WorldWideScience

Sample records for monthly river flow

  1. Investigation of Shannon and PolyWog Wavelet Neural Networks In Monthly River Flow Modeling

    Science.gov (United States)

    Abghari, H.; van de Giesen, N.; Noury, M.

    2009-04-01

    Intelligence models consist of distributed parallel processors that learn to reproduce the relationship between input and output signals and present the best topology of patterns simulation. Due to nonlinearity of hydrological events the learning process has restrictions . In this study, using a combination of Wavelet theory and a Multi Layer Perceptron Network, two Wavelet Neural Network models for monthly flow of Nazloochaei River basin in Iran were developed. Instead of using common sigmoid activation functions in the MLP network a wavelet function was used, The hybrid wavelet neural network (WNNs) employing a nonlinear wavelet basis was developed as an alternative approach to nonlinear fitting. Result of MLP base model show the 86% in training and 79% in model testing. Results of the MLP base model show a goodness of fit of 86% in training and 79% in model testing. Results shows that the Polywog neural network with the best topology has a 94% accuracy in the training phase and 89% in testing of model. The Shannon neural network with the best topology produces 79% accuracy in training phase and 61% in testing of model. Comparison of WNN and MLP shows that Polywog wavelet could have better accuracy in time series modeling. Classic sigmoid activation functions in the MLP network show better results than the Shannon wavelet. Keywords: Shannon and PolyWog Wavelet, Wavelet Neural Networks, Nazloochaei River Basin, River Flow Modeling.

  2. Monthly river flow forecasting using artificial neural network and support vector regression models coupled with wavelet transform

    Science.gov (United States)

    Kalteh, Aman Mohammad

    2013-04-01

    Reliable and accurate forecasts of river flow is needed in many water resources planning, design development, operation and maintenance activities. In this study, the relative accuracy of artificial neural network (ANN) and support vector regression (SVR) models coupled with wavelet transform in monthly river flow forecasting is investigated, and compared to regular ANN and SVR models, respectively. The relative performance of regular ANN and SVR models is also compared to each other. For this, monthly river flow data of Kharjegil and Ponel stations in Northern Iran are used. The comparison of the results reveals that both ANN and SVR models coupled with wavelet transform, are able to provide more accurate forecasting results than the regular ANN and SVR models. However, it is found that SVR models coupled with wavelet transform provide better forecasting results than ANN models coupled with wavelet transform. The results also indicate that regular SVR models perform slightly better than regular ANN models.

  3. Future Flows Hydrology: an ensemble of daily river flow and monthly groundwater levels for use for climate change impact assessment across Great Britain

    Directory of Open Access Journals (Sweden)

    C. Prudhomme

    2012-12-01

    Full Text Available The dataset Future Flows Hydrology was developed as part of the project "Future Flows and Groundwater Levels" to provide a consistent set of transient daily river flow and monthly groundwater levels projections across England, Wales and Scotland to enable the investigation of the role of climate variability on river flow and groundwater levels nationally and how this may change in the future.

    Future Flows Hydrology is derived from Future Flows Climate, a national ensemble projection derived from the Hadley Centre's ensemble projection HadRM3-PPE to provide a consistent set of climate change projections for the whole of Great Britain at both space and time resolutions appropriate for hydrological applications. Three hydrological models and one groundwater level model were used to derive Future Flows Hydrology, with 30 river sites simulated by two hydrological models to enable assessment of hydrological modelling uncertainty in studying the impact of climate change on the hydrology.

    Future Flows Hydrology contains an 11-member ensemble of transient projections from January 1951 to December 2098, each associated with a single realisation from a different variant of HadRM3 and a single hydrological model. Daily river flows are provided for 281 river catchments and monthly groundwater levels at 24 boreholes as .csv files containing all 11 ensemble members. When separate simulations are done with two hydrological models, two separate .csv files are provided.

    Because of potential biases in the climate-hydrology modelling chain, catchment fact sheets are associated with each ensemble. These contain information on the uncertainty associated with the hydrological modelling when driven using observed climate and Future Flows Climate for a period representative of the reference time slice 1961–1990 as described by key hydrological statistics. Graphs of projected changes for selected hydrological indicators are also provided for

  4. Future Flows Hydrology: an ensemble of daily river flow and monthly groundwater levels for use for climate change impact assessment across Great Britain

    Directory of Open Access Journals (Sweden)

    C. Prudhomme

    2013-03-01

    Full Text Available The dataset Future Flows Hydrology was developed as part of the project "Future Flows and Groundwater Levels'' to provide a consistent set of transient daily river flow and monthly groundwater level projections across England, Wales and Scotland to enable the investigation of the role of climate variability on river flow and groundwater levels nationally and how this may change in the future. Future Flows Hydrology is derived from Future Flows Climate, a national ensemble projection derived from the Hadley Centre's ensemble projection HadRM3-PPE to provide a consistent set of climate change projections for the whole of Great Britain at both space and time resolutions appropriate for hydrological applications. Three hydrological models and one groundwater level model were used to derive Future Flows Hydrology, with 30 river sites simulated by two hydrological models to enable assessment of hydrological modelling uncertainty in studying the impact of climate change on the hydrology. Future Flows Hydrology contains an 11-member ensemble of transient projections from January 1951 to December 2098, each associated with a single realisation from a different variant of HadRM3 and a single hydrological model. Daily river flows are provided for 281 river catchments and monthly groundwater levels at 24 boreholes as .csv files containing all 11 ensemble members. When separate simulations are done with two hydrological models, two separate .csv files are provided. Because of potential biases in the climate–hydrology modelling chain, catchment fact sheets are associated with each ensemble. These contain information on the uncertainty associated with the hydrological modelling when driven using observed climate and Future Flows Climate for a period representative of the reference time slice 1961–1990 as described by key hydrological statistics. Graphs of projected changes for selected hydrological indicators are also provided for the 2050s time slice

  5. Savannah River Laboratory monthly report, October 1991

    Energy Technology Data Exchange (ETDEWEB)

    Ferrell, J.M. (comp.)

    1991-01-01

    This document details monthly activities at the Savannah River Laboratory. Topics addressed are reactor operation, tritium facilities and production; separations operations; environmental concerns; and waste management. (FI)

  6. Savannah River Laboratory monthly report, October 1991

    Energy Technology Data Exchange (ETDEWEB)

    Ferrell, J.M. [comp.

    1991-12-31

    This document details monthly activities at the Savannah River Laboratory. Topics addressed are reactor operation, tritium facilities and production; separations operations; environmental concerns; and waste management. (FI)

  7. Savannah River Laboratory monthly report, September 1991

    Energy Technology Data Exchange (ETDEWEB)

    Ferrell, J.M. (comp.)

    1991-01-01

    This document details monthly activities at the Savannah River Laboratory. Topics addressed are reactor operation, tritium facilities and production; separation operations; environmental concerns; and waste management. (FI)

  8. Savannah River Laboratory monthly report, September 1991

    Energy Technology Data Exchange (ETDEWEB)

    Ferrell, J.M. [comp.

    1991-12-31

    This document details monthly activities at the Savannah River Laboratory. Topics addressed are reactor operation, tritium facilities and production; separation operations; environmental concerns; and waste management. (FI)

  9. Savannah River Laboratory monthly report, November 1991

    Energy Technology Data Exchange (ETDEWEB)

    Ferrell, J.M. [comp.

    1991-12-31

    This document details monthly activities at the Savannah River Laboratory. Topics addressed are reactor operation; tritium facilities and production; separation operations; environmental concerns; and waste management. (FI)

  10. Savannah River Laboratory monthly report, November 1991

    Energy Technology Data Exchange (ETDEWEB)

    Ferrell, J.M. (comp.)

    1991-01-01

    This document details monthly activities at the Savannah River Laboratory. Topics addressed are reactor operation; tritium facilities and production; separation operations; environmental concerns; and waste management. (FI)

  11. El-Niño/Southern Oscillation (ENSO) influences on monthly NO 3 load and concentration, stream flow and precipitation in the Little River Watershed, Tifton, Georgia (GA)

    Science.gov (United States)

    Keener, V. W.; Feyereisen, G. W.; Lall, U.; Jones, J. W.; Bosch, D. D.; Lowrance, R.

    2010-02-01

    SummaryAs climate variability increases, it is becoming increasingly critical to find predictable patterns that can still be identified despite overall uncertainty. The El-Niño/Southern Oscillation is the best known pattern. Its global effects on weather, hydrology, ecology and human health have been well documented. Climate variability manifested through ENSO has strong effects in the southeast United States, seen in precipitation and stream flow data. However, climate variability may also affect water quality in nutrient concentrations and loads, and have impacts on ecosystems, health, and food availability in the southeast. In this research, we establish a teleconnection between ENSO and the Little River Watershed (LRW), GA., as seen in a shared 3-7 year mode of variability for precipitation, stream flow, and nutrient load time series. Univariate wavelet analysis of the NINO 3.4 index of sea surface temperature (SST) and of precipitation, stream flow, NO 3 concentration and load time series from the watershed was used to identify common signals. Shared 3-7 year modes of variability were seen in all variables, most strongly in precipitation, stream flow and nutrient load in strong El Niño years. The significance of shared 3-7 year periodicity over red noise with 95% confidence in SST and precipitation, stream flow, and NO 3 load time series was confirmed through cross-wavelet and wavelet-coherence transforms, in which common high power and co-variance were computed for each set of data. The strongest 3-7 year shared power was seen in SST and stream flow data, while the strongest co-variance was seen in SST and NO 3 load data. The strongest cross-correlation was seen as a positive value between the NINO 3.4 and NO 3 load with a three-month lag. The teleconnection seen in the LRW between the NINO 3.4 index and precipitation, stream flow, and NO 3 load can be utilized in a model to predict monthly nutrient loads based on short-term climate variability

  12. Savannah River Technology Center, monthly report

    Energy Technology Data Exchange (ETDEWEB)

    1994-04-01

    This is the monthly report to detail the research currently being conducted at the Savannah River Technology Center. The areas of research are in Tritium, Seperation processes, Environmental Engineering, and Waste Management.

  13. Savannah River Laboratory monthly report, February 1992

    Energy Technology Data Exchange (ETDEWEB)

    Ferrell, J.M. [comp.; Ice, L.W. [ed.

    1992-02-01

    This report is a progress report for the Savannah River Laboratory for the month of February 1992. The progress and activities in six categories were described in the report. The categories are reactor, tritium, separations, environmental, waste management, and general. Each category described numerous and varied activities. Some examples of these activities described are such things as radiation monitoring, maintenance, modifications, and remedial action.

  14. Savannah River Technology Center. Monthly report

    Energy Technology Data Exchange (ETDEWEB)

    1994-02-01

    This document contains information about the research programs being conducted at the Savannah River Plant. Topics of discussion include: thermal cycling absorption process, development of new alloys, ion exchange, oxalate precipitation, calcination, environmental research, remedial action, ecological risk assessments, chemical analysis of salt cakes, natural phenomena hazards assessment, and sampling of soils and groundwater.

  15. Savannah River Technology Center monthly report

    Energy Technology Data Exchange (ETDEWEB)

    1994-03-01

    This document contains information about the research programs being conducted at the Savannah River Plant. Topics of discussion include: Acorn Cleaning Study, tritium, separation processes, bioremediation programs, environmental remediation, environmental sampling, waste management, statistical design, phase I array experiments, and, Monte Carlo Neutron Photon input files.

  16. SAVANNAH RIVER TECHNOLOGY CENTER MONTHLY REPORT AUGUST 1992

    Energy Technology Data Exchange (ETDEWEB)

    Ferrell, J.M.

    1999-06-21

    'This monthly report summarizes Programs and Accomplishments of the Savannah River Technology Center in support of activities at the Savannah River Site. The following categories are addressed: Reactor, Tritium, Separations, Environmental, Waste Management, General, and Items of Interest.'

  17. Savannah River Technology Center monthly report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-06-01

    This report for the month of June 1995 presents information on the typical topics of tritium processing, environmental studies, waste management issues, and miscellaneous projects. The document consists many small reports by individuals or small groups.

  18. Resilience of river flow regimes.

    Science.gov (United States)

    Botter, Gianluca; Basso, Stefano; Rodriguez-Iturbe, Ignacio; Rinaldo, Andrea

    2013-08-06

    Landscape and climate alterations foreshadow global-scale shifts of river flow regimes. However, a theory that identifies the range of foreseen impacts on streamflows resulting from inhomogeneous forcings and sensitivity gradients across diverse regimes is lacking. Here, we derive a measurable index embedding climate and landscape attributes (the ratio of the mean interarrival of streamflow-producing rainfall events and the mean catchment response time) that discriminates erratic regimes with enhanced intraseasonal streamflow variability from persistent regimes endowed with regular flow patterns. Theoretical and empirical data show that erratic hydrological regimes typical of rivers with low mean discharges are resilient in that they hold a reduced sensitivity to climate fluctuations. The distinction between erratic and persistent regimes provides a robust framework for characterizing the hydrology of freshwater ecosystems and improving water management strategies in times of global change.

  19. Savannah River Technology Center monthly report, September 1992

    Energy Technology Data Exchange (ETDEWEB)

    Ferrell, J.M. [comp.

    1992-09-01

    This is a monthly progress report from the Savannah River Laboratory for the month of September, 1992. It has sections dealing with work in the broad areas of reactor safety, tritium processes and absorption, separations programs and wastes, environmental concerns and responses, waste management practices, and general concerns.

  20. Columbia River flow-time calculations

    Energy Technology Data Exchange (ETDEWEB)

    Soldat, J.K.

    1962-07-01

    An appraisal of available data on flow times in the Columbia River between the reactor areas and Pasco was made to permit extrapolation of the flow-time curves to lower river flow rates. Comparisons were made between data collected by the US Corps of Engineers and environmental monitoring data and with the previously developed equation for flow times. New equations were developed to fit curves over the range (4 to 40) x 10/sup 4/CFS.

  1. Monthly to seasonal low flow prediction: statistical versus dynamical models

    Science.gov (United States)

    Ionita-Scholz, Monica; Klein, Bastian; Meissner, Dennis; Rademacher, Silke

    2016-04-01

    the Alfred Wegener Institute a purely statistical scheme to generate streamflow forecasts for several months ahead. Instead of directly using teleconnection indices (e.g. NAO, AO) the idea is to identify regions with stable teleconnections between different global climate information (e.g. sea surface temperature, geopotential height etc.) and streamflow at different gauges relevant for inland waterway transport. So-called stability (correlation) maps are generated showing regions where streamflow and climate variable from previous months are significantly correlated in a 21 (31) years moving window. Finally, the optimal forecast model is established based on a multiple regression analysis of the stable predictors. We will present current results of the aforementioned approaches with focus on the River Rhine (being one of the world's most frequented waterways and the backbone of the European inland waterway network) and the Elbe River. Overall, our analysis reveals the existence of a valuable predictability of the low flows at monthly and seasonal time scales, a result that may be useful to water resources management. Given that all predictors used in the models are available at the end of each month, the forecast scheme can be used operationally to predict extreme events and to provide early warnings for upcoming low flows.

  2. The relationship between ENSO and Paraná River flow

    Directory of Open Access Journals (Sweden)

    A. O. Cardoso

    2006-01-01

    Full Text Available Several studies indicate that there is a relationship between the climatic variability in the South American continent and alterations of the position and intensity of the heat sources in the equatorial region. The El Niño phenomenon can influence the precipitation over some regions of South America such as the Brazilian Northeast, Amazonia, South of Brazil and Uruguay. Over 80% of Brazil's energy comes from hydropower, and decisions concerning future availability and pricing require forecasts of river flow, ideally several months in advance. In this work the relationship between the Paraná River flow and the ENSO (El Niño/Southern Oscillation mode is investigated and statistical forecasts of river flow are tested. An evaluation of the relationship between the Pacific sea surface temperature and the Paraná River flow indicates an ENSO pattern over the equatorial Pacific. The time series of the ENSO mode obtained by applying principal components analysis on the sea surface temperature (SST were used as predictors for the Paraná River flow forecast. Improvement in the model forecast skill is also obtained by considering the lagged river flow time series as a predictor.

  3. Comparison of performance of statistical models in forecasting monthly streamflow of Kizil River,China

    Institute of Scientific and Technical Information of China (English)

    Shalamu ABUDU; Chun-liang CUI; James Phillip KING; Kaiser ABUDUKADEER

    2010-01-01

    This paper presents the application of autoregressive integrated moving average(ARIMA),seasonal ARIMA(SARIMA),and Jordan-Elman artificial neural networks(ANN)models in forecasting the monthly streamflow of the Kizil River in Xinjiang,China.Two different types of monthly streamflow data(original and deseasonalized data)were used to develop time series and Jordan-Elman ANN models using previous flow conditions as predictors.The one-month-ahead forecasting performances of all models for the testing period(1998-2005)were compared using the average monthly flow data from the Kalabeili gaging station on the Kizil River.The Jordan-Elman ANN models,using previous flow conditions as inputs,resulted in no significant improvement over time series models in one-month-ahead forecasting.The results suggest that the simple time series models(ARIMA and SARIMA)can be used in one-month-ahead streamflow forecasting at the study site with a simple and explicit model structure and a model performance similar to the Jordan-Elman ANN models.

  4. 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...

  5. Columbia River flow-time calculations

    Energy Technology Data Exchange (ETDEWEB)

    Soldat, J.K.

    1958-11-21

    Re-appraisal of the available data on flow times of the Columbia River between the reactor areas and Pasco was undertaken to permit extrapolation of the flow-time curves to lower river flow rates. Comparisons were made between data collected by the US Corps of Engineers and Regional Monitoring and with the equation for calculation of flow times developed by H.T. Norton. Extrapolation of the Regional Monitoring float study data to a flow of 3 {times} 10{sup 5} gallons per second was accomplished by comparison with the slope of the curve obtained from the US Corps of Engineers data; the latter covered flow times from 100-F Area to Pasco over a range of 3.4 {times} 10{sup 5} gps to 3.7 {times} 10{sup 6} gps. The revised flow-time curves are illustrated in Figures 1 through 6.

  6. Simulating river flow velocity on global scale

    Directory of Open Access Journals (Sweden)

    K. Schulze

    2005-01-01

    Full Text Available Flow velocity in rivers has a major impact on residence time of water and thus on high and low water as well as on water quality. For global scale hydrological modeling only very limited information is available for simulating flow velocity. Based on the Manning-Strickler equation, a simple algorithm to model temporally and spatially variable flow velocity was developed with the objective of improving flow routing in the global hydrological model of WaterGAP. An extensive data set of flow velocity measurements in US rivers was used to test and to validate the algorithm before integrating it into WaterGAP. In this test, flow velocity was calculated based on measured discharge and compared to measured velocity. Results show that flow velocity can be modeled satisfactorily at selected river cross sections. It turned out that it is quite sensitive to river roughness, and the results can be optimized by tuning this parameter. After the validation of the approach, the tested flow velocity algorithm has been implemented into the WaterGAP model. A final validation of its effects on the model results is currently performed.

  7. River flow time series using least squares support vector machines

    Science.gov (United States)

    Samsudin, R.; Saad, P.; Shabri, A.

    2011-06-01

    This paper proposes a novel hybrid forecasting model known as GLSSVM, which combines the group method of data handling (GMDH) and the least squares support vector machine (LSSVM). The GMDH is used to determine the useful input variables which work as the time series forecasting for the LSSVM model. Monthly river flow data from two stations, the Selangor and Bernam rivers in Selangor state of Peninsular Malaysia were taken into consideration in the development of this hybrid model. The performance of this model was compared with the conventional artificial neural network (ANN) models, Autoregressive Integrated Moving Average (ARIMA), GMDH and LSSVM models using the long term observations of monthly river flow discharge. The root mean square error (RMSE) and coefficient of correlation (R) are used to evaluate the models' performances. In both cases, the new hybrid model has been found to provide more accurate flow forecasts compared to the other models. The results of the comparison indicate that the new hybrid model is a useful tool and a promising new method for river flow forecasting.

  8. Estimating daily flow duration curves from monthly streamflow data

    CSIR Research Space (South Africa)

    Smakhtin, VU

    2000-01-01

    Full Text Available The paper describes two techniques by which to establish 1-day (1d) flow duration curves at an ungauged site where only a simulated or calculated monthly flow time series is available. Both methods employ the straightforward relationships between...

  9. 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.

  10. Sediment Transport in Rivers with Overbank Flow

    Institute of Scientific and Technical Information of China (English)

    Donald; W; KNIGHT

    2005-01-01

    Some concepts related to sediment transport in rivers with overbank flow are described.Following a description of the physical processes that are involved when a river inundates its floodplains,some simple com- putational methods are presented which permit the depth-averaged velocity and boundary shear stress to be pre- dicted within a cross section of variable,but prismatic shape.The methoda account for the strong transverse shear in velocity that occurs when the stage is just above bankfull,as well as ...

  11. Rising river flows and glacial mass balance in central Karakoram

    Science.gov (United States)

    Mukhopadhyay, Biswajit; Khan, Asif

    2014-05-01

    Field observations and geodetic measurements suggest that in the central part of the Karakoram Mountains, glaciers are either stable or expanding since 1990, in sharp contrast to glacier retreats that are prevalent in the Himalayas and adjoining high-altitude terrains of central Asia. Decreased discharge in the rivers originating from Karakoram is cited as a supporting evidence of this somewhat anomalous phenomenon. Here, in contrary to those citations, we show that, river discharge during the melting season of the glaciers in central Karakoram has increased from 1985 to 2010. We have implemented a sophisticated statistical procedure involving non-parametric tests combined with a benchmark smoothing technique that has proven to be a powerful method for empirical trend analysis to remove the stochastic component from the trend component in a time series. Melt water from winter snows is the dominant constituent of June and July flows. Glacial melts predominantly contribute to August and partially to September flows, which are controlled by monsoonal snowfall too at elevations approximately >3500 m. For all four summer months, flows increased from 1985 to 2000. August flows, which actually reflect the states of the glaciers, have continued to rise steadily after 2000 at the same rate as those did for the period 1985-2000. However, the rising trends of June and July flows changed to slightly declining trends from 2000 to 2010. These trends most likely indicate drop in winter snowfall over Karakoram and do not provide direct indications about the states of the glaciers. The rising trend of August discharge is due to change in glacial storage at a steadily decreasing rate of approximately 0.04-0.05 mm/day/year for the period 1985-2010. This rate is nearly equal to the rate of increase in precipitation during the summer months over Karakoram Mountains in recent decades as determined from the ERA-40 and GPCP precipitation datasets. Thereby, this is most plausibly, why the

  12. Evaluation of environmental flow requirements using eco-hydrologic-hydraulic methods in perennial rivers.

    Science.gov (United States)

    Abdi, Reza; Yasi, Mehdi

    2015-01-01

    The assessment of environmental flows in rivers is of vital importance for preserving riverine ecosystem processes. This paper addresses the evaluation of environmental flow requirements in three reaches along a typical perennial river (the Zab transboundary river, in north-west Iran), using different hydraulic, hydrological and ecological methods. The main objective of this study came from the construction of three dams and inter-basin transfer of water from the Zab River to the Urmia Lake. Eight hydrological methods (i.e. Tennant, Tessman, flow duration curve analysis, range of variability approach, Smakhtin, flow duration curve shifting, desktop reserve and 7Q2&10 (7-day low flow with a 2- and 10-year return period)); two hydraulic methods (slope value and maximum curvature); and two habitat simulation methods (hydraulic-ecologic, and Q Equation based on water quality indices) were used. Ecological needs of the riverine key species (mainly Barbus capito fish), river geometries, natural flow regime and the environmental status of river management were the main indices for determining the minimum flow requirements. The results indicate that the order of 35%, 17% and 18% of the mean annual flow are to be maintained for the upper, middle and downstream river reaches, respectively. The allocated monthly flow rates in the three Dams steering program are not sufficient to preserve the Zab River life.

  13. Improving Accuracy of River Flow Forecasting Using LSSVR with Gravitational Search Algorithm

    Directory of Open Access Journals (Sweden)

    Rana Muhammad Adnan

    2017-01-01

    Full Text Available River flow prediction is essential in many applications of water resources planning and management. In this paper, the accuracy of multivariate adaptive regression splines (MARS, model 5 regression tree (M5RT, and conventional multiple linear regression (CMLR is compared with a hybrid least square support vector regression-gravitational search algorithm (HLGSA in predicting monthly river flows. In the first part of the study, all three regression methods were compared with each other in predicting river flows of each basin. It was found that the HLGSA method performed better than the MARS, M5RT, and CMLR in river flow prediction. The effect of log transformation on prediction accuracy of the regression methods was also examined in the second part of the study. Log transformation of the river flow data significantly increased the prediction accuracy of all regression methods. It was also found that log HLGSA (LHLSGA performed better than the other regression methods. In the third part of the study, the accuracy of the LHLGSA and HLGSA methods was examined in river flow estimation using nearby river flow data. On the basis of results of all applications, it was found that LHLGSA and HLGSA could be successfully used in prediction and estimation of river flow.

  14. Profiling river surface velocities and volume flow estimation with bistatic UHF RiverSonde radar

    Science.gov (United States)

    Barrick, D.; Teague, C.; Lilleboe, P.; Cheng, R.; Gartner, J.; ,

    2003-01-01

    From the velocity profiles across the river, estimates of total volume flow for the four methods were calculated based on a knowledge of the bottom depth vs position across the river. It was found that the flow comparisons for the American River were much closer, within 2% of each other among all of the methods. Sources of positional biases and anomalies in the RiverSonde measurement patterns along the river were identified and discussed.

  15. LOW FLOW ON THE RIVERS OF THE EUROPEAN PART OF RUSSIA AND ITS HAZARDS

    Directory of Open Access Journals (Sweden)

    Maria B. Kireeva

    2016-01-01

    Full Text Available This paper reviews the changes in river flow of the European part of Russia during the low-flow period, characterizing groundwater flow feeding. River flow oscillations were analyzed for winter and summer periods. Statistical analyses of average low flow and the minimum monthly summer and winter discharges for 1946–1977 and 1978–2010 showed significant positive trends for all parameters of low-water period. The greatest increase is observed in the Middle Volga, where low flow has almost doubled.The low flow discharges increased by up to 50–70 % in the center of the European part of Russia and the Upper Don and its tributaries, ranging from 0 to 30 % for the northern rivers. Despite the low flow increase, the lack of water in 2010 and 2014 caused economic damage. It is shown that the observed hydrological hazards occur as a result of snow melt draughts and water management instability.

  16. Analysis of stochastic characteristics of the Benue River flow process

    Institute of Scientific and Technical Information of China (English)

    Martins Y.OTACHE; Mohammad BAKIR; LI Zhijia

    2008-01-01

    Stochastic characteristics of the Benue River streamflow process are examined under conditions of data austerity.The streamflow process is investigated for trend,non-stationarity and seasonality for a time period of 26 years.Results of trend analyses with Mann-Kendall test show that there is no trend in the annual mean discharges.Monthly flow series examined with seasonal Kendall test indicate the presence of positive change in the trend for some months,especially the months of August,January,and February.For the stationarity test,daily and monthly flow series appear to be stationary whereas at 1%,5%,and 10% significant levels,the stationarity alternative hypothesis is rejected for the annual flow series.Though monthly flow appears to be stationary going by this test,because of high seasonality,it could be said to exhibit periodic stationarity based on the seasonality analysis.The following conclusions are drawn:(1) There is seasonality in both the mean and variance with unimodal distribution.(2) Days with high mean also have high variance.(3) Skewness coefficients for the months within the dry season period are greater than those of the wet season period,and seasonal autocorrelations for streamflow during dry season are generally larger than those of the wet season.Precisely,they are significantly different for most of the months.(4) The autocorrelation functions estimated "over time" are greater in the absolute value for data that have not been deseasonalised but were initially normalised by logarithmic transformation only,while autocorrelation functions for i=1,2,…,365 estimated "over realisations" have their coefficients significantly different from other coefficients.

  17. Flow reconstructions in the Upper Missouri River Basin using riparian tree rings

    Science.gov (United States)

    Schook, Derek M.; Friedman, Jonathan M.; Rathburn, Sara L.

    2016-10-01

    River flow reconstructions are typically developed using tree rings from montane conifers that cannot reflect flow regulation or hydrologic inputs from the lower portions of a watershed. Incorporating lowland riparian trees may improve the accuracy of flow reconstructions when these trees are physically linked to the alluvial water table. We used riparian plains cottonwoods (Populus deltoides ssp. monilifera) to reconstruct discharge for three neighboring rivers in the Upper Missouri River Basin: the Yellowstone (n = 389 tree cores), Powder (n = 408), and Little Missouri Rivers (n = 643). We used the Regional Curve Standardization approach to reconstruct log-transformed discharge over the 4 months in early summer that most highly correlated to tree ring growth. The reconstructions explained at least 57% of the variance in historical discharge and extended back to 1742, 1729, and 1643. These are the first flow reconstructions for the Lower Yellowstone and Powder Rivers, and they are the furthest downstream among Rocky Mountain rivers in the Missouri River Basin. Although mostly free-flowing, the Yellowstone and Powder Rivers experienced a shift from early-summer to late-summer flows within the last century. This shift is concurrent with increasing irrigation and reservoir storage, and it corresponds to decreased cottonwood growth. Low-frequency flow patterns revealed wet conditions from 1870 to 1980, a period that includes the majority of the historical record. The 1816-1823 and 1861-1865 droughts were more severe than any recorded, revealing that drought risks are underestimated when using the instrumental record alone.

  18. 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

  19. Changes in Monthly Streamflow Conditions in the Missouri River Basin from 1957 to 2007

    Science.gov (United States)

    Anderson, M. T.; Stamm, J. F.; Norton, P. A.

    2008-12-01

    Observations of 50 years of continuous record at about 200 U.S. Geological Survey gages indicate that streamflow conditions are changing in the Missouri River Basin (MRB). Trends are evident in the annual streamflow records at 81 stations using the non-parametric Kendall Tau test. Where trends are significant, they generally are upward in the eastern portions of the basin and downward in the western portions of the basin. The reduced runoff in the western basin has resulted in main-stem reservoirs on the Missouri River that have operated at much less than full capacity for most of the last decade. Lower reservoir capacities result in significant economic effects such as reduced hydropower revenues, reduced recreation opportunities, and lower basin barge traffic. A change in the timing of streamflow or seasonality merits careful examination due to the implications for reservoir management, water supply strategies, and ecological ramifications. In this study, we examine streamflow trends by month within the MRB for the period 1957 to 2007. Two data sets were examined-202 stations with 51 years of record and a subset of 81 stations that presented a significant trend in annual flow. For both data sets, the month of April has the most stations (66) with upward trends, followed by March (59), then February (44) and May (44). The month of June has the fewest stations (18) with downward trends. Similarly, for both data sets, the months of September (57) and December (56) have the most stations with downward trends. The month of August has the fewest stations with downward trends (21). There is a strong geographic clustering of stations with trend directions. For example, most stations with trends in Colorado, North Dakota, South Dakota, Iowa, and Missouri are upward, whereas most stations with trends in Montana and Wyoming are downward. In 81 percent of the cases, more than one month exhibited a trend for a given station. The amount of water that these upward or downward

  20. MONTHLY AVERAGE FLOW IN RÂUL NEGRU HYDROGRAPHIC BASIN

    Directory of Open Access Journals (Sweden)

    VIGH MELINDA

    2014-03-01

    Full Text Available Râul Negru hydrographic basin represents a well individualised and relatively homogenous physical-geographical unity from Braşov Depression. The flow is controlled by six hydrometric stations placed on the main collector and on two of the most powerful tributaries. Our analysis period is represented by the last 25 years (1988 - 2012 and it’s acceptable for make pertinent conclusions. The maximum discharge month is April, that it’s placed in the high flow period: March – June. Minimum discharges appear in November - because of the lack of pluvial precipitations; in January because of high solid precipitations and because of water volume retention in ice. Extreme discharge frequencies vary according to their position: in the mountain area – small basin surface; into a depression – high basin surface. Variation coefficients point out very similar variation principles, showing a relative homogeneity of flow processes.

  1. Alterations of River Flow Caused By Dams. The Ebro River (ne Spain)

    Science.gov (United States)

    Batalla, R. J.; Kondolf, G. M.

    The Ebro River drains 85,530 km2 of the Cantabrian Range, Pyrenees, and Iberian Massif in northeastern Spain, with a mean annual runoff of 13,400 106 m3 at Tortosa, where it debouches into the Mediterranean Sea, about 180 km south of Barcelona. One hundred eighty-seven reservoirs (two-thirds built between 1950 and 1975) built for hydroelectric production, irrigation, cooling water, and industrial and domestic uses, have a total capacity equivalent to 57% of the Ebro River's mean annual runoff. Gauging records are available from the Confederación Hidrográfica del Ebro (CHE), a government agency established in 1926 to manage the water resources in the Ebro River basin. We analyzed 38 gauging records from 22 rivers that, by virtue of their location within the drainage network and period of record, would reflect hydrological changes from reservoir construction and operation. From pre- and post-dam records, we analyzed changes in flood peaks, mean annual runoff, mean daily flows, and mean monthly flows for four distinct climatic zones. Most rivers showed reduction in flood magnitude, with average reduction of over 30% for Q2 and Q10. Greater reductions were associated with higher values of the Impounded Runoff index (IR, calculated as reservoir capacity divided by mean annual runoff). Despite similar values of IR, floods in the low-rainfall Mediterranean tributaries in the southeast part of the basin were more affected by reservoirs than those in the high-rainfall humid Atlantic tributaries in the western part of the basin, with a given percentage of regulation producing twice the flood reduction as in the humid Atlantic zone. Annual runoff did not show strong trends, but the variability of mean daily flows was reduced in most cases due to storing of winter floods and increased baseflows in summer for irrigation. Monthly flows ranged from virtually no change post-dam to complete inversion in seasonal pattern, the latter due to releases for irrigation in the summer

  2. Environmental flow for Monsoon Rivers in India: The Yamuna River as a case study

    CERN Document Server

    Soni, Vikram; Singh, Diwan

    2013-01-01

    We consider the flows of Monsoon Rivers in India that will permit the river to perform all its natural functions. About 80% of the total flow for Indian rivers is during the monsoon and the remaining 20% is during the non monsoon period. By carrying out a case study of the river Yamuna in Delhi we find that at least 50% of the virgin monsoon (July to September) flow is required for the transport of the full spectrum of soil particles in the river sediment. A similar flow is needed for adequate recharge of the floodplain aquifers along river. For the non monsoon period (October to June) about 60% of the virgin flow is necessary to avoid the growth of still water algae and to support river biodiversity.

  3. FLUID FLOW INTERACTIONS IN OGUN RIVER, NIGERIA

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    Dr.Amartya Kumar Bhattacharya and G.Akin Bolaji

    2010-02-01

    Full Text Available Surface and groundwater interaction is an important aspect of the hydrologic cycle that borders on the watershed assessment, protection and restoration. In groundwater/surface water interactions, the groundwater component is much greater than the surface water but is much less visible and attracts less public interest. The mixing between surface and groundwater enables them to import their characteristics upon one another thereby counting a change in their parameters. Groundwater interacts with surface water in nearly all landscapes, ranging from small streams to major river valleys. Many scientists have studied the physical aspects of groundwater/surface water interactions, but it is in recent times that these interactions have been looked upon in relation to their ecological implications. With the coming of a more holistic approach to environmental flows and environmental protection, surface water/groundwater (SW/GW interactions should receive heightened attention at multidisciplinary scale and more so, by policy makers and watershed managers. It is generally understood in conceptual form that surface water therefore has the ability to enhance or detract from groundwater quality and vice versa, yet little is known about the processes by which these two entities interact (Gardener, 1988. In the past, emphasis has been placed on studying the physical and chemical effects that groundwater has on surface water but it is also important to look at the ecological role surface water and groundwater interactions can play in maintenance of environmental flows in a river basin. In area where surface water and groundwater directly interacts, the important issue commonly raised in recent times are not only concern with water quality but related with ecology and biodiversity. Therefore, there is a need for thorough understanding of the surface water and groundwater interactions within catchments so as to enhance the sustainable development and management of

  4. Impacts of changes in flow in glacier fed river in Nepal on hydropower production.

    Science.gov (United States)

    Khadka Mishra, S.

    2014-12-01

    Variability of water flow in rivers due to change in temperature, precipitation and melting of glacier translates to change in water availability for agriculture, biodiversity conservation, and hydropower production impacting 1.5 billion people living downstream in India and Nepal. Previous studies ranked hydropower sector as the highest priority sector considering the urgency and severity of impacts in countries such as Nepal where hydropower shares 96 percentage of electricity production. In India, 45 per cent of hydroelectricity is generated from glacier fed rivers and hydropower shares 17 per cent of power generation. This study developed a framework to estimate the change in river flow attributed to global climate change and quantify its impact on hydropower generation in South Asian Mountains. The framework is applied on one of the major rivers Koshi River in Nepal with existing and proposed hydropower plants. The integrated assessment approach involved estimation of the change in flow in the river in the first part. Model was developed to estimate the change in flow that uses time series data on precipitation, temperature, remote sensing imagery on snow accumulation and ablation, and slope and surface hydrology. In the second part, another model was developed to investigate the impact of change in flow on hydropower production in various types of hydropower production plants. Data on flow, characteristics of hydropower plants and hydropower produced monthly from power plants in and outside of the river basin were used to model the flow and power generation from various categories of power plants. We will further discuss the results of the integrated assessments of potential changes in hydropower generation in various categories of hydropower plants based on Koshi River under various expected changes in flow and the implications for hydropower generation from other river systems in Nepal and India.

  5. Environmental flow assessment for river Trebizat, BiH

    Science.gov (United States)

    Smolar-Zvanut, N.; Kupusovic, E.; Vucijak, B.; Mijatovic, A.; Grizelj, Z.; Antonelli, F.

    2009-04-01

    The alteration of the water flow downstream of dams is one of the most stressful factors influencing the aquatic and riverine ecosystem. The environmental flow assessment is a tool for finding the balance between water use by humans and nature and ensuring a long-term and good quality water supply both for human purposes and for ecosystems. In 2007/08 WWF has implemented a project in the Neretva basin (Bosnia and Herzegovina) with a focus on environmental flow evaluation for the river Trebizat, located in the western region of Herzegovina. The water regime of the Trebizat river is affected by the abstraction of its water for hydropower plants, irrigation and fish farming not to mention pollution problems. The Trebizat river flows through an area of remarkable ecological value hosting also protected areas (the travertine-formation around Kravice waterfall). The main aim of this paper is to present the results of the application of a methodology for environmental flow assessment, namely the GEP methodology (guaranteed ecological flow). It belongs to the category of hydrological environmental flow assessment methods and the test was done to assess the environmental flow in the river Trebizat. Using existing hydrological data as well as samples specifically collected on the field, the environmental flow was assessed applying the GEP methodology. Additionally, instream ecological values and critical parameters for environmental flow assessment were evaluated. The area was assessed in terms of its geography, climate conditions, historic heritage of the river, demography, geology of the river and its tributaries, river hydrology and morphology, ecological characteristics, river pollution, river use and river management. At five selected sampling sites along the Trebizat river, additional data on macrophytes, phytobenthos and physico-chemical parameters were collected and analysed. Although there have been many negative impacts in recent years on the Trebizat river, the

  6. Estimated monthly streamflows for selected locations on the Kabul and Logar Rivers, Aynak copper, cobalt, and chromium area of interest, Afghanistan, 1951-2010

    Science.gov (United States)

    Vining, Kevin C.; Vecchia, Aldo V.

    2014-01-01

    The U.S. Geological Survey, in cooperation with the U.S. Department of Defense Task Force for Business and Stability Operations, used the stochastic monthly water-balance model and existing climate data to estimate monthly streamflows for 1951–2010 for selected streamgaging stations located within the Aynak copper, cobalt, and chromium area of interest in Afghanistan. The model used physically based, nondeterministic methods to estimate the monthly volumetric water-balance components of a watershed. A comparison of estimated and recorded monthly streamflows for the streamgaging stations Kabul River at Maidan and Kabul River at Tangi-Saidan indicated that the stochastic water-balance model was able to provide satisfactory estimates of monthly streamflows for high-flow months and low-flow months even though withdrawals for irrigation likely occurred. A comparison of estimated and recorded monthly streamflows for the streamgaging stations Logar River at Shekhabad and Logar River at Sangi-Naweshta also indicated that the stochastic water-balance model was able to provide reasonable estimates of monthly streamflows for the high-flow months; however, for the upstream streamgaging station, the model overestimated monthly streamflows during periods when summer irrigation withdrawals likely occurred. Results from the stochastic water-balance model indicate that the model should be able to produce satisfactory estimates of monthly streamflows for locations along the Kabul and Logar Rivers. This information could be used by Afghanistan authorities to make decisions about surface-water resources for the Aynak copper, cobalt, and chromium area of interest.

  7. Analysis of long-term dependence phenomenon in Benue River flow process and its hypothesis testing

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In this paper, the long-term dependence phenomenon (the Hurst Effect) which characterizes hydrological and other geophysical times series is studied. The long-term memory is analysed for both daily and monthly streamflow series of the Benue River at Makurdi, Nigeria by using heuristic methods and testing specifically the null hypothesis of short-term memory in the monthly flow series. Results obtained by applying heuristic procedures indicated that there may be the presence of long-term memory component in mean daily flow series but there is no discernible reason to suspect the presence in both average monthly and maximum monthly flow series (extreme event). Hypothesis testing was conducted by using original and modified versions of rescaled range statistic. When the modified rescaled range, which accounts for short-term memory in the series, is used, the null hypothesis is accepted for both the average monthly and maximum monthly flow series, indicating little or no probable presence of long-term memory in the series. An identical conclusion is also arrived at when second null hypothesis for independence of the monthly flow series is tested. Therefore, apart from the mean daily flow series, there is little evidence of long-term dependence in the Benue River streamflow series at Makurdi. However, considering the limited length of data used, the results are inconclusive.

  8. Comparison of Artificial Intelligence Techniques for river flow forecasting

    Directory of Open Access Journals (Sweden)

    M. Firat

    2008-01-01

    Full Text Available The use of Artificial Intelligence methods is becoming increasingly common in the modeling and forecasting of hydrological and water resource processes. In this study, applicability of Adaptive Neuro Fuzzy Inference System (ANFIS and Artificial Neural Network (ANN methods, Generalized Regression Neural Networks (GRNN and Feed Forward Neural Networks (FFNN, and Auto-Regressive (AR models for forecasting of daily river flow is investigated and Seyhan River and Cine River was chosen as case study area. For the Seyhan River, the forecasting models are established using combinations of antecedent daily river flow records. On the other hand, for the Cine River, daily river flow and rainfall records are used in input layer. For both stations, the data sets are divided into three subsets, training, testing and verification data set. The river flow forecasting models having various input structures are trained and tested to investigate the applicability of ANFIS and ANN and AR methods. The results of all models for both training and testing are evaluated and the best fit input structures and methods for both stations are determined according to criteria of performance evaluation. Moreover the best fit forecasting models are also verified by verification set which was not used in training and testing processes and compared according to criteria. The results demonstrate that ANFIS model is superior to the GRNN and FFNN forecasting models, and ANFIS can be successfully applied and provide high accuracy and reliability for daily river flow forecasting.

  9. Seasonal and interannual variations of flow discharge from Pearl River into sea

    Directory of Open Access Journals (Sweden)

    Wei ZHANG

    2012-12-01

    Full Text Available Flow discharge from the river basin into the sea has severe impacts on the immediate vicinity of river channels, estuaries, and coastal areas. This paper analyzes the features and temporal trends of flow discharge at Pearl River’s three main gauge stations: the Wuzhou, Shijiao, and Boluo gauge stations on the West River, North River, and East River, respectively. The results show no significant trend in annual mean discharge into the sea at the three gauge stations. Changes of monthly mean discharge at the Boluo Gauge Station are evident, and a majority of monthly discharge in the dry season displays significant increasing trends. Furthermore, changes of the extreme discharge are quite evident, with a significant decreasing trend in the annual maximum discharge and a significant increasing trend in the minimum one. The significantly decreasing ratio of the flood discharge to annual discharge at the Boluo Gauge Station indicates that the flow discharge from the East River has increased in the dry season and decreased in the flood season since the construction of dams and reservoirs. At the other two gauge stations, the Wuzhou and Shijiao gauge stations, the seasonal discharge generally does not change perceptibly. Human impacts, especially those pertaining to reservoir and dam construction, appear to be responsible for the seasonal variation of flow discharge. The results indicate that the construction and operation of dams and reservoirs in the East River have a greater influence on flow discharge, which can well explain why the seasonal variation of flow discharge from the East River is more evident.

  10. Analytical model of interaction of tide and river flow

    Directory of Open Access Journals (Sweden)

    Phairot Chatanantavet

    2006-11-01

    Full Text Available Hydrodynamic characteristics of a river resulting from interaction of tide and river flow are important since problems regarding flood, salinity intrusion, water quality and sedimentation are ubiquitous. The lower reach of the river strongly influenced by tides from the sea, when interacting with river flows, results in a complicated pattern which is simplified to its interaction with four main constituents of tides obtained from harmonic analysis. An analytical model is developed in this study for simulating the hydrodynamic processes in estuarine waters, with the emphasis being given to the interaction between tides and river flows. The perturbation method is used to derive the analytical solution, in which the estuarine flow is separated into steady and unsteady components. Thus the analytical solutions derived consist of two distinct parts; one represents the influence of river flows and the other represents the influence of tides. The application of the model to a case study, the Chao Phraya river, which requires a time series of discharges and loadings at the river mouth to model water quality in the Gulf of Thailand, shows that the model can beautifully and completely simulate the hydrodynamic features of tide and river flow interaction especially in the rainy season when the river discharge is high. Data of tidal discharges are scarce because of high cost of measurement especially in the lower reach of the river strongly influenced by tides from the sea. From this study of relation between tidal discharges and tides, the analytical model can compute tidal discharges from tides correctly. The results of tides and tidal flow can subsequently be used to calculate eddy viscosity and dispersion coefficient for describing salinity and water quality profiles.

  11. In-stream flow needs of the Athabasca River

    Energy Technology Data Exchange (ETDEWEB)

    Van Meer, T. [Syncrude Canada Ltd., Edmonton, AB (Canada)

    2004-07-01

    This presentation described the importance of the in-stream flow needs of the Athabasca River. Physical and biological river functions are affected by the amount of water in the stream. The functional needs of the river are met by maintaining minimum flows. Since the development of oil sands requires large volumes of water, there has been a general perception of low river flows in the Lower Athabasca River. Syncrude Canada Ltd. challenges this perception with defensible information. The Surface Water Working Group of the Cumulative Environmental Management Association (CEMA) has created a sub-group called the In-Stream Flow Needs (IFN) to establish environmental criteria and develop management systems to protect the in-stream flow needs of the lower Athabasca River. The objective is to launch a science-based program that identifies the habitat suitability for key fish species as a function of the physical hydraulics of the river. Another objective is to have a science-based objective for flow management in place by the end of 2005. The tasks of the IFN include radio telemetry, on-ice data collection, hydraulic surveys, and modeling. tabs., figs.

  12. GRID GENERATION AND NUMERICAL SIMULATION OF 2-D RIVER FLOW GRID GENERATION AND NUMERICAL SIMULATION OF 2-D RIVER FLOW

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    This paper presents new weighting functions in grid generation and new discretizing scheme of momentum equations in numerical simulation of river flow. By using the new weighting functions, the curvilinear grid could be concentrated as desired near the assigned points or lines in physical plane. By using the new discretizing scheme, the difficulties caused by movable boundary and dry riverbed can be overcome. As an application, the flow in the Wuhan Section of Yangtze River is simulated. The computational results are in good agreement with the measured results. The new method is applicable to the numerical simulation of 2-D river flow with irregular region and moveable boundary.

  13. Global-scale analysis of river flow alterations due to water withdrawals and reservoirs

    Science.gov (United States)

    Döll, P.; Fiedler, K.; Zhang, J.

    2009-12-01

    Global-scale information on natural river flows and anthropogenic river flow alterations is required to identify areas where aqueous ecosystems are expected to be strongly degraded. Such information can support the identification of environmental flow guidelines and a sustainable water management that balances the water demands of humans and ecosystems. This study presents the first global assessment of the anthropogenic alteration of river flow regimes, in particular of flow variability, by water withdrawals and dams/reservoirs. Six ecologically relevant flow indicators were quantified using an improved version of the global water model WaterGAP. WaterGAP simulated, with a spatial resolution of 0.5 degree, river discharge as affected by human water withdrawals and dams around the year 2000, as well as naturalized discharge without this type of human interference. Compared to naturalized conditions, long-term average global discharge into oceans and internal sinks has decreased by 2.7% due to water withdrawals, and by 0.8% due to dams. Mainly due to irrigation, long-term average river discharge and statistical low flow Q90 (monthly river discharge that is exceeded in 9 out of 10 months) have decreased by more than 10% on one sixth and one quarter of the global land area (excluding Antarctica and Greenland), respectively. Q90 has increased significantly on only 5% of the land area, downstream of reservoirs. Due to both water withdrawals and reservoirs, seasonal flow amplitude has decreased significantly on one sixth of the land area, while interannual variability has increased on one quarter of the land area mainly due to irrigation. It has decreased on only 8% of the land area, in areas downstream of reservoirs where consumptive water use is low. The impact of reservoirs is likely underestimated by our study as small reservoirs are not taken into account. Areas most affected by anthropogenic river flow alterations are the Western and Central USA, Mexico, the

  14. Global-scale analysis of river flow alterations due to water withdrawals and reservoirs

    Directory of Open Access Journals (Sweden)

    P. Döll

    2009-07-01

    Full Text Available Global-scale information on natural river flows and anthropogenic river flow alterations is required to identify areas where aqueous ecosystems are expected to be strongly degraded. Such information can support the identification of environmental flow guidelines and a sustainable water management that balances the water demands of humans and ecosystems. This study presents the first global assessment of the anthropogenic alteration of river flow regimes by water withdrawals and dams, focusing in particular on the change of flow variability. Six ecologically relevant flow indicators were quantified using an improved version of the global water model WaterGAP. WaterGAP simulated, with a spatial resolution of 0.5 degree, river discharge as affected by human water withdrawals and dams, as well as naturalized discharge without this type of human interference. Mainly due to irrigation, long-term average river discharge and statistical low flow Q90 (monthly river discharge that is exceeded in 9 out of 10 months have decreased by more than 10% on one sixth and one quarter of the global land area (excluding Antarctica and Greenland, respectively. Q90 has increased significantly on only 5% of the land area, downstream of reservoirs. Due to both water withdrawals and dams, seasonal flow amplitude has decreased significantly on one sixth of the land area, while interannual variability has increased on one quarter of the land area mainly due to irrigation. It has decreased on only 8% of the land area, in areas with little consumptive water use that are downstream of dams. Areas most affected by anthropogenic river flow alterations are the western and central USA, Mexico, the western coast of South America, the Mediterranean rim, Southern Africa, the semi-arid and arid countries of the Near East and Western Asia, Pakistan and India, Northern China and the Australian Murray-Darling Basin, as well as some Arctic rivers. Due

  15. Global-scale analysis of river flow alterations due to water withdrawals and reservoirs

    Directory of Open Access Journals (Sweden)

    P. Döll

    2009-12-01

    Full Text Available Global-scale information on natural river flows and anthropogenic river flow alterations is required to identify areas where aqueous ecosystems are expected to be strongly degraded. Such information can support the identification of environmental flow guidelines and a sustainable water management that balances the water demands of humans and ecosystems. This study presents the first global assessment of the anthropogenic alteration of river flow regimes, in particular of flow variability, by water withdrawals and dams/reservoirs. Six ecologically relevant flow indicators were quantified using an improved version of the global water model WaterGAP. WaterGAP simulated, with a spatial resolution of 0.5 degree, river discharge as affected by human water withdrawals and dams around the year 2000, as well as naturalized discharge without this type of human interference. Compared to naturalized conditions, long-term average global discharge into oceans and internal sinks has decreased by 2.7% due to water withdrawals, and by 0.8% due to dams. Mainly due to irrigation, long-term average river discharge and statistical low flow Q90 (monthly river discharge that is exceeded in 9 out of 10 months have decreased by more than 10% on one sixth and one quarter of the global land area (excluding Antarctica and Greenland, respectively. Q90 has increased significantly on only 5% of the land area, downstream of reservoirs. Due to both water withdrawals and reservoirs, seasonal flow amplitude has decreased significantly on one sixth of the land area, while interannual variability has increased on one quarter of the land area mainly due to irrigation. It has decreased on only 8% of the land area, in areas downstream of reservoirs where consumptive water use is low. The impact of reservoirs is likely underestimated by our study as small reservoirs are not taken into account. Areas most affected by anthropogenic river flow

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

    African Journals Online (AJOL)

    2014-03-04

    Mar 4, 2014 ... Riparian species disperse, reproduce and survive in response to river flow timing ..... transformed when assumptions of heterogeneity of variance ..... soil type on growth, vessel diameter and vessel frequency in seed-.

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

    Directory of Open Access Journals (Sweden)

    Z. Yang

    2012-01-01

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

  19. Prediction of mean monthly river discharges in Colombia through Empirical Mode Decomposition

    Science.gov (United States)

    Carmona, A. M.; Poveda, G.

    2015-04-01

    The hydro-climatology of Colombia exhibits strong natural variability at a broad range of time scales including: inter-decadal, decadal, inter-annual, annual, intra-annual, intra-seasonal, and diurnal. Diverse applied sectors rely on quantitative predictions of river discharges for operational purposes including hydropower generation, agriculture, human health, fluvial navigation, territorial planning and management, risk preparedness and mitigation, among others. Various methodologies have been used to predict monthly mean river discharges that are based on "Predictive Analytics", an area of statistical analysis that studies the extraction of information from historical data to infer future trends and patterns. Our study couples the Empirical Mode Decomposition (EMD) with traditional methods, e.g. Autoregressive Model of Order 1 (AR1) and Neural Networks (NN), to predict mean monthly river discharges in Colombia, South America. The EMD allows us to decompose the historical time series of river discharges into a finite number of intrinsic mode functions (IMF) that capture the different oscillatory modes of different frequencies associated with the inherent time scales coexisting simultaneously in the signal (Huang et al. 1998, Huang and Wu 2008, Rao and Hsu, 2008). Our predictive method states that it is easier and simpler to predict each IMF at a time and then add them up together to obtain the predicted river discharge for a certain month, than predicting the full signal. This method is applied to 10 series of monthly mean river discharges in Colombia, using calibration periods of more than 25 years, and validation periods of about 12 years. Predictions are performed for time horizons spanning from 1 to 12 months. Our results show that predictions obtained through the traditional methods improve when the EMD is used as a previous step, since errors decrease by up to 13% when the AR1 model is used, and by up to 18% when using Neural Networks is combined with the

  20. Particularities of periods with maximum water flow on the rivers from the Suceava hydrographic basin (1981–2005

    Directory of Open Access Journals (Sweden)

    ADRIANA MIHAELA PORCUȚAN

    2016-11-01

    Full Text Available Suceava river basin gets its tributaries from the eastern slopes of the northern group of the Eastern Romanian Carpathians, situated under the influence of Baltic air masses, which bring rainfalls and cold weather, felt into the water flow regime of rivers in the region studied. This water flow regime varies from month to month, with the maximum flow having the most important role in the restoration of underground water reserves. This study examines the temporal (frequency, duration and intensity and quantitative (volume and flow parameters of periods with maximum flow, at monthly and seasonal level, revealing the differences in the water flow regime induced by the relief’s morphometric particularities (altitude, fragmentation degree, exhibition. For the evaluation of mentioned parameters was appealed to the TML 2.1 extension from the HydroOffice software package, which uses quantitative thresholds, depending on which it is set the appearance, and disappearance of periods with maximum flow.

  1. 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.

  2. Monthly spatial occurrence of phytoplankton and zooplankton in River Ogun, Abeokuta, Ogun State, southwest Nigeria

    OpenAIRE

    Dimowo, B.O.

    2013-01-01

    The aim of this study was to investigate the monthly spatial occurrence of phytoplankton and zooplankton in River Ogun, Abeokuta, Southwest Nigeria. This was carried out for seven months between December, 2011 and June, 2012 in 4 stations. A total of 41 species of phytoplankton and 16 zooplankton species from 5 classes respectively were recorded. Zooplankton was dominated by Cladocera throughout the study period while phytoplankton was dominated by blue green algae (Cyanophyta or Cyanobacteri...

  3. REGULATION OF FLOW AND SEDIMENT LOAD IN THE YELLOW RIVER

    Institute of Scientific and Technical Information of China (English)

    Wenxue LI; Jixiang LIU; Zhanwei WAN

    2007-01-01

    Small runoff, large sediment load, and incompatible relationship of flow and sediment load are very important characteristics of the Yellow River. They are also the crux of the most prominent problems of the Yellow River. To solve these problems, the regimes of flow and sediment load have to be improved by increasing water, reducing sediment load, and by using reservoirs to regulate flow and sediment load. The results of experiments for regulating the flow and sediment load in the last three years by the Xiaolangdi Reservoir have indicated that this measure is a realistic and effective way to mitigate the prominent problems in flood control of the Lower Yellow River at present and in the near future. However, the regulation system is still imperfect. It is advisable to speed up the pace of research and construction of the system for regulating flow and sediment load.

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

    Directory of Open Access Journals (Sweden)

    Z. Yang

    2011-06-01

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

  5. Overcoming Information Limitations for the Prescription of an Environmental Flow Regime for a Central American River

    Directory of Open Access Journals (Sweden)

    Peter C. Esselman

    2010-03-01

    Full Text Available Hydropower dam construction is expanding rapidly in Central America because of the increasing demand for electricity. Although hydropower can provide a low-carbon source of energy, dams can also degrade socially valued riverine and riparian ecosystems and the services they provide. Such degradation can be partially mitigated by the release of environmental flows below dams. However, environmental flows have been applied infrequently to dams in Central America, partly because of the lack of information on the ecological, social, and economic aspects of rivers. This paper presents a case study of how resource and information limitations were addressed in the development of environmental flow recommendations for the Patuca River in Honduras below a proposed hydroelectric dam. To develop flow recommendations, we applied a multistep process that included hydrological analysis and modeling, the collection of traditional ecological knowledge (TEK during field trips, expert consultation, and environmental flow workshops for scientists, water managers, and community members. The final environmental flow recommendation specifies flow ranges for different components of river hydrology, including low flows for each month, high-flow pulses, and floods, in dry, normal, and wet years. The TEK collected from local and indigenous riverine communities was particularly important for forming hypotheses about flow-dependent ecological and social factors that may be vulnerable to disruption from dam-modified river flows. We show that our recommended environmental flows would have a minimal impact on the dam's potential to generate electricity. In light of rapid hydropower development in Central America, we suggest that environmental flows are important at the local scale, but that an integrated landscape perspective is ultimately needed to pursue hydropower development in a manner that is as ecologically sustainable as possible.

  6. Characterization of river flow fluctuations via horizontal visibility graphs

    CERN Document Server

    Braga, A C; Costa, L S; Ribeiro, A A; de Jesus, M M A; Tateishi, A A; Ribeiro, H V

    2015-01-01

    We report on a large-scale characterization of river discharges by employing the network framework of the horizontal visibility graph. By mapping daily time series from 141 different stations of 53 Brazilian rivers into complex networks, we present an useful approach for investigating the dynamics of river flows. We verified that the degree distributions of these networks were well described by exponential functions, where the characteristic exponents are almost always larger than the value obtained for random time series. The faster-than-random decay of the degree distributions is an another evidence that the fluctuation dynamics underlying the river discharges has a longe-range correlated nature. We further investigated the evolution of the river discharges by tracking the values of the characteristic exponents (of the degree distribution) and the global clustering coefficients of the networks over the years. We show that the river discharges in several stations have evolved to become more or less correlate...

  7. Climate influences on Vaal River flow

    African Journals Online (AJOL)

    2016-04-02

    Apr 2, 2016 ... Keywords: Vaal River, hydro-meteorology, climate influence. INTRODUCTION ... rainfall fluctuate from year to year (CV = 0.3), a constraint to pro- duction and ..... African Weather Bureau Technical Paper 14. South African.

  8. Modeling summer month hydrological drought probabilities in the United States using antecedent flow conditions

    Science.gov (United States)

    Austin, Samuel H.; Nelms, David L.

    2017-01-01

    Climate change raises concern that risks of hydrological drought may be increasing. We estimate hydrological drought probabilities for rivers and streams in the United States (U.S.) using maximum likelihood logistic regression (MLLR). Streamflow data from winter months are used to estimate the chance of hydrological drought during summer months. Daily streamflow data collected from 9,144 stream gages from January 1, 1884 through January 9, 2014 provide hydrological drought streamflow probabilities for July, August, and September as functions of streamflows during October, November, December, January, and February, estimating outcomes 5-11 months ahead of their occurrence. Few drought prediction methods exploit temporal links among streamflows. We find MLLR modeling of drought streamflow probabilities exploits the explanatory power of temporally linked water flows. MLLR models with strong correct classification rates were produced for streams throughout the U.S. One ad hoc test of correct prediction rates of September 2013 hydrological droughts exceeded 90% correct classification. Some of the best-performing models coincide with areas of high concern including the West, the Midwest, Texas, the Southeast, and the Mid-Atlantic. Using hydrological drought MLLR probability estimates in a water management context can inform understanding of drought streamflow conditions, provide warning of future drought conditions, and aid water management decision making.

  9. Defining environmental river flow requirements – a review

    Directory of Open Access Journals (Sweden)

    M. C. Acreman

    2004-01-01

    Full Text Available Around the world, there is an increasing desire, supported by national and regional policies and legislation, to conserve or restore the ecological health and functioning of rivers and their associated wetlands for human use and biodiversity. To achieve this, many organisations have developed methods for defining “environmental flows‿, i.e. the flow regime required in a river to achieve desired ecological objectives. This paper reviews the various methods available and suggests a simple categorisation of the methods into four types: look-up tables, desk-top analysis; functional analysis and hydraulic habitat modelling. No method is necessarily better than another; each may be suitable for different applications. Whilst look-up methods are easy and cheap to apply, they can be expensive to develop, are less accurate and more suitable for scoping studies; in contrast, although hydraulic habitat modelling is more expensive to apply, it is suitable for impact assessment at specific sites. Each method would need to be used within a wider decision-support framework. These are generally either objective-based to define a target flow regime for a specific desired river status, or scenario-based to indicate the relative merits of various flow regime options for the river environment. Keywords: environmental flow, instream flow, river habitat modelling, building block method, flow scenario analysis, objective setting.

  10. Low flow forecasting with a lead time of 14 days for navigation and energy supply in the Rhine River

    NARCIS (Netherlands)

    Demirel, M.C.; Booij, Martijn J.

    2011-01-01

    Low flow forecasting, days or even months in advance, is particularly important to the efficient operation of power plants and freight shipment. This study presents a low flow forecasting model with a lead time of 14 days for the Rhine River. The forecasts inherit uncertainty sources mainly because

  11. Two-dimensional surface river flow patterns measured with paired RiverSondes

    Science.gov (United States)

    Teague, C.C.; Barrick, D.E.; Lilleboe, P.M.; Cheng, R.T.

    2008-01-01

    Two RiverSondes were operated simultaneously in close proximity in order to provide a two-dimensional map of river surface velocity. The initial test was carried out at Threemile Slough in central California. The two radars were installed about 135 m apart on the same bank of the channel. Each radar used a 3-yagi antenna array and determined signal directions using direction finding. The slough is approximately 200 m wide, and each radar processed data out to about 300 m, with a range resolution of 15 m and an angular resolution of 1 degree. Overlapping radial vector data from the two radars were combined to produce total current vectors at a grid spacing of 10 m, with updates every 5 minutes. The river flow in the region, which has a maximum velocity of about 0.8 m/s, is tidally driven with flow reversals every 6 hours, and complex flow patterns were seen during flow reversal. The system performed well with minimal mutual interference. The ability to provide continuous, non-contact two-dimensional river surface flow measurements will be useful in several unique settings, such as studies of flow at river junctions where impacts to juvenile fish migration are significant. Additional field experiments are planned this year on the Sacramento River. ?? 2007 IEEE.

  12. [Effects of vegetation on river flow: a review].

    Science.gov (United States)

    Xu, Wei-Gang; Zhang, Hua-Yong; Wang, Zhong-Yu; Huang, Wen-Pei

    2013-01-01

    Vegetation is a component of the natural river. To understand the interaction between vegetation and water flow is of scientific and practical significance for the protection of wildlife habitats, the control of water body eutrophication, the ecological restoration of rivers and lakes, and the management of riverways. This paper reviewed the researches about the interaction between vegetation and water flow in riverways, summarized the research progress in the effects of the vegetation on the resistance coefficient and water flow structure, and introduced the applications of numerical simulation in this research field. Based on the previous studies, the effects of river section shape, plant individual form, and vegetation distribution pattern on the flow regime of water flow in vegetation section were analyzed. For further study, the importance of deeply understanding the hydraulics mechanisms of the interaction between vegetation and water flow in terms of the diversity of river morphology, the vegetation variation at different spatiotemporal scales, the water flow distribution in vegetation section, and the three dimensional turbulent simulation was expatiated.

  13. Upper Klamath Lake Basin nutrient-loading study; assessment of historic flows in the Williamson and Sprague rivers

    Science.gov (United States)

    Risley, John C.; Laenen, Antonius

    1999-01-01

    The Williamson River Basin, located in southcentral Oregon, has a drainage area of approximately 3,000 square miles. The Sprague River, which flows into the Williamson River Basin, has a drainage area of 1,580 square miles. Together, the Williamson and Sprague Rivers supply about one-half of the inflow to Upper Klamath Lake. Various statistical techniques, which included trend tests, double-mass curves, and two-sample tests, were used to detect significant changes in the precipitation-runoff relation for the Williamson and Sprague River Basins. Flows from these two rivers were compared with the precipitation and air temperature records collected at Klamath Falls to assess the effect of climate on flow variations. Most of the double-mass curves showed a major break in the slope of the curve occurring around 1950 and a smaller one near 1990. For the years 1930?50 and 1990?96, February through May flows were relatively lower in the Williamson River than in rivers in nearby basins, by an average of 25,000 acre-feet per year and 36,000 acre-feet per year, respectively, for the 4-month period. From 1950 through 1963, flows were generally higher in the Williamson River compared with the nearby rivers by an average of 38,000 acre-feet for the 4 months. In July through September of 1945?51, 1970?76, and 1992?96, flows were lower in the Williamson River than in the comparison rivers by an average of about 6,000 acre-feet for the 3-month period. Two-sample statistical tests of the annual flow data sets for the Williamson and Sprague Rivers showed a significant increase in the estimated population mean for the period 1951?96 compared to the estimated population mean for the period 1922?50. However, climate data, which included annual precipitation data from Klamath Falls, Crater Lake, and Medford, and annual air temperature data from Klamath Falls, all showed no significant difference between the two periods. During the past century, various human land-use activities, such as

  14. Mekong River flow and hydrological extremes under climate change

    OpenAIRE

    Hoang, L.P.; H. Lauri; M. Kummu; Koponen, J.; van Vliet, M. T. H.; I. Supit; Leemans, R.; Kabat, P.; Ludwig, F.

    2016-01-01

    Climate change poses critical threats to water-related safety and sustainability in the Mekong River basin. Hydrological impact signals from earlier Coupled Model Intercomparison Project phase 3 (CMIP3)-based assessments, however, are highly uncertain and largely ignore hydrological extremes. This paper provides one of the first hydrological impact assessments using the CMIP5 climate projections. Furthermore, we model and analyse changes in river flow regimes and hydrologica...

  15. Flow Durations, Low-Flow Frequencies, and Monthly Median Flows for Selected Streams in Connecticut through 2005

    Science.gov (United States)

    Ahearn, Elizabeth A.

    2008-01-01

    Flow durations, low-flow frequencies, and monthly median streamflows were computed for 91 continuous-record, streamflow-gaging stations in Connecticut with 10 or more years of record. Flow durations include the 99-, 98-, 97-, 95-, 90-, 85-, 80-, 75-, 70-, 60-, 50-, 40-, 30-, 25-, 20-, 10-, 5-, and 1-percent exceedances. Low-flow frequencies include the 7-day, 10-year (7Q10) low flow; 7-day, 2-year (7Q2) low flow; and 30-day, 2-year (30Q2) low flow. Streamflow estimates were computed for each station using data for the period of record through water year 2005. Estimates of low-flow statistics for 7 short-term (operated between 3 and 10 years) streamflow-gaging stations and 31 partial-record sites were computed. Low-flow estimates were made on the basis of the relation between base flows at a short-term station or partial-record site and concurrent daily mean streamflows at a nearby index station. The relation is defined by the Maintenance of Variance Extension, type 3 (MOVE.3) method. Several short-term stations and partial-record sites had poorly defined relations with nearby index stations; therefore, no low-flow statistics were derived for these sites. The estimated low-flow statistics for the short-term stations and partial-record sites include the 99-, 98-, 97-, 95-, 90-, and 85-percent flow durations; the 7-day, 10-year (7Q10) low flow; 7-day, 2-year (7Q2) low flow; and 30-day, 2-year (30Q2) low-flow frequencies; and the August median flow. Descriptive information on location and record length, measured basin characteristics, index stations correlated to the short-term station and partial-record sites, and estimated flow statistics are provided in this report for each station. Streamflow estimates from this study are stored on USGS's World Wide Web application 'StreamStats' (http://water.usgs.gov/osw/streamstats/connecticut.html).

  16. 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

  17. Dual-RiverSonde measurements of two-dimensional river flow patterns

    Science.gov (United States)

    Teague, C.C.; Barrick, D.E.; Lilleboe, P.M.; Cheng, R.T.; Stumpner, P.; Burau, J.R.

    2008-01-01

    Two-dimensional river flow patterns have been measured using a pair of RiverSondes in two experiments in the Sacramento-San Joaquin River Delta system of central California during April and October 2007. An experiment was conducted at Walnut Grove, California in order to explore the use of dual RiverSondes to measure flow patterns at a location which is important in the study of juvenile fish migration. The data available during the first experiment were limited by low wind, so a second experiment was conducted at Threemile Slough where wind conditions and surface turbulence historically have resulted in abundant data. Both experiments included ADCP near-surface velocity measurements from either manned or unmanned boats. Both experiments showed good comparisons between the RiverSonde and ADCP measurements. The flow conditions at both locations are dominated by tidal effects, with partial flow reversal at Walnut Grove and complete flow reversal at Threemile Slough. Both systems showed complex flow patterns during the flow reversals. Quantitative comparisons between the RiverSondes and an ADCP on a manned boat at Walnut Grove showed mean differences of 4.5 cm/s in the u (eastward) and 7.6 cm/s in the v (northward) components, and RMS differences of 14.7 cm/s in the u component and 21.0 cm/s in the v component. Quantitative comparisons between the RiverSondes and ADCPs on autonomous survey vessels at Threemile Slough showed mean differences of 0.007 cm/s in the u component and 0.5 cm/s in the v component, and RMS differences of 7.9 cm/s in the u component and 13.5 cm/s in the v component after obvious outliers were removed. ?? 2008 IEEE.

  18. A joint stochastic-deterministic approach for long-term and short-term modelling of monthly flow rates

    Science.gov (United States)

    Stojković, Milan; Kostić, Srđan; Plavšić, Jasna; Prohaska, Stevan

    2017-01-01

    The authors present a detailed procedure for modelling of mean monthly flow time-series using records of the Great Morava River (Serbia). The proposed procedure overcomes a major challenge of other available methods by disaggregating the time series in order to capture the main properties of the hydrologic process in both long-run and short-run. The main assumption of the conducted research is that a time series of monthly flow rates represents a stochastic process comprised of deterministic, stochastic and random components, the former of which can be further decomposed into a composite trend and two periodic components (short-term or seasonal periodicity and long-term or multi-annual periodicity). In the present paper, the deterministic component of a monthly flow time-series is assessed by spectral analysis, whereas its stochastic component is modelled using cross-correlation transfer functions, artificial neural networks and polynomial regression. The results suggest that the deterministic component can be expressed solely as a function of time, whereas the stochastic component changes as a nonlinear function of climatic factors (rainfall and temperature). For the calibration period, the results of the analysis infers a lower value of Kling-Gupta Efficiency in the case of transfer functions (0.736), whereas artificial neural networks and polynomial regression suggest a significantly better match between the observed and simulated values, 0.841 and 0.891, respectively. It seems that transfer functions fail to capture high monthly flow rates, whereas the model based on polynomial regression reproduces high monthly flows much better because it is able to successfully capture a highly nonlinear relationship between the inputs and the output. The proposed methodology that uses a combination of artificial neural networks, spectral analysis and polynomial regression for deterministic and stochastic components can be applied to forecast monthly or seasonal flow rates.

  19. A Wavelet Neural Network Hybrid Model for Monthly Ammonia Forecasting in River Water

    OpenAIRE

    2013-01-01

    Forecasting water quality is always an effective approach for water environmental management. This study presents a combined Wavelet transform (WA) and Artificial Neural Network (ANN) model for monthly ammonia nitrogen series prediction in river water. The WA decomposed original time series into different subseries, in which the most significant one was chosen as the training data instead of the original series. Compared to the traditional ANN, the WA-ANN models were found more accurate and r...

  20. 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

  1. Sediment transport during flushing flows in the lower River Ebro

    Science.gov (United States)

    Batalla, R. J.; Vericat, D.; Palau, A.

    2009-04-01

    This study describes the sediment transport which occurred during several flushing flows between 2002 and 2008 in the impounded lower River Ebro (Northeast Spain). The experimental releases were designed and undertaken to control the excess of aquatic vegetation and enhance sediment-related processes in the river channel downstream the lowermost dams in the basin. Macrophytes cause problems to water users, especially to the hydroelectric and the nuclear power plants located in the vicinity of the river. Sediment transport results from flushing flows are compared with those observed during natural floods. Observations show distinct patterns of sediment transport owing to the particular channel conditions (i.e. exhaustion of fine sediment and removal of the surface layer). Flushing flows depict notably higher suspended sediment concentrations in relation to natural floods. Bed load rates during flushing flows are typically low and, because the flood duration is short, no incision is observed in the river bed. In spite of that, large quantities of macrophytes were removed. The combination of hydraulic and sedimentary parameters during the designed floods maximizes the ecological and management benefits of the experimental releases without significant adverse geomorphological impacts on the river channel.

  2. EXPERIMENTS OF THREE-DIMENSIONAL FLOW STRUCTURE IN BRAIDED RIVERS

    Institute of Scientific and Technical Information of China (English)

    HUA Zu-lin; GU Li; CHU Ke-jian

    2009-01-01

    The braided river is a typical river pattern in nature, but there is a paucity of comprehensive data set describing the three-dimensional flow field in the braided river. A physical model experiment was used to study the flow characteristics in the typical braided river with a mid-bar between two anabranches. In the experiment, two kinds of mid-bar with the ratios of its length to maximal width of 3 and 5 were considered. Moreover, the mid-bar could be moved to adjust the width of two anabranches. The detailed measurements of velocity were conducted using an acoustic Doppler velocimeter over a grid defined throughout the whole braided river region, including the bifurcation, two anabranches and the confluence. In two kinds of mid-bar braided models, a separation zone was observed in the anabranch of the model in which the ratio of length to maximal width of mid-bar is 3, however the separation zone was not found in another model in which the ratio is 5. In addition, the opposite secondary cells were observed at the bend apex of anabranch in two models, and different longitudinal velocity distributions in the entrance region of anabranch account for this opposite flow structure. Finally, turbulent kinetic energy were shown and compared in different situations. The high turbulence occurs at the place with strong shear, especially at the boundary of the separation zone and the high velocity passing flow.

  3. 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

    2015-12-01

    Increasing nitrogen concentrations in the world's major rivers have led to over-fertilization of sensitive downstream waters. Flow through channel bed and bank sediments acts to remove riverine nitrogen through microbe-mediated denitrification reactions. 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 zones. 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.

  4. Flow structures and sandbar dynamics in a canyon river during a controlled flood, Colorado River, Arizona

    Science.gov (United States)

    Wright, S.A.; Kaplinski, M.

    2011-01-01

    In canyon rivers, debris fan constrictions create rapids and downstream pools characterized by secondary flow structures that are closely linked to channel morphology. In this paper we describe detailed measurements of the three-dimensional flow structure and sandbar dynamics of two pools along the Colorado River in the Grand Canyon during a controlled flood release from Glen Canyon Dam. Results indicate that the pools are characterized by large lateral recirculation zones (eddies) resulting from flow separation downstream from the channel constrictions, as well as helical flow structures in the main channel and eddy. The lateral recirculation zones are low-velocity areas conducive to fine sediment deposition, particularly in the vicinity of the separation and reattachment points and are thus the dominant flow structures controlling sandbar dynamics. The helical flow structures also affect morphology but appear secondary in importance to the lateral eddies. During the controlled flood, sandbars in the separation and reattachment zones at both sites tended to build gradually during the rising limb and peak flow. Deposition in shallow water on the sandbars was accompanied by erosion in deeper water along the sandbar slope at the interface with the main channel. Erosion occurred via rapid mass failures as well as by gradual boundary shear stress driven processes. The flow structures and morphologic links at our study sites are similar to those identified in other river environments, in particular sharply curved meanders and channel confluences where the coexistence of lateral recirculation and helical flows has been documented. Copyright 2011 by the American Geophysical Union.

  5. 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

  6. Modeling and forecasting the peak flows of a river

    Directory of Open Access Journals (Sweden)

    Mario Lefebvre

    2002-01-01

    Full Text Available A stochastic model is found for the value of the peak flows of the Mistassibi river in Québec, Canada, when the river is in spate. Next, the objective is to forecast the value of the coming peak flow about four days in advance, when the flow begins to show a marked increase. Both the stochastic model proposed in the paper and a model based on linear regression are used to produce the forecasts. The quality of the forecasts is assessed by considering the standard errors and the peak criterion. The forecasts are much more accurate than those obtained by taking the mean value of the previous peak flows.

  7. The importance of base flow in sustaining surface water flow in the Upper Colorado River Basin

    Science.gov (United States)

    Miller, Matthew P.; Buto, Susan G.; Susong, David D.; Rumsey, Christine

    2016-01-01

    The Colorado River has been identified as the most overallocated river in the world. Considering predicted future imbalances between water supply and demand and the growing recognition that base flow (a proxy for groundwater discharge to streams) is critical for sustaining flow in streams and rivers, there is a need to develop methods to better quantify present-day base flow across large regions. We adapted and applied the spatially referenced regression on watershed attributes (SPARROW) water quality model to assess the spatial distribution of base flow, the fraction of streamflow supported by base flow, and estimates of and potential processes contributing to the amount of base flow that is lost during in-stream transport in the Upper Colorado River Basin (UCRB). On average, 56% of the streamflow in the UCRB originated as base flow, and precipitation was identified as the dominant driver of spatial variability in base flow at the scale of the UCRB, with the majority of base flow discharge to streams occurring in upper elevation watersheds. The model estimates an average of 1.8 × 1010 m3/yr of base flow in the UCRB; greater than 80% of which is lost during in-stream transport to the Lower Colorado River Basin via processes including evapotranspiration and water diversion for irrigation. Our results indicate that surface waters in the Colorado River Basin are dependent on base flow, and that management approaches that consider groundwater and surface water as a joint resource will be needed to effectively manage current and future water resources in the Basin.

  8. Fractal analysis of flow of the river Warta

    Science.gov (United States)

    Radziejewski, Maciej; Kundzewicz, Zbigniew W.

    1997-12-01

    A long time series (170 years) of daily flows of the river Warta (Poland) are subject to fractal analysis. A binary variable (renewal stream) illustrating excursions of the process of flow is examined. The raw series is subject to de-seasonalization and normalization. Fractal dimensions of crossings of Warta flows are determined using a novel variant of the box-counting method. Temporal variability of the flow process is studied by determination of fractal dimensions for shifted horizons of 10 or 30 years length. Spectral properties are compared between the time series of flows, and the fractional Brownian motion which describes both the fractal structure of the process and the Hurst phenomenon. The approach may be useful in further studies of non-stationary of the process of flow, analysis of extreme hydrological events and synthetic flow generation.

  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. Decomposing the Unsteady Flow Routing in River Systems

    Science.gov (United States)

    Gomez Cunya, L. A.; Leon, A.; Gibson, N. L.; Vasylkivska, V.

    2014-12-01

    This work presents an optimization-based domain decomposition strategy for unsteady flow routing in complex river systems. This strategy couples the domain decomposition technique with a Precomputed Channel Hydraulics Ensemble approach, known also as HydraulicPerformance Graph (HPG), which utilizes precomputed solutions along reaches on a river system. These solutions are stored in a database. While efficient and robust, HPGs requires extensive memory allocation, especially for high resolution simulations. Decomposing the river system into subdomains reduces computer memory constraints as each sub-domain is solved independently. Further, an optimization method is used to couple the sub-domains using the stored precomputed solution. In turn, the computational efficiency of the HPG approach allows the optimization-based scheme to be competitive with a whole domain methodology. The combined strategy is expected to reduce the overall computational time for large-scale problems. This work discusses the results of the application to the Columbia River (Northwest USA).

  11. 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.

  12. 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

  13. Coherent Turbulent Flow Structures in a Gravel-Bed River

    Science.gov (United States)

    Ashley, W.; Macmahan, J. H.; Reniers, A. J.; Thornton, E. B.; Brown, J.; Swick, W. A.

    2010-12-01

    The characteristics of coherent turbulent flow structures were examined during multi-day deployments with three different sensors in a gravel-bed river reach section of the Kootenai River, ID in August 2010. In-situ river velocities were measured using a custom 2 MHz Acoustic Doppler Current Profiler (ADCP) head, an Acoustic Doppler Velocimeter (ADV), and a lagged array of six electromagnetic current meters (ECM) mounted on a GPS-equipped portable aluminum frame. The frame was deployed in the river which varied from 0.6 to 1m water depths and 0.5 to 1.5 m/s velocities. It was also deployed in a small channel, near riffle pools, and on the lee of river obstructions. The ECM array was horizontally mounted on a 4m length pole attached to the frame, oriented in the stream-wise direction, with a sampling frequency of 16 Hz. The lagged spacing of the six ECMs was set to resolve coherent motions from up to 8m in length. The ADCP was fitted with a custom head to measure the along beam velocities in all three axes, with a sampling frequency of 1 Hz, 35cm bins, with a maximum range of 10m. The upstream beam is used to describe the coherent structures in the stream-wise velocity. An iterative maximum likelihood estimator is used to evaluate the streamwise wavenumber-frequency spectrum. The coherent structures measured by the ECM array and ADCP are compared to validate the results by the new ADCP head. Turbulent measurements from the 32 Hz sampled ADV are compared to the ADCP and ECM. Our unique approach provides spatial measurements in river reaches (depths) previously not examined. The flow structure as a function of river feature, bed roughness, and flow velocity are described in the stream-wise and lateral directions. This effort was supported by the Office of Naval Research Coastal Geosciences Program.

  14. Mekong River flow and hydrological extremes under climate change

    Directory of Open Access Journals (Sweden)

    L. P. Hoang

    2015-11-01

    Full Text Available Climate change poses critical threats to water related safety and sustainability in the Mekong River basin. Hydrological impact signals derived from CMIP3 climate change scenarios, however, are highly uncertain and largely ignore hydrological extremes. This paper provides one of the first hydrological impact assessments using the most recent CMIP5 climate change scenarios. Furthermore, we model and analyse changes in river flow regimes and hydrological extremes (i.e. high flow and low flow conditions. Similar to earlier CMIP3-based assessments, the hydrological cycle also intensifies in the CMIP5 climate change scenarios. The scenarios ensemble mean shows increases in both seasonal and annual river discharges (annual change between +5 and +16 %, depending on location. Despite the overall increasing trend, the individual scenarios show differences in the magnitude of discharge changes and, to a lesser extent, contrasting directional changes. We further found that extremely high flow events increase in both magnitude and frequency. Extremely low flows, on the other hand, are projected to occur less often under climate change. Higher low flows can help reducing dry season water shortage and controlling salinization in the downstream Mekong Delta. However, higher and more frequent peak discharges will exacerbate flood risk in the basin. The implications of climate change induced hydrological changes are critical and thus require special attention in climate change adaptation and disaster-risk reduction.

  15. Mekong River flow and hydrological extremes under climate change

    Science.gov (United States)

    Phi Hoang, Long; Lauri, Hannu; Kummu, Matti; Koponen, Jorma; van Vliet, Michelle T. H.; Supit, Iwan; Leemans, Rik; Kabat, Pavel; Ludwig, Fulco

    2016-07-01

    Climate change poses critical threats to water-related safety and sustainability in the Mekong River basin. Hydrological impact signals from earlier Coupled Model Intercomparison Project phase 3 (CMIP3)-based assessments, however, are highly uncertain and largely ignore hydrological extremes. This paper provides one of the first hydrological impact assessments using the CMIP5 climate projections. Furthermore, we model and analyse changes in river flow regimes and hydrological extremes (i.e. high-flow and low-flow conditions). In general, the Mekong's hydrological cycle intensifies under future climate change. The scenario's ensemble mean shows increases in both seasonal and annual river discharges (annual change between +5 and +16 %, depending on location). Despite the overall increasing trend, the individual scenarios show differences in the magnitude of discharge changes and, to a lesser extent, contrasting directional changes. The scenario's ensemble, however, shows reduced uncertainties in climate projection and hydrological impacts compared to earlier CMIP3-based assessments. We further found that extremely high-flow events increase in both magnitude and frequency. Extremely low flows, on the other hand, are projected to occur less often under climate change. Higher low flows can help reducing dry season water shortage and controlling salinization in the downstream Mekong Delta. However, higher and more frequent peak discharges will exacerbate flood risks in the basin. Climate-change-induced hydrological changes will have important implications for safety, economic development, and ecosystem dynamics and thus require special attention in climate change adaptation and water management.

  16. Remote Monitoring of Subsurface Flow Conditions in Rivers

    Science.gov (United States)

    2013-09-30

    measured by the ADV. The colored stars represent the run mean flow magnitudes obtained by the 3 methods: DPIV, OF and SAS. TKE Dissipation The...Mech., vol. 77, 531-560. Korchoka Y. M. (1968). Investigation of the dune movement of sediments on the Polomet’ River. Sov. Hydrol. 541-559. McKenna

  17. A fuzzy-autoregressive model of daily river flows

    Science.gov (United States)

    Greco, Roberto

    2012-06-01

    A model for the identification of daily river flows has been developed, consisting of the combination of an autoregressive model with a fuzzy inference system. The AR model is devoted to the identification of base flow, supposed to be described by linear laws. The fuzzy model identifies the surface runoff, by applying a small set of linguistic statements, deriving from the knowledge of the physical features of the nonlinear rainfall-runoff transformation, to the inflow entering the river basin. The model has been applied to the identification of the daily flow series of river Volturno at Cancello-Arnone (Southern Italy), with a drainage basin of around 5560 km2, observed between 1970 and 1974. The inflow was estimated on the basis of daily precipitations registered during the same years at six rain gauges located throughout the basin. The first two years were used for model training, the remaining three for the validation. The obtained results show that the proposed model provides good predictions of either low river flows or high floods, although the analysis of residuals, which do not turn out to be a white noise, indicates that the cause and effect relationship between rainfall and runoff is not completely identified by the model.

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

    NARCIS (Netherlands)

    Paarlberg, Andries J.; Dohmen-Janssen, C. Marjolein; Hulscher, Susanne 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

  19. Flow dynamics at a river confluence on Mississippi River: field measurement and large eddy simulation

    Science.gov (United States)

    Le, Trung; Khosronejad, Ali; Bartelt, Nicole; Woldeamlak, Solomon; Peterson, Bonnie; Dewall, Petronella; Sotiropoulos, Fotis; Saint Anthony Falls Laboratory, University of Minnesota Team; Minnesota Department of Transportation Team

    2015-11-01

    We study the dynamics of a river confluence on Mississippi River branch in the city of Minneapolis, Minnesota, United States. Field measurements by Acoustic Doppler Current Profiler using on-board GPS tracking were carried out for five campaigns in the summer of 2014 and 2015 to collect both river bed elevation data and flow fields. Large Eddy Simulation is carried out to simulate the flow field with the total of 100 million grid points for the domain length of 3.2 km. The simulation results agree well with field measurements at measured cross-sections. The results show the existence of wake mode on the mixing interface of two branches near the upstream junction corner. The mutual interaction between the shear layers emanating from the river banks leading to the formation of large scale energetic structures that leads to ``switching'' side of the flow coherent structures. Our result here is a feasibility study for the use of eddy-resolving simulations in predicting complex flow dynamics in medium-size natural rivers. This work is funded by Minnesota Dept. Transportation and Minnesota Institute of Supercomputing.

  20. 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. PMID:26207997

  1. Evaluation of Spatial Pattern of Altered Flow Regimes on a River Network Using a Distributed Hydrological Model.

    Directory of Open Access Journals (Sweden)

    Masahiro Ryo

    Full Text Available 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.

  2. 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.

  3. Distributed modeling of monthly air temperatures over the rugged terrain of the Yellow River Basin

    Institute of Scientific and Technical Information of China (English)

    ZENG Yan; QIU XinFa; HE YongJian; SHI GuoPing; LIU ChangMing

    2009-01-01

    Our analyses of the monthly mean air temperature of meteorological stations show that altitude, global solar radiation and surface effective radiation have a significant impact on air temperature. We set up a physically-based empirical model for monthly air temperature simulation. Combined the proposed model with the distributed modeling results of global solar radiation and routine meteorological ob-servation data, we also developed a method for the distributed simulation of monthly sir temperatures over rugged terrain. Spatial distribution maps are generated at a resolution of 1 km×1 km for the monthly mean, the monthly mean maximum and the monthly mean minimum air temperatures for the Yellow River Basin. Analysis shows that the simulation results reflect to a considerable extent the macro and local distribution characteristics of air temperature. Cross-validation shows that the pro-posed model displays good stability with mean absolute bias errors of 0.19℃-0.35℃. Tests carried out on local meteorological station data and case year data show that the model has good spatial and temporal simulation capacity. The proposed model solely uses routine meteorological data and can be applied easily to other regions.

  4. Distributed modeling of monthly air temperatures over the rugged terrain of the Yellow River Basin

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Our analyses of the monthly mean air temperature of meteorological stations show that altitude,global solar radiation and surface effective radiation have a significant impact on air temperature.We set up a physically-based empirical model for monthly air temperature simulation.Combined the proposed model with the distributed modeling results of global solar radiation and routine meteorological observation data,we also developed a method for the distributed simulation of monthly air temperatures over rugged terrain.Spatial distribution maps are generated at a resolution of 1 km×1 km for the monthly mean,the monthly mean maximum and the monthly mean minimum air temperatures for the Yellow River Basin.Analysis shows that the simulation results reflect to a considerable extent the macro and local distribution characteristics of air temperature.Cross-validation shows that the proposed model displays good stability with mean absolute bias errors of 0.19℃-0.35℃.Tests carried out on local meteorological station data and case year data show that the model has good spatial and temporal simulation capacity.The proposed model solely uses routine meteorological data and can be applied easily to other regions.

  5. Stochastic Modelling of Shiroro River Stream flow Process

    Directory of Open Access Journals (Sweden)

    Musa, J. J

    2013-01-01

    Full Text Available 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 model involves some basic steps such as obtain stream flow record and other information, Selecting models that best describes the marginal probability distribution of flows. The flow discharge of about 22 years (1990-2011 was gotten from the Meteorological Station at Shiroro and analyzed with three different models namely; Autoregressive (AR model, Autoregressive Moving Average (ARMA model and Autoregressive Integrated Moving Average (ARIMA model. The initial model identification is done by using the autocorrelation function (ACF and partial autocorrelation function (PACF. Based on the model analysis and evaluations, proper predictions for the effective usage of the flow from the river for farming activities and generation of power for both industrial and domestic us were made. It also highlights some recommendations to be made to utilize the possible potentials of the river effectively

  6. How will climate change modify river flow regimes in Europe?

    Directory of Open Access Journals (Sweden)

    C. Schneider

    2013-01-01

    Full Text Available Worldwide, flow regimes are being modified by various anthropogenic impacts and climate change induces an additional risk. Rising temperatures, declining snow cover and changing precipitation patterns will interact differently at different locations. Consequently, in distinct climate zones, unequal consequences can be expected in matters of water stress, flood risk, water quality, and food security. In particular, river ecosystems and their vital ecosystem services will be compromised as their species richness and composition have evolved over long time under natural flow conditions. This study aims at evaluating the exclusive impacts of climate change on river flow regimes in Europe. Various flow characteristics are taken into consideration and diverse dynamics are identified for each distinct climate zone in Europe. In order to simulate present-day natural flow regimes and future flow regimes under climate change, the global hydrology model WaterGAP3 is applied. All calculations for current and future conditions (2050s are carried out on a 5' × 5' European grid. To address uncertainty, bias-corrected climate forcing data of three different global climate models are used to drive WaterGAP3. Finally, the hydrological alterations of different flow characteristics are quantified by the Indicators of Hydrological Alteration approach. Results of our analysis indicate that on the European scale, climate change can be expected to modify flow regimes remarkably. This is especially the case in the Mediterranean (due to drier conditions with reduced precipitation across the year and in the boreal climate zone (due to reduced snowmelt, increased precipitation, and strong temperature rises. In the temperate climate zone, impacts increase from oceanic to continental. Regarding single flow characteristics, strongest impacts on timing were found for the boreal climate zone. This applies for both high and low flows. Flow magnitudes, in turn, will be

  7. How will climate change modify river flow regimes in Europe?

    Directory of Open Access Journals (Sweden)

    C. Schneider

    2012-08-01

    Full Text Available Worldwide, flow regimes are being modified by various anthropogenic impacts and climate change induces an additional risk. Rising evapotranspiration rates, declining snow cover and changing precipitation patterns will interact differently at different locations. Consequently, in distinct climate zones, unequal consequences can be expected in matters of water stress, flood risk, water quality, and food security. In particular, river ecosystems and their vital ecosystem services will be compromised as their species richness and composition have evolved over long time under natural flow conditions. This study aims at evaluating the exclusive impacts of climate change on river flow regimes in Europe. Various flow characteristics are taken into consideration and diverse dynamics are identified for each distinct climate zone in Europe. In order to simulate natural and modified flow regimes, the global hydrology model WaterGAP3 is applied. All calculations for current and future conditions (2050s are carried out on a 5' × 5' European grid. To address uncertainty, climate forcing data of three different global climate models are used to drive WaterGAP3. Finally, the hydrological alterations of different flow characteristics are quantified by the Indicators of Hydrological Alteration approach. Results of our analysis indicate that on European scale, climate change can be expected to modify flow regimes significantly. This is especially the case in the Mediterranean climate zone (due to drier conditions with reduced precipitation across the year and in the continental climate zone (due to reduced snowmelt and drier summers. Regarding single flow characteristics, strongest impacts on timing were found for the boreal climate zone. This applies for both, high and low flows. While low flow magnitudes are likely to be stronger influenced in the Mediterranean climate, high flow magnitudes will be mainly altered in snow climates with warmer summers. At the end

  8. Effects of Flaming Gorge Dam hydropower operations on flow and stage in the Green River, Utah and Colorado

    Energy Technology Data Exchange (ETDEWEB)

    Yin, S.C.L.; Cho, H.E. [Argonne National Lab., IL (United States). Environmental Assessment Div.; McCoy, J.J.; Palmer, S.C. [Western Area Power Administration, Salt Lake City, UT (United States)

    1995-05-01

    This report presents the development of Flaming Gorge Reservoir release patterns and resulting downstream flows and stages for four potential hydropower operational scenarios. The release patterns were developed for three representative hydrologic years: moderate, dry, and wet. Computer models were used to estimate flows and stages in the Green River resulting from these release patterns for the moderate water year. The four hydropower operational scenarios for Flaming Gorge Dam were year-round high fluctuating flows, seasonally adjusted high fluctuating flows, seasonally adjusted moderate fluctuating flows, and seasonally adjusted steady flows. The year-round high fluctuating flow scenario assumes that the monthly total reservoir releases would be the same as historical releases. The remaining seasonally adjusted flow scenarios would comply with the 1992 Biological Opinion of the US Fish and Wildlife Service, which requires high flows in the spring and limited hourly fluctuations, especially in summer and autumn releases, to protect endangered fish. Within one year, the maximum daily river stage fluctuations resulting from hydropower operations under the seasonally adjusted high fluctuating flow scenario would be similar to the maximum daily fluctuations under the year-round high fluctuating flow scenario. However, reduced or no fluctuations would occur in some time periods under the former scenario. The maximum daily river stage fluctuations under the seasonally adjusted moderate fluctuating flow scenario would be about half of those under the seasonally adjusted high fluctuating flow scenario.

  9. An engineering based approach for hydraulic computations in river flows

    Science.gov (United States)

    Di Francesco, S.; Biscarini, C.; Pierleoni, A.; Manciola, P.

    2016-06-01

    This paper presents an engineering based approach for hydraulic risk evaluation. The aim of the research is to identify a criteria for the choice of the simplest and appropriate model to use in different scenarios varying the characteristics of main river channel. The complete flow field, generally expressed in terms of pressure, velocities, accelerations can be described through a three dimensional approach that consider all the flow properties varying in all directions. In many practical applications for river flow studies, however, the greatest changes occur only in two dimensions or even only in one. In these cases the use of simplified approaches can lead to accurate results, with easy to build and faster simulations. The study has been conducted taking in account a dimensionless parameter of channels (ratio of curvature radius and width of the channel (R/B).

  10. Reconstruction, prediction and simulation of multiple monthly stream-flow series

    Directory of Open Access Journals (Sweden)

    L. TORELLI

    1976-06-01

    Full Text Available The logarithms of monthly stream-flows are usually found to have a Normal distribution. Stream-flow series are auto-correlated up to a given time lag s. Moreover stream-flow series of the same region are cross correlated.

  11. Characterization of river flow fluctuations via horizontal visibility graphs

    Science.gov (United States)

    Braga, A. C.; Alves, L. G. A.; Costa, L. S.; Ribeiro, A. A.; de Jesus, M. M. A.; Tateishi, A. A.; Ribeiro, H. V.

    2016-02-01

    We report on a large-scale characterization of river discharges by employing the network framework of the horizontal visibility graph. By mapping daily time series from 141 different stations of 53 Brazilian rivers into complex networks, we present a useful approach for investigating the dynamics of river flows. We verified that the degree distributions of these networks were well described by exponential functions, where the characteristic exponents are almost always larger than the value obtained for random time series. The faster-than-random decay of the degree distributions is an another evidence that the fluctuation dynamics underlying the river discharges has a long-range correlated nature. We further investigated the evolution of the river discharges by tracking the values of the characteristic exponents (of the degree distribution) and the global clustering coefficients of the networks over the years. We show that the river discharges in several stations have evolved to become more or less correlated (and displaying more or less complex internal network structures) over the years, a behavior that could be related to changes in the climate system and other man-made phenomena.

  12. A Wavelet Neural Network Hybrid Model for Monthly Ammonia Forecasting in River Water

    Directory of Open Access Journals (Sweden)

    Yi Wang

    2013-06-01

    Full Text Available Forecasting water quality is always an effective approach for water environmental management. This study presents a combined Wavelet transform (WA and Artificial Neural Network (ANN model for monthly ammonia nitrogen series prediction in river water. The WA decomposed original time series into different subseries, in which the most significant one was chosen as the training data instead of the original series. Compared to the traditional ANN, the WA-ANN models were found more accurate and reliable. The results of the study indicate that WA could remove the noise of the original datasets and the WA-ANN could help environment decision-maker manage water quality more effective.

  13. 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.

  14. A Distributed Monthly Water Balance Model for Analyzing Impacts of Land Cover Change on Flow Regimes

    Institute of Scientific and Technical Information of China (English)

    XIA Jun; WANG Gang-Sheng; YE Ai-Zhong; NIU Cun-Wen

    2005-01-01

    The Miyun Reservoir is the most important water source for Beijing Municipality, the capital of China with a population of more than 12 million. In recent decades, the inflow to the reservoir has shown a decreasing trend, which has seriously threatened water use in Beijing. In order to analyze the influents of land use and cover change (LUCC)upon inflow to Miyun Reservoir, terrain and land use information from remote sensing were utilized with a revised evapotranspiration estimation formula; a water loss model under conditions of human impacts was introduced; and a distributed monthly water balance model was established and applied to the Chaobai River Basin controlled by the Miyun Reservoir. The model simulation suggested that not only the impact of land cover change on evapotranspiration, but also the extra water loss caused by human activities, such as the water and soil conservation development projects should be considered. Although these development projects were of great benefit to human and ecological protection, they could reallocate water resources in time and space, and in a sense thereby influence the stream flow.

  15. Inferring Aquifer Transmissivity from River Flow Data

    Science.gov (United States)

    Trichakis, Ioannis; Pistocchi, Alberto

    2016-04-01

    Daily streamflow data is the measurable result of many different hydrological processes within a basin; therefore, it includes information about all these processes. In this work, recession analysis applied to a pan-European dataset of measured streamflow was used to estimate hydrogeological parameters of the aquifers that contribute to the stream flow. Under the assumption that base-flow in times of no precipitation is mainly due to groundwater, we estimated parameters of European shallow aquifers connected with the stream network, and identified on the basis of the 1:1,500,000 scale Hydrogeological map of Europe. To this end, Master recession curves (MRCs) were constructed based on the RECESS model of the USGS for 1601 stream gauge stations across Europe. The process consists of three stages. Firstly, the model analyses the stream flow time-series. Then, it uses regression to calculate the recession index. Finally, it infers characteristics of the aquifer from the recession index. During time-series analysis, the model identifies those segments, where the number of successive recession days is above a certain threshold. The reason for this pre-processing lies in the necessity for an adequate number of points when performing regression at a later stage. The recession index derives from the semi-logarithmic plot of stream flow over time, and the post processing involves the calculation of geometrical parameters of the watershed through a GIS platform. The program scans the full stream flow dataset of all the stations. For each station, it identifies the segments with continuous recession that exceed a predefined number of days. When the algorithm finds all the segments of a certain station, it analyses them and calculates the best linear fit between time and the logarithm of flow. The algorithm repeats this procedure for the full number of segments, thus it calculates many different values of recession index for each station. After the program has found all the

  16. The Bermejo River flows beyond its banks.

    Science.gov (United States)

    Porter, C

    1999-03-01

    This article examines the effectiveness of the environmental management approach used by Argentina and Bolivia as a means to a better life for the many impoverished people who live in this area. The approach aims to integrate environmental and development concerns in a plan for the future of the region. With financial support from international agencies, Argentina and Bolivia are conducting a wide-ranging study of a border-spanning watershed that spreads over 190,000 sq. km. The two countries want to learn how to make better decisions about development. These decisions are aimed to preserve the environment and improve economic opportunity for the 1.2 million people of the region. The study conducted will explore ecotourism as a strategy for forest preservation and increased economic opportunity. The two countries have been working together with the Organizations of American States for nearly 20 years. This collaboration is an attempt to improve the condition of the watershed. Efforts to find answers in the Bermejo River basin are motivated by an integrated form of environmental science, the economic hardships of the people of the region, and a new economic dynamism inspired by Mercosur, the Mercado Comun del Sur or Common Market of the South. The Mercosur agreement also places a special emphasis on social justice, efficient use of available resources, and preservation of the environment. The reliable and well-managed water resources are critical to industrialization, and the improvement in the way of life of the people in the Bermejo watershed region.

  17. Characteristics of the Flow and Sediment in the Inner Rivers Broad-shallow Shifting Reach

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Rivers are classified into two types.One is the outer river which flows into ocean and the other is the inner river which does not flow into the ocean but into desert or lake.The inner rivers are the erosive rivers that have been seldom studied so far.Based on the field survey data,the analysis on the characteristics of the flow and sediment in the inner rivers' broad-shallow shifting (IRBS) reach.The IRBS reach often bears such the properties as:high gradient bed,usually 10‰or greater;small flow dischar...

  18. Influences of North Atlantic climate variability on low-flows in the Connecticut River Basin

    Science.gov (United States)

    Steinschneider, Scott; Brown, Casey

    2011-10-01

    SummaryConnections between summertime, ecologically relevant low-flow indicators and both winter and spring climate phenomena are explored for the Connecticut River Basin, with an emphasis on assessing forecast potential. Low-flow streamflow statistics deemed important for ecological health, including minimum 1-day mean flows, minimum 7-day mean flows, and monthly streamflow averages from June to September, are derived from 61 years of continuous, daily streamflow data at 15 United States Geological Survey streamflow gauging stations across the basin. Relationships between the ecological flow indicators with leading sea-surface temperature and sea-level pressure are investigated using correlation and composite analysis. Results suggest lagged relationships of up to 5 months between summer streamflow and the wintertime North Atlantic Oscillation, springtime east coast pressure trough, and springtime North Atlantic Tripole. These climate states have been linked to shifts between zonal and meridonal airflow as well as sea-surface temperature anomalies off the coast of the eastern US, both of which have implications for the movement of moisture systems over the study region. This study suggests that residual influences on airflow and sea-surface temperature persist into the summer following these earlier climate states, influencing low-flow hydrology in the region. As eco-hydrologic flow targets often conflict with other stakeholder objectives within a watershed, reservoir operators may utilize such lagged teleconnection patterns to predict annual low-flow characteristics in the region and help negotiate tradeoffs between traditional water management objectives and those emphasizing ecological conservation.

  19. Nutrient flows and related impacts between a Mediterranean river and the associated coastal area

    Science.gov (United States)

    Markogianni, Vassiliki; Varkitzi, Ioanna; Pagou, Kalliopi; Dimitriou, Elias

    2017-02-01

    Taking into consideration the Water Framework Directive's requirements, water samples were collected monthly and/or bimonthly between 2014 and 2015 from Spercheios River, its estuary and the adjacent Maliakos Gulf in order to assess the quality of these water bodies. A study on dissolved nitrate, nitrite, ammonium, phosphate and chlorophyll-a concentrations was carried out, to investigate the impact between the river and the associated coastal area and assess the nutrient loads based on water flows from Spercheios River into the marine system.Furthermore a seasonal distribution of nutrient concentrations have been studied, dividing the sampling period into dry and wet season according to the river's discharges. Correlation analysis and hierarchical cluster analysis among the available chemical data were conducted in order to enhance the detection of the two systems' interaction. Nutrients' concentrations increased from upstream to downstream sampling stations, particularly in areas where human-induced activities are detected. Marine samples were characterized by lower nutrient concentrations than the river ones, and the ecological quality of Maliakos Gulf, based on chlorophyll-a values, is characterized as moderate, except for the stations close to the river, which constantly presented poor quality. Chemical analyses and statistical analysis indicated high nutrient flows and a strong impact between the freshwater and marine systems, accompanied by the profound effect of the adjacent aquafarming areas and the wastewater treatment plant of Lamia city. The highest nutrients' and chlorophyll-a values of the coastal stations were detected close to the river mouth and they were decreasing towards the outer Maliakos Gulf.

  20. 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

  1. Effects of Reducing River Flow on Pulse Residence Time in Little Manatee River, USA

    Institute of Scientific and Technical Information of China (English)

    HUANG Wenrui; LIU Xiaohai

    2009-01-01

    Residence time is an important indicator for river environmental management. In this paper, a 3D hydrody-namic model has been successfully applied to Little Manatee River to characterize the mixing and transport process and residence time. The model employs horizontal curvilinear orthogonal grids to represent the complex river system that consists of branches and bayous. The model has been satisfactorily calibrated and verified by using two continuous data sets. The data sets consist of hourly observations of all forcing boundaries, including freshwater inputs, tides, winds, salin-ity and temperatures at bay boundary, and air temperatures for model simulations. The data sets also consist of hourly observations of water levels, salinity, and temperature at several river stations. The calibrated and verified hydrodynamic model was used to predict residence time in the Little Manatee River. Under the minimum flow of 0.312 m3/s, the pulse residence time (PRT) is 108 days. Model simulations were also conducted for 17 flow scenarios. Empirical regression equations have been satisfactorily derived to correlate PRT to freshwater inflow. Correlation coefficient R2 is 0.982 for PRT.

  2. 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.

  3. Impact of climate change on freshwater ecosystems: a global-scale analysis of ecologically relevant river flow alterations

    Directory of Open Access Journals (Sweden)

    P. Döll

    2010-05-01

    Full Text Available River flow regimes, including long-term average flows, seasonality, low flows, high flows and other types of flow variability, play an important role for freshwater ecosystems. Thus, climate change affects freshwater ecosystems not only by increased temperatures but also by altered river flow regimes. However, with one exception, transferable quantitative relations between flow alterations and ecological responses have not yet been derived. While discharge decreases are generally considered to be detrimental for ecosystems, the effect of future discharge increases is unclear. As a first step towards a global-scale analysis of climate change impacts on freshwater ecosystems, we quantified the impact of climate change on five ecologically relevant river flow indicators, using the global water model WaterGAP 2.1g to simulate monthly time series of river discharge with a spatial resolution of 0.5 degrees. Four climate change scenarios based on two global climate models and two greenhouse gas emissions scenarios were evaluated.

    We compared the impact of climate change by the 2050s to the impact of water withdrawals and dams on natural flow regimes that had occurred by 2002. Climate change was computed to alter seasonal flow regimes significantly (i.e. by more than 10% on 90% of the global land area (excluding Greenland and Antarctica, as compared to only one quarter of the land area that had suffered from significant seasonal flow regime alterations due to dams and water withdrawals. Due to climate change, the timing of the maximum mean monthly river discharge will be shifted by at least one month on one third on the global land area, more often towards earlier months (mainly due to earlier snowmelt. Dams and withdrawals had caused comparable shifts on less than 5% of the land area only. Long-term average annual river discharge is predicted to significantly increase on one half of the land area, and to significantly decrease on one quarter

  4. Impact of climate change on freshwater ecosystems: a global-scale analysis of ecologically relevant river flow alterations

    Directory of Open Access Journals (Sweden)

    P. Döll

    2010-02-01

    Full Text Available River flow regimes, including long-term average flows, seasonality, low flows, high flows and other types of flow variability, play an important role for freshwater ecosystems. Thus, climate change affects freshwater ecosystems not only by increased temperatures but also by altered river flow regimes. However, with one exception, transferable quantitative relations between flow alterations and ecosystem responses have not yet been derived. While discharge decreases are generally considered to be detrimental for ecosystems, the effect of future discharge increases is unclear. As a first step towards a global-scale analysis of climate change impacts on freshwater ecosystems, we quantified the impact of climate change on five ecologically relevant river flow indicators, using the global water model WaterGAP 2.1g to simulate monthly time series of river discharge with a spatial resolution of 0.5 degrees. Four climate change scenarios based on two global climate models and two greenhouse gas emissions scenarios were evaluated.

    We compared the impact of climate change by the 2050s to the impact of water withdrawals and dams on natural flow regimes that had occurred by 2002. Climate change was computed to alter seasonal flow regimes significantly (i.e. by more than 10% on 90% of the global land area (excluding Greenland and Antarctica, as compared to only one quarter of the land area that had suffered from significant seasonal flow regime alterations due to dams and water withdrawals. Due to climate change, the timing of the maximum mean monthly river discharge will be shifted by at least one month on one third on the global land area, more often towards earlier months (mainly due to earlier snowmelt. Dams and withdrawals had caused comparable shifts on less than 5% of the land area only. Long-term average annual river discharge is predicted to significantly increase on one half of the land area, and to significantly decrease on one quarter

  5. Trends in seasonal river flow regimes in the UK

    Science.gov (United States)

    Hannaford, J.; Buys, G.

    2012-12-01

    SummaryA wide range of hydrological trend studies have been published for the UK, but there has not previously been a UK-wide assessment of changes in seasonal river flow regimes in a large number of catchments reflecting the diversity of UK rivers. This represents a gap in research, as climate change impacts are likely to vary regionally and seasonally, and seasonal river flows form the basis of many climate change impact assessments. This study attempts to fill this gap, by analysing trends over the 1969-2008 period in a network of 89 catchments from across the UK. Many UK catchments are heavily disturbed by human influences, so this study primarily focuses on catchments with near-natural flow regimes, to enable climate-driven trends to be distinguished from direct anthropogenic disturbances such as river regulation and abstractions. Trends are characterised for four standard seasons (December-February, March-May, June-August, September-November), for seven flow quantiles. Particular emphasis is placed on examining spatial patterns in observed trend magnitude for median, high and low flows. A set of eight catchments with long records (starting in the 1930s or earlier) are used to assess the representativeness of recent trends in a long-term context, via a moving window trend analysis. The results of this study suggest a much more complex pattern of regional and seasonal variation than revealed in previous work. Some findings resonate with observed rainfall changes, and also with potential future climate change - e.g. increased runoff and high flows in winter and autumn, and decreased flows in spring. The latter is a result which is sensitive to study period, and is not observed in longer records. In summer, there is no compelling evidence for a decrease in overall runoff or low flows, which is contrary to trajectories of most future projections. Overall, the results do not suggest immediate concern for current water resource management on the basis of observed

  6. Modelling of the monthly and daily behaviour of the runoff of the Xallas river using Box-Jenkins and neural networks methods

    Science.gov (United States)

    Castellano-Méndez, María.; González-Manteiga, Wenceslao; Febrero-Bande, Manuel; Manuel Prada-Sánchez, José; Lozano-Calderón, Román

    2004-08-01

    This paper presents a study of the hydrological behaviour of the Xallas river basin in the northwest of Spain, based on modelling the performance of the runoff produced by the river at different temporal scales. For monthly mean runoff as well as mean rainfall forecasting, Box-Jenkins models have been used. For short-term daily flow predictions, two statistical techniques were tested and compared: the classic statistical Box-Jenkins models and artificial neural networks (ANNs). The performance of the ANN was an improvement on the Box-Jenkins results. The neural networks capability of modelling a complex rainfall-runoff relationship has been observed. Although the neural network's performance was not satisfactory for detecting some peak flows, the results were most promising.

  7. Impacts of climate change on ecologically relevant river flow characteristics in the Danube river catchment

    Science.gov (United States)

    Stagl, Judith; Hattermann, Fred F.

    2014-05-01

    River flow characteristics reflecting flow seasonality and variability such as low and high flow durations play an important role for aquatic, wetland and riparian ecosystems. Climate change might not only alter long term average flows, but also affect the hydrologic regime on smaller scales. The Indicators of Hydrological Alteration (IHA) statistics (Richter et al. 1996) characterize changes in hydrologic regime by using a suite of ecologically relevant indicators given a daily discharge time series. Eco-hydrological indicators are applied to bridge the communication gap that exists between professionals in the fields of hydrology and ecology. Such indicators can help to synthesize complex hydrological variables into ecologically-meaningful information. For this study the eco-hydrological watershed model SWIM was applied for the whole Danube river catchment using 1224 subbasins. The SWIM model (Soil and Water Integrated Model) is a continuous-time semi-distributed watershed model, which combines hydrological processes, vegetation, erosion and nutrient dynamics at the meso- to macroscale (Krysanova et al. 1998, 2000). As the Danube river basin is climatically heterogeneous, it is characterized by a changing-complex river runoff regime varying from nival regimes in the alpine parts to mainly rain feed regimes in the lowlands. To account for these different river regimes of the Danubian tributaries, the SWIM model was calibrated separately for the major river subbasins. After calibration and validation of the model, this study uses a set of 14 high-resolution climate change projections performed by several state-of-art GCMs and RCMs, all based on the IPCC-SRES-A1B emission scenario, from the ENSEMBLES project (EU FP6). They serve as meteorological drivers for the SWIM model to simulate future daily time series of river discharge under different scenario conditions. The derived hydrologic data series then were statistically analyzed by using selected eco

  8. Seasonality of low flows and dominant processes in the Rhine River

    NARCIS (Netherlands)

    Tongal, H.; Demirel, M.C.; Booij, M.J.

    2013-01-01

    Low flow forecasting is crucial for sustainable cooling water supply and planning of river navigation in the Rhine River. The first step in reliable low flow forecasting is to understand the characteristics of low flow. In this study, several methods are applied to understand the low flow characteri

  9. Using regional flow classes as references to analyse flow regime anomalies across a set of regulated Canadian rivers

    Science.gov (United States)

    McLaughlin, Fraser; Lapointe, Michel; Bourque, Guillaume; Boisclair, Daniel

    2014-11-01

    It is well established that a river's natural flow regime is a key determinant of ecological integrity and that dam regulated-flow releases can be detrimental to biotic communities and even affect river ecosystem structure (e.g. Poff and Zimmerman, 2010). Regional flow classes, groups of rivers that share similar natural flow regimes (called ‘river types' by Poff and Zimmerman (2010)) and to which regional fish communities are ‘adapted', have been proposed as units of analysis to identify significant damming related flow alteration (e.g. Poff, 1996; Poff and Zimmerman, 2010; McManamay et al., 2012a). Specifically, the natural range of flow behaviour within regional classes can be used to identify clearly anomalous flow features in rivers regulated by dams. Through ordination analysis on 70 ecologically important flow indices, we isolated five distinctive regional groupings of natural flow regimes among the 96 unregulated rivers located in study regions of South Eastern and South Western Canada, selected based on watershed characteristics as possible references for the 13 hydro-regulated, NSERC-HydroNet study rivers in British Columbia, Alberta, Ontario, Quebec and New Brunswick. The distinguishing characteristics of natural flow regimes within each flow class are explored through visualization in principal component space. The 16 regulated HydroNet sites were assigned to appropriate regional flow classes through discriminant function analysis based on shared geographic location and watershed characteristics. Anomalous flow features in the regulated rivers are then characterized by type and strength, based on identification of flow indices that are significantly different from observed natural variability in the relevant regional class. The magnitude distributions and the main axes of variability in index anomalies are analysed, across regions and regulation types (storage, peaking and run-of-the-river (RoR)). We also discuss the potential biological

  10. Flow and salinity characteristics of the upper Suwannee River Estuary, Florida

    Science.gov (United States)

    Tillis, Gina M.

    2000-01-01

    Continuous stage and salinity data were recorded from August 1995 to December 1997 at four gages located in the upper Suwannee River Estuary. Continuous velocity data were recorded at two of the four gages and continuous discharge data were computed for these two gages. Additional salinity data were collected at 15 monitoring sites from November 1992 to October 1997. Wind-speed data collected at Cedar Key, Florida, during the study period were utilized in the regression analysis. Correlations were developed to describe the longitudinal extent of the saltwater/freshwater interface (defined as 0.5 parts per thousand (ppt) salinity) and salinity distribution in the upper Suwannee River Estuary. On East Pass, the median of difference between daily maximum and daily minimum stage ranged from 2.92 feet for a gage at river mile 3.8 to 3.33 feet for a gage at river mile 1.2. Velocities tended to be unidirectional with some instances of bilateral flow. Reversal in flow direction was common and coincided with rising tides. Monthly mean discharges for the Suwannee River near Wilcox, Florida, during the study period typically were lower than the average for the period of record (1931.97). Discharge near Wilcox averaged 4,000 cubic feet per second (ft3/s) lower than the long-term average from June to September 1996. An El Ni?o event induced precipitation that was responsible for higher than average monthly mean discharge measured near Wilcox during November and December 1997. The maximum observed salinity concentrations for the study period ranged from 28.20 ppt at river mile 3.8 to 31.00 ppt at river mile 1.9. Median daily fluctuations of salinity at river miles 3.8 and 1.2 were 0.12 and 11.31 ppt, respectively. The maximum daily upstream extent of the saltwater/freshwater interface was at or upstream from river mile 4.0 for about 50 percent of the study period. The interface was at or upstream from river mile 3.8 and river mile 2.8 40 and 57 percent of the time. The interface

  11. 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.

  12. 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.

  13. 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...

  14. Environmental Flow Assessments in the McKenzie and Santiam River Basins, Oregon

    Science.gov (United States)

    Risley, J. C.; Bach, L.; Budai, C.; Duffy, K.

    2012-12-01

    The McKenzie and Santiam Rivers are tributaries of the Willamette River in northwestern Oregon, draining areas of 3,370 and 4,690 square kilometers, respectively. The river basins are heavily forested and contain streams that historically provided critical habit for salmonid rearing, salmonid spawning, and bull trout. In the 1950s and 1960s, hydropower and flood control dams were constructed in both basins. In 2008, the U.S. Geological Survey (USGS), in cooperation with The Nature Conservancy (TNC) and the U.S. Army Corps of Engineers (Corps), began assessing the impacts of dam regulation in the two basins on streamflow, geomorphic, and ecological processes (Risley et. al., 2010; 2012). The baseline assessments were made under the auspices of the Sustainable Rivers Project (SRP), formed in 2002 by TNC and the Corps. SRP is a nation-wide partnership aimed at developing, implementing, and refining environmental flows downstream of dams. Environmental flows can be defined as the streamflow needed to sustain ecosystems while continuing to meet human needs. Determining environmental flows is an iterative collective process involving stakeholders, workshops, bio-monitoring, and follow-up assessments. The dams on the McKenzie and Santiam Rivers have decreased the frequency and magnitude of floods and increased the magnitude of low flows. In the Santiam River study reaches, for example, annual 1-day maximum streamflows decreased by 46-percent on average because of regulated streamflow conditions. Annual 7-day minimum flows in six of the seven study reaches increased by 146 percent on average. On a seasonal basis, median monthly streamflows in both river basins decreased from February to May and increased from September to January. However, the magnitude of these impacts usually decreased farther downstream from the dams because of the cumulative inflow from unregulated tributaries and groundwater discharge below the dams. In addition to streamflow assessments, the USGS

  15. Providing peak river flow statistics and forecasting in the Niger River basin

    Science.gov (United States)

    Andersson, Jafet C. M.; Ali, Abdou; Arheimer, Berit; Gustafsson, David; Minoungou, Bernard

    2017-08-01

    Flooding is a growing concern in West Africa. Improved quantification of discharge extremes and associated uncertainties is needed to improve infrastructure design, and operational forecasting is needed to provide timely warnings. In this study, we use discharge observations, a hydrological model (Niger-HYPE) and extreme value analysis to estimate peak river flow statistics (e.g. the discharge magnitude with a 100-year return period) across the Niger River basin. To test the model's capacity of predicting peak flows, we compared 30-year maximum discharge and peak flow statistics derived from the model vs. derived from nine observation stations. The results indicate that the model simulates peak discharge reasonably well (on average + 20%). However, the peak flow statistics have a large uncertainty range, which ought to be considered in infrastructure design. We then applied the methodology to derive basin-wide maps of peak flow statistics and their associated uncertainty. The results indicate that the method is applicable across the hydrologically active part of the river basin, and that the uncertainty varies substantially depending on location. Subsequently, we used the most recent bias-corrected climate projections to analyze potential changes in peak flow statistics in a changed climate. The results are generally ambiguous, with consistent changes only in very few areas. To test the forecasting capacity, we ran Niger-HYPE with a combination of meteorological data sets for the 2008 high-flow season and compared with observations. The results indicate reasonable forecasting capacity (on average 17% deviation), but additional years should also be evaluated. We finish by presenting a strategy and pilot project which will develop an operational flood monitoring and forecasting system based in-situ data, earth observations, modelling, and extreme statistics. In this way we aim to build capacity to ultimately improve resilience toward floods, protecting lives and

  16. COUPLING EFFECT OF SEEPAGE FLOW AND RIVER FLOW ON THE BANK FAILURE

    Institute of Scientific and Technical Information of China (English)

    NING Bo; WU Shi-qiang; TAN Ye-fei; XIE Xing-hua; YAN Jun; YAN Zhong-min; GENG Yan-qiong

    2011-01-01

    On the basis of the generalized physical model of the riverbank,the experiments were conducted to study the mechanisms of riverbank failure under the coupling effect of seepage flow and river flow.The experimental setup was specially designed,as well as test point location,parameters and procedures,and the main influencing factors were analyzed affecting riverbank failure based on the failure types,the variations of pore water pressure and soil displacement.The results indicated that the coupling effect has different influences on the bank failure in three aspects:the failure type,the process and the extent.In addition,the river flow played a more important role than the seepage flow in the coupling effect on the bank failure.

  17. Predicting the impact of water demand and river flow regulation over riparian vegetation through mathematical modeling

    Science.gov (United States)

    Garcia-Arias, A.; Pons, C.; Frances, F.

    2013-12-01

    The vegetation of the riversides is a main part of the complex riparian ecosystems and has an important role maintaining the fluvial ecosystems. Biotic and abiotic interactions between the river and the riverbank are essential for the subsistence and the development of both ecosystems. In semi-arid Mediterranean areas, the riparian vegetation growth and distribution is especially controlled by the water accessibility, determining the limit between the lush riparian bands and the sparse upland. Human intervention can alter the river hydrology determining the riparian vegetation wellbeing and its distribution and, in consequence, affecting both riparian and fluvial ecosystems. Predictive models are necessary decision support tools for adequate river management and restoration initiatives. In this context, the RibAV model is useful to predict the impact of water demand and river flow regulation on the riparian vegetation. RibAV is able to reproduce the vegetation performance on the riverside allowing the scenarios analysis in terms of vegetation distribution and wellbeing. In this research several flow regulation and water demand scenarios are proposed and the impacts over three plant functional types (PFTs) are analyzed. The PFTs group the herbaceous riparian plants, the woody riparian plants and the terrestrial vegetation. The study site is the Terde reach at the Mijares River, a 539m length reach located in a semi-arid Mediterranean area in Spain. The scenarios represent river flow alterations required to attend different human demands. These demands encompass different seasonality, magnitude and location. The seasonality is represented as hydroelectric (constant all over the year), urban (increased during the summer period) and agricultural demands (monthly seasonality). The magnitude is varied considering the 20%, the 40% and the 80% of the mean daily flow. Two locations are considered, upstream or downstream the study site. To attend the demands located

  18. Multivariate stochastic analysis for Monthly hydrological time series at Cuyahoga River Basin

    Science.gov (United States)

    zhang, L.

    2011-12-01

    Copula has become a very powerful statistic and stochastic methodology in case of the multivariate analysis in Environmental and Water resources Engineering. In recent years, the popular one-parameter Archimedean copulas, e.g. Gumbel-Houggard copula, Cook-Johnson copula, Frank copula, the meta-elliptical copula, e.g. Gaussian Copula, Student-T copula, etc. have been applied in multivariate hydrological analyses, e.g. multivariate rainfall (rainfall intensity, duration and depth), flood (peak discharge, duration and volume), and drought analyses (drought length, mean and minimum SPI values, and drought mean areal extent). Copula has also been applied in the flood frequency analysis at the confluences of river systems by taking into account the dependence among upstream gauge stations rather than by using the hydrological routing technique. In most of the studies above, the annual time series have been considered as stationary signal which the time series have been assumed as independent identically distributed (i.i.d.) random variables. But in reality, hydrological time series, especially the daily and monthly hydrological time series, cannot be considered as i.i.d. random variables due to the periodicity existed in the data structure. Also, the stationary assumption is also under question due to the Climate Change and Land Use and Land Cover (LULC) change in the fast years. To this end, it is necessary to revaluate the classic approach for the study of hydrological time series by relaxing the stationary assumption by the use of nonstationary approach. Also as to the study of the dependence structure for the hydrological time series, the assumption of same type of univariate distribution also needs to be relaxed by adopting the copula theory. In this paper, the univariate monthly hydrological time series will be studied through the nonstationary time series analysis approach. The dependence structure of the multivariate monthly hydrological time series will be

  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. A RIVER FLOW ROUTING MODEL BASED ON DIGITAL DRAINAGE NETWORK

    Institute of Scientific and Technical Information of China (English)

    YUAN Fei; REN Li-liang; YU Zhong-bo; XU Jing

    2005-01-01

    On the basis of Digital Elevation Model (DEM) data, watershed delineation and spatial topological relationship were proposed by the Digital Elevation Drainage Network Model (DEDNM) for the area upstream of the Hanzhong Hydrological Station in the Hanjiang River in China. Then, the Muskingum-Cunge method considering lateral flow into the river was applied to flood routing on the platform of digital basin derived from DEDNM. Because of considering lateral flow into the river, the Muskingum-Cunge method performs better than the Muskingum method in terms of the Nash-Sutcliffe model efficiency coefficient and the relative error of flood discharge peak value. With a routing-after-superposition algorithm, the Muskingum-Cunge method performs better than the Muskingum method in terms of the Nash-Sutcliffe model efficiency coefficient and the relative error of flood discharge peak value. As a result, the digital basin coupled with the Muskingum-Cunge method provides a better platform for water resources management and flood control.

  1. Glacier melt buffering sustains river flow in the Pamir Mountains

    Science.gov (United States)

    Pohl, Eric; Andermann, Christoff; Gloaguen, Richard

    2017-04-01

    Central Asia's water resources and agricultural practices depend on snow and glacier melts in the high mountains. The Amu Darya, the main river draining the Pamir Mountains, exemplifies the resulting seasonality in stream flow. In winter, comparably low amounts of groundwater discharge feed the streams, while the bulk of precipitation is provided and stored as snow. Successive melting of snow cover and glaciers during summer releases these stored waters to the swelling rivers. Despite a strong variability in precipitation and temperatures over the entire Pamir Mountain region, river flow shows severely less variability. We investigate what processes lead to this apparent discrepancy by using a simple but robust hydrological model that we thoroughly validate with remote sensing snow cover observations, Gravity Recovery and Climate Experiment (GRACE) data, highlighting changes in total water storage, and hydrograph comparison. We find that glaciers play a paramount role by buffering extreme meteorological conditions to sustain stream flow. In a simplified scheme, low precipitation amounts in winter result in small snow stocks, compensated for by more intensive glacier melt, and vice versa. By carrying out analyses over the extensive catchment area of the Amu Darya in the high mountain domain, we highlight regional differences in the effectiveness of this mechanism. Regional influences of wind systems and associated moisture transport as well as glaciated area emerge as main factors. Modeled negative glacier mass balances between -0.38 and -0.93 m/year agree with other studies based on geodetic methods and indicate a future reduction in stream flow sustainability. This not only exacerbates the conflict potential between riparian countries downstream, but also means that extreme weather events are more likely to cause floods and droughts.

  2. 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

  3. 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

    contributed by East River increased and the percentage of flow contributed by Faka Union River decreased, compared to the earlier years. No changes in annual flow occurred at any sites west of Faka Union River. No changes in the relative flow contributions were observed during the wet season; however, the relative amounts of streamflow increased during the dry season at East River in 2014. East River had only 1 month of negative flow in 2014 compared to 6 months in 2011 and 7 months in 2008. Higher dry season flows in East River may be in response to restoration efforts. The sites to the west of Faka Union River had higher salinities on average than Faka Union River and East River. Faka Union River had the highest range in salinities, and Faka Union Boundary had the lowest range in salinities. Pumpkin River was the tributary with the lowest range in salinities.1Water year is defined as the 12-month period from October 1, for any given year, through September 30 of the following year.

  4. Low flow analysis of the lower Drava River

    Science.gov (United States)

    Mijuskovic-Svetinovic, T.; Maricic, S.

    2008-11-01

    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. Estimation of natural historical flows for the Manitowish River near Manitowish Waters, Wisconsin

    Science.gov (United States)

    Juckem, Paul F.; Reneau, Paul C.; Robertson, Dale M.

    2012-01-01

    The Wisconsin Department of Natural Resources is charged with oversight of dam operations throughout Wisconsin and is considering modifications to the operating orders for the Rest Lake Dam in Vilas County, Wisconsin. State law requires that the operation orders be tied to natural low flows at the dam. Because the presence of the dam confounds measurement of natural flows, the U.S. Geological Survey, in cooperation with the Wisconsin Department of Natural Resources, installed streamflow-gaging stations and developed two statistical methods to improve estimates of natural flows at the Rest Lake Dam. Two independent methods were used to estimate daily natural flow for the Manitowish River approximately 1 mile downstream of the Rest Lake Dam. The first method was an adjusted drainage-area ratio method, which used a regression analysis that related measured water yield (flow divided by watershed area) from short-term (2009–11) gaging stations upstream of the Manitowish Chain of Lakes to the water yield from two nearby long-term gaging stations in order to extend the flow record (1991–2011). In this approach, the computed flows into the Chain of Lakes at the upstream gaging stations were multiplied by a coefficient to account for the monthly hydrologic contributions (precipitation, evaporation, groundwater, and runoff) associated with the additional watershed area between the upstream gaging stations and the dam at the outlet of the Chain of Lakes (Rest Lake Dam). The second method used to estimate daily natural flow at the Rest Lake Dam was a water-budget approach, which used lake stage and dam outflow data provided by the dam operator. A water-budget model was constructed and then calibrated with an automated parameter-estimation program by matching simulated flow-duration statistics with measured flow-duration statistics at the upstream gaging stations. After calibration of the water-budget model, the model was used to compute natural flow at the dam from 1973 to

  6. 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.

  7. 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.

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

    Science.gov (United States)

    Pal, I.; Lall, U.; Robertson, A. W.; Cane, M. A.; Bansal, R.

    2013-06-01

    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.

  9. ADCP measured flow current of the middle-lower Changjiang River channel

    Institute of Scientific and Technical Information of China (English)

    Qiang ZHANG; Yafeng SHI; Zhongyuan CHEN; Tong JIANG

    2008-01-01

    The water column flow velocity of 36 river sections in the river reach between Hankou (Wuhan) and Wuxue of the middle-lower Changjiang River.Their cross sectional distribution patterns in relation to the river channel morphologies were examined by using shipmounted ADCP (Acoustic Doppler Current Profiler) instrument.The results indicate four (Ⅰ-Ⅳ) types of river channel morphology associated flow patterns:Ⅰ-laterally deepening riverbed topographic pattern; Ⅱ-symmetrical to asymmetrical riverbed topographic pattern; Ⅲ-relative fiat riverbed topographic pattern,and Ⅳ-sandbar supported riverbed topographic pattern.All these correspond to the different patterns of flow velocity distribution.The maximum flow velocity is usually related to the deeper water depth,but irregular water column distribution of flow current velocity results often from the vortices' current associated with river knots.Deeper river water depth is usually identified in the river reach located slightly downstream to the river knot,where faster flow velocity occurs.Downward change in flow velocity fits semi-log law,showing an exponential decreasing flow current with the maximum flow velocity near the water surface.However,in the river reach near the river knots,the water column distribution of flow current velocity does not fit the semi-log law,showing the irregular flow current pattern.This study,in context of river catchment management,highlights the controls of riverbed morphology to the flow current structure,which will shed light on the post study of Three Gorges damming in 2009.

  10. Urban rivers as conveyors of hydrocarbons to sediments of estuarine areas: source characterization, flow rates and mass accumulation.

    Science.gov (United States)

    Mauad, Cristiane R; Wagener, Angela de L R; Massone, Carlos G; Aniceto, Mayara da S; Lazzari, Letícia; Carreira, Renato S; Farias, Cássia de O

    2015-02-15

    Aliphatic (n-C12-n-C40, unresolved complex mixture, resolved peaks) and aromatic hydrocarbons (46 PAH) were investigated in suspended particulate matter (SPM) sampled over eleven months in six of the major rivers and two channels of the Guanabara Bay Basin. PAH flow rates of the most contaminated rivers, the contribution to the PAH sediment load of the receiving bay, and the main sources of hydrocarbons were determined. PAH (38) ranged from 28 ng L(-1) to 11,514 ng L(-1). Hydrocarbon typology and statistical evaluation demonstrated contribution of distinct sources in different regions and allowed quantification of these contributions. Total flow rate for the five major rivers amounts to 3 t year(-1) and responds for 30% of the total PAH annual input into the northern area of the Guanabara Bay. For the first time PAH mass deposited in the bay sediments has been estimated and shall serve as base for decision making and source abatement.

  11. 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.

  12. Relação entre as vazões médias mensais do rio Piancó e as anomalias de temperatura da superfície dos oceanos Atlântico e Pacífico tropical Relationhips between monthly mean stream flow for the Pianco river and tropical Atlantic and Pacific sst anomalies

    Directory of Open Access Journals (Sweden)

    Manoel F. Gomes Filho

    2000-01-01

    Full Text Available Apresenta-se, neste trabalho, uma análise estatística baseada em correlações entre as temperaturas globais da superfície do mar (TSM e as descargas do Rio Piancó, no sertão da Paraíba, principal contribuinte do reservatório de Coremas, na região. Os coeficientes globais de correlação foram obtidos entre as temperaturas médias da superfície do mar, para os trimestres de novembro a janeiro e de fevereiro a abril, e as descargas do Rio Piancó no reservatório de Coremas, para cada mês de fevereiro até maio, que compreendem a estação chuvosa na bacia hidrográfica do reservatório. Os resultados mostram correlações significativas entre as TSM das regiões NINO1+2 e NINO3 no Oceano Pacífico. Na área do Atlântico não existe um padrão de correlações bem definido.This paper presents a statistical analysis based on the correlation between the Global Sea Surface Temperatures (SST and the discharge of Piancó river the principal contributor to the Coremas reservoir in the Paraíba State. The global correlation coefficients were obtained between the mean Sea Surface Temperatures (SST for the November to January and February to April trimesters and the volume of water discharged by the Piancó river in the Coremas reservoir for each of the individual months from February to May, the rainy season in the region of the reservoir. The results show the existence of a strong negative correlation between the SST's of the Nino1+2 and Nino3 regions of the Pacific Ocean. For the Atlantic area no well defined pattern of correlation was found.

  13. Update of Columbia River flow and temperature data measured at Priest Rapids Dam and Vernita Bridge

    Energy Technology Data Exchange (ETDEWEB)

    Whelan, G.; Newbill, C.A.

    1983-09-01

    Columbia River temperatures and flow rates are collected daily at Priest Rapids Dam and Vernita Bridge. These data are necessary for assessing trends or changes in river conditions downstream of Priest Rapids Dam. In order to analyze this data, Pacific Northwest Laboratory developed a computerized data base using existing US Geological Survey flow and temperature records at Priest Rapids Dam and Vernita Bridge. Daily-averaged temperature and daily flow information on the Columbia River just downstream of Priest Rapids Dam and upstream of river mile 380 were collected and stored in a data base. A newly developed computer model, COLSTAT (Columbia River Statistical Update), used the data base to statistically analyze temperature and flow conditions by computing the frequency of occurrence and duration of selected temperatures and flow rates for the Columbia River. Information regarding the data base is presented, as well as, a description of the COLSTAT model.

  14. Adaptive management of river flows in Europe: A transferable framework for implementation

    Science.gov (United States)

    Summers, M. F.; Holman, I. P.; Grabowski, R. C.

    2015-12-01

    The evidence base for defining flow regimes to support healthy river ecosystems is weak, as there are few studies which quantify the ecological impact associated with different degrees of hydrological alteration. As a result, river flow standards used to manage water abstraction are largely based on expert judgement. Planned adaptive management studies on multiple rivers under the European Water Framework Directive represent an opportunity to learn about ecological flow requirements and improve the quantitative evidence base. However, identifying clear ecological responses to flow alteration can be a significant challenge, because of the complexity of river systems and the other factors which may confound the response. This paper describes the Adaptive River Management (ARM) framework, a flexible framework for implementing adaptive management of river flows that is transferable to other regions of the world. Application of the framework will ensure that the effectiveness of implemented management actions is appraised and that transferable quantitative data are collected that can be used in other geographical regions.

  15. 信息动态%Study on Flow Characteristics of Jingjiang River

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The Yangtze River Flood Protection Physical Model is employed to comprehensively measure the hydraulic elements for different flow discharges of Jingjiang river. Furthermore, the water sediment and topography data since the impoundment of Three Gorges Reservoir were taken to analyse the general laws and characteristics of flow movement. Based on the above analysis, different river regulation programs are studied and detailed solutions for different river regimes are offered. The study reveals the flow movement rules for Jingjiang River by clearly presenting the inherent laws of hydraulic elements variation including that of the water level, water surface longitudinal slope, breadth to depth ratio of cross section, flow velocity distribution and dynamicaxis of flow, and consequently provides scientific basis for river regulation.

  16. Estimating river low flows statistics in ungauged sites

    Science.gov (United States)

    Rossi, G.; Caporali, E.

    2010-12-01

    Index. The division into subregions is validated using discordancy and heterogeneity tests. Several subdivisions are tested, starting from previous studies on different hydrological extreme values and introducing some hydrological features. For every river section of interest the catchment area is identified and an appropriate set of catchment physiographic and climatic characteristics is defined. A physiographical space-based method is used to relate the duration and annual minimum indices of low flow to the rivers basins characteristics. The new space is built as a power correlation of the catchment geomorphologic and climatic characteristics. In this space several interpolation techniques, either deterministic or geostatistical, such as Inverse Distance, Thiessen polygon methods and Kriging, are applied. The results are valuated using the jack-knife method. Different error measurement (mean square error, mean relative error…) are also assessed to compare the results, to quantify the accuracy of the different techniques and to define the most suitable procedure for low flow regionalization.

  17. 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

    2017-08-30

    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.

  18. Functional no-flow events and their identification in the Lower Yellow River

    Institute of Scientific and Technical Information of China (English)

    NI; Jinren; (倪晋仁); QIAN; Zhenghan; (钱征寒)

    2002-01-01

    Based on the understandings of the relationship between the river runoff and the pri-mary functions of the Yellow River, this paper advances the concept of functional no-flow event that is different from the zero-discharge event occurring in the river. Factors reflecting the charac-teristics of functional no-flow events were analyzed and the criteria describing severity levels of the events were given from the cluster analysis with the measured data from 1950 to 1999. The results show that the severity level is subject to the critical water demand for river ecosystem protection. Using two critical water use demand scenarios for the Yellow River proposed by the authors and the Yellow River Water Conservancy Commission, different severity levels of functional no-flow events are identified. In addition, the differences between the zero-discharge and the functional no-flow events are discussed.

  19. Seepage flow-stability analysis of the riverbank of Saigon river due to river water level fluctuation

    CERN Document Server

    Oya, A; Hiraoka, N; Fujimoto, M; Fukagawa, R

    2015-01-01

    The Saigon River, which flows through the center of Ho Chi Minh City, is of critical importance for the development of the city as forms as the main water supply and drainage channel for the city. In recent years, riverbank erosion and failures have become more frequent along the Saigon River, causing flooding and damage to infrastructures near the river. A field investigation and numerical study has been undertaken by our research group to identify factors affecting the riverbank failure. In this paper, field investigation results obtained from multiple investigation points on the Saigon River are presented, followed by a comprehensive coupled finite element analysis of riverbank stability when subjected to river water level fluctuations. The river water level fluctuation has been identified as one of the main factors affecting the riverbank failure, i.e. removal of the balancing hydraulic forces acting on the riverbank during water drawdown.

  20. Explaining and forecasting interannual variability in the flow of the Nile River

    OpenAIRE

    M. S. Siam; E. A. B. Eltahir

    2014-01-01

    The natural interannual variability in the flow of Nile River had a significant impact on the ancient civilizations and cultures that flourished on the banks of the river. This is evident from stories in the Bible and Koran, and from the numerous Nilometers discovered near ancient temples. Here, we analyze extensive data sets collected during the 20th century and define four modes of natural variability in the flow of Nile River, identifying a new significant ...

  1. Muskingum equation based downstream sediment flow simulation models for a river system

    Institute of Scientific and Technical Information of China (English)

    Briti Sundar Sil; Parthasarathi Choudhury

    2016-01-01

    Applications of sediment transport and water flow characteristics based sediment transport simulation models for a river system are presented in this study. An existing water–sediment model and a new sediment–water model are used to formulate the simulation models representing water and sediment movement in a river system. The sediment–water model parameters account for water flow characteristics embodying sediment transport properties of a section. The models are revised formulations of the multiple water inflows model describing water movement through a river system as given by the Muskingum principle. The models are applied to a river system in Mississippi River basin to estimate downstream sediment concentration, sediment discharge, and water discharge. River system and the river section parameters are estimated using a revised and the original multiple water inflows models by applying the genetic algorithm. The models estimate downstream sediment transport rates on the basis of upstream sediment/water flow rates to a system. Model performance is evaluated by using standard statistical criteria;downstream water discharge resulting from the original multiple water inflows model using the estimated river system parameters indicate that the revised models satisfactorily describe water movement through a river system. Results obtained in the study demonstrate the applicability of the sediment transport and water flow characteristics-based simulation models in predicting downstream sediment transport and water flow rates in a river system.

  2. Braided River Flow and Invasive Vegetation Dynamics in the Southern Alps, New Zealand

    Science.gov (United States)

    Caruso, Brian S.; Edmondson, Laura; Pithie, Callum

    2013-07-01

    In mountain braided rivers, extreme flow variability, floods and high flow pulses are fundamental elements of natural flow regimes and drivers of floodplain processes, understanding of which is essential for management and restoration. This study evaluated flow dynamics and invasive vegetation characteristics and changes in the Ahuriri River, a free-flowing braided, gravel-bed river in the Southern Alps of New Zealand's South Island. Sixty-seven flow metrics based on indicators of hydrologic alteration and environmental flow components (extreme low flows, low flows, high flow pulses, small floods and large floods) were analyzed using a 48-year flow record. Changes in the areal cover of floodplain and invasive vegetation classes and patch characteristics over 20 years (1991-2011) were quantified using five sets of aerial photographs, and the correlation between flow metrics and cover changes were evaluated. The river exhibits considerable hydrologic variability characteristic of mountain braided rivers, with large variation in floods and other flow regime metrics. The flow regime, including flood and high flow pulses, has variable effects on floodplain invasive vegetation, and creates dynamic patch mosaics that demonstrate the concepts of a shifting mosaic steady state and biogeomorphic succession. As much as 25 % of the vegetation cover was removed by the largest flood on record (570 m3/s, ~50-year return period), with preferential removal of lupin and less removal of willow. However, most of the vegetation regenerated and spread relatively quickly after floods. Some flow metrics analyzed were highly correlated with vegetation cover, and key metrics included the peak magnitude of the largest flood, flood frequency, and time since the last flood in the interval between photos. These metrics provided a simple multiple regression model of invasive vegetation cover in the aerial photos evaluated. Our analysis of relationships among flow regimes and invasive vegetation

  3. 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

  4. 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

    2017-03-03

    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.

  5. Flow seasonality and fish assemblage in a tropical river, French Guiana, South America

    Directory of Open Access Journals (Sweden)

    Francisco Leonardo Tejerina-Garro

    Full Text Available The objective of this study is to verify the existence of a seasonal pattern of variation in the fish assemblages of a tropical river using taxonomic and functional descriptors. Fish were sampled using gillnets at two sites on the Comté River, a large-sized river 254.8 km long, flowing entirely through rainforest areas of French Guiana. Samplings were conducted every other month from August 1998 to July 2000. Four types of fish assemblage descriptors were used: the species descriptor (number of individual fish of each species in the sample; the family descriptor (number of individual fish of each family in the sample; the trophic descriptor (distribution of the fish biomass in each feeding guild and the specific maximum observed size - MOS (number of individual fish in each of four classes of MOS: 300 mm. Results point out that changes in the fish assemblage are related to water level oscillations. The role of migration seems to be weak and is limited to trophic displacements characteristic of few species. In the low-water season, characterized by weak water level oscillation, fish species and families belonging to piscivorous or aquatic invertivorous guilds were predominant, whereas in the high-water season the environment is submitted to strong variations caused by fast and large water level oscillations, and the fish assemblage was characterized by species or families with an opportunistic omnivorous diet.

  6. About the high flow regime of the rivers of Kosovo and Metohia

    Directory of Open Access Journals (Sweden)

    Živković Nenad

    2009-01-01

    Full Text Available The examples from Kosovo and Metohia attempted to point to some problems in the domain of hydrogeographic regionalization. The river water regime, especially the phase of high flows which marks this regime, has been the topic of almost all researches which treat water resources of drainage basins. However, the thing that has not been achieved till now is the unique solution by which the classification of rivers would be made according to this feature. On this example it has been shown that even some older methods, based on genetic analysis of hydrograms and of global type, as well as some recent ones, with lot of quantitative entry and regional approaches, cannot with certainty answer all the challenges which river regimes bring with themselves. This work shows that apart from climate, orographic and physiognomic features of drainage basins, the periods of data processing and the analysis of individual intra-annual series of discharges are very important as well. Discretization on time periods shorter than one month, as well as elimination of the extreme values of discharges in the longtime series is recommended for the future research.

  7. 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

  8. GloFAS-Seasonal: Operational Seasonal Ensemble River Flow Forecasts at the Global Scale

    Science.gov (United States)

    Emerton, Rebecca; Zsoter, Ervin; Smith, Paul; Salamon, Peter

    2017-04-01

    Seasonal hydrological forecasting has potential benefits for many sectors, including agriculture, water resources management and humanitarian aid. At present, no global scale seasonal hydrological forecasting system exists operationally; although smaller scale systems have begun to emerge around the globe over the past decade, a system providing consistent global scale seasonal forecasts would be of great benefit in regions where no other forecasting system exists, and to organisations operating at the global scale, such as disaster relief. We present here a new operational global ensemble seasonal hydrological forecast, currently under development at ECMWF as part of the Global Flood Awareness System (GloFAS). The proposed system, which builds upon the current version of GloFAS, takes the long-range forecasts from the ECMWF System4 ensemble seasonal forecast system (which incorporates the HTESSEL land surface scheme) and uses this runoff as input to the Lisflood routing model, producing a seasonal river flow forecast out to 4 months lead time, for the global river network. The seasonal forecasts will be evaluated using the global river discharge reanalysis, and observations where available, to determine the potential value of the forecasts across the globe. The seasonal forecasts will be presented as a new layer in the GloFAS interface, which will provide a global map of river catchments, indicating whether the catchment-averaged discharge forecast is showing abnormally high or low flows during the 4-month lead time. Each catchment will display the corresponding forecast as an ensemble hydrograph of the weekly-averaged discharge forecast out to 4 months, with percentile thresholds shown for comparison with the discharge climatology. The forecast visualisation is based on a combination of the current medium-range GloFAS forecasts and the operational EFAS (European Flood Awareness System) seasonal outlook, and aims to effectively communicate the nature of a seasonal

  9. 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 , geohydrological and geomorphological conditions. This paper tests physiological differences among trees along rivers with varying flow regimes. In this study 3 parameters were selected and tested, namely wood density, specific leaf area and water use efficiency...

  10. River flow prediction using hybrid models of support vector regression with the wavelet transform, singular spectrum analysis and chaotic approach

    Science.gov (United States)

    Baydaroğlu, Özlem; Koçak, Kasım; Duran, Kemal

    2017-03-01

    Prediction of water amount that will enter the reservoirs in the following month is of vital importance especially for semi-arid countries like Turkey. Climate projections emphasize that water scarcity will be one of the serious problems in the future. This study presents a methodology for predicting river flow for the subsequent month based on the time series of observed monthly river flow with hybrid models of support vector regression (SVR). Monthly river flow over the period 1940-2012 observed for the Kızılırmak River in Turkey has been used for training the method, which then has been applied for predictions over a period of 3 years. SVR is a specific implementation of support vector machines (SVMs), which transforms the observed input data time series into a high-dimensional feature space (input matrix) by way of a kernel function and performs a linear regression in this space. SVR requires a special input matrix. The input matrix was produced by wavelet transforms (WT), singular spectrum analysis (SSA), and a chaotic approach (CA) applied to the input time series. WT convolutes the original time series into a series of wavelets, and SSA decomposes the time series into a trend, an oscillatory and a noise component by singular value decomposition. CA uses a phase space formed by trajectories, which represent the dynamics producing the time series. These three methods for producing the input matrix for the SVR proved successful, while the SVR-WT combination resulted in the highest coefficient of determination and the lowest mean absolute error.

  11. Estimates of monthly streamflow characteristics at selected sites in the upper Missouri River basin, Montana, base period water years 1937-86

    Science.gov (United States)

    Parrett, Charles; Johnson, D.R.; Hull, J.A.

    1989-01-01

    Estimates of streamflow characteristics (monthly mean flow that is exceeded 90, 80, 50, and 20 percent of the time for all years of record and mean monthly flow) were made and are presented in tabular form for 312 sites in the Missouri River basin in Montana. Short-term gaged records were extended to the base period of water years 1937-86, and were used to estimate monthly streamflow characteristics at 100 sites. Data from 47 gaged sites were used in regression analysis relating the streamflow characteristics to basin characteristics and to active-channel width. The basin-characteristics equations, with standard errors of 35% to 97%, were used to estimate streamflow characteristics at 179 ungaged sites. The channel-width equations, with standard errors of 36% to 103%, were used to estimate characteristics at 138 ungaged sites. Streamflow measurements were correlated with concurrent streamflows at nearby gaged sites to estimate streamflow characteristics at 139 ungaged sites. In a test using 20 pairs of gages, the standard errors ranged from 31% to 111%. At 139 ungaged sites, the estimates from two or more of the methods were weighted and combined in accordance with the variance of individual methods. When estimates from three methods were combined the standard errors ranged from 24% to 63 %. A drainage-area-ratio adjustment method was used to estimate monthly streamflow characteristics at seven ungaged sites. The reliability of the drainage-area-ratio adjustment method was estimated to be about equal to that of the basin-characteristics method. The estimate were checked for reliability. Estimates of monthly streamflow characteristics from gaged records were considered to be most reliable, and estimates at sites with actual flow record from 1937-86 were considered to be completely reliable (zero error). Weighted-average estimates were considered to be the most reliable estimates made at ungaged sites. (USGS)

  12. 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.

  13. Quantitative Analysis of Groundwater Flow near a Partially Penetrating River under Riverside Pumping

    Institute of Scientific and Technical Information of China (English)

    WANG Bingchen; ZHENG Xilai; QIAN Hui; LIN Guoqing; XU Qiant

    2004-01-01

    According to practical geological and hydrogeological conditions of riverside water-supply well fields in northwestern China, an ideal hydrogeological model has been generalized and a three-dimensional mathematical model has been set up. A finite difference method was applied to simulating groundwater flow near a partially penetrating river under riverside pumping, and to analyzing the effects of river width, partial penetration and permeability of riverbed sediments on groundwater recharges. Results show that riverside pumping may cause groundwater to flow beneath the partially penetrating river, and that river width, penetration and riverbed permeability obviously influence flows from the partially penetrating river and constant-head boundaries. However, the pumping output is mainly from the partially penetrating river.

  14. Multi-compartment approach to identify minimal flow and maximal recreational use of a lowland river

    Science.gov (United States)

    Pusch, Martin; Lorenz, Stefan

    2013-04-01

    Most approaches to establish a minimum flow rate for river sections subjected to water abstraction focus on flow requirements of fish and benthic invertebrates. However, artificial reduction of river flow will always affect additional key ecosystem features, as sediment properties and the metabolism of matter in these ecosystems as well, and may even influence adjacent floodplains. Thus, significant effects e.g. on the dissolved oxygen content of river water, on habitat conditions in the benthic zone, and on water levels in the floodplain are to be expected. Thus, we chose a multiple compartment method to identify minimum flow requirements in a lowland River in northern Germany (Spree River), selecting the minimal required flow level out of all compartments studied. Results showed that minimal flow levels necessary to keep key ecosystem features at a 'good' state depended significantly on actual water quality and on river channel morphology. Thereby, water quality of the Spree is potentially influenced by recreational boating activity, which causes mussels to stop filter-feeding, and thus impedes self-purification. Disturbance of mussel feeding was shown to directly depend on boat type and speed, with substantial differences among mussel species. Thus, a maximal recreational boating intensity could be derived that does not significantly affect self purification. We conclude that minimal flow levels should be identified not only based on flow preferences of target species, but also considering channel morphology, ecological functions, and the intensity of other human uses of the river section.

  15. Monthly Activity Report, Fiscal Year 2004: Presquile and James River National Wildlife Refuges

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This annual narrative report for Presquile and James River National Wildlife Refuges outlines Refuge accomplishments during the 2004 fiscal year. Land acquisition is...

  16. 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

  17. Tidal impacts on the subtidal flow division at the main bifurcation in the Yangtze River Delta

    Science.gov (United States)

    Zhang, Wei; Feng, Haochuan; Hoitink, A. J. F.; Zhu, Yuliang; Gong, Fei; Zheng, Jinhai

    2017-09-01

    Flow division at bifurcations in the Yangtze Estuary has received ample attention, since it may control the pathways of terrestrial sediments over downstream river branches including the 12.5 m Deepwater Navigation channel. While some efforts have been made to interpret flow division at the bifurcations of the Yangtze Estuary, little attention has been paid to the role of tides. Flow division at estuarine bifurcations is made complicated by tides that propagate from the outlet of the tidal channels into the delta. To quantify the tidal influence on the distribution of river discharge, and more generally, to understand the mechanisms governing the subtidal flow division at the tidally affected bifurcation in the Yangtze River Delta, a two-dimensional hydrodynamic model is employed. In this model, the landward boundary is chosen beyond the tidal limit, where the tidal motion has faded out entirely. The seaward boundary is chosen such that the river discharge does not influence the water level. Subtidal discharges are decomposed using the method of factor separation, to distinguish between the effects of tides, river discharge and river-tide interactions on the subtidal flow division. Results indicate that tides modify the river discharge distribution over distributary channels in the Yangtze River Delta, particularly in the dry season. A significant difference in the subtidal flow division during spring tide and neap tide shows that the tidally averaged flow division over the distributaries in the delta greatly depends on tidal amplitude. By varying the river discharge at the landward boundary and amplitudes and phases of the principal tidal constituents at the seaward boundary of the established model, the sensitivities of the subtidal flow division to the river discharge and tidal amplitude variation were investigated in detail. Generally, the tidal impacts on the subtidal flow division are around 12% to 22%, with river discharge varying from 30,000 m3s-1 to 20

  18. Research on monthly flow uncertain reasoning model based on cloud theory

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    In view of the mid and long term runoff forecasting containing many uncertain factors,this paper constructs a uncertain reasoning model (UR) based on the cloud theory to solve the problem of uncertain reasoning.Firstly,in the proposed model,a classification method,i.e.,attribute oriented induction maximum variance (MaxVar),is used to divide the runoff series into different intervals,which are softened and described by the cloud membership with expected value (Ex),entropy (En) and hyper-entropy (He),then an uncertain reasoning rule set is constructed by means of the runoff value generalization and applied to monthly flow for uncertain prediction.Next,a new modification formula is used to calculate He in runoff forecasting,and a confident level probability prediction interval is obtained by statistical method.Finally,this paper takes the monthly flow of Manwan station in China as an example and uses UR model,LSSVM model,and ARMA model to calculate the monthly flow,respectively.The results show that the UR model has the highest prediction accuracy compared to other models,and that it not only provides random output but also supports probability interval prediction.

  19. Generic 2-D River Network Modeling of Flow and Sediment Transports

    Science.gov (United States)

    Guo, W.; Wang, C.; Xiang, X.; Ma, T.

    2012-04-01

    A generic 2D river network model of flow and sediment transports is proposed for the flow and sediment simulation in the complex river network. The paper expands the three-step method adopted in the 1D river network to the 2D river network simulation. A 2D river network model is divided into several cells, including single river cell, "tree-like" river cell, "ring-like" river cell and "cross-like" river cell, which can reflect the interactive influence of flow field in the bifurcated channel and applies to generic 2D simulation. Based on equation of the 2D shallow water and unsteady non-uniform suspended sediment, the relationship between the variables (water level, discharge and sediment concentration) of each section and those of the boundaries are obtained through the full implicit matrix chase-after method. Through the conservation of water and sediment on the boundaries, the water level and sediment concentration on the nodes can be got by solving the irregular sparse matrix of conservation equation, so as to implement the coupled simulation of flow and sediment in the whole river network. The paper take the Chengtong River Reach located in the low reaches of Yangtze River as the example of "cross-like" river to verify the algorithm. The model is calibrated using the measured data. A comparison of calculated water level, discharge and sediment concentration shows that the generic model can reflex the interactive influence of flow field, with reasonable accuracy, especially in the bifurcated channel.

  20. Influence of deposition of fine plant debris in river floodplain shrubs on flood flow conditions - The Warta River case study

    Science.gov (United States)

    Mazur, Robert; Kałuża, Tomasz; Chmist, Joanna; Walczak, Natalia; Laks, Ireneusz; Strzeliński, Paweł

    2016-08-01

    This paper presents problems caused by organic material transported by flowing water. This material is usually referred to as plant debris or organic debris. Its composition depends on the characteristic of the watercourse. For lowland rivers, the share of the so-called small organic matter in plant debris is considerable. This includes both various parts of water plants and floodplain vegetation (leaves, stems, blades of grass, twigs, etc.). During floods, larger woody debris poses a significant risk to bridges or other water engineering structures. It may cause river jams and may lead to damming of the flowing water. This, in turn, affects flood safety and increases flood risk in river valleys, both directly and indirectly. The importance of fine plant debris for the phenomenon being studied comes down to the hydrodynamic aspect (plant elements carried by water end up on trees and shrubs, increase hydraulic flow resistance and contribute to the nature of flow through vegetated areas changed from micro-to macro-structural). The key part of the research problem under analysis was to determine qualitative and quantitative debris parameters and to establish the relationship between the type of debris and the type of land use of river valleys (crop fields, meadows and forested river sections). Another problem was to identify parameters of plant debris for various flow conditions (e.g. for low, medium and flood flows). The research also included an analysis of the materials deposited on the structure of shrubs under flood flow conditions during the 2010 flood on the Warta River.

  1. [Application of wavelet transform to monthly runoff time serial analysis in Zagunao watershed, the upper Minjiang river].

    Science.gov (United States)

    Lin, Yong; Liu, Shirong; Li, Chongwei; Ge, Jianqing; Suo, Anning; Chen, Baoyu

    2005-09-01

    Runoff is an important component of regional water resources, and its dynamics is to some extent an indicator of water resources dynamics in a region. To know the runoff dynamics and water resources in a region is essential for the sustainable utilization and planning of water resources, and for the research on hydrological response of vegetation change at watershed scale. To disclose the water resources dynamics in Upper Minjiang River, one of the large reaches of Yangze River in southwest China, this paper analyzed the runoff dynamic features of Zagunao watershed, an important watershed in Minjiang River basin. Multi-Resolution Analysis (MRA) and periodicity analysis were conducted with Dmey wavelet function on the monthly runoff data from 1962 to 2002 observed by Zagunao hydrological station, which provided a data-based approximation on the evolution of monthly runoff in Zagunao watershed. It was found that the runoff dynamics in Zagunao watershed was relatively stable during 1962 - 1978, despite that this period was just in correspondence with the term of intensive deforestation activities in Upper Minjiang River basin. It was also clear that the runoff in Zagunao watershed was increased from 1986 to 1997, which was inconsistent with the commonly accepted viewpoint that the runoff decreased with increasing vegetation cover in forest watershed. However, the increasing trend from 1986 - 1997 was consistent with the research results in Yichang by Wang Wensheng and with the global warming at global and continent scale, which meant that global climate change plays a big role in runoff dynamics in Upper Minjiang River. Periodicity analysis showed that the rich-short water periodicity at the scale of 10 years (120 months) and 5 years (60 months) was 3 and 7 times, respectively, which could provide invaluable information for the eco-hydrological function research of forest landscape in Minjiang river basin and the sustainable utilization of water resources. The results

  2. Historical Maps Potential on the Assessment of the Hydromorphological Changes in Large Rivers: Towards Sustainable Rivers Management under Altered Flows

    Science.gov (United States)

    Kuriqi, Alban; Rosário Fernandes, M.; Santos, Artur; Ferreira, M. Teresa

    2017-04-01

    Hydromorphological patterns changes in large rivers, result from a long history of human interventions. In this study, we evaluate the causes and effects of hydromorphological alterations in the Iberian Minho River using a planform change analysis. We performed a temporal comparison using historical maps (nineteen century) and contemporaneous maps. The studied river was divided in 2.5 km long river stretches in a total of 25 sampling units. The historical maps were initially georeferenced for the WGS84 coordinate system. We used Geographic Information System (GIS) to extract the hydromorphological features and to store and organised the spatial data. The hydromorphological features (sinuosity index, braiding intensity, river corridor and active channel width, lotic and lentic habitats) were mapped by visual interpretation of the historical and the contemporaneous maps on a scale 1:2500 by applying the same methodology. Also, we analysed certain Indicators of Hydrological Alteration (IHA) based on pre- and post-dam daily streamflow data obtained from the Spanish Water Information System (SIA). The results revealed a significant reduction in the active channel width and all sinuosity indexes representing an overall degradation of river conditions. We also noticed a drastic diminution in the number and total area of lentic habitats causing fish habitat shifts. Changes were less evident in upstream sampling units due to diverse Land Use/Land Cover (LULC) changes combine with some geological constraints. These responses were consistent with reductions in mean annual discharge, flood disturbance decrease and minimum flow increase during the summer season. This work allows to understand the evolutionary trajectory of large fluvial system over more than 100 years and to implement concrete measures for sustainable river management. Keywords: historical maps, large rivers, flow alteration, sinuosity index, lotic and lentic habitats, regulated rivers, river restoration.

  3. Improving peak flow estimates in artificial neural network river flow models

    Science.gov (United States)

    Sudheer, K. P.; Nayak, P. C.; Ramasastri, K. S.

    2003-02-01

    In this paper, the concern of accuracy in peak estimation by the artificial neural network (ANN) river flow models is discussed and a suitable statistical procedure to get better estimates from these models is presented. The possible cause for underestimation of peak flow values has been attributed to the local variations in the function being mapped due to varying skewness in the data series, and theoretical considerations of the network functioning confirm this. It is envisaged that an appropriate data transformation will reduce the local variations in the function being mapped, and thus any ANN model built on the transformed series should perform better. This heuristic is illustrated and confirmed by many case studies and the results suggest that the model performance is significantly improved by data transformation. The model built on transformed data outperforms the model built on raw data in terms of various statistical performance indices. The peak estimates are improved significantly by data transformation.

  4. 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

  5. Geophysical controls of aquifer-river exchange flow patterns in a UK lowland meandering river.

    Science.gov (United States)

    Dara, Rebwar; Krause, Stefan; Rivett, Michael

    2016-04-01

    were characterized by low amplitude non-continuous distortion and attenuation of GPR reflections. Highly conductive gravel and sand drift deposits were indicated by strong, subhorizontal, undulating and localized sets of dipping reflections in the GPR survey. Vertical hydraulic gradients (VHG) distinguished at streambed piezometers showed positive values throughout the observation period, indicating groundwater upwelling into the river. Hotspots of increased VHG were observed in piezometers installed in permeable sections where strong groundwater upwelling was predominant and in impermeable sections where the screen section located below low conductivity layers. Push-pull dilution tracer experiments within and around low conductivity peat and clay lenses revealed that these layers substantially inhibit groundwater upwelling, resulting in enhanced streambed residence and reaction times and significant reduction in nitrogen and dissolved oxygen concentrations. The increase in residence time and the related depletion in the volume of dissolved oxygen facilitated the development of conditions necessary for nitrate reduction. In contrast, preferential flow paths and short residence times in highly conductive drift deposits resulted in no significant changes in nitrate concentrations along hyporheic flow paths. The revealed impact of strongly heterogeneous physical streambed properties on hotspots of enhanced residence time and biogeochemical turnover highlights the value of GPR-based of high-resolution streambed monitoring.

  6. Analysis of flow process variation degree and influencing factors in inner Mongolia reach of the Yellow River

    Science.gov (United States)

    Jin, S. Y.; Zhang, P.; Zhao, W. R.

    2017-06-01

    The provincial hydrological sections of Shizuishan and Toudaoguai are selected as the object of study to analyze flow process variation degree and influencing factor in Inner Mongolia reach of the Yellow River, according to observe and natural monthly runoff from 1956 to 2013. The result shows that there are three phases of the flow process variation degree of the two sections, namely the year 1956 to 1968, 1969 to 1986 and 1987 to 2013, and which increase by phases. The markings appear to decrease by phases and the marking in Toudaoguai section is lower than that in Shizuishan section. The key reasons of the above features are water consumption of industry and agriculture along the river and reservoir operation of Longyangxia and Liujiaxia.

  7. Flow and Transport in the Hanford 300 Area Vadose Zone-Aquifer-River System

    Energy Technology Data Exchange (ETDEWEB)

    Waichler, Scott R.; Yabusaki, Steven B.

    2005-07-13

    Contaminant migration in the 300 Area unconfined aquifer is strongly coupled to fluctuations in the Columbia River stage. To better understand the interaction between the river, aquifer, and vadose zone, a 2-D saturated-unsaturated flow and transport model was developed for a vertical cross-section aligned west-east across the Hanford Site 300 Area, nearly perpendicular to the river. The model was used to investigate water flow and tracer transport in the vadose zone-aquifer-river flow system, in support of the ongoing study of the 300 Area uranium plume. The STOMP simulator was used to model 1-year from 3/1/92 to 2/28/93, a period when hourly data were available for both groundwater and river levels. Net water flow to the river (per 1-meter width of shoreline) was 182 m3/y in the base case, but the cumulative exchange or total flow back and forth across the riverbed was 30 times greater. The low river case had approximately double the net water and Groundwater tracer flux into the river as compared to the base case.

  8. Groundwater flow model for the Little Plover River basin in Wisconsin’s Central Sands

    Science.gov (United States)

    Ken Bradbury,; Fienen, Michael N.; Kniffin, Maribeth; Jacob Krause,; Westenbroek, Stephen M.; Leaf, Andrew T.; Barlow, Paul M.

    2017-01-01

    explicitly includes all high-capacity wells in the model domain and simulates seasonal variations in recharge and well pumping. The model represents the Little Plover River, and other significant streams and drainage ditches in the model domain, as fully connected to the groundwater system, computes stream base flow resulting from groundwater discharge, and routes the flow along the stream channel. A separate soil-water-balance (SWB) model was used to develop groundwater recharge arrays as input for the groundwater flow model. The SWB model uses topography, soils, land use, and climatic data to estimate recharge as deep drainage from the soil zone. The SWB model explicitly includes recharge originating as irrigation water, and computes irrigation using techniques similar to those used by local irrigation operators. The groundwater flow model uses the U.S. Geological Survey’s MODFLOW modeling code which is freely available, widely accepted, and commonly used by the groundwater community. The groundwater flow model and the SWB model use identical high-resolution numerical grids having model cells 100 feet on a side, with physical properties assigned to each grid cell. This grid allows accurate geographic placement of wells, streams, and other model features. The 3-dimensional grid has three layers; layers 1 and 2 represent the sand and gravel aquifer and layer 3 represents the underlying sandstone. The distribution of material properties in the model (hydraulic conductivity, aquifer thickness, etc.) comes from previous published geologic studies of the region, updated by calibration to recent streamflow and groundwater level data. The SWB model operates on a daily time step. The groundwater flow model was calibrated to monthly stress periods with time steps ranging from 1 to 16 days. More detailed time discretization is possible. The groundwater model was calibrated to water-level and streamflow data collected during 2013 and 2014 by adjusting model parameters (primarily

  9. 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.

  10. 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.

  11. Debris flow occurrence and sediment persistence, Upper Colorado River Valley, CO

    Science.gov (United States)

    Grimsley, Kyle J; Rathburn, Sara L.; Friedman, Jonathan M.; Mangano, Joseph F.

    2016-01-01

    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.

  12. Assessing Geomorphic and Vegetative Responses to Environmental Flows in the Willamette River Basin

    Science.gov (United States)

    Mangano, J.; Jones, K.; Wallick, R.; Bach, L.; Olson, M.; Bervid, H.

    2015-12-01

    On regulated rivers, restoring flow regimes is a process-based restoration approach that may strongly affect downstream ecosystems. Developing realistic flow targets with meaningful geomorphic and ecological benefits, however, is challenging. For instance, hydraulic, geomorphic and biological processes are affected by more than manipulating water release—sediment supply and transport conditions also require consideration. Also, funding and programmatic directives rarely require the monitoring necessary to adaptively manage environmental flow programs. Recent research in the Willamette River basin in support of the Sustainable Rivers Project (SRP) demonstrates how such a monitoring program can be implemented. At the reach scale, initial efforts have assessed geomorphic and vegetative changes in alluvial sections of the Middle Fork Willamette and McKenzie Rivers using repeat mapping from aerial photographs and flow analyses. Overall, both rivers are largely stable because of reduced discharge, bed-material supply and local revetments, but some reaches of the McKenzie River are more dynamic, perhaps reflecting greater inputs of sediment from unregulated tributaries and higher magnitude peak flows. Repeat, reach-scale mapping on the Middle Fork Willamette River shows that frequent bankfull flows are able to scour minimally vegetated gravel bars and sustain a patchwork of actively shifting bed-material sediment. Repeat mapping on the McKenzie River in summer 2015 will reveal insights about the geomorphic effectiveness of bankfull flows. At the site scale, monitoring at two bars in summer 2015 is linking streamflow with the establishment of black cottonwood. Lastly, a review of hydrographs from 2000-2015 and retrospectively applying stakeholder-defined flow targets showed substantial variability in meeting objectives for the timing and types of flows under traditional regulated conditions and the SRP. Altogether, these related efforts help link streamflow, geomorphic

  13. A water framework directive (WFD) compliant determination of eologically acceptable flows in alpine rivers - a river type specific approach

    Science.gov (United States)

    Jäger, Paul; Zitek, Andreas

    2010-05-01

    Currently the EU-Water Framework Directive (WFD) represents the driving force behind the assessment for rehabilitation and conservation of aquatic resources throughout Europe. Hydropower production, often considered as "green energy", in the past has put significant pressures on river systems like fragmentation by weirs, impoundment, hydropeaking and water abstraction. Due to the limited availability of data for determining ecologically acceptable flow for rivers at water abstraction sites, a special monitoring program was conducted in the federal state of Salzburg in Austria from 2006 to 2009. Water abstraction sites at 19 hydropower plants, mostly within the trout region of the River Salzach catchment, were assessed in detail with regard to the effect of water abstraction on fish and macrozoobenthos. Based on a detailed assessment of the specific local hydro-morphological and biological situations, the validity of natural low flow criteria (Absolute Minimum Flow - AMF, the lowest daily average flow ever measured and Mean Annual Daily Low Flow - MADLF) as starting points for the determination of an ecologically acceptable flow was tested. It was assessed, if a good ecological status in accordance with the EU-WFD can be maintained at natural AMF. Additionally it was tested, if important habitat parameters describing connectivity, river type specific flow variability and river type specific habitats are maintained at this discharge. Habitat modelling was applied in some situations. Hydraulic results showed that at AMF the highest flow velocity classes were lost in most situations. When AMF was significantly undercut, flow velocities between 0,0 - 0,4 m/s became dominant, describing the loss of the river type specific flow character, leading to a loss of river type specific flow variability and habitats and increased sedimentation of fines. Furthermore limits for parameters describing connectivity for fish like maximum depth at the pessimum profile and minimum flow

  14. 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.

  15. Suspended sediment dynamics in a tidal channel network under peak river flow

    Science.gov (United States)

    Achete, Fernanda Minikowski; van der Wegen, Mick; Roelvink, Dano; Jaffe, Bruce

    2016-05-01

    Peak river flows transport fine sediment, nutrients, and contaminants that may deposit in the estuary. This study explores the importance of peak river flows on sediment dynamics with special emphasis on channel network configurations. The Sacramento-San Joaquin Delta, which is connected to San Francisco Bay (California, USA), motivates this study and is used as a validation case. Besides data analysis of observations, we applied a calibrated process-based model (D-Flow FM) to explore and analyze high-resolution (˜100 m, ˜1 h) dynamics. Peak river flows supply the vast majority of sediment into the system. Data analysis of six peak flows (between 2012 and 2014) shows that on average, 40 % of the input sediment in the system is trapped and that trapping efficiency depends on timing and magnitude of river flows. The model has 90 % accuracy reproducing these trapping efficiencies. Modeled deposition patterns develop as the result of peak river flows after which, during low river flow conditions, tidal currents are not able to significantly redistribute deposited sediment. Deposition is quite local and mainly takes place at a deep junction. Tidal movement is important for sediment resuspension, but river induced, tide residual currents are responsible for redistributing the sediment towards the river banks and to the bay. We applied the same forcing for four different channel configurations ranging from a full delta network to a schematization of the main river. A higher degree of network schematization leads to higher peak-sediment export downstream to the bay. However, the area of sedimentation is similar for all the configurations because it is mostly driven by geometry and bathymetry.

  16. 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.

  17. Mapping the Historical Probability of Increased Flood Hazard During ENSO Events Using a New 20th Century River Flow Reanalysis

    Science.gov (United States)

    Emerton, R.; Cloke, H. L.; Stephens, L.; Woolnough, S. J.; Zsoter, E.; Pappenberger, F.

    2016-12-01

    El Niño Southern Oscillation (ENSO), a mode of variability which sees fluctuations between anomalously high or low sea surface temperatures in the Pacific, is known to influence river flow and flooding at the global scale. The anticipation and forecasting of floods is crucial for flood preparedness, and this link, alongside the predictive skill of ENSO up to seasons ahead, may provide an early indication of upcoming severe flood events. Information is readily available indicating the likely impacts of El Niño and La Niña on precipitation across the globe, which is often used as a proxy for flood hazard. However, the nonlinearity between precipitation and flood magnitude and frequency means that it is important to assess the impact of ENSO events not only on precipitation, but also on river flow and flooding. Historical probabilities provide key information regarding the likely impacts of ENSO events. We estimate, for the first time, the historical probability of increased flood hazard during El Niño and La Niña through a global hydrological analysis, using a new 20thCentury ensemble river flow reanalysis for the global river network. This dataset was produced by running the ECMWF ERA-20CM atmospheric reanalysis through a research set-up of the Global Flood Awareness System (GloFAS) using the CaMa-Flood hydrodynamic model, to produce a 110-year global reanalysis of river flow. We further evaluate the added benefit of the hydrological analysis over the use of precipitation as a proxy for flood hazard. For example, providing information regarding regions that are likely to experience a lagged influence on river flow compared to the influence on precipitation. Our results map, at the global scale, the probability of abnormally high river flow during any given month during an El Niño or La Niña; information such as this is key for organisations that work at the global scale, such as humanitarian aid organisations, providing a seasons-ahead indicator of potential

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

    Energy Technology Data Exchange (ETDEWEB)

    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

  19. The Monitoring of River Flows and the Management of Flood Hazards using UAVs

    Science.gov (United States)

    Verosub, K. L.

    2015-12-01

    The increasing occurrence of extreme precipitation events as well as severe droughts, coupled with greater and greater human occupation of flood plains, makes increased monitoring of flows in rivers an important component of assessing the potential for water-related natural disasters as well as responding to them when they do occur. Unfortunately, this increasing need comes at a time when funding for monitoring activities is generally decreasing. In the United States, for example, gauging stations with daily flow records going back several decades or even a hundred years have been abandoned, and new stations in critical areas have not even been established. A methodology based on periodic UAV-based imaging of an entire river offers the prospect of obtaining inexpensive, real-time, high-resolution data for the determination of the river flows. The method makes use of fact that as the flow in a river rises or falls, the areal extent covered by the river changes accordingly. Furthermore, barring anthropogenic changes, the area inundated by a flow of a particular magnitude is invariant in time. For a given stretch of a river, a sequence of images spanning the full range of flow conditions provides the basic template for determining river flows. The actual flow in the river can be calibrated using previously measured flow data corresponding the dates of old aerial or satellite imagery, or calculated from new imagery by using standard flow equations and the topography of the banks of the river, determined by field surveying or Lidar. Once the basic template has been established, determination of "the state-of-the-river" at any point in time can be obtained by comparing newly-acquired UAV images with those in the database. And because a given image encompasses many topographic features that are inundated to differing extents, the resolution of the flow determination is limited only by the completeness of the imagery in the basic template. Repeat flights at weekly

  20. Savannah River Plant, Works Technical Department monthly progress report for March 1956

    Energy Technology Data Exchange (ETDEWEB)

    None

    1956-04-18

    This document details activities of the Works Technical Department during the month of March 1956. It covers reactor technology, separations technology, engineering assistance and heavy water technology.

  1. Decadal variability in core surface flows deduced from geomagnetic observatory monthly means

    DEFF Research Database (Denmark)

    Whaler, K. A.; Olsen, Nils; Finlay, Chris

    2016-01-01

    itself changes slowly, its time derivative can be locally (temporally and spatially) large, in particular when and where core surface secular acceleration peaks. Spherical harmonic expansion coefficients of the flows are not well resolved, and many of them are strongly correlated. Averaging functions......Monthly means of the magnetic field measurements at ground observatories are a key data source for studying temporal changes of the core magnetic field. However, when they are calculated in the usual way, contributions of external (magnetospheric and ionospheric) origin may remain, which make them...

  2. 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,

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

    NARCIS (Netherlands)

    Demirel, Mehmet 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

  4. Habitat availability vs. flow rate for the Pecos River, Part 1 : Depth and velocity availability.

    Energy Technology Data Exchange (ETDEWEB)

    James, Scott Carlton; Schaub, Edward F.; Jepsen, Richard Alan; Roberts, Jesse Daniel

    2004-02-01

    The waters of the Pecos River in New Mexico must be delivered to three primary users: (1) The Pecos River Compact: each year a percentage of water from natural river flow must be delivered to Texas; (2) Agriculture: Carlsbad Irrigation District has a storage and diversion right and Fort Sumner Irrigation District has a direct flow diversion right; and, (3) Endangered Species Act: an as yet unspecified amount of water is to support Pecos Bluntnose Shiner Minnow habitat within and along the Pecos River. Currently, the United States Department of Interior Bureau of Reclamation, the New Mexico Interstate Stream Commission, and the United States Department of the Interior Fish and Wildlife Service are studying the Pecos Bluntnose Shiner Minnow habitat preference. Preliminary work by Fish and Wildlife personnel in the critical habitat suggest that water depth and water velocity are key parameters defining minnow habitat preference. However, river flows that provide adequate preferred habitat to support this species have yet to be determined. Because there is a limited amount of water in the Pecos River and its reservoirs, it is critical to allocate water efficiently such that habitat is maintained, while honoring commitments to agriculture and to the Pecos River Compact. This study identifies the relationship between Pecos River flow rates in cubic feet per second (cfs) and water depth and water velocity.

  5. Low-flow frequency and flow duration of selected South Carolina streams in the Broad River basin through March 2008

    Science.gov (United States)

    Guimaraes, Wladmir B.; Feaster, Toby D.

    2010-01-01

    In 2008, the U.S. Geological Survey, in cooperation with the South Carolina Department of Health and Environmental Control, initiated a study to update low-flow statistics at continuous-record streamgaging stations operated by the U.S. Geological Survey in South Carolina. This report presents the low-flow statistics for 23 selected streamgaging stations in the Broad River basin in South Carolina, and includes flow durations of 5-, 10-, 25-, 50-, 75-, 90-, and 95-percent probability of exceedance and the annual minimum 1-, 3-, 7-, 14-, 30-, 60-, and 90-day mean flows with recurrence intervals of 2, 5, 10, 20, 30, and 50 years, depending on the length of record available at the streamgaging station. The low-flow statistics were computed from records available through March 31, 2008. In addition, flow duration information is presented for one streamgaging station 021556525, Pacolet River below Lake Blalock near Cowpens, SC, where recurrence interval computations were not appropriate.

  6. 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.

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

    African Journals Online (AJOL)

    2008-07-23

    Jul 23, 2008 ... may be accomplished using a remotely sensed spectral vegetation index. .... Daily river flow data were obtained from the DWAF using their on-line ..... streamflow of clearing invasive pine and wattle trees from a riparian zone.

  8. 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

  9. Effects of stream flow intermittency on riparian vegetation of a semiarid region river (San Pedro River, Arizona)

    Science.gov (United States)

    Stromberg, J.C.; Bagstad, K.J.; Leenhouts, J.M.; Lite, S.J.; Makings, E.

    2005-01-01

    The San Pedro River in the southwestern United States retains a natural flood regime and has several reaches with perennial stream flow and shallow ground water. However, much of the river flows intermittently. Urbanization-linked declines in regional ground-water levels have raised concerns over the future status of the riverine ecosystem in some parts of the river, while restoration-linked decreases in agricultural ground-water pumping are expected to increase stream flows in other parts. This study describes the response of the streamside herbaceous vegetation to changes in stream flow permanence. During the early summer dry season, streamside herbaceous cover and species richness declined continuously across spatial gradients of flow permanence, and composition shifted from hydric to mesic species at sites with more intermittent flow. Hydrologic threshold values were evident for one plant functional group: Schoenoplectus acutus, Juncus torreyi, and other hydric riparian plants declined sharply in cover with loss of perennial stream flow. In contrast, cover of mesic riparian perennials (including Cynodon dactylon, an introduced species) increased at sites with intermittent flow. Patterns of hydric and mesic riparian annuals varied by season: in the early summer dry season their cover declined continuously as flow became more intermittent, while in the late summer wet season their cover increased as the flow became more intermittent. Periodic drought at the intermittent sites may increase opportunities for establishment of these annuals during the monsoonal flood season. During the late summer flood season, stream flow was present at most sites, and fewer vegetation traits were correlated with flow permanence; cover and richness were correlated with other environmental factors including site elevation and substrate nitrate level and particle size. Although perennial-flow and intermittent-flow sites support different streamside plant communities, all of the plant

  10. The relationship betwwen ENSO cycle and high and low—flow in the upper Yellow River

    Institute of Scientific and Technical Information of China (English)

    LANYongchao; DINGYongjiang; KANGErsi; MAQuanjie; ZHANGJishi

    2003-01-01

    Firstly,the hydrological and meteorological features of the upper reaches of the Yellow River above Tangnag are analyzed based on observation data,and effects of El Nino and La Nina events on the high and low flow in the upper Yellow River are discussed.The results show El Nino and La Nina events possess consanguineous relationship with runoff in the upper Yellow River.As a whole,the probability of low flow occurrence in the upper Yellow River is relatively great along with the occurrence of El Nino event.Moreover,the flood in the upper Yellow River occurs frequently with the occurrence of La Nina event.Besides,the results also show dissimilarity of El Nino event occurring time exerts greater impact on high flow and low flow in the upper Yellow River,that is,the probability of drought will be greater in the same year if El Nino event occurs in spring,the high-flow may happen in this year if El Nino occurs in summer or autumn;the longer the continuous period of El Nino is,the lower the runoff in the upper Yellow River is.

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

    Directory of Open Access Journals (Sweden)

    C. Mathison

    2015-06-01

    Full Text Available South Asia is a region with a large and rising population and a high dependance on industries sensitive to water resource such as agriculture. The climate is hugely variable with the region relying on both the Asian Summer Monsoon (ASM and glaciers for its supply of fresh water. In recent years, changes in the ASM, fears over the rapid retreat of glaciers and the increasing demand for water resources for domestic and industrial use, have caused concern over the reliability of water resources both in the present day and future for this region. The climate of South Asia means it is one of the most irrigated agricultural regions in the world, therefore pressures on water resource affecting the availability of water for irrigation could adversely affect crop yields and therefore food production. In this paper we present the first 25 km resolution regional climate projections of river flow for the South Asia region. ERA-Interim, together with two global climate models (GCMs, which represent the present day processes, particularly the monsoon, reasonably well are downscaled using a regional climate model (RCM for the periods; 1990–2006 for ERA-Interim and 1960–2100 for the two GCMs. The RCM river flow is routed using a river-routing model to allow analysis of present day and future river flows through comparison with river gauge observations, where available. In this analysis we compare the river flow rate for 12 gauges selected to represent the largest river basins for this region; Ganges, Indus and Brahmaputra basins and characterize the changing conditions from east to west across the Himalayan arc. Observations of precipitation and runoff in this region have large or unknown uncertainties, are short in length or are outside the simulation period, hindering model development and validation designed to improve understanding of the water cycle for this region. In the absence of robust observations for South Asia, a downscaled ERA-Interim RCM

  12. 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

    South Asia is a region with a large and rising population and a high dependance on industries sensitive to water resource such as agriculture. The climate is hugely variable with the region relying on both the Asian Summer Monsoon (ASM) and glaciers for its supply of fresh water. In recent years, changes in the ASM, fears over the rapid retreat of glaciers and the increasing demand for water resources for domestic and industrial use, have caused concern over the reliability of water resources both in the present day and future for this region. The climate of South Asia means it is one of the most irrigated agricultural regions in the world, therefore pressures on water resource affecting the availability of water for irrigation could adversely affect crop yields and therefore food production. In this paper we present the first 25 km resolution regional climate projections of river flow for the South Asia region. ERA-Interim, together with two global climate models (GCMs), which represent the present day processes, particularly the monsoon, reasonably well are downscaled using a regional climate model (RCM) for the periods; 1990-2006 for ERA-Interim and 1960-2100 for the two GCMs. The RCM river flow is routed using a river-routing model to allow analysis of present day and future river flows through comparison with river gauge observations, where available. In this analysis we compare the river flow rate for 12 gauges selected to represent the largest river basins for this region; Ganges, Indus and Brahmaputra basins and characterize the changing conditions from east to west across the Himalayan arc. Observations of precipitation and runoff in this region have large or unknown uncertainties, are short in length or are outside the simulation period, hindering model development and validation designed to improve understanding of the water cycle for this region. In the absence of robust observations for South Asia, a downscaled ERA-Interim RCM simulation provides a

  13. 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.

  14. Rainfall-runoff modelling for estimating Latonyanda River flow contributions to Luvuvhu River downstream of Albasini Dam

    Science.gov (United States)

    Odiyo, J. O.; Phangisa, J. I.; Makungo, R.

    Rainfall-runoff modelling was conducted to estimate the flows that Latonyanda River contribute to Luvuvhu River downstream of Albasini Dam. The confluence of Latonyanda and Luvuvhu Rivers is ungauged. The contributed flows compensate for upstream water abstractions and periodic lack of releases from Albasini Dam. The flow contributions from tributaries to Luvuvhu River are important for ecosystem sustenance, meeting downstream domestic and agricultural water demand and ecological water requirements particularly in Kruger National Park. The upper Latonyanda River Quaternary Catchment (LRQC), with streamflow gauging station number A9H027 was delineated and used for rainfall-runoff modelling. The simulation was done using Mike 11 NAM rainfall-runoff model. Calibration and verification runs of Mike 11 NAM rainfall-runoff model were carried out using data for periods of 4 and 2 years, respectively. The model was calibrated using shuffled complex evolution optimizer. The model efficiency was tested using coefficient of determination (R2), root mean square error (RMSE), overall water balance error (OWBE) and percentage bias (PBIAS). The model parameters obtained from the upper LRQC were transferred and used together with rainfall and evaporation data for 40 years period in the simulation of runoff for the LRQC. The flows that Latonyanda River contribute to Luvuvhu River were computed by subtracting irrigation abstractions and runoff drained to Tshakhuma Dam from the simulated runoff time series of the LRQC. The observed and the simulated runoff showed similar trends and measures of performances for both calibration and verification runs fell within acceptable ranges. The pairs of values obtained for R2, RMSE, OWBE and PBIAS for calibration and verification were 0.86 and 0.73, 0.21 and 0.2, 2.1 and 1.3, and 4.1 and 3.4, respectively. The simulated runoff for LRQC correlated well with the areal rainfall showing that the results are reasonable. The mean and maximum daily

  15. Groundwater response to the 2014 pulse flow in the Colorado River Delta

    Science.gov (United States)

    Kennedy, Jeffrey; Rodriguez-Burgueno, Eliana; Ramirez-Hernandez, Jorge

    2017-01-01

    During the March-May 2014 Colorado River Delta pulse flow, approximately 102 × 106 m3 (82,000 acre-feet) of water was released into the channel at Morelos Dam, with additional releases further downstream. The majority of pulse flow water infiltrated and recharged the regional aquifer. Using groundwater-level and microgravity data we mapped the spatial and temporal distribution of changes in aquifer storage associated with pulse flow. Surface-water losses to infiltration were greatest around the Southerly International Boundary, where a lowered groundwater level owing to nearby pumping created increased storage potential as compared to other areas with shallower groundwater. Groundwater levels were elevated for several months after the pulse flow but had largely returned to pre-pulse levels by fall 2014. Elevated groundwater levels in the limitrophe (border) reach extended about 2 km to the east around the midway point between the Northerly and Southerly International Boundaries, and about 4 km to the east at the southern end. In the southern part of the delta, although total streamflow in the channel was less due to upstream infiltration, augmented deliveries through irrigation canals and possible irrigation return flows created sustained increases in groundwater levels during summer 2014. Results show that elevated groundwater levels and increases in groundwater storage were relatively short lived (confined to calendar year 2014), and that depressed water levels associated with groundwater pumping around San Luis, Arizona and San Luis Rio Colorado, Sonora cause large, unavoidable infiltration losses of in-channel water to groundwater in the vicinity.

  16. Climate Change Impacts and Adaptation to Flow of Swat River and Glaciers in Hindu Kush Ranges, Swat District, Pakistan (2003-2013

    Directory of Open Access Journals (Sweden)

    Saifullah Khan

    2016-06-01

    Full Text Available This work aims at the climate change impacts and adaptation to surface flow of Swat river and glacier resources in Swat river catchments area, Hindu Kush ranges, Northwest Pakistan. The data about temperature and precipitation have been collected from the Pakistan Meteorological Department, Karachi, whereas the Swat River flow data from the Irrigation Department, Peshawar, Khyber Pukhtunkhwa. Two types of climate that is humid and undifferentiated highlands prevail over the area. The total precipitation recorded has been 41.8inches (1061.7 millimeters with mean monthly precipitation of 3.5 inches (88.9 millimeters having a decrease of -0.1 inch (-2.8 millimeters. The area has been humid during 2004 and currently at the threshold of the sub-humid climates (20-40 inches. Kalam valley experiences cold long winters (7 months and short warm summers (5 months. The mean temperature reveals an increase of 0.90C, maximum temperature 0.40C and mean minimum temperature 0.50Celsius. This increase in the temperature of the area has caused water stress and retreat of glaciers and affected the permafrost condition at higher altitudes in the area. The annual flow of the Swat river is 192.2 cubic meter/seconds with a decline of -0.03 cubic m/sec from 2003 to 2013. The annual trend of water flow is directly proportional to precipitation and contrary to maximum temperature during 2003 to 2012 and shows converse condition till 2013. The decrease in the flow of Swat river seems both in winter and summer season. The glaciers and snow covered area of the Kalam valley decreases with passage of time and required mitigation. The vulnerability of the study area to climate change can be minimized by the construction of small reservoirs, river embankments, improvement in sewerage and sanitation, planning for flood water, and revision of the water management policy, implementation, and establishment of research and development funds.

  17. Low-flow characteristics and profiles for the Rocky River in the Yadkin-Pee Dee River basin, North Carolina, through 2002

    Science.gov (United States)

    Weaver, J. Curtis; Fine, Jason M.

    2003-01-01

    An understanding of the magnitude and frequency of low-flow discharges is an important part of protecting surface-water resources and planning for municipal and industrial economic expansion. Low-flow characteristics are summarized for 12 continuous-record gaging stations and 44 partial-record measuring sites in the Rocky River basin in North Carolina. Records of discharge collected through the 2002 water year at continuous-record gaging stations and through the 2001 water year at partial-record measuring sites were used. Flow characteristics included in the summary are (1) average annual unit flow; (2) 7Q10 low-flow discharge, the minimum average discharge for a 7-consecutive-day period occurring, on average, once in 10 years; (3) 30Q2 low-flow discharge; (4) W7Q10 low-flow discharge, which is similar to 7Q10 discharge but is based only on flow during the winter months of November through March; and (5) 7Q2 low-flow discharge. The Rocky River basin drains 1,413 square miles (mi2) of the southern Piedmont Province in North Carolina. The Rocky River is about 91 miles long and merges with the Yadkin River in eastern Stanly County to form the Pee Dee River, which discharges into the Atlantic Ocean in South Carolina. Low-flow characteristics compiled for selected sites in the Rocky River basin indicated that the potential for sustained base flows in the upper half of the basin is relatively higher than for streams in the lower half of the basin. The upper half of the basin is underlain by the Charlotte Belt, where streams have been identified as having moderate potentials for sustained base flows. In the lower half of the basin, many streams were noted as having little to no potential for sustained base flows. Much of the decrease in base-flow potential is attributed to the underlying rock types of the Carolina Slate Belt. Of the 19 sites in the basin having minimal (defined as less than 0.05 cubic foot per second) or zero 7Q10 discharges, 18 sites are located in the

  18. New river flow maxima in Northern England, December 2015: Implications for flood hazard and risk assessment?

    Science.gov (United States)

    Thornton, James

    2016-04-01

    December 2015 was recently confirmed as the UK's wettest month on record by the Met Office. The most extreme precipitation was associated with three extratropical storm systems, named Desmond, Eva and Frank by the pilot Met Éireann/Met Office "Name our storms" project. In response, river levels reached new maxima at many locations across Northern England. Property damage was widespread, with at least 16,000 homes in England flooded. As with recent predecessors, these events reinvigorated public debate about the extent to which natural weather variability, anthropogenic climate change, increased urbanisation and/or other changes in catchment and river management might be responsible for apparent increases in flood frequency and severity. Change detection and attribution science is required to inform the debate, but is complicated by the short (typically ~ 35 years) river flow records available. Running a large number of coupled climate and hydrological model simulations is a powerful way of addressing the 'attribution question' with respect to the hypothesised climate forcing, for example, albeit one that remains largely in the research domain at present. In the meantime, flood-frequency analysis of available records still forms the bedrock of practice in the water industry; the results are used routinely in the design of new defence structures and in the development of flood hazard maps, amongst other things. In such analyses, it is usual for the records to be assumed stationary. In this context, the specific aims of this research are twofold: • To investigate whether, under the assumption of stationarity, the outputs of standard flood-frequency modelling methods (both 'single-site' and 'spatially pooled' methods) differ significantly depending on whether the new peaks are included or excluded, and; • To assess the sustainability of previous conclusions regarding trends in English river flows by reapplying simple statistical tests, such as the Mann-Kendal test

  19. Environmental flows allocation in river basins: Exploring allocation challenges and options in the Great Ruaha River catchment in Tanzania

    Science.gov (United States)

    Kashaigili, Japhet J.; Kadigi, Reuben M. J.; Lankford, Bruce A.; Mahoo, Henry F.; Mashauri, Damus A.

    Provision for environmental flows is currently becoming a central issue in the debate of integrated water resources management in river basins. However, the theories, concepts and practical applications are still new in most developing countries with challenging situations arising in complex basins with multiple water uses and users and increasing water demands and conflicts exemplified by the Great Ruaha River catchment in Tanzania. The research has shown that a flow of 0.5-1 m 3/s for Great Ruaha River through the Ruaha National Park is required to sustain the environment in the park during the dry season. But a question is how can this be achieved? This paper reviews the challenges and suggests some options for achieving environmental water allocation in river basins. The following challenges are identified: (a) the concept of environmental flows is still new and not well known, (b) there is limited data and understanding of the hydrologic and ecological linkages, (c) there is insufficient specialist knowledge and legislative support, (d) there are no storage reservoirs for controlled environmental water releases, and (e) there are contradicting policies and institutions on environmental issues. Notwithstanding these challenges, this paper identifies the options towards meeting environmental water allocation and management: (a) conducting purposive training and awareness creation to communities, politicians, government officials and decision makers on environmental flows, (b) capacity building in environmental flows and setting-up multidisciplinary environmental flows team with stakeholders involvement, (c) facilitating the development of effective local institutions supported by legislation, (d) water harvesting and storage and proportional flow structures design to allow water for the environment, and (e) harmonizing policies and reform in water utilization and water rights to accommodate and ensure water for the environment.

  20. Modeling Economic Impacts of Environmental Flows in California's Yuba River Watershed

    Science.gov (United States)

    Rheinheimer, D. E.; Yarnell, S.; Viers, J. H.

    2010-12-01

    Managing rivers is becoming more challenging with increasing demand for better environmental flow regimes, just as demand for water for hydropower and water supply are increasing and water supplies are changing due to climate change. Restoration of freshwater ecosystems, such as in the Yuba River in California’s Sierra Nevada, will require flows that mimic the natural flow regime, which native freshwater species are uniquely adapted to. In particular, freshwater ecosystems of the Sierra Nevada were historically adapted to the spring snowmelt flows. To study the potential effects of restoring a natural flow regime to the Yuba River watershed, we developed a multi-reservoir network flow optimization model of the watershed that represents environmental flows more ecologically useful than simple minimum instream flows, which are typically the only environmental requirement in streams. The model uses weekly time steps. The objective function is to maximize benefit, which equals hydropower revenue less penalties for deviations from environmental constraints and spills. Constraints include targets for minimum flows, maximum flows, maximum weekly up-ramp rates and maximum weekly down-ramp rates. We applied the model to the Yuba River watershed surface water inflow data from a rainfall-runoff model recently developed for the Sierra Nevada that considers regional climate warming of +0, 2, 4 and 6 °C. The Yuba watershed has high potential for fish restoration yet is currently managed primarily for hydropower. We assess the economic effects (primarily impacts on hydropower generation and revenues in the adjacent Bear River) and management implications of increasing and reshaping instream flow requirements in several ecologically important, yet regulated, stream reaches within the Yuba watershed. Further, we explore the potential of using regulating reservoirs to adapt to changing hydrologic conditions. Increasing minimum instream flow magnitudes in the South Fork Yuba River

  1. Pomona Member of the Columbia River Basalt Group: an intracanyon flow in the Columbia River Gorge, Oregon.

    Science.gov (United States)

    Anderson, J.L.

    1980-01-01

    The Pomona Member of the Saddle Mountains Basalt (Columbia River Basalt Group) occurs as an intracanyon flow greater than 75m (250ft) thick along the S side of the Columbia River Gorge between Mitchell Point and Shellrock Mountain, Oregon. Best exposures are at Mitchell Point, where this flow caps more than 70m (230ft) of cobble conglomerate that partially fills a canyon cut into flows of the underlying Frenchman Springs Member. These exposures provide a necessary link between outcrops of the Pomona Member in the Columbia Plateau and western Washington. Post-Frenchman Springs, pre-Pomona canyon cutting implies deformation in the ancestral Cascade Range between about 14.5 and 12Ma ago.-Author

  2. EFFECT OF SANTA ROSA LAKE ON GROUND WATER FLOW TO THE PECOS RIVER, NEW MEXICO.

    Science.gov (United States)

    Risser, Dennis W.

    1985-01-01

    In 1980, Santa Rosa Dam began impounding water on the Pecos River about 7 miles (11 kilometers) north of Santa Rosa, New Mexico, to provide flood control and storage for irrigation. Santa Rosa Lake has caused changes in the ground water flow system, which may cause changes in the streamflow of the Pecos River that cannot be detected at the present streamflow-gaging stations, which are used to administer water rights along the Pecos River. The effect of the lake on streamflow was investigated using a three-dimensional ground water flow model. These simulations indicated that the net change in ground water flow to the river would be almost zero if the lake were maintained at its flood control pool for 90 days.

  3. 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

  4. 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.

  5. Effects of flow regimes altered by dams on survival, population declines, and range-wide losses of California river-breeding frogs.

    Science.gov (United States)

    Kupferberg, Sarah J; Palen, Wendy J; Lind, Amy J; Bobzien, Steve; Catenazzi, Alessandro; Drennan, Joe; Power, Mary E

    2012-06-01

    Widespread alteration of natural hydrologic patterns by large dams combined with peak demands for power and water delivery during summer months have resulted in frequent aseasonal flow pulses in rivers of western North America. Native species in these ecosystems have evolved with predictable annual flood-drought cycles; thus, their likelihood of persistence may decrease in response to disruption of the seasonal synchrony between stable low-flow conditions and reproduction. We evaluated whether altered flow regimes affected 2 native frogs in California and Oregon (U.S.A.) at 4 spatial and temporal extents. We examined changes in species distribution over approximately 50 years, current population density in 11 regulated and 16 unregulated rivers, temporal trends in abundance among populations occupying rivers with different hydrologic histories, and within-year patterns of survival relative to seasonal hydrology. The foothill yellow-legged frog (Rana boylii), which breeds only in flowing water, is more likely to be absent downstream of large dams than in free-flowing rivers, and breeding populations are on average 5 times smaller in regulated rivers than in unregulated rivers. Time series data (range = 8 - 19 years) from 5 populations of yellow-legged frogs and 2 populations of California red-legged frogs (R. draytonii) across a gradient of natural to highly artificial timing and magnitude of flooding indicate that variability of flows in spring and summer is strongly correlated with high mortality of early life stages and subsequent decreases in densities of adult females. Flow management that better mimics natural flow timing is likely to promote persistence of these species and others with similar phenology.

  6. 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

  7. Seasonal Variations of Stable Isotope Composition of River Flow in Permafrost Regions of Yenisei and Kolyma Rivers (Russia)

    Science.gov (United States)

    Streletskiy, D. A.; Davydova, A.; Davydov, S. P.; Opel, T.; Shiklomanov, A. I.; Shiklomanov, N. I.; Streletskaya, I. D.; Tananaev, N.; Tokarev, I.

    2015-12-01

    Permafrost plays an important role in the hydrology of the northern regions. To investigate the role of climate change on permafrost degradation and hydrology, extensive field work was conducted in a series of small watersheds located in the discontinuous permafrost zone of the lower Yenisei River near Igarka, and in the continuous permafrost zone of the Kolyma River near Cherskii. Climatic, hydrologic and permafrost characteristics were monitored at both locations over a three year period and extended using historical data. Stable isotope composition of rain, snow, water from lakes and rivers, and various types of ground ice was used to determine various inputs and runoff pathways to a river flow in several watersheds. The study found that water flow of smaller creeks follows precipitation closely, while flow of larger rivers is affected by evaporation effects related to water storage in thermokarst lakes. Ground ice of the epigenetic permafrost near Igarka has a similar isotopic composition as that of Holocene permafrost and contemporary late summer precipitation. Ground ice of the syngenetic Pleistocene permafrost (Ice Complex) near Cherskii has a significantly lighter isotopic composition than pore water of the active and transient layers. Increases in air temperature resulted in thickening of the active-layer and melting of ice that reach the transient layer in continuous permafrost. In areas where the transient layer severely reduced as a result of intense forest fires and other landscape disturbances, ground ice from permafrost is also involved in hydrological processes. Progressive decrease in the seasonal freezing layer thickness and a lower permafrost table promoted more groundwater storage and redistribution of summer precipitation towards winter baseflow in discontinuous permafrost region. The major contribution of permafrost at both locations is not through the melting of ground ice, but through changes in soil properties affecting the water flow.

  8. 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

  9. Fragmentation and flow regulation of the world's large river systems.

    Science.gov (United States)

    Nilsson, Christer; Reidy, Catherine A; Dynesius, Mats; Revenga, Carmen

    2005-04-15

    A global overview of dam-based impacts on large river systems shows that over half (172 out of 292) are affected by dams, including the eight most biogeographically diverse. Dam-impacted catchments experience higher irrigation pressure and about 25 times more economic activity per unit of water than do unaffected catchments. In view of projected changes in climate and water resource use, these findings can be used to identify ecological risks associated with further impacts on large river systems.

  10. Comparison of forecasts of mean monthly water level in the Paraguay River, Brazil, from two fractionally differenced models

    Science.gov (United States)

    Prass, Taiane S.; Bravo, Juan Martin; Clarke, Robin T.; Collischonn, Walter; Lopes, SíLvia R. C.

    2012-05-01

    The paper compares forecasts of mean monthly water levels up to six months ahead at Ladário, on the Upper Paraguay River, Brazil, estimated from two long-range dependence models. In one of them, the marked seasonal cycle was removed and a fractionally differenced model was fitted to the transformed series. In the other, a seasonal fractionally differenced model was fitted to water levels without transformation. Forecasts from both models for periods up to six months ahead were compared with forecasts given by simpler "short-range dependence" Box-Jenkins models, one fitted to the transformed series, the other a seasonal autoregressive moving average (ARMA) model. Estimates of parameters in the four models (two "long-range dependence", two "short-range dependence") were updated at six-monthly intervals over a 20 year period, and forecasts were compared using root mean square errors (rmse) between water-level forecasts and observed levels. As judged by rmse, performances of the two long-range dependence models, and of the ARMA (1,1) short-range dependence model, were very similar; all three out-performed the seasonal short-range dependence ARMA model. There was evidence that all models performed better during recession periods, than on the hydrograph rising limb.

  11. Response of bankfull discharge of the Inner Mongolia Yellow River to flow and sediment factors

    Indian Academy of Sciences (India)

    Suzhen Hou; Ping Wang; Yan Guo; Ting Li

    2014-08-01

    Bankfull discharge is a comprehensive factor reflecting the channel-forming capability of water flow and the flood and sediment transport capacity of a river channel. It is based on the interaction of the flow, sediment, and river channel, of which flow and sediment conditions play crucial roles. Using data recorded since the 1950s, this paper analyses statistically, the characteristics and variations of bankfull discharge at two stations on the Inner Mongolian reaches of the upper Yellow River. Results indicate that flood season variations in bankfull discharge are nonlinear and are governed by flood peak discharge, mean discharge, and the mean incoming sediment coefficients. Variation in bankfull discharge is related not only to the flow and sediment conditions of the current year but also to those of previous years. The 10-year moving average of flow and sediment conditions can be representative of present and previous years. By considering flood season peak discharge and incoming sediment coefficients as independent impact factors, a formula is derived to determine bankfull discharge. The results can be used to predict the bankfull discharge of the Yellow River channel in Inner Mongolia under specific flow and sediment conditions and provide reference for the purpose of further study related to restoring and maintaining the basic functions of the river channel regarding flood discharge and sediments.

  12. Comparative Assessment of Environmental Flow Estimation Methods in a Mediterranean Mountain River

    Science.gov (United States)

    Papadaki, Christina; Soulis, Konstantinos; Ntoanidis, Lazaros; Zogaris, Stamatis; Dercas, Nicholas; Dimitriou, Elias

    2017-08-01

    The ecological integrity of rivers ultimately depends on flow regime. Flow degradation is especially prominent in Mediterranean systems and assessing environmental flows in modified rivers is difficult, especially in environments with poor hydrologic monitoring and data availability. In many Mediterranean countries, which are characterized by pronounced natural variability and low summer flows, water management actions usually focus on prescribing minimum acceptable flows estimated by hydrologic methods. In this study, a comparative assessment of environmental flow estimation methods is developed in a river with poorly monitored flows and limited understanding of past reference conditions. This assessment incorporates both a hydrologic and a fish habitat simulation effort that takes into consideration hydrologic seasonality in a Greek mountainous river. The results of this study indicate that especially in data scarce regions the utilization of biotic indicators through habitat models, may provide valuable information, beyond that achievable with hydrologic methods, for developing regional environmental flow criteria. Despite the widespread use of the method, challenges in transferability of fish habitat simulation provide undefined levels of uncertainty and may require the concurrent use of different assessment tools and site-specific study.

  13. Tidal impacts on the subtidal flow division at the main bifurcation in the Yangtze River Delta

    NARCIS (Netherlands)

    Zhang, Wei; Feng, Haochuan; Hoitink, A.J.F.; Zhu, Yuliang; Gong, Fei; Zheng, Jinhai

    2017-01-01

    Flow division at bifurcations in the Yangtze Estuary has received ample attention, since it may control the pathways of terrestrial sediments over downstream river branches including the 12.5 m Deepwater Navigation channel. While some efforts have been made to interpret flow division at the bifurcat

  14. 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.

  15. Linking river flow regimes to riparian plant guilds: a community-wide modeling approach.

    Science.gov (United States)

    Lytle, David A; Merritt, David M; Tonkin, Jonathan D; Olden, Julian D; Reynolds, Lindsay V

    2017-06-01

    Modeling riparian plant dynamics along rivers is complicated by the fact that plants have different edaphic and hydrologic requirements at different life stages. With intensifying human demands for water and continued human alteration of rivers, there is a growing need for predicting responses of vegetation to flow alteration, including responses related to climate change and river flow management. We developed a coupled structured population model that combines stage-specific responses of plant guilds with specific attributes of river hydrologic regime. The model uses information on the vital rates of guilds as they relate to different hydrologic conditions (flood, drought, and baseflow), but deliberately omits biotic interactions from the structure (interaction neutral). Our intent was to (1) consolidate key vital rates concerning plant population dynamics and to incorporate these data into a quantitative framework, (2) determine whether complex plant stand dynamics, including biotic interactions, can be predicted from basic vital rates and river hydrology, and (3) project how altered flow regimes might affect riparian communities. We illustrated the approach using five flow-response guilds that encompass much of the river floodplain community: hydroriparian tree, xeroriparian shrub, hydroriparian shrub, mesoriparian meadow, and desert shrub. We also developed novel network-based tools for predicting community-wide effects of climate-driven shifts and deliberately altered flow regimes. The model recovered known patterns of hydroriparian tree vs. xeroriparian shrub dominance, including the relative proportion of these two guilds as a function of river flow modification. By simulating flow alteration scenarios ranging from increased drought to shifts in flood timing, the model predicted that mature hydroriparian forest should be most abundant near the observed natural flow regime. Multiguild sensitivity analysis identified substantial network connectivity (many

  16. Mass flows of endocrine disruptors in the Glatt River during varying weather conditions

    Energy Technology Data Exchange (ETDEWEB)

    Jonkers, Niels; Kohler, Hans-Peter E.; Dammshaeuser, Anna [Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Duebendorf (Switzerland); Giger, Walter [Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Duebendorf (Switzerland)], E-mail: giger@eawag.ch

    2009-03-15

    This study focused on the occurrence and behaviour in wastewater and surface waters of several phenolic endocrine disrupting compounds (EDCs) including parabens, alkylphenolic compounds, phenylphenol (PhP) and bisphenol A (BPA). Analytical procedures using solid-phase-extraction and LC-MS/MS techniques were applied to samples of influents and effluents of wastewater treatment plants (WWTPs) discharging into the Glatt River (Switzerland) as well as to river water samples. A mass flow analysis provided insight into the main sources and the fate of these contaminants during different weather conditions. Concentrations in influents were in the low {mu}g/L range for most analytes. Removal of parabens in the WWTPs was mostly above 99%. Nonylphenol polyethoxylates (A{sub 9}PEO) removal amounted to 98%, but in some cases nonylphenoxy acetic acid (A{sub 9}PEC) or nonylphenols (NP) were formed. In effluents, concentrations were highest for the A{sub 9}PEC, A{sub 9}PEO and NP. Concentrations in river water were in the high ng/L range for alkylphenolic compounds and in the low ng/L range for BPA, PhP and the parabens. During the sampling period, in which several rain events occurred, both water flows and mass flows varied strongly. Mass flows in WWTP effluents and in the river increased with increasing water flows for most compounds indicating that higher water flows do not lead necessarily to a proportional dilution of the pollutants. Throughout the low water flow period, mass flows predicted from the known inputs were similar to the actual mass flows at the end of the river for most analytes. For none of the EDCs, significant in-stream removal could be observed. In the periods with high water flows, mass flows in the river were much higher than can be explained by the initially defined sources. Discharge of untreated wastewater influent into the river was assessed as an additional source. Adding this source improved the mass balance for some, but not all of the analytes

  17. Quantifying braided river morphodynamics through a sequence of high-flow events

    Science.gov (United States)

    Williams, R. D.; Brasington, J.; Vericat, D.; Hicks, D. M.

    2012-04-01

    Quantifying braided river morphology and morphological change is a key task for understanding braided river behaviour. In the last decade, developments in geomatics technologies and associated data processing toolboxes have transformed the potential for producing precise, reach-scale topographic datasets. Moreover, since fast data acquisition rates enable surveys to be undertaken at frequencies that are commensurate with individual flood events, it is now possible to map morphological change for sequences of high-flow events over considerable spatial extents. The application of high-resolution remote sensing technologies to monitor braided river dynamics thus has the potential to provide considerable insight into the relationships between forcing discharges, sediment transport and morphological evolution. In this paper we present a set of Digital Elevation Models (DEMs) that have been produced by monitoring the evolution of a 2.5 x 0.7 km braided study area of the Rees River, New Zealand, through a sequence of ten high-flow events over an eight-month period. We then use the morphological approach to produce a sediment budget for the study area. The morphological evolution of the Rees River braided study area was monitored after each storm event using a combination of two remote sensing methodologies. First, dry areas of the braidplain were surveyed using a Terrestrial Laser Scanner (TLS) mounted on an Argo Amphibious All Terrain Vehicle. Second, since the TLS was not water penetrating, bathymetry was mapped using an empirically calibrated optical method, based on non-metric vertical aerial photos acquired from a helicopter and an acoustic depth survey along primary anabranches. The resulting data were fused together to produce high quality DEMs, with sub-cm and sub-decimetre vertical standard deviations of error for the TLS and optical-empirical bathymetric components respectively. The resulting set of DEMs enabled the quantification of morphological change through

  18. Explaining the internal behaviour of artificial neural network river flow models

    Science.gov (United States)

    Sudheer, K. P.; Jain, Ashu

    2004-03-01

    A novel method of visualizing and understanding the internal functional behaviour of an artificial neural network (ANN) river flow model is presented. The method hypothesizes that an ANN is able to map a function similar to the flow duration curve while modelling the river flow. A mathematical analysis of the hypothesis is presented, and a case study of an ANN river flow model confirms its significance. The proposed approach is also useful within other models that improve the performance of an ANN. The reasons why these models improve a raw ANN can be clearly understood using this approach. While the field of ANN knowledge-extraction is one that continues to attract considerable interest, it is anticipated that the current approach will initiate further research and make ANNs more useful to the hydrologic community.

  19. Short-term variations in core surface flow resolved from an improved method of calculating observatory monthly means

    DEFF Research Database (Denmark)

    Olsen, Nils; Whaler, K. A.; Finlay, Chris

    2014-01-01

    Monthly means of the magnetic field measurements taken by ground observatories are a useful data source for studying temporal changes of the core magnetic field and the underlying core flow. However, the usual way of calculating monthly means as the arithmetic mean of all days (geomagnetic quiet...... as well as disturbed) and all local times (day and night) may result in contributions from external (magnetospheric and ionospheric) origin in the (ordinary, omm) monthly means. Such contamination makes monthly means less favourable for core studies. We calculated revised monthly means (rmm...... a secular variation spherical harmonic model. The main field is specified by the CHAOS-4 model. Data from up to 128 observatories between 1997 and 2013 were used to calculate 185 flow models from the omm and rmm, for each possible set of three consecutive months. The full 3x3 (non-diagonal) data covariance...

  20. Groundwater Flow Modeling Using Pmwin Model in the Wakal River Basin, Rajasthan, India

    Science.gov (United States)

    Biswas, H.; Melesse, A.; McClain, M.; Sukop, M.

    2008-05-01

    The absence of surface water resources in the driest and largest state of India, Rajasthan, has put pressure on the groundwater resources of the state. The water supply problem is exacerbated by the increasing human population, deforestation, unsustainable land-use and irrigation practices. The problem is even severe during droughts. The monsoon rainfall from June to September is the main source of the groundwater recharge in the region.To be able to exploit this natural resource in a sustainable manner with minimal impact on the environment, there is a need to evaluate the potential of the aquifer in terms of water quantity and replenishment using the tolls of groundwater modeling. A numerical model for regional ground water flow was developed using Processing Modflow for Windows (PMWIN)model for a 120 squre Km watershed in the Wakal River Basin in the Jhadol block, Udaipur District, Rajasthan. The model was calibrated for steady state conditions. Watershed boundary formed the no-flow boundaries and was set around the model except north-east part of the study area, where the boundary had been set as constant head. The modeled area consisted of a 143 columns x 177 rows with one layer which simulated an unconfined aquifer in a hard rock terrain. Hydraulic conductivity of the unconfined aquifer were determined using pump tests conducted in the field and validated from literature of studies in a similar groundwater system. Main input of the model was determined from the 3-months monsoon rainfall. Abstraction rates from open dug wells, and evapotranspiration were applied as output at different cells. A steady-state flow simulation was carried out and calibrated against July 2006 water levels. The calibration was carried out by comparing computed and observed heads at 187 wells. There was a good match between the simulated water level contours with the observed water level contours. This model can be used in the future to run transient simulations for full understanding

  1. [Assessment of ecosystem energy flow and carrying capacity of swimming crab enhancement in the Yellow River estuary and adjacent waters].

    Science.gov (United States)

    Lin Qun; Wang, Jun; Li, Zhong-yi; Wu, Qiang

    2015-11-01

    Stock enhancement is increasingly proved to be an important measure of the fishery resources conservation, and the assessment of carrying capacity is the decisive factor of the effects of stock enhancement. Meanwhile, the variations in the energy flow patterns of releasing species and ecosystem were the basis for assessing carrying capacity of stock enhancement. So, in the present study, based on the survey data collected from the Yellow River estuary and adjacent waters during 2012-2013, three Ecopath mass-balance models were established in June, August and October, and the variations in ecosystem energy flow in these months were analyzed, as well as the assessment of carrying capacity of swimming crab enhancement. The energy flow mainly concentrated on trophic level I-III in Yellow River estuary and adjacent waters, and was relatively less on trophic level IV or above. The system flow proportion on the trophic level I was the highest in June, and was the lowest in August. The highest system flow proportion on the trophic level II was found in August, and the lowest in June. The relative and absolute energy flow of swimming crab mainly concentrated on the trophic level III, and the mean trophic level of swimming crab among June, August and October were 3.28. Surplus production was relatively higher in Yellow River estuary and adjacent waters, the highest value was found in June, and the lowest value in August. The ratios of total primary production/total respiration (TPP/TR) were 5.49, 2.47 and 3.01 in June, August and October, respectively, and the ratios of total primary production/total biomass (TPP/B) were 47.61, 33.30 and 29.78, respectively. Combined with the low Finn' s cycling index (FCI: 0.03-0.06), these changes indicated that the Yellow River estuary ecosystem was at an early development stage with higher vulnerability. The energy conversion efficiency of system was from 7.3% to 11.5%, the mean trophic levels of the catch were 3.23, 2.97 and 2.82 in

  2. Distribution Regularity of Debris Flow and Its Hazard in Upper Reaches of Yangtze River and Other Rivers of Southwestern China

    Institute of Scientific and Technical Information of China (English)

    WEI Fangqiang; JIANG Yuhong; GUI Peng; DING Mingtao

    2007-01-01

    In the upper reaches of Yangtze River and other rivers of southwestern China, the debris flows develop and lead to most serious disasters because of the various landforms, complex geological structures and abundant rainfall. The distribution of debris flows has regularity in the regions with different landform, geological structure, and precipitation. The regularities of distribution of debris flows are as following:① distributed in transition belts of different morphologic regions; ②distributed in the area with strong stream trenching; ③distributed along fracture zones and seismic belts: ④distributed in the area with abundant precipitation;⑤ distribution of debris flow is azonal. The activity of abundant debris flows not only brings harm to Towns, Villages and Farmlands, Main Lines of Communication, Water-Power Engineering, Stream Channels etc., but also induces strong water and soil loss. According to the present status of debris flow prevention, the problems in disasters mitigation and soil conservancy are found out, and the key works are brought up for the future disasters prevention and soil conservancy.

  3. Hydrogeology and simulated groundwater flow and availability in the North Fork Red River aquifer, southwest Oklahoma, 1980–2013

    Science.gov (United States)

    Smith, S. Jerrod; Ellis, John H.; Wagner, Derrick L.; Peterson, Steven M.

    2017-09-28

    definition of the aquifer extent and potentiometric surface, as well as a description of the textural and hydraulic properties of aquifer materials. The hydrogeologic framework was used in the construction of a numerical groundwater-flow model of the North Fork Red River aquifer described in this report. A conceptual model of aquifer inflows and outflows was developed for the North Fork Red River aquifer to constrain the construction and calibration of a numerical groundwater-flow model that reasonably represented the groundwater-flow system. The conceptual-model water budget estimated mean annual inflows to and outflows from the North Fork Red River aquifer for the period 1980–2013 and included a sub-accounting of mean annual inflows and outflows for the portions of the aquifer that were upgradient and downgradient from Lake Altus. The numerical groundwater-flow model simulated the period 1980–2013 and was calibrated to water-table-altitude observations at selected wells, monthly base flow at selected streamgages, net streambed seepage as estimated for the conceptual model, and Lake Altus stage.Groundwater-availability scenarios were performed by using the calibrated numerical groundwater-flow model to (1) estimate the EPS pumping rate that guarantees a minimum 20-, 40-, and 50-year life of the aquifer, (2) quantify the potential effects of projected well withdrawals on groundwater storage over a 50-year period, and (3) simulate the potential effects of a hypothetical (10-year) drought on base flow and groundwater storage. The results of the groundwater-availability scenarios could be used by the Oklahoma Water Resources Board to reevaluate the maximum annual yield of groundwater from the North Fork Red River aquifer.EPS scenarios for the North Fork Red River aquifer were run for periods of 20, 40, and 50 years. The 20-, 40-, and 50-year EPS pumping rates under normal recharge conditions were 0.59, 0.52, and 0.52 acre-foot per acre per year, respectively. Given the 497

  4. South Fork Shenandoah River habitat-flow modeling to determine ecological and recreational characteristics during low-flow periods

    Science.gov (United States)

    Krstolic, Jennifer L.; Ramey, R. Clay

    2012-01-01

    The ecological habitat requirements of aquatic organisms and recreational streamflow requirements of the South Fork Shenandoah River were investigated by the U.S. Geological Survey in cooperation with the Central Shenandoah Valley Planning District Commission, the Northern Shenandoah Valley Regional Commission, and Virginia Commonwealth University. Physical habitat simulation modeling was conducted to examine flow as a major determinant of physical habitat availability and recreation suitability using field-collected hydraulic habitat variables such as water depth, water velocity, and substrate characteristics. Fish habitat-suitability criteria specific to the South Fork Shenandoah River were developed for sub-adult and adult smallmouth bass (Micropterus dolomieu), juvenile and sub-adult redbreast sunfish (Lepomis auritus), spotfin or satinfin shiner (Cyprinella spp), margined madtom (Noturus insignis),and river chub (Nocomis micropogon). Historic streamflow statistics for the summer low-flow period during July, August, and September were used as benchmark low-flow conditions and compared to habitat simulation results and water-withdrawal scenarios based on 2005 withdrawal data. To examine habitat and recreation characteristics during droughts, daily fish habitat or recreation suitability values were simulated for 2002 and other selected drought years. Recreation suitability during droughts was extremely low, because the modeling demonstrated that suitable conditions occur when the streamflows are greater than the 50th percentile flow for July, August, and September. Habitat availability for fish is generally at a maximum when streamflows are between the 75th and 25th percentile flows for July, August, and September. Time-series results for drought years, such as 2002, showed that extreme low-flow conditions less than the 5th percentile of flow for July, August, and September corresponded to below-normal habitat availability for both game and nongame fish in the

  5. Decadal oscillations and extreme value distribution of river peak flows in the Meuse catchment

    Science.gov (United States)

    De Niel, Jan; Willems, Patrick

    2017-04-01

    In flood risk management, flood probabilities are often quantified through Generalized Pareto distributions of river peak flows. One of the main underlying assumptions is that all data points need to originate from one single underlying distribution (i.i.d. assumption). However, this hypothesis, although generally assumed to be correct for variables such as river peak flows, remains somehow questionable: flooding might indeed be caused by different hydrological and/or meteorological conditions. This study confirms these findings from previous research by showing a clear indication of the link between atmospheric conditions and flooding for the Meuse river in The Netherlands: decadal oscillations of river peak flows can (at least partially) be attributed to the occurrence of westerly weather types. The study further proposes a method to take this correlation between atmospheric conditions and river peak flows into account when calibrating an extreme value distribution for river peak flows. Rather than calibrating one single distribution to the data and potentially violating the i.i.d. assumption, weather type depending extreme value distributions are derived and composed. The study shows that, for the Meuse river in The Netherlands, such approach results in a more accurate extreme value distribution, especially with regards to extrapolations. Comparison of the proposed method with a traditional extreme value analysis approach and an alternative model-based approach for the same case study shows strong differences in the peak flow extrapolation. The design-flood for a 1,250 year return period is estimated at 4,800 m3s-1 for the proposed method, compared with 3,450 m3s-1 and 3,900 m3s-1 for the traditional method and a previous study. The methods were validated based on instrumental and documentary flood information of the past 500 years.

  6. A time delay artificial neural network approach for flow routing in a river system

    Directory of Open Access Journals (Sweden)

    M. J. Diamantopoulou

    2006-09-01

    Full Text Available River flow routing provides basic information on a wide range of problems related to the design and operation of river systems. In this paper, three layer cascade correlation Time Delay Artificial Neural Network (TDANN models have been developed to forecast the one day ahead daily flow at Ilarionas station on the Aliakmon river, in Northern Greece. The networks are time lagged feed-formatted with delayed memory processing elements at the input layer. The network topology is using multiple inputs, which include the time lagged daily flow values further up at Siatista station on the Aliakmon river and at Grevena station on the Venetikos river, which is a tributary to the Aliakmon river and a single output, which are the daily flow values at Ilarionas station. The choice of the input variables introduced to the input layer was based on the cross-correlation. The use of cross-correlation between the ith input series and the output provides a short cut to the problem of the delayed memory determination. Kalman's learning rule was used to modify the artificial neural network weights. The networks are designed by putting weights between neurons, by using the hyperbolic-tangent function for training. The number of nodes in the hidden layer was determined based on the maximum value of the correlation coefficient. The results show a good performance of the TDANN approach for forecasting the daily flow values, at Ilarionas station and demonstrate its adequacy and potential for river flow routing. The TDANN approach introduced in this study is sufficiently general and has great potential to be applicable to many hydrological and environmental applications.

  7. Electricity vs Ecosystems - understanding and predicting hydropower impact on Swedish river flow

    Science.gov (United States)

    Arheimer, B.; Lindström, G.

    2014-09-01

    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.

  8. 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.

  9. Effects of climate change on three flow regime-related ecosystem services in a highly-regulated Alpine river

    Science.gov (United States)

    Carolli, Mauro; Zolezzi, Guido; Geneletti, Davide; Majone, Bruno; Bellin, Alberto

    2016-04-01

    River systems provide several flow regime-related ecosystem services (ES) to society. The flow regime of several Alpine rivers is often regulated by hydropower production, which represents one of the most relevant ES in the area. Climate change is expected to modify the flow regime of rivers, with possible relevant consequences on the suitability of related ES. In this work we applied an approach aimed at evaluating the variations of ES under different flow regime conditions and consequently, the possibility to quantify the effects of different climate change scenarios on river ecosystem services. The case-study is the Noce River, a gravel-bed river in the Italian Alps (Trentino, North East Italy) which hydrological regime is subject to daily alterations of flow regime (hydropeaking) induced by the management of large hydropower plants. Here we considered three ES indicators: habitat for adult marble trout as representative for habitat provisioning service, rafting for recreational services, and small hydropower production as provisioning service. In particular, we evaluated the daily variations of these indicators under three different operating scenarios: a reference scenarios (REF, from 1970 to 2000) and two future scenarios (from 2040 to 2070), with (FUT) and without (FUT CC) the inclusion of the required minimum environmental flow (minimum vital flow) recently implemented in the regional water resources policy. For each scenario, four climate models have been applied (see Majone et al., 2016). Future scenarios indicate a modification of the flow regime, with a direct effect on the suitability of related ES. The effects on ES differ according with climate models and management scenarios: as a general result and considering the comparison with respect to the reference period, the applied models predict a temporal shift from late to early summer in the rafting suitability, a decrease of the suitability for trout in spring months and an increase of the suitability

  10. Modeling water quality, temperature, and flow in Link River, south-central Oregon

    Science.gov (United States)

    Sullivan, Annett B.; Rounds, Stewart A.

    2016-09-09

    The 2.1-km (1.3-mi) Link River connects Upper Klamath Lake to the Klamath River in south-central Oregon. A CE-QUAL-W2 flow and water-quality model of Link River was developed to provide a connection between an existing model of the upper Klamath River and any existing or future models of Upper Klamath Lake. Water-quality sampling at six locations in Link River was done during 2013–15 to support model development and to provide a better understanding of instream biogeochemical processes. The short reach and high velocities in Link River resulted in fast travel times and limited water-quality transformations, except for dissolved oxygen. Reaeration through the reach, especially at the falls in Link River, was particularly important in moderating dissolved oxygen concentrations that at times entered the reach at Link River Dam with marked supersaturation or subsaturation. This reaeration resulted in concentrations closer to saturation downstream at the mouth of Link River.

  11. Reconstruction palaeoflood hydrology using slackwater flow depth method in the Yanhe River valley, middle Yellow River basin, China

    Science.gov (United States)

    Guo, Yongqiang; Huang, Chun Chang; Pang, Jiangli; Zhou, Yali; Zha, Xiaochun; Mao, Peini

    2017-01-01

    Water depth above the flood deposits should be taken into account in calculations of the palaeoflood peak stages, which can provide more accurately estimate of palaeoflood stage. Here we present a new method, slackwater flow depth, to assess palaeoflood peak stage and to reduce the underestimation of palaeoflood stage. Palaeoflood slackwater deposits (SWDs) were identified by palaeohydrological criteria in cliff riverbank on the Yanhe River, middle Yellow River basin. Palaeoflood events recorded in four layers of SWD were dated by optical stimulated luminescence to 9.5-8.5 ka. The estimation of palaeoflood maximum stage was 778.3 m using the slackwater flow depth method and the palaeoflood peak discharge is 15,000 m3/s using the step-backwater method. Palaeoflood results greatly extend the current flood data series in the Yanhe River basin. The regional flood history including gauged flood, historical and palaeoflood data was compiled and evaluated for the major tributaries of the middle Yellow River. The relationship between palaeoflood peak discharges and drainage areas in this region fit well with the global maximum curves. The results of site-specific and regional palaeoflood evaluations demonstrate that the approach estimates the true palaeoflood peak stage and discharges and improves the flood frequency analysis of extreme and rare floods for a particular basin. Meanwhile, the advantages and uncertainties of this method need ongoing discussion in palaeoflood investigations.

  12. THREE DIMENSIONAL NUMERICAL MODELLING OF FLOW AND SEDIMENT TRANSPORT IN RIVERS

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The 3D numerical model, ECOMSED (open source code), was used to simulate flow and sediment transport in rivers. The model has a long history of successful applications to oceanic, coastal and estuarine waters. Improvements in the advection scheme, treatment of river roughness parameterization and shear stress partitioning were necessary to reproduce realistic and comparable results in a river application. To account for the dynamics of the mobile bed boundary, a model for the bed load transport was included in the code. The model reproduced observed secondary currents,bed shear stress distribution and erosion-deposition patterns on a curved channel. The model also successfully predicted the general flow patterns and sediment transport characteristics ora l-km long reach of the River Klar(a)lven, located in the north of the county of V(a)rmland, Sweden.

  13. 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 flo

  14. Overland Flow Direction Information for the Upper Colorado River Basin in Daymet Climate Data resolution (overland_flow_direction_UCRB_daymet_resolution.txt)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — overland_flow_direction_UCRB_daymet_resolution.txt is an Esri ASCII grid representing overland flow direction in the Upper Colorado River Basin using the D8...

  15. Overland Flow Direction Information for the Upper Colorado River Basin in Maurer et al. (2002) Climate Data resolution (overland_flow_direction_UCRB_Maurer_resolution.asc)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — overland_flow_direction_UCRB_Maurer_resolution.asc is an Esri ASCII grid representing overland flow direction in the Upper Colorado River Basin using the D8...

  16. Suwannee River flow variability 1550-2005 CE reconstructed from a multispecies tree-ring network

    Science.gov (United States)

    Harley, Grant L.; Maxwell, Justin T.; Larson, Evan; Grissino-Mayer, Henri D.; Henderson, Joseph; Huffman, Jean

    2017-01-01

    Understanding the long-term natural flow regime of rivers enables resource managers to more accurately model water level variability. Models for managing water resources are important in Florida where population increase is escalating demand on water resources and infrastructure. The Suwannee River is the second largest river system in Florida and the least impacted by anthropogenic disturbance. We used new and existing tree-ring chronologies from multiple species to reconstruct mean March-October discharge for the Suwannee River during the period 1550-2005 CE and place the short period of instrumental flows (since 1927 CE) into historical context. We used a nested principal components regression method to maximize the use of chronologies with varying time coverage in the network. Modeled streamflow estimates indicated that instrumental period flow conditions do not adequately capture the full range of Suwannee River flow variability beyond the observational period. Although extreme dry and wet events occurred in the gage record, pluvials and droughts that eclipse the intensity and duration of instrumental events occurred during the 16-19th centuries. The most prolonged and severe dry conditions during the past 450 years occurred during the 1560s CE. In this prolonged drought period mean flow was estimated at 17% of the mean instrumental period flow. Significant peaks in spectral density at 2-7, 10, 45, and 85-year periodicities indicated the important influence of coupled oceanic-atmospheric processes on Suwannee River streamflow over the past four centuries, though the strength of these periodicities varied over time. Future water planning based on current flow expectations could prove devastating to natural and human systems if a prolonged and severe drought mirroring the 16th and 18th century events occurred. Future work in the region will focus on updating existing tree-ring chronologies and developing new collections from moisture-sensitive sites to improve

  17. Were rivers flowing across the Sahara during the last interglacial? Implications for human migration through Africa.

    Science.gov (United States)

    Coulthard, Tom J; Ramirez, Jorge A; Barton, Nick; Rogerson, Mike; Brücher, Tim

    2013-01-01

    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.

  18. Water demand for ecosystem protection in rivers with hyper-concentrated sediment-laden flow

    Institute of Scientific and Technical Information of China (English)

    LUO Huaming; LI Tianhong; NI Jinren; WANG Yudong

    2004-01-01

    Sediment transport is one of the main concerns in a river system with hyper-concentrated flows. Therefore, the water use for sediment transport must be considered in study on the water demand for river ecosystem. The conventional methods for calculating the Minimum Water Demand for River Ecosystem (MWDRE) are not appropriate for rivers with high sediment concentration. This paper studied the MWDRE in wet season, dry season and the whole year under different water-and-sediment conditions in the Lower Yellow River, which is regarded as a typical river with sediment-laden flows. The characteristics of MWDRE in the river are analyzed. Firstly,the water demand for sediment transport (WDST) is much larger than the demands for other riverine functions, the WDST accounts for the absolute majority of the MWDRE.Secondly, in wet season when the WDST is satisfied, not only most of the annual incoming sediment can be transported downstream, but also the water demands for other river functions can be satisfied automatically, so that the MWDRE in wet season is identical to the WDST. Thirdly, in dry season, when the WDST is satisfied, the water demands for other river functions can also be satisfied, but the low sediment transport efficiency results in significant waste of water resources. According to these characteristics and aiming at decreasing sediment deposition in the riverbed and improving the utilization efficiency of water resources, hydrological engineering works can be used to regulate or control flow and sediment so that the sediment incoming in dry season can be accumulated and be transported downstream intensively and thus efficiently in wet season.

  19. Restoring Alternate Bar Sequences in Large Rivers: Flow, Sediment, and Elbow Room

    Science.gov (United States)

    Trush, W. J.; McBain, S. M.

    2006-12-01

    Large river management must rely on crucial premises that the river channel is a product of its watershed's hydrology and the space within which it moves, and that native plant and animal species have evolved with, and still depend on, the natural annual hydrograph. While interesting academically, these premises may appear to offer very limited utility as management tools, given few large rivers in the Pacific Northwest and elsewhere have escaped major hydrologic and geomorphic change. The opposite, however, is likely true. Without reconstructing and incorporating an historical perspective, large river restoration will fail. Healthy river ecosystems can be achieved without completely restoring the natural unregulated hydrology, sediment supply regime, and original migration corridor. Usually there is little choice. An historical perspective identifies crucial threshold streamflow, sediment, and corridor processes driving a healthy river ecosystem. Alternating point bar sequences are the building blocks of alluvial rivers that also function as the physical template for creating abundant, high quality habitat for fish, amphibians, and riparian plant. While alternating bars can be created with bulldozers, their evolution, longevity, and quality will endure only if key geomorphic and biological threshold processes are provided by naturally variable annual hydrographs. An historical perspective therefore must identify how unregulated annual hydrographs once created and fostered dynamic alternating bar sequences. Restoration practitioners must then devise ways to restore these processes while purposefully cheating Mother Nature of some of her flow, sediment, and corridor width (elbow room). Two commonly prescribed high flow releases, flushing flows and the bankfull discharge, address several geomorphic requirements yet neither, or the two combined, can restore and maintain alternating bar sequences. Higher flood peak magnitudes from winter floods and spring snowmelt

  20. Theoretical Study on the Confluence of Debris Flow and the Main River

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Because of the high momentum of debris flow,when it confluences with the Main River,the water level in the upstream of the conjunction point will increase and a portion of sediment will deposit in the con- junction area.The discharge of downstream will be less then the summation discharge of main river and side channel,and the density of downstream will be difference from both the density of the fluid of main river and tributary.Based on momentum theory,and with the transport coefficient and deposit coef...

  1. Mekong River flow and hydrological extremes under climate change

    NARCIS (Netherlands)

    Hoang, P.L.; Lauri, P.; Kummu, M.; Koponen, J.; Vliet, van M.T.H.; Supit, I.; Leemans, H.B.J.; Kabat, P.; Ludwig, F.

    2016-01-01

    Climate change poses critical threats to water related safety and sustainability in the Mekong River basin. Hydrological impact signals derived from CMIP3 climate change scenarios, however, are highly uncertain and largely ignore hydrological extremes. This paper provides one of the first hydrologic

  2. Satellite mapping of areas evaporating river and groundwater flows

    Science.gov (United States)

    van Dijk, Albert I. J. M.; Guerschman, Juan Pablo; Warren, Garth A.

    2010-05-01

    The 500m resolution CSIRO MODIS reflectance scaling evapotranspiration product (CMRSET) was combined with a gridded rainfall product to determine where in the landscape evapotranspiration exceeds rainfall over longer time periods, and by implication, where lateral inflows of river or groundwater are received and evaporated. This procedure produces valuable information for hydrological applications, including the spatial distribution of water use, the temporal distribution, and the absolute magnitude of (net) evaporation across the landscape. Practical uses that have been tested in Australia include evaluating the realism of simulated water use components in river models, attributing apparent losses from river reaches to processes and spatial locations, and identifying river and groundwater dependent ecosystems. Satellite observed inundation patterns have been used to separate surface water from groundwater use. Higher resolution Landsat imagery has been used for image enhancement, allowing smaller irrigation and wetland areas to be detected. Satellite-based land use classification helps to separate agricultural from environmental water use. The information produced is used in the Australian Water Resources Assessment (AWRA) system under development by CSIRO and the Australian Bureau of Meteorology to underpin operational delivery of water resources information.

  3. River flow and fish abundance in a South African estuary

    CSIR Research Space (South Africa)

    Whitfield, AK

    2003-06-01

    Full Text Available The ichthyofauna of the Thukela Estuary, a small (55 ha), shallow (<1_5 m) system on the KwaZulu-Natal coast (mean annual river runoff of 3865_106m3, from a large catchment of29 000km2, is seasonal: peak inputs occurring between November and March...

  4. Influence of River Bed Elevation Survey Configurations and Interpolation Methods on the Accuracy of LIDAR Dtm-Based River Flow Simulations

    Science.gov (United States)

    Santillan, J. R.; Serviano, J. L.; Makinano-Santillan, M.; Marqueso, J. T.

    2016-09-01

    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. The use of

  5. 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

  6. 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.

  7. 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...... to species indifferent to flow conditions. Filter feeders were partially replaced by collector/gatherers, which likely reduces the retention of organic matter, and thus the self-purification capacity of the river section. These shifts were associated with low discharge during summer, cascading into daily DO...

  8. On the Calibration of Multigene Genetic Programming to Simulate Low Flows in the Moselle River

    Directory of Open Access Journals (Sweden)

    Ali DANANDEH MEHR

    2016-12-01

    Full Text Available The aim of this paper is to calibrate a data-driven model to simulate Moselle River flows and compare the performance with three different hydrologic models from a previous study. For consistency a similar set up and error metric are used to evaluate the model results. Precipitation, potential evapotranspiration and streamflow from previous day have been used as inputs. Based on the calibration and validation results, the proposed multigene genetic programming model is the best performing model among four models. The timing and the magnitude of extreme low flow events could be captured even when we use root mean squared error as the objective function for model calibration. Although the model is developed and calibrated for Moselle River flows, the multigene genetic algorithm offers a great opportunity for hydrologic prediction and forecast problems in the river basins with scarce data issues.

  9. A water balance model to estimate flow through the Old and Middle River corridor

    Science.gov (United States)

    Andrews, Stephen W.; Gross, Edward S.; Hutton, Paul H.

    2016-01-01

    We applied a water balance model to predict tidally averaged (subtidal) flows through the Old River and Middle River corridor in the Sacramento–San Joaquin Delta. We reviewed the dynamics that govern subtidal flows and water levels and adopted a simplified representation. In this water balance approach, we estimated ungaged flows as linear functions of known (or specified) flows. We assumed that subtidal storage within the control volume varies because of fortnightly variation in subtidal water level, Delta inflow, and barometric pressure. The water balance model effectively predicts subtidal flows and approaches the accuracy of a 1–D Delta hydrodynamic model. We explore the potential to improve the approach by representing more complex dynamics and identify possible future improvements.

  10. 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.

  11. Optimizing the operation of the Qingshitan Reservoir in the Lijiang River for multiple human interests and quasi-natural flow maintenance

    Institute of Scientific and Technical Information of China (English)

    Qiuwen Chen; Duan Chen; Ruiguang Han; Ruonan Li; Jinfeng Ma; Koen Blanckaert

    2012-01-01

    For reservoir operation,maintaining a quasi-natural flow regime can benefit river ecosystems,but may sacrifice human interests.This study took the Qingshitan Reservoir in the Lijiang River as a case,and developed an optimization model to explore a trade-off solution between social-economic interests and nature flow maintenance on a monthly base.The objective function considered irrigation,cruise navigation and water supply aspects.An index of flow alteration degree was proposed to measure the difference between the regulated discharge and the natural flow.The index was then used as an additional constraint in the model besides the conventional constraints on reservoir safety.During model solving,different criteria were applied to the index,representing various degrees of alteration of the natural flow regime in the river.Through the model,a relationship between social-economic interests and flow alteration degree was established.Finally,a trade-off solution of the reservoir operation was defined that led to a favorable social-economic benefit at an acceptable alteration of the natural flow.

  12. The influence of three dimensional dunes on river flows and fluxes

    Science.gov (United States)

    Hardy, R. J.; Parsons, D. R.; Ockelford, A.; Ashworth, P. J.; Reesink, A.; Best, J.

    2015-12-01

    Fluvial systems in large river basins experience temporal variations in flow discharge, which creates unsteady changes in the flow field and sediment fluxes. The sediment-water interface responds and organizes to these changes over a wide range of spatial and temporal scales, primarily through adjustment of a variety of bed roughness elements. These roughness elements are the key component of overall flow resistance and the magnitude of their form drag significantly influences river stage levels for given discharge and determines the state and functioning of river systems and sediment fluxes. Here we present three dimensional numerically predicted flow results to demonstrate the importance of complex morphology on flow and sediment fluxes. Model boundary conditions and validation data were taken from two sources. Initially, they were collected from a field campaign on a 1.5 by 0.3 km stretch of the Mississippi near Alton, Illinois. Secondly, a series of flume experiments were undertaken that applied unsteady hydraulic conditions to generate a series of quasi-equilibrium three dimensional bed forms, which were scaled on the data collected in the field. The numerical flow results show that superimposed bed forms can cause changes in the nature of the classical separated flow region in particularly the number of locations where vortices are shed and the point of flow reattachment, which may be important for sediment flux dynamics during bed form adjustment.

  13. Explaining and forecasting interannual variability in the flow of the Nile River

    Directory of Open Access Journals (Sweden)

    M. S. Siam

    2014-05-01

    Full Text Available The natural interannual variability in the flow of Nile River had a significant impact on the ancient civilizations and cultures that flourished on the banks of the river. This is evident from stories in the Bible and Koran, and from the numerous Nilometers discovered near ancient temples. Here, we analyze extensive data sets collected during the 20th century and define four modes of natural variability in the flow of Nile River, identifying a new significant potential for improving predictability of floods and droughts. Previous studies have identified a significant teleconnection between the Nile flow and the Eastern Pacific Ocean. El Niño–Southern Oscillation (ENSO explains about 25% of the interannual variability in the Nile flow. Here, we identify, for the first time, a region in the southern Indian Ocean with similarly strong teleconnection to the Nile flow. Sea Surface Temperature (SST in the region (50–80° E and 25–35° S explains 28% of the interannual variability in the Nile flow. During those years with anomalous SST conditions in both Oceans, we estimate that indices of the SSTs in the Pacific and Indian Oceans can collectively explain up to 84% of the interannual variability in the flow of Nile. Building on these findings, we use classical Bayesian theorem to develop a new hybrid forecasting algorithm that predicts the Nile flow based on global models predictions of indices of the SST in the Eastern Pacific and Southern Indian Oceans.

  14. Improved higher lead time river flow forecasts using sequential neural network with error updating

    Directory of Open Access Journals (Sweden)

    Prakash Om

    2014-03-01

    Full Text Available This paper presents a novel framework to use artificial neural network (ANN for accurate forecasting of river flows at higher lead times. The proposed model, termed as sequential ANN (SANN, is based on the heuristic that a mechanism that provides an accurate representation of physical condition of the basin at the time of forecast, in terms of input information to ANNs at higher lead time, helps improve the forecast accuracy. In SANN, a series of ANNs are connected sequentially to extend the lead time of forecast, each of them taking a forecast value from an immediate preceding network as input. The output of each network is modified by adding an expected value of error so that the residual variance of the forecast series is minimized. The applicability of SANN in hydrological forecasting is illustrated through three case examples: a hypothetical time series, daily river flow forecasting of Kentucky River, USA and hourly river flow forecasting of Kolar River, India. The results demonstrate that SANN is capable of providing accurate forecasts up to 8 steps ahead. A very close fit (>94% efficiency was obtained between computed and observed flows up to 1 hour in advance for all the cases, and the deterioration in fit was not significant as the forecast lead time increased (92% at 8 steps ahead. The results show that SANN performs much better than traditional ANN models in extending the forecast lead time, suggesting that it can be effectively employed in developing flood management measures.

  15. Quantifying the effects of tidal amplitude on river delta network flow partitioning

    Science.gov (United States)

    Hiatt, M. R.; Sendrowski, A.; Passalacqua, P.

    2014-12-01

    Deltas are generally classified as river-, tide-, or wave-dominated systems, but the influences of all environmental forces cannot be ignored when fully addressing the dynamics of the system. For example, in river-dominated deltas, river flow from the feeder channel acts as the primary driver of dynamics within the system by delivering water, sediment, and nutrients through the distributary channels, but tides and waves may affect their allocation within the network. There has been work on the asymmetry of environmental fluxes at bifurcations, but relatively few studies exist on the water partitioning at the network scale. Understanding the network and environmental effects on the flux of water, sediment, and nutrients would benefit delta restoration projects and management practices. In this study, we investigate the allocation of water flow among the five major distributary channels at Wax Lake Delta (WLD), a micro-tidal river-dominated delta in coastal Louisiana, and the effects of tidal amplitude on distributary channel discharges. We collect and compare discharge results from acoustic Doppler current profiler (ADCP) velocity transects between spring and neap tide and between falling and rising tide. The results show that discharges increased from spring to neap tide and from rising to falling tide. We investigate the spatial gradients of tidal influence within the network and validate hydraulic geometry relations for tidally influenced channels. Our results give insight into the control of network structure on flow partitioning and show the degree of tidal influence on channel flow in the river-dominated WLD.

  16. River flow forecasting with Artificial Neural Networks using satellite observed precipitation pre-processed with flow length and travel time information: case study of the Ganges river basin

    Directory of Open Access Journals (Sweden)

    M. K. Akhtar

    2009-04-01

    Full Text Available This paper explores the use of flow length and travel time as a pre-processing step for incorporating spatial precipitation information into Artificial Neural Network (ANN models used for river flow forecasting. Spatially distributed precipitation is commonly required when modelling large basins, and it is usually incorporated in distributed physically-based hydrological modelling approaches. However, these modelling approaches are recognised to be quite complex and expensive, especially due to the data collection of multiple inputs and parameters, which vary in space and time. On the other hand, ANN models for flow forecasting are frequently developed only with precipitation and discharge as inputs, usually without taking into consideration the spatial variability of precipitation. Full inclusion of spatially distributed inputs into ANN models still leads to a complex computational process that may not give acceptable results. Therefore, here we present an analysis of the flow length and travel time as a basis for pre-processing remotely sensed (satellite rainfall data. This pre-processed rainfall is used together with local stream flow measurements of previous days as input to ANN models. The case study for this modelling approach is the Ganges river basin. A comparative analysis of multiple ANN models with different hydrological pre-processing is presented. The ANN showed its ability to forecast discharges 3-days ahead with an acceptable accuracy. Within this forecast horizon, the influence of the pre-processed rainfall is marginal, because of dominant influence of strongly auto-correlated discharge inputs. For forecast horizons of 7 to 10 days, the influence of the pre-processed rainfall is noticeable, although the overall model performance deteriorates. The incorporation of remote sensing data of spatially distributed precipitation information as pre-processing step showed to be a promising alternative for the setting-up of ANN models for

  17. Flow regulation effects on the hydrogeochemistry of the hyporheic zone in boreal rivers.

    Science.gov (United States)

    Siergieiev, D; Widerlund, A; Ingri, J; Lundberg, A; Öhlander, B

    2014-11-15

    River-aquifer interfaces are essential for ecosystem functioning in terms of nutrient exchange and biological habitat, but are greatly threatened world-wide. This study examined geochemical aspects of river-aquifer interaction in one regulated and one unregulated boreal river in Northern Sweden to determine whether the geochemical functioning of the hyporheic zone is affected by hydrological alterations, e.g. regulated river discharge and river-aquifer connectivity. In the unregulated Kalix River, the hyporheic pore water was well-oxygenated with orthogonal fluxes (≈0.6-0.7 m d(-1)) and acted as a sink for Fe, Mn, Al, NH4, and Ca, with fractional losses of 95%, 92%, 45%, 31%, and 15%, respectively. A corresponding elevation in the concentrations of these elements in the hyporheic sediment was observed, with higher saturation indices of Fe-, Mn-, and Al-bearing secondary minerals in hyporheic waters. In the regulated Lule River, hydraulic connectivity at the river-aquifer interface was altered by the presence of a clogging layer (0.04 m d(-1)). In addition, the river discharge oscillated daily, severely reducing exchange flows across the riverbed (<0.01 m d(-1)). As a result, the hyporheic pore water was suboxic, with elevated concentrations of filtered Fe and Mn (fractional increases of ≈3700% and ≈2500%, respectively) and other solutes (NH4, Si, S, Ca). A conceptual model revealed functional differences between geochemical features of the hyporheic zone of regulated and unregulated rivers. Overall, the results showed that hyporheic processes are altered along regulated rivers, with resulting impacts on the geochemistry of riverine, riparian and related marine ecosystems.

  18. The effect of channel shape, bed morphology, and shipwrecks on flow velocities in the Upper St. Clair River

    Science.gov (United States)

    Czuba, Jonathan A.; Oberg, Kevin; Best, Jim; Parsons, Daniel R.

    2009-01-01

    In the Great Lakes of North America, the St. Clair River is the major outlet of Lake Huron and conveys water to Lake St. Clair which then flows to Lake Erie. One major topic of interest is morphological change in the St. Clair River and its impact on water levels in the Upper Great Lakes and connecting channel flows. A combined multibeam echosounder (MBES) bathymetric survey and acoustic Doppler current profiler (ADCP) flow survey of the outlet of Lake Huron and the Upper St. Clair River was conducted July 21 – 25, 2008. This paper presents how channel morphology and shipwrecks affect the flow in the Upper St. Clair River. The river is most constricted at the Blue Water Bridge near Port Huron, Michigan, with water velocities over 2 ms-1 for a flow of 5,200 m3s-1. Downstream of this constriction, the river flows around a bend and expands creating a large recirculation zone along the left bank due to flow separation. This recirculation zone reduces the effective channel width, and thus increases flow velocities to over 2 ms-1 in this region. The surveys reveal several shipwrecks on the bed of the St. Clair River, which possess distinct wakes in their flow velocity downstream of the wrecks. The constriction and expansion of the channel, combined with forcing of the flow by bed topography, initiates channel-scale secondary flow, creating streamwise vortices that maintain coherence downstream over a distance of several channel widths.

  19. Hydroecology of river plankton: the role of variability in channel flow

    Science.gov (United States)

    Reynolds, C. S.

    2000-10-01

    The mechanisms by which entrained planktonic organisms survive in river systems, despite an inexorable, unidirectional downstream transport, are revisited. The importance of channel retentivity to downstream population recruitment is emphasized. The aggregated dead-zone (ADZ) model is shown to be adequate to explain downstream recruitment of a growing population. The ADZ behaviour is more prevalent in sinuous, low-gradient reaches than in other parts of the river. Plankton selection and dynamics relate conspicuously to flow at higher discharges but other environmental features are important at low flows. Discharge variability is pivotal to the opportunities for potamoplankton to thrive.

  20. Temporal Variability of Monthly Daily Extreme Water Levels in the St. Lawrence River at the Sorel Station from 1912 to 2010

    OpenAIRE

    2014-01-01

    Although climate models predict that the impacts of climate change on the temporal variability of water levels in the St. Lawrence River will be seasonally-dependent, such a seasonal effect on the current variability of extreme water levels has never been analyzed. To address this, we analyzed the temporal variability of three hydrological variables (monthly daily maximums and minimums, as well as their ratio) of water levels in the St. Lawrence River measured at the Sorel station since 1912,...

  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. Flow regulation and river fragmentation in large basins due to global dam development (Invited)

    Science.gov (United States)

    Grill, G. O.; Lehner, B.

    2013-12-01

    Dam construction has recently received new interest as an alternative and renewable source of energy, especially in developing countries, and as a means to provide water security in regions with naturally variable water flows. On the other hand, the negative effects from increased fragmentation of the world's large rivers through hydropower and irrigation dams is a matter of great concern for ecologists and conservationists. The main negative effects of dams result from their role as a barrier for migratory fish species, as well as the alteration of the natural flow regime owing to artificial water release schedules. While the trade-offs between these antagonistic effects are usually assessed locally by conducting environmental impact assessments at and in the vicinity of the construction site, the cumulative effects of multiple dams located in the same basin are generally neglected in such plans. To address the cumulative effects at the scale of large river networks, we developed a new impact assessment approach by combining state-of-the-art global scale hydrographic (HydroSHEDS) and hydrological models (WaterGAP) with a river routing scheme (HydroROUT). This combination enables modelers to simulate scenarios for historic, current and future conditions that allow for comparisons between the large river basins of the world. We derive indices that can describe the relative impact of individual and multiple dams regarding flow alteration and habitat fragmentation at a global scale. Our model also allows for the application of tailor-made weighting schemes to include information of eco-hydrological classifications, as well as species richness and diversity. Furthermore, we include natural barriers such as waterfalls, and examine their effect on river network connectivity. Results for the Greater Mekong Region show that ecosystem connectivity and flow alteration are most strongly affected by dams located at the mainstream rivers, particularly for basins where the main

  3. 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.

  4. 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.

  5. A millennium-length reconstruction of Bear River stream flow, Utah

    Science.gov (United States)

    DeRose, R. J.; Bekker, M. F.; Wang, S.-Y.; Buckley, B. M.; Kjelgren, R. K.; Bardsley, T.; Rittenour, T. M.; Allen, E. B.

    2015-10-01

    The Bear River contributes more water to the eastern Great Basin than any other river system. It is also the most significant source of water for the burgeoning Wasatch Front metropolitan area in northern Utah. Despite its importance for water resources for the region's agricultural, urban, and wildlife needs, our understanding of the variability of Bear River's stream flow derives entirely from the short instrumental record (1943-2010). Here we present a 1200-year calibrated and verified tree-ring reconstruction of stream flow for the Bear River that explains 67% of the variance of the instrumental record over the period from 1943 to 2010. Furthermore, we developed this reconstruction from a species that is not typically used for dendroclimatology, Utah juniper (Juniperus osteosperma). We identify highly significant periodicity in our reconstruction at quasi-decadal (7-8 year), multi-decadal (30 year), and centennial (>50 years) scales. The latter half of the 20th century was found to be the 2nd wettest (∼40-year) period of the past 1200 years, while the first half of the 20th century marked the 4th driest period. The most severe period of reduced stream flow occurred during the Medieval Warm Period (ca. mid-1200s CE) and persisted for ∼70 years. Upper-level circulation anomalies suggest that atmospheric teleconnections originating in the western tropical Pacific are responsible for the delivery of precipitation to the Bear River watershed during the October-December (OND) season of the previous year. The Bear River flow was compared to recent reconstructions of the other tributaries to the Great Salt Lake (GSL) and the GSL level. Implications for water management could be drawn from the observation that the latter half of the 20th century was the 2nd wettest in 1200 years, and that management for future water supply should take into account the stream flow variability over the past millennium.

  6. Debris Flow Monitoring System and Observed Event in Taiwan: A Case Study at Aiyuzi River

    Institute of Scientific and Technical Information of China (English)

    HSIAO Taichung; LEE Bingjean; CHOU Tienyin; LIEN Huipain; CHANG Yinghuei

    2007-01-01

    Since 2002, the Soil and Water Conservation Bureau, which is responsible for the conservation and administrative management of hillside in Taiwan, has been cooperating with Feng Chia University. Together, they have successfully carried out the establishment and maintenance of 13 fixed debris flow monitoring stations over the island and 2 mobile debris flow monitoring stations. During July 2004, a powerful southwest air current brought by Mindulle Typhoon caused serious flood in central and southern Taiwan. This paper aims to describe the establishment of debris flow monitoring systems in Taiwan and the observation of the debris flow event during Mindulle Typhoon at Aiyuzi River in Shenmu Village, Nantou County by the monitoring station.

  7. A large-scale environmental flow experiment for riparian restoration in the Colorado River delta

    Science.gov (United States)

    Shafroth, Patrick B.; Schlatter, Karen; Gomez-Sapiens, Martha; Lundgren, Erick; Grabau, Matthew R.; Ramirez-Hernandez, Jorge; Rodriguez-Burgeueno, J. Eliana; Flessa, Karl W.

    2017-01-01

    Managing streamflow is a widely-advocated approach to provide conditions necessary for seed germination and seedling establishment of trees in the willow family (Salicaceae). Experimental flow releases to the Colorado River delta in 2014 had a primary objective of promoting seedling establishment of Fremont cottonwood (Populus fremontii) and Goodding's willow (Salix gooddingii). We assessed seed germination and seedling establishment of these taxa as well as the non-native tamarisk (Tamarix spp.) and native seepwillow shrubs (Baccharis spp.) in the context of seedling requirements and active land management (land grading, vegetation removal) at 23 study sites along 87 river km. In the absence of associated active land management, experimental flows to the Colorado River delta were minimally successful at promoting establishment of new woody riparian seedlings, except for non-native Tamarix. Our results suggest that the primary factors contributing to low seedling establishment varied across space, but included low or no seed availability in some locations for some taxa, insufficient soil moisture availability during the growing season indicated by deep groundwater tables, and competition from adjacent vegetation (and, conversely, availability of bare ground). Active land management to create bare ground and favorable land grades contributed to significantly higher rates of Salicaceae seedling establishment in a river reach with high groundwater tables. Our results provide insights that can inform future environmental flow deliveries to the Colorado River delta and its ecosystems and other similar efforts to restore Salicaceae taxa around the world.

  8. Detecting impact of land use change on river flow, sediment and nutrient through distributed hydrological simulation

    Science.gov (United States)

    Lihua, T.; Yang, D.

    2009-12-01

    Change in land use has significant impact on river flow, sediment and nutrient losses of the watershed. This paper presents a process-based hydrological model, GBNP (Geomorphology-Based Non-point source Pollution model), coupling erosion, sediment and nutrient processes into the distributed hydrological model GBHM (Geomorphology-Based Hydrological Model). The proposed model is able to take into account the physical processes of non-point source pollution with rainfall-runoff, soil erosion, sediment transportation, pollutant flushing off from soil and transportation in river. Moreover the calculation unit division is based on geomorphological features of the watershed. Because of the distributed depiction of landscape condition and physically-based description of all processes, the model can be used to detect the hydrological responses of runoff, erosion and non-point source pollution under changing condition. After calibration and validation, the GBNP model is applied to the Chaobai River basin in northern China to detect the impact of land use change on runoff, sediment and pollutant loads. The results showed that the land use change reduced the river flow, sediment and nutrient losses from 1980 to 2005, moreover the land use change has different impacts on river flow, sediment and nutrient loads.

  9. 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.

  10. 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.

  11. CIS-Based Risk Assessment of Debris Flow Disasters in the Upper Reach of Yangtze River

    Institute of Scientific and Technical Information of China (English)

    HAN Yongshun; LIU Hongjiang; ZHONG Dunlun; SU Fenghuan; LI Chaokui

    2007-01-01

    This paper discussed theory and methodologies of debris-flow risk assessment and established an implementation process according to indicators of debris-flow hazard degree, vulnerability, risk degree, etc. Among these methodologies, historical and potential hazard degree was comprehensively considered into hazard assessment and hazard index was presented to indicate the debris-flow hazard degree. Regarding debris-flow vulnerability assessment, its statistical data and calculating procedure were based on the hazard-degree regionalization instead of administrative divisions, which improved the assessing scientificity and precision. These quantitative methodologies integrated with Geography Information System (GIS) were applied to the risk assessment of debris flows in the upper reach of Yangtze River. Its results were in substantial agreement on investigation data and the actual distribution of debris flows, which showed that these principles and methodologies were reasonable and feasible and can provide basis or reference for debris-flow risk assessment and disaster management.

  12. 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.

  13. Effect of no-flow in the Lower Yellow River on groundwater formation and usage in areas along the banks

    Institute of Scientific and Technical Information of China (English)

    Jianfeng CAO; Xueyan YE; Kaijun WANG; Jiyi JIANG

    2008-01-01

    Frequent flow cutoff has a serious effect on the eco-environment of the region along the Lower Yellow River. The authors study the impact on lateral seepage quantity and groundwater cycling caused by cutoff of the Yellow River and compare it with that of the year 1999 through the numerical simulation model of ground-water flow system of the affected zone. The lateral seepage quantity decreased 53.8% on flow cutoff stage from Huayuankou to the river entrance and breaking time of 300 d. The lateral seepage quantity will decrease 46.3% if flow cutoff is from Jiahetan to the river entrance and breaking time is 300 d, and it will decrease 75.2% if flow cutoff occurs throughout the year. The lateral seepage quantity will decrease 19.8% if flow cutoff is from Luokou to the river entrance and breaking time is 300 d, and it will decrease 25.1% if flow cutoff occurs throughout the year. The lateral seepage quantity will decrease 4.7% if flow cutoff is from Lijin to the river entrance and flow cutoff occurs throughout the year. Flow cutoff of the Yellow River has a minor effect on the shape of ground-water flow domain of the affected zone. Thus, the bound-ary condition of the shallow groundwater system will not change. Although flow cutoffhas a major influence on the riverside source fields in the Lower Yellow River, it will not have a significant effect on groundwater resources macroscopically in the affected zone of the Yellow River due to its large storage capacity.

  14. 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.

  15. Numerical study of junction-angle effects on flow pattern in a river ...

    African Journals Online (AJOL)

    2016-01-01

    Jan 1, 2016 ... This complexity is not only because of their turbulence and intense ... The use of numerical models for simulating the flow in river junctions has ..... longitudinal velocity profiles in different sections of the main channel is shown ...

  16. A review of the status, research opportunities and future of large-scale river flow archives

    NARCIS (Netherlands)

    Hannah, D.M.; Demuth, S.; Lanen, van H.A.J.; Looser, U.; Prudhomme, C.; Rees, G.; Stahl, K.; Tallaksen, L.M.

    2010-01-01

    Large-scale river flow archives hold vital data to identify and understand the changing water cycle, to underpin modelling of future regional and global hydrology, and to inform water resource assessment and decision making. Notable examples of such datasets include that held by the WMO Global Runof

  17. River Flow Control on the Phytoplankton Dynamics of Chesapeake Bay

    Institute of Scientific and Technical Information of China (English)

    YU Qingyun; WANG You; TANG Xuexi; LI Ming

    2013-01-01

    Recent observations support an emerging paradigm that climate variability dominates nutrient enrichment in costal ecosystems,which can explain seasonal and inter-annual variability of phytoplankton community composition,biomass (Chl-a),and primary production (PP).In this paper,we combined observation and modeling to investigate the regulation of phytoplankton dynamics in Chesapeake Bay.The year we chose is 1996 that has high river runoff and is usually called a ‘wet year’.A 3-D physical-biogeochemical model based on ROMS was developed to simulate the seasonal cycle and the regional distributions of phytoplankton biomass and primary production in Chesapeake Bay.Based on the model results,NO3 presents a strong contrast to the river nitrate load during spring and the highest concentration in the bay reaches around 80mmol N m3.Compared with the normal year,phytoplankton bloom in spring of 1996 appears in lower latitudes with a higher concentration.Quantitative comparison between the modeled and observed seasonal averaged dissolved inorganic nitrogen concentrations shows that the model produces reliable results.The correlation coefficient r2 for all quantities exceeds 0.95,and the skill parameter for the four seasons is all above 0.95.

  18. Climate or land-use change? Complexities in the attribution of trends in river flow records

    Science.gov (United States)

    Harrigan, S.; Murphy, C.; Noone, S.; Wilby, R. L.; Hall, J.

    2012-12-01

    Uncertainty associated with projections of regional climate change and the challenge of developing adaptation responses are heightening interest in trend detection from observations. In many studies, attribution of detected trends in river flow has been based on the assessment of correlations with large scale modes of climate variability, with too little emphasis being placed on understanding non-climatic changes within the catchment. The River Boyne in Ireland has been cited as exhibiting a climate driven increase in river flows associated with a shift towards positive anomalies in the North Atlantic Oscillation Index (NAOI) from the mid to late 1970s. However, metadata suggests that the catchment was subjected to extensive arterial drainage during the period 1969-86. This was installed to improve land drainage and reduce the frequency/ extent of overland flooding, particularly through river straightening and channel deepening, complicating the attribution of change linked to climatic drivers. This study uses river flow records from the pre-drainage period along with meteorological data to calibrate conceptual rainfall runoff models in order to reconstruct continuous flow series spanning the pre- and post-drainage eras. Model parameter and structure uncertainties were explored via a suite of conceptually and structurally diverse models. Archival rainfall records dating from the late 1800s were used to further extend the flow series. Reconstructed flows are analyzed for both monotonic and step changes using a variety of statistical tests. Emphasis is placed on a moving windows approach to assess the evolution of trends throughout the reconstructed series. Our results show that the variability of trends (direction, magnitude and significance) is heavily dependent on the choice of record start and end dates. Rather than being associated with a change point in the NAOI, the mid 1970s step change is shown to coincide with the documented changes in arterial drainage

  19. 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

  20. 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.

  1. Reservoir Operations and Flow Modeling to Support Decision Making in the Delaware River Basin

    Science.gov (United States)

    Quinodoz, H. A.

    2006-12-01

    About five percent of the US population depends on the waters from the Delaware River Basin for its water supply, including New York City and Philadelphia. Water management in the basin is governed by a compact signed in 1961 by the four basin states and the federal government. The compact created the Delaware River Basin Commission (DRBC) and gave it broad powers to plan, regulate, and manage the development of the basin water resources. The compact also recognized a pre-existing (1954) U.S. Supreme Court Decree that grants the City of New York the right to export up to 800 million gallons per day out of the basin, provided that a prescribed minimum flow is met at Montague, New Jersey for the use of the lower-basin states. The Delaware River Basin Compact also allows the DRBC to adjust the releases and diversions under the Decree, subject to the unanimous consent of the decree parties. This mechanism has been used several times over the last 30 years, to implement and modify rules governing drought operations, instream flows, minimum flow targets, and control of salinity intrusion. In every case, decision makers have relied upon extensive modeling of alternative proposals, using a basin-wide daily flow model. Often, stakeholders have modified and used the same model to test and refine their proposals prior to consideration by the decision makers. The flow model has been modified over the years, to simulate new features and processes in a river system partially controlled by more than ten reservoirs. The flow model has proved to be an adaptable tool, able to simulate the dynamics of a complex system driven by conflicting objectives. This presentation reviews the characteristics of the daily flow model in its current form, discuss how model simulations are used to inform the decision-making process, and provide a case study of a recent modification of the system-wide drought operating plan.

  2. Geomorphic response of rivers to glacial retreat and increasing peak flows downstream from Mount Rainier, Washington

    Science.gov (United States)

    Czuba, J. A.; Barnas, C. R.; Magirl, C. S.; Voss, F. D.

    2010-12-01

    On Mount Rainier, Washington, the National Park Service has documented widespread aggradation of as much as 10 m since the early 20th century, of rivers draining the glaciated stratovolcano. This rapid sedimentation appears to be related to glacial retreat and also may be a function of the increased magnitude and timing of peak flows that mobilize and transport sediment. We are conducting an assessment of the Puget Lowland rivers that drain Mount Rainier, 25-100 km downstream from the park boundary, to document the geomorphic response of the downstream reaches given the widespread aggradation upstream. These downstream reaches provide critical aquatic habitat for spawning and rearing of several species of salmonids, including endangered Chinook salmon and steelhead. Fluvial sedimentation can have both deleterious and beneficial effects on aquatic habitat depending on sediment particle size, river slope and width, and river management. To date, our work shows sedimentation of as much as 2 m between 1984 and 2009 in these lowland rivers. Aggradation rates that were calculated by comparing channel change at 156 cross sections, ranged between 4.8 and 9.1 cm/yr in reaches where rivers exit the mountain front and enter the lowland. Analysis of streamflow-gaging station data from throughout the watersheds draining Mount Rainier show rapid incision and aggradation, suggesting pulses of coarse-grained bedload may be moving down the mountainous rivers as kinetic waves. Preliminary results, however, seem to indicate that the rivers in the Puget Lowland have not yet experienced significant widespread sedimentation directly related to glacial retreat. Estimating the time of arrival of mobilized alluvium is a critical need for resource managers given the potential effects of sedimentation on river flood-conveyance capacity, fish habitat, and estuarine wetlands.

  3. 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.

  4. "An assessment of changes the Danube river flow along the Iron Gate gorge for XXI century

    Science.gov (United States)

    Adamovic, M.

    2009-04-01

    . The second approach, which is more typically meteorological, relies on the calculation of the E for the time frame 2071-2100 by using the previous coefficients. On the basis of the assessment of climate units in the XXI century and with help of the established relationships, the water flow of Danube river and runoff depth were defined for this century. The results according to this model, show that the river flow of the Danube, in this part of its basin, will decrease over 50% with a great consequences to the dams Iron Gate I and II, their accumulations and ecosystems. Furthermore, if we take into account predictions made by IPCC which say that the south-east Europe will face temperature growth of 0.2 degrees in the next two decades for the range of SRES scenarios, makes the whole problem much more complicated and alarming. Results also show that precipitation's peak in the early summer months and in November, which gives more often a secondary maximum, is the typical feature of the observed climatology of the precipitation of the Danubian region. The minima of precipitation are also clustered in two periods of the year, namely February and the summer months. The latter minimum is a signature of the influence of the typical Mediterranean summer. As an output of all that, as has been mentioned above, this part of Europe will face with worse conditions (high temperatures, droughts) in a region already vulnerable to climate variability, than those of 2003 when Europe was hit by an incredible heat wave. Reductions of water availability, hydropower potential, summer tourism and general crop productivity are certainly appearances which are to be expected in this area. In turns of the results, one question has arisen: Should we adapt to the climate change, or should we mitigate it? Maybe, the answer is in mitigation while doing adaptation. According to the Danube river in this region, the works for fighting reservoir related bank erosion in order to preserve the dam and

  5. Seasonal invasion dynamics in a spatially heterogeneous river with fluctuating flows.

    Science.gov (United States)

    Jin, Yu; Hilker, Frank M; Steffler, Peter M; Lewis, Mark A

    2014-07-01

    A key problem in environmental flow assessment is the explicit linking of the flow regime with ecological dynamics. We present a hybrid modeling approach to couple hydrodynamic and biological processes, focusing on the combined impact of spatial heterogeneity and temporal variability on population dynamics. Studying periodically alternating pool-riffle rivers that are subjected to seasonally varying flows, we obtain an invasion ratchet mechanism. We analyze the ratchet process for a caricature model and a hybrid physical-biological model. The water depth and current are derived from a hydrodynamic equation for variable stream bed water flows and these quantities feed into a reaction-diffusion-advection model that governs population dynamics of a river species. We establish the existence of spreading speeds and the invasion ratchet phenomenon, using a mixture of mathematical approximations and numerical computations. Finally, we illustrate the invasion ratchet phenomenon in a spatially two-dimensional hydraulic simulation model of a meandering river structure. Our hybrid modeling approach strengthens the ecological component of stream hydraulics and allows us to gain a mechanistic understanding as to how flow patterns affect population survival.

  6. A STATISTICAL AND HYDROLOGICAL ANALYSIS OF THE MAXIMUM FLOW IN THE TERPEZITA RIVER DRAINAGE BASIN

    Directory of Open Access Journals (Sweden)

    GABRIELA ADINA MOROŞANU

    2015-03-01

    Full Text Available A statistical and hydrological analysis of the maximum flow in the Terpezița river drainage basin. Starting from the idea that hydrological and hydrometeorological parameters have a statistical existence over time and a spatial distribution that can be represented by an interaction between the mathematical and geographical elements, the present paper aims to analyze the relationship between maximum flows, hourly rains, flow coefficients and concentration times of the Terpezita Basin. This is the second-largest sub-basin (182km2 in the basin of Desnatui, which is located in the SW of Romania and is a first degree tributary of the Danube. The assessment of the concentration time, which involves the sizes of the liquid flow and specific liquid flow, was attained according to the physical and geographical characteristics of the basin. Thus taking into account the homogenous character from this point of view and the existence of statistically established hydrological and pluviometric background, we could outline the behavior of Terpezița River Basin during the extreme hydro-meteorological events. The documentation was completed through an exemplification of previously calculated results, using observations and measurements of the river bed in the vicinity of Terpezita village and processing the values that resulted from the hydro-graph of the 2005 flash-flood.

  7. Effective discharge for sediment transport: the sorting role of river flow regimes

    Science.gov (United States)

    Basso, Stefano; Sprocati, Riccardo; Frascati, Alessandro; Marani, Marco; Schirmer, Mario; Botter, Gianluca

    2016-04-01

    The effective discharge is a key concept in geomorphology, river engineering and restoration. It is used to design the most stable channel configuration, to estimate sedimentation rate and lifespan of reservoirs and to characterize the hydrologic forcing in models studying long-term evolution of rivers. Previous empirical, theoretical and numerical studies found the effective discharge to be affected by climate, landscape and river morphology, type of transport (dissolved, suspended or bedload), and by streamflow variability. However, the heterogeneity of values observed for the effective discharge challenges a clear understanding of its pivotal drivers, and a consistent framework which explains observations carried out in different catchments and geographic areas is still lacking. This work relates the observed diversity of effective discharge values to the underlying heterogeneity of river flow regimes. The effective ratio (i.e. the ratio between effective discharge and mean streamflow) is derived as a function of the empirical exponent of the sediment rating curve and the streamflow variability, resulting from climatic and landscape drivers. The proposed analytic expression helps to disentangle hydrologic and landscape controls on the effective discharge, and highlights distinct effective ratios of persistent and erratic hydrologic regimes (respectively characterized by low and high flow variability), attributable to intrinsically different streamflow dynamics. The framework captures observed values of effective discharge for suspended sediment transport in a set of catchments of the continental United States, and may allow for first-order estimates of effective discharge in rivers belonging to different climatic regions.

  8. 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.

  9. FLUVIAL PROCESSES AND SEDIMENT SCOUR RATE OF THE YELLOW RIVER UNDER ACTION OF UNSTEADY FLOWS

    Institute of Scientific and Technical Information of China (English)

    Yong-Nian XU; Zhi-Yong LIANG; Zhao-Yin WANG

    2001-01-01

    Riverbed scour of the main channel by floods in the Yellow River and its tributaries was investigated, including scour by hyper-concentrated floods. Flood scour usually causes variation of river cross-sections in a way similar to that occured when the sediment inflow is less than the sediment-laden capacity. Scour rate equation for the main channel derived based on the momentum and continuous equations was verified by field data. This equation indicates that unsteady flow scour rate is proportional to the flow density, the velocity of the flood peak, the rising rate of flow discharge per unit width, and so on. The Maximum scour depth after a flood could be predicted by the scour rate equation proposed in this paper.

  10. Classification of Hydrological time series using Probabilistic Neural Network for River Flow Modeling by RBF Networks

    Science.gov (United States)

    Abghari, H.; van de Giesen, N.; Mahdavi, M.; Salajegheh, A.

    2009-04-01

    Artificial intelligence modeling of nonstationary rainfall-runoff has some restrictions in simulation accuracy due to the complexity and nonlinearity of training patterns. Preprocessing of trainings dataset could determine homogeneity of rainfall-runoff patterns before modeling. In this presentation, a new hybrid model of Artificial Intelligence in conjunction with clustering is introduced and applied to flow prediction. Simulation of Nazloochaei river flow in North-West Iran was the case used for development of a PNN-RBF model. PNN classify a training dataset in two groups based on Parezen theory using unsupervised classification. Subsequently each data group is used to train and test two RBF networks and the results are compared to the application of all data in a RBF network without classification. Results show that classification of rainfall-runoff patterns using PNN and prediction of runoff with RBF increase prediction precise of networks. Keywords: Probabilistic Neural Network, Radial Base Function Neural Network, Parezen theory, River Flow Prediction

  11. River bedform inception by flow unsteadiness: A modal and nonmodal analysis

    Science.gov (United States)

    Caruso, Alice; Vesipa, Riccardo; Camporeale, Carlo; Ridolfi, Luca; Schmid, Peter J.

    2016-05-01

    River bedforms arise as a result of morphological instabilities of the stream-sediment interface. Dunes and antidunes constitute the most typical patterns, and their occurrence and dynamics are relevant for a number of engineering and environmental applications. Although flow variability is a typical feature of all rivers, the bedform-triggering morphological instabilities have generally been studied under the assumption of a constant flow rate. In order to partially address this shortcoming, we here discuss the influence of (periodic) flow unsteadiness on bedform inception. To this end, our recent one-dimensional validated model coupling Dressler's equations with a refined mechanistic sediment transport formulation is adopted, and both the asymptotic and transient dynamics are investigated by modal and nonmodal analyses.

  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. Flow and suspended-sediment transport in the Colorado River near National Canyon

    Science.gov (United States)

    Smith, J. Dungan

    Point measurements of flow speed and suspended-sand concentration were made from a cableway 293-km downstream from Glen Canyon Dam during the 1996 controlled flood. The data demonstrate a systematic fining of the suspended load in the Colorado River, a reduction in near-bed sand concentration with time, and a strong secondary circulation that very effectively transported suspended sand toward the channel margins. In the center of the river, the primary flow was well represented by steady, horizontally uniform flow theory, with a shear velocity of 0.081 m/s and a sand grain related roughness parameter of 4.5·1O-6 m; at the channel margins the primary flow exhibited a distinct internal boundary layer with a shear velocity of approximately 0.081 m/s and an outer boundary layer with a shear velocity of approximately twice that value. The secondary circulation was caused by long wavelength irregularities in the rockfall-produced sloping banks of the approximately trapezoidal channel. The primary flow was forced upward and toward the river center by these topographic features causing a fully 3-dimensional circulation. The upward forced vertical velocities apparently interacted with turbulence in the primary flow to produce boils. Consequently, the upwelling zone degraded to an irregular, bank-parallel boil line. Downwelling occurred over a broad region in the center of the river, but also was concentrated along well-defined convergence zones over which woody debris concentrated. This secondary circulation was very effective in transporting suspended sand toward the channel margins at the bottom, then lifting it in the boils and depositing it inshore of the boil line on the riverbanks.

  14. Simulated effects of dam removal on water temperatures along the Klamath River, Oregon and California, using 2010 Biological Opinion flow requirements

    Science.gov (United States)

    Risley, John C.; Brewer, Scott J.; Perry, Russell W.

    2012-01-01

    Computer model simulations were run to determine the effects of dam removal on water temperatures along the Klamath River, located in south-central Oregon and northern California, using flow requirements defined in the 2010 Biological Opinion of the National Marine Fisheries Service. A one-dimensional, daily averaged water temperature model (River Basin Model-10) developed by the U.S. Environmental Protection Agency Region 10, Seattle, Washington, was used in the analysis. This model had earlier been configured and calibrated for the Klamath River by the U.S. Geological Survey for the U.S. Department of the Interior, Klamath Secretarial Determination to simulate the effects of dam removal on water temperatures for current (2011) and future climate change scenarios. The analysis for this report was performed outside of the scope of the Klamath Secretarial Determination process at the request of the Bureau of Reclamation Technical Services Office, Denver, Colorado.For this analysis, two dam scenarios were simulated: “dams in” and “dams out.” In the “dams in” scenario, existing dams in the Klamath River were kept in place. In the “dams out” scenario, the river was modeled as a natural stream, without the J.C. Boyle, Copco1, Copco2, and Iron Gate Dams, for the entire simulation period. Output from the two dam scenario simulations included daily water temperatures simulated at 29 locations for a 50-year period along the Klamath River between river mile 253 (downstream of Link River Dam) and the Pacific Ocean. Both simulations used identical flow requirements, formulated in the 2010 Biological Opinion, and identical climate conditions based on the period 1961–2009.Simulated water temperatures from January through June at almost all locations between J.C. Boyle Reservoir and the Pacific Ocean were higher for the “dams out” scenario than for the “dams in” scenario. The simulated mean monthly water temperature increase was highest [1.7–2

  15. Impact of the Mekong River flow alteration on the Tonle Sap flood pulse.

    Science.gov (United States)

    Kummu, Matti; Sarkkula, Juha

    2008-05-01

    Rapid development in the upper reaches of the Mekong River, in the form of construction of large hydropower dams and reservoirs, large irrigation schemes, and rapid urban development, is putting water resources under stress. Recent studies have concluded that these developments will lead to flow alterations in the Mekong River. These flow alterations would threaten the sensitive ecosystems downstream, particularly Tonle Sap River, Tonle Sap Lake, its floodplain, and its gallery forest and protected areas, by changing the flood-pulse system of the lake. This article estimates the changes in parameters of the Tonle Sap flood pulse due to the aforementioned flow alterations. The impacts on the flooded area and loss of gallery forest and protected areas were analyzed using geographic information system-based methods. Relatively small rises in the dry-season lake water level would permanently inundate disproportionately large areas of floodplain, rendering it inaccessible to floodplain vegetation and eroding the productivity basis of the ecosystem. It is highly important to maintain the natural hydrological pattern of the Mekong River, particularly the dry-season water levels, to preserve Tonle Sap Lake's ecosystem productivity.

  16. 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

  17. CEM ultrasonic flow monitoring design, installation and certification results at the Salt River Project

    Energy Technology Data Exchange (ETDEWEB)

    Rihs, P.W. [Salt River Project, Saint Johns, AZ (United States). Coronado Generating Station

    1995-12-31

    This presentation will include Salt River Project`s design, installation, experiences and results using ultrasonic flow monitoring equipment for certification of continuous emissions monitoring systems. Flow Monitoring is the newest and has been the most controversial component of CEM systems. Experience in measuring flue gas volumetric flow prior to CEMs was very limited. There are currently three basic techniques used to measure gas flow: (1) thermal sensing using hotwire anemometer or thermal dispersion; (2) differential pressure (pitot tube and annubar); (3) acoustic using ultrasonic transducers. The Salt River Project (SRP) operates a variety of affected generating stations: coal, gas and oil. Ultrasonic flow monitoring technology was chosen for all affected generating stations which the author operates. SRP`s approach and reasoning for choosing ultrasonic systems will be discussed. A review of each generating station`s flow monitoring system will be presented. The presentation will include, but may not be limited to, the following: general facilities, description and schematics; physical installations, plan and section drawings; design considerations; results of flow monitors certification testing; and CEMs Project Manager`s conclusions.

  18. 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.

  19. On rating curve variability in presence of movable bed and unsteady flow. Applications to Tuscan rivers.

    Science.gov (United States)

    Minatti, Lorenzo; Nicoletta De Cicco, Pina; Paris, Enio

    2014-05-01

    In common engineering practice, rating curves are obtained from direct stage-discharge measurements or, more often, from stage measurements coupled with flow simulations. The present work mainly focuses on the latter technique, where stage-measuring gauges are usually installed on bridges with flow conditions likely to be influenced by local geometry constraints. In such cases, backwater flow and flow transition to supercritical state may occur, influencing sediment transport capacity and triggering more intense changes in river morphology. The unsteadiness of the flow hydrograph may play an important role too, according to the velocity of its rising and falling limbs. Nevertheless, the simulations conducted to build a rating curve are often carried out with steady flow and fixed bed conditions where the afore-mentioned effects are not taken into account at all. Numerical simulations with mobile bed and different unsteady flow conditions have been conducted on some real case studies in the rivers of Tuscany (Italy), in order to assess how rating curves change with respect to the "standard" one (that is, the classical steady flow rating curve). A 1D finite volume numerical model (REMo, River Evolution Modeler) has been employed for the simulations. The model solves the 1D Shallow Water equations coupled with the sediments continuity equation in composite channels, where the overbanks are treated with fixed bed conditions while the main channel can either aggrade or be scoured. The model employs an explicit scheme with 2nd order accuracy in both space and time: this allows the correct handling of moderately stiff source terms via a local corrector step. Such capability is very important for the applications of the present work as it allows the modelling of abrupt contractions and jumps in bed bottom elevations which often occur near bridges. The outcomes of the simulations are critically analyzed in order to provide a first insight on the conditions inducing

  20. Geothermal investigations in Idaho. Part 8. Heat flow study of the Snake River Plain region, Idaho

    Energy Technology Data Exchange (ETDEWEB)

    Brott, C.A.; Blackwell, D.D.; Mitchell, J.C.

    1976-09-01

    The Snake River Plain of Idaho has recent lava flows and a large number of thermal springs and wells. A heat flow study was initiated which, together with available geological and geophysical information, allows a better definition of the geothermal resource and evaluation of the geothermal potential. Local geothermal anomalies were not the objects of this study and have not been studied in detail. The quality of the heat flow values obtained varies as interpretation was necessary to determine geothermal gradients for many of the holes which had disturbances. A major problem in determining the heat flow values is the lack of knowledge of the in situ porosity of the rocks. The heat flow values obtained for the Eastern Snake River Plain are from shallow wells (< 200 m), hence the heat flow there is low (< 0.5 HFU) because of the water movement in the Snake Plain aquifer. The anomalous regional heat flow pattern around the Snake River Plain, together with other geophysical and geological data, suggest the presence of a major crustal heat source. With the exception of the area of the Snake Plain aquifer, high geothermal gradients were found in all areas of southern Idaho (40 to 100/sup 0/C/km). Temperatures hot enough for space heating can be found most anywhere in the Plain at relatively shallow depths (1 to 2 km). Temperatures hot enough for electrical power generation (200/sup 0/C) can be found beneath southern Idaho almost anywhere at depths of 3 to 4 kilometers. The Plain is fault bounded and hot water circulating along the fault zones from depths can be a very important geothermal resource at shallow depths. The margins of the Plain have the highest heat flow values, are the most faulted, and have possibly the highest geothermal resource potential.

  1. Predicting groundwater flow system discharge in the river network at the watershed scale

    Science.gov (United States)

    Caruso, Alice; Ridolfi, Luca; Boano, Fulvio

    2016-04-01

    The interaction between rivers and aquifers affects the quality and the quantity of surface and subsurface water since it plays a crucial role for solute transport, nutrient cycling and microbial transformations. The groundwater-surface water interface, better known as hyporheic zone, has a functional significance for the biogeochemical and ecological conditions of the fluvial ecosystem since it controls the flux of groundwater solutes discharging into rivers, and vice versa. The hyporheic processes are affected by the complex surrounding aquifer because the groundwater flow system obstructs the penetration of stream water into the sediments. The impact of large-scale stream-aquifer interactions on small scale exchange has generally been analyzed at local scales of a river reach, or even smaller. However, a complete comprehension of how hyporheic fluxes are affected by the groundwater system at watershed scale is still missing. Evaluating this influence is fundamental to predict the consequences of hyporheic exchange on water quality and stream ecology. In order to better understand the actual structure of hyporheic exchange along the river network, we firstly examine the role of basin topography complexity in controlling river-aquifer interactions. To reach this target, we focus on the analysis of surface-subsurface water exchange at the watershed scale, taking into account the river-aquifer interactions induced by landscape topography. By way of a mathematical model, we aim to improve the estimation of the role of large scale hydraulic gradients on hyporheic exchange. The potential of the method is demonstrated by the analysis of a benchmark case's study, which shows how the topographic conformation influences the stream-aquifer interaction and induces a substantial spatial variability of the groundwater discharge even among adjacent reaches along the stream. The vertical exchange velocity along the river evidences a lack of autocorrelation. Both the groundwater

  2. 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

  3. Daily Flow Model of the Delaware River Basin. Main Report.

    Science.gov (United States)

    1981-09-01

    II Tape History 111-3 111-2 High and Low Flow Lag Times 111-17 111-3 Fixes for Recurring Negative Inflows 111-21 IV-l Periods of Record of New York...00000 00000 00 - 00000 00000 00 0.= 0. U *00000 cacao 00 E 0 U Li.. IA. 0*00.0 00*00 NC C onto can.n. *0 O 00000 00000 00 .0 U 00000 00000 0000 0. EU0...As expected, 1964-1966 was the worst event in the 50 year history . The 25th worst annual event, June 1, 1935 to May 31, 1936 is an average year. The

  4. Adaptive real-time forecast of river flow-rates from rainfall data

    Science.gov (United States)

    Bolzern, P.; Ferrario, M.; Fronza, G.

    1980-07-01

    The paper describes a stochastic rainfall—river flow-rate model of the ARMAX type. Then a real-time Kalman predictor is derived from the model, namely a recursive relationship which, at the beginning of each time step, supplies the "best" forecast of future flow-rate on the basis of current rainfall and flow-rate measurements. Three different versions (ordered in the sense of increasing complexity) of the predictor are considered, corresponding to different approaches for estimating parameters and noise statistics of the stochastic model. The flood forecast performance of all predictors is tested on a real case (Lake Maggiore water system). The performance is satisfactory (for instance correlations about 99% between forecast and true values, standard deviation of the forecast error less than 1% of the average flood flow-rate) and conspicuously better than the one given by the trivial persistence predictor (the future flow-rate is the present one).

  5. On-line updating of a distributed flow routing model - River Vistula case study

    Science.gov (United States)

    Karamuz, Emilia; Romanowicz, Renata; Napiorkowski, Jaroslaw

    2015-04-01

    This paper presents an application of methods of on-line updating in the River Vistula flow forecasting system. All flow-routing codes make simplifying assumptions and consider only a reduced set of the processes known to occur during a flood. Hence, all models are subject to a degree of structural error that is typically compensated for by calibration of the friction parameters. Calibrated parameter values are not, therefore, physically realistic, as in estimating them we also make allowance for a number of distinctly non-physical effects, such as model structural error and any energy losses or flow processes which occur at sub-grid scales. Calibrated model parameters are therefore area-effective, scale-dependent values which are not drawn from the same underlying statistical distribution as the equivalent at-a-point parameter of the same name. The aim of this paper is the derivation of real-time updated, on-line flow forecasts at certain strategic locations along the river, over a specified time horizon into the future, based on information on the behaviour of the flood wave upstream and available on-line measurements at a site. Depending on the length of the river reach and the slope of the river bed, a realistic forecast lead time, obtained in this manner, may range from hours to days. The information upstream can include observations of river levels and/or rainfall measurements. The proposed forecasting system will integrate distributed modelling, acting as a spatial interpolator with lumped parameter Stochastic Transfer Function models. Daily stage data from gauging stations are typically available at sites 10-60 km apart and test only the average routing performance of hydraulic models and not their ability to produce spatial predictions. Application of a distributed flow routing model makes it possible to interpolate forecasts both in time and space. This work was partly supported by the project "Stochastic flood forecasting system (The River Vistula reach

  6. 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 A.

    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

  7. Unravelling connections between river flow and large-scale climate: experiences from Europe

    Science.gov (United States)

    Hannah, D. M.; Kingston, D. G.; Lavers, D.; Stagge, J. H.; Tallaksen, L. M.

    2016-12-01

    The United Nations has identified better knowledge of large-scale water cycle processes as essential for socio-economic development and global water-food-energy security. In this context, and given the ever-growing concerns about climate change/ variability and human impacts on hydrology, there is an urgent research need: (a) to quantify space-time variability in regional river flow, and (b) to improve hydroclimatological understanding of climate-flow connections as a basis for identifying current and future water-related issues. In this paper, we draw together studies undertaken at the pan-European scale: (1) to evaluate current methods for assessing space-time dynamics for different streamflow metrics (annual regimes, low flows and high flows) and for linking flow variability to atmospheric drivers (circulation indices, air-masses, gridded climate fields and vapour flux); and (2) to propose a plan for future research connecting streamflow and the atmospheric conditions in Europe and elsewhere. We believe this research makes a useful, unique contribution to the literature through a systematic inter-comparison of different streamflow metrics and atmospheric descriptors. In our findings, we highlight the need to consider appropriate atmospheric descriptors (dependent on the target flow metric and region of interest) and to develop analytical techniques that best characterise connections in the ocean-atmosphere-land surface process chain. We call for the need to consider not only atmospheric interactions, but also the role of the river basin-scale terrestrial hydrological processes in modifying the climate signal response of river flows.

  8. Methodology to determine regional water demand for instream flow and its application in the Yellow River Basin

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yuan; YANG Zhi-feng; Wang Xi-qin

    2006-01-01

    In order to realistically reflect the difference between regional water demand for instream flow and river ecological water demand as well as to resolve the problem that water demand may be counted repeatedly, a concept of regional water demand for minimum instream flow have been developed. The concept was used in the process of determining river functions and calculating ecological water demand for a river. The Yellow River watershed was used to validate the calculation methodology for regional water demand. Calculation results indicate that there are significant differences in water demands among the different regions. The regionalwater demand at the downstream of the Yellow River is the largest about 14.893 × 109 m3/a. The regional water demand of upstream,Lanzhou-Hekou section is the smallest about -5.012×109 m3/a. The total ecological water demand of the Yellow River Basin is 23.06 × 109 m3/a, about the 39% of surface water resources of the Yellow River Basin. That means the maximum available surface water resources should not exceed 61% in the Yellow River Basin. The regional river ecological water demands at the Lower Section of the Yellow River and Longyangxia-Lanzhou Section exceed the surface water resources produced in its region and need to be supplemented from other regions through the water rational planning of watershed water resources. These results provides technical basis for rational plan of water resources of the Yellow River Basin.

  9. Assessing climate change impacts on river flows and environmental flow requirements at catchment scale

    DEFF Research Database (Denmark)

    Gül, G.O.; Rosbjerg, Dan; Gül, A.

    2010-01-01

    mostly at the local scale. though potential changes in the hydrological cycle and eco-hydrological processes are more difficult to model and analyse at this level. The difficulty is even greater for studies on lowland river systems, which require the modelling of hydrological processes in greater detail...

  10. 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

  11. Sensitivity of Circulation in the Skagit River Estuary to Sea Level Rise and Future Flows

    Energy Technology Data Exchange (ETDEWEB)

    Khangaonkar, Tarang; Long, Wen; Sackmann, Brandon; Mohamedali, Teizeen; Hamlet, Alan F.

    2016-01-01

    Future climate simulations based on the Intergovernmental Panel on Climate Change emissions scenario (A1B) have shown that the Skagit River flow will be affected, which may lead to modification of the estuarine hydrodynamics. There is considerable uncertainty, however, about the extent and magnitude of resulting change, given accompanying sea level rise and site-specific complexities with multiple interconnected basins. To help quantify the future hydrodynamic response, we developed a three dimensional model of the Skagit River estuary using the Finite Volume Coastal Ocean Model (FVCOM). The model was set up with localized high-resolution grids in Skagit and Padilla Bay sub-basins within the intermediate-scale FVCOM based model of the Salish Sea (greater Puget Sound and Georgia Basin). Future changes to salinity and annual transport through the basin were examined. The results confirmed the existence of a residual estuarine flow that enters Skagit Bay from Saratoga Passage to the south and exits through Deception Pass. Freshwater from the Skagit River is transported out in the surface layers primarily through Deception Pass and Saratoga Passage, and only a small fraction (≈4%) is transported to Padilla Bay. The moderate future perturbations of A1B emissions, corresponding river flow, and sea level rise of 0.48 m examined here result only in small incremental changes to salinity structure and inter-basin freshwater distribution and transport. An increase in salinity of ~1 ppt in the near-shore environment and a salinity intrusion of approximately 3 km further upstream is predicted in Skagit River, well downstream of the drinking water intakes.

  12. 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?.

  13. Scaling characteristics of mountainous river flow fluctuations determined using a shallow-water acoustic tomography system

    Science.gov (United States)

    Al Sawaf, Mohamad Basel; Kawanisi, Kiyosi; Kagami, Junya; Bahreinimotlagh, Masoud; Danial, Mochammad Meddy

    2017-10-01

    The aim of this study is to investigate the scaling exponent properties of mountainous river flow fluctuations by detrended fluctuation analysis (DFA). Streamflow data were collected continuously using Fluvial Acoustic Tomography System (FATS), which is a novel system for measuring continuous streamflow at high-frequency scales. The results revealed that river discharge fluctuations have two scaling regimes and scaling break. In contrast to the Ranting Curve method (RC), the small-scale exponent detected by the FATS is estimated to be 1.02 ± 0.42% less than that estimated by RC. More importantly, the crossover times evaluated from the FATS delayed approximately by 42 ± 21 hr ≈2-3 days than their counterparts estimated by RC. The power spectral density analysis assists our findings. We found that scaling characteristics information evaluated for a river using flux data obtained by RC approach might not be accurately detected, because this classical method assumes that flow in river is steady and depends on constructing a relationship between discharge and water level, while the discharge obtained by the FATS decomposes velocity and depth into two ratings according to the continuity equation. Generally, this work highlights the performance of FATS as a powerful and effective approach for continuous streamflow measurements at high-frequency levels.

  14. River Flow Lane Detection and Kalman Filtering-Based B-Spline Lane Tracking

    Directory of Open Access Journals (Sweden)

    King Hann Lim

    2012-01-01

    Full Text Available A novel lane detection technique using adaptive line segment and river flow method is proposed in this paper to estimate driving lane edges. A Kalman filtering-based B-spline tracking model is also presented to quickly predict lane boundaries in consecutive frames. Firstly, sky region and road shadows are removed by applying a regional dividing method and road region analysis, respectively. Next, the change of lane orientation is monitored in order to define an adaptive line segment separating the region into near and far fields. In the near field, a 1D Hough transform is used to approximate a pair of lane boundaries. Subsequently, river flow method is applied to obtain lane curvature in the far field. Once the lane boundaries are detected, a B-spline mathematical model is updated using a Kalman filter to continuously track the road edges. Simulation results show that the proposed lane detection and tracking method has good performance with low complexity.

  15. Chemical elements potentially toxic at different flow rates in the Turvo Sujo river, MG, Brazil

    Directory of Open Access Journals (Sweden)

    Paulo Roberto Cecon

    2009-08-01

    Full Text Available Some chemical elements in small amounts are essential to life; however, in high concentrations can commit the quality of the water courses and cause damages to human health. The objective of this work was to quantify the presence of potentially toxic elements, in a section of the Turvo Sujo river in the Viçosa city during different flow rates. In this river five collection points were chosen and monitored in four different seasons. For each point, the concentrations of copper, manganese, iron, zinc, chromium, cadmium and lead were obtained. The iron and manganese concentrations were larger in summer time, due to the largest superficial drainage in this period, while the most toxic elements, such as chromium, cadmium and lead were observed in higher concentrations in the spring period corresponding to the lowest rate flow.

  16. BED VARIATION ANALYSIS IN THE CHIKUGO RIVER ESTUARY BY THE FLOOD FLOWS

    Science.gov (United States)

    Suzuki, Kenta; Shimamoto, Hisanori; Kubo, Seiki; Fukuoka, Shoji

    A series of fisherie issues in the Ariake sea has been believed to be caused by a lack of sand supply from the Chikugo river on the basis of few investigations of characteristics and amount of sediment transport in the the Chikugo river estuary. The core sampling and super-sonic echo sounder indicates that the vertical structure of mid stream of the Chikugo river estuary is consists of complex alternate layer and the rate of water content is much different to each layer. To make the rate of sand transport in the Chikugo river estuary clear, the authors applied unsteady quasi-three dimensional flood flow and river bed variation analysis using observed temporal changes in water surface profiles of flood. In the analysis, the bed layer which the rate of water content upper than 70% is calculated 2009by the experimental equation of erosion speed of the cohesive material. The results of analysis indicates that the rate of sand supply is strongly affected by the tidal level change of the Ariake sea.

  17. Using radon to understand parafluvial flows and the changing locations of groundwater inflows in the Avon River, southeast Australia

    Science.gov (United States)

    Cartwright, Ian; Hofmann, Harald

    2016-09-01

    Understanding the location and magnitude of groundwater inflows to rivers is important for the protection of riverine ecosystems and the management of connected groundwater and surface water systems. This study utilizes 222Rn activities and Cl concentrations in the Avon River, southeast Australia, to determine the distribution of groundwater inflows and to understand the importance of parafluvial flow on the 222Rn budget. The distribution of 222Rn activities and Cl concentrations implies that the Avon River contains alternating gaining and losing reaches. The location of groundwater inflows changed as a result of major floods in 2011-2013 that caused significant movement of the floodplain sediments. The floodplain of the Avon River comprises unconsolidated coarse-grained sediments with numerous point bars and sediment banks through which significant parafluvial flow is likely. The 222Rn activities in the Avon River, which are locally up to 3690 Bq m-3, result from a combination of groundwater inflows and the input of water from the parafluvial zone that has high 222Rn activities due to 222Rn emanation from the alluvial sediments. If the high 222Rn activities were ascribed solely to groundwater inflows, the calculated net groundwater inflows would exceed the measured increase in streamflow along the river by up to 490 % at low streamflows. Uncertainties in the 222Rn activities of groundwater, the gas transfer coefficient, and the degree of hyporheic exchange cannot explain a discrepancy of this magnitude. The proposed model of parafluvial flow envisages that water enters the alluvial sediments in reaches where the river is losing and subsequently re-enters the river in the gaining reaches with flow paths of tens to hundreds of metres. Parafluvial flow is likely to be important in rivers with coarse-grained alluvial sediments on their floodplains and failure to quantify the input of 222Rn from parafluvial flow will result in overestimating groundwater inflows to

  18. 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.

  19. Pollen flow of wheat under natural conditions in the Huanghuai River Wheat Region, China

    OpenAIRE

    Sun, Ai-Qing; Zhang, Chun-Qing; Wu, Cheng-Lai; Gao, Qing-Rong

    2015-01-01

    The transgenic pollen spread is the main pathway of transgenic plant gene flow. The maximum distance of pollen dispersal (horizontal), the spatial dynamics of pollen movement (vertical), and the patterns of pollen dispersal are important considerations in biosafety assessments of genetically modified crops. To evaluate wheat (Triticum aestivum) pollen dispersal, we measured the pollen suspension velocity and analyzed pollen dispersal patterns under natural conditions in the Huanghuai River wh...

  20. Environmental flow in the River Ondas basin in Bahia, Brazilian Cerrado.

    Science.gov (United States)

    de Souza Castro, Elis Regina Rodrigues; Moreira, Michel Castro; da Silva, Demetrius David

    2016-01-01

    This paper aimed to estimate the environmental flow of a water basin located in the Brazilian Cerrado using the bidimensional model River2D. The study was carried out in a stretch of the lower portion of the River Ondas in the western part of the state of Bahia, Brazil. To carry out the ecohydrological modeling, the following were used: topobathymetry, hydraulic characterization, the streamflows with the probability of non-exceedances (Q50, Q60, Q70, Q80, Q90, and Q95), and the Habitat Suitability Index for species of the genus Hypostomus. In the River2D, the weighted usable areas (WUAs) pertaining to the streamflows associated with different non-exceedances were simulated for the later construction of optimization and identification matrices of the streamflows that maximize the habitat area throughout the year. For juvenile Hypostomus, WUA increased as streamflow increased, with higher values associated with Q50. For adult specimens, lower WUA values were observed associated with Q50, while higher values were associated with Q95, which shows a preference for lower streamflows. The environmental flows found for the stretch of the River Ondas varied over the course of the year. The lowest environmental flows were observed in September (30.31 m(3) s(-1)) and October (29.98 m(3) s(-1)), while the highest were observed in February (44.22 m(3) s(-1)) and March (43.16 m(3) s(-1)). The environmental flow regime obtained restricts the water availability in the basin, for the purpose of water capture, which shows the importance of ecohydrological studies in forming a basis for water resource management actions.

  1. Determination of flow losses in the Cape Fear River between B. Everett Jordan Lake and Lillington, North Carolina, 2008-2010

    Science.gov (United States)

    Weaver, J. Curtis; McSwain, Kristen Bukowski

    2013-01-01

    During 2008-2010, the U.S. Geological Survey conducted a hydrologic investigation in cooperation with the Triangle J Council of Governments Cape Fear River Flow Study Committee and the North Carolina Division of Water Resources to collect hydrologic data in the Cape Fear River between B. Everett Jordan Lake and Lillington in central North Carolina to help determine if suspected flow losses occur in the reach. Flow loss analyses were completed by summing the daily flow releases at Jordan Lake Dam with the daily discharges at Deep River at Moncure and Buckhorn Creek near Corinth, then subtracting these values from the daily discharges at Cape Fear River at Lillington. Examination of long-term records revealed that during 10,227 days of the 1983-2010 water years, 408 days (4.0 percent) had flow loss when conditions were relatively steady with respect to the previous day's records. The flow loss that occurred on these 40 days ranged from 0.49 to 2,150 cubic feet per second with a median flow loss of 37.2 cubic feet per second. The months with the highest number of days with flow losses were June (16. percent), September (16.9 percent), and October (19.4 percent). A series of synoptic discharge measurements made on six separate days in 2009 provided "snapshots" of overall flow conditions along the study reach. The largest water diversion is just downstream from the confluence of the Haw and Deep Rivers, and discharges substantially decrease in the main stem downstream from the intake point. Downstream from Buckhorn Dam, minimal gain or loss between the dam and Raven Rock State Park was noted. Analyses of discharge measurements and ratings for two streamgages-one at Deep River at Moncure and the other at Cape Fear River at Lillington-were completed to address the accuracy of the relation between stage and discharge at these sites. The ratings analyses did not indicate a particular time during the 1982-2011 water years in which a consistent bias occurred in the

  2. 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

  3. Solar forcing of the stream flow of a continental scale South American river.

    Science.gov (United States)

    Mauas, Pablo J D; Flamenco, Eduardo; Buccino, Andrea P

    2008-10-17

    Solar forcing on climate has been reported in several studies although the evidence so far remains inconclusive. Here, we analyze the stream flow of one of the largest rivers in the world, the Paraná in southeastern South America. For the last century, we find a strong correlation with the sunspot number, in multidecadal time scales, and with larger solar activity corresponding to larger stream flow. The correlation coefficient is r=0.78, significant to a 99% level. In shorter time scales we find a strong correlation with El Niño. These results are a step toward flood prediction, which might have great social and economic impacts.

  4. VERIFICATION OF MATHEMATICL MODEL FOR SEDIMENT TRANSPORT BY UNSTEADY FLOW IN THE LOWER YELLOW RIVER

    Institute of Scientific and Technical Information of China (English)

    Jianjun ZHOU; Bingnan LIN

    2004-01-01

    Field data from the Lower Yellow River (LYR) covering a period of ten consecutive years are used to test a mathematical model for one dimensional sediment transport by unsteady flow developed previously by the writers. Data of the first year of the said period, i.e., 1976, are used to calibrate the model and those of the remaining years to verify it. Items investigated include discharge, water stage, rate of transport of suspended sediment and riverbed erosion/deposition. Comparisons between computed and observed data indicate that the proposed model may well simulate sediment transport in the LYR under conditions of unsteady flow with sufficient accuracy.

  5. 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...

  6. River-flow predictions for the South African mid-summer using a coupled general circulation model

    CSIR Research Space (South Africa)

    Olivier, C

    2013-09-01

    Full Text Available There are limited sources of streamflow data available in South Africa. These include simulated streamflow for catchments across South Africa and measured river-flow at specific rivers around the country. Given that a number of studies has been done...

  7. 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...

  8. The international river interface cooperative: Public domain flow and morphodynamics software for education and applications

    Science.gov (United States)

    Nelson, Jonathan M.; Shimizu, Yasuyuki; Abe, Takaaki; Asahi, Kazutake; Gamou, Mineyuki; Inoue, Takuya; Iwasaki, Toshiki; Kakinuma, Takaharu; Kawamura, Satomi; Kimura, Ichiro; Kyuka, Tomoko; McDonald, Richard R.; Nabi, Mohamed; Nakatsugawa, Makoto; Simões, Francisco R.; Takebayashi, Hiroshi; Watanabe, Yasunori

    2016-07-01

    This paper describes a new, public-domain interface for modeling flow, sediment transport and morphodynamics in rivers and other geophysical flows. The interface is named after the International River Interface Cooperative (iRIC), the group that constructed the interface and many of the current solvers included in iRIC. The interface is entirely free to any user and currently houses thirteen models ranging from simple one-dimensional models through three-dimensional large-eddy simulation models. Solvers are only loosely coupled to the interface so it is straightforward to modify existing solvers or to introduce other solvers into the system. Six of the most widely-used solvers are described in detail including example calculations to serve as an aid for users choosing what approach might be most appropriate for their own applications. The example calculations range from practical computations of bed evolution in natural rivers to highly detailed predictions of the development of small-scale bedforms on an initially flat bed. The remaining solvers are also briefly described. Although the focus of most solvers is coupled flow and morphodynamics, several of the solvers are also specifically aimed at providing flood inundation predictions over large spatial domains. Potential users can download the application, solvers, manuals, and educational materials including detailed tutorials at www.-i-ric.org. The iRIC development group encourages scientists and engineers to use the tool and to consider adding their own methods to the iRIC suite of tools.

  9. River Flow Forecasting Using Neural Networks and Auto-Calibrated NAM Model with Shuffled Complex Evolution

    Science.gov (United States)

    Zakermoshfegh, M.; Ghodsian, M.; Salehi Neishabouri, S. A. A.; Shakiba, M.

    River flow forecasting is required to provide important information on a wide range of cases related to design and operation of river systems. Since there are a lot of parameters with uncertainties and non-linear relationships, the calibration of conceptual or physically-based models is often a difficult and time consuming procedure. So it is preferred to implement a heuristic black box model to perform a non-linear mapping between the input and output spaces without detailed consideration of the internal structure of the physical process. In this study, the capability of artificial neural networks for stream flow forecasting in Kashkan River in West of Iran is investigated and compared to a NAM model which is a lumped conceptual model with shuffled complex evolution algorithm for auto calibration. Multi Layer Perceptron and Radial Basis Function neural networks are introduced and implemented. The results show that the discharge can be more adequately forecasted by Multi Layer Perceptron neural network, compared to other implemented models, in case of both peak discharge and base flow forecasting.

  10. The international river interface cooperative: Public domain flow and morphodynamics software for education and applications

    Science.gov (United States)

    Nelson, Jonathan M.; Shimizu, Yasuyuki; Abe, Takaaki; Asahi, Kazutake; Gamou, Mineyuki; Inoue, Takuya; Iwasaki, Toshiki; Kakinuma, Takaharu; Kawamura, Satomi; Kimura, Ichiro; Kyuka, Tomoko; McDonald, Richard R.; Nabi, Mohamed; Nakatsugawa, Makoto; Simoes, Francisco J.; Takebayashi, Hiroshi; Watanabe, Yasunori

    2016-01-01

    This paper describes a new, public-domain interface for modeling flow, sediment transport and morphodynamics in rivers and other geophysical flows. The interface is named after the International River Interface Cooperative (iRIC), the group that constructed the interface and many of the current solvers included in iRIC. The interface is entirely free to any user and currently houses thirteen models ranging from simple one-dimensional models through three-dimensional large-eddy simulation models. Solvers are only loosely coupled to the interface so it is straightforward to modify existing solvers or to introduce other solvers into the system. Six of the most widely-used solvers are described in detail including example calculations to serve as an aid for users choosing what approach might be most appropriate for their own applications. The example calculations range from practical computations of bed evolution in natural rivers to highly detailed predictions of the development of small-scale bedforms on an initially flat bed. The remaining solvers are also briefly described. Although the focus of most solvers is coupled flow and morphodynamics, several of the solvers are also specifically aimed at providing flood inundation predictions over large spatial domains. Potential users can download the application, solvers, manuals, and educational materials including detailed tutorials at www.-i-ric.org. The iRIC development group encourages scientists and engineers to use the tool and to consider adding their own methods to the iRIC suite of tools.

  11. Improved river flow and random sample consensus for curve lane detection

    Directory of Open Access Journals (Sweden)

    Huachun Tan

    2015-07-01

    Full Text Available Accurate and robust lane detection, especially the curve lane detection, is the premise of lane departure warning system and forward collision warning system. In this article, an algorithm based on improved river flow and random sample consensus is proposed to detect curve lane under challenging conditions including the dashed lane markings and vehicle occlusion. The curve lanes are modeled as hyperbola pair. To determine the coefficient of curvature, an improved river flow method is presented to search feature points in the far vision field guided by the results of detected straight lines in near vision field or the curved lines from the last frame, which can connect dashed lane markings or obscured lane markings. As a result, it is robust on dashed lane markings and vehicle occlusion conditions. Then, random sample consensus is utilized to calculate the curvature, which can eliminate noisy feature points obtained from improved river flow. The experimental results show that the proposed method can accurately detect lane under challenging conditions.

  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. Research on flow in water intake of a run-of-river hydropower plant

    Directory of Open Access Journals (Sweden)

    Balzannikov Mikhail

    2017-01-01

    Full Text Available The work shows the importance of flow research in parts of canal systems at hydropower plants. The authors researched a mathematical model of water intake at run-of-river hydropower plant. ANSYS software was used. The 3D model created by the authors described the upper part of the water intake extended to the approach area in front of it. The work was aimed at identifying flow parameters in the flow-narrowing zone of the water intake. The work describes the research method and presents graphical calculation results. Whirling areas were discovered in the upper part of water intake and in gate grooves. It was noted that the flow in gate grooves is spiral-shaped and runs downwards. The work highlights the danger of such flow because it increases the amount of small rubbish gravitating onto the lower part of the groove, which can cause gate hang up (blocking when it is shut in emergency. The results are of high importance for increasing safety of intakes at run-of-river hydropower plants.

  14. A novel permanent gauge-cam station for surface-flow observations on the Tiber River

    Science.gov (United States)

    Tauro, Flavia; Petroselli, Andrea; Porfiri, Maurizio; Giandomenico, Lorenzo; Bernardi, Guido; Mele, Francesco; Spina, Domenico; Grimaldi, Salvatore

    2016-06-01

    Flow monitoring of riverine environments is crucial for hydrology and hydraulic engineering practice. Besides few experimental implementations, flow gauging relies on local water level and surface-flow velocity measurements through ultrasonic meters and radars. In this paper, we describe a novel permanent gauge-cam station for large-scale and continuous observation of surface flows, based on remote acquisition and calibration of video data. Located on the Tiber River, in the center of Rome, Italy, the station captures 1 min videos every 10 min over an area oriented along the river cross section of up to 20.6 × 15.5 m2. In a feasibility study, we demonstrate that accurate surface-flow velocity estimations can be obtained by analyzing experimental images via particle tracking velocimetry (PTV). In medium illumination conditions (70-75 lux), PTV leads to velocity estimations in close agreement with radar records and is less affected by uneven lighting than large-scale particle image velocimetry. Future efforts will be devoted to the development of a comprehensive test bed infrastructure for investigating the potential of multiple optics-based approaches for surface hydrology.

  15. 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.

  16. Asymetrical structure in coastal river flows and jets

    Science.gov (United States)

    Redondo, Jose M.; Sekula, Emil; Bateman, Allen

    2010-05-01

    We apply visual scaling methods to both laboratory experiments and to satellite images of coastal flows as a tool to understand jet/boundary interactions in the environment. We compare the structure of SAR(Synthetic Aperture Radar) images of coastal jets and vortices and to experiments of jets of different Reynolds numbers and their images searching for common scaling and structural relationship between these two kinds of jets taking advantage of the self-similarity of the mixing processes. In order to investigate the structure of ocean surface detected jets (SAR)and vortices near the coast, we compare wall and boundary effects on the structure of turbulent jets (3D and 2D) which are non-homogeneous. We also use the multifractal analysis of SAR and experimental jets (plumes) images looking for relationship between these two kinds of jets. The SAR images exhibit a large variation of natural features produced by winds, internal waves, the bathymetric distribution, by thermal or solutal convection by rain, etc. These produce variations in the sea surface roughness. The satellite-borne SAR is able to detect oceanic features with a range of scales. The spatial cross-correlation may give an indication of the length over which such features are correlated. We compare the inner and outer jet boundaries detecting a clear asymetry, A similar effect is detected in laboratory experiments at large Reynolds number when a wall is near one of the sides of the jet. The geometrical constrains are seen to affect also the scale to scale energy transfer.

  17. MODFLOW-USG model of groundwater flow in the Wood River Valley aquifer system in Blaine County, Idaho

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — A three-dimensional numerical groundwater flow model (MODFLOW-USG) was developed for the Wood River Valley (WRV) aquifer system, south-central Idaho, to evaluate...

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

    Science.gov (United States)

    Crandall, Christy A.; Katz, Brian G.; Hirten, Joshua J.

    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 5.88m above mean sea level in April 1996 and discharge peaked at 360m3/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). Résumé Les aquifères karstiques sont particulièrement sensibles à l'infiltration rapide d'eau de rivières, spécialement pendant les périodes de hautes eaux. A la suite d'une période de pluies soutenues sur le bassin de la rivière Suwannee (Floride, États-Unis), le niveau de cette rivière est monté de 3,0 à 5,88m au-dessus du niveau

  19. 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.

  20. 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.

  1. Estuarine response to river flow and sea-level rise under future climate change and human development

    Science.gov (United States)

    Yang, Zhaoqing; Wang, Taiping; Voisin, Nathalie; Copping, Andrea

    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.

  2. Flow recommendations for maintaining riparian vegetation along the Upper Missouri River, Montana

    Science.gov (United States)

    Scott, Michael L.; Auble, Gregor T.; Friedman, Jonathan M.; Ischinger, Lee S.; Eggleston, Erik D.; Wondzell, Mark A.; Shafroth, Patrick B.; Back, Jennifer T.; Jordan, Mette S.

    1993-01-01

    Montana Power Company, Inc. (MPC) submitted a final license application to the Federal Energy Regulatory Commission (FERC) on November 30, 1992. In this application, MPC proposed a plan for the protection of fish, wildlife, habitat, and water-quality resources. One concern was maintenance of woody riparian vegetation along the Missouri River, especially along the Wild and Scenic reach of the river, where the riparian forest occurs in relatively small discontinuous stands. The objectives of this project were 1) to recommend flows that would protect and enhance riparian forests along the Missouri River, and 2) to develop elements of an environmental monitoring program that could be used to assess the effectiveness of the recommended flows. Plains cottonwood (Populus deltoides subsp. monilifera) is the key structural component of riparian forests along the Missouri River. Therefore, we focused our analysis on factors affecting populations of this species. Previous work had demonstrated that the age structure of cottonwood populations is strongly influenced by aspects of flow that promote successfully establishment. In this study our approach was to determine the precise age of plains cottonwood trees growing along the Upper Missouri River and to relate years of establishment to the flow record. Our work was carried out between Coal Banks Landing and the Fred G. Robinson Bridge within the Wild and Scenic portion of the Missouri River. This segment of the river occupies a narrow valley and exhibits little channel migration. Maps and notes from the journals of Lewis and Clark (1804-1806) suggest that the present distribution and abundance of cottonwoods within the study reach is generally similar to presettlement conditions. Flows in the study reach are influenced by a number of dams and diversions, most importantly, Canyon Ferry and Tiber Dams. Although flow regulation has decreased peak flows and increased low flows, the gross seasonal pattern of flow has not been

  3. Repeated surveys by acoustic Doppler current profiler for flow and sediment dynamics in a tidal river

    Science.gov (United States)

    Dinehart, R. L.; Burau, J. R.

    2005-11-01

    A strategy of repeated surveys by acoustic Doppler current profiler (ADCP) was applied in a tidal river to map velocity vectors and suspended-sediment indicators. The Sacramento River at the junction with the Delta Cross Channel at Walnut Grove, California, was surveyed over several tidal cycles in the Fall of 2000 and 2001 with a vessel-mounted ADCP. Velocity profiles were recorded along flow-defining survey paths, with surveys repeated every 27 min through a diurnal tidal cycle. Velocity vectors along each survey path were interpolated to a three-dimensional Cartesian grid that conformed to local bathymetry. A separate array of vectors was interpolated onto a grid from each survey. By displaying interpolated vector grids sequentially with computer animation, flow dynamics of the reach could be studied in three-dimensions as flow responded to the tidal cycle. Velocity streamtraces in the grid showed the upwelling of flow from the bottom of the Sacramento River channel into the Delta Cross Channel. The sequential display of vector grids showed that water in the canal briefly returned into the Sacramento River after peak flood tides, which had not been known previously. In addition to velocity vectors, ADCP data were processed to derive channel bathymetry and a spatial indicator for suspended-sediment concentration. Individual beam distances to bed, recorded by the ADCP, were transformed to yield bathymetry accurate enough to resolve small bedforms within the study reach. While recording velocity, ADCPs also record the intensity of acoustic backscatter from particles suspended in the flow. Sequential surveys of backscatter intensity were interpolated to grids and animated to indicate the spatial movement of suspended sediment through the study reach. Calculation of backscatter flux through cross-sectional grids provided a first step for computation of suspended-sediment discharge, the second step being a calibrated relation between backscatter intensity and sediment

  4. Simulation of ground-water flow and evaluation of water-management alternatives in the upper Charles River basin, eastern Massachusetts

    Science.gov (United States)

    DeSimone, Leslie A.; Walter, Donald A.; Eggleston, John R.; Nimiroski, Mark T.

    2002-01-01

    12 to 13 percent of total annual flow in some subbasins and of total monthly flow throughout the basin in summer and early fall. Water-management alternatives were evaluated by simulating hypothetical scenarios of increased withdrawals and altered recharge for average 1989?98 conditions with the flow models. Increased withdrawals to maximum State-permitted levels would result in withdrawals of about 15 million gallons per day, or about 50 percent more than current withdrawals. Model-calculated effects of these increased withdrawals included reductions in stream base flow that were greatest (as a percentage of total flow) in late summer and early fall. These reductions ranged from less than 5 percent to more than 60 percent of model-calculated 1989?98 base flow along reaches of the Charles River and major tributaries during low-flow periods. Reductions in base flow generally were comparable to upstream increases in withdrawals, but were slightly less than upstream withdrawals in areas where septic-system return flow was simulated. Increased withdrawals also increased the proportion of wastewater in the Charles River downstream of treatment facilities. The wastewater component increased downstream from a treatment facility in Milford from 80 percent of September base flow under 1989?98 conditions to 90 percent of base flow, and from 18 to 27 percent of September base flow downstream of a treatment facility in Medway. In another set of hypothetical scenarios, additional recharge equal to the transfer of water out of a typical subbasin by sewers was found to increase model-calculated base flows by about 12 percent of model-calculated base flows. Addition of recharge equal to that available from artificial recharge of residential rooftop runoff had smaller effects, augmenting simulated September base flow by about 3 percent. Simulation-optimization methods were applied to an area near Populatic Pond and the confluence of the Mill and Charles Rivers in Franklin,

  5. What maintains the waters flowing in our rivers? - Rethinking hydrogeology to improve public policy

    Science.gov (United States)

    Vasconcelos, Vitor Vieira

    2016-01-01

    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.

  6. Comparison of Natural Dams from Lava Flows and Landslides on the Owyhee River, Oregon

    Science.gov (United States)

    Ely, L. L.; Brossy, C. C.; Othus, S. M.; Orem, C.; Fenton, C.; House, P. K.; O'Connor, J. E.; Safran, E. B.

    2008-12-01

    Numerous large lava flows and mass movements have temporarily dammed the Owyhee River in southeastern Oregon at various temporal and spatial scales. These channel-encroaching events potentially play a significant role in creating and maintaining the geomorphic features of river canyons in uplifted volcanic terranes that compose a significant part of the western U.S. Abundant landslides and lava flows have the capacity to inhibit incision by altering channel slope, width, and bed character, and burying valley- bottom bedrock under exogenous material; or promote incision by generating cataclysmic floods through natural dam failures. The natural dams vary in their source, morphology, longevity and process of removal, which in turn affects the extent and duration of their impact on the river. The 3 most recent lava flows filled the channel 10-75 m deep and flowed up to 26 kilometers downvalley, creating long, low dams that were subject to gradual, rather than catastrophic, removal. In the last 125 ka, the Saddle Butte and West Crater lava dams created reservoirs into which 10-30 meters of silt and sand were deposited. The river overtopped the dams and in most reaches eventually cut a new channel through the adjacent, less resistant bedrock buttresses. Terraces at several elevations downstream and upstream of the West Crater dam indicate periods of episodic incision ranging from 0.28 to 1.7 mm/yr., based on 3He exposure ages on strath surfaces and boulder-rich fluvial deposits. In contrast to the lava dams, outburst flood deposits associated with landslide dams are common along the river. The mechanisms of failure are related to the geologic setting, and include rotational slump complexes, cantilevered blocks and block slides, and massive earthflows. Most large-scale mass movements occur in reaches where the Owyhee canyon incises through stacks of interbedded fluviolacustrine sediments capped with lava flows. The frequently observed association of landslides and flood

  7. Assessment of dam impacts on river flow regimes and water quality: a case study of the Huai River Basin in P. R. China

    Institute of Scientific and Technical Information of China (English)

    XIA Jun; ZHANG Yong-yong; WANG Gang-sheng

    2008-01-01

    The Huai River Basin is a unique area in P.R.China with the highest densities of population and water projects. It is also subject to the most serious water pollution. We proposed a distributional SWAT (Soil and Water Assessment Tool) model coupled with a water quality-quantity balance model to evaluate dam impacts on river flow regimes and water quality in the middle and upper reaches of the Huai River Basin. We calibrated and validated the SWAT model with data from 29 selected cross-sections in four typical years (1971, 1981, 1991 and 1999) and used scenario analysis to compensate for the unavailability of historical data regarding uninterrupted river flows before dam and floodgate construction, a problem of prediction for ungauged basins. The results indicate that dam and floodgate operations tended to reduce runoff, decrease peak value and shift peaking time.The contribution of water projects to river water quality deterioration in the concerned river system was between 0 to 40%, while pollutant discharge contributed to 60% to 100% of the water pollution. Pollution control should therefore be the key to the water quality rehabilitation in the Huai River Basin.

  8. An approach to assess the marginal environmental costs for flow regulation: an example in three European rivers

    Science.gov (United States)

    de Jalon Diego, Garcia; de Jalon Silvestre, Garcia; Tanago Marta, Gonzalez

    2015-04-01

    In the last decades there has been a growing concern about water environmental costs. 'Polluter should pay' has been a phrase repeated in numerous policy-making processes. Water abstraction for Irrigation, Hydropower or water supply for Domestic or Industrial porpoises alters natural flow regimes impacting severely fluvial Ecosystems. The objective of this paper is to develop an evaluation of the marginal environmental costs for flow regulation. This approach is based on the idea 'who regulates flows should pay' and the amount to be paid should be proportional on the intensity, duration and frequency of the resulting regulated flows. The methodology proposed includes three separated steps: (i) estimating the natural flow regime of a river segment through studying the hydrologic conditions before the river is affected by a determined anthropogenic impact, (ii) assessing the hydrologic alteration of the river segment according to the estimated natural flow regime, and (iii) calculating marginal environmental costs of water supply. The three different case studies where the methodology was applied were the Esla River (Spain), the Upper River Tyne (England) and the Marna River (Norway).

  9. Landscape Aesthetics of Riparian Environments: Relationship of Flow Quantity to Scenic Quality Along a Wild and Scenic River

    Science.gov (United States)

    Brown, Thomas C.; Daniel, Terry C.

    1991-08-01

    The relationship between flow quantity and scenic quality was measured for a "wild and scenic" river in Colorado. Respondents' scenic beauty judgments of video sequences depicting the river at flow rates from 120 to 2650 cfs (3.40 to 75.0 m3/s) were scaled to an interval scale measure of perceived scenic beauty following psychophysical scaling procedures. Regressions of scenic beauty on variables describing flow and other site characteristics showed scenic beauty to increase as flow increased up to about 1100-1500 cfs (31-42 m3/s) and then fall as flow continued to increase. Optimum flows for scenic beauty typically occur for two short periods each year, during the ascending and descending portions of the annual late spring peak runoff season. Flow explained from 10 to 25% of the variance in scenic beauty, depending on how much emphasis the scenic beauty judgment format tended to place on flow.

  10. 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

  11. Occurrence of a bimodal behavior in riparian vegetation dynamics driven by river flow variability

    Science.gov (United States)

    Camporeale, C.; Ridolfi, L.

    2006-12-01

    The riparian zone is a fluvial ecotone which exhibits very interesting interaction between hydraulics and ecology, with several important implications in the environmental management. Even though random variability is a key characteristic of the river hydrology, which plays a crucial role in the evolution of riparian vegetation, the impact of stochastic hydrologic fluctuations on the dynamics of riparian vegetation ecosystems remains for most part poorly understood. Here we propose a new approach to study the distribution of phreatophyte riparian vegetation, using a stochastic process to model the random forcing exerted by river flow on the dynamics of the overall biomass of vegetation. Growth and decrease of vegetation are modelled through a logistic and an exponential functions, respectively, which switch in a random way, depending on the flooding conditions. The time series of the river flow (described by the pdf and autocorrelation function), determines the corresponding time series of the water levels which in turn drives the statistical characteristics of the switching. In the logistic model, the carrying capacity is taken dependent on the water table depth through a quadratic optimum function with species-dependent parameters. A dimensional analysis shows that the fundamental factors are the autocorrelation function of the flow, the coefficient of variation, the ratio between growth and decrease rate of vegetation and the optimum water table depth. The switching dynamics is shown to be described by a single stochastic differential equation driven by dichotomic noise that is analytically solved herein. The main outcome is the pdf of the vegetation biomass at the steady state which allows the stability of the models and the central moments to be investigated. Bimodality of the solution and peculiar behaviors (e.g., noise-induced stability) are discussed, depending on the river geometry and the hydrological characteristics. The obtained analytical expressions

  12. Low-flow Characteristics of Eau Claire River Basin near Antigo, Wisconsin

    Science.gov (United States)

    Holmstrom, B.K.

    1975-01-01

    This report presents low-flow characteristics at six sites on streams in the Eau Claire River basin near Antigo, Wis., where applications for irrigation permits were made. The low-flow characteristics presented are the annual minimum 7-day mean flows at the 2-year recurrence interval and 10-year recurrence interval. A seepage run made October 10, 1974, showed a substantial gain in discharge from site 2 (3.75 ft3/s [cubic feet per second] or 0.11 m3/s (cubic metres per second) to site 6 (30.6 ft3/s or 0.87 m3/s) on the East Branch Eau Claire River and from site 12 (3.98 ft3/s or 0.11 m3/s) to site 16 (18.1 ft3/s or 0.51 m3/s) on the West Branch Eau Claire River; a fairly constant discharge between sites 6 (30.6 ft3/s or 0.87 m3/s) and 11 (32.3 ft3/s or 0.91 m3/s) on the East Branch and sites 16 (18.1 ft3/s or 0.51 m3/s) and 20 (18.8 ft3/s or 0.53 m3/s) on the West Branch; and a substantial gain in discharge from site 23 (57.3 ft3/s or 1.62 m3/s) to site 24 (63.4 ft3/s or 1.80 m3/s) on the Eau Claire River. A gaging station was established at the downstream potential irrigation site to collect continuous stage and discharge data on streamflow to assist the Wisconsin Department of Natural Resources in the regulation of irrigation withdrawals.

  13. Invasive riparian vegetation response to flow regimes and flood pulses in a braided river floodplain.

    Science.gov (United States)

    Caruso, Brian S; Pithie, Callum; Edmondson, Laura

    2013-08-15

    This study evaluated flow regimes and flood pulse characteristics, and their influences on invasive riparian vegetation, in a free-flowing braided river in the Southern Alps, South Island, New Zealand. A 46-year gauged flow record was used to evaluate 67 flow metrics for the Ahuriri River, and five sets of colour aerial photographs over 20 years (1991-2011) were analysed to quantify temporal and spatial changes in vegetation (crack willow, Russell lupin, and grassland). The correlation between flow metrics and vegetation class cover for each aerial photo interval was analysed, and multiple regression models were developed. Significant changes in different invasive vegetation classes were found, including cover, number and sizes of patches, and distances from patches to primary channels. In addition to infrequent large floods, specific characteristics of small floods, high flows, low/baseflows, and extreme low flows had influences on different vegetation classes. Key metrics that appear to drive changes in cover and provide a useful multiple regression model include the largest flood peak, frequency of floods, and the time since the last flood for each air photo interval. Up to 25% of invasive vegetation cover was removed and bare substrate increased after the largest flood on record (approximately 50-year flood), and the amount of vegetation cover is highly variable over time and space. Within approximately six years, however, the proportion of vegetation recovered to pre-flood levels. The study reach appears to demonstrate the "shifting-mosaic steady state" conceptual model of riverine floodplains, where the total proportion of substrate, vegetation and water remain relatively constant over long time periods.

  14. Simulated ground-water flow and water quality of the Mississippi River alluvium near Burlington, Iowa, 1999

    Science.gov (United States)

    Boyd, Robert A.

    2001-01-01

    The City of Burlington, Iowa, obtains some of its public water supply by withdrawing ground water from the Mississippi River alluvium, an alluvial aquifer adjacent to the Mississippi River. The U.S. Geological Survey, in cooperation with the City of Burlington, conducted a hydrologic study of the Mississippi River alluvium near Burlington in 1999 to improve understanding of the flow system, evaluate the effects of hypothetical pumping scenarios on the flow system, and evaluate selected water-quality constituents in parts of the alluvium.

  15. 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

  16. 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

  17. Widespread dieback of riparian trees on a dammed ephemeral river and evidence of local mitigation by tributary flows

    Directory of Open Access Journals (Sweden)

    Caitlin M. S. Douglas

    2016-10-01

    Full Text Available Ephemeral rivers act as linear oases in drylands providing key resources to people and wildlife. However, not much is known about these rivers’ sensitivities to human activities. We investigated the landscape-level determinants of riparian tree dieback along the Swakop River, a dammed ephemeral river in Namibia, focusing on the native ana tree (Faidherbia albida and the invasive mesquite (Prosopis spp.. We surveyed over 1,900 individual trees distributed across 24 sites along a 250 km stretch of the river. General linear mixed models were used to test five hypotheses relating to three anthropogenic threats: river flow disruption from damming, human settlement and invasive species. We found widespread dieback in both tree populations: 51% mortality in ana tree, with surviving trees exhibiting 18% canopy death (median; and 26% mortality in mesquite, with surviving trees exhibiting 10% canopy death. Dieback in the ana tree was most severe where trees grew on drier stretches of the river, where tributary flow was absent and where mesquite grew more abundantly. Dieback in the mesquite, a more drought-tolerant taxon, did not show any such patterns. Our findings suggest that dieback in the ana tree is primarily driven by changes in river flow resulting from upstream dam creation and that tributary flows provide a local buffer against this loss of main channel flow. The hypothesis that the invasive mesquite may contribute to ana tree dieback was also supported. Our findings suggest that large dams along the main channels of ephemeral rivers have the ability to cause widespread mortality in downstream riparian trees. To mitigate such impacts, management might focus on the maintenance of natural tributary flows to buffer local tree populations from the disruption to main channel flow.

  18. 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.

  19. 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

  20. Flow and sediment-transport modeling of Kootenai River White Sturgeon Spawning Habitat.

    Science.gov (United States)

    McDonald, R. R.; Nelson, J.; Barton, G.; Paragamian, V.

    2004-12-01

    The population of White Sturgeon in the Kootenai River downstream of Libby Dam in Montana and Idaho has declined since the construction of the dam in 1972. The White Sturgeon was listed as endangered in 1994 and an 11.2 mile reach of the river, downstream of Bonners Ferry, Idaho was designated as Critical Habitat in 2001. It is hypothesized that hydro-electric and flood control operations have contributed to poor spawning habitat and recruitment of juvenile fish. The successful incubation of eggs requires a stable and coarse bed material. Currently the sturgeon are spawning in a reach of poor substrate consisting of dunes up to 2 meters in amplitude and composed of fine sand while a short distance upstream there is suitable substrate of coarse gravel. We present here the preliminary results of a flow and sediment-transport modeling effort to aid in an understanding of both the current spawning habitat of the White Sturgeon and the potential to artificially enhance the current spawning habitat or to influence the sturgeon to move upstream to more suitable habitat. A 2.5 dimensional flow model was constructed for an 8-kilometer reach of the designated Critical Habitat. The modeled reach consists of several broad meanders and a mid channel island. The substrate is composed of fine sand with a median grain size of 0.22mm and has large dunes up to 2m in amplitude at relatively lows flows of 200 cms that wash out to a plane bed at around 600 cms. The model has been calibrated to a range of historical flow conditions from 170 cms to 1709 cms and verified against 16 ADCP velocity cross-section profiles collected during a period of steady flow at 554 cms. The model predicts well most of the salient features of the velocity field including the magnitude and location of the secondary flow, using a simple constant value for roughness. However for a few reaches of the river the bed forms and their spatial variability in size are shown to significantly affect the flow and the

  1. Coupled flow and salinity transport modelling in semi-arid environments: The Shashe River Valley, Botswana

    Science.gov (United States)

    Bauer, Peter; Held, Rudolf J.; Zimmermann, Stephanie; Linn, Flenner; Kinzelbach, Wolfgang

    2006-01-01

    Numerical groundwater modelling is used as the base for sound aquifer system analysis and water resources assessment. In many cases, particularly in semi-arid and arid regions, groundwater flow is intricately linked to salinity transport. A case in point is the Shashe River Valley in Botswana. A freshwater aquifer located around an ephemeral stream is depleted by the combined effect of transpiration and pumping. Quantitative system analysis reveals that the amount of water taken by transpiration is far more than the quantities pumped for water supply. Furthermore, the salinity distribution in and around Shashe River Valley as well as its temporal dynamics can be satisfactorily reproduced if the transpiration is modelled as a function of groundwater salinity. The location and dynamics of the saltwater-freshwater interface are highly sensitive to the parameterization of evaporative and transpirative salt enrichment. An existing numerical code for coupled flow/transport simulations (SEAWAT) was adapted to this situation. Model results were checked against a large set of field data including water levels, water chemistry, isotope data and ground and airborne geophysical data. The resulting groundwater model was able to reproduce the long-term development of the freshwater lens located in Shashe River Valley as well as the decline in piezometric heads observed over the last decade. Furthermore, the old age of the saline water surrounding the central freshwater lens could be explained.

  2. Predictability of soil moisture and river flows over France for the spring season

    Directory of Open Access Journals (Sweden)

    S. Singla

    2012-01-01

    Full Text Available 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.

  3. Water velocity and the nature of critical flow in large rapids on the Colorado River, Utah

    Science.gov (United States)

    Magirl, C.S.; Gartner, J.W.; Smart, G.M.; Webb, R.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 data, the Froude number in the fastest-flowing section of a rapid was estimated from near-surface velocity and depth soundings alone.

  4. River flow forecasting: use of phase-space reconstruction and artificial neural networks approaches

    Science.gov (United States)

    Sivakumar, B.; Jayawardena, A. W.; Fernando, T. M. K. G.

    2002-08-01

    The use of two non-linear black-box approaches, phase-space reconstruction (PSR) and artificial neural networks (ANN), for forecasting river flow dynamics is studied and a comparison of their performances is made. This is done by attempting 1-day and 7-day ahead forecasts of the daily river flow from the Nakhon Sawan station at the Chao Phraya River basin in Thailand. The results indicate a reasonably good performance of both approaches for both 1-day and 7-day ahead forecasts. However, the performance of the PSR approach is found to be consistently better than that of ANN. One reason for this could be that in the PSR approach the flow series in the phase-space is represented step by step in local neighborhoods, rather than a global approximation as is done in ANN. Another reason could be the use of the multi-layer perceptron (MLP) in ANN, since MLPs may not be most appropriate for forecasting at longer lead times. The selection of training set for the ANN may also contribute to such results. A comparison of the optimal number of variables for capturing the flow dynamics, as identified by the two approaches, indicates a large discrepancy in the case of 7-day ahead forecasts (1 and 7 variables, respectively), though for 1-day ahead forecasts it is found to be consistent (3 variables). A possible explanation for this could be the influence of noise in the data, an observation also made from the 1-day ahead forecast results using the PSR approach. The present results lead to observation on: (1) the use of other neural networks for runoff forecasting, particularly at longer lead times; (2) the influence of training set used in the ANN; and (3) the effect of noise on forecast accuracy, particularly in the PSR approach.

  5. The contribution of glacier melt to stream flow in the Wind River Range, WY

    Science.gov (United States)

    Cable, J. M.; Williams, D. G.; Bachman, S. A.

    2008-12-01

    The Wind River Range (Wyoming) boasts the largest concentration of glaciers in the American Rockies, and together with adjacent mountain ranges is the source of several major river systems in the western US. Declines in the volume of these glaciers associated with recent climate warming are well documented. Such declines of alpine glaciers will reduce the amount of water available for agricultural and domestic use, especially in late summer and fall. The contribution of glacial melt to stream flow remains largely unquantified in many parts of the U.S., particularly in Wyoming. In this study, we estimated the fractional contribution of glacier melt water from Dinwoody Glacier to flow in Dinwoody Creek in the Wind River Range on diurnal, seasonal, and interannual time scales. The stable isotope composition of water from the Dinwoody Creek watershed was determined on spatially and temporally intensive scales in 2007 and 2008. Spatially intensive sampling took place in the summers of both years; water samples were collected from (1) above and below major confluences along Dinwoody Creek, from (2) Dinwoody Glacier, (3) rain water, and (4) snow. Stream samples were collected over the entire melt season using an automated stream sampler placed beside an unimpaired USGS gauging station low in the watershed. Glacial melt contributed significantly to stream flow during periods of peak daily discharge (afternoon) and during late summer peak flow (late-August). In 2008, snow persisted late into the summer, so snowmelt was the main source of streamflow in mid-summer (July). Disappearance of glaciers in this watershed will affect both ecosystem and human water supplies during the late summer period, particularly in years when snowfields do not persist late into the summer.

  6. A Computer Method of Steady Non-Uniform Gradually Varied Flow in Open Channel & in River

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    Most of water flow in open channel or in river belongs to steady non-uniform flow. The surface profiles are caused by changes of channel section. It is very important to analyze its computation. According to the regularity of its surface change, the suitable sectional dimensions of open channel or flood control work can be designed. Commonly, computation of non-uniform flow adopts the traditional methods by hand or by graphic method. The speed and precision of computation are restricted. In this paper, a software to calculate water surface profile is introduced. The software is put forward by using C++ .By means of interpolate method and dialogue between user and computer, we can calculate the water surface profile much more quickly and exactly.

  7. MODFLOW-NWT groundwater flow model and GWM-VI optimization code for the Little Plover River Basin in Wisconsin's Central Sand Plain

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The Little Plover River groundwater flow model simulates three-dimensional groundwater movement in and around Wisconsin’s Little Plover River basin under...

  8. Regional groundwater flow and geochemical evolution in the Amacuzac River Basin, Mexico

    Science.gov (United States)

    Morales-Casique, Eric; Guinzberg-Belmont, Jacobo; Ortega-Guerrero, Adrián

    2016-11-01

    An approach is presented to investigate the regional evolution of groundwater in the basin of the Amacuzac River in Central Mexico. The approach is based on groundwater flow cross-sectional modeling in combination with major ion chemistry and geochemical modeling, complemented with principal component and cluster analyses. The hydrogeologic units composing the basin, which combine aquifers and aquitards both in granular, fractured and karstic rocks, were represented in sections parallel to the regional groundwater flow. Steady-state cross-section numerical simulations aided in the conceptualization of the groundwater flow system through the basin and permitted estimation of bulk hydraulic conductivity values, recharge rates and residence times. Forty-five water locations (springs, groundwater wells and rivers) were sampled throughout the basin for chemical analysis of major ions. The modeled gravity-driven groundwater flow system satisfactorily reproduced field observations, whereas the main geochemical processes of groundwater in the basin are associated to the order and reactions in which the igneous and sedimentary rocks are encountered along the groundwater flow. Recharge water in the volcanic and volcano-sedimentary aquifers increases the concentration of HCO3 -, Mg2+ and Ca2+ from dissolution of plagioclase and olivine. Deeper groundwater flow encounters carbonate rocks, under closed CO2 conditions, and dissolves calcite and dolomite. When groundwater encounters gypsum lenses in the shallow Balsas Group or the deeper Huitzuco anhydrite, gypsum dissolution produces proportional increased concentration of Ca2+ and SO4 2-; two samples reflected the influence of hydrothermal fluids and probably halite dissolution. These geochemical trends are consistent with the principal component and cluster analyses.

  9. Two-Dimensional River Flow Patterns Observed with a Pair of UHF Radar System

    Directory of Open Access Journals (Sweden)

    Yidong Hou

    2017-01-01

    Full Text Available A pair of ultrahigh-frequency (UHF radars system for measuring the two-dimensional river flow patterns is presented. The system consists of two all-digital UHF radars with exactly the same hardware structure, operating separately at 329–339 MHz and 341–351 MHz. The adoption of direct radio frequency (RF sampling technique and digital pulse compression simplifies the structure of radar system and eliminates the distortion introduced by the analog mixer, which improves the SNR and dynamic range of the radar. The field experiment was conducted at Hanjiang River, Hubei province, China. Over a period of several weeks, the radar-derived surface velocity has been very highly correlated with the measurements of EKZ-I, with a correlation coefficient of 0.958 and a mean square error of 0.084 m/s.

  10. Dispatch Method for Independently Owned Hydropower Plants in the Same River Flow

    Directory of Open Access Journals (Sweden)

    Slavko Krajcar

    2012-09-01

    Full Text Available This paper proposes a coexistence model for two independent companies both operating hydropower plants in the same river flow, based on a case study of the Cetina river basin in Croatia. Companies are participants of the day-ahead electricity market. The incumbent company owns the existing hydropower plants and holds concessions for the water. The new company decides to build a pump storage hydropower plant that uses one of the existing reservoirs as its lower reservoir. Meeting reservoir water balance is affected by decisions by both companies which are independently seeking maximal profit. Methods for water use settlement and preventing of spillage are proposed. A mixed-integer linear programming approach is used. Head effects on output power levels are also considered. Existences of dispatches that satisfy both companies are shown.

  11. 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.

  12. Improving River Flow Predictions from the NOAA NCRFC Forecasting Model by Incorporating Satellite Observations

    Science.gov (United States)

    Tuttle, S. E.; Jacobs, J. M.; Restrepo, P. J.; Deweese, M. M.; Connelly, B.; Buan, S.

    2016-12-01

    The NOAA National Weather Service North Central River Forecast Center (NCRFC) is responsible for issuing river flow forecasts for parts of the Upper Mississippi, Great Lakes, and Hudson Bay drainages, including the Red River of the North basin (RRB). The NCRFC uses an operational hydrologic modeling infrastructure called the Community Hydrologic Prediction System (CHPS) for its operational forecasts, which currently links the SNOW-17 snow accumulation and ablation model, to the Sacramento-Soil Moisture Accounting (SAC-SMA) rainfall-runoff model, to a number of hydrologic and hydraulic flow routing models. The operational model is lumped and requires only area-averaged precipitation and air temperature as inputs. NCRFC forecasters use observational data of hydrological state variables as a source of supplemental information during forecasting, and can use professional judgment to modify the model states in real time. In a few recent years (e.g. 2009, 2013), the RRB exhibited unexpected anomalous hydrologic behavior, resulting in overestimation of peak flood discharge by up to 70% and highlighting the need for observations with high temporal and spatial coverage. Unfortunately, observations of hydrological states (e.g. soil moisture, snow water equivalent (SWE)) are relatively scarce in the RRB. Satellite remote sensing can fill this need. We use Minnesota's Buffalo River watershed within the RRB as a test case and update the operational CHPS model using modifications based on satellite observations, including AMSR-E SWE and SMOS soil moisture estimates. We evaluate the added forecasting skill of the satellite-enhanced model compared to measured streamflow using hindcasts from 2010-2013.

  13. IOD and ENSO impacts on the extreme stream-flows of Citarum river in Indonesia

    Science.gov (United States)

    Sahu, Netrananda; Behera, Swadhin K.; Yamashiki, Yosuke; Takara, Kaoru; Yamagata, Toshio

    2012-10-01

    Extreme stream-flow events of Citarum River are derived from the daily stream-flows at the Nanjung gauge station. Those events are identified based on their persistently extreme flows for 6 or more days during boreal fall when the seasonal mean stream-flow starts peaking-up from the lowest seasonal flows of June-August. Most of the extreme events of high-streamflows were related to La Niña conditions of tropical Pacific. A few of them were also associated with the negative phases of IOD and the newly identified El Niño Modoki. Unlike the cases of extreme high streamflows, extreme low streamflow events are seen to be associated with the positive IODs. Nevertheless, it was also found that the low-stream-flow events related to positive IOD events were also associated with El Niño events except for one independent event of 1977. Because the occurrence season coincides the peak season of IOD, not only the picked extreme events are seen to fall under the IOD seasons but also there exists a statistically significant correlation of 0.51 between the seasonal IOD index and the seasonal streamflows. There also exists a significant lag correlation when IOD of June-August season leads the streamflows of September-November. A significant but lower correlation coefficient (0.39) is also found between the seasonal streamflow and El Niño for September-November season only.

  14. Coherent Flow Structures and Suspension Events over Low-angle Dunes: Fraser River, Canada

    Science.gov (United States)

    Bradley, R. W.; Venditti, J. G.; Kostaschuk, R. A.; Hendershot, M. L.; Allison, M. A.; Church, M. A.

    2012-12-01

    Increasing observations show that dunes with low-angle lee-sides (MBES) while an acoustic Doppler current profiler (aDcp) simultaneously provided flow and suspended sediment measurements over a range of flows through tidal cycles. At high tide, river flow nearly ceases and a salt wedge enters the channel, forcing plumes of salt water towards the surface into the downstream moving fresh water above as the wedge moves upstream over the dunes. The salt wedge persists in the channel causing stratification in water column and one-sided instabilities along the saline-fresh water interface until the late in the falling tide. At low tide, mean velocities peak and force the saline water out of the channel. Flow over the low-angle dunes displays topographically induced flow patterns similar to previously observed over high-angle dunes, but permanent flow separation is notably absent. Sediment-laden kolks emerge as important suspended sediment transport agents during low tide but become more coherent, yet less frequent, structures as the tide begins to rise. Kolks appear to form downstream of dune crests along the shear layer that is likely formed by intermittent flow separation. Kolks also form at the reattachment point and grow over the stoss slope of the dunes. This is consistent with the generation of hairpin vortices formed near the bed that lift into the flow and grow to the surface through an 'autogeneration' mechanism. Persistent downwelling and periodic sweeps at dune crests provide a mechanism for sediment erosion and entrainment while periodic ejection motions or kolks in a zone of persistent upwelling at the lower stoss provide a mechanism sediment suspension. Kolks are estimated to move ~70% of the total sediment in the flow above dunes when they are present in the water column.

  15. Influence of groundwater extraction on river flows and the surrounding ecosystem

    Science.gov (United States)

    Belova, Anna

    2010-05-01

    Influence of groundwater extraction on river flows and the surrounding ecosystem. Change of hydro-geological conditions and the conditions of environment connected with them? One of the most adverse consequences of the large centralised operation of underground waters coastal (riverine) water fences. Such situation is predicted on the Permilovsky deposit reconnoitered for water supply of Arkhangelsk. The projected water fence was planned in a valley of the river of Vajmugi on its left coast. The predesigns spent on hydrogeodynamic of model of a deposit, show that as a result of operation of underground waters the damage to a drain of the river Vajmuga approximately equal дебиту of a water fence that leads to a considerable shallowing of the river, especially during its periods маловодности, up to a drain total disappearance on a water fence site is formed. On the average, on territories of a deposit expenses of the river concerning natural state can be reduced more than to 50 %. Reduction of a river drain will lead to considerable negative consequences in environment, including: - changes in surface runoff, reduced groundwater levels, inhibit vegetation and changes in plant communities, draining wetlands, changing soil moisture conditions, a decrease of spring runoff, damage to forestry; - earth's surface subsidence, damage to streets and roads, buildings, structures and communications, drainage wells, the development of karst processes and suffosion; - the formation of deep depressions, capturing several zones of water exchange, which could lead to mixing of water of different chemical composition and mineralization of the runoff into surface water bodies, increase the nitrogen content in groundwater; - discontinuity separating the layers and the increased vulnerability of groundwater and surface water, the action of man-made agents. The aim of this study was a preliminary study of alternative schemes of exploitation of underground water deposits

  16. Simulating Spawning and Juvenile Rainbow Trout (Oncorhynchus mykiss Habitat in Colorado River Based on High-Flow Effects

    Directory of Open Access Journals (Sweden)

    Weiwei Yao

    2017-02-01

    Full Text Available High flow generates significant alterations in downstream river reaches, resulting in physical condition changes in the downstream regions of the river such as water depth, flow velocity, water temperature and river bed. These alterations will lead to change in fish habitat configuration in the river. This paper proposes a model system to evaluate the high flow effects on river velocity, water depth, substrates changes, temperature distribution and consequently assess the change in spawning and juvenile rainbow trout (Oncorhynchus mykiss habitats in the downstream region of the Glen Canyon Dam. Firstly, based on the 2 dimensional (2D depth-averaged CFD (Computational Fluid Dynamics model and heat transfer equation applied for simulation, three indices were simulated, namely depth, flow velocity and temperature distribution. Then, the spawning and juvenile fish preference curves were obtained based on these three indices and substrates distribution. After that, the habitat model was proposed and used to simulate the high flow effects on juvenile and spawning rainbow trout habitat structure. Finally, the weighted usable area (WUA and overall suitability index (OSI of the spawning and juvenile fish species were quantitatively simulated to estimate the habitat sensitivity. The results illustrate that the high flow effect (HFE increased the juvenile rainbow trout habitat quality but decreased the spawning rainbow trout habitat quality. The juvenile trout were mainly affected by the water depth while the spawning rainbow trout were dominated by the bed elevation.

  17. Benefits of prescribed flows for salmon smolt survival enhancement vary longitudinally in a highly managed river system

    Science.gov (United States)

    Courter, Ian; Garrison, Thomas; Kock, Tobias J.; Perry, Russell W.; Child, David; Hubble, Joel

    2016-01-01

    The influence of streamflow on survival of emigrating juvenile Pacific salmonids Oncorhynchus spp. (smolts) is a major concern for water managers throughout the northeast Pacific Rim. However, few studies have quantified flow effects on smolt survival, and available information does not indicate a consistent flow–survival relationship within the typical range of flows under management control. In the Yakima Basin, Washington, the potential effects of streamflow alterations on smolt survival have been debated for over 20 years. Using a series of controlled flow releases from upper basin reservoirs and radiotelemetry, we quantified the relationship between flow and yearling Chinook salmon smolt survival in the 208 km reach between Roza Dam and the Yakima River mouth. A multistate mark–recapture model accounted for weekly variation in flow conditions experienced by tagged fish in four discrete river segments. Smolt survival was significantly associated with streamflow in the Roza Reach [river kilometre (rkm) 208–189] and marginally associated with streamflow in the Sunnyside Reach (rkm 169–77). However, smolt survival was not significantly associated with flow in the Naches and Prosser Reaches (rkm 189–169 and rkm 77–3). This discrepancy indicates potential differences in underlying flow-related survival mechanisms, such as predation or passage impediments. Our results clarify trade-offs between flow augmentation for fisheries enhancement and other beneficial uses, and our study design provides a framework for resolving uncertainties about streamflow effects on migratory fish survival in other river systems. 

  18. Thermodynamics, maximum power, and the dynamics of preferential river flow structures on continents

    Directory of Open Access Journals (Sweden)

    A. Kleidon

    2012-06-01

    Full Text Available The organization of drainage basins shows some reproducible phenomena, as exemplified by self-similar fractal river network structures and typical scaling laws, and these have been related to energetic optimization principles, such as minimization of stream power, minimum energy expenditure or maximum "access". Here we describe the organization and dynamics of drainage systems using thermodynamics, focusing on the generation, dissipation and transfer of free energy associated with river flow and sediment transport. We argue that the organization of drainage basins reflects the fundamental tendency of natural systems to deplete driving gradients as fast as possible through the maximization of free energy generation, thereby accelerating the dynamics of the system. This effectively results in the maximization of sediment export to deplete topographic gradients as fast as possible and potentially involves large-scale feedbacks to continental uplift. We illustrate this thermodynamic description with a set of three highly simplified models related to water and sediment flow and describe the mechanisms and feedbacks involved in the evolution and dynamics of the associated structures. We close by discussing how this thermodynamic perspective is consistent with previous approaches and the implications that such a thermodynamic description has for the understanding and prediction of sub-grid scale organization of drainage systems and preferential flow structures in general.

  19. Quasi 3D refined simulation of flow and pollutant transport in a meandering River Reach

    Directory of Open Access Journals (Sweden)

    Li-ren Yu

    2013-03-01

    Full Text Available This paper reports a quasi 3D numerical simulation in a meandering river reach of the Yellow River, aiming to develop a tool for modeling turbulent flows and pollutant transport in complex natural waters. The recently built depth-averaged two-equation turbulence model, together with and models, were used to close non-simplified quasi 3D hydrodynamic fundamental governing equations. The discretized equations were solved by advanced multi-grid iterative method under non-orthogonal body-fitted coarse and fine two-levels’ grids with collocated variable arrangement. Except for steady flow and transport computation, the processes of contaminant inpouring and plume development, caused by the side-discharge from a tribytary, also have been investigated numerically. The used three closure approaches are suitable for modeling strong mixing turbulence. The established model with higher order of magnitude of transported variable provides a possibility to elevate the computational precision. Based on the developed mathematical model, a CFD (Computational Fluid Dynamics software, namely Q3drm1.0, was developed. This numerical tool focuses on the refined simulations of the steady and unsteady problems of flow and temperature/contaminant transports in complicated computational domains with the strong ability to deal with different discharge situations: side-discharge, point-source discharge/point-sink, and area-source discharge from the slope along bank. In this article, the study of side-discharge is presented only.

  20. Thermodynamics, maximum power, and the dynamics of preferential river flow structures at the continental scale

    Directory of Open Access Journals (Sweden)

    A. Kleidon

    2013-01-01

    Full Text Available The organization of drainage basins shows some reproducible phenomena, as exemplified by self-similar fractal river network structures and typical scaling laws, and these have been related to energetic optimization principles, such as minimization of stream power, minimum energy expenditure or maximum "access". Here we describe the organization and dynamics of drainage systems using thermodynamics, focusing on the generation, dissipation and transfer of free energy associated with river flow and sediment transport. We argue that the organization of drainage basins reflects the fundamental tendency of natural systems to deplete driving gradients as fast as possible through the maximization of free energy generation, thereby accelerating the dynamics of the system. This effectively results in the maximization of sediment export to deplete topographic gradients as fast as possible and potentially involves large-scale feedbacks to continental uplift. We illustrate this thermodynamic description with a set of three highly simplified models related to water and sediment flow and describe the mechanisms and feedbacks involved in the evolution and dynamics of the associated structures. We close by discussing how this thermodynamic perspective is consistent with previous approaches and the implications that such a thermodynamic description has for the understanding and prediction of sub-grid scale organization of drainage systems and preferential flow structures in general.

  1. Mapping rivers with a potential danger of damage by flash flooding and debris flows

    Science.gov (United States)

    Peereboom, I.; Svegården, J.; Fergus, T.

    2009-04-01

    Landforms associated with past debris flows such as alluvial fans are typical locations for settlements in Norway. Flash floods with associated debris flows in small and steep river catchments cause a great deal of damage to infrastructure and housing located on alluvial fans. The Norwegian Water Resources and Energy Resources Directorate (NVE) is the national authority responsible for flood and landslide hazard management in Norway. Mapping areas with a risk of damage from flooding and landslides coupled with advice on land use planning, results in better land use practices and an increased awareness of the potential hazard among local authorities and citizens. Methods for mapping floodplain inundation for large rivers are well developed. This is not the case for rivers with small and steep catchments with a potential for high rates of erosion and sediment transport. A method for identifying and mapping rivers with a potential danger of flash flooding and associated debris flows is currently being developed at NVE. The resultant maps will assist local authorities in the first step in land use planning where they are required to identify if there is a potential hazard in the area. The method makes use of spatial data available for the whole country and is based on a 25*25 m terrain model. The method is based on two simple assumptions adapted to the available data: i) Under normal hydraulic conditions there is a balance between processes of erosion and sedimentation. A debris flow will first occur when this balance is disturbed. This is quantified by the relative difference between the discharge of an extreme flood and floods that occur more frequently, ie. if the difference is large the probability of a debris flow occurring is greater and vice versa. ii) Steep rivers with a large difference in height between cells have more energy available for erosion and sediment transport and therefore a larger potential for erosion and sediment transport than less steep rivers

  2. Recent changes (1973-2014 versus 1903-1972) in the flow regime of the Lower Paraná River and current fluvial pollution warnings in its Delta Biosphere Reserve.

    Science.gov (United States)

    Puig, Alba; Olguín Salinas, Héctor F; Borús, Juan A

    2016-06-01

    Alterations in flow regimes of large rivers may originate or increase risks to ecosystems and humans. The Paraná River basin (South America) undergoes human pressures (e.g., heavy damming in the upper basin, deforestation, and mixed pollution) that may affect the water quantity and quality of its terminal Delta (Argentina). In this study, after applying univariate and multivariate change-point detection and trend analyses to the daily data series of flows incoming to the Delta (Paraná-Santa Fe section), flow characteristics were compared by Indicators of Hydrologic Alteration (IHA) and Environmental Flow Components (EFC). Some flood characteristics were also compared from hydrometric levels in the middle Delta (San Pedro station). Chemical and microbiological water variables in the main rivers of the "Paraná Delta" Biosphere Reserve were examined during two extreme hydrologic years (October 2008 to July 2010) to detect potential risk factors in association with hydrologic conditions. In the Lower Paraná River, a historical period (1903-1972) and two more altered periods (1973-1999 wet period and 2000-2014 dry period) were identified. Flow duration curves evidenced different changes in both altered periods, reflecting the joint effect of climatic variability and human influence. The most evident alterations in the flow regime were the lack of record of the extreme-low-flow component, the attenuation of monthly flow seasonality, and the increase in the number of reversals (dry period) and in the variability of maximum and minimum flow dates. These alterations are consistent with the monthly and daily flow regulation by upstream dams evidenced by available data from the current dry period. In the middle Delta, the marked monthly seasonality in flood days decreased only in the wet period. The proportion between the number of flood days exceeding the evacuation level and that of those exceeding the warning level doubled in the wet period but decreased only

  3. Recent changes (1973-2014 versus 1903-1972) in the flow regime of the Lower Paraná River and current fluvial pollution warnings in its Delta Biosphere Reserve

    Science.gov (United States)

    Puig, Alba; Olguín Salinas, Héctor F.; Borús, Juan A.

    2016-06-01

    Alterations in flow regimes of large rivers may originate or increase risks to ecosystems and humans. The Paraná River basin (South America) undergoes human pressures (e.g., heavy damming in the upper basin, deforestation, and mixed pollution) that may affect the water quantity and quality of its terminal Delta (Argentina). In this study, after applying univariate and multivariate change-point detection and trend analyses to the daily data series of flows incoming to the Delta (Paraná-Santa Fe section), flow characteristics were compared by Indicators of Hydrologic Alteration (IHA) and Environmental Flow Components (EFC). Some flood characteristics were also compared from hydrometric levels in the middle Delta (San Pedro station). Chemical and microbiological water variables in the main rivers of the "Paraná Delta" Biosphere Reserve were examined during two extreme hydrologic years (October 2008 to July 2010) to detect potential risk factors in association with hydrologic conditions. In the Lower Paraná River, a historical period (1903-1972) and two more altered periods (1973-1999 wet period and 2000-2014 dry period) were identified. Flow duration curves evidenced different changes in both altered periods, reflecting the joint effect of climatic variability and human influence. The most evident alterations in the flow regime were the lack of record of the extreme-low-flow component, the attenuation of monthly flow seasonality, and the increase in the number of reversals (dry period) and in the variability of maximum and minimum flow dates. These alterations are consistent with the monthly and daily flow regulation by upstream dams evidenced by available data from the current dry period. In the middle Delta, the marked monthly seasonality in flood days decreased only in the wet period. The proportion between the number of flood days exceeding the evacuation level and that of those exceeding the warning level doubled in the wet period but decreased only slightly

  4. Controls of channel morphology and sediment concentration on flow resistance in a large sand-bed river: A case study of the lower Yellow River

    Science.gov (United States)

    Ma, Yuanxu; Huang, He Qing

    2016-07-01

    Accurate estimation of flow resistance is crucial for flood routing, flow discharge and velocity estimation, and engineering design. Various empirical and semiempirical flow resistance models have been developed during the past century; however, a universal flow resistance model for varying types of rivers has remained difficult to be achieved to date. In this study, hydrometric data sets from six stations in the lower Yellow River during 1958-1959 are used to calibrate three empirical flow resistance models (Eqs. (5)-(7)) and evaluate their predictability. A group of statistical measures have been used to evaluate the goodness of fit of these models, including root mean square error (RMSE), coefficient of determination (CD), the Nash coefficient (NA), mean relative error (MRE), mean symmetry error (MSE), percentage of data with a relative error ≤ 50% and 25% (P50, P25), and percentage of data with overestimated error (POE). Three model selection criterions are also employed to assess the model predictability: Akaike information criterion (AIC), Bayesian information criterion (BIC), and a modified model selection criterion (MSC). The results show that mean flow depth (d) and water surface slope (S) can only explain a small proportion of variance in flow resistance. When channel width (w) and suspended sediment concentration (SSC) are involved, the new model (7) achieves a better performance than the previous ones. The MRE of model (7) is generally methods developed in this study can be used as an effective surrogate in estimation of flow resistance in the large sand-bed rivers like the lower Yellow River.

  5. Dissolved Nutrient Retention Dynamics in River Networks: A Modeling Investigation of Transient Flow and Scale Effects

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Sheng; Covino, Timothy P.; Sivapalan, Murugesu; Basu, Nandita; Li, Hongyi; Wang, Shaowen

    2012-06-30

    In this paper, we use a dynamic network flow model, coupled with a transient storage zone biogeochemical model, to simulate dissolved nutrient removal processes at the channel network scale. We have explored several scenarios in respect of the combination of rainfall variability, and the biological and geomorphic characteristics of the catchment, to understand the dominant controls on removal and delivery of dissolved nutrients (e.g., nitrate). These model-based theoretical analyses suggested that while nutrient removal efficiency is lower during flood events compared to during baseflow periods, flood events contribute significantly to bulk nutrient removal, whereas bulk removal during baseflow periods is less. This is due to the fact that nutrient supply is larger during flood events; this trend is even stronger in large rivers. However, the efficiency of removal during both periods decreases in larger rivers, however, due to (i) increasing flow velocities and thus decreasing residence time, and (ii) increasing flow depth, and thus decreasing nutrient uptake rates. Besides nutrient removal processes can be divided into two parts: in the main channel and in the hyporheic transient storage zone. When assessing their relative contributions the size of the transient storage zone is a dominant control, followed by uptake rates in the main channel and in the transient storage zone. Increasing size of the transient storage zone with downstream distance affects the relative contributions to nutrient removal of the water column and the transient storage zone, which also impacts the way nutrient removal rates scale with increasing size of rivers. Intra-annual hydrologic variability has a significant impact on removal rates at all scales: the more variable the streamflow is, compared to mean discharge, the less nutrient is removed in the channel network. A scale-independent first order uptake coefficient, ke, estimated from model simulations, is highly dependent on the

  6. Optimisation of LiDAR derived terrain models for river flow modelling

    Directory of Open Access Journals (Sweden)

    G. Mandlburger

    2008-12-01

    Full Text Available Airborne LiDAR (Light Detection And Ranging combines cost efficiency, high degree of automation, high point density of typically 1–10 points per m2 and height accuracy of better than ±15 cm. For all these reasons LiDAR is particularly suitable for deriving precise Digital Terrain Models (DTM as geometric basis for hydrodynamic-numerical (HN simulations. The application of LiDAR for river flow modelling requires a series of preprocessing steps. Terrain points have to be filtered and merged with river bed data, e.g. from echo sounding. Then, a smooth Digital Terrain Model of the Watercourse (DTM-W needs to be derived, preferably considering the random measurement error during surface interpolation. In a subsequent step, a hydraulic computation mesh has to be constructed. Hydraulic simulation software is often restricted to a limited number of nodes and elements, thus, data reduction and data conditioning of the high resolution LiDAR DTM-W becomes necessary. We will present a DTM thinning approach based on adaptive TIN refinement which allows a very effective compression of the point data (more than 95% in flood plains and up to 90% in steep areas while preserving the most relevant topographic features (height tolerance ±20 cm. Traditional hydraulic mesh generators focus primarily on physical aspects of the computation grid like aspect ratio, expansion ratio and angle criterion. They often neglect the detailed shape of the topography as provided by LiDAR data. In contrast, our approach considers both the high geometric resolution of the LiDAR data and additional mesh quality parameters. It will be shown that the modelling results (flood extents, flow velocities, etc. can vary remarkably by the availability of surface details. Thus, the inclusion of such geometric details in the hydraulic computation meshes will gain importance for river flow modelling in the future.

  7. Impact of Lake Gopło on low-flow regime of the upper Noteć river

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    Tomaszewski Edmund

    2016-12-01

    Full Text Available The main aim of this study is to make an assessment of the impact of Lake Gopło on a river low-flow regime. Two water gauges were selected, located in an upstream and downstream position to the lake on the River Noteć. On the basis of the daily discharge series from the period 1965–1990, a group of low-flow regime estimators was computed. Analyses involved various aspects of minimum flows and drought streamflow deficits. Comparison of the data between both gauging stations showed the extent of the influence of water management on Lake Gopło on low-flow regime transformation in the River Noteć.

  8. Vegetation Phenology and Intensity as a Function of Climate and River Flows for an Ephemeral Desert River, 2000 to 2010, Using MODIS Satellite Data

    Science.gov (United States)

    Nguyen, U.; Nagler, P. L.; Glenn, E. P.; Van Riper, C., III

    2011-12-01

    The San Pedro river, located along Sonoran and Chihuahuan desert, is one of the most biologically diverse ecosystems in the Rocky mountains of the Southwestern United States. Vegetation dynamics related to seasonal changes may affect the life and migration of many wildlife species. Furthermore, vegetation density is related to surface flows in the river and depth to groundwater, which vary year to year. The MODIS Vegetation Index products (EVI and NDVI) were used to monitor vegetation dynamics during 10 years (2000-2010) to examine the impact of climatic conditions (such as temperature from LST, precipitation from PRISM and rive flows from gaga data) on the onset of greenness, senescence, and maximum vegetation density. The phenology profiles from time series data and relationships between vegetation index and temperature not only show seasonal changes but also respond to moisture stress on vegetation in the riparian areas of the San Pedro River.

  9. Contrasting fish assemblages in free-flowing and impounded tributaries to the Upper Delaware River: Implications for conserving biodiversity

    Science.gov (United States)

    Baldigo, Barry P.; Delucia, Mari-Beth; Keller, Walter D.; Schuler, George E.; Apse, Colin D.; Moberg, Tara

    2015-01-01

    The Neversink River and the Beaver Kill in southeastern New York are major tributaries to the Delaware River, the longest undammed river east of the Mississippi. While the Beaver Kill is free flowing for its entire length, the Neversink River is subdivided by the Neversink Reservoir, which likely affects the diversity of local fish assemblages and health of aquatic ecosystems. The reservoir is an important part of the New York City waster-supply system that provides drinking water to more than 9 million people. Fish population and community data from recent quantitative surveys at comparable sites in both basins were assessed to characterize the differences between free-flowing and impounded rivers and the extent of reservoir effects to improve our capacity to define ecosystems responses that two modified flow-release programs (implemented in 2007 and 2011) should produce in the Neversink River. In general, the continuum of changes in fish assemblages which normally occur between headwaters and mouth was relatively uninterrupted in the Beaver Kill, but disrupted by the mid-basin impoundment in the Neversink River. Fish assemblages were also adversely affected at several acidified sites in the upper Neversink River, but not at most sites assessed herein. The reservoir clearly excluded diadromous species from the upper sub-basin, but it also substantially reduced community richness, diversity, and biomass at several mid-basin sites immediately downstream from the impoundment. There results will aid future attempts to determine if fish assemblages respond to more natural, yet highly regulated, flow regimes in the Neversink River. More important, knowledge gained from this study can help optimize use of valuable water resources while promoting species of special concern, such as American eel (Anguilla rostrata) and conserving biodiversity in Catskill Mountain streams.

  10. Modeling the Effects of Changing Seasonal River Flow Rates on the Mixing of Reverse Osmosis Plant Effluent into the Pasquotank River in North Carolina

    Science.gov (United States)

    Fischer, K. M.; Hankinson, S. D.

    2004-12-01

    The goal of this research, begun Fall 2004, is to assess the seasonal impact of effluent from a reverse osmosis (RO) plant on the water of the Pasquotank River, a trunk river of Albemarle Sound in northeast North Carolina. Currently, the plant discharges about 103,000 gallons of high salinity (16 ppt) processed groundwater into Chantilly Bay in the Pasquotank River (0-3 ppt, depending on season) over an eight-hour operational day. The impact of the RO effluent on water chemistry and physical properties along the river bottom depends on the flow rate of the river. The Pasquotank is slower flowing (anecdotally, reverse flowing at times) during the generally dry summer season and faster flowing during the rainy winter season. This varying river flow rate may result in various effluent zones: a pool of effluent on the riverbed, a plume of effluent dissipating with downstream distance, or a minimal effluent signal near the outlet manifold. Modeling of seasonal data for the current rate of effluent discharge allows prediction of the effects of tripling the daily volume of RO plant discharge through round-the-clock plant operation, an outcome that seems likely in the near future due to residential growth in the county served by the plant. Data from fall and early winter 2004 will be presented. Water parameters (salinity/conductivity, temperature, pH, turbidity, Secchi depth, dissolved oxygen content, and dissolved major cation concentrations) are measured biweekly at nine surface stations (three water depths at each station) in the general vicinity of the effluent discharge outlet. Similar parameters are measured biweekly for Pasquotank River water at two stations upstream and two stations downstream of the outlet. River flow rates and discharge rates are measured weekly. The results of modeling using a two-end member mixing model and a normative analysis treatment will be presented. Additionally, modeling results for various possible changes (relocation of discharge

  11. Transthoracic coronary flow reserve and dobutamine derived myocardial function: a 6-month evaluation after successful coronary angioplasty

    Directory of Open Access Journals (Sweden)

    Pardo Moira

    2004-12-01

    Full Text Available Abstract After percutaneous transluminal coronary angioplasty (PTCA, stress-echocardiography and gated single photon emission computerized tomography (g-SPECT are usually performed but both tools have technical limitations. The present study evaluated results of PTCA of left anterior descending artery (LAD six months after PTCA, by combining transthoracic Doppler coronary flow reserve (CFR and color Tissue Doppler (C-TD dobutamine stress. Six months after PTCA of LAD, 24 men, free of angiographic evidence of restenosis, underwent standard Doppler-echocardiography, transthoracic CFR of distal LAD (hyperemic to basal diastolic coronary flow ratio and C-TD at rest and during dobutamine stress to quantify myocardial systolic (Sm and diastolic (Em and Am, Em/Am ratio peak velocities in middle posterior septum. Patients with myocardial infarction, coronary stenosis of non-LAD territory and heart failure were excluded. According to dipyridamole g-SPECT, 13 patients had normal perfusion and 11 with perfusion defects. The 2 groups were comparable for age, wall motion score index (WMSI and C-TD at rest. However, patients with perfusion defects had lower CFR (2.11 ± 0.4 versus 2.87 ± 0.6, p m at high-dose dobutamine (p m of middle septum (r = 0.55, p In conclusion, even in absence of epicardial coronary restenosis, stress perfusion imaging reflects a physiologic impairment in coronary microcirculation function whose magnitude is associated with the degree of regional functional impairment detectable by C-TD.

  12. Evaluation of hydrological methods to obtain environmental flows in the Tulua River, Colombia

    Energy Technology Data Exchange (ETDEWEB)

    Castro-Herendia, Lina Mabel; Carvajal-Escobar, Yesid [Universidad del Valle (Colombia)

    2008-10-15

    Most rivers in the world have been modified in their structure, form, composition or function, which has caused severe ecological and environmental alterations, such as pollution, a dramatic reduction in flow, and less environmental and recreational services. To reduce the human impact on the hydrological systems, new policies of sustainability are being developed worldwide. The aim is the sustainable and responsible use of water resources. One of them is the development and implementation of techniques to estimate environmental flows (EF) and environmental regimen flow regime (EFR). In this article, some hydrological methods used to determine EF and EFR are explained, and their implementation in the Tulua River (Valle del Cauca-Colombia). Simulation on HEC-RAS of the given flows was performed in order to examine flow and level variability. The result showed that most hydrological methods demand constant flows over time, and are specific for certain places and aquatic species, but some others calculate a variable EFR throughout the year and with some modifications can be used in Colombian Rivers. [Spanish] La mayoria de los rios en el mundo han sido modificados en su estructura, forma, composicion y funcionamiento, lo que ha provocado graves alteraciones ecologicas y ambientales, como contaminacion, disminucion excesiva de caudales, y perdida de los servicios ambientales y recreativos, entre otras. Es por esto que para reducir los impactos generadores por las actividades humanas en las cuencas, se estan desarrollando nuevas politicas en el mundo para el uso sostenible y responsable del recurso hidrico, entre las cuales se tienen el desarrollo y la aplicacion de tecnicas de estimacion de caudales ambientales (QA) o de regimenes de caudal ambiental (RQA). En el presente trabajo se explican algunos de los metodos hidrologicos usados para determinar el QA y el RQA, y se muestra la aplicacion de los mismos rios Tulua (Valle del Cauca, Colombia), y su posterior

  13. Influence of snow pack and soil water dynamics on river flows in un-glaciarized Himalayan catchments.

    Science.gov (United States)

    Eeckman, Judith; Neppel, Luc; Chevalier, Pierre; Delclaux, François; Boone, Aaron

    2016-04-01

    In the Central Himalayas, it is generally accepted that 80 % of the annual precipitation occurs during the monsoon months (June - September). However, surveys with local populations show that surface water is available throughout the year. The main question then is to identify the origin of these surface flows. One hypothesis proposes that they are provided by glacial melt during the dry season. However, on the one hand, this historically "permanent" supply is also observed in catchments with little or no glacial contribution, and on the other hand, annual volumes cannot be totally explained by the glacial mass balances currently monitored. Therefore, a better understanding of the hydrological processes is needed for quantifying the influence of the inter-seasonal surface (snow) and sub-surface storage on surface flows outside of the monsoon season. One solution consists in the application of modelling tools. However, simulations for Himalayan catchments are limited due to a lack of knowledge regarding their hydrological behaviour. The main source of uncertainty in poorly monitored environments is the scarcity of observations, which can be used for model calibration and evaluation. In this study, physically-based modelling with the ISBA Soil-Vegetation-Atmosphere transfer scheme is applied to small catchments whose physical characteristics are well studied, therefore this approach could constitute an interesting way for understanding hydrological systems. For that purpose, two small slope catchments selected in the Dudh Koshi River basin (Eastern Nepal), which represent high and mid-mountain environments, are studied in order to evaluate the spatial variability of the studied processes. They are equipped with 6 stations for air temperature and precipitation observations. A distributed approach allows a better representation of the spatial variation of hydro-climatic processes. Moreover, the descriptions of surfaces currently available at global scales are enhanced

  14. IVERINE FLOW OBSERVATIONS AND MODELING: Sensitivity of Delft3D River Model to Bathymetric Variability

    Science.gov (United States)

    2011-01-01

    equipped backpack and with an echosounder-equipped electric kayak . The meandering reach (Figure 2) is a deep (~10m) channel with flows around 0.5m/s...Kootenai River, ID on 12-16 August 2010. The study reach contained a number of natural channel features, such as a pool-riffle sequence and bank...irregularities, which influence transverse mixing. The dye was released at a constant rate for one hour from a kayak fixed in the center of the channel

  15. Toward Developing a Hydrodynamic Flow & Inundation Model of the Lower Pearl River

    Science.gov (United States)

    2010-01-20

    AUTHOR(S) Paul McKay, Cheryl Ann Blain 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 73-6205-A9-5 7. PERFORMING ORGANIZATION...8/98) Prescribed by ANSI Sid. Z39.18 Toward Developing a Hydrodynamic Flow and Inundation Model of the Lower Pearl River Paul McKay and Cheryl... Ekman transport due to offshore forcing or surge tied to local storm events. Both channels of the lower Pearl are bordered by extensive floodplains

  16. Assessment of spatial and temporal patterns of green and blue water flows in inland river basins in Northwest China

    Directory of Open Access Journals (Sweden)

    C. F. Zang

    2012-03-01

    Full Text Available In arid and semi-arid regions freshwater resources have become scarcer with increasing demands from socio-economic development and population growth. Until recently, water research and management in these has mainly focused on blue water but ignored green water. Here we report on spatial and temporal patterns of both blue and green water flows simulated by the Soil and Water Assessment Tool (SWAT for the Heihe river basin, the second largest inland river basin in Northwest China. Calibration and validation at two hydrological stations show good performance of the SWAT model in modelling hydrological processes. The total green and blue water flows were 22.09 billion m3 in the 2000s for the Heihe river basin. Blue water flows are larger in upstream sub-basins than in downstream sub-basins mainly due to high precipitation and large areas of glaciers in upstream. Green water flows are distributed more homogeneously among different sub-basins. The green water coefficient was 88.0% in the 2000s for the entire river basin, varying from around 80–90% in up- and mid-stream sub-basins to above 95% in downstream sub-basins. This is much higher than reported green water coefficient in many other river basins. The spatial patterns of green water coefficient were closely linked to dominant land covers (e.g. glaciers in upstream and desert in downstream and climate conditions (e.g. high precipitation in upstream and low precipitation in downstream. There are no clear consistent historical trends of change in green and blue water flows and green water coefficient at both the river basin and sub-basin levels. This study provides insights into green and blue water endowments for the entire Heihe river basin at sub-basin level. The results are helpful for formulating reasonable water policies to improve water resources management in the inland river basins of China.

  17. River flow is critical for vegetation dynamics: Lessons from multi-scale analysis in a hyper-arid endorheic basin.

    Science.gov (United States)

    Shen, Qin; Gao, Guangyao; Lü, Yihe; Wang, Shuai; Jiang, Xiaohui; Fu, Bojie

    2017-12-15

    Knowledge of the spatio-temporal responses of vegetation dynamics to hydro-climatic factors is important to assess ecological restoration efforts in arid and semiarid areas. In this study, the vegetation dynamics during 2000-2015 were investigated in the downstream area of the Heihe River Basin (HRB) in Northwest China where an ecological water diversion project (EWDP) commenced in 2000. The spatio-temporal relationships between vegetation cover and climatic factors (precipitation and temperature) and available water resources (river flow and groundwater) were determined. The results indicated that the mean growing season NDVI increased significantly during the period of 2000-2015, and the area of East Juyan Lake (EJL) enlarged to 36.4km(2) in 2010. The scale effect of the relationships between NDVI and hydro-climatic factors was obvious. At the catchment scale, changes of NDVI were not significantly correlated with climatic factors, but significantly related with the antecedent 1-year river flow. River flow played an important role in vegetation growth within approximately 2000m distance from the river bank. At the pixel scale, the changes of NDVI were significantly positive with temperature and river flow in 17.40% and 7.14% of the study area, respectively, whereas significant relationship between NDVI and precipitation occurred in only 0.65% of study area. The suitable water table depth for vegetation growth was between 1.8 and 3.5m. The increased river flow and recovered groundwater due to the EWDP were critical for the improvement of vegetation cover, whereas the riparian vegetation degraded along some parts of the river bank. It is important to improve integrated watershed management with consideration of spatio-temporal lagged hydro-ecological connections in the study area. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Impact of climate change and anthropogenic activities on stream flow and sediment discharge in the Wei River basin, China

    Directory of Open Access Journals (Sweden)

    P. Gao

    2012-03-01

    Full Text Available Reduced stream flow and increased sediment discharge are a major concern in the Yellow River basin of China which supplies water for agriculture, industry and the growing populations located along the river. Similar concerns exist in the Wei River basin which is the largest tributary of the Yellow River basin and comprises the highly eroded Loess Plateau. Better understanding of the drivers of stream flow and sediment discharge dynamics in the Wei River basin is needed for development of effective management strategies for the region and entire Yellow River basin. In this regard we analysed long term trends for water and sediment discharge during the flood season in the Wei River basin, China. Stream flow and sediment discharge data for 1932 to 2008 from existing hydrological stations located in two sub-catchments and at two points in the Wei River were analysed. Precipitation data were analysed from corresponding meteorological stations. We identified change points or transition years for the trends by the Pettitt method and, using double mass curves, we diagnosed whether they were caused by precipitation changes, human intervention, or both. We found significant decreasing trends for stream flow and sediment discharge during the flood season in both sub-catchments and in the Wei River itself. Change-point analyses further revealed that transition years existed and that rapid decline in stream flow began in 1968 (P<0.01, and that sediment discharge began in 1981 (P<0.01 in the main river. In the two sub-catchments, the transition years were 1985 (P<0.01 and 1994 (P<0.05 for water discharge, and 1978 and 1979 for sediment discharge (P<0.05, respectively. The impact of precipitation or human activity on the reduction amount after the transition years was estimated by double mass curves of precipitation vs stream flow (sediment. For reductions in stream flow and sediment discharge, the contribution rate of human

  19. Closing the irrigation deficit in Cambodia: Implications for transboundary impacts on groundwater and Mekong River flow

    Science.gov (United States)

    Erban, Laura E.; Gorelick, Steven M.

    2016-04-01

    Rice production in Cambodia, essential to food security and exports, is largely limited to the wet season. The vast majority (96%) of land planted with rice during the wet season remains fallow during the dry season. This is in large part due to lack of irrigation capacity, increases in which would entail significant consequences for Cambodia and Vietnam, located downstream on the Mekong River. Here we quantify the extent of the dry season "deficit" area in the Cambodian Mekong River catchment, using a recent agricultural survey and our analysis of MODIS satellite data. Irrigation of this land for rice production would require a volume of water up to 31% of dry season Mekong River flow to Vietnam. However, the two countries share an aquifer system in the Mekong Delta, where irrigation demand is increasingly met by groundwater. We estimate expansion rates of groundwater-irrigated land to be >10% per year in the Cambodian Delta using LANDSAT satellite data and simulate the effects of future expansion on groundwater levels over a 25-year period. If groundwater irrigation continues to expand at current rates, the water table will drop below the lift limit of suction pump wells, used for domestic supply by >1.5 million people, throughout much of the area within 15 years. Extensive groundwater irrigation jeopardizes access for shallow domestic water supply wells, raises the costs of pumping for all groundwater users, and may exacerbate arsenic contamination and land subsidence that are already widespread hazards in the region.

  20. A long range dependent model with nonlinear innovations for simulating daