J.; Ulrich, C.; Romanovsky, V. E.; Kneafsey, T. J.; Wu, Y.

    2015-12-01

    Quantitative characterization of the soil surface-subsurface hydrological and thermal processes is essential as they are primary factors that control the biogeochemical processes, ecological landscapes and greenhouse gas fluxes. In the Artic region, the surface-subsurface hydrological and thermal regimes co-interact and are both largely influenced by soil texture and soil organic content. In this study, we present a coupled inversion scheme that jointly inverts hydrological, thermal and geophysical data to estimate the vertical profiles of clay, sand and organic contents. Within this inversion scheme, the Community Land Model (CLM4.5) serves as a forward model to simulate the land-surface energy balance and subsurface hydrological-thermal processes. Soil electrical conductivity (from electrical resistivity tomography), temperature and water content are linked together via petrophysical and geophysical models. Particularly, the inversion scheme accounts for the influences of the soil organic and mineral content on both of the hydrological-thermal dynamics and the petrophysical relationship. We applied the inversion scheme to the Next Generation Ecosystem Experiments (NGEE) intensive site in Barrow, AK, which is characterized by polygonal-shaped arctic tundra. The monitoring system autonomously provides a suite of above-ground measurements (e.g., precipitation, air temperature, wind speed, short-long wave radiation, canopy greenness and eddy covariance) as well as below-ground measurements (soil moisture, soil temperature, thaw layer thickness, snow thickness and soil electrical conductivity), which complement other periodic, manually collected measurements. The preliminary results indicate that the model can well reproduce the spatiotemporal dynamics of the soil temperature, and therefore, accurately predict the active layer thickness. The hydrological and thermal dynamics are closely linked to the polygon types and polygon features. The results also enable the

  17. Radiochemical analyses of surface water from U.S. Geological Survey hydrologic bench-mark stations

    Science.gov (United States)

    Janzer, V.J.; Saindon, L.G.

    1972-01-01

    The U.S. Geological Survey's program for collecting and analyzing surface-water samples for radiochemical constituents at hydrologic bench-mark stations is described. Analytical methods used during the study are described briefly and data obtained from 55 of the network stations in the United States during the period from 1967 to 1971 are given in tabular form.Concentration values are reported for dissolved uranium, radium, gross alpha and gross beta radioactivity. Values are also given for suspended gross alpha radioactivity in terms of natural uranium. Suspended gross beta radioactivity is expressed both as the equilibrium mixture of strontium-90/yttrium-90 and as cesium-137.Other physical parameters reported which describe the samples include the concentrations of dissolved and suspended solids, the water temperature and stream discharge at the time of the sample collection.

  18. Assimilation of ASCAT near-surface soil moisture into the SIM hydrological model over France

    Science.gov (United States)

    Draper, C.; Mahfouf, J.-F.; Calvet, J.-C.; Martin, E.; Wagner, W.

    2011-12-01

    This study examines whether the assimilation of remotely sensed near-surface soil moisture observations might benefit an operational hydrological model, specifically Météo-France's SAFRAN-ISBA-MODCOU (SIM) model. Soil moisture data derived from ASCAT backscatter observations are assimilated into SIM using a Simplified Extended Kalman Filter (SEKF) over 3.5 years. The benefit of the assimilation is tested by comparison to a delayed cut-off version of SIM, in which the land surface is forced with more accurate atmospheric analyses, due to the availability of additional atmospheric observations after the near-real time data cut-off. However, comparing the near-real time and delayed cut-off SIM models revealed that the main difference between them is a dry bias in the near-real time precipitation forcing, which resulted in a dry bias in the root-zone soil moisture and associated surface moisture flux forecasts. While assimilating the ASCAT data did reduce the root-zone soil moisture dry bias (by nearly 50%), this was more likely due to a bias within the SEKF, than due to the assimilation having accurately responded to the precipitation errors. Several improvements to the assimilation are identified to address this, and a bias-aware strategy is suggested for explicitly correcting the model bias. However, in this experiment the moisture added by the SEKF was quickly lost from the model surface due to the enhanced surface fluxes (particularly drainage) induced by the wetter soil moisture states. Consequently, by the end of each winter, during which frozen conditions prevent the ASCAT data from being assimilated, the model land surface had returned to its original (dry-biased) climate. This highlights that it would be more effective to address the precipitation bias directly, than to correct it by constraining the model soil moisture through data assimilation.

  19. The Martian hydrologic cycle - Effects of CO2 mass flux on global water distribution

    Science.gov (United States)

    James, P. B.

    1985-01-01

    The Martian CO2 cycle, which includes the seasonal condensation and subsequent sublimation of up to 30 percent of the planet's atmosphere, produces meridional winds due to the consequent mass flux of CO2. These winds currently display strong seasonal and hemispheric asymmetries due to the large asymmetries in the distribution of insolation on Mars. It is proposed that asymmetric meridional advection of water vapor on the planet due to these CO2 condensation winds is capable of explaining the observed dessication of Mars' south polar region at the current time. A simple model for water vapor transport is used to verify this hypothesis and to speculate on the effects of changes in orbital parameters on the seasonal water cycle.

  20. Sedimentary evidence for enhanced hydrological cycling in response to rapid carbon release during the early Toarcian oceanic anoxic event

    Science.gov (United States)

    Izumi, Kentaro; Kemp, David B.; Itamiya, Shoma; Inui, Mutsuko

    2018-01-01

    A pronounced excursion in the carbon-isotope composition of biospheric carbon and coeval seawater warming during the early Toarcian (∼183 Ma) has been linked to the large-scale transfer of 12C-enriched carbon to the oceans and atmosphere. A European bias in the distribution of available data means that the precise pattern, tempo and global expression of this carbon cycle perturbation, and the associated environmental responses, remain uncertain. Here, we present a new cm-scale terrestrial-dominated carbon-isotope record through an expanded lower Toarcian section from Japan that displays a negative excursion pattern similar to marine and terrestrial carbon-isotope records documented from Europe. These new data suggest that 12C-enriched carbon was added to the biosphere in at least one rapid, millennial-scale pulse. Sedimentological analysis indicates a close association between the carbon-isotope excursion and high-energy sediment transport and enhanced fluvial discharge. Together, these data support the hypothesis that a sudden strengthening of the global hydrological cycle occurred in direct and immediate response to rapid carbon release and atmospheric warming.

  1. The role of water ice clouds in the Martian hydrologic cycle

    Science.gov (United States)

    James, Philip B.

    1990-01-01

    A one-dimensional model for the seasonal cycle of water on Mars has been used to investigate the direction of the net annual transport of water on the planet and to study the possible role of water ice clouds, which are included as an independent phase in addition to ground ice and water vapor, in the cycle. The calculated seasonal and spatial patterns of occurrence of water ice clouds are qualitatively similar to the observed polar hoods, suggesting that these polar clouds are, in fact, an important component of water cycle. A residual dry ice in the south acts as a cold trap which, in the absence of sources other than the caps, will ultimately attract the water ice from the north cap; however, in the presence of a source of water in northern midlatitudes during spring, it is possible that the observed distribution of vapor and ice can be in a steady state even if a residual CO2 cap is a permanent feature of the system.

  2. Titan's methane cycle and its effect on surface geology

    Science.gov (United States)

    Lopes, R. M.; Peckyno, R. S.; Le Gall, A. A.; Wye, L.; Stofan, E. R.; Radebaugh, J.; Hayes, A. G.; Aharonson, O.; Wall, S. D.; Janssen, M. A.; Cassini RADAR Team

    2010-12-01

    Titan’s surface geology reflects surface-atmospheric interaction in ways similar to Earth’s. The methane cycle on Titan is a major contributor to the formation of surface features such as lakes, seas, rivers, and dunes. We used data from Cassini RADAR to map the distribution and relative ages of terrains that allow us to determine the geological processes that have shaped Titan’s surface. These SAR swaths (up to Titan flyby T64) cover about ~45% percent of the surface, at a spatial resolution ranging from 350 m to about >2 km. The data are distributed over a wide latitudinal and longitudinal range, enabling some conclusions to be drawn about the global distribution and significance of processes. They reveal a geologically complex surface that has been modified by all the major geologic processes seen on Earth. In this paper, we update the geologic unit map that used flybys up to T30 (Lopes et al., 2010, Icarus, 205, 540-558), representing ~20% of the surface. We find that the overall correlations found previously still hold given more than double the areal coverage. In terms of global areal distribution, both dunes and mountainous terrains (including Xanadu) cover more area (respectively 9.2% and 14.6% of the observed area) than other identified geologic units. In terms of latitudinal distribution, dunes and hummocky, mountainous terrains are located mostly at low latitudes (less than 30 degrees), with no dunes being present above 60 degrees. Channels formed by fluvial activity are present at all latitudes, but lakes filled with liquid are found at high latitudes only (above 60 degrees). Impact structures are mostly located at low latitudes, with no confidently identified craters above 60 degrees latitude, possibly indicating that more resurfacing has occurred at higher latitudes. Putative cryovolcanic features, consisting mostly of flows, are not ubiquitous and are mostly located in the areas surrounding Xanadu. We examine temporal relationships between

  3. Seasonal dynamics of surface chlorophyll concentration and sea surface temperature, as indicator of hydrological structure of the ocean (by satellite data)

    Science.gov (United States)

    Shevyrnogov, Anatoly; Vysotskaya, Galina

    Continuous monitoring of phytopigment concentrations and sea surface temperature in the ocean by space-borne methods makes possible to estimate ecological condition of biocenoses in critical areas. Unlike land vegetation, hydrological processes largely determine phytoplank-ton dynamics, which may be either recurrent or random. The types of chlorophyll concentration dynamics and sea surface temperature can manifest as zones quasistationary by seasonal dynamics, quasistationary areas (QSA). In the papers of the authors (A. Shevyrnogov, G. Vysotskaya, E. Shevyrnogov, A study of the stationary and the anomalous in the ocean surface chlorophyll distribution by satellite data. International Journal of Remote Sensing, Vol. 25, No.7-8, pp. 1383-1387, April 2004 & A. P. Shevyrnogov, G. S. Vysotskaya, J. I. Gitelson, Quasistationary areas of chlorophyll concentra-tion in the world ocean as observed satellite data Advances in Space Research, Volume 18, Issue 7, Pages 129-132, 1996) existence of zones, which are quasi-stationary with similar seasonal dynamics of chlorophyll concentration at surface layer of ocean, was shown. Results were obtained on the base of processing of time series of satellite images SeaWiFS. It was shown that fronts and frontal zones coincide with dividing lines between quasi-stationary are-as, especially in areas of large oceanic streams. To study the dynamics of the ocean for the period from 1985 through 2012 we used data on the temperature of the surface layer of the ocean and chlorophyll concentration (AVHRR, SeaWiFS and MODIS). Biota of surface oceanic layer is more stable in comparison with quickly changing surface tem-perature. It gives a possibility to circumvent influence of high-frequency component (for exam-ple, a diurnal cycle) in investigation of dynamics of spatial distribution of surface streams. In addition, an analyses of nonstable ocean productivity phenomena, stood out time series of satellite images, showed existence of areas with

  4. Use of Isotopic Techniques for the Assessment of Hydrological Interaction Surface Water and Groundwater. Rio Man - Cienaga Colombia

    International Nuclear Information System (INIS)

    Palacio B, P.; Betancur V, T.; Dapena, C.

    2011-01-01

    This job integrates the first results from the studies ''Conceptual Hydrological Model for the middle and lower parts of the Man River basin using hydrological, hydrochemical and isotopic techniques'' (Palacio, 2011) and ''Hydrochemical and Isotopic techniques for the assessment of hydrological processes in the the wetlands of Bajo Cauca Antioquia'' (University of Antioquia and International Atomic Energy Agency (IAEA). The Man river basin covers an area of 688 km 2 ; with temperatures ranging from 25 to 30 o C; The average annual rainfall is 2.800 mm. The geology of the area is composed mainly of clastic sedimentary rocks of continental origin. A hydrological model of interaction between surface water and groundwater for the lower middle of the Man River basin was obtained by the use of hydrological analysis techniques. This model was refined, adjusted and validated using isotope techniques based mainly on the analysis of spatial and temporal variance of stable isotopes found in rain water, surface bodies of water such as streams and wetlands, and in an unconfined aquifer.

  5. Development and implementation of a Variable Infiltration Capacity model of surface hydrology into the General Circulation Model

    International Nuclear Information System (INIS)

    Lettenmaier, D.P.; Stamm, J.F.; Wood, E.F.

    1993-04-01

    A Variable Infiltration Capacity (VIC) model is described for the representation of land surface hydrology in General Circulation Models (GCMs). The VIC model computes runoff as a function of the distribution of soil moisture capacity within a GCM grid cell. The major distinguishing feature of the VIC model relative to the bucket model currently used to represent the land surface in many GCMs is that it parameterizes the nonlinearity of the fraction of precipitation that infiltrates over a large area (hence the production of direct runoff) as a function of spatial average soil moisture storage, and that it models subsurface runoff between storms via a simple recession mechanism. The VIC model was incorporated into the Geophysical Fluid Dynamics Laboratory (GFDL) GCM at R15 resolution (roughly 4.5 degrees latitude by 7.5 degrees longitude). Ten-year simulations of global climate were produced using the GFDL GCM with both VIC land surface hydrology, and, for comparison purposes, the standard bucket representation. Comparison of the ten year runs using the VIC model with those using bucket hydrology showed that for the VIC run, global average runoff increased, soil moisture decreased, evaporation decreased, land surface temperature increased, and precipitation decreased. As expected, changes in precipitation occurred primarily over the continents, especially in the northern hemisphere. Changes in the surface water balance for Africa, Australia, and South America were much less than for North American and Eurasia. Both VIC and bucket simulations of surface air temperature and precipitation were compared with gridded monthly average observation fields. These comparisons indicated that the VIC hydrology reproduced winter temperatures better, and summer temperatures worse, than the bucket model. The VIC hydrology better represented global precipitation, primarily as a result of partially reducing the upward bias in precipitation associated with the GFDL R15 bucket runs

  6. Changes in the Global Hydrological Cycle: Lessons from Modeling Lake Levels at the Last Glacial Maximum

    Science.gov (United States)

    Lowry, D. P.; Morrill, C.

    2011-12-01

    receives. Our results indicate that the causes of hydrologic fluctuations are spatially diverse and that future projections will need to consider more than just thermodynamic changes for accurate regional predictions.

  7. HYDROLOGIC AND FEATURE-BASED SURFACE ANALYSIS FOR TOOL MARK INVESTIGATION ON ARCHAEOLOGICAL FINDS

    Directory of Open Access Journals (Sweden)

    K. Kovács

    2012-07-01

    Full Text Available The improvement of detailed surface documentation methods provides unique tool mark-study opportunities in the field of archaeological researches. One of these data collection techniques is short-range laser scanning, which creates a digital copy of the object’s morphological characteristics from high-resolution datasets. The aim of our work was the accurate documentation of a Bronze Age sluice box from Mitterberg, Austria with a spatial resolution of 0.2 mm. Furthermore, the investigation of the entirely preserved tool marks on the surface of this archaeological find was also accomplished by these datasets. The methodology of this tool mark-study can be summarized in the following way: At first, a local hydrologic analysis has been applied to separate the various patterns of tools on the finds’ surface. As a result, the XYZ coordinates of the special points, which represent the edge lines of the sliding tool marks, were calculated by buffer operations in a GIS environment. During the second part of the workflow, these edge points were utilized to manually clip the triangle meshes of these patterns in reverse engineering software. Finally, circle features were generated and analysed to determine the different sections along these sliding tool marks. In conclusion, the movement of the hand tool could be reproduced by the spatial analysis of the created features, since the horizontal and vertical position of the defined circle centre points indicated the various phases of the movements. This research shows an exact workflow to determine the fine morphological structures on the surface of the archaeological find.

  8. Hydrological regime shift in a constructed catchment: Effect of vegetation encroachment on surface runoff

    Science.gov (United States)

    Hinz, C.; Caviedes-Voullieme, D.; Andezhath Mohanan, A.; Brueck, Y.; Zaplata, M.

    2017-12-01

    The Hühnerwasser catchment (Chicken Creek) was constructed to provide discharge for a small stream in the post-mining landscape of Lusatia, Germany. It has an area of 6 ha and quaternary sands with a thickness of 2-4 m were dumped on to a clay liner to prevent deep drainage. After completion of the construction the catchment was left to develop on its own without intervention and has been monitored since 2005. The upper part of the catchment discharges water and sediment into the lower part forming an alluvial fan. Below the alluvial fan is a pond receiving all surface and subsurface water from the upper catchment. After the formation of the drainage network vegetation started growing and surface runoff decreased until the water balance was dominated by evapotranspiration. This regime shift and the rate at which it happened depends on the vegetation encroachment into the rills and the interrill areas. Based on the hypothesis that vegetation will increase surface roughness and infiltration behavior, aerial photos were used to map rills and vegetation within and outside the rills for the last 10 years to obtain a time series of change. Observational evidence clearly shows that vegetation encroaches from the bottom, from the interrill areas as well as from the top. The rills themselves did not change their topology, however, the width of the erosion rills and gully increased at the bottom. For a subcatchment area a high resolution a physical based numerical model of overland flow was developed to explicitly assess the importance of increasing roughness and infiltration capacity for surface runoff. For the purpose of analyzing the effect of rainfall variability a rainfall generator was developed to carry out large sets of simulations. The simulations provide a means to assess how the roughness/infiltration feedback affects the rate of regime shift for a set of parameters that are consistent with the observed hydrological behavior of the drainage network.

  9. MUREX: a land-surface field experiment to study the annual cycle of the energy and water budgets

    Directory of Open Access Journals (Sweden)

    J.-C. Calvet

    1999-06-01

    Full Text Available The MUREX (monitoring the usable soil reservoir experimentally experiment was designed to provide continuous time series of field data over a long period, in order to improve and validate the Soil-vegetation-Atmosphere Transfer (SVAT parameterisations employed in meteorological models. Intensive measurements were performed for more than three years over fallow farmland in southwestern France. To capture the main processes controlling land-atmosphere exchanges, the local climate was fully characterised, and surface water and energy fluxes, vegetation biomass, soil moisture profiles, surface soil moisture and surface and soil temperature were monitored. Additional physiological measurements were carried out during selected periods to describe the biological control of the fluxes. The MUREX data of 1995, 1996, and 1997 are presented. Four SVAT models are applied to the annual cycle of 1995. In general, they succeed in simulating the main features of the fallow functioning, although some shortcomings are revealed.Key words. Hydrology (evapotranspiration; soil moisture; water-energy interactions.

  10. Palaeotethys seawater temperature rise and an intensified hydrological cycle following the end-Permian mass extinction

    DEFF Research Database (Denmark)

    Schobben, Martin; Joachimski, Michael M.; Korn, Dieter

    2014-01-01

    are presented together with new data from Wuchiapingian to Griesbachian sections in Iran. δ18O data from P-Tr sections in Iran document tropical sea surface temperatures (SST) of 27-33°C during the Changhsingian with a negative shift in δ18O starting at the extinction horizon, translating into a warming of SSTs...... and associated processes, vertical water column stratification, eutrophication and subsequent local anoxia may all have facilitated an extinction event....

  11. 2-way coupling the hydrological land surface model PROMET with the regional climate model MM5

    Directory of Open Access Journals (Sweden)

    F. Zabel

    2013-05-01

    Full Text Available Most land surface hydrological models (LSHMs consider land surface processes (e.g. soil–plant–atmosphere interactions, lateral water flows, snow and ice in a spatially detailed manner. The atmosphere is considered as exogenous driver, neglecting feedbacks between the land surface and the atmosphere. On the other hand, regional climate models (RCMs generally simulate land surface processes through coarse descriptions and spatial scales but include land–atmosphere interactions. What is the impact of the differently applied model physics and spatial resolution of LSHMs on the performance of RCMs? What feedback effects are induced by different land surface models? This study analyses the impact of replacing the land surface module (LSM within an RCM with a high resolution LSHM. A 2-way coupling approach was applied using the LSHM PROMET (1 × 1 km2 and the atmospheric part of the RCM MM5 (45 × 45 km2. The scaling interface SCALMET is used for down- and upscaling the linear and non-linear fluxes between the model scales. The change in the atmospheric response by MM5 using the LSHM is analysed, and its quality is compared to observations of temperature and precipitation for a 4 yr period from 1996 to 1999 for the Upper Danube catchment. By substituting the Noah-LSM with PROMET, simulated non-bias-corrected near-surface air temperature improves for annual, monthly and daily courses when compared to measurements from 277 meteorological weather stations within the Upper Danube catchment. The mean annual bias was improved from −0.85 to −0.13 K. In particular, the improved afternoon heating from May to September is caused by increased sensible heat flux and decreased latent heat flux as well as more incoming solar radiation in the fully coupled PROMET/MM5 in comparison to the NOAH/MM5 simulation. Triggered by the LSM replacement, precipitation overall is reduced; however simulated precipitation amounts are still of high uncertainty, both

  12. Efficient uncertainty quantification in fully-integrated surface and subsurface hydrologic simulations

    Science.gov (United States)

    Miller, K. L.; Berg, S. J.; Davison, J. H.; Sudicky, E. A.; Forsyth, P. A.

    2018-01-01

    Although high performance computers and advanced numerical methods have made the application of fully-integrated surface and subsurface flow and transport models such as HydroGeoSphere common place, run times for large complex basin models can still be on the order of days to weeks, thus, limiting the usefulness of traditional workhorse algorithms for uncertainty quantification (UQ) such as Latin Hypercube simulation (LHS) or Monte Carlo simulation (MCS), which generally require thousands of simulations to achieve an acceptable level of accuracy. In this paper we investigate non-intrusive polynomial chaos for uncertainty quantification, which in contrast to random sampling methods (e.g., LHS and MCS), represents a model response of interest as a weighted sum of polynomials over the random inputs. Once a chaos expansion has been constructed, approximating the mean, covariance, probability density function, cumulative distribution function, and other common statistics as well as local and global sensitivity measures is straightforward and computationally inexpensive, thus making PCE an attractive UQ method for hydrologic models with long run times. Our polynomial chaos implementation was validated through comparison with analytical solutions as well as solutions obtained via LHS for simple numerical problems. It was then used to quantify parametric uncertainty in a series of numerical problems with increasing complexity, including a two-dimensional fully-saturated, steady flow and transient transport problem with six uncertain parameters and one quantity of interest; a one-dimensional variably-saturated column test involving transient flow and transport, four uncertain parameters, and two quantities of interest at 101 spatial locations and five different times each (1010 total); and a three-dimensional fully-integrated surface and subsurface flow and transport problem for a small test catchment involving seven uncertain parameters and three quantities of interest at

  13. The possible influence of terracettes on surface hydrology of steep-sloping and subalpine environments

    Science.gov (United States)

    Greenwood, Philip; Kuonen, Samuel; Fister, Wolfgang; Kuhn, Nikolaus

    2015-04-01

    could provide temporary storage for runoff-associated substances. Greater understanding of the exact influence of terracettes on surface hydrology in steep-sloping and subalpine environments could benefit the future management of grazing and rangelands in such areas.

  14. Hydrologic controls on nitrogen cycling processes and functional gene abundance in sediments of a groundwater flow-through lake

    Science.gov (United States)

    Stoliker, Deborah L.; Repert, Deborah A.; Smith, Richard L.; Song, Bongkeun; LeBlanc, Denis R.; McCobb, Timothy D.; Conaway, Christopher; Hyun, Sung Pil; Koh, Dong-Chan; Moon, Hee Sun; Kent, Douglas B.

    2016-01-01

    The fate and transport of inorganic nitrogen (N) is a critically important issue for human and aquatic ecosystem health because discharging N-contaminated groundwater can foul drinking water and cause algal blooms. Factors controlling N-processing were examined in sediments at three sites with contrasting hydrologic regimes at a lake on Cape Cod, MA. These factors included water chemistry, seepage rates and direction of groundwater flow, and the abundance and potential rates of activity of N-cycling microbial communities. Genes coding for denitrification, anaerobic ammonium oxidation (anammox), and nitrification were identified at all sites regardless of flow direction or groundwater dissolved oxygen concentrations. Flow direction was, however, a controlling factor in the potential for N-attenuation via denitrification in the sediments. Potential rates of denitrification varied from 6 to 4500 pmol N/g/h from the inflow to the outflow side of the lake, owing to fundamental differences in the supply of labile organic matter. The results of laboratory incubations suggested that when anoxia and limiting labile organic matter prevailed, the potential existed for concomitant anammox and denitrification. Where oxic lake water was downwelling, potential rates of nitrification at shallow depths were substantial (1640 pmol N/g/h). Rates of anammox, denitrification, and nitrification may be linked to rates of organic N-mineralization, serving to increase N-mobility and transport downgradient.

  15. What will be the impacts of climate change on surface hydrology in France by 2070?

    International Nuclear Information System (INIS)

    Chauveau, Mathilde; Chazot, Sebastien; David, Julian; Norotte, Thomas; Perrin, Charles; Bourgin, Pierre-Yves; Sauquet, Eric; Vidal, Jean-Philippe; Rouchy, Nathalie; Martin, Eric; Maugis, Pascal; De Lacaze, Xavier

    2013-01-01

    Within the Explore 2070 project, an evaluation of the possible impacts of climate change on surface water between the 1961-1990 reference period and the 2046-2065 period was carried out in continental France and i n overseas departments on the basis of the A1B greenhouse gas emission scenario, seven general circulation models an d two hydrological models (Isba-Modcou and GR4J). In continental France, results indicate: (1) a possible increase in ai r temperature between +1.4 deg. C and +3 deg. C; (2) an uncertain evolution of precipitation, most models however agreeing on a decreasing trend in summer precipitation; (3) a significant decrease (10% to 40%) of mean annual flows at the country scale, especially pronounced in the Seine-Normandie and Adour-Garonne districts; (4) a strong decrease in summer lo w flows in most basins; (5) more heterogeneous and less significant evolutions for floods. A special care was given to the quantification of the uncertainties linked to these results. They provide an indication of the significance of projected changes. The evolutions calculated in the overseas zones can be considered non-significant given the level of uncertainty linked to the hydro-climatic modelling chain. These results urge to implement adaptation strategies based on a better management of water resources, among others. (authors)

  16. Surface hydrologic characteristics of proposed repository locations in the Palo Duro Basin of the Texas Panhandle

    International Nuclear Information System (INIS)

    1985-04-01

    This report provides a description of the surface hydrology in the two proposed locations of a high-level waste repository within the Palo Duro Basin of the Texas Panhandle. Included for consideration are the topography; the major drainage systems - Palo Duro, Tierra Blanca, and Tule Creeks, and Prairie Dog Town Fork of the Red River; and the most prominent impoundments, the playa lakes. The magnitude and frequency of precipitation throughout the region are discussed, and rainfall depth-duration-area data for the 100-year, 500-year, and probable maximum storms are presented. Soil properties are also described, with specific reference to the infiltration and runoff processes and the contribution of these processes to Ogallala aquifer recharge. A summary discussion of the local streams includes information on historical streamflow, a brief description of flooding, and results of a study of floodplains for the 100-year, 500-year, and probable maximum storms. The report concludes with a characterization of the water quality of these streams and an explanation of the local geologic influences on stream-water chemistry. 25 figures, 20 tables

  17. A regional-scale, high resolution dynamical malaria model that accounts for population density, climate and surface hydrology.

    Science.gov (United States)

    Tompkins, Adrian M; Ermert, Volker

    2013-02-18

    The relative roles of climate variability and population related effects in malaria transmission could be better understood if regional-scale dynamical malaria models could account for these factors. A new dynamical community malaria model is introduced that accounts for the temperature and rainfall influences on the parasite and vector life cycles which are finely resolved in order to correctly represent the delay between the rains and the malaria season. The rainfall drives a simple but physically based representation of the surface hydrology. The model accounts for the population density in the calculation of daily biting rates. Model simulations of entomological inoculation rate and circumsporozoite protein rate compare well to data from field studies from a wide range of locations in West Africa that encompass both seasonal endemic and epidemic fringe areas. A focus on Bobo-Dioulasso shows the ability of the model to represent the differences in transmission rates between rural and peri-urban areas in addition to the seasonality of malaria. Fine spatial resolution regional integrations for Eastern Africa reproduce the malaria atlas project (MAP) spatial distribution of the parasite ratio, and integrations for West and Eastern Africa show that the model grossly reproduces the reduction in parasite ratio as a function of population density observed in a large number of field surveys, although it underestimates malaria prevalence at high densities probably due to the neglect of population migration. A new dynamical community malaria model is publicly available that accounts for climate and population density to simulate malaria transmission on a regional scale. The model structure facilitates future development to incorporate migration, immunity and interventions.

  18. Hydrology and surface morphology of the Bonneville Salt Flats and Pilot Valley Playa, Utah

    Science.gov (United States)

    Lines, Gregory C.

    1979-01-01

    The Bonneville Salt Flats and Pilot Valley are in the western part of the Great Salt Lake Desert in northwest Utah. The areas are separate, though similar, hydrologic basins, and both contain a salt crust. The Bonneville salt crust covered about 40 square miles in the fall of 1976, and the salt crust in Pilot Valley covered 7 square miles. Both areas lack any noticeable surface relief (in 1976, 1.3 feet on the Bonneville salt crust and 0.3 foot on the Pilot Valley salt crust).The salt crust on the Salt Flats has been used for many years for automobile racing, and brines from shallow lacustrine deposits have been used for the production of potash. In recent years, there has been an apparent conflict between these two major uses of the area as the salt crust has diminished in both thickness and extent. Much of the Bonneville Racetrack has become rougher, and there has also been an increase in the amount of sediment on the south end of the racetrack. The Pilot Valley salt crust and surrounding playa have been largely unused.Evaporite minerals on the Salt Flats and the Pilot Valley playa are concentrated in three zones: (1) a carbonate zone composed mainly of authigenic clay-size carbonate minerals, (2) a sulfate zone composed mainly of authigenic gypsum, and (3) a chloride zone composed of crystalline halite (the salt crust). Five major types of salt crust were recognized on the Salt Flats, but only one type was observed in Pilot Valley. Geomorphic differences in the salt crust are caused by differences in their hydrologic environments. The salt crusts are dynamic features that are subject to change because of climatic factors and man's activities.Ground water occurs in three distinct aquifers in much of the western Great Salt Lake Desert: (1) the basin-fill aquifer, which yields water from conglomerate in the lower part of the basin fill, (2) the alluvial-fan aquifer, which yields water from sand and gravel along the western margins of both playas, and (3) the

  19. Valuing Non-market Benefits of Rehabilitation of Hydrologic Cycle Improvements in the Anyangcheon Watershed: Using Mixed Logit Models

    Science.gov (United States)

    Yoo, J.; Kong, K.

    2010-12-01

    This research the findings from a discrete-choice experiment designed to estimate the economic benefits associated with the Anyangcheon watershed improvements in Rep. of Korea. The Anyangcheon watershed has suffered from streamflow depletion and poor stream quality, which often negatively affect instream and near-stream ecologic integrity, as well as water supply. Such distortions in the hydrologic cycle mainly result from rapid increase of impermeable area due to urbanization, decreases of baseflow runoff due to groundwater pumping, and reduced precipitation inputs driven by climate forcing. As well, combined sewer overflows and increase of non-point source pollution from urban regions decrease water quality. The appeal of choice experiments (CE) in economic analysis is that it is based on random utility theory (McFadden, 1974; Ben-Akiva and Lerman, 1985). In contrast to contingent valuation method (CVM), which asks people to choose between a base case and a specific alternative, CE asks people to choice between cases that are described by attributes. The attributes of this study were selected from hydrologic vulnerability components that represent flood damage possibility, instreamflow depletion, water quality deterioration, form of the watershed and tax. Their levels were divided into three grades include status quo. Two grades represented the ideal conditions. These scenarios were constructed from a 35 orthogonal main effect design. This design resulted in twenty-seven choice sets. The design had nine different choice scenarios presented to each respondent. The most popular choice models in use are the conditional logit (CNL). This model provides closed-form choice probability calculation. The shortcoming of CNL comes from irrelevant alternatives (IIA). In this paper, the mixed logit (ML) is applied to allow the coefficient’s variation for random taste heterogeneity in the population. The mixed logit model(with normal distributions for the attributes) fit the

  20. Hydrology of surface waters and thermohaline circulation during the last glacial period

    International Nuclear Information System (INIS)

    Vidal, L.

    1996-01-01

    Sedimentological studies on oceanic cores from the north Atlantic have revealed, over the last glacial period, abrupt climatic changes with a periodicity of several thousand years which contrasts strongly with the glacial-interglacial periodicity (several tens of thousand years). These periods of abrupt climate changes correspond to massive icebergs discharges into the north Atlantic. The aim of this work was to study the evolution of the thermohaline circulation in relation to these episodic iceberg discharges which punctuated the last 60 ka. To reconstruct the oceanic circulation in the past, we have analysed oxygen and carbon stable isotopes on benthic foraminifera from north Atlantic deep-sea cores. First of all, the higher temporal resolution of sedimentary records has enabled us to establish a precise chrono-stratigraphy for the different cores. Then, we have shown the close linkage between surface water hydrology and deep circulation, giving evidence of the sensibility of thermohaline circulation to melt water input in the north Atlantic ocean. Indeed, changes in deep circulation are synchronous from those identified in surface waters and are recorded on a period which lasted ∼ 1500 years. Deep circulation reconstructions, before and during a typical iceberg discharge reveal several modes of circulation linked to different convection sites at the high latitudes of the Atlantic basin. Moreover, the study of the last glacial period gives the opportunity to differentiate circulation changes due to the external forcing (variations of the orbital parameters) and those linked to a more local forcing (icebergs discharges). 105 refs., 50 figs., 14 tabs., 4 appends

  1. Design and development of a smart aerial platform for surface hydrological measurements

    Science.gov (United States)

    Tauro, F.; Pagano, C.; Porfiri, M.; Grimaldi, S.

    2013-12-01

    Currently available experimental methodologies for surface hydrological monitoring rely on the use of intrusive sensing technologies which tend to provide local rather than distributed information on the flow physics. In this context, drawbacks deriving from the use of invasive instrumentation are partially alleviated by Large Scale Particle Image Velocimetry (LSPIV). LSPIV is based on the use of cameras mounted on masts along river banks which capture images of artificial tracers or naturally occurring objects floating on water surfaces. Images are then georeferenced and the displacement of groups of floating tracers statistically analyzed to reconstruct flow velocity maps at specific river cross-sections. In this work, we mitigate LSPIV spatial limitations and inaccuracies due to image calibration by designing and developing a smart platform which integrates digital acquisition system and laser calibration units onboard of a custom-built quadricopter. The quadricopter is designed to be lightweight, low cost as compared to kits available on the market, highly customizable, and stable to guarantee minimal vibrations during image acquisition. The onboard digital system includes an encased GoPro Hero 3 camera whose axis is constantly kept orthogonal to the water surface by means of an in-house developed gimbal. The gimbal is connected to the quadricopter through a shock absorber damping device which further reduces eventual vibrations. Image calibration is performed through laser units mounted at known distances on the quadricopter landing apparatus. The vehicle can be remotely controlled by the open-source Ardupilot microcontroller. Calibration tests and field experiments are conducted in outdoor environments to assess the feasibility of using the smart platform for acquisition of high quality images of natural streams. Captured images are processed by LSPIV algorithms and average flow velocities are compared to independently acquired flow estimates. Further, videos

  2. Understanding wetland sub-surface hydrology using geologic and isotopic signatures

    Directory of Open Access Journals (Sweden)

    P. Sahu

    2009-07-01

    Full Text Available This paper attempts to utilize hydrogeology and isotope composition of groundwater to understand the present hydrological processes prevalent in a freshwater wetland, source of wetland groundwater, surface water/groundwater interaction and mixing of groundwater of various depth zones in the aquifer. This study considers East Calcutta Wetlands (ECW – a freshwater peri-urban inland wetland ecosystem located at the lower part of the deltaic alluvial plain of South Bengal Basin and east of Kolkata city. This wetland is well known over the world for its resource recovery systems, developed by local people through ages, using wastewater of the city. Geological investigations reveal that the sub-surface geology is completely blanketed by the Quaternary sediments comprising a succession of silty clay, sand of various grades and sand mixed with occasional gravels and thin intercalations of silty clay. At few places the top silty clay layer is absent due to scouring action of past channels. In these areas sand is present throughout the geological column and the areas are vulnerable to groundwater pollution. Groundwater mainly flows from east to west and is being over-extracted to the tune of 65×103 m3/day. δ18O and δD values of shallow and deep groundwater are similar indicating resemblance in hydrostratigraphy and climate of the recharge areas. Groundwater originates mainly from monsoonal rain with some evaporation prior to or during infiltration and partly from bottom of ponds, canals and infiltration of groundwater withdrawn for irrigation. Relatively high tritium content of the shallow groundwater indicates local recharge, while the deep groundwater with very low tritium is recharged mainly from distant areas. At places the deep aquifer has relatively high tritium, indicating mixing of groundwater of shallow and deep aquifers. Metals such as copper, lead, arsenic, cadmium, aluminium, nickel and chromium are also

  3. Understanding wetland sub-surface hydrology using geologic and isotopic signatures

    Science.gov (United States)

    Sikdar, P. K.; Sahu, P.

    2009-07-01

    This paper attempts to utilize hydrogeology and isotope composition of groundwater to understand the present hydrological processes prevalent in a freshwater wetland, source of wetland groundwater, surface water/groundwater interaction and mixing of groundwater of various depth zones in the aquifer. This study considers East Calcutta Wetlands (ECW) - a freshwater peri-urban inland wetland ecosystem located at the lower part of the deltaic alluvial plain of South Bengal Basin and east of Kolkata city. This wetland is well known over the world for its resource recovery systems, developed by local people through ages, using wastewater of the city. Geological investigations reveal that the sub-surface geology is completely blanketed by the Quaternary sediments comprising a succession of silty clay, sand of various grades and sand mixed with occasional gravels and thin intercalations of silty clay. At few places the top silty clay layer is absent due to scouring action of past channels. In these areas sand is present throughout the geological column and the areas are vulnerable to groundwater pollution. Groundwater mainly flows from east to west and is being over-extracted to the tune of 65×103 m3/day. δ18O and δD values of shallow and deep groundwater are similar indicating resemblance in hydrostratigraphy and climate of the recharge areas. Groundwater originates mainly from monsoonal rain with some evaporation prior to or during infiltration and partly from bottom of ponds, canals and infiltration of groundwater withdrawn for irrigation. Relatively high tritium content of the shallow groundwater indicates local recharge, while the deep groundwater with very low tritium is recharged mainly from distant areas. At places the deep aquifer has relatively high tritium, indicating mixing of groundwater of shallow and deep aquifers. Metals such as copper, lead, arsenic, cadmium, aluminium, nickel and chromium are also present in groundwater of various depths. Therefore

  4. Full Coupling Between the Atmosphere, Surface, and Subsurface for Integrated Hydrologic Simulation

    Science.gov (United States)

    Davison, Jason Hamilton; Hwang, Hyoun-Tae; Sudicky, Edward A.; Mallia, Derek V.; Lin, John C.

    2018-01-01

    An ever increasing community of earth system modelers is incorporating new physical processes into numerical models. This trend is facilitated by advancements in computational resources, improvements in simulation skill, and the desire to build numerical simulators that represent the water cycle with greater fidelity. In this quest to develop a state-of-the-art water cycle model, we coupled HydroGeoSphere (HGS), a 3-D control-volume finite element surface and variably saturated subsurface flow model that includes evapotranspiration processes, to the Weather Research and Forecasting (WRF) Model, a 3-D finite difference nonhydrostatic mesoscale atmospheric model. The two-way coupled model, referred to as HGS-WRF, exchanges the actual evapotranspiration fluxes and soil saturations calculated by HGS to WRF; conversely, the potential evapotranspiration and precipitation fluxes from WRF are passed to HGS. The flexible HGS-WRF coupling method allows for unique meshes used by each model, while maintaining mass and energy conservation between the domains. Furthermore, the HGS-WRF coupling implements a subtime stepping algorithm to minimize computational expense. As a demonstration of HGS-WRF's capabilities, we applied it to the California Basin and found a strong connection between the depth to the groundwater table and the latent heat fluxes across the land surface.

