WorldWideScience

Sample records for rainfall river flows

  1. Distributional changes in rainfall and river flow in Sarawak, Malaysia

    Science.gov (United States)

    Sa'adi, Zulfaqar; Shahid, Shamsuddin; Ismail, Tarmizi; Chung, Eun-Sung; Wang, Xiao-Jun

    2017-11-01

    Climate change may not change the rainfall mean, but the variability and extremes. Therefore, it is required to explore the possible distributional changes of rainfall characteristics over time. The objective of present study is to assess the distributional changes in annual and northeast monsoon rainfall (November-January) and river flow in Sarawak where small changes in rainfall or river flow variability/distribution may have severe implications on ecology and agriculture. A quantile regression-based approach was used to assess the changes of scale and location of empirical probability density function over the period 1980-2014 at 31 observational stations. The results indicate that diverse variation patterns exist at all stations for annual rainfall but mainly increasing quantile trend at the lowers, and higher quantiles for the month of January and December. The significant increase in annual rainfall is found mostly in the north and central-coastal region and monsoon month rainfalls in the interior and north of Sarawak. Trends in river flow data show that changes in rainfall distribution have affected higher quantiles of river flow in monsoon months at some of the basins and therefore more flooding. The study reveals that quantile trend can provide more information of rainfall change which may be useful for climate change mitigation and adaptation planning.

  2. Impact analysis of satellite rainfall products on flow simulations in the Magdalena River Basin, Colombia

    Directory of Open Access Journals (Sweden)

    Amr Elgamal

    2017-02-01

    Full Text Available The Magdalena River is the most important river in Colombia in terms of economic activities and is home to about 77% of the country’s population. The river faces water resources allocation challenges, which require reliable hydrological assessments. However, hydrological analysis and model simulations are hampered by insufficient and uncertain knowledge of the actual rainfall fields. In this research the reliability of groundbased measurements, different satellite products of rainfall and their combinations are tested for their impact on the discharge simulations of the Magdalena River. Two different satellite rainfall products from the Tropical Rainfall Measuring Mission (TRMM, have been compared and merged with the ground-based measurements and their impact on the Magdalena river flows quantified using the Representative Elementary Watershed (REW distributed hydrological model.

  3. Rainfall Variability and Landuse Conversion Impacts to Sensitivity of Citarum River Flow

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    Dyah Marganingrum

    2013-07-01

    Full Text Available The objective of this study is to determine the sensitivity of Citarum river flow to climate change and land conversion. It will provide the flow information that required in the water resources sustainability. Saguling reservoir is one of the strategic reservoirs, which 75% water is coming from the inflow of Upper Citarum measured at Nanjung station. Climate variability was identified as rainfall variability. Sensitivity was calculated as the elasticity value of discharge using three-variate model of statistical approach. The landuse conversion was calculated used GIS at 1994 and 2004. The results showed that elasticity at the Nanjung station and Saguling station decreased from 1.59 and 1.02 to 0.68 and 0.62 respectively. The decreasing occurred in the before the dam was built period (1950-1980 to the after reservoirs operated period (1986-2008. This value indicates that: 1 Citarum river flow is more sensitive to rainfall variability that recorded at Nanjung station than Saguling station, 2 rainfall character is more difficult to predict. The landuse analysis shows that forest area decrease to ± 27% and built up area increased to ± 26%. Those implied a minimum rainfall reduction to± 8% and minimum flow to ± 46%. Those were caused by land conversion and describing that the vegetation have function to maintain the base flow for sustainable water resource infrastructure.

  4. Analysis of Debris Flow Kuranji River in Padang City Using Rainfall Data, Remote Sensing and Geographic Information System

    International Nuclear Information System (INIS)

    Umar, Z; Wan Mohd Akib, W A A; Ahmad, A

    2014-01-01

    Flash flood is the most common environmental hazard worldwide. This phenomenon is usually occurs due to intense and prolonged rainfall spells on saturated ground. When there is a rapid rise in water levels and high flow-velocities of the stream occur, the channel overflows and the result is a flash flood. Flash floods normally cause a dangerous wall of roaring water carrying rocks, mud and other debris. On Tuesday, July 24, 2012 at 18:00 pm, a flash flood (debris flow) struck Kuranji River whereby 19 urban villages in seven (7) sub-districts in the city of Padang were affected by this flood disaster. The temporary loss estimated is 40 Billion US Dollar reported by the West Sumatra Provincial Government due to many damages of the built environment infrastructures. This include damaged houses of 878 units, mosque 15 units, irrigation damaged 12 units, bridges 6 units, schools 2 units and health posts 1 unit. Generally, widely used methods for making a landslide study are Geographic Information System (GIS) and Remote Sensing techniques. The landslide information extracted from remotely sensed products is mainly related to morphology, vegetation and hydrologic conditions of a slope. While GIS is used to create a database, data management, data display and to analyze data such as thematic maps of land use/land cover, normalized difference vegetation index (NDVI), rainfall data and soil texture. This paper highlights the analysis of the condition of the Watershed Kuranji River experiencing flash floods, using remote sensing satellite image of Landsat ETM 7 in 2009 and 2012 and Geographic Information System (GIS). Furthermore, the data was analyzed to determine whether this flash flood occurred due to extreme rain or collapse of existing natural dams in the upstream of the Kuranji River

  5. Hydrological Effects of Historic Rainfall on the Waccamaw River

    Science.gov (United States)

    Jolly, J.; Bao, S.

    2017-12-01

    This study focuses on the overall water budget of the Waccamaw River during and after a historic rainfall event related to Hurricane Joaquin, producing a 1000-year rainfall event. While rainfall is the only input, it enters the basin through various means. Some rainwater enters the soil as soil moisture while rainfall also goes underground and enters the river channels from underground, which is defined as bucket in. Over time, the rainfall was removed from the river site through various natural processes. Those processes, including evaporation, soil storage as soil moisture, discharge runoff through the river channel, among others, were modeled and validated against the USGS gauge stations. The validated model results were then used to estimate the hydrological response of the Waccamaw River to the rainfall event and determine the overall water budget. The experiment was completed using a WRF-Hydro modeling system for the purposes of weather forecasting and meteorological analysis. Upon completion of the data analysis, the WRF-Hydro model result showed that large amounts of rainfall were variously dispersed through the aforementioned areas. It was determined that after entering the soil rainfall predominantly left the river basin by discharge, while evaporation accounted for the second most common destination of rainfall. Base flow also accounted for a destination of rainfall, though not as much as those previously mentioned.

  6. Rainfall characteristics and thresholds for periglacial debris flows in ...

    Indian Academy of Sciences (India)

    Mingfeng Deng

    2018-02-14

    Feb 14, 2018 ... Rainfall characteristics; runoff generated; threshold; debris flows; southeast Tibetan. Plateau. 1. ... glacier ablation water (Lu and Li 1989; Liu et al. 2013). ...... F J and Lund L J, US Department of Agriculture (River- side, CA ...

  7. Applications of multiscale change point detections to monthly stream flow and rainfall in Xijiang River in southern China, part I: correlation and variance

    Science.gov (United States)

    Zhu, Yuxiang; Jiang, Jianmin; Huang, Changxing; Chen, Yongqin David; Zhang, Qiang

    2018-04-01

    This article, as part I, introduces three algorithms and applies them to both series of the monthly stream flow and rainfall in Xijiang River, southern China. The three algorithms include (1) normalization of probability distribution, (2) scanning U test for change points in correlation between two time series, and (3) scanning F-test for change points in variances. The normalization algorithm adopts the quantile method to normalize data from a non-normal into the normal probability distribution. The scanning U test and F-test have three common features: grafting the classical statistics onto the wavelet algorithm, adding corrections for independence into each statistic criteria at given confidence respectively, and being almost objective and automatic detection on multiscale time scales. In addition, the coherency analyses between two series are also carried out for changes in variance. The application results show that the changes of the monthly discharge are still controlled by natural precipitation variations in Xijiang's fluvial system. Human activities disturbed the ecological balance perhaps in certain content and in shorter spells but did not violate the natural relationships of correlation and variance changes so far.

  8. Numerical representation of rainfall field in the Yarmouk River Basin

    Science.gov (United States)

    Shentsis, Isabella; Inbar, Nimrod; Magri, Fabien; Rosenthal, Eliyahu

    2017-04-01

    , geomorphologic and climatic division of the basin. Difference between regional curves is comparable with amplitude of rainfall variance within the regions. In general, rainfall increases with altitude and decreases from west to east (south-east). It should be emphasized that (i) Lake Kinneret Basin (2,490 sq. km) was earlier divided into seven "orographic regions" and (ii) the Lake Kinneret Basin and the Yarmouk River Basin are presented by the system of regional curves X = f (Z) as one whole rainfall field in the Upper Jordan River Basin, where the mean annual rain (X) increases with altitude (Z) and decreases from west to east and from north to south. In the Yarmouk Basin there is much less rainfall (344 mm) than in the Lake Kinneret Basin (749 mm), wherein mean annual rain (2,352 MCM versus 1,865 MCM) is shared between Syria, Jordan and Israel as 80%, 15% and 5%, respectively. The provided rainfall data allow more precise estimations of surface water balances and of recharge to the regional aquifers in the Upper Jordan River Basin. The derived rates serve as fundamental input data for numerical modeling of groundwater flow. This method can be applied to other areas at different temporal and spatial scales. The general applicability makes it a very useful tool in several hydrological problems connected with assessment, management and policy-making of water resources, as well as their changes due to climate and anthropogenic factors. Reference: I. Shentsis (1990). Mathematical models for long-term prediction of mountainous river runoff: methods, information and results, Hydrological Sciences Journal, 35:5, 487-500, DOI: 10.1080/02626669009492453

  9. ANALYSIS OF EFFECTIVE RAINFALL INTENSITY AND WORKING RAINFALL FOR BASIC WARNING CRITERIA DEVELOPMENT ON LAHAR FLOW EVENT

    Directory of Open Access Journals (Sweden)

    Fitriyadi Fitriyadi

    2015-05-01

    The research results showed that the number of reviewed serial rain with total value ≥ 80 mm is 9.28% of the whole serial rain, and 12.5% of them caused lahar flow in Gendol River. Debris flow occurrence probability on total rainfall amount of ≥ 80 mm that may occur on Gendol River amounted to 1.89%. This value represents less possibility of debris flow in Gendol River, this is due to the rain conditions in the Gendol Watershed different from the situation in Japan as well as the limitations of the available data. It is recommended for further research on the limitation of total rainfall in accordance with the conditions in Gendol Watershed by considering other parameters becoming the lahar flow controller factor. Further, it is necessary to perform the analysis using rain catchment method by averaging rainfall values on each of serial rain.

  10. The impact of Indian Ocean high pressure system on rainfall and stream flow

    International Nuclear Information System (INIS)

    Rehman, S.; Nasir, H.; Zia, S.S.; Ansari, W.A.; Salam, K.; Tayyab, N.

    2012-01-01

    Centre of Action approach is very useful in getting insight of rainfall and stream flow variability of specific region. Hameed et al. showed that Inter-annual variability of Gulf Stream north wall is influenced by low Icelandic pressure system and has more statistically significant correlation than North Atlantic Oscillation (NAO) with longitude of Icelandic low. This study also aims to explore possible relationships between rainfall and stream flow in Collie river catchment in Southwest Western Australia (SWWA) with Indian Ocean high pressure dynamics. The relationship between rainfall and stream flow with Indian Ocean high pressure system have been investigated using correlation analysis for early winter season (MJJA), lag correlation for MJJA versus SOND rainfall and stream flow are also calculated and found significant at 95% confidence level. By investigating the relationship between COA indices with rainfall and stream flow over the period 1976-2008, significant correlations suggests that rainfall and stream flow in Collie river basin is strongly influenced by COA indices. Multiple correlations between rainfall and stream flow with Indian Ocean high pressure (IOHPS and IOHLN) is 0.7 and 0.6 respectively. Centers of Action (COA) indices explain 51% and 36% of rainfall and stream flow respectively. The correlation between rainfall and stream flow with IOHPS is -0.4 and -0.3 whereas, with IOHLN is -0.47 and -0.52 respectively. (author)

  11. Rainfall and Detention Basin Flows

    Data.gov (United States)

    U.S. Environmental Protection Agency — Storm event data and flow rates in/out pre-post device installation. This dataset is associated with the following publication: Hawley, R., J. Goodrich, N. Korth, C....

  12. Analysis of rainfall distribution in Kelantan river basin, Malaysia

    Science.gov (United States)

    Che Ros, Faizah; Tosaka, Hiroyuki

    2018-03-01

    Using rainfall gauge on its own as input carries great uncertainties regarding runoff estimation, especially when the area is large and the rainfall is measured and recorded at irregular spaced gauging stations. Hence spatial interpolation is the key to obtain continuous and orderly rainfall distribution at unknown points to be the input to the rainfall runoff processes for distributed and semi-distributed numerical modelling. It is crucial to study and predict the behaviour of rainfall and river runoff to reduce flood damages of the affected area along the Kelantan river. Thus, a good knowledge on rainfall distribution is essential in early flood prediction studies. Forty six rainfall stations and their daily time-series were used to interpolate gridded rainfall surfaces using inverse-distance weighting (IDW), inverse-distance and elevation weighting (IDEW) methods and average rainfall distribution. Sensitivity analysis for distance and elevation parameters were conducted to see the variation produced. The accuracy of these interpolated datasets was examined using cross-validation assessment.

  13. Abrupt state change of river water quality (turbidity): Effect of extreme rainfalls and typhoons.

    Science.gov (United States)

    Lee, Chih-Sheng; Lee, Yi-Chao; Chiang, Hui-Min

    2016-07-01

    River turbidity is of dynamic nature, and its stable state is significantly changed during the period of heavy rainfall events. The frequent occurrence of typhoons in Taiwan has caused serious problems in drinking water treatment due to extremely high turbidity. The aim of the present study is to evaluate impact of typhoons on river turbidity. The statistical methods used included analyses of paired annual mean and standard deviation, frequency distribution, and moving standard deviation, skewness, and autocorrelation; all clearly indicating significant state changes of river turbidity. Typhoon Morakot of 2009 (recorded high rainfall over 2000mm in three days, responsible for significant disaster in southern Taiwan) is assumed as a major initiated event leading to critical state change. In addition, increasing rate of turbidity in rainfall events is highly and positively correlated with rainfall intensity both for pre- and post-Morakot periods. Daily turbidity is also well correlated with daily flow rate for all the eleven events evaluated. That implies potential prediction of river turbidity by river flow rate during rainfall and typhoon events. Based on analysis of stable state changes, more effective regulations for better basin management including soil-water conservation in watershed are necessary. Furthermore, municipal and industrial water treatment plants need to prepare and ensure the adequate operation of water treatment with high raw water turbidity (e.g., >2000NTU). Finally, methodology used in the present of this study can be applied to other environmental problems with abrupt state changes. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Radar rainfall estimation for the identification of debris-flow precipitation thresholds

    Science.gov (United States)

    Marra, Francesco; Nikolopoulos, Efthymios I.; Creutin, Jean-Dominique; Borga, Marco

    2014-05-01

    Identification of rainfall thresholds for the prediction of debris-flow occurrence is a common approach for warning procedures. Traditionally the debris-flow triggering rainfall is derived from the closest available raingauge. However, the spatial and temporal variability of intense rainfall on mountainous areas, where debris flows take place, may lead to large uncertainty in point-based estimates. Nikolopoulos et al. (2014) have shown that this uncertainty translates into a systematic underestimation of the rainfall thresholds, leading to a step degradation of the performances of the rainfall threshold for identification of debris flows occurrence under operational conditions. A potential solution to this limitation lies on use of rainfall estimates from weather radar. Thanks to their high spatial and temporal resolutions, these estimates offer the advantage of providing rainfall information over the actual debris flow location. The aim of this study is to analyze the value of radar precipitation estimations for the identification of debris flow precipitation thresholds. Seven rainfall events that triggered debris flows in the Adige river basin (Eastern Italian Alps) are analyzed using data from a dense raingauge network and a C-Band weather radar. Radar data are elaborated by using a set of correction algorithms specifically developed for weather radar rainfall application in mountainous areas. Rainfall thresholds for the triggering of debris flows are identified in the form of average intensity-duration power law curves using a frequentist approach by using both radar rainfall estimates and raingauge data. Sampling uncertainty associated to the derivation of the thresholds is assessed by using a bootstrap technique (Peruccacci et al. 2012). Results show that radar-based rainfall thresholds are largely exceeding those obtained by using raingauge data. Moreover, the differences between the two thresholds may be related to the spatial characteristics (i.e., spatial

  15. Spatio-temporal trends of rainfall across Indian river basins

    Science.gov (United States)

    Bisht, Deepak Singh; Chatterjee, Chandranath; Raghuwanshi, Narendra Singh; Sridhar, Venkataramana

    2018-04-01

    Daily gridded high-resolution rainfall data of India Meteorological Department at 0.25° spatial resolution (1901-2015) was analyzed to detect the trend in seasonal, annual, and maximum cumulative rainfall for 1, 2, 3, and 5 days. The present study was carried out for 85 river basins of India during 1901-2015 and pre- and post-urbanization era, i.e., 1901-1970 and 1971-2015, respectively. Mann-Kendall ( α = 0.05) and Theil-Sen's tests were employed for detecting the trend and percentage of change over the period of time, respectively. Daily extreme rainfall events, above 95 and 99 percentile threshold, were also analyzed to detect any trend in their magnitude and number of occurrences. The upward trend was found for the majority of the sub-basins for 1-, 2-, 3-, and 5-day maximum cumulative rainfall during the post-urbanization era. The magnitude of extreme threshold events is also found to be increasing in the majority of the river basins during the post-urbanization era. A 30-year moving window analysis further revealed a widespread upward trend in a number of extreme threshold rainfall events possibly due to urbanization and climatic factors. Overall trends studied against intra-basin trend across Ganga basin reveal the mixed pattern of trends due to inherent spatial heterogeneity of rainfall, therefore, highlighting the importance of scale for such studies.

  16. Simulation of a rainfall - runoff process for the evaluation of variability in the river flow regime in small basins with vegetation changes

    Czech Academy of Sciences Publication Activity Database

    Buchtele, Josef; Tesař, Miroslav

    2010-01-01

    Roč. 41, - (2010), s. 103-110 ISSN 0071-6715 R&D Projects: GA MŽP(CZ) SP/1A6/151/07 EU Projects: European Commission(XE) 511179 - NEWATER Institutional research plan: CEZ:AV0Z20600510 Keywords : vegetation change * land use * rainfall - runoff simulation * evapotranspiration demand Subject RIV: DA - Hydrology ; Limnology

  17. Rainfall-runoff and hydraulic modelling integration in the Blatina River

    International Nuclear Information System (INIS)

    Timko, J.

    2017-01-01

    This paper investigates the use and integration of rainfall-runoff modelling and hydrologic modelling of Blatina river catchment. Characteristics of physical-geographical sphere and its components were created within the model, enhancing the robustness of input data for the mathematical modelling of landscape runoff. Rainfall-runoff model HEC-HMS utilised in this research allows using a wide range of methodologies to determine the movement of water in the riverbed, water losses in the basin, hydraulic and hydrological methods of transformation and base-flow. Loss and transformation of water in the basin were modeled with curve numbers method SCS-CN. The simulated hydrograph was calibrated using rainfall-runoff event from June 2009. The same event was also modelled after the deforestation of the focus area. Using hydraulic model MIKE 21, a flood of focus rainfall-runoff area was simulated under both current real and changed land cover scenarios. (authors)

  18. RAINFALL ANALYSIS IN KLANG RIVER BASIN USING CONTINUOUS WAVELET TRANSFORM

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    Celso A. G. Santos

    2016-01-01

    Full Text Available The rainfall characteristics within Klang River basin is analyzed by the continuous wavelet transform using monthly rainfall data (1997–2009 from a raingauge and also using daily rainfall data (1998–2013 from the Tropical Rainfall Measuring Mission (TRMM. The wavelet power spectrum showed that some frequency components were presented within the rainfall time series, but the observed time series is short to provide accurate information, thus the daily TRMM rainfall data were used. In such analysis, two main frequency components, i.e., 6 and 12 months, showed to be present during the entire period of 16 years. Such semiannual and annual frequencies were confirmed by the global wavelet power spectra. Finally, the modulation in the 8–16-month and 256– 512-day bands were examined by an average of all scales between 8 and 16 months, and 256 and 512 days, respectively, giving a measure of the average monthly/daily variance versus time, where the periods with low or high variance could be identified.

  19. Rainfall and runoff water quality of the Pang and Lambourn, tributaries of the River Thames, south-eastern England

    Directory of Open Access Journals (Sweden)

    C. Neal

    2004-01-01

    Full Text Available The water quality of rainfall and runoff is described for two catchments of two tributaries of the River Thames, the Pang and Lambourn. Rainfall chemistry is variable and concentrations of most determinands decrease with increasing volume of catch probably due to 'wash out' processes. Two rainfall sites have been monitored, one for each catchment. The rainfall site on the Lambourn shows higher chemical concentrations than the one for the Pang which probably reflects higher amounts of local inputs from agricultural activity. Rainfall quality data at a long-term rainfall site on the Pang (UK National Air Quality Archive shows chemistries similar to that for the Lambourn site, but with some clear differences. Rainfall chemistries show considerable variation on an event-to-event basis. Average water quality concentrations and flow-weighted concentrations as well as fluxes vary across the sites, typically by about 30%. Stream chemistry is much less variable due to the main source of water coming from aquifer sources of high storage. The relationship between rainfall and runoff chemistry at the catchment outlet is described in terms of the relative proportions of atmospheric and within-catchment sources. Remarkably, in view of the quantity of agricultural and sewage inputs to the streams, the catchments appear to be retaining both P and N. Keywords: water quality, nitrate, ammonium, phosphorus, ammonia, nitrogen dioxide, pH, alkalinity, nutrients, trace metals, rainfall, river, Pang, Lambourn, LOCAR

  20. Incorporating rainfall uncertainty in a SWAT model: the river Zenne basin (Belgium) case study

    Science.gov (United States)

    Tolessa Leta, Olkeba; Nossent, Jiri; van Griensven, Ann; Bauwens, Willy

    2013-04-01

    The European Union Water Framework Directive (EU-WFD) called its member countries to achieve a good ecological status for all inland and coastal water bodies by 2015. According to recent studies, the river Zenne (Belgium) is far from this objective. Therefore, an interuniversity and multidisciplinary project "Towards a Good Ecological Status in the river Zenne (GESZ)" was launched to evaluate the effects of wastewater management plans on the river. In this project, different models have been developed and integrated using the Open Modelling Interface (OpenMI). The hydrologic, semi-distributed Soil and Water Assessment Tool (SWAT) is hereby used as one of the model components in the integrated modelling chain in order to model the upland catchment processes. The assessment of the uncertainty of SWAT is an essential aspect of the decision making process, in order to design robust management strategies that take the predicted uncertainties into account. Model uncertainty stems from the uncertainties on the model parameters, the input data (e.g, rainfall), the calibration data (e.g., stream flows) and on the model structure itself. The objective of this paper is to assess the first three sources of uncertainty in a SWAT model of the river Zenne basin. For the assessment of rainfall measurement uncertainty, first, we identified independent rainfall periods, based on the daily precipitation and stream flow observations and using the Water Engineering Time Series PROcessing tool (WETSPRO). Secondly, we assigned a rainfall multiplier parameter for each of the independent rainfall periods, which serves as a multiplicative input error corruption. Finally, we treated these multipliers as latent parameters in the model optimization and uncertainty analysis (UA). For parameter uncertainty assessment, due to the high number of parameters of the SWAT model, first, we screened out its most sensitive parameters using the Latin Hypercube One-factor-At-a-Time (LH-OAT) technique

  1. Changing trends of rainfall and sediment fluxes in the Kinta River catchment, Malaysia

    Directory of Open Access Journals (Sweden)

    W. R. Ismail

    2015-03-01

    Full Text Available The Kinta River, draining an area of 2566 km2, originates in the Korbu Mountain in Perak, Malaysia, and flows through heterogeneous, mixed land uses ranging from extensive forests to mining, rubber and oil palm plantations, and urban development. A land use change analysis of the Kinta River catchment was carried out together with assessment of the long-term trend in rainfall and sediment fluxes. The Mann-Kendall test was used to examine and assess the long-term trends in rainfall and its relationship with the sediment discharge trend. The land use analysis shows that forests, water bodies and mining land declined whilst built and agricultural land use increased significantly. This has influenced the sediment flux of the catchment. However, most of the rainfall stations and river gauging stations are experiencing an increasing trends, except at Kinta river at Tg. Rambutan. Sediment flux shows a net erosion for the period from 1961 to 1969. The total annual sediment discharge in the Kinta River catchment was low with an average rate of 1,757 t/km2/year. From 1970 to 1985, the annual sediment yield rose to an average rate of 4062 t/km2/year. Afterwards, from 1986 to 1993, the total annual sediment discharge decreased to an average rate of 1,306 t/km2/year and increased back during the period 1994 to 2000 to 2109 t/km2/year. From 2001 to 2006 the average sediment flux rate declined to 865 t/km2/year. The decline was almost 80% from the 1970s. High sediment flux in the early 1970s is partly associated with reduced tin mining activities in the area. This decreasing trend in sediment delivery leaving the Kinta River catchment is expected to continue dropping in the future.

  2. Changing trends of rainfall and sediment fluxes in the Kinta River catchment, Malaysia

    Science.gov (United States)

    Ismail, W. R.; Hashim, M.

    2015-03-01

    The Kinta River, draining an area of 2566 km2, originates in the Korbu Mountain in Perak, Malaysia, and flows through heterogeneous, mixed land uses ranging from extensive forests to mining, rubber and oil palm plantations, and urban development. A land use change analysis of the Kinta River catchment was carried out together with assessment of the long-term trend in rainfall and sediment fluxes. The Mann-Kendall test was used to examine and assess the long-term trends in rainfall and its relationship with the sediment discharge trend. The land use analysis shows that forests, water bodies and mining land declined whilst built and agricultural land use increased significantly. This has influenced the sediment flux of the catchment. However, most of the rainfall stations and river gauging stations are experiencing an increasing trends, except at Kinta river at Tg. Rambutan. Sediment flux shows a net erosion for the period from 1961 to 1969. The total annual sediment discharge in the Kinta River catchment was low with an average rate of 1,757 t/km2/year. From 1970 to 1985, the annual sediment yield rose to an average rate of 4062 t/km2/year. Afterwards, from 1986 to 1993, the total annual sediment discharge decreased to an average rate of 1,306 t/km2/year and increased back during the period 1994 to 2000 to 2109 t/km2/year. From 2001 to 2006 the average sediment flux rate declined to 865 t/km2/year. The decline was almost 80% from the 1970s. High sediment flux in the early 1970s is partly associated with reduced tin mining activities in the area. This decreasing trend in sediment delivery leaving the Kinta River catchment is expected to continue dropping in the future.

  3. Potential of commercial microwave link network derived rainfall for river runoff simulations

    Science.gov (United States)

    Smiatek, Gerhard; Keis, Felix; Chwala, Christian; Fersch, Benjamin; Kunstmann, Harald

    2017-03-01

    Commercial microwave link networks allow for the quantification of path integrated precipitation because the attenuation by hydrometeors correlates with rainfall between transmitter and receiver stations. The networks, operated and maintained by cellphone companies, thereby provide completely new and country wide precipitation measurements. As the density of traditional precipitation station networks worldwide is significantly decreasing, microwave link derived precipitation estimates receive increasing attention not only by hydrologists but also by meteorological and hydrological services. We investigate the potential of microwave derived precipitation estimates for streamflow prediction and water balance analyses, exemplarily shown for an orographically complex region in the German Alps (River Ammer). We investigate the additional value of link derived rainfall estimations combined with station observations compared to station and weather radar derived values. Our river runoff simulation system employs a distributed hydrological model at 100 × 100 m grid resolution. We analyze the potential of microwave link derived precipitation estimates for two episodes of 30 days with typically moderate river flow and an episode of extreme flooding. The simulation results indicate the potential of this novel precipitation monitoring method: a significant improvement in hydrograph reproduction has been achieved in the extreme flooding period that was characterized by a large number of local strong precipitation events. The present rainfall monitoring gauges alone were not able to correctly capture these events.

  4. Vallerani Micro-Catchment Infiltration Dynamics and Erosion from Simulated Rainfall and Concentrated Flow

    Science.gov (United States)

    Founds, M. J.; McGwire, K.; Weltz, M.

    2017-12-01

    Critical research gaps in rangeland hydrology still exist on the impact of conservation practices on erosion and subsequent mobilization of dissolved solids to streams. This study develops the scientific foundation necessary to better understand how a restoration strategy using a Vallerani Plow can be optimized to minimize erosion from rainfall impact and concentrated flow. Use of the Vallerani system has been proposed for use in the Upper Colorado River Basin (UCRB), where rapidly eroding rangelands contribute high salt loads to the Colorado River at a significant economic cost. The poster presentation will document the findings from a series of physical rainfall and concentrated flow simulations taking place at an experimental site northeast of Reno, NV in early August. A Walnut Gulch Rainfall simulator is used to apply variable intensity and duration rainfall events to micro-catchment structures created by the Vallerani Plow. The erosion and deposition caused by simulated rainfall will be captured from multi-angle photography using structure from motion (SFM) to create sub-centimeter 3-D models between each rainfall event. A rill-simulator also will be used to apply large volumes of concentrated flow to Vallerani micro-catchments, testing the point at which their infiltration capacity is exceeded and micro-catchments are overtopped. This information is important to adequately space structures on a given hillslope so that chances of failure are minimized. Measurements of saturated hydraulic conductivity and sorptivity from a Guelph Permeameter will be compared to the experimental results in order to develop an efficient method for surveying new terrain for treatment with the Vallerani plow. The effect of micro-catchments on surface flow and erosion will eventually be incorporated into the process-based Rangeland Hydrology and Erosion Model (RHEM) to create a tool that provides decision makers with quantitative estimates of potential reductions in erosion when

  5. Flowing with Rivers

    Science.gov (United States)

    Anderson, Heather

    2004-01-01

    This article describes a lesson in which students compare how artists have depicted rivers in paintings, using different styles, compositions, subject matter, colors, and techniques. They create a watercolor landscape that includes a river. Students can learn about rivers by studying them on site, through environmental study, and through works of…

  6. [Rainfall effects on the sap flow of Hedysarum scoparium.

    Science.gov (United States)

    Yang, Qiang; Zha, Than Shan; Jia, Xin; Qin, Shu Gao; Qian, Duo; Guo, Xiao Nan; Chen, Guo Peng

    2016-03-01

    In arid and semi-arid areas, plant physiological responses to water availability depend largely on the intensity and frequency of rain events. Knowledge on the responses of xerophytic plants to rain events is important for predicting the structure and functioning of dryland ecosystems under changing climate. The sap flow of Hedysarum scoparium in the Mu Us Sand Land was continuously measured during the growing season of 2012 and 2013. The objectives were to quantify the dynamics of sap flow under different weather conditions, and to examine the responses of sap flow to rain events of different sizes. The results showed that the daily sap flow rates of H. scoparium were lower on rainy days than on clear days. On clear days, the sap flow of H. scoparium showed a midday plateau, and was positively correlated with solar radiation and relative humidity. On rainy days, the sap flow fluctuated at low levels, and was positively correlated with solar radiation and air temperature. Rain events not only affected the sap flow on rainy days through variations in climatic factors (e.g., solar radiation and air temperature), but also affected post-rainfall sap flow velocities though changes in soil moisture. Small rain events (sap flow, whereas large rain events (>20 mm) significantly increased the sap flow on days following rainfall. Rain-wetted soil conditions not only resulted in higher sap flow velocities, but also enhanced the sensitivity of sap flow to solar radiation, vapor pressure deficit and air temperature.

  7. Climate downscaling over South America for 1971-2000: application in SMAP rainfall-runoff model for Grande River Basin

    Science.gov (United States)

    da Silva, Felipe das Neves Roque; Alves, José Luis Drummond; Cataldi, Marcio

    2018-03-01

    This paper aims to validate inflow simulations concerning the present-day climate at Água Vermelha Hydroelectric Plant (AVHP—located on the Grande River Basin) based on the Soil Moisture Accounting Procedure (SMAP) hydrological model. In order to provide rainfall data to the SMAP model, the RegCM regional climate model was also used working with boundary conditions from the MIROC model. Initially, present-day climate simulation performed by RegCM model was analyzed. It was found that, in terms of rainfall, the model was able to simulate the main patterns observed over South America. A bias correction technique was also used and it was essential to reduce mistakes related to rainfall simulation. Comparison between rainfall simulations from RegCM and MIROC showed improvements when the dynamical downscaling was performed. Then, SMAP, a rainfall-runoff hydrological model, was used to simulate inflows at Água Vermelha Hydroelectric Plant. After calibration with observed rainfall, SMAP simulations were evaluated in two different periods from the one used in calibration. During calibration, SMAP captures the inflow variability observed at AVHP. During validation periods, the hydrological model obtained better results and statistics with observed rainfall. However, in spite of some discrepancies, the use of simulated rainfall without bias correction captured the interannual flow variability. However, the use of bias removal in the simulated rainfall performed by RegCM brought significant improvements to the simulation of natural inflows performed by SMAP. Not only the curve of simulated inflow became more similar to the observed inflow, but also the statistics improved their values. Improvements were also noticed in the inflow simulation when the rainfall was provided by the regional climate model compared to the global model. In general, results obtained so far prove that there was an added value in rainfall when regional climate model was compared to global climate

  8. Implication of Negative Entropy Flow for Local Rainfall

    Directory of Open Access Journals (Sweden)

    Zhaohui Li

    2013-08-01

    Full Text Available The relation between the atmospheric entropy flow field and local rainfall is examined in terms of the theory of dissipative structures. In this paper, the entropy balance equation in a form suitable for describing the entropy budget of the Earth’s atmosphere is derived starting from the Gibbs relation, and, as examples, the entropy flows of the two severe weather events associated with the development of an extratropical cyclone and a tropical storm are calculated, respectively. The results show that negative entropy flow (NEF has a significant effect on the precipitation intensity and scope with an apparent matching of the NEF’s pattern with the rainfall distribution revealed and, that the diagnosis of NEF is able to provide a good indicator for precipitation forecasting.

  9. Estimation of Surface Runoff in the Jucar River Basin from Rainfall Data and SMOS Soil Moisture

    Science.gov (United States)

    Garcia Leal, Julio A.; Estrela, Teodoro; Fidalgo, Arancha; Gabaldo, Onofre; Gonzalez Robles, Maura; Herrera Daza, Eddy; Khodayar, Samiro; Lopez-Baeza, Ernesto

    2013-04-01

    Surface runoff is the water that flows after soil is infiltrated to full capacity and excess water from rain, meltwater, or other sources flows over the land. When the soil is saturated and the depression storage filled, and rain continues to fall, the rainfall will immediately produce surface runoff. The Soil Conservation Service Curve Number (SCS-CN) method is widely used for determining the approximate direct runoff volume for a given rainfall event in a particular area. The advantage of the method is its simplicity and widespread inclusion in existing computer models. It was originally developed by the US Department of Agriculture, Soil Conservation Service, and documented in detail in the National Engineering Handbook, Sect. 4: Hydrology (NEH-4) (USDA-SCS, 1985). Although the SCS-CN method was originally developed in the United States and mainly for the evaluation of storm runoff in small agricultural watersheds, it soon evolved well beyond its original objective and was adopted for various land uses and became an integral part of more complex, long-term, simulation models. The basic assumption of the SCS-CN method is that, for a single storm, the ratio of actual soil retention after runoff begins to potential maximum retention is equal to the ratio of direct runoff to available rainfall. This relationship, after algebraic manipulation and inclusion of simplifying assumptions, results in the following equation given in USDA-SCS (1985): (P--0,2S)2 Q = (P + 0,8S) where Q is the average runoff (mm), P the effective precipitation (mm) and S is potential maximum retention (mm) after the rainfall event. The study has been applied to the Jucar River Basin area, East of Spain. A selection of recent significant rainfall events has been made corresponding to the periods around 22nd November, 2011 and 28-29 September and 10 October, 2012, from Jucar River Basin Authority rain gauge data. Potential maximum retention values for each point have been assumed as the first

  10. Simulation of the catastrophic floods caused by extreme rainfall events - Uh River basin case study

    OpenAIRE

    Pekárová, Pavla; Halmová, Dana; Mitková, Veronika

    2005-01-01

    The extreme rainfall events in Central and East Europe on August 2002 rise the question, how other basins would respond on such rainfall situations. Such theorisation helps us to arrange in advance the necessary activity in the basin to reduce the consequence of the assumed disaster. The aim of the study is to recognise a reaction of the Uh River basin (Slovakia, Ukraine) to the simulated catastrophic rainfall events from August 2002. Two precipitation scenarios, sc1 and sc2, were created. Th...

  11. Rainfall-runoff model for prediction of waterborne viral contamination in a small river catchment

    Science.gov (United States)

    Gelati, E.; Dommar, C.; Lowe, R.; Polcher, J.; Rodó, X.

    2013-12-01

    We present a lumped rainfall-runoff model aimed at providing useful information for the prediction of waterborne viral contamination in small rivers. Viral contamination of water bodies may occur because of the discharge of sewage effluents and of surface runoff over areas affected by animal waste loads. Surface runoff is caused by precipitation that cannot infiltrate due to its intensity and to antecedent soil water content. It may transport animal feces to adjacent water bodies and cause viral contamination. We model streamflow by separating it into two components: subsurface flow, which is produced by infiltrated precipitation; and surface runoff. The model estimates infiltrated and non-infiltrated precipitation and uses impulse-response functions to compute the corresponding fractions of streamflow. The developed methodologies are applied to the Glafkos river, whose catchment extends for 102 km2 and includes the city of Patra. Streamflow and precipitation observations are available at a daily time resolution. Waterborne virus concentration measurements were performed approximately every second week from the beginning of 2011 to mid 2012. Samples were taken at several locations: in river water upstream of Patras and in the urban area; in sea water at the river outlet and approximately 2 km south-west of Patras; in sewage effluents before and after treatment. The rainfall-runoff model was calibrated and validated using observed streamflow and precipitation data. The model contribution to waterborne viral contamination prediction was benchmarked by analyzing the virus concentration measurements together with the estimated surface runoff values. The presented methodology may be a first step towards the development of waterborne viral contamination alert systems. Predicting viral contamination of water bodies would benefit sectors such as water supply and tourism.

  12. Rainfall characteristics and thresholds for periglacial debris flows in the Parlung Zangbo Basin, southeast Tibetan Plateau

    Science.gov (United States)

    Deng, Mingfeng; Chen, Ningsheng; Ding, Haitao

    2018-02-01

    The Parlung Zangbo Basin in the southeastern Tibet Plateau is affected by the summer monsoon from the Indian Ocean, which produces large rainfall gradients in the basin. Rainfall data during 2012-2015 from five new meteorological stations are used to analyse the rainfall characteristics. The daily rainfall, rainfall duration, mean rainfall intensity, and peak rainfall intensity are consistent, but sometimes contrasting. For example, these values decrease with increasing altitude, and the gradient is large downstream and small upstream, respectively. Moreover, the rainfall intensity peaks between 01:00 and 06:00 and increases during the afternoon. Based on the analysis of 14 debris flow cases in the basin, differences in the rainfall threshold differ depending on the location as sediment varieties. The sediment in the middle portions of the basin is wet and well structured; thus, long-duration, high-intensity rainfall is required to generate debris flows. Ravels in the upstream area are arid and not well structured, and short-duration rainfall is required to trigger debris flows. Between the above two locations, either long-duration, low-intensity rainfall or short-duration, high-intensity rainfall could provoke debris flows. Clearly, differences in rainfall characteristics and rainfall thresholds that are associated with the location must be considered in debris flow monitoring and warnings.

  13. Relationship of Rainfall Distribution and Water Level on Major Flood 2014 in Pahang River Basin, Malaysia

    Directory of Open Access Journals (Sweden)

    Nur Hishaam Sulaiman

    2017-01-01

    Full Text Available Climate change gives impact on extreme hydrological events especially in extreme rainfall. This article discusses about the relationship of rainfall distribution and water level on major flood 2014 in Pahang River Basin, Malaysia in helping decision makers to flood management system. Based on DID Malaysia rainfall station, 56 stations have being use as point in this research and it is including Pahang, Terengganu, Kelantan and Perak. Data set for this study were analysed with GIS analysis using interpolation method to develop Isohyet map and XLstat statistical software for PCA and SPC analyses. The results that were obtained from the Isohyet Map for three months was mid-November, rainfall started to increase about in range of 800mm-1200mm and the intensity keep increased to 2200mm at mid-December 2014. The high rainfall intensity sense at highland that is upstream of Pahang River. The PCA and SPC analysis also indicates the high relationship between rainfall and water level of few places at Pahang River. The Sg. Yap station and Kg. Serambi station obtained the high relationship of rainfall and water level with factor loading value at 0.9330 and 0.9051 for each station. Hydrological pattern and trend are extremely affected by climate such as north east monsoon season that occurred in South China Sea and affected Pahang during November to March. The findings of this study are important to local authorities by providing basic data as guidelines to the integrated river management at Pahang River Basin.

  14. Rainfall simulators - innovations seeking rainfall uniformity and automatic flow rate measurements

    Science.gov (United States)

    Bauer, Miroslav; Kavka, Petr; Strouhal, Luděk; Dostál, Tomáš; Krása, Josef

    2016-04-01

    single pressure operating mode, which is ensured by the pressure probe controlled electromagnetic valve. Previous experiments implied the need of automatic continuous measurements of selected variables. To this end the control unit was equipped with a datalogger. In a several seconds time step it collects the values of water pressure, nozzle-valves operation, control point rainfall intensity from a tipping bucket rain gauge, topsoil moisture from several Theta ML2x probes and most recently the plot outlet runoff rate. For a continuous runoff rate measurement a 0,4-foot HS-flume was constructed and equipped with S18U ultrasonic sensor. Assemble setting was optimised both in flow rate laboratory flume and in laboratory rainfall simulator. Namely the rating curves for particular flume bottom slopes were derived. Employment of the flume in the terrain is scheduled for the experimental season 2016, but laboratory results already show sufficient measurement accuracy and are promising in terms of experimental campaigns simplification. The abovementioned activities have been supported by the research grants SGS14/180/OHK1/3T/11, QJ1530181, QJ1520265 and QJ1330118.

  15. CORRELATION BETWEEN RAINFALL PATTERNS AND THE WATER TABLE IN THE GENERAL SEPARATIONS AREA OF THE SAVANNAH RIVER SITE

    International Nuclear Information System (INIS)

    Smith, C.

    2009-01-01

    The objective of the study was to evaluate rainfall and water table elevation data in search of a correlation that could be used to understand and predict water elevation changes. This information will be useful in placing screen zones for future monitoring wells and operations of groundwater treatment units. Fifteen wells in the General Separations Area (GSA) at Savannah River Site were evaluated from 1986 through 2001. The study revealed that the water table does respond to rainfall with minimal delay. (Water level information was available monthly, which restricted the ability to evaluate a shorter delay period.) Water elevations were found to be related to the cumulative sum (Q-Delta Sum) of the difference between the average rainfall for a specific month and the actual rainfall for that month, calculated from an arbitrary starting point. Water table elevations could also be correlated between wells, but using the right well for correlation was very important. The strongest correlation utilized a quadratic equation that takes into account the rainfall in a specific area and the rainfall from an adjacent area that contributes through a horizontal flow. Specific values vary from well to well as a result of geometry and underground variations. R2's for the best models ranged up to 0.96. The data in the report references only GSA wells but other wells (including confined water tables) on the site have been observed to return similar water level fluctuation patterns

  16. Runoff and leaching of metolachlor from Mississippi River alluvial soil during seasons of average and below-average rainfall.

    Science.gov (United States)

    Southwick, Lloyd M; Appelboom, Timothy W; Fouss, James L

    2009-02-25

    The movement of the herbicide metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide] via runoff and leaching from 0.21 ha plots planted to corn on Mississippi River alluvial soil (Commerce silt loam) was measured for a 6-year period, 1995-2000. The first three years received normal rainfall (30 year average); the second three years experienced reduced rainfall. The 4-month periods prior to application plus the following 4 months after application were characterized by 1039 +/- 148 mm of rainfall for 1995-1997 and by 674 +/- 108 mm for 1998-2000. During the normal rainfall years 216 +/- 150 mm of runoff occurred during the study seasons (4 months following herbicide application), accompanied by 76.9 +/- 38.9 mm of leachate. For the low-rainfall years these amounts were 16.2 +/- 18.2 mm of runoff (92% less than the normal years) and 45.1 +/- 25.5 mm of leachate (41% less than the normal seasons). Runoff of metolachlor during the normal-rainfall seasons was 4.5-6.1% of application, whereas leaching was 0.10-0.18%. For the below-normal periods, these losses were 0.07-0.37% of application in runoff and 0.22-0.27% in leachate. When averages over the three normal and the three less-than-normal seasons were taken, a 35% reduction in rainfall was characterized by a 97% reduction in runoff loss and a 71% increase in leachate loss of metolachlor on a percent of application basis. The data indicate an increase in preferential flow in the leaching movement of metolachlor from the surface soil layer during the reduced rainfall periods. Even with increased preferential flow through the soil during the below-average rainfall seasons, leachate loss (percent of application) of the herbicide remained below 0.3%. Compared to the average rainfall seasons of 1995-1997, the below-normal seasons of 1998-2000 were characterized by a 79% reduction in total runoff and leachate flow and by a 93% reduction in corresponding metolachlor movement via these routes

  17. Buck Creek River Flow Analysis

    Science.gov (United States)

    Dhanapala, Yasas; George, Elizabeth; Ritter, John

    2009-04-01

    Buck Creek flowing through Springfield Ohio has a number of low-head dams currently in place that cause safety issues and sometimes make it impossible for recreational boaters to pass through. The safety issues include the back eddies created by the dams that are known as drowning machines and the hydraulic jumps. In this study we are modeling the flow of Buck Creek using topographical and flow data provided by the Geology Department of Wittenberg University. The flow is analyzed using Hydraulic Engineering Center - River Analysis System software (HEC-RAS). As the first step a model of the river near Snyder Park has been created with the current structure in place for validation purposes. Afterwards the low-head dam is replaced with four drop structures with V-notch overflow gates. The river bed is altered to reflect plunge pools after each drop structure. This analysis will provide insight to how the flow is going to behave after the changes are made. In addition a sediment transport analysis is also being conducted to provide information about the stability of these structures.

  18. Numerical modelling of river processes: flow and river bed deformation

    NARCIS (Netherlands)

    Tassi, P.A.

    2007-01-01

    The morphology of alluvial river channels is a consequence of complex interaction among a number of constituent physical processes, such as flow, sediment transport and river bed deformation. This is, an alluvial river channel is formed from its own sediment. From time to time, alluvial river

  19. Flood risk reduction and flow buffering as ecosystem services - Part 2: Land use and rainfall intensity effects in Southeast Asia

    Science.gov (United States)

    van Noordwijk, Meine; Tanika, Lisa; Lusiana, Betha

    2017-05-01

    Watersheds buffer the temporal pattern of river flow relative to the temporal pattern of rainfall. This ecosystem service is inherent to geology and climate, but buffering also responds to human use and misuse of the landscape. Buffering can be part of management feedback loops if salient, credible and legitimate indicators are used. The flow persistence parameter Fp in a parsimonious recursive model of river flow (Part 1, van Noordwijk et al., 2017) couples the transmission of extreme rainfall events (1 - Fp), to the annual base-flow fraction of a watershed (Fp). Here we compare Fp estimates from four meso-scale watersheds in Indonesia (Cidanau, Way Besai and Bialo) and Thailand (Mae Chaem), with varying climate, geology and land cover history, at a decadal timescale. The likely response in each of these four to variation in rainfall properties (including the maximum hourly rainfall intensity) and land cover (comparing scenarios with either more or less forest and tree cover than the current situation) was explored through a basic daily water-balance model, GenRiver. This model was calibrated for each site on existing data, before being used for alternative land cover and rainfall parameter settings. In both data and model runs, the wet-season (3-monthly) Fp values were consistently lower than dry-season values for all four sites. Across the four catchments Fp values decreased with increasing annual rainfall, but specific aspects of watersheds, such as the riparian swamp (peat soils) in Cidanau reduced effects of land use change in the upper watershed. Increasing the mean rainfall intensity (at constant monthly totals for rainfall) around the values considered typical for each landscape was predicted to cause a decrease in Fp values by between 0.047 (Bialo) and 0.261 (Mae Chaem). Sensitivity of Fp to changes in land use change plus changes in rainfall intensity depends on other characteristics of the watersheds, and generalisations made on the basis of one or two

  20. Spatial and Temporal Variability of Rainfall in the Gandaki River Basin of Nepal Himalaya

    Directory of Open Access Journals (Sweden)

    Jeeban Panthi

    2015-03-01

    Full Text Available Landslides, floods, and droughts are recurring natural disasters in Nepal related to too much or too little water. The summer monsoon contributes more than 80% of annual rainfall, and rainfall spatial and inter-annual variation is very high. The Gandaki River, one of the three major rivers of Nepal and one of the major tributaries of the Ganges River, covers all agro-ecological zones in the central part of Nepal. Time series tests were applied for different agro-ecological zones of the Gandaki River Basin (GRB for rainfall trends of four seasons (pre-monsoon, monsoon, post-monsoon and winter from 1981 to 2012. The non-parametric Mann-Kendall and Sen’s methods were used to determine the trends. Decadal anomalies relative to the long-term average were analyzed using the APHRODITE precipitation product. Trends in number of rainy days and timing of the monsoon were also analyzed. We found that the post-monsoon, pre-monsoon and winter rainfalls are decreasing significantly in most of the zones but monsoon rainfall is increasing throughout the basin. In the hill region, the annual rainfall is increasing but the rainy days do not show any trend. There is a tendency toward later departure of monsoon from Nepal, indicating an increase in its duration. These seasonally and topographically variable trends may have significant impacts for the agriculture and livestock smallholders that form the majority of the population in the GRB.

  1. River flow response to changes in vegetation cover in a South ...

    African Journals Online (AJOL)

    It was hypothesised in this study that annual river yield (river flow as a fraction of rainfall) in the Molenaars catchment near Paarl, South Africa co-varies with an index of green vegetation cover derived from satellite data (the normalised difference vegetation index, NDVI). The catchment was partitioned into 'upland' and ...

  2. Real-Time Analysis and Forecasting of Multisite River Flow Using a Distributed Hydrological Model

    Directory of Open Access Journals (Sweden)

    Mingdong Sun

    2014-01-01

    Full Text Available A spatial distributed hydrological forecasting system was developed to promote the analysis of river flow dynamic state in a large basin. The research presented the real-time analysis and forecasting of multisite river flow in the Nakdong River Basin using a distributed hydrological model with radar rainfall forecast data. A real-time calibration algorithm of hydrological distributed model was proposed to investigate the particular relationship between the water storage and basin discharge. Demonstrate the approach of simulating multisite river flow using a distributed hydrological model couple with real-time calibration and forecasting of multisite river flow with radar rainfall forecasts data. The hydrographs and results exhibit that calibrated flow simulations are very approximate to the flow observation at all sites and the accuracy of forecasting flow is gradually decreased with lead times extending from 1 hr to 3 hrs. The flow forecasts are lower than the flow observation which is likely caused by the low estimation of radar rainfall forecasts. The research has well demonstrated that the distributed hydrological model is readily applicable for multisite real-time river flow analysis and forecasting in a large basin.

  3. Affecting factors of preferential flow in the forest of the Three Gorges area, Yangtze River

    Institute of Scientific and Technical Information of China (English)

    CHENG Jinhua; ZHANG Hongjiang; HE Fan; QI Shenglin; SUN Yanhong; ZHANG Youyan; SHI Yuhu

    2007-01-01

    In order to study the factors affecting preferential flow,a 2.9 m-long,2.6 m-deep soil profile was dug in the Quxi watershed,Yangtze River.To analyze the influence of rainfall on preferential flow,the preferential flow process was observed when the rainfalls were recorded.Soil physical and infiltration characteristics were also measured to study their effect on preferential flow.The results showed that the rainfall amount that could cause preferential flow was over 26 mm.There are four types of rainfall in the Three Gorges area,namely gradually dropping rain,even rain,sudden rain and peak rain.Preferential flow process was found to be relevant to the rainfall process.It was determined that with different rainfall types,preferential flow appeared at different times,occurring first in peak rain,followed by sudden rain,gradually dropping rain,and then even rain.Preferential flow would appear when the rainfall intensity was over 0.075 mm/min.In the studied area,the coarse soil particles increased with the soil depth,and for the deeper soil layer,the coarse particles promote the formation of preferential flow.Preferential flow accelerates the steady infiltration rate in the 83-110 cm soil horizon,and the quickly moving water in this horizon also enhanced the further formation and development of preferential flow.

  4. Numerical simulation of scouring-deposition variations caused by rainfall-induced landslides in the upstream of Zengwun River, Taiwan

    Science.gov (United States)

    Lee, Ming-Hsi; Liao, Yi-Wen; Tsai, Kuang-Jung

    2017-04-01

    In recent years, the increasing sediment disasters of severe rainfall-induced landslides on human lives and lifeline facilities worldwide have advanced the necessity to find out both economically acceptable and useful techniques to predict the occurrence and destructive power of the disasters. In August 2009, Typhoon Morakot brought a large amount of rainfall with both high intensity and long duration to a vast area of Taiwan. Unfortunately, this resulted in a catastrophic landslide in watershed of Zengwun-River reservoir, southern Taiwan. Meanwhile, large amounts of landslides were formed in the upstream of Zengwun River. The major scope of this study is to apply numerical model to simulate the scouring-deposition variations caused by rainfall-induced landslides that occurred in the upstream of Zengwun River during Typhoon Morakot. This study proposed the relation diagrams of the intermediate diameter (d50), recurrence interval (T) and scouring-deposition depth (D), and applied the diagrams to understand the impacts of the scouring-deposition variations on the structures for water and soil conservation and their measurements. Based on the simulation of scouring-deposition variation at the Da-Bu dam and Da-Bang dam, this study also discussed the scouring-deposition variations of different sections under different scenarios (including flow rate, intermediate diameters and structures). In summary, the result suggested that the diagrams of the intermediate diameter, recurrence interval and scouring-deposition depth could be used as the reference for designing the check dams, ground sills and lateral constructions.

  5. Dealing with rainfall forecast uncertainties in real-time flood control along the Demer river

    Directory of Open Access Journals (Sweden)

    Vermuyten Evert

    2016-01-01

    Full Text Available Real-time Model Predictive Control (MPC of hydraulic structures strongly reduces flood consequences under ideal circumstances. The performance of such flood control may, however, be significantly affected by uncertainties. This research quantifies the influence of rainfall forecast uncertainties and related uncertainties in the catchment rainfall-runoff discharges on the control performance for the Herk river case study in Belgium. To limit the model computational times, a fast conceptual model is applied. It is calibrated to a full hydrodynamic river model. A Reduced Genetic Algorithm is used as optimization method. Next to the analysis of the impact of the rainfall forecast uncertainties on the control performance, a Multiple Model Predictive Control (MMPC approach is tested to reduce this impact. Results show that the deterministic MPC-RGA outperforms the MMPC and that it is inherently robust against rainfall forecast uncertainties due to its receding horizon strategy.

  6. Evaluation of TRMM rainfall estimates over a large Indian river basin (Mahanadi

    Directory of Open Access Journals (Sweden)

    D. Kneis

    2014-07-01

    Full Text Available The paper examines the quality of satellite-based precipitation estimates for the lower Mahanadi River basin (eastern India. The considered data sets known as 3B42 and 3B42-RT (version 7/7A are routinely produced by the tropical rainfall measuring mission (TRMM from passive microwave and infrared recordings. While the 3B42-RT data are disseminated in real time, the gauge-adjusted 3B42 data set is published with a delay of some months. The quality of the two products was assessed in a two-step procedure. First, the correspondence between the remotely sensed precipitation rates and rain gauge data was evaluated at the sub-basin scale. Second, the quality of the rainfall estimates was assessed by analysing their performance in the context of rainfall–runoff simulation. At sub-basin level (4000 to 16 000 km2 the satellite-based areal precipitation estimates were found to be moderately correlated with the gauge-based counterparts (R2 of 0.64–0.74 for 3B42 and 0.59–0.72 for 3B42-RT. Significant discrepancies between TRMM data and ground observations were identified at high-intensity levels. The rainfall depth derived from rain gauge data is often not reflected by the TRMM estimates (hit rate 80 mm day-1. At the same time, the remotely sensed rainfall rates frequently exceed the gauge-based equivalents (false alarm ratios of 0.2–0.6. In addition, the real-time product 3B42-RT was found to suffer from a spatially consistent negative bias. Since the regionalisation of rain gauge data is potentially associated with a number of errors, the above results are subject to uncertainty. Hence, a validation against independent information, such as stream flow, was essential. In this case study, the outcome of rainfall–runoff simulation experiments was consistent with the above-mentioned findings. The best fit between observed and simulated stream flow was obtained if rain gauge data were used as model input (Nash–Sutcliffe index of 0.76–0.88 at

  7. Estimation of typhoon rainfall in GaoPing River: A Multivariate Maximum Entropy Method

    Science.gov (United States)

    Pei-Jui, Wu; Hwa-Lung, Yu

    2016-04-01

    The heavy rainfall from typhoons is the main factor of the natural disaster in Taiwan, which causes the significant loss of human lives and properties. Statistically average 3.5 typhoons invade Taiwan every year, and the serious typhoon, Morakot in 2009, impacted Taiwan in recorded history. Because the duration, path and intensity of typhoon, also affect the temporal and spatial rainfall type in specific region , finding the characteristics of the typhoon rainfall type is advantageous when we try to estimate the quantity of rainfall. This study developed a rainfall prediction model and can be divided three parts. First, using the EEOF(extended empirical orthogonal function) to classify the typhoon events, and decompose the standard rainfall type of all stations of each typhoon event into the EOF and PC(principal component). So we can classify the typhoon events which vary similarly in temporally and spatially as the similar typhoon types. Next, according to the classification above, we construct the PDF(probability density function) in different space and time by means of using the multivariate maximum entropy from the first to forth moment statistically. Therefore, we can get the probability of each stations of each time. Final we use the BME(Bayesian Maximum Entropy method) to construct the typhoon rainfall prediction model , and to estimate the rainfall for the case of GaoPing river which located in south of Taiwan.This study could be useful for typhoon rainfall predictions in future and suitable to government for the typhoon disaster prevention .

  8. Daily River Flow Forecasting with Hybrid Support Vector Machine – Particle Swarm Optimization

    Science.gov (United States)

    Zaini, N.; Malek, M. A.; Yusoff, M.; Mardi, N. H.; Norhisham, S.

    2018-04-01

    The application of artificial intelligence techniques for river flow forecasting can further improve the management of water resources and flood prevention. This study concerns the development of support vector machine (SVM) based model and its hybridization with particle swarm optimization (PSO) to forecast short term daily river flow at Upper Bertam Catchment located in Cameron Highland, Malaysia. Ten years duration of historical rainfall, antecedent river flow data and various meteorology parameters data from 2003 to 2012 are used in this study. Four SVM based models are proposed which are SVM1, SVM2, SVM-PSO1 and SVM-PSO2 to forecast 1 to 7 day ahead of river flow. SVM1 and SVM-PSO1 are the models with historical rainfall and antecedent river flow as its input, while SVM2 and SVM-PSO2 are the models with historical rainfall, antecedent river flow data and additional meteorological parameters as input. The performances of the proposed model are measured in term of RMSE and R2 . It is found that, SVM2 outperformed SVM1 and SVM-PSO2 outperformed SVM-PSO1 which meant the additional meteorology parameters used as input to the proposed models significantly affect the model performances. Hybrid models SVM-PSO1 and SVM-PSO2 yield higher performances as compared to SVM1 and SVM2. It is found that hybrid models are more effective in forecasting river flow at 1 to 7 day ahead at the study area.

  9. Hydrological classification of natural flow regimes to support environmental flow assessments in intensively regulated Mediterranean rivers, Segura River Basin (Spain).

    Science.gov (United States)

    Belmar, Oscar; Velasco, Josefa; Martinez-Capel, Francisco

    2011-05-01

    Hydrological classification constitutes the first step of a new holistic framework for developing regional environmental flow criteria: the "Ecological Limits of Hydrologic Alteration (ELOHA)". The aim of this study was to develop a classification for 390 stream sections of the Segura River Basin based on 73 hydrological indices that characterize their natural flow regimes. The hydrological indices were calculated with 25 years of natural monthly flows (1980/81-2005/06) derived from a rainfall-runoff model developed by the Spanish Ministry of Environment and Public Works. These indices included, at a monthly or annual basis, measures of duration of droughts and central tendency and dispersion of flow magnitude (average, low and high flow conditions). Principal Component Analysis (PCA) indicated high redundancy among most hydrological indices, as well as two gradients: flow magnitude for mainstream rivers and temporal variability for tributary streams. A classification with eight flow-regime classes was chosen as the most easily interpretable in the Segura River Basin, which was supported by ANOSIM analyses. These classes can be simplified in 4 broader groups, with different seasonal discharge pattern: large rivers, perennial stable streams, perennial seasonal streams and intermittent and ephemeral streams. They showed a high degree of spatial cohesion, following a gradient associated with climatic aridity from NW to SE, and were well defined in terms of the fundamental variables in Mediterranean streams: magnitude and temporal variability of flows. Therefore, this classification is a fundamental tool to support water management and planning in the Segura River Basin. Future research will allow us to study the flow alteration-ecological response relationship for each river type, and set the basis to design scientifically credible environmental flows following the ELOHA framework.

  10. River catchment rainfall series analysis using additive Holt-Winters method

    Science.gov (United States)

    Puah, Yan Jun; Huang, Yuk Feng; Chua, Kuan Chin; Lee, Teang Shui

    2016-03-01

    Climate change is receiving more attention from researchers as the frequency of occurrence of severe natural disasters is getting higher. Tropical countries like Malaysia have no distinct four seasons; rainfall has become the popular parameter to assess climate change. Conventional ways that determine rainfall trends can only provide a general result in single direction for the whole study period. In this study, rainfall series were modelled using additive Holt-Winters method to examine the rainfall pattern in Langat River Basin, Malaysia. Nine homogeneous series of more than 25 years data and less than 10% missing data were selected. Goodness of fit of the forecasted models was measured. It was found that seasonal rainfall model forecasts are generally better than the monthly rainfall model forecasts. Three stations in the western region exhibited increasing trend. Rainfall in southern region showed fluctuation. Increasing trends were discovered at stations in the south-eastern region except the seasonal analysis at station 45253. Decreasing trend was found at station 2818110 in the east, while increasing trend was shown at station 44320 that represents the north-eastern region. The accuracies of both rainfall model forecasts were tested using the recorded data of years 2010-2012. Most of the forecasts are acceptable.

  11. Rainfall control of debris-flow triggering in the Réal Torrent, Southern French Prealps

    Science.gov (United States)

    Bel, Coraline; Liébault, Frédéric; Navratil, Oldrich; Eckert, Nicolas; Bellot, Hervé; Fontaine, Firmin; Laigle, Dominique

    2017-08-01

    This paper investigates the occurrence of debris flow due to rainfall forcing in the Réal Torrent, a very active debris flow-prone catchment in the Southern French Prealps. The study is supported by a 4-year record of flow responses and rainfall events, from three high-frequency monitoring stations equipped with geophones, flow stage sensors, digital cameras, and rain gauges measuring rainfall at 5-min intervals. The classic method of rainfall intensity-duration (ID) threshold was used, and a specific emphasis was placed on the objective identification of rainfall events, as well as on the discrimination of flow responses observed above the ID threshold. The results show that parameters used to identify rainfall events significantly affect the ID threshold and are likely to explain part of the threshold variability reported in the literature. This is especially the case regarding the minimum duration of rain interruption (MDRI) between two distinct rainfall events. In the Réal Torrent, a 3-h MDRI appears to be representative of the local rainfall regime. A systematic increase in the ID threshold with drainage area was also observed from the comparison of the three stations, as well as from the compilation of data from experimental debris-flow catchments. A logistic regression used to separate flow responses above the ID threshold, revealed that the best predictors are the 5-min maximum rainfall intensity, the 48-h antecedent rainfall, the rainfall amount and the number of days elapsed since the end of winter (used as a proxy of sediment supply). This emphasizes the critical role played by short intense rainfall sequences that are only detectable using high time-resolution rainfall records. It also highlights the significant influence of antecedent conditions and the seasonal fluctuations of sediment supply.

  12. Seasonal forecasts of the summer 2016 Yangtze River basin rainfall

    OpenAIRE

    Bett, Philip E.; Scaife, Adam A.; Li, Chaofan; Hewitt, Chris; Golding, Nicola; Zhang, Peiqun; Dunstone, Nick; Smith, Doug M.; Thornton, Hazel E.; Lu, Riyu; Ren, Hong-Li

    2017-01-01

    The Yangtze River has been subject to heavy flooding throughout history, and in recent times severe floods such as those in 1998 have resulted in heavy loss of life and livelihoods. Dams along the river help to manage flood waters, and are important sources of electricity for the region. Being able to forecast high-impact events at long lead times therefore has enormous potential benefit. Recent improvements in seasonal forecasting mean that dynamical climate models can start to be used direc...

  13. Event-based rainfall-runoff modelling of the Kelantan River Basin

    Science.gov (United States)

    Basarudin, Z.; Adnan, N. A.; Latif, A. R. A.; Tahir, W.; Syafiqah, N.

    2014-02-01

    Flood is one of the most common natural disasters in Malaysia. According to hydrologists there are many causes that contribute to flood events. The two most dominant factors are the meteorology factor (i.e climate change) and change in land use. These two factors contributed to floods in recent decade especially in the monsoonal catchment such as Malaysia. This paper intends to quantify the influence of rainfall during extreme rainfall events on the hydrological model in the Kelantan River catchment. Therefore, two dynamic inputs were used in the study: rainfall and river discharge. The extreme flood events in 2008 and 2004 were compared based on rainfall data for both years. The events were modeled via a semi-distributed HEC-HMS hydrological model. Land use change was not incorporated in the study because the study only tries to quantify rainfall changes during these two events to simulate the discharge and runoff value. Therefore, the land use data representing the year 2004 were used as inputs in the 2008 runoff model. The study managed to demonstrate that rainfall change has a significant impact to determine the peak discharge and runoff depth for the study area.

  14. Event-based rainfall-runoff modelling of the Kelantan River Basin

    International Nuclear Information System (INIS)

    Basarudin, Z; Adnan, N A; Latif, A R A; Syafiqah, N; Tahir, W

    2014-01-01

    Flood is one of the most common natural disasters in Malaysia. According to hydrologists there are many causes that contribute to flood events. The two most dominant factors are the meteorology factor (i.e climate change) and change in land use. These two factors contributed to floods in recent decade especially in the monsoonal catchment such as Malaysia. This paper intends to quantify the influence of rainfall during extreme rainfall events on the hydrological model in the Kelantan River catchment. Therefore, two dynamic inputs were used in the study: rainfall and river discharge. The extreme flood events in 2008 and 2004 were compared based on rainfall data for both years. The events were modeled via a semi-distributed HEC-HMS hydrological model. Land use change was not incorporated in the study because the study only tries to quantify rainfall changes during these two events to simulate the discharge and runoff value. Therefore, the land use data representing the year 2004 were used as inputs in the 2008 runoff model. The study managed to demonstrate that rainfall change has a significant impact to determine the peak discharge and runoff depth for the study area

  15. Traffic Flow Prediction with Rainfall Impact Using a Deep Learning Method

    Directory of Open Access Journals (Sweden)

    Yuhan Jia

    2017-01-01

    Full Text Available Accurate traffic flow prediction is increasingly essential for successful traffic modeling, operation, and management. Traditional data driven traffic flow prediction approaches have largely assumed restrictive (shallow model architectures and do not leverage the large amount of environmental data available. Inspired by deep learning methods with more complex model architectures and effective data mining capabilities, this paper introduces the deep belief network (DBN and long short-term memory (LSTM to predict urban traffic flow considering the impact of rainfall. The rainfall-integrated DBN and LSTM can learn the features of traffic flow under various rainfall scenarios. Experimental results indicate that, with the consideration of additional rainfall factor, the deep learning predictors have better accuracy than existing predictors and also yield improvements over the original deep learning models without rainfall input. Furthermore, the LSTM can outperform the DBN to capture the time series characteristics of traffic flow data.

  16. Rainfall threshold calculation for debris flow early warning in areas with scarcity of data

    Science.gov (United States)

    Pan, Hua-Li; Jiang, Yuan-Jun; Wang, Jun; Ou, Guo-Qiang

    2018-05-01

    Debris flows are natural disasters that frequently occur in mountainous areas, usually accompanied by serious loss of lives and properties. One of the most commonly used approaches to mitigate the risk associated with debris flows is the implementation of early warning systems based on well-calibrated rainfall thresholds. However, many mountainous areas have little data regarding rainfall and hazards, especially in debris-flow-forming regions. Therefore, the traditional statistical analysis method that determines the empirical relationship between rainstorms and debris flow events cannot be effectively used to calculate reliable rainfall thresholds in these areas. After the severe Wenchuan earthquake, there were plenty of deposits deposited in the gullies, which resulted in several debris flow events. The triggering rainfall threshold has decreased obviously. To get a reliable and accurate rainfall threshold and improve the accuracy of debris flow early warning, this paper developed a quantitative method, which is suitable for debris flow triggering mechanisms in meizoseismal areas, to identify rainfall threshold for debris flow early warning in areas with a scarcity of data based on the initiation mechanism of hydraulic-driven debris flow. First, we studied the characteristics of the study area, including meteorology, hydrology, topography and physical characteristics of the loose solid materials. Then, the rainfall threshold was calculated by the initiation mechanism of the hydraulic debris flow. The comparison with other models and with alternate configurations demonstrates that the proposed rainfall threshold curve is a function of the antecedent precipitation index (API) and 1 h rainfall. To test the proposed method, we selected the Guojuanyan gully, a typical debris flow valley that during the 2008-2013 period experienced several debris flow events, located in the meizoseismal areas of the Wenchuan earthquake, as a case study. The comparison with other

  17. Experimental Investigation of Rainfall Impact on Overland Flow Driven Erosion Processes and Flow Hydrodynamics on a Steep Hillslope

    Science.gov (United States)

    Tian, P.; Xu, X.; Pan, C.; Hsu, K. L.; Yang, T.

    2016-12-01

    Few attempts have been made to investigate the quantitative effects of rainfall on overland flow driven erosion processes and flow hydrodynamics on steep hillslopes under field conditions. Field experiments were performed in flows for six inflow rates (q: 6-36 Lmin-1m-1) with and without rainfall (60 mm h-1) on a steep slope (26°) to investigate: (1) the quantitative effects of rainfall on runoff and sediment yield processes, and flow hydrodynamics; (2) the effect of interaction between rainfall and overland flow on soil loss. Results showed that the rainfall increased runoff coefficients and the fluctuation of temporal variations in runoff. The rainfall significantly increased soil loss (10.6-68.0%), but this increment declined as q increased. When the interrill erosion dominated (q=6 Lmin-1m-1), the increment in the rill erosion was 1.5 times that in the interrill erosion, and the effect of the interaction on soil loss was negative. When the rill erosion dominated (q=6-36 Lmin-1m-1), the increment in the interrill erosion was 1.7-8.8 times that in the rill erosion, and the effect of the interaction on soil loss became positive. The rainfall was conducive to the development of rills especially for low inflow rates. The rainfall always decreased interrill flow velocity, decreased rill flow velocity (q=6-24 Lmin-1m-1), and enhanced the spatial uniformity of the velocity distribution. Under rainfall disturbance, flow depth, Reynolds number (Re) and resistance were increased but Froude number was reduced, and lower Re was needed to transform a laminar flow to turbulent flow. The rainfall significantly increased flow shear stress (τ) and stream power (φ), with the most sensitive parameters to sediment yield being τ (R2=0.994) and φ (R2=0.993), respectively, for non-rainfall and rainfall conditions. Compared to non-rainfall conditions, there was a reduction in the critical hydrodynamic parameters of mean flow velocity, τ, and φ by the rainfall. These findings

  18. Characteristics of rainfall triggering of debris flows in the Chenyulan watershed, Taiwan

    Directory of Open Access Journals (Sweden)

    J. C. Chen

    2013-04-01

    Full Text Available This paper reports the variation in rainfall characteristics associated with debris flows in the Chenyulan watershed, central Taiwan, between 1963 and 2009. The maximum hourly rainfall Im, the maximum 24 h rainfall Rd, and the rainfall index RI (defined as the product RdIm were analysed for each rainfall event that triggered a debris flow within the watershed. The corresponding number of debris flows initiated by each rainfall event (N was also investigated via image analysis and/or field investigation. The relationship between N and RI was analysed. Higher RI of a rainfall event would trigger a larger number of debris flows. This paper also discusses the effects of the Chi-Chi earthquake (CCE on this relationship and on debris flow initiation. The results showed that the critical RI for debris flow initiation had significant variations and was significantly lower in the years immediately following the CCE of 1999, but appeared to revert to the pre-earthquake condition about five years later. Under the same extreme rainfall event of RI = 365 cm2 h−1, the value of N in the CCE-affected period could be six times larger than that in the non-CCE-affected periods.

  19. Remote sensing-based characterization of rainfall during atmospheric rivers over the central United States

    Science.gov (United States)

    Nayak, Munir A.; Villarini, Gabriele

    2018-01-01

    Atmospheric rivers (ARs) play a central role in the hydrology and hydroclimatology of the central United States. More than 25% of the annual rainfall is associated with ARs over much of this region, with many large flood events tied to their occurrence. Despite the relevance of these storms for flood hydrology and water budget, the characteristics of rainfall associated with ARs over the central United has not been investigated thus far. This study fills this major scientific gap by describing the rainfall during ARs over the central United States using five remote sensing-based precipitation products over a 12-year study period. The products we consider are: Stage IV, Tropical Rainfall Measuring Mission - Multi-satellite Precipitation Analysis (TMPA, both real-time and research version); Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks (PERSIANN); the CPC MORPHing Technique (CMORPH). As part of the study, we evaluate these products against a rain gauge-based dataset using both graphical- and metrics-based diagnostics. Based on our analyses, Stage IV is found to better reproduce the reference data. Hence, we use it for the characterization of rainfall in ARs. Most of the AR-rainfall is located in a narrow region within ∼150 km on both sides of the AR major axis. In this region, rainfall has a pronounced positive relationship with the magnitude of the water vapor transport. Moreover, we have also identified a consistent increase in rainfall intensity with duration (or persistence) of AR conditions. However, there is not a strong indication of diurnal variability in AR rainfall. These results can be directly used in developing flood protection strategies during ARs. Further, weather prediction agencies can benefit from the results of this study to achieve higher skill of resolving precipitation processes in their models.

  20. Hydrological Evaluation of TRMM Rainfall over the Upper Senegal River Basin

    Directory of Open Access Journals (Sweden)

    Ansoumana Bodian

    2016-04-01

    Full Text Available The availability of climatic data, especially on a daily time step, has become very rare in West Africa over the last few years due to the high costs of climate data monitoring. This scarcity of climatic data is a huge obstacle to conduct hydrological studies over some watersheds. In this context, our study aimed to evaluate the capacity of Tropical Rainfall Measuring Mission (TRMM satellite data to simulate the observed runoffs over the Bafing (the main important tributary of the Senegal River before their potential integration in hydrological studies. The conceptual hydrological model GR4J (modèle du Génie Rural (Agricultural Engineering Model à 4 paramètres Journalier (4 parameters Daily has been used, calibrated and validated over the 1961–1997 period with rainfall and Potential Evapotranspiration (PET as inputs. Then, the parameters that best reflect the rainfall-runoff relation, obtained during the cross-calibration-validation phase, were used to simulate runoff over the 1998–2004 period using observed and TRMM rainfalls. The findings of this study show that there is a high consistency between satellite-based estimates and ground-based observations of rainfall. Over the 1998–2004 simulation period, the two rainfall data series show quite satisfactorily results. The output hydrographs from satellite-based estimates and ground-based observations of rainfall coincide quite well with the shape of observed hydrographs with Nash-Sutcliffe Efficiency coefficient (NSE of 0.88 and 0.80 for observed rainfalls and TRMM rainfalls, respectively.

  1. Arima modelling of annual rainfalls in the Bregalnica River basin

    OpenAIRE

    Jovanovski, Vlatko; Delipetrov, Todor

    2007-01-01

    Changes in the hydrological characteristics have an impact on the environment. The reasons for the impact in the Bregalnica river basin are heavy rains and long droughts. Monitoring the undenstanding of hydrological impacts may provide useful assessment ingand forecast in several fields. This paper analysis hydrological processes, and offeres data processing of the monitor with ARIMA Modelling in STATISTICA packet like good techniques for estimation forecast of the hydrological caracterist...

  2. Estimation of reservoir inflow in data scarce region by using Sacramento rainfall runoff model - A case study for Sittaung River Basin, Myanmar

    Science.gov (United States)

    Myo Lin, Nay; Rutten, Martine

    2017-04-01

    The Sittaung River is one of four major rivers in Myanmar. This river basin is developing fast and facing problems with flood, sedimentation, river bank erosion and salt intrusion. At present, more than 20 numbers of reservoirs have already been constructed for multiple purposes such as irrigation, domestic water supply, hydro-power generation, and flood control. The rainfall runoff models are required for the operational management of this reservoir system. In this study, the river basin is divided into (64) sub-catchments and the Sacramento Soil Moisture Accounting (SAC-SMA) models are developed by using satellite rainfall and Geographic Information System (GIS) data. The SAC-SMA model has sixteen calibration parameters, and also uses a unit hydrograph for surface flow routing. The Sobek software package is used for SAC-SMA modelling and simulation of river system. The models are calibrated and tested by using observed discharge and water level data. The statistical results show that the model is applicable to use for data scarce region. Keywords: Sacramento, Sobek, rainfall runoff, reservoir

  3. Beryllium-7 in Rainfall, River Sediment and Sewage Sludge - Beryllium-7 in rainwater, river sediment and sewage sludge

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, Helmut W.; Igbinosa, Aimuamwosa; Souti, Maria Evangelia [University of Bremen, Institute of Environmental Physics, Otto-Hahn-Allee 1, D-28359 Bremen (Germany)

    2014-07-01

    Introduction: The cosmogenic radioisotope {sup 7}Be is one of the major contributors to natural airborne radioactivity, with fairly constant concentrations of some mBq/m{sup 3} near the Earth's surface. The isotope is assumed to be bound to aerosols. It is deposited onto the Earth's surface mainly by wet deposition. In environmental surveillance it is detected regularly in air by aerosol sampling, and in topsoil and on plant leaves after rainfall. In previous studies of this laboratory it had also been detected regularly in freshwater sediments and in wastewater treatment primary sludge. River sediment samples from an estuary showed concentrations influenced by dilution with sea water. Thus it appeared interesting to investigate the usefulness of {sup 7}Be as tracer for rainfall contribution in environmental samples. Experimental: In order to investigate possible correlations and interrelations between {sup 7}Be activity in rainfall, sediment and primary sludge, a measurement campaign was planned and conducted covering a time span of 6 months. {sup 7}Be concentrations were determined in weekly samples of rainwater and primary sludge and in monthly samples of river sediment by high resolution gamma spectroscopy. Besides, rainfall amount and intensity were recorded and weekly primary sludge production volume data were obtained from the treatment plant operators. From these numbers, total atmospheric deposition per surface area could be calculated. Results and discussion: The data show a clear correlation between weekly rainfall amount and {sup 7}Be surface deposition. This is more than plausible as wet deposition is known to be the most effective deposition process. Although washout effectivity is assumed to decrease with rainfall intensity, no correlation could be seen in the data, probably due to averaging within the weekly sampling intervals. The time series of {sup 7}Be deposition with rain and its concentration in primary sludge exhibit very similar

  4. Effects of rainfall patterns and land cover on the subsurface flow generation of sloping Ferralsols in southern China.

    Directory of Open Access Journals (Sweden)

    Jian Duan

    Full Text Available Rainfall patterns and land cover are two important factors that affect the runoff generation process. To determine the surface and subsurface flows associated with different rainfall patterns on sloping Ferralsols under different land cover types, observational data related to surface and subsurface flows from 5 m × 15 m plots were collected from 2010 to 2012. The experiment was conducted to assess three land cover types (grass, litter cover and bare land in the Jiangxi Provincial Soil and Water Conservation Ecological Park. During the study period, 114 natural rainfall events produced subsurface flow and were divided into four groups using k-means clustering according to rainfall duration, rainfall depth and maximum 30-min rainfall intensity. The results showed that the total runoff and surface flow values were highest for bare land under all four rainfall patterns and lowest for the covered plots. However, covered plots generated higher subsurface flow values than bare land. Moreover, the surface and subsurface flows associated with the three land cover types differed significantly under different rainfall patterns. Rainfall patterns with low intensities and long durations created more subsurface flow in the grass and litter cover types, whereas rainfall patterns with high intensities and short durations resulted in greater surface flow over bare land. Rainfall pattern I had the highest surface and subsurface flow values for the grass cover and litter cover types. The highest surface flow value and lowest subsurface flow value for bare land occurred under rainfall pattern IV. Rainfall pattern II generated the highest subsurface flow value for bare land. Therefore, grass or litter cover are able to convert more surface flow into subsurface flow under different rainfall patterns. The rainfall patterns studied had greater effects on subsurface flow than on total runoff and surface flow for covered surfaces, as well as a greater effect on surface

  5. Madagascar corals reveal a multidecadal signature of rainfall and river runoff since 1708

    Directory of Open Access Journals (Sweden)

    C. A. Grove

    2013-03-01

    Full Text Available Pacific Ocean sea surface temperatures (SST influence rainfall variability on multidecadal and interdecadal timescales in concert with the Pacific Decadal Oscillation (PDO and Interdecadal Pacific Oscillation (IPO. Rainfall variations in locations such as Australia and North America are therefore linked to phase changes in the PDO. Furthermore, studies have suggested teleconnections exist between the western Indian Ocean and Pacific Decadal Variability (PDV, similar to those observed on interannual timescales related to the El Niño Southern Oscillation (ENSO. However, as instrumental records of rainfall are too short and sparse to confidently assess multidecadal climatic teleconnections, here we present four coral climate archives from Madagascar spanning up to the past 300 yr (1708–2008 to assess such decadal variability. Using spectral luminescence scanning to reconstruct past changes in river runoff, we identify significant multidecadal and interdecadal frequencies in the coral records, which before 1900 are coherent with Asian-based PDO reconstructions. This multidecadal relationship with the Asian-based PDO reconstructions points to an unidentified teleconnection mechanism that affects Madagascar rainfall/runoff, most likely triggered by multidecadal changes in North Pacific SST, influencing the Asian Monsoon circulation. In the 20th century we decouple human deforestation effects from rainfall-induced soil erosion by pairing luminescence with coral geochemistry. Positive PDO phases are associated with increased Indian Ocean temperatures and runoff/rainfall in eastern Madagascar, while precipitation in southern Africa and eastern Australia declines. Consequently, the negative PDO phase that started in 1998 may contribute to reduced rainfall over eastern Madagascar and increased precipitation in southern Africa and eastern Australia. We conclude that multidecadal rainfall variability in Madagascar and the western Indian Ocean needs to be

  6. Rainfall Characteristic on the Slopes of Mount Merapi Region (Empirical Formula, Duration, Distribution, And Critical Line Woro River

    Directory of Open Access Journals (Sweden)

    Pudak Juni Laksana

    2015-05-01

    Full Text Available Debris flow on the slopes of Mount Merapi area became a serious natural disasters because it has great destructive force and velocity. Rainfall with a certain intensity and duration is one component triggering debris flow. Rainfall has variability of the temporal and spatial characteristics influenced by various factors, such as topography and climate. Dharma (2012 suggested to define the characteristics of the intensity of rainfall using rainfall data with a shorter duration with statistical tests to establish the best empirical IDF formula.  This research was using of 30 minutes rainfall data for short duration (<3 hours and a spreadsheet software representing duration and distribution of the rainfall. The most appropriate rainfall intensity formula was done by the empirical IDF formula, i.e. Sherman, Kimijima, Hasper and Mononobe. Rainfall intensity analysis applied Frequency Analysis Software (based on Microsoft Excel. Debris flow occurrence was analyzed using MLIT for method A to establish standard rainfall index.  Sherman formula performed the best fit to the IDF characteristics of rainfall in the region of the slopes of Mount Merapi. Rainfall distribution pattern showed high intensity rainfall in the first hour and then decreased in the next hour which means distribution for the duration of 3 hours, 12%, 28%, 25%, 16%, 12%, and 7%, respectively with an interval of 30 minutes. Based on critical line, 5 mm of standard rainfall index was gained in the case of warning (R1 and 28 mm in the case of evacuation (R2.

  7. Analysis and Modeling of Time-Correlated Characteristics of Rainfall-Runoff Similarity in the Upstream Red River Basin

    Directory of Open Access Journals (Sweden)

    Xiuli Sang

    2012-01-01

    Full Text Available We constructed a similarity model (based on Euclidean distance between rainfall and runoff to study time-correlated characteristics of rainfall-runoff similar patterns in the upstream Red River Basin and presented a detailed evaluation of the time correlation of rainfall-runoff similarity. The rainfall-runoff similarity was used to determine the optimum similarity. The results showed that a time-correlated model was found to be capable of predicting the rainfall-runoff similarity in the upstream Red River Basin in a satisfactory way. Both noised and denoised time series by thresholding the wavelet coefficients were applied to verify the accuracy of model. And the corresponding optimum similar sets obtained as the equation solution conditions showed an interesting and stable trend. On the whole, the annual mean similarity presented a gradually rising trend, for quantitatively estimating comprehensive influence of climate change and of human activities on rainfall-runoff similarity.

  8. Rainfall variability and its influence on surface flow regimes. Examples from the central highlands of Ethiopia

    Energy Technology Data Exchange (ETDEWEB)

    Osman, M. [Debre Zeit (Ethiopia); Sauerborn, P. [Seminar fuer Geographie und ihre Didaktik, Univ. zu Koeln, Koeln (Germany)

    2002-07-01

    The article shows results of an international and interdisciplinary project with the title 'Rainfall and its Erosivity in Ethiopia'. Rainfall variability affects the water resource management of Ethiopia. The influence of rainfall variability on flow regimes was investigated using five gauging stations with data availability from 1982-1997. It was confirmed that the variability in rainfall has a direct implication for surface runoff. Surface runoff declined at most of the gauging stations investigated. Therefore, effective water resource management is recommended for the study area. Future research should focus on watershed management which includes land-use and land cover. The question posed here is whether the variability in rainfall significantly affected surface flow in the study area. (orig.)

  9. Rainfall characteristics and their implications for rain-fed agriculture : a case study in the Upper Zambezi River Basin

    NARCIS (Netherlands)

    Beyer, M.; Wallner, M.; Bahlmann, L.; Thiemig, V.; Dietrich, J.; Billib, M.

    2016-01-01

    This study investigates rainfall characteristics in the Upper Zambezi River Basin and implications for rain-fed agriculture. Seventeen indices describing the character of each rainy season were calculated using a bias-corrected version of TRMM-B42 v6 rainfall estimate for 1998–2010. These were

  10. Statistical Seasonal Rainfall Forecast in the Neuquén River Basin (Comahue Region, Argentina

    Directory of Open Access Journals (Sweden)

    Marcela Hebe González

    2015-05-01

    Full Text Available A detailed statistical analysis was performed at the Neuquén river basin using precipitation data for 1980–2007. The hydrological year begins in March with a maximum in June associated with rainfall and another relative maximum in October derived from snow-break. General features of the rainy season and the excess or deficits thereof are analyzed using standardized precipitation index (SPI for a six-month period in the basin. The SPI has a significant cycle of 14.3 years; the most severe excess (SPI greater than 2 has a return period of 25 years, while the most severe droughts (SPI less than −2 have a return period of 10 years. The SPI corresponding to the rainy season (April–September (SPI9 has no significant trend and is used to classify wet/dry years. In order to establish the previous circulation patterns associated with interannual SPI9 variability, the composite fields of wet and dry years are compared. There is a tendency for wet (dry periods to take place during El Niño (La Niña years, when there are positive anomalies of precipitable water over the basin, when the zonal flow over the Pacific Ocean is weakened (intensified and/or when there are negative pressure anomalies in the southern part of the country and Antarctic sea. Some prediction schemes using multiple linear regressions were performed. One of the models derived using the forward stepwise method explained 42% of the SPI9 variance and retained two predictors related to circulation over the Pacific Ocean: one of them shows the relevance of the intensity of zonal flow in mid-latitudes, and the other is because of the influence of low pressure near the Neuquén River basin. The cross-validation used to prove model efficiency showed a correlation of 0.41 between observed and estimated SPI9; there was a probability of detection of wet (dry years of 80% (65% and a false alarm relation of 25% in both cases.

  11. Climate influences on Vaal River flow

    African Journals Online (AJOL)

    2016-04-02

    Apr 2, 2016 ... enriched NW-cloud bands over the Vaal River catchment, during the flood case study of January 2010. Comparison of. (Pacific) Southern Oscillation and east Atlantic influence on Vaal River discharge reveals the former drives evaporative losses while the latter provides an advance warning of flow ...

  12. Ecological flow requirements for South African rivers

    CSIR Research Space (South Africa)

    Ferrar, AA

    1989-01-01

    Full Text Available This document contains the proceedings of a workshop which was convened to debate the ecological flow requirements of South African rivers. Topics which are discussed include the influence of weirs and impoundments, the quantity requirements...

  13. Sensitivity of peak flow to the change of rainfall temporal pattern due to warmer climate

    Science.gov (United States)

    Fadhel, Sherien; Rico-Ramirez, Miguel Angel; Han, Dawei

    2018-05-01

    The widely used design storms in urban drainage networks has different drawbacks. One of them is that the shape of the rainfall temporal pattern is fixed regardless of climate change. However, previous studies have shown that the temporal pattern may scale with temperature due to climate change, which consequently affects peak flow. Thus, in addition to the scaling of the rainfall volume, the scaling relationship for the rainfall temporal pattern with temperature needs to be investigated by deriving the scaling values for each fraction within storm events, which is lacking in many parts of the world including the UK. Therefore, this study analysed rainfall data from 28 gauges close to the study area with a 15-min resolution as well as the daily temperature data. It was found that, at warmer temperatures, the rainfall temporal pattern becomes less uniform, with more intensive peak rainfall during higher intensive times and weaker rainfall during less intensive times. This is the case for storms with and without seasonal separations. In addition, the scaling values for both the rainfall volume and the rainfall fractions (i.e. each segment of rainfall temporal pattern) for the summer season were found to be higher than the corresponding results for the winter season. Applying the derived scaling values for the temporal pattern of the summer season in a hydrodynamic sewer network model produced high percentage change of peak flow between the current and future climate. This study on the scaling of rainfall fractions is the first in the UK, and its findings are of importance to modellers and designers of sewer systems because it can provide more robust scenarios for flooding mitigation in urban areas.

  14. Simulation of Sediment and Cesium Transport in the Ukedo River and the Ogi Dam Reservoir during a Rainfall Event using the TODAM Code

    Energy Technology Data Exchange (ETDEWEB)

    Onishi, Yasuo; Yokuda, Satoru T.; Kurikami, Hiroshi

    2014-03-28

    The accident at the Fukushima Daiichi Nuclear Power Plant in March 2011 caused widespread environmental contamination. Although decontamination activities have been performed in residential areas of the Fukushima area, decontamination of forests, rivers, and reservoirs is still controversial because of the economical, ecological, and technical difficulties. Thus, an evaluation of contaminant transport in such an environment is important for safety assessment and for implementation of possible countermeasures to reduce radiation exposure to the public. The investigation revealed that heavy rainfall events play a significant role in transporting radioactive cesium deposited on the land surface, via soil erosion and sediment transport in rivers. Therefore, we simulated the sediment and cesium transport in the Ukedo River and its tributaries in Fukushima Prefecture, including the Ogaki Dam Reservoir, and the Ogi Dam Reservoir of the Oginosawa River in Fukushima Prefecture during and after a heavy rainfall event by using the TODAM (Time-dependent, One-dimensional Degradation And Migration) code. The main outcomes are the following: • Suspended sand is mostly deposited on the river bottom. Suspended silt and clay, on the other hand, are hardly deposited in the Ukedo River and its tributaries except in the Ogaki Dam Reservoir in the Ukedo River even in low river discharge conditions. • Cesium migrates mainly during high river discharge periods during heavy rainfall events. Silt and clay play more important roles in cesium transport to the sea than sand does. • The simulation results explain variations in the field data on cesium distributions in the river. Additional field data currently being collected and further modeling with these data may shed more light on the cesium distribution variations. • Effects of 40-hour heavy rainfall events on clay and cesium transport continue for more than a month. This is because these reservoirs slow down the storm-induced high

  15. Grey Forecast Rainfall with Flow Updating Algorithm for Real-Time Flood Forecasting

    Directory of Open Access Journals (Sweden)

    Jui-Yi Ho

    2015-04-01

    Full Text Available The dynamic relationship between watershed characteristics and rainfall-runoff has been widely studied in recent decades. Since watershed rainfall-runoff is a non-stationary process, most deterministic flood forecasting approaches are ineffective without the assistance of adaptive algorithms. The purpose of this paper is to propose an effective flow forecasting system that integrates a rainfall forecasting model, watershed runoff model, and real-time updating algorithm. This study adopted a grey rainfall forecasting technique, based on existing hourly rainfall data. A geomorphology-based runoff model can be used for simulating impacts of the changing geo-climatic conditions on the hydrologic response of unsteady and non-linear watershed system, and flow updating algorithm were combined to estimate watershed runoff according to measured flow data. The proposed flood forecasting system was applied to three watersheds; one in the United States and two in Northern Taiwan. Four sets of rainfall-runoff simulations were performed to test the accuracy of the proposed flow forecasting technique. The results indicated that the forecast and observed hydrographs are in good agreement for all three watersheds. The proposed flow forecasting system could assist authorities in minimizing loss of life and property during flood events.

  16. Visualization of Flow Alternatives, Lower Missouri River

    Science.gov (United States)

    Jacobson, Robert B.; Heuser, Jeanne

    2002-01-01

    Background The U.S. Army Corps of Engineers (COE) 'Missouri River Master Water Control Manual' (Master Manual) review has resulted in consideration of many flow alternatives for managing the water in the river (COE, 2001; 1998a). The purpose of this report is to present flow-management alternative model results in a way that can be easily visualized and understood. This report was updated in October 2001 to focus on the specific flow-management alternatives presented by the COE in the 'Master Manual Revised Draft Environmental Impact Statement' (RDEIS; COE, 2001). The original version (February 2000) is available by clicking here. The COE, U.S. Fish and Wildlife Service (FWS), Missouri River states, and Missouri River basin tribes have been participating in discussions concerning water management of the Missouri River mainstem reservoir system (MRMRS), the Missouri River Bank Stabilization and Navigation Project, and the Kansas River reservoir system since 1986. These discussions include general input to the revision of the Master Manual as well as formal consultation under Section 7 of the Endangered Species Act. In 2000, the FWS issued a Biological Opinion that prescribed changes to reservoir management on the Missouri River that were believed to be necessary to preclude jeopardy to three endangered species, the pallid sturgeon, piping plover, and interior least tern (USFWS, 2000). The combined Missouri River system is large and complex, including many reservoirs, control structures, and free-flowing reaches extending over a broad region. The ability to assess future impacts of altered management scenarios necessarily involves complex, computational models that attempt to integrate physical, chemical, biological, and economic effects. Graphical visualization of the model output is intended to improve understanding of the differences among flow-management alternatives.

  17. Flow Forecasting in Drainage Systems with Extrapolated Radar Rainfall Data and Auto Calibration on Flow Observations

    DEFF Research Database (Denmark)

    Thorndahl, Søren Liedtke; Grum, M.; Rasmussen, Michael R.

    2011-01-01

    Forecasting of flows, overflow volumes, water levels, etc. in drainage systems can be applied in real time control of drainage systems in the future climate in order to fully utilize system capacity and thus save possible construction costs. An online system for forecasting flows and water levels......-calibrated on flow measurements in order to produce the best possible forecast for the drainage system at all times. The system shows great potential for the implementation of real time control in drainage systems and forecasting flows and water levels.......Forecasting of flows, overflow volumes, water levels, etc. in drainage systems can be applied in real time control of drainage systems in the future climate in order to fully utilize system capacity and thus save possible construction costs. An online system for forecasting flows and water levels...... in a small urban catchment has been developed. The forecast is based on application of radar rainfall data, which by a correlation based technique, is extrapolated with a lead time up to two hours. The runoff forecast in the drainage system is based on a fully distributed MOUSE model which is auto...

  18. Detection of Anomalies and Changes of Rainfall in the Yellow River Basin, China, through Two Graphical Methods

    Directory of Open Access Journals (Sweden)

    Hao Wu

    2017-12-01

    Full Text Available This study aims to reveal rainfall anomalies and changes over the Yellow River Basin due to the fragile ecosystem and rainfall-related disasters. Common trend analyses relate to overall trends in mean values. Therefore, we used two graphical methods: the quantile perturbation method (QPM was used to investigate anomalies over time in extreme rainfall, and the partial trend method (PTM was used to analyze rainfall changes at different intensities. A nonparametric bootstrap procedure is proposed in order to identify significant PTM indices. The QPM indicated prevailing positive anomalies in extreme daily rainfall 50 years ago and in the middle reaches during the 1970s and 1980s. The PTM detected significant decreases in annual rainfall mainly in the latter half of the middle reaches, two-thirds of which occurred in high and heavy rainfall. Most stations in the middle and lower reaches showed significant decreases in rainy days. Daily rainfall intensity had a significant increase at 13 stations, where rainy days were generally decreasing. The combined effect of these opposing changes explains the prevailing absence of change in annual rainfall, and the observed decreases in annual rainfall can be attributed to the decreasing number of rainy days. The changes in rainy days and rainfall intensity were dominated by the wet season and dry season, respectively.

  19. Daily rainfall statistics of TRMM and CMORPH: A case for trans-boundary Gandak River basin

    Science.gov (United States)

    Kumar, Brijesh; Patra, Kanhu Charan; Lakshmi, Venkat

    2016-07-01

    Satellite precipitation products offer an opportunity to evaluate extreme events (flood and drought) for areas where rainfall data are not available or rain gauge stations are sparse. In this study, daily precipitation amount and frequency of TRMM 3B42V.7 and CMORPH products have been validated against daily rain gauge precipitation for the monsoon months (June-September or JJAS) from 2005-2010 in the trans-boundary Gandak River basin. The analysis shows that the both TRMM and CMORPH can detect rain and no-rain events, but they fail to capture the intensity of rainfall. The detection of precipitation amount is strongly dependent on the topography. In the plains areas, TRMM product is capable of capturing high-intensity rain events but in the hilly regions, it underestimates the amount of high-intensity rain events. On the other hand, CMORPH entirely fails to capture the high-intensity rain events but does well with low-intensity rain events in both hilly regions as well as the plain region. The continuous variable verification method shows better agreement of TRMM rainfall products with rain gauge data. TRMM fares better in the prediction of probability of occurrence of high-intensity rainfall events, but it underestimates intensity at high altitudes. This implies that TRMM precipitation estimates can be used for flood-related studies only after bias adjustment for the topography.

  20. Raindrop characteristics analysis (Oct 25, 2015) of natural rainfall in Zhengzhou city of Yellow River basin

    Science.gov (United States)

    Liu, Nana; Lin, Jing; Che, Shuhong; Yang, Xueqin; Li, Weiwei; Shen, Zhenzhou

    2018-03-01

    Raindrop characteristics, including speed and size of raindrops, in Zhengzhou city of Yellow River basin were analyzed through a natural rainfall on the loess slope. Results showed that the process of natural rainfall belonged to a parabola and counts, size and terminal velocity would increase with the rainfall intensity rising. Besides, the size and terminal velocity of natural raindrops were relatively scattered; In the process of individual rainfall, the terminal velocity and its peak value were mainly focused between 1∼5m/s and 3.4m/s, respectively. Size of raindrops were mainly consisted of 0.125-1.25mm, among which the terminal velocity of raindrops with a size of 0.125mm, 0.25mm, 0.375mm, 0.5mm, 0.75mm and 1mm were primarily 0.8-2.6m/s, 1-3.4m/s, 1.4-3.4m/s, 1.8-3.4m/s, 3-4.2m/s and 3.4-5m/s, respectively.

  1. Estimation of underground river water availability based on rainfall in the Maros karst region, South Sulawesi

    Science.gov (United States)

    Arsyad, Muhammad; Ihsan, Nasrul; Tiwow, Vistarani Arini

    2016-02-01

    Maros karst region, covering an area of 43.750 hectares, has water resources that determine the life around it. Water resources in Maros karst are in the rock layers or river underground in the cave. The data used in this study are primary and secondary data. Primary data includes characteristics of the medium. Secondary data is rainfall data from BMKG, water discharge data from the PSDA, South Sulawesi province in 1990-2010, and the other characteristics data Maros karst, namely cave, flora and fauna of the Bantimurung Bulusaraung National Park. Data analysis was conducted using laboratory test for medium characteristics Maros karst, rainfall and water discharge were analyzed using Minitab Program 1.5 to determine their profile. The average rainfall above 200 mm per year occurs in the range of 1999 to 2005. The availability of the water discharge at over 50 m3/s was happened in 1993 and 1995. Prediction was done by modeling Autoregressive Integrated Moving Average (ARIMA), with the rainfall data shows that the average precipitation for four years (2011-2014) will sharply fluctuate. The prediction of water discharge in Maros karst region was done for the period from January to August in 2011, including the type of 0. In 2012, the addition of the water discharge started up in early 2014.

  2. Modelling the effects of spatial and temporal resolution of rainfall and basin model on extreme river discharge

    NARCIS (Netherlands)

    Booij, Martijn J.

    2002-01-01

    Important characteristics of an appropriate river basin model, intended to study the effect of climate change on basin response, are the spatial and temporal resolution of the model and the rainfall input. The effects of input and model resolution on extreme discharge of a large river basin are

  3. Microelement Exploration Water Flow of Rimnik River

    OpenAIRE

    , N. Bajraktari; , B. Baraj; , T. Arbneshi; , S. Jusufi

    2016-01-01

    Compared to the increasing need on qualitative water use, many water şows are subject to a rising pollution by urban and industrial untreated water discharge, and in some cases by incidental run-offs. Besides them, there is also a great impact made by disseminated agricultural pollution and air and soil rinsing after atmospheric rainfalls. The main purpose of this paper is the micro-element exploration in water and sediments, along the water şow of Rimnik River. Some of the heavy metals: Pb, ...

  4. Comparison of short term rainfall forecasts for model based flow prediction in urban drainage systems

    DEFF Research Database (Denmark)

    Thorndahl, Søren; Poulsen, Troels Sander; Bøvith, Thomas

    2012-01-01

    Forecast based flow prediction in drainage systems can be used to implement real time control of drainage systems. This study compares two different types of rainfall forecasts – a radar rainfall extrapolation based nowcast model and a numerical weather prediction model. The models are applied...... performance of the system is found using the radar nowcast for the short leadtimes and weather model for larger lead times....

  5. Comparison of short-term rainfall forecasts for modelbased flow prediction in urban drainage systems

    DEFF Research Database (Denmark)

    Thorndahl, Søren; Ahm, Malte; Nielsen, Jesper Ellerbek

    2013-01-01

    Forecast-based flow prediction in drainage systems can be used to implement real-time control of drainage systems. This study compares two different types of rainfall forecast - a radar rainfall extrapolation-based nowcast model and a numerical weather prediction model. The models are applied...... performance of the system is found using the radar nowcast for the short lead times and the weather model for larger lead times....

  6. Experimental evidence of lateral flow in unsaturated homogeneous isotropic sloping soil due to rainfall

    NARCIS (Netherlands)

    Sinai, G.; Dirksen, C.

    2006-01-01

    This paper describes laboratory experimental evidence for lateral flow in the top layer of unsaturated sloping soil due to rainfall. Water was applied uniformly on horizontal and V-shaped surfaces of fine sand, at rates about 100 times smaller than the saturated hydraulic conductivity. Flow regimes

  7. Spatial Distribution of Annual and Monthly Rainfall Erosivity in the Jaguarí River Basin

    Directory of Open Access Journals (Sweden)

    Lucas Machado Pontes

    2017-11-01

    Full Text Available ABSTRACT The Jaguarí River Basin forms the main water supply sources for the São Paulo Metropolitan Region and other cities in the state. Since the kinetic energy of rainfall is the driving force of water erosion, the main cause of land and water degradation, we tested the hypothesis of correlation between the erosive potential of rainfall (erosivity and geographical coordinates and altitude for the purpose of predicting the spatial and temporal distribution of the rainfall erosivity index (EI30 in the basin. An equation was used to estimate the (EI30 in accordance with the average monthly and total annual rainfall at rainfall stations with data available for the study area. In the regression kriging technique, the deterministic part was modeled using multiple linear regression between the dependent variable (EI30 and environmental predictor variables: latitude, longitude, and altitude. From the result of equations and the maps generated, a direct correlation between erosivity and altitude could be observed. Erosivity has a markedly seasonal behavior in accordance with the rainy season from October to March. This season concentrates 86 % of the estimated EI30 values, with monthly maximum values of up to 2,342 MJ mm ha-1 h-1 month-1 between December and January, and minimum of 34 MJ mm ha-1 h-1 month-1 in August. The highest values were found in the Mantiqueira Range region (annual average of up to 12,000 MJ mm ha-1 h-1, a region that should be prioritized in soil and water conservation efforts. From this validation, good precision and accuracy of the model was observed for the long period of the annual average, which is the main factor used in soil loss prediction models.

  8. Comparison of Conventional and ANN Models for River Flow Forecasting

    Science.gov (United States)

    Jain, A.; Ganti, R.

    2011-12-01

    Hydrological models are useful in many water resources applications such as flood control, irrigation and drainage, hydro power generation, water supply, erosion and sediment control, etc. Estimates of runoff are needed in many water resources planning, design development, operation and maintenance activities. River flow is generally estimated using time series or rainfall-runoff models. Recently, soft artificial intelligence tools such as Artificial Neural Networks (ANNs) have become popular for research purposes but have not been extensively adopted in operational hydrological forecasts. There is a strong need to develop ANN models based on real catchment data and compare them with the conventional models. In this paper, a comparative study has been carried out for river flow forecasting using the conventional and ANN models. Among the conventional models, multiple linear, and non linear regression, and time series models of auto regressive (AR) type have been developed. Feed forward neural network model structure trained using the back propagation algorithm, a gradient search method, was adopted. The daily river flow data derived from Godavari Basin @ Polavaram, Andhra Pradesh, India have been employed to develop all the models included here. Two inputs, flows at two past time steps, (Q(t-1) and Q(t-2)) were selected using partial auto correlation analysis for forecasting flow at time t, Q(t). A wide range of error statistics have been used to evaluate the performance of all the models developed in this study. It has been found that the regression and AR models performed comparably, and the ANN model performed the best amongst all the models investigated in this study. It is concluded that ANN model should be adopted in real catchments for hydrological modeling and forecasting.

  9. Experimental evidence of lateral flow in unsaturated homogeneous isotropic sloping soil due to rainfall

    Science.gov (United States)

    Sinai, G.; Dirksen, C.

    2006-12-01

    This paper describes laboratory experimental evidence for lateral flow in the top layer of unsaturated sloping soil due to rainfall. Water was applied uniformly on horizontal and V-shaped surfaces of fine sand, at rates about 100 times smaller than the saturated hydraulic conductivity. Flow regimes near the surface and in the soil bulk were studied by using dyes. Streamlines and streak lines and wetting fronts were visually studied and photographed through a vertical glass wall. Near wetting fronts the flow direction was always perpendicular to the fronts owing to dominant matrix potential gradients. Thus, during early wetting of dry sloping sand, the flow direction is directed upslope. Far above a wetting front the flow was vertical due to the dominance of gravity. Downslope flow was observed during decreasing rainfall and dry periods. The lateral movement was largest near the soil surface and decayed with soil depth. Unstable downslope lateral flow close to the soil surface was attributed to non-Darcian flow due to variable temporal and spatial raindrop distributions. The experiments verify the theory that predicts unsaturated downslope lateral flow in sloping soil due to rainfall dynamics only, without apparent soil texture difference or anisotropy. This phenomenon could have significant implications for hillside hydrology, desert agriculture, irrigation management, etc., as well as for the basic mechanisms of surface runoff and erosion.

  10. The influence of Atmospheric Rivers over the South Atlantic on rainfall in South Africa

    Science.gov (United States)

    Ramos, A. M.; Trigo, R. M.; Blamey, R. C.; Tome, R.; Reason, C. J. C.

    2017-12-01

    An automated atmospheric river (AR) detection algorithm is used for the South Atlantic Ocean basin, allowing the identification of the major ARs impinging on the west coast of South Africa during the austral winter months (April-September) for the period 1979-2014, using two reanalysis products (NCEP-NCAR and ERA-Interim). The two products show relatively good agreement, with 10-15 persistent ARs (lasting 18h or longer) occurring on average per winter and nearly two thirds of these systems occurring poleward of 35°S. The relationship between persistent AR activity and winter rainfall is demonstrated using South African Weather Service rainfall data. Most stations positioned in areas of high topography contained the highest percentage of rainfall contributed by persistent ARs, whereas stations downwind, to the east of the major topographic barriers, had the lowest contributions. Extreme rainfall days in the region are also ranked by their magnitude and spatial extent. It is found that around 70% of the top 50 daily winter rainfall extremes in South Africa were in some way linked to ARs (both persistent and non-persistent). Results suggest that although persistent ARs are important contributors to heavy rainfall events, they are not necessarily a prerequisite. Overall, the findings of this study support akin assessments in the last decade on ARs in the northern hemisphere bound for the western coasts of USA and Europe. AcknowledgementsThe financial support for attending this workshop was possible through FCT project UID/GEO/50019/2013 - Instituto Dom Luiz. The author wishes also to acknowledge the contribution of project IMDROFLOOD - Improving Drought and Flood Early Warning, Forecasting and Mitigation using real-time hydroclimatic indicators (WaterJPI/0004/2014, Funded by Fundação para a Ciência e a Tecnologia, Portugal (FCT)), with the data provided to achieve this work. A. M. Ramos was also supported by a FCT postdoctoral grant (FCT/DFRH/ SFRH/BPD/84328/2012).

  11. Chance-constrained overland flow modeling for improving conceptual distributed hydrologic simulations based on scaling representation of sub-daily rainfall variability

    International Nuclear Information System (INIS)

    Han, Jing-Cheng; Huang, Guohe; Huang, Yuefei; Zhang, Hua; Li, Zhong; Chen, Qiuwen

    2015-01-01

    Lack of hydrologic process representation at the short time-scale would lead to inadequate simulations in distributed hydrological modeling. Especially for complex mountainous watersheds, surface runoff simulations are significantly affected by the overland flow generation, which is closely related to the rainfall characteristics at a sub-time step. In this paper, the sub-daily variability of rainfall intensity was considered using a probability distribution, and a chance-constrained overland flow modeling approach was proposed to capture the generation of overland flow within conceptual distributed hydrologic simulations. The integrated modeling procedures were further demonstrated through a watershed of China Three Gorges Reservoir area, leading to an improved SLURP-TGR hydrologic model based on SLURP. Combined with rainfall thresholds determined to distinguish various magnitudes of daily rainfall totals, three levels of significance were simultaneously employed to examine the hydrologic-response simulation. Results showed that SLURP-TGR could enhance the model performance, and the deviation of runoff simulations was effectively controlled. However, rainfall thresholds were so crucial for reflecting the scaling effect of rainfall intensity that optimal levels of significance and rainfall threshold were 0.05 and 10 mm, respectively. As for the Xiangxi River watershed, the main runoff contribution came from interflow of the fast store. Although slight differences of overland flow simulations between SLURP and SLURP-TGR were derived, SLURP-TGR was found to help improve the simulation of peak flows, and would improve the overall modeling efficiency through adjusting runoff component simulations. Consequently, the developed modeling approach favors efficient representation of hydrological processes and would be expected to have a potential for wide applications. - Highlights: • We develop an improved hydrologic model considering the scaling effect of rainfall. • A

  12. Chance-constrained overland flow modeling for improving conceptual distributed hydrologic simulations based on scaling representation of sub-daily rainfall variability

    Energy Technology Data Exchange (ETDEWEB)

    Han, Jing-Cheng [State Key Laboratory of Hydroscience & Engineering, Department of Hydraulic Engineering, Tsinghua University, Beijing 100084 (China); Huang, Guohe, E-mail: huang@iseis.org [Institute for Energy, Environment and Sustainable Communities, University of Regina, Regina, Saskatchewan S4S 0A2 (Canada); Huang, Yuefei [State Key Laboratory of Hydroscience & Engineering, Department of Hydraulic Engineering, Tsinghua University, Beijing 100084 (China); Zhang, Hua [College of Science and Engineering, Texas A& M University — Corpus Christi, Corpus Christi, TX 78412-5797 (United States); Li, Zhong [Institute for Energy, Environment and Sustainable Communities, University of Regina, Regina, Saskatchewan S4S 0A2 (Canada); Chen, Qiuwen [Center for Eco-Environmental Research, Nanjing Hydraulics Research Institute, Nanjing 210029 (China)

    2015-08-15

    Lack of hydrologic process representation at the short time-scale would lead to inadequate simulations in distributed hydrological modeling. Especially for complex mountainous watersheds, surface runoff simulations are significantly affected by the overland flow generation, which is closely related to the rainfall characteristics at a sub-time step. In this paper, the sub-daily variability of rainfall intensity was considered using a probability distribution, and a chance-constrained overland flow modeling approach was proposed to capture the generation of overland flow within conceptual distributed hydrologic simulations. The integrated modeling procedures were further demonstrated through a watershed of China Three Gorges Reservoir area, leading to an improved SLURP-TGR hydrologic model based on SLURP. Combined with rainfall thresholds determined to distinguish various magnitudes of daily rainfall totals, three levels of significance were simultaneously employed to examine the hydrologic-response simulation. Results showed that SLURP-TGR could enhance the model performance, and the deviation of runoff simulations was effectively controlled. However, rainfall thresholds were so crucial for reflecting the scaling effect of rainfall intensity that optimal levels of significance and rainfall threshold were 0.05 and 10 mm, respectively. As for the Xiangxi River watershed, the main runoff contribution came from interflow of the fast store. Although slight differences of overland flow simulations between SLURP and SLURP-TGR were derived, SLURP-TGR was found to help improve the simulation of peak flows, and would improve the overall modeling efficiency through adjusting runoff component simulations. Consequently, the developed modeling approach favors efficient representation of hydrological processes and would be expected to have a potential for wide applications. - Highlights: • We develop an improved hydrologic model considering the scaling effect of rainfall. • A

  13. The bi-decadal rainfall cycle, Southern Annular Mode and tropical cyclones over the Limpopo River Basin, southern Africa

    CSIR Research Space (South Africa)

    Malherbe, J

    2014-06-01

    Full Text Available contribution to rainfall by tropical cyclones and depressions. The findings suggest that a broadening of the Hadley circulation underpinned by an anomalous anticyclonic pattern to the east of southern Africa altered tropospheric steering flow, relative...

  14. Regional scale flood modeling using NEXRAD rainfall, GIS, and HEC-HMS/RAS: a case study for the San Antonio River Basin Summer 2002 storm event.

    Science.gov (United States)

    Knebl, M R; Yang, Z-L; Hutchison, K; Maidment, D R

    2005-06-01

    This paper develops a framework for regional scale flood modeling that integrates NEXRAD Level III rainfall, GIS, and a hydrological model (HEC-HMS/RAS). The San Antonio River Basin (about 4000 square miles, 10,000 km2) in Central Texas, USA, is the domain of the study because it is a region subject to frequent occurrences of severe flash flooding. A major flood in the summer of 2002 is chosen as a case to examine the modeling framework. The model consists of a rainfall-runoff model (HEC-HMS) that converts precipitation excess to overland flow and channel runoff, as well as a hydraulic model (HEC-RAS) that models unsteady state flow through the river channel network based on the HEC-HMS-derived hydrographs. HEC-HMS is run on a 4 x 4 km grid in the domain, a resolution consistent with the resolution of NEXRAD rainfall taken from the local river authority. Watershed parameters are calibrated manually to produce a good simulation of discharge at 12 subbasins. With the calibrated discharge, HEC-RAS is capable of producing floodplain polygons that are comparable to the satellite imagery. The modeling framework presented in this study incorporates a portion of the recently developed GIS tool named Map to Map that has been created on a local scale and extends it to a regional scale. The results of this research will benefit future modeling efforts by providing a tool for hydrological forecasts of flooding on a regional scale. While designed for the San Antonio River Basin, this regional scale model may be used as a prototype for model applications in other areas of the country.

  15. Rainfall measurement based on in-situ storm drainage flow sensors

    DEFF Research Database (Denmark)

    Ahm, Malte; Rasmussen, Michael Robdrup

    2017-01-01

    Data for adjustment of weather radar rainfall estimations are mostly obtained from rain gauge observations. However, the density of rain gauges is often very low. Yet in many urban catchments, runoff sensors are typically available which can measure the rainfall indirectly. By utilising these sen......Data for adjustment of weather radar rainfall estimations are mostly obtained from rain gauge observations. However, the density of rain gauges is often very low. Yet in many urban catchments, runoff sensors are typically available which can measure the rainfall indirectly. By utilising...... these sensors, it may be possible to improve the ground rainfall estimate, and thereby improve the quantitative precipitation estimation from weather radars for urban drainage applications. To test the hypothesis, this paper presents a rainfall measurement method based on flow rate measurements from well......-defined urban surfaces. This principle was used to design a runoff measurement system in a parking structure in Aalborg, Denmark, where it was evaluated against rain gauges. The measurements show that runoff measurements from well-defined urban surfaces perform just as well as rain gauges. This opens up...

  16. Evaluation TRMM Rainfall Data In Hydrological Modeling For An Ungaged In Lhasa River Basin

    Science.gov (United States)

    Ji, H. J.; Liu, J.

    2017-12-01

    Evaluation TRMM Rainfall Data In Hydrological Modeling For An Ungaged In Lhasa River BasinHaijuan Ji1* Jintao Liu1,2 Shanshan Xu1___________________ 1College of Hydrology and Water Resources, Hohai University, Nanjing 210098, People's Republic of China 2State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Hohai University, Nanjing 210098, People's Republic of China ___________________ * Corresponding author. Tel.: +86-025-83786973; Fax: +86-025-83786606. E-mail address: Hhu201510@163.com (H.J. Ji). Abstract: The Tibetan Plateau plays an important role in regulating the regional hydrological processes due to its high elevations and being the headwaters of many major Asian river basins. If familiar with the distribution of hydrological characteristics, will help us improve the level of development and utilization the water resources. However, there exist glaciers and snow with few sites. It is significance for us to understand the glacier and snow hydrological process in order to recognize the evolution of water resources in the Tibetan. This manuscript takes Lhasa River as the study area, taking use of ground, remote sensing and assimilation data, taking advantage of high precision TRMM precipitation data and MODIS snow cover data, first, according to the data from ground station evaluation of TRMM data in the application of the accuracy of the Lhasa River, and based on MODIS data fusion of multi source microwave snow making cloudless snow products, which are used for discriminant and analysis glacier and snow regulation mechanism on day scale, add snow and glacier unit into xinanjing model, this model can simulate the study region's runoff evolution, parameter sensitivity even spatial variation of hydrological characteristics the next ten years on region grid scale. The results of hydrological model in Lhasa River can simulate the glacier and snow runoff variation in high cold region better, to enhance the predictive ability of the spring

  17. Flow Regime Classification and Hydrological Characterization: A Case Study of Ethiopian Rivers

    Directory of Open Access Journals (Sweden)

    Belete Berhanu

    2015-06-01

    Full Text Available The spatiotemporal variability of a stream flow due to the complex interaction of catchment attributes and rainfall induce complexity in hydrology. Researchers have been trying to address this complexity with a number of approaches; river flow regime is one of them. The flow regime can be quantified by means of hydrological indices characterizing five components: magnitude, frequency, duration, timing, and rate of change of flow. Similarly, this study aimed to understand the flow variability of Ethiopian Rivers using the observed daily flow data from 208 gauging stations in the country. With this process, the Hierarchical Ward Clustering method was implemented to group the streams into three flow regimes (1 ephemeral, (2 intermittent, and (3 perennial. Principal component analysis (PCA is also applied as the second multivariate analysis tool to identify dominant hydrological indices that cause the variability in the streams. The mean flow per unit catchment area (QmAR and Base flow index (BFI show an incremental trend with ephemeral, intermittent and perennial streams. Whereas the number of mean zero flow days ratio (ZFI and coefficient of variation (CV show a decreasing trend with ephemeral to perennial flow regimes. Finally, the streams in the three flow regimes were characterized with the mean and standard deviation of the hydrological variables and the shape, slope, and scale of the flow duration curve. Results of this study are the basis for further understanding of the ecohydrological processes of the river basins in Ethiopia.

  18. Rainfall-runoff characteristics and effects of increased urban density on streamflow and infiltration in the eastern part of the San Jacinto River basin, Riverside County, California

    Science.gov (United States)

    Guay, Joel R.

    2002-01-01

    To better understand the rainfall-runoff characteristics of the eastern part of the San Jacinto River Basin and to estimate the effects of increased urbanization on streamflow, channel infiltration, and land-surface infiltration, a long-term (1950?98) time series of monthly flows in and out of the channels and land surfaces were simulated using the Hydrologic Simulation Program- FORTRAN (HSPF) rainfall-runoff model. Channel and land-surface infiltration includes rainfall or runoff that infiltrates past the zone of evapotranspiration and may become ground-water recharge. The study area encompasses about 256 square miles of the San Jacinto River drainage basin in Riverside County, California. Daily streamflow (for periods with available data between 1950 and 1998), and daily rainfall and evaporation (1950?98) data; monthly reservoir storage data (1961?98); and estimated mean annual reservoir inflow data (for 1974 conditions) were used to calibrate the rainfall-runoff model. Measured and simulated mean annual streamflows for the San Jacinto River near San Jacinto streamflow-gaging station (North-South Fork subbasin) for 1950?91 and 1997?98 were 14,000 and 14,200 acre-feet, respectively, a difference of 1.4 percent. The standard error of the mean for measured and simulated annual streamflow in the North-South Fork subbasin was 3,520 and 3,160 acre-feet, respectively. Measured and simulated mean annual streamflows for the Bautista Creek streamflow-gaging station (Bautista Creek subbasin) for 1950?98 were 980 acre-feet and 991 acre-feet, respectively, a difference of 1.1 percent. The standard error of the mean for measured and simulated annual streamflow in the Bautista Creek subbasin was 299 and 217 acre-feet, respectively. Measured and simulated annual streamflows for the San Jacinto River above State Street near San Jacinto streamflow-gaging station (Poppet subbasin) for 1998 were 23,400 and 23,500 acre-feet, respectively, a difference of 0.4 percent. The simulated

  19. Evaluation of synthetic rainfall application with respect to the flow volume at upstream Brantas watershed, East Java Province of Indonesia

    Directory of Open Access Journals (Sweden)

    Limantara Lily Montarcih

    2017-12-01

    Full Text Available Indonesian Technical Implementation Unit (UPT of Synthetic Rainfall has modified climate by generating synthetic rainfall from 9th May until 4th June 2013. This unit has cooperated with the Department of Technological Study and Application (BPPT of Indonesia and Perum Jasa Tirta I and TNI AU Lanud Abdulrachman Saleh. This study intended to increase reservoirs water level in upstream Brantas watershed, one of them is Sutami reservoir. Successive grade evaluation of synthetic rainfall used the method of Double Ratio and Flow Discharge. The target area is upstream Brantas watershed that is represented by 12 rainfall stations and the control area is in the distance of ±30 km from the boundary of upstream Brantas watershed and is represented by 5 rainfall stations. Results show rainfall increasing by 152.05% according to the Double Ratio method and the increase of flow discharge from Sutami reservoir by 74.19% according to the Flow Discharge method.

  20. Evaluation of Environmental Flows in Rivers Using Hydrological Methods (Case study: The Barandozchi River- Urmia Lake Basin

    Directory of Open Access Journals (Sweden)

    S. Mostafavi

    2017-01-01

    Full Text Available Introduction Development of water resources projects are accompanied by several environmental impacts, among them, the changes in the natural flow regime and the reduction of downstream water flows. With respect to the water shortages and non-uniform distribution of rainfall, sustainable management of water resources would be inevitable. In order to prevent negative effects on long-term river ecosystems, it is necessary to preserve the ecological requirements of the river systems. The assessment of environmental flow requirements in a river ecosystem is a challenging practice all over the world, and in particular, in developing countries such as Iran. Environmental requirements of rivers are often defined as a suite of flow discharges of certain magnitude, timing, frequency and duration. These flows ensure a flow regime capable of sustaining a complex set of aquatic habitats and ecosystem processes and are referred to as "environmental flows". There are several methods for determining environmental flows. The majority of these methods can be grouped into four reasonably distinct categories, namely as: hydrological, hydraulic rating, habitat simulation (or rating, and holistic methodologies. However, the current knowledge of river ecology and existing data on the needs of aquatic habitats for water quantity and quality is very limited. It is considered that there is no unique and universal method to adapt to different rivers and/or different reaches in a river. The main aim of the present study was to provide with a framework to determine environmental flow requirements of a typical perennial river using eco-hydrological methods. The Barandozchi River was selected as an important water body in the Urmia Lake Basin, Iran. The preservation of the river lives, the restoration of the internationally recognized Urmia Lake, and the elimination of negative impact from the construction of the Barandoz dam on this river were the main concerns in this

  1. Risk and size estimation of debris flow caused by storm rainfall in mountain regions

    Institute of Scientific and Technical Information of China (English)

    CHENG; Genwei

    2003-01-01

    Debris flow is a common disaster in mountain regions. The valley slope, storm rainfall and amassed sand-rock materials in a watershed may influence the types of debris flow. The bursting of debris flow is not a pure random event. Field investigations show the periodicity of its burst, but no directive evidence has been found yet. A risk definition of debris flow is proposed here based upon the accumulation and the starting conditions of loose material in channel. According to this definition, the risk of debris flow is of quasi-periodicity. A formula of risk estimation is derived. Analysis of relative factors reveals the relationship between frequency and size of debris flow. For a debris flow creek, the longer the time interval between two occurrences of debris flows is, the bigger the bursting event will be.

  2. Extreme river flow dependence in Northern Scotland

    Science.gov (United States)

    Villoria, M. Franco; Scott, M.; Hoey, T.; Fischbacher-Smith, D.

    2012-04-01

    Various methods for the spatial analysis of hydrologic data have been developed recently. Here we present results using the conditional probability approach proposed by Keef et al. [Appl. Stat. (2009): 58,601-18] to investigate spatial interdependence in extreme river flows in Scotland. This approach does not require the specification of a correlation function, being mostly suitable for relatively small geographical areas. The work is motivated by the Flood Risk Management Act (Scotland (2009)) which requires maps of flood risk that take account of spatial dependence in extreme river flow. The method is based on two conditional measures of spatial flood risk: firstly the conditional probability PC(p) that a set of sites Y = (Y 1,...,Y d) within a region C of interest exceed a flow threshold Qp at time t (or any lag of t), given that in the specified conditioning site X > Qp; and, secondly the expected number of sites within C that will exceed a flow Qp on average (given that X > Qp). The conditional probabilities are estimated using the conditional distribution of Y |X = x (for large x), which can be modeled using a semi-parametric approach (Heffernan and Tawn [Roy. Statist. Soc. Ser. B (2004): 66,497-546]). Once the model is fitted, pseudo-samples can be generated to estimate functionals of the joint tails of the distribution of (Y,X). Conditional return level plots were directly compared to traditional return level plots thus improving our understanding of the dependence structure of extreme river flow events. Confidence intervals were calculated using block bootstrapping methods (100 replicates). We report results from applying this approach to a set of four rivers (Dulnain, Lossie, Ewe and Ness) in Northern Scotland. These sites were chosen based on data quality, spatial location and catchment characteristics. The river Ness, being the largest (catchment size 1839.1km2) was chosen as the conditioning river. Both the Ewe (441.1km2) and Ness catchments have

  3. Dynamic Critical Rainfall-Based Flash Flood Early Warning and Forecasting for Medium-Small Rivers

    Science.gov (United States)

    Liu, Z.; Yang, D.; Hu, J.

    2012-04-01

    China is extremely frequent food disasters hit countries, annual flood season flash floods triggered by rainfall, mudslides, landslides have caused heavy casualties and property losses, not only serious threaten the lives of the masses, but the majority of seriously restricting the mountain hill areas of economic and social development and the people become rich, of building a moderately prosperous society goals. In the next few years, China will focus on prevention and control area in the flash flood disasters initially built "for the surveillance, communications, forecasting, early warning and other non-engineering measure based, non-engineering measures and the combinations of engineering measures," the mitigation system. The latest progresses on global torrential flood early warning and forecasting techniques are reviewed in this paper, and then an early warning and forecasting approach is proposed on the basis of a distributed hydrological model according to dynamic critical rainfall index. This approach has been applied in Suichuanjiang River basin in Jiangxi province, which is expected to provide valuable reference for building a national flash flood early warning and forecasting system as well as control of such flooding.

  4. Hydrochemical evidence for mixing of river water and groundwater during high-flow conditions, lower Suwannee River basin, Florida, USA

    Science.gov (United States)

    Crandall, C.A.; Katz, B.G.; Hirten, J.J.

    1999-01-01

    Karstic aquifers are highly susceptible to rapid infiltration of river water, particularly during periods of high flow. Following a period of sustained rainfall in the Suwannee River basin, Florida, USA, the stage of the Suwannee River rose from 3.0 to 5.88 m above mean sea level in April 1996 and discharge peaked at 360 m3/s. During these high-flow conditions, water from the Suwannee River migrated directly into the karstic Upper Floridan aquifer, the main source of water supply for the area. Changes in the chemical composition of groundwater were quantified using naturally occurring geochemical tracers and mass-balance modeling techniques. Mixing of river water with groundwater was indicated by a decrease in the concentrations of calcium, silica, and 222Rn; and by an increase in dissolved organic carbon (DOC), tannic acid, and chloride, compared to low-flow conditions in water from a nearby monitoring well, Wingate Sink, and Little River Springs. The proportion (fraction) of river water in groundwater ranged from 0.13 to 0.65 at Wingate Sink and from 0.5 to 0.99 at well W-17258, based on binary mixing models using various tracers. The effectiveness of a natural tracer in quantifying mixing of river water and groundwater was related to differences in tracer concentration of the two end members and how conservatively the tracer reacted in the mixed water. Solutes with similar concentrations in the two end-member waters (Na, Mg, K, Cl, SO4, SiO2) were not as effective tracers for quantifying mixing of river water and groundwater as those with larger differences in end-member concentrations (Ca, tannic acid, DOC, 222Rn, HCO3). ?? Springer-Verlag.

  5. Daily disaggregation of simulated monthly flows using different rainfall datasets in southern Africa

    Directory of Open Access Journals (Sweden)

    D.A. Hughes

    2015-09-01

    New hydrological insights for the region: There are substantial regional differences in the success of the monthly hydrological model, which inevitably affects the success of the daily disaggregation results. There are also regional differences in the success of using global rainfall data sets (Climatic Research Unit (CRU datasets for monthly, National Oceanic and Atmospheric Administration African Rainfall Climatology, version 2 (ARC2 satellite data for daily. The overall conclusion is that the disaggregation method presents a parsimonious approach to generating daily flow simulations from existing monthly simulations and that these daily flows are likely to be useful for some purposes (e.g. water quality modelling, but less so for others (e.g. peak flow analysis.

  6. Rainfall intensity-duration thresholds for postfire debris-flow emergency-response planning

    Science.gov (United States)

    Cannon, S.H.; Boldt, E.M.; Laber, J.L.; Kean, J.W.; Staley, D.M.

    2011-01-01

    Following wildfires, emergency-response and public-safety agencies can be faced with evacuation and resource-deployment decisions well in advance of coming winter storms and during storms themselves. Information critical to these decisions is provided for recently burned areas in the San Gabriel Mountains of southern California. A compilation of information on the hydrologic response to winter storms from recently burned areas in southern California steeplands is used to develop a system for classifying magnitudes of hydrologic response. The four-class system describes combinations of reported volumes of individual debris flows, consequences of debris flows and floods in an urban setting, and spatial extents of the hydrologic response. The range of rainfall conditions associated with different magnitude classes is defined by integrating local rainfall data with the response magnitude information. Magnitude I events can be expected when within-storm rainfall accumulations (A) of given durations (D) fall above the threshold A = 0.4D0.5 and below A = 0.5D0.6 for durations greater than 1 h. Magnitude II events will be generated in response to rainfall accumulations and durations between A = 0.4D0.5 and A = 0.9D0.5 for durations less than 1 h, and between A = 0.5D0.6 and A = 0.9D0.5 or durations greater than 1 h. Magnitude III events can be expected in response to rainfall conditions above the threshold A = 0.9D0.5. Rainfall threshold-magnitude relations are linked with potential emergency-response actions as an emergency-response decision chart, which leads a user through steps to determine potential event magnitudes and identify possible evacuation and resource-deployment levels. Use of this information in planning and response decision-making process could result in increased safety for both the public and emergency responders. ?? 2011 US Government.

  7. A simulation of rainfall infiltration based on two-phase flow

    Science.gov (United States)

    Wang, Jun; Xi, Niannian; Liu, Gang; Hao, Shuang

    2016-04-01

    Rainfall infiltration in slope usually is one of major reasons cause landslide, which involves multiphase flow coupling with soil, water and gas. In order to study the mechanism of landslide caused by rainfall infiltration, a simulation of rainfall infiltration of DaPing slope, which locates in the Three Gorges Region of China, is presented based on the numerical solution of governing equations of two-phase flow in this paper. The results of this research suggest that there are two sections can be divided in the surface of slope, one is inflow area and the other is overflow area, according to where it is infiltration and discharge. The general inflow area is on the upside of slope, while the overflow area is on the underside. The middle section of slope is on a fluctuant position between inflow and overflow area, which is dramatically affected by the water content inside of slope. Moreover, the average rate of infiltration is more stable in both inflow and overflow area, whose numerical value is depend on the geometry and transmission characteristics of slope. And the factors of rainfall characteristics, surface flow and temperature have little effect on them. Furthermore, in the inflow area, when rainfall intensity is higher than infiltration the rain on the surface of slope will run off, otherwise water and gas will completely infiltrate through soil. The situation is different in the overflow area whose overland flow condition is depended on whether it is saturated or not inside of slope. When it is saturated in the slope, there is no infiltration in the overflow area. But when it is unsaturated, the infiltration intensity will equal to rainfall intensity. In a summary, the difference from inflow and overflow area is the evidence that the landslide may likely to happen on the slope of overflow area when it comes to a rainfall. It is disadvantageous for slope stability when transmitting the pressure of saturated water weight at the top of slope through the pore

  8. History of natural flows--Kansas River

    Science.gov (United States)

    Leeson, Elwood R.

    1958-01-01

    Through its Water Resources Division, the United States Geological Survey has become the major water-resources historian for the nation. The Geological Survey's collection of streamflow records in Kansas began on a very small scale in 1895 in response to some early irrigation interest, Since that time the program has grown, and we now have about 21 350 station-years of record accumulated. A station-year of record is defined as a continuous record of flow collected at a fixed point for a period of one year. Volume of data at hand, however, is not in itself an, adequate measure of its usefullness. An important element in historical streamflow data which enhances its value as a tool for the prediction of the future is the length of continuous records available in the area being studied. The records should be of sufficient length that they may be regarded as a reasonable sample of what has gone before and may be expected in the future. Table 1 gives a graphical inventory of the available streamflow records in Kansas. It shows that, in general, there is a fair coverage of stations with records of about thirty-seven years in length, This is not a long period as history goes but it does include considerable experience with floods and droughts.Although a large quantity of data on Kansas streamflow has been accumulated, hydrologists and planning engineers find that stream flow information for many areas of the State is considerably less than adequate. The problem of obtaining adequate coverage has been given careful study by the Kansas Water Resources Board in cooperation with the U. S. Geological Survey and a report entitled "Development of A Balanced Stream-Gaging Program For Kansas", has been published by the Board as Bulletin No. 4, That report presents an analysis of the existing stream-gaging program and recommendations for a program to meet the rapidly expanding needs for more comprehensive basic data.The Kansas River is formed near Junction City, Kansas, by the

  9. Application of Statistical Downscaling Techniques to Predict Rainfall and Its Spatial Analysis Over Subansiri River Basin of Assam, India

    Science.gov (United States)

    Barman, S.; Bhattacharjya, R. K.

    2017-12-01

    The River Subansiri is the major north bank tributary of river Brahmaputra. It originates from the range of Himalayas beyond the Great Himalayan range at an altitude of approximately 5340m. Subansiri basin extends from tropical to temperate zones and hence exhibits a great diversity in rainfall characteristics. In the Northern and Central Himalayan tracts, precipitation is scarce on account of high altitudes. On the other hand, Southeast part of the Subansiri basin comprising the sub-Himalayan and the plain tract in Arunachal Pradesh and Assam, lies in the tropics. Due to Northeast as well as Southwest monsoon, precipitation occurs in this region in abundant quantities. Particularly, Southwest monsoon causes very heavy precipitation in the entire Subansiri basin during May to October. In this study, the rainfall over Subansiri basin has been studied at 24 different locations by multiple linear and non-linear regression based statistical downscaling techniques and by Artificial Neural Network based model. APHRODITE's gridded rainfall data of 0.25˚ x 0.25˚ resolutions and climatic parameters of HadCM3 GCM of resolution 2.5˚ x 3.75˚ (latitude by longitude) have been used in this study. It has been found that multiple non-linear regression based statistical downscaling technique outperformed the other techniques. Using this method, the future rainfall pattern over the Subansiri basin has been analyzed up to the year 2099 for four different time periods, viz., 2020-39, 2040-59, 2060-79, and 2080-99 at all the 24 locations. On the basis of historical rainfall, the months have been categorized as wet months, months with moderate rainfall and dry months. The spatial changes in rainfall patterns for all these three types of months have also been analyzed over the basin. Potential decrease of rainfall in the wet months and months with moderate rainfall and increase of rainfall in the dry months are observed for the future rainfall pattern of the Subansiri basin.

  10. Rainfall thresholds for the initiation of debris flows at La Honda, California

    Science.gov (United States)

    Wilson, R.C.; Wieczorek, G.F.

    1995-01-01

    A simple numerical model, based on the physical analogy of a leaky barrel, can simulate significant features of the interaction between rainfall and shallow-hillslope pore pressures. The leaky-barrel-model threshold is consistent with, but slightly higher than, an earlier, purely empirical, threshold. The number of debris flows triggered by a storm can be related to the time and amount by which the leaky-barrel-model response exceeded the threshold during the storm. -from Authors

  11. Amazon river basin evapotranspiration and its influence on the rainfall in southern Brazil

    Science.gov (United States)

    Folegatti, M. V.; Wolff, W.

    2017-12-01

    Amazon river basin (ARB) presents a positive water balance, i.e. the precipitation is higher than evapotranspiration. Regarding the regional circulation, ARB evapotranspiration represents an important source of humidity for the South of Brazil. Thus, the aim of this work is to answer the question: how much is the correlation between ARB evapotranspiration and rainfall in South of Brazil? The shapefiles data of ARB and countries/states boundary were obtained through the Oak Ridge National Laboratory (ORNL) and Instituto Brasileiro de Geografia e Estatística (IBGE), respectively. According to rasters data, the precipitation was obtained from study of Numerical Terradynamic Simulation Group (NTSG) for images of Moderate Resolution Imaging Spectroradiometer (MODIS), under code MOD16A2, whereas rasters data for evapotranspiration were obtained from National Aeronautics and Space Administration (NASA) by Tropical Rainfall Measuring Mission Multi-Satellite Precipitation Analysis (TMPA), under code 3B43_V7. The products MOD16A2 and 3B43_V7 have a respective spatial resolution of 0.5º and 0.25º, and a monthly temporal resolution from January/2000 to December/2014. For ARB and South region of Brazil was calculated the mean evapotranspiration and mean precipitation through the pixels within of the respective polygons. To answer the question of this work was performed the cross-correlation analysis between these time series. We observed the highest value for the lag that corresponds the begin of spring (October), being 0.3 approximately. As a result, the mean precipitation on South region of Brazil during spring and summer was in the order of 15% to 30 %, explained by ARB evapotranspiration. For this reason, the maintenance of ARB is extremely important for water resource grant in South of Brazil.

  12. Assessment of climate change impact on river flow regimes in The Red River Delta, Vietnam – A case study of the Nhue-Day River Basin

    Directory of Open Access Journals (Sweden)

    Phan Cao Duong

    2016-09-01

    Full Text Available Global warming has caused dramatic changes in regional climate variability, particularly regarding fluctuations in temperature and rainfall. Thus, it is predicted that river flow regimes will be altered accordingly. The purpose of this paper is to present the results of modeling such changes by simulating discharge using the HEC-HMS model. The precipitation was projected using super-high resolution multiple climate models (20 km resolution with newly updated emission scenarios as the input for the HEC-HMS model for flow analysis at the Red River Basin in the northern area of Vietnam. The findings showed that climate change impact on the river flow regimes tend towards a decrease in the dry season and a longer duration of flood flow. A slight runoff reduction is simulated for November while a considerable runoff increase is modeled for July and August amounting to 30% and 25%, respectively. The discharge scenarios serve as a basis for water managers to develop suitable adaptation methods and responses on the river basin scale.

  13. Increasing trends in rainfall-runoff erosivity in the Source Region of the Three Rivers, 1961-2012.

    Science.gov (United States)

    Wang, Yousheng; Cheng, Congcong; Xie, Yun; Liu, Baoyuan; Yin, Shuiqing; Liu, Yingna; Hao, Yanfang

    2017-08-15

    As the head source of the two longest rivers in China and the longest river in Southeast Asia, the East Qinghai-Tibetan Plateau (QTP) is experiencing increasing thaw snowmelt and more heavy precipitation events under global warming, which might lead to soil erosion risk. To understand the potential driving force of soil erosion and its relationship with precipitation in the context of climate change, this study analyzed long-term variations in annual rainfall-runoff erosivity, a climatic index of soil erosion, by using the Mann-Kendall statistical test and Theil and Sen's approach in the Source Region of the Three Rivers during 1961-2012. The results showed the followings: (i) increasing annual rainfall-runoff erosivity was observed over the past 52years, with a mean relative trend index (RT 1 ) value of 12.1%. The increasing trend was more obvious for the latest two decades: RT 1 was nearly three times larger than that over the entire period; (ii) more precipitation events and a higher precipitation amount were the major forces for the increasing rainfall-runoff erosivity; (iii) similar rising trends in sediment yields, which corresponded to rainfall-runoff erosivity under slightly increasing vegetation coverage in the study area, implied a large contribution of rainfall-runoff erosivity to the increasing sediment yields; and (iv) high warming rates increased the risk of soil destruction, soil erosion and sediment yields. Conservation measures, such as enclosing grassland, returning grazing land to grassland and rotation grazing since the 1980s, have maintained vegetation coverage and should be continued and strengthened. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Changes in land cover, rainfall and stream flow in Upper Gilgel Abbay catchment, Blue Nile basin – Ethiopia

    Directory of Open Access Journals (Sweden)

    T. H. M. Rientjes

    2011-06-01

    Full Text Available In this study we evaluated changes in land cover and rainfall in the Upper Gilgel Abbay catchment in the Upper Blue Nile basin and how changes affected stream flow in terms of annual flow, high flows and low flows. Land cover change assessment was through classification analysis of remote sensing based land cover data while assessments on rainfall and stream flow data are by statistical analysis. Results of the supervised land cover classification analysis indicated that 50.9 % and 16.7 % of the catchment area was covered by forest in 1973 and 2001, respectively. This significant decrease in forest cover is mainly due to expansion of agricultural land.

    By use of a change detection procedure, three periods were identified for which changes in rainfall and stream flow were analyzed. Rainfall was analyzed at monthly base by use of the Mann-Kendall test statistic and results indicated a statistically significant, decreasing trend for most months of the year. However, for the wet season months of June, July and August rainfall has increased. In the period 1973–2005, the annual flow of the catchment decreased by 12.1 %. Low flow and high flow at daily base were analyzed by a low flow and a high flow index that is based on a 95 % and 5 % exceedance probability. Results of the low flow index indicated decreases of 18.1 % and 66.6 % for the periods 1982–2000 and 2001–2005 respectively. Results of high flows indicated an increase of 7.6 % and 46.6 % for the same periods. In this study it is concluded that over the period 1973–2005 stream flow has changed in the Gilgel Abbay catchment by changes in land cover and changes in rainfall.

  15. South Asia river flow projections and their implications for water resources

    Science.gov (United States)

    Mathison, C.; Wiltshire, A. J.; Falloon, P.; Challinor, A. J.

    2015-06-01

    benchmark for comparison against the downscaled GCMs. On the basis that these simulations are among the highest resolution climate simulations available we examine how useful they are for understanding the changes in water resources for the South Asia region. In general the downscaled GCMs capture the seasonality of the river flows, with timing of maximum river flows broadly matching the available observations and the downscaled ERA-Interim simulation. Typically the RCM simulations over-estimate the maximum river flows compared to the observations probably due to a positive rainfall bias and a lack of abstraction in the model although comparison with the downscaled ERA-Interim simulation is more mixed with only a couple of the gauges showing a bias compared with the downscaled GCM runs. The simulations suggest an increasing trend in annual mean river flows for some of the river gauges in this analysis, in some cases almost doubling by the end of the century; this trend is generally masked by the large annual variability of river flows for this region. The future seasonality of river flows does not change with the future maximum river flow rates still occuring during the ASM period, with a magnitude in some cases, greater than the present day natural variability. Increases in river flow during peak flow periods means additional water resource for irrigation, the largest usage of water in this region, but also has implications in terms of inundation risk. Low flow rates also increase which is likely to be important at times of the year when water is historically more scarce. However these projected increases in resource from rivers could be more than countered by changes in demand due to reductions in the quantity and quality of water available from groundwater, increases in domestic use due to a rising population or expansion of other industries such as hydro-electric power generation.

  16. Rainfall-runoff modelling and palaeoflood hydrology applied to reconstruct centennial scale records of flooding and aquifer recharge in ungauged ephemeral rivers

    Directory of Open Access Journals (Sweden)

    G. Benito

    2011-04-01

    Full Text Available In this study we propose a multi-source data approach for quantifying long-term flooding and aquifer recharge in ungauged ephemeral rivers. The methodology is applied to the Buffels River, at 9000 km2 the largest ephemeral river in Namaqualand (NW South Africa, a region with scarce stream flow records limiting research investigating hydrological response to global change. Daily discharge and annual flood series (1965–2006 were estimated from a distributed rainfall-runoff hydrological model (TETIS using rainfall gauge records located within the catchment. The model was calibrated and validated with data collected during a two year monitoring programme (2005–2006 at two stream flow stations, one each in the upper and lower reaches of the catchment. In addition to the modelled flow records, non-systematic flood data were reconstructed using both sedimentary and documentary evidence. The palaeoflood record identified at least 25 large floods during the last 700 yr; with the largest floods reaching a minimum discharge of 255 m3 s−1 (450 yr return period in the upper basin, and 510 m3 s−1 (100 yr return period in the lower catchment. Since AD 1925, the flood hydrology of the Buffels River has been characterised by a decrease in the magnitude and frequency of extreme floods, with palaeoflood discharges (period 1500–1921 five times greater than the largest modelled floods during the period 1965–2006. Large floods generated the highest hydrograph volumes, however their contribution to aquifer recharge is limited as this depends on other factors such as flood duration and storage capacity of the unsaturated zone prior to the flood. Floods having average return intervals of 5–10 yr (120–140 m3 s−1 and flowing for 12 days are able to fully saturate the Spektakel aquifer in the lower Buffels River basin. Alluvial aquifer storage capacity limiting potential recharge

  17. THRESH—Software for tracking rainfall thresholds for landslide and debris-flow occurrence, user manual

    Science.gov (United States)

    Baum, Rex L.; Fischer, Sarah J.; Vigil, Jacob C.

    2018-02-28

    Precipitation thresholds are used in many areas to provide early warning of precipitation-induced landslides and debris flows, and the software distribution THRESH is designed for automated tracking of precipitation, including precipitation forecasts, relative to thresholds for landslide occurrence. This software is also useful for analyzing multiyear precipitation records to compare timing of threshold exceedance with dates and times of historical landslides. This distribution includes the main program THRESH for comparing precipitation to several kinds of thresholds, two utility programs, and a small collection of Python and shell scripts to aid the automated collection and formatting of input data and the graphing and further analysis of output results. The software programs can be deployed on computing platforms that support Fortran 95, Python 2, and certain Unix commands. The software handles rainfall intensity-duration thresholds, cumulative recent-antecedent precipitation thresholds, and peak intensity thresholds as well as various measures of antecedent precipitation. Users should have predefined rainfall thresholds before running THRESH.

  18. South Asia river-flow projections and their implications for water resources

    Science.gov (United States)

    Mathison, C.; Wiltshire, A. J.; Falloon, P.; Challinor, A. J.

    2015-12-01

    South Asia is a region with a large and rising population, a high dependence on water intense industries, such as agriculture and a highly variable climate. In recent years, fears over the changing Asian summer monsoon (ASM) and rapidly retreating glaciers together with increasing demands for water resources have caused concern over the reliability of water resources and the potential impact on intensely irrigated crops in this region. Despite these concerns, there is a lack of climate simulations with a high enough resolution to capture the complex orography, and water resource analysis is limited by a lack of observations of the water cycle for the region. In this paper we present the first 25 km resolution regional climate projections of river flow for the South Asia region. Two global climate models (GCMs), which represent the ASM reasonably well are downscaled (1960-2100) using a regional climate model (RCM). In the absence of robust observations, ERA-Interim reanalysis is also downscaled providing a constrained estimate of the water balance for the region for comparison against the GCMs (1990-2006). The RCM river flow is routed using a river-routing model to allow analysis of present-day and future river flows through comparison with available river gauge observations. We examine how useful these simulations are for understanding potential changes in water resources for the South Asia region. In general the downscaled GCMs capture the seasonality of the river flows but overestimate the maximum river flows compared to the observations probably due to a positive rainfall bias and a lack of abstraction in the model. The simulations suggest an increasing trend in annual mean river flows for some of the river gauges in this analysis, in some cases almost doubling by the end of the century. The future maximum river-flow rates still occur during the ASM period, with a magnitude in some cases, greater than the present-day natural variability. Increases in river flow

  19. Dependence between sea surge, river flow and precipitation in south and west Britain

    Directory of Open Access Journals (Sweden)

    C. Svensson

    2004-01-01

    Full Text Available Estuaries around Great Britain may be at heightened risk of flooding because of the simultaneous occurrence of extreme sea surge and river flow, both of which may be caused by mid-latitude cyclones. A measure especially suited for extremes was employed to estimate dependence between river flow and sea surge. To assist in the interpretation of why flow-surge dependence occurs in some areas and not in others, the dependence between precipitation and surge and between precipitation and river flow was also studied. Case studies of the meteorological situations leading to high surges and/or river flows were also carried out. The present study concerns catchments draining to the south and west coasts of Great Britain. Statistically significant dependence between river flow and daily maximum sea surge may be found at catchments spread along most of this coastline. However, higher dependence is generally found in catchments in hilly areas with a southerly to westerly aspect. Here, precipitation in south-westerly airflow, which is generally the quadrant of prevailing winds, will be enhanced orographically as the first higher ground is encountered. The sloping catchments may respond quickly to the abundant rainfall and the flow peak may arrive in the estuary on the same day as a large sea surge is produced by the winds and low atmospheric pressure associated with the cyclone. There are three regions where flow-surge dependence is strong: the western part of the English south coast, southern Wales and around the Solway Firth. To reduce the influence of tide-surge interaction on the dependence analysis, the dependence between river flow and daily maximum surge occurring at high tide was estimated. The general pattern of areas with higher dependence is similar to that using the daily maximum surge. The dependence between river flow and daily maximum sea surge is often strongest when surge and flow occur on the same day. The west coast from Wales and

  20. Magnified Sediment Export of Small Mountainous Rivers in Taiwan: Chain Reactions from Increased Rainfall Intensity under Global Warming.

    Science.gov (United States)

    Lee, Tsung-Yu; Huang, Jr-Chuan; Lee, Jun-Yi; Jien, Shih-Hao; Zehetner, Franz; Kao, Shuh-Ji

    2015-01-01

    Fluvial sediment export from small mountainous rivers in Oceania has global biogeochemical significance affecting the turnover rate and export of terrestrial carbon, which might be speeding up at the recognized conditions of increased rainfall intensity. In this study, the historical runoff and sediment export from 16 major rivers in Taiwan are investigated and separated into an early stage (1970-1989) and a recent stage (1990-2010) to illustrate the changes of both runoff and sediment export. The mean daily sediment export from Taiwan Island in the recent stage significantly increased by >80% with subtle increase in daily runoff, indicating more sediment being delivered to the ocean per unit of runoff in the recent stage. The medians of the runoff depth and sediment yield extremes (99.0-99.9 percentiles) among the 16 rivers increased by 6.5%-37% and 62%-94%, respectively, reflecting the disproportionately magnified response of sediment export to the increased runoff. Taiwan is facing increasing event rainfall intensity which has resulted in chain reactions on magnified runoff and sediment export responses. As the globe is warming, rainfall extremes, which are proved to be temperature-dependent, very likely intensify runoff and trigger more sediment associated hazards. Such impacts might occur globally because significant increases of high-intensity precipitation have been observed not only in Taiwan but over most land areas of the globe.

  1. Nutrient Dynamics of Estuarine Invertebrates Are Shaped by Feeding Guild Rather than Seasonal River Flow.

    Directory of Open Access Journals (Sweden)

    Kelly Ortega-Cisneros

    Full Text Available This study aimed to determine the variability of carbon and nitrogen elemental content, stoichiometry and diet proportions of invertebrates in two sub-tropical estuaries in South Africa experiencing seasonal changes in rainfall and river inflow. The elemental ratios and stable isotopes of abiotic sources, zooplankton and macrozoobenthos taxa were analyzed over a dry/wet seasonal cycle. Nutrient content (C, N and stoichiometry of suspended particulate matter exhibited significant spatio-temporal variations in both estuaries, which were explained by the variability in river inflow. Sediment particulate matter (%C, %N and C:N was also influenced by the variability in river flow but to a lesser extent. The nutrient content and ratios of the analyzed invertebrates did not significantly vary among seasons with the exception of the copepod Pseudodiaptomus spp. (C:N and the tanaid Apseudes digitalis (%N, C:N. These changes did not track the seasonal variations of the suspended or sediment particulate matter. Our results suggest that invertebrates managed to maintain their stoichiometry independent of the seasonality in river flow. A significant variability in nitrogen content among estuarine invertebrates was recorded, with highest % N recorded from predators and lowest %N from detritivores. Due to the otherwise general lack of seasonal differences in elemental content and stoichiometry, feeding guild was a major factor shaping the nutrient dynamics of the estuarine invertebrates. The nutrient richer suspended particulate matter was the preferred food source over sediment particulate matter for most invertebrate consumers in many, but not all seasons. The most distinct preference for suspended POM as a food source was apparent from the temporarily open/closed system after the estuary had breached, highlighting the importance of river flow as a driver of invertebrate nutrient dynamics under extreme events conditions. Moreover, our data showed that

  2. Nutrient Dynamics of Estuarine Invertebrates Are Shaped by Feeding Guild Rather than Seasonal River Flow.

    Science.gov (United States)

    Ortega-Cisneros, Kelly; Scharler, Ursula M

    2015-01-01

    This study aimed to determine the variability of carbon and nitrogen elemental content, stoichiometry and diet proportions of invertebrates in two sub-tropical estuaries in South Africa experiencing seasonal changes in rainfall and river inflow. The elemental ratios and stable isotopes of abiotic sources, zooplankton and macrozoobenthos taxa were analyzed over a dry/wet seasonal cycle. Nutrient content (C, N) and stoichiometry of suspended particulate matter exhibited significant spatio-temporal variations in both estuaries, which were explained by the variability in river inflow. Sediment particulate matter (%C, %N and C:N) was also influenced by the variability in river flow but to a lesser extent. The nutrient content and ratios of the analyzed invertebrates did not significantly vary among seasons with the exception of the copepod Pseudodiaptomus spp. (C:N) and the tanaid Apseudes digitalis (%N, C:N). These changes did not track the seasonal variations of the suspended or sediment particulate matter. Our results suggest that invertebrates managed to maintain their stoichiometry independent of the seasonality in river flow. A significant variability in nitrogen content among estuarine invertebrates was recorded, with highest % N recorded from predators and lowest %N from detritivores. Due to the otherwise general lack of seasonal differences in elemental content and stoichiometry, feeding guild was a major factor shaping the nutrient dynamics of the estuarine invertebrates. The nutrient richer suspended particulate matter was the preferred food source over sediment particulate matter for most invertebrate consumers in many, but not all seasons. The most distinct preference for suspended POM as a food source was apparent from the temporarily open/closed system after the estuary had breached, highlighting the importance of river flow as a driver of invertebrate nutrient dynamics under extreme events conditions. Moreover, our data showed that estuarine

  3. The remarkable occurrence of large rainfall-induced debris flows at two different locations on July 12, 2008, Southern Sierra Nevada, CA, USA

    Science.gov (United States)

    DeGraff, J.V.; Wagner, D.L.; Gallegos, A.J.; DeRose, M.; Shannon, C.; Ellsworth, T.

    2011-01-01

    On July 12, 2008, two convective cells about 155 km apart produced a brief period of intense rainfall triggering large debris flows in the southern Sierra Nevada. The northernmost cell was centered over Oak Creek Canyon, an east-flowing drainage, and its tributaries near Independence, CA, USA. About 5:00 P.M., debris flows passed down the South Fork and North Fork of Oak Creek to merge into a large single feature whose passage affected the historic Mt. Whitney Fish hatchery and blocked California State Highway 395. At about the same time, the southernmost cell was largely centered over Erskine Creek, a main tributary of the west-flowing Kern River. Debris flows issued from several branches to coalesce into a large debris flow that passed along Erskine Creek, through the town of Lake Isabella, CA, USA and into the Kern River. It was observed reaching Lake Isabella about 6:30 P.M. Both debris flows caused significant disruption and damage to local communities. ?? 2011 Springer-Verlag.

  4. Identification of basin characteristics influencing spatial variation of river flows

    NARCIS (Netherlands)

    Mazvimavi, D.; Burgers, S.L.G.E.; Stein, A.

    2006-01-01

    The selection of basin characteristics that explain spatial variation of river flows is important for hydrological regionalization as this enables estimation of flow statistics of ungauged basins. A direct gradient analysis method, redundancy analysis, is used to identify basin characteristics,

  5. Variation in turbidity with precipitation and flow in a regulated river system – river Göta Älv, SW Sweden

    Directory of Open Access Journals (Sweden)

    G. Göransson

    2013-07-01

    Full Text Available The turbidity variation in time and space is investigated in the downstream stretch of the river Göta Älv in Sweden. The river is heavily regulated and carries the discharge from the largest fresh water lake in Sweden, Lake Vänern, to the outflow point in Göteborg Harbour on the Swedish west coast. The river is an important waterway and serves as a fresh-water supply for 700 000 users. Turbidity is utilised as a water quality indicator to ensure sufficient quality of the intake water to the treatment plant. The overall objective of the study was to investigate the influence of rainfall, surface runoff, and river water flow on the temporal and spatial variability of the turbidity in the regulated river system by employing statistical analysis of an extensive data set. A six year long time series of daily mean values on precipitation, discharge, and turbidity from six stations along the river were examined primarily through linear correlation and regression analysis, combined with nonparametric tests and analysis of variance. The analyses were performed on annual, monthly, and daily bases, establishing temporal patterns and dependences, including; seasonal changes, impacts from extreme events, influences from tributaries, and the spatial variation along the river. The results showed that there is no simple relationship between discharge, precipitation, and turbidity, mainly due to the complexity of the runoff process, the regulation of the river, and the effects of Lake Vänern and its large catchment area. For the river Göta Älv, significant, positive correlations between turbidity, discharge, and precipitation could only be found during periods with high flow combined with heavy rainfall. Local precipitation does not seem to have any significant impact on the discharge in the main river, which is primarily governed by precipitation at catchment scale. The discharge from Lake Vänern determines the base level for the turbidity in the river

  6. A combined triggering-propagation modeling approach for the assessment of rainfall induced debris flow susceptibility

    Science.gov (United States)

    Stancanelli, Laura Maria; Peres, David Johnny; Cancelliere, Antonino; Foti, Enrico

    2017-07-01

    Rainfall-induced shallow slides can evolve into debris flows that move rapidly downstream with devastating consequences. Mapping the susceptibility to debris flow is an important aid for risk mitigation. We propose a novel practical approach to derive debris flow inundation maps useful for susceptibility assessment, that is based on the integrated use of DEM-based spatially-distributed hydrological and slope stability models with debris flow propagation models. More specifically, the TRIGRS infiltration and infinite slope stability model and the FLO-2D model for the simulation of the related debris flow propagation and deposition are combined. An empirical instability-to-debris flow triggering threshold calibrated on the basis of observed events, is applied to link the two models and to accomplish the task of determining the amount of unstable mass that develops as a debris flow. Calibration of the proposed methodology is carried out based on real data of the debris flow event occurred on 1 October 2009, in the Peloritani mountains area (Italy). Model performance, assessed by receiver-operating-characteristics (ROC) indexes, evidences fairly good reproduction of the observed event. Comparison with the performance of the traditional debris flow modeling procedure, in which sediment and water hydrographs are inputed as lumped at selected points on top of the streams, is also performed, in order to assess quantitatively the limitations of such commonly applied approach. Results show that the proposed method, besides of being more process-consistent than the traditional hydrograph-based approach, can potentially provide a more accurate simulation of debris-flow phenomena, in terms of spatial patterns of erosion and deposition as well on the quantification of mobilized volumes and depths, avoiding overestimation of debris flow triggering volume and, thus, of maximum inundation flow depths.

  7. Nowcasting of rainfall and of combined sewage flow in urban drainage systems.

    Science.gov (United States)

    Achleitner, Stefan; Fach, Stefan; Einfalt, Thomas; Rauch, Wolfgang

    2009-01-01

    Nowcasting of rainfall may be used additionally to online rain measurements to optimize the operation of urban drainage systems. Uncertainties quoted for the rain volume are in the range of 5% to 10% mean square error (MSE), where for rain intensities 45% to 75% MSE are noted. For larger forecast periods up to 3 hours, the uncertainties will increase up to some hundred percents. Combined with the growing number of real time control concepts in sewer systems, rainfall forecast is used more and more in urban drainage systems. Therefore it is of interest how the uncertainties influence the final evaluation of a defined objective function. Uncertainty levels associated with the forecast itself are not necessarily transferable to resulting uncertainties in the catchment's flow dynamics. The aim of this paper is to analyse forecasts of rainfall and specific sewer output variables. For this study the combined sewer system of the city of Linz in the northern part of Austria located on the Danube has been selected. The city itself represents a total area of 96 km2 with 39 municipalities connected. It was found that the available weather radar data leads to large deviations in the forecast for precipitation at forecast horizons larger than 90 minutes. The same is true for sewer variables such a CSO overflow for small sub-catchments. Although the results improve for larger spatial scales, acceptable levels at forecast horizons larger than 90 minutes are not reached.

  8. Great expectations: Flow restoration and sediment transport in the Waimea River, Kaua'i

    Science.gov (United States)

    Gomez, Basil

    2018-04-01

    Conventional and novel observations made in the Waimea River basin between 1960 and 1995 permit the total riverine mass flux to be estimated and the influence that flow restoration will have on sediment dynamics in the river's lower reaches to be assessed. Flows between the threshold for sediment transport ( 6.0 m3 s-1) and the most effective flow (80.7 m3 s-1) recur annually and transport 60% of the Waimea River's suspended sediment load. Discharges of this magnitude essentially were unaffected by plantation era agricultural diversions of 2.3 ± 0.7 m3 s-1. The modern-day mass flux from the Waimea River basin is 155 ± 38 t km-2 y-1, and comparison with an independent cosmogenic nuclide-based estimate implies that it has remained at about this level for the past 10 ky. Previous work indicated that: (i) most of the sand the Waimea River transports to the coast is derived from steep, rapidly eroding, sparsely vegetated, bedrock-dominated hillslopes; and (ii) the sediment transport regime of the Waimea River is supply-limited at very high discharges (recurrence interval > 2.5 years). Consequently, major floods tend to remove sand from the estuary. Climate change has caused a statewide decline in heavy rainfall, and a commensurate decline in the magnitude of peak flows in the basin's pristine, undiverted headwaters over the past 97 years. The effect this secular change in climate presently is having on streamflow was foreshadowed in the late 1970s by a naturally occurring, warm Pacific Decadal Oscillation phase reduction in the magnitude of flows with low exceedance probabilities. Additionally, the controlling base level at the river mouth has risen and been displaced seaward. Simple proportionality approximations show that, for a constant sediment supply, aggradation will occur if either the magnitude of flows with a low exceedance probability declines and/or base level rises. Thus, anthropogenic stresses on Waimea River's lower reaches are not derived from the

  9. Amplified melt and flow of the Greenland ice sheet driven by late-summer cyclonic rainfall

    DEFF Research Database (Denmark)

    Doyle, Samuel H.; Hubbard, Alun; van de Wal, Roderik S.W.

    2015-01-01

    and meteorological variables from the western margin of the Greenland ice sheet during a week of warm, wet cyclonic weather in late August and early September 2011. We find that extreme surface runoff from melt and rainfall led to a widespread acceleration in ice flow that extended 140 km into the ice-sheet interior....... We suggest that the late-season timing was critical in promoting rapid runoff across an extensive bare ice surface that overwhelmed a subglacial hydrological system in transition to a less-efficient winter mode. Reanalysis data reveal that similar cyclonic weather conditions prevailed across southern...

  10. Nonlinear analysis of river flow time sequences

    Science.gov (United States)

    Porporato, Amilcare; Ridolfi, Luca

    1997-06-01

    Within the field of chaos theory several methods for the analysis of complex dynamical systems have recently been proposed. In light of these ideas we study the dynamics which control the behavior over time of river flow, investigating the existence of a low-dimension deterministic component. The present article follows the research undertaken in the work of Porporato and Ridolfi [1996a] in which some clues as to the existence of chaos were collected. Particular emphasis is given here to the problem of noise and to nonlinear prediction. With regard to the latter, the benefits obtainable by means of the interpolation of the available time series are reported and the remarkable predictive results attained with this nonlinear method are shown.

  11. Evaluation of artificial neural network techniques for flow forecasting in the River Yangtze, China

    Directory of Open Access Journals (Sweden)

    C. W. Dawson

    2002-01-01

    Full Text Available While engineers have been quantifying rainfall-runoff processes since the mid-19th century, it is only in the last decade that artificial neural network models have been applied to the same task. This paper evaluates two neural networks in this context: the popular multilayer perceptron (MLP, and the radial basis function network (RBF. Using six-hourly rainfall-runoff data for the River Yangtze at Yichang (upstream of the Three Gorges Dam for the period 1991 to 1993, it is shown that both neural network types can simulate river flows beyond the range of the training set. In addition, an evaluation of alternative RBF transfer functions demonstrates that the popular Gaussian function, often used in RBF networks, is not necessarily the ‘best’ function to use for river flow forecasting. Comparisons are also made between these neural networks and conventional statistical techniques; stepwise multiple linear regression, auto regressive moving average models and a zero order forecasting approach. Keywords: Artificial neural network, multilayer perception, radial basis function, flood forecasting

  12. Rainfall-runoff modeling in the Turkey River using numerical and ...

    African Journals Online (AJOL)

    Modeling rainfall-runoff relationships in a watershed have an important role in water resources engineering. Researchers have used numerical models for modeling rainfall-runoff ... Also, by using SPSS software, the regression equations were developed and then the best equation was selected from regression analysis.

  13. Rainfall and flow of the Riozinho do Rôla Basin on Western Amazon

    Directory of Open Access Journals (Sweden)

    Maria Lúcia Hall de Souza

    2013-04-01

    Full Text Available The present study was conducted to analyze the factors influencing the hydrological behavior of the Riozinho do Rôla hydrographic basin, and was based on descriptive analysis tools. Fourteen pluviometers were set up in order to conduct a representative analysis of the rainfall in the basin. Residents of the area voluntarily participated in collection of the rainfall data in the years 2007 and 2008; the residents were trained to collect the data before the pluviometers were installed. ArcGis 9.2 software was used to outline and calculate the area of the Thiessen polygons, and both arithmetic and Thiessen precipitation means were calculated using Excel software. The average precipitation values were 1,428 mm and 1,450 mm, as calculated using the arithmetic mean and Thiessen method, respectively. Using data from the Agência Nacional de Águas (ANA, the rainfall and flow rate in the basin were calculated for the period from 1998 to 2005. The seasonality of precipitation is reflected in the temporary flow rate activity, which reached a peak of 1,276.9 m³/s during the flood period and 4.1 m³/s during periods of the dry season. This behavior is fundamentally related to natural and social aspects of the basin, such as the occurrence of a hydrographic network with characteristics of a headwater associated with a hydrological regime marked by high seasonality; the low permeability of the soils in the basin; and the intensification of deforestation in the region in order to develop livestock as a privileged form of land use.

  14. How East Asian westerly jet's meridional position affects the summer rainfall in Yangtze-Huaihe River Valley?

    Science.gov (United States)

    Wang, Shixin; Zuo, Hongchao; Zhao, Shuman; Zhang, Jiankai; Lu, Sha

    2017-03-01

    Existing studies show that the change in the meridional position of East Asian westerly jet (EAWJ) is associated with rainfall anomalies in Yangtze-Huaihe River Valley (YHRV) in summer. However, the dynamic mechanism has not been resolved yet. The present study reveals underlying mechanisms for this impact for early summer and midsummer, separately. Mechanism1: associated with EAWJ's anomalously southward displacement, the 500-hPa westerly wind over YHRV is strengthened through midtropospheric horizontal circulation anomalies; the westerly anomalies are related to the formation of warm advection anomalies over YHRV, which cause increased rainfall through adiabatic ascent motion and convective activities; the major difference in these processes between early summer and midsummer is the midtropospheric circulation anomaly pattern. Mechanism 2: associated with EAWJ's anomalously southward displacement, the large day-to-day variability of midtropospheric temperature advection in midlatitudes is displaced southward by the jet's trapping transient eddies; this change enhances the day-to-day variability of temperature advection over YHRV, which in turn causes the increased rainfall in most part of YHRV through "lower-bound effect" (rainfall amount can not become negative); there is not much difference in these processes between early summer and midsummer.

  15. Multiyear Rainfall and Temperature Trends in the Volta River Basin and their Potential Impact on Hydropower Generation in Ghana

    Directory of Open Access Journals (Sweden)

    Amos T. Kabo-Bah

    2016-10-01

    Full Text Available The effects of temperature and rainfall changes on hydropower generation in Ghana from 1960–2011 were examined to understand country-wide trends of climate variability. Moreover, the discharge and the water level trends for the Akosombo reservoir from 1965–2014 were examined using the Mann-Kendall test statistic to assess localised changes. The annual temperature trend was positive while rainfall showed both negative and positive trends in different parts of the country. However, these trends were not statistically significant in the study regions in 1960 to 2011. Rainfall was not evenly distributed throughout the years, with the highest rainfall recorded between 1960 and 1970 and the lowest rainfalls between 2000 and 2011. The Mann-Kendall test shows an upward trend for the discharge of the Akosombo reservoir and a downward trend for the water level. However, the discharge irregularities of the reservoir do not necessarily affect the energy generated from the Akosombo plant, but rather the regular low flow of water into the reservoir affected power generation. This is the major concern for the operations of the Akosombo hydropower plant for energy generation in Ghana.

  16. Quantifying downstream impacts of impoundment on flow regime and channel planform, lower Trinity River, Texas

    Science.gov (United States)

    Wellmeyer, Jessica L.; Slattery, Michael C.; Phillips, Jonathan D.

    2005-07-01

    As human population worldwide has grown, so has interest in harnessing and manipulating the flow of water for the benefit of humans. The Trinity River of eastern Texas is one such watershed greatly impacted by engineering and urbanization. Draining the Dallas-Fort Worth metroplex, just under 30 reservoirs are in operation in the basin, regulating flow while containing public supplies, supporting recreation, and providing flood control. Lake Livingston is the lowest, as well as largest, reservoir in the basin, a mere 95 km above the Trinity's outlet near Galveston Bay. This study seeks to describe and quantify channel activity and flow regime, identifying effects of the 1968 closure of Livingston dam. Using historic daily and peak discharge data from USGS gauging stations, flow duration curves are constructed, identifying pre- and post-dam flow conditions. A digital historic photo archive was also constructed using six sets of aerial photographs spanning from 1938 to 1995, and three measures of channel activity applied using a GIS. Results show no changes in high flow conditions following impoundment, while low flows are elevated. However, the entire post-dam period is characterized by significantly higher rainfall, which may be obscuring the full impact of flow regulation. Channel activity rates do not indicate a more stabilized planform following dam closure; rather they suggest that the Trinity River is adjusting itself to the stress of Livingston dam in a slow, gradual process that may not be apparent in a modern time scale.

  17. [Responses of sap flow to natural rainfall and continuous drought of tree species growing on bedrock outcrops].

    Science.gov (United States)

    Zhang, Hui Ling; Ding, Ya Li; Chen, Hong Song; Wang, Ke Lin; Nie, Yun Peng

    2018-04-01

    This study focused on bedrock outcrops, a very common habitat in karst region of southwest China. To reveal the responses of plant transpiration to natural rainfall and continuous drought, two tree species typical to this habitat, Radermachera sinica and Triadica rotundifolia, were selected as test materials. A rainout shelter was used to simulate continuous drought. The sap flow dynamics were monitored using the method of Granier's thermal dissipation probe (TDP). Our results showed that sap flow density increased to different degrees after rain in different stages of the growing season. Sap flow density of the deciduous species T. rotundifolia was always higher than that of the semi-deciduous species R. sinica. After two months without rainfall input, both species exhibited no obvious decrease in sap flow density, indicating that rainfall was not the dominant source for their water uptake, at least in the short-term. Based on the regression relationships between sap flow density and meteorological factors before and after rainfall, as well as at different stages of continuous drought, we found that the dynamics of meteorological factors contributed little to plant transpiration. The basic transpiration characteristics of both species were not changed in the circumstance of natural rainfall and short-term continuous drought, which would be closely related to the special water storage environments of bedrock outcrops and the reliance on deep water sources by tree species.

  18. GIS-based two-dimensional numerical simulation of rainfall-induced debris flow

    Directory of Open Access Journals (Sweden)

    C. Wang

    2008-02-01

    Full Text Available This paper aims to present a useful numerical method to simulate the propagation and deposition of debris flow across the three dimensional complex terrain. A depth-averaged two-dimensional numerical model is developed, in which the debris and water mixture is assumed to be continuous, incompressible, unsteady flow. The model is based on the continuity equations and Navier-Stokes equations. Raster grid networks of digital elevation model in GIS provide a uniform grid system to describe complex topography. As the raster grid can be used as the finite difference mesh, the continuity and momentum equations are solved numerically using the finite difference method. The numerical model is applied to simulate the rainfall-induced debris flow occurred in 20 July 2003, in Minamata City of southern Kyushu, Japan. The simulation reproduces the propagation and deposition and the results are in good agreement with the field investigation. The synthesis of numerical method and GIS makes possible the solution of debris flow over a realistic terrain, and can be used to estimate the flow range, and to define potentially hazardous areas for homes and road section.

  19. Deterministic chaotic dynamics of Raba River flow (Polish Carpathian Mountains)

    Science.gov (United States)

    Kędra, Mariola

    2014-02-01

    Is the underlying dynamics of river flow random or deterministic? If it is deterministic, is it deterministic chaotic? This issue is still controversial. The application of several independent methods, techniques and tools for studying daily river flow data gives consistent, reliable and clear-cut results to the question. The outcomes point out that the investigated discharge dynamics is not random but deterministic. Moreover, the results completely confirm the nonlinear deterministic chaotic nature of the studied process. The research was conducted on daily discharge from two selected gauging stations of the mountain river in southern Poland, the Raba River.

  20. Community Based Warning and Evacuation System against Debris Flow in the Upper Jeneberang River, Gowa, South Sulawesi

    Directory of Open Access Journals (Sweden)

    Sutikno Hardjosuwarno

    2008-07-01

    Full Text Available Gigantic collapse of the Caldera wall of Mt. Bawakaraeng (2,830 m in March 2004 had supplied the sediment volume of 230 million to the most upper stream of Jeneberang River, which flowed down to the lower reach in the form of debris flow which is triggered by rainfall. The purpose of the research is to provide a system which is able to forecast the occurrence of debris flow, to identify the weak points along the river course, to identify the hazard areas and how to inform effectively and efficiently the warning messages to the inhabitants in the dangerous area by using the existing modern equipment combined with the traditional one. The standard rainfall which is used to judge the occurrence of debris flow was established by Yano method. It is based on the historical data of rainfall that trigger and not trigger to the occurrence of debris flow which is widely used in Japan so far. The hazard area was estimated by Two-Dimensional Simulation Model for debris flow, the debris flow arrival time at each point in the river were estimated by dividing their distance from reference point by debris flow velocity, where the check dam no. 7-1 in Manimbahoi was designated as reference point. The existing evacuation routes were checked by field survey, the strength and coverage of sound for kentongan and manual siren were examined using sound pressure level at the location of the existing monitoring post and the effectiveness of warning and evacuation were evaluated by comparing the warning and evacuation time against the debris flow arrival time. It was resulted that debris flow occurrence was triggered by short duration of high rainfall intensity, long duration of low rainfall intensity and the outbreak of natural dam which is formed by land slide or bank collapses. The hazard area of upper Jeneberang River are mostly located on the river terraces where the local inhabitants earn their living through cultivating the river terraces as paddy fields, dry

  1. Linking river nutrient concentrations to land use and rainfall in a paddy agriculture-urban area gradient watershed in southeast China.

    Science.gov (United States)

    Xia, Yongqiu; Ti, Chaopu; She, Dongli; Yan, Xiaoyuan

    2016-10-01

    The effects of land use and land-use changes on river nutrient concentrations are not well understood, especially in the watersheds of developing countries that have a mixed land use of rice paddy fields and developing urban surfaces. Here, we present a three-year study of a paddy agricultural-urban area gradient watershed in southeast China. The annual anthropogenic nitrogen (N) input from the agricultural region to the urban region was high, yet the results showed that the monthly nutrient concentrations in the river were low in the rainy seasons. The nutrient concentrations decreased continuously as the river water passed through the traditional agriculture region (TAR; paddy rice and wheat rotation) and increased substantially in the city region (CR). The traditional agricultural reference region exported most of the nutrient loads at high flows (>1mmd(-1)), the intensified agricultural region (IAR, aquaculture and poultry farming) exported most of the nutrient loads at moderate flows (between 0.5 and 1mmd(-1)), and the CR reference area exported most of the nutrient loads under low to moderate flows. We developed a statistical model to link variations in the nutrient concentrations to the proportion of land-use types and rainfall. The statistical results showed that impervious surfaces, which we interpret as a proxy for urban activities including sewage disposal, were the most important drivers of nutrient concentrations, whereas water surfaces accounted for a substantial proportion of the nutrient sinks. Therefore, to efficiently reduce water pollution, sewage from urban areas must be addressed as a priority, although wetland restoration could also achieve substantial pollutant removal. Copyright © 2016. Published by Elsevier B.V.

  2. Developing New Modelling Tools for Environmental Flow Assessment in Regulated Salmon Rivers

    Science.gov (United States)

    Geris, Josie; Soulsby, Chris; Tetzlaff, Doerthe

    2013-04-01

    of the natural flow variability and the hydrological impacts of the regulation is unavailable, partly because pre-regulation data of existing hydropower schemes are lacking. Here we develop a novel modelling approach for characterising natural flow regimes and defining hydrological flow indices. This allows us to quantitatively assess the impacts of hydropower to better inform environmental flow requirements for the Atlantic salmon river ecosystem. Results are presented for the River Lyon (390 km2), a regulated headwater catchment of the River Tay. The HBV hydrological rainfall-runoff model is used to simulate flows, based on calibrated parameters from regulated flow data, with the current hydropower scheme active. For this, the HBV model is adapted to be able to incorporate water transfers and regulated flows. The natural hydrological indices are derived from the simulated pre-regulation data, and compared with those of the regulated data to investigate the impact of the regulation on these at different critical times for Atlantic salmon. The sensitivity of the system to change is also investigated to explore the extent to which flow variables can be modified without major degradation to the river's ecosystem, while still maintaining viable hydropower generation. The modelling approach presented will provide the basis for assessing impacts on hydrological flow indices and informing environmental flows in regions with similar heavily regulated mountain river ecosystems.

  3. Effects of rainfall on water quality in six sequentially disposed fishponds with continuous water flow

    Directory of Open Access Journals (Sweden)

    LH. Sipaúba-Tavares

    Full Text Available An investigation was carried out during the rainy period in six semi-intensive production fish ponds in which water flowed from one pond to another without undergoing any treatment. Eight sampling sites were assigned at pond outlets during the rainy period (December-February. Lowest and highest physical and chemical parameters of water occurred in pond P1 (a site near the springs and in pond P4 (a critical site that received allochthonous material from the other ponds and also from frog culture ponds, respectively. Pond sequential layout caused concentration of nutrients, chlorophyll-a and conductivity. Seasonal rains increased the water flow in the ponds and, consequently, silted more particles and other dissolved material from one fish pond to another. Silting increased limnological variables from P3 to P6. Although results suggest that during the period under analysis, rainfall affected positively the ponds' water quality and since the analyzed systems have been aligned in a sequential layout with constant water flow from fish ponds and parallel tanks without any previous treatment, care has to be taken so that an increase in rain-induced water flow does not have a contrary effect in the fish ponds investigated.

  4. Integration and calibration of a conceptual rainfall-runoff model in the framework of a decision support system for river basin management

    Directory of Open Access Journals (Sweden)

    J. Götzinger

    2005-01-01

    Full Text Available Water balance models provide significant input to integrated models that are used to simulate river basin processes. However, one of the primary problems involves the coupling and simultaneous calibration of rainfall-runoff and groundwater models. This problem manifests itself through circular arguments - the hydrologic model is modified to calculate highly discretized groundwater recharge rates as input to the groundwater model which provides modeled base flow for the flood-routing module of the rainfall-runoff model. A possibility to overcome this problem using a modified version of the HBV Model is presented in this paper. Regionalisation and optimization methods lead to objective and efficient calibration despite large numbers of parameters. The representation of model parameters by transfer functions of catchment characteristics enables consistent parameter estimation. By establishing such relationships, models are calibrated for the parameters of the transfer functions instead of the model parameters themselves. Simulated annealing, using weighted Nash-Sutcliffe-coefficients of variable temporal aggregation, assists in efficient parameterisations. The simulations are compared to observed discharge and groundwater recharge modeled by the State Institute for Environmental Protection Baden-Württemberg using the model TRAIN-GWN.

  5. Instrumental record of debris flow initiation during natural rainfall: Implications for modeling slope stability

    Science.gov (United States)

    Montgomery, D.R.; Schmidt, K.M.; Dietrich, W.E.; McKean, J.

    2009-01-01

    The middle of a hillslope hollow in the Oregon Coast Range failed and mobilized as a debris flow during heavy rainfall in November 1996. Automated pressure transducers recorded high spatial variability of pore water pressure within the area that mobilized as a debris flow, which initiated where local upward flow from bedrock developed into overlying colluvium. Postfailure observations of the bedrock surface exposed in the debris flow scar reveal a strong spatial correspondence between elevated piezometric response and water discharging from bedrock fractures. Measurements of apparent root cohesion on the basal (Cb) and lateral (Cl) scarp demonstrate substantial local variability, with areally weighted values of Cb = 0.1 and Cl = 4.6 kPa. Using measured soil properties and basal root strength, the widely used infinite slope model, employed assuming slope parallel groundwater flow, provides a poor prediction of hydrologie conditions at failure. In contrast, a model including lateral root strength (but neglecting lateral frictional strength) gave a predicted critical value of relative soil saturation that fell within the range defined by the arithmetic and geometric mean values at the time of failure. The 3-D slope stability model CLARA-W, used with locally observed pore water pressure, predicted small areas with lower factors of safety within the overall slide mass at sites consistent with field observations of where the failure initiated. This highly variable and localized nature of small areas of high pore pressure that can trigger slope failure means, however, that substantial uncertainty appears inevitable for estimating hydrologie conditions within incipient debris flows under natural conditions. Copyright 2009 by the American Geophysical Union.

  6. The coherent variability of African river flows : composite climate ...

    African Journals Online (AJOL)

    The composite structure of the ocean and atmosphere around Africa is studied in the context of river flow variability. Annual streamflows are analysed for the Blue and White Nile, Congo, Niger, Senegal, Zambezi, and Orange Rivers, and inflow to Lake Malawi. Spectral energy is concentrated in 6.6- and 2.4-year bands.

  7. Riparian trees as common denominators across the river flow ...

    African Journals Online (AJOL)

    Riparian tree species, growing under different conditions of water availability, can ... leaf area and increasing wood density correlating with deeper groundwater levels. ... and Sanddrifskloof Rivers (South Africa) under reduced flow conditions.

  8. Rainfall Variability, Wetland Persistence, and Water–Carbon Cycle Coupling in the Upper Zambezi River Basin in Southern Africa

    Directory of Open Access Journals (Sweden)

    Lauren E. L. Lowman

    2018-05-01

    Full Text Available The Upper Zambezi River Basin (UZRB delineates a complex region of topographic, soil and rainfall gradients between the Congo rainforest and the Kalahari Desert. Satellite imagery shows permanent wetlands in low-lying convergence zones where surface–groundwater interactions are vigorous. A dynamic wetland classification based on MODIS Nadir BRDF-Adjusted Reflectance is developed to capture the inter-annual and seasonal changes in areal extent due to groundwater redistribution and rainfall variability. Simulations of the coupled water–carbon cycles of seasonal wetlands show nearly double rates of carbon uptake as compared to dry areas, at increasingly lower water-use efficiencies as the dry season progresses. Thus, wetland extent and persistence into the dry season is key to the UZRB’s carbon sink and water budget. Whereas groundwater recharge governs the expansion of wetlands in the rainy season under large-scale forcing, wetland persistence in April–June (wet–dry transition months is tied to daily morning fog and clouds, and by afternoon land–atmosphere interactions (isolated convection. Rainfall suppression in July–September results from colder temperatures, weaker regional circulations, and reduced instability in the lower troposphere, shutting off moisture recycling in the dry season despite high evapotranspiration rates. The co-organization of precipitation and wetlands reflects land–atmosphere interactions that determine wetland seasonal persistence, and the coupled water and carbon cycles.

  9. A century of changing flows: Forest management changed flow magnitudes and warming advanced the timing of flow in a southwestern US river.

    Directory of Open Access Journals (Sweden)

    Marcos D Robles

    Full Text Available The continued provision of water from rivers in the southwestern United States to downstream cities, natural communities and species is at risk due to higher temperatures and drought conditions in recent decades. Snowpack and snowfall levels have declined, snowmelt and peak spring flows are arriving earlier, and summer flows have declined. Concurrent to climate change and variation, a century of fire suppression has resulted in dramatic changes to forest conditions, and yet, few studies have focused on determining the degree to which changing forests have altered flows. In this study, we evaluated changes in flow, climate, and forest conditions in the Salt River in central Arizona from 1914-2012 to compare and evaluate the effects of changing forest conditions and temperatures on flows. After using linear regression models to remove the influence of precipitation and temperature, we estimated that annual flows declined by 8-29% from 1914-1963, coincident with a 2-fold increase in basal area, a 2-3-fold increase in canopy cover, and at least a 10-fold increase in forest density within ponderosa pine forests. Streamflow volumes declined by 37-56% in summer and fall months during this period. Declines in climate-adjusted flows reversed at mid-century when spring and annual flows increased by 10-31% from 1964-2012, perhaps due to more winter rainfall. Additionally, peak spring flows occurred about 12 days earlier in this period than in the previous period, coincident with winter and spring temperatures that increased by 1-2°C. While uncertainties remain, this study adds to the knowledge gained in other regions that forest change has had effects on flow that were on par with climate variability and, in the case of mid-century declines, well before the influence of anthropogenic warming. Current large-scale forest restoration projects hold some promise of recovering seasonal flows.

  10. Hazard Assessment from Storm Tides and Rainfall on a Tidal River Estuary

    Science.gov (United States)

    Orton, P.; Conticello, F.; Cioffi, F.; Hall, T.; Georgas, N.; Lall, U.; Blumberg, A.

    2015-01-01

    Here, we report on methods and results for a model-based flood hazard assessment we have conducted for the Hudson River from New York City to Troy/Albany at the head of tide. Our recent work showed that neglecting freshwater flows leads to underestimation of peak water levels at up-river sites and neglecting stratification (typical with two-dimensional modeling) leads to underestimation all along the Hudson. As a result, we use a three-dimensional hydrodynamic model and merge streamflows and storm tides from tropical and extratropical cyclones (TCs, ETCs), as well as wet extratropical cyclone (WETC) floods (e.g. freshets, rain-on-snow events). We validate the modeled flood levels and quantify error with comparisons to 76 historical events. A Bayesian statistical method is developed for tropical cyclone streamflows using historical data and consisting in the evaluation of (1) the peak discharge and its pdf as a function of TC characteristics, and (2) the temporal trend of the hydrograph as a function of temporal evolution of the cyclone track, its intensity and the response characteristics of the specific basin. A k-nearest-neighbors method is employed to determine the hydrograph shape. Out of sample validation tests demonstrate the effectiveness of the method. Thus, the combined effects of storm surge and runoff produced by tropical cyclones hitting the New York area can be included in flood hazard assessment. Results for the upper Hudson (Albany) suggest a dominance of WETCs, for the lower Hudson (at New York Harbor) a case where ETCs are dominant for shorter return periods and TCs are more important for longer return periods (over 150 years), and for the middle-Hudson (Poughkeepsie) a mix of all three flood events types is important. However, a possible low-bias for TC flood levels is inferred from a lower importance in the assessment results, versus historical event top-20 lists, and this will be further evaluated as these preliminary methods and results are

  11. River flow controls on tides an tide-mean water level profiles in a tidel freshwater river

    NARCIS (Netherlands)

    Sassi, M.G.; Hoitink, A.J.F.

    2013-01-01

    [1] Tidal rivers feature oscillatory and steady gradients in the water surface, controlled by interactions between river flow and tides. The river discharge attenuates the tidal motion, and tidal motion increases tidal-mean friction in the river, which may act as a barrier to the river discharge.

  12. River Flow Prediction Using the Nearest Neighbor Probabilistic Ensemble Method

    Directory of Open Access Journals (Sweden)

    H. Sanikhani

    2016-02-01

    Full Text Available Introduction: In the recent years, researchers interested on probabilistic forecasting of hydrologic variables such river flow.A probabilistic approach aims at quantifying the prediction reliability through a probability distribution function or a prediction interval for the unknown future value. The evaluation of the uncertainty associated to the forecast is seen as a fundamental information, not only to correctly assess the prediction, but also to compare forecasts from different methods and to evaluate actions and decisions conditionally on the expected values. Several probabilistic approaches have been proposed in the literature, including (1 methods that use resampling techniques to assess parameter and model uncertainty, such as the Metropolis algorithm or the Generalized Likelihood Uncertainty Estimation (GLUE methodology for an application to runoff prediction, (2 methods based on processing the forecast errors of past data to produce the probability distributions of future values and (3 methods that evaluate how the uncertainty propagates from the rainfall forecast to the river discharge prediction, as the Bayesian forecasting system. Materials and Methods: In this study, two different probabilistic methods are used for river flow prediction.Then the uncertainty related to the forecast is quantified. One approach is based on linear predictors and in the other, nearest neighbor was used. The nonlinear probabilistic ensemble can be used for nonlinear time series analysis using locally linear predictors, while NNPE utilize a method adapted for one step ahead nearest neighbor methods. In this regard, daily river discharge (twelve years of Dizaj and Mashin Stations on Baranduz-Chay basin in west Azerbijan and Zard-River basin in Khouzestan provinces were used, respectively. The first six years of data was applied for fitting the model. The next three years was used to calibration and the remained three yeas utilized for testing the models

  13. Rainfall-runoff modelling of the Okavango River catchment to assess impacts of land use change on runoff and downstream ecosystems

    Science.gov (United States)

    Milzow, Christian; Bauer-Gottwein, Peter

    2010-05-01

    The competition between human water use and ecosystem water use is one of the major challenges for water resources management at the global scale. We analyse the situation for the Okavango River basin of southern Africa. The Okavango River is representative for many large rivers throughout the developing world in that it is ungauged and poorly studied. The Okavango basin - spanning over Angola, Namibia and Botswana - represents a multi-objective problem in an international setting. Economic benefits of agricultural development and conservation of ecosystem services call for opposed actions. A semi-distributed rainfall-runoff model of the Okavango catchment is set up using the Soil and Water Assessment Tool (SWAT). The model is sufficiently physically based to simulate the impact on runoff of extent of agricultural use, crop types and management practices. Precipitation and temperature inputs are taken from datasets covering large parts of the globe. The methodology can thus easily be applied for other ungauged catchments. For temperature we use the ERA-Interim reanalysis product of the European Centre for Medium-Range Weather Forecasts and for precipitation the Famine Early Warning Systems Network data (FEWS-Net). Tropical Rainfall Measurement Mission (TRMM) data resulted in poor model performance compared to the FEWS-Net data. Presently, the upstream catchment in Angola is largely pristine and agriculture is basically restricted to dry land subsistence farming. But economic growth in Angola is likely to result in agricultural development and consequent impacts on catchment runoff. Land use scenarios that are simulated include large scale irrigated agriculture with water extractions from the river and the shallow aquifer. Climate change impacts are also studied and compared to land use change impacts. The downstream part of the basin consists of the large Okavango Wetlands, which are a biodiversity hotspot of global importance and, through tourism, an important

  14. RRAWFLOW: Rainfall-Response Aquifer and Watershed Flow Model (v1.15)

    Science.gov (United States)

    Long, Andrew J.

    2015-01-01

    The Rainfall-Response Aquifer and Watershed Flow Model (RRAWFLOW) is a lumped-parameter model that simulates streamflow, spring flow, groundwater level, or solute transport for a measurement point in response to a system input of precipitation, recharge, or solute injection. I introduce the first version of RRAWFLOW available for download and public use and describe additional options. The open-source code is written in the R language and is available at http://sd.water.usgs.gov/projects/RRAWFLOW/RRAWFLOW.html along with an example model of streamflow. RRAWFLOW includes a time-series process to estimate recharge from precipitation and simulates the response to recharge by convolution, i.e., the unit-hydrograph approach. Gamma functions are used for estimation of parametric impulse-response functions (IRFs); a combination of two gamma functions results in a double-peaked IRF. A spline fit to a set of control points is introduced as a new method for estimation of nonparametric IRFs. Several options are included to simulate time-variant systems. For many applications, lumped models simulate the system response with equal accuracy to that of distributed models, but moreover, the ease of model construction and calibration of lumped models makes them a good choice for many applications (e.g., estimating missing periods in a hydrologic record). RRAWFLOW provides professional hydrologists and students with an accessible and versatile tool for lumped-parameter modeling.

  15. Climate influences on upper Limpopo River flow

    African Journals Online (AJOL)

    2016-01-01

    Jan 1, 2016 ... Keywords: Limpopo Valley, hydro-meteorology, surface water deficit. * To whom all ... millenia and there is a history of drought impacts on vegetation. (Ekblom et ... water budget of the upper Limpopo River valley using direct.

  16. MSET modeling of Crystal River-3 venturi flow meters

    International Nuclear Information System (INIS)

    Bockhorst, F. K.; Gross, K. C.; Herzog, J. P.; Wegerich, S. W.

    1998-01-01

    The analysis of archived Crystal River-3 feedwater flow data reveals a slow and steady degradation of the flow meter measurements during the 1992/1993 operating cycle. MSET can reliably estimate the true flow rate and quantify the degree of departure between the indicated signal and the true flow rate with high accuracy. The MSET computed flow rate could, in principle, be used to provide an improved estimate of the reactor power and hence avoid the revenue loss associated with derating the reactor based on a faulty feedwater flow rate indication

  17. Flow intermittence and ecosystem services in rivers of the Anthropocene

    Science.gov (United States)

    Intermittent rivers and ephemeral streams (IRES) are watercourses that cease flow at some point in time and space. Arguably Earth's most widespread type of flowing water, IRES are expanding where Anthropocenic climates grow drier and human demands for water escalate. However, IRE...

  18. River Bank Erosion and the Influence of Environmental Flow Management

    Science.gov (United States)

    Vietz, Geoff J.; Lintern, Anna; Webb, J. Angus; Straccione, David

    2018-03-01

    Environmental flows aim to influence river hydrology to provide appropriate physical conditions for ecological functioning within the restrictions of flow regulation. The hydrologic characteristics of flow events, however, may also lead to unintended morphologic effects in rivers, such as increases in riverbank erosion beyond natural rates. This may negatively impact habitat for biota, riparian infrastructure, and land use. Strategic environmental flow delivery linked to monitoring and adaptive management can help mitigate risks. We monitor riverbank condition (erosion and deposition) relative to environmental flows on the Goulburn River, Victoria, Australia. We describe the process of adaptive management aimed at reducing potential impacts of flow management on bank condition. Field measurements (erosion pins) quantify the hydrogeomorphic response of banks to the delivery of planned and natural flow events. Managed flows provide opportunities for monitoring riverbank response to flows, which in turn informs planning. The results demonstrate that environmental flows have little influence on bank erosion and visual perceptions in the absence of monitoring are an unreliable guide. This monitoring project represents a mutually beneficial, science-practice partnership demonstrating that a traditional `know then do' approach can be foreshortened by close collaboration between researchers and managers. To do so requires transparent, often informal lines of communication. The benefits for researchers-a more strategic and targeted approach to monitoring activities; and benefits for the practitioners-reduced time between actions and understanding response; mean that a learn by doing approach is likely to have better outcomes for researchers, stakeholders, the public, and the environment.

  19. River Bank Erosion and the Influence of Environmental Flow Management.

    Science.gov (United States)

    Vietz, Geoff J; Lintern, Anna; Webb, J Angus; Straccione, David

    2018-03-01

    Environmental flows aim to influence river hydrology to provide appropriate physical conditions for ecological functioning within the restrictions of flow regulation. The hydrologic characteristics of flow events, however, may also lead to unintended morphologic effects in rivers, such as increases in riverbank erosion beyond natural rates. This may negatively impact habitat for biota, riparian infrastructure, and land use. Strategic environmental flow delivery linked to monitoring and adaptive management can help mitigate risks. We monitor riverbank condition (erosion and deposition) relative to environmental flows on the Goulburn River, Victoria, Australia. We describe the process of adaptive management aimed at reducing potential impacts of flow management on bank condition. Field measurements (erosion pins) quantify the hydrogeomorphic response of banks to the delivery of planned and natural flow events. Managed flows provide opportunities for monitoring riverbank response to flows, which in turn informs planning. The results demonstrate that environmental flows have little influence on bank erosion and visual perceptions in the absence of monitoring are an unreliable guide. This monitoring project represents a mutually beneficial, science-practice partnership demonstrating that a traditional 'know then do' approach can be foreshortened by close collaboration between researchers and managers. To do so requires transparent, often informal lines of communication. The benefits for researchers-a more strategic and targeted approach to monitoring activities; and benefits for the practitioners-reduced time between actions and understanding response; mean that a learn by doing approach is likely to have better outcomes for researchers, stakeholders, the public, and the environment.

  20. Meeting instream flow needs of lower Colorado River in Texas

    International Nuclear Information System (INIS)

    Martin, Q.W.

    1993-01-01

    The Lower Colorado River Authority (LCRA), an agency of the State of Texas, manages the surface waters of the lower Colorado River in Texas. The major water supply source in the lower basin is the Highland Lakes chain of reservoirs in Central Texas. The use of water from these lakes for environmental protection and enhancement has received increasing attention in recent years. The LCRA recently completed major revisions to its comprehensive Water Management Plan (WMP) for the Highland Lakes. These revisions included changes to incorporate the results of a three year study of instream flow needs in the lower Colorado River. The instream flow needs were determined to consist of two flow regimes: critical and target. The critical flows are considered to be the daily minimum flows needed to maintain minimum viable aquatic conditions for important fish species. The target flow needs are those daily flows which maximize the available habitat for a variety of fish. After evaluating numerous policy options, LCRA revised to WMP to allow the release of water from the Highland Lakes to maintain the daily river flows at no less than the critical flows in all years. Further, in those years when drought-induced irrigation water supply curtailments do not occur, LCRA will release water from the lakes, to the extent of daily inflows, to maintain daily river flows at no less than the target levels. To fully honor this pledge, LCRA committed an average of 28,700 acre-feet annually, during any ten consecutive years, from the dependable supply of the Highland Lakes

  1. Hydrological model calibration for derived flood frequency analysis using stochastic rainfall and probability distributions of peak flows

    Science.gov (United States)

    Haberlandt, U.; Radtke, I.

    2014-01-01

    Derived flood frequency analysis allows the estimation of design floods with hydrological modeling for poorly observed basins considering change and taking into account flood protection measures. There are several possible choices regarding precipitation input, discharge output and consequently the calibration of the model. The objective of this study is to compare different calibration strategies for a hydrological model considering various types of rainfall input and runoff output data sets and to propose the most suitable approach. Event based and continuous, observed hourly rainfall data as well as disaggregated daily rainfall and stochastically generated hourly rainfall data are used as input for the model. As output, short hourly and longer daily continuous flow time series as well as probability distributions of annual maximum peak flow series are employed. The performance of the strategies is evaluated using the obtained different model parameter sets for continuous simulation of discharge in an independent validation period and by comparing the model derived flood frequency distributions with the observed one. The investigations are carried out for three mesoscale catchments in northern Germany with the hydrological model HEC-HMS (Hydrologic Engineering Center's Hydrologic Modeling System). The results show that (I) the same type of precipitation input data should be used for calibration and application of the hydrological model, (II) a model calibrated using a small sample of extreme values works quite well for the simulation of continuous time series with moderate length but not vice versa, and (III) the best performance with small uncertainty is obtained when stochastic precipitation data and the observed probability distribution of peak flows are used for model calibration. This outcome suggests to calibrate a hydrological model directly on probability distributions of observed peak flows using stochastic rainfall as input if its purpose is the

  2. How is overland flow produced under intermittent rain? An analysis using plot-scale rainfall simulation on dryland soils

    Science.gov (United States)

    Dunkerley, David

    2018-01-01

    The characteristic intermittency of rainfall includes temporary cessations (hiatuses), as well as periods of very low intensity within more intense events. To understand how these characteristics of rainfall affect overland flow production, rainfall simulations involving repeated cycles of on-off intermittency were carried out on dryland soils in arid western New South Wales, Australia. Periods of rain (10 mm/h) and no-rain were applied in alternation with cycle times from 3 min to 25 min, in experiments lasting 1-1.5 h. Results showed that intermittency could delay the onset of runoff by more than 30 min, reduce the runoff ratio, reduce the peak runoff rate, and reduce the apparent event infiltration rate by 30-45%. When hiatuses in rainfall were longer than 15-20 min, runoff that had resulted from prior rain ceased completely before the recommencement of rain. Results demonstrate that if rainfall intermittency is not accounted for, estimates of infiltrability based on runoff plot data can be systematically in error. Despite the use of intermittent rain, the episodic occurrence of runoff could be predicted successfully by fitting multiple affine Horton infiltration equations, whose changing f0 and Kf coefficients, but uniform values of fc, reflected the redistribution of soil moisture and the change in the infiltrability f during hiatuses in rainfall. The value of fc varied little among the fitted equations, so constituting an affine set of relationships. This new approach provides an alternative to the use of steady-state methods that are common in rainfall simulation experiments and which typically yield only an estimate of fc. The new field results confirm that intermittency affects infiltration and runoff depths and timing at plot scale and on intra-event timescales. Additional work on other soil types, and at other spatial and temporal scales, is needed to test the generality of these findings.

  3. Climate change impact on river flows in Chitral watershed

    International Nuclear Information System (INIS)

    Shakir, A.S.; Rehman, H.U.; Ehsan, S.

    2010-01-01

    The impact of climate change has always been very important for water resources in the world. In countries like Pakistan where different weather conditions exist, the effects of climate change can be more crucial. Generally, the climate changes are considered in terms of global warming i.e. increase in the average temperature of earth's near surface air. The global warming can have a strong impact on river flows in Pakistan. This may be due to the melting of snow and glaciers at a higher rate and changes in precipitation patterns. Glaciers in Pakistan cover about 13,680 km/sup 2/, which is 13% of the mountainous regions of the Upper Indus Basin. Glacier and Snow melt water from these glaciers contributes significantly to the river flows in Pakistan. Due to climate change, the changes in temperature and the amount of precipitation could have diversified effects on river flows of arid and semi-arid regions of Pakistan. This paper reviews the existing research studies on climate change impact on water resources of Pakistan. The past trend of river flows in Pakistan has been discussed with respect to the available data. Further, different projections about future climate changes in terms of glacier melting and changes in temperature and precipitation have also been taken into consideration in order to qualitatively assess the future trend of river flows in Pakistan. As a case study, the flows were generated for the Chitral watershed using UBC Watershed Model. Model was calibrated for the year 2002, which is an average flow year. Model results show good agreement between simulated and observed flows. UBC watershed model was applied to a climate change scenario of 1 deg. C increase in temperature and 15% decrease in glaciated area. Results of the study reveal that the flows were decreased by about 4.2 %. (author)

  4. Simulation and Modelling of Climate Change Effects on River Awara Flow Discharge using WEAP Model

    Directory of Open Access Journals (Sweden)

    Oyati E.N.

    2017-11-01

    Full Text Available Modelling of stream flow and discharge of river Awara under changed climate conditions using CLIMGEN for stochastic weather generation and WEAP model was used to simulate reserviour storage volume, water demand and river discharges at high spatial resolution (0.5°×0.5°, total 66,420 grid cells. Results of CLM-Based flow measurement shows a linear regression with R 2 = 0.99 for IFPRI-MNP- IGSM_WRS calibration. Sensitivity simulation of ambient long-term shows an increase in temperature with 0.5 o c thus the results of the studies generally show that annual runoff and river discharges could largely decrease. The projection of water demand 150 million m 3 by 2020 against the reservoir storage volume 60 million m 3 and decrease in rainfall depth by -5.7 mm. The output of the combined models used in this study is veritable to create robust water management system under different climate change scenarios.

  5. Environmental flows and water quality objectives for the River Murray.

    Science.gov (United States)

    Gippel, C; Jacobs, T; McLeod, T

    2002-01-01

    Over the past decade, there intense consideration of managing flows in the River Murray to provide environmental benefits. In 1990 the Murray-Darling Basin Ministerial Council adopted a water quality policy: To maintain and, where necessary, improve existing water quality in the rivers of the Murray-Darling Basin for all beneficial uses - agricultural, environmental, urban, industrial and recreational, and in 1994 a flow policy: To maintain and where necessary improve existing flow regimes in the waterways of the Murray-Darling Basin to protect and enhance the riverine environment. The Audit of Water Use followed in 1995, culminating in the decision of the Ministerial Council to implement an interim cap on new diversions for consumptive use (the "Cap") in a bid to halt declining river health. In March 1999 the Environmental Flows and Water Quality Objectives for the River Murray Project (the Project) was set up, primarily to establish be developed that aims to achieve a sustainable river environment and water quality, in accordance with community needs, and including an adaptive approach to management and operation of the River. It will lead to objectives for water quality and environmental flows that are feasible, appropriate, have the support of the scientific, management and stakeholder communities, and carry acceptable levels of risk. This paper describes four key aspects of the process being undertaken to determine the objectives, and design the flow options that will meet those objectives: establishment of an appropriate technical, advisory and administrative framework; establishing clear evidence for regulation impacts; undergoing assessment of environmental flow needs; and filling knowledge gaps. A review of the impacts of flow regulation on the health of the River Murray revealed evidence for decline, but the case for flow regulation as the main cause is circumstantial or uncertain. This is to be expected, because the decline of the River Murray results

  6. RRAWFLOW: Rainfall-Response Aquifer and Watershed Flow Model (v1.11)

    Science.gov (United States)

    Long, A. J.

    2014-09-01

    The Rainfall-Response Aquifer and Watershed Flow Model (RRAWFLOW) is a lumped-parameter model that simulates streamflow, springflow, groundwater level, solute transport, or cave drip for a measurement point in response to a system input of precipitation, recharge, or solute injection. The RRAWFLOW open-source code is written in the R language and is included in the Supplement to this article along with an example model of springflow. RRAWFLOW includes a time-series process to estimate recharge from precipitation and simulates the response to recharge by convolution; i.e., the unit hydrograph approach. Gamma functions are used for estimation of parametric impulse-response functions (IRFs); a combination of two gamma functions results in a double-peaked IRF. A spline fit to a set of control points is introduced as a new method for estimation of nonparametric IRFs. Other options include the use of user-defined IRFs and different methods to simulate time-variant systems. For many applications, lumped models simulate the system response with equal accuracy to that of distributed models, but moreover, the ease of model construction and calibration of lumped models makes them a good choice for many applications. RRAWFLOW provides professional hydrologists and students with an accessible and versatile tool for lumped-parameter modeling.

  7. Hydrological real-time modelling in the Zambezi river basin using satellite-based soil moisture and rainfall data

    Directory of Open Access Journals (Sweden)

    P. Meier

    2011-03-01

    Full Text Available Reliable real-time forecasts of the discharge can provide valuable information for the management of a river basin system. For the management of ecological releases even discharge forecasts with moderate accuracy can be beneficial. Sequential data assimilation using the Ensemble Kalman Filter provides a tool that is both efficient and robust for a real-time modelling framework. One key parameter in a hydrological system is the soil moisture, which recently can be characterized by satellite based measurements. A forecasting framework for the prediction of discharges is developed and applied to three different sub-basins of the Zambezi River Basin. The model is solely based on remote sensing data providing soil moisture and rainfall estimates. The soil moisture product used is based on the back-scattering intensity of a radar signal measured by a radar scatterometer. These soil moisture data correlate well with the measured discharge of the corresponding watershed if the data are shifted by a time lag which is dependent on the size and the dominant runoff process in the catchment. This time lag is the basis for the applicability of the soil moisture data for hydrological forecasts. The conceptual model developed is based on two storage compartments. The processes modeled include evaporation losses, infiltration and percolation. The application of this model in a real-time modelling framework yields good results in watersheds where soil storage is an important factor. The lead time of the forecast is dependent on the size and the retention capacity of the watershed. For the largest watershed a forecast over 40 days can be provided. However, the quality of the forecast increases significantly with decreasing prediction time. In a watershed with little soil storage and a quick response to rainfall events, the performance is relatively poor and the lead time is as short as 10 days only.

  8. Analysis of rainfall-induced shallow landslides and debris flows in the Eastern Pyrenees

    Science.gov (United States)

    Portilla Gamboa, M.; Hürlimann, M.; Corominas, J.

    2009-09-01

    The inventory of rainfall-induced mass movements, rainfall data, and slope characteristics are considered the basis of the analysis determining appropriate rainfall thresholds for mass movements in a specific region. The rainfall-induced landslide thresholds established in the literature for the Catalan Pyrenees have been formulated referring to the rainfall events of November 1982, September 1992, December 1997, and others occurred after 1999. It has been shown that a rainfall intensity greater than 190 mm in 24 hours without antecedent rainfall would be necessary to produce mass movements (Corominas and Moya, 1999; Corominas et al, 2002) or 51mm in 24h with 61 mm of accumulated rainfall (Marco, 2007). Short duration-high intensity rainfalls have brought about several mass movements in some Catalonian regions throughout the course of twenty-first century (Berga, Bonaigua, Saldes, Montserrat, Port-Ainé, Riu Runer, and Sant Nicolau). Preliminary analysis of these events shows that it is necessary to review the thresholds defined so far and redo the existing inventory of mass movements for the Catalan Pyrenees. The present work shows the usefulness of aerial photographs in the reconstruction of the inventory of historic mass movements (Molló-Queralbs, 1940; Arties-Vielha, 1963; Barruera-Senet, 1940 and 1963, and Berga-Cercs, 1982, 1997 and 2008). Also, it highlights the treatment given to scarce and scattered rainfall data available inside these Catalonia’s regions, and the application of Geographic Information Systems (ArcGIS) in the management of the gathered information. The results acquired until now show that the historic rainfall events occurred in the Eastern Pyrenees have yielded many more mass movements than those reported in the literature. Besides, it can be said that the thresholds formulated for the Pyrenees are valid for longstanding regional rainfalls, and not for local downpours. In the latter cases it should be necessary to take into account the

  9. Altered Precipitation and Flow Patterns in the Dunajec River Basin

    Directory of Open Access Journals (Sweden)

    Mariola Kędra

    2017-01-01

    Full Text Available This study analyzes changes in long-term patterns of precipitation and river flow, as well as changes in their variability over the most recent 60 years (1956–2015. The study area is situated in the mountain basin of the Dunajec River, encompassing streams draining the Tatra Mountains in southern Poland. The focus of the study was to evaluate how regional warming translates into precipitation changes in the studied mountain region, and how changes in climate affect sub-regional hydrology. Monthly time series of precipitation measured at several sites were compared for two 30-year periods (1986–2015 versus 1956–1985. The significance of the difference between the periods in question was evaluated by means of the Wilcoxon signed rank test with the Bonferroni correction. The identified shifts in precipitation for 6 months are statistically significant and largely consistent with the revealed changes in river flow patterns. Moreover, significant differences in precipitation variability were noted in the study area, resulting in a significant decrease in the repeatability of precipitation over the most recent 30 years (1986–2015. Changes in the variability of the river flow studied were less visible in this particular mountain region (while significant for two months; however, the overall repeatability of river flow decreased significantly at the same rate as for precipitation.

  10. Predictability of Western Himalayan river flow: melt seasonal inflow into Bhakra Reservoir in northern India

    Directory of Open Access Journals (Sweden)

    I. Pal

    2013-06-01

    Full Text Available Snowmelt-dominated streamflow of the Western Himalayan rivers is an important water resource during the dry pre-monsoon spring months to meet the irrigation and hydropower needs in northern India. Here we study the seasonal prediction of melt-dominated total inflow into the Bhakra Dam in northern India based on statistical relationships with meteorological variables during the preceding winter. Total inflow into the Bhakra Dam includes the Satluj River flow together with a flow diversion from its tributary, the Beas River. Both are tributaries of the Indus River that originate from the Western Himalayas, which is an under-studied region. Average measured winter snow volume at the upper-elevation stations and corresponding lower-elevation rainfall and temperature of the Satluj River basin were considered as empirical predictors. Akaike information criteria (AIC and Bayesian information criteria (BIC were used to select the best subset of inputs from all the possible combinations of predictors for a multiple linear regression framework. To test for potential issues arising due to multicollinearity of the predictor variables, cross-validated prediction skills of the best subset were also compared with the prediction skills of principal component regression (PCR and partial least squares regression (PLSR techniques, which yielded broadly similar results. As a whole, the forecasts of the melt season at the end of winter and as the melt season commences were shown to have potential skill for guiding the development of stochastic optimization models to manage the trade-off between irrigation and hydropower releases versus flood control during the annual fill cycle of the Bhakra Reservoir, a major energy and irrigation source in the region.

  11. Denitrification in the Mississippi River network controlled by flow through river bedforms

    Science.gov (United States)

    Gomez-Velez, Jesus D.; Harvey, Judson W.; Cardenas, M. Bayani; Kiel, Brian

    2015-01-01

    Increasing nitrogen concentrations in the world’s major rivers have led to over-fertilization of sensitive downstream waters1, 2, 3, 4. Flow through channel bed and bank sediments acts to remove riverine nitrogen through microbe-mediated denitrification reactions5, 6, 7, 8, 9, 10. However, little is understood about where in the channel network this biophysical process is most efficient, why certain channels are more effective nitrogen reactors, and how management practices can enhance the removal of nitrogen in regions where water circulates through sediment and mixes with groundwater - hyporheic zones8, 11, 12. Here we present numerical simulations of hyporheic flow and denitrification throughout the Mississippi River network using a hydrogeomorphic model. We find that vertical exchange with sediments beneath the riverbed in hyporheic zones, driven by submerged bedforms, has denitrification potential that far exceeds lateral hyporheic exchange with sediments alongside river channels, driven by river bars and meandering banks. We propose that geomorphic differences along river corridors can explain why denitrification efficiency varies between basins in the Mississippi River network. Our findings suggest that promoting the development of permeable bedforms at the streambed - and thus vertical hyporheic exchange - would be more effective at enhancing river denitrification in large river basins than promoting lateral exchange through induced channel meandering. 

  12. Water quality modelling in the San Antonio River Basin driven by radar rainfall data

    Directory of Open Access Journals (Sweden)

    Almoutaz Elhassan

    2016-05-01

    Full Text Available Continuous monitoring of stream water quality is needed as it has significant impacts on human and ecological health and well-being. Estimating water quality between sampling dates requires model simulation based on the available geospatial and water quality data for a given watershed. Models such as the Soil and Water Assessment Tool (SWAT can be used to estimate the missing water quality data. In this study, SWAT was used to estimate water quality at a monitoring station near the outlet of the San Antonio River. Precipitation data from both rain gauges and weather radar were used to force the SWAT simulations. Virtual rain gauges which were based on weather radar data were created in the approximate centres of the 163 sub-watersheds of the San Antonio River Basin for SWAT simulations. This method was first tested in a smaller watershed in the middle of the Guadalupe River Basin resulting in increased model efficiency in simulating surface run-off. The method was then applied to the San Antonio River watershed and yielded good simulations for surface run-off (R2 = 0.7, nitrate (R2 = 0.6 and phosphate (R2 = 0.5 at the watershed outlet (Goliad, TX – USGS (United States Geological Survey gauge as compared to observed data. The study showed that the proper use of weather radar precipitation in SWAT model simulations improves the estimation of missing water quality data.

  13. STEP-TRAMM - A modeling interface for simulating localized rainfall induced shallow landslides and debris flow runout pathways

    Science.gov (United States)

    Or, D.; von Ruette, J.; Lehmann, P.

    2017-12-01

    Landslides and subsequent debris-flows initiated by rainfall represent a common natural hazard in mountainous regions. We integrated a landslide hydro-mechanical triggering model with a simple model for debris flow runout pathways and developed a graphical user interface (GUI) to represent these natural hazards at catchment scale at any location. The STEP-TRAMM GUI provides process-based estimates of the initiation locations and sizes of landslides patterns based on digital elevation models (SRTM) linked with high resolution global soil maps (SoilGrids 250 m resolution) and satellite based information on rainfall statistics for the selected region. In the preprocessing phase the STEP-TRAMM model estimates soil depth distribution to supplement other soil information for delineating key hydrological and mechanical properties relevant to representing local soil failure. We will illustrate this publicly available GUI and modeling platform to simulate effects of deforestation on landslide hazards in several regions and compare model outcome with satellite based information.

  14. Variability of Rainfall Erosivity and Erosivity Density in the Ganjiang River Catchment, China: Characteristics and Influences of Climate Change

    Directory of Open Access Journals (Sweden)

    Xianghu Li

    2018-02-01

    Full Text Available Soil erosion is one of the most critical environmental hazards in the world. Understanding the changes in rainfall erosivity (RE and erosivity density (ED, as well as their affecting factors, at local and catchment scales in the context of climate warming is an important prerequisite of soil erosion prevention and soil loss risk assessment. The present study identified the variability and trends of RE and ED in terms of both time and space in the Ganjiang River catchment over the period of 1960–2012, and also analyzed and discussed the impact of climate change. The results show that RE and ED in the catchment had great monthly variations and high year-to-year variability. Both presented long-term increasing trends over the entire study period. The highest RE and ED were observed in June and in the eastern and northeast parts of the catchment, which indicated that June was the most susceptible month for soil erosion in this area and the lower reaches of the Ganjiang River was the riskiest area for soil erosion. Finally, the East Asian summer monsoon and climate change were highly correlated with changes in RE and ED.

  15. Impact of urban WWTP and CSO fluxes on river peak flow extremes under current and future climate conditions.

    Science.gov (United States)

    Keupers, Ingrid; Willems, Patrick

    2013-01-01

    The impact of urban water fluxes on the river system outflow of the Grote Nete catchment (Belgium) was studied. First the impact of the Waste Water Treatment Plant (WWTP) and the Combined Sewer Overflow (CSO) outflows on the river system for the current climatic conditions was determined by simulating the urban fluxes as point sources in a detailed, hydrodynamic river model. Comparison was made of the simulation results on peak flow extremes with and without the urban point sources. In a second step, the impact of climate change scenarios on the urban fluxes and the consequent impacts on the river flow extremes were studied. It is shown that the change in the 10-year return period hourly peak flow discharge due to climate change (-14% to +45%) was in the same order of magnitude as the change due to the urban fluxes (+5%) in current climate conditions. Different climate change scenarios do not change the impact of the urban fluxes much except for the climate scenario that involves a strong increase in rainfall extremes in summer. This scenario leads to a strong increase of the impact of the urban fluxes on the river system.

  16. Analysis of rainfall preceding debris flows on the Smědavská hora Mt., Jizerské hory Mts., Czech Republic

    Czech Academy of Sciences Publication Activity Database

    Smolíková, J.; Blahůt, Jan; Vilímek, V.

    2016-01-01

    Roč. 13, č. 4 (2016), s. 683-696 ISSN 1612-510X Institutional support: RVO:67985891 Keywords : debris flow * rainfall pattern * rainfall thresholds * Jizerské hory Mts. * Czech Republic Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 3.657, year: 2016

  17. Potential predictability of a Colombian river flow

    Science.gov (United States)

    Córdoba-Machado, Samir; Palomino-Lemus, Reiner; Quishpe-Vásquez, César; García-Valdecasas-Ojeda, Matilde; Raquel Gámiz-Fortis, Sonia; Castro-Díez, Yolanda; Jesús Esteban-Parra, María

    2017-04-01

    In this study the predictability of an important Colombian river (Cauca) has been analysed based on the use of climatic variables as potential predictors. Cauca River is considered one of the most important rivers of Colombia because its basin supports important productive activities related with the agriculture, such as the production of coffee or sugar. Potential relationships between the Cauca River seasonal streamflow anomalies and different climatic variables such as sea surface temperature (SST), precipitation (Pt), temperature over land (Tm) and soil water (Sw) have been analysed for the period 1949-2009. For this end, moving correlation analysis of 30 years have been carried out for lags from one to four seasons for the global SST, and from one to two seasons for South America Pt, Tm and Sw. Also, the stability of the significant correlations have been also studied, identifying the regions used as potential predictors of streamflow. Finally, in order to establish a prediction scheme based on the previous stable correlations, a Principal Component Analysis (PCA) applied on the potential predictor regions has been carried out in order to obtain a representative time series for each predictor field. Significant and stable correlations between the seasonal streamflow and the tropical Pacific SST (El Niño region) are found for lags from one to four (one-year) season. Additionally, some regions in the Indian and Atlantic Oceans also show significant and stable correlations at different lags, highlighting the importance that exerts the Atlantic SST on the hydrology of Colombia. Also significant and stable correlations are found with the Pt, Tm and Sw for some regions over South America, at lags of one and two seasons. The prediction of Cauca seasonal streamflow based on this scheme shows an acceptable skill and represents a relative improvement compared with the predictability obtained using the teleconnection indices associated with El Niño. Keywords

  18. Rainfall thresholds and susceptibility mapping for shallow landslides and debris flows in Scotland

    Science.gov (United States)

    Postance, Benjamin; Hillier, John; Dijkstra, Tom; Dixon, Neil

    2017-04-01

    Shallow translational slides and debris flows (hereafter 'landslides') pose a significant threat to life and cause significant annual economic impacts (e.g. by damage and disruption of infrastructure). The focus of this research is on the definition of objective rainfall thresholds using a weather radar system and landslide susceptibility mapping. In the study area Scotland, an inventory of 75 known landslides was used for the period 2003 to 2016. First, the effect of using different rain records (i.e. time series length) on two threshold selection techniques in receiver operating characteristic (ROC) analysis was evaluated. The results show that thresholds selected by 'Threat Score' (minimising false alarms) are sensitive to rain record length and which is not routinely considered, whereas thresholds selected using 'Optimal Point' (minimising failed alarms) are not; therefore these may be suited to establishing lower limit thresholds and be of interest to those developing early warning systems. Robust thresholds are found for combinations of normalised rain duration and accumulation at 1 and 12 day's antecedence respectively; these are normalised using the rainy-day normal and an equivalent measure for rain intensity. This research indicates that, in Scotland, rain accumulation provides a better indicator than rain intensity and that landslides may be generated by threshold conditions lower than previously thought. Second, a landslide susceptibility map is constructed using a cross-validated logistic regression model. A novel element of the approach is that landslide susceptibility is calculated for individual hillslope sections. The developed thresholds and susceptibility map are combined to assess potential hazards and impacts posed to the national highway network in Scotland.

  19. Rainfall and flow of the Riozinho do Rôla Basin on Western Amazon

    OpenAIRE

    Maria Lúcia Hall de Souza; Elias Silva; Edson Alves Araújo; Herly Carlos Teixeira Dias; France Maria Gontijo Coelho; Maria de Nazaré Costa de Macêdo

    2013-01-01

    The present study was conducted to analyze the factors influencing the hydrological behavior of the Riozinho do Rôla hydrographic basin, and was based on descriptive analysis tools. Fourteen pluviometers were set up in order to conduct a representative analysis of the rainfall in the basin. Residents of the area voluntarily participated in collection of the rainfall data in the years 2007 and 2008; the residents were trained to collect the data before the pluviometers were installed. ArcGis 9...

  20. 1992 Columbia River salmon flow measures Options Analysis/EIS

    International Nuclear Information System (INIS)

    1992-01-01

    This Options Analysis/Environmental Impact Statement (OA/EIS) identifies, presents effects of, and evaluates the potential options for changing instream flow levels in efforts to increase salmon populations in the lower Columbia and Snake rivers. The potential actions would be implemented during 1992 to benefit juvenile and adult salmon during migration through eight run-of-river reservoirs. The Corps of Engineers (Corps) prepared this document in cooperation with the Bonneville Power Administration and the Bureau of Reclamation. The US Fish and Wildlife Service (FSWS) is a participating agency. The text and appendices of the document describe the characteristics of 10 Federal projects and one private water development project in the Columbia River drainage basin. Present and potential operation of these projects and their effects on the salmon that spawn and rear in the Columbia and Snake River System are presented. The life history, status, and response of Pacific salmon to current environmental conditions are described

  1. 1992 Columbia River Salmon Flow Measures Options Analysis/EIS.

    Energy Technology Data Exchange (ETDEWEB)

    1992-01-01

    This Options Analysis/Environmental Impact Statement (OA/EIS) identifies, presents effects of, and evaluates the potential options for changing instream flow levels in efforts to increase salmon populations in the lower Columbia and Snake rivers. The potential actions would be implemented during 1992 to benefit juvenile and adult salmon during migration through eight run-of-river reservoirs. The Corps of Engineers (Corps) prepared this document in cooperation with the Bonneville Power Administration and the Bureau of Reclamation. The US Fish and Wildlife Service (FSWS) is a participating agency. The text and appendices of the document describe the characteristics of 10 Federal projects and one private water development project in the Columbia River drainage basin. Present and potential operation of these projects and their effects on the salmon that spawn and rear in the Columbia and Snake River System are presented. The life history, status, and response of Pacific salmon to current environmental conditions are described.

  2. Joint impact of rainfall and tidal level on flood risk in a coastal city with a complex river network: a case study of Fuzhou City, China

    Directory of Open Access Journals (Sweden)

    J. J. Lian

    2013-02-01

    Full Text Available Coastal cities are particularly vulnerable to flood under multivariable conditions, such as heavy precipitation, high sea levels, and storms. The combined effect of multiple sources and the joint probability of extremes should be considered to assess and manage flood risk better. This paper aims to study the combined effect of rainfall and the tidal level of the receiving water body on flood probability and severity in Fuzhou City, which has a complex river network. Flood severity under a range of precipitation intensities, with return periods (RPs of 5 yr to 100 yr, and tidal levels was assessed through a hydrodynamic model verified by data observed during Typhoon Longwang in 2005. According to the percentages of the river network where flooding occurred, the threshold conditions for flood severity were estimated in two scenarios: with and without working pumps. In Fuzhou City, working pumps efficiently reduce flood risk from precipitation within a 20-yr RP. However, the pumps may not work efficiently when rainfall exceeds a 100-yr RP because of the limited conveyance capacity of the river network. Joint risk probability was estimated through the optimal copula. The joint probability of rainfall and tidal level both exceeding their threshold values is very low, and the greatest threat in Fuzhou comes from heavy rainfall. However, the tidal level poses an extra risk of flood. Given that this extra risk is ignored in the design of flood defense in Fuzhou, flood frequency and severity may be higher than understood during design.

  3. Effects of extreme rainfall events on the distribution of selected emerging contaminants in surface and groundwater: The Guadalete River basin (SW, Spain).

    Science.gov (United States)

    Corada-Fernández, Carmen; Candela, Lucila; Torres-Fuentes, Nivis; Pintado-Herrera, Marina G; Paniw, Maria; González-Mazo, Eduardo

    2017-12-15

    This study is focused on the Guadalete River basin (SW, Spain), where extreme weather conditions have become common, with and alternation between periods of drought and extreme rainfall events. Combined sewer overflows (CSOs) occur when heavy rainfall events exceed the capacity of the wastewater treatment plants (WWTP), as well as pollution episodes in parts of the basin due to uncontrolled sewage spills and the use of reclaimed water and sludge from the local WWTP. The sampling was carried out along two seasons and three campaigns during dry (March 2007) and extreme rainfall (April and December 2010) in the Guadalete River, alluvial aquifer and Jerez de la Frontera aquifer. Results showed minimum concentrations for synthetic surfactants in groundwater (contaminants increased in December 2010 as the heavy rainfall caused the river to overflow. In surface water, surfactant concentrations showed similar trends to groundwater observations. In addition to surfactants, pharmaceuticals and personal care products (PPCPs) were analyzed in the third campaign, 22 of which were detected in surface waters. Two fragrances (OTNE and galaxolide) and one analgesic/anti-inflammatory (ibuprofen) were the most abundant PPCPs (up to 6540, 2748 and 1747ng·L -1 , respectively). Regarding groundwater, most PPCPs were detected in Jerez de la Frontera aquifer, where a synthetic fragrance (OTNE) was predominant (up to 1285ng·L -1 ). Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Designing ecological flows to gravely braided rivers in alpine environments

    Science.gov (United States)

    Egozi, R.; Ashmore, P.

    2009-04-01

    Designing ecological flows in gravelly braided streams requires estimating the channel forming discharge in order to maintain the braided reach physical (allocation of flow and bed load) and ecological (maintaining the habitat diversity) functions. At present, compared to single meander streams, there are fewer guiding principles for river practitioners that can be used to manage braided streams. Insight into braiding morphodynamics using braiding intensity indices allows estimation of channel forming discharge. We assess variation in braiding intensity by mapping the total number of channels (BIT) and the number of active (transporting bed load) channels (BIA) at different stages of typical diurnal melt-water hydrographs in a pro-glacial braided river, Sunwapta River, Canada. Results show that both BIA and BIT vary with flow stage but over a limited range of values. Furthermore, maximum BIT occurs below peak discharge. At this stage there is a balance between channel merging from inundation and occupation of new channels as the stage rises. This stage is the channel forming discharge because above this stage the existing braided pattern cannot discharge the volume of water without causing morphological changes (e.g., destruction of bifurcations, channel avulsion). Estimation of the channel forming discharge requires a set of braiding intensity measurements over a range of flow stages. The design of ecological flows must take into consideration flow regime characteristics rather than just the channel forming discharge magnitude.

  5. Impacts of Rainfall Variability, Land Use and Land Cover Change on Stream Flow of the Black Volta Basin, West Africa

    Directory of Open Access Journals (Sweden)

    Komlavi Akpoti

    2016-07-01

    Full Text Available Potential implications of rainfall variability along with Land Use and Land Cover Change (LULC on stream flow have been assessed in the Black Volta basin using the SWAT model. The spatio-temporal variability of rainfall over the Black Volta was assessed using the Mann-Kendall monotonic trend test and the Sen’s slope for the period 1976–2011. The statistics of the trend test showed that 61.4% of the rain gauges presented an increased precipitation trend whereas the rest of the stations showed a decreased trend. However, the test performed at the 95% confidence interval level showed that the detected trends in the rainfall data were not statistically significant. Land use trends between the year 2000 and 2013 show that within thirteen years, land use classes like bare land, urban areas, water bodies, agricultural lands, deciduous forests and evergreen forests have increased respectively by 67.06%, 33.22%, 7.62%, 29.66%, 60.18%, and 38.38%. Only grass land has decreased by 44.54% within this period. Changes in seasonal stream flow due to LULC were assessed by defining dry and wet seasons. The results showed that from year 2000 to year 2013, the dry season discharge has increased by 6% whereas the discharge of wet season has increased by 1%. The changes in stream flows components such us surface run-off (SURF_Q, lateral flow (LAT_Q and ground water contribution to stream flow (GW_Q and also on evapotranspiration (ET changes due to LULC was evaluated. The results showed that between the year 2000 and 2013, SURF_Q and LAT_Q have respectively increased by 27% and 19% while GW_Q has decreased by 6% while ET has increased by 4.59%. The resultant effects are that the water yield to stream flow has increased by 4%.

  6. Climate influences on Vaal River flow | Jury | Water SA

    African Journals Online (AJOL)

    A study of climatic influences on Vaal River discharge, near Johannesburg, South Africa, finds that peak summer flows in the period 1979–2014 coincide with ocean–atmosphere interaction in the east Atlantic. The analysis has three parts: interannual influences by correlation of summer discharge with climate fields, ...

  7. Modeling river dune evolution using a parameterization of flow separation

    NARCIS (Netherlands)

    Paarlberg, Andries J.; Dohmen-Janssen, C. Marjolein; Hulscher, Suzanne J.M.H.; Termes, Paul

    2009-01-01

    This paper presents an idealized morphodynamic model to predict river dune evolution. The flow field is solved in a vertical plane assuming hydrostatic pressure conditions. The sediment transport is computed using a Meyer-Peter–Müller type of equation, including gravitational bed slope effects and a

  8. Comparative Measurement of Stream Flow in the Ethiope River for ...

    African Journals Online (AJOL)

    This study investigates comparative measurement of stream flow in the Ethiope River for small hydropower development. Two methods – the Float and Current Meter or Bridge Broom Methods were investigated and values compared to determine best method for optimal power generation. Depth and width measurements ...

  9. Computation of the flow in shallow river bends

    NARCIS (Netherlands)

    Kalkwijk, J.P.T.; De Vriend, H.J.

    1980-01-01

    The mathematical model presented describes the flow in rivers of which: i the depth is small compared with the width, ii the width is small compared with the radius of curvature, iii the horizontal length scale of the bottom variations is of the order of magnitude of the width. Within these limits,

  10. Low-Flow Water Study for the Missouri River.

    Science.gov (United States)

    2008-08-01

    The (MoDOT) retained TranSystems to identify and review low-flow industry : trends, equipment and strategies used in inland navigation settings throughout the United States and worldwide which : may be transferable to the Missouri River and which cou...

  11. Downstream flow top width prediction in a river system | Choudhury ...

    African Journals Online (AJOL)

    ANFIS, ARIMA and Hybrid Multiple Inflows Muskingum models (HMIM) were applied to simulate and forecast downstream discharge and flow top widths in a river system. The ANFIS model works on a set of linguistic rules while the ARIMA model uses a set of past values to predict the next value in a time series. The HMIM ...

  12. Flow characteristics and salinity patterns of tidal rivers within the northern Ten Thousand Islands, southwest Florida, water years 2007–14

    Science.gov (United States)

    Booth, Amanda C.; Soderqvist, Lars E.

    2016-12-12

    Freshwater flow to the Ten Thousand Islands estuary has been altered by the construction of the Tamiami Trail and the Southern Golden Gate Estates. The Picayune Strand Restoration Project, which is associated with the Comprehensive Everglades Restoration Plan, has been implemented to improve freshwater delivery to the Ten Thousand Islands estuary by removing hundreds of miles of roads, emplacing hundreds of canal plugs, removing exotic vegetation, and constructing three pump stations. Quantifying the tributary flows and salinity patterns prior to, during, and after the restoration is essential to assessing the effectiveness of upstream restoration efforts.Tributary flow and salinity patterns during preliminary restoration efforts and prior to the installation of pump stations were analyzed to provide baseline data and preliminary analysis of changes due to restoration efforts. The study assessed streamflow and salinity data for water years1 2007–2014 for the Faka Union River (canal flow included), East River, Little Wood River, Pumpkin River, and Blackwater River. Salinity data from the Palm River and Faka Union Boundary water-quality stations were also assessed.Faka Union River was the dominant contributor of freshwater during water years 2007–14 to the Ten Thousand Islands estuary, followed by Little Wood and East Rivers. Pumpkin River and Blackwater River were the least substantial contributors of freshwater flow. The lowest annual flow volumes, the highest annual mean salinities, and the highest percentage of salinity values greater than 35 parts per thousand (ppt) occurred in water year 2011 at all sites with available data, corresponding with the lowest annual rainfall during the study. The highest annual flow volumes and the lowest percentage of salinities greater than 35 ppt occurred in water year 2013 for all sites with available data, corresponding with the highest rainfall during the study.In water year 2014, the percentage of monitored annual flow

  13. Investigating the impact of land cover change on peak river flow in UK upland peat catchments, based on modelled scenarios

    Science.gov (United States)

    Gao, Jihui; Holden, Joseph; Kirkby, Mike

    2014-05-01

    Changes to land cover can influence the velocity of overland flow. In headwater peatlands, saturation means that overland flow is a dominant source of runoff, particularly during heavy rainfall events. Human modifications in headwater peatlands may include removal of vegetation (e.g. by erosion processes, fire, pollution, overgrazing) or pro-active revegetation of peat with sedges such as Eriophorum or mosses such as Sphagnum. How these modifications affect the river flow, and in particular the flood peak, in headwater peatlands is a key problem for land management. In particular, the impact of the spatial distribution of land cover change (e.g. different locations and sizes of land cover change area) on river flow is not clear. In this presentation a new fully distributed version of TOPMODEL, which represents the effects of distributed land cover change on river discharge, was employed to investigate land cover change impacts in three UK upland peat catchments (Trout Beck in the North Pennines, the Wye in mid-Wales and the East Dart in southwest England). Land cover scenarios with three typical land covers (i.e. Eriophorum, Sphagnum and bare peat) having different surface roughness in upland peatlands were designed for these catchments to investigate land cover impacts on river flow through simulation runs of the distributed model. As a result of hypothesis testing three land cover principles emerged from the work as follows: Principle (1): Well vegetated buffer strips are important for reducing flow peaks. A wider bare peat strip nearer to the river channel gives a higher flow peak and reduces the delay to peak; conversely, a wider buffer strip with higher density vegetation (e.g. Sphagnum) leads to a lower peak and postpones the peak. In both cases, a narrower buffer strip surrounding upstream and downstream channels has a greater effect than a thicker buffer strip just based around the downstream river network. Principle (2): When the area of change is equal

  14. Water allocation assessment in low flow river under data scarce conditions: a study of hydrological simulation in Mediterranean basin.

    Science.gov (United States)

    Bangash, Rubab F; Passuello, Ana; Hammond, Michael; Schuhmacher, Marta

    2012-12-01

    River Francolí is a small river in Catalonia (northeastern Spain) with an average annual low flow (~2 m(3)/s). The purpose of the River Francolí watershed assessments is to support and inform region-wide planning efforts from the perspective of water protection, climate change and water allocation. In this study, a hydrological model of the Francolí River watershed was developed for use as a tool for watershed planning, water resource assessment, and ultimately, water allocation purposes using hydrological data from 2002 to 2006 inclusive. The modeling package selected for this application is DHI's MIKE BASIN. This model is a strategic scale water resource management simulation model, which includes modeling of both land surface and subsurface hydrological processes. Topographic, land use, hydrological, rainfall, and meteorological data were used to develop the model segmentation and input. Due to the unavailability of required catchment runoff data, the NAM rainfall-runoff model was used to calculate runoff of all the sub-watersheds. The results reveal a potential pressure on the availability of groundwater and surface water in the lower part of River Francolí as was expected by the IPCC for Mediterranean river basins. The study also revealed that due to the complex hydrological regime existing in the study area and data scarcity, a comprehensive physically based method was required to better represent the interaction between groundwater and surface water. The combined ArcGIS/MIKE BASIN models appear as a useful tool to assess the hydrological cycle and to better understand water allocation to different sectors in the Francolí River watershed. Copyright © 2012 Elsevier B.V. All rights reserved.

  15. Flood modelling with a distributed event-based parsimonious rainfall-runoff model: case of the karstic Lez river catchment

    Directory of Open Access Journals (Sweden)

    M. Coustau

    2012-04-01

    Full Text Available Rainfall-runoff models are crucial tools for the statistical prediction of flash floods and real-time forecasting. This paper focuses on a karstic basin in the South of France and proposes a distributed parsimonious event-based rainfall-runoff model, coherent with the poor knowledge of both evaporative and underground fluxes. The model combines a SCS runoff model and a Lag and Route routing model for each cell of a regular grid mesh. The efficiency of the model is discussed not only to satisfactorily simulate floods but also to get powerful relationships between the initial condition of the model and various predictors of the initial wetness state of the basin, such as the base flow, the Hu2 index from the Meteo-France SIM model and the piezometric levels of the aquifer. The advantage of using meteorological radar rainfall in flood modelling is also assessed. Model calibration proved to be satisfactory by using an hourly time step with Nash criterion values, ranging between 0.66 and 0.94 for eighteen of the twenty-one selected events. The radar rainfall inputs significantly improved the simulations or the assessment of the initial condition of the model for 5 events at the beginning of autumn, mostly in September–October (mean improvement of Nash is 0.09; correction in the initial condition ranges from −205 to 124 mm, but were less efficient for the events at the end of autumn. In this period, the weak vertical extension of the precipitation system and the low altitude of the 0 °C isotherm could affect the efficiency of radar measurements due to the distance between the basin and the radar (~60 km. The model initial condition S is correlated with the three tested predictors (R2 > 0.6. The interpretation of the model suggests that groundwater does not affect the first peaks of the flood, but can strongly impact subsequent peaks in the case of a multi-storm event. Because this kind of model is based on a limited

  16. Assessing flow regime alterations in a temporary river – the River Celone case study

    Directory of Open Access Journals (Sweden)

    De Girolamo Anna Maria

    2015-09-01

    Full Text Available In this paper, we present an approach to evaluate the hydrological alterations of a temporary river. In these rivers, it is expected that anthropogenic pressures largely modify low-flow components of the flow regime with consequences for aquatic habitat and diversity in invertebrate species. First, by using a simple hydrological index (IARI river segments of the Celone stream (southern Italy whose hydrological regime is significantly influenced by anthropogenic activities have been identified. Hydrological alteration has been further classified through the analysis of two metrics: the degree (Mf and the predictability of dry flow conditions (Sd6. Measured streamflow data were used to calculate the metrics in present conditions (impacted. Given the lack of data from pristine conditions, simulated streamflow time series were used to calculate the metrics in reference conditions. The Soil and Water Assessment Tool (SWAT model was used to estimate daily natural streamflow. Hydrological alterations associated with water abstractions, point discharges and the presence of a reservoir were assessed by comparing the metrics (Mf, Sd6 before and after the impacts. The results show that the hydrological regime of the river segment located in the upper part of the basin is slightly altered, while the regime of the river segment downstream of the reservoir is heavily altered. This approach is intended for use with ecological metrics in defining the water quality status and in planning streamflow management activities.

  17. Assessment of the Effects of Temperature and Precipitation Variations on the Trend of River Flows in Urmia Lake Watershed

    Directory of Open Access Journals (Sweden)

    Ashkan Farokhnia

    2014-07-01

    Full Text Available Trend analysis is one of the appropriate methods to assess the hydro-climatic condition of watersheds, which is commonly used for analysis of change pattern in a single variable over time. However, in real cases, many hydrological variables such as river flow are directly affected by climate and environmental factors, which usually go unnoticed in routine analyzes. The aim of the present research is to investigate the trend of river discharge in 25 hydrometric stations in Lake Urmia river basin with and without consideration of temperature and rainfall variability. Briefly, the results showed that there is a decreasing trend in all stations, which is significant in 9 cases. Also, it has been shown that regarding to trends in precipitation and temperature, the number of stations with significant decreasing trend will reduce to 7, which shows low impact of climate factors on the reduction rate of discharge in these stations. Based on the results, it can be concluded that climate variations have direct effect in inferring significant trends in river flow, so that considering these variables in studying of river discharge can lead to different results in the detection of significant trends.

  18. Statistical evaluation of rainfall time series in concurrence with agriculture and water resources of Ken River basin, Central India (1901-2010)

    Science.gov (United States)

    Meshram, Sarita Gajbhiye; Singh, Sudhir Kumar; Meshram, Chandrashekhar; Deo, Ravinesh C.; Ambade, Balram

    2017-12-01

    Trend analysis of long-term rainfall records can be used to facilitate better agriculture water management decision and climate risk studies. The main objective of this study was to identify the existing trends in the long-term rainfall time series over the period 1901-2010 utilizing 12 hydrological stations located at the Ken River basin (KRB) in Madhya Pradesh, India. To investigate the different trends, the rainfall time series data were divided into annual and seasonal (i.e., pre-monsoon, monsoon, post-monsoon, and winter season) sub-sets, and a statistical analysis of data using the non-parametric Mann-Kendall (MK) test and the Sen's slope approach was applied to identify the nature of the existing trends in rainfall series for the Ken River basin. The obtained results were further interpolated with the aid of the Quantum Geographic Information System (GIS) approach employing the inverse distance weighted approach. The results showed that the monsoon and the winter season exhibited a negative trend in rainfall changes over the period of study, and this was true for all stations, although the changes during the pre- and the post-monsoon seasons were less significant. The outcomes of this research study also suggest significant decreases in the seasonal and annual trends of rainfall amounts in the study period. These findings showing a clear signature of climate change impacts on KRB region potentially have implications in terms of climate risk management strategies to be developed during major growing and harvesting seasons and also to aid in the appropriate water resource management strategies that must be implemented in decision-making process.

  19. Long-term flow forecasts based on climate and hydrologic modeling: Uruguay River basin

    Science.gov (United States)

    Tucci, Carlos Eduardo Morelli; Clarke, Robin Thomas; Collischonn, Walter; da Silva Dias, Pedro Leite; de Oliveira, Gilvan Sampaio

    2003-07-01

    This paper describes a procedure for predicting seasonal flow in the Rio Uruguay drainage basin (area 75,000 km2, lying in Brazilian territory), using sequences of future daily rainfall given by the global climate model (GCM) of the Brazilian agency for climate prediction (Centro de Previsão de Tempo e Clima, or CPTEC). Sequences of future daily rainfall given by this model were used as input to a rainfall-runoff model appropriate for large drainage basins. Forecasts of flow in the Rio Uruguay were made for the period 1995-2001 of the full record, which began in 1940. Analysis showed that GCM forecasts underestimated rainfall over almost all the basin, particularly in winter, although interannual variability in regional rainfall was reproduced relatively well. A statistical procedure was used to correct for the underestimation of rainfall. When the corrected rainfall sequences were transformed to flow by the hydrologic model, forecasts of flow in the Rio Uruguay basin were better than forecasts based on historic mean or median flows by 37% for monthly flows and by 54% for 3-monthly flows.

  20. Recovery of contaminated wetland soils at the Savannah River Site by natural rainfall: An experimental, toxicological study

    International Nuclear Information System (INIS)

    Loehle, C.

    1990-08-01

    This study was conducted at the Department of Energy Savannah River Site in South Carolina. Seepage basins at the SRS F-Area received liquid effluent from the 1950s to 1988. This effluent was typically acidic, containing high amounts of total dissolved ions, low levels of tritium and other radioactive elements, and trace levels of various heavy metals. Sodium (from NaOH), and aluminum [from soil matrix reduction due to acid leachate] were at particularly high levels in the outcropping water. The effluent gradually seeped down to the water table and subsequently outcropped along the edge of a forested wetland bordering Four Mile Creek. A laboratory study was conducted to evaluate the potential for natural remediation of contaminated wetland soils by rainfall. Contaminated soils were collected and leached repeatedly with rainwater. After 6 leachings the leachate was observed to be non-toxic to lettuce seedlings, whereas the initial leachate was very toxic. These results suggest that more detailed studies on leaching as a remediation technique would be beneficial. 6 refs., 2 figs., 3 tabs

  1. A methodology for treating missing data applied to daily rainfall data in the Candelaro River Basin (Italy).

    Science.gov (United States)

    Lo Presti, Rossella; Barca, Emanuele; Passarella, Giuseppe

    2010-01-01

    Environmental time series are often affected by the "presence" of missing data, but when dealing statistically with data, the need to fill in the gaps estimating the missing values must be considered. At present, a large number of statistical techniques are available to achieve this objective; they range from very simple methods, such as using the sample mean, to very sophisticated ones, such as multiple imputation. A brand new methodology for missing data estimation is proposed, which tries to merge the obvious advantages of the simplest techniques (e.g. their vocation to be easily implemented) with the strength of the newest techniques. The proposed method consists in the application of two consecutive stages: once it has been ascertained that a specific monitoring station is affected by missing data, the "most similar" monitoring stations are identified among neighbouring stations on the basis of a suitable similarity coefficient; in the second stage, a regressive method is applied in order to estimate the missing data. In this paper, four different regressive methods are applied and compared, in order to determine which is the most reliable for filling in the gaps, using rainfall data series measured in the Candelaro River Basin located in South Italy.

  2. TRENDS IN VARIABILITY OF WATER FLOW OF TELEAJEN RIVER

    Directory of Open Access Journals (Sweden)

    N. JIPA

    2012-03-01

    Full Text Available TRENDS IN VARIABILITY OF WATER FLOW OF TELEAJEN RIVER. In the context of climate change at global and regional scale, this study intends to identify the trends in variability of the annual and monthly flow of Teleajen river. The study is based on processing the series of mean, maximum and minimum flows at Cheia and Moara Domnească hydrometric stations (these data were taken from the National Institute of Meteorology and Hydrology. The period of analysis is 1966-1998, statistical methods beeing mostly used, among which the Mann – Kendall test, that identifies the liniar trend and its statistic significance, comes into focus. The trends in the variability of water annual and monthly flows are highlighted. The results obtained show downward trends for the mean and maximum annual flows, and for the minimum water discharge, a downward trend for Cheia station and an upward trend for Moara Domnească station. Knowing the trends in the variability of the rivers’ flow is important empirically in view of taking adequate administration measures of the water resources and managment measures for the risks lead by extreme hidrologic events (floods, low-water, according to the possible identified changes.

  3. Flow controls on lowland river macrophytes: a review.

    Science.gov (United States)

    Franklin, Paul; Dunbar, Michael; Whitehead, Paul

    2008-08-01

    We review the current status of knowledge regarding the role that flow parameters play in controlling the macrophyte communities of temperate lowland rivers. We consider both direct and indirect effects and the interaction with other factors known to control macrophyte communities. Knowledge gaps are identified and implications for the management of river systems considered. The main factors and processes controlling the status of macrophytes in lowland rivers are velocity (hence also discharge), light, substrate, competition, nutrient status and river management practices. We suggest that whilst the characteristics of any particular macrophyte community reflect the integral effects of a combination of the factors, fundamental importance can be attributed to the role of discharge and velocity in controlling instream macrophyte colonisation, establishment and persistence. Velocity and discharge also appear to control the relative influence of some of the other controlling factors. Despite the apparent importance of velocity in determining the status of macrophyte communities in lowland rivers, relatively little is understood about the nature of the processes controlling this relationship. Quantitative knowledge is particularly lacking. Consequently, the ability to predict macrophyte abundance and distribution in rivers is still limited. This is further complicated by the likely existence of feedback effects between the growth of macrophytes and velocity. Demand for water resources increases the pressure on lowland aquatic ecosystems. Despite growing recognition of the need to allocate water for the needs of instream biota, the inability to assess the flow requirements of macrophyte communities limits the scope to achieve this. This increases the likelihood of overexploitation of the water resource as other users, whose demands are quantifiable, are prioritised.

  4. Owyhee River intracanyon lava flows: does the river give a dam?

    Science.gov (United States)

    Ely, Lisa L.; Brossy, Cooper C.; House, P. Kyle; Safran, Elizabeth B.; O'Connor, Jim E.; Champion, Duane E.; Fenton, Cassandra R.; Bondre, Ninad R.; Orem, Caitlin A.; Grant, Gordon E.; Henry, Christopher D.; Turrin, Brent D.

    2013-01-01

    Rivers carved into uplifted plateaus are commonly disrupted by discrete events from the surrounding landscape, such as lava flows or large mass movements. These disruptions are independent of slope, basin area, or channel discharge, and can dominate aspects of valley morphology and channel behavior for many kilometers. We document and assess the effects of one type of disruptive event, lava dams, on river valley morphology and incision rates at a variety of time scales, using examples from the Owyhee River in southeastern Oregon. Six sets of basaltic lava flows entered and dammed the river canyon during two periods in the late Cenozoic ca. 2 Ma–780 ka and 250–70 ka. The dams are strongly asymmetric, with steep, blunt escarpments facing up valley and long, low slopes down valley. None of the dams shows evidence of catastrophic failure; all blocked the river and diverted water over or around the dam crest. The net effect of the dams was therefore to inhibit rather than promote incision. Once incision resumed, most of the intracanyon flows were incised relatively rapidly and therefore did not exert a lasting impact on the river valley profile over time scales >106 yr. The net long-term incision rate from the time of the oldest documented lava dam, the Bogus Rim lava dam (≤1.7 Ma), to present was 0.18 mm/yr, but incision rates through or around individual lava dams were up to an order of magnitude greater. At least three lava dams (Bogus Rim, Saddle Butte, and West Crater) show evidence that incision initiated only after the impounded lakes filled completely with sediment and there was gravel transport across the dams. The most recent lava dam, formed by the West Crater lava flow around 70 ka, persisted for at least 25 k.y. before incision began, and the dam was largely removed within another 35 k.y. The time scale over which the lava dams inhibit incision is therefore directly affected by both the volume of lava forming the dam and the time required for sediment

  5. Investigation of flow and transport parameters in some Romanian rivers

    International Nuclear Information System (INIS)

    Pascu, M.; Gaspar, E.; Gaspar, R. D.; Roncea, C.; Pascu, A.

    1998-01-01

    Together with continuous pollution, the accidental spills-e.g. from industrial faults-are the greatest danger for rivers. When such spill occurs, downstream water supplies have to be warned about the arrival time of the pollutant wave. Establishing an efficient warning system implies knowing of the flow and transport parameters of the river. Within this frame, two tracer experiments were carried out in the Olt and Somes rivers, using 32 Br and fluorescent dye tracers as injected in input pulses. A basic analysis of the field data allows the calculation of the water Residence Time Distribution and the maximum concentration of the tracer versus the distance from the injection point. Afterwards, some results are found based on the interpolation technique, in order to estimate the travel time and the maximum concentration of the pollutant along the river for a given flow rate and a given injection point. A further analysis of the field data using the dispersion theory allows determining the transfer velocities of the water and dispersion coefficient. Empirical relationship between velocity, dispersion coefficient and the distance from injection point is established. (author)

  6. Estimating the Risk of River Flow under Climate Change in the Tsengwen River Basin

    Directory of Open Access Journals (Sweden)

    Hsiao-Ping Wei

    2016-03-01

    Full Text Available This study evaluated the overflow risk of the Tsengwen River under a climate change scenario by using bias-corrected dynamic downscaled data as inputs for a SOBEK model (Deltares, the Netherlands. The results showed that the simulated river flow rate at Yufeng Bridge (upstream, Erxi Bridge (midstream, and XinZong (1 (downstream stations are at risk of exceeding the management plan’s flow rate for three projection periods (1979–2003, 2015–2039, 2075–2099. After validation with the geomorphic and hydrological data collected in this study, the frequency at which the flow rate exceeded the design flood was 2 in 88 events in the base period (1979–2003, 6 in 82 events in the near future (2015–2039, and 10 in 81 events at the end of the century (2075–2099.

  7. Analyses of flow modification on water quality on Nechako River

    International Nuclear Information System (INIS)

    Mitchell, A.C.; James, C.B.; Edinger, J.E.

    1995-01-01

    Alcan Smelters and Chemicals Ltd. initiated construction of the final phase of the Kemano Completion Project in north-central British Columbia to divert additional water from the Nechako Reservoir to the existing powerhouse. The Nechako Reservoir was created by the construction of the Kenney Dam in Nechako Canyon, a natural barrier to salmon migration. The Nechako River downstream of Nechako Canyon supports important runs of sockeye and chinook salmon. This additional diversion of Nechako River flow creates the potential of high water temperatures and increased thermal stress to migrating sockeye salmon enroute to their spawning grounds in Nechako River tributaries. To achieve specific downstream water temperature objectives during sockeye salmon migration each summer, a two-level outlet facility adjacent to Kenney Dam is to be constructed to release cooling water at 10 C to the Nechako River. Results of mathematical modeling of Nechako River water temperatures show that, based on specified design criteria, a maximum Kenney Dam release of 167 m 3 /s at 10 C would be required to meet the downstream water temperature objectives

  8. The Role of Forests in Regulating the River Flow Regime of Large Basins of the World

    Science.gov (United States)

    Salazar, J. F.; Villegas, J. C.; Mercado-Bettin, D. A.; Rodríguez, E.

    2017-12-01

    Many natural and social phenomena depend on river flow regimes that are being altered by global change. Understanding the mechanisms behind such alterations is crucial for predicting river flow regimes in a changing environment. Here we explore potential linkages between the presence of forests and the capacity of river basins for regulating river flows. Regulation is defined here as the capacity of river basins to attenuate the amplitude of the river flow regime, that is to reduce the difference between high and low flows. We first use scaling theory to show how scaling properties of observed river flows can be used to classify river basins as regulated or unregulated. This parsimonious classification is based on a physical interpretation of the scaling properties (particularly the scaling exponents) that is novel (most previous studies have focused on the interpretation of the scaling exponents for floods only), and widely-applicable to different basins (the only assumption is that river flows in a given river basin exhibit scaling properties through well-known power laws). Then we show how this scaling framework can be used to explore global-change-induced temporal variations in the regulation capacity of river basins. Finally, we propose a conceptual hypothesis (the "Forest reservoir concept") to explain how large-scale forests can exert important effects on the long-term water balance partitioning and regulation capacity of large basins of the world. Our quantitative results are based on data analysis (river flows and land cover features) from 22 large basins of the world, with emphasis in the Amazon river and its main tributaries. Collectively, our findings support the hypothesis that forest cover enhances the capacity of large river basins to maintain relatively high mean river flows, as well as to regulate (ameliorate) extreme river flows. Advancing towards this quantitative understanding of the relation between forest cover and river flow regimes is

  9. Anthropogenic Water Uses and River Flow Regime Alterations by Dams

    Science.gov (United States)

    Ferrazzi, M.; Botter, G.

    2017-12-01

    Dams and impoundments have been designed to reconcile the systematic conflict between patterns of anthropogenic water uses and the temporal variability of river flows. Over the past seven decades, population growth and economic development led to a marked increase in the number of these water infrastructures, so that unregulated free-flowing rivers are now rare in developed countries and alterations of the hydrologic cycle at global scale have to be properly considered and characterized. Therefore, improving our understanding of the influence of dams and reservoirs on hydrologic regimes is going to play a key role in water planning and management. In this study, a physically based analytic approach is combined to extensive hydrologic data to investigate natural flow regime alterations downstream of dams in the Central-Eastern United States. These representative case studies span a wide range of different uses, including flood control, water supply and hydropower production. Our analysis reveals that the most evident effects of flood control through dams is a decrease in the intra-seasonal variability of flows, whose extent is controlled by the ratio between the storage capacity for flood control and the average incoming streamflow. Conversely, reservoirs used for water supply lead to an increase of daily streamflow variability and an enhanced inter-catchment heterogeneity. Over the last decades, the supply of fresh water required to sustain human populations has become a major concern at global scale. Accordingly, the number of reservoirs devoted to water supply increased by 50% in the US. This pattern foreshadows a possible shift in the cumulative effect of dams on river flow regimes in terms of inter-catchment homogenization and intra-annual flow variability.

  10. Detecting Human Hydrologic Alteration from Diversion Hydropower Requires Universal Flow Prediction Tools: A Proposed Framework for Flow Prediction in Poorly-gauged, Regulated Rivers

    Science.gov (United States)

    Kibler, K. M.; Alipour, M.

    2016-12-01

    Achieving the universal energy access Sustainable Development Goal will require great investment in renewable energy infrastructure in the developing world. Much growth in the renewable sector will come from new hydropower projects, including small and diversion hydropower in remote and mountainous regions. Yet, human impacts to hydrological systems from diversion hydropower are poorly described. Diversion hydropower is often implemented in ungauged rivers, thus detection of impact requires flow analysis tools suited to prediction in poorly-gauged and human-altered catchments. We conduct a comprehensive analysis of hydrologic alteration in 32 rivers developed with diversion hydropower in southwestern China. As flow data are sparse, we devise an approach for estimating streamflow during pre- and post-development periods, drawing upon a decade of research into prediction in ungauged basins. We apply a rainfall-runoff model, parameterized and forced exclusively with global-scale data, in hydrologically-similar gauged and ungauged catchments. Uncertain "soft" data are incorporated through fuzzy numbers and confidence-based weighting, and a multi-criteria objective function is applied to evaluate model performance. Testing indicates that the proposed framework returns superior performance (NSE = 0.77) as compared to models parameterized by rote calibration (NSE = 0.62). Confident that the models are providing `the right answer for the right reasons', our analysis of hydrologic alteration based on simulated flows indicates statistically significant hydrologic effects of diversion hydropower across many rivers. Mean annual flows, 7-day minimum and 7-day maximum flows decreased. Frequency and duration of flow exceeding Q25 decreased while duration of flows sustained below the Q75 increased substantially. Hydrograph rise and fall rates and flow constancy increased. The proposed methodology may be applied to improve diversion hydropower design in data-limited regions.

  11. Stochastic Modelling of Shiroro River Stream flow Process

    OpenAIRE

    Musa, J. J

    2013-01-01

    Economists, social scientists and engineers provide insights into the drivers of anthropogenic climate change and the options for adaptation and mitigation, and yet other scientists, including geographers and biologists, study the impacts of climate change. This project concentrates mainly on the discharge from the Shiroro River. A stochastic approach is presented for modeling a time series by an Autoregressive Moving Average model (ARMA). The development and use of a stochastic stream flow m...

  12. The Graded Alluvial River: Variable Flow and the Dominant Discharge

    Science.gov (United States)

    Blom, A.; Arkesteijn, L.; Viparelli, E.

    2016-12-01

    We derive analytical formulations for the graded or equilibrium longitudinal profile of a mixed-sediment alluvial river under variable flow. The formulations are applicable to reaches upstream from the backwater zone. The model is based on the conservation equations for the mass of two distinct sediment modes, sand and gravel, at the bed surface to account for the effects of grain size selective transport and abrasion of gravel particles. The effects of a variable flow rate are included by (a) treating the flow as a continuously changing yet steady water discharge (i.e. here termed an alternating steady discharge) and (b) assuming the time scale of changes in channel slope and bed surface texture to be much larger than the one of changes in flow rate. The equations are simplified realizing that at equilibrium the river profile finds itself in a dynamic steady state with oscillations around constant mean values of channel slope and bed surface texture. A generalized sediment transport relation representing the stochastic nature of sediment transport allows for explicit or analytical solutions to the streamwise decrease of both the channel slope and the bed surface mean grain size under variable flow for reaches unaffected by backwater effects. This modelling approach also provides a definition of a channel-forming or dominant water discharge, i.e., that steady water discharge that is equivalent in its effect on the equilibrium channel slope to the full hydrograph.

  13. Ground water flow velocity in the bank of the Columbia River, Hanford, Washington

    International Nuclear Information System (INIS)

    Ballard, S.

    1995-12-01

    To properly characterize the transport of contaminants from the sediments beneath the Hanford Site into the Columbia River, a suite of In Situ Permeable Flow Sensors was deployed to accurately characterize the hydrologic regime in the banks of the river. The three dimensional flow velocity was recorded on an hourly basis from mid May to mid July, 1994 and for one week in September. The first data collection interval coincided with the seasonal high water level in the river while the second interval reflected conditions during relatively low seasonal river stage. Two flow sensors located approximately 50 feet from the river recorded flow directions which correlated very well with river stage, both on seasonal and diurnal time scales. During time intervals characterized by falling river stage, the flow sensors recorded flow toward the river while flow away from the river was recorded during times of rising river stage. The flow sensor near the river in the Hanford Formation recorded a component of flow oriented vertically downward, probably reflecting the details of the hydrostratigraphy in close proximity to the probe. The flow sensor near the river in the Ringold Formation recorded an upward component of flow which dominated the horizontal components most of the time. The upward flow in the Ringold probably reflects regional groundwater flow into the river. The magnitudes of the flow velocities recorded by the flow sensors were lower than expected, probably as a result of drilling induced disturbance of the hydraulic properties of the sediments around the probes. The probes were installed with resonant sonic drilling which may have compacted the sediments immediately surrounding the probes, thereby reducing the hydraulic conductivity adjacent to the probes and diverting the groundwater flow away from the sensors

  14. A Computed River Flow-Based Turbine Controller on a Programmable Logic Controller for Run-Off River Hydroelectric Systems

    Directory of Open Access Journals (Sweden)

    Razali Jidin

    2017-10-01

    Full Text Available The main feature of a run-off river hydroelectric system is a small size intake pond that overspills when river flow is more than turbines’ intake. As river flow fluctuates, a large proportion of the potential energy is wasted due to the spillages which can occur when turbines are operated manually. Manual operation is often adopted due to unreliability of water level-based controllers at many remote and unmanned run-off river hydropower plants. In order to overcome these issues, this paper proposes a novel method by developing a controller that derives turbine output set points from computed mass flow rate of rivers that feed the hydroelectric system. The computed flow is derived by summation of pond volume difference with numerical integration of both turbine discharge flows and spillages. This approach of estimating river flow allows the use of existing sensors rather than requiring the installation of new ones. All computations, including the numerical integration, have been realized as ladder logics on a programmable logic controller. The implemented controller manages the dynamic changes in the flow rate of the river better than the old point-level based controller, with the aid of a newly installed water level sensor. The computed mass flow rate of the river also allows the controller to straightforwardly determine the number of turbines to be in service with considerations of turbine efficiencies and auxiliary power conservation.

  15. Impact of farm dams on river flows; A case study in the Limpopo River basin, Southern Africa

    NARCIS (Netherlands)

    Meijer, E.; Querner, E.P.; Boesveld, H.

    2013-01-01

    The study analysed the impact of a farm dam on the river flow in the Limpopo River basin. Two methods are used to calculate the water inflow: one uses the runoff component from the catchment water balance; the other uses the drainage output of the SIMFLOW model. The impact on the flow in a

  16. What maintains the waters flowing in our rivers?

    Science.gov (United States)

    Vasconcelos, Vitor Vieira

    2017-07-01

    This article discusses how new contributions from hydrogeological science in the 20th and 21st centuries have allowed for a better understanding of the processes that affect the maintenance of river flows. Moreover, the way in which this knowledge has been conveyed beyond academia and has been gradually incorporated into public policy for natural resource management is also discussed. This article explains the development of several approaches used to understand the relationships among the management of aquifers, vegetation and river flows, including water balance, aquifer recharge, the piston effect, seasonal effects, and safe and sustainable yields. Additionally, the current challenges regarding the modeling of hydrological processes that integrate groundwater and surface waters are discussed. Examples of studies applied in Brazil that demonstrate these processes and stimulate thought regarding water management strategies are presented. In light of the case studies, it is possible to propose different strategies, each adapted for specific hydrogeological context to maximize aquifer recharge or base flow maintenance. Based on these strategies, the role of infiltration ponds and other artificial recharge techniques is re-evaluated in the context of the mitigation of environmental impacts on the maintenance of river flows. Proposals for the improvement of public policies regarding the payment of related environmental services to stimulate investment in aquifer recharge and the maintenance of base flow, for which the goal is to attain win-win-win situations for the environment, farmers and water users, while preventing land speculation, are discussed. Lastly, a conceptual model for the dissemination of hydrogeological knowledge in public policies is provided, and its challenges and possibilities are discussed.

  17. DETECTING FOREST STRESS AND DECLINE IN RESPONSE TO INCREASING RIVER FLOW IN SOUTHWEST FLORIDA, USA

    Science.gov (United States)

    Forest stress and decline resulting from increased river flows were investigated in Myakka River State Park (MRSP), Florida, USA. Since 1977, land-use changes around the upper Myakka River watershed have resulted in significant increases in water entering the river, which have...

  18. Spatiotemporal changes in precipitation extremes over Yangtze River basin, China, considering the rainfall shift in the late 1970s

    Science.gov (United States)

    Gao, Tao; Xie, Lian

    2016-12-01

    Precipitation extremes are the dominated causes for the formation of severe flood disasters at regional and local scales under the background of global climate change. In the present study, five annual extreme precipitation events, including 1, 7 and 30 day annual maximum rainfall and 95th and 97.5th percentile threshold levels, are analyzed relating to the reference period 1960-2011 from 140 meteorological stations over Yangtze River basin (YRB). A generalized extreme value (GEV) distribution is applied to fit annual and percentile extreme precipitation events at each station with return periods up to 200 years. The entire time period is divided into preclimatic (preceding climatic) period 1960-1980 and aftclimatic (after climatic) period 1981-2011 by considering distinctly abrupt shift of precipitation regime in the late 1970s across YRB. And the Mann-Kendall trend test is adopted to conduct trend analysis during pre- and aftclimatic periods, respectively, for the purpose of exploring possible increasing/decreasing patterns in precipitation extremes. The results indicate that the increasing trends for return values during aftclimatic period change significantly in time and space in terms of different magnitudes of extreme precipitation, while the stations with significantly positive trends are mainly distributed in the vicinity of the mainstream and major tributaries as well as large lakes, this would result in more tremendous flood disasters in the mid-lower reaches of YRB, especially in southeast coastal regions. The increasing/decreasing linear trends based on annual maximum precipitation are also investigated in pre- and aftclimatic periods, respectively, whereas those changes are not significantly similar to the variations of return values during both subperiods. Moreover, spatiotemporal patterns of precipitation extremes become more uneven and unstable in the second half period over YRB.

  19. RiverFlow2D numerical simulation of flood mitigation solutions in the Ebro River

    Directory of Open Access Journals (Sweden)

    I. Echeverribar

    2017-01-01

    Full Text Available A study of measures oriented to flood mitigation in the mid reach of the Ebro river is presented: elimination of vegetation in the riverbed, use of controlled flooding areas and construction or re-adaptation of levees. The software used is RiverFlow2D which solves the conservative free-surface flow equations with a finite volume method running on GPU. The results are compared with measurements at gauge stations and aerial views. The most effective measure has turned out to be the elimination of vegetation in the riverbed. It is demonstrated that not only the maximum flooded area is narrower but also it reduces the water depth up to 1 m. The other measures have local consequences when the peak discharge is relatively high although they could be useful in case the discharge is lower.

  20. Approximation and spatial regionalization of rainfall erosivity based on sparse data in a mountainous catchment of the Yangtze River in Central China.

    Science.gov (United States)

    Schönbrodt-Stitt, Sarah; Bosch, Anna; Behrens, Thorsten; Hartmann, Heike; Shi, Xuezheng; Scholten, Thomas

    2013-10-01

    In densely populated countries like China, clean water is one of the most challenging issues of prospective politics and environmental planning. Water pollution and eutrophication by excessive input of nitrogen and phosphorous from nonpoint sources is mostly linked to soil erosion from agricultural land. In order to prevent such water pollution by diffuse matter fluxes, knowledge about the extent of soil loss and the spatial distribution of hot spots of soil erosion is essential. In remote areas such as the mountainous regions of the upper and middle reaches of the Yangtze River, rainfall data are scarce. Since rainfall erosivity is one of the key factors in soil erosion modeling, e.g., expressed as R factor in the Revised Universal Soil Loss Equation model, a methodology is needed to spatially determine rainfall erosivity. Our study aims at the approximation and spatial regionalization of rainfall erosivity from sparse data in the large (3,200 km(2)) and strongly mountainous catchment of the Xiangxi River, a first order tributary to the Yangtze River close to the Three Gorges Dam. As data on rainfall were only obtainable in daily records for one climate station in the central part of the catchment and five stations in its surrounding area, we approximated rainfall erosivity as R factors using regression analysis combined with elevation bands derived from a digital elevation model. The mean annual R factor (R a) amounts for approximately 5,222 MJ mm ha(-1) h(-1) a(-1). With increasing altitudes, R a rises up to maximum 7,547 MJ mm ha(-1) h(-1) a(-1) at an altitude of 3,078 m a.s.l. At the outlet of the Xiangxi catchment erosivity is at minimum with approximate R a=1,986 MJ mm ha(-1) h(-1) a(-1). The comparison of our results with R factors from high-resolution measurements at comparable study sites close to the Xiangxi catchment shows good consistance and allows us to calculate grid-based R a as input for a spatially high-resolution and area-specific assessment of

  1. New insights on historic droughts in the UK: Analysis of 200 river flow reconstructions for 1890-2015

    Science.gov (United States)

    Parry, Simon; Barker, Lucy; Hannaford, Jamie; Prudhomme, Christel; Smith, Katie; Svensson, Cecilia; Tanguy, Maliko

    2017-04-01

    Hydrological droughts of the last 50 years in the UK have been well characterised owing to a relatively dense hydrometric network. Prior to this, observed river flow data were generally limited in their spatial coverage and often subject to considerable uncertainty. Whilst qualitative records indicate the occurrence of severe droughts in the late 19th and early 20th centuries, including scenarios which may cause substantial impacts to contemporary water supply systems, existing observations are not sufficient to describe their spatio-temporal characteristics. As such, insights on drought in the UK are constrained and a range of stakeholders including water companies and regulators would benefit from a more thorough assessment of historic drought characteristics and their variability. The multi-disciplinary Historic Droughts project aims to rigorously characterise droughts in the UK to inform improved drought management and communication. Driven by rainfall and potential evapotranspiration data that have been extended using recovered records, lumped catchment hydrological models are used to reconstruct daily river flows from 1890 to 2015 for more than 200 catchments across the UK. The reconstructions are derived within a state-of-the-art modelling framework which allows a comprehensive assessment of model, structure and parameter uncertainty. Standardised and threshold-based indicators are applied to the river flow reconstructions to identify and characterise hydrological drought events. The reconstructions are most beneficial in comprehensively describing well known but poorly quantified late 19th and early 20th century droughts, placing the spatial and temporal footprint of these often extreme events within the context of modern episodes for the first time. Oscillations between drought-rich and drought-poor periods are shown not to be limited to the recent observational past, providing an increased sample size of events against which to test a range of airflow and

  2. Characteristics of the event mean concentration (EMCs) from rainfall runoff on mixed agricultural land use in the shoreline zone of the Yamuna River in Delhi, India

    Science.gov (United States)

    Sharma, Deepshikha; Gupta, Ruchi; Singh, Ram Karan; Kansal, Arun

    2012-03-01

    This paper is focused on the monitoring of the diffuse pollution characteristics from the agricultural land confining the River Yamuna in Delhi (capital of India). Agricultural fields surrounding the Yamuna river are direct nonpoint source of pollution impacting the river quality. The study includes watershed delineation for the River Yamuna using SWAT (2005) and land use classification for the city using GIS and remote sensing. Thereafter, the rainfall-runoff pollutant concentrations from the mixed agricultural land use were assessed for the 2006 and 2007 monsoon period (July-September). Runoff was measured using SCS method and grab samples of rainfall runoff were collected at three stations namely Old Delhi Railway Bridge (ODRB), Nizamuddin and Okhla bridge in Delhi. The samples were analysed for physico-chemical and biological parameters. Rainfall runoff and event mean concentrations (EMCs) for different water quality parameters were characterized and the effect of land use was analyzed. The average EMCs for BOD, COD, ammonia, nitrate, TKN, hardness, TDS, TSS, chlorides, sulfates, phosphate, fluorides and TC were 21.82 mg/L, 73.48 mg/L, 72.68 μg/L, 229.87 μg/L, 15.32 μg/L, 11.36 mg/L, 117.44 mg/L, 77.60 mg/L, 117.64 mg/L, 135.82 mg/L, 0.08 mg/L, 0.85 mg/L and 2,827.47 MPN/100 mL, respectively. The EMCs of TSS, nitrogen and its compounds, phosphate and BOD were high.

  3. a multi-period markov model for monthly rainfall in lagos, nigeria

    African Journals Online (AJOL)

    PUBLICATIONS1

    A twelve-period. Markov model has been developed for the monthly rainfall data for Lagos, along the coast of .... autoregressive process to model river flow; Deo et al. (2015) utilized an ...... quences for the analysis of river basins by simulation.

  4. Low flow analysis of the lower Drava River

    International Nuclear Information System (INIS)

    Mijuskovic-Svetinovic, T; Maricic, S

    2008-01-01

    Understanding the regime and the characteristics of low streamflows is of vital importance in several aspects. It is essential for the effective planning, designing, constructing, maintaining, using and managing different water management systems and structures. In addition, frequent running and assessing of estimates of low stream-flow statistics are especially important when different aspects of water quality are considered. This paper attempts to present the results of a stochastic analysis of the River Drava low flow from the gauging station, Donji Miholjac [located at rkm 77+700]. Currently, almost all specialists apply the truncation method in low-flows analysis. Taking this into consideration, it is possible to accept the definition of a low streamflow, as a period when the analysed characteristics are either, equal to or lower than the truncation level of drought. The same method has been applied in this analysis. The calculating method applied takes into account all the essential components of the afore-mentioned process. This includes a number of elements, such as the deficit, duration or the time of the occurrence of low flows, the number of times, the maximum deficit and the maximum duration of the low flows in the analysed time period. Moreover, this paper determines computational values for deficits and for the duration of low flow in different return periods.

  5. The Diurnal and Semidiurnal Patterns of Rainfall and its Correlation to the Stream Flow Characteristic in the Ciliwung Watershed, West Java, Indonesia

    Directory of Open Access Journals (Sweden)

    Riawan Edi

    2018-01-01

    Full Text Available Based on the data analysis of 16 years of TMPA dataset, the common patterns of rainfall over the Ciliwung River Basin are diurnal and semidiurnal. Those patterns can be associated by a stationary or moving rainstorm with different magnitude and direction. Based on hydrological model simulations, both the pattern and movement have a significant role to the discharge. At the downstream area, the discharge that triggered by semidiurnal pattern of rainfall can produces higher peak discharge and longer flood duration than diurnal pattern. This result open possibility to improve our prediction on design discharge.

  6. River flow availability for environmental flow allocation downstream of hydropower facilities in the Kafue Basin of Zambia

    Science.gov (United States)

    Kalumba, Mulenga; Nyirenda, Edwin

    2017-12-01

    The Government of the Republic Zambia (GRZ) will install a new hydropower station Kafue Gorge Lower downstream of the existing Kafue Gorge Station (KGS) and plans to start operating the Itezhi-Tezhi (ITT) hydropower facility in the Kafue Basin. The Basin has significant biodiversity hot spots such as the Luangwa National park and Kafue Flats. It is described as a Man-Biosphere reserve and the National Park is a designated World Heritage Site hosting a variety of wildlife species. All these natural reserves demand special protection, and environmental flow requirements (e-flows) have been identified as a necessary need to preserve these ecosystems. Implementation of e-flows is therefore a priority as Zambia considers to install more hydropower facilities. However before allocation of e-flows, it is necessary to first assess the river flow available for allocation at existing hydropower stations in the Kafue Basin. The river flow availability in the basin was checked by assessing the variability in low and high flows since the timing, frequency and duration of extreme droughts and floods (caused by low and high flows) are all important hydrological characteristics of a flow regime that affects e-flows. The river flows for a 41 year monthly time series data (1973-2014) were used to extract independent low and high flows using the Water Engineering Time Series Processing Tool (WETSPRO). The low and high flows were used to construct cumulative frequency distribution curves that were compared and analysed to show their variation over a long period. A water balance of each hydropower station was used to check the river flow allocation aspect by comparing the calculated water balance outflow (river flow) with the observed river flow, the hydropower and consumptive water rights downstream of each hydropower station. In drought periods about 50-100 m3/s of riverflow is available or discharged at both ITT and KGS stations while as in extreme flood events about 1300-1500 m3/s

  7. Role river flow for Sr 90 decontamination of polluted territories of Belarus

    International Nuclear Information System (INIS)

    Kudel'skij, A.V.; Smith, J.T.; Zhukova, O.M.; Rudaya, S.M.; Sasina, N.V.

    2002-01-01

    Sr 90 contamination of the water flow Dnepr, Pripyat', Sozh, Besed', Iput' rivers is considered. The dynamics of reducing the average year activities of Sr 90 and the variations of the levels of Sr 90 activities in river water during spring-autumn high water are shown. The results of investigation of Sr 90 activity of the sediments of Pripyat' and Braginka rivers are connected with the second effects of the contamination of the river flowing off Sr 90 during high water period. Sr 90 transfer in composition of the flowing off river during 1990-1995 (from Belarus to Ukraine) is being estimated. (authors)

  8. Benefits and limitations of using the weather radar for the definition of rainfall thresholds for debris flows. Case study from Catalonia (Spain).

    Science.gov (United States)

    Abancó, C.; Hürlimann, M.; Sempere, D.; Berenguer, M.

    2012-04-01

    Torrential processes such as debris flows or hyperconcentrated flows are fast movements formed by a mix of water and different amounts of unsorted solid material. They occur in steep torrents and suppose a high risk for the human settlements. Rainfall is the most common triggering factor for debris flows. The rainfall threshold defines the rainfall conditions that, when reached or exceeded, are likely to provoke one or more events. Many different types of empirical rainfall thresholds for landslide triggering have been defined. Direct measurements of rainfall data are normally not available from a point next to or in the surroundings of the initiation area of the landslide. For this reason, most of the thresholds published for debris flows have been established by data measured at the nearest rain gauges (often located several km far from the landslide). Only in very few cases, the rainfall data to analyse the triggering conditions of the debris flows have been obtained by weather (Doppler) radar. Radar devices present certain limitations in mountainous regions due to undesired reboots, but their main advantage is that radar data can be obtained for any point of the territory. The objective of this work was to test the use of the weather radar data for the definition of rainfall thresholds for debris-flow triggering. Thus, rainfall data obtained from 3 to 5 rain gauges and from radar were compared for a dataset of events occurred in Catalonia (Spain). The goal was to determine in which cases the description of the rainfall episode (in particular the maximum intensity) had been more accurate. The analysed dataset consists of: 1) three events occurred in the Rebaixader debris-flow monitoring station (Axial Pyrenees) including two hyperconcentrated flows and one debris flow; 2) one debris-flow event occurred in the Port Ainé ski resort (Axial Pyrenees); 3) one debris-flow event in Montserrat (Mediterranean Coastal range). The comparison of the hyetographs from the

  9. A water availability and low-flow analysis of the Tagliamento River discharge in Italy under changing climate conditions

    Directory of Open Access Journals (Sweden)

    L. N. Gunawardhana

    2012-03-01

    Full Text Available This study estimated the effects of projected variations in precipitation and temperature on snowfall-snowmelt processes and subsequent river discharge variations in the Tagliamento River in Italy. A lumped-parameter, non-linear, rainfall-runoff model with 10 general circulation model (GCM scenarios was used. Spatial and temporal changes in snow cover were assessed using 15 high-quality Landsat images. The 7Q10 low-flow probability distribution approximated by the Log-Pearson type III distribution function was used to examine river discharge variations with respect to climate extremes in the future. On average, the results obtained for 10 scenarios indicate a consistent warming rate for all time periods, which may increase the maximum and minimum temperatures by 2.3 °C (0.6–3.7 °C and 2.7 °C (1.0–4.0 °C, respectively, by the end of the 21st century compared to the present climate. Consequently, the exponential rate of frost day decrease for 1 °C winter warming in lower-elevation areas is approximately three-fold (262% higher than that in higher-elevation areas, revealing that snowfall in lower-elevation areas will be more vulnerable under a changing climate. In spite of the relatively minor changes in annual precipitation (−17.4 ~ 1.7% compared to the average of the baseline (1991–2010 period, snowfall will likely decrease by 48–67% during the 2080–2099 time period. The mean river discharges are projected to decrease in all seasons, except winter. The low-flow analysis indicated that while the magnitude of the minimum river discharge will increase (e.g. a 25% increase in the 7Q10 estimations for the winter season in the 2080–2099 time period, the number of annual average low-flow events will also increase (e.g. 16 and 15 more days during the spring and summer seasons, respectively, in the 2080–2099 time period compared to the average during the baseline period, leading to a future with a highly variable river discharge

  10. The International River Interface Cooperative: Public Domain Software for River Flow and Morphodynamics (Invited)

    Science.gov (United States)

    Nelson, J. M.; Shimizu, Y.; McDonald, R.; Takebayashi, H.

    2009-12-01

    The International River Interface Cooperative is an informal organization made up of academic faculty and government scientists with the goal of developing, distributing and providing education for a public-domain software interface for modeling river flow and morphodynamics. Formed in late 2007, the group released the first version of this interface (iRIC) in late 2009. iRIC includes models for two and three-dimensional flow, sediment transport, bed evolution, groundwater-surface water interaction, topographic data processing, and habitat assessment, as well as comprehensive data and model output visualization, mapping, and editing tools. All the tools in iRIC are specifically designed for use in river reaches and utilize common river data sets. The models are couched within a single graphical user interface so that a broad spectrum of models are available to users without learning new pre- and post-processing tools. The first version of iRIC was developed by combining the USGS public-domain Multi-Dimensional Surface Water Modeling System (MD_SWMS), developed at the USGS Geomorphology and Sediment Transport Laboratory in Golden, Colorado, with the public-domain river modeling code NAYS developed by the Universities of Hokkaido and Kyoto, Mizuho Corporation, and the Foundation of the River Disaster Prevention Research Institute in Sapporo, Japan. Since this initial effort, other Universities and Agencies have joined the group, and the interface has been expanded to allow users to integrate their own modeling code using Executable Markup Language (XML), which provides easy access and expandability to the iRIC software interface. In this presentation, the current components of iRIC are described and results from several practical modeling applications are presented to illustrate the capabilities and flexibility of the software. In addition, some future extensions to iRIC are demonstrated, including software for Lagrangian particle tracking and the prediction of

  11. Application of The Rainfall-runoff Model Topkapi For The Entire Basin of The Po River As Part of The European Project Effs

    Science.gov (United States)

    Todini, E.; Bartholmes, J.

    The project EFFS (European Flood Forecasting System) aims at developing a flood forecasting system for the major river basins all over Europe. To extend the forecast- ing and thus the warning time in a significant way (up to 10 days) meteorological forecasting data from the ECMWF will be used as input to hydrological models. For this purpose it is fundamental to have a reliable rainfall-runoff model. For the river Po basin we chose the TOPKAPI model (Ciarapica, Todini 1998). TOPKAPI is a physi- cally based rainfall-runoff model that maintains its physical significance passing from hillslope to large basin scale. The aim of the distributed version is to reproduce the spatial variability and to lead to a better understanding of scaling effects on meteo- rological data used as well as of physical phenomena and parameters. By now the TOPKAPI model has been applied successfully to basins of smaller and medium size (up to 8000 km2). The present work also proves that TOPKAPI is a valuable flood forecasting tool for larger basins such as the Po river. An advantage of the TOPKAPI model is its physical basis. It doesn't need a "real" calibration in the common sense of the expression. The calibration work that has to be done is due to the unavoidable averaging and approximation in the input data representing various phenomena. This reduces the calibration work as well as the length of data required. The model was implemented on the Po river at spatial steps of 1km and time steps of 1 hour using available data during the year 1994. After the calibration phase, mesoscale forecasts (from ECMWF) as well as forecasts of LAM models (DWD,DMI) will be used as input to the Po river models and their behaviour will be studied as a function of the prediction quality and of the coarseness of the spatial discretisation.

  12. Large Dam Effects on Flow Regime and Hydraulic Parameters of river (Case study: Karkheh River, Downstream of Reservoir Dam

    Directory of Open Access Journals (Sweden)

    Farhang Azarang

    2017-06-01

    Full Text Available Introduction: The critical role of the rivers in supplying water for various needs of life has led to engineering identification of the hydraulic regime and flow condition of the rivers. Hydraulic structures such dams have inevitable effects on their downstream that should be well investigated. The reservoir dams are the most important hydraulic structures which are the cause of great changes in river flow conditions. Materials and Methods: In this research, an accurate assessment was performed to study the flow regime of Karkheh river at downstream of Karkheh Reservoir Dam as the largest dam in Middle East. Karkheh River is the third waterful river of Iran after Karun and Dez and the third longest river after the Karun and Sefidrud. The Karkheh Dam is a large reservoir dam built in Iran on the Karkheh River in 2000. The Karkheh Reservoir Dam is on the Karkheh River in the Northwestern Khouzestan Province, the closest city being Andimeshk to the east. The part of Karkheh River, which was studied in this research is located at downstream of Karkheh Reservoir Dam. This interval is approximately 94 km, which is located between PayePol and Abdolkhan hydrometric stations. In this research, 138 cross sections were used along Karkheh River. Distance of cross sections from each other was 680m in average. The efficient model of HEC-RAS has been utilized to simulate the Karkheh flow conditions before and after the reservoir dam construction using of hydrometric stations data included annually and monthly mean discharges, instantaneous maximum discharges, water surface profiles and etc. Three defined discharges had been chosen to simulate the Karkheh River flow; maximum defined discharge, mean defined discharge and minimum defined discharge. For each of these discharges values, HEC-RAS model was implemented as a steady flow of the Karkheh River at river reach of study. Water surface profiles of flow, hydraulic parameters and other results of flow regime in

  13. Parameter Identification and Uncertainty Analysis for Visual MODFLOW based Groundwater Flow Model in a Small River Basin, Eastern India

    Science.gov (United States)

    Jena, S.

    2015-12-01

    The overexploitation of groundwater resulted in abandoning many shallow tube wells in the river Basin in Eastern India. For the sustainability of groundwater resources, basin-scale modelling of groundwater flow is essential for the efficient planning and management of the water resources. The main intent of this study is to develope a 3-D groundwater flow model of the study basin using the Visual MODFLOW package and successfully calibrate and validate it using 17 years of observed data. The sensitivity analysis was carried out to quantify the susceptibility of aquifer system to the river bank seepage, recharge from rainfall and agriculture practices, horizontal and vertical hydraulic conductivities, and specific yield. To quantify the impact of parameter uncertainties, Sequential Uncertainty Fitting Algorithm (SUFI-2) and Markov chain Monte Carlo (MCMC) techniques were implemented. Results from the two techniques were compared and the advantages and disadvantages were analysed. Nash-Sutcliffe coefficient (NSE) and coefficient of determination (R2) were adopted as two criteria during calibration and validation of the developed model. NSE and R2 values of groundwater flow model for calibration and validation periods were in acceptable range. Also, the MCMC technique was able to provide more reasonable results than SUFI-2. The calibrated and validated model will be useful to identify the aquifer properties, analyse the groundwater flow dynamics and the change in groundwater levels in future forecasts.

  14. Daily river flow prediction based on Two-Phase Constructive Fuzzy Systems Modeling: A case of hydrological - meteorological measurements asymmetry

    Science.gov (United States)

    Bou-Fakhreddine, Bassam; Mougharbel, Imad; Faye, Alain; Abou Chakra, Sara; Pollet, Yann

    2018-03-01

    Accurate daily river flow forecast is essential in many applications of water resources such as hydropower operation, agricultural planning and flood control. This paper presents a forecasting approach to deal with a newly addressed situation where hydrological data exist for a period longer than that of meteorological data (measurements asymmetry). In fact, one of the potential solutions to resolve measurements asymmetry issue is data re-sampling. It is a matter of either considering only the hydrological data or the balanced part of the hydro-meteorological data set during the forecasting process. However, the main disadvantage is that we may lose potentially relevant information from the left-out data. In this research, the key output is a Two-Phase Constructive Fuzzy inference hybrid model that is implemented over the non re-sampled data. The introduced modeling approach must be capable of exploiting the available data efficiently with higher prediction efficiency relative to Constructive Fuzzy model trained over re-sampled data set. The study was applied to Litani River in the Bekaa Valley - Lebanon by using 4 years of rainfall and 24 years of river flow daily measurements. A Constructive Fuzzy System Model (C-FSM) and a Two-Phase Constructive Fuzzy System Model (TPC-FSM) are trained. Upon validating, the second model has shown a primarily competitive performance and accuracy with the ability to preserve a higher day-to-day variability for 1, 3 and 6 days ahead. In fact, for the longest lead period, the C-FSM and TPC-FSM were able of explaining respectively 84.6% and 86.5% of the actual river flow variation. Overall, the results indicate that TPC-FSM model has provided a better tool to capture extreme flows in the process of streamflow prediction.

  15. Geomorphic and hydrologic study of peak-flow management on the Cedar River, Washington

    Science.gov (United States)

    Magirl, Christopher S.; Gendaszek, Andrew S.; Czuba, Christiana R.; Konrad, Christopher P.; Marineau, Mathieu D.

    2012-01-01

    Assessing the linkages between high-flow events, geomorphic response, and effects on stream ecology is critical to river management. High flows on the gravel-bedded Cedar River in Washington are important to the geomorphic function of the river; however, high flows can deleteriously affect salmon embryos incubating in streambed gravels. A geomorphic analysis of the Cedar River showed evidence of historical changes in river form over time and quantified the effects of anthropogenic alterations to the river corridor. Field measurements with accelerometer scour monitors buried in the streambed provided insight into the depth and timing of streambed scour during high-flow events. Combined with a two-dimensional hydrodynamic model, the recorded accelerometer disturbances allowed the prediction of streambed disturbance at the burial depth of Chinook and sockeye salmon egg pockets for different peak discharges. Insight gained from these analyses led to the development of suggested monitoring metrics for an ongoing geomorphic monitoring program on the Cedar River.

  16. Low flows and reservoir management for the Durance River basin (Southern France) in the 2050s

    Science.gov (United States)

    Sauquet, Eric

    2015-04-01

    The Durance River is one of the major rivers located in the Southern part of France. Water resources are under high pressure due to significant water abstractions for human uses within and out of the natural boundaries of the river basin through an extended open channel network. Water demands are related to irrigation, hydropower, drinking water, industries and more recently water management has included water needs for recreational uses as well as for preserving ecological services. Water is crucial for all these activities and for the socio-economic development of South Eastern France. Both socio-economic development and population evolution will probably modify needs for water supply, irrigation, energy consumption, tourism, industry, etc. In addition the Durance river basin will have to face climate change and its impact on water availability that may question the sustainability of the current rules for water allocation. The research project R²D²-2050 "Risk, water Resources and sustainable Development within the Durance river basin in 2050" aims at assessing future water availability and risks of water shortage in the 2050s by taking into account changes in both climate and water management. R²D²-2050 is partially funded by the French Ministry in charge of Ecology and the Rhône-Méditerranée Water Agency. This multidisciplinary project (2010-2014) involves Irstea, Electricité de France (EDF), the University Pierre et Marie Curie (Paris), LTHE (CNRS), the Société du Canal de Provence (SCP) and the research and consultancy company ACTeon. A set of models have been developed to simulate climate at regional scale (given by 330 projections obtained by applying three downscaling methods), water resources (provided by seven rainfall-runoff models forced by a subset of 330 climate projections), water demand for agriculture and drinking water, for different sub basins of the Durance River basin upstream of Mallemort under present day and under future conditions

  17. DNA capture reveals transoceanic gene flow in endangered river sharks.

    Science.gov (United States)

    Li, Chenhong; Corrigan, Shannon; Yang, Lei; Straube, Nicolas; Harris, Mark; Hofreiter, Michael; White, William T; Naylor, Gavin J P

    2015-10-27

    For over a hundred years, the "river sharks" of the genus Glyphis were only known from the type specimens of species that had been collected in the 19th century. They were widely considered extinct until populations of Glyphis-like sharks were rediscovered in remote regions of Borneo and Northern Australia at the end of the 20th century. However, the genetic affinities between the newly discovered Glyphis-like populations and the poorly preserved, original museum-type specimens have never been established. Here, we present the first (to our knowledge) fully resolved, complete phylogeny of Glyphis that includes both archival-type specimens and modern material. We used a sensitive DNA hybridization capture method to obtain complete mitochondrial genomes from all of our samples and show that three of the five described river shark species are probably conspecific and widely distributed in Southeast Asia. Furthermore we show that there has been recent gene flow between locations that are separated by large oceanic expanses. Our data strongly suggest marine dispersal in these species, overturning the widely held notion that river sharks are restricted to freshwater. It seems that species in the genus Glyphis are euryhaline with an ecology similar to the bull shark, in which adult individuals live in the ocean while the young grow up in river habitats with reduced predation pressure. Finally, we discovered a previously unidentified species within the genus Glyphis that is deeply divergent from all other lineages, underscoring the current lack of knowledge about the biodiversity and ecology of these mysterious sharks.

  18. Runoff Analysis Considering Orographical Features Using Dual Polarization Radar Rainfall

    Science.gov (United States)

    Noh, Hui-seong; Shin, Hyun-seok; Kang, Na-rae; Lee, Choong-Ke; Kim, Hung-soo

    2013-04-01

    Recently, the necessity for rainfall estimation and forecasting using the radar is being highlighted, due to the frequent occurrence of torrential rainfall resulting from abnormal changes of weather. Radar rainfall data represents temporal and spatial distributions properly and replace the existing rain gauge networks. It is also frequently applied in many hydrologic field researches. However, the radar rainfall data has an accuracy limitation since it estimates rainfall, by monitoring clouds and precipitation particles formed around the surface of the earth(1.5-3km above the surface) or the atmosphere. In a condition like Korea where nearly 70% of the land is covered by mountainous areas, there are lots of restrictions to use rainfall radar, because of the occurrence of beam blocking areas by topography. This study is aiming at analyzing runoff and examining the applicability of (R(Z), R(ZDR) and R(KDP)) provided by the Han River Flood Control Office(HRFCO) based on the basin elevation of Nakdong river watershed. For this purpose, the amount of radar rainfall of each rainfall event was estimated according to three sub-basins of Nakdong river watershed with the average basin elevation above 400m which are Namgang dam, Andong dam and Hapcheon dam and also another three sub-basins with the average basin elevation below 150m which are Waegwan, Changryeong and Goryeong. After runoff analysis using a distribution model, Vflo model, the results were reviewed and compared with the observed runoff. This study estimated the rainfall by using the radar-rainfall transform formulas, (R(Z), R(Z,ZDR) and R(Z,ZDR,KDP) for four stormwater events and compared the results with the point rainfall of the rain gauge. As the result, it was overestimated or underestimated, depending on rainfall events. Also, calculation indicates that the values from R(Z,ZDR) and R(Z,ZDR,KDP) relatively showed the most similar results. Moreover the runoff analysis using the estimated radar rainfall is

  19. Longitudinal heterogeneity of flow and heat fluxes in a large lowland river: A study of the San Joaquin River, CA, USA during a large-scale flow experiment

    Science.gov (United States)

    Bray, E. N.; Dunne, T.; Dozier, J.

    2011-12-01

    Systematic downstream variation of channel characteristics, scaled by flow affects the transport and distribution of heat throughout a large river. As water moves through a river channel, streamflow and velocity may fluctuate by orders of magnitude primarily due to channel geometry, slope and resistance to flow, and the time scales of those fluctuations range from days to decades (Constantz et al., 1994; Lundquist and Cayan, 2002; McKerchar and Henderson, 2003). It is well understood that the heat budget of a river is primarily governed by surface exchanges, with the most significant surface flux coming from net shortwave radiation. The absorption of radiation at a given point in a river is determined by the wavelength-dependent index of refraction, expressed by the angle of refraction and the optical depth as a function of physical depth and the absorption coefficient (Dozier, 1980). Few studies consider the influence of hydrologic alteration to the optical properties governing net radiative heat transfer in a large lowland river, yet it is the most significant component of the heat budget and definitive to a river's thermal regime. We seek a physically based model without calibration to incorporate scale-dependent physical processes governing heat and flow dynamics in large rivers, how they change across the longitudinal profile, and how they change under different flow regimes. Longitudinal flow and heat flux analyses require synoptic flow time series from multiple sites along rivers, and few hydrometric networks meet this requirement (Larned et al, 2011). We model the energy budget in a regulated 240-km mainstem reach of the San Joaquin River California, USA equipped with multiple gaging stations from Friant Dam to its confluence with the Merced River during a large-scale flow experiment. We use detailed hydroclimatic observations distributed across the longitudinal gradient creating a non-replicable field experiment of heat fluxes across a range of flow regime

  20. 76 FR 53436 - Free Flow Power Corporation; Northland Power Mississippi River LLC; Notice of Competing...

    Science.gov (United States)

    2011-08-26

    ... Mississippi River, near the town of Luling, in St. Charles Parish, Louisiana. The sole purpose of a.... 14091-000] Free Flow Power Corporation; Northland Power Mississippi River LLC; Notice of Competing... Mississippi River LLC (Northland) filed preliminary permit applications, pursuant to section 4(f) of the...

  1. 76 FR 53427 - Free Flow Power Corporation; Northland Power Mississippi River LLC; Notice of Competing...

    Science.gov (United States)

    2011-08-26

    ... Mississippi River, near the town of Killona, in St. Charles Parish, Louisiana. The sole purpose of a.... 14092-000] Free Flow Power Corporation; Northland Power Mississippi River LLC; Notice of Competing... Mississippi River LLC (Northland) filed preliminary permit applications, pursuant to section 4(f) of the...

  2. Flow Restoration in the Columbia River Basin: An Evaluation of a Flow Restoration Accounting Framework.

    Science.gov (United States)

    McCoy, Amy L; Holmes, S Rankin; Boisjolie, Brett A

    2018-03-01

    Securing environmental flows in support of freshwater biodiversity is an evolving field of practice. An example of a large-scale program dedicated to restoring environmental flows is the Columbia Basin Water Transactions Program in the Pacific Northwest region of North America, which has been restoring flows in dewatered tributary habitats for imperiled salmon species over the past decade. This paper discusses a four-tiered flow restoration accounting framework for tracking the implementation and impacts of water transactions as an effective tool for adaptive management. The flow restoration accounting framework provides compliance and flow accounting information to monitor transaction efficacy. We review the implementation of the flow restoration accounting framework monitoring framework to demonstrate (a) the extent of water transactions that have been implemented over the past decade, (b) the volumes of restored flow in meeting flow targets for restoring habitat for anadromous fish species, and (c) an example of aquatic habitat enhancement that resulted from Columbia Basin Water Transactions Program investments. Project results show that from 2002 to 2015, the Columbia Basin Water Transactions Program has completed more than 450 water rights transactions, restoring approximately 1.59 million megaliters to date, with an additional 10.98 million megaliters of flow protected for use over the next 100 years. This has resulted in the watering of over 2414 stream kilometers within the Columbia Basin. We conclude with a discussion of the insights gained through the implementation of the flow restoration accounting framework. Understanding the approach and efficacy of a monitoring framework applied across a large river basin can be informative to emerging flow-restoration and adaptive management efforts in areas of conservation concern.

  3. Flow Restoration in the Columbia River Basin: An Evaluation of a Flow Restoration Accounting Framework

    Science.gov (United States)

    McCoy, Amy L.; Holmes, S. Rankin; Boisjolie, Brett A.

    2018-03-01

    Securing environmental flows in support of freshwater biodiversity is an evolving field of practice. An example of a large-scale program dedicated to restoring environmental flows is the Columbia Basin Water Transactions Program in the Pacific Northwest region of North America, which has been restoring flows in dewatered tributary habitats for imperiled salmon species over the past decade. This paper discusses a four-tiered flow restoration accounting framework for tracking the implementation and impacts of water transactions as an effective tool for adaptive management. The flow restoration accounting framework provides compliance and flow accounting information to monitor transaction efficacy. We review the implementation of the flow restoration accounting framework monitoring framework to demonstrate (a) the extent of water transactions that have been implemented over the past decade, (b) the volumes of restored flow in meeting flow targets for restoring habitat for anadromous fish species, and (c) an example of aquatic habitat enhancement that resulted from Columbia Basin Water Transactions Program investments. Project results show that from 2002 to 2015, the Columbia Basin Water Transactions Program has completed more than 450 water rights transactions, restoring approximately 1.59 million megaliters to date, with an additional 10.98 million megaliters of flow protected for use over the next 100 years. This has resulted in the watering of over 2414 stream kilometers within the Columbia Basin. We conclude with a discussion of the insights gained through the implementation of the flow restoration accounting framework. Understanding the approach and efficacy of a monitoring framework applied across a large river basin can be informative to emerging flow-restoration and adaptive management efforts in areas of conservation concern.

  4. Modeling the evolution of riparian woodlands facing climate change in three European rivers with contrasting flow regimes.

    Directory of Open Access Journals (Sweden)

    Rui P Rivaes

    Full Text Available Global circulation models forecasts indicate a future temperature and rainfall pattern modification worldwide. Such phenomena will become particularly evident in Europe where climate modifications could be more severe than the average change at the global level. As such, river flow regimes are expected to change, with resultant impacts on aquatic and riparian ecosystems. Riparian woodlands are among the most endangered ecosystems on earth and provide vital services to interconnected ecosystems and human societies. However, they have not been the object of many studies designed to spatially and temporally quantify how these ecosystems will react to climate change-induced flow regimes. Our goal was to assess the effects of climate-changed flow regimes on the existing riparian vegetation of three different European flow regimes. Cases studies were selected in the light of the most common watershed alimentation modes occurring across European regions, with the objective of appraising expected alterations in the riparian elements of fluvial systems due to climate change. Riparian vegetation modeling was performed using the CASiMiR-vegetation model, which bases its computation on the fluvial disturbance of the riparian patch mosaic. Modeling results show that riparian woodlands may undergo not only at least moderate changes for all flow regimes, but also some dramatic adjustments in specific areas of particular vegetation development stages. There are circumstances in which complete annihilation is feasible. Pluvial flow regimes, like the ones in southern European rivers, are those likely to experience more pronounced changes. Furthermore, regardless of the flow regime, younger and more water-dependent individuals are expected to be the most affected by climate change.

  5. How tides and river flows determine estuarine bathymetries [review article

    Science.gov (United States)

    Prandle, D.

    2004-04-01

    For strongly tidal, funnel-shaped estuaries, we examine how tides and river flows determine size and shape. We also consider how long it takes for bathymetric adjustment, both to determine whether present-day bathymetry reflects prevailing forcing and how rapidly changes might occur under future forcing scenarios. Starting with the assumption of a 'synchronous' estuary (i.e., where the sea surface slope resulting from the axial gradient in phase of tidal elevation significantly exceeds the gradient in tidal amplitude ζ̂), an expression is derived for the slope of the sea bed. Thence, by integration we derive expressions for the axial depth profile and estuarine length, L, as a function of ζ̂ and D, the prescribed depth at the mouth. Calculated values of L are broadly consistent with observations. The synchronous estuary approach enables a number of dynamical parameters to be directly calculated and conveniently illustrated as functions of ζ̂ and D, namely: current amplitude Û, ratio of friction to inertia terms, estuarine length, stratification, saline intrusion length, flushing time, mean suspended sediment concentration and sediment in-fill times. Four separate derivations for the length of saline intrusion, LI, all indicate a dependency on D 2/f ÛU o ( Uo is the residual river flow velocity and f is the bed friction coefficient). Likely bathymetries for `mixed' estuaries can be delineated by mapping, against ζ̂ and D, the conditions LI/ Lsalt. By combining the derived expressions for L and LI with this latter criterion, an expression is derived relating Di, the depth at the centre of the intrusion, to the corresponding value of Uo. This expression indicates Uo is always close to 1 cm s -1, as commonly observed. Converting from Uo to river flow, Q, provides a morphological expression linking estuarine depth to Q (with a small dependence on side slope gradients). These dynamical solutions are coupled with further generalised theory related to depth and

  6. Relations between Rainfall and Postfire Debris-Flow- and Flood-Event Magnitudes for Emergency-Response Planning, San Gabriel Mountains, Southern California, USA

    Science.gov (United States)

    Cannon, Susan; Collins, Larry; Boldt, Eric; Staley, Dennis

    2010-05-01

    Following wildfires, emergency-response and public-safety agencies are often faced with making evacuation decisions and deploying resources both well in advance of each coming winter storm and during storm events themselves. We here provide information critical to this process for recently burned areas in the San Gabriel Mountains of southern California. The National Weather Service (NWS) issues Quantitative Precipitation Forecasts (QPFs) for the San Gabriel Mountains twice a day, at approximately 4 am and 4 pm, along with unscheduled updates when conditions change. QPFs provide estimates of rainfall totals in 3-hour increments for the first 12-hour period and in 6-hour increments for the second. Estimates of one-hour rainfall intensities can be provided in the forecast narrative, along with probable peak intensities and timing, although with less confidence than rainfall totals. A compilation of information on the hydrologic response to winter storm events from recently burned areas in southern California was used to develop a system for classifying the magnitude of postfire hydrologic events. The three-class system is based on differences between the reported volume of individual debris flows, the consequences of these events in an urban setting, and the spatial extent of the response to the triggering storm. Threshold rainfall conditions that may lead to debris flow and floods of different magnitude classes are defined by integrating local rainfall data with debris-flow- and flood-event magnitude information. The within-storm rainfall accumulations (A) and durations (D) below which Magnitude I events are expected, and above which Magnitude II events may occur, are defined by A=0.4D0.55. The function A=0.6D0.50 defines the within-storm rainfall accumulations and durations above which a Magnitude III event will occur in response to a regional-scale storm, and a Magnitude II event will occur if the storm affects only a few drainage basins. The function A=1.1D0

  7. Relations Between Rainfall and Postfire Debris-Flow and Flood Magnitudes for Emergency-Response Planning, San Gabriel Mountains, Southern California

    Science.gov (United States)

    Cannon, Susan H.; Boldt, Eric M.; Kean, Jason W.; Laber, Jayme; Staley, Dennis M.

    2010-01-01

    Following wildfires, emergency-response and public-safety agencies are faced often with making evacuation decisions and deploying resources both well in advance of each coming winter storm and during storms themselves. Information critical to this process is provided for recently burned areas in the San Gabriel Mountains of southern California. The National Weather Service (NWS) issues Quantitative Precipitation Forecasts (QPFs) for the San Gabriel Mountains twice a day, at approximately 4 a.m. and 4 p.m., along with unscheduled updates when conditions change. QPFs provide estimates of rainfall totals in 3-hour increments for the first 12-hour period and in 6-hour increments for the second 12-hour period. Estimates of one-hour rainfall intensities can be provided in the forecast narrative, along with probable peak intensities and timing, although with less confidence than rainfall totals. A compilation of information on the hydrologic response to winter storms from recently burned areas in southern California steeplands was used to develop a system for classifying the magnitude of the postfire hydrologic response. The four-class system is based on a combination of the reported volume of individual debris flows, the consequences of these events in an urban setting, and the spatial extent of the response to the triggering storm. Threshold rainfall conditions associated with debris flow and floods of different magnitude classes are defined by integrating local rainfall data with debris-flow and flood magnitude information. The within-storm rainfall accumulations (A) and durations (D) above which magnitude I events are expected are defined by A=0.3D0.6. The function A=0.5D0.6 defines the within-storm rainfall accumulations and durations above which a magnitude III event will occur in response to a regional-scale storm, and a magnitude II event will occur if the storm affects only a few drainage basins. The function A=1.0D0.5defines the rainfall conditions above which

  8. Scaling properties reveal regulation of river flows in the Amazon through a forest reservoir

    Directory of Open Access Journals (Sweden)

    J. F. Salazar

    2018-03-01

    Full Text Available Many natural and social phenomena depend on river flow regimes that are being altered by global change. Understanding the mechanisms behind such alterations is crucial for predicting river flow regimes in a changing environment. Here we introduce a novel physical interpretation of the scaling properties of river flows and show that it leads to a parsimonious characterization of the flow regime of any river basin. This allows river basins to be classified as regulated or unregulated, and to identify a critical threshold between these states. We applied this framework to the Amazon river basin and found both states among its main tributaries. Then we introduce the forest reservoir hypothesis to describe the natural capacity of river basins to regulate river flows through land–atmosphere interactions (mainly precipitation recycling that depend strongly on the presence of forests. A critical implication is that forest loss can force the Amazonian river basins from regulated to unregulated states. Our results provide theoretical and applied foundations for predicting hydrological impacts of global change, including the detection of early-warning signals for critical transitions in river basins.

  9. Scaling properties reveal regulation of river flows in the Amazon through a forest reservoir

    Science.gov (United States)

    Salazar, Juan Fernando; Villegas, Juan Camilo; María Rendón, Angela; Rodríguez, Estiven; Hoyos, Isabel; Mercado-Bettín, Daniel; Poveda, Germán

    2018-03-01

    Many natural and social phenomena depend on river flow regimes that are being altered by global change. Understanding the mechanisms behind such alterations is crucial for predicting river flow regimes in a changing environment. Here we introduce a novel physical interpretation of the scaling properties of river flows and show that it leads to a parsimonious characterization of the flow regime of any river basin. This allows river basins to be classified as regulated or unregulated, and to identify a critical threshold between these states. We applied this framework to the Amazon river basin and found both states among its main tributaries. Then we introduce the forest reservoir hypothesis to describe the natural capacity of river basins to regulate river flows through land-atmosphere interactions (mainly precipitation recycling) that depend strongly on the presence of forests. A critical implication is that forest loss can force the Amazonian river basins from regulated to unregulated states. Our results provide theoretical and applied foundations for predicting hydrological impacts of global change, including the detection of early-warning signals for critical transitions in river basins.

  10. Economic interpretation of environmental flow regime downstream diverted river reaches.

    Science.gov (United States)

    Gorla, Lorenzo; Perona, Paolo

    2013-04-01

    Water demand for hydropower production is increasing together with the consciousness of the importance of riparian ecosystems and biodiversity. Some Cantons in Switzerland and other alpine regions in Austria and in Sud Tirol (Italy) started replacing the inadequate concept of Minimum Flow Requirement (MFR) with a dynamic one, by releasing a fix percentage of the total inflow (e.g. 25 %) to the environment. In the same direction Perona et al. (in revision) mathematically formulated a method particularly suitable for small hydropower plants, handling the environment as a non-traditional water use, which competes with exploitators. This model uses the Principle of Equal Marginal Utility (PEMU) as optimal water allocation rule for generating like-natural flow releases while maximizing the aggregate economic benefit of all uses (Gorla and Perona, in revision). In this paper we show how redistribution policies can be interpreted in terms of PEMU, particularly we focus at traditional water repartition rules, such as the MFR, but also to dynamic ones like proportional redistribution. For the first case we show both ecological and economical arguments suggesting its inappropriateness; in the second case we highlight explicit points of strength and weakness, and suggest ways of improvement. For example the flow release allocation rule can be changed from inflow-independent ones (e.g., proportional redistribution), to inflow-dependent ones (e.g., non-proportional). The latters, having fewer constraints, can generally lead to better both ecological and economical performances. A class of simple functions, based on the PEMU, is then proposed as a suitable solution in run-of-river or small hydropower plants. Each water repartition policy underlies an ecosystem monetization. We explicit the value of the ecosystem health underlying each policy by means of the PEMU under a few assumptions, and discuss how the theoretic efficient redistribution law obtained by our approach is

  11. Tempo-spatial dynamics of water quality and its response to river flow in estuary of Taihu Lake based on GOCI imagery.

    Science.gov (United States)

    Du, Chenggong; Li, Yunmei; Wang, Qiao; Liu, Ge; Zheng, Zhubin; Mu, Meng; Li, Yuan

    2017-12-01

    . The increase in Chl-a content was linked to higher levels of TP and good weather conditions after the rain event. Higher flow rates mainly play a dilution role for the Chl-a concentration. Erosion of the surface soil via rainfall is a major source of TSM to the estuary. This paper firstly analyzes tempo-spatial dynamics of water quality and its response to river flow in estuary of Taihu Lake, helps to further understand the impact of river input on lake water quality, and is important for lake eutrophication.

  12. Spatial scales of carbon flow in a river food web

    Science.gov (United States)

    Finlay, J.C.; Khandwala, S.; Power, M.E.

    2002-01-01

    Spatial extents of food webs that support stream and river consumers are largely unknown, but such information is essential for basic understanding and management of lotic ecosystems. We used predictable variation in algal ??13C with water velocity, and measurements of consumer ??13C and ??15N to examine carbon flow and trophic structure in food webs of the South Fork Eel River in Northern California. Analyses of ??13C showed that the most abundant macroinvertebrate groups (collector-gatherers and scrapers) relied on algae from local sources within their riffle or shallow pool habitats. In contrast, filter-feeding invertebrates in riffles relied in part on algal production derived from upstream shallow pools. Riffle invertebrate predators also relied in part on consumers of pool-derived algal carbon. One abundant taxon drifting from shallow pools and riffles (baetid mayflies) relied on algal production derived from the habitats from which they dispersed. The trophic linkage from pool algae to riffle invertebrate predators was thus mediated through either predation on pool herbivores dispersing into riffles, or on filter feeders. Algal production in shallow pool habitats dominated the resource base of vertebrate predators in all habitats at the end of the summer. We could not distinguish between the trophic roles of riffle algae and terrestrial detritus, but both carbon sources appeared to play minor roles for vertebrate consumers. In shallow pools, small vertebrates, including three-spined stickleback (Gasterosteus aculeatus), roach (Hesperoleucas symmetricus), and rough-skinned newts (Taricha granulosa), relied on invertebrate prey derived from local pool habitats. During the most productive summer period, growth of all size classes of steelhead and resident rainbow trout (Oncorhynchus mykiss) in all habitats (shallow pools, riffles, and deep unproductive pools) was largely derived from algal production in shallow pools. Preliminary data suggest that the strong

  13. Informed Decision Making Process for Managing Environmental Flows in Small River Basins

    Science.gov (United States)

    Padikkal, S.; Rema, K. P.

    2013-03-01

    Numerous examples exist worldwide of partial or complete alteration to the natural flow regime of river systems as a consequence of large scale water abstraction from upstream reaches. The effects may not be conspicuous in the case of very large rivers, but the ecosystems of smaller rivers or streams may be completely destroyed over a period of time. While restoration of the natural flow regime may not be possible, at present there is increased effort to implement restoration by regulating environmental flow. This study investigates the development of an environmental flow management model at an icon site in the small river basin of Bharathapuzha, west India. To determine optimal environmental flow regimes, a historic flow model based on data assimilated since 1978 indicated a satisfactory minimum flow depth for river ecosystem sustenance is 0.907 m (28.8 m3/s), a value also obtained from the hydraulic model; however, as three of the reservoirs were already operational at this time a flow depth of 0.922 m is considered a more viable estimate. Analysis of daily stream flow in 1997-2006, indicated adequate flow regimes during the monsoons in June-November, but that sections of the river dried out in December-May with alarming water quality conditions near the river mouth. Furthermore, the preferred minimum `dream' flow regime expressed by stakeholders of the region is a water depth of 1.548 m, which exceeds 50 % of the flood discharge in July. Water could potentially be conserved for environmental flow purposes by (1) the de-siltation of existing reservoirs or (2) reducing water spillage in the transfer between river basins. Ultimately environmental flow management of the region requires the establishment of a co-ordinated management body and the regular assimilation of water flow information from which science based decisions are made, to ensure both economic and environmental concerns are adequately addressed.

  14. Compounding Effects of Agricultural Land Use and Water Use in Free-Flowing Rivers: Confounding Issues for Environmental Flows

    Science.gov (United States)

    Hardie, Scott A.; Bobbi, Chris J.

    2018-03-01

    Defining the ecological impacts of water extraction from free-flowing river systems in altered landscapes is challenging as multiple stressors (e.g., flow regime alteration, increased sedimentation) may have simultaneous effects and attributing causality is problematic. This multiple-stressor context has been acknowledged in environmental flows science, but is often neglected when it comes to examining flow-ecology relationships, and setting and implementing environmental flows. We examined the impacts of land and water use on rivers in the upper Ringarooma River catchment in Tasmania (south-east Australia), which contains intensively irrigated agriculture, to support implementation of a water management plan. Temporal and spatial and trends in river condition were assessed using benthic macroinvertebrates as bioindicators. Relationships between macroinvertebrate community structure and environmental variables were examined using univariate and multivariate analyses, focusing on the impacts of agricultural land use and water use. Structural changes in macroinvertebrate communities in rivers in the catchment indicated temporal and spatial declines in the ecological condition of some stretches of river associated with agricultural land and water use. Moreover, water extraction appeared to exacerbate impairment associated with agricultural land use (e.g., reduced macroinvertebrate density, more flow-avoiding taxa). The findings of our catchment-specific bioassessments will underpin decision-making during the implementation of the Ringarooma water management plan, and highlight the need to consider compounding impacts of land and water use in environmental flows and water planning in agricultural landscapes.

  15. Compounding Effects of Agricultural Land Use and Water Use in Free-Flowing Rivers: Confounding Issues for Environmental Flows.

    Science.gov (United States)

    Hardie, Scott A; Bobbi, Chris J

    2018-03-01

    Defining the ecological impacts of water extraction from free-flowing river systems in altered landscapes is challenging as multiple stressors (e.g., flow regime alteration, increased sedimentation) may have simultaneous effects and attributing causality is problematic. This multiple-stressor context has been acknowledged in environmental flows science, but is often neglected when it comes to examining flow-ecology relationships, and setting and implementing environmental flows. We examined the impacts of land and water use on rivers in the upper Ringarooma River catchment in Tasmania (south-east Australia), which contains intensively irrigated agriculture, to support implementation of a water management plan. Temporal and spatial and trends in river condition were assessed using benthic macroinvertebrates as bioindicators. Relationships between macroinvertebrate community structure and environmental variables were examined using univariate and multivariate analyses, focusing on the impacts of agricultural land use and water use. Structural changes in macroinvertebrate communities in rivers in the catchment indicated temporal and spatial declines in the ecological condition of some stretches of river associated with agricultural land and water use. Moreover, water extraction appeared to exacerbate impairment associated with agricultural land use (e.g., reduced macroinvertebrate density, more flow-avoiding taxa). The findings of our catchment-specific bioassessments will underpin decision-making during the implementation of the Ringarooma water management plan, and highlight the need to consider compounding impacts of land and water use in environmental flows and water planning in agricultural landscapes.

  16. Risk analysis on heavy metal contamination in sediments of rivers flowing into Nansi Lake.

    Science.gov (United States)

    Cao, Qingqing; Song, Ying; Zhang, Yiran; Wang, Renqing; Liu, Jian

    2017-12-01

    In order to understand the risk of heavy metals in sediments of the rivers flowing into Nansi Lake, 36 surface sediments were sampled from six rivers and seven heavy metals (Cr, Cu, Ni, Zn, As, Pb, and Cd) were determined. Potential ecological risk index (RI) of the six rivers showed significant differences: Xinxue River, Jiehe River, and Guangfu River were at medium potential risk, whereas the risk of Chengguo River was the lowest. Jiehe River, Xuesha River, and Jiangji River were meeting the medium potential risk at river mouths. Geo-accumulation index (I geo ) of the seven heavy metals revealed that the contamination of Cu and Cd was more serious than most other metals in the studied areas, whereas Cr in most sites of our study was not polluted. Moreover, correlation cluster analysis demonstrated that the contamination of Cu, Ni, and Zn in six rivers was mainly caused by local emissions, whereas that of As, Pb, and Cd might come from the external inputs in different forms. Consequently, the contamination of Cu and Cd and the potential risk in Xinxue River, Jiehe River, and Guangfu River as well as the local emissions should be given more attention to safeguard the water quality of Nansi Lake and the East Route Project of South to North Water Transfer.

  17. Spatial distribution of impacts to channel bed mobility due to flow regulation, Kootenai River, USA

    Science.gov (United States)

    Michael Burke; Klaus Jorde; John M. Buffington; Jeffrey H. Braatne; Rohan Benjakar

    2006-01-01

    The regulated hydrograph of the Kootenai River between Libby Dam and Kootenay Lake has altered the natural flow regime, resulting in a significant decrease in maximum flows (60% net reduction in median 1-day annual maximum, and 77%-84% net reductions in median monthly flows for the historic peak flow months of May and June, respectively). Other key hydrologic...

  18. Extreme Rainfall In A City

    Science.gov (United States)

    Nkemdirim, Lawrence

    and river flow hazards reflect similar environmental controls.

  19. Potential effects of elevated base flow and midsummer spike flow experiments on riparian vegetation along the Green River

    Science.gov (United States)

    Friedman, Jonathan M.

    2018-01-01

    The Upper Colorado River Endangered Fish Recovery Program has requested experimental flow releases from Flaming Gorge Dam for (1) elevated summer base flows to promote larval endangered Colorado pikeminnow, and (2) midsummer spike flows to disadvantage spawning invasive smallmouth bass. This white paper explores the effects of these proposed flow modifications on riparian vegetation and sediment deposition downstream along the Green River. Although modest in magnitude, the elevated base flows and possible associated reductions in magnitude or duration of peak flows would exacerbate a long-term trend of flow stabilization on the Green River that is already leading to proliferation of vegetation including invasive tamarisk along the channel and associated sediment deposition, channel narrowing and channel simplification. Midsummer spike flows could promote establishment of late-flowering plants like tamarisk. Because channel narrowing and simplification threaten persistence and quality of backwater and side channel features needed by endangered fish, the proposed flow modifications could lead to degradation of fish habitat. Channel narrowing and vegetation encroachment could be countered by increases in peak flows or reductions in base flows in some years and by prescription of rapid flow declines following midsummer spike flows. These strategies for reducing vegetation encroachment would need to be balanced with flow

  20. Riparian trees as common denominators across the river flow spectrum: are ecophysiological methods useful tools in environmental flow assessments?

    CSIR Research Space (South Africa)

    Schachtschneider, K

    2014-04-01

    Full Text Available physiological differences for trees occurred along rivers of the drier flow regime spectrum (seasonal and ephemeral). As such, this physiological measurement may be a valuable indicator for water stress, while the other measurements might provide more conclusive...

  1. Determination of flow times and longitudinal dispersion coefficients in the Main river using 3HHO as tracer

    International Nuclear Information System (INIS)

    Krause, W.J.; Mundschenk, H.

    1989-01-01

    Single discharges from nuclear power plants as well as discrete labeling with tritiated water are used to determine flow times, flow velocities and longitudinal dispersion coefficients in German rivers as shown here, for example, for the Main river. (orig.)

  2. Detecting nonlinearity in time series driven by non-Gaussian noise: the case of river flows

    Directory of Open Access Journals (Sweden)

    F. Laio

    2004-01-01

    Full Text Available Several methods exist for the detection of nonlinearity in univariate time series. In the present work we consider riverflow time series to infer the dynamical characteristics of the rainfall-runoff transformation. It is shown that the non-Gaussian nature of the driving force (rainfall can distort the results of such methods, in particular when surrogate data techniques are used. Deterministic versus stochastic (DVS plots, conditionally applied to the decay phases of the time series, are instead proved to be a suitable tool to detect nonlinearity in processes driven by non-Gaussian (Poissonian noise. An application to daily discharges from three Italian rivers provides important clues to the presence of nonlinearity in the rainfall-runoff transformation.

  3. Evaluation of Restoration and Flow Interactions on River Structure and Function: Channel Widening of the Thur River, Switzerland

    Directory of Open Access Journals (Sweden)

    Eduardo J. Martín

    2018-04-01

    Full Text Available Removal of lateral constraints to restore rivers has become increasingly common in river resource management, but little is known how the interaction of de-channelization with flow influences ecosystem structure and function. We evaluated the ecosystem effects of river widening to improve sediment relations in the Thur River, Switzerland, 12 years after implementation. We tested if restored and non-restored reaches differed in water physico-chemistry, hyporheic function, primary production, and macroinvertebrate density and composition in relation to the flow regime. Our results showed that (i spatio-temporal variation in sediment respiration and macroinvertebrate taxonomic richness were driven by interactions between restoration and flow; (ii riverbed conditions including substrate size, organic matter content, and groundwater–surface water exchange changed due to restoration, but (iii physico-chemistry, hydraulic conditions, and primary production were not altered by restoration. Importantly, our study revealed that abiotic conditions, except channel morphology, changed only marginally, whereas other ecosystem attributes responded markedly to changes in flow-restoration interactions. These results highlight integrating a more holistic ecosystem perspective in the design and monitoring of restoration projects such as river widening in resource management, preferably in relation to flow-sediment regimes and interactions with the biotic components of the ecosystem.

  4. Flow regime alterations under changing climate in two river basins: Implications for freshwater ecosystems

    Science.gov (United States)

    Gibson, C.A.; Meyer, J.L.; Poff, N.L.; Hay, L.E.; Georgakakos, A.

    2005-01-01

    We examined impacts of future climate scenarios on flow regimes and how predicted changes might affect river ecosystems. We examined two case studies: Cle Elum River, Washington, and Chattahoochee-Apalachicola River Basin, Georgia and Florida. These rivers had available downscaled global circulation model (GCM) data and allowed us to analyse the effects of future climate scenarios on rivers with (1) different hydrographs, (2) high future water demands, and (3) a river-floodplain system. We compared observed flow regimes to those predicted under future climate scenarios to describe the extent and type of changes predicted to occur. Daily stream flow under future climate scenarios was created by either statistically downscaling GCMs (Cle Elum) or creating a regression model between climatological parameters predicted from GCMs and stream flow (Chattahoochee-Apalachicola). Flow regimes were examined for changes from current conditions with respect to ecologically relevant features including the magnitude and timing of minimum and maximum flows. The Cle Elum's hydrograph under future climate scenarios showed a dramatic shift in the timing of peak flows and lower low flow of a longer duration. These changes could mean higher summer water temperatures, lower summer dissolved oxygen, and reduced survival of larval fishes. The Chattahoochee-Apalachicola basin is heavily impacted by dams and water withdrawals for human consumption; therefore, we made comparisons between pre-large dam conditions, current conditions, current conditions with future demand, and future climate scenarios with future demand to separate climate change effects and other anthropogenic impacts. Dam construction, future climate, and future demand decreased the flow variability of the river. In addition, minimum flows were lower under future climate scenarios. These changes could decrease the connectivity of the channel and the floodplain, decrease habitat availability, and potentially lower the ability

  5. Isotope Compositions Of Mekong River Flow Water In The South Of Vietnam

    International Nuclear Information System (INIS)

    Nguyen Kien Chinh; Huynh Long; Le Danh Chuan; Nguyen Van Nhien; Tran Thi Bich Lien

    2008-01-01

    As a part of the Research Contract No. VIE/12569, isotope composition of Mekong river flow water in the South of Vietnam has been monitored to provide information on water origin and residence times, surface-groundwater exchange in the monitoring area. According to the primary results obtained, a seasonal variation as well as the dependence on local precipitation and on the river water level of isotopic composition of two distributaries of Mekong river water have been observed. At the same time a slight change on season of tritium in rivers water and the difference between tritium content in local rainy water and river water has been recorded. (author)

  6. Contribution of hydrological data to the understanding of the spatio-temporal dynamics of F-specific RNA bacteriophages in river water during rainfall-runoff events.

    Science.gov (United States)

    Fauvel, Blandine; Cauchie, Henry-Michel; Gantzer, Christophe; Ogorzaly, Leslie

    2016-05-01

    Heavy rainfall events were previously reported to bring large amounts of microorganisms in surface water, including viruses. However, little information is available on the origin and transport of viral particles in water during such rain events. In this study, an integrative approach combining microbiological and hydrological measurements was investigated to appreciate the dynamics and origins of F-specific RNA bacteriophage fluxes during two distinct rainfall-runoff events. A high frequency sampling (automatic sampler) was set up to monitor the F-specific RNA bacteriophages fluxes at a fine temporal scale during the whole course of the rainfall-runoff events. A total of 276 rainfall-runoff samples were collected and analysed using both infectivity and RT-qPCR assays. The results highlight an increase of 2.5 log10 and 1.8 log10 of infectious F-specific RNA bacteriophage fluxes in parallel of an increase of the water flow levels for both events. Faecal pollution was characterised as being mainly from anthropic origin with a significant flux of phage particles belonging to the genogroup II. At the temporal scale, two successive distinct waves of phage pollution were established and identified through the hydrological measurements. The first arrival of phages in the water column was likely to be linked to the resuspension of riverbed sediments that was responsible for a high input of genogroup II. Surface runoff contributed further to the second input of phages, and more particularly of genogroup I. In addition, an important contribution of infectious phage particles has been highlighted. These findings imply the existence of a close relationship between the risk for human health and the viral contamination of flood water. Copyright © 2016 Luxembourg institute of Science and Technology. Published by Elsevier Ltd.. All rights reserved.

  7. LJUBLJANICA CONNECTS - Restoration of the Ljubljanica River corridor and improvement of the river's flow regime

    Science.gov (United States)

    Zabret, Katarina; Sapač, Klaudija; Šraj, Mojca; Bezak, Nejc; Sečnik, Matej; Vidmar, Andrej; Brilly, Mitja

    2016-04-01

    The project Ljubljanica connects is focused on improving connectivity and living conditions in Ljubljanica River which flows through capital city of Slovenia, Ljubljana. It represents living environment for endangered and Natura 2000 targeted fish species Danube Salmon (Hucho hucho), Danube Roach (Rutilus pigus) and Striped Chub (Leuciscus souffia). The project consists of four sets of activities: concrete restoration actions including improvement of two fish passes, monitoring of fish migration, monitoring of eco-hydrological parameters, and raising of public awareness. To improve living conditions the concrete restoration measures were performed. The reconstructions of sill and two fish passes on the Ljubljanica River have been implemented and barrier's lifting system on the weir was modernized. Above the sill in Zalog there is an oxbow which was disconnected with main river channel during the low flows. Interrupted inflow of fresh water caused very poor living conditions for animals in the oxbow. The raise of the sill helped to improve this situation. One of the fish passes included in the project is more than 100 years old whereas both are protected as cultural and technical heritage. None was working properly and due to the protection no visible nor drastic measures were allowed. With smaller improvements we managed to re-establish their operation. A lifting system of the barrier at the Ambrožev trg gate was outdated and did not allow precise regulation of the water level. Too fast raising of the barrier instantly caused deterioration of eco-hydrological conditions downstream. With modernization of the electromechanical equipment the situation is improved. The fish monitoring helps us to evaluate success of concrete restoration actions. The fish population status is monitored with marking the fish with Visible Implant Elastomer (VIE) tags. Regarding the location of catch we implant tags beneath transparent or translucent tissue combining different tag

  8. Socio-Hydrology of Channel Flows in Complex River Basins: Rivers, Canals, and Distributaries in Punjab, Pakistan

    Science.gov (United States)

    Wescoat, James L.; Siddiqi, Afreen; Muhammad, Abubakr

    2018-01-01

    This paper presents a socio-hydrologic analysis of channel flows in Punjab province of the Indus River basin in Pakistan. The Indus has undergone profound transformations, from large-scale canal irrigation in the mid-nineteenth century to partition and development of the international river basin in the mid-twentieth century, systems modeling in the late-twentieth century, and new technologies for discharge measurement and data analytics in the early twenty-first century. We address these processes through a socio-hydrologic framework that couples historical geographic and analytical methods at three levels of flow in the Punjab. The first level assesses Indus River inflows analysis from its origins in 1922 to the present. The second level shows how river inflows translate into 10-daily canal command deliveries that vary widely in their conformity with canal entitlements. The third level of analysis shows how new flow measurement technologies raise questions about the performance of established methods of water scheduling (warabandi) on local distributaries. We show how near real-time measurement sheds light on the efficiency and transparency of surface water management. These local socio-hydrologic changes have implications in turn for the larger scales of canal and river inflow management in complex river basins.

  9. Comparing the urbanization and global warming impacts on extreme rainfall characteristics in Southern China Pearl River Delta megacity based on dynamical downscaling

    Science.gov (United States)

    Fung, K. Y.; Tam, C. Y.; Wang, Z.

    2017-12-01

    It is well known that urban land use can significantly influence the local temperature, precipitation and meteorology through altering land-atmosphere exchange of momentum, moisture and heat in urban areas. In recent decades, there has been a substantial increase ( 5-10%) on the intensity of extreme rainfall over Southeast China; it is projected to increase further according to the latest IPCC reports. In this study, we assess how urbanization and global warming together might impact on heavy precipitation characteristics over the highly urbanized Pearl River Delta (PRD) megacity, located in southern China. This is done by dynamically downscaling GFDL-ESM2M simulations for the present and future (RCP8.5) climate scenarios, using the Weather Research and Forecasting (WRF) model coupled with a single-layer urban canopy model (UCM). Over the PRD area, the WRF model is integrated at a resolution of 2km x 2km. To focus on extreme events, episodes covering daily rainfall intensity above the 99th percentile in Southeast China in the GFDL-ESM2M daily precipitation datasets were first identified. These extreme episodes were then dynamically downscaled in two parallel experiments with the following model designs: one with anthropogenic heat flux (AH) = 0 Wm-2 and the other with peak AH = 300 Wm-2 in the AH diurnal cycle over the urban domain. Results show that, with AH in urban area, the urban 2m-temperature can rise by about 2oC. This in turn leads to an increase of the mean as well as the extreme rain rates by 10-15% in urban domain. The latter is comparable to the impact of global warming alone, according to downscaling experiments for the RCP8.5 scenario. Implications of our results on urban effects on extreme rainfall under a warming background climate will be discussed.

  10. AIRS Impact on Analysis and Forecast of an Extreme Rainfall Event (Indus River Valley 2010) with a Global Data Assimilation and Forecast System

    Science.gov (United States)

    Reale, O.; Lau, W. K.; Susskind, J.; Rosenberg, R.

    2011-01-01

    A set of data assimilation and forecast experiments are performed with the NASA Global data assimilation and forecast system GEOS-5, to compare the impact of different approaches towards assimilation of Advanced Infrared Spectrometer (AIRS) data on the precipitation analysis and forecast skill. The event chosen is an extreme rainfall episode which occurred in late July 11 2010 in Pakistan, causing massive floods along the Indus River Valley. Results show that the assimilation of quality-controlled AIRS temperature retrievals obtained under partly cloudy conditions produce better precipitation analyses, and substantially better 7-day forecasts, than assimilation of clear-sky radiances. The improvement of precipitation forecast skill up to 7 day is very significant in the tropics, and is caused by an improved representation, attributed to cloudy retrieval assimilation, of two contributing mechanisms: the low-level moisture advection, and the concentration of moisture over the area in the days preceding the precipitation peak.

  11. A statistical forecast model using the time-scale decomposition technique to predict rainfall during flood period over the middle and lower reaches of the Yangtze River Valley

    Science.gov (United States)

    Hu, Yijia; Zhong, Zhong; Zhu, Yimin; Ha, Yao

    2018-04-01

    In this paper, a statistical forecast model using the time-scale decomposition method is established to do the seasonal prediction of the rainfall during flood period (FPR) over the middle and lower reaches of the Yangtze River Valley (MLYRV). This method decomposites the rainfall over the MLYRV into three time-scale components, namely, the interannual component with the period less than 8 years, the interdecadal component with the period from 8 to 30 years, and the interdecadal component with the period larger than 30 years. Then, the predictors are selected for the three time-scale components of FPR through the correlation analysis. At last, a statistical forecast model is established using the multiple linear regression technique to predict the three time-scale components of the FPR, respectively. The results show that this forecast model can capture the interannual and interdecadal variation of FPR. The hindcast of FPR during 14 years from 2001 to 2014 shows that the FPR can be predicted successfully in 11 out of the 14 years. This forecast model performs better than the model using traditional scheme without time-scale decomposition. Therefore, the statistical forecast model using the time-scale decomposition technique has good skills and application value in the operational prediction of FPR over the MLYRV.

  12. Application of SARIMA model to forecasting monthly flows in Waterval River, South Africa

    Directory of Open Access Journals (Sweden)

    Tadesse Kassahun Birhanu

    2017-12-01

    Full Text Available Knowledge of future river flow information is fundamental for development and management of a river system. In this study, Waterval River flow was forecasted by SARIMA model using GRETL statistical software. Mean monthly flows from 1960 to 2016 were used for modelling and forecasting. Different unit root and Mann–Kendall trend analysis proved the stationarity of the observed flow time series. Based on seasonally differenced correlogram characteristics, different SARIMA models were evaluated; their parameters were optimized, and diagnostic check up of forecasts was made using white noise and heteroscedasticity tests. Finally, based on minimum Akaike Information (AI and Hannan–Quinn (HQ criteria, SARIMA (3, 0, 2 x (3, 1, 312 model was selected for Waterval River flow forecasting. Comparison of forecast performance of SARIMA models with that of computational intelligent forecasting techniques was recommended for future study.

  13. Evaluation of ecological instream flow considering hydrological alterations in the Yellow River basin, China

    Science.gov (United States)

    Zhang, Qiang; Zhang, Zongjiao; Shi, Peijun; Singh, Vijay P.; Gu, Xihui

    2018-01-01

    The Yellow River is the second largest river in China and is the important source for water supply in the northwestern and northern China. It is often regarded as the mother river of China. Owing to climatic change and intensifying human activities, such as increasing withdrawal of water for meeting growing agricultural irrigation needs since 1986, the flow of Yellow River has decreased, with serious impacts on the ecological environment. Using multiple hydrological indicators and Flow Duration Curve (DFC)-based ecodeficit and ecosurplus, this study investigates the impact of hydrological alterations, such as the impact of water reservoirs or dams, on downstream ecological instream flow. Results indicate that: (1) due to the impoundment and hydrological regulations of water reservoirs, occurrence rates and magnitudes of high flow regimes have decreased and the decrease is also found in the magnitudes of low flow events. These changes tend to be more evident from the upper to the lower Yellow River basin; (2) human activities tend to enhance the instream flow variability, particularly after the 1980s;(3) the ecological environment in different parts of the Yellow River basin is under different degrees of ecological risk. In general, lower to higher ecological risk can be detected due to hydrological alterations from the upper to the lower Yellow River basin. This shows that conservation of ecological environment and river health is facing a serious challenge in the lower Yellow River basin; (4) ecological instream flow indices, such as ecodeficit and ecosurplus, and IHA32 hydrological indicators are in strong relationships, suggesting that ecodeficit and ecosurplus can be regarded as appropriate ecological indicators for developing measures for mitigating the adverse impact of human activities on the conservation of ecological environment in the Yellow River basin.

  14. Debris Flow Occurrence and Sediment Persistence, Upper Colorado River Valley, CO.

    Science.gov (United States)

    Grimsley, K J; Rathburn, S L; Friedman, J M; Mangano, J F

    2016-07-01

    Debris flow magnitudes and frequencies are compared across the Upper Colorado River valley to assess influences on debris flow occurrence and to evaluate valley geometry effects on sediment persistence. Dendrochronology, field mapping, and aerial photographic analysis are used to evaluate whether a 19th century earthen, water-conveyance ditch has altered the regime of debris flow occurrence in the Colorado River headwaters. Identifying any shifts in disturbance processes or changes in magnitudes and frequencies of occurrence is fundamental to establishing the historical range of variability (HRV) at the site. We found no substantial difference in frequency of debris flows cataloged at eleven sites of deposition between the east (8) and west (11) sides of the Colorado River valley over the last century, but four of the five largest debris flows originated on the west side of the valley in association with the earthen ditch, while the fifth is on a steep hillslope of hydrothermally altered rock on the east side. These results suggest that the ditch has altered the regime of debris flow activity in the Colorado River headwaters as compared to HRV by increasing the frequency of debris flows large enough to reach the Colorado River valley. Valley confinement is a dominant control on response to debris flows, influencing volumes of aggradation and persistence of debris flow deposits. Large, frequent debris flows, exceeding HRV, create persistent effects due to valley geometry and geomorphic setting conducive to sediment storage that are easily delineated by valley confinement ratios which are useful to land managers.

  15. Modeling Flood Inundation Induced by River Flow and Storm Surges over a River Basin

    Directory of Open Access Journals (Sweden)

    Wei-Bo Chen

    2014-10-01

    Full Text Available Low-lying coastal regions and their populations are at risk during storm surge events and high freshwater discharges from upriver. An integrated storm surge and flood inundation modeling system was used to simulate storm surge and inundation in the Tsengwen River basin and the adjacent coastal area in southern Taiwan. A three-dimensional hydrodynamic model with an unstructured grid was used, which was driven by the tidal elevation at the open boundaries and freshwater discharge at the upriver boundary. The model was validated against the observed water levels for three typhoon events. The simulation results for the model were in reasonable agreement with the observational data. The model was then applied to investigate the effects of a storm surge, freshwater discharge, and a storm surge combined with freshwater discharge during an extreme typhoon event. The super Typhoon Haiyan (2013 was artificially shifted to hit Taiwan: the modeling results showed that the inundation area and depth would cause severe overbank flow and coastal flooding for a 200 year return period flow. A high-resolution grid model is essential for the accurate simulation of storm surges and inundation.

  16. An analysis of river bank slope and unsaturated flow effects on bank storage.

    Science.gov (United States)

    Doble, Rebecca; Brunner, Philip; McCallum, James; Cook, Peter G

    2012-01-01

    Recognizing the underlying mechanisms of bank storage and return flow is important for understanding streamflow hydrographs. Analytical models have been widely used to estimate the impacts of bank storage, but are often based on assumptions of conditions that are rarely found in the field, such as vertical river banks and saturated flow. Numerical simulations of bank storage and return flow in river-aquifer cross sections with vertical and sloping banks were undertaken using a fully-coupled, surface-subsurface flow model. Sloping river banks were found to increase the bank infiltration rates by 98% and storage volume by 40% for a bank slope of 3.4° from horizontal, and for a slope of 8.5°, delay bank return flow by more than four times compared with vertical river banks and saturated flow. The results suggested that conventional analytical approximations cannot adequately be used to quantify bank storage when bank slope is less than 60° from horizontal. Additionally, in the unconfined aquifers modeled, the analytical solutions did not accurately model bank storage and return flow even in rivers with vertical banks due to a violation of the dupuit assumption. Bank storage and return flow were also modeled for more realistic cross sections and river hydrograph from the Fitzroy River, Western Australia, to indicate the importance of accurately modeling sloping river banks at a field scale. Following a single wet season flood event of 12 m, results showed that it may take over 3.5 years for 50% of the bank storage volume to return to the river. © 2011, The Author(s). Ground Water © 2011, National Ground Water Association.

  17. Monitoring and Evaluation of Environmental Flow Prescriptions for Five Demonstration Sites of the Sustainable Rivers Project

    Science.gov (United States)

    Konrad, Christopher P.

    2010-01-01

    The Nature Conservancy has been working with U.S. Army Corps of Engineers (Corps) through the Sustainable Rivers Project (SRP) to modify operations of dams to achieve ecological objectives in addition to meeting the authorized purposes of the dams. Modifications to dam operations are specified in terms of environmental flow prescriptions that quantify the magnitude, duration, frequency, and seasonal timing of releases to achieve specific ecological outcomes. Outcomes of environmental flow prescriptions implemented from 2002 to 2008 have been monitored and evaluated at demonstration sites in five rivers: Green River, Kentucky; Savannah River, Georgia/South Carolina; Bill Williams River, Arizona; Big Cypress Creek, Texas; and Middle Fork Willamette River, Oregon. Monitoring and evaluation have been accomplished through collaborative partnerships of federal and state agencies, universities, and nongovernmental organizations.

  18. Free surface profiles in river flows: Can standard energy-based gradually-varied flow computations be pursued?

    Science.gov (United States)

    Cantero, Francisco; Castro-Orgaz, Oscar; Garcia-Marín, Amanda; Ayuso, José Luis; Dey, Subhasish

    2015-10-01

    Is the energy equation for gradually-varied flow the best approximation for the free surface profile computations in river flows? Determination of flood inundation in rivers and natural waterways is based on the hydraulic computation of flow profiles. This is usually done using energy-based gradually-varied flow models, like HEC-RAS, that adopts a vertical division method for discharge prediction in compound channel sections. However, this discharge prediction method is not so accurate in the context of advancements over the last three decades. This paper firstly presents a study of the impact of discharge prediction on the gradually-varied flow computations by comparing thirteen different methods for compound channels, where both energy and momentum equations are applied. The discharge, velocity distribution coefficients, specific energy, momentum and flow profiles are determined. After the study of gradually-varied flow predictions, a new theory is developed to produce higher-order energy and momentum equations for rapidly-varied flow in compound channels. These generalized equations enable to describe the flow profiles with more generality than the gradually-varied flow computations. As an outcome, results of gradually-varied flow provide realistic conclusions for computations of flow in compound channels, showing that momentum-based models are in general more accurate; whereas the new theory developed for rapidly-varied flow opens a new research direction, so far not investigated in flows through compound channels.

  19. THE PECULIARITIES OF SEASONAL FLOW REGIME ON SMALL RIVERS FROM THE EASTERN APUSENI MOUNTAINS

    Directory of Open Access Journals (Sweden)

    SOROCOVSCHI V.

    2014-03-01

    Full Text Available Investigated region is overlapping the territory drained by tributaries of Someşul Mic and Arieş River and also the creeks collected by Mureş River between the mouth of Arieş and Geoagiu River. The study is based on processing and interpreting data from 24 gauging stations, of which 18 control surfaces basins below 150 km2. To highlight the features of seasonal flow regime we have considered three periods (1950-1967, 1950-2009 and 1970-2009. Thus, all rivers are recording a dominant flow during spring while the lowest annual average volume is related to winter season. Seasonal time variation of river flow was highlighted by analyzing the trends in the three periods using the variation coefficients.

  20. Effects of flow regulation and fragmentation by dams on riparian flora in boreal rivers

    International Nuclear Information System (INIS)

    Jansson, Roland

    2000-01-01

    The object of this thesis is to evaluate the effects of river regulation on riparian flora in boreal rivers, and to increase the understanding of the processes causing patterns in species diversity. Comparisons of free-flowing and regulated rivers showed that regulated rivers have fewer plant species and less plant cover per 200-m-stretch of river margin. Regulated river-margins were less species-rich compared to free-flowing rivers irrespective of the type of regulated water level regime, except for unimpounded reaches downstream of dams. Species with good dispersal capacity (wind-dispersed or long-floating species) were least affected by regulation, showing that the ability to recolonize after local extinction is an important character. The temporal development of river-margin vegetation in regulated rivers was studied by investigating differently-old reservoirs and impoundments. Plant-species richness along storage reservoirs increased during the first 30-40 years following damming, but declined thereafter. Both species richness and plant cover remained impoverished compared to free-flowing rivers about 70 years after regulation. Along run-of-river impoundments, plant species richness and cover peaked after 10-20 years. In the long run, riparian species richness was lower, but riparian species density did not differ, compared to free-flowing rivers. Dams fragment the riparian flora. Adjacent run-of-river impoundments developed different riparian floras, probably because dams are barriers to the dispersal of species with poor floating ability. This shows that dams disrupt the ecological continuity not only for the river channel, but also for the adjoining riparian corridor. The number of species and genera were similar between river margins along boreal free-flowing rivers in Europe and North America. The riparian floras shared few species but many genera and families. The regional species pools were similar-sized and composed of species with similar traits, and

  1. Evaluation of statistical and rainfall-runoff models for predicting historical daily streamflow time series in the Des Moines and Iowa River watersheds

    Science.gov (United States)

    Farmer, William H.; Knight, Rodney R.; Eash, David A.; Kasey J. Hutchinson,; Linhart, S. Mike; Christiansen, Daniel E.; Archfield, Stacey A.; Over, Thomas M.; Kiang, Julie E.

    2015-08-24

    Daily records of streamflow are essential to understanding hydrologic systems and managing the interactions between human and natural systems. Many watersheds and locations lack streamgages to provide accurate and reliable records of daily streamflow. In such ungaged watersheds, statistical tools and rainfall-runoff models are used to estimate daily streamflow. Previous work compared 19 different techniques for predicting daily streamflow records in the southeastern United States. Here, five of the better-performing methods are compared in a different hydroclimatic region of the United States, in Iowa. The methods fall into three classes: (1) drainage-area ratio methods, (2) nonlinear spatial interpolations using flow duration curves, and (3) mechanistic rainfall-runoff models. The first two classes are each applied with nearest-neighbor and map-correlated index streamgages. Using a threefold validation and robust rank-based evaluation, the methods are assessed for overall goodness of fit of the hydrograph of daily streamflow, the ability to reproduce a daily, no-fail storage-yield curve, and the ability to reproduce key streamflow statistics. As in the Southeast study, a nonlinear spatial interpolation of daily streamflow using flow duration curves is found to be a method with the best predictive accuracy. Comparisons with previous work in Iowa show that the accuracy of mechanistic models with at-site calibration is substantially degraded in the ungaged framework.

  2. Quantifying Km-scale Hydrological Exchange Flows under Dynamic Flows and Their Influences on River Corridor Biogeochemistry

    Science.gov (United States)

    Chen, X.; Song, X.; Shuai, P.; Hammond, G. E.; Ren, H.; Zachara, J. M.

    2017-12-01

    Hydrologic exchange flows (HEFs) in rivers play vital roles in watershed ecological and biogeochemical functions due to their strong capacity to attenuate contaminants and process significant quantities of carbon and nutrients. While most of existing HEF studies focus on headwater systems with the assumption of steady-state flow, there is lack of understanding of large-scale HEFs in high-order regulated rivers that experience high-frequency stage fluctuations. The large variability of HEFs is a result of interactions between spatial heterogeneity in hydrogeologic properties and temporal variation in river discharge induced by natural or anthropogenic perturbations. Our 9-year spatially distributed dataset (water elevation, specific conductance, and temperature) combined with mechanistic hydrobiogeochemical simulations have revealed complex spatial and temporal dynamics in km-scale HEFs and their significant impacts on contaminant plume mobility and hyporheic biogeochemical processes along the Hanford Reach. Extended multidirectional flow behaviors of unconfined, river corridor groundwater were observed hundreds of meters inland from the river shore resulting from discharge-dependent HEFs. An appropriately sized modeling domain to capture the impact of regional groundwater flow as well as knowledge of subsurface structures controlling intra-aquifer hydrologic connectivity were essential to realistically model transient storage in this large-scale river corridor. This work showed that both river water and mobile groundwater contaminants could serve as effective tracers of HEFs, thus providing valuable information for evaluating and validating the HEF models. Multimodal residence time distributions with long tails were resulted from the mixture of long and short exchange pathways, which consequently impact the carbon and nutrient cycling within the river corridor. Improved understanding of HEFs using integrated observational and modeling approaches sheds light on

  3. Monitoring winter flow conditions on the Ivishak River, Alaska : final report.

    Science.gov (United States)

    2017-09-01

    The Sagavanirktok River, a braided river on the Alaska North Slope, flows adjacent to the trans-Alaska pipeline for approximately 100 miles south of Prudhoe Bay. During an unprecedented flooding event in mid-May 2015, the pipeline was exposed in an a...

  4. The lower San Pedro River: hydrology and flow restoration for biodiversity conservation

    Science.gov (United States)

    Jeanmarie Haney

    2005-01-01

    The lower San Pedro River, downstream from Benson, is a nearly unfragmented habitat containing perennial flow reaches that support riparian vegetation that serve as “stepping stones” for migratory species. The Nature Conservancy has purchased farm properties and retired agricultural pumping along the lower river, based largely on results from hydrologic analyses...

  5. River flow regime and snow cover of the Pamir Alay (Central Asia) in a changing climate

    NARCIS (Netherlands)

    Chevallier, P.; Pouyaud, B.; Mojaisky, M.; Bolgov, M.; Olsson, O.; Bauer, M.; Froebrich, J.

    2014-01-01

    The Vakhsh and Pyandj rivers, main tributaries of the Amu Darya River in the mountainous region of the Pamir Alay, play an important role in the water resources of the Aral Sea basin (Central Asia). In this region, the glaciers and snow cover significantly influence the water cycle and flow regime,

  6. Identification of appropriate low flow forecast model for the Meuse River.

    NARCIS (Netherlands)

    Demirel, M.C.; Booij, Martijn J.; Cluckie, Ian; Chen, Yangbo; Babovic, Vladan; Konikow, Lenny; Mynett, Arthur; Demuth, Siegfried; Savic, Dragan A.

    2009-01-01

    This study investigates the selection of an appropriate low flow forecast model for the Meuse River based on the comparison of output uncertainties of different models. For this purpose, three data driven models have been developed for the Meuse River: a multivariate ARMAX model, a linear regression

  7. Statistical Characterization of River and Channel Network Formation in Intermittently Flowing Vortex Systems.

    Science.gov (United States)

    Olson, C. J.; Reichhardt, C.; Nori, F.

    1997-03-01

    Vortices moving in dirty superconductors can form intricate flow patterns, resembling fluid rivers, as they interact with the pinning landscape (F. Nori, Science 271), 1373 (1996).. Weaker pinning produces relatively straight nori>vortex channels, while stronger pinning results in the formation of one or more winding channels that carry all flow. This corresponds to a crossover from elastic flow to plastic flow as the pinning strength is increased. For several pinning parameters, we find the fractal dimension of the channels that form, the vortex trail density, the distance travelled by vortices as they pass through the sample, the branching ratio, the sinuosity, and the size distribution of the rivers, and we compare our rivers with physical rivers that follow Horton's laws.

  8. Short-term stream flow forecasting at Australian river sites using data-driven regression techniques

    CSIR Research Space (South Africa)

    Steyn, Melise

    2017-09-01

    Full Text Available This study proposes a computationally efficient solution to stream flow forecasting for river basins where historical time series data are available. Two data-driven modeling techniques are investigated, namely support vector regression...

  9. Rivers running deep : complex flow and morphology in the Mahakam River, Indonesia

    NARCIS (Netherlands)

    Vermeulen, B.

    2014-01-01

    Rivers in tropical regions often challenge our geomorphological understanding of fluvial systems. Hairpin bends, natural scours, bifurcate meander bends, tie channels and embayments in the river bank are a few examples of features ubiquitous in tropical rivers. Existing observation techniques

  10. Sele coastal plain flood risk due to wave storm and river flow interaction

    Science.gov (United States)

    Benassai, Guido; Aucelli, Pietro; Di Paola, Gianluigi; Della Morte, Renata; Cozzolino, Luca; Rizzo, Angela

    2016-04-01

    Wind waves, elevated water levels and river discharge can cause flooding in low-lying coastal areas, where the water level is the interaction between wave storm elevated water levels and river flow interaction. The factors driving the potential flood risk include weather conditions, river water stage and storm surge. These data are required to obtain inputs to run the hydrological model used to evaluate the water surface level during ordinary and extreme events regarding both the fluvial overflow and storm surge at the river mouth. In this paper we studied the interaction between the sea level variation and the river hydraulics in order to assess the location of the river floods in the Sele coastal plain. The wave data were acquired from the wave buoy of Ponza, while the water level data needed to assess the sea level variation were recorded by the tide gauge of Salerno. The water stages, river discharges and rating curves for Sele river were provided by Italian Hydrographic Service (Servizio Idrografico e Mareografico Nazionale, SIMN).We used the dataset of Albanella station (40°29'34.30"N, 15°00'44.30"E), located around 7 km from the river mouth. The extreme river discharges were evaluated through the Weibull equation, which were associated with their return period (TR). The steady state river water levels were evaluated through HEC-RAS 4.0 model, developed by Hydrologic Engineering Center (HEC) of the United States Army Corps of Engineers Hydrologic Engineering Center (USACE,2006). It is a well-known 1D model that computes water surface elevation (WSE) and velocity at discrete cross-sections by solving continuity, energy and flow resistance (e.g., Manning) equation. Data requirements for HEC-RAS include topographic information in the form of a series of cross-sections, friction parameter in the form of Manning's n values across each cross-section, and flow data including flow rates, flow change locations, and boundary conditions. For a steady state sub

  11. Comparative Analysis of River Flow Modelling by Using Supervised Learning Technique

    Science.gov (United States)

    Ismail, Shuhaida; Mohamad Pandiahi, Siraj; Shabri, Ani; Mustapha, Aida

    2018-04-01

    The goal of this research is to investigate the efficiency of three supervised learning algorithms for forecasting monthly river flow of the Indus River in Pakistan, spread over 550 square miles or 1800 square kilometres. The algorithms include the Least Square Support Vector Machine (LSSVM), Artificial Neural Network (ANN) and Wavelet Regression (WR). The forecasting models predict the monthly river flow obtained from the three models individually for river flow data and the accuracy of the all models were then compared against each other. The monthly river flow of the said river has been forecasted using these three models. The obtained results were compared and statistically analysed. Then, the results of this analytical comparison showed that LSSVM model is more precise in the monthly river flow forecasting. It was found that LSSVM has he higher r with the value of 0.934 compared to other models. This indicate that LSSVM is more accurate and efficient as compared to the ANN and WR model.

  12. Simple Model for Simulating Characteristics of River Flow Velocity in Large Scale

    Directory of Open Access Journals (Sweden)

    Husin Alatas

    2015-01-01

    Full Text Available We propose a simple computer based phenomenological model to simulate the characteristics of river flow velocity in large scale. We use shuttle radar tomography mission based digital elevation model in grid form to define the terrain of catchment area. The model relies on mass-momentum conservation law and modified equation of motion of falling body in inclined plane. We assume inelastic collision occurs at every junction of two river branches to describe the dynamics of merged flow velocity.

  13. Synthetic river flow time series generator for dispatch and spot price forecast

    International Nuclear Information System (INIS)

    Flores, R.A.

    2007-01-01

    Decision-making in electricity markets is complicated by uncertainties in demand growth, power supplies and fuel prices. In Peru, where the electrical power system is highly dependent on water resources at dams and river flows, hydrological uncertainties play a primary role in planning, price and dispatch forecast. This paper proposed a signal processing method for generating new synthetic river flow time series as a support for planning and spot market price forecasting. River flow time series are natural phenomena representing a continuous-time domain process. As an alternative synthetic representation of the original river flow time series, this proposed signal processing method preserves correlations, basic statistics and seasonality. It takes into account deterministic, periodic and non periodic components such as those due to the El Nino Southern Oscillation phenomenon. The new synthetic time series has many correlations with the original river flow time series, rendering it suitable for possible replacement of the classical method of sorting historical river flow time series. As a dispatch and planning approach to spot pricing, the proposed method offers higher accuracy modeling by decomposing the signal into deterministic, periodic, non periodic and stochastic sub signals. 4 refs., 4 tabs., 13 figs

  14. Transient Flow through an Unsaturated Levee Embankment during the 2011 Mississippi River Flood

    Science.gov (United States)

    Jafari, N.; Stark, T.; Vahedifard, F.; Cadigan, J.

    2017-12-01

    The Mississippi River and corresponding tributaries drain approximately 3.23 million km2 (1.25 million mi2) or the equivalent of 41% of the contiguous United States. Approximately 2,600 km ( 1,600 miles) of earthen levees presently protect major urban cities and agricultural land against the periodic Mississippi River floods within the Lower Mississippi River Valley. The 2011 flood also severely stressed the levees and highlighted the need to evaluate the behavior of levee embankments during high water levels. The performance of earthen levees is complex because of the uncertainties in construction materials, antecedent moisture contents, hydraulic properties, and lack of field monitoring. In particular, calibration of unsaturated and saturated soil properties of levee embankment and foundation layers along with the evaluation of phreatic surface during high river stage is lacking. Due to the formation of sand boils at the Duncan Point Levee in Baton Rouge, LA during the 2011 flood event, a reconnaissance survey was conducted to collect pore-water pressures in the sand foundation using piezometers and identifying the phreatic surface at the peak river level. Transient seepage analyses were performed to calibrate the foundation and levee embankment material properties using field data collected. With this calibrated levee model, numerical experiments were conducted to characterize the effects of rainfall intensity and duration, progression of phreatic surface, and seasonal climate variability prior to floods on the performance of the levee embankment. For example, elevated phreatic surface from river floods are maintained for several months and can be compounded with rainfall to lead to slope instability.

  15. Simulation of soil loss processes based on rainfall runoff and the time factor of governance in the Jialing River Watershed, China.

    Science.gov (United States)

    Wu, Lei; Long, Tian-Yu; Liu, Xia; Mmereki, Daniel

    2012-06-01

    Jialing River is the largest tributary in the catchment area of Three Gorges Reservoir, and it is also one of the important areas of sediment yield in the upper reaches of the Yangtze River. In recent years, significant changes of water and sediment characteristics have taken place. The "Long Control" Project implemented since 1989 had greatly changed the surface appearance of the Jialing River Watershed (JRW), and it had made the environments of the watershed sediment yield and sediment transport change significantly. In this research, the Revised Universal Soil Loss Equation was selected and used to predict the annual average amount of soil erosion for the special water and sediment environments in the JRW after the implementation of the "Long Control" Project, and then the rainfall-runoff modulus and the time factor of governance were both considered as dynamic factors, the dynamic sediment transport model was built for soil erosion monitoring and forecasting based on the average sediment yield model. According to the dynamic model, the spatial and temporal distribution of soil erosion amount and sediment transport amount of the JRW from 1990 to 2007 was simulated using geographic information system (GIS) technology and space-grid algorithm. Simulation results showed that the average relative error of sediment transport was less than 10% except for the extreme hydrological year. The relationship between water and sediment from 1990 to 2007 showed that sediment interception effects of the soil and water conservation projects were obvious: the annual average sediment discharge reduced from 145.3 to 35 million tons, the decrement of sediment amount was about 111 million tons, and decreasing amplitude was 76%; the sediment concentration was also decreased from 2.01 to 0.578 kg/m(3). These data are of great significance for the prediction and estimation of the future changing trends of sediment storage in the Three Gorges Reservoir and the particulate non

  16. Using a Population Model to Inform the Management of River Flows and Invasive Carp ( Cyprinus carpio)

    Science.gov (United States)

    Koehn, John D.; Todd, Charles R.; Zampatti, Brenton P.; Stuart, Ivor G.; Conallin, Anthony; Thwaites, Leigh; Ye, Qifeng

    2018-03-01

    Carp are a highly successful invasive fish species, now widespread, abundant and considered a pest in south-eastern Australia. To date, most management effort has been directed at reducing abundances of adult fish, with little consideration of population growth through reproduction. Environmental water allocations are now an important option for the rehabilitation of aquatic ecosystems, particularly in the Murray-Darling Basin. As carp respond to flows, there is concern that environmental watering may cause floodplain inundation and provide access to spawning habitats subsequently causing unwanted population increase. This is a management conundrum that needs to be carefully considered within the context of contemporary river flow management (natural, environmental, irrigation). This paper uses a population model to investigate flow-related carp population dynamics for three case studies in the Murray-Darling Basin: (1) river and terminal lakes; (2) wetlands and floodplain lakes; and (3) complex river channel and floodplain system. Results highlight distinctive outcomes depending on site characteristics. In particular, the terminal lakes maintain a significant source carp population regardless of river flow; hence any additional within-channel environmental flows are likely to have little impact on carp populations. In contrast, large-scale removal of carp from the lakes may be beneficial, especially in times of extended low river flows. Case studies 2 and 3 show how wetlands, floodplain lakes and the floodplain itself can now often be inundated for several months over the carp spawning season by high volume flows provided for irrigation or water transfers. Such inundations can be a major driver of carp populations, compared to within channel flows that have relatively little effecton recruitment. The use of a population model that incorporates river flows and different habitats for this flow-responsive species, allows for the comparison of likely population

  17. Experimental effect of flow depth on ratio discharge in lateral intakes in river bend

    International Nuclear Information System (INIS)

    Masjedi, A; Foroushani, E P

    2012-01-01

    Open-channel dividing flow is characterized by the inflow and outflow discharges, the upstream and downstream water depths, and the recirculation flow in the branch channel. In general, diversion flow can be categorized as natural and artificial flow. Natural flow diversion usually occurs as braiding or cut-off in bend rivers, while artificial flow is man-made to divert flow by lateral intake channels for water supply. This study presents the results of a laboratory research into effect intake flow depth on ratio discharge in lateral intakes in 180 degree bend. Investigation on lateral intake and determination of intake flow depth is among the most important issues in lateral intake on ratio discharge with model intake flow depth were measured in a laboratory flume under clear-water. Experiments were conducted for various intake flow depths and with different discharges. It was found that by increasing the flow depth at 180 degree flume bend, ratio discharge increases.

  18. Simulation of the effects of rainfall and groundwater use on historical lake water levels, groundwater levels, and spring flows in central Florida

    Science.gov (United States)

    O'Reilly, Andrew M.; Roehl, Edwin A.; Conrads, Paul; Daamen, Ruby C.; Petkewich, Matthew D.

    2014-01-01

    The urbanization of central Florida has progressed substantially in recent decades, and the total population in Lake, Orange, Osceola, Polk, and Seminole Counties more than quadrupled from 1960 to 2010. The Floridan aquifer system is the primary source of water for potable, industrial, and agricultural purposes in central Florida. Despite increases in groundwater withdrawals to meet the demand of population growth, recharge derived by infiltration of rainfall in the well-drained karst terrain of central Florida is the largest component of the long-term water balance of the Floridan aquifer system. To complement existing physics-based groundwater flow models, artificial neural networks and other data-mining techniques were used to simulate historical lake water level, groundwater level, and spring flow at sites throughout the area. Historical data were examined using descriptive statistics, cluster analysis, and other exploratory analysis techniques to assess their suitability for more intensive data-mining analysis. Linear trend analyses of meteorological data collected by the National Oceanic and Atmospheric Administration at 21 sites indicate 67 percent of sites exhibited upward trends in air temperature over at least a 45-year period of record, whereas 76 percent exhibited downward trends in rainfall over at least a 95-year period of record. Likewise, linear trend analyses of hydrologic response data, which have varied periods of record ranging in length from 10 to 79 years, indicate that water levels in lakes (307 sites) were about evenly split between upward and downward trends, whereas water levels in 69 percent of wells (out of 455 sites) and flows in 68 percent of springs (out of 19 sites) exhibited downward trends. Total groundwater use in the study area increased from about 250 million gallons per day (Mgal/d) in 1958 to about 590 Mgal/d in 1980 and remained relatively stable from 1981 to 2008, with a minimum of 559 Mgal/d in 1994 and a maximum of 773

  19. QUANTIFICATION OF INSTREAM FLOW NEEDS OF A WILD AND SCENIC RIVER FOR WATER RIGHTS LITIGATION.

    Science.gov (United States)

    Garn, Herbert S.

    1986-01-01

    The lower 4 miles of the Red River, a tributary of the Rio Grande in northern New Mexico, was designated as one of the 'instant' components of the National Wild and Scenic River System in 1968. Instream flow requirements were determined by several methods to quantify the claims made by the United States for a federal reserved water right under the Wild and Scenic Rivers Act. The scenic (aesthetic), recreational, and fish and wildlife values are the purposes for which instream flow requirements were claimed. Since water quality is related to these values, instream flows for waste transport and protection of water quality were also included in the claim. The U. S. Fish and Wildlife Service's Instream Flow Incremental Methodology was used to quantify the relationship between various flow regimes and fish habitat. Study results are discussed.

  20. Numerical simulation of runoff from extreme rainfall events in a mountain water catchment

    Directory of Open Access Journals (Sweden)

    J. Burguete

    2002-01-01

    Full Text Available A numerical model for unsteady shallow water flow over initially dry areas is applied to a case study in a small drainage area at the Spanish Ebro River basin. Several flood mitigation measures (reforestation, construction of a small reservoir and channelization are simulated in the model in order to compare different extreme rainfall-runoff scenarios.

  1. Impacts of impervious cover, water withdrawals, and climate change on river flows in the conterminous US

    Directory of Open Access Journals (Sweden)

    P. V. Caldwell

    2012-08-01

    Full Text Available Rivers are essential to aquatic ecosystem and societal sustainability, but are increasingly impacted by water withdrawals, land-use change, and climate change. The relative and cumulative effects of these stressors on continental river flows are relatively unknown. In this study, we used an integrated water balance and flow routing model to evaluate the impacts of impervious cover and water withdrawal on river flow across the conterminous US at the 8-digit Hydrologic Unit Code (HUC watershed scale. We then estimated the impacts of projected change in withdrawals, impervious cover, and climate under the B1 "Low" and A2 "High" emission scenarios on river flows by 2060. Our results suggest that compared to no impervious cover, 2010 levels of impervious cover increased river flows by 9.9% on average with larger impacts in and downstream of major metropolitan areas. In contrast, compared to no water withdrawals, 2005 withdrawals decreased river flows by 1.4% on average with larger impacts in heavily irrigated arid regions of Western US. By 2060, impacts of climate change were predicted to overwhelm the potential gain in river flow due to future changes in impervious cover and add to the potential reduction in river flows from withdrawals, decreasing mean annual river flows from 2010 levels by 16% on average. However, increases in impervious cover by 2060 may offset the impact of climate change during the growing season in some watersheds. Large water withdrawals will aggravate the predicted impact of climate change on river flows, particularly in the Western US. Predicted ecohydrological impacts of land cover, water withdrawal, and climate change will likely include alteration of the terrestrial water balance, stream channel habitat, riparian and aquatic community structure in snow-dominated basins, and fish and mussel extirpations in heavily impacted watersheds. These changes may also require new infrastructure to support increasing anthropogenic

  2. Flow regime effects on mature Populus fremontii (Fremont cottonwood) productivity on two contrasting dryland river floodplains

    Science.gov (United States)

    Andersen, Douglas C.

    2016-01-01

    I compared riparian cottonwood (Populus fremontii) productivity-discharge relationships in a relictual stand along the highly regulated Green River and in a naturally functioning stand along the unregulated Yampa River in semiarid northwest Colorado. I used multiple regression to model flow effects on annual basal area increment (BAI) from 1982 to 2011, after removing any autocorrelation present. Each BAI series was developed from 20 trees whose mean size (67 cm diameter at breast height [DBH]) was equivalent in the two stands. BAI was larger in the Yampa River stand except in 2 y when defoliating leaf beetles were present there. I found no evidence for a Yampa flood-magnitude threshold above which BAI declined. Flow variables explained ∼45% of residual BAI variability, with most explained by current-year maximum 90-d discharge (QM90) in the Yampa River stand and by a measure of the year-to-year change in QM90 in the Green River stand. The latter reflects a management-imposed ceiling on flood magnitude—Flaming Gorge Dam power plant capacity—infrequently exceeded during the study period. BAI in the relictual stand began to trend upward in 1992 when flows started to mimic a natural flow regime. Mature Fremont cottonwoods appear to be ecologically resilient. Their productivity along regulated rivers might be optimized using multiyear environmental flow designs.

  3. Integrated Analysis of Flow, Form, and Function for River Management and Design Testing

    Science.gov (United States)

    Lane, B. A. A.; Pasternack, G. B.; Sandoval Solis, S.

    2017-12-01

    Rivers are highly complex, dynamic systems that support numerous ecosystem functions including transporting sediment, modulating biogeochemical processes, and regulating habitat availability for native species. The extent and timing of these functions is largely controlled by the interplay of hydrologic dynamics (i.e. flow) and the shape and composition of the river corridor (i.e. form). This study applies synthetic channel design to the evaluation of river flow-form-function linkages, with the aim of evaluating these interactions across a range of flows and forms to inform process-driven management efforts with limited data and financial requirements. In an application to California's Mediterranean-montane streams, the interacting roles of channel form, water year type, and hydrologic impairment were evaluated across a suite of ecosystem functions related to hydrogeomorphic processes, aquatic habitat, and riparian habitat. Channel form acted as the dominant control on hydrogeomorphic processes considered, while water year type controlled salmonid habitat functions. Streamflow alteration for hydropower increased redd dewatering risk and altered aquatic habitat availability and riparian recruitment dynamics. Study results highlight critical tradeoffs in ecosystem function performance and emphasize the significance of spatiotemporal diversity of flow and form at multiple scales for maintaining river ecosystem integrity. The approach is broadly applicable and extensible to other systems and ecosystem functions, where findings can be used to characterize complex controls on river ecosystems, assess impacts of proposed flow and form alterations, and inform river restoration strategies.

  4. Forecasting of Average Monthly River Flows in Colombia

    Science.gov (United States)

    Mesa, O. J.; Poveda, G.

    2006-05-01

    The last two decades have witnessed a marked increase in our knowledge of the causes of interannual hydroclimatic variability and our ability to make predictions. Colombia, located near the seat of the ENSO phenomenon, has been shown to experience negative (positive) anomalies in precipitation in concert with El Niño (La Niña). In general besides the Pacific Ocean, Colombia has climatic influences from the Atlantic Ocean and the Caribbean Sea through the tropical forest of the Amazon basin and the savannas of the Orinoco River, in top of the orographic and hydro-climatic effects introduced by the Andes. As in various other countries of the region, hydro-electric power contributes a large proportion (75 %) of the total electricity generation in Colombia. Also, most agriculture is rain-fed dependant, and domestic water supply relies mainly on surface waters from creeks and rivers. Besides, various vector borne tropical diseases intensify in response to rain and temperature changes. Therefore, there is a direct connection between climatic fluctuations and national and regional economies. This talk specifically presents different forecasts of average monthly stream flows for the inflow into the largest reservoir used for hydropower generation in Colombia, and illustrates the potential economic savings of such forecasts. Because of planning of the reservoir operation, the most appropriated time scale for this application is the annual to interannual. Fortunately, this corresponds to the scale at which hydroclimate variability understanding has improved significantly. Among the different possibilities we have explored: traditional statistical ARIMA models, multiple linear regression, natural and constructed analogue models, the linear inverse model, neural network models, the non-parametric regression splines (MARS) model, regime dependant Markovian models and one we termed PREBEO, which is based on spectral bands decomposition using wavelets. Most of the methods make

  5. Stochastic modeling of hourly rainfall times series in Campania (Italy)

    Science.gov (United States)

    Giorgio, M.; Greco, R.

    2009-04-01

    Occurrence of flowslides and floods in small catchments is uneasy to predict, since it is affected by a number of variables, such as mechanical and hydraulic soil properties, slope morphology, vegetation coverage, rainfall spatial and temporal variability. Consequently, landslide risk assessment procedures and early warning systems still rely on simple empirical models based on correlation between recorded rainfall data and observed landslides and/or river discharges. Effectiveness of such systems could be improved by reliable quantitative rainfall prediction, which can allow gaining larger lead-times. Analysis of on-site recorded rainfall height time series represents the most effective approach for a reliable prediction of local temporal evolution of rainfall. Hydrological time series analysis is a widely studied field in hydrology, often carried out by means of autoregressive models, such as AR, ARMA, ARX, ARMAX (e.g. Salas [1992]). Such models gave the best results when applied to the analysis of autocorrelated hydrological time series, like river flow or level time series. Conversely, they are not able to model the behaviour of intermittent time series, like point rainfall height series usually are, especially when recorded with short sampling time intervals. More useful for this issue are the so-called DRIP (Disaggregated Rectangular Intensity Pulse) and NSRP (Neymann-Scott Rectangular Pulse) model [Heneker et al., 2001; Cowpertwait et al., 2002], usually adopted to generate synthetic point rainfall series. In this paper, the DRIP model approach is adopted, in which the sequence of rain storms and dry intervals constituting the structure of rainfall time series is modeled as an alternating renewal process. Final aim of the study is to provide a useful tool to implement an early warning system for hydrogeological risk management. Model calibration has been carried out with hourly rainfall hieght data provided by the rain gauges of Campania Region civil

  6. The impact of river-lake flow and sediment exchange on sediment scouring and siltation in middle and lower Yangtze River

    Science.gov (United States)

    Liu, Y.; Wang, Z. L.; Zuo, L. Q.

    2017-12-01

    The operation of TGR (Three Gorges Reservoir) caused river erosion and water level decline at downstream, which affects the water and sediment exchange of river-lake (Yangtze River - Dongting lake & Poyang lake). However, the change of river-lake relationship plays a significant role in the flow and sediment process of Yangtze River. In this study, flow diversion ratios of the three outlets, Chenglingji station, Hukou station are used as indexes of river-lake exchange to study the response of river erosion to flow diversion ratios. The results show that:(1) the sediment erosion in each reach from Yichang to Datong has linear correlation with the flow diversion ratio of the three outlets; (2) the sediment erosion above Chenglingji has negative linear correlation with the flow diversion ratio of Chenglingji station. While the sediment erosion below Chenglingji station has non-linear correlation with the flow diversion ratio variation of Chenglingji station; (3) the reach above Hankou station will not be affected by the flow diversion ratio of Hukou station. On one hand, if the flow diversion ratio is less than 10%, the correlation between sediment erosion and flow diversion ratio of Hukou station will be positive in Hankou to Hukou reach, but will be negative in Hukou to Datong reach. On the other hand, if the flow diversion ratio is more than 10%, the correlation will reverse.

  7. Ecosystem effects of environmental flows: Modelling and experimental floods in a dryland river

    Science.gov (United States)

    Shafroth, P.B.; Wilcox, A.C.; Lytle, D.A.; Hickey, J.T.; Andersen, D.C.; Beauchamp, Vanessa B.; Hautzinger, A.; McMullen, L.E.; Warner, A.

    2010-01-01

    Successful environmental flow prescriptions require an accurate understanding of the linkages among flow events, geomorphic processes and biotic responses. We describe models and results from experimental flow releases associated with an environmental flow program on the Bill Williams River (BWR), Arizona, in arid to semiarid western U.S.A. Two general approaches for improving knowledge and predictions of ecological responses to environmental flows are: (1) coupling physical system models to ecological responses and (2) clarifying empirical relationships between flow and ecological responses through implementation and monitoring of experimental flow releases. We modelled the BWR physical system using: (1) a reservoir operations model to simulate reservoir releases and reservoir water levels and estimate flow through the river system under a range of scenarios, (2) one- and two-dimensional river hydraulics models to estimate stage-discharge relationships at the whole-river and local scales, respectively, and (3) a groundwater model to estimate surface- and groundwater interactions in a large, alluvial valley on the BWR where surface flow is frequently absent. An example of a coupled, hydrology-ecology model is the Ecosystems Function Model, which we used to link a one-dimensional hydraulic model with riparian tree seedling establishment requirements to produce spatially explicit predictions of seedling recruitment locations in a Geographic Information System. We also quantified the effects of small experimental floods on the differential mortality of native and exotic riparian trees, on beaver dam integrity and distribution, and on the dynamics of differentially flow-adapted benthic macroinvertebrate groups. Results of model applications and experimental flow releases are contributing to adaptive flow management on the BWR and to the development of regional environmental flow standards. General themes that emerged from our work include the importance of response

  8. In situ measurements of post-fire debris flows in southern California: Comparisons of the timing and magnitude of 24 debris-flow events with rainfall and soil moisture conditions

    Science.gov (United States)

    Kean, J.W.; Staley, D.M.; Cannon, S.H.

    2011-01-01

    Debris flows often occur in burned steeplands of southern California, sometimes causing property damage and loss of life. In an effort to better understand the hydrologic controls on post-fire debris-flow initiation, timing and magnitude, we measured the flow stage, rainfall, channel bed pore fluid pressure and hillslope soil-moisture accompanying 24 debris flows recorded in five different watersheds burned in the 2009 Station and Jesusita Fires (San Gabriel and Santa Ynez Mountains). The measurements show substantial differences in debris-flow dynamics between sites and between sequential events at the same site. Despite these differences, the timing and magnitude of all events were consistently associated with local peaks in short duration (landslides. By identifying the storm characteristics most closely associated with post-fire debris flows, these measurements provide valuable guidance for warning operations and important constraints for developing and testing models of post-fire debris flows. copyright. 2011 by the American Geophysical Union.

  9. Flow-gauging structures in South African rivers Part 2: Calibration ...

    African Journals Online (AJOL)

    Accurate hydrological information is of paramount importance in a dry country such as South Africa. Flow measurements in rivers are complicated by the high variability of flows as well as by sediment loads and debris. It has been found necessary to modify and even substitute certain internationally accepted gauging station ...

  10. A modified hydrodynamic model for routing unsteady flow in a river having piedmont zone

    Directory of Open Access Journals (Sweden)

    Patowary Sudarshan

    2017-03-01

    Full Text Available Existence of piedmont zone in a river bed is a critical parameter from among numerous variations of topographical, geological and geographical conditions that can significantly influence the river flow scenario. Downstream flow situation assessed by routing of upstream hydrograph may yield higher flow depth if existence of such high infiltration zone is ignored and therefore it is a matter of concern for water resources planning and flood management. This work proposes a novel modified hydrodynamic model that has the potential to accurately determine the flow scenario in presence of piedmont zone. The model has been developed using unsteady free surface flow equations, coupled with Green-Ampt infiltration equation as governing equation. For solution of the governing equations Beam and Warming implicit finite difference scheme has been used. The proposed model was first validated from the field data of Trout Creek River showing excellent agreement. The validated model was then applied to a hypothetical river reach commensurate with the size of major tributaries of Brahmaputra Basin of India. Results indicated a 10% and 14% difference in the maximum value of discharge and depth hydrograph in presence and absence of piedmont zone respectively. Overall this model was successfully used to accurately predict the effect of piedmont zone on the unsteady flow in a river.

  11. Calculation of the Instream Ecological Flow of the Wei River Based on Hydrological Variation

    Directory of Open Access Journals (Sweden)

    Shengzhi Huang

    2014-01-01

    Full Text Available It is of great significance for the watershed management department to reasonably allocate water resources and ensure the sustainable development of river ecosystems. The greatly important issue is to accurately calculate instream ecological flow. In order to precisely compute instream ecological flow, flow variation is taken into account in this study. Moreover, the heuristic segmentation algorithm that is suitable to detect the mutation points of flow series is employed to identify the change points. Besides, based on the law of tolerance and ecological adaptation theory, the maximum instream ecological flow is calculated, which is the highest frequency of the monthly flow based on the GEV distribution and very suitable for healthy development of the river ecosystems. Furthermore, in order to guarantee the sustainable development of river ecosystems under some bad circumstances, minimum instream ecological flow is calculated by a modified Tennant method which is improved by replacing the average flow with the highest frequency of flow. Since the modified Tennant method is more suitable to reflect the law of flow, it has physical significance, and the calculation results are more reasonable.

  12. Prolonged river water pollution due to variable-density flow and solute transport in the riverbed

    Science.gov (United States)

    Jin, Guangqiu; Tang, Hongwu; Li, Ling; Barry, D. A.

    2015-04-01

    A laboratory experiment and numerical modeling were used to examine effects of density gradients on hyporheic flow and solute transport under the condition of a solute pulse input to a river with regular bed forms. Relatively low-density gradients due to an initial salt pulse concentration of 1.55 kg m-3 applied in the experiment were found to modulate significantly the pore-water flow and solute transport in the riverbed. Such density gradients increased downward flow and solute transport in the riverbed by factors up to 1.6. This resulted in a 12.2% increase in the total salt transfer from the water column to the riverbed over the salt pulse period. As the solute pulse passed, the effect of the density gradients reversed, slowing down the release of the solute back to the river water by a factor of 3.7. Numerical modeling indicated that these density effects intensified as salt concentrations in the water column increased. Simulations further showed that the density gradients might even lead to unstable flow and result in solute fingers in the bed of large bed forms. The slow release of solute from the bed back to the river led to a long tail of solute concentration in the river water. These findings have implications for assessment of impact of pollution events on river systems, in particular, long-term effects on both the river water and riverbed due to the hyporheic exchange.

  13. Precipitation estimates and comparison of satellite rainfall data to in situ rain gauge observations to further develop the watershed-modeling capabilities for the Lower Mekong River Basin

    Science.gov (United States)

    Dandridge, C.; Lakshmi, V.; Sutton, J. R. P.; Bolten, J. D.

    2017-12-01

    This study focuses on the lower region of the Mekong River Basin (MRB), an area including Burma, Cambodia, Vietnam, Laos, and Thailand. This region is home to expansive agriculture that relies heavily on annual precipitation over the basin for its prosperity. Annual precipitation amounts are regulated by the global monsoon system and therefore vary throughout the year. This research will lead to improved prediction of floods and management of floodwaters for the MRB. We compare different satellite estimates of precipitation to each other and to in-situ precipitation estimates for the Mekong River Basin. These comparisons will help us determine which satellite precipitation estimates are better at predicting precipitation in the MRB and will help further our understanding of watershed-modeling capabilities for the basin. In this study we use: 1) NOAA's PERSIANN daily 0.25° precipitation estimate Climate Data Record (CDR), 2) NASA's Tropical Rainfall Measuring Mission (TRMM) daily 0.25° estimate, and 3) NASA's Global Precipitation Measurement (GPM) daily 0.1 estimate and 4) 488 in-situ stations located in the lower MRB provide daily precipitation estimates. The PERSIANN CDR precipitation estimate was able to provide the longest data record because it is available from 1983 to present. The TRMM precipitation estimate is available from 2000 to present and the GPM precipitation estimates are available from 2015 to present. It is for this reason that we provide several comparisons between our precipitation estimates. Comparisons were done between each satellite product and the in-situ precipitation estimates based on geographical location and date using the entire available data record for each satellite product for daily, monthly, and yearly precipitation estimates. We found that monthly PERSIANN precipitation estimates were able to explain up to 90% of the variability in station precipitation depending on station location.

  14. River flow and riparian vegetation dynamics - implications for management of the Yampa River through Dinosaur National Monument

    Science.gov (United States)

    Scott, Michael L; Friedman, Jonathan M.

    2018-01-01

    This report addresses the relation between flow of the Yampa River and occurrence of herbaceous and woody riparian vegetation in Dinosaur National Monument (DINO) with the goal of informing management decisions related to potential future water development. The Yampa River in DINO flows through diverse valley settings, from the relatively broad restricted meanders of Deerlodge Park to narrower canyons, including debris fan-affected reaches in the upper Yampa Canyon and entrenched meanders in Harding Hole and Laddie Park. Analysis of occurrence of all plant species measured in 1470 quadrats by multiple authors over the last 24 years shows that riparian vegetation along the Yampa River is strongly related to valley setting and geomorphic surfaces, defined here as active channel, active floodplain, inactive floodplain, and upland. Principal Coordinates Ordination arrayed quadrats and species along gradients of overall cover and moisture availability, from upland and inactive floodplain quadrats and associated xeric species like western wheat grass (Pascopyrum smithii), cheatgrass (Bromus tectorum), and saltgrass (Distichlis spicata) to active channel and active floodplain quadrats supporting more mesic species including sandbar willow (Salix exigua), wild licorice (Glycyrrhiza lepidota), and cordgrass (Spartina spp.). Indicator species analysis identified plants strongly correlated with geomorphic surfaces. These species indicate state changes in geomorphic surfaces, such as the conversion of active channel to floodplain during channel narrowing. The dominant woody riparian species along the Yampa River are invasive tamarisk (Tamarix ramosissima), and native Fremont cottonwood (Populus deltoides ssp. wislizenii), box elder (Acer negundo L. var. interius), and sandbar willow (Salix exigua). These species differ in tolerance of drought, salinity, inundation, flood disturbance and shade, and in seed size, timing of seed dispersal and ability to form root sprouts. These

  15. Chronological trends in maximum and minimum water flows of the Teesta River, Bangladesh, and its implications

    Directory of Open Access Journals (Sweden)

    Md. Sanaul H. Mondal

    2017-03-01

    Full Text Available Bangladesh shares a common border with India in the west, north and east and with Myanmar in the southeast. These borders cut across 57 rivers that discharge through Bangladesh into the Bay of Bengal in the south. The upstream courses of these rivers traverse India, China, Nepal and Bhutan. Transboundary flows are the important sources of water resources in Bangladesh. Among the 57 transboundary rivers, the Teesta is the fourth major river in Bangladesh after the Ganges, the Brahmaputra and the Meghna and Bangladesh occupies about 2071 km2 . The Teesta River floodplain in Bangladesh accounts for 14% of the total cropped area and 9.15 million people of the country. The objective of this study was to investigate trends in both maximum and minimum water flow at Kaunia and Dalia stations for the Teesta River and the coping strategies developed by the communities to adjust with uncertain flood situations. The flow characteristics of the Teesta were analysed by calculating monthly maximum and minimum water levels and discharges from 1985 to 2006. Discharge of the Teesta over the last 22 years has been decreasing. Extreme low-flow conditions were likely to occur more frequently after the implementation of the Gozoldoba Barrage by India. However, a very sharp decrease in peak flows was also observed albeit unexpected high discharge in 1988, 1989, 1991, 1997, 1999 and 2004 with some in between April and October. Onrush of water causes frequent flash floods, whereas decreasing flow leaves the areas dependent on the Teesta vulnerable to droughts. Both these extreme situations had a negative impact on the lives and livelihoods of people dependent on the Teesta. Over the years, people have developed several risk mitigation strategies to adjust with both natural and anthropogenic flood situations. This article proposed the concept of ‘MAXIN (maximum and minimum flows’ for river water justice for riparian land.

  16. Electricity vs Ecosystems – understanding and predicting hydropower impact on Swedish river flow

    Directory of Open Access Journals (Sweden)

    B. Arheimer

    2014-09-01

    Full Text Available The most radical anthropogenic impact on water systems in Sweden originates from the years 1900–1970, when the electricity network was developed in the country and almost all rivers were regulated. The construction of dams and changes in water flow caused problems for ecosystems. Therefore, when implementing the EU Water Framework Directive (WFD hydro-morphological indicators and targets were developed for rivers and lakes to achieve good ecological potential. The hydrological regime is one such indicator. To understand the change in flow regime we quantified the hydropower impact on river flow across Sweden by using the S-HYPE model and observations. The results show that the average redistribution of water during a year due to regulation is 19 % for the total discharge from Sweden. A distinct impact was found in seasonal flow patterns and flow duration curves. Moreover, we quantified the model skills in predicting hydropower impact on flow. The median NSE for simulating change in flow regime was 0.71 for eight dams studied. Results from the spatially distributed model are available for 37 000 sub-basins across the country, and will be used by the Swedish water authorities for reporting hydro-morphological indicators to the EU and for guiding the allocation of river restoration measures.

  17. Applications of Coupled Explicit–Implicit Solution of SWEs for Unsteady Flow in Yangtze River

    Directory of Open Access Journals (Sweden)

    Yufei Ding

    2017-02-01

    Full Text Available In engineering practice, the unsteady flows generated from the operation of hydropower station in the upstream region could significantly change the navigation system of waterways located in the middle-lower reaches of the river. In order to study the complex propagation, convergence and superposition characteristics of unsteady flows in a long channel with flow confluence, a numerical model based on the coupling of implicit and explicit solution algorithms of Shallow Water Equations (SWEs has been applied to two large rivers in the reach of Yangtze River, China, which covers the distance from Yibin to Chongqing located upstream side of the Three Gorges Dam. The accuracy of numerical model has been validated by both the steady and unsteady flows using the prototype hydrological data. It is found that the unsteady flows show much more complex water level and discharge behaviors than the steady ones. The studied unsteady flows arising from the water regulation of two upstream hydropower stations could influence the region as far as Zhutuo hydrologic station, which is close to the city of Chongqing. Meanwhile, the computed stage–discharge rating curves at all observation stations demonstrate multi-value loop patterns because of the presence of additional water surface gradient. The present numerical model proves to be robust for simulating complex flows in very long engineering rivers up to 400 km.

  18. Influence of secondary flow on meandring of rivers

    NARCIS (Netherlands)

    Olesen, K.W.

    1982-01-01

    A linear stability analysis of the governing equations for the bed and flow topography in straight alluvial channels is treated. The flow is described by a horizontal two-dimensional model, but secondary flow due to curvature of the streamlines is included. Further more knowledge about secondary

  19. Contribution of wave-induced liquefaction in triggering hyperpycnal flows in Yellow River Estuary

    Science.gov (United States)

    Liu, X.; Jia, Y.

    2017-12-01

    Hyperpycnal flows, driven mainly by the gravity of near-bed negatively buoyant layers, are one of the most important processes for moving marine sediment across the earth. The issue of hyperpycnal flows existing in marine environment has drawn increasing scholars' attention since that was observed in situ off the Yellow River estuary in the 1980s. Most researches maintain that hyperpycnal flows in the Yellow River estuary are caused by the high-concentration sediments discharged from the Yellow River into sea, however, other mechanisms have been discounted since the sediment input from the river has been significantly changed due to climate and anthropogenic change. Here we demonstrate that wave-seabed interactions can generate hyperpycnal flows, without river input, by sediment flux convergence above an originally consolidated seabed. Using physical model experiments and multi-sensor field measurements, we characterize the composition-dependent liquefaction properties of the sediment due to wave-induced pore water pressure accumulation. This allows quantification of attenuation of sediment threshold velocity and critical shear stress (predominant variables in transport mechanics) during the liquefaction under waves. Parameterising the wave-seabed interactions in a new concept model shows that high waves propagating over the seabed sediment can act as a scarifier plough remoulding the seabed sediment. This contributes to marine hyperpycnal flows as the sediment is quickly resuspended under accumulating attenuation in strength. Therefore, the development of more integrative numerical models could supply realistic predictions of marine record in response to rising magnitude and frequency of storms.

  20. Assessment of environmental flow requirements for river basin planning in Zimbabwe

    Science.gov (United States)

    Mazvimavi, D.; Madamombe, E.; Makurira, H.

    There is a growing awareness and understanding of the need to allocate water along a river to maintain ecological processes that provide goods and services. Legislation in Zimbabwe requires water resources management plans to include the amount of water to be reserved for environmental purposes in each river basin. This paper aims to estimate the amount of water that should be reserved for environmental purposes in each of the 151 sub-basins or water management units of Zimbabwe. A desktop hydrological method is used to estimate the environmental flow requirement (EFR). The estimated EFRs decrease with increasing flow variability, and increase with the increasing contribution of base flows to total flows. The study has established that in order to maintain slightly modified to natural habitats along rivers, the EFR should be 30-60% of mean annual runoff (MAR) in regions with perennial rivers, while this is 20-30% in the dry parts of the country with rivers, which only flow during the wet season. The inclusion of EFRs in water resources management plans will not drastically change the proportion of the available water allocated to water permits, since the amount of water allocated to water permit holders is less than 50% of the MAR on 77% of the sub-basins in the country.

  1. Economic compensation standard for irrigation processes to safeguard environmental flows in the Yellow River Estuary, China

    Science.gov (United States)

    Pang, Aiping; Sun, Tao; Yang, Zhifeng

    2013-03-01

    SummaryAgriculture and ecosystems are increasingly competing for water. We propose an approach to assess the economic compensation standard required to release water from agricultural use to ecosystems while taking into account seasonal variability in river flow. First, we defined agricultural water shortage as the difference in water volume between agricultural demands and actual supply after maintaining environmental flows for ecosystems. Second, we developed a production loss model to establish the relationship between production losses and agricultural water shortages in view of seasonal variation in river discharge. Finally, we estimated the appropriate economic compensation for different irrigation stakeholders based on crop prices and production losses. A case study in the Yellow River Estuary, China, demonstrated that relatively stable economic compensation for irrigation processes can be defined based on the developed model, taking into account seasonal variations in river discharge and different levels of environmental flow. Annual economic compensation is not directly related to annual water shortage because of the temporal variability in river flow rate and environmental flow. Crops that have stable planting areas to guarantee food security should be selected as indicator crops in economic compensation assessments in the important grain production zone. Economic compensation may be implemented by creating funds to update water-saving measures in agricultural facilities.

  2. Simulated flow and solute transport, and mitigation of a hypothetical soluble-contaminant spill for the New River in the New River Gorge National River, West Virginia

    Science.gov (United States)

    Wiley, J.B.

    1993-01-01

    This report presents the results of a study by the U.S. Geological Survey (USGS), in cooperation with the National Park Service, to investigate the transport and factors affecting mitigation of a hypothetical spill of a soluble contaminant into the New River in the New River Gorge National River, West Virginia. The study reach, 53 miles of the lower New River between Hinton and Fayette, is characterized as a pool-and-riffle stream that becomes narrower, steeper, and deeper in the downstream direction. A USGS unsteady-flow model, DAFLOW (Diffusion Analogy FLOW), and a USGS solute-transport model, BLTM (Branch Lagrangian Transport Model), were applied to the study reach. Increases in discharge caused decreases in peak concentration and traveltime of peak concentration. Decreases in discharge caused increases in peak concentration and traveltime of peak concentration. This study indicated that the effects of an accidental spill could be mitigated by regulating discharge from Bluestone Dam. Knowledge of the chemical characteristics of the spill, location and time of the spill, and discharge of the river can aid in determining a mitigation response.

  3. Inferring the flood frequency distribution for an ungauged basin using a spatially distributed rainfall-runoff model

    Directory of Open Access Journals (Sweden)

    G. Moretti

    2008-08-01

    Full Text Available The estimation of the peak river flow for ungauged river sections is a topical issue in applied hydrology. Spatially distributed rainfall-runoff models can be a useful tool to this end, since they are potentially able to simulate the river flow at any location of the watershed drainage network. However, it is not fully clear to what extent these models can provide reliable simulations over a wide range of spatial scales. This issue is investigated here by applying a spatially distributed, continuous simulation rainfall-runoff model to infer the flood frequency distribution of the Riarbero River. This is an ungauged mountain creek located in northern Italy, whose drainage area is 17 km2. The hydrological model is first calibrated by using a 1-year record of hourly meteorological data and river flows observed at the outlet of the 1294 km2 wide Secchia River basin, of which the Riarbero is a tributary. The model is then validated by performing a 100-year long simulation of synthetic river flow data, which allowed us to compare the simulated and observed flood frequency distributions at the Secchia River outlet and the internal cross river section of Cavola Bridge, where the basin area is 337 km2. Finally, another simulation of hourly river flows was performed by referring to the outlet of the Riarbero River, therefore allowing us to estimate the related flood frequency distribution. The results were validated by using estimates of peak river flow obtained by applying hydrological similarity principles and a regional method. The results show that the flood flow estimated through the application of the distributed model is consistent with the estimate provided by the regional procedure as well as the behaviors of the river banks. Conversely, the method based on hydrological similarity delivers an estimate that seems to be not as reliable. The analysis highlights interesting perspectives for the application of

  4. Market Anatomy of a Drought: Modeling Barge and Corn Market Adaptation to Reduced Rainfall and Low Mississippi River Water Levels During the 2012 Midwestern U.S. Drought

    Science.gov (United States)

    Foster, B.; Characklis, G. W.; Thurman, W. N.

    2015-12-01

    In mid 2012, a severe drought swept across the Midwest, the heartland of corn production in the U.S. When the drought persisted into late Fall, corn markets were affected in two distinct ways: (1) reduced rainfall led to projected and actual corn yields that were lower than expected and (2) navigation restrictions, a result of low water levels on the Mississippi River, disrupted barge transportation, the most common and inexpensive mode for moving corn to many markets. Both (1) and (2) led to significant financial losses, but due to the complexity of the economic system and the coincidence of two different market impacts, the size of the role that low water levels played wass unclear. This is important, as losses related to low water levels are used to justify substantial investments in dredging activities on the Mississippi River. An "engineering" model of the system, suggests that low water levels should drive large increases in barge and corn prices, while some econometric models suggest that water levels explain very little of the changes in barge rates and corn prices. Employing a model that integrates both the engineering and economic elements of the system indicates that corn prices and barge rates during the drought display spatial and temporal behavior that is difficult to explain using either the engineering or econometric models alone. This integrated model accounts for geographic and temporal variations in drought impacts and identifies unique market responses to four different sets of conditions over the drought's length. Results illustrate that corn and barge price responses during the drought were a product of comingled, but distinct, reactions to both supply changes and navigation disruptions. Results also provide a more structured description of how the economic system that governs corn allocation interacts with the Mississippi River system during drought. As both public and private parties discuss potential managerial or infrastructural methods

  5. Flood-flow analysis for Kabul river at Warsak on the basis of flow-records of Kabul river at Nowshera

    International Nuclear Information System (INIS)

    Khan, B.

    2007-01-01

    High flows and stream discharge have long been measured and used by the engineers in the design of hydraulic structures and flood-protection works and in planning for flood-plain use. Probability-analysis is the basis for the engineering design of many projects and advance information about flood-forecasting. High-flow analysis or flood-frequency studies interpret a past record of events, to predict the future probability of occurrence. In many countries, including the author's country, the long term flow data required for design of hydraulic structures and flood-protection works are not available. In such cases, the only tool with hydrologists is to extend the short-term flow data available at some other site in the region. The present study is made to find a reliable estimation of maximum instantaneous flood for higher frequencies of Kabul River at Warsak weir. Kabul River, at Nowshera gaging station is used or the purpose and regression-analysis is performed to extend the instantaneous peak-flow record up to 29 years at Warsak. The frequency-curves of high-flows are plotted on the normal probability paper, using different probability distributions. The Gumbel distribution seemed to be the best fit for the observed data-points, and is used here for estimation of flood for different return periods. (author)

  6. Rainfall and runoff regime trends in mountain catchments (Case study area: the upper Hron River basin, Slovakia

    Directory of Open Access Journals (Sweden)

    Blahušiaková Andrea

    2015-09-01

    Full Text Available This paper presents an analysis of trends and causes of changes of selected hydroclimatic variables influencing the runoff regime in the upper Hron River basin (Slovakia. Different methods for identifying trends in data series are evaluated and include: simple mass curve analysis, linear regression, frequency analysis of flood events, use of the Indicators of Hydrological Alteration software, and the Mann-Kendall test. Analyses are performed for data from two periods (1931-2010 and 1961-2010. The changes in runoff are significant, especially in terms of lower QMax and 75 percentile values. This fact is also confirmed by the lower frequency and extremity of flood events. The 1980s are considered a turning point in the development of all hydroclimatic variables. The Mann-Kendall test shows a significant decrease in runoff in the winter period. The main causes of runoff decline are: the considerable increase in air temperature, the decrease in snow cover depth and changes in seasonal distribution of precipitation amounts.

  7. Bacteriological pollution indicators in Ogun River flowing through ...

    African Journals Online (AJOL)

    Water resources are significant part of integrated community development policy and good health. Hence, the need to reduce the impact of natural and anthropogenic pollution causes so as to enhance water quality. The bacteriological quality of the Ogun River was investigated to determine the sanitary conditions of the ...

  8. Establishing the environmental flow regime for the Middle Zambezi River

    NARCIS (Netherlands)

    Mwelwa-Mutekenya-Mwelwa, E.

    2016-01-01

    The Middle Zambezi, host to a rich biodiversity, is located in the central part of the Zambezi River Basin which covers eight Southern African Countries. The area is located downstream of three hydropower schemes. In the last decades, the floodplain riparian tree, the Faidherbia albida, vital for

  9. Establishing the Environmental Flow Regime for the Middle Zambezi River

    NARCIS (Netherlands)

    Mwelwa-Mutekenya, E.

    2016-01-01

    The Middle Zambezi, host to a rich biodiversity, is located in the central part of the Zambezi River Basin which covers eight Southern African Countries. The area is located downstream of three hydropower schemes. In the last decades, the floodplain riparian tree, the Faidherbia albida, vital for

  10. Flow status of three transboundary rivers in Northern Greece as a tool for hydro-diplomacy

    Science.gov (United States)

    Hatzigiannakis, Eyaggelos; Hatzispiroglou, Ioannis; Arampatzis, Georgios; Ilia, Andreas; Pantelakis, Dimitrios; Filintas, Agathos; Panagopoulos, Andreas

    2015-04-01

    The aim of this paper is to examine how the river flow monitoring consists a tool for hydro-diplomacy. Management of transboundary catchments and the demand of common water resources, often comprise the cause of conflicts and tension threatening the peaceful coexistence of nations. The Water Framework Directive 2000/60/EU sets a base for water management contributing to common approaches, common goals, common principles as well as providing new definitions and measures for Europe's water resources. In northern Greece the main renewable resources are "imported" (over 25% of its water reserves) and for this reason the implementation of continuous flow measurements throughout the year is necessary, even though difficult to achieve. This paper focuses on the three largest transboundary rivers in Northern Greece. Axios and Strymonas river flow across the region of Central Macedonia in Northern Greece. Axios flows from FYROM to Greece, and Strymonas from Bulgaria to Greece. Nestos river flows from Bulgaria to Greece. The Greek part is in the region of Eastern Macedonia and Thrace in Northern Greece. Significant productive agricultural areas around these rivers are irrigated from them so they are very important for the local society. Measurements of the river flow velocity and the flow depth have been made at bridges. The frequency of the measurements is roughly monthly, because it is expected a significant change in the depth flow and discharge. A series of continuously flow measure-ments were performed during 2013 and 2014 using flowmeters (Valeport and OTT type). The cross-section characteristics, the river flow velocity of segments and the mean water flow velocity and discharge total profile were measured and calculated re-spectively. Measurements are conducted in the framework of the national water resources monitoring network, which is realised in compliance to the Water Framework Directive under the supervision and coordination of the Hellenic Ministry for the

  11. Stream II-V5: Revision Of Stream II-V4 To Account For The Effects Of Rainfall Events

    International Nuclear Information System (INIS)

    Chen, K.

    2010-01-01

    STREAM II-V4 is the aqueous transport module currently used by the Savannah River Site emergency response Weather Information Display (WIND) system. The transport model of the Water Quality Analysis Simulation Program (WASP) was used by STREAM II to perform contaminant transport calculations. WASP5 is a US Environmental Protection Agency (EPA) water quality analysis program that simulates contaminant transport and fate through surface water. STREAM II-V4 predicts peak concentration and peak concentration arrival time at downstream locations for releases from the SRS facilities to the Savannah River. The input flows for STREAM II-V4 are derived from the historical flow records measured by the United States Geological Survey (USGS). The stream flow for STREAM II-V4 is fixed and the flow only varies with the month in which the releases are taking place. Therefore, the effects of flow surge due to a severe storm are not accounted for by STREAM II-V4. STREAM II-V4 has been revised to account for the effects of a storm event. The steps used in this method are: (1) generate rainfall hyetographs as a function of total rainfall in inches (or millimeters) and rainfall duration in hours; (2) generate watershed runoff flow based on the rainfall hyetographs from step 1; (3) calculate the variation of stream segment volume (cross section) as a function of flow from step 2; (4) implement the results from steps 2 and 3 into the STREAM II model. The revised model (STREAM II-V5) will find the proper stream inlet flow based on the total rainfall and rainfall duration as input by the user. STREAM II-V5 adjusts the stream segment volumes (cross sections) based on the stream inlet flow. The rainfall based stream flow and the adjusted stream segment volumes are then used for contaminant transport calculations.

  12. Forecasting models for flow and total dissolved solids in Karoun river-Iran

    Science.gov (United States)

    Salmani, Mohammad Hassan; Salmani Jajaei, Efat

    2016-04-01

    Water quality is one of the most important factors contributing to a healthy life. From the water quality management point of view, TDS (total dissolved solids) is the most important factor and many water developing plans have been implemented in recognition of this factor. However, these plans have not been perfect and very successful in overcoming the poor water quality problem, so there are a good volume of related studies in the literature. We study TDS and the water flow of the Karoun river in southwest Iran. We collected the necessary time series data from the Harmaleh station located in the river. We present two Univariate Seasonal Autoregressive Integrated Movement Average (ARIMA) models to forecast TDS and water flow in this river. Then, we build up a Transfer Function (TF) model to formulate the TDS as a function of water flow volume. A performance comparison between the Seasonal ARIMA and the TF models are presented.

  13. Analysis of trends of low flow in river stations in eastern Slovakia

    Directory of Open Access Journals (Sweden)

    Martina Zeleňáková

    2012-01-01

    Full Text Available The availability of using hypothesis test techniques to identify the long-term trends of hydrological time series is investigated in this study. The aim is to analyse trends of low flows at streams in eastern Slovakia, namely Poprad, Hornád, Bodva, Bodrog river basins. The article presents a methodology for prediction of hydrological drought based on statistical testing of low stream flows by non-parametric statistical test. The main objective is to identify low flow trends in the selected 63 river stations in eastern Slovakia. The stations with human impacts are also evaluated. The Mann-Kendall non-parametric test has been used to detect trends in hydrological time series. Statistically significant trends have been determined from the trend lines for the whole territory of eastern Slovakia. The results indicate that the observed changes in Slovakian river basins do not have a clearly defined trend.

  14. INFLUENCE OF RIVER BED ELEVATION SURVEY CONFIGURATIONS AND INTERPOLATION METHODS ON THE ACCURACY OF LIDAR DTM-BASED RIVER FLOW SIMULATIONS

    Directory of Open Access Journals (Sweden)

    J. R. Santillan

    2016-09-01

    Full Text Available In this paper, we investigated how survey configuration and the type of interpolation method can affect the accuracy of river flow simulations that utilize LIDAR DTM integrated with interpolated river bed as its main source of topographic information. Aside from determining the accuracy of the individually-generated river bed topographies, we also assessed the overall accuracy of the river flow simulations in terms of maximum flood depth and extent. Four survey configurations consisting of river bed elevation data points arranged as cross-section (XS, zig-zag (ZZ, river banks-centerline (RBCL, and river banks-centerline-zig-zag (RBCLZZ, and two interpolation methods (Inverse Distance-Weighted and Ordinary Kriging were considered. Major results show that the choice of survey configuration, rather than the interpolation method, has significant effect on the accuracy of interpolated river bed surfaces, and subsequently on the accuracy of river flow simulations. The RMSEs of the interpolated surfaces and the model results vary from one configuration to another, and depends on how each configuration evenly collects river bed elevation data points. The large RMSEs for the RBCL configuration and the low RMSEs for the XS configuration confirm that as the data points become evenly spaced and cover more portions of the river, the resulting interpolated surface and the river flow simulation where it was used also become more accurate. The XS configuration with Ordinary Kriging (OK as interpolation method provided the best river bed interpolation and river flow simulation results. The RBCL configuration, regardless of the interpolation algorithm used, resulted to least accurate river bed surfaces and simulation results. Based on the accuracy analysis, the use of XS configuration to collect river bed data points and applying the OK method to interpolate the river bed topography are the best methods to use to produce satisfactory river flow simulation outputs

  15. Sensitivity Modeling and Evaluation of Evapotranspiration Effects on Flow Discharge of River Owena in Nigeria

    Directory of Open Access Journals (Sweden)

    P.O Idogho

    2015-07-01

    Full Text Available Analysis of discharges, precipitation and temperature and some other meteorological-hydrological variables from 1996-2011 at the section of Owena River Basin. The evaluation, correlations, and the relationship between precipitation and discharge time series indicate a strong relationship. Minimum discharge values of 0.8 m 3 /s and 1.2 m 3 /s were observed in January and December and these values correspond to rainfall depth of 1.4 mm and 8.2 mm respectively. The average annual rainfall, river discharge were computed as 1,306.7 mm, 1,165 m 3 /s and mean temperature and evaporation of 31.1 oC and 4.6 mm. Evapotranspiration computation using pan evaporation model overestimated the evapotranspiration values by 0.5 mm and 0.21 mm over IHACRES and CROPWAT model for the total period of 15-year. Integration of the simulation outputs would be veritable in creating realistic-robust water management system for domestic and agricultural applications.

  16. Hydrochemical transformations of river waters during the flow in the reception basin on the basis of Olechówka River in Łódź

    Directory of Open Access Journals (Sweden)

    Bagrowicz Tomasz

    2017-01-01

    Full Text Available This work presents the results of the research experiment of conducting hydrochemical observation of the Olechówka River in Łódź and its flow from the river source until its estuary. The main aim of the research was to set tendencies of changes in waters flowing down from municipal reception basin with developed rain drain system and in waters flowing into bathing areas at the same time. Along with the flow of the river, 12 measuring-research points were established. In each of those points, measurements of the discharge rate and mean flow velocity of water in the channel were performed, which enabled to set average time of the flow of water between individual measuring-research points. The time of storing water in reservoirs was taken into consideration. The total time of the flow of water in the Olechówka River amounted to 856 h and 15 min. The analyses included in situ measurements (T, pH, SEC, analytical determinations Cl−, NH4+, NO3−, TN, PO43−, TP and Oxidability. The interchangeability of values of tested indicators and discharge point out to their decrease along with the increase of water flowing in the riverbed. There were self-cleaning processes identified in the Olechówka River: dilution and denitrification, along with the accumulation of total phosphorus in the river flow.

  17. Development of a stream–aquifer numerical flow model to assess river water management under water scarcity in a Mediterranean basin

    International Nuclear Information System (INIS)

    Mas-Pla, Josep; Font, Eva; Astui, Oihane; Menció, Anna; Rodríguez-Florit, Agustí; Folch, Albert; Brusi, David; Pérez-Paricio, Alfredo

    2012-01-01

    Stream flow, as a part of a basin hydrological cycle, will be sensible to water scarcity as a result of climate change. Stream vulnerability should then be evaluated as a key component of the basin water budget. Numerical flow modeling has been applied to an alluvial formation in a small mountain basin to evaluate the stream–aquifer relationship under these future scenarios. The Arbúcies River basin (116 km 2 ) is located in the Catalan Inner Basins (NE Spain) and its lower reach, which is related to an alluvial aquifer, usually becomes dry during the summer period. This study seeks to determine the origin of such discharge losses whether from natural stream leakage and/or induced capture due to groundwater withdrawal. Our goal is also investigating how discharge variations from the basin headwaters, representing potential effects of climate change, may affect stream flow, aquifer recharge, and finally environmental preservation and human supply. A numerical flow model of the alluvial aquifer, based on MODFLOW and especially in the STREAM routine, reproduced the flow system after the usual calibration. Results indicate that, in the average, stream flow provides more than 50% of the water inputs to the alluvial aquifer, being responsible for the amount of stored water resources and for satisfying groundwater exploitation for human needs. Detailed simulations using daily time-steps permit setting threshold values for the stream flow entering at the beginning of the studied area so surface discharge is maintained along the whole watercourse and ecological flow requirements are satisfied as well. The effects of predicted rainfall and temperature variations on the Arbúcies River alluvial aquifer water balance are also discussed from the outcomes of the simulations. Finally, model results indicate the relevance of headwater discharge management under future climate scenarios to preserve downstream hydrological processes. They also point out that small mountain basins

  18. Cascading effects of flow reduction on the benthic invertebrate community in a lowland river

    DEFF Research Database (Denmark)

    Graeber, Daniel; Pusch, Martin T.; Lorenz, Stefan

    2013-01-01

    on dissolved oxygen concentrations (DO) have not yet received much attention. We compared the macroinvertebrate composition between reference conditions and a situation after several years of discharge reduction in the Spree River (Brandenburg, Germany). Community composition shifted from rheophilic species...... concentration minima of less than 5 mg l−1 which prevailed 74% of the days in summer. This depletion of DO after flow reduction presumably caused the observed species turnover. Hence, flow reduction in lowland rivers may not only directly impair the ecological functions provided by benthic macroinvertebrates...

  19. ECTOPARASITIC TREMATODES ON Scardinius erythrophthalmus FROM THE LOWER FLOW OF THE SAVA RIVER

    Directory of Open Access Journals (Sweden)

    Zlatko Nedić

    2014-12-01

    Full Text Available The research on ectoparasitic trematodes on Scardinius erythrophthalmus from the lower flow of the Sava River showed three species of trematodes, which parasitized on the fish gills and fish skin. During the study period, we sampled 120 individuals of Scardinius erythrophthalmus. In total, 85 individuals or more than 70% showed the presence of one of the three types of ectoparasitic trematodes. Determination of the trematodes was done to the species level for one species (Posthodiplosomum cuticola and to the genus level for two of them (Dactylogyrus and Gyrodactylus. Key words: Sava River, lower flow, Orašje, ectoparasitictrematodes

  20. Low flow characteristics of river Notwane at Gaborone Dam ...

    African Journals Online (AJOL)

    ... dam has been undertaken using daily flow records between 1979 and 1999 to determine the magnitude of annual maximum deficit volumes and deficit durations at a threshold level equivalent to 75 % dependable flow. Statistical modeling of these annual maximum values, separately, using a PWM/L-moment procedure, ...

  1. DNA capture reveals transoceanic gene flow in endangered river sharks

    OpenAIRE

    Li, Chenhong; Corrigan, Shannon; Yang, Lei; Straube, Nicolas; Harris, Mark; Hofreiter, Michael; White, William T.; Naylor, Gavin J. P.

    2015-01-01

    The river sharks of the genus Glyphis, widely feared as man-eaters throughout India, remain very poorly known to science. The group constitutes five described species, all of which are considered highly endangered and restricted to freshwater systems in Australasia and Southeast Asia. DNA sequence data derived from 19th-century dried museum material augmented with contemporary samples indicates that only three of the five currently described species are valid; that there is a genetically dist...

  2. The river as a chemostat: fresh perspectives on dissolved organic matter flowing down the river continuum

    Science.gov (United States)

    Creed, Irena F.; McKnight, Diane M.; Pellerin, Brian; Green, Mark B.; Bergamaschi, Brian; Aiken, George R.; Burns, Douglas A.; Findlay, Stuart E G; Shanley, James B.; Striegl, Robert G.; Aulenbach, Brent T.; Clow, David W.; Laudon, Hjalmar; McGlynn, Brian L.; McGuire, Kevin J.; Smith, Richard A.; Stackpoole, Sarah M.

    2015-01-01

    A better understanding is needed of how hydrological and biogeochemical processes control dissolved organic carbon (DOC) concentrations and dissolved organic matter (DOM) composition from headwaters downstream to large rivers. We examined a large DOM dataset from the National Water Information System of the US Geological Survey, which represents approximately 100 000 measurements of DOC concentration and DOM composition at many sites along rivers across the United States. Application of quantile regression revealed a tendency towards downstream spatial and temporal homogenization of DOC concentrations and a shift from dominance of aromatic DOM in headwaters to more aliphatic DOM downstream. The DOC concentration–discharge (C-Q) relationships at each site revealed a downstream tendency towards a slope of zero. We propose that despite complexities in river networks that have driven many revisions to the River Continuum Concept, rivers show a tendency towards chemostasis (C-Q slope of zero) because of a downstream shift from a dominance of hydrologic drivers that connect terrestrial DOM sources to streams in the headwaters towards a dominance of instream and near-stream biogeochemical processes that result in preferential losses of aromatic DOM and preferential gains of aliphatic DOM.

  3. Hydrological model calibration for flood prediction in current and future climates using probability distributions of observed peak flows and model based rainfall

    Science.gov (United States)

    Haberlandt, Uwe; Wallner, Markus; Radtke, Imke

    2013-04-01

    Derived flood frequency analysis based on continuous hydrological modelling is very demanding regarding the required length and temporal resolution of precipitation input data. Often such flood predictions are obtained using long precipitation time series from stochastic approaches or from regional climate models as input. However, the calibration of the hydrological model is usually done using short time series of observed data. This inconsistent employment of different data types for calibration and application of a hydrological model increases its uncertainty. Here, it is proposed to calibrate a hydrological model directly on probability distributions of observed peak flows using model based rainfall in line with its later application. Two examples are given to illustrate the idea. The first one deals with classical derived flood frequency analysis using input data from an hourly stochastic rainfall model. The second one concerns a climate impact analysis using hourly precipitation from a regional climate model. The results show that: (I) the same type of precipitation input data should be used for calibration and application of the hydrological model, (II) a model calibrated on extreme conditions works quite well for average conditions but not vice versa, (III) the calibration of the hydrological model using regional climate model data works as an implicit bias correction method and (IV) the best performance for flood estimation is usually obtained when model based precipitation and observed probability distribution of peak flows are used for model calibration.

  4. Measurement of flows for two irrigation districts in the lower Colorado River basin, Texas

    Science.gov (United States)

    Coplin, L.S.; Liscum, Fred; East, J.W.; Goldstein, L.B.

    1996-01-01

    The Lower Colorado River Authority sells and distributes water for irrigation of rice farms in two irrigation districts, the Lakeside district and the Gulf Coast district, in the lower Colorado River Basin of Texas. In 1993, the Lower Colorado River Authority implemented a water-measurement program to account for the water delivered to rice farms and to promote water conservation. During the rice-irrigation season (summer and fall) of 1995, the U.S. Geological Survey measured flows at 30 sites in the Lakeside district and 24 sites in the Gulf Coast district coincident with Lower Colorado River Authority measuring sites. In each district, the Survey made essentially simultaneous flow measurements with different types of meters twice a day once in the morning and once in the afternoon at each site on selected days for comparison with Lower Colorado River Authority measurements. One-hundred pairs of corresponding (same site, same date) Lower Colorado River Authority and U.S. Geological Survey measurements from the Lakeside district and 104 measurement pairs from the Gulf Coast district are compared statistically and graphically. For comparison, the measurement pairs are grouped by irrigation district and further subdivided by the time difference between corresponding measurements less than or equal to 1 hour or more than 1 hour. Wilcoxon signed-rank tests (to indicate whether two groups of paired observations are statistically different) on Lakeside district measurement pairs with 1 hour or less between measurements indicate that the Lower Colorado River Authority and U.S. Geological Survey measurements are not statistically different. The median absolute percent difference between the flow measurements is 5.9 percent; and 33 percent of the flow measurements differ by more than 10 percent. Similar statistical tests on Gulf Coast district measurement pairs with 1 hour or less between measurements indicate that the Lower Colorado River Authority and U.S. Geological

  5. 3-D flow and scour near a submerged wing dike: ADCP measurements on the Missouri River

    Science.gov (United States)

    Jamieson, E.C.; Rennie, C.D.; Jacobson, R.B.; Townsend, R.D.

    2011-01-01

    Detailed mapping of bathymetry and three-dimensional water velocities using a boat-mounted single-beam sonar and acoustic Doppler current profiler (ADCP) was carried out in the vicinity of two submerged wing dikes located in the Lower Missouri River near Columbia, Missouri. During high spring flows the wing dikes become submerged, creating a unique combination of vertical flow separation and overtopping (plunging) flow conditions, causing large-scale three-dimensional turbulent flow structures to form. On three different days and for a range of discharges, sampling transects at 5 and 20 m spacing were completed, covering the area adjacent to and upstream and downstream from two different wing dikes. The objectives of this research are to evaluate whether an ADCP can identify and measure large-scale flow features such as recirculating flow and vortex shedding that develop in the vicinity of a submerged wing dike; and whether or not moving-boat (single-transect) data are sufficient for resolving complex three-dimensional flow fields. Results indicate that spatial averaging from multiple nearby single transects may be more representative of an inherently complex (temporally and spatially variable) three-dimensional flow field than repeated single transects. Results also indicate a correspondence between the location of calculated vortex cores (resolved from the interpolated three-dimensional flow field) and the nearby scour holes, providing new insight into the connections between vertically oriented coherent structures and local scour, with the unique perspective of flow and morphology in a large river.

  6. As long as the rivers flow: Athabasca River knowledge, use and change

    International Nuclear Information System (INIS)

    Candler, C.; Olson, R.; Deroy, S.

    2010-11-01

    This document is a report supported by specific information gathered by the Athabasca Chipewyan First Nation (ACFN) and the Mikisew Cree First Nation (MCFN), and takes part in an Athabasca River Use and Traditional Ecological Knowledge (TEK) study conducted in 2010. The main objective was to provide a written submission, based on evidence, in order to effectively notify the crown about plans for managing industrial water withdrawals from the lower Athabasca River. The First Nations used the same methods, wrote their community reports as distinguished stand-alone documents and made the choice to present the ACFN and MCFN data in parallel with each other within the same document. The study provides information on the knowledge and uses of the Athabasca River by the community members. Context and background for the study can be found in the part A. It comprises a short discussion of the Treaty No.8 of 1899, the latter confirming the rights of First Nation people. The importance of boat transportation for the community members is mentioned, and a summary of the methods is given. The results of the ACFN and MCFN studies are given in part B and C. The reduction of the quantity and quality of the river has affected the practice of ACFN and MCFN aboriginal and treaty rights. The community perceptions of the changes of the river and how it has influenced their lifestyle is discussed. Some uses of the Athabasca river have been lost because of concerns regarding contamination associated with oil sands operations. The last part of the document provides an analysis of results and suggests two thresholds that define the ability of ACFN and MCFN members to practice their rights and access their territories. This document ends with recommendations for implementation of these thresholds. 22 refs., 12 maps.

  7. As long as the rivers flow: Athabasca River knowledge, use and change

    Energy Technology Data Exchange (ETDEWEB)

    Candler, C.; Olson, R.; Deroy, S. [Firelight Group Research Cooperative, Victoria, BC (Canada)

    2010-11-15

    This document is a report supported by specific information gathered by the Athabasca Chipewyan First Nation (ACFN) and the Mikisew Cree First Nation (MCFN), and takes part in an Athabasca River Use and Traditional Ecological Knowledge (TEK) study conducted in 2010. The main objective was to provide a written submission, based on evidence, in order to effectively notify the crown about plans for managing industrial water withdrawals from the lower Athabasca River. The First Nations used the same methods, wrote their community reports as distinguished stand-alone documents and made the choice to present the ACFN and MCFN data in parallel with each other within the same document. The study provides information on the knowledge and uses of the Athabasca River by the community members. Context and background for the study can be found in the part A. It comprises a short discussion of the Treaty No.8 of 1899, the latter confirming the rights of First Nation people. The importance of boat transportation for the community members is mentioned, and a summary of the methods is given. The results of the ACFN and MCFN studies are given in part B and C. The reduction of the quantity and quality of the river has affected the practice of ACFN and MCFN aboriginal and treaty rights. The community perceptions of the changes of the river and how it has influenced their lifestyle is discussed. Some uses of the Athabasca river have been lost because of concerns regarding contamination associated with oil sands operations. The last part of the document provides an analysis of results and suggests two thresholds that define the ability of ACFN and MCFN members to practice their rights and access their territories. This document ends with recommendations for implementation of these thresholds. 22 refs., 12 maps.

  8. Preliminary synthesis and assessment of environmental flows in the middle Verde River watershed, Arizona

    Science.gov (United States)

    Paretti, Nicholas; Brasher, Anne M. D.; Pearlstein, Susanna L.; Skow, Dena M.; Gungle, Bruce W.; Garner, Bradley D.

    2018-05-15

    A 3-year study was undertaken to evaluate the suitability of the available modeling tools for characterizing environmental flows in the middle Verde River watershed of central Arizona, describe riparian vegetation throughout the watershed, and estimate sediment mobilization in the river. Existing data on fish and macroinvertebrates were analyzed in relation to basin characteristics, flow regimes, and microhabitat, and a pilot study was conducted that sampled fish and macroinvertebrates and the microhabitats in which they were found. The sampling for the pilot study took place at five different locations in the middle Verde River watershed. This report presents the results of this 3-year study. The Northern Arizona Groundwater Flow Model (NARGFM) was found to be capable of predicting long-term changes caused by alteration of regional recharge (such as may result from climate variability) and groundwater pumping in gaining, losing, and dry reaches of the major streams in the middle Verde River watershed. Over the period 1910 to 2006, the model simulated an increase in dry reaches, a small increase in reaches losing discharge to the groundwater aquifer, and a concurrent decrease in reaches gaining discharge from groundwater. Although evaluations of the suitability of using the NARGFM and Basin Characteristic Model to characterize various streamflow intervals showed that smallerscale basin monthly runoff could be estimated adequately at locations of interest, monthly stream-flow estimates were found unsatisfactory for determining environmental flows.Orthoimagery and Moderate Resolution Imaging Spectroradiometer data were used to quantify stream and riparian vegetation properties related to biotic habitat. The relative abundance of riparian vegetation varied along the main channel of the Verde River. As would be expected, more upland plant species and fewer lowland species were found in the upper-middle section compared to the lower-middle section, and vice

  9. Forecasting Shaharchay River Flow in Lake Urmia Basin using Genetic Programming and M5 Model Tree

    Directory of Open Access Journals (Sweden)

    S. Samadianfard

    2017-01-01

    Full Text Available Introduction: Precise prediction of river flows is the key factor for proper planning and management of water resources. Thus, obtaining the reliable methods for predicting river flows has great importance in water resource engineering. In the recent years, applications of intelligent methods such as artificial neural networks, fuzzy systems and genetic programming in water science and engineering have been grown extensively. These mentioned methods are able to model nonlinear process of river flows without any need to geometric properties. A huge number of studies have been reported in the field of using intelligent methods in water resource engineering. For example, Noorani and Salehi (23 presented a model for predicting runoff in Lighvan basin using adaptive neuro-fuzzy network and compared the performance of it with neural network and fuzzy inference methods in east Azerbaijan, Iran. Nabizadeh et al. (21 used fuzzy inference system and adaptive neuro-fuzzy inference system in order to predict river flow in Lighvan river. Khalili et al. (13 proposed a BL-ARCH method for prediction of flows in Shaharchay River in Urmia. Khu et al. (16 used genetic programming for runoff prediction in Orgeval catchment in France. Firat and Gungor (11 evaluated the fuzzy-neural model for predicting Mendes river flow in Turkey. The goal of present study is comparing the performance of genetic programming and M5 model trees for prediction of Shaharchay river flow in the basin of Lake Urmia and obtaining a comprehensive insight of their abilities. Materials and Methods: Shaharchay river as a main source of providing drinking water of Urmia city and agricultural needs of surrounding lands and finally one of the main input sources of Lake Urmia is quite important in the region. For obtaining the predetermined goals of present study, average monthly flows of Shaharchay River in Band hydrometric station has been gathered from 1951 to 2011. Then, two third of mentioned

  10. SOUTH-WESTERN APUSENI MOUNTAINS SMALL RIVERS SEASONAL HYDROLOGICAL FLOW REGIME

    Directory of Open Access Journals (Sweden)

    SOROCOVSCHI V.

    2015-03-01

    Full Text Available The researched area overlaps the territory belonging to Crişul Alb and Crişul Negru river basins. The study is based on processing and interpretation data from 33 hydrometric stations of which 18 stations control hydrographic basins with surfaces of less than 150 km2. To highlight the seasonal hydrological flow regime, we took into account three time periods (1950-1967, 1950-2009 and 1970-2009. For all rivers the highest flow values appear during springtime, while the smallest contribution to the multiannual average volume is realized in autumn. The time variation of seasonal flow was highlighted by analysis and variation of extreme values coefficients and also by analysing seasonal flow trends that appeared in all three time periods.

  11. An analysis of effect of land use change on river flow variability

    Science.gov (United States)

    Zhang, Tao; Liu, Yuting; Yang, Xinyue; Wang, Xiang

    2018-02-01

    Land use scenario analysis, SWAT model, flow characteristic indices and flow variability technology were used to analyze the effect of land use quantity and location change on river flow. Results showed that river flow variation caused by land use change from forest to crop was larger than that caused by land use change from forest to grass; Land use change neither from upstream to downstream nor from downstream to upstream had little effect on annual average discharge and maximum annual average discharge. But it had obvious effect on maximum daily discharge; Land use change which occurred in upstream could lead to producing larger magnitude flood more easily; Land use change from forest to crop or grass could increase the number of large magnitude floods and their total duration. And it also could increase the number of small magnitude floods but decrease their duration.

  12. Flow structure through pool-riffle sequences and a conceptual model for their sustainability in gravel-bed rivers

    Science.gov (United States)

    D. Caamano; P. Goodwin; J. M. Buffington

    2010-01-01

    Detailed field measurements and simulations of three-dimensional flow structure were used to develop a conceptual model to explain the sustainability of self-formed pool-riffle sequences in gravel-bed rivers. The analysis was conducted at the Red River Wildlife Management Area in Idaho, USA, and enabled characterization of the flow structure through two consecutive...

  13. An ecological economic assessment of flow regimes in a hydropower dominated river basin: the case of the lower Zambezi River, Mozambique.

    Science.gov (United States)

    Fanaian, Safa; Graas, Susan; Jiang, Yong; van der Zaag, Pieter

    2015-02-01

    The flow regime of rivers, being an integral part of aquatic ecosystems, provides many important services benefiting humans in catchments. Past water resource developments characterized by river embankments and dams, however, were often dominated by one (or few) economic use(s) of water. This results in a dramatically changed flow regime negatively affecting the provision of other ecosystem services sustained by the river flow. This study is intended to demonstrate the value of alternative flow regimes in a river that is highly modified by the presence of large hydropower dams and reservoirs, explicitly accounting for a broad range of flow-dependent ecosystem services. In this study, we propose a holistic approach for conducting an ecological economic assessment of a river's flow regime. This integrates recent advances in the conceptualization and classification of ecosystem services (UK NEA, 2011) with the flow regime evaluation technique developed by Korsgaard (2006). This integrated approach allows for a systematic comparison of the economic values of alternative flow regimes, including those that are considered beneficial for aquatic ecosystems. As an illustration, we applied this combined approach to the Lower Zambezi Basin, Mozambique. Empirical analysis shows that even though re-operating dams to create environmentally friendly flow regimes reduces hydropower benefits, the gains to goods derived from the aquatic ecosystem may offset the forgone hydropower benefits, thereby increasing the total economic value of river flow to society. The proposed integrated flow assessment approach can be a useful tool for welfare-improving decision-making in managing river basins. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. Sedimentary Records of Hyperpycnal Flows and the Influence of River Damming on Sediment Dynamics of Estuaries: Examples from the Nelson, Churchill, Moisie and Sainte-Marguerite Rivers (Canada)

    Science.gov (United States)

    St-Onge, G.; Duboc, Q.; Boyer-Villemaire, U.; Lajeunesse, P.; Bernatchez, P.

    2015-12-01

    Sediment cores were sampled in the estuary of the Nelson and Churchill Rivers in western Hudson Bay, as well as in the estuary of the Moisie and Sainte-Marguerite Rivers in Gulf of St. Lawrence in order to evaluate the impact of hydroelectric dams on the sedimentary regime of these estuaries. The gravity cores at the mouth of the Nelson River recorded several cm-thick rapidly deposited layers with a reverse to normal grading sequence, indicating the occurrence of hyperpycnal flows generated by major floods during the last few centuries. These hyperpycnal flows were probably caused by ice-jam formation, which can increase both the flow and the sediment concentration following the breaching of such natural dams. Following the construction of hydroelectric dams since the 1960s, the regulation of river discharge prevented the formation of hyperpycnal flows, and hence the deposition of hyperpycnites in the upper part of the cores. In the core sampled in the estuary of the Churchill River, only one hyperpycnite was recorded. This lower frequency may be due to the enclosed estuary of the Churchill River, its weaker discharge and the more distal location of the coring site.In the Gulf of St. Lawrence, grain size measurements allowed the identification of a major flood around AD 1844±4 years in box cores from both the Sainte-Marguerite and Moisie Rivers, whereas a drastic decrease in variations in the median grain size occurred around AD ~1900 in the estuary of the Sainte-Marguerite River, highlighting the offshore impact of the SM1 dam construction in the early 1900s. Furthermore, sedimentological variations in the box cores from both estuaries have been investigated by wavelet analysis and the sharp disappearance of high frequencies around AD 1900 in the estuary of the dammed river (Sainte-Marguerite River), but not in the estuary of the natural river (Moisie River), also provides evidence of the influence of dams on the sedimentary regime of estuaries.

  15. Numerical simulation of groundwater flow for the Yakima River basin aquifer system, Washington

    Science.gov (United States)

    Ely, D.M.; Bachmann, M.P.; Vaccaro, J.J.

    2011-01-01

    A regional, three-dimensional, transient numerical model of groundwater flow was constructed for the Yakima River basin aquifer system to better understand the groundwater-flow system and its relation to surface-water resources. The model described in this report can be used as a tool by water-management agencies and other stakeholders to quantitatively evaluate proposed alternative management strategies that consider the interrelation between groundwater availability and surface-water resources.

  16. A hybrid least squares support vector machines and GMDH approach for river flow forecasting

    Science.gov (United States)

    Samsudin, R.; Saad, P.; Shabri, A.

    2010-06-01

    This paper proposes a novel hybrid forecasting model, which combines the group method of data handling (GMDH) and the least squares support vector machine (LSSVM), known as GLSSVM. The GMDH is used to determine the useful input variables for LSSVM model and the LSSVM model which works as time series forecasting. In this study the application of GLSSVM for monthly river flow forecasting of Selangor and Bernam River are investigated. The results of the proposed GLSSVM approach are compared with the conventional artificial neural network (ANN) models, Autoregressive Integrated Moving Average (ARIMA) model, GMDH and LSSVM models using the long term observations of monthly river flow discharge. The standard statistical, the root mean square error (RMSE) and coefficient of correlation (R) are employed to evaluate the performance of various models developed. Experiment result indicates that the hybrid model was powerful tools to model discharge time series and can be applied successfully in complex hydrological modeling.

  17. Importance of the 2014 Colorado River Delta pulse flow for migratory songbirds: Insights from foraging behavior

    Science.gov (United States)

    Darrah, Abigail J.; Greeney, Harold F.; van Riper, Charles

    2017-01-01

    The Lower Colorado River provides critical riparian areas in an otherwise arid region and is an important stopover site for migrating landbirds. In order to reverse ongoing habitat degradation due to drought and human-altered hydrology, a pulse flow was released from Morelos Dam in spring of 2014, which brought surface flow to dry stretches of the Colorado River in Mexico. To assess the potential effects of habitat modification resulting from the pulse flow, we used foraging behavior of spring migrants from past and current studies to assess the relative importance of different riparian habitats. We observed foraging birds in 2000 and 2014 at five riparian sites along the Lower Colorado River in Mexico to quantify prey attack rates, prey attack maneuvers, vegetation use patterns, and degree of preference for fully leafed-out or flowering plants. Prey attack rate was highest in mesquite (Prosopis spp.) in 2000 and in willow (Salix gooddingii) in 2014; correspondingly, migrants predominantly used mesquite in 2000 and willow in 2014 and showed a preference for willows in flower or fruit in 2014. Wilson’s warbler (Cardellina pusilla) used relatively more low-energy foraging maneuvers in willow than in tamarisk (Tamarix spp.) or mesquite. Those patterns in foraging behavior suggest native riparian vegetation, and especially willow, are important resources for spring migrants along the lower Colorado River. Willow is a relatively short-lived tree dependent on spring floods for dispersal and establishment and thus spring migrants are likely to benefit from controlled pulse flows.

  18. River flow simulation using a multilayer perceptron-firefly algorithm model

    Science.gov (United States)

    Darbandi, Sabereh; Pourhosseini, Fatemeh Akhoni

    2018-06-01

    River flow estimation using records of past time series is importance in water resources engineering and management and is required in hydrologic studies. In the past two decades, the approaches based on the artificial neural networks (ANN) were developed. River flow modeling is a non-linear process and highly affected by the inputs to the modeling. In this study, the best input combination of the models was identified using the Gamma test then MLP-ANN and hybrid multilayer perceptron (MLP-FFA) is used to forecast monthly river flow for a set of time intervals using observed data. The measurements from three gauge at Ajichay watershed, East Azerbaijani, were used to train and test the models approach for the period from January 2004 to July 2016. Calibration and validation were performed within the same period for MLP-ANN and MLP-FFA models after the preparation of the required data. Statistics, the root mean square error and determination coefficient, are used to verify outputs from MLP-ANN to MLP-FFA models. The results show that MLP-FFA model is satisfactory for monthly river flow simulation in study area.

  19. Application of a methodological advance to calculate 3D flow fields in river channel junctions

    NARCIS (Netherlands)

    Moradi, Gelare; Vermeulen, Bart; Rennie, Colin; Cardot, Romain; Lane, Stuart

    2018-01-01

    Acoustic Doppler current profiler (aDcp) vessel-mounted flow measurements are now commonly used to quantify discharge and velocity in shallow water fluvial environments. Here, we consider the benefits of improving secondary circulation estimates in river confluences through the manner in which

  20. [Characteristics of nutrient loss by runoff in sloping arable land of yellow-brown under different rainfall intensities].

    Science.gov (United States)

    Chen, Ling; Liu, De-Fu; Song, Lin-Xu; Cui, Yu-Jie; Zhang, Gei

    2013-06-01

    In order to investigate the loss characteristics of N and P through surface flow and interflow under different rainfall intensities, a field experiment was conducted on the sloping arable land covered by typical yellow-brown soils inXiangxi River watershed by artificial rainfall. The results showed that the discharge of surface flow, total runoff and sediment increased with the increase of rain intensity, while the interflow was negatively correlated with rain intensity under the same total rainfall. TN, DN and DP were all flushed at the very beginning in surface flow underdifferent rainfall intensities; TP fluctuated and kept consistent in surface flow without obvious downtrend. While TN, DN and DP in interflow kept relatively stable in the whole runoff process, TP was high at the early stage, then rapidly decreased with time and kept steady finally. P was directly influenced by rainfall intensity, its concentration in the runoff increased with the increase of the rainfall intensity, the average concentration of N and P both exceeded the threshold of eutrophication of freshwater. The higher the amount of P loss was, the higher the rain intensity. The change of N loss was the opposite. The contribution rate of TN loss carried by surface flow increased from 36.5% to 57.6% with the increase of rainfall intensity, but surface flow was the primary form of P loss which contributed above 90.0%. Thus, it is crucial to control interflow in order to reduce N loss. In addition, measures should be taken to effectively manage soil erosion to mitigate P loss. The proportion of dissolved nitrogen in surface flow elevated with the decrease of rainfall intensity, but in interflow, dissolved form was predominant. P was exported mainly in the form of particulate under different rainfall intensities and runoff conditions.

  1. Chapter 1: Hydrologic exchange flows and their ecological consequences in river corridors

    Science.gov (United States)

    Harvey, Judson

    2016-01-01

    The actively flowing waters of streams and rivers remain in close contact with surrounding off-channel and subsurface environments. These hydrologic linkages between relatively fast flowing channel waters, with more slowly flowing waters off-channel and in the subsurface, are collectively referred to as hydrologic exchange flows (HEFs). HEFs include surface exchange with a channel’s marginal areas and subsurface flow through the streambed (hyporheic flow), as well as storm-driven bank storage and overbank flows onto floodplains. HEFs are important, not only for storing water and attenuating flood peaks, but also for their role in influencing water conservation, water quality improvement, and related outcomes for ecological values and services of aquatic ecosystems. Biogeochemical opportunities for chemical transformations are increased by HEFs as a result of the prolonged contact between flowing waters and geochemically and microbially active surfaces of sediments and vegetation. Chemical processing is intensified and water quality is often improved by removal of excess nutrients, metals, and organic contaminants from flowing waters. HEFs also are important regulators of organic matter decomposition, nutrient recycling, and stream metabolism that helps establish a balanced and resilient aquatic food web. The shallow and protected storage zones associated with HEFs support nursery and feeding areas for aquatic organisms that sustain aquatic biological diversity. Understanding of these varied roles for HEFs has been driven by the related disciplines of stream ecology, fluvial geomorphology, surface-water hydraulics, and groundwater hydrology. A current research emphasis is on the role that HEFs play in altered flow regimes, including restoration to achieve diverse goals, such as expanding aquatic habitats and managing dissolved and suspended river loads to reduce over-fertilization of coastal waters and offset wetland loss. New integrative concepts and models are

  2. A modeling approach to establish environmental flow threshold in ungauged semidiurnal tidal river

    Science.gov (United States)

    Akter, A.; Tanim, A. H.

    2018-03-01

    Due to shortage of flow monitoring data in ungauged semidiurnal river, 'environmental flow' (EF) determination based on its key component 'minimum low flow' is always difficult. For EF assessment this study selected a reach immediately after the Halda-Karnafuli confluence, a unique breeding ground for Indian Carp fishes of Bangladesh. As part of an ungauged tidal river, EF threshold establishment faces challenges in changing ecological paradigms with periodic change of tides and hydrologic alterations. This study describes a novel approach through modeling framework comprising hydrological, hydrodynamic and habitat simulation model. The EF establishment was conceptualized according to the hydrologic process of an ungauged semi-diurnal tidal regime in four steps. Initially, a hydrologic model coupled with a hydrodynamic model to simulate flow considering land use changes effect on streamflow, seepage loss of channel, friction dominated tidal decay as well as lack of long term flow characteristics. Secondly, to define hydraulic habitat feature, a statistical analysis on derived flow data was performed to identify 'habitat suitability'. Thirdly, to observe the ecological habitat behavior based on the identified hydrologic alteration, hydraulic habitat features were investigated. Finally, based on the combined habitat suitability index flow alteration and ecological response relationship was established. Then, the obtained EF provides a set of low flow indices of desired regime and thus the obtained discharge against maximum Weighted Usable Area (WUA) was defined as EF threshold for the selected reach. A suitable EF regime condition was obtained within flow range 25-30.1 m3/s i.e., around 10-12% of the mean annual runoff of 245 m3/s and these findings are within researchers' recommendation of minimum flow requirement. Additionally it was observed that tidal characteristics are dominant process in semi-diurnal regime. However, during the study period (2010-2015) the

  3. Comparison of the Gen Expression Programming, Nonlinear Time Series and Artificial Neural Network in Estimating the River Daily Flow (Case Study: The Karun River

    Directory of Open Access Journals (Sweden)

    R. Zamani

    2015-06-01

    Full Text Available Today, the daily flow forecasting of rivers is an important issue in hydrology and water resources and thus can be used the results of daily river flow modeling in water resources management, droughts and floods monitoring. In this study, due to the importance of this issue, using nonlinear time series models and artificial intelligence (Artificial Neural Network and Gen Expression Programming, the daily flow modeling has been at the time interval (1981-2012 in the Armand hydrometric station on the Karun River. Armand station upstream basin is one of the most basins in the North Karun basin and includes four sub basins (Vanak, Middle Karun, Beheshtabad and Kohrang.The results of this study shown that artificial intelligence models have superior than nonlinear time series in flow daily simulation in the Karun River. As well as, modeling and comparison of artificial intelligence models showed that the Gen Expression Programming have evaluation criteria better than artificial neural network.

  4. Determination of flow times and flow velocities in the upper Rhine river using 3HHO as tracer

    International Nuclear Information System (INIS)

    Krause, W.J.; Mundschenk, H.

    1990-01-01

    The behaviour of water bodies of the Upper Rhine river discretely traced with 3 HHO-loaded waste waters from the nuclear power plants of Beznau, Fessenheim, Philippsburg and Biblis was investigated along a distance of nearly 385 km down to Nierstein. The passage of the distinct entrainment charged by different emissions was measured at the sampling points of Bad Saeckingen, Weil, Weisweil, Iffezheim and Nierstein. From these profiles the flow times and flow velocities were calculated for the discharge range from 0.6 to 1.7 MQ (mean discharge), taking the begin, end and duration of the individual releases into account. (orig./HP) [de

  5. Modeling flow, sediment transport and morphodynamics in rivers

    Science.gov (United States)

    Nelson, Jonathan M.; McDonald, Richard R.; Shimizu, Yasuyuki; Kimura, Ichiro; Nabi, Mohamed; Asahi, Kazutake

    2016-01-01

    Predicting the response of natural or man-made channels to imposed supplies of water and sediment is one of the difficult practical problems commonly addressed by fluvial geomorphologists. This problem typically arises in three situations. In the first situation, geomorphologists are attempting to understand why a channel or class of channels has a certain general form; in a sense, this is the central goal of fluvial geomorphology. In the second situation, geomorphologists are trying to understand and explain how and why a specific channel will evolve or has evolved in response to altered or unusual sediment and water supplies to that channel. For example, this would include explaining the short-term response of a channel to an unusually large flood or predicting the response of a channel to long-term changes in flow or sediment supply due to various human activities such as damming or diversions. Finally, geomorphologists may be called upon to design or assess the design of proposed man-made channels that must carry a certain range of flows and sediment loads in a stable or at least quasi-stable manner. In each of these three situations, the problem is really the same: geomorphologists must understand and predict the interaction of the flow field in the channel, the sediment movement in the channel and the geometry of the channel bed and banks. In general, the flow field, the movement of sediment making up the bed and the morphology of the bed are intricately linked; the flow moves the sediment, the bed is altered by erosion and deposition of sediment and the shape of the bed is critically important for predicting the flow. This complex linkage is precisely what makes understanding channel form and process such a difficult and interesting challenge.

  6. Unraveling the effects of climate change and flow abstraction on an aggrading Alpine river

    Science.gov (United States)

    Bakker, Maarten; Costa, Anna; Adriao Silva, Tiago A.; Stutenbecker, Laura; Girardclos, Stéphanie; Loizeau, Jean-Luc; Molnar, Peter; Schlunegger, Fritz; Lane, Stuart N.

    2017-04-01

    Widespread temperature increase has been observed in the Swiss Alps and is most pronounced at high elevations. Alpine rivers are very susceptible to such change where large amounts of sediments are released from melting (peri)glacial environments and potentially become available for transport. These rivers are also impacted on a large scale by hydropower exploitation, where flow is commonly abstracted and transferred to a hydropower scheme. Whilst water is diverted, sediment is trapped at the intake and intermittently flushed down the river during short duration purges. Thus, these rivers are impacted upon by both climate and human forcing. In this study we quantify their relative and combined impacts upon the morphological evolution of an aggrading Alpine river. Our study focusses on the development of a sequence of braided reaches of the Borgne River (tributary of the Rhône) in south-west Switzerland. A unique dataset forms the basis for determining sediment deposition and transfer: (1) a set of high resolution Digital Elevation Models (DEMs) of the reaches was derived through applying Structure from Motion (SfM) photogrammetry to archival aerial photographs available for the period 1959-2014; (2) flow intake management data, provided by Grande Dixence SA, allowed the reconstruction of (up- and downstream) discharge and sediment supply since 1977. Subsequently we used climate data and transport capacity calculations to assess their relative impact on the system evolution over the last 25 years. Not surprisingly, considerable aggradation of the river bed (up to 5 meters) has taken place since the onset of flow abstraction in 1963: the abstraction of flow has substantially reduced sediment transport capacity whilst the sediment supply to the river was maintained. Although there was an initial response of the system to the start of abstraction in the 1960s, it was not before the onset of glacial retreat and the dry and warm years in the late 1980s and early 1990's

  7. Flow Routing in River Yala Using the Muskingum Technique | Opere ...

    African Journals Online (AJOL)

    The magnitude and frequency of occurrence of extreme hydrological events is of great importance due to the reasons of communication, water supply, power generation, agriculture and others. Due to population ... Forecasting through flow routing is achieved in this study using the Muskingum method. In this method ...

  8. Simulating floods in the Amazon River Basin: Impacts of new river geomorphic and dynamic flow parameterizations

    Science.gov (United States)

    Coe, M. T.; Costa, M. H.; Howard, E. A.

    2006-12-01

    In this paper we analyze the hydrology of the Amazon River system for the latter half of the 20th century with our recently completed model of terrestrial hydrology (Terrestrial Hydrology Model with Biogeochemistry, THMB). We evaluate the simulated hydrology of the Central Amazon basin against limited observations of river discharge, floodplain inundation, and water height and analyze the spatial and temporal variability of the hydrology for the period 1939-1998. We compare the simulated discharge and floodplain inundated area to the simulations by Coe et al., 2002 using a previous version of this model. The new model simulates the discharge and flooded area in better agreement with the observations than the previous model. The coefficient of correlation between the simulated and observed discharge for the greater than 27000 monthly observations of discharge at 120 sites throughout the Brazilian Amazon is 0.9874 compared to 0.9744 for the previous model. The coefficient of correlation between the simulated monthly flooded area and the satellite-based estimates by Sippel et al., 1998 exceeds 0.7 for 8 of the 12 mainstem reaches. The seasonal and inter-annual variability of the water height and the river slope compares favorably to the satellite altimetric measurements of height reported by Birkett et al., 2002.

  9. Dynamic hydro-climatic networks in pristine and regulated rivers

    Science.gov (United States)

    Botter, G.; Basso, S.; Lazzaro, G.; Doulatyari, B.; Biswal, B.; Schirmer, M.; Rinaldo, A.

    2014-12-01

    Flow patterns observed at-a-station are the dynamical byproduct of a cascade of processes involving different compartments of the hydro-climatic network (e.g., climate, rainfall, soil, vegetation) that regulates the transformation of rainfall into streamflows. In complex branching rivers, flow regimes result from the heterogeneous arrangement around the stream network of multiple hydrologic cascades that simultaneously occur within distinct contributing areas. As such, flow regimes are seen as the integrated output of a complex "network of networks", which can be properly characterized by its degree of temporal variability and spatial heterogeneity. Hydrologic networks that generate river flow regimes are dynamic in nature. In pristine rivers, the time-variance naturally emerges at multiple timescales from climate variability (namely, seasonality and inter-annual fluctuations), implying that the magnitude (and the features) of the water flow between two nodes may be highly variable across different seasons and years. Conversely, the spatial distribution of river flow regimes within pristine rivers involves scale-dependent transport features, as well as regional climatic and soil use gradients, which in small and meso-scale catchments (A guarantee quite uniform flow regimes and high spatial correlations. Human-impacted rivers, instead, constitute hybrid networks where observed spatio-temporal patterns are dominated by anthropogenic shifts, such as landscape alterations and river regulation. In regulated rivers, the magnitude and the features of water flows from node to node may change significantly through time due to damming and withdrawals. However, regulation may impact river regimes in a spatially heterogeneous manner (e.g. in localized river reaches), with a significant decrease of spatial correlations and network connectivity. Provided that the spatial and temporal dynamics of flow regimes in complex rivers may strongly impact important biotic processes

  10. Regional implications of heat flow of the Snake River Plain, Northwestern United States

    Science.gov (United States)

    Blackwell, D. D.

    1989-08-01

    The Snake River Plain is a major topographic feature of the Northwestern United States. It marks the track of an upper mantle and crustal melting event that propagated across the area from southwest to northeast at a velocity of about 3.5 cm/yr. The melting event has the same energetics as a large oceanic hotspot or plume and so the area is the continental analog of an oceanic hotspot track such as the Hawaiian Island-Emperor Seamount chain. Thus, the unique features of the area reflect the response of a continental lithosphere to a very energetic hotspot. The crust is extensively modified by basalt magma emplacement into the crust and by the resulting massive rhyolite volcanism from melted crustal material, presently occurring at Yellowstone National Park. The volcanism is associated with little crustal extension. Heat flow values are high along the margins of the Eastern and Western Snake River Plains and there is abundant evidence for low-grade geothermal resources associated with regional groundwater systems. The regional heat flow pattern in the Western Snake River Plains reflects the influence of crustal-scale thermal refraction associated with the large sedimentary basin that has formed there. Heat flow values in shallow holes in the Eastern Snake River Plains are low due to the Snake River Plains aquifer, an extensive basalt aquifer where water flow rates approach 1 km/yr. Below the aquifer, conductive heat flow values are about 100 mW m -2. Deep holes in the region suggest a systematic eastward increase in heat flow in the Snake River Plains from about 75-90 mW m -2 to 90-110 mW m -2. Temperatures in the upper crust do not behave similarly because the thermal conductivity of the Plio-Pleistocene sedimentary rocks in the west is lower than that in the volcanic rocks characteristic of the Eastern Snake River Plains. Extremely high heat loss values (averaging 2500 mW m -2) and upper crustal temperatures are characteristic of the Yellowstone caldera.

  11. Research of thermoluminescence dating for ancient debris flow materials in Qingshui river basin of Beijing

    International Nuclear Information System (INIS)

    Liu Junxin; Wei Mingjian; Zhou Rui; Zhang Bin; Liu Tiantian

    2012-01-01

    The thermoluminescence age of the samples for ancient debris flow terraces material of Lingshan and Hongshuikou, which are in Qingshui River Basin of Beijing, was studied using the thermo luminescence technology. The age increases with the increasing depth of two ancient debris flow profile, and the deeper debris flow deposits material the more of the environmental radiation dose is. The trend with depth of U, Th and K contents and annual dose is consistency. And the change with depth of Th content is more discrete than that of U, K contents. (authors)

  12. Petrology and chemistry of the Huntzinger flow, Columbia River basalt, Washington

    Energy Technology Data Exchange (ETDEWEB)

    Ward, A.W. Jr.

    1976-11-01

    Drill core samples of basalts of the Columbia River Group from the Hanford Reservation reveal a spotted, diabasic flow of up to 60 meters in thickness. These samples and those from the flow outcropping at Wahatis Peak (Saddle Mountains, Washington) were examined in detail to document intraflow textural, mineralogical, and chemical variations, which are of importance in basalt flow correlations. Analyses were by atomic absorption, instrumental neutron activation, electron microprobe, natural gamma well logging, K-Ar age dating, X-ray fluorescence, field (portable) magnetometer, and petrographic microscope.

  13. Interim Columbia and Snake rivers flow improvement measures for salmon: Final Supplemental Environmental Impact Statement (SEIS)

    Energy Technology Data Exchange (ETDEWEB)

    1993-03-01

    Public comments are sought on this final SEIS, which supplements the 1992 Columbia River Salmon Flow Measures Options Analysis (OA)/Environmental Impact Statement (EIS). The Corps of Engineers, in cooperation with the Bonneville Power Administration and the Bureau of Reclamation proposes five alternatives to improve flows of water in the lower Columbia-Snake rivers in 1993 and future years to assist the migration of juvenile and adult anadromous fish past eight hydropower dams. These are: (1) Without Project (no action) Alternative, (2) the 1992 Operation, (3) the 1992 Operation with Libby/Hungry Horse Sensitivity, (4) a Modified 1992 Operation with Improvements to Salmon Flows from Dworshak, and (5) a Modified 1992 Operation with Upper Snake Sensitivity. Alternative 4, Modified 1992 Operations, has been identified as the preferred alternative.

  14. Dynamic modeling of the Ganga river system: impacts of future climate and socio-economic change on flows and nitrogen fluxes in India and Bangladesh.

    Science.gov (United States)

    Whitehead, P G; Sarkar, S; Jin, L; Futter, M N; Caesar, J; Barbour, E; Butterfield, D; Sinha, R; Nicholls, R; Hutton, C; Leckie, H D

    2015-06-01

    This study investigates the potential impacts of future climate and socio-economic change on the flow and nitrogen fluxes of the Ganga river system. This is the first basin scale water quality study for the Ganga considering climate change at 25 km resolution together with socio-economic scenarios. The revised dynamic, process-based INCA model was used to simulate hydrology and water quality within the complex multi-branched river basins. All climate realizations utilized in the study predict increases in temperature and rainfall by the 2050s with significant increase by the 2090s. These changes generate associated increases in monsoon flows and increased availability of water for groundwater recharge and irrigation, but also more frequent flooding. Decreased concentrations of nitrate and ammonia are expected due to increased dilution. Different future socio-economic scenarios were found to have a significant impact on water quality at the downstream end of the Ganga. A less sustainable future resulted in a deterioration of water quality due to the pressures from higher population growth, land use change, increased sewage treatment discharges, enhanced atmospheric nitrogen deposition, and water abstraction. However, water quality was found to improve under a more sustainable strategy as envisaged in the Ganga clean-up plan.

  15. Evaporation and abstraction determined from stable isotopes during normal flow on the Gariep River, South Africa

    Science.gov (United States)

    Diamond, Roger E.; Jack, Sam

    2018-04-01

    Changes in the stable isotope composition of water can, with the aid of climatic parameters, be used to calculate the quantity of evaporation from a water body. Previous workers have mostly focused on small, research catchments, with abundant data, but of limited scope. This study aimed to expand such work to a regional or sub-continental scale. The first full length isotope survey of the Gariep River quantifies evaporation on the river and the man-made reservoirs for the first time, and proposes a technique to calculate abstraction from the river. The theoretically determined final isotope composition for an evaporating water body in the given climate lies on the empirically determined local evaporation line, validating the assumptions and inputs to the Craig-Gordon evaporation model that was used. Evaporation from the Gariep River amounts to around 20% of flow, or 40 m3/s, of which about half is due to evaporation from the surface of the Gariep and Vanderkloof Reservoirs, showing the wastefulness of large surface water impoundments. This compares well with previous estimates based on evapotranspiration calculations, and equates to around 1300 GL/a of water, or about the annual water consumption of Johannesburg and Pretoria, where over 10 million people reside. Using similar evaporation calculations and applying existing transpiration estimates to a gauged length of river, the remaining quantity can be attributed to abstraction, amounting to 175 L/s/km in the lower middle reaches of the river. Given that high water demand and climate change are global problems, and with the challenges of maintaining water monitoring networks, stable isotopes are shown to be applicable over regional to national scales for modelling hydrological flows. Stable isotopes provide a complementary method to conventional flow gauging for understanding hydrology and management of large water resources, particularly in arid areas subject to significant evaporation.

  16. Impacts of small scale flow regulation on sediment dynamics in an ecologically important upland river.

    Science.gov (United States)

    Quinlan, E; Gibbins, C N; Batalla, R J; Vericat, D

    2015-03-01

    Flow regulation is widely recognized as affecting fluvial processes and river ecosystems. Most impact assessments have focused on large dams and major water transfer schemes, so relatively little is known about the impacts of smaller dams, weirs and water diversions. This paper assesses sediment dynamics in an upland river (the Ehen, NW England) whose flows are regulated by a small weir and tributary diversion. The river is important ecologically due to the presence of the endangered freshwater pearl mussel Margaritifera margaritifera, a species known to be sensitive to sedimentary conditions. Fine sediment yield for the 300-m long study reach was estimated to be 0.057 t km(-2) year(-1), a very low value relative to other upland UK rivers. Mean in-channel storage of fine sediment was also low, estimated at an average of around 40 g m(-2). Although the study period was characterized by frequent high flow events, little movement of coarser bed material was observed. Data therefore indicate an extremely stable fluvial system within the study reach. The implication of this stability for pearl mussels is discussed.

  17. Hydraulic conditions of flood flows in a Polish Carpathian river subjected to variable human impacts

    Science.gov (United States)

    Radecki-Pawlik, Artur; Czech, Wiktoria; Wyżga, Bartłomiej; Mikuś, Paweł; Zawiejska, Joanna; Ruiz-Villanueva, Virginia

    2016-04-01

    Channel morphology of the Czarny Dunajec River, Polish Carpathians, has been considerably modified as a result of channelization and gravel-mining induced channel incision, and now it varies from a single-thread, incised or regulated channel to an unmanaged, multi-thread channel. We investigated effects of these distinct channel morphologies on the conditions for flood flows in a study of 25 cross-sections from the middle river course where the Czarny Dunajec receives no significant tributaries and flood discharges increase little in the downstream direction. Cross-sectional morphology, channel slope and roughness of particular cross-section parts were used as input data for the hydraulic modelling performed with the 1D steady-flow HEC-RAS model for discharges with recurrence interval from 1.5 to 50 years. The model for each cross-section was calibrated with the water level of a 20-year flood from May 2014, determined shortly after the flood on the basis of high-water marks. Results indicated that incised and channelized river reaches are typified by similar flow widths and cross-sectional flow areas, which are substantially smaller than those in the multi-thread reach. However, because of steeper channel slope in the incised reach than in the channelized reach, the three river reaches differ in unit stream power and bed shear stress, which attain the highest values in the incised reach, intermediate values in the channelized reach, and the lowest ones in the multi-thread reach. These patterns of flow power and hydraulic forces are reflected in significant differences in river competence between the three river reaches. Since the introduction of the channelization scheme 30 years ago, sedimentation has reduced its initial flow conveyance by more than half and elevated water stages at given flood discharges by about 0.5-0.7 m. This partly reflects a progressive growth of natural levees along artificially stabilized channel banks. By contrast, sediments of natural

  18. Identifying hydrological regime and eco-flow threshold of small and medium flood of the Xiaoqing River in Jinan city

    Science.gov (United States)

    Liu, Yang; Cao, Sheng-Le

    2017-06-01

    It was known that hydrological regime was the main influencing factor of river ecosystem, but the regime of different flow rates of urban rivers was poorly understood. We collected daily inflows at the Huangtai station of the Xiaoqing River from 1960 to 2014 and divided the data into three periods. Then we calculated hydrological parameters by the method of EFCs (Environmental Flow Components) and analyzed the tendency and change rates of each component respectively in the three periods. Combined with the ecological significance of environmental flow components, we identified the small and medium flood had the greatest impact on the river regime and ecosystem. And then we used the hydraulic parameters in the good ecosystem period as control conditions, to calculate the ecological threshold of the flow component under the current situation. This study could provide technical support for restoring and improving hydrological regime and ecological environment of the Xiaoqing River in Jinan city.

  19. Geomorphic Change Induced by 100 years of Flow Alteration on the Diamond Fork River, Central Utah

    Science.gov (United States)

    Jones, J.; Belmont, P.; Wilcock, P. R.

    2017-12-01

    Changes in hydrology and sediment supply affect the form of rivers. The rate of change of fluvial form is controlled by a variety of factors, including valley confinement, sediment size, and antecedent condition. The Diamond Fork River in central Utah has been altered by trans-basin flows delivered from the Colorado River system for over a century. Beginning in 1915, water used for irrigation was delivered through a tributary, Sixth Water Creek, with daily summer flows regularly exceeding the 50 - 100 year flood. Elevated flows caused drastic geomorphic change - resulting in incision and widening of the channel, and the destruction of riparian vegetation. Beginning in 1997, the outlet for the trans-basin diversion was moved downstream on Sixth Water, bypassing a large landslide, and flows were drastically reduced in 2004 through management actions. We delineated eight distinct process domains for the Sixth Water-Diamond Fork system and examined the response of each process domain to the altered flow and sediment regimes through the analysis of aerial photographs and repeat cross-sections. We measured a variety of channel metrics, including channel width, areal extent of bars and islands, and sinuosity in ArcGIS. Results indicate that unconfined reaches that were wide and braided during the period of elevated flows have narrowed to become single threaded and meandering in response to the reduced flows. Confined reaches have experienced minor changes since the reduction in flows, suggesting that confinement is a primary control on the degree of channel response. These findings and complimentary studies will provide managers of Sixth Water and Diamond Fork with a greater understanding of the physical response of the streams, and the resulting effects on ecological communities.

  20. Linking Flow Regime and Water Quality in Rivers: a Challenge to Adaptive Catchment Management

    Directory of Open Access Journals (Sweden)

    Christer Nilsson

    2008-12-01

    Full Text Available Water quality describes the physicochemical characteristics of the water body. These vary naturally with the weather and with the spatiotemporal variation of the water flow, i.e., the flow regime. Worldwide, biota have adapted to the variation in these variables. River channels and their riparian zones contain a rich selection of adapted species and have been able to offer goods and services for sustaining human civilizations. Many human impacts on natural riverine environments have been destructive and present opportunities for rehabilitation. It is a big challenge to satisfy the needs of both humans and nature, without sacrificing one or the other. New ways of thinking, new policies, and institutional commitment are needed to make improvements, both in the ways water flow is modified in rivers by dam operations and direct extractions, and in the ways runoff from adjacent land is affected by land-use practices. Originally, prescribed flows were relatively static, but precepts have been developed to encompass variation, specifically on how water could be shared over the year to become most useful to ecosystems and humans. A key aspect is how allocations of water interact with physicochemical variation of water. An important applied question is how waste releases and discharge can be managed to reduce ecological and sanitary problems that might arise from inappropriate combinations of flow variation and physicochemical characteristics of water. We review knowledge in this field, provide examples on how the flow regime and the water quality can impact ecosystem processes, and conclude that most problems are associated with low-flow conditions. Given that reduced flows represent an escalating problem in an increasing number of rivers worldwide, managers are facing enormous challenges.

  1. Numerical modelling of admixture transport in a turbulent flow at river confluence

    International Nuclear Information System (INIS)

    Lyubimova, T; Parshakova, Ya; Konovalov, V; Shumilova, N; Lepikhin, A; Tiunov, A

    2013-01-01

    The paper is concerned with the development of the hydrodynamic model of the Chusovskoy water intake located in the confluence zone of two rivers with essentially different hydrochemical regimes and in the backwater zone of the Kamskaya hydroelectric power station. The proposed model is used for numerical simulation in the framework of two-and three-dimensional approaches for the annual average, minimal and maximal values of the water flow rates in two rivers. The data for water mineralization in the water intake zone have been obtained. The recommendations for optimization of the water intake structure have been formulated.

  2. Design of a naturalized flow regime—An example from the Lower Missouri River, USA

    Science.gov (United States)

    Jacobson, Robert B.; Galat, David L.

    2008-01-01

     group of river managers, stakeholders, and scientists met during summer 2005 to design a more naturalized flow regime for the Lower Missouri River (LMOR). The objective was to comply with requirements under the U.S. Endangered Species Act to support reproduction and survival of threatened and endangered species, with emphasis on the endangered pallid sturgeon (Scaphirhynchus albus), while minimizing negative effects to existing social and economic benefits of prevailing river management. Specific hydrograph requirements for pallid sturgeon reproduction are unknown, hence much of the design process was based on features of the natural flow regime. Environmental flow components (EFCs) extracted from the reference natural flow regime were used to design and assess performance of alternative flow regimes.The design process incorporated a primary stage in which conceptual hydrographs were developed and assessed for their general ecological and social-economic performance. The second stage accounted for hydroclimatic variation by coding the conceptual hydrographs into reservoir release rules, adding constraints for downstream flooding and low-storage precludes, and running the rules through 100 years of hydroclimatic simulation. The output flow regimes were then evaluated for presumed ecological benefits based on how closely they resembled EFCs in the reference natural flow regime. Flow regimes also were assessed for social-economic cost indicators, including days of flooding of low-lying agricultural land, days over flood stage, and storage levels in system reservoirs.Our experience with flow-regime design on the LMOR underscored the lack of confidence the stakeholders place in the value of the natural flow regime as a measure of ecosystem benefit in the absence of fundamental scientific documentation. Stakeholders desired proof of ecological benefits commensurate with the certainty of economic losses. We also gained insight into the processes of integrating science

  3. STRUCTURAL CHARACTERISTIC OF ICHTHYOPLANKTON IN A SMALL RIVER FLOWING WITHIN A BAR PLAIN OF THE DNIPRO RIVER

    Directory of Open Access Journals (Sweden)

    I. Abramiuk

    2017-09-01

    Full Text Available Purpose. Using as an example of a small river, which flows through a bar plain of the Dnipro, to study species composition of the littoral ichthyoplankton, dynamics of its structure during the season and its diversity in different parts of the river. Methodology. The littoral ichthyoplankton was investigated during four seasons of 2011-2014 on the Vita river, a right tributary of the Dnipro affected by the operation of Kaniv HPP. The research covered the main channel, a permanent backwater connected with the channel, as well as temporarily flooded areas of the floodplain and separated from the channel oxbow lakes. Samples were collected with standard sweep nets and Bagenal buoyant nets. Identification of young fish was carried out under binocular microscope MBS-9. Early life stages of larvae were determined according to the system of V. Vasnetsov. Species diversity of ichthyoplankton was assessed by the Shannon index. Findings. The littoral ichthyoplankton during May-July mostly consisted of limnophilic fish larvae belonging to a family Cyprinidae. In the river channel and the backwater at the beginning of the period the larvae of roach (Rutilus rutilus prevailed, later they were substituted by larvae of more thermophilic species, among which the rudd (Scardinius erythrophthalmus was the most abundant. In the oxbow lakes and temporarily flooded areas in spring the coastal ichthyoplankton was mainly structured by larvae of Carassius sp. and the rudd, in summer the larvae assemblages of oxbow lakes were quantitatively dominated by the sunbleak (Leucaspius delineatus. In areas covered with vegetation the larvae of invasive Chinese sleeper (Perccottus glenii were firstly found. Rheophilic species among young fish were absent, which indicates unfavorable conditions for their spawning at present hydrologic regime of the river. Originality. For the first time the coastal communities of early young fish in a small tributary of the Dnipro were

  4. High Resolution Monitoring of River Bluff Erosion Reveals Failure Mechanisms and Geomorphically Effective Flows

    Directory of Open Access Journals (Sweden)

    Sara Ann Kelly

    2018-03-01

    Full Text Available Using a combination of Structure from Motion and time lapse photogrammetry, we document rapid river bluff erosion occurring in the Greater Blue Earth River (GBER basin, a muddy tributary to the sediment-impaired Minnesota River in south central Minnesota. Our datasets elucidated dominant bluff failure mechanisms and rates of bluff retreat in a transient system responding to ongoing streamflow increases and glacial legacy impacts. Specifically, we document the importance of fluvial scour, freeze–thaw, as well as other drivers of bluff erosion. We find that even small flows, a mere 30% of the two-year recurrence interval flow, are capable of causing bluff erosion. During our study period (2014–2017, the most erosion was associated with two large flood events with 13- and 25-year return periods. However, based on the frequency of floods and magnitude of bluff face erosion associated with floods over the last 78 years, the 1.2-year return interval flood has likely accomplished the most cumulative erosion, and is thus more geomorphically effective than larger magnitude floods. Flows in the GBER basin are nonstationary, increasing across the full range of return intervals. We find that management implications differ considerably depending on whether the bluff erosion-runoff power law exponent, γ, is greater than, equal to, or less than 1. Previous research has recommended installation of water retention sites in tributaries to the Minnesota River in order to reduce flows and sediment loading from river bluffs. Our findings support the notion that water retention would be an effective practice to reduce sediment loading and highlight the importance of managing for both runoff frequency and magnitude.

  5. Role of river flow and sediment mobilization in riparian alder establishment along a bedrock-gravel river, South Fork Eel River, California

    Science.gov (United States)

    Jablkowski, P.; Johnson, E. A.; Martin, Y. E.

    2017-10-01

    Climatic, hydraulics, hydrologic, and fluvial geomorphic processes are the main drivers of riparian white alder (Alnus rhombifolia Nutt.) distribution in northern California. The Mediterranean climate and canyon bound, bedrock-gravel morphology of the South Fork Eel have a distinct effect on these processes. White alder seeds are preferentially deposited on river bars where river hydraulics create eddies coinciding with the downstream part of riffles and the upstream part of pools. Seeds are generally deposited below bankfull elevations by the descending hydrograph during the spring season in this Mediterranean climate. For successful germination and establishment, the seeds must be deposited at a location such that they are not remobilized by late spring flows. The summer establishment period is defined from the date of seed deposition and germination to the fall/winter date of river sediment mobilization. Seedling root growth rate decreases exponentially with decreasing water potential. However, seedlings are shown not to be generally limited by water availability at the elevations they are most commonly deposited. The establishment of white alder seedlings following the first summer will therefore depend on their ability to resist fall/winter high flows. The method proposed here compares the predicted rooting depth to predicted sediment scour rates. The length of the establishment period rather than water availability determines final seedling rooting depth. Over the past 40 years, very few years had establishment periods that were long enough or had fast enough alder growth rates to survive winter floods that often scour deeper than the total root length. The low survival of seedlings in the first autumn season following germination is believed to be a principal reason for the missing age classes often found in alder distributions along rivers.

  6. Nutrients and carbon fluxes in the estuaries of major rivers flowing into the tropical Atlantic

    Directory of Open Access Journals (Sweden)

    Moacyr Cunha De Araujo

    2014-05-01

    Full Text Available Knowledge of the seasonal variability of river discharge and the concentration of nutrients in the estuary waters of large rivers flowing into the tropical Atlantic contributes to a better understanding of the biogeochemical processes that occur in adjacent coastal and ocean systems. The monthly averaged variations of the physical and biogeochemical contributions of the Orinoco, Amazon, São Francisco, Paraíba do Sul (South America, Volta, Niger and Congo (Africa Rivers are estimated from models or observations. The results indicate that these rivers deliver approximately 0.1 Pg C yr-1 in its dissolved organic (DOC 0.046 Pg C yr-1 and inorganic (DIC 0.053 Pg C yr-1 forms combined. These values represent 27.3% of the global DOC and 13.2% of the global DIC delivered by rivers into the world’s oceans. Estimations of the air-sea CO2 fluxes indicate a slightly higher atmospheric liberation for the African systems compared with the South American estuaries (+10.67 mmol m-2 day-1 and +5.48 mmol m-2 day-1, respectively. During the high river discharge periods, the fluxes remained positive in all of the analyzed systems (average +128 mmol m-2 day-1, except at the mouth of the Orinoco River, which continued to act as a sink for CO2. During the periods of low river discharges, the mean CO2 efflux decreased to +5.29 mmol m-2 day-1. The updated and detailed review presented here contributes to the accurate quantification of CO2 input into the atmosphere and to ongoing studies on the oceanic modeling of biogeochemical cycles in the tropical Atlantic.

  7. Hydrograph simulation models of the Hillsborough and Alafia Rivers, Florida: a preliminary report

    Science.gov (United States)

    Turner, James F.

    1972-01-01

    Mathematical (digital) models that simulate flood hydrographs from rainfall records have been developed for the following gaging stations in the Hillsborough and Alafia River basins of west-central Florida: Hillsborough River near Tampa, Alafia River at Lithia, and north Prong Alafia River near Keysville. These models, which were developed from historical streamflow and and rainfall records, are based on rainfall-runoff and unit-hydrograph procedures involving an arbitrary separation of the flood hydrograph. These models assume the flood hydrograph to be composed of only two flow components, direct (storm) runoff, and base flow. Expressions describing these two flow components are derived from streamflow and rainfall records and are combined analytically to form algorithms (models), which are programmed for processing on a digital computing system. Most Hillsborough and Alafia River flood discharges can be simulated with expected relative errors less than or equal to 30 percent and flood peaks can be simulated with average relative errors less than 15 percent. Because of the inadequate rainfall network that is used in obtaining input data for the North Prong Alafia River model, simulated peaks are frequently in error by more than 40 percent, particularly for storms having highly variable areal rainfall distribution. Simulation errors are the result of rainfall sample errors and, to a lesser extent, model inadequacy. Data errors associated with the determination of mean basin precipitation are the result of the small number and poor areal distribution of rainfall stations available for use in the study. Model inadequacy, however, is attributed to the basic underlying theory, particularly the rainfall-runoff relation. These models broaden and enhance existing water-management capabilities within these basins by allowing the establishment and implementation of programs providing for continued development in these areas. Specifically, the models serve not only as a

  8. Explore the impacts of river flow and quality on biodiversity for water resources management by AI techniques

    Science.gov (United States)

    Chang, Fi-John; Tsai Tsai, Wen-Ping; Chang, Li-Chiu

    2016-04-01

    Water resources development is very challenging in Taiwan due to her diverse geographic environment and climatic conditions. To pursue sustainable water resources development, rationality and integrity is essential for water resources planning. River water quality and flow regimes are closely related to each other and affect river ecosystems simultaneously. This study aims to explore the complex impacts of water quality and flow regimes on fish community in order to comprehend the situations of the eco-hydrological system in the Danshui River of northern Taiwan. To make an effective and comprehensive strategy for sustainable water resources management, this study first models fish diversity through implementing a hybrid artificial neural network (ANN) based on long-term observational heterogeneity data of water quality, stream flow and fish species in the river. Then we use stream flow to estimate the loss of dissolved oxygen based on back-propagation neural networks (BPNNs). Finally, the non-dominated sorting genetic algorithm II (NSGA-II) is established for river flow management over the Shihmen Reservoir which is the main reservoir in this study area. In addition to satisfying the water demands of human beings and ecosystems, we also consider water quality for river flow management. The ecosystem requirement takes the form of maximizing fish diversity, which can be estimated by the hybrid ANN. The human requirement is to provide a higher satisfaction degree of water supply while the water quality requirement is to reduce the loss of dissolved oxygen in the river among flow stations. The results demonstrate that the proposed methodology can offer diversified alternative strategies for reservoir operation and improve reservoir operation strategies for producing downstream flows that could better meet both human and ecosystem needs as well as maintain river water quality. Keywords: Artificial intelligence (AI), Artificial neural networks (ANNs), Non

  9. Bed Load Variability and Morphology of Gravel Bed Rivers Subject to Unsteady Flow: A Laboratory Investigation

    Science.gov (United States)

    Redolfi, M.; Bertoldi, W.; Tubino, M.; Welber, M.

    2018-02-01

    Measurement and estimation of bed load transport in gravel bed rivers are highly affected by its temporal fluctuations. Such variability is primarily driven by the flow regime but is also associated with a variety of inherent channel processes, such as flow turbulence, grain entrainment, and bed forms migration. These internal and external controls often act at comparable time scales, and are therefore difficult to disentangle, thus hindering the study of bed load variability under unsteady flow regime. In this paper, we report on laboratory experiments performed in a large, mobile bed flume where typical hydromorphological conditions of gravel bed rivers were reproduced. Data from a large number of replicated runs, including triangular and square-wave hydrographs, were used to build a statistically sound description of sediment transport processes. We found that the inherent variability of bed load flux strongly depends on the sampling interval, and it is significantly higher in complex, wandering or braided channels. This variability can be filtered out by computing the mean response over the experimental replicates, which allows us to highlight two distinctive phenomena: (i) an overshooting (undershooting) response of the mean bed load flux to a sudden increase (decrease) of discharge, and (ii) a clockwise hysteresis in the sediment rating curve. We then provide an interpretation of these findings through a conceptual mathematical model, showing how both phenomena are associated with a lagging morphological adaptation to unsteady flow. Overall, this work provides basic information for evaluating, monitoring, and managing gravel transport in morphologically active rivers.

  10. Determination of reliable environmental flows in Colombia: The example of the River Palace (Cauca)

    International Nuclear Information System (INIS)

    Diez Hernandez, Juan Manuel; Ruiz Cobo Dario Hernan

    2007-01-01

    The increasing exploitation of the water resources in Colombia requires an advanced Environmental Flows Regime (EFR) regulation, for a properly design of the Watershed Planning and Management Programs. Among the diversity of approaches proposed to EFR assessment, the most used and scientifically accepted is the well-known Instream Flow Incremental Methodology (IFIM), whose applicability for Colombian rivers is explored in this study. The IFIM modeling of the Palace River below the diversion of 500 l/s to the new water-supply facilities in Popayan (Cauca) reveals that the global effect of this limited derivation of the 6.78% mean annual flow in the integrity of the aquatic ecosystem is very low. The eco-hydraulic and eco hydrological simulations of the representative reach (500m length, 18m width, 500/00 slope and coarse substrate) analyzed with the software RHABSIM 3.0, revealed some not very significant reductions of the usable habitat for adult fishes and macro-invertebrates. Consequently, the present instream flows regime of the Palace River caused by the diversion project is corroborated as a satisfactory EFR, according to the IFIM evaluation system. Finally, some research lines are suggested, that are focused to the improvement and adaptation of the IFIM to the particular fluvial conditions of Colombia

  11. Effect of river flow fluctuations on riparian vegetation dynamics: Processes and models

    Science.gov (United States)

    Vesipa, Riccardo; Camporeale, Carlo; Ridolfi, Luca

    2017-12-01

    Several decades of field observations, laboratory experiments and mathematical modelings have demonstrated that the riparian environment is a disturbance-driven ecosystem, and that the main source of disturbance is river flow fluctuations. The focus of the present work has been on the key role that flow fluctuations play in determining the abundance, zonation and species composition of patches of riparian vegetation. To this aim, the scientific literature on the subject, over the last 20 years, has been reviewed. First, the most relevant ecological, morphological and chemical mechanisms induced by river flow fluctuations are described from a process-based perspective. The role of flow variability is discussed for the processes that affect the recruitment of vegetation, the vegetation during its adult life, and the morphological and nutrient dynamics occurring in the riparian habitat. Particular emphasis has been given to studies that were aimed at quantifying the effect of these processes on vegetation, and at linking them to the statistical characteristics of the river hydrology. Second, the advances made, from a modeling point of view, have been considered and discussed. The main models that have been developed to describe the dynamics of riparian vegetation have been presented. Different modeling approaches have been compared, and the corresponding advantages and drawbacks have been pointed out. Finally, attention has been paid to identifying the processes considered by the models, and these processes have been compared with those that have actually been observed or measured in field/laboratory studies.

  12. Scaling up watershed model parameters--Flow and load simulations of the Edisto River Basin

    Science.gov (United States)

    Feaster, Toby D.; Benedict, Stephen T.; Clark, Jimmy M.; Bradley, Paul M.; Conrads, Paul

    2014-01-01

    The Edisto River is the longest and largest river system completely contained in South Carolina and is one of the longest free flowing blackwater rivers in the United States. The Edisto River basin also has fish-tissue mercury concentrations that are some of the highest recorded in the United States. As part of an effort by the U.S. Geological Survey to expand the understanding of relations among hydrologic, geochemical, and ecological processes that affect fish-tissue mercury concentrations within the Edisto River basin, analyses and simulations of the hydrology of the Edisto River basin were made with the topography-based hydrological model (TOPMODEL). The potential for scaling up a previous application of TOPMODEL for the McTier Creek watershed, which is a small headwater catchment to the Edisto River basin, was assessed. Scaling up was done in a step-wise process beginning with applying the calibration parameters, meteorological data, and topographic wetness index data from the McTier Creek TOPMODEL to the Edisto River TOPMODEL. Additional changes were made with subsequent simulations culminating in the best simulation, which included meteorological and topographic wetness index data from the Edisto River basin and updated calibration parameters for some of the TOPMODEL calibration parameters. Comparison of goodness-of-fit statistics between measured and simulated daily mean streamflow for the two models showed that with calibration, the Edisto River TOPMODEL produced slightly better results than the McTier Creek model, despite the significant difference in the drainage-area size at the outlet locations for the two models (30.7 and 2,725 square miles, respectively). Along with the TOPMODEL hydrologic simulations, a visualization tool (the Edisto River Data Viewer) was developed to help assess trends and influencing variables in the stream ecosystem. Incorporated into the visualization tool were the water-quality load models TOPLOAD, TOPLOAD-H, and LOADEST

  13. Non-equilibrium flow and sediment transport distribution over mobile river dunes

    Science.gov (United States)

    Hoitink, T.; Naqshband, S.; McElroy, B. J.

    2017-12-01

    Flow and sediment transport are key processes in the morphodynamics of river dunes. During floods in several rivers (e.g., the Elkhorn, Missouri, Niobrara, and Rio Grande), dunes are observed to grow rapidly as flow strength increases, undergoing an unstable transition regime, after which they are washed out in what is called upper stage plane bed. This morphological evolution of dunes to upper stage plane bed is the strongest bed-form adjustment during non-equilibrium flows and is associated with a significant change in hydraulic roughness and water levels. Detailed experimental investigations, however, have mostly focused on fixed dunes limited to equilibrium flow and bed conditions that are rare in natural channels. Our understanding of the underlying sedimentary processes that result into the washing out of dunes is therefore very limited. In the present study, using the Acoustic Concentration and Velocity Profiler (ACVP), we were able to quantify flow structure and sediment transport distribution over mobile non-equilibrium dunes. Under these non-equilibrium flow conditions average dune heights were decreasing while dune lengths were increasing. Preliminary results suggest that this morphological behaviour is due to a positive phase lag between sediment transport maximum and topographic maximum leading to a larger erosion on the dune stoss side compared to deposition on dune lee side.

  14. Flathead River Instream Flow Investigation Project : Final Report 1996-2003.

    Energy Technology Data Exchange (ETDEWEB)

    Miller, William J. (Miller Ecological Consultants., Fort Collins, CO); Ptacek, Jonathan A. (Miller Ecological Consultants, Inc., Fort Collins, CO)

    2003-09-01

    A modified Instream Flow Incremental Methodology (IFIM) approach was used on the mainstem Flathead River from the South Fork Flathead River downstream to Flathead Lake. The objective of this study was to quantify changes in habitat for the target fish species, bull trout (Salvelinus confluentus) and west slope cutthroat trout (Oncorhynchus clarki lewisi), as a function of discharge in the river. This approach used a combination of georeferenced field data for each study site combined with a two-dimensional hydraulic simulation of river hydraulic characteristics. The hydraulic simulations were combined with habitat suitability criteria in a GIS analysis format to determine habitat area as a function of discharge. Results of the analysis showed that habitat area is more available at lower discharges than higher discharges and that in comparison of the pre-dam hydrology with post-dam hydrology, the stable pre-dam baseflows provided more stable habitat than the highly variable flow regime during both summer and winter baseflow post-dam periods. The variability week to week and day to day under post-dam conditions waters and dewaters stream margins. This forces sub-adult fish, in particular bull trout, to use less productive habitat during the night. There is a distinct difference between daytime and nighttime habitat use for bull trout sub-adults. The marginal areas that are constantly wet and then dried provide little in productivity for lower trophic levels and consequently become unproductive for higher trophic levels, especially bull trout sub-adults that use those areas as flows increase. A stable flow regime would be more productive than flow regimes with high variability week to week. The highly variable flows likely put stress on a bull trout subadult and west slope cutthroat trout, due to the additional movement required to find suitable habitat. The GIS approach presented here provides both a visual characterization of habitat as well as Arcview project data

  15. Effect of tides, river flow, and gate operations on entrainment of juvenile salmon into the interior Sacramento–San Joaquin River Delta

    Science.gov (United States)

    Perry, Russell W.; Brandes, Patricia L.; Burau, Jon R.; Sandstrom, Philip T.; Skalski, John R.

    2015-01-01

    Juvenile Chinook Salmon Oncorhynchus tshawytscha emigrating from natal tributaries of the Sacramento River, California, must negotiate the Sacramento-San Joaquin River Delta (hereafter, the Delta), a complex network of natural and man-made channels linking the Sacramento River with San Francisco Bay. Fish that enter the interior and southern Delta—the region to the south of the Sacramento River where water pumping stations are located—survive at a lower rate than fish that use alternative migration routes. Consequently, total survival decreases as the fraction of the population entering the interior Delta increases, thus spurring management actions to reduce the proportion of fish that are entrained into the interior Delta. To better inform management actions, we modeled entrainment probability as a function of hydrodynamic variables. We fitted alternative entrainment models to telemetry data that identified when tagged fish in the Sacramento River entered two river channels leading to the interior Delta (Georgiana Slough and the gated Delta Cross Channel). We found that the probability of entrainment into the interior Delta through both channels depended strongly on the river flow and tidal stage at the time of fish arrival at the river junction. Fish that arrived during ebb tides had a low entrainment probability, whereas fish that arrived during flood tides (i.e., when the river's flow was reversed) had a high probability of entering the interior Delta. We coupled our entrainment model with a flow simulation model to evaluate the effect of nighttime closures of the Delta Cross Channel gates on the daily probability of fish entrainment into the interior Delta. Relative to 24-h gate closures, nighttime closures increased daily entrainment probability by 3 percentage points on average if fish arrived at the river junction uniformly throughout the day and by only 1.3 percentage points if 85% of fish arrived at night. We illustrate how our model can be used to

  16. Tocantins river as an effective barrier to gene flow in Saguinus niger populations

    Directory of Open Access Journals (Sweden)

    Marcelo Vallinoto

    2006-01-01

    Full Text Available The Saguinus represent the basal genus of the Callitrichinae subfamily. Traditionally this genus is divided into three groups: Hairy, Mottled and Bare-face, however, molecular data failed to validate these groups as monophyletic units, as well as raised some subspecies to the species status. This is the case of the former subspecies Saguinus midas midas and S. midas niger, which are now considered as different species. In the present study, we sequenced a portion of the D-loop mtDNA region in populations from the East bank of the Xingu and from both banks of the Tocantins river, in order to test the effectiveness of large rivers as barriers to the gene flow in Saguinus. According to our results, the populations from the East and West banks of the Tocantins river are more divergent than true species like S. mystax and S. imperator. The Tocantins river may be acting as a barrier to gene flow, and consequently these very divergent populations may represent distinct taxonomic entities (species?.

  17. Flow prediction models using macroclimatic variables and multivariate statistical techniques in the Cauca River Valley

    International Nuclear Information System (INIS)

    Carvajal Escobar Yesid; Munoz, Flor Matilde

    2007-01-01

    The project this centred in the revision of the state of the art of the ocean-atmospheric phenomena that you affect the Colombian hydrology especially The Phenomenon Enos that causes a socioeconomic impact of first order in our country, it has not been sufficiently studied; therefore it is important to approach the thematic one, including the variable macroclimates associated to the Enos in the analyses of water planning. The analyses include revision of statistical techniques of analysis of consistency of hydrological data with the objective of conforming a database of monthly flow of the river reliable and homogeneous Cauca. Statistical methods are used (Analysis of data multivariante) specifically The analysis of principal components to involve them in the development of models of prediction of flows monthly means in the river Cauca involving the Lineal focus as they are the model autoregressive AR, ARX and Armax and the focus non lineal Net Artificial Network.

  18. Parameter estimation of an ARMA model for river flow forecasting using goal programming

    Science.gov (United States)

    Mohammadi, Kourosh; Eslami, H. R.; Kahawita, Rene

    2006-11-01

    SummaryRiver flow forecasting constitutes one of the most important applications in hydrology. Several methods have been developed for this purpose and one of the most famous techniques is the Auto regressive moving average (ARMA) model. In the research reported here, the goal was to minimize the error for a specific season of the year as well as for the complete series. Goal programming (GP) was used to estimate the ARMA model parameters. Shaloo Bridge station on the Karun River with 68 years of observed stream flow data was selected to evaluate the performance of the proposed method. The results when compared with the usual method of maximum likelihood estimation were favorable with respect to the new proposed algorithm.

  19. Three-dimensional simulation of flow, salinity, sediment, and radionuclide movements in the Hudson River estuary

    International Nuclear Information System (INIS)

    Onishi, Y.; Trent, D.S.

    1985-04-01

    The three-dimensional, finite difference model, FLESCOT simulates time-varying movements of flow, turbulent kinetic energy, salinity, water temperature, sediment, and contaminants in estuarine, coastal, and ocean waters. The model was applied to a 106-km (66-mi) reach of the Hudson River estuary in New York between Chelsea and the mouth of the river. It predicted the time-varying, three-dimensional distributions of tidal flow, salinity, three separate groups of sediments (i.e., sand, silt, and clay), and a radionuclide ( 137 Cs) in both dissolved and particulate (those sorbed by sediments) forms for over 40 days. The model also calculated riverbed elevation changes caused by sediment deposition and bed erosion, bed sediment size distribution and armoring, and distributions of the particulate 137 Cs sorbed by sand, silt, and clay in the bed

  20. Modelling maximum river flow by using Bayesian Markov Chain Monte Carlo

    Science.gov (United States)

    Cheong, R. Y.; Gabda, D.

    2017-09-01

    Analysis of flood trends is vital since flooding threatens human living in terms of financial, environment and security. The data of annual maximum river flows in Sabah were fitted into generalized extreme value (GEV) distribution. Maximum likelihood estimator (MLE) raised naturally when working with GEV distribution. However, previous researches showed that MLE provide unstable results especially in small sample size. In this study, we used different Bayesian Markov Chain Monte Carlo (MCMC) based on Metropolis-Hastings algorithm to estimate GEV parameters. Bayesian MCMC method is a statistical inference which studies the parameter estimation by using posterior distribution based on Bayes’ theorem. Metropolis-Hastings algorithm is used to overcome the high dimensional state space faced in Monte Carlo method. This approach also considers more uncertainty in parameter estimation which then presents a better prediction on maximum river flow in Sabah.

  1. Quantifying water requirements of riparian river red gum (Eucalyptus camaldulensis) in the Murray-Darling Basin, Australia: Implications for the management of environmental flows

    Science.gov (United States)

    Doody, Tanya M.; Colloff, Matthew J.; Davies, Micah; Koul, Vijay; Benyon, Richard G.; Nagler, Pamela L.

    2015-01-01

    Water resource development and drought have altered river flow regimes, increasing average flood return intervals across floodplains in the Murray-Darling Basin, Australia, causing health declines in riparian river red gum (Eucalyptus camaldulensis) forests and woodlands. Environmental flow allocations helped to alleviate water stress during the recent Millennium Drought (1997–2010), however, quantification of the flood frequency required to support healthy E. camaldulensis communities is still needed. We quantified water requirements of E. camaldulensis for two years across a flood gradient (trees inundated at frequencies of 1:2, 1:5 and 1:10 years) at Yanga National Park, New South Wales to help inform management decision-making and design of environmental flows. Sap flow, evaporative losses and soil moisture measurements were used to determine transpiration, evapotranspiration and plant-available soil water before and after flooding. A formula was developed using plant-available soil water post-flooding and average annual rainfall, to estimate maintenance time of soil water reserves in each flood frequency zone. Results indicated that soil water reserves could sustain 1:2 and 1:5 trees for 15 months and six years, respectively. Trees regulated their transpiration rates, allowing them to persist within their flood frequency zone, and showed reduction in active sapwood area and transpiration rates when flood frequencies exceeded 1:2 years. A leaf area index of 0.5 was identified as a potential threshold indicator of severe drought stress. Our results suggest environmental water managers may have greater flexibility to adaptively manage floodplains in order to sustain E. camaldulensis forests and woodlands than has been appreciated hitherto.

  2. Swarm slide - debris flow disaster induced by extreme rainfall in Hiroshima, August 2014 and lessons learnt in urban designing

    Science.gov (United States)

    Fukuoka, H.; Wang, C.

    2015-12-01

    Hiroshima city was hit by swarm debris flows along a narrow, and linear-shaped rain band of 2 km x 10 km which appeared in the early morning of August 20, 2014. Most of the flows were induced by shallow slide in the upstream. This disaster claimed 74 death, although this city experienced very similar disaster in 1999, claiming more than 30 residents lives. In the most severely affected debris flow torrent, more than 50 residents were killed. Most of the casualties arose in the wooden, vulnerable houses constructed in front of the exit of torrents. Points and lessons learnt from the disaster are as follows:1. Authors collected two types of sands from the source scar of the initial debris slides which induced debris flows. Tested by the ring shear apparatus under pore-pressure control condition, clear "Sliding surface liquefaction" was confirmed for both samples even under small normal stress, representing the small thickness of the slides. These results shows even instant excess pore pressure could initiate the slides and trigger slide-induced debris flow byundrained loading onto the torrent deposits.2. Apparently long-term land-use change since 1945 affected and raised the vulnerability of the community. Residential area had expanded into hill-slope (mountainous / semi-mountainous area) especially along the torrents. Those communities were developed on the past debris flow fan.3. As the devastated area is very close to downtown of Hiroshima city, it gave large societal impact to the Japanese citizens. After 1999 Hiroshima debris flow disaster, the Landslide disaster reduction law which intends to promote designation of landslide potential risk zones, was adopted in 2000. Immediately after 2014 disaster, national diet approved revision of the bill to promote rapid completion of the designation over the national territory. MLIT (Ministry of Land, Infrastructure, Tranportation and Tourism) decided to install X-band rain radars at more sites to cover whole city zones

  3. Were rivers flowing across the Sahara during the last interglacial? Implications for human migration through Africa.

    Directory of Open Access Journals (Sweden)

    Tom J Coulthard

    Full Text Available Human migration north through Africa is contentious. This paper uses a novel palaeohydrological and hydraulic modelling approach to test the hypothesis that under wetter climates c.100,000 years ago major river systems ran north across the Sahara to the Mediterranean, creating viable migration routes. We confirm that three of these now buried palaeo river systems could have been active at the key time of human migration across the Sahara. Unexpectedly, it is the most western of these three rivers, the Irharhar river, that represents the most likely route for human migration. The Irharhar river flows directly south to north, uniquely linking the mountain areas experiencing monsoon climates at these times to temperate Mediterranean environments where food and resources would have been abundant. The findings have major implications for our understanding of how humans migrated north through Africa, for the first time providing a quantitative perspective on the probabilities that these routes were viable for human habitation at these times.

  4. Can we predict the response of large sand bed rivers to changes in flow and sediment supply? The case of the Missouri River.

    Science.gov (United States)

    Viparelli, E.; Blum, M. D.

    2015-12-01

    In the past century engineering projects and changes in land use significantly modified the hydrology and the sediment supply of large sand bed rivers all over the world. Field studies documented the river responses to the imposed changes, which can be summarized as adjustments in channel geometry, slope, and/or characteristics of the bed material. Further, one-, two- and three-dimensional river morphodynamic models were used to predict the fluvial system response to the imposed changes at time scales ranging from few months up to several decades. Notwithstading this previous research effort, the spatial and temporal scales of river adjustment, as well as quantitative predictions of the river responses, are still a matter of debate due to the difficulties associated with the interpretation of limited field datasets and with the large scale sediment transport modeling. Here we present the preliminary results of a study of the Missouri River response to the construction of dams, i.e. reduction in flood flow and sediment supply. In particular, we first compare the numerical results of a one-dimensional model of river morphodynamics for large, low slope sand bed rivers with field data to validate the model. The validated model is then used to constrain the spatial and temporal scales of the river adjustment, i.e. bed degradation in the Missouri River case. In other words, our numerical work focuses on how the magnitude and speed of the wave of channel bed degradation changes in time and space for the Missouri River case and how these scales change for different values of the ratio between pre- and pos-dam flow rates, and pre- and post-dam sediment loads.

  5. Evaluation of Spatial Pattern of Altered Flow Regimes on a River Network Using a Distributed Hydrological Model.

    Science.gov (United States)

    Ryo, Masahiro; Iwasaki, Yuichi; Yoshimura, Chihiro; Saavedra V, Oliver C

    2015-01-01

    Alteration of the spatial variability of natural flow regimes has been less studied than that of the temporal variability, despite its ecological importance for river ecosystems. Here, we aimed to quantify the spatial patterns of flow regime alterations along a river network in the Sagami River, Japan, by estimating river discharge under natural and altered flow conditions. We used a distributed hydrological model, which simulates hydrological processes spatiotemporally, to estimate 20-year daily river discharge along the river network. Then, 33 hydrologic indices (i.e., Indicators of Hydrologic Alteration) were calculated from the simulated discharge to estimate the spatial patterns of their alterations. Some hydrologic indices were relatively well estimated such as the magnitude and timing of maximum flows, monthly median flows, and the frequency of low and high flow pulses. The accuracy was evaluated with correlation analysis (r > 0.4) and the Kolmogorov-Smirnov test (α = 0.05) by comparing these indices calculated from both observed and simulated discharge. The spatial patterns of the flow regime alterations varied depending on the hydrologic indices. For example, both the median flow in August and the frequency of high flow pulses were reduced by the maximum of approximately 70%, but these strongest alterations were detected at different locations (i.e., on the mainstream and the tributary, respectively). These results are likely caused by different operational purposes of multiple water control facilities. The results imply that the evaluation only at discharge gauges is insufficient to capture the alteration of the flow regime. Our findings clearly emphasize the importance of evaluating the spatial pattern of flow regime alteration on a river network where its discharge is affected by multiple water control facilities.

  6. Instream Flows Incremental Methodology :Kootenai River, Montana : Final Report 1990-2000.

    Energy Technology Data Exchange (ETDEWEB)

    Hoffman, Greg; Skaar, Don; Dalbey, Steve (Montana Department of Fish, Wildlife and Parks, Libby, MT)

    2002-11-01

    Regulated rivers such as the Kootenai River below Libby Dam often exhibit hydrographs and water fluctuation levels that are atypical when compared to non-regulated rivers. These flow regimes are often different conditions than those which native fish species evolved with, and can be important limiting factors in some systems. Fluctuating discharge levels can change the quantity and quality of aquatic habitat for fish. The instream flow incremental methodology (IFIM) is a tool that can help water managers evaluate different discharges in terms of their effects on available habitat for a particular fish species. The U.S. Fish and Wildlife Service developed the IFIM (Bovee 1982) to quantify changes in aquatic habitat with changes in instream flow (Waite and Barnhart 1992; Baldridge and Amos 1981; Gore and Judy 1981; Irvine et al. 1987). IFIM modeling uses hydraulic computer models to relate changes in discharge to changes in the physical parameters such as water depth, current velocity and substrate particle size, within the aquatic environment. Habitat utilization curves are developed to describe the physical habitat most needed, preferred or tolerated for a selected species at various life stages (Bovee and Cochnauer 1977; Raleigh et al. 1984). Through the use of physical habitat simulation computer models, hydraulic and physical variables are simulated for differing flows, and the amount of usable habitat is predicted for the selected species and life stages. The Kootenai River IFIM project was first initiated in 1990, with the collection of habitat utilization and physical hydraulic data through 1996. The physical habitat simulation computer modeling was completed from 1996 through 2000 with the assistance from Thomas Payne and Associates. This report summarizes the results of these efforts.

  7. Computer modeling of ground-water flow at the Savannah River Plant

    International Nuclear Information System (INIS)

    Root, R.W. Jr.

    1979-01-01

    Mathematical equations describing ground-water flow are used in a computer model being developed to predict the space-time distribution of hydraulic head beneath a part of the Savannah River Plant site. These equations are solved by a three-dimensional finite-difference scheme. Preliminary calibration of the hydraulic head model has been completed and calculated results compare well with water-level changes observed in the field. 10 figures, 1 table

  8. Environmental flow calculation for the maintenance of the water reserve of the Piaxtla River, Sinaloa, Mexico

    Directory of Open Access Journals (Sweden)

    Guadalupe de la Lanza Espino

    2014-03-01

    Full Text Available The calculation of river flows necessary to maintain the environmental services of the diverse river basins in Mexico has been an element to be considered in complying with the Mexican Norm and in allowing an adequate administration of water resources. Several methods have been proposed for this calculation, among which a very simple one is a hydrological method that requires a data base on runoff to determine the volume of water that ecosystem functions need. Hydrological methodology proposed by the NMX cited above, provides guidelines for establishing a regime as a percentage of average annual runoff and it is assumed maintain biological attributes at certain levels of conservation. It also analyzes the regime of seasonal normal flow for wet hydrological conditions, socks, dry and very dry, and the system of avenues (considered as the sudden increase in the volume and speed of the current in a river due to runoff resulting from rain cyclical or extraordinary, it is also known as flooding, considering at least three categories of avenues (intra-annual, annual and interannual low magnitude of average size with corresponding attributes of magnitude, duration, frequency, time of occurrence and rate exchange. For greater certainty calculation it will always be necessary to have records in the three levels of a basin. This level of analysis is to determine the final volume of ecological flow, considering the benchmark to achieve the previously defined environmental objective. For ecological calculation referred by the NMX, some fundamental aspects were considered, such as: ecology importance (which ranks among very high, high, medium and low based on the concepts of the rule itself ; use pressures (determined as the ratio percentage of the volume allocated over the concession between the annual average availability basin or aquifer, determined as high ≥ 80%, ≥ 40% high, medium and low ≥ 11% ≤ 10% ; the environmental objective (ecological

  9. CERCLA document flow: Compressing the schedule, saving costs, and expediting review at the Savannah River Site

    International Nuclear Information System (INIS)

    Hoffman, W.D.

    1991-01-01

    The purpose of this paper is to convey the logic of the CERCLA document flow including Work Plans, Characterization Studies, Risk Assessments, Remedial Investigations, Feasibility Studies, proposed plans, and Records of Decision. The intent is to show how schedules at the Savannah River Site are being formulated to accomplish work using an observational approach where carefully planned tasks can be initiated early and carried out in parallel. This paper will share specific proactive experience in working with the EPA to expedite projects, begin removal actions, take interim actions, speed document flow, and eliminate unnecessary documents from the review cycle

  10. Countercurrent flow-limiting characteristics of a Savannah River Plant control rod septifoil

    International Nuclear Information System (INIS)

    Anderson, J.L.

    1992-07-01

    Experiments were performed at the Idaho National Engineering Laboratory to investigate the counter-current flow limiting characteristics of a Savannah River Plant control rod septifoil assembly. These experiments were unheated, using air and water as the working fluids. Results are presented in terms of the Wallis flooding correlation for several different control rod configurations. Flooding was observed to occur in the vicinity of the inlet slots/holes of the septifoil, rather than within the rod bundle at the location of the minimum flow area. Nearly identical flooding characteristics of the septifoil were observed for configurations with zero, three, and four rods inserted, but significantly different results occurred with 5 rods inserted

  11. Small farm dams: impact on river flows and sustainability in a context of climate change

    Science.gov (United States)

    Habets, F.; Philippe, E.; Martin, E.; David, C. H.; Leseur, F.

    2014-10-01

    The repetition of droughts in France has led to a growing demand for irrigation water and consequently to an increase in requests for the construction of small farm dams. Although such dams are small, their accumulation in a basin affects river flows, because the water collected in these small farm dams is used for irrigation and thus does not contribute to river flow. In order to gain more insight into their impact on the annual and monthly discharges, especially during dry years, a small farm dam model was built and connected to a hydrometeorological model. Several scenarios with different volume capacities, filling catchment sizes and filling periods were tested for such dams. The results were analysed in a small basin in western France, where the pressure for building such dams is high, and then extended to the entire country. It was found that, due to the hydrometeorological conditions (mainly low precipitation compared to other regions in France), the development of small farm dams in north-western France would result in greater decreases in river flows and less efficient filling of small farm dams than in other regions. Therefore, such dams might not be as efficient as expected in supplying water to farmers when needed. Moreover, the ability to fill small farm dams is projected to decrease in a context of climate change, despite the uncertainty on the evolution of precipitation, thus worsening the situation.

  12. Influence of flow variability on floodplain formation and destruction, Little Missouri River, North Dakota

    Science.gov (United States)

    Miller, J.R.; Friedman, J.M.

    2009-01-01

    Resolving observations of channel change into separate planimetric measurements of floodplain formation and destruction reveals distinct relations between these processes and the flow regime. We analyzed a time sequence of eight bottomland images from 1939 to 2003 along the Little Missouri River, North Dakota, to relate geomorphic floodplain change to flow along this largely unregulated river. At the decadal scale, floodplain formation and destruction varied independently. Destruction was strongly positively correlated with the magnitude of infrequent high flows that recur every 5-10 yr, whereas floodplain formation was negatively correlated with the magnitude of frequent low flows exceeded 80% of the time. At the century scale, however, a climatically induced decrease in peak flows has reduced the destruction rate, limiting the area made available for floodplain formation. The rate of destruction was not uniform across the floodplain. Younger surfaces were consistently destroyed at a higher rate than older surfaces, suggesting that throughput of contaminants would have occurred more rapidly than predicted by models that assume uniform residence time of sediment across the floodplain. Maps of floodplain ages produced by analysis of sequential floodplain images are similar to maps of forest ages produced through dendrochronology, confirming the assumption of dendrogeomorphic studies that riparian tree establishment in this system is limited to recent channel locations. ?? 2009 Geological Society of America.

  13. Low Flow Regimes of the Tarim River Basin, China: Probabilistic Behavior, Causes and Implications

    Directory of Open Access Journals (Sweden)

    Peng Sun

    2018-04-01

    Full Text Available Droughts are a frequent occurrence in Xinjiang, China, and therefore fundamental to determining their hydrologic characteristics is low flow analysis. To that end, 11 probability distribution functions and 26 copulas functions were employed to analyze the changing characteristics of low flow regime (defined as seven-day low flow of the Tarim River Basin. Results indicated that: (1 The Wakeby distribution satisfactorily described the probabilistic behavior of the low flow regime. According to Akaike Information Criterion (AIC, Bayesian Information Criterions (BIC, maximum likelihood, and other residual-based metrics, Tawn copula, Farlie–Gumbel–Morgenstern copula and Frank copula were the best choice and used in this current study. (2 After 1987, hydrological droughts of longer return periods were prone to higher occurrence frequency. (3 The low flow volume has been increasing in recent years due to the temperature-induced increase of snowmelt and increasing precipitation. However, hydrological droughts can be expected to occur due to the massive increase in water demand from the development of irrigated agriculture, increasing arable land and livestock farming. As a result, the water shortage in the lower Tarim River Basin will be increasingly severe under the influence of climate change and human activities. To alleviate the shortage would call for the development of water-saving agricultural irrigation, water-saving technology, conservation of eco-environment and sustainable development of local socio-economy.

  14. Flow Regime Changes: From Impounding a Temperate Lowland River to Small Hydropower Operations

    Directory of Open Access Journals (Sweden)

    Petras Punys

    2015-07-01

    Full Text Available This article discusses the environmental issues facing small hydropower plants (SHPs operating in temperate lowland rivers of Lithuania. The research subjects are two medium head reservoir type hydro schemes considered within a context of the global fleet of SHPs in the country. This research considers general abiotic indicators (flow, level, water retention time in the reservoirs of the stream that may affect the aquatic systems. The main idea was to test whether the hydrologic regime has been altered by small hydropower dams. The analysis of changes in abiotic indicators is a complex process, including both pre- and post-reservoir construction and post commissioning of the SHPs under operation. Downstream hydrograph (flow and stage ramping is also an issue for operating SHPs that can result in temporary rapid changes in flow and consequently negatively impact aquatic resources. This ramping has been quantitatively evaluated. To avoid the risk of excessive flow ramping, the types of turbines available were evaluated and the most suitable types for the natural river flow regime were identified. The results of this study are to allow for new hydro schemes or upgrades to use water resources in a more sustainable way.

  15. Understanding controls on flow permanence in intermittent rivers to aid ecological research: integrating meteorology, geology and land cover

    Science.gov (United States)

    Intermittent rivers, those channels that periodically cease to flow, constitute over half of the total discharge of the global river network and will likely increase in their extent due to climatic shifts and/or water resources development. Burgeoning research on intermittent riv...

  16. On the role of the cross equatorial flow on summer monsoon rainfall over India using NCEP/NCAR reanalysis data

    Digital Repository Service at National Institute of Oceanography (India)

    RameshKumar, M.R.; Shenoi, S.S.C.; Schluessel, P.

    throughout the year and Bay of Bengal (Fig. 6f) a low level moisture con- vergence area for most of the months agrees well with the earlier results (Ramesh Kumar and Prasad, 1995). 5. Interannual Variability of Wind Speed, Specific Humidity and Precipitable... (d) Monsoon Years (Negative Sign Indicates Inward Flux and Positive Sign Indicates Outward Flow). Div and Con indicate Divergence and Convergence in the Box respectively. E & P indicate the Evaporation and Precipitation respectively. Units: 10 10 Tons...

  17. Hydrology and modeling of flow conditions at Bridge 339 and Mile 38-43, Copper River Highway, Alaska

    Science.gov (United States)

    Brabets, Timothy P.

    2012-01-01

    The Copper River basin, the sixth largest watershed in Alaska, drains an area of 24,200 square miles in south-central Alaska. This large, glacier-fed river flows across a wide alluvial fan before it enters the Gulf of Alaska. The Copper River Highway, which traverses the alluvial fan, has been affected by channel planform reconfiguration. Currently (2012), two areas of the Copper River Highway are at risk: at Mile 38-43, the road grade is too low and the highway could be flooded by high flows of the Copper River, and at Mile 36, the main channel of the Copper River has migrated directly toward Bridge 339. Because Bridge 339 was not designed and built to convey the main flow of the Copper River, as much as 50 feet of scour occurred at the piers in 2011. The piers can no longer absorb the lateral or vertical loads, resulting in closure of the bridge and the Copper River Highway. The U.S. Geological Survey Flow and Sediment Transport with Morphologic Evolution of Channels (FaSTMECH) model was used to simulate the flow of the Copper River and produce simulations of depth, water-surface elevation, and velocity. At the Mile 38-43 area, FaSTMECH was used to analyze the effects of raising the road grade 5 feet, and at Mile 36, FaSTMECH was used to analyze the effects of constructing a channel to divert flow away from Bridge 339. Results from FaSTMECH indicate that if raising the road grade 5 feet in the Mile 38-43 area, a flood with an annual exceedance probability of 2 percent (400,000 cubic feet per second) would not overtop the highway. In the Bridge 339 area, results from FaSTMECH indicate that a design channel could divert flows as much as 100,000 cubic feet per second away from Bridge 339.

  18. Coupling machine learning with mechanistic models to study runoff production and river flow at the hillslope scale

    Science.gov (United States)

    Marçais, J.; Gupta, H. V.; De Dreuzy, J. R.; Troch, P. A. A.

    2016-12-01

    Geomorphological structure and geological heterogeneity of hillslopes are major controls on runoff responses. The diversity of hillslopes (morphological shapes and geological structures) on one hand, and the highly non linear runoff mechanism response on the other hand, make it difficult to transpose what has been learnt at one specific hillslope to another. Therefore, making reliable predictions on runoff appearance or river flow for a given hillslope is a challenge. Applying a classic model calibration (based on inverse problems technique) requires doing it for each specific hillslope and having some data available for calibration. When applied to thousands of cases it cannot always be promoted. Here we propose a novel modeling framework based on coupling process based models with data based approach. First we develop a mechanistic model, based on hillslope storage Boussinesq equations (Troch et al. 2003), able to model non linear runoff responses to rainfall at the hillslope scale. Second we set up a model database, representing thousands of non calibrated simulations. These simulations investigate different hillslope shapes (real ones obtained by analyzing 5m digital elevation model of Brittany and synthetic ones), different hillslope geological structures (i.e. different parametrizations) and different hydrologic forcing terms (i.e. different infiltration chronicles). Then, we use this model library to train a machine learning model on this physically based database. Machine learning model performance is then assessed by a classic validating phase (testing it on new hillslopes and comparing machine learning with mechanistic outputs). Finally we use this machine learning model to learn what are the hillslope properties controlling runoffs. This methodology will be further tested combining synthetic datasets with real ones.

  19. Broad-scale patterns of invertebrate richness and community composition in temporary rivers: effects of flow intermittence

    Science.gov (United States)

    A central goal in ecology is to identify general relationships between environmental drivers and community patterns. In this study, we investigated the relationships between aquatic invertebrate communities and river flow intermittence across multiple continents. Particularly, we...

  20. Flow intermittence and ecosystem services in rivers of the Anthropocene_Figure 4_Journal of Applied Ecology

    Data.gov (United States)

    U.S. Environmental Protection Agency — Counts of ecosystem service status (provided, altered, and lost/absent) during three hydrological phases (flowing, pool, dry) typically seen in intermittent rivers...

  1. Grain-Size Analysis of Debris Flow Alluvial Fans in Panxi Area along Jinsha River, China

    Directory of Open Access Journals (Sweden)

    Wen Zhang

    2015-11-01

    Full Text Available The basic geometric parameters of 236 debris flow catchments were determined by interpreting SPOT5 remote sensing images with a resolution of 2.5 m in a 209 km section along the Jinsha River in the Panxi area, China. A total of 27 large-scale debris flow catchments were selected for detailed in situ investigation. Samples were taken from two profiles in the deposition zone for each debris flow catchment. The φ value gradation method of the grain size was used to obtain 54 histograms with abscissa in a logarithmic scale. Five types of debris flows were summarized from the outline of the histogram. Four grain size parameters were calculated: mean grain size, standard deviation, coefficient of skewness, and coefficient of kurtosis. These four values were used to evaluate the features of the histogram. The grain index that reflects the transport (kinetic energy information of debris flows was defined to describe the characteristics of the debris-flow materials. Furthermore, a normalized grain index based on the catchment area was proposed to allow evaluation of the debris flow mobility. The characteristics of the debris-flow materials were well-described by the histogram of grain-size distribution and the normalized grain index.

  2. Estuarine Response to River Flow and Sea-Level Rise under Future Climate Change and Human Development

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Zhaoqing; Wang, Taiping; Voisin, Nathalie; Copping, Andrea E.

    2015-04-01

    Understanding the response of river flow and estuarine hydrodynamics to climate change, land-use/land-cover change (LULC), and sea-level rise is essential to managing water resources and stress on living organisms under these changing conditions. This paper presents a modeling study using a watershed hydrology model and an estuarine hydrodynamic model, in a one-way coupling, to investigate the estuarine hydrodynamic response to sea-level rise and change in river flow due to the effect of future climate and LULC changes in the Snohomish River estuary, Washington, USA. A set of hydrodynamic variables, including salinity intrusion points, average water depth, and salinity of the inundated area, were used to quantify the estuarine response to river flow and sea-level rise. Model results suggest that salinity intrusion points in the Snohomish River estuary and the average salinity of the inundated areas are a nonlinear function of river flow, although the average water depth in the inundated area is approximately linear with river flow. Future climate changes will shift salinity intrusion points further upstream under low flow conditions and further downstream under high flow conditions. In contrast, under the future LULC change scenario, the salinity intrusion point will shift downstream under both low and high flow conditions, compared to present conditions. The model results also suggest that the average water depth in the inundated areas increases linearly with sea-level rise but at a slower rate, and the average salinity in the inundated areas increases linearly with sea-level rise; however, the response of salinity intrusion points in the river to sea-level rise is strongly nonlinear.

  3. Combined Flow Abstraction and Climate Change Impacts on an Aggrading Alpine River

    Science.gov (United States)

    Bakker, M.; Costa, A.; Silva, T. A.; Stutenbecker, L.; Girardclos, S.; Loizeau, J.-L.; Molnar, P.; Schlunegger, F.; Lane, S. N.

    2018-01-01

    Recent climatic warming and associated glacial retreat may have a large impact on sediment release and transfer in Alpine river basins. Concurrently, the sediment transport capacity of many European Alpine streams is affected by hydropower exploitation, notably where flow is abstracted but the sediment supply downstream is maintained. Here, we investigate the combined effects of climate change and flow abstraction on morphodynamics and sediment transfer in the Borgne River, Switzerland. From photogrammetrically derived historical Digital Elevation Models (DEMs), we find considerable net aggradation of the braided river bed (up to 5 m) since the onset of flow abstraction in 1963. Reaches responded through bed level steepening which was strongest in the upper most reach. Widespread aggradation however did not commence until the onset of glacier retreat in the late 1980s and the dry and warm years of the early 1990s. Upstream flow intake data shows that this aggradation coincided with an increase in sediment supply, although aggradation accounts for no more than 25% of supplied material. The remainder was transferred through the studied reaches. Estimations of bed load transport capacity indicate that flow abstraction reduces transport capacity by 1-2 orders of magnitude. While residual transport rates vary with morphological evolution, they are in the same order of magnitude as the sediment supply rates, which is why significant transport remains. However, the reduction in transport capacity makes the system more sensitive to short-term (annual) changes in climate-driven hydrological variability and climate-induced changes in intake management and sediment delivery rates.

  4. Probability modeling of high flow extremes in Yingluoxia watershed, the upper reaches of Heihe River basin

    Science.gov (United States)

    Li, Zhanling; Li, Zhanjie; Li, Chengcheng

    2014-05-01

    Probability modeling of hydrological extremes is one of the major research areas in hydrological science. Most basins in humid and semi-humid south and east of China are concerned for probability modeling analysis of high flow extremes. While, for the inland river basin which occupies about 35% of the country area, there is a limited presence of such studies partly due to the limited data availability and a relatively low mean annual flow. The objective of this study is to carry out probability modeling of high flow extremes in the upper reach of Heihe River basin, the second largest inland river basin in China, by using the peak over threshold (POT) method and Generalized Pareto Distribution (GPD), in which the selection of threshold and inherent assumptions for POT series are elaborated in details. For comparison, other widely used probability distributions including generalized extreme value (GEV), Lognormal, Log-logistic and Gamma are employed as well. Maximum likelihood estimate is used for parameter estimations. Daily flow data at Yingluoxia station from 1978 to 2008 are used. Results show that, synthesizing the approaches of mean excess plot, stability features of model parameters, return level plot and the inherent independence assumption of POT series, an optimum threshold of 340m3/s is finally determined for high flow extremes in Yingluoxia watershed. The resulting POT series is proved to be stationary and independent based on Mann-Kendall test, Pettitt test and autocorrelation test. In terms of Kolmogorov-Smirnov test, Anderson-Darling test and several graphical diagnostics such as quantile and cumulative density function plots, GPD provides the best fit to high flow extremes in the study area. The estimated high flows for long return periods demonstrate that, as the return period increasing, the return level estimates are probably more uncertain. The frequency of high flow extremes exhibits a very slight but not significant decreasing trend from 1978 to

  5. Influence of Flow Regulation on Summer Water Temperature: Sauce Grande River, Argentina

    Science.gov (United States)

    Casado, A.; Hannah, D. M.; Peiry, J.; Campo, A. M.

    2012-12-01

    This study quantifies the effects of the Paso de las Piedras Dam on the thermal behaviour of the Sauce Grande River, Argentina, during a summer season. A 30-day data set of continuous hourly data was assembled for eight stream temperature gauging sites deployed above and below the impoundment. Time series span the hottest period recorded during summer 2009 to evaluate variations in river water temperature under strong meteorological influence. The methods include: (i) analysis of the time series by inspecting the absolute differences in daily data (magnitude, timing, frequency, duration and rate of change), (ii) classification of diurnal regimes by using a novel regime 'shape' and 'magnitude' classifying method (RSMC), and (ii) quantification of the sensitivity of water temperature regimes to air temperature by computation of a novel sensitivity index (SI). Results showed that fluctuations in daily water temperatures were linked to meteorological drivers; however, spatial variability in the shape and the magnitude of the thermographs revealed the effects of the impoundment in regulating the thermal behaviour of the river downstream. An immediate cooling effect below the dam was evident. Mean daily temperatures were reduced in up to 4 °C, and described a warming trend in the downstream direction over a distance of at least 15 km (up to +2.3 °C). Diurnal cycles were reduced in amplitude and delayed in timing, and revealed a dominance of regime magnitude stability and regime shape climatic insensitivity over a distance of 8 km downstream. These findings provide new information about the water quality of the Sauce Grande River and inform management of flows to maintain the ecological integrity of the river system. Also, they motivate further analysis of potential correlates under varying hydrological and meteorological conditions. The methods presented herein have wider applicability for quantifying river thermal regimes and their sensitivity to climate and other

  6. Development of a stream-aquifer numerical flow model to assess river water management under water scarcity in a Mediterranean basin.

    Science.gov (United States)

    Mas-Pla, Josep; Font, Eva; Astui, Oihane; Menció, Anna; Rodríguez-Florit, Agustí; Folch, Albert; Brusi, David; Pérez-Paricio, Alfredo

    2012-12-01

    Stream flow, as a part of a basin hydrological cycle, will be sensible to water scarcity as a result of climate change. Stream vulnerability should then be evaluated as a key component of the basin water budget. Numerical flow modeling has been applied to an alluvial formation in a small mountain basin to evaluate the stream-aquifer relationship under these future scenarios. The Arbúcies River basin (116 km(2)) is located in the Catalan Inner Basins (NE Spain) and its lower reach, which is related to an alluvial aquifer, usually becomes dry during the summer period. This study seeks to determine the origin of such discharge losses whether from natural stream leakage and/or induced capture due to groundwater withdrawal. Our goal is also investigating how discharge variations from the basin headwaters, representing potential effects of climate change, may affect stream flow, aquifer recharge, and finally environmental preservation and human supply. A numerical flow model of the alluvial aquifer, based on MODFLOW and especially in the STREAM routine, reproduced the flow system after the usual calibration. Results indicate that, in the average, stream flow provides more than 50% of the water inputs to the alluvial aquifer, being responsible for the amount of stored water resources and for satisfying groundwater exploitation for human needs. Detailed simulations using daily time-steps permit setting threshold values for the stream flow entering at the beginning of the studied area so surface discharge is maintained along the whole watercourse and ecological flow requirements are satisfied as well. The effects of predicted rainfall and temperature variations on the Arbúcies River alluvial aquifer water balance are also discussed from the outcomes of the simulations. Finally, model results indicate the relevance of headwater discharge management under future climate scenarios to preserve downstream hydrological processes. They also point out that small mountain basins

  7. Heterogeneity of Dutch rainfall

    NARCIS (Netherlands)

    Witter, J.V.

    1984-01-01

    Rainfall data for the Netherlands have been used in this study to investigate aspects of heterogeneity of rainfall, in particular local differences in rainfall levels, time trends in rainfall, and local differences in rainfall trend. The possible effect of urbanization and industrialization on the

  8. Assessment of Environmental Flows for the Rivers of Western Ganges Delta with Special Reference to Indian Sundarban

    Science.gov (United States)

    Bhadra, T.; Hazra, S.; Ghosh, S.; Barman, B. C.

    2016-12-01

    The Indian Sundarban, situated on the western tide-dominated part of the Ganges delta was formed by the sedimentation of the Ganges and its tributaries. Freshwater is a scarce resource in the Sundarban though it is traversed by rivers. Most of the rivers of Western Ganges Delta, which used to nourish the Sundarban, have become defunct with the passage of time. To ensure sustainable flow and to enhance the flow-dependent ecosystem services in this region, assessment of environmental flows within the system is required. A pilot assessment of environment flows, supported by IUCN has been carried out in some specific river reaches of Western Ganges Delta under the present study. The holistic Building Block Methodology (BBM) has been modified and used for the assessment of environmental flows. In the modified BBM, three distinctive blocks namely Hydro-Morphology, Ecology and Socio-Economy have been selected and indicators like Ganges Dolphin (Platanista gangetica), Sundari tree (Heritiera fomes) and Hilsa fish (Tenualosa ilisha) etc. have been determined to assess the environmental flows. As the discharge data of the selected rivers are restricted in the public domain, the SWAT model has been run to generate the discharge data of the classified rivers. The Hydraulic model, HEC-RAS has been calibrated in the selected River reaches to assess the habitat availability and its changes for indicator species under different flow condition. The study reveals that River Bhagirathi-Hugli requires 150-427 cumec additional water in monsoon and 850-1127 cumec additional water in post-monsoon months for Hilsa migration, whereas 327-486 cumec additional water in pre-monsoon and dry season and 227-386 cumec additional water in post-monsoon months are required for Dolphin movement. Flow requirement of river Ichhamati has also been estimated under the present study. The total required flow for the Sundarban ecosystem to reduce the salinity level from 30ppt to 14ppt during the dry and pre

  9. Development of an Environmental Flow Framework for the McKenzie River Basin, Oregon

    Science.gov (United States)

    Risley, John; Wallick, J. Rose; Waite, Ian; Stonewall, Adam J.

    2010-01-01

    The McKenzie River is a tributary to the Willamette River in northwestern Oregon. The McKenzie River is approximately 90 miles in length and has a drainage area of approximately 1,300 square miles. Two major flood control dams, a hydropower dam complex, and two hydropower canals significantly alter streamflows in the river. The structures reduce the magnitude and frequency of large and small floods while increasing the annual 7-day minimum streamflows. Stream temperatures also have been altered by the dams and other anthropogenic factors, such as the removal of riparian vegetation and channel simplification. Flow releases from one of the flood control dams are cooler in the summer and warmer in the fall in comparison to unregulated flow conditions before the dam was constructed. In 2006, the Oregon Department of Environmental Quality listed a total of 112.4, 6.3, and 55.7 miles of the McKenzie River basin mainstem and tributary stream reaches as thermally impaired for salmonid rearing, salmonid spawning, and bull trout, respectively. The analyses in this report, along with previous studies, indicate that dams have altered downstream channel morphology and ecologic communities. In addition to reducing the magnitude and frequency of floods, dams have diminished sediment transport by trapping bed material. Other anthropogenic factors, such as bank stabilization, highway construction, and reductions of in-channel wood, also have contributed to the loss of riparian habitat. A comparison of aerial photography taken in 1939 and 2005 showed substantial decreases in secondary channels, gravel bars, and channel sinuosity, particularly along the lower alluvial reaches of the McKenzie River. In addition, bed armoring and incision may contribute to habitat degradation, although further study is needed to determine the extent of these processes. Peak streamflow reduction has led to vegetation colonization and stabilization of formerly active bar surfaces. The large flood control

  10. Turbulent flow structure at a discordant river confluence: Asymmetric jet dynamics with implications for channel morphology

    Science.gov (United States)

    Sukhodolov, Alexander N.; Krick, Julian; Sukhodolova, Tatiana A.; Cheng, Zhengyang; Rhoads, Bruce L.; Constantinescu, George S.

    2017-06-01

    Only a handful of field studies have examined turbulent flow structure at discordant confluences; the dynamics of flow at such confluences have mainly been examined in the laboratory. This paper reports results of a field-based investigation of turbulent flow structure at a discordant river confluence. These results support the hypothesis that flow at a discordant alluvial confluence with a velocity ratio greater than 2 exhibits jet-like characteristics. Scaling analysis shows that the dynamics of the jet core are quite similar to those of free jets but that the complex structure of flow at the confluence imposes strong effects that can locally suppress or enhance the spreading rate of the jet. This jet-like behavior of the flow has important implications for morphodynamic processes at these types of confluences. The highly energetic core of the jet at this discordant confluence is displaced away from the riverbed, thereby inhibiting scour; however, helical motion develops adjacent to the jet, particularly at high flows, which may promote scour. Numerical experiments demonstrate that the presence or absence of a depositional wedge at the mouth of the tributary can strongly influence detachment of the jet from the bed and the angle of the jet within the confluence.

  11. Identification of appropriate lags and temporal resolutions for low flow indicators in the River Rhine to forecast low flows with different lead times

    NARCIS (Netherlands)

    Demirel, M.C.; Booij, Martijn J.; Hoekstra, Arjen Ysbert

    2013-01-01

    The aim of this paper is to assess the relative importance of low flow indicators for the River Rhine and to identify their appropriate temporal lag and resolution. This is done in the context of low flow forecasting with lead times of 14 and 90 days. First, the Rhine basin is subdivided into seven

  12. Flow and Residence Times of Dynamic River Bank Storage and Sinuosity-Driven Hyporheic Exchange

    Science.gov (United States)

    Gomez-Velez, J. D.; Wilson, J. L.; Cardenas, M. B.; Harvey, J. W.

    2017-10-01

    Hydrologic exchange fluxes (HEFs) vary significantly along river corridors due to spatiotemporal changes in discharge and geomorphology. This variability results in the emergence of biogeochemical hot-spots and hot-moments that ultimately control solute and energy transport and ecosystem services from the local to the watershed scales. In this work, we use a reduced-order model to gain mechanistic understanding of river bank storage and sinuosity-driven hyporheic exchange induced by transient river discharge. This is the first time that a systematic analysis of both processes is presented and serves as an initial step to propose parsimonious, physics-based models for better predictions of water quality at the large watershed scale. The effects of channel sinuosity, alluvial valley slope, hydraulic conductivity, and river stage forcing intensity and duration are encapsulated in dimensionless variables that can be easily estimated or constrained. We find that the importance of perturbations in the hyporheic zone's flux, residence times, and geometry is mainly explained by two-dimensionless variables representing the ratio of the hydraulic time constant of the aquifer and the duration of the event (Γd) and the importance of the ambient groundwater flow (Δh∗). Our model additionally shows that even systems with small sensitivity, resulting in small changes in the hyporheic zone extent, are characterized by highly variable exchange fluxes and residence times. These findings highlight the importance of including dynamic changes in hyporheic zones for typical HEF models such as the transient storage model.

  13. 1992 Columbia River Salmon Flow Measures Options Analysis/EIS : Appendices.

    Energy Technology Data Exchange (ETDEWEB)

    1992-01-01

    This Options Analysis/Environmental Impact Statement (OA/EIS) identifies, presents effects of, and evaluates the potential options for changing instream flow levels in efforts to increase salmon populations in the lower Columbia and Snake rivers. The potential actions would be implemented during 1992 to benefit juvenile and adult salmon during migration through eight run-of-river reservoirs. The Corps of Engineers (Corps) prepared this document in cooperation with the Bonneville Power Administration and the Bureau of Reclamation. The US Fish and Wildlife Service (FWS) is a participating agency. The text and appendices of the document describe the characteristics of 10 Federal projects and one private water development project in the Columbia River drainage basin. Present and potential operation of these projects and their effects on the salmon that spawn and rear in the Columbia and Snake River System are presented. The life history, status, and response of Pacific salmon to current environmental conditions are described. The document concludes with an evaluation of the potential effects that could result from implementing proposed actions. The conclusions are based on evaluation of existing data, utilization of numerical models, and application of logical inference. This volume contains the appendices.

  14. 1992 Columbia River salmon flow measures Options Analysis/EIS: Appendices

    International Nuclear Information System (INIS)

    1992-01-01

    This Options Analysis/Environmental Impact Statement (OA/EIS) identifies, presents effects of, and evaluates the potential options for changing instream flow levels in efforts to increase salmon populations in the lower Columbia and Snake rivers. The potential actions would be implemented during 1992 to benefit juvenile and adult salmon during migration through eight run-of-river reservoirs. The Corps of Engineers (Corps) prepared this document in cooperation with the Bonneville Power Administration and the Bureau of Reclamation. The US Fish and Wildlife Service (FWS) is a participating agency. The text and appendices of the document describe the characteristics of 10 Federal projects and one private water development project in the Columbia River drainage basin. Present and potential operation of these projects and their effects on the salmon that spawn and rear in the Columbia and Snake River System are presented. The life history, status, and response of Pacific salmon to current environmental conditions are described. The document concludes with an evaluation of the potential effects that could result from implementing proposed actions. The conclusions are based on evaluation of existing data, utilization of numerical models, and application of logical inference. This volume contains the appendices

  15. River adjustments under varying flow and sediment sypply regimes. The role of hydrograh shape

    Science.gov (United States)

    Ferrer-Boix, C.; Elgueta, M. A.; Hassan, M. A.

    2016-12-01

    This research aims to explore how sediment supply conditions and hydrograph shape influence bed surface evolution, vertical and downstream sediment sorting, and sediment transport in gravel bed streams. While a significant body of research has been focused on channel evolution under constant flow regimes, few studies have focused on the impacts of flow variations in channel adjustments. Particularly, we are interested in examining the impact of the sediment supply regime and hydrograph magnitude and duration on channel adjustments and sediment transport rates. To this end, we conducted a set of experiments in a 0.8 m-wide, 5 m-long tilting flume. Flow discharge during the runs was increased and decreased at steps of certain duration allowing us to vary the steepness of rising and falling limbs of hydrographs. The influence of hydrograph shape (symmetrical and asymmetrical) on river morphodynamics was tested. Flow rates during the experiments ranged from 30 l/s to 70 l/s. Some of the experiments were conducted under no feed conditions while others were carried out with sediment supply, which ranged from 10 kg/h to 80 kg/h. The feed texture in these latter runs was identical to that of the original mixture (Dmin = 0.5 mm, Dmax = 64 mm, Dg = 5.65 mm and σg = 3.05). Initial bed slope and surface configuration were obtained after varying times of conditioning under constant flow and no feed. Finally, we conducted equilibrium experiments under constant flow and sediment supply that were used as reference. All these sets of experiments benefited from a very detailed and extensive data monitoring which allowed us to provide a unique description or river adjustments under varying flow conditions. Data acquisition included: 1) bed surface images covering the entire flume, 2) bed scans at 2 mm resolution of the whole flume and 3) real-time measurements of bedload transport (rate and texture) at the outlet of the flume. This set up allows us to obtain fractional particle

  16. Predictability of soil moisture and river flows over France for the spring season

    Science.gov (United States)

    Singla, S.; Céron, J.-P.; Martin, E.; Regimbeau, F.; Déqué, M.; Habets, F.; Vidal, J.-P.

    2012-01-01

    Sources of spring predictability of the hydrological system over France were studied on a seasonal time scale over the 1960-2005 period. Two random sampling experiments were set up in order to test the relative importance of the land surface initial state and the atmospheric forcing. The experiments were based on the SAFRAN-ISBA-MODCOU hydrometeorological suite which computed soil moisture and river flow forecasts over a 8-km grid and more than 880 river-gauging stations. Results showed that the predictability of hydrological variables primarily depended on the seasonal atmospheric forcing (mostly temperature and total precipitation) over most plains, whereas it mainly depended on snow cover over high mountains. However, the Seine catchment area was an exception as the skill mainly came from the initial state of its large and complex aquifers. Seasonal meteorological hindcasts with the Météo-France ARPEGE climate model were then used to force the ISBA-MODCOU hydrological model and obtain seasonal hydrological forecasts from 1960 to 2005 for the entire March-April-May period. Scores from this seasonal hydrological forecasting suite could thus be compared with the random atmospheric experiment. Soil moisture and river flow skill scores clearly showed the added value in seasonal meteorological forecasts in the north of France, contrary to the Mediterranean area where values worsened.

  17. Physical habitat classification and instream flow modeling to determine habitat availability during low-flow periods, North Fork Shenandoah River, Virginia

    Science.gov (United States)

    Krstolic, Jennifer L.; Hayes, Donald C.; Ruhl, Peter M.

    2006-01-01

    Increasing development and increasing water withdrawals for public, industrial, and agricultural water supply threaten to reduce streamflows in the Shenandoah River basin in Virginia. Water managers need more information to balance human water-supply needs with the daily streamflows necessary for maintaining the aquatic ecosystems. To meet the need for comprehensive information on hydrology, water supply, and instream-flow requirements of the Shenandoah River basin, the U.S. Geological Survey and the Northern Shenandoah Valley Regional Commission conducted a cooperative investigation of habitat availability during low-flow periods on the North Fork Shenandoah River. Historic streamflow data and empirical data on physical habitat, river hydraulics, fish community structure, and recreation were used to develop a physical habitat simulation model. Hydraulic measurements were made during low, medium, and high flows in six reaches at a total of 36 transects that included riffles, runs, and pools, and that had a variety of substrates and cover types. Habitat suitability criteria for fish were developed from detailed fish-community sampling and microhabitat observations. Fish were grouped into four guilds of species and life stages with similar habitat requirements. Simulated habitat was considered in the context of seasonal flow regimes to show the availability of flows that sustain suitable habitat during months when precipitation and streamflow are scarce. The North Fork Shenandoah River basin was divided into three management sections for analysis purposes: the upper section, middle section, and lower section. The months of July, August, and September were chosen to represent a low-flow period in the basin with low mean monthly flows, low precipitation, high temperatures, and high water withdrawals. Exceedance flows calculated from the combined data from these three months describe low-flow periods on the North Fork Shenandoah River. Long-term records from three

  18. Pulsed flows, tributary inputs, and food web structure in a highly regulated river

    Science.gov (United States)

    Sabo, John; Caron, Melanie; Doucett, Richard R.; Dibble, Kimberly L.; Ruhi, Albert; Marks, Jane; Hungate, Bruce; Kennedy, Theodore A.

    2018-01-01

    1.Dams disrupt the river continuum, altering hydrology, biodiversity, and energy flow. Although research indicates that tributary inputs have the potential to dilute these effects, knowledge at the food web level is still scarce.2.Here we examined the riverine food web structure of the Colorado River below Glen Canyon Dam, focusing on organic matter sources, trophic diversity, and food chain length. We asked how these components respond to pulsed flows from tributaries following monsoon thunderstorms that seasonally increase streamflow in the American Southwest.3.Tributaries increased the relative importance of terrestrial organic matter, particularly during the wet season below junctures of key tributaries. This contrasted with the algal-based food web present immediately below Glen Canyon Dam.4.Tributary inputs during the monsoon also increased trophic diversity and food chain length: food chain length peaked below the confluence with the largest tributary (by discharge) in Grand Canyon, increasing by >1 trophic level over a 4-5 kilometre reach possibly due to aquatic prey being flushed into the mainstem during heavy rain events.5.Our results illustrate that large tributaries can create seasonal discontinuities, influencing riverine food web structure in terms of allochthony, food web diversity, and food chain length.6.Synthesis and applications. Pulsed flows from unregulated tributaries following seasonal monsoon rains increase the importance of terrestrially-derived organic matter in large, regulated river food webs, increasing food chain length and trophic diversity downstream of tributary inputs. Protecting unregulated tributaries within hydropower cascades may be important if we are to mitigate food web structure alteration due to flow regulation by large dams. This is critical in the light of global hydropower development, especially in megadiverse, developing countries where dam placement (including completed and planned structures) is in tributaries.

  19. Water velocity and the nature of critical flow in large rapids on the Colorado River, Utah

    Science.gov (United States)

    Magirl, Christopher S.; Gartner, Jeffrey W.; Smart, Graeme M.; Webb, Robert H.

    2009-01-01

    Rapids are an integral part of bedrock‐controlled rivers, influencing aquatic ecology, geomorphology, and recreational value. Flow measurements in rapids and high‐gradient rivers are uncommon because of technical difficulties associated with positioning and operating sufficiently robust instruments. In the current study, detailed velocity, water surface, and bathymetric data were collected within rapids on the Colorado River in eastern Utah. With the water surface survey, it was found that shoreline‐based water surface surveys may misrepresent the water surface slope along the centerline of a rapid. Flow velocities were measured with an ADCP and an electronic pitot‐static tube. Integrating multiple measurements, the ADCP returned velocity data from the entire water column, even in sections of high water velocity. The maximum mean velocity measured with the ADCP was 3.7 m/s. The pitot‐static tube, while capable of only point measurements, quantified velocity 0.39 m below the surface. The maximum mean velocity measured with the pitot tube was 5.2 m/s, with instantaneous velocities up to 6.5 m/s. Analysis of the data showed that flow was subcritical throughout all measured rapids with a maximum measured Froude number of 0.7 in the largest measured rapids. Froude numbers were highest at the entrance of a given rapid, then decreased below the first breaking waves. In the absence of detailed bathymetric and velocity dat