  5. Historical trends and the long-term changes of the hydrological cycle components in a Mediterranean river basin.

    Science.gov (United States)

    Mentzafou, A; Wagner, S; Dimitriou, E

    2018-04-29

    Identifying the historical hydrometeorological trends in a river basin is necessary for understanding the dominant interactions between climate, human activities and local hydromorphological conditions. Estimating the hydrological reference conditions in a river is also crucial for estimating accurately the impacts from human water related activities and design appropriate water management schemes. In this effort, the output of a regional past climate model was used, covering the period from 1660 to 1990, in combination with a dynamic, spatially distributed, hydrologic model to estimate the past and recent trends in the main hydrologic parameters such as overland flow, water storages and evapotranspiration, in a Mediterranean river basin. The simulated past hydrologic conditions (1660-1960) were compared with the current hydrologic regime (1960-1990), to assess the magnitude of human and natural impacts on the identified hydrologic trends. The hydrological components of the recent period of 2008-2016 were also examined in relation to the impact of human activities. The estimated long-term trends of the hydrologic parameters were partially assigned to varying atmospheric forcing due to volcanic activity combined with spontaneous meteorological fluctuations. Copyright © 2018. Published by Elsevier B.V.

  6. Assessing the impact of model spin-up on surface water-groundwater interactions using an integrated hydrologic model

    KAUST Repository

    Ajami, Hoori

    2014-03-01

    Integrated land surface-groundwater models are valuable tools in simulating the terrestrial hydrologic cycle as a continuous system and exploring the extent of land surface-subsurface interactions from catchment to regional scales. However, the fidelity of model simulations is impacted not only by the vegetation and subsurface parameterizations, but also by the antecedent condition of model state variables, such as the initial soil moisture, depth to groundwater, and ground temperature. In land surface modeling, a given model is often run repeatedly over a single year of forcing data until it reaches an equilibrium state: the point at which there is minimal artificial drift in the model state or prognostic variables (most often the soil moisture). For more complex coupled and integrated systems, where there is an increased computational cost of simulation and the number of variables sensitive to initialization is greater than in traditional uncoupled land surface modeling schemes, the challenge is to minimize the impact of initialization while using the smallest spin-up time possible. In this study, multicriteria analysis was performed to assess the spin-up behavior of the ParFlow.CLM integrated groundwater-surface water-land surface model over a 208 km2 subcatchment of the Ringkobing Fjord catchment in Denmark. Various measures of spin-up performance were computed for model state variables such as the soil moisture and groundwater storage, as well as for diagnostic variables such as the latent and sensible heat fluxes. The impacts of initial conditions on surface water-groundwater interactions were then explored. Our analysis illustrates that the determination of an equilibrium state depends strongly on the variable and performance measure used. Choosing an improper initialization of the model can generate simulations that lead to a misinterpretation of land surface-subsurface feedback processes and result in large biases in simulated discharge. Estimated spin

  7. Description of climate, surface hydrology, and near-surface hydrogeology. Preliminary site description. Forsmark area - version 1.2

    Energy Technology Data Exchange (ETDEWEB)

    Johansson, Per-Olof [Artesia Grundvattenkonsult AB, Stockholm (Sweden); Werner, Kent [SWECO VIAK AB/Golder Associates AB, Stockholm (Sweden); Bosson, Emma; Berglund, Sten [Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden); Juston, John [DBE Sweden, Uppsala (Sweden)

    2005-06-15

    The Swedish Nuclear Fuel and Waste Management Company (SKB) is conducting site investigations at two different locations, the Forsmark and Simpevarp areas, with the objective of siting a geological repository for spent nuclear fuel. The results from the investigations at the sites are used as a basic input to the development of Site Descriptive Models (SDM). The SDM shall summarise the current state of knowledge of the site, and provide parameters and models to be used in further analyses within Safety Assessment, Repository Design and Environmental Impact Assessment. The present report is a background report describing the meteorological conditions and the modelling of surface hydrology and near-surface hydrogeology in support of the Forsmark version 1.2 SDM based on the data available in the Forsmark 1.2 'data freeze' (July 31, 2004). The groundwater is very shallow, with groundwater levels within one meter below ground as an annual mean for almost all groundwater monitoring wells. Also, the annual groundwater level amplitude is less than 1.5 m for most wells. The shallow groundwater levels mean that there is a strong interaction between evapotranspiration, soil moisture and groundwater. In the modelling, surface water and near-surface groundwater divides are assumed to coincide. The small-scale topography implies that many local, shallow groundwater flow systems are formed in the Quaternary deposits, overlaying more large-scale flow systems associated with groundwater flows at greater depths. Groundwater level time series from wells in till and bedrock within the same areas show a considerably higher groundwater level in the till than in the bedrock. The observed differences in levels are not fully consistent with the good hydraulic contact between overburden and bedrock indicated by the hydraulic tests in the Quaternary deposits. However, the relatively lower groundwater levels in the bedrock may be caused by the horizontal to sub-horizontal highly

  8. Description of climate, surface hydrology, and near-surface hydrogeology. Preliminary site description. Forsmark area - version 1.2

    International Nuclear Information System (INIS)

    Johansson, Per-Olof; Werner, Kent; Bosson, Emma; Berglund, Sten; Juston, John

    2005-06-01

    The present report is a background report describing the meteorological conditions and the modelling of surface hydrology and near-surface hydrogeology in support of the Forsmark version 1.2 SDM based on the data available in the Forsmark 1.2 ''data freeze'' (July 31, 2004). The area covered in the conceptual and descriptive modelling is characterised by a low relief and a small-scale topography. Almost the whole area is located below 20 m a s l (metres above sea level). The corrected mean annual precipitation is 600-650 mm and the mean annual evapotranspiration can be estimated to a little more than 400 mm, leaving approximately 200 mm x year-1 for runoff. Till is the dominating Quaternary deposit covering approximately 75% of the area. In most of the area, the till is sandy. Bedrock outcrops are frequent but cover only approximately 5% of the area. Direct groundwater recharge from precipitation is the dominant source of groundwater recharge. The small-scale topography implies that many local, shallow groundwater flow systems are formed in the Quaternary deposits, overlaying more large-scale flow systems associated with groundwater flows at greater depths. Groundwater level time series from wells in till and bedrock within the same areas show a considerably higher groundwater level in the till than in the bedrock. The sediment stratigraphy of lakes and wetlands is crucial for their function as discharge areas for groundwater. Comparisons between measured lake water levels and groundwater levels below and around lakes indicate that the lakes in some cases may act as sources of groundwater recharge. Specifically, observations from Lake Bolundsfjaerden and Lake Eckarfjaerden show that such conditions were at hand during the dry summer of 2003. However, whether the observed water level relations correspond to significant water fluxes depends also on the hydrogeological properties of the lake sediments and the underlying Quaternary deposits. ''Old'' water with high

  9. The response of zooplankton communities to the 2016 extreme hydrological cycle in floodplain lakes connected to the Yangtze River in China.

    Science.gov (United States)

    Zhang, Kun; Xu, Mei; Wu, Qili; Lin, Zhi; Jiang, Fangyuan; Chen, Huan; Zhou, Zhongze

    2018-06-04

    The Huayanghe Lakes play an important role in the Yangtze floodplain in China and had extremely high water levels during the summer of 2016. Monitoring data was collected in an effort to understand the impact of this change on the crustacean zooplankton composition and abundance and the biomass variation in the Huayanghe Lakes between a regular hydrological cycle (RHC) and an extreme hydrological cycle (EHC). The crustacean zooplankton community composition, abundance, and biomass in the floodplain lakes were markedly affected by the water-level disturbance. The number of species was lower in the RHC, but the mean density and biomass decreased from 93.84 ± 13.29 ind./L and 6.11 ± 0.89 mg/L, respectively, in the RHC to 66.62 ± 10.88 ind./L and 1.22 ± 0.26 mg/L, respectively, in the EHC. Pearson correlations and redundancy analyses revealed the environmental factors with the most significant impact on the crustacean zooplankton community differed between the RHC and EHC cycles. Little previous information exists on the zooplankton in these lakes, and the present study provides data on the zooplankton composition, abundance, and biomass, both at baseline and in response to hydrological changes.

  10. Anthropogenic hydrological cycle disturbance at a regional scale: State-wide evapotranspiration trends (1979-2015) across Nebraska, USA

    Science.gov (United States)

    Szilagyi, Jozsef

    2018-02-01

    Trends in monthly evapotranspiration (ET) rates across Nebraska, the most intensely irrigated state within the US, were calculated by the calibration-free version of the nonlinear complementary relationship of evaporation over the 1979-2015 period utilizing North American Regional Reanalysis (NARR) net radiation, 10-m wind velocity, as well as Parameter Regression Independent Slope Model (PRISM) air- and dew-point temperature data. State-averaged modeled ET rates rose by 5.5 mm decade-1 due to the presence of wide-spread large-scale irrigation projects in accordance with a 2.4 mm decade-1 increase in PRISM precipitation (P) and a simultaneous -2.8 mm decade-1 drop in United States Geological Survey's state-averaged annual streamflow rates, raising the state-wide ET to P ratio from 0.89 to 0.91 over the modeled time-period. ET rates over irrigated crops increased by 7 mm decade-1 despite a -4.4 mm decade-1 drop in precipitation rates. A similar increase in ET rates (6 mm decade-1) required 8.1 mm decade-1 increase in precipitation rates across the non-irrigated Sand Hills of Nebraska. Published NARR ET rates are unable to pick up this unusual regional trend. Since an increase in precipitation rates should normally decrease the ET ratio, as predicted by the Budyko curve, this study yields evidence on how dramatically sustained large-scale irrigation can alter the regional hydrologic cycle not only through a) trivially depleting streamflow rates and/or lowering groundwater table levels; b) suppressing precipitation locally (while enhancing it a long distance downwind), but also; c) reversing the trajectory of the regional ET ratio under generally increasing trends of precipitation.

  11. Flood Simulations and Uncertainty Analysis for the Pearl River Basin Using the Coupled Land Surface and Hydrological Model System

    Directory of Open Access Journals (Sweden)

    Yongnan Zhu

    2017-06-01

    Full Text Available The performances of hydrological simulations for the Pearl River Basin in China were analysed using the Coupled Land Surface and Hydrological Model System (CLHMS. Three datasets, including East Asia (EA, high-resolution gauge satellite-merged China Merged Precipitation Analysis (CMPA-Daily, and the Asian Precipitation Highly-Resolved Observational Data Integration Towards Evaluation (APHRODITE daily precipitation were used to drive the CLHMS model to simulate daily hydrological processes from 1998 to 2006. The results indicate that the precipitation data was the most important source of uncertainty in the hydrological simulation. The simulated streamflow driven by the CMPA-Daily agreed well with observations, with a Pearson correlation coefficient (PMC greater than 0.70 and an index of agreement (IOA similarity coefficient greater than 0.82 at Liuzhou, Shijiao, and Wuzhou Stations. Comparison of the Nash-Sutcliffe efficiency coefficient (NSE shows that the peak flow simulation ability of CLHMS driven with the CMPA-Daily rainfall is relatively superior to that with the EA and APHRODITE datasets. The simulation results for the high-flow periods in 1998 and 2005 indicate that the CLHMS is promising for its future application in the flood simulation and prediction.

  12. A Regional Model for Malaria Vector Developmental Habitats Evaluated Using Explicit, Pond-Resolving Surface Hydrology Simulations.

    Directory of Open Access Journals (Sweden)

    Ernest Ohene Asare

    Full Text Available Dynamical malaria models can relate precipitation to the availability of vector breeding sites using simple models of surface hydrology. Here, a revised scheme is developed for the VECTRI malaria model, which is evaluated alongside the default scheme using a two year simulation by HYDREMATS, a 10 metre resolution, village-scale model that explicitly simulates individual ponds. Despite the simplicity of the two VECTRI surface hydrology parametrization schemes, they can reproduce the sub-seasonal evolution of fractional water coverage. Calibration of the model parameters is required to simulate the mean pond fraction correctly. The default VECTRI model tended to overestimate water fraction in periods subject to light rainfall events and underestimate it during periods of intense rainfall. This systematic error was improved in the revised scheme by including the a parametrization for surface run-off, such that light rainfall below the initial abstraction threshold does not contribute to ponds. After calibration of the pond model, the VECTRI model was able to simulate vector densities that compared well to the detailed agent based model contained in HYDREMATS without further parameter adjustment. Substituting local rain-gauge data with satellite-retrieved precipitation gave a reasonable approximation, raising the prospects for regional malaria simulations even in data sparse regions. However, further improvements could be made if a method can be derived to calibrate the key hydrology parameters of the pond model in each grid cell location, possibly also incorporating slope and soil texture.

  13. A Regional Model for Malaria Vector Developmental Habitats Evaluated Using Explicit, Pond-Resolving Surface Hydrology Simulations.

    Science.gov (United States)

    Asare, Ernest Ohene; Tompkins, Adrian Mark; Bomblies, Arne

    2016-01-01

    Dynamical malaria models can relate precipitation to the availability of vector breeding sites using simple models of surface hydrology. Here, a revised scheme is developed for the VECTRI malaria model, which is evaluated alongside the default scheme using a two year simulation by HYDREMATS, a 10 metre resolution, village-scale model that explicitly simulates individual ponds. Despite the simplicity of the two VECTRI surface hydrology parametrization schemes, they can reproduce the sub-seasonal evolution of fractional water coverage. Calibration of the model parameters is required to simulate the mean pond fraction correctly. The default VECTRI model tended to overestimate water fraction in periods subject to light rainfall events and underestimate it during periods of intense rainfall. This systematic error was improved in the revised scheme by including the a parametrization for surface run-off, such that light rainfall below the initial abstraction threshold does not contribute to ponds. After calibration of the pond model, the VECTRI model was able to simulate vector densities that compared well to the detailed agent based model contained in HYDREMATS without further parameter adjustment. Substituting local rain-gauge data with satellite-retrieved precipitation gave a reasonable approximation, raising the prospects for regional malaria simulations even in data sparse regions. However, further improvements could be made if a method can be derived to calibrate the key hydrology parameters of the pond model in each grid cell location, possibly also incorporating slope and soil texture.

  14. Comparing and Combining Remotely Sensed Land Surface Temperature Products for Improved Hydrological Applications

    Directory of Open Access Journals (Sweden)

    Robert M. Parinussa

    2016-02-01

    Full Text Available Land surface temperature (LST is an important variable that provides a valuable connection between the energy and water budget and is strongly linked to land surface hydrology. Space-borne remote sensing provides a consistent means for regularly observing LST using thermal infrared (TIR and passive microwave observations each with unique strengths and weaknesses. The spatial resolution of TIR based LST observations is around 1 km, a major advantage when compared to passive microwave observations (around 10 km. However, a major advantage of passive microwaves is their cloud penetrating capability making them all-weather sensors whereas TIR observations are routinely masked under the presence of clouds and aerosols. In this study, a relatively simple combination approach that benefits from the cloud penetrating capacity of passive microwave sensors was proposed. In the first step, TIR and passive microwave LST products were compared over Australia for both anomalies and raw timeseries. A very high agreement was shown over the vast majority of the country with R2 typically ranging from 0.50 to 0.75 for the anomalies and from 0.80 to 1.00 for the raw timeseries. Then, the scalability of the passive microwave based LST product was examined and a pixel based merging approach through linear scaling was proposed. The individual and merged LST products were further compared against independent LST from the re-analysis model outputs. This comparison revealed that the TIR based LST product agrees best with the re-analysis data (R2 0.26 for anomalies and R2 0.76 for raw data, followed by the passive microwave LST product (R2 0.16 for anomalies and R2 0.66 for raw data and the combined LST product (R2 0.18 for anomalies and R2 0.62 for raw data. It should be noted that the drop in performance comes with an increased revisit frequency of approximately 20% compared to the revised frequency of the TIR alone. Additionally, this comparison against re

  15. Hydrologic response to multimodel climate output using a physically based model of groundwater/surface water interactions

    Science.gov (United States)

    Sulis, M.; Paniconi, C.; Marrocu, M.; Huard, D.; Chaumont, D.

    2012-12-01

    General circulation models (GCMs) are the primary instruments for obtaining projections of future global climate change. Outputs from GCMs, aided by dynamical and/or statistical downscaling techniques, have long been used to simulate changes in regional climate systems over wide spatiotemporal scales. Numerous studies have acknowledged the disagreements between the various GCMs and between the different downscaling methods designed to compensate for the mismatch between climate model output and the spatial scale at which hydrological models are applied. Very little is known, however, about the importance of these differences once they have been input or assimilated by a nonlinear hydrological model. This issue is investigated here at the catchment scale using a process-based model of integrated surface and subsurface hydrologic response driven by outputs from 12 members of a multimodel climate ensemble. The data set consists of daily values of precipitation and min/max temperatures obtained by combining four regional climate models and five GCMs. The regional scenarios were downscaled using a quantile scaling bias-correction technique. The hydrologic response was simulated for the 690 km2des Anglais catchment in southwestern Quebec, Canada. The results show that different hydrological components (river discharge, aquifer recharge, and soil moisture storage) respond differently to precipitation and temperature anomalies in the multimodel climate output, with greater variability for annual discharge compared to recharge and soil moisture storage. We also find that runoff generation and extreme event-driven peak hydrograph flows are highly sensitive to any uncertainty in climate data. Finally, the results show the significant impact of changing sequences of rainy days on groundwater recharge fluxes and the influence of longer dry spells in modifying soil moisture spatial variability.

  16. Effects of plough pan development on surface hydrology and on soil physical properties in Southeastern Brazilian plateau

    Science.gov (United States)

    Bertolino, Ana V. F. A.; Fernandes, Nelson F.; Miranda, João P. L.; Souza, Andréa P.; Lopes, Marcel R. S.; Palmieri, Francesco

    2010-10-01

    SummaryConventional tillage may impose changes in soil physical properties that lead to a decrease in soil physical quality. Although plough pan formation is considered to be an important consequence of conventional tillage practices in Southeastern Brazil, few studies have focused on its hydrological consequences. Detailed investigations in two experimental plots located in the hilly landscape of Serra do Mar close to Rio de Janeiro city were carried out to characterize the changes in soil physical properties and in soil hydrology due to plough pan formation. Conventional (CT) and minimum tillage (MT) practices were implemented in two plots for 3 years and soil matric potential (SMP) was monitored in each plot via nests of tensiometers and Watermark® sensors installed at different depths. Undisturbed soil blocks were collected for micromorphological analyses to quantify the total pore space in soils under CT and MT systems, and in soils under natural tropical forest. Results suggest that soils under the CT system developed a plough pan layer at about 20 cm depth that had 44% less total porosity as compared to surface conditions. It is shown that soils under the CT system tended to stay saturated for longer periods of time after each rainfall event. Besides, during intense rainy periods soils under the CT system may develop hydrologic conditions that favor lateral flows while soils under the MT system were still draining. Such hydrological responses may explain why average soil erosion rates measured for individual rainfall events under the CT system were about 2.5 times greater than the ones observed at MT. The results attested that conventional tillage in this area generated modifications in soil fabric, especially in pore-size distribution and connectivity, which induced important changes in soil hydrology and soil erosion. The agricultural practices used in this area, associated with the local steep hillslopes and intense rainfall events, are definitely not

  17. Development of hydrological models and surface process modelization Study case in High Mountain slopes

    International Nuclear Information System (INIS)

    Loaiza, Juan Carlos; Pauwels, Valentijn R

    2011-01-01

    Hydrological models are useful because allow to predict fluxes into the hydrological systems, which is useful to predict foods and violent phenomenon associated to water fluxes, especially in materials under a high meteorization level. The combination of these models with meteorological predictions, especially with rainfall models, allow to model water behavior into the soil. On most of cases, this type of models is really sensible to evapotranspiration. On climatic studies, the superficial processes have to be represented adequately. Calibration and validation of these models is necessary to obtain reliable results. This paper is a practical exercise of application of complete hydrological information at detailed scale in a high mountain catchment, considering the soil use and types more representatives. The information of soil moisture, infiltration, runoff and rainfall is used to calibrate and validate TOPLATS hydrological model to simulate the behavior of soil moisture. The finds show that is possible to implement an hydrological model by means of soil moisture information use and an equation of calibration by Extended Kalman Filter (EKF).

  18. Numerical modelling of surface hydrology and near-surface hydrogeology at Forsmark. Site descriptive modelling SDM. Site Forsmark

    Energy Technology Data Exchange (ETDEWEB)

    Bosson, Emma (Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden)); Gustafsson, Lars-Goeran; Sassner, Mona (DHI Sverige AB, Stockholm (Sweden))

    2008-09-15

    SKB is currently performing site investigations at two potential sites for a final repository for spent nuclear fuel. This report presents results of water flow and solute transport modelling of the Forsmark site. The modelling reported in this document focused on the near-surface groundwater, i.e. groundwater in Quaternary deposits and shallow rock, and surface water systems, and was performed using the MIKE SHE tool. The most recent site data used in the modelling were delivered in the Forsmark 2.3 dataset, which had its 'data freeze' on March 31, 2007. The present modelling is performed in support of the final version of the Forsmark site description that is produced during the site investigation phase. In this work, the hydrological modelling system MIKE SHE has been used to describe near-surface groundwater flow and the contact between groundwater and surface water at the Forsmark site. The surface water system at Forsmark is described with the one-dimensional 'channel flow' modelling tool MIKE 11, which is fully and dynamically integrated with MIKE SHE. The MIKE SHE model was updated with data from the F2.3 data freeze. The main updates concerned the geological description of the saturated zone and the time series data on water levels and surface water discharges. The time series data used as input data and for calibration and validation was extended until the Forsmark 2.3 data freeze (March 31, 2007). The present work can be subdivided into the following four parts: 1. Update of the numerical flow model. 2. Sensitivity analysis and calibration of the model parameters. 3. Validation of the calibrated model, followed by evaluation and identification of discrepancies between measurements and model results. 4. Additional sensitivity analysis and calibration in order to resolve the problems identified in point three above. The main actions taken during the calibration can be summarised as follows: 1. The potential evapotranspiration was

  19. Hydrological Modelling and data assimilation of Satellite Snow Cover Area using a Land Surface Model, VIC

    Directory of Open Access Journals (Sweden)

    S. Naha

    2016-06-01

    Full Text Available The snow cover plays an important role in Himalayan region as it contributes a useful amount to the river discharge. So, besides estimating rainfall runoff, proper assessment of snowmelt runoff for efficient management and water resources planning is also required. A Land Surface Model, VIC (Variable Infiltration Capacity is used at a high resolution grid size of 1 km. Beas river basin up to Thalot in North West Himalayas (NWH have been selected as the study area. At first model setup is done and VIC has been run in its energy balance mode. The fluxes obtained from VIC has been routed to simulate the discharge for the time period of (2003-2006. Data Assimilation is done for the year 2006 and the techniques of Data Assimilation considered in this study are Direct Insertion (D.I and Ensemble Kalman Filter (EnKF that uses observations of snow covered area (SCA to update hydrologic model states. The meteorological forcings were taken from 0.5 deg. resolution VIC global forcing data from 1979-2006 with daily maximum temperature, minimum temperature from Climate Research unit (CRU, rainfall from daily variability of NCEP and wind speed from NCEP-NCAR analysis as main inputs and Indian Meteorological Department (IMD data of 0.25 °. NBSSLUP soil map and land use land cover map of ISRO-GBP project for year 2014 were used for generating the soil parameters and vegetation parameters respectively. The threshold temperature i.e. the minimum rain temperature is -0.5°C and maximum snow temperature is about +0.5°C at which VIC can generate snow fluxes. Hydrological simulations were done using both NCEP and IMD based meteorological Forcing datasets, but very few snow fluxes were obtained using IMD data met forcing, whereas NCEP based met forcing has given significantly better snow fluxes throughout the simulation years as the temperature resolution as given by IMD data is 0.5°C and rainfall resolution of 0.25°C. The simulated discharge has been validated

  20. Water System Adaptation To Hydrological Changes: Module 14, Life Cycle Analysis (LCA) and Prioritization Tools in Water System Adaptation

    Science.gov (United States)

    This course will introduce students to the fundamental principles of water system adaptation to hydrological changes, with emphasis on data analysis and interpretation, technical planning, and computational modeling. Starting with real-world scenarios and adaptation needs, the co...

  1. Modeling interactions of soil hydrological dynamics and soil thermal and permafrost dynamics and their effects on carbon cycling in northern high latitudes

    Science.gov (United States)

    Zhuang, Q.; Tang, J.

    2008-12-01

    Large areas of northern high latitude ecosystems are underlain with permafrost. The warming temperature and fires deteriorate the stability of those permafrost, altering hydrological cycle, and consequently soil temperature and active layer depth. These changes will determine the fate of large carbon pools in soils and permafrost over the region. We developed a modeling framework of hydrology, permafrost, and biogeochemical dynamics based on our existing modules of these components. The framework was incorporated with a new snow dynamics module and the effects of soil moisture on soil thermal properties. The framework was tested for tundra and boreal forest ecosystems at field sites with respect to soil thermal and hydrological regimes in Alaska and was then applied to the whole Alaskan ecosystems for the period of 1923-2000 at a daily time step. Our two sets of simulations with and without considering soil moisture effects indicated that the soil temperature profile and active layer depth between two simulations are significant different. The differences of soil thermal regime would expect to result in different carbon dynamics. Next, we will verify the framework with the observed data of soil moisture and soil temperature at poor-drain, moderate-drain, and well-drain boreal forest sites in Alaska. With the verified framework, we will evaluate the effects of interactions of soil thermal and hydrological dynamics on carbon dynamics for the whole northern high latitudes.

  2. Extracting Hydrologic Understanding from the Unique Space-time Sampling of the Surface Water and Ocean Topography (SWOT) Mission

    Science.gov (United States)

    Nickles, C.; Zhao, Y.; Beighley, E.; Durand, M. T.; David, C. H.; Lee, H.

    2017-12-01

    The Surface Water and Ocean Topography (SWOT) satellite mission is jointly developed by NASA, the French space agency (CNES), with participation from the Canadian and UK space agencies to serve both the hydrology and oceanography communities. The SWOT mission will sample global surface water extents and elevations (lakes/reservoirs, rivers, estuaries, oceans, sea and land ice) at a finer spatial resolution than is currently possible enabling hydrologic discovery, model advancements and new applications that are not currently possible or likely even conceivable. Although the mission will provide global cover, analysis and interpolation of the data generated from the irregular space/time sampling represents a significant challenge. In this study, we explore the applicability of the unique space/time sampling for understanding river discharge dynamics throughout the Ohio River Basin. River network topology, SWOT sampling (i.e., orbit and identified SWOT river reaches) and spatial interpolation concepts are used to quantify the fraction of effective sampling of river reaches each day of the three-year mission. Streamflow statistics for SWOT generated river discharge time series are compared to continuous daily river discharge series. Relationships are presented to transform SWOT generated streamflow statistics to equivalent continuous daily discharge time series statistics intended to support hydrologic applications using low-flow and annual flow duration statistics.

  3. Effects on surface hydrology and near-surface hydrogeology of an open repository in Laxemar Results of modelling with MIKE SHE

    International Nuclear Information System (INIS)

    Maartensson, Erik; Gustafsson, Lars-Goeran; Bosson, Emma

    2009-10-01

    the local SKB stations during the period 2004-2006. The groundwater modelling was performed with the MIKE SHE code, a process-based modelling tool that calculates the groundwater flow in three dimensions. It takes the whole hydrological cycle into consideration and describes the water flow from rainfall to river flow. The coupling to the pipe flow model MOUSE was used to implement the repository. A development of the coupling code, compared to the code used in earlier open repository modelling, was made. The repository was described as a number of pipe links in MOUSE and the inflow of water from MIKE SHE to MOUSE, i.e. the flow of water from the aquifer to the tunnels, was calculated. The shafts were described as cells with atmospheric pressure. The results from the updated MIKE SHE model for undisturbed conditions agrees with the results obtained from the SDM Laxemar model presented in the final (SDM-Site) version of the site description. The average specific runoff in the simulation for the year 2006 was calculated to 139 mm and the total evapotranspiration to 398 mm. The groundwater table in the area is rather deep; the mean depth to the groundwater table for the year 2006 was calculated to 3.7 m below ground surface (the sea area excluded). The discharge in the water courses is transient during the year and is dependent on the meteorological conditions. The impact of the open repository on the groundwater table position is extensive, which is also the case with the head change in the bedrock, and reaches the model boundary in the northern and southern parts of the model domain. The largest drawdown of the groundwater table is developed above the central parts of the repository. The calculated groundwater table drawdown and the size of the associated influence area (here defined as the area where the drawdown is larger than 0.3 m) are somewhat dependent on the level of grouting in the access tunnel and the deposition tunnels. Three levels of grouting were tested

  4. Using ATM laser altimetry to constrain surface mass balance estimates and supraglacial hydrology of the Greenland Ice Sheet

    Science.gov (United States)

    Studinger, M.; Medley, B.; Manizade, S.; Linkswiler, M. A.

    2016-12-01

    Repeat airborne laser altimetry measurements can provide large-scale field observations to better quantify spatial and temporal variability of surface processes contributing to seasonal elevation change and therefore surface mass balance. As part of NASA's Operation IceBridge the Airborne Topographic Mapper (ATM) laser altimeter measured the surface elevation of the Greenland Ice Sheet during spring (March - May) and fall (September - October) of 2015. Comparison of the two surveys reveals a general trend of thinning for outlet glaciers and for the ice sheet in a manner related to elevation and latitude. In contrast, some thickening is observed on the west (but not on the east) side of the ice divide above 2200 m elevation in the southern half, below latitude 69°N.The observed magnitude and spatial patterns of the summer melt signal can be utilized as input into ice sheet models and for validating reanalysis of regional climate models such as RACMO and MAR. We use seasonal anomalies in MERRA-2 climate fields (temperature, precipitation) to understand the observed spatial signal in seasonal change. Aside from surface elevation change, runoff from meltwater pooling in supraglacial lakes and meltwater channels accounts for at least half of the total mass loss. The ability of the ATM laser altimeters to image glacial hydrological features in 3-D and determine the depth of supraglacial lakes could be used for process studies and for quantifying melt processes over large scales. The 1-meter footprint diameter of ATM laser on the surface, together with a high shot density, allows for the production of large-scale, high-resolution, geodetic quality DEMs (50 x 50 cm) suitable for fine-scale glacial hydrology research and as input to hydrological models quantifying runoff.

  5. A model for estimating time-variant rainfall infiltration as a function of antecedent surface moisture and hydrologic soil type

    Science.gov (United States)

    Wilkening, H. A.; Ragan, R. M.

    1982-01-01

    Recent research indicates that the use of remote sensing techniques for the measurement of near surface soil moisture could be practical in the not too distant future. Other research shows that infiltration rates, especially for average or frequent rainfall events, are extremely sensitive to the proper definition and consideration of the role of the soil moisture at the beginning of the rainfall. Thus, it is important that an easy to use, but theoretically sound, rainfall infiltration model be available if the anticipated remotely sensed soil moisture data is to be optimally utilized for hydrologic simulation. A series of numerical experiments with the Richards' equation for an array of conditions anticipated in watershed hydrology were used to develop functional relationships that describe temporal infiltration rates as a function of soil type and initial moisture conditions.

  6. ENHANCED MODELING OF REMOTELY SENSED ANNUAL LAND SURFACE TEMPERATURE CYCLE

    Directory of Open Access Journals (Sweden)

    Z. Zou

    2017-09-01

    Full Text Available Satellite thermal remote sensing provides access to acquire large-scale Land surface temperature (LST data, but also generates missing and abnormal values resulting from non-clear-sky conditions. Given this limitation, Annual Temperature Cycle (ATC model was employed to reconstruct the continuous daily LST data over a year. The original model ATCO used harmonic functions, but the dramatic changes of the real LST caused by the weather changes remained unclear due to the smooth sine curve. Using Aqua/MODIS LST products, NDVI and meteorological data, we proposed enhanced model ATCE based on ATCO to describe the fluctuation and compared their performances for the Yangtze River Delta region of China. The results demonstrated that, the overall root mean square errors (RMSEs of the ATCE was lower than ATCO, and the improved accuracy of daytime was better than that of night, with the errors decreased by 0.64 K and 0.36 K, respectively. The improvements of accuracies varied with different land cover types: the forest, grassland and built-up areas improved larger than water. And the spatial heterogeneity was observed for performance of ATC model: the RMSEs of built-up area, forest and grassland were around 3.0 K in the daytime, while the water attained 2.27 K; at night, the accuracies of all types significantly increased to similar RMSEs level about 2 K. By comparing the differences between LSTs simulated by two models in different seasons, it was found that the differences were smaller in the spring and autumn, while larger in the summer and winter.

  7. Hydrological analysis relevant to surface water storage at Jabiluka. Supervising Scientist report 142

    International Nuclear Information System (INIS)

    Chiew, F.H.S.; Wang, Q.J.

    1999-01-01

    The report is prepared for the Supervising Scientist at Jabiru. It describes part of an investigation into hydrological issues relating to the water management system proposed for the Jabiluka project. Specifically, the objective is to estimate the water storage capacity required to store surface runoff and other water within the total containment zone (TCZ) of the Jabiluka project. The water storage volume is calculated for a range of probabilities up to 0.002% that the pond design volume would be exceeded over a 30-year mine life. In this study, 50 000 sets of 30 years of daily rainfall and monthly pan evaporation data are stochastically generated to simulate the storage water balance. The approach used by Kinhill and Energy Resources of Australia (ERA) is reviewed and the pond design compared with the estimates derived here. The Kinhill-ERA approach is described in the Jabiluka Mill Alternative Public Environment Report and the Jabiluka Mill Alternative Public Environment Report Technical Appendices (hereon referred to as Jabiluka PER Appendices) (1998). The two reports also provide background to many other issues. The structural design of the storage and other features of the mine site are not considered here. This study also assumes that the bunds and other drainage diversion structures will prevent all water outside the TCZ from entering the TCZ and vice versa. The storage water balance components are discussed in section 2. Some of the water inflows into the storage and losses from the storage are discussed in detail, while elsewhere, the values used by Kinhill-ERA are adopted. Section 3 describes the selection of the climate stations used here, the rainfall and pan evaporation characteristics in the area and the stochastic generation of 1.5 million years of daily rainfall and monthly pan evaporation data. Section 4 describes the approach used to estimate the storage capacity, and presents the storage capacity estimates for various probabilities of

  8. Hydrologic connectivity between geographically isolated wetlands and surface water systems: A review of select modeling methods

    Science.gov (United States)

    Heather E. Golden; Charles R. Lane; Devendra M. Amatya; Karl W. Bandilla; Hadas Raanan Kiperwas Kiperwas; Christopher D. Knightes; Herbert. Ssegane

    2014-01-01

    Geographically isolated wetlands (GIW), depressional landscape features entirely surrounded by upland areas, provide a wide range of ecological functions and ecosystem services for human well-being. Current and future ecosystem management and decision-making rely on a solid scientific understanding of how hydrologic processes affect these important GIW services and...

  9. Enhancing Global Land Surface Hydrology Estimates from the NASA MERRA Reanalysis Using Precipitation Observations and Model Parameter Adjustments

    Science.gov (United States)

    Reichle, Rolf; Koster, Randal; DeLannoy, Gabrielle; Forman, Barton; Liu, Qing; Mahanama, Sarith; Toure, Ally

    2011-01-01

    The Modern-Era Retrospective analysis for Research and Applications (MERRA) is a state-of-the-art reanalysis that provides. in addition to atmospheric fields. global estimates of soil moisture, latent heat flux. snow. and runoff for J 979-present. This study introduces a supplemental and improved set of land surface hydrological fields ('MERRA-Land') generated by replaying a revised version of the land component of the MERRA system. Specifically. the MERRA-Land estimates benefit from corrections to the precipitation forcing with the Global Precipitation Climatology Project pentad product (version 2.1) and from revised parameters in the rainfall interception model, changes that effectively correct for known limitations in the MERRA land surface meteorological forcings. The skill (defined as the correlation coefficient of the anomaly time series) in land surface hydrological fields from MERRA and MERRA-Land is assessed here against observations and compared to the skill of the state-of-the-art ERA-Interim reanalysis. MERRA-Land and ERA-Interim root zone soil moisture skills (against in situ observations at 85 US stations) are comparable and significantly greater than that of MERRA. Throughout the northern hemisphere, MERRA and MERRA-Land agree reasonably well with in situ snow depth measurements (from 583 stations) and with snow water equivalent from an independent analysis. Runoff skill (against naturalized stream flow observations from 15 basins in the western US) of MERRA and MERRA-Land is typically higher than that of ERA-Interim. With a few exceptions. the MERRA-Land data appear more accurate than the original MERRA estimates and are thus recommended for those interested in using '\\-tERRA output for land surface hydrological studies.

  10. Northern hydrology and water resources in a changing environment

    International Nuclear Information System (INIS)

    Kane, D.L.

    1993-01-01

    The role that climatic change may play in altering various components of the hydrologic cycle in Arctic regions is discussed. The hydrologic setting of these regions is first described, noting the importance of subsurface freezing and thawing on hydrologic pathways and the lack of incorporation of soil freezing and thawing into climate models. Major processes of interest in the relation between climate change and hydrology are the timing and magnitude of fluxes entering and leaving a basin: precipitation, evaporation and transpiration, and runoff. The active layer of the soil could be drastically increased by only a few degrees of surface warming. The natural hydrologic cycle has considerable yearly variation, tending to mask any hydrologic changes caused by climatic change. There are too many unknowns at present for an adequate prediction of the impact of climate change on the hydrologic cycle. The biggest uncertainty is how the timing and quantity of precipitation is going to change. This quantity could be altered by any major changes in vegetation, which would be closely related to the amount of warming. In hydrologic scenarios where air temperature rises 4 degree C over 50 y, under stable, high, and low precipitation conditions, there are no significant changes in hydrologic response. 24 refs., 6 figs

  11. Hydrology, microbiology and carbon cycling at a high Arctic polythermal glacier, (John Evans Glacier, Ellesmere Island, Canada)

    Science.gov (United States)

    Skidmore, Mark Leslie

    Analysis of the hydrology, hydrochemistry and microbiology at polythermal John Evans Glacier and geochemical and isotopic data from Haut Glacier d'Arolla demonstrates that certain subglacial chemical weathering processes are microbially mediated. Subglacial drainage is likely an annual occurrence beneath John Evans Glacier and solute rich subglacial waters indicate over winter storage at the glacier bed. Subglacial microbial populations are also present, and are viable under simulated near in situ conditions at 0.3°C. This suggests that temperate subglacial environments at a polythermal glacier, which are isolated by cold ice above and around them, provide a viable habitat for life where basal water and organic carbon are present throughout the year. Thus, a subglacial microbial ecosystem based upon legacy carbon, (from old soils or surface inputs) rather than primary production may exist, where redox processes are a key component, and seasonal anoxia may occur. The existence of anoxic environments is supported by the presence of strictly anaerobic bacteria (sulphate reducing bacteria and methanogens) in the basal sediments---which are viable in culture at 4°C---and also argues that these bacteria are not washed in with oxygenated surface meltwaters, but are present in the subglacial environment. During the summer meltseason there is a large input of surficial waters to the subglacial system and water residence times are drastically reduced. Hence, kinetic weathering processes dominate, resulting in light delta 13C-DIC (dissolved inorganic carbon) in glacial runoff, as verified by experimental work on CaCO3 and John Evans Glacier sediments. The experiments demonstrate kinetic bedrock fractionation (KBF) during carbonate hydrolysis and that kinetic fractionation of CO2 (KFC) is proportional to the rate of CO2 draw down during the carbonation of carbonates. This results in significantly depleted delta13C-DIC values (≤-16 ‰) relative to the bedrock carbonate

  12. Retrieval Assimilation and Modeling of Atmospheric Water Vapor from Ground- and Space-Based GPS Networks: Investigation of the Global and Regional Hydrological Cycles

    Science.gov (United States)

    Dickey, Jean O.

    1999-01-01

    Uncertainty over the response of the atmospheric hydrological cycle (particularly the distribution of water vapor and cloudiness) to anthropogenic forcing is a primary source of doubt in current estimates of global climate sensitivity, which raises severe difficulties in evaluating its likely societal impact. Fortunately, a variety of advanced techniques and sensors are beginning to shed new light on the atmospheric hydrological cycle. One of the most promising makes use of the sensitivity of the Global Positioning System (GPS) to the thermodynamic state, and in particular the water vapor content, of the atmosphere through which the radio signals propagate. Our strategy to derive the maximum benefit for hydrological studies from the rapidly increasing GPS data stream will proceed in three stages: (1) systematically analyze and archive quality-controlled retrievals using state-of-the-art techniques; (2) employ both currently available and innovative assimilation procedures to incorporate these determinations into advanced regional and global atmospheric models and assess their effects; and (3) apply the results to investigate selected scientific issues of relevance to regional and global hydrological studies. An archive of GPS-based estimation of total zenith delay (TZD) data and water vapor where applicable has been established with expanded automated quality control. The accuracy of the GPS estimates is being monitored; the investigation of systematic errors is ongoing using comparisons with water vapor radiometers. Meteorological packages have been implemented. The accuracy and utilization of the TZD estimates has been improved by implementing a troposphere gradient model. GPS-based gradients have been validated as real atmospheric moisture gradients, establishing a link between the estimated gradients and the passage of weather fronts. We have developed a generalized ray tracing inversion scheme that can be used to analyze occultation data acquired from space

  13. Research on Land Surface Thermal-Hydrologic Exchange in Southern China under Future Climate and Land Cover Scenarios

    Directory of Open Access Journals (Sweden)

    Jianwu Yan

    2013-01-01

    Full Text Available Climate change inevitably leads to changes in hydrothermal circulation. However, thermal-hydrologic exchanging caused by land cover change has also undergone ineligible changes. Therefore, studying the comprehensive effects of climate and land cover changes on land surface water and heat exchanges enables us to well understand the formation mechanism of regional climate and predict climate change with fewer uncertainties. This study investigated the land surface thermal-hydrologic exchange across southern China for the next 40 years using a land surface model (ecosystem-atmosphere simulation scheme (EASS. Our findings are summarized as follows. (i Spatiotemporal variation patterns of sensible heat flux (H and evapotranspiration (ET under the land cover scenarios (A2a or B2a and climate change scenario (A1B are unanimous. (ii Both H and ET take on a single peak pattern, and the peak occurs in June or July. (iii Based on the regional interannual variability analysis, H displays a downward trend (10% and ET presents an increasing trend (15%. (iv The annual average H and ET would, respectively, increase and decrease by about 10% when woodland converts to the cultivated land. Through this study, we recognize that land surface water and heat exchanges are affected greatly by the future climate change as well as land cover change.

  14. Surface contamination technology in decommissioning of nuclear fuel cycle

    International Nuclear Information System (INIS)

    Ishiguro, Hideharu

    2012-01-01

    Surface contamination measurement is the most basic technology in radiation control of the nuclear and radiation facilities. Loose surface contamination causes internal exposure through airborne contamination. Surface contamination measurement is recently more important in the waste management such as confirmation of decontamination factor, contamination survey of carried-out materials from radioactive control area, and application of clearance level. This report describes the base of surface contamination standards, meaning of contamination in decommissioning, relationship between clearance level and surface contamination, and current technology of surface contamination measurement. (author)

  15. The Hydrological Sensitivity to Global Warming and Solar Geoengineering Derived from Thermodynamic Constraints

    Energy Technology Data Exchange (ETDEWEB)

    Kleidon, Alex; Kravitz, Benjamin S.; Renner, Maik

    2015-01-16

    We derive analytic expressions of the transient response of the hydrological cycle to surface warming from an extremely simple energy balance model in which turbulent heat fluxes are constrained by the thermodynamic limit of maximum power. For a given magnitude of steady-state temperature change, this approach predicts the transient response as well as the steady-state change in surface energy partitioning and the hydrologic cycle. We show that the transient behavior of the simple model as well as the steady state hydrological sensitivities to greenhouse warming and solar geoengineering are comparable to results from simulations using highly complex models. Many of the global-scale hydrological cycle changes can be understood from a surface energy balance perspective, and our thermodynamically-constrained approach provides a physically robust way of estimating global hydrological changes in response to altered radiative forcing.

  16. Terrestrial Hydrological Data from NASA's Hydrology Data and Information Services Center (HDISC): Products, Services, and Applications

    Science.gov (United States)

    Fang, Hongliang; Beaudoing, Hiroko K.; Mocko, David M.; Rodell, Matthew; Teng, Bill; Vollmer, Bruce

    2010-01-01

    Terrestrial hydrological variables are important in global hydrology, climate, and carbon cycle studies. The North American and Global Land Data Assimilation Systems (NLDAS and GLDAS, respectively) have been generating a series of land surface states (soil moisture, snow, and temperature) and fluxes (evapotranspiration, radiation, and heat flux) variables. These data, hosted at and available from NASA s Hydrology Data and Information Services Center (HDISC), include the NLDAS hourly 1/8 degree products and the GLDAS 3-hourly 0.25 and 1.0 degree products. HDISC provides easy access and visualization and analysis capabilities for these products, thus reducing the time and resources spent by scientists on data management and facilitating hydrological research. Users can perform spatial and parameter subsetting, data format transformation, and data analysis operations without needing to first download the data. HDISC is continually being developed as a data and services portal that supports weather and climate forecasts, and water and energy cycle research.

  17. Water vapour inter-comparison effort in the framework of the hydrological cycle in the mediterranean experiment - special observation period (hymex-sop1)

    Science.gov (United States)

    Summa, Donato; Di Girolamo, Paolo; Flamant, Cyrille; De Rosa, Benedetto; Cacciani, Marco; Stelitano, Dario

    2018-04-01

    Accurate measurements of the vertical profiles of water vapour are of paramount importance for most key areas of atmospheric sciences. A comprehensive inter-comparison between different remote sensing and in-situ sensors has been carried out in the frame work of the first Special Observing Period of the Hydrological cycle in the Mediterranean Experiment for the purpose of obtaining accurate error estimates for these sensors. The inter-comparison involves a ground-based Raman lidar (BASIL), an airborne DIAL (LEANDRE2), a microwave radiometer, radiosondes and aircraft in-situ sensors.

  18. Water vapour inter-comparison effort in the framework of the hydrological cycle in the mediterranean experiment – special observation period (hymex-sop1

    Directory of Open Access Journals (Sweden)

    Summa Donato

    2018-01-01

    Full Text Available Accurate measurements of the vertical profiles of water vapour are of paramount importance for most key areas of atmospheric sciences. A comprehensive inter-comparison between different remote sensing and in-situ sensors has been carried out in the frame work of the first Special Observing Period of the Hydrological cycle in the Mediterranean Experiment for the purpose of obtaining accurate error estimates for these sensors. The inter-comparison involves a ground-based Raman lidar (BASIL, an airborne DIAL (LEANDRE2, a microwave radiometer, radiosondes and aircraft in-situ sensors.

  19. Development of an advanced eco-hydrologic and biogeochemical coupling model aimed at clarifying the missing role of inland water in the global biogeochemical cycle

    Science.gov (United States)

    Nakayama, Tadanobu

    2017-04-01

    Recent research showed that inland water including rivers, lakes, and groundwater may play some role in carbon cycling, although its contribution has remained uncertain due to limited amount of reliable data available. In this study, the author developed an advanced model coupling eco-hydrology and biogeochemical cycle (National Integrated Catchment-based Eco-hydrology (NICE)-BGC). This new model incorporates complex coupling of hydrologic-carbon cycle in terrestrial-aquatic linkages and interplay between inorganic and organic carbon during the whole process of carbon cycling. The model could simulate both horizontal transports (export from land to inland water 2.01 ± 1.98 Pg C/yr and transported to ocean 1.13 ± 0.50 Pg C/yr) and vertical fluxes (degassing 0.79 ± 0.38 Pg C/yr, and sediment storage 0.20 ± 0.09 Pg C/yr) in major rivers in good agreement with previous researches, which was an improved estimate of carbon flux from previous studies. The model results also showed global net land flux simulated by NICE-BGC (-1.05 ± 0.62 Pg C/yr) decreased carbon sink a little in comparison with revised Lund-Potsdam-Jena Wetland Hydrology and Methane (-1.79 ± 0.64 Pg C/yr) and previous materials (-2.8 to -1.4 Pg C/yr). This is attributable to CO2 evasion and lateral carbon transport explicitly included in the model, and the result suggests that most previous researches have generally overestimated the accumulation of terrestrial carbon and underestimated the potential for lateral transport. The results further implied difference between inverse techniques and budget estimates suggested can be explained to some extent by a net source from inland water. NICE-BGC would play an important role in reevaluation of greenhouse gas budget of the biosphere, quantification of hot spots, and bridging the gap between top-down and bottom-up approaches to global carbon budget.

  20. Assessing the skill of hydrology models at simulating the water cycle in the HJ Andrews LTER: Assumptions, strengths and weaknesses

    Science.gov (United States)

    Simulated impacts of climate on hydrology can vary greatly as a function of the scale of the input data, model assumptions, and model structure. Four models are commonly used to simulate streamflow in model assumptions, and model structure. Four models are commonly used to simu...

  1. LIFE CYCLE DESIGN OF IN-MOLD SURFACING FILM

    Science.gov (United States)

    Since 1990, the NRMRL has been at the forefront in the development of Life Cycle Assessment as a methodology for environmental assessment. In 1994, NRMRL established an LCA Team to organize individual efforts into a comprehensive research program. The LCA Team coordinates work in...

  2. Using isotopes to improve impact and hydrological predictions of land-surface schemes in global climate models

    International Nuclear Information System (INIS)

    McGuffie, K.; Henderson-Sellers, A.

    2002-01-01

    Global climate model (GCM) predictions of the impact of large-scale land-use change date back to 1984 as do the earliest isotopic studies of large-basin hydrology. Despite this coincidence in interest and geography, with both papers focussed on the Amazon, there have been few studies that have tried to exploit isotopic information with the goal of improving climate model simulations of the land-surface. In this paper we analyze isotopic results from the IAEA global data base specifically with the goal of identifying signatures of potential value for improving global and regional climate model simulations of the land-surface. Evaluation of climate model predictions of the impacts of deforestation of the Amazon has been shown to be of significance by recent results which indicate impacts occurring distant from the Amazon i.e. tele-connections causing climate change elsewhere around the globe. It is suggested that these could be similar in magnitude and extent to the global impacts of ENSO events. Validation of GCM predictions associated with Amazonian deforestation are increasingly urgently required because of the additional effects of other aspects of climate change, particularly synergies occurring between forest removal and greenhouse gas increases, especially CO 2 . Here we examine three decades distributions of deuterium excess across the Amazon and use the results to evaluate the relative importance of the fractionating (partial evaporation) and non-fractionating (transpiration) processes. These results illuminate GCM scenarios of importance to the regional climate and hydrology: (i) the possible impact of increased stomatal resistance in the rainforest caused by higher levels of atmospheric CO2 [4]; and (ii) the consequences of the combined effects of deforestation and global warming on the regions climate and hydrology

  3. Use of Isotopic Techniques for the Assessment of Hydrological Interactions Between Ground and Surface Waters - Rio Man, Cienaga Colombia

    Energy Technology Data Exchange (ETDEWEB)

    Palacio, P.; Dapena, C.; Betancur, T. [Universidad de Antioquia, Medellin (Colombia)

    2013-07-15

    The Man River basin is located in the lower foothills of the western and central ranges of the tropical Andes, Colombia. In this area hydrological studies and hydrochemical analyses were carried out and isotopic techniques applied to describe and understand the interactions between ground and surface waters. To expand this model and to include elements other than local hydrodynamics, relationships between regional precipitation, recharge, regional flow paths and hydraulic gradients controlling water flows from big rivers to groundwater are currently being explored. Accordingly, an isotope local meteoric water line was derived and it was discovered that the relationship between ground and surface waters is similar in wet and dry seasons. Precipitation constitutes the main recharge source, base flow is important in supporting flow in rivers, streams and wetlands, and evaporation causes effects over water systems in dry periods. A tendency towards increasing air temperatures has been detected in the Man River; this change may cause negative impacts over the hydrological system, affecting evapotranspiration- recharge processes. (author)

  4. The progress of hydrology

    Energy Technology Data Exchange (ETDEWEB)

    Chow, V T [University of Illinois, Urbana, IL (United States)

    1967-05-15

    This paper discusses mainly the challenge of hydrology, recent activities, events, and major problems in hydrology, and advances in hydrological techniques. New scientific knowledge and techniques developed in many modern scientific disciplines, and the recognition of the importance of hydrology in water-resources development enable and encourage the hydrologist to advance scientific hydrology. Many programmes to promote hydrology and to expand its attendant activities have been developed in recent years. Therefore, the activities in the United States of America, such as the Universities Council on Water Resources and the President's Water for Peace Programme, and the programmes in the International Hydrological Decade are mentioned. The most important advance in theoretical hydrology is the development of a new concept of dynamic sequential systems for the hydrological cycle, thus creating new fields of systems, parametric, and stochastic hydrology. Modern scientific instrumentation provide the hydrologist with better tools for solving his problems. The most important of these, such as electronic computers, remote sensing, and nuclear techniques are discussed. Today various major problems, both theoretical and practical, face the hydrologist. Theoretical problems concern the basic understanding of hydrological systems and the mathematical simulation and physical interpretation of hydrological phenomena. Major practical problems are numerous and diversified, but they are mostly related to the multiple-purpose development of water resources. Four central problematical subjects are discussed; namely, the effects of man on his environment, the dynamics of aqueous flow systems, hydrological transport mechanism, and groundwater hydrology. Also, the use of nuclear techniques in solving various hydrological problems is discussed. It is believed that the application of nuclear techniques would prove extremely valuable in helping solve problems, but their ultimate use in

  5. The progress of hydrology

    International Nuclear Information System (INIS)

    Chow, V.T.

    1967-01-01

    This paper discusses mainly the challenge of hydrology, recent activities, events, and major problems in hydrology, and advances in hydrological techniques. New scientific knowledge and techniques developed in many modern scientific disciplines, and the recognition of the importance of hydrology in water-resources development enable and encourage the hydrologist to advance scientific hydrology. Many programmes to promote hydrology and to expand its attendant activities have been developed in recent years. Therefore, the activities in the United States of America, such as the Universities Council on Water Resources and the President's Water for Peace Programme, and the programmes in the International Hydrological Decade are mentioned. The most important advance in theoretical hydrology is the development of a new concept of dynamic sequential systems for the hydrological cycle, thus creating new fields of systems, parametric, and stochastic hydrology. Modern scientific instrumentation provide the hydrologist with better tools for solving his problems. The most important of these, such as electronic computers, remote sensing, and nuclear techniques are discussed. Today various major problems, both theoretical and practical, face the hydrologist. Theoretical problems concern the basic understanding of hydrological systems and the mathematical simulation and physical interpretation of hydrological phenomena. Major practical problems are numerous and diversified, but they are mostly related to the multiple-purpose development of water resources. Four central problematical subjects are discussed; namely, the effects of man on his environment, the dynamics of aqueous flow systems, hydrological transport mechanism, and groundwater hydrology. Also, the use of nuclear techniques in solving various hydrological problems is discussed. It is believed that the application of nuclear techniques would prove extremely valuable in helping solve problems, but their ultimate use in

  6. Application of the HBV model for assessment of climate change impacts on the elements of hydrological cycle for the Struma River Basin

    International Nuclear Information System (INIS)

    Stanev, Krassimir

    2004-01-01

    The model used in this report is a version of the HBV model developed for the project Climate Change and Energy Production, a Nordic project aimed at evaluating the impacts of climate change on the water resources. It has a simple vegetation parametrization including interception, temperature based evapotranspiration. calculations, lake evaporation, lake routing, glacier mass balance simulation, special functions for climate change simulations etc. The HBV model, originally developed at the Swedish Meteorological and Hydrological Institute in the first half of the seventies (Bergstroem 1976) has gained widespread use for a large range of applications both in Scandinavia and beyond. It can be classified as a semi-distributed conceptual model. The version described in this report was developed for the Nordic project 'Climate change and Energy Production' (Saelthun 1996), as a synthesis of several versions used in the different Nordic countries. The main input variables are the average daily temperature, daily totals of the precipitation, the potential evapotranspiration and the daily discharges. The HBV model was applied for assessment of climate change impacts on the elements of hydrological cycle for the Struma river basin. The river Struma flows from North to South up to the Aegean Sea. Considerable part of the river basin is situated in northwest part of Bulgaria, heaving an area of more than 10 000 km 2 and average elevation about 900m asl (cross-section Marino pole). The period of 16 years (1973-1988), four precipitation and temperature stations were used for the model parameters evaluation. The achieved value of R 2 (Nash criterion) is 0.55. The climate change impact calculations (monthly values of temperatures change in o C and precipitation change in %) for two scenarios were used for the input data correction to the HBV model. The obtained results are promising and they show the potential possibility for the HBV model use to assess the climate change

  7. Surface erosion and hydrology of earth covers used in shallow land burial of low-level radioactive waste

    International Nuclear Information System (INIS)

    Bent, G.C.

    1988-01-01

    Shallow land burial is the current method of disposal of low-level radioactive waste in the United States. The most serious technical problems encountered in shallow land burial are water-related. Water is reported to come into contact with the waste by erosion of earth covers or through infiltration of precipitation through the earth covers. The objectives of this study were to: compare and evaluate the effects of crested wheatgrass and streambank wheatgrass on surface erosion of simulated earth covers at Idaho National Engineering Laboratory (INEL), characterize the surface hydrology, and estimate cumulative soil loss for average and extreme rainfall events and determine if the waste will become exposed during its burial life due to erosion. 30 refs., 26 figs., 21 tabs

  8. Near-Surface Geophysical Mapping of the Hydrological Response to an Intense Rainfall Event at the Field Scale

    Science.gov (United States)

    Martínez, G.; Vanderlinden, K.; Giraldez, J. V.; Espejo, A. J.; Muriel, J. L.

    2009-12-01

    Soil moisture plays an important role in a wide variety of biogeochemical fluxes in the soil-plant-atmosphere system and governs the (eco)hydrological response of a catchment to an external forcing such as rainfall. Near-surface electromagnetic induction (EMI) sensors that measure the soil apparent electrical conductivity (ECa) provide a fast and non-invasive means for characterizing this response at the field or catchment scale through high-resolution time-lapse mapping. Here we show how ECa maps, obtained before and after an intense rainfall event of 125 mm h-1, elucidate differences in soil moisture patterns and hydrologic response of an experimental field as a consequence of differed soil management. The dryland field (Vertisol) was located in SW Spain and cropped with a typical wheat-sunflower-legume rotation. Both, near-surface and subsurface ECa (ECas and ECad, respectively), were measured using the EM38-DD EMI sensor in a mobile configuration. Raw ECa measurements and Mean Relative Differences (MRD) provided information on soil moisture patterns while time-lapse maps were used to evaluate the hydrologic response of the field. ECa maps of the field, measured before and after the rainfall event showed similar patterns. The field depressions where most of water and sediments accumulated had the highest ECa and MRD values. The SE-oriented soil, which was deeper and more exposed to sun and wind, showed the lowest ECa and MRD. The largest differences raised in the central part of the field where a high ECa and MRD area appeared after the rainfall event as a consequence of the smaller soil depth and a possible subsurface flux concentration. Time-lapse maps of both ECa and MRD were also similar. The direct drill plots showed higher increments of ECa and MRD as a result of the smaller runoff production. Time-lapse ECa increments showed a bimodal distribution differentiating clearly the direct drill from the conventional and minimum tillage plots. However this kind

  9. Tropical sea surface temperatures and the earth's orbital eccentricity cycles

    Digital Repository Service at National Institute of Oceanography (India)

    Gupta, S.M.; Fernandes, A.A.; Mohan, R.

    The tropical oceanic warm pools are climatologically important regions because their sea surface temperatures (SSTs) are positively related to atmospheric greenhouse effect and the cumulonimbus-cirrus cloud anvil. Such a warm pool is also present...

  10. Enhancement of a parsimonious water balance model to simulate surface hydrology in a glacierized watershed

    Science.gov (United States)

    Valentin, Melissa M.; Viger, Roland J.; Van Beusekom, Ashley E.; Hay, Lauren E.; Hogue, Terri S.; Foks, Nathan Leon

    2018-01-01

    The U.S. Geological Survey monthly water balance model (MWBM) was enhanced with the capability to simulate glaciers in order to make it more suitable for simulating cold region hydrology. The new model, MWBMglacier, is demonstrated in the heavily glacierized and ecologically important Copper River watershed in Southcentral Alaska. Simulated water budget components compared well to satellite‐based observations and ground measurements of streamflow, evapotranspiration, snow extent, and total water storage, with differences ranging from 0.2% to 7% of the precipitation flux. Nash Sutcliffe efficiency for simulated and observed streamflow was greater than 0.8 for six of eight stream gages. Snow extent matched satellite‐based observations with Nash Sutcliffe efficiency values of greater than 0.89 in the four Copper River ecoregions represented. During the simulation period 1949 to 2009, glacier ice melt contributed 25% of total runoff, ranging from 12% to 45% in different tributaries, and glacierized area was reduced by 6%. Statistically significant (p < 0.05) decreasing and increasing trends in annual glacier mass balance occurred during the multidecade cool and warm phases of the Pacific Decadal Oscillation, respectively, reinforcing the link between climate perturbations and glacier mass balance change. The simulations of glaciers and total runoff for a large, remote region of Alaska provide useful data to evaluate hydrologic, cryospheric, ecologic, and climatic trends. MWBM glacier is a valuable tool to understand when, and to what extent, streamflow may increase or decrease as glaciers respond to a changing climate.

  11. Fundamentals of watershed hydrology

    Science.gov (United States)

    Pamela J. Edwards; Karl W.J. Williard; Jon E. Schoonover

    2015-01-01

    This is a primer about hydrology, the science of water. Watersheds are the basic land unit for water resource management and their delineation, importance, and variation are explained and illustrated. The hydrologic cycle and its components (precipitation, evaporation, transpiration, soil water, groundwater, and streamflow) which collectively provide a foundation for...

  12. Hands-On Hydrology

    Science.gov (United States)

    Mathews, Catherine E.; Monroe, Louise Nelson

    2004-01-01

    A professional school and university collaboration enables elementary students and their teachers to explore hydrology concepts and realize the beneficial functions of wetlands. Hands-on experiences involve young students in determining water quality at field sites after laying the groundwork with activities related to the hydrologic cycle,…

  13. [Effect of thermal cycling on surface microstructure of different light-curing composite resins].

    Science.gov (United States)

    Lv, Da; Liu, Kai-Lei; Yao, Yao; Zhang, Wei-Sheng; Liao, Chu-Hong; Jiang, Hong

    2015-04-01

    To evaluate the effect of thermal cycling on surface microstructure of different light-curing composite resins. A nanofilled composite (Z350) and 4 microhybrid composites (P60, Z250, Spectrum, and AP-X) were fabricated from lateral to center to form cubic specimens. The lateral surfaces were abrased and polished before water storage and 40 000 thermal cycles (5/55 degrees celsius;). The mean surface roughness (Ra) were measured and compared before and after thermal cycling, and the changes of microstructure were observed under scanning electron microscope (SEM). Significant decreases of Ra were observed in the composites, especially in Spectrum (from 0.164±0.024 µm to 0.140±0.017 µm, Presins, and fissures occurred on Z350 following the thermal cycling. Water storage and thermal cycling may produce polishing effect on composite resins and cause fissures on nanofilled composite resins.

  14. Analyzing the Relative Linkages of Land Use and Hydrologic Variables with Urban Surface Water Quality using Multivariate Techniques

    Science.gov (United States)

    Ahmed, S.; Abdul-Aziz, O. I.

    2015-12-01

    We used a systematic data-analytics approach to analyze and quantify relative linkages of four stream water quality indicators (total nitrogen, TN; total phosphorus, TP; chlorophyll-a, Chla; and dissolved oxygen, DO) with six land use and four hydrologic variables, along with the potential external (upstream in-land and downstream coastal) controls in highly complex coastal urban watersheds of southeast Florida, U.S.A. Multivariate pattern recognition techniques of principle component and factor analyses, in concert with Pearson correlation analysis, were applied to map interrelations and identify latent patterns of the participatory variables. Relative linkages of the in-stream water quality variables with their associated drivers were then quantified by developing dimensionless partial least squares (PLS) regression model based on standardized data. Model fitting efficiency (R2=0.71-0.87) and accuracy (ratio of root-mean-square error to the standard deviation of the observations, RSR=0.35-0.53) suggested good predictions of the water quality variables in both wet and dry seasons. Agricultural land and groundwater exhibited substantial controls on surface water quality. In-stream TN concentration appeared to be mostly contributed by the upstream water entering from Everglades in both wet and dry seasons. In contrast, watershed land uses had stronger linkages with TP and Chla than that of the watershed hydrologic and upstream (Everglades) components for both seasons. Both land use and hydrologic components showed strong linkages with DO in wet season; however, the land use linkage appeared to be less in dry season. The data-analytics method provided a comprehensive empirical framework to achieve crucial mechanistic insights into the urban stream water quality processes. Our study quantitatively identified dominant drivers of water quality, indicating key management targets to maintain healthy stream ecosystems in complex urban-natural environments near the coast.

  15. GEWEX: The Global Energy and Water Cycle Experiment

    Science.gov (United States)

    Chahine, M.; Vane, D.

    1994-01-01

    GEWEX is one of the world's largest global change research programs. Its purpose is to observe and understand the hydrological cycle and energy fluxes in the atmosphere, at land surfaces and in the upper oceans.

  16. Hydrological cycle effects on the aquatic community in a Neotropical stream of the Andean piedmont during the 2007-2010 ENSO events.

    Science.gov (United States)

    Ríos-Pulgarín, M I; Barletta, M; Mancera-Rodriguez, N J

    2016-07-01

    The seasonal and interannual changes in the fish, macroinvertebrates and phycoperiphyton assemblages of the Guarinó River were examined in relation to the physical and chemical environmental changes associated with the hydrological cycle and the El Niño-Niña/Southern Oscillation (ENSO) between 2007 and 2010. Four samplings (in dry and rainy seasons) were performed per year. Environmental variables (temperature, pH, conductivity, turbidity, oxygen, total nitrogen, orthophosphate, depth and flow rate) were measured. The temporal patterns of the taxonomic compositions for the three assemblages and the functional composition of fish and macroinvertebrate assemblages with respect to environmental variables were examined through canonical discriminant analysis, multidimensional scaling and multiple correlations. The presence and abundance of fishes, macroinvertebrates and algae species were regulated by environmental variables associated with extreme hydrological events, which derived from the natural torrential regimen of the basin and larger-scale phenomena, such as El Niño and La Niña. Fish abundance and richness were significantly correlated with algal density and pH, the macroinvertebrate density was negatively related to the flow rate and the richness was positively correlated with algal density. The algae richness was positively correlated with pH and negatively correlated with the flow rate and nitrogen. The algal density was positively correlated with pH and temperature and negatively correlated with river flow. The phycoperiphyton assemblage exhibited more direct responses in its density and richness to the hydrological changes (r(2) = 0·743 and 0·800, respectively). In functional terms, the El Niño phenomenon was defined by a greater abundance of omnivorous and insectivorous fishes, as well as filter feeders, scrapers and macroinvertebrate predators. During La Niña, a greater abundance of benthic fishes (both detritivorous and insectivorous) and

  17. The IAHR project CCHE-Climate Change impact on the Hydrological cycle, water management and Engineering: an overview and preliminary results

    Science.gov (United States)

    Ranzi, Roberto; Kojiri, T.; Mynett, A.; Barontini, S.; van de Giesen, N.; Kolokytha, E.; Ngo, L. A.; Oreamuno, R.; Renard, B.; Sighomnou, D.; Vizina, A.

    2010-05-01

    IAHR, the International Association for Hydro-Environment Engineering and Research launched a research Project called Climate Change impact on the Hydrological cycle, water management and Engineering (IAHR CCHE Project). It was motivated by the fact that, although it is now well accepted that, in the light of the recent IPCC reports the vast majority of members of the scientific community are convinced that the climate is changing or at least will experience a significant fluctuation already during the current century, it is perceived that some hydrologists, water experts and hydraulic engineers are not yet ready to incorporate climate change scenarios in their designs for such projects as: - flood protection and river training, - dam rehabilitation, - water resources management under water scarcity and changes in the hydrological regimes. The objective of the project is to encourage a close co-operation between the scientific and engineering communities in taking appropriate and timely action in response to the impact of climate change on the hydrological regime and on water resource projects. The project aims at reporting on (a) the current state of knowledge as regards the impact of projected climate change on the hydrological regime in different regions of the world, where these regions are defined not just in geographic terms but also on the basis of their level of economic and water resources development; (b) the extent to which these impacts are recognized and taken into account by national water authorities, engineering organizations and other regulating bodies in setting their standard practices and procedures for the planning, design and operation of water works. These adaptation measures will include both "hard" responses, such as the construction or enlargement of engineering structures, and "soft" responses, such as changes in legislation or the operating rules of existing structures. An overview of the project and preliminary results extracted from of

  18. Nutrients and Hydrology Indicate the Driving Mechanisms of Peatland Surface Patterning

    NARCIS (Netherlands)

    Eppinga, M.B.; Ruiter, de P.C.; Wassen, M.J.; Rietkerk, M.

    2009-01-01

    Peatland surface patterning motivates studies that identify underlying structuring mechanisms. Theoretical studies so far suggest that different mechanisms may drive similar types of patterning. The long time span associated with peatland surface pattern formation, however, limits possibilities for

  19. Land Surface Model (LSM 1.0) for Ecological, Hydrological, Atmospheric Studies

    Data.gov (United States)

    National Aeronautics and Space Administration — The NCAR LSM 1.0 is a land surface model developed to examine biogeophysical and biogeochemical land-atmosphere interactions, especially the effects of land surfaces...

  20. Coupling impervious surface rate derived from satellite remote sensing with distributed hydrological model for highly urbanized watershed flood forecasting

    Science.gov (United States)

    Dong, L.

    2017-12-01

    Abstract: The original urban surface structure changed a lot because of the rapid development of urbanization. Impermeable area has increased a lot. It causes great pressure for city flood control and drainage. Songmushan reservoir basin with high degree of urbanization is taken for an example. Pixel from Landsat is decomposed by Linear spectral mixture model and the proportion of urban area in it is considered as impervious rate. Based on impervious rate data before and after urbanization, an physically based distributed hydrological model, Liuxihe Model, is used to simulate the process of hydrology. The research shows that the performance of the flood forecasting of high urbanization area carried out with Liuxihe Model is perfect and can meet the requirement of the accuracy of city flood control and drainage. The increase of impervious area causes conflux speed more quickly and peak flow to be increased. It also makes the time of peak flow advance and the runoff coefficient increase. Key words: Liuxihe Model; Impervious rate; City flood control and drainage; Urbanization; Songmushan reservoir basin

  1. Applications of AMS to hydrology

    International Nuclear Information System (INIS)

    Bentley, H.W.; Davis, S.N.

    1981-01-01

    The evaluation and management of water as a resource requires an understanding of the chemical, and geological interactions that water effects or undergoes in the hydrologic cycle. Delivery of water to the land surface by precipitation, subsequent streamflow, circulation in surface waters and evapotranspiration, infiltration, recharge, movement of waters in the subsurface, and discharge are of interest. Also important are the quality of water, water's role in mineral dissolution, transport, and deposition, and the various water-related geotechnical problems of subsidence, tectonics, slope instability, and earth structures. Mathematical modeling techniques are available and are being improved which describe these phenomena and predict future system behavior. Typically, however, models suffer from substantial uncertainties due to insufficient data. Refinement, calibration,and verification of hydrologic models require expansion of the data base. Examination of chemical constituents of water which act as tracers can often supply the needed information. Unfortunately, few tracers are available which are both mobile and chemically stable. Several long-lived radioisotopic hydrologic tracers exist, however, which have received little attention in hydrologic studies to date because of low concentration, low specific activity, or sample size limitations. Recent development of ultra-sensitive accelerator mass spectrometry techniques (AMS) by Purser and others (1977), Nelson and others (1977), Bennett and others (1978), Muller and others (1978), Raisbeck and others (1978) is now expected to provide access to many of these tracers

  2. Effect of Autoclave Cycles on Surface Characteristics of S-File Evaluated by Scanning Electron Microscopy.

    Science.gov (United States)

    Razavian, Hamid; Iranmanesh, Pedram; Mojtahedi, Hamid; Nazeri, Rahman

    2016-01-01

    Presence of surface defects in endodontic instruments can lead to unwanted complications such as instrument fracture and incomplete preparation of the canal. The current study was conducted to evaluate the effect of autoclave cycles on surface characteristics of S-File by scanning electron microscopy (SEM). In this experimental study, 17 brand new S-Files (#30) were used. The surface characteristics of the files were examined in four steps (without autoclave, 1 autoclave cycle, 5 autoclave cycles and 10 autoclave cycles) by SEM under 200× and 1000× magnifications. Data were analyzed using the SPSS software and the paired sample t-test, independent sample t-test and multifactorial repeated measures ANOVA. The level of significance was set at 0.05. New files had debris and pitting on their surfaces. When the autoclave cycles were increased, the mean of surface roughness also increased at both magnifications (Pautoclave increased the surface roughness of the files and this had was directly related to the number of autoclave cycles.

  3. Evaluation of global continental hydrology as simulated by the Land-surface Processes and eXchanges Dynamic Global Vegetation Model

    Directory of Open Access Journals (Sweden)

    S. J. Murray

    2011-01-01

    Full Text Available Global freshwater resources are sensitive to changes in climate, land cover and population density and distribution. The Land-surface Processes and eXchanges Dynamic Global Vegetation Model is a recent development of the Lund-Potsdam-Jena model with improved representation of fire-vegetation interactions. It allows simultaneous consideration of the effects of changes in climate, CO2 concentration, natural vegetation and fire regime shifts on the continental hydrological cycle. Here the model is assessed for its ability to simulate large-scale spatial and temporal runoff patterns, in order to test its suitability for modelling future global water resources. Comparisons are made against observations of streamflow and a composite dataset of modelled and observed runoff (1986–1995 and are also evaluated against soil moisture data and the Palmer Drought Severity Index. The model captures the main features of the geographical distribution of global runoff, but tends to overestimate runoff in much of the Northern Hemisphere (where this can be somewhat accounted for by freshwater consumption and the unrealistic accumulation of the simulated winter snowpack in permafrost regions and the southern tropics. Interannual variability is represented reasonably well at the large catchment scale, as are seasonal flow timings and monthly high and low flow events. Further improvements to the simulation of intra-annual runoff might be achieved via the addition of river flow routing. Overestimates of runoff in some basins could likely be corrected by the inclusion of transmission losses and direct-channel evaporation.

  4. Cycle-to-cycle control of swing phase of paraplegic gait induced by surface electrical stimulation

    NARCIS (Netherlands)

    Franken, H.M.; Franken, H.M.; Veltink, Petrus H.; Baardman, G.; Redmeijer, R.A.; Boom, H.B.K.

    1995-01-01

    Parameterised swing phase of gait in paraplegics was obtained using surface electrical stimulation of the hip flexors, hamstrings and quadriceps; the hip flexors were stimulated to obtain a desired hip angle range, the hamstrings to provide foot clearance in the forward swing, and the quadriceps to

  5. Source and composition of surface water dissolved organic matter (DOM) and the effect of flood events on the organic matter cycling

    Science.gov (United States)

    Bondar-Kunze, Elisabeth; Welti, Nina; Tritthart, Michael; Baker, Andrew; Pinay, Gilles; Hein, Thomas

    2014-05-01

    Floodplains are often simultaneously affected by land use change, river regulation and loss of hydrological dynamics which alter the surface water connectivity between floodplain and river main channel. These alterations can have significant impacts on the sources of organic matter and their degradation and thus, the carbon cycling of riverine landscapes. Although floodplains are known to be important sources of dissolved organic matter (DOM) within watersheds, reduced hydrological connectivity impair their role. The key questions of our research were to determine i) to what extent the degree of connection between the Danube River and its floodplain controlled the DOM composition with its backwater systems, and ii) what were the effects of the DOM changes on carbon cycling in floodplains during two flood events with different magnitude? In this study we report on the variations in DOM spectrophotometric properties of surface waters in different connected floodplain areas and during two flood events of different magnitude in a section of the Alluvial Zone National Park of the Danube River downstream Vienna, Austria. Two backwater floodplain systems were studied, one backwater system mostly disconnected from the fluvial dynamics except during high flood events (Lower Lobau) and the second one, recently restored and connected even during mean flow conditions (Orth). Fluorescence excitation-emission matrix (EEM) spectrophotometry and water chemical analyses were applied to investigate the DOM dynamics. In both backwater systems 15 sites were sampled monthly for two years and every second day during a flood event.

  6. Calibration of a distributed hydrology and land surface model using energy flux measurements

    DEFF Research Database (Denmark)

    Larsen, Morten Andreas Dahl; Refsgaard, Jens Christian; Jensen, Karsten H.

    2016-01-01

    In this study we develop and test a calibration approach on a spatially distributed groundwater-surface water catchment model (MIKE SHE) coupled to a land surface model component with particular focus on the water and energy fluxes. The model is calibrated against time series of eddy flux measure...

  7. Final report of the project GICC-MedWater (march 2003/february 2006). Impacts of the climatic change on the hydrological cycle of the mediterranean basin

    International Nuclear Information System (INIS)

    Li, L.

    2006-03-01

    In the framework of the climatic change, the management of the impacts needs a precise knowledge of the change characteristics at the regional scale. The hydrological cycle is an important component of the mediterranean regional climate. The GICC-MedWater project is placed in the scope of climatic scenari regionalization and studies the characteristics of the climatic warming for the mediterranean basin. The main objective is to propose scenari of the climate evolution, for the mediterranean basin region and the impacts on the general circulation and the biology of Mediterranean Sea. It also includes a validation of the models in order to verify the the quality of the obtained scenari. (A.L.B.)

  8. Hydrophobic durability characteristics of butterfly wing surface after freezing cycles towards the design of nature inspired anti-icing surfaces.

    Directory of Open Access Journals (Sweden)

    Tingkun Chen

    Full Text Available The hydrophobicity and anti-icing performance of the surfaces of some artificial hydrophobic coatings degraded after several icing and de-icing cycles. In this paper, the frost formation on the surfaces of butterfly wings from ten different species was observed, and the contact angles were measured after 0 to 6 frosting/defrosting cycles. The results show that no obvious changes in contact angle for the butterfly wing specimens were not obvious during the frosting/defrosting process. Further, the conclusion was inferred that the topography of the butterfly wing surface forms a special space structure which has a larger space inside that can accommodate more frozen droplets; this behavior prevents destruction of the structure. The findings of this study may provide a basis and new concepts for the design of novel industrially important surfaces to inhibit frost/ice growth, such as durable anti-icing coatings, which may decrease or prevent the socio-economic loss.

  9. Hydrophobic durability characteristics of butterfly wing surface after freezing cycles towards the design of nature inspired anti-icing surfaces.

    Science.gov (United States)

    Chen, Tingkun; Cong, Qian; Qi, Yingchun; Jin, Jingfu; Choy, Kwang-Leong

    2018-01-01

    The hydrophobicity and anti-icing performance of the surfaces of some artificial hydrophobic coatings degraded after several icing and de-icing cycles. In this paper, the frost formation on the surfaces of butterfly wings from ten different species was observed, and the contact angles were measured after 0 to 6 frosting/defrosting cycles. The results show that no obvious changes in contact angle for the butterfly wing specimens were not obvious during the frosting/defrosting process. Further, the conclusion was inferred that the topography of the butterfly wing surface forms a special space structure which has a larger space inside that can accommodate more frozen droplets; this behavior prevents destruction of the structure. The findings of this study may provide a basis and new concepts for the design of novel industrially important surfaces to inhibit frost/ice growth, such as durable anti-icing coatings, which may decrease or prevent the socio-economic loss.

  10. ClimoBase: Rouse Canadian Surface Observations of Weather, Climate, and Hydrological Variables, 1984-1998

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — ClimoBase is a collection of surface climate measurements collected in Northern Canada by Dr. Wayne Rouse between 1984 and 1998 in three locations: Churchill,...

  11. The impact of the Suwannee River Sill on the surface hydrology of Okefenokee Swamp, USA

    Science.gov (United States)

    Yin, Zhi-Yong; Brook, George A.

    1992-08-01

    Okefenokee Swamp, located in southeastern Georgia and northeastern Florida, is one of the largest freshwater wetland complexes and a National Wildlife Refuge in the United States. A low earthen dam, the Suwannee River Sill, was built on the largest outlet stream of Okefenokee Swamp in the early 1960s. The purpose was to raise the water level and thus reduce fire frequency in this National Wildlife Refuge. In this study, hydrologic conditions in the swamp prior to (1937-1962) and after (1963-1986) sill construction were compared by statistical procedures. An average 9 cm increase in swamp water level at the Suwannee Canal Recreation Area was attributed to the sill. Increased precipitation and decreased evapotranspiration during the study period caused another 5 cm increase in water levels. Seasonal changes in climatic factors were also responsible for seasonal changes in water levels and streamflow in the pre- and post-sill periods. Although the effect of the sill on water level was more significant during dry periods, it is doubtful that the Suwannee River Sill actually prevented occurrence of severe fibres in the post-sill period, which was wetter than the period before sill construction. The sill diverted 2.6% of swamp outflow from the Suwannee River to the St. Mary's River. Diversion of flow was more marked during low flow periods. Therefore, the discharge of the St. Mary's River in the post-sill increased more than the discharge of the Suwannee River and its variability became lower that of the Suwannee River. The relationships between swamp water level, streamflow and precipitation were also changed due to construction of the sill.

  12. Integrated surface-subsurface water flow modelling of the Laxemar area. Application of the hydrological model ECOFLOW

    International Nuclear Information System (INIS)

    Sokrut, Nikolay; Werner, Kent; Holmen, Johan

    2007-01-01

    Since 2002, the Swedish Nuclear Fuel and Waste Management Co (SKB) performs site investigations in the Simpevarp area, for the siting of a deep geological repository for spent nuclear fuel. The site descriptive modelling includes conceptual and quantitative modelling of surface-subsurface water interactions, which are key inputs to safety assessment and environmental impact assessment. Such modelling is important also for planning of continued site investigations. In this report, the distributed hydrological model ECOFLOW is applied to the Laxemar subarea to test the ability of the model to simulate surface water and near-surface groundwater flow, and to illustrate ECOFLOW's advantages and drawbacks. The ECOFLOW model area is generally characterised by large areas of exposed or shallow bedrock. The ECOFLOW modelling results are compared to previous results produced by MIKE SHE-MIKE 11 and PCRaster-POLFLOW, in order to check whether non-calibrated surface and subsurface water flows computed by ECOFLOW are consistent with these previous results. The analyses include quantification and comparison of inflow and outflow terms of the water balance, as well as analyses of groundwater recharge-discharge patterns. ECOFLOW is used to simulate a one-year non calibrated period, considering seven catchments (including three areas with direct runoff to the sea) within the Laxemar subarea. The modelling results show the ability of the model to produce reasonable results for a model domain including both porous media (Quaternary deposits) and discontinuous media (bedrock). The results demonstrate notable differences in the specific discharge between the considered catchments, with specific discharge values in the range 157-212 mm/year; the lowest value (the Lake Frisksjoen catchment) may however be erroneous due to numerical instability in the model. Overall, these results agree with specific discharge values computed by MIKE SHE-MIKE 11 and PCRaster-POLFLOW (190 and 128-186 mm

  13. Integrated surface-subsurface water flow modelling of the Laxemar area. Application of the hydrological model ECOFLOW

    Energy Technology Data Exchange (ETDEWEB)

    Sokrut, Nikolay; Werner, Kent; Holmen, Johan [Golder Associates AB, Uppsala (Sweden)

    2007-01-15

    Since 2002, the Swedish Nuclear Fuel and Waste Management Co (SKB) performs site investigations in the Simpevarp area, for the siting of a deep geological repository for spent nuclear fuel. The site descriptive modelling includes conceptual and quantitative modelling of surface-subsurface water interactions, which are key inputs to safety assessment and environmental impact assessment. Such modelling is important also for planning of continued site investigations. In this report, the distributed hydrological model ECOFLOW is applied to the Laxemar subarea to test the ability of the model to simulate surface water and near-surface groundwater flow, and to illustrate ECOFLOW's advantages and drawbacks. The ECOFLOW model area is generally characterised by large areas of exposed or shallow bedrock. The ECOFLOW modelling results are compared to previous results produced by MIKE SHE-MIKE 11 and PCRaster-POLFLOW, in order to check whether non-calibrated surface and subsurface water flows computed by ECOFLOW are consistent with these previous results. The analyses include quantification and comparison of inflow and outflow terms of the water balance, as well as analyses of groundwater recharge-discharge patterns. ECOFLOW is used to simulate a one-year non calibrated period, considering seven catchments (including three areas with direct runoff to the sea) within the Laxemar subarea. The modelling results show the ability of the model to produce reasonable results for a model domain including both porous media (Quaternary deposits) and discontinuous media (bedrock). The results demonstrate notable differences in the specific discharge between the considered catchments, with specific discharge values in the range 157-212 mm/year; the lowest value (the Lake Frisksjoen catchment) may however be erroneous due to numerical instability in the model. Overall, these results agree with specific discharge values computed by MIKE SHE-MIKE 11 and PCRaster-POLFLOW (190 and 128

  14. On the implications of the Surface Water and Ocean Topography (SWOT) mission for hydrologic science and applications (Invited)

    Science.gov (United States)

    Lettenmaier, D. P.

    2010-12-01

    The SWOT mission will provide surface water elevation and extent information with unprecedented accuracy and spatial resolution globally. All of the implications of thedata that SWOT will produce for the hydrologic science and applications communities are not yet apparent. The SWOT data will, however, certainly offer groundbreaking opportunities for estimation of two key terms in the land surface water budget: surface water storage (in almost all water bodies with surface area exceeding about 1 km2) and derived discharge for many of the world’s large rivers (widths greater than roughly 100-250 m). Among just a few of the science questions that the observations should allow us to address are a) what are the dynamics of floods and overbank flows in large rivers? b) what is the contribution of long-term, seasonal, and interannual storage in reservoirs, lakes, and wetlands to sea level? c) what is the magnitude of surface water storage changes at seasonal to decadal time scales and continental spatial scales relative to soil moisture and groundwater? d) what will be the implications of SWOT-based estimates of reservoir storage and storage change to the management of transboundary rivers? These quite likely are among just a few of the questions that SWOT will help elucidate. Others no doubt will arise from creative analyses of SWOT data in combination with data from other missions I conclude with a discussion of mechanisms that will help foster a community to investigate these and other questions, and the implications of a SWOT data policy.

  15. Effect of Autoclave Cycles on Surface Characteristics of S-File Evaluated by Scanning Electron Microscopy

    OpenAIRE

    Razavian, Hamid; Iranmanesh, Pedram; Mojtahedi, Hamid; Nazeri, Rahman

    2015-01-01

    Introduction: Presence of surface defects in endodontic instruments can lead to unwanted complications such as instrument fracture and incomplete preparation of the canal. The current study was conducted to evaluate the effect of autoclave cycles on surface characteristics of S-File by scanning electron microscopy (SEM). Methods and Materials: In this experimental study, 17 brand new S-Files (#30) were used. The surface characteristics of the files were examined in four steps (without autocla...

  16. Hydrological Process Simulation of Inland River Watershed: A Case Study of the Heihe River Basin with Multiple Hydrological Models

    Directory of Open Access Journals (Sweden)

    Lili Wang

    2018-04-01

    Full Text Available Simulating the hydrological processes of an inland river basin can help provide the scientific guidance to the policies of water allocation among different subbasins and water resource management groups within the subbasins. However, it is difficult to simulate the hydrological processes of an inland river basin with hydrological models due to the non-consistent hydrological characteristics of the entire basin. This study presents a solution to this problem with a case study about the hydrological process simulation in an inland river basin in China, Heihe River basin. It is divided into the upper, middle, and lower reaches based on the distinctive hydrological characteristics in the Heihe River basin, and three hydrological models are selected, applied, and tested to simulate the hydrological cycling processes for each reach. The upper reach is the contributing area with the complex runoff generation processes, therefore, the hydrological informatic modeling system (HIMS is utilized due to its combined runoff generation mechanisms. The middle reach has strong impacts of intensive human activities on the interactions of surface and subsurface flows, so a conceptual water balance model is applied to simulate the water balance process. For the lower reach, as the dissipative area with groundwater dominating the hydrological process, a groundwater modeling system with the embedment of MODFLOW model is applied to simulate the groundwater dynamics. Statistical parameters and water balance analysis prove that the three models have excellent performances in simulating the hydrological process of the three reaches. Therefore, it is an effective way to simulate the hydrological process of inland river basin with multiple hydrological models according to the characteristics of each subbasin.

  17. Disappearing Arctic tundra ponds: Fine-scale analysis of surface hydrology in drained thaw lake basins over a 65 year period (1948-2013)

    Science.gov (United States)

    Andresen, Christian G.; Lougheed, Vanessa L.

    2015-03-01

    Long-term fine-scale dynamics of surface hydrology in Arctic tundra ponds (less than 1 ha) are largely unknown; however, these small water bodies may contribute substantially to carbon fluxes, energy balance, and biodiversity in the Arctic system. Change in pond area and abundance across the upper Barrow Peninsula, Alaska, was assessed by comparing historic aerial imagery (1948) and modern submeter resolution satellite imagery (2002, 2008, and 2010). This was complemented by photogrammetric analysis of low-altitude kite-borne imagery in combination with field observations (2010-2013) of pond water and thaw depth transects in seven ponds of the International Biological Program historic research site. Over 2800 ponds in 22 drained thaw lake basins (DTLB) with different geological ages were analyzed. We observed a net decrease of 30.3% in area and 17.1% in number of ponds over the 62 year period. The inclusion of field observations of pond areas in 1972 from a historic research site confirms the linear downward trend in area. Pond area and number were dependent on the age of DTLB; however, changes through time were independent of DTLB age, with potential long-term implications for the hypothesized geomorphologic landscape succession of the thaw lake cycle. These losses were coincident with increases in air temperature, active layer, and density and cover of aquatic emergent plants in ponds. Increased evaporation due to warmer and longer summers, permafrost degradation, and transpiration from encroaching aquatic emergent macrophytes are likely the factors contributing to the decline in surface area and number of ponds.

  18. Analysis of the structural parameters that influence gas production from the Devonian shale. Annual progress report, 1979-1980. Volume II. Data repository and reports published during fiscal year 1979-1980: regional structure, surface structure, surface fractures, hydrology

    Energy Technology Data Exchange (ETDEWEB)

    Negus-De Wys, J.; Dixon, J. M.; Evans, M. A.; Lee, K. D.; Ruotsala, J. E.; Wilson, T. H.; Williams, R. T.

    1980-10-01

    This volume comprises appendices giving regional structure data, surface structure data, surface fracture data, and hydrology data. The fracture data covers oriented Devonian shale cores from West Virginia, Ohio, Virginia, Pennsylvania, and Kentucky. The subsurface structure of the Eastern Kentucky gas field is also covered. (DLC)

  19. Disagreement between Hydrological and Land Surface models on the water budgets in the Arctic: why is this and which of them is right?

    Science.gov (United States)

    Blyth, E.; Martinez-de la Torre, A.; Ellis, R.; Robinson, E.

    2017-12-01

    The fresh-water budget of the Artic region has a diverse range of impacts: the ecosystems of the region, ocean circulation response to Arctic freshwater, methane emissions through changing wetland extent as well as the available fresh water for human consumption. But there are many processes that control the budget including a seasonal snow packs building and thawing, freezing soils and permafrost, extensive organic soils and large wetland systems. All these processes interact to create a complex hydrological system. In this study we examine a suite of 10 models that bring all those processes together in a 25 year reanalysis of the global water budget. We assess their performance in the Arctic region. There are two approaches to modelling fresh-water flows at large scales, referred to here as `Hydrological' and `Land Surface' models. While both approaches include a physically based model of the water stores and fluxes, the Land Surface models links the water flows to an energy-based model for processes such as snow melt and soil freezing. This study will analyse the impact of that basic difference on the regional patterns of evapotranspiration, runoff generation and terrestrial water storage. For the evapotranspiration, the Hydrological models tend to have a bigger spatial range in the model bias (difference to observations), implying greater errors compared to the Land-Surface models. For instance, some regions such as Eastern Siberia have consistently lower Evaporation in the Hydrological models than the Land Surface models. For the Runoff however, the results are the other way round with a slightly higher spatial range in bias for the Land Surface models implying greater errors than the Hydrological models. A simple analysis would suggest that Hydrological models are designed to get the runoff right, while Land Surface models designed to get the evapotranspiration right. Tracing the source of the difference suggests that the difference comes from the treatment

  20. Radioactivity in the hydrologic environment

    International Nuclear Information System (INIS)

    Werner, L.B.

    1969-01-01

    Certain proposed uses of nuclear explosives for peaceful purposes will introduce radioactive debris into the natural hydrologic environment. Consideration must therefore be given in each situation to the extent and significance to man of resulting radioactively contaminated water. For contained underground detonations, space-time - concentration predictions of radioactive materials in ground water are dependent on several factors: radionuclide production and initial distribution, radioactive decay, sorption on geologic materials, and dispersion during hydrologic transport. For uncontained (cratering) detonations, other aspects of the hydrologic cycle, particularly rainfall, and watershed characteristics must be considered. Programs sponsored principally by the U.S. Atomic Energy Commission have investigated these factors. Examination of their net effects on radioactivity concentration in water shows that areas if any, underlain by water exceeding permissible concentrations tend first to increase in size, then decrease, and finally disappear. Hydrologic processes at the surface remove or redistribute radioactive debris deposited on a watershed to other locations. Where sufficient information is available, predictions of location and concentration of radionuclides in natural waters can be made. Any potentially hazardous conditions arising from a particular detonation can then be evaluated. (author)

  1. Radioactivity in the hydrologic environment

    Energy Technology Data Exchange (ETDEWEB)

    Werner, L B [Isotopes, Inc., Palo Alto, CA (United States)

    1969-07-01

    Certain proposed uses of nuclear explosives for peaceful purposes will introduce radioactive debris into the natural hydrologic environment. Consideration must therefore be given in each situation to the extent and significance to man of resulting radioactively contaminated water. For contained underground detonations, space-time - concentration predictions of radioactive materials in ground water are dependent on several factors: radionuclide production and initial distribution, radioactive decay, sorption on geologic materials, and dispersion during hydrologic transport. For uncontained (cratering) detonations, other aspects of the hydrologic cycle, particularly rainfall, and watershed characteristics must be considered. Programs sponsored principally by the U.S. Atomic Energy Commission have investigated these factors. Examination of their net effects on radioactivity concentration in water shows that areas if any, underlain by water exceeding permissible concentrations tend first to increase in size, then decrease, and finally disappear. Hydrologic processes at the surface remove or redistribute radioactive debris deposited on a watershed to other locations. Where sufficient information is available, predictions of location and concentration of radionuclides in natural waters can be made. Any potentially hazardous conditions arising from a particular detonation can then be evaluated. (author)

  2. The influence of terracettes on surface hydrology and erosion on vegetated Alpine, mountain and steep-sloping environments

    Science.gov (United States)

    Kuhn, Nikolaus; (Phil) Greenwood, Philip

    2014-05-01

    Alpine and mountain slopes represent important pathways that link high altitude grazing areas to meadows and rangelands at lower elevations. Given the often acute gradient of mountain slopes, they represent a convenient and potentially highly efficient runoff conveyance route that facilitates the downslope transfer of fine-sediment and sediment-bound nutrients and contaminants during erosion events. Above a certain gradient, many slopes host small steps, or `terracettes`. As these are generally orientated across slope, their genesis is usually attributed to a combination of soil creep, coupled with (and often accentuated by) grazing animals. Motivated by the prevalence of these distinct landform features and lack of information on their role as runoff conveyance routes, this communication reports preliminary results from an investigation to explore the possibility that terracettes may act as preferential flow-paths, with an as yet undocumented ability to greatly influence surface hydrology in mountainous and steeply-sloping environments. A ca. 40 m2 area of vegetated terracettes and section of adjacent thalweg, with gradients ranging from approximately 25-35o, were scanned using an automated Topcon IS03 Total Station at a resolution of 0.1 * 0.1 m. Data were converted to a Digital Elevation Model (DEM) in ArcGIS 10 Geographical Information System (GIS), and queried using Spatial Analyst (Surface Hydrology; Flow Accumulation function) to identify slope-sections that could act as preferential flow-pathways during runoff events. These data were supplemented by information on soil physical properties that included grain size composition, bulk density and porosity, in order to establish spatial variations in soil characteristics associated with the vertical and horizontal terracette features. Combining the digital and in-situ data indicate that the technique is able to identify preferential surface flow-paths. Such information could greatly benefit the future management

  3. Geospatial technology applications in forest hydrology

    Science.gov (United States)

    S.S. Panda; E. Masson; S. Sen; H.W. Kim; Devendra Amatya

    2016-01-01

    Two separate disciplines, hydrology and forestry, together constitute forest hydrology. It is obvious that forestry and forest hydrology disciplines are spatial entities. Forestry is the science that seeks to understand the nature of forests throygh their life cycle and interactions with the surrounding environment. Forest hydrology includes forest soil water, streams...

  4. Quantifying groundwater dependency of riparian surface hydrologic features using the exit gradient

    Science.gov (United States)

    This study examines groundwater exit gradients as a way to quantify groundwater interactions with surface water. We calibrated high resolution groundwater models for the basin fill sediments in the lower Calapooia watershed, Oregon, using data collected between 1928--2000. The e...

  5. Influence of macroclimatic phenomena on the annual cycle of the Colombian hydrology: lineal quantification, not lineal and probabilistic percentiles

    International Nuclear Information System (INIS)

    Poveda, German; Velez, Jaime I; Mesa, Oscar; Hoyos, Carlos D; Mejia, J Freddy; Barco, Olga J; Correa, Paula L

    2002-01-01

    We study the influence of macroclimatic phenomena on the Colombian hydrology monthly, annual and interannual variability. The degree of linear dependency that exists between several indices of el Nino south oscillation (ENSO) phenomena, other phenomena such as the North Atlantic Oscillation NAO), the pacific decadal oscillation (PDO), etc., is quantified. We estimate quarterly cross-correlations between climatic variables and continuous series (over 30 years) of precipitation and run off, distributed all over Colombia. For nonlinear analysis we used the wavelets methodology. In general, we estimated positive and statistically significant simultaneous correlations of around 0.6 and 0.65 between the sol, and also for lags of one and two quarters. Correlations with the pacific decadal oscillation (PDO) indicate negative significant correlations (although smaller than - 0,5). We observed positive correlations around 0,5 between the south Atlantic temperature and trimesters JJA and SON precipitation. We estimate frequencies histograms of discharge series to quantify the impact of ENSO on the mean floods in Colombia

  6. Water EducaTion for Alabama's Black Belt (WET Alabama): Facilitating Scientific Understanding of the Hydrologic Cycle in Low-Resource Schools

    Science.gov (United States)

    Wolf, L. W.; Lee, M.; Stone, K.

    2008-12-01

    Youth, as future citizens, play an important role in obtaining and maintaining water resources. Water EducaTion for Alabama's Black Belt (WET Alabama) provides off-campus environmental and water-education activities designed to increase the appreciation, knowledge, conservation, and protection of water resources by middle-school teachers and children from predominantly African-American families in some of Alabama's poorest counties. The project is structured around a variety of indoor and outdoor activities held at two field sites, Auburn University's E. V. Smith Center in Macon County and the Robert G. Wehle Nature Center in Bullock County located in Alabama's "Black Belt" region, a region in which the prosperity of local communities is low. The educational activities provide an engaging laboratory and field experience for children from rural schools that lack scientific facilities and equipment. Both hosting centers have easy access to surface water (ponds, wetlands, streams) and offer facilities for basic hydrologic experiments (e.g., aquifer models, permeameter, water quality). The E.V. Smith site has access to groundwater through pairs of nested wells. Educational activities are designed to help students and teachers visualize groundwater flow and its interaction with surface water in an aquifer tank model; compare the hydrologic properties (porosity and permeability) of different aquifer materials (sands, gravels, and clays); learn about groundwater purging and sampling; and assess water quality and flow direction in the field. Simple exercises demonstrate (1) the balance of recharge and discharge, (2) the effects of flooding, drought and pumping, and (3) movement of contaminants through aquifers. A set of ready-to-teach laboratory exercises and tutorials address goals specified by the State of Alabama science curriculum for grades 6 to 8. The ultimate goal of Project WET Alabama is to help students and teachers from resource-poor schools become knowledgeable

  7. Data-model integration to interpret connectivity between biogeochemical cycling, and vegetation phenology and productivity in mountainous ecosystems under changing hydrologic regimes

    Science.gov (United States)

    Brodie, E.; Arora, B.; Beller, H. R.; Bill, M.; Bouskill, N.; Chakraborty, R.; Conrad, M. E.; Dafflon, B.; Enquist, B. J.; Falco, N.; Henderson, A.; Karaoz, U.; Polussa, A.; Sorensen, P.; Steltzer, H.; Wainwright, H. M.; Wang, S.; Williams, K. H.; Wilmer, C.; Wu, Y.

    2017-12-01

    In mountainous systems, snow-melt is associated with a large pulse of nutrients that originates from under-snow microbial mineralization of organic matter and microbial biomass turnover. Vegetation phenology in these systems is regulated by environmental cues such as air temperature ranges and photoperiod, such that, under typical conditions, vegetation greening and nutrient uptake occur in sync with microbial biomass turnover and nutrient release, closing nutrient cycles and enhancing nutrient retention. However, early snow-melt has been observed with increasing frequency in the mountainous west and is hypothesized to disrupt coupled plant-microbial behavior, potentially resulting in a temporal discontinuity between microbial nutrient release and vegetation greening. As part of the Watershed Function Scientific Focus Area (SFA) at Berkeley Lab we are quantifying below-ground biogeochemistry and above-ground phenology and vegetation chemistry and their relationships to hydrologic events at a lower montane hillslope in the East River catchment, Crested Butte, CO. This presentation will focus on data-model integration to interpret connectivity between biogeochemical cycling of nitrogen and vegetation nitrogen demand. Initial model results suggest that early snow-melt will result in an earlier accumulation and leaching loss of nitrate from the upper soil depths but that vegetation productivity may not decline as traits such as greater rooting depth and resource allocation to stems are favored.

  8. Safety case for the disposal of spent nuclear fuel at Olkiluoto. Surface and near-surface hydrological modelling in the biosphere assessment BSA-2012

    International Nuclear Information System (INIS)

    Karvonen, T.

    2013-05-01

    The Finnish nuclear waste disposal company, Posiva Oy, is planning an underground repository for spent nuclear fuel to be constructed on the island of Olkiluoto on the south-west coast of Finland. This study is part of the biosphere assessment (BSA-2012) within the safety case for the repository. The surface hydrological modelling described in this report is aimed at providing link between radionuclide transport in the geosphere and in the biosphere systems. The SVAT-model and Olkiluoto site scale surface hydrological model were calibrated and validated in the present day conditions using the input data provided by the Olkiluoto Monitoring Programme (OMO). During the next 10 000 years the terrain and ecosystem development is to a large extent driven by the postglacial crustal uplift. UNTAMO is a GIS toolbox developed for simulating land-uplift driven or other changes in the biosphere. All the spatial and temporal input data (excluding meteorological data) needed in the surface hydrological modelling were provided by the UNTAMO toolbox. The specific outputs given by UNTAMO toolbox are time-dependent evolution of the biosphere objects. They are continuous and sufficiently homogeneous sub-areas of the modelled area that could potentially receive radionuclides released from the repository. Possible ecosystem types for biosphere objects are coast, lake, river, forest, cropland, pasture and wetland. The primary goal of this study was to compute vertical and horizontal water fluxes in the biosphere objects. These data will be used in the biosphere radionuclide transport calculations. The method adopted here is based on calculating average vertical and horizontal fluxes for biosphere objects from the results of the full 3D-model. It was not necessary to develop any simplified hydrological model for the biosphere objects. This report includes modelling results from for the Reference Case (present day climate) and Terr M axAgri Case (maximum extent of agricultural areas and

  9. Capturing interactions between nitrogen and hydrological cycles under historical climate and land use: Susquehanna watershed analysis with the GFDL land model LM3-TAN

    Science.gov (United States)

    Lee, M.; Malyshev, S.; Shevliakova, E.; Milly, Paul C. D.; Jaffé, P. R.

    2014-01-01

    We developed a process model LM3-TAN to assess the combined effects of direct human influences and climate change on terrestrial and aquatic nitrogen (TAN) cycling. The model was developed by expanding NOAA's Geophysical Fluid Dynamics Laboratory land model LM3V-N of coupled terrestrial carbon and nitrogen (C-N) cycling and including new N cycling processes and inputs such as a soil denitrification, point N sources to streams (i.e., sewage), and stream transport and microbial processes. Because the model integrates ecological, hydrological, and biogeochemical processes, it captures key controls of the transport and fate of N in the vegetation–soil–river system in a comprehensive and consistent framework which is responsive to climatic variations and land-use changes. We applied the model at 1/8° resolution for a study of the Susquehanna River Basin. We simulated with LM3-TAN stream dissolved organic-N, ammonium-N, and nitrate-N loads throughout the river network, and we evaluated the modeled loads for 1986–2005 using data from 16 monitoring stations as well as a reported budget for the entire basin. By accounting for interannual hydrologic variability, the model was able to capture interannual variations of stream N loadings. While the model was calibrated with the stream N loads only at the last downstream Susquehanna River Basin Commission station Marietta (40°02' N, 76°32' W), it captured the N loads well at multiple locations within the basin with different climate regimes, land-use types, and associated N sources and transformations in the sub-basins. Furthermore, the calculated and previously reported N budgets agreed well at the level of the whole Susquehanna watershed. Here we illustrate how point and non-point N sources contributing to the various ecosystems are stored, lost, and exported via the river. Local analysis of six sub-basins showed combined effects of land use and climate on soil denitrification rates, with the highest rates in the

  10. POSEIDON: An integrated system for analysis and forecast of hydrological, meteorological and surface marine fields in the Mediterranean area

    Science.gov (United States)

    Speranza, A.; Accadia, C.; Casaioli, M.; Mariani, S.; Monacelli, G.; Inghilesi, R.; Tartaglione, N.; Ruti, P. M.; Carillo, A.; Bargagli, A.; Pisacane, G.; Valentinotti, F.; Lavagnini, A.

    2004-07-01

    The Mediterranean area is characterized by relevant hydrological, meteorological and marine processes developing at horizontal space-scales of the order of 1-100 km. In the recent past, several international programs have been addressed (ALPEX, POEM, MAP, etc.) to "resolving" the dynamics of such motions. Other projects (INTERREG-Flooding, MEDEX, etc.) are at present being developed with special emphasis on catastrophic events with major impact on human society that are, quite often, characterized in their manifestation by processes with the above-mentioned scales of motion. In the dynamical evolution of such events, however, equally important is the dynamics of interaction of the local (and sometimes very damaging) processes with others developing at larger scales of motion. In fact, some of the most catastrophic events in the history of Mediterranean countries are associated with dynamical processes covering all the range of space-time scales from planetary to local. The Prevision Operational System for the mEditerranean basIn and the Defence of the lagOon of veNice (POSEIDON) is an integrated system for the analysis and forecast of hydrological, meteorological, oceanic fields specifically designed and set up in order to bridge the gap between global and local scales of motion, by modeling explicitly the above referred to dynamical processes in the range of scales from Mediterranean to local. The core of POSEIDON consists of a "cascade" of numerical models that, starting from global scale numerical analysis-forecast, goes all the way to very local phenomena, like tidal propagation in Venice Lagoon. The large computational load imposed by such operational design requires necessarily parallel computing technology: the first model in the cascade is a parallelised version of BOlogna Limited Area Model (BOLAM) running on a Quadrics 128 processors computer (also known as QBOLAM). POSEIDON, developed in the context of a co-operation between the Italian Agency for New

  11. A review and evaluation of stemflow literature in the hydrologic and biogeochemical cycles of forested and agricultural ecosystems

    Science.gov (United States)

    Levia, Delphis F.; Frost, Ethan E.

    2003-04-01

    Stemflow is a spatially localized point input of precipitation and solutes at the plant stem and is of hydrological and ecological significance in forested and agricultural ecosystems. The purpose of this review is to: (1) critically evaluate our current understanding of stemflow; (2) identify gaps in our present knowledge of stemflow; and (3) stimulate further research in areas where present knowledge is weak. The review begins by analyzing stemflow drainage and nutrient inputs under diverse vegetal cover. Stemflow inputs are then examined as a function of meteorological conditions, seasonality, interspecific and intraspecific differences among and within species, canopy structure, spatiality, and atmospheric pollutants in urban environments. Stemflow modeling studies are also reviewed and evaluated. Stemflow yield and chemistry are the result of the interaction of the many complex variables listed. By analyzing each separately, it may be possible to isolate their individual affects on stemflow production and chemistry. A comprehensive understanding of each influencing factor would enable the accurate modeling of stemflow water and nutrient inputs into agricultural and forest soils which may result in the optimization of timber and crop harvests. Some areas where present knowledge is particularly weak are: (1) stemflow production and nutrient transfers in northern boreal forests (aspen, birch, conifers) and desert cacti; (2) chemical enrichment of stemflow from live trees charred by forest fires; (3) stemflow yield and nutrient inputs during the winter season; (4) intraspecific variation in stemflow production and chemistry; (5) stemflow chemistry from standing dead trees; (6) influence of canopy structure on stemflow chemistry; (7) understory stemflow generation and nutrient transfer; and (8) stemflow enrichment associated with insect infestations.

  12. Forest hydrology

    Science.gov (United States)

    Ge Sun; Devendra Amatya; Steve McNulty

    2016-01-01

    Forest hydrology studies the distribution, storage, movement, and quality of water and the hydrological processes in forest-dominated ecosystems. Forest hydrological science is regarded as the foundation of modern integrated water¬shed management. This chapter provides an overview of the history of forest hydrology and basic principles of this unique branch of...

  13. Surface area changes of Himalayan ponds as a proxy of hydrological climate-driven fluctuations

    Science.gov (United States)

    Salerno, Franco; Thakuri, Sudeep; Guyennon, Nicolas; Viviano, Gaetano; Tartari, Gianni

    2016-04-01

    The meteorological measurements at high-elevations of the Himalayan range are scarce due to the harsh conditions of these environments which limit the suitable maintenance of weather stations. As a consequence, the meager knowledge on how the climate is changed in the last decades at Himalayan high-elevations sets a serious limit upon the interpretation of relationships between causes and recent observed effects on the cryosphere. Although the glaciers masses reduction in Himalaya is currently sufficiently well described, how changes in climate drivers (precipitation and temperature) have influenced the melting and shrinkage processes are less clear. Consequently, the uncertainty related to the recent past amplifies when future forecasts are done, both for climate and impacts. In this context, a substantial body of research has already demonstrated the high sensitivity of lakes and ponds to climate. Some climate-related signals are highly visible and easily measurable in lakes. For example, climate-driven fluctuations in lake surface area have been observed in many remote sites. On interior Tibetan Plateau the lake growth since the late 1990s is mainly attributed to increased regional precipitation and weakened evaporation. Differently, other authors attribute at the observed increases of lake surfaces at the enhanced glacier melting. In our opinion these divergences found in literature are due to the type of glacial lakes considered in the study and in particular their relationship with glaciers. In general, in Himalaya three types of glacial lakes can be distinguished: (i) lakes that are not directly connected with glaciers, but that may have a glacier located in their basin (unconnected glacial lakes); (ii) supraglacial lakes, which develop on the surface of the glacier downstream; or (iii) proglacial lakes, which are moraine-dammed lakes that are in contact with the glacier front. Some of these lakes store large quantities of water and are susceptible to GLOFs

  14. The seasonal cycle of snow cover, sea ice and surface albedo

    Science.gov (United States)

    Robock, A.

    1980-01-01

    The paper examines satellite data used to construct mean snow cover caps for the Northern Hemisphere. The zonally averaged snow cover from these maps is used to calculate the seasonal cycle of zonally averaged surface albedo. The effects of meltwater on the surface, solar zenith angle, and cloudiness are parameterized and included in the calculations of snow and ice albedo. The data allows a calculation of surface albedo for any land or ocean 10 deg latitude band as a function of surface temperature ice and snow cover; the correct determination of the ice boundary is more important than the snow boundary for accurately simulating the ice and snow albedo feedback.

  15. Converting chemical energy into electricity through a functionally cooperating device with diving-surfacing cycles.

    Science.gov (United States)

    Song, Mengmeng; Cheng, Mengjiao; Ju, Guannan; Zhang, Yajun; Shi, Feng

    2014-11-05

    A smart device that can dive or surface in aqueous medium has been developed by combining a pH-responsive surface with acid-responsive magnesium. The diving-surfacing cycles can be used to convert chemical energy into electricity. During the diving-surfacing motion, the smart device cuts magnetic flux lines and produces a current, demonstrating that motional energy can be realized by consuming chemical energy of magnesium, thus producing electricity. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Gridded Surface Subsurface Hydrologic Analysis Modeling for Analysis of Flood Design Features at the Picayune Strand Restoration Project

    Science.gov (United States)

    2016-08-01

    restore its predrainage hydrology and ecological function for beneficial effects on flora and fauna in the project area and surrounding public lands. The...partnership with South Florida Water Management District (SFWMD), is constructing these features. Engineering support is required for hydrologic and...simulation accuracy and related resource requirements. Spatial data products such as digital elevation models, surveyed channel cross sections, soil

  17. Mercury cycling in agricultural and managed wetlands: a synthesis of methylmercury production, hydrologic export, and bioaccumulation from an integrated field study

    Science.gov (United States)

    Windham-Myers, Lisamarie; Fleck, Jacob A.; Ackerman, Joshua T.; Marvin-DiPasquale, Mark C.; Stricker, Craig A.; Heim, Wesley A.; Bachand, Philip A.M.; Eagles-Smith, Collin A.; Gill, Gary; Stephenson, Mark; Alpers, Charles N.

    2014-01-01

    With seasonal wetting and drying, and high biological productivity, agricultural wetlands (rice paddies) may enhance the conversion of inorganic mercury (Hg(II)) to methylmercury (MeHg), the more toxic, organic form that biomagnifies through food webs. Yet, the net balance of MeHg sources and sinks in seasonal wetland environments is poorly understood because it requires an annual, integrated assessment across biota, sediment, and water components. We examined a suite of wetlands managed for rice crops or wildlife during 2007–2008 in California's Central Valley, in an area affected by Hg contamination from historic mining practices. Hydrologic management of agricultural wetlands for rice, wild rice, or fallowed — drying for field preparation and harvest, and flooding for crop growth and post-harvest rice straw decay — led to pronounced seasonality in sediment and aqueous MeHg concentrations that were up to 95-fold higher than those measured concurrently in adjacent, non-agricultural permanently-flooded and seasonally-flooded wetlands. Flooding promoted microbial MeHg production in surface sediment of all wetlands, but extended water residence time appeared to preferentially enhance MeHg degradation and storage. When incoming MeHg loads were elevated, individual fields often served as a MeHg sink, rather than a source. Slow, horizontal flow of shallow water in the agricultural wetlands led to increased importance of vertical hydrologic fluxes, including evapoconcentration of surface water MeHg and transpiration-driven advection into the root zone, promoting temporary soil storage of MeHg. Although this hydrology limited MeHg export from wetlands, it also increased MeHg exposure to resident fish via greater in situ aqueous MeHg concentrations. Our results suggest that the combined traits of agricultural wetlands — slow-moving shallow water, manipulated flooding and drying, abundant labile plant matter, and management for wildlife — may enhance microbial

  18. Hydrogeochemistry and isotope hydrology of surface water and groundwater systems in the Ellembelle district, Ghana, West Africa

    Science.gov (United States)

    Edjah, A. K. M.; Akiti, T. T.; Osae, S.; Adotey, D.; Glover, E. T.

    2017-05-01

    An integrated approach based on the hydrogeochemistry and the isotope hydrology of surface water and groundwater was carried out in the Ellembelle district of the Western Region of Ghana. Measurement of physical parameters (pH, temperature, salinity, total dissolved solutes, total hardness and conductivity), major ions (Ca2+, Mg2+, Na+, K+, HCO3 -, Cl-, SO4 2- and NO3 -), and stable isotopes (δ2H and δ18O) in 7 rivers, 13 hand-dug wells and 18 boreholes were taken. Na+ was the dominant cation and HCO3 - was the dominant anion for both rivers and groundwater. The dominant hydrochemical facies for the rivers were Na-K-HCO3 - type while that of the groundwater (hand-dug wells and boreholes) were Na-Cl and Na-HCO3 - type. According to the Gibbs diagram, majority of the rivers fall in the evaporation-crystallization field and majority of the hand-dug wells and the boreholes fall in the rock dominance field. From the stable isotope composition measurements, all the rivers appeared to be evaporated, 60 % of the hand-dug wells and 70 % of the boreholes clustered along and in between the global meteoric water line and the local meteoric water line, suggesting an integrative and rapid recharge from meteoric origin.

  19. The geographic distribution of strontium isotopes in Danish surface waters - A base for provenance studies in archaeology, hydrology and agriculture

    International Nuclear Information System (INIS)

    Frei, Karin M.; Frei, Robert

    2011-01-01

    Research highlights: → Strontium isotope data of 192 surface waters from Denmark. → Geographic baseline distribution of bio-available fractions. → Applicable for provenance studies within archaeology, geology, agriculture and hydrology. → Proposal of a band of strontium isotope values to characterize 'local' Danish signatures. - Abstract: In this paper Sr isotope signatures are reported for 192 surface water (lakes/ponds and rivers/creeks) samples from within Denmark and an isotope distribution map is presented that may serve as a base for provenance applications, including archaeological migration studies, ground water - surface water - seawater interaction/contamination monitoring, and potentially for agricultural applications, including cases of authenticity proof for particular food products. The Sr isotopic compositions of surface waters range from 87 Sr/ 86 Sr = 0.7078 to 0.7125 (average 0.7096 ± 0.0016; 2σ). This average value lies above the range of 87 Sr/ 86 Sr values between 0.7078 and 0.7082 expected from Late Cretaceous to Early Tertiary (Oligocene) limestones which form the dominant bedrock type in a NW-SE trending belt in Denmark. The elevated 87 Sr/ 86 Sr signatures >∼0.7095 are explained by additions to the surface waters of radiogenic Sr predominantly derived from the near-surface weathering and wash-out of Quarternary glaciogenic tills and soils deposited and formed during and after the last two ice age stages (Saale and Weichsel). The Sr isotopic compositions and concentrations of the surface waters can, therefore, best be modeled by a two-component mixing involving carbonaceous bedrock and glaciogenic cover sediments as the two predominant Sr sources. A feasibility study for using Sr isotopic compositions of surface waters as a proxy for bio-available Sr signatures was conducted in a representative test area on Zealand (Land of Legends, Lejre) where there is no use and application of commercial fertilizers. It is demonstrated that

  20. Contributions to hydrological tracer methods and their application

    International Nuclear Information System (INIS)

    1982-04-01

    The activities of the Institut fuer Radiohydrometrie of the GSF are mainly devoted to the field of environmental research studying the quality, use and protection from pollution of drinking water which has become scarce in many parts of the world. The knowledge and experience of a variety of scientific disciplines are combined to the common task of developing new tracer methods and selecting suitable hydrogeological methods to allow quantitative studies of the hydrological cycle, from rainfall to surface or sub-surface run-off. The tracers used in these studies are for the most part stable, natural radioisotopes occurring in the hydrological cycle, as well as fluorescent dyes or radionuclides for water labelling. The contributions collected in this volume are grouped according to the above outline of tasks and present a survey of current methods and measurements, illustrating their efficiency in solving hydrological problems. (orig./RW) [de

  1. Daily cycle of the surface energy balance in Antarctica and the influence of clouds

    NARCIS (Netherlands)

    van den Broeke, M.R.|info:eu-repo/dai/nl/073765643; Reijmer, C.H.|info:eu-repo/dai/nl/229345956; van As, D.; Boot, W.

    2006-01-01

    We present the summertime daily cycle of the Antarctic surface energy balance (SEB) and its sensitivity to cloud cover. We use data of automatic weather stations (AWS) located in four major Antarctic climate zones: the coastal ice shelf, the coastal and interior katabatic wind zone and the interior

  2. A modeling study of the processes of surface salinity seasonal cycle in the Bay of Bengal.

    Digital Repository Service at National Institute of Oceanography (India)

    Akhil, V.P.; Durand, F.; Lengaigne, M.; Vialard, J.; Keerthi, M.G.; Gopalakrishna, V.V.; Deltel, C.; Papa, F.; Montegut, C.deB.

    of Science, Bangalore, India, 5LOS, IFREMER, Plouzan�e, France Abstract In response to the Indian Monsoon freshwater forcing, the Bay of Bengal exhibits a very strong seasonal cycle in sea surface salinity (SSS), especially near the mouths of the Ganges...

  3. Ground penetrating radar documents short-term near-surface hydrological changes around Old Faithful Geyser, Yellowstone National Park, USA

    Science.gov (United States)

    Lynne, Bridget Y.; Heasler, Henry; Jaworowski, Cheryl; Smith, Gary J.; Smith, Isaac J.; Foley, Duncan

    2018-04-01

    In April 2015, Ground Penetrating Radar (GPR) was used to characterize the shallow subsurface (images were collected between two eruptions of Old Faithful Geyser. Each set of time-sequence GPR recordings consisted of four transects aligned to provide coverage near the potential location of the inferred 15 m deep geyser chamber. However, the deepest penetration we could achieve with a 200 MHz GPR antennae was 5 m. Seven time-sequence events were collected over a 48-minute interval to image changes in the near-surface, during pre- and post-eruptive cycles. Time-sequence GPR images revealed a series of possible micro-fractures in a highly porous siliceous sinter in the near-surface that fill and drain repetitively, immediately after an eruption and during the recharge period prior to the next main eruptive event.

  4. Hydrology team

    Science.gov (United States)

    Ragan, R.

    1982-01-01

    General problems faced by hydrologists when using historical records, real time data, statistical analysis, and system simulation in providing quantitative information on the temporal and spatial distribution of water are related to the limitations of these data. Major problem areas requiring multispectral imaging-based research to improve hydrology models involve: evapotranspiration rates and soil moisture dynamics for large areas; the three dimensional characteristics of bodies of water; flooding in wetlands; snow water equivalents; runoff and sediment yield from ungaged watersheds; storm rainfall; fluorescence and polarization of water and its contained substances; discriminating between sediment and chlorophyll in water; role of barrier island dynamics in coastal zone processes; the relationship between remotely measured surface roughness and hydraulic roughness of land surfaces and stream networks; and modeling the runoff process.

  5. Estimation of subsurface hydrological parameters around Akwuke, Enugu, Nigeria using surface resistivity measurements

    International Nuclear Information System (INIS)

    Utom, Ahamefula U; Odoh, Benard I; Egboka, Boniface C E; Egboka, Nkechi E; Okeke, Harold C

    2013-01-01

    As few boreholes may be available and carrying out pumping tests can be expensive and time consuming, relationships between aquifer characteristics and the electrical parameters of different geoelectric layers exist. Data from 19 vertical electrical soundings (VESs; 13 of these selected for evaluation) was recorded with a Schlumberger electrode configuration in the area around Akwuke, Enugu, Nigeria. The data was interpreted by computer iterative modelling with curve matching for calibration purposes. Geoelectric cross-sections along a number of lines were prepared to ascertain the overall distribution of the resistivity responses of the subsurface lithology. Identified probable shallow aquifer resistivity, thickness and depth values are in the range of 28–527 Ωm, 2.1–22.5 m and 3.1–28.3 m respectively. As our aquifer system consists of fine-grained, clay–silty sand materials, a modification of the Archie equations (Waxman–Smits model) was adopted to determine the true formation factor using the relationship between the apparent formation factor and the pore water resistivity. This representation of the effects of a separate conducting path due to the presence of clay particles in the aquifer materials was used in making reliable estimations of aquifer properties. The average hydraulic conductivity of 8.96 × 10 −4 m s −1 transmissivity ranging between 1.88 × 10 −3 and 2.02 × 10 −3 m 2 s −1 estimated from surface resistivity measurements correlated well with the available field data. Results of the study also showed a direct relationship between aquifer transmissivity and modified transverse resistance (R 2 = 0.85). (paper)

  6. Low-cycle fatigue of sheet elements with ''soft'' surface layer

    International Nuclear Information System (INIS)

    Luk'yanov, V.F.; Kharchenko, V.Ya.; Berezutskij, V.I.; Ovsyannikov, V.G.

    1978-01-01

    Investigated are regularities of low-cycle fatigue of bimetallic sheet constructions made of chrome-nickel-molybdenum steel, plated with a low-alloyed steel with a reduced yield limit. Static repeated bending tests have been carried out using two-layer samples. The surface layer has been shown to increase resistance to nucleation and propagation of cracks under pulsating load if stresses are not more than 2 times higher than the yield limit. Increase in stresses leads to elastoplastic deformation and reduces durability. The positive effect of the surface layer is advisable to be used when welding-up surface defects and strengthening welded joints of high-strength steels

  7. Finding shortest non-trivial cycles in directed graphs on surfaces

    Directory of Open Access Journals (Sweden)

    Sergio Cabello

    2016-04-01

    Full Text Available Let $D$ be a weighted directed graph cellularly embedded in a surface of genus $g$, orientable or not, possibly with boundary.  We describe algorithms to compute shortest non-contractible and shortest surface non-separating cycles in $D$, generalizing previous results that dealt with undirected graphs.Our first algorithm computes such cycles in $O(n^2\\log n$ time, where $n$ is the total number of vertices and edges of $D$, thus matching the complexity of the best general algorithm in the undirected case.  It revisits and extends Thomassen's 3-path condition; the technique applies to other families of cycles as well.We also provide more efficient algorithms in special cases, such as graphs with small genus or bounded treewidth, using a divide-and-conquer technique that simplifies the graph while preserving the topological properties of its cycles.  Finally, we give an efficient output-sensitive algorithm, whose running time depends on the length of the shortest non-contractible or non-separating cycle.

  8. Surface-water hydrology and quality, and macroinvertebrate and smallmouth bass populations in four stream basins in southwestern Wisconsin, 1987-90

    Science.gov (United States)

    Graczyk, David J.; Lillie, Richard A.; Schlesser, Roger A.; Mason, John W.; Lyons, John D.; Kerr, Roger A.; Graczyk, David J.

    1993-01-01

    Data on streamflow, water quality, and macroinvertebrate and smallmouth bass (microptercus dolomieni) populations were collected from July 1987 through September 1990, in four streams in southwestern Wisconsin to determine the effect of surface-water hydrology and quality on populations of macroinvertebrates and smallmouth bass. The study was a joint project of the U.S. Geological Survey and the Wisconsin Department of Natural Resources.

  9. Determination of the appropriate use of pavement surface history in the KDOT life-cycle analysis process.

    Science.gov (United States)

    2008-09-01

    The primary objective of this study was to evaluate KDOTs pavement surfacing history and recommend : whether or not the departments life-cycle cost analysis (LCCA) procedure should include a surfacing history : component, and, if so, how the LC...

  10. Potential effects of surface coal mining on the hydrology of the Corral Creek area, Hanging Woman Creek coal field, southeastern Montana

    Science.gov (United States)

    McClymonds, N.E.

    1984-01-01

    The Corral Creek area of the Hanging Woman Creek coal field, 9 miles east of the Decker coal mines near the Tongue River, contains large reserves of Federal coal that have been identified for potential lease sale. A hydrologic study was conducted in the area to describe existing hydrologic systems and to study assess potential impacts of surface coal mining on local water resources. Hydrogeologic data collected indicate that aquifers are coal and sandstone beds within the Tongue River Member of the Fort Union Formation (Paleocene age) and sand and gravel in valley alluvium (Pleistocene and Holocene age). Surface-water resources are limited to a few spring-fed stock ponds in the higher parts of the area and the intermittent flow of Corral Creek near the mouth. Most of the stock ponds in the area become dry by midsummer. Mining of the Anderson coal bed would remove three stock wells and would lower the potentiometric surface within the coal and sandstone aquifers. The alluvial aquifer beneath Corral Creek and South Fork would be removed. Although mining would alter the existing hydrologic systems and remove several shallow wells, alternative ground-water supplies are available that could be developed to replace those lost by mining. (USGS)

  11. Spanish Network for Isotopes in Precipitation: Isotope Spatial distribution and contribution to the knowledge of the hydrological cycle

    International Nuclear Information System (INIS)

    Diaz-Teijeiro, M. F.; Rodriguez-Arevalo, J.; Castano, S.

    2009-01-01

    The results of seven years of operation of the Spanish Network for Isotopes ( 2 H, 1 8O y 3 H) in Precipitation (REVIP) are shown. this Network is managed since 2000 by the Centro de Estudios de Tecnicas Aplicadas of the Centro de Estudios y Experimentacion de Obras Publicas (CEDEX) in collaboration with the Agencia Estatal de Meteorologia (AEMET). The results of REVIP are sent to the International Atomic Energy Agency (IAEA) in order to be integrated in the Global Network for Isotopes in Precipitation (GNIP). The spatial distribution of stable isotopes ( 1 8O h 2 H) in precipitation in Spain follows a multiple regression model, based on two geographic factors: latitude and elevation, which is strongly correlated with temperature, an important factor controlling isotope fractionation. This information on 1 8O and 2 H is useful to trace surface and ground waters and, combined with the information, about the spatial and temporal distribution of the Tritium ( 3 H) concentration in precipitation, allows to date these waters in order to estimate flow directions and velocities, and to evaluate the residence time of water resources and aquifer vulnerability. (Author)

  12. Diurnal Cycles of High Resolution Land Surface Temperatures (LSTs) Determined from UAV Platforms Across a Range of Surface Types

    Science.gov (United States)

    McCabe, M.; Rosas Aguilar, J.; Parkes, S. D.; Aragon, B.

    2017-12-01

    Observation of land surface temperature (LST) has many practical uses, from studying boundary layer dynamics and land-atmosphere coupling, to investigating surface properties such as soil moisture status, heat stress and surface heat fluxes. Typically, LST is observed via satellite based sensors such as LandSat or via point measurements using IR radiometers. These measurements provide either good spatial coverage and resolution or good temporal coverage. However, neither are able to provide the needed spatial and temporal resolution for many of the research applications described above. Technological developments in the use of Unmanned Aerial Vehicles (UAVs), together with small thermal frame cameras, has enabled a capacity to overcome this spatiotemporal constraint. Utilising UAV platforms to collect LST measurements across diurnal cycles provides an opportunity to study how meteorological and surface properties vary in both space and time. Here we describe the collection of LST data from a multi-rotor UAV across a study domain that is observed multiple times throughout the day. Flights over crops of Rhodes grass and alfalfa, along with a bare desert surface, were repeated with between 8 and 11 surveys covering the period from early morning to sunset. Analysis of the collected thermal imagery shows that the constructed LST maps illustrate a strong diurnal cycle consistent with expected trends, but with considerable spatial and temporal variability observed within and between the different domains. These results offer new insights into the dynamics of land surface behavior in both dry and wet soil conditions and at spatiotemporal scales that are unable to be replicated using traditional satellite platforms.

  13. Unsteady surface pressure measurements on a slender delta wing undergoing limit cycle wing rock

    Science.gov (United States)

    Arena, Andrew S., Jr.; Nelson, Robert C.

    1991-01-01

    An experimental investigation of slender wing limit cycle motion known as wing rock was investigated using two unique experimental systems. Dynamic roll moment measurements and visualization data on the leading edge vortices were obtained using a free to roll apparatus that incorporates an airbearing spindle. In addition, both static and unsteady surface pressure data was measured on the top and bottom surfaces of the model. To obtain the unsteady surface pressure data a new computer controller drive system was developed to accurately reproduce the free to roll time history motions. The data from these experiments include, roll angle time histories, vortex trajectory data on the position of the vortices relative to the model's surface, and surface pressure measurements as a function of roll angle when the model is stationary or undergoing a wing rock motion. The roll time history data was numerically differentiated to determine the dynamic roll moment coefficient. An analysis of these data revealed that the primary mechanism for the limit cycle behavior was a time lag in the position of the vortices normal to the wing surface.

  14. Hydrology Project

    International Nuclear Information System (INIS)

    Anon.

    Research carried out in the 'Hydrology Project' of the Centro de Energia Nuclear na Agricultura', Piracicaba, Sao Paulo State, Brazil, are described. Such research comprises: Amazon hydrology and Northeast hydrology. Techniques for the measurement of isotope ratios are used. (M.A.) [pt

  15. Using the PCRaster-POLFLOW approach to GIS-based modelling of coupled groundwater-surface water hydrology in the Forsmark Area

    International Nuclear Information System (INIS)

    Jarsjoe, Jerker; Shibuo, Yoshihiro; Destouni, Georgia

    2004-09-01

    The catchment-scale hydrologic modelling approach PCRaster-POLFLOW permits the integration of environmental process modelling functions with classical GIS functions such as database maintenance and screen display. It has previously successfully been applied at relatively large river basins and catchments, such as Rhine, Elbe and Norrstroem, for modelling stream water flow and nutrient transport. In this study, we review the PCRaster-POLFLOW modelling approach and apply it using a relatively fine spatial resolution to the smaller catchment of Forsmark. As input we use data from SKB's database, which includes detailed data from Forsmark (and Simpevarp), since these locations are being investigated as part of the process to find a suitable location for a deep repository for spent nuclear fuel. We show, by comparison with independently measured, area-averaged runoff data, that the PCRaster-POLFLOW model produces results that, without using site-specific calibration, agree well with these independent measurements. In addition, we deliver results for four planned hydrological stations within the Forsmark catchment thus allowing for future direct comparisons with streamflow monitoring. We also show that, and how, the PCRaster-POLFLOW model in its present state can be used for predicting average seasonal streamflow. The present modelling exercise provided insights into possible ways of extending and using the PCRaster-POLFLOW model for applications beyond its current main focus of surface water hydrology. In particular, regarding analysis of possible surface water-groundwater interactions, we identify the Analytic Element Method for groundwater modelling together with its GIS-based pre- and post processor ArcFlow as suitable and promising for use in combination with the PCRaster-POLFLOW modelling approach. Furthermore, for transport modelling, such as that of radionuclides entering the coupled shallow groundwater-surface water hydrological system from possible deep

  16. Using the PCRaster-POLFLOW approach to GIS-based modelling of coupled groundwater-surface water hydrology in the Forsmark Area

    Energy Technology Data Exchange (ETDEWEB)

    Jarsjoe, Jerker; Shibuo, Yoshihiro; Destouni, Georgia [Stockholm Univ. (Sweden). Dept. of Physical Geography and Quaternary Geology

    2004-09-01

    The catchment-scale hydrologic modelling approach PCRaster-POLFLOW permits the integration of environmental process modelling functions with classical GIS functions such as database maintenance and screen display. It has previously successfully been applied at relatively large river basins and catchments, such as Rhine, Elbe and Norrstroem, for modelling stream water flow and nutrient transport. In this study, we review the PCRaster-POLFLOW modelling approach and apply it using a relatively fine spatial resolution to the smaller catchment of Forsmark. As input we use data from SKB's database, which includes detailed data from Forsmark (and Simpevarp), since these locations are being investigated as part of the process to find a suitable location for a deep repository for spent nuclear fuel. We show, by comparison with independently measured, area-averaged runoff data, that the PCRaster-POLFLOW model produces results that, without using site-specific calibration, agree well with these independent measurements. In addition, we deliver results for four planned hydrological stations within the Forsmark catchment thus allowing for future direct comparisons with streamflow monitoring. We also show that, and how, the PCRaster-POLFLOW model in its present state can be used for predicting average seasonal streamflow. The present modelling exercise provided insights into possible ways of extending and using the PCRaster-POLFLOW model for applications beyond its current main focus of surface water hydrology. In particular, regarding analysis of possible surface water-groundwater interactions, we identify the Analytic Element Method for groundwater modelling together with its GIS-based pre- and post processor ArcFlow as suitable and promising for use in combination with the PCRaster-POLFLOW modelling approach. Furthermore, for transport modelling, such as that of radionuclides entering the coupled shallow groundwater-surface water hydrological system from possible deep

  17. On algebraic cycles on a fibre product of families of K3-surfaces

    International Nuclear Information System (INIS)

    Nikol'skaya, Ol'ga V

    2013-01-01

    We prove the Hodge conjecture and the standard conjecture of Lefschetz type for fibre squares of smooth projective non-isotrivial families of K3-surfaces over a smooth projective curve under the assumption that the rank of the lattice of transcendental cycles on a generic geometric fibre of the family is an odd prime. We prove the Hodge conjecture for a fibre product of two non-isotrivial families of K3-surfaces (possibly with degenerations) under the condition that, for every point of the curve, at least one family has non-singular fibre over this point, and the rank of the lattice of transcendental cycles on a generic geometric fibre of one family is odd and not equal to the corresponding rank for the other.

  18. A preliminary study of the tropical water cycle and its sensitivity to surface warming

    Science.gov (United States)

    Lau, K. M.; Sui, C. H.; Tao, W. K.

    1993-01-01

    The Goddard Cumulus Ensemble Model (GCEM) has been used to demonstrate that cumulus-scale dynamics and microphysics play a major role in determining the vertical distribution of water vapor and clouds in the tropical atmosphere. The GCEM is described and is the basic structure of cumulus convection. The long-term equilibrium response to tropical convection to surface warming is examined. A picture of the water cycle within tropical cumulus clusters is developed.

  19. Surface-finish effects on the high-cycle fatigue of Alloy 718

    International Nuclear Information System (INIS)

    Korth, G.E.

    1981-06-01

    Alloy 718 us a precipitation-hardening nickel-base superalloy that is being specified for various components for liquid-meal fast breeder reactors (LMFBRs). This alloy maintains high strength at elevated temperatures making it a desirable structural material. But the property that justifies most LMFBR applications is the alloy's resistance to thermal striping damage due to its high fatigue endurance strength. Thermal striping is a high-cycle fatigue phenomenon caused by thermal stresses from the fluctuating mixing action of sodium streams of differing temperatures impinging on the metal surfaces. Most of the design data is generated from laboratory fatigue specimens with carefully controlled surface finishes prepared with a low-stress grind and buffed to a surface finish 8--12 in. Since Alloy 718 has been shown to be quite notch sensitive under cyclic loading, the detrimental effect on the high-cycle fatigue properties caused by shop surface finishes of actual components has been questioned. This report examines some of the surface finishes that could be produced in a commercial shop on an actual component

  20. The geographic distribution of strontium isotopes in Danish surface waters - A base for provenance studies in archaeology, hydrology and agriculture

    Energy Technology Data Exchange (ETDEWEB)

    Frei, Karin M., E-mail: kmfrei@hum.ku.dk [Danish National Research Foundation Centre for Textile Research, SAXO Institute, University of Copenhagen, Njalsgade 80, DK-2300 Copenhagen (Denmark); Frei, Robert [Institute of Geography and Geology and Nordic Center for Earth Evolution (NordCEE), University of Copenhagen, Oster Voldgade 10, DK-1350 Copenhagen (Denmark)

    2011-03-15

    Research highlights: {yields} Strontium isotope data of 192 surface waters from Denmark. {yields} Geographic baseline distribution of bio-available fractions. {yields} Applicable for provenance studies within archaeology, geology, agriculture and hydrology. {yields} Proposal of a band of strontium isotope values to characterize 'local' Danish signatures. - Abstract: In this paper Sr isotope signatures are reported for 192 surface water (lakes/ponds and rivers/creeks) samples from within Denmark and an isotope distribution map is presented that may serve as a base for provenance applications, including archaeological migration studies, ground water - surface water - seawater interaction/contamination monitoring, and potentially for agricultural applications, including cases of authenticity proof for particular food products. The Sr isotopic compositions of surface waters range from {sup 87}Sr/{sup 86}Sr = 0.7078 to 0.7125 (average 0.7096 {+-} 0.0016; 2{sigma}). This average value lies above the range of {sup 87}Sr/{sup 86}Sr values between 0.7078 and 0.7082 expected from Late Cretaceous to Early Tertiary (Oligocene) limestones which form the dominant bedrock type in a NW-SE trending belt in Denmark. The elevated {sup 87}Sr/{sup 86}Sr signatures >{approx}0.7095 are explained by additions to the surface waters of radiogenic Sr predominantly derived from the near-surface weathering and wash-out of Quarternary glaciogenic tills and soils deposited and formed during and after the last two ice age stages (Saale and Weichsel). The Sr isotopic compositions and concentrations of the surface waters can, therefore, best be modeled by a two-component mixing involving carbonaceous bedrock and glaciogenic cover sediments as the two predominant Sr sources. A feasibility study for using Sr isotopic compositions of surface waters as a proxy for bio-available Sr signatures was conducted in a representative test area on Zealand (Land of Legends, Lejre) where there is no use

  1. Nuclear techniques in hydrology

    International Nuclear Information System (INIS)

    Moser, H.

    1976-01-01

    The nuclear techniques used in hydrology are usually tracer techniques based on the use of nuclides either intentionally introduced into, or naturally present in the water. The low concentrations of these nuclides, which must be detected in groundwater and surface water, require special measurement techniques for the concentrations of radioactive or of stable nuclides. The nuclear techniques can be used most fruitfully in conjunction with conventional methods for the solution of problems in the areas of hydrology, hydrogeology and glacier hydrology. Nuclear techniques are used in practice in the areas of prospecting for water, environment protection and engineering hydrogeology. (orig.) [de

  2. Surface-water hydrology of the Little Black River basin, Missouri and Arkansas, before water-land improvement practices

    Science.gov (United States)

    Berkas, W.R.; Femmer, Suzanne R.; Mesko, T.O.; Thompson, B.W.

    1987-01-01

    The U. S. Department of Agriculture, Soil Conservation Service, in accordance with Public Law 566, is implementing various types of water-land improvement practices in the Little Black River basin in southeastern Missouri. These practices are designed, in part, to decrease the suspended sediment (SS) transport in the basin, decrease flood damage in the basin, and improve drainage in the agricultural area. The general features of the basin, such as geology, groundwater hydrology, soils, land use, water use, and precipitation are described; surface water quantity, quality, and suspended sediment discharge are also described. The aquifers are the Mississippi River valley alluvial aquifer, which can yield about 3,500 gal/min to properly constructed wells, and the Ozark and St. Francois aquifers, which can yield from about 30 to 500 gal/min to properly constructed wells. Soils in the area have formed in loess and cherty residuum in the uplands or have formed in alluvial sediment in the lowlands. About 93% of the estimated 3 billion gal/year of water used in the basin is for crop irrigation. The average monthly precipitation varies slightly throughout the year, with an average annual precipitation of about 47 inches. Water quality data were collected at seven stations. Specific conductance values ranged from 50 to 400 microsiemens/cm at 25 C. Water temperatures ranged from 0.0 C in the winter to 33.5 C in summer. pH values ranged from 6.4 to 8.5 units. Dissolved oxygen concentrations ranged from 2.2 to 12.8 ml/l. Total nitrogen concentrations ranged from 0.13 to 2.20 ml/l as nitrogen, with organic nitrogen as the most abundant form. Phosphorus concentrations ranged from zero to 0.29 ml/l as phosphorus. Bacterial counts were largest during storm runoff in the basin with livestock waste as the significant contributor. For the period from October 1, 1980, to September 30, 1984, the average annual SS discharge ranged from 2,230 tons/yr in the headwater areas to 27,800 tons

  3. Hydrology, Water Quality, and Surface- and Ground-Water Interactions in the Upper Hillsborough River Watershed, West-Central Florida

    Science.gov (United States)

    Trommer, J.T.; Sacks, L.A.; Kuniansky, E.L.

    2007-01-01

    A study of the Hillsborough River watershed was conducted between October 1999 through September 2003 to characterize the hydrology, water quality, and interaction between the surface and ground water in the highly karstic uppermost part of the watershed. Information such as locations of ground-water recharge and discharge, depth of the flow system interacting with the stream, and water quality in the watershed can aid in prudent water-management decisions. The upper Hillsborough River watershed covers a 220-square-mile area upstream from Hillsborough River State Park where the watershed is relatively undeveloped. The watershed contains a second order magnitude spring, many karst features, poorly drained swamps, marshes, upland flatwoods, and ridge areas. The upper Hillsborough River watershed is subdivided into two major subbasins, namely, the upper Hillsborough River subbasin, and the Blackwater Creek subbasin. The Blackwater Creek subbasin includes the Itchepackesassa Creek subbasin, which in turn includes the East Canal subbasin. The upper Hillsborough River watershed is underlain by thick sequences of carbonate rock that are covered by thin surficial deposits of unconsolidated sand and sandy clay. The clay layer is breached in many places because of the karst nature of the underlying limestone, and the highly variable degree of confinement between the Upper Floridan and surficial aquifers throughout the watershed. Potentiometric-surface maps indicate good hydraulic connection between the Upper Floridan aquifer and the Hillsborough River, and a poorer connection with Blackwater and Itchepackesassa Creeks. Similar water level elevations and fluctuations in the Upper Floridan and surficial aquifers at paired wells also indicate good hydraulic connection. Calcium was the dominant ion in ground water from all wells sampled in the watershed. Nitrate concentrations were near or below the detection limit in all except two wells that may have been affected by

  4. Closed Brayton Cycle Power Conversion Unit for Fission Surface Power Phase I Final Report

    Science.gov (United States)

    Fuller, Robert L.

    2010-01-01

    A Closed Brayton cycle power conversion system has been developed to support the NASA fission surface power program. The goal is to provide electricity from a small nuclear reactor heat source for surface power production for lunar and Mars environments. The selected media for a heat source is NaK 78 with water as a cooling source. The closed Brayton cycle power was selected to be 12 kWe output from the generator terminals. A heat source NaK temperature of 850 K plus or minus 25 K was selected. The cold source water was selected at 375 K plus or minus 25 K. A vacuum radiation environment of 200 K is specified for environmental operation. The major components of the system are the power converter, the power controller, and the top level data acquisition and control unit. The power converter with associated sensors resides in the vacuum radiation environment. The power controller and data acquisition system reside in an ambient laboratory environment. Signals and power are supplied across the pressure boundary electrically with hermetic connectors installed on the vacuum vessel. System level analyses were performed on working fluids, cycle design parameters, heater and cooling temperatures, and heat exchanger options that best meet the needs of the power converter specification. The goal is to provide a cost effective system that has high thermal-to-electric efficiency in a compact, lightweight package.

  5. Coupled land surface-subsurface hydrogeophysical inverse modeling to estimate soil organic carbon content and explore associated hydrological and thermal dynamics in the Arctic tundra

    Science.gov (United States)

    Phuong Tran, Anh; Dafflon, Baptiste; Hubbard, Susan S.

    2017-09-01

    Quantitative characterization of soil organic carbon (OC) content is essential due to its significant impacts on surface-subsurface hydrological-thermal processes and microbial decomposition of OC, which both in turn are important for predicting carbon-climate feedbacks. While such quantification is particularly important in the vulnerable organic-rich Arctic region, it is challenging to achieve due to the general limitations of conventional core sampling and analysis methods, and to the extremely dynamic nature of hydrological-thermal processes associated with annual freeze-thaw events. In this study, we develop and test an inversion scheme that can flexibly use single or multiple datasets - including soil liquid water content, temperature and electrical resistivity tomography (ERT) data - to estimate the vertical distribution of OC content. Our approach relies on the fact that OC content strongly influences soil hydrological-thermal parameters and, therefore, indirectly controls the spatiotemporal dynamics of soil liquid water content, temperature and their correlated electrical resistivity. We employ the Community Land Model to simulate nonisothermal surface-subsurface hydrological dynamics from the bedrock to the top of canopy, with consideration of land surface processes (e.g., solar radiation balance, evapotranspiration, snow accumulation and melting) and ice-liquid water phase transitions. For inversion, we combine a deterministic and an adaptive Markov chain Monte Carlo (MCMC) optimization algorithm to estimate a posteriori distributions of desired model parameters. For hydrological-thermal-to-geophysical variable transformation, the simulated subsurface temperature, liquid water content and ice content are explicitly linked to soil electrical resistivity via petrophysical and geophysical models. We validate the developed scheme using different numerical experiments and evaluate the influence of measurement errors and benefit of joint inversion on the

  6. Coupling a groundwater model with a land surface model to improve water and energy cycle simulation

    Directory of Open Access Journals (Sweden)

    W. Tian

    2012-12-01

    Full Text Available Water and energy cycles interact, making these two processes closely related. Land surface models (LSMs can describe the water and energy cycles on the land surface, but their description of the subsurface water processes is oversimplified, and lateral groundwater flow is ignored. Groundwater models (GWMs describe the dynamic movement of the subsurface water well, but they cannot depict the physical mechanisms of the evapotranspiration (ET process in detail. In this study, a coupled model of groundwater flow with a simple biosphere (GWSiB is developed based on the full coupling of a typical land surface model (SiB2 and a 3-D variably saturated groundwater model (AquiferFlow. In this coupled model, the infiltration, ET and energy transfer are simulated by SiB2 using the soil moisture results from the groundwater flow model. The infiltration and ET results are applied iteratively to drive the groundwater flow model. After the coupled model is built, a sensitivity test is first performed, and the effect of the groundwater depth and the hydraulic conductivity parameters on the ET are analyzed. The coupled model is then validated using measurements from two stations located in shallow and deep groundwater depth zones. Finally, the coupled model is applied to data from the middle reach of the Heihe River basin in the northwest of China to test the regional simulation capabilities of the model.

  7. A process-level attribution of the annual cycle of surface temperature over the Maritime Continent

    Science.gov (United States)

    Li, Yana; Yang, Song; Deng, Yi; Hu, Xiaoming; Cai, Ming

    2017-12-01

    The annual cycle of the surface temperature over the Maritime Continent (MC) is characterized by two periods of rapid warming in March-April and September-October, respectively, and a period of rapid cooling in June-July. Based upon an analysis of energy balance within individual atmosphere-surface columns, the seasonal variations of surface temperature in the MC are partitioned into partial temperature changes associated with various radiative and non-radiative (dynamical) processes. The seasonal variations in direct solar forcing and surface latent heat flux show the largest positive contributions to the annual cycle of MC surface temperature while the changes in oceanic dynamics (including ocean heat content change) work against the temperature changes related to the annual cycle. The rapid warming in March-April is mainly a result of the changes in atmospheric quick processes and ocean-atmosphere coupling such as water vapor, surface latent heat flux, clouds, and atmospheric dynamics while the contributions from direct solar forcing and oceanic dynamics are negative. This feature is in contrast to that associated with the warming in September-October, which is driven mainly by the changes in solar forcing with a certain amount of contributions from water vapor and latent heat flux change. More contribution from atmospheric quick processes and ocean-atmosphere coupling in March-April coincides with the sudden northward movement of deep convection belt, while less contribution from these quick processes and coupling is accompanied with the convection belt slowly moving southward. The main contributors to the rapid cooling in June-July are the same as those to the rapid warming in March-April, and the cooling is also negatively contributed by direct solar forcing and oceanic dynamics. The changes in water vapor in all three periods contribute positively to the change in total temperature and they are associated with the change in the location of the center of

  8. Wetland Hydrology

    Science.gov (United States)

    This chapter discusses the state of the science in wetland hydrology by touching upon the major hydraulic and hydrologic processes in these complex ecosystems, their measurement/estimation techniques, and modeling methods. It starts with the definition of wetlands, their benefit...

  9. Air-Surface-Ground Water Cycling in an Agricultural Desert Valley of Southern Colorado

    Science.gov (United States)

    Lanzoni, M.

    2017-12-01

    In dryland areas around the world, vegetation plays an important role in stabilizing soil and encouraging recharge. In the Colorado high desert of the San Luis Valley, windstorms strip away topsoil and deposit dust on the surrounding mountain snowpack. Dust-on-snow lowers albedo and hastens melting, which in turn lowers infiltration and aquifer recharge. Since the 1990s, the San Luis Valley has experienced a sharp decline in aquifer levels due to over-development of its water resources. Where agricultural abstraction is significant, the unconfined aquifer has experienced a 9 m (30 ft) drop. Over the course of three years, this dryland hydrology study analyzed rain, snow, surface and ground water across a 20,000 km2 high desert area to establish a baseline of water inputs. δ18O and δ2H were analyzed to develop a LMWL specific to this region of the southern Rockies and isotopic differences were examined in relation to chemistry to understand environmental influences on meteoric waters. This work identifies a repeating pattern of acid rainfall with trace element contaminants, including actinides.To better understand how the area's dominant vegetation responds to a lowered water table, 76 stem water samples were collected from the facultative phreatophyte shrubs E. nauseosa and S. vermiculatus over the summer, fall, spring, and summer of 2015 and 2016 from study plots chosen for increasing depths to groundwater. This research shows distinct patterns of water capture strategy and seasonal shifts among the E. nauseosa and S. vermiculatus shrubs. These differences are most apparent where groundwater is most accessible. However, where the water table has dropped 6 m (20 feet) over the last decade, both E. nauseosa and S. vermiculatus survive only on near-surface snowmelt and rain.

  10. DOC-dynamics in a small headwater catchment as driven by redox fluctuations and hydrological flow paths – are DOC exports mediated by iron reduction/oxidation cycles?

    Directory of Open Access Journals (Sweden)

    K.-H. Knorr

    2013-02-01

    Full Text Available Dissolved organic carbon (DOC exports from many catchments in Europe and North-America are steadily increasing. Several studies have sought to explain this observation. As possible causes, a decrease in acid rain or sulfate deposition, concomitant reductions in ionic strength and increasing temperatures were identified. DOC often originates from riparian wetlands; but here, despite higher DOC concentrations, ionic strength in pore waters usually exceeds that in surface waters. In the catchment under study, DOC concentrations were synchronous with dissolved iron concentrations in pore and stream water. This study aims at testing the hypothesis that DOC exports are mediated by iron reduction/oxidation cycles. Following the observed hydrographs, δ18O of water and DOC fluorescence, the wetlands were identified as the main source of DOC. Antecedent biogeochemical conditions, i.e., water table levels in the wetlands, influenced the discharge patterns of nitrate, iron and DOC during an event. The correlation of DOC with pH was positive in pore waters, but negative in surface waters; it was negative for DOC with sulfate in pore waters, but only weak in surface waters. Though, the positive correlation of DOC with iron was universal for pore and surface water. The decline of DOC and iron concentrations in transition from anoxic wetland pore water to oxic stream water suggests a flocculation of DOC with oxidising iron, leading to a drop in pH in the stream during high DOC fluxes. The pore water did not per se differ in pH. There is, thus, a need to consider processes more thoroughly of DOC mobilisation in wetlands when interpreting DOC exports from catchments. The coupling of DOC with iron fluxes suggested that increased DOC exports could at least, in part, be caused by increasing activities in iron reduction, possibly due to increases in temperature, increasing wetness of riparian wetlands, or by a shift from sulfate dominated to iron

  11. Multi-scale validation of a new soil freezing scheme for a land-surface model with physically-based hydrology

    Directory of Open Access Journals (Sweden)

    I. Gouttevin

    2012-04-01

    Full Text Available Soil freezing is a major feature of boreal regions with substantial impact on climate. The present paper describes the implementation of the thermal and hydrological effects of soil freezing in the land surface model ORCHIDEE, which includes a physical description of continental hydrology. The new soil freezing scheme is evaluated against analytical solutions and in-situ observations at a variety of scales in order to test its numerical robustness, explore its sensitivity to parameterization choices and confront its performance to field measurements at typical application scales.

    Our soil freezing model exhibits a low sensitivity to the vertical discretization for spatial steps in the range of a few millimetres to a few centimetres. It is however sensitive to the temperature interval around the freezing point where phase change occurs, which should be 1 °C to 2 °C wide. Furthermore, linear and thermodynamical parameterizations of the liquid water content lead to similar results in terms of water redistribution within the soil and thermal evolution under freezing. Our approach does not allow firm discrimination of the performance of one approach over the other.

    The new soil freezing scheme considerably improves the representation of runoff and river discharge in regions underlain by permafrost or subject to seasonal freezing. A thermodynamical parameterization of the liquid water content appears more appropriate for an integrated description of the hydrological processes at the scale of the vast Siberian basins. The use of a subgrid variability approach and the representation of wetlands could help capture the features of the Arctic hydrological regime with more accuracy.

    The modeling of the soil thermal regime is generally improved by the representation of soil freezing processes. In particular, the dynamics of the active layer is captured with more accuracy, which is of crucial importance in the prospect of

  12. Simulation of Changes in the Near-Surface Soil Freeze/Thaw Cycle Using CLM4.5 With Four Atmospheric Forcing Data Sets

    Science.gov (United States)

    Guo, Donglin; Wang, Aihui; Li, Duo; Hua, Wei

    2018-03-01

    Change in the near-surface soil freeze/thaw cycle is critical for assessments of hydrological activity, ecosystems, and climate change. Previous studies investigated the near-surface soil freeze/thaw cycle change mostly based on in situ observations and satellite monitoring. Here numerical simulation method is tested to estimate the long-term change in the near-surface soil freeze/thaw cycle in response to recent climate warming for its application to predictions. Four simulations are performed at 0.5° × 0.5° resolution from 1979 to 2009 using the Community Land Model version 4.5, each driven by one of the four atmospheric forcing data sets (i.e., one default Climate Research Unit-National Centers for Environmental Prediction [CRUNCEP] and three newly developed Modern Era Retrospective-Analysis for Research and Applications, Climate Forecast System Reanalysis, and European Centre for Medium-Range Weather Forecasts Reanalysis Interim). The observations from 299 weather stations in both Russia and China are employed to validate the simulated results. The results show that all simulations reasonably reproduce the observed variations in the ground temperature, the freeze start and end dates, and the freeze duration (the correlation coefficients range from 0.47 to 0.99, and the Nash-Sutcliffe efficiencies range from 0.19 to 0.98). Part of the simulations also exactly simulate the trends of the ground temperature, the freeze start and end dates, and the freeze duration. Of the four simulations, the results from the simulation using the CRUNCEP data set show the best overall agreement with the in situ observations, indicating that the CRUNCEP data set could be preferentially considered as the basic atmospheric forcing data set for future prediction. The simulated area-averaged annual freeze duration shortened by 8.03 days on average from 1979 to 2009, with an uncertainty (one standard deviation) of 0.67 days caused by the different atmospheric forcing data sets. These

  13. Clouds, radiation, and the diurnal cycle of sea surface temperature in the tropical Western Pacific

    Energy Technology Data Exchange (ETDEWEB)

    Webster, P.J.; Clayson, C.A.; Curry, J.A. [Univ. of Colorado, Boulder, CO (United States)

    1996-04-01

    In the tropical Western Pacific (TWP) Ocean, the clouds and the cloud-radiation feedback can only be understood in the context of air/sea interactions and the ocean mixed layer. Considerable interest has been shown in attempting to explain why sea surface temperature (SST) rarely rises above 30{degrees}C, and gradients of the SST. For the most part, observational studies that address this issue have been conducted using monthly cloud and SST data, and the focus has been on intraseasonal and interannual time scales. For the unstable tropical atmosphere, using monthly averaged data misses a key feedback between clouds and SST that occurs on the cloud-SST coupling time scale, which was estimated to be 3-6 days for the unstable tropical atmosphere. This time scale is the time needed for a change in cloud properties, due to the change of ocean surface evaporation caused by SST variation, to feed back to the SST variation, to feed back to the SST through its effect on the surface heat flux. This paper addresses the relationship between clouds, surface radiation flux and SST of the TWP ocean over the diurnal cycle.

  14. Intercomparison of the seasonal cycle of tropical surface stress in 17 AMIP atmospheric general circulation models

    Energy Technology Data Exchange (ETDEWEB)

    Saji, N.H.; Goswami, B.N. [Indian Inst. of Sci., Bangalore (India). Centre for Atmos. and Oceanic Sci.

    1997-08-01

    The mean state of the tropical atmosphere is important as the nature of the coupling between the ocean and the atmosphere depends nonlinearly on the basic state of the coupled system. The simulation of the annual cycle of the tropical surface wind stress by 17 atmospheric general circulation models (AGCMs) is examined and intercompared. The models considered were part of the atmospheric model intercomparison project (AMIP) and were integrated with observed sea surface temperature (SST) for the decade 1979-1988. Several measures have been devised to intercompare the performance of the 17 models on global tropical as well as regional scales. Within the limits of observational uncertainties, the models under examination simulate realistic tropical area-averaged zonal and meridional annual mean stresses. This is a noteworthy improvement over older generation low resolution models which were noted for their simulation of surface stresses considerably weaker than the observations. The models also simulate realistic magnitudes of the spatial distribution of the annual mean surface stress field and are seen to reproduce realistically its observed spatial pattern. Similar features are observed in the simulations of the annual variance field. The models perform well over almost all the tropical regions apart from a few. Of these, the simulations over Somali are interesting. Over this region, the models are seen to underestimate the annual mean zonal and meridional stresses. There is also wide variance between the different models in simulating these quantities. 44 refs.

  15. Model of hydrological behaviour of the anthropized semiarid wetland of Las Tablas de Daimiel National Park (Spain) based on surface water-groundwater interactions

    Science.gov (United States)

    Aguilera, H.; Castaño, S.; Moreno, L.; Jiménez-Hernández, M. E.; de la Losa, A.

    2013-05-01

    Las Tablas de Daimiel National Park (TDNP) in Spain is one of the most important semiarid wetlands of the Mediterranean area. The inversion of the regional groundwater flow, primarily due to overexploitation and inadequate aquifer management, has led to degradation. The system has turned from a groundwater discharge zone into a recharge zone, and has remained mostly dry since the 1980s. High heterogeneity and complexity, enhanced by anthropogenic management action, hampers prediction of the surface-groundwater system response to flooding events. This study analyses these interactions and provides empirical evidence to define a conceptual model of flooding-infiltration-groundwater dynamics through the application of a few simple analysis tools to basic hydrological data. Relevant surface water-groundwater interactions are mainly localized in the left (west) margin of TDNP, as confirmed by the fast responses to flooding observed in the hydrochemic, hydrodynamic and isotopic data. During drying periods, small artificial and/or low-flow natural floods are followed by infiltration of evaporated poor-quality ponding water into saline low-permeability layers. The results allow an improved understanding of the hydrological behaviour essential to support efficient management practices. The relative simplicity of the methodology allows for its application in other similar complex groundwater-linked wetlands where detailed knowledge of local geology is still absent.

  16. Virtual hydrology observatory: an immersive visualization of hydrology modeling

    Science.gov (United States)

    Su, Simon; Cruz-Neira, Carolina; Habib, Emad; Gerndt, Andreas

    2009-02-01

    The Virtual Hydrology Observatory will provide students with the ability to observe the integrated hydrology simulation with an instructional interface by using a desktop based or immersive virtual reality setup. It is the goal of the virtual hydrology observatory application to facilitate the introduction of field experience and observational skills into hydrology courses through innovative virtual techniques that mimic activities during actual field visits. The simulation part of the application is developed from the integrated atmospheric forecast model: Weather Research and Forecasting (WRF), and the hydrology model: Gridded Surface/Subsurface Hydrologic Analysis (GSSHA). Both the output from WRF and GSSHA models are then used to generate the final visualization components of the Virtual Hydrology Observatory. The various visualization data processing techniques provided by VTK are 2D Delaunay triangulation and data optimization. Once all the visualization components are generated, they are integrated into the simulation data using VRFlowVis and VR Juggler software toolkit. VR Juggler is used primarily to provide the Virtual Hydrology Observatory application with fully immersive and real time 3D interaction experience; while VRFlowVis provides the integration framework for the hydrologic simulation data, graphical objects and user interaction. A six-sided CAVETM like system is used to run the Virtual Hydrology Observatory to provide the students with a fully immersive experience.

  17. Hydrologic modeling in a marsh-mangrove ecotone: Predicting wetland surface water and salinity response to restoration in the Ten Thousand Islands region of Florida, USA

    Science.gov (United States)

    Michot, B.D.; Meselhe, E.A.; Krauss, Ken W.; Shrestha, Surendra; From, Andrew S.; Patino, Eduardo

    2017-01-01

    At the fringe of Everglades National Park in southwest Florida, United States, the Ten Thousand Islands National Wildlife Refuge (TTINWR) habitat has been heavily affected by the disruption of natural freshwater flow across the Tamiami Trail (U.S. Highway 41). As the Comprehensive Everglades Restoration Plan (CERP) proposes to restore the natural sheet flow from the Picayune Strand Restoration Project area north of the highway, the impact of planned measures on the hydrology in the refuge needs to be taken into account. The objective of this study was to develop a simple, computationally efficient mass balance model to simulate the spatial and temporal patterns of water level and salinity within the area of interest. This model could be used to assess the effects of the proposed management decisions on the surface water hydrological characteristics of the refuge. Surface water variations are critical to the maintenance of wetland processes. The model domain is divided into 10 compartments on the basis of their shared topography, vegetation, and hydrologic characteristics. A diversion of +10% of the discharge recorded during the modeling period was simulated in the primary canal draining the Picayune Strand forest north of the Tamiami Trail (Faka Union Canal) and this discharge was distributed as overland flow through the refuge area. Water depths were affected only modestly. However, in the northern part of the refuge, the hydroperiod, i.e., the duration of seasonal flooding, was increased by 21 days (from 115 to 136 days) for the simulation during the 2008 wet season, with an average water level rise of 0.06 m. The average salinity over a two-year period in the model area just south of Tamiami Trail was reduced by approximately 8 practical salinity units (psu) (from 18 to 10 psu), whereas the peak dry season average was reduced from 35 to 29 psu (by 17%). These salinity reductions were even larger with greater flow diversions (+20%). Naturally, the reduction

  18. Chemical loading into surface water along a hydrological, biogeochemical, and land use gradient: A holistic watershed approach

    Science.gov (United States)

    Barber, L.B.; Murphy, S.F.; Verplanck, P.L.; Sandstrom, M.W.; Taylor, Howard E.; Furlong, E.T.

    2006-01-01

    Identifying the sources and impacts of organic and inorganic contaminants at the watershed scale is a complex challenge because of the multitude of processes occurring in time and space. Investigation of geochemical transformations requires a systematic evaluation of hydrologic, landscape, and anthropogenic factors. The 1160 km2 Boulder Creek Watershed in the Colorado Front Range encompasses a gradient of geology, ecotypes, climate, and urbanization. Streamflow originates primarily as snowmelt and shows substantial annual variation. Water samples were collected along a 70-km transect during spring-runoff and base-flow conditions, and analyzed for major elements, trace elements, bulk organics, organic wastewater contaminants (OWCs), and pesticides. Major-element and trace-element concentrations were low in the headwaters, increased through the urban corridor, and had a step increase downstream from the first major wastewater treatment plant (WWTP). Boron, gadolinium, and lithium were useful inorganic tracers of anthropogenic inputs. Effluent from the WWTP accounted for as much as 75% of the flow in Boulder Creek and was the largest chemical input. Under both hydrological conditions, OWCs and pesticides were detected in Boulder Creek downstream from the WWTP outfall as well as in the headwater region, and loads of anthropogenic-derived contaminants increased as basin population density increased. This report documents a suite of potential endocrine-disrupting chemicals in a reach of stream with native fish populations showing indication of endocrine disruption.

  19. Hydrological Bulletin

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Historical report (December 1937-April 1948) containing hydrologic information for the United States, divided into ten regions. While hourly precipitation tables...

  20. Landfilling: Hydrology

    DEFF Research Database (Denmark)

    Kjeldsen, Peter; Beaven, R.

    2011-01-01

    Landfill hydrology deals with the presence and movement of water through a landfill. The main objective in landfill hydrology is usually to predict leachate generation, but the presence and movement of water in a landfill also affect the degradation of the waste, the leaching of pollutants...... and the geotechnical stability of the fill. Understanding landfill hydrology is thus important for many aspects of landfill, in particular siting, design and operation. The objective of this chapter is to give a basic understanding of the hydrology of landfills, and to present ways to estimate leachate quantities...... under specific circumstances. Initially a general water balance equation is defined for a typical landfill, and the different parts of the water balance are discussed. A separate section discusses water flow and the hydrogeology of landfilled wastes and considers the impact of water short...

  1. Roles of surface water areas for water and solute cycle in Hanoi city, Viet Nam

    Science.gov (United States)

    Hayashi, Takeshi; Kuroda, Keisuke; Do Thuan, An; Tran Thi Viet, Nga; Takizawa, Satoshi

    2013-04-01

    Hanoi city, the capital of Viet Nam, has developed beside the Red river. Recent rapid urbanization of this city has reduced a large number of natural water areas such as lakes, ponds and canals not only in the central area but the suburban area. Contrary, the urbanization has increased artificial water areas such as pond for fish cultivation and landscaping. On the other hand, the urbanization has induced the inflow of waste water from households and various kinds of factories to these water areas because of delay of sewerage system development. Inflow of the waste water has induced eutrophication and pollution of these water areas. Also, there is a possibility of groundwater pollution by infiltration of polluted surface water. However, the role of these water areas for water cycle and solute transport is not clarified. Therefore, this study focuses on the interaction between surface water areas and groundwater in Hanoi city to evaluate appropriate land development and groundwater resource management. We are carrying out three approaches: a) understanding of geochemical characteristics of surface water and groundwater, b) monitoring of water levels of pond and groundwater, c) sampling of soil and pond sediment. Correlation between d18O and dD of precipitation (after GNIP), the Red River (after GNIR) and the water samples of this study showed that the groundwater is composed of precipitation, the Red River and surface water that has evaporation process. Contribution of the surface water with evaporation process was widely found in the study area. As for groundwater monitoring, the Holocene aquifers at two sites were in unconfined condition in dry season and the groundwater levels in the aquifer continued to increase through rainy season. The results of isotopic analysis and groundwater level monitoring showed that the surface water areas are one of the major groundwater sources. On the other hand, concentrations of dissolved Arsenic (filtered by 0.45um) in the pore

  2. Assessment of groundwater–surface water interaction using long-term hydrochemical data and isotope hydrology: Headwaters of the Condamine River, Southeast Queensland, Australia

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, Jorge L., E-mail: jlmarti@ig.com.br [Queensland University of Technology, Brisbane (Australia); Raiber, Matthias [CSIRO Land and Water Flagship, Brisbane (Australia); Cox, Malcolm E. [Queensland University of Technology, Brisbane (Australia)

    2015-12-01

    A spatial analysis of hydrochemical data of groundwater and surface water was undertaken to identify groundwater-surface water connectivity in the headwaters of the Condamine River catchment, Southeast Queensland, Australia. An assessment of long-term hydrochemical and water level data supplemented by stable- and radioisotope measurements following a prolonged dry period dominated by baseflow, helped in determining patterns of interaction in different tributaries of the upper Condamine catchment. A conceptual hydrological model representing the major hydrochemical processes and their implications for stream-aquifer connectivity was developed and tested using multiple lines of evidence. The results of a multivariate statistical analysis highlight that there are two main regions with distinct hydrochemical facies (salinity, alkalinity, and predominant ions) in surface water. Geomorphology, geology, anthropogenic and climate influence were identified as the most relevant controlling factors of the spatial variability in water quality. Stable isotope data confirmed a clear evaporation trend in almost all surface water samples during baseflow conditions. Two water types can be identified and separated by the degree of evaporation and the proximity of one group to the local meteoric water line. The results confirm the discharge of groundwater from aquifers recharged by rainfall and located upstream of the surface water sampling sites. Overall, {sup 222}Rn data show a trend of increased activity in surface water towards the upstream portions of these tributaries, validating the use of this tracer to estimate groundwater input to the local creeks. The proportion of groundwater contribution to stream flow calculated by {sup 222}Rn and chloride mass balance is in agreement, and ranges between 20–70% in tributaries in the northern areas, and between 8–50% in the upper reaches of the main river channel. This study shows the efficacy of an integrated approach combining long

  3. Assessment of groundwater–surface water interaction using long-term hydrochemical data and isotope hydrology: Headwaters of the Condamine River, Southeast Queensland, Australia

    International Nuclear Information System (INIS)

    Martinez, Jorge L.; Raiber, Matthias; Cox, Malcolm E.

    2015-01-01

    A spatial analysis of hydrochemical data of groundwater and surface water was undertaken to identify groundwater-surface water connectivity in the headwaters of the Condamine River catchment, Southeast Queensland, Australia. An assessment of long-term hydrochemical and water level data supplemented by stable- and radioisotope measurements following a prolonged dry period dominated by baseflow, helped in determining patterns of interaction in different tributaries of the upper Condamine catchment. A conceptual hydrological model representing the major hydrochemical processes and their implications for stream-aquifer connectivity was developed and tested using multiple lines of evidence. The results of a multivariate statistical analysis highlight that there are two main regions with distinct hydrochemical facies (salinity, alkalinity, and predominant ions) in surface water. Geomorphology, geology, anthropogenic and climate influence were identified as the most relevant controlling factors of the spatial variability in water quality. Stable isotope data confirmed a clear evaporation trend in almost all surface water samples during baseflow conditions. Two water types can be identified and separated by the degree of evaporation and the proximity of one group to the local meteoric water line. The results confirm the discharge of groundwater from aquifers recharged by rainfall and located upstream of the surface water sampling sites. Overall, 222 Rn data show a trend of increased activity in surface water towards the upstream portions of these tributaries, validating the use of this tracer to estimate groundwater input to the local creeks. The proportion of groundwater contribution to stream flow calculated by 222 Rn and chloride mass balance is in agreement, and ranges between 20–70% in tributaries in the northern areas, and between 8–50% in the upper reaches of the main river channel. This study shows the efficacy of an integrated approach combining long

  4. Hydrologic Cycle Response to the Paleocene-Eocene Thermal Maximum at Austral, High-Latitude Site 690 as Revealed by In Situ Measurements of Foraminiferal Oxygen Isotope and Mg/Ca Ratios

    Science.gov (United States)

    Kozdon, R.; Kelly, D.; Fournelle, J.; Valley, J. W.

    2012-12-01

    Earth surface temperatures warmed by ~5°C during an ancient (~55.5 Ma) global warming event termed the Paleocene-Eocene thermal maximum (PETM). This transient (~200 ka) "hyperthermal" climate state had profound consequences for the planet's surficial processes and biosphere, and is widely touted as being an ancient analog for climate change driven by human activities. Hallmarks of the PETM are pervasive carbonate dissolution in the ocean basins and a negative carbon isotope excursion (CIE) recorded in variety of substrates including soil and marine carbonates. Together these lines of evidence signal the rapid (≤30 ka) release of massive quantities (≥2000 Gt) of 13C-depleted carbon into the exogenic carbon cycle. Paleoenvironmental reconstructions based on pedogenic features in paleosols, clay mineralogy and sedimentology of coastal and continental deposits, and land-plant communities indicate that PETM warmth was accompanied by a major perturbation to the hydrologic cycle. Micropaleontological evidence and n-alkane hydrogen isotope records indicate that increased poleward moisture transport reduced sea-surface salinities (SSSs) in the central Arctic Ocean during the PETM. Such findings are broadly consistent with predictions of climate model simulations. Here we reassess a well-studied PETM record from the Southern Ocean (ODP Site 690) in light of new δ18O and Mg/Ca data obtained from planktic foraminiferal shells by secondary ion mass spectrometry (SIMS) and electron microprobe analysis (EMPA), respectively. The unparalleled spatial resolution of these in situ techniques permits extraction of more reliable δ18O and Mg/Ca data by targeting of minute (≤10 μm spots), biogenic domains within individual planktic foraminifera that retain the original shell chemistry (Kozdon et al. 2011, Paleocean.). In general, the stratigraphic profile and magnitude of the δ18O decrease (~2.2‰) delimiting PETM warming in our SIMS-generated record are similar to those of

  5. Terrestrial N Cycling And C Storage: Some Insights From A Process-based Land Surface Model

    Science.gov (United States)

    Zaehle, S.; Friend, A. D.; Friedlingstein, P.

    2008-12-01

    We present results of a new land surface model, O-CN, which includes a process-based coupling between the terrestrial cycling of energy, water, carbon, and nitrogen. The model represents the controls of the terrestrial nitrogen (N) cycling on carbon (C) pools and fluxes through photosynthesis, respiration, changes in allocation, and soil organic matter decomposition, and explicitly accounts for N leaching and gaseous losses. O-CN has been shown to give realistic results in comparison to observations at a wide range of scales, including in situ flux measurements, productivity databases, and atmospheric CO2 concentration data. O-CN is run for three free air carbon dioxide enrichment (FACE) sites (Duke, Oak Ridge, Aspen), and reproduces observed magnitudes of changes in net primary productivity, foliage area and foliage N content. Several alternative hypotheses concerning the control of N on vegetation growth and decomposition, including effects of diluting foliage N concentrations, down-regulation of photosynthesis and respiration, acclimation of C allocation patterns and biological N fixation, are tested with respect to their effect on long- term C sequestration estimate. Differences in initial N availability, small transient changes in N inputs and the assumed plasticity of C:N stoichiometry can lead to substantial differences in the simulated long-term changes in productivity and C sequestration. We discuss the capacity of observations obtained at FACE sites to evaluate these alternative hypotheses, and investigate implications of a transient versus instantaneous increase in atmospheric carbon dioxide for the magnitude of the simulated limiting effect of N on C cycling. Finally, we re-examine earlier model-based assessments of the terrestrial C sequestration potential using a global transient O-CN simulation driven by increases in atmospheric CO2, N deposition and climatic changes over the 21st century.

  6. Hydrology and soil erosion

    Science.gov (United States)

    Leonard J. Lane; Mary R. Kidwell

    2003-01-01

    We review research on surface water hydrology and soil erosion at the Santa Rita Experimental Range (SRER). Almost all of the research was associated with eight small experimental watersheds established from 1974 to 1975 and operated until the present. Analysis of climatic features of the SRER supports extending research findings from the SRER to broad areas of the...

  7. Potassium Rankine cycle power conversion systems for lunar-Mars surface power

    International Nuclear Information System (INIS)

    Holcomb, R.S.

    1992-01-01

    The potassium Rankine cycle has good potential for application to nuclear power systems for surface power on the moon and Mars. A substantial effort on the development of the power conversion system was carried out in the 1960's which demonstrated successful operation of components made of stainless steel at moderate temperatures. This technology could be applied in the near term to produce a 360 kW(e) power system by coupling a stainless steel power conversion system to the SP-100 reactor. Improved performance could be realized in later systems by utilizing niobium or tantalum refractory metal alloys in the reactor and power conversion system. The design characteristics and estimated mass of power systems for each of three technology levels are presented in the paper

  8. Mercury cycling in surface water, pore water and sediments of Mugu Lagoon, CA, USA

    Energy Technology Data Exchange (ETDEWEB)

    Rothenberg, Sarah E. [Environmental Science and Engineering Program, Box 951772, University of California, Los Angeles, CA 90095-1772 (United States)], E-mail: rothenberg.sarah@gmail.com; Ambrose, Richard F. [Environmental Science and Engineering Program, Box 951772, University of California, Los Angeles, CA 90095-1772 (United States); Department of Environmental Health Sciences, Box 951772, University of California, Los Angeles, CA 90095-1772 (United States)], E-mail: rambrose@ucla.edu; Jay, Jennifer A. [Department of Civil and Environmental Engineering, Box 951593, University of California, Los Angeles, CA 90095-1593 (United States)], E-mail: jjay@seas.ucla.edu

    2008-07-15

    Mugu Lagoon is an estuary in southern California, listed as impaired for mercury. In 2005, we examined mercury cycling at ten sites within at most four habitats. In surface water (unfiltered and filtered) and pore water, the concentration of total mercury was correlated with methylmercury levels (R{sup 2} = 0.29, 0.26, 0.27, respectively, p < 0.05), in contrast to sediments, where organic matter and reduced iron levels were most correlated with methylmercury content (R{sup 2} = 0.37, 0.26, respectively, p < 0.05). Interestingly, levels for percent methylmercury of total mercury in sediments were higher than typical values for estuarine sediments (average 5.4%, range 0.024-38%, n = 59), while pore water methylmercury K{sub d} values were also high (average 3.1, range 2.0-4.2 l kg{sup -1}, n = 39), and the estimated methylmercury flux from sediments was low (average 1.7, range 0.14-5.3 ng m{sup -2} day{sup -1}, n = 19). Mercury levels in predatory fish tissue at Mugu are >0.3 ppm, suggesting biogeochemical controls on methylmercury mobility do not completely mitigate methylmercury uptake through the food web. - Trends in mercury cycling differed between habitats and within matrices at Mugu Lagoon.

  9. Understanding the life cycle surface land requirements of natural gas-fired electricity

    Science.gov (United States)

    Jordaan, Sarah M.; Heath, Garvin A.; Macknick, Jordan; Bush, Brian W.; Mohammadi, Ehsan; Ben-Horin, Dan; Urrea, Victoria; Marceau, Danielle

    2017-10-01

    The surface land use of fossil fuel acquisition and utilization has not been well characterized, inhibiting consistent comparisons of different electricity generation technologies. Here we present a method for robust estimation of the life cycle land use of electricity generated from natural gas through a case study that includes inventories of infrastructure, satellite imagery and well-level production. Approximately 500 sites in the Barnett Shale of Texas were sampled across five life cycle stages (production, gathering, processing, transmission and power generation). Total land use (0.62 m2 MWh-1, 95% confidence intervals ±0.01 m2 MWh-1) was dominated by midstream infrastructure, particularly pipelines (74%). Our results were sensitive to power plant heat rate (85-190% of the base case), facility lifetime (89-169%), number of wells per site (16-100%), well lifetime (92-154%) and pipeline right of way (58-142%). When replicated for other gas-producing regions and different fuels, our approach offers a route to enable empirically grounded comparisons of the land footprint of energy choices.

  10. A distributed eco-hydrological model and its application

    Directory of Open Access Journals (Sweden)

    Zong-xue Xu

    2017-10-01

    Full Text Available Eco-hydrological processes in arid areas are the focus of many hydrological and water resources studies. However, the hydrological cycle and the ecological system have usually been considered separately in most previous studies, and the correlation between the two has not been fully understood. Interdisciplinary research on eco-hydrological processes using multidisciplinary knowledge has been insufficient. In order to quantitatively analyze and evaluate the interaction between the ecosystem and the hydrological cycle, a new kind of eco-hydrological model, the ecology module for a grid-based integrated surface and groundwater model (Eco-GISMOD, is proposed with a two-way coupling approach, which combines the ecological model (EPIC and hydrological model (GISMOD by considering water exchange in the soil layer. Water interaction between different soil layers is simply described through a generalized physical process in various situations. A special method was used to simulate the water exchange between plants and the soil layer, taking into account precipitation, evapotranspiration, infiltration, soil water replenishment, and root water uptake. In order to evaluate the system performance, the Heihe River Basin in northwestern China was selected for a case study. The results show that forests and crops were generally growing well with sufficient water supply, but water shortages, especially in the summer, inhibited the growth of grass and caused grass degradation. This demonstrates that water requirements and water consumption for different kinds of vegetation can be estimated by considering the water-supply rules of Eco-GISMOD, which will be helpful for the planning and management of water resources in the future.

  11. A novel algorithm for delineating wetland depressions and mapping surface hydrologic flow pathways using LiDAR data

    Science.gov (United States)

    In traditional watershed delineation and topographic modeling, surface depressions are generally treated as spurious features and simply removed from a digital elevation model (DEM) to enforce flow continuity of water across the topographic surface to the watershed outlets. In re...

  12. Response of Surface Soil Hydrology to the Micro-Pattern of Bio-Crust in a Dry-Land Loess Environment, China.

    Science.gov (United States)

    Wei, Wei; Yu, Yun; Chen, Liding

    2015-01-01

    The specific bio-species and their spatial patterns play crucial roles in regulating eco-hydrologic process, which is significant for large-scale habitat promotion and vegetation restoration in many dry-land ecosystems. Such effects, however, are not yet fully studied. In this study, 12 micro-plots, each with size of 0.5 m in depth and 1 m in length, were constructed on a gentle grassy hill-slope with a mean gradient of 8° in a semiarid loess hilly area of China. Two major bio-crusts, including mosses and lichens, had been cultivated for two years prior to the field simulation experiments, while physical crusts and non-crusted bare soils were used for comparison. By using rainfall simulation method, four designed micro-patterns (i.e., upper bio-crust and lower bare soil, scattered bio-crust, upper bare soil and lower bio-crust, fully-covered bio-crust) to the soil hydrological response were analyzed. We found that soil surface bio-crusts were more efficient in improving soil structure, water holding capacity and runoff retention particularly at surface 10 cm layers, compared with physical soil crusts and non-crusted bare soils. We re-confirmed that mosses functioned better than lichens, partly due to their higher successional stage and deeper biomass accumulation. Physical crusts were least efficient in water conservation and erosion control, followed by non-crusted bare soils. More importantly, there were marked differences in the efficiency of the different spatial arrangements of bio-crusts in controlling runoff and sediment generation. Fully-covered bio-crust pattern provides the best option for soil loss reduction and runoff retention, while a combination of upper bio-crust and lower bare soil pattern is the least one. These findings are suggested to be significant for surface-cover protection, rainwater infiltration, runoff retention, and erosion control in water-restricted and degraded natural slopes.

  13. Combining satellite radar altimetry, SAR surface soil moisture and GRACE total storage changes for hydrological model calibration in a large poorly gauged catchment

    Directory of Open Access Journals (Sweden)

    C. Milzow

    2011-06-01

    Full Text Available The availability of data is a major challenge for hydrological modelling in large parts of the world. Remote sensing data can be exploited to improve models of ungauged or poorly gauged catchments. In this study we combine three datasets for calibration of a rainfall-runoff model of the poorly gauged Okavango catchment in Southern Africa: (i surface soil moisture (SSM estimates derived from radar measurements onboard the Envisat satellite; (ii radar altimetry measurements by Envisat providing river stages in the tributaries of the Okavango catchment, down to a minimum river width of about one hundred meters; and (iii temporal changes of the Earth's gravity field recorded by the Gravity Recovery and Climate Experiment (GRACE caused by total water storage changes in the catchment. The SSM data are shown to be helpful in identifying periods with over-respectively underestimation of the precipitation input. The accuracy of the radar altimetry data is validated on gauged subbasins of the catchment and altimetry data of an ungauged subbasin is used for model calibration. The radar altimetry data are important to condition model parameters related to channel morphology such as Manning's roughness. GRACE data are used to validate the model and to condition model parameters related to various storage compartments in the hydrological model (e.g. soil, groundwater, bank storage etc.. As precipitation input the FEWS-Net RFE, TRMM 3B42 and ECMWF ERA-Interim datasets are considered and compared.

  14. Estimating daily time series of streamflow using hydrological model calibrated based on satellite observations of river water surface width: Toward real world applications.

    Science.gov (United States)

    Sun, Wenchao; Ishidaira, Hiroshi; Bastola, Satish; Yu, Jingshan

    2015-05-01

    Lacking observation data for calibration constrains applications of hydrological models to estimate daily time series of streamflow. Recent improvements in remote sensing enable detection of river water-surface width from satellite observations, making possible the tracking of streamflow from space. In this study, a method calibrating hydrological models using river width derived from remote sensing is demonstrated through application to the ungauged Irrawaddy Basin in Myanmar. Generalized likelihood uncertainty estimation (GLUE) is selected as a tool for automatic calibration and uncertainty analysis. Of 50,000 randomly generated parameter sets, 997 are identified as behavioral, based on comparing model simulation with satellite observations. The uncertainty band of streamflow simulation can span most of 10-year average monthly observed streamflow for moderate and high flow conditions. Nash-Sutcliffe efficiency is 95.7% for the simulated streamflow at the 50% quantile. These results indicate that application to the target basin is generally successful. Beyond evaluating the method in a basin lacking streamflow data, difficulties and possible solutions for applications in the real world are addressed to promote future use of the proposed method in more ungauged basins. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  15. Critical Zone structure inferred from multiscale near surface geophysical and hydrological data across hillslopes at the Eel River CZO

    Science.gov (United States)

    Lee, S. S.; Rempe, D. M.; Holbrook, W. S.; Schmidt, L.; Hahm, W. J.; Dietrich, W. E.

    2017-12-01

    Except for boreholes and road cut, landslide, and quarry exposures, the subsurface structure of the critical zone (CZ) of weathered bedrock is relatively invisible and unmapped, yet this structure controls the short and long term fluxes of water and solutes. Non-invasive geophysical methods such as seismic refraction are widely applied to image the structure of the CZ at the hillslope scale. However, interpretations of such data are often limited due to heterogeneity and anisotropy contributed from fracturing, moisture content, and mineralogy on the seismic signal. We develop a quantitative framework for using seismic refraction tomography from intersecting geophysical surveys and hydrologic data obtained at the Eel River Critical Zone Observatory (ERCZO) in Northern California to help quantify the nature of subsurface structure across multiple hillslopes of varying topography in the area. To enhance our understanding of modeled velocity gradients and boundaries in relation to lithological properties, we compare refraction tomography results with borehole logs of nuclear magnetic resonance (NMR), gamma and neutron density, standard penetration testing, and observation drilling logs. We also incorporate laboratory scale rock characterization including mineralogical and elemental analyses as well as porosity and density measurements made via pycnometry, helium and mercury porosimetry, and laboratory scale NMR. We evaluate the sensitivity of seismically inferred saprolite-weathered bedrock and weathered-unweathered bedrock boundaries to various velocity and inversion parameters in relation with other macro scale processes such as gravitational and tectonic forces in influencing weathered bedrock velocities. Together, our sensitivity analyses and multi-method data comparison provide insight into the interpretation of seismic refraction tomography for the quantification of CZ structure and hydrologic dynamics.

  16. Application of near-surface geophysics as part of a hydrologic study of a subsurface drip irrigation system along the Powder River floodplain near Arvada, Wyoming

    Science.gov (United States)

    Sams, James I.; Veloski, Garret; Smith, Bruce D.; Minsley, Burke J.; Engle, Mark A.; Lipinski, Brian A.; Hammack, Richard W.; Zupancic, John W.

    2014-01-01

    Rapid development of coalbed natural gas (CBNG) production in the Powder River Basin (PRB) of Wyoming has occurred since 1997. National attention related to CBNG development has focused on produced water management, which is the single largest cost for on-shore domestic producers. Low-cost treatment technologies allow operators to reduce their disposal costs, provide treated water for beneficial use, and stimulate oil and gas production by small operators. Subsurface drip irrigation (SDI) systems are one potential treatment option that allows for increased CBNG production by providing a beneficial use for the produced water in farmland irrigation.Water management practices in the development of CBNG in Wyoming have been aided by integrated geophysical, geochemical, and hydrologic studies of both the disposal and utilization of water. The U.S. Department of Energy (DOE) National Energy Technology Laboratory (NETL) and the U.S. Geological Survey (USGS) have utilized multi-frequency airborne, ground, and borehole electromagnetic (EM) and ground resistivity methods to characterize the near-surface hydrogeology in areas of produced water disposal. These surveys provide near-surface EM data that can be compared with results of previous surveys to monitor changes in soils and local hydrology over time as the produced water is discharged through SDI.The focus of this investigation is the Headgate Draw SDI site, situated adjacent to the Powder River near the confluence of a major tributary, Crazy Woman Creek, in Johnson County, Wyoming. The SDI system was installed during the summer of 2008 and began operation in October of 2008. Ground, borehole, and helicopter electromagnetic (HEM) conductivity surveys were conducted at the site prior to the installation of the SDI system. After the installation of the subsurface drip irrigation system, ground EM surveys have been performed quarterly (weather permitting). The geophysical surveys map the heterogeneity of the near-surface

  17. Unraveling of permafrost hydrological variabilities on Central Qinghai-Tibet Plateau using stable isotopic technique.

    Science.gov (United States)

    Yang, Yuzhong; Wu, Qingbai; Hou, Yandong; Zhang, Zhongqiong; Zhan, Jing; Gao, Siru; Jin, Huijun

    2017-12-15

    Permafrost degradation on the Qinghai-Tibet Plateau (QTP) will substantially alter the surface runoff discharge and generation, which changes the recharge processes and influences the hydrological cycle on the QTP. Hydrological connections between different water bodies and the influence of thawing permafrost (ground ice) are not well understood on the QTP. This study applied water stable isotopic method to investigate the permafrost hydrological variabilities in Beiluhe Basin (BLB) on Central QTP. Isotopic variations of precipitation, river flow, thermokarst lake, and near-surface ground ice were identified to figure out the moisture source of them, and to elaborate the hydrological connections in permafrost region. Results suggested that isotopic seasonalities in precipitation is evident, it is showing more positive values in summer seasons, and negative values in winter seasons. Stable isotopes of river flow are mainly distributed in the range of precipitation which is indicative of important replenishment from precipitation. δ 18 O, δD of thermokarst lakes are more positive than precipitation, indicating of basin-scale evaporation of lake water. Comparison of δ I values in different water bodies shows that hydrology of thermokarst lakes was related to thawing of permafrost (ground ice) and precipitation. Near-surface ground ice in BLB exhibits different isotopic characteristics, and generates a special δD-δ 18 O relationship (freezing line): δD=5.81δ 18 O-23.02, which reflects typical freezing of liquid water. From isotopic analysis, it is inferred that near-surface ground ice was mainly recharged by precipitation and active layer water. Stable isotopic and conceptual model is suggestive of striking hydrological connections between precipitation, river flow, thermokarst lake, and ground ice under degrading permafrost. This research provides fundamental comprehensions into the hydrological processes in permafrost regions on QTP, which should be considered

  18. Changes of Hydrological Cycles in Land and Atmosphere in Europe and Asia in Case of Deforestation of Siberia (Results of GCM Numerical Experiments)

    International Nuclear Information System (INIS)

    Rubinstein, Konstantin G.; Shmakin, Andrey B.

    2004-01-01

    A new parameterization scheme of land hydrology was introduced into GCM of Hydro meteorological Centre of Russia. In this paper a short description of GCM and the scheme and their main parameters is given, as well as some results of experiments are discussed. It was analyzed hydrological balance in Atmosphere above Euro-Asia continent in two experiments. One of them we call 'Control' and other 'Siberian'. It differs only in type of vegetation and soil in Siberian region. It was shown that in case of 'Siberian deforestation' experiment average summer precipitation and evaporation became detectable less. In region of Caspian Sea precipitation and a little evaporation grow. As consequence it is possible to see changes in season changes of runoff Siberian and Caspian Sea basins. Runoff Siberian rivers decrease (as example we show result of Lena basin) and runoff Caspian basin increase.(Author)

  19. Acidification at the Surface in the East Sea: A Coupled Climate-carbon Cycle Model Study

    Science.gov (United States)

    Park, Young-Gyu; Seol, Kyung-Hee; Boo, Kyung-On; Lee, Johan; Cho, Chunho; Byun, Young-Hwa; Seo, Seongbong

    2018-05-01

    This modeling study investigates the impacts of increasing atmospheric CO2 concentration on acidification in the East Sea. A historical simulation for the past three decades (1980 to 2010) was performed using the Hadley Centre Global Environmental Model (version 2), a coupled climate model with atmospheric, terrestrial and ocean cycles. As the atmospheric CO2 concentration increased, acidification progressed in the surface waters of the marginal sea. The acidification was similar in magnitude to observations and models of acidification in the global ocean. However, in the global ocean, the acidification appears to be due to increased in-situ oceanic CO2 uptake, whereas local processes had stronger effects in the East Sea. pH was lowered by surface warming and by the influx of water with higher dissolved inorganic carbon (DIC) from the northwestern Pacific. Due to the enhanced advection of DIC, the partial pressure of CO2 increased faster than in the overlying air; consequently, the in-situ oceanic uptake of CO2 decreased.

  20. Daily Cycle of Air Temperature and Surface Temperature in Stone Forest

    Science.gov (United States)

    Wang, K.; Li, Y.; Wang, X.; Yuan, M.

    2013-12-01

    Urbanization is one of the most profound human activities that impact on climate change. In cities, where are highly artificial areas, the conflict between human activity and natural climate is particularly prominent. Urban areas always have the larger area of impervious land, the higher consumption of greenhouse gases, more emissions of anthropogenic heat and air pollution, all contribute to the urban warming phenomena. Understanding the mechanisms causing a variety of phenomena involved in the urban warming is critical to distinguish the anthropogenic effect and natural variation in the climate change. However, the exact dynamics of urban warming were poorly understood, and effective control strategies are not available. Here we present a study of the daily cycle of air temperature and surface temperature in Stone Forest. The specific heat of the stones in the Stone Forest and concrete of the man-made structures within the cities are approximate. Besides, the height of the Stone Forest and the height of buildings within the city are also similar. As a scenic area, the Stone Forest is being preserved and only opened for sightseeing. There is no anthropogenic heat, as well air pollution within the Stone Forest. The thermal environment in Stone Forest can be considered to be a simulation of thermal environment in the city, which can reveal the effect of man-made structures on urban thermal environment. We conducted the field studies and numerical analysis in the Stone Forest for 4 typical urban morphology and environment scenarios, including high-rise compact cities, low-rise sparse cities, garden cities and isolated single stone. Air temperature and relative humidity were measured every half an hour in 15 different locations, which within different spatial distribution of stones and can represent the four urban scenarios respectively. At the same time, an infrared camera was used to take thermal images and get the hourly surface temperatures of stones and

  1. Combining satellite radar altimetry, SAR surface soil moisture and GRACE total storage changes for hydrological model calibration in a large poorly gauged catchment

    DEFF Research Database (Denmark)

    Milzow, Christian; Krogh, Pernille Engelbredt; Bauer-Gottwein, Peter

    2011-01-01

    The availability of data is a major challenge for hydrological modelling in large parts of the world. Remote sensing data can be exploited to improve models of ungauged or poorly gauged catchments. In this study we combine three datasets for calibration of a rainfall-runoff model of the poorly...... gauged Okavango catchment in Southern Africa: (i) surface soil moisture (SSM) estimates derived from radar measurements onboard the Envisat satellite; (ii) radar altimetry measurements by Envisat providing river stages in the tributaries of the Okavango catchment, down to a minimum river width of about...... one hundred meters; and (iii) temporal changes of the Earth's gravity field recorded by the Gravity Recovery and Climate Experiment (GRACE) caused by total water storage changes in the catchment. The SSM data are shown to be helpful in identifying periods with over-respectively underestimation...

  2. Modelling hydrological changes in surface in relation with anthropogenic drivers and consequences on human health and local economic

    Science.gov (United States)

    Sandoz, Alain; Leblond, Agnès; Boutron, Olivier

    2016-04-01

    Marais des Baux are located between Alpilles in the North and the plain of the Crau (South-East) of the town of Arles, in the South of France. Already built in Roman times, swamps located at the outlet of the Baux valley basin have experienced an increased human pressure during last centuries. Apotheosis of human development is the period of post-war with Marshall Plan and the development of the Common Agricultural Policy (CAP). At the beginning of the 21st century, inverse hydrologic dynamic is observed. Renaturation of the lower parts of the marshes, where land is less profitable, has reversed the trend of previous centuries. To be sustainable, this annealing must be accompanied by water governance at the watershed scale. This work aims to help policy makers and managers to good governance of the territory. Hierarchical multi-scale approach has enabled a better understanding of hydrological flows. In addition, knowledge of different actors' strategies is not enough. There may be different interests and strategies within the same group of actors. In this case, this is what we observe between farmers located on the upstream parts of the watershed eager, for some, to increase irrigation, and those located downstream, in the marshes, forced pump to maintain water levels corresponding to the expectations of the majority of the actors. On the other hand, there is a negative image of still marsh near a rural population and new rural population. Decreasing pumping or to send a higher volume of water could significantly increase flooded areas. This increase in flooded areas could facilitate the development of certain mosquito species. These mosquitoes not only represent a potential health risk for human populations but also increase the discomfort felt by the local population and tourists. This discomfort may also have an impact on economic activity linked with tourism. The work allowed the testing of different scenarios of flooding, according to the hydraulic management

  3. Application of 2H and 18O in hydrological studies

    International Nuclear Information System (INIS)

    Stichler, W.

    1980-08-01

    Due to isotope fractionation effects there exist typical variations in isotope content in the hydrological cycle. The greatest changes in isotope concentration occur in precipitation and can be described in terms of global and local effects. In surface waters the fluctuations in isotope content can be used for many hydrological investigations such as river mixing and lake studies. The isotope effects in the formation of precipitation also enable conclusions about the residence time and the origin of groundwater i.e. its catchment area, and about the climatic conditions prevailing at the time of groundwater recharge. In two expamples the interrelations between precipitation and surface or groundwater as well as between surface water and groundwater show the application of isotope techniques. (orig.) [de

  4. Hydrology of the Beryl-Enterprise area, Escalante Desert, Utah, with emphasis on ground water; With a section on surface water

    Science.gov (United States)

    Mower, Reed W.; Sandberg, George Woodard

    1982-01-01

    An investigation of the water resources of the Beryl-Enterprise area, Escalante Desert, Utah (pl. 1), was made during 1976-78 as part of a cooperative program with the Utah Department of Natural Resources, Division of Water Rights. Wells were the most important source of water for all purposes in the Beryl-Enterprise area during 1978, but it has not always been so. For nearly a century after the first settlers arrived in about 1860, streams supplied most of the irrigation water and springs supplied much of the water for domestic and stock use. A few shallow wells were dug by the early settlers for domestic and stock water, but the widespread use of ground water did not start until the 1920's when shallow wells were first dug to supply irrigation water. Ground-water withdrawals from wells, principally for irrigation, have increased nearly every year since the 1920's. The quantity withdrawn from wells surpassed that diverted from surface sources during the mid-1940's and was about eight times that amount during the 1970's. As a result, water levels have declined measurably throughout the area resulting in administrative water-rights problems.The primary purpose of this report is to describe the water resources with emphasis on ground water. The surface-water resources are evaluated only as they pertain to the understanding of the ground-water resources. A secondary purpose is to discuss the extent and effects of the development of ground water in order to provide the hydrologic information needed for the orderly and optimum development of the resource and for the effective administration and adjudication of water rights in the area. The hydrologic data on which this report is based are given in a companion report by Mower (1981).

  5. Isotope methods in hydrology

    International Nuclear Information System (INIS)

    Moser, H.; Rauert, W.

    1980-01-01

    Of the investigation methods used in hydrology, tracer methods hold a special place as they are the only ones which give direct insight into the movement and distribution processes taking place in surface and ground waters. Besides the labelling of water with salts and dyes, as in the past, in recent years the use of isotopes in hydrology, in water research and use, in ground-water protection and in hydraulic engineering has increased. This by no means replaces proven methods of hydrological investigation but tends rather to complement and expand them through inter-disciplinary cooperation. The book offers a general introduction to the application of various isotope methods to specific hydrogeological and hydrological problems. The idea is to place the hydrogeologist and the hydrologist in the position to recognize which isotope method will help him solve his particular problem or indeed, make a solution possible at all. He should also be able to recognize what the prerequisites are and what work and expenditure the use of such methods involves. May the book contribute to promoting cooperation between hydrogeologists, hydrologists, hydraulic engineers and isotope specialists, and thus supplement proven methods of investigation in hydrological research and water utilization and protection wherever the use of isotope methods proves to be of advantage. (orig./HP) [de

  6. A hydrological prediction system based on the SVS land-surface scheme: efficient calibration of GEM-Hydro for streamflow simulation over the Lake Ontario basin

    Directory of Open Access Journals (Sweden)

    É. Gaborit

    2017-09-01

    Full Text Available This work explores the potential of the distributed GEM-Hydro runoff modeling platform, developed at Environment and Climate Change Canada (ECCC over the last decade. More precisely, the aim is to develop a robust implementation methodology to perform reliable streamflow simulations with a distributed model over large and partly ungauged basins, in an efficient manner. The latest version of GEM-Hydro combines the SVS (Soil, Vegetation and Snow land-surface scheme and the WATROUTE routing scheme. SVS has never been evaluated from a hydrological point of view, which is done here for all major rivers flowing into Lake Ontario. Two established hydrological models are confronted to GEM-Hydro, namely MESH and WATFLOOD, which share the same routing scheme (WATROUTE but rely on different land-surface schemes. All models are calibrated using the same meteorological forcings, objective function, calibration algorithm, and basin delineation. GEM-Hydro is shown to be competitive with MESH and WATFLOOD: the NSE  √  (Nash–Sutcliffe criterion computed on the square root of the flows is for example equal to 0.83 for MESH and GEM-Hydro in validation on the Moira River basin, and to 0.68 for WATFLOOD. A computationally efficient strategy is proposed to calibrate SVS: a simple unit hydrograph is used for routing instead of WATROUTE. Global and local calibration strategies are compared in order to estimate runoff for ungauged portions of the Lake Ontario basin. Overall, streamflow predictions obtained using a global calibration strategy, in which a single parameter set is identified for the whole basin of Lake Ontario, show accuracy comparable to the predictions based on local calibration: the average NSE  √  in validation and over seven subbasins is 0.73 and 0.61, respectively for local and global calibrations. Hence, global calibration provides spatially consistent parameter values, robust performance at gauged locations, and reduces the

  7. A hydrological prediction system based on the SVS land-surface scheme: efficient calibration of GEM-Hydro for streamflow simulation over the Lake Ontario basin

    Science.gov (United States)

    Gaborit, Étienne; Fortin, Vincent; Xu, Xiaoyong; Seglenieks, Frank; Tolson, Bryan; Fry, Lauren M.; Hunter, Tim; Anctil, François; Gronewold, Andrew D.

    2017-09-01

    This work explores the potential of the distributed GEM-Hydro runoff modeling platform, developed at Environment and Climate Change Canada (ECCC) over the last decade. More precisely, the aim is to develop a robust implementation methodology to perform reliable streamflow simulations with a distributed model over large and partly ungauged basins, in an efficient manner. The latest version of GEM-Hydro combines the SVS (Soil, Vegetation and Snow) land-surface scheme and the WATROUTE routing scheme. SVS has never been evaluated from a hydrological point of view, which is done here for all major rivers flowing into Lake Ontario. Two established hydrological models are confronted to GEM-Hydro, namely MESH and WATFLOOD, which share the same routing scheme (WATROUTE) but rely on different land-surface schemes. All models are calibrated using the same meteorological forcings, objective function, calibration algorithm, and basin delineation. GEM-Hydro is shown to be competitive with MESH and WATFLOOD: the NSE √ (Nash-Sutcliffe criterion computed on the square root of the flows) is for example equal to 0.83 for MESH and GEM-Hydro in validation on the Moira River basin, and to 0.68 for WATFLOOD. A computationally efficient strategy is proposed to calibrate SVS: a simple unit hydrograph is used for routing instead of WATROUTE. Global and local calibration strategies are compared in order to estimate runoff for ungauged portions of the Lake Ontario basin. Overall, streamflow predictions obtained using a global calibration strategy, in which a single parameter set is identified for the whole basin of Lake Ontario, show accuracy comparable to the predictions based on local calibration: the average NSE √ in validation and over seven subbasins is 0.73 and 0.61, respectively for local and global calibrations. Hence, global calibration provides spatially consistent parameter values, robust performance at gauged locations, and reduces the complexity and computation burden of the

  8. Isotope hydrology

    International Nuclear Information System (INIS)

    Drost, W.

    1978-01-01

    The International Symposium on Isotope Hydrology was jointly organized by the IAEA and UNESCO, in co-operation with the National Committee of the Federal Republic of Germany for the International Hydrological Programme (IHP) and the Gesellschaft fuer Strahlen- und Umweltforschung mbH (GSF). Upon the invitation of the Federal Republic of Germany the Symposium was held from 19-23 June 1978 in Neuherberg on the GSF campus. The Symposium was officially opened by Mr. S. Eklund, Director General of the IAEA. The symposium - the fifth meeting held on isotope hydrology - was attended by over 160 participants from 44 countries and four international organizations and by about 30 observers from the Federal Republic of Germany. Due to the absence of scientists from the USSR five papers were cancelled and therefore only 46 papers of the original programme were presented in ten sessions

  9. Assessing the impact of model spin-up on surface water-groundwater interactions using an integrated hydrologic model

    KAUST Repository

    Ajami, Hoori; McCabe, Matthew; Evans, Jason P.; Stisen, Simon

    2014-01-01

    is to minimize the impact of initialization while using the smallest spin-up time possible. In this study, multicriteria analysis was performed to assess the spin-up behavior of the ParFlow.CLM integrated groundwater-surface water-land surface model over a 208 km

  10. The importance of kinetics and redox in the biogeochemical cycling of iron in the surface ocean.

    Directory of Open Access Journals (Sweden)

    Peter L. Croot

    2012-06-01

    Full Text Available It is now well established that Iron (Fe is a limiting element in many regions of the open ocean. Our current understanding of the key processes which control iron distribution in the open ocean have been largely based on thermodynamic measurements performed under the assumption of equilibrium conditions. Using this equilibrium approach, researchers have been able to detect and quantify organic complexing ligands in seawater and examine their role in increasing the overall solubility of iron. Our current knowledge about iron bioavailability to phytoplankton and bacteria is also based heavily on carefully controlled laboratory studies where it is assumed the chemical species are in equilibrium in line with the free ion association model (FIAM and/or its successor the biotic ligand model (BLM. Similarly most field work on Fe biogeochemistry generally consists of a single profile which is in essence a ‘snap-shot’ in time of the system under investigation. However it is well known that the surface ocean is an extremely dynamic environment and it is unlikely if thermodynamic equilibrium between all the iron species present is ever truly achieved. In sunlit waters this is mostly due to the daily passage of the sun across the sky leading to photoredox processes which alter Fe speciation by cycling between redox states and between inorganic and organic species. Episodic deposition events, are also important perturbations to iron cycling as they bring new iron to the system altering the equilibrium between species and phases. Over the last 20 years the mesoscale iron enrichment experiments (e.g. IronEx I /II, SOIREE, EisenEx, SOFeX, EIFeX, SAGE, SEEDS and SERIES I /II and the FeCycle (I/II experiments have provided the first insights into processes altering iron speciation and distribution which occur over temporal scales of days to weeks. Here we utilize new field data collected in the open ocean on the redox and complexation kinetics of iron in the

  11. ClimoBase: Rouse Canadian Surface Observations of Weather, Climate, and Hydrological Variables, 1984-1998, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — ClimoBase is a collection of surface climate measurements collected in Northern Canada by Dr. Wayne Rouse between 1984 and 1998 in three locations: Churchill,...

  12. A satellite based scheme for predicting the effects of land cover change on local microclimate and surface hydrology: Development of an operational regional planning tool

    Science.gov (United States)

    Arthur, Sandra Traci

    Humans have diverse goals for their use of land: mining, water supply, aesthetic enjoyment, recreation, transportation, housing, etc. Any individual living within an actively developing community can look back in time and note how, perhaps slowly but nonetheless dramatically, the total land area dedicated to human use has increased. As our society's basic functioning intensifies, the disappearance of "free" open space is apparent---today, even conservation areas are carefully designated, mapped and controlled. This transition in land use is a result of many individual decisions that occur throughout space and time, often with little concern for the potential impacts on the local environment. Two specific environmental components---the microclimate and surface hydrology---are the focus of this thesis. This study, as well as related tools and bodies of knowledge, should be used to broaden the scientific basis behind land use management decisions. It will be shown that development can induce predictable changes in measures of the local radiant surface temperature and evapotranspiration fraction---as long as certain features of the development are known. Specifically, the vegetation changes that accompany the development must be noted, as well as the initial climatic state of the land parcel. Additionally, plots of runoff vs. rainfall for gauged basins will be interpreted in terms of the proportion of the basin contributing to a storm event's runoff signal. For a particular basin, four distinct runoff responses, separated by season and antecedent moisture conditions, will be distinguished. The response for the non-summer months under typical antecedent moisture conditions will be shown to be the most representative of and responsive to a basin's land use patterns. A scheme that makes use of satellite-derived land cover patterns and other physical attributes of the basin in order to determine this particular runoff response will be presented. The Soil Conservation

  13. Frozen soil and snow cover with respect to the hydrological land-surface behaviour; Gefrorener Boden und Schneebedeckung unter besonderer Beruecksichtigung des hydrologischen Verhaltens der Landoberflaeche

    Energy Technology Data Exchange (ETDEWEB)

    Warrach, K. [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Atmosphaerenphysik

    2000-07-01

    Investigations of the water and energy cycle in the climate system using atmospheric circulation models require a proper representation of the land surface. The land-surface model SEWAB calculates the vertical exchange of water and energy between the atmosphere and the land-surface. This includes the calculation of runoff from the land-surface into the rivers and of the vertical heat and water fluxes within the soil. The inclusion of soil freezing and thawing and the accumulation and ablation of a snow cover in SEWAB is introduced. Additionally changes in the runoff calculation such as the inclusion of the TOPMODEL-approach to consider orographic effects are made. Applications carried out for various regions of North America show good agreement between model results and measurements. (orig.)

  14. Improving Permafrost Hydrology Prediction Through Data-Model Integration

    Science.gov (United States)

    Wilson, C. J.; Andresen, C. G.; Atchley, A. L.; Bolton, W. R.; Busey, R.; Coon, E.; Charsley-Groffman, L.

    2017-12-01

    The CMIP5 Earth System Models were unable to adequately predict the fate of the 16GT of permafrost carbon in a warming climate due to poor representation of Arctic ecosystem processes. The DOE Office of Science Next Generation Ecosystem Experiment, NGEE-Arctic project aims to reduce uncertainty in the Arctic carbon cycle and its impact on the Earth's climate system by improved representation of the coupled physical, chemical and biological processes that drive how much buried carbon will be converted to CO2 and CH4, how fast this will happen, which form will dominate, and the degree to which increased plant productivity will offset increased soil carbon emissions. These processes fundamentally depend on permafrost thaw rate and its influence on surface and subsurface hydrology through thermal erosion, land subsidence and changes to groundwater flow pathways as soil, bedrock and alluvial pore ice and massive ground ice melts. LANL and its NGEE colleagues are co-developing data and models to better understand controls on permafrost degradation and improve prediction of the evolution of permafrost and its impact on Arctic hydrology. The LANL Advanced Terrestrial Simulator was built using a state of the art HPC software framework to enable the first fully coupled 3-dimensional surface-subsurface thermal-hydrology and land surface deformation simulations to simulate the evolution of the physical Arctic environment. Here we show how field data including hydrology, snow, vegetation, geochemistry and soil properties, are informing the development and application of the ATS to improve understanding of controls on permafrost stability and permafrost hydrology. The ATS is being used to inform parameterizations of complex coupled physical, ecological and biogeochemical processes for implementation in the DOE ACME land model, to better predict the role of changing Arctic hydrology on the global climate system. LA-UR-17-26566.

  15. Calculation of the surface water pollution index in the evaluation of environmental component of product life cycle

    Directory of Open Access Journals (Sweden)

    Олег Аскольдович Проскурнин

    2015-05-01

    Full Text Available The assessment feasibility of the combined effect of the product life cycle on the environment is grounded. As an example, the pollution of surface waters at the production stage is considered in the article. A mechanism of ranking indicators of surface water pollution according to their importance is proposed. An algorithm for checking the consistency of the statistical expert judgment in determining weight coefficient for the indicators of pollution, based on the use of the concordance coefficient, is given

  16. Using coral Ba/Ca records to investigate seasonal to decadal scale biogeochemical cycling in the surface and intermediate ocean.

    Science.gov (United States)

    LaVigne, M.; Cobb, K. M.; DeLong, K. L.; Freiberger, M. M.; Grottoli, A. G.; Hill, T. M.; Miller, H. R.; Nurhati, I. S.; Richey, J. N.; Serrato Marks, G.; Sherrell, R. M.

    2016-12-01

    Dissolved barium (BaSW), a bio-intermediate element, is linked to several biogeochemical processes such as the cycling and export of nutrients, organic carbon (Corg), and barite in surface and intermediate oceans. Dynamic BaSW cycling has been demonstrated in the water column on short timescales (days-weeks) while sedimentary records have documented geologic-scale changes in barite preservation driven by export production. Our understanding of how seasonal-decadal scale climate variability impacts these biogeochemical processes currently lacks robust records. Ba/Ca calibrations in surface and deep sea corals suggest barium is incorporated via cationic substitution in both aragonite and calcite. Here we demonstrate the utility of Ba/Ca for reconstructing biogeochemical variability using examples of surface and deep sea coral records. Century-long deep sea coral records from the California Current System (bamboo corals: 900-1500m) record interannual variations in Ba/Ca, likely reflecting changes in barite formation via bacterial Corg respiration or barite saturation state. A surface Porites coral Ba/Ca record from Christmas Island (central equatorial Pacific: 1978-1995) shows maxima during low productivity El Niño warm periods, suggesting that variations in BaSW are driven by biological removal via direct cellular uptake or indirectly via barite precipitation with the decomposition of large phytoplankton blooms at this location. Similarly, a sixteen-year long Siderastera siderea surface coral record from Dry Tortugas, FL (Gulf of Mexico: 1991-2007) shows seasonal Ba/Ca cycles that align with annual chlorophyll and δ13C. Taken together, these records demonstrate the linkages among Corg, nutrient cycling and BaSW in the surface and intermediate ocean on seasonal to decadal timescales. Multi-proxy paleoceanographic reconstructions including Ba/Ca have the potential to elucidate the mechanisms linking past climate, productivity, nutrients, and BaSW cycling in the past.

  17. Integrated Landsat Image Analysis and Hydrologic Modeling to Detect Impacts of 25-Year Land-Cover Change on Surface Runoff in a Philippine Watershed

    Directory of Open Access Journals (Sweden)

    Enrico Paringit

    2011-05-01

    Full Text Available Landsat MSS and ETM+ images were analyzed to detect 25-year land-cover change (1976–2001 in the critical Taguibo Watershed in Mindanao Island, Southern Philippines. This watershed has experienced historical modifications of its land-cover due to the presence of logging industries in the 1950s, and continuous deforestation due to illegal logging and slash-and-burn agriculture in the present time. To estimate the impacts of land-cover change on watershed runoff, land-cover information derived from the Landsat images was utilized to parameterize a GIS-based hydrologic model. The model was then calibrated with field-measured discharge data and used to simulate the responses of the watershed in its year 2001 and year 1976 land-cover conditions. The availability of land-cover information on the most recent state of the watershed from the Landsat ETM+ image made it possible to locate areas for rehabilitation such as barren and logged-over areas. We then created a “rehabilitated” land-cover condition map of the watershed (re-forestation of logged-over areas and agro-forestation of barren areas and used it to parameterize the model and predict the runoff responses of the watershed. Model results showed that changes in land-cover from 1976 to 2001 were directly related to the significant increase in surface runoff. Runoff predictions showed that a full rehabilitation of the watershed, especially in barren and logged-over areas, will be likely to reduce the generation of a huge volume of runoff during rainfall events. The results of this study have demonstrated the usefulness of multi-temporal Landsat images in detecting land-cover change, in identifying areas for rehabilitation, and in evaluating rehabilitation strategies for management of tropical watersheds through its use in hydrologic modeling.

  18. Surface Corrosion and Microstructure Degradation of Calcium Sulfoaluminate Cement Subjected to Wet-Dry Cycles in Sulfate Solution

    Directory of Open Access Journals (Sweden)

    Wuman Zhang

    2017-01-01

    Full Text Available The hydration products of calcium sulfoaluminate (CSA cement are different from those of Portland cement. The degradation of CSA cement subjected to wet-dry cycles in sulfate solution was studied in this paper. The surface corrosion was recorded and the microstructures were examined by scanning electron microscopy (SEM. The results show that SO42-, Na+, Mg2+, and Cl− have an effect on the stability of ettringite. In the initial period of sulfate attack, salt crystallization is the main factor leading to the degradation of CSA cement specimens. The decomposition and the carbonation of ettringite will cause long-term degradation of CSA cement specimens under wet-dry cycles in sulfate solution. The surface spalling and microstructure degradation increase significantly with the increase of wet-dry cycles, sulfate concentration, and water to cement ratio. Magnesium sulfate and sodium chloride reduce the degradation when the concentration of sulfate ions is a constant value.

  19. A Conceptual Approach to Assimilating Remote Sensing Data to Improve Soil Moisture Profile Estimates in a Surface Flux/Hydrology Model. Part 1; Overview

    Science.gov (United States)

    Crosson, William L.; Laymon, Charles A.; Inguva, Ramarao; Schamschula, Marius; Caulfield, John

    1998-01-01

    advantage of radar is its much higher resolution than passive microwave systems, but it is currently hampered by surface roughness effects and the lack of a good algorithm based on a single frequency and single polarization. In addition, its repeat frequency is generally low (about 40 days). In the meantime, two new radiometers offer some hope for remote sensing of soil moisture from space. The Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI), launched in November 1997, possesses a 10.65 GHz channel and the Advanced Microwave Scanning Radiometer (AMSR) on both the ADEOS-11 and Earth Observing System AM-1 platforms to be launched in 1999 possesses a 6.9 GHz channel. Aside from issues about interference from vegetation, the coarse resolution of these data will provide considerable challenges pertaining to their application. The resolution of TMI is about 45 km and that of AMSR is about 70 km. These resolutions are grossly inconsistent with the scale of soil moisture processes and the spatial variability of factors that control soil moisture. Scale disparities such as these are forcing us to rethink how we assimilate data of various scales in hydrologic models. Of particular interest is how to assimilate soil moisture data by reconciling the scale disparity between what we can expect from present and future remote sensing measurements of soil moisture and modeling soil moisture processes. It is because of this disparity between the resolution of space-based sensors and the scale of data needed for capturing the spatial variability of soil moisture and related properties that remote sensing of soil moisture has not met with more widespread success. Within a single footprint of current sensors at the wavelengths optimal for this application, in most cases there is enormous heterogeneity in soil moisture created by differences in landcover, soils and topography, as well as variability in antecedent precipitation. It is difficult to interpret the meaning of 'mean

  20. Deforestation Hydrological Effects

    International Nuclear Information System (INIS)

    Poveda J, G.; Mesa S, O.J.

    1995-01-01

    Deforestation causes strong disturbances in ecosystems and in hydrological cycle, increasing or reducing wealths. Particularly in this work, effects of feed back between interface processes land - atmosphere are discussed and is demonstrated that losses of water by evaporation-transpiration are thoroughly indispensable to maintain the balance of hydrological regime. It's concluded that as a rule the effect of deforestation is to reduce wealth middle and to increase extreme wealth with consequent stronger and more frequent droughts or flood effects. Other deforestation effects as increase in superficial temperature, increase in atmospherical pressure, decrease in soil moisture, decrease in evaporation-transpiration, decrease of soil ruggedness, decrease of thickness of atmospherical cap limit, decrease of clouds, decrease of rain in both medium and long term and the consequent decrease of rivers wealth middle are explained. Of other side, the basins with greater deforestation affectation in Colombia are indicated. Finally, it's demonstrated the need of implementing reforestation programs

  1. Using Modeling Tools to Better Understand Permafrost Hydrology

    Directory of Open Access Journals (Sweden)

    Clément Fabre

    2017-06-01

    Full Text Available Modification of the hydrological cycle and, subsequently, of other global cycles is expected in Arctic watersheds owing to global change. Future climate scenarios imply widespread permafrost degradation caused by an increase in air temperature, and the expected effect on permafrost hydrology is immense. This study aims at analyzing, and quantifying the daily water transfer in the largest Arctic river system, the Yenisei River in central Siberia, Russia, partially underlain by permafrost. The semi-distributed SWAT (Soil and Water Assessment Tool hydrological model has been calibrated and validated at a daily time step in historical discharge simulations for the 2003–2014 period. The model parameters have been adjusted to embrace the hydrological features of permafrost. SWAT is shown capable to estimate water fluxes at a daily time step, especially during unfrozen periods, once are considered specific climatic and soils conditions adapted to a permafrost watershed. The model simulates average annual contribution to runoff of 263 millimeters per year (mm yr−1 distributed as 152 mm yr−1 (58% of surface runoff, 103 mm yr−1 (39% of lateral flow and 8 mm yr−1 (3% of return flow from the aquifer. These results are integrated on a reduced basin area downstream from large dams and are closer to observations than previous modeling exercises.

  2. Response of Surface Soil Hydrology to the Micro-Pattern of Bio-Crust in a Dry-Land Loess Environment, China.

    Directory of Open Access Journals (Sweden)

    Wei Wei

    Full Text Available The specific bio-species and their spatial patterns play crucial roles in regulating eco-hydrologic process, which is significant for large-scale habitat promotion and vegetation restoration in many dry-land ecosystems. Such effects, however, are not yet fully studied. In this study, 12 micro-plots, each with size of 0.5 m in depth and 1 m in length, were constructed on a gentle grassy hill-slope with a mean gradient of 8° in a semiarid loess hilly area of China. Two major bio-crusts, including mosses and lichens, had been cultivated for two years prior to the field simulation experiments, while physical crusts and non-crusted bare soils were used for comparison. By using rainfall simulation method, four designed micro-patterns (i.e., upper bio-crust and lower bare soil, scattered bio-crust, upper bare soil and lower bio-crust, fully-covered bio-crust to the soil hydrological response were analyzed. We found that soil surface bio-crusts were more efficient in improving soil structure, water holding capacity and runoff retention particularly at surface 10 cm layers, compared with physical soil crusts and non-crusted bare soils. We re-confirmed that mosses functioned better than lichens, partly due to their higher successional stage and deeper biomass accumulation. Physical crusts were least efficient in water conservation and erosion control, followed by non-crusted bare soils. More importantly, there were marked differences in the efficiency of the different spatial arrangements of bio-crusts in controlling runoff and sediment generation. Fully-covered bio-crust pattern provides the best option for soil loss reduction and runoff retention, while a combination of upper bio-crust and lower bare soil pattern is the least one. These findings are suggested to be significant for surface-cover protection, rainwater infiltration, runoff retention, and erosion control in water-restricted and degraded natural slopes.

  3. Response of Surface Soil Hydrology to the Micro-Pattern of Bio-Crust in a Dry-Land Loess Environment, China

    Science.gov (United States)

    Wei, Wei; Yu, Yun; Chen, Liding

    2015-01-01

    The specific bio-species and their spatial patterns play crucial roles in regulating eco-hydrologic process, which is significant for large-scale habitat promotion and vegetation restoration in many dry-land ecosystems. Such effects, however, are not yet fully studied. In this study, 12 micro-plots, each with size of 0.5 m in depth and 1 m in length, were constructed on a gentle grassy hill-slope with a mean gradient of 8° in a semiarid loess hilly area of China. Two major bio-crusts, including mosses and lichens, had been cultivated for two years prior to the field simulation experiments, while physical crusts and non-crusted bare soils were used for comparison. By using rainfall simulation method, four designed micro-patterns (i.e., upper bio-crust and lower bare soil, scattered bio-crust, upper bare soil and lower bio-crust, fully-covered bio-crust) to the soil hydrological response were analyzed. We found that soil surface bio-crusts were more efficient in improving soil structure, water holding capacity and runoff retention particularly at surface 10 cm layers, compared with physical soil crusts and non-crusted bare soils. We re-confirmed that mosses functioned better than lichens, partly due to their higher successional stage and deeper biomass accumulation. Physical crusts were least efficient in water conservation and erosion control, followed by non-crusted bare soils. More importantly, there were marked differences in the efficiency of the different spatial arrangements of bio-crusts in controlling runoff and sediment generation. Fully-covered bio-crust pattern provides the best option for soil loss reduction and runoff retention, while a combination of upper bio-crust and lower bare soil pattern is the least one. These findings are suggested to be significant for surface-cover protection, rainwater infiltration, runoff retention, and erosion control in water-restricted and degraded natural slopes. PMID:26207757

  4. Potentiometric Surface of the Alluvial Aquifer and Hydrologic Conditions in the Juana Diaz area, Puerto Rico, June 29 - July 1, 2005

    Science.gov (United States)

    Rodriguez, Jose M.; Santigo-Rivera, Luis; Gómez-Gómez, Fernando

    2006-01-01

    A synoptic survey of the hydrologic conditions in the Juana Diaz area, Puerto Rico, was conducted between June 29 and July 1, 2005, to define the spatial distribution of the potentiometric surface of the alluvial aquifer. The study area encompasses 21 square miles of the more extensive South Coastal Plain Alluvial Aquifer system and is bounded along the north by foothills of the Cordillera Central mountain chain, to the south by the Caribbean Sea, the east by the Rio Descalabrado and to the west by the Rio Inabon. Ground water in the Juana Diaz area is in the Quaternary-age alluvial deposits and the middle-Tertiary age Ponce Limestone and Juana Diaz Formation (Giusti, 1968). The hydraulic properties of the Ponce Limestone in the Juana Diaz area are unknown, and the Juana Diaz Formation is a unit of poor permeability due to its high clay content. Consequently, the Ponce Limestone and the Juana Diaz Formation are generally considered to be the base of the alluvial aquifer in the Juana Diaz area with ground-water flow occurring primarily within the alluvial deposits. The potentiometric-surface map of the alluvial aquifer was delineated using ground-water level measurements taken at existing wells. The water-level measurements were taken at wells that were either not pumping during the survey or were shut down for a brief period. In the latter case, a recovery period of 30 minutes was allowed for the drawdown in the wellbore to achieve a near static level position representative of the aquifer at the measurement point. Land-surface altitude from U.S. Geological Survey (USGS) 1:20,000 scale topographic maps (Playa de Ponce, Ponce, Rio Descalabrado, and Santa Isabel) were used to refer ground-water levels to mean sea level datum (National Geodetic Vertical Datum of 1929). In addition to the ground-water level measurements, the potentiometricsurface contours were delineated using hydrologic features, such as drainage ditches and saturated intermittent streams that were

  5. Surface-atmospheric water cycle at Gale crater through multi-year MSL/REMS observations

    Science.gov (United States)

    Harri, A. M.; Genzer, M.; McConnochie, T. H.; Savijarvi, H. I.; Smith, M. D.; Martinez, G.; de la Torre Juarez, M.; Haberle, R. M.; Polkko, J.; Gomez-Elvira, J.; Renno, N. O.; Kemppinen, O.; Paton, M.; Richardson, M. I.; Newman, C. E.; Siili, T. T.; Mäkinen, T.

    2017-12-01

    The Mars Science laboratory (MSL) has been successfully operating for almost three Martian years. That includes an unprecedented long time series of atmospheric observations by the REMS instrument performing measurements of atmospheric pressure, relative humidity (REMS-H), temperature of the air, ground temperature, UV and wind speed and direction. The REMS-H relative humidity device is based on polymeric capacitive humidity sensors developed by Vaisala Inc. and it makes use of three (3) humidity sensor heads. The humidity device is mounted on the REMS boom providing ventilation with the ambient atmosphere through a filter protecting the device from airborne dust. The REMS-H humidity instrument has created an unprecedented data record of more than two full Martian. REMS-H measured the relative humidity and temperature at 1.6 m height for a period of 5 minutes every hour as part of the MSL/REMS instrument package. We focus on describing the annual in situ water cycle with the REMS-H instrument data for the period of almost three Martian years. The results will be constrained through comparison with independent indirect observations and through modeling efforts. We inferred the hourly atmospheric VMR from the REMS-H observations and compared these VMR measurements with predictions of VMR from our 1D column Martian atmospheric model and regolith to investigate the local water cycle, exchange processes and the local climate in Gale Crater. The strong diurnal variation suggests there are surface-atmosphere exchange processes at Gale Crater during all seasons, which depletes moisture to the ground in the evening and nighttime and release the moisture back to the atmosphere during the daytime. On the other hand, these processes do not seem to result in significant water deposition on the ground. Hence, our modelling results presumably indicate that adsorption processes take place during the nighttime and desorption during the daytime. Other processes, e.g. convective

  6. Surface Acting and Job-Related Affective Wellbeing: Preventing Resource Loss Spiral and Resource Loss Cycle for Sustainable Workplaces

    Directory of Open Access Journals (Sweden)

    Seongwook Ha

    2018-04-01

    Full Text Available This study empirically examines the synergistic negative effect of two kinds of job demand on job-related affective wellbeing (JAW and the accelerating effects of cynicism in the negative relationships between job demands and JAW using a sample of 299 employees in the Chinese banking industry. Job demands include quantitative role overload and surface acting to represent the quantitative and qualitative aspects of job demands. Cynicism is introduced as a state where one’s energy resource is lost. The results of this study show that surface acting has a negative relationship with JAW, but quantitative role overload has no relationship with JAW. High levels of quantitative role overload exacerbate the negative relationship between surface acting and JAW. Cynicism also exacerbates the negative relationship between surface acting and JAW but does not have any moderating effect in the relationship between quantitative role overload and JAW. These results are consistent with the relationships predicted by resource loss spiral and resource loss cycle. The resource loss spiral means that resource loss, caused by handling with a quantitative role overload, lessens the employee’s ability to cope with surface acting. The resource loss cycle represents a vicious circle that amplifies the resource loss caused by surface acting. Surface acting reduces the level of one’s resources. Furthermore, surface acting reduces JAW and resources more strongly when an individual has low levels of previous energy resources than it reduces JAW and resources when he or she has high levels of previous energy resources.

  7. The AMMA-CATCH Gourma observatory site in Mali: Relating climatic variations to changes in vegetation, surface hydrology, fluxes and natural resources

    Science.gov (United States)

    Mougin, E.; Hiernaux, P.; Kergoat, L.; Grippa, M.; de Rosnay, P.; Timouk, F.; Le Dantec, V.; Demarez, V.; Lavenu, F.; Arjounin, M.; Lebel, T.; Soumaguel, N.; Ceschia, E.; Mougenot, B.; Baup, F.; Frappart, F.; Frison, P. L.; Gardelle, J.; Gruhier, C.; Jarlan, L.; Mangiarotti, S.; Sanou, B.; Tracol, Y.; Guichard, F.; Trichon, V.; Diarra, L.; Soumaré, A.; Koité, M.; Dembélé, F.; Lloyd, C.; Hanan, N. P.; Damesin, C.; Delon, C.; Serça, D.; Galy-Lacaux, C.; Seghieri, J.; Becerra, S.; Dia, H.; Gangneron, F.; Mazzega, P.

    2009-08-01

    SummaryThe Gourma site in Mali is one of the three instrumented meso-scale sites deployed in West-Africa as part of the African Monsoon Multi-disciplinary Analysis (AMMA) project. Located both in the Sahelian zone sensu stricto, and in the Saharo-Sahelian transition zone, the Gourma meso-scale window is the northernmost site of the AMMA-CATCH observatory reached by the West African Monsoon. The experimental strategy includes deployment of a variety of instruments, from local to meso-scale, dedicated to monitoring and documentation of the major variables characterizing the climate forcing, and the spatio-temporal variability of surface processes and state variables such as vegetation mass, leaf area index (LAI), soil moisture and surface fluxes. This paper describes the Gourma site, its associated instrumental network and the research activities that have been carried out since 1984. In the AMMA project, emphasis is put on the relations between climate, vegetation and surface fluxes. However, the Gourma site is also important for development and validation of satellite products, mainly due to the existence of large and relatively homogeneous surfaces. The social dimension of the water resource uses and governance is also briefly analyzed, relying on field enquiry and interviews. The climate of the Gourma region is semi-arid, daytime air temperatures are always high and annual rainfall amounts exhibit strong inter-annual and seasonal variations. Measurements sites organized along a north-south transect reveal sharp gradients in surface albedo, net radiation, vegetation production, and distribution of plant functional types. However, at any point along the gradient, surface energy budget, soil moisture and vegetation growth contrast between two main types of soil surfaces and hydrologic systems. On the one hand, sandy soils with high water infiltration rates and limited run-off support almost continuous herbaceous vegetation with scattered woody plants. On the other

  8. The annual cycle of satellite derived sea surface temperature on the western South Atlantic shelf

    Directory of Open Access Journals (Sweden)

    Carlos A. D. Lentini

    2000-01-01

    Full Text Available In this article, thirteen years of weekly sea surface temperature (SST fields derived from NOAA Advanced Very High Resolution Radiometer global area coverage infrared satellite data, from January 1982 to December 1994, are used to investigate spatial and temporal variabilities of SST seasonal cycle in the Southwest Atlantic Oceano This work addresses large scale variations over the eastem South American continental shelf and slope regions limited offshore by the 1000-m isobath, between 42° and 22°S. SST time series are fit with annual and semi-annual harmonics to describe the annual variation of sea surface temperatures. The annual harmonic explains a large proportion of the SST variability. The coefficient of determination is highest (> 90% on the continental shelf, decreasing offshore. The estimated amplitude of the seasonal cycle ranges between 4° and 13°e throughout the study area, with minima in August­September and maxima in February-March. After the identification and removal of the dominant annual components ofSST variability, models such as the one presented here are an attractive tool to study interannual SST variability.Neste artigo, treze anos de imagens semanais da temperatura da superfície do mar (TSM obtidas através do sensor infravermelho Advanced Very High Resolution Radiometer a bordo dos satélites NOAA, de janeiro de 1982 a dezembro de 1994, são utlilizadas para investigar as variabilidades espacial e temporal do cicIo sazonal de TSM no Oceano Atlântico Sudoeste. Este trabalho objetiva as variações de larga escala sobre a plataforma continental e o talude leste da América do Sul limitados ao largo pela isóbata de 1000 metros, entre 42°5 e 22°S. As séries temporais de TSM são ajustadas aos .harmônicos anual e sem i-anual para descrever a variação anual das temperaturas da superfície do mar. O harmônico anual explica a maior parte da variabilidade da TSM. O coeficiente de determinação é alto (> 90

  9. Thermal-hydrological models

    Energy Technology Data Exchange (ETDEWEB)

    Buscheck, T., LLNL

    1998-04-29

    This chapter describes the physical processes and natural and engineered system conditions that affect thermal-hydrological (T-H) behavior in the unsaturated zone (UZ) at Yucca Mountain and how these effects are represented in mathematical and numerical models that are used to predict T-H conditions in the near field, altered zone, and engineered barrier system (EBS), and on waste package (WP) surfaces.

  10. Development of a Thin Film Primary Surface Heat Exchanger for Advanced Power Cycles

    Energy Technology Data Exchange (ETDEWEB)

    Allison, Tim [Southwest Research Inst., San Antonio, TX (United States); Beck, Griffin [Southwest Research Inst., San Antonio, TX (United States); Bennett, Jeffrey [Southwest Research Inst., San Antonio, TX (United States); Hoopes, Kevin [Southwest Research Inst., San Antonio, TX (United States); Miller, Larry [Southwest Research Inst., San Antonio, TX (United States)

    2016-06-29

    This project objective is to develop a high-temperature design upgrade for an existing primary surface heat exchanger so that the redesigned hardware is capable of operation in CO2 at temperatures up to 1,510°F (821°C) and pressure differentials up to 130 psi (9 bar). The heat exchanger is proposed for use as a recuperator in an advanced low-pressure oxy-fuel Brayton cycle that is predicted to achieve over 50% thermodynamic efficiency, although the heat exchanger could also be used in other high-temperature, low-differential pressure cycles. This report describes the progress to date, which includes continuing work performed to select and test new candidate materials for the recuperator redesign, final mechanical and thermal performance analysis results of various redesign concepts, and the preliminary design of a test loop for the redesigned recuperator including a budgetary estimate for detailed test loop design, procurement, and test operation. A materials search was performed in order to investigate high-temperature properties of many candidate materials, including high-temperature strength and nickel content. These properties were used to rank the candidate materials, resulting in a reduced list of nine materials for corrosion testing. Multiple test rigs were considered and analyzed for short-term corrosion testing and Thermal Gravimetric Analysis (TGA) was selected as the most cost-effective option for evaluating corrosion resistance of the candidate materials. In addition, tantalum, niobium, and chromium coatings were identified as potential options for increased corrosion resistance. The test results show that many materials exhibit relatively low weight gain rates, and that niobium and tantalum coatings may improve corrosion resistance for many materials, while chromium coatings appear to oxidize and debond quickly. Metallurgical analysis of alloys was also performed, showing evidence of intergranular attack in 282 that may cause long

  11. Fluorine uptake into the human enamel surface from fluoride-containing sealing materials during cariogenic pH cycling

    Science.gov (United States)

    Yasuhiro, Matsuda; Katsushi, Okuyama; Hiroko, Yamamoto; Hisanori, Komatsu; Masashi, Koka; Takahiro, Sato; Naoki, Hashimoto; Saiko, Oki; Chiharu, Kawamoto; Hidehiko, Sano

    2015-04-01

    To prevent the formation of caries and reduce dentin hypersensitivity, sealing materials, either with or without fluoride, are generally applied on the tooth in clinical practice. Application of fluoride-free sealing materials results in the formation of an acid-resistant layer on the tooth surface. On the other hand, fluoride-containing sealing materials might not only form an acid-resistant layer but could possibly further provide fluoride to enhance remineralization and reduce demineralization. In this study, the demineralization prevention ability and fluorine uptake rate in human enamel of fluoride-containing sealing materials ["MS coats F" (MSF)] and fluoride-free sealing materials ("hybrid coats 2" [HI]) were evaluated using an automatic pH cycling system. Each material was applied to the original tooth surface, the cut surfaces were covered with sticky wax, and the automatic pH-cycling system simulated daily acid changes (pH 6.8-4.5) occurring in the oral cavity for 4 weeks. Caries progression was analyzed using transverse microradiography (TMR) taken pre and post the 4 weeks of pH cycling. The fluorine and calcium distributions in the carious lesion in each specimen were evaluated using the proton-induced gamma emission (PIGE) and proton-induced X-ray (PIXE) techniques, respectively. TMR analysis showed that both MSF and HI had a caries-preventing effect after 4 weeks of pH cycling. PIGE/PIXE analysis demonstrated that only MSF resulted in fluoride uptake in the enamel surface. Therefore, MSF can help to form an acid-resistant layer and provide fluoride to the enamel surface. The presence of fluoride on the enamel surface suggested that MSF could prevent demineralization, even if the acid-resistant layer was removed, in clinical settings. The data obtained using the PIGE and PIXE techniques are useful for understanding the benefits of the use of a fluoride-containing sealing material for preventing caries.

  12. Improving the representation of river-groundwater interactions in land surface modeling at the regional scale: Observational evidence and parameterization applied in the Community Land Model

    KAUST Repository

    Zampieri, Matteo; Serpetzoglou, Efthymios; Anagnostou, Emmanouil N.; Nikolopoulos, Efthymios I.; Papadopoulos, Anastasios

    2012-01-01

    Groundwater is an important component of the hydrological cycle, included in many land surface models to provide a lower boundary condition for soil moisture, which in turn plays a key role in the land-vegetation-atmosphere interactions

  13. Development of a real-time hydrological cycle - rice growth coupled simulation system as a tool for farmers' decision making in an ungauged basin in Cambodia for the better agricultural water resources management

    Science.gov (United States)

    Tsujimoto, K.; Ohta, T.; Yasukawa, M.; Koike, T.; Kitsuregawa, M.; Homma, K.

    2013-12-01

    The entire country of Cambodia depends on agriculture for its economy. Rice is the staple food, making it the major agricultural product (roughly 80% of total national production). The target area of this study is western Cambodia, where rice production is the greatest in the country and most land is rainfed. Since most farmers rely only on their (non-science-based) experience, they would not adjust to changing rainfall and degraded water resources under climate change, so food security in the region would be seriously threatened (Monichoth et al., 2013). Under this condition, irrigation master plans are being considered by several ODA projects. This study aims to contribute to the design of such irrigation plans through the development of a real-time hydrological cycle - rice growth coupled simulation system. The purpose of the development of this system is to support decision making 1) for determining the necessary agricultural water resources and 2) for allocating limited water resources to various sectors. Rice growing condition as affected by water stress due to the water shortage is supposed to be shown for both of the cases with and without irrigation for several rainfall patterns. A dynamically coupled model of a distributed hydrological model (WEB-DHM., Wang et al., 2009) and a rice growth model (SIMRIW-rainfed, Homma et al., 2009) has been developed with a simple irrigation model. The target basin, a small basin in western Cambodia, is basically an ungauged basin and the model was validated by soil moisture, LAI, dry matter production of the rice crop, and rice yield, using both intensive field observation and satellite observations. Calibrating hourly satellite precipitation dataset (GSMaP/NRT) using ground rain gauges, hydrological cycle (soil moisture at three layers, river discharge, irrigatable water amount, water level of each paddy field, water demand of each paddy field, etc.) and rice growth (LAI, developmental index of the rice crop, dry matter

  14. HOBE – a hydrological observatory

    DEFF Research Database (Denmark)

    Jensen, Karsten Høgh; Illangasekare, Tissa

    2011-01-01

    In this paper a short introducO on is given to the Danish hydrological observatory—HOBE. We describe characteristics of the catchment, which is subject to experimental and modeling investigations. An overview is given of the research reported in this special section of the journal, which includes...... 11 papers of original research covering precipitation, evapotranspiration, emission of greenhouse gasses, unsaturated flow, groundwater–surface water interaction, and climate change impacts on hydrology....

  15. Modelling of hydrologic processes and potential response to climate change through the use of a multisite SWAT

    DEFF Research Database (Denmark)

    Gül, G.O.; Rosbjerg, Dan

    2010-01-01

    Hydrologic models that use components for integrated modelling of surface water and groundwater systems help conveniently simulate the dynamically linked hydrologic and hydraulic processes that govern flow conditions in watersheds. The Soil and Water Assessment Tool (SWAT) is one such model...... that allows continuous simulations over long time periods in the land phase of the hydrologic cycle by incorporating surface water and groundwater interactions. This study provides a verified structure for the SWAT to evaluate existing flow regimes in a small-sized catchment in Denmark and examines a simple...... simulation to help quantify the effects of climate change on regional water quantities. SWAT can be regarded among the alternative hydrologic simulation tools applicable for catchments with similar characteristics and of similar sizes in Denmark. However, the modellers would be required to determine a proper...

  16. Remote sensing estimates of impervious surfaces for hydrological modelling of changes in flood risk during high-intensity rainfall events

    DEFF Research Database (Denmark)

    Kaspersen, Per Skougaard; Fensholt, Rasmus; Drews, Martin

    This paper addresses the accuracy and applicability of medium resolution (MR) remote sensing estimates of impervious surfaces (IS) for urban land cover change analysis. Landsat-based vegetation indices (VI) are found to provide fairly accurate measurements of sub-pixel imperviousness for urban...... areas at different geographical locations within Europe, and to be applicable for cities with diverse morphologies and dissimilar climatic and vegetative conditions. Detailed data on urban land cover changes can be used to examine the diverse environmental impacts of past and present urbanisation...

  17. The geographic distribution of strontium isotopes in Danish surface waters - A base for provenance studies in archaeology, hydrology and agriculture

    DEFF Research Database (Denmark)

    Frei, Karin Margarita; Frei, Robert

    2011-01-01

    is consequently not readily transferred into the shallow-rooting plants and into small herbivores feeding on them. Since drinking water is a likely important source of Sr uptake of humans and larger animals, the contention is that a surface water isotopic composition can potentially characterize the bio...... some notable exceptions) neither mirror the pre-Quarternary bedrock geology nor a (Pleistocene) soil-type distribution map of Denmark. As a conservative suggestion, the use of the average 87Sr/86Sr ratio of 0.7096 ± 0.0015 (2r) is recommended as an average for bio-available Sr from within Denmark...

  18. A comprehensive approach to identify dominant controls of the behavior of a land surface-hydrology model across various hydroclimatic conditions

    Science.gov (United States)

    Haghnegahdar, Amin; Elshamy, Mohamed; Yassin, Fuad; Razavi, Saman; Wheater, Howard; Pietroniro, Al

    2017-04-01

    Complex physically-based environmental models are being increasingly used as the primary tool for watershed planning and management due to advances in computation power and data acquisition. Model sensitivity analysis plays a crucial role in understanding the behavior of these complex models and improving their performance. Due to the non-linearity and interactions within these complex models, Global sensitivity analysis (GSA) techniques should be adopted to provide a comprehensive understanding of model behavior and identify its dominant controls. In this study we adopt a multi-basin multi-criteria GSA approach to systematically assess the behavior of the Modélisation Environmentale-Surface et Hydrologie (MESH) across various hydroclimatic conditions in Canada including areas in the Great Lakes Basin, Mackenzie River Basin, and South Saskatchewan River Basin. MESH is a semi-distributed physically-based coupled land surface-hydrology modelling system developed by Environment and Climate Change Canada (ECCC) for various water resources management purposes in Canada. We use a novel method, called Variogram Analysis of Response Surfaces (VARS), to perform sensitivity analysis. VARS is a variogram-based GSA technique that can efficiently provide a spectrum of sensitivity information across a range of scales within the parameter space. We use multiple metrics to identify dominant controls of model response (e.g. streamflow) to model parameters under various conditions such as high flows, low flows, and flow volume. We also investigate the influence of initial conditions on model behavior as part of this study. Our preliminary results suggest that this type of GSA can significantly help with estimating model parameters, decreasing calibration computational burden, and reducing prediction uncertainty.

  19. Hydrological Modelling the Middle Magdalena Valley (Colombia)

    Science.gov (United States)

    Arenas, M. C.; Duque, N.; Arboleda, P.; Guadagnini, A.; Riva, M.; Donado-Garzon, L. D.

    2017-12-01

    Hydrological distributed modeling is key point for a comprehensive assessment of the feedback between the dynamics of the hydrological cycle, climate conditions and land use. Such modeling results are markedly relevant in the fields of water resources management, natural hazards and oil and gas industry. Here, we employ TopModel (TOPography based hydrological MODEL) for the hydrological modeling of an area in the Middle Magdalena Valley (MMV), a tropical basin located in Colombia. This study is located over the intertropical convergence zone and is characterized by special meteorological conditions, with fast water fluxes over the year. It has been subject to significant land use changes, as a result of intense economical activities, i.e., and agriculture, energy and oil & gas production. The model employees a record of 12 years of daily precipitation and evapotranspiration data as inputs. Streamflow data monitored across the same time frame are used for model calibration. The latter is performed by considering data from 2000 to 2008. Model validation then relies on observations from 2009 to 2012. The robustness of our analyses is based on the Nash-Sutcliffe coefficient (values of this metric being 0.62 and 0.53, respectively for model calibration and validation). Our results reveal high water storage capacity in the soil, and a marked subsurface runoff, consistent with the characteristics of the soil types in the regions. A significant influence on runoff response of the basin to topographical factors represented in the model is evidenced. Our calibrated model provides relevant indications about recharge in the region, which is important to quantify the interaction between surface water and groundwater, specially during the dry season, which is more relevant in climate-change and climate-variability scenarios.

  20. Exotic Homoclinic Surface of a Saddle-Node Limit Cycle in a Leech Neuron Model

    Science.gov (United States)

    Yooer, Chi-Feng; Wei, Fang; Xu, Jian-Xue; Zhang, Xin-Hua

    2011-03-01

    We carry out numerical and theoretical investigations on the global unstable invariant set (manifold) of a saddle-node limit cycle in a leech heart interneuron model. The corresponding global bifurcation is accompanied by an explosion of secondary bifurcations of limit cycles and the emergence of loop-shaped bifurcation structures. The dynamical behaviors of the trajectories of the invariant set are very complicated and can only be partially explained by existing theories.

  1. netherland hydrological modeling instrument

    Science.gov (United States)

    Hoogewoud, J. C.; de Lange, W. J.; Veldhuizen, A.; Prinsen, G.

    2012-04-01

    Netherlands Hydrological Modeling Instrument A decision support system for water basin management. J.C. Hoogewoud , W.J. de Lange ,A. Veldhuizen , G. Prinsen , The Netherlands Hydrological modeling Instrument (NHI) is the center point of a framework of models, to coherently model the hydrological system and the multitude of functions it supports. Dutch hydrological institutes Deltares, Alterra, Netherlands Environmental Assessment Agency, RWS Waterdienst, STOWA and Vewin are cooperating in enhancing the NHI for adequate decision support. The instrument is used by three different ministries involved in national water policy matters, for instance the WFD, drought management, manure policy and climate change issues. The basis of the modeling instrument is a state-of-the-art on-line coupling of the groundwater system (MODFLOW), the unsaturated zone (metaSWAP) and the surface water system (MOZART-DM). It brings together hydro(geo)logical processes from the column to the basin scale, ranging from 250x250m plots to the river Rhine and includes salt water flow. The NHI is validated with an eight year run (1998-2006) with dry and wet periods. For this run different parts of the hydrology have been compared with measurements. For instance, water demands in dry periods (e.g. for irrigation), discharges at outlets, groundwater levels and evaporation. A validation alone is not enough to get support from stakeholders. Involvement from stakeholders in the modeling process is needed. There fore to gain sufficient support and trust in the instrument on different (policy) levels a couple of actions have been taken: 1. a transparent evaluation of modeling-results has been set up 2. an extensive program is running to cooperate with regional waterboards and suppliers of drinking water in improving the NHI 3. sharing (hydrological) data via newly setup Modeling Database for local and national models 4. Enhancing the NHI with "local" information. The NHI is and has been used for many

  2. Hydrogeological, hydrochemical and isotope-hydrological investigations of surface and crevice waters in the Grimsel area (Switzerland)

    International Nuclear Information System (INIS)

    Keppler, A.

    1995-12-01

    The Grimsel rock laboratory (Hasli valley, Berner Oberland, Switzerland) has been used since 1984 by NAGRA (Nationale Genossenschaft fuer die Lagerung radioaktiver Abfaelle, Wettingen, Switzerland). It is about 450 metres deep under the Juchli ridge in the crystalline rock basement of the Aar massif. Within the framework of an international cooperation, a great many research topics in connection with the underground storage of radioactive waste are being studied at this location. Their focus is, inter alia, on the following: hydrogeological investigations of crevice water movement, investigations of geophysical structures and rock tension measurements, migration of radionuclides in an individual crevice. So far, hydrogeological and hydrogeochemical conditions have only been studied as far as they related to the needs of individual investigations, and systematic information on global waterways in the Juchli basement was scarce. By contrast, this work aimed at the chemical characterization of surface and spring waters in the catchment area of the rock laboratory as well as the crevice waters in the day-drift system, the description of the chemical development of the waters during their passage through the crevice system, and the assessment of the mean underground retention time of crevice waters by means of different stable and radioactive isotopes. In addition, hydrogeological mapping of the system of waters above ground and crevice water accesses underground was carried out. (orig./SR) [de

  3. Effects of vegetation and soil-surface cover treatments on the hydrologic behavior of low-level waste trench caps

    International Nuclear Information System (INIS)

    Lopez, E.A.; Barnes, F.J.; Antonio, E.J.

    1988-01-01

    Preliminary results are presented on a three-year field study at Los Alamos National Laboratory to evaluate the influence of different low-level radioactive waste trench cap designs on water balance under natural precipitation. Erosion plots having two different vegetative covers (shrubs and grasses) and with either gravel-mulched or unmulched soil surface treatments have been established on three different soil profiles on a decommissioned waste site. Total runoff and soil loss from each plot is measured after each precipitation event. Soil moisture is measured biweekly while plant canopy cover is measured seasonally. Preliminary results from the first year show that the application of a gravel mulch reduced runoff by 73 to 90%. Total soil loss was reduced by 83 to 93% by the mulch treatment. On unmulched plots, grass cover reduced both runoff and soil loss by about 50% compared to the shrub plots. Continued monitoring of the study site will provide data that will be used to analyze complex interactions between independent variables such rainfall amount and intensity, antecedent soil moisture, and soil and vegetation factors, as they influence water balance, and soil erosion. 18 refs., 2 figs., 3 tabs

  4. A reduced-order modeling approach to represent subgrid-scale hydrological dynamics for land-surface simulations: application in a polygonal tundra landscape

    Science.gov (United States)

    Pau, G. S. H.; Bisht, G.; Riley, W. J.

    2014-09-01

    Existing land surface models (LSMs) describe physical and biological processes that occur over a wide range of spatial and temporal scales. For example, biogeochemical and hydrological processes responsible for carbon (CO2, CH4) exchanges with the atmosphere range from the molecular scale (pore-scale O2 consumption) to tens of kilometers (vegetation distribution, river networks). Additionally, many processes within LSMs are nonlinearly coupled (e.g., methane production and soil moisture dynamics), and therefore simple linear upscaling techniques can result in large prediction error. In this paper we applied a reduced-order modeling (ROM) technique known as "proper orthogonal decomposition mapping method" that reconstructs temporally resolved fine-resolution solutions based on coarse-resolution solutions. We developed four different methods and applied them to four study sites in a polygonal tundra landscape near Barrow, Alaska. Coupled surface-subsurface isothermal simulations were performed for summer months (June-September) at fine (0.25 m) and coarse (8 m) horizontal resolutions. We used simulation results from three summer seasons (1998-2000) to build ROMs of the 4-D soil moisture field for the study sites individually (single-site) and aggregated (multi-site). The results indicate that the ROM produced a significant computational speedup (> 103) with very small relative approximation error (training the ROM. We also demonstrate that our approach: (1) efficiently corrects for coarse-resolution model bias and (2) can be used for polygonal tundra sites not included in the training data set with relatively good accuracy (< 1.7% relative error), thereby allowing for the possibility of applying these ROMs across a much larger landscape. By coupling the ROMs constructed at different scales together hierarchically, this method has the potential to efficiently increase the resolution of land models for coupled climate simulations to spatial scales consistent with

  5. Microtomography evaluation of dental tissue wear surface induced by in vitro simulated chewing cycles on human and composite teeth

    Directory of Open Access Journals (Sweden)

    Rossella Bedini

    2012-01-01

    Full Text Available In this study a 3D microtomography display of tooth surfaces after in vitro dental wear tests has been obtained. Natural teeth have been compared with prosthetic teeth, manufactured by three different polyceramic composite materials. The prosthetic dental element samples, similar to molars, have been placed in opposition to human teeth extracted by paradontology diseases. After microtomography analysis, samples have been subjected to in vitro fatigue test cycles by servo-hydraulic mechanical testing machine. After the fatigue test, each sample has been subjected again to microtomography analysis to obtain volumetric value changes and dental wear surface images. Wear surface images were obtained by 3D reconstruction software and volumetric value changes were measured by CT analyser software. The aim of this work has been to show the potential of microtomography technique to display very clear and reliable wear surface images. Microtomography analysis methods to evaluate volumetric value changes have been used to quantify dental tissue and composite material wear.

  6. Roughing in Human Replumbing of the Water Cycle: Challenges, Opportunities, and Progress in Capturing the Influence of Water Management in Regional Models of Hydrology and Climate

    Science.gov (United States)

    Flores, A. N.; Kaiser, K. E.; Steimke, A.; Leonard, A.; FitzGerald, K.; Benner, S. G.; Vache, K. B.; Hillis, V.; Bolte, J.; Han, B.

    2017-12-01

    projects illustrate significant improvements in modeling human modification of the timing and partitioning of hydrologic fluxes. Important challenges and opportunities remain, however, particularly in improving modeling the interactions between and among actors that exert controls on the redistribution of water.

  7. Influence of surface finish on the high cycle fatigue behavior of a 304L austenitic stainless steel

    International Nuclear Information System (INIS)

    Petitjean, S.

    2003-06-01

    This work has dealt with the influence of surface finish on the high cycle fatigue behavior of a 304L. The role played by roughness, surface hardening and residual stresses has been particularly described. First part of this study has consisted of the production of several surface finishes. These latter were obtained by turning, grinding, mechanical polishing and sandblasting. The obtained surfaces were then characterised in terms of roughness, hardening, microstructure and residual stresses. Fatigue tests were finally conducted under various stress ratios or mean stresses at two temperatures (25 C and 300 C). Results clearly evidenced an effect of the surface integrity on the fatigue resistance of the 304L. This influence is nevertheless more pronounced at ambient temperature and for a positive mean stress. For all explored testing conditions, the lowest endurance limit was obtained for ground specimens whereas polished samples exhibited the best fatigue strength. Results also cleared out a detrimental influence of a positive mean stress in the case of specimens having surface defaults of a great acuity. The study of the relative effect of each of the surface parameter, under a positive stress ratio and at the ambient temperature, showed that roughness profile and surface hardening are the two more influential factors. The role of the residual stresses remains negligible due to their rapid relaxation during the application of the first cycles of fatigue. The estimation of the initiation and propagation periods showed that mechanisms differed as a function of the applied stress ratio. Crack propagation is governed by the parameter DK at a positive stress ratio and by Dep/2 in the case of tension-compression tests. (author)

  8. Making sense of Big Data in Hydrology (Invited)

    Science.gov (United States)

    Booth, N.; Blodgett, D. L.; Briar, D.

    2013-12-01

    At the same time that "big data" promises to help provide new insights for understanding earth processes, budget challenges require we more effectively use data collected by organizations other than our own. Answering societally relevant questions related to water requires that we consider all natural and anthropogenic aspects of the hydrologic cycle. How do we integrate across organizations and across water cycle components to satisfy these challenges and expectations? We now need to move beyond metadata that describe individual datasets to an ability to interrogate integrated collections of observations. Furthermore, we need to be able to query across obvious (yet elusive) dimensions including hydrologic context and position while filtering for data of a known quality that meets our purpose. In addition, we need to traverse the climate/geography interface, efficiently attributing a climate signal to watersheds. We know that water flows downhill and that after heavy rain, streams flood. But we cannot systematically query for observations made during a flashy summer storm-related flood upstream from notable points on a river or stream such as water treatment intakes. USGS has long committed to providing real-time access to surface and groundwater monitoring networks across the United States. Of the over 45 million requests made for these data in a recent month, nearly a quarter were made via mobile devices. An additional 19.8 million requests were made to web services that provide content according to community and international data standards -- presumably to support other applications and mash ups. This presentation will describe ongoing efforts at the USGS on how we are working with the earth sciences and water resource management communities to develop and implement new techniques for both delivering and consuming hydrologic data. Our strategy has been an "all-of-the-above" approach whereby we recognize and work to advance best practices in various communities

  9. Wetland Hydrology | Science Inventory | US EPA

    Science.gov (United States)

    This chapter discusses the state of the science in wetland hydrology by touching upon the major hydraulic and hydrologic processes in these complex ecosystems, their measurement/estimation techniques, and modeling methods. It starts with the definition of wetlands, their benefits and types, and explains the role and importance of hydrology on wetland functioning. The chapter continues with the description of wetland hydrologic terms and related estimation and modeling techniques. The chapter provides a quick but valuable information regarding hydraulics of surface and subsurface flow, groundwater seepage/discharge, and modeling groundwater/surface water interactions in wetlands. Because of the aggregated effects of the wetlands at larger scales and their ecosystem services, wetland hydrology at the watershed scale is also discussed in which we elaborate on the proficiencies of some of the well-known watershed models in modeling wetland hydrology. This chapter can serve as a useful reference for eco-hydrologists, wetland researchers and decision makers as well as watershed hydrology modelers. In this chapter, the importance of hydrology for wetlands and their functional role are discussed. Wetland hydrologic terms and the major components of water budget in wetlands and how they can be estimated/modeled are also presented. Although this chapter does not provide a comprehensive coverage of wetland hydrology, it provides a quick understanding of the basic co

  10. An explanation for the different climate sensitivities of land and ocean surfaces based on the diurnal cycle

    Directory of Open Access Journals (Sweden)

    A. Kleidon

    2017-09-01

    Full Text Available Observations and climate model simulations consistently show a higher climate sensitivity of land surfaces compared to ocean surfaces. Here we show that this difference in temperature sensitivity can be explained by the different means by which the diurnal variation in solar radiation is buffered. While ocean surfaces buffer the diurnal variations by heat storage changes below the surface, land surfaces buffer it mostly by heat storage changes above the surface in the lower atmosphere that are reflected in the diurnal growth of a convective boundary layer. Storage changes below the surface allow the ocean surface–atmosphere system to maintain turbulent fluxes over day and night, while the land surface–atmosphere system maintains turbulent fluxes only during the daytime hours, when the surface is heated by absorption of solar radiation. This shorter duration of turbulent fluxes on land results in a greater sensitivity of the land surface–atmosphere system to changes in the greenhouse forcing because nighttime temperatures are shaped by radiative exchange only, which are more sensitive to changes in greenhouse forcing. We use a simple, analytic energy balance model of the surface–atmosphere system in which turbulent fluxes are constrained by the maximum power limit to estimate the effects of these different means to buffer the diurnal cycle on the resulting temperature sensitivities. The model predicts that land surfaces have a 50 % greater climate sensitivity than ocean surfaces, and that the nighttime temperatures on land increase about twice as much as daytime temperatures because of the absence of turbulent fluxes at night. Both predictions compare very well with observations and CMIP5 climate model simulations. Hence, the greater climate sensitivity of land surfaces can be explained by its buffering of diurnal variations in solar radiation in the lower atmosphere.

  11. Using stable isotopes to assess surface water source dynamics and hydrological connectivity in a high-latitude wetland and permafrost influenced landscape

    Science.gov (United States)

    Ala-aho, P.; Soulsby, C.; Pokrovsky, O. S.; Kirpotin, S. N.; Karlsson, J.; Serikova, S.; Vorobyev, S. N.; Manasypov, R. M.; Loiko, S.; Tetzlaff, D.

    2018-01-01

    Climate change is expected to alter hydrological and biogeochemical processes in high-latitude inland waters. A critical question for understanding contemporary and future responses to environmental change is how the spatio-temporal dynamics of runoff generation processes will be affected. We sampled stable water isotopes in soils, lakes and rivers on an unprecedented spatio-temporal scale along a 1700 km transect over three years in the Western Siberia Lowlands. Our findings suggest that snowmelt mixes with, and displaces, large volumes of water stored in the organic soils and lakes to generate runoff during the thaw season. Furthermore, we saw a persistent hydrological connection between water bodies and the landscape across permafrost regions. Our findings help to bridge the understanding between small and large scale hydrological studies in high-latitude systems. These isotope data provide a means to conceptualise hydrological connectivity in permafrost and wetland influenced regions, which is needed for an improved understanding of future biogeochemical changes.

  12. Surface and interfacial reaction study of half cycle atomic layer deposited HfO{sub 2} on chemically treated GaSb surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Zhernokletov, D. M. [Department of Physics, University of Texas at Dallas, Richardson, Texas 75080 (United States); Dong, H.; Brennan, B.; Kim, J. [Department of Materials Science and Engineering, University of Texas at Dallas, Richardson, Texas 75080 (United States); Yakimov, M.; Tokranov, V.; Oktyabrsky, S. [College of Nanoscale Science and Engineering, University at Albany - SUNY, Albany, New York 12203 (United States); Wallace, R. M. [Department of Physics, University of Texas at Dallas, Richardson, Texas 75080 (United States); Department of Materials Science and Engineering, University of Texas at Dallas, Richardson, Texas 75080 (United States)

    2013-04-01

    An in situ half-cycle atomic layer deposition/X-ray photoelectron spectroscopy (XPS) study was conducted in order to investigate the evolution of the HfO{sub 2} dielectric interface with GaSb(100) surfaces after sulfur passivation and HCl etching, designed to remove the native oxides. With the first pulses of tetrakis(dimethylamido)hafnium(IV) and water, a decrease in the concentration of antimony oxide states present on the HCl-etched surface is observed, while antimony sulfur states diminished below the XPS detection limit on sulfur passivated surface. An increase in the amount of gallium oxide/sulfide is seen, suggesting oxygen or sulfur transfers from antimony to gallium during antimony oxides/sulfides decomposition.

  13. Experimental study of microstructure changes due to low cycle fatigue of a steel nanocrystallised by Surface Mechanical Attrition Treatment (SMAT)

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Z. [ICD, P2MN, LASMIS, University of Technology of Troyes, UMR 6281, CNRS, Troyes (France); Retraint, D., E-mail: delphine.retraint@utt.fr [ICD, P2MN, LASMIS, University of Technology of Troyes, UMR 6281, CNRS, Troyes (France); Baudin, T.; Helbert, A.L.; Brisset, F. [ICMMO, Univ Paris-Sud, Université Paris-Saclay, UMR CNRS 8182, 91405 Orsay Cedex (France); Chemkhi, M.; Zhou, J. [ICD, P2MN, LASMIS, University of Technology of Troyes, UMR 6281, CNRS, Troyes (France); Kanouté, P. [ICD, P2MN, LASMIS, University of Technology of Troyes, UMR 6281, CNRS, Troyes (France); ONERA, The French Aerospace Lab, 29 avenue de la Division Leclerc, 92322 Chatillon Cedex (France)

    2017-02-15

    Electron Backscatter Diffraction technique is used to characterize the microstructure of 316L steel generated by Surface Mechanical Attrition Treatment (SMAT) before and after low cycle fatigue tests. A grain size gradient is generated from the top surface to the interior of the samples after SMAT so that three main regions can be distinguished below the treated surface: (i) the ultra-fine grain area within 5 μm under the top surface with preferably oriented grains, (ii) the intermediate area where the original grains are partially transformed, and (iii) the edge periphery area where the original grains are just mechanically deformed with the presence of plastic slips. Fatigue tests show that cyclic loading does not change the grain orientation spread and does not activate any plastic slip in the ultra-fine grain top surface area induced by SMAT. On the opposite, in the plastically SMAT affected region including the intermediate area and the edge periphery area, new slip systems are activated by low cycle fatigue while the grain orientation spread is increased. These results represent a first very interesting step towards the characterization and understanding of mechanical mechanisms involved during the fatigue of a grain size gradient material. - Highlights: •LCF tests are carried out on specimens processed by SMAT. •EBSD is used to investigate microstructural changes induced by LCF. •A grain size gradient is generated by SMAT from surface to the bulk of the fatigue samples. •New slip systems are activated by LCF and GOS is increased in plastically deformed region. •However, these phenomena are not observed in the top surface ultra-fine grain area.

  14. Experimental study of microstructure changes due to low cycle fatigue of a steel nanocrystallised by Surface Mechanical Attrition Treatment (SMAT)

    International Nuclear Information System (INIS)

    Sun, Z.; Retraint, D.; Baudin, T.; Helbert, A.L.; Brisset, F.; Chemkhi, M.; Zhou, J.; Kanouté, P.

    2017-01-01

    Electron Backscatter Diffraction technique is used to characterize the microstructure of 316L steel generated by Surface Mechanical Attrition Treatment (SMAT) before and after low cycle fatigue tests. A grain size gradient is generated from the top surface to the interior of the samples after SMAT so that three main regions can be distinguished below the treated surface: (i) the ultra-fine grain area within 5 μm under the top surface with preferably oriented grains, (ii) the intermediate area where the original grains are partially transformed, and (iii) the edge periphery area where the original grains are just mechanically deformed with the presence of plastic slips. Fatigue tests show that cyclic loading does not change the grain orientation spread and does not activate any plastic slip in the ultra-fine grain top surface area induced by SMAT. On the opposite, in the plastically SMAT affected region including the intermediate area and the edge periphery area, new slip systems are activated by low cycle fatigue while the grain orientation spread is increased. These results represent a first very interesting step towards the characterization and understanding of mechanical mechanisms involved during the fatigue of a grain size gradient material. - Highlights: •LCF tests are carried out on specimens processed by SMAT. •EBSD is used to investigate microstructural changes induced by LCF. •A grain size gradient is generated by SMAT from surface to the bulk of the fatigue samples. •New slip systems are activated by LCF and GOS is increased in plastically deformed region. •However, these phenomena are not observed in the top surface ultra-fine grain area.

  15. On the behavior of surface electromyographic variables during the menstrual cycle

    International Nuclear Information System (INIS)

    Soares, Fabiano Araujo; Salomoni, Sauro Emerick; De Carvalho, Joao Luiz Azevedo; Nascimento, Francisco Assis de Oliveira; Veneziano, Wilson Henrique; Pires, Kenia Fonseca; Da Rocha, Adson Ferreira

    2011-01-01

    The goal of this work is to study the behavior of electromyographic variables during the menstrual cycle. Ten female volunteers (24.0 ± 2.8 years of age) performed fatiguing isometric contractions, and electromyographic signals were measured on the biceps brachii in four phases of the menstrual cycle. Adaptations of classical algorithms were used for the estimation of the root mean square (RMS) value, absolute rectified value (ARV), mean frequency (MNF), median frequency (MDF), and conduction velocity (CV). The CV estimator had a higher (p = 0.002) rate of decrease at the end of the follicular phase and at the end of the luteal phase. The MDF (p = 0.002) and MNF (p = 0.004) estimators had a higher rate of decrease at the beginning of the follicular phase and at the end of the luteal phase. No significant differences between phases of the menstrual cycle were detected with the ARV and RMS estimators (p > 0.05). These results suggest that the behavior of the muscles in women presents different characteristics during different phases of the menstrual cycle. In particular, women were more susceptible to fatigue at the end of the luteal phase

  16. Fluorine uptake into the human enamel surface from fluoride-containing sealing materials during cariogenic pH cycling

    Energy Technology Data Exchange (ETDEWEB)

    Yasuhiro, Matsuda, E-mail: matsuda@den.hokudai.ac.jp [Department of Restorative Dentistry, Graduate School of Dental Medicine Hokkaido University (Japan); Katsushi, Okuyama [Department of Restorative Dentistry, Graduate School of Dental Medicine Hokkaido University (Japan); Hiroko, Yamamoto [Graduate School of Dentistry, Osaka University (Japan); Hisanori, Komatsu [Department of Restorative Dentistry, Graduate School of Dental Medicine Hokkaido University (Japan); Masashi, Koka; Takahiro, Sato [Takasaki Advanced Radiation Research Institute, JAEA (Japan); Naoki, Hashimoto; Saiko, Oki; Chiharu, Kawamoto; Hidehiko, Sano [Department of Restorative Dentistry, Graduate School of Dental Medicine Hokkaido University (Japan)

    2015-04-01

    To prevent the formation of caries and reduce dentin hypersensitivity, sealing materials, either with or without fluoride, are generally applied on the tooth in clinical practice. Application of fluoride-free sealing materials results in the formation of an acid-resistant layer on the tooth surface. On the other hand, fluoride-containing sealing materials might not only form an acid-resistant layer but could possibly further provide fluoride to enhance remineralization and reduce demineralization. In this study, the demineralization prevention ability and fluorine uptake rate in human enamel of fluoride-containing sealing materials [“MS coats F” (MSF)] and fluoride-free sealing materials (“hybrid coats 2” [HI]) were evaluated using an automatic pH cycling system. Each material was applied to the original tooth surface, the cut surfaces were covered with sticky wax, and the automatic pH-cycling system simulated daily acid changes (pH 6.8–4.5) occurring in the oral cavity for 4 weeks. Caries progression was analyzed using transverse microradiography (TMR) taken pre and post the 4 weeks of pH cycling. The fluorine and calcium distributions in the carious lesion in each specimen were evaluated using the proton-induced gamma emission (PIGE) and proton-induced X-ray (PIXE) techniques, respectively. TMR analysis showed that both MSF and HI had a caries-preventing effect after 4 weeks of pH cycling. PIGE/PIXE analysis demonstrated that only MSF resulted in fluoride uptake in the enamel surface. Therefore, MSF can help to form an acid-resistant layer and provide fluoride to the enamel surface. The presence of fluoride on the enamel surface suggested that MSF could prevent demineralization, even if the acid-resistant layer was removed, in clinical settings. The data obtained using the PIGE and PIXE techniques are useful for understanding the benefits of the use of a fluoride-containing sealing material for preventing caries.

  17. Fluorine uptake into the human enamel surface from fluoride-containing sealing materials during cariogenic pH cycling

    International Nuclear Information System (INIS)

    Yasuhiro, Matsuda; Katsushi, Okuyama; Hiroko, Yamamoto; Hisanori, Komatsu; Masashi, Koka; Takahiro, Sato; Naoki, Hashimoto; Saiko, Oki; Chiharu, Kawamoto; Hidehiko, Sano

    2015-01-01

    To prevent the formation of caries and reduce dentin hypersensitivity, sealing materials, either with or without fluoride, are generally applied on the tooth in clinical practice. Application of fluoride-free sealing materials results in the formation of an acid-resistant layer on the tooth surface. On the other hand, fluoride-containing sealing materials might not only form an acid-resistant layer but could possibly further provide fluoride to enhance remineralization and reduce demineralization. In this study, the demineralization prevention ability and fluorine uptake rate in human enamel of fluoride-containing sealing materials [“MS coats F” (MSF)] and fluoride-free sealing materials (“hybrid coats 2” [HI]) were evaluated using an automatic pH cycling system. Each material was applied to the original tooth surface, the cut surfaces were covered with sticky wax, and the automatic pH-cycling system simulated daily acid changes (pH 6.8–4.5) occurring in the oral cavity for 4 weeks. Caries progression was analyzed using transverse microradiography (TMR) taken pre and post the 4 weeks of pH cycling. The fluorine and calcium distributions in the carious lesion in each specimen were evaluated using the proton-induced gamma emission (PIGE) and proton-induced X-ray (PIXE) techniques, respectively. TMR analysis showed that both MSF and HI had a caries-preventing effect after 4 weeks of pH cycling. PIGE/PIXE analysis demonstrated that only MSF resulted in fluoride uptake in the enamel surface. Therefore, MSF can help to form an acid-resistant layer and provide fluoride to the enamel surface. The presence of fluoride on the enamel surface suggested that MSF could prevent demineralization, even if the acid-resistant layer was removed, in clinical settings. The data obtained using the PIGE and PIXE techniques are useful for understanding the benefits of the use of a fluoride-containing sealing material for preventing caries

  18. Evaluation of the Effect of Surface Finish on High-Cycle Fatigue of SLM-IN718

    Science.gov (United States)

    Lambert, D. M.

    2016-01-01

    The surface finish of parts produced by additive manufacturing processes is much rougher than the surface finish generated by machining processes, and a rougher surface can reduce the fatigue strength of a part. This paper discusses an effort to quantify that reduction of strength in high-cycle fatigue for selective laser melt (SLM) coupons. A high-cycle fatigue (HCF) knockdown factor was estimated for Inconel 718, manufactured with the SLM process. This factor is the percentage reduction from the maximum stress in fatigue for low-stress ground (LSG) specimens to the maximum stress of those left with the original surface condition at the same fatigue life. Specimens were provided by a number of vendors, free to use their "best practice"; only one heat treat condition was considered; and several test temperatures were characterized, including room temperature, 800F, 1000F, and 1200F. The 1000F data had a large variance, and was omitted from consideration in this document. A first method used linear approximations extracted from the graphs, and only where data was available for both. A recommended knockdown factor of the as-built surface condition (average roughness of approximately 245 micro-inches/inch) versus low-stress ground condition (roughness no more than 4 micro-inches/inch) was established at approximately 1/3 or 33%. This is to say that for the as-built surface condition, a maximum stress of 2/3 of the stress for LSG can be expected to produce a similar life in the as-built surface condition. In this first evaluation, the knockdown factor did not appear to be a function of temperature. A second approach, the "KP method", incorporated the surface finish measure into a new parameter termed the pseudo-stress intensity factor, Kp, which was formulated to be similar to the fracture mechanics stress intensity factor. Using Kp, the variance seemed to be reduced across all sources, and knockdown factors were estimated using Kp over the range where data occurred. A

  19. Improved Ground Hydrology Calculations for Global Climate Models (GCMs): Soil Water Movement and Evapotranspiration.

    Science.gov (United States)

    Abramopoulos, F.; Rosenzweig, C.; Choudhury, B.

    1988-09-01

    A physically based ground hydrology model is developed to improve the land-surface sensible and latent heat calculations in global climate models (GCMs). The processes of transpiration, evaporation from intercepted precipitation and dew, evaporation from bare soil, infiltration, soil water flow, and runoff are explicitly included in the model. The amount of detail in the hydrologic calculations is restricted to a level appropriate for use in a GCM, but each of the aforementioned processes is modeled on the basis of the underlying physical principles. Data from the Goddard Institute for Space Studies (GISS) GCM are used as inputs for off-line tests of the ground hydrology model in four 8° × 10° regions (Brazil, Sahel, Sahara, and India). Soil and vegetation input parameters are calculated as area-weighted means over the 8° × 10° gridhox. This compositing procedure is tested by comparing resulting hydrological quantities to ground hydrology model calculations performed on the 1° × 1° cells which comprise the 8° × 10° gridbox. Results show that the compositing procedure works well except in the Sahel where lower soil water levels and a heterogeneous land surface produce more variability in hydrological quantities, indicating that a resolution better than 8° × 10° is needed for that region. Modeled annual and diurnal hydrological cycles compare well with observations for Brazil, where real world data are available. The sensitivity of the ground hydrology model to several of its input parameters was tested; it was found to be most sensitive to the fraction of land covered by vegetation and least sensitive to the soil hydraulic conductivity and matric potential.

  20. Changes in the Amplitude and Phase of the Annual Cycle: quantifying from surface wind series in China

    Science.gov (United States)

    Feng, Tao

    2013-04-01

    Climate change is not only reflected in the changes in annual means of climate variables but also in the changes in their annual cycles (seasonality), especially in the regions outside the tropics. Changes in the timing of seasons, especially the wind season, have gained much attention worldwide in recent decade or so. We introduce long-range correlated surrogate data to Ensemble Empirical Mode Decomposition method, which represent the statistic characteristics of data better than white noise. The new method we named Ensemble Empirical Mode Decomposition with Long-range Correlated noise (EEMD-LRC) and applied to 600 station wind speed records. This new method is applied to investigate the trend in the amplitude of the annual cycle of China's daily mean surface wind speed for the period 1971-2005. The amplitude of seasonal variation decrease significantly in the past half century over China, which can be well explained by Annual Cycle component from EEMD-LRC. Furthermore, the phase change of annual cycle lead to strongly shorten of wind season in spring, and corresponding with strong windy day frequency change over Northern China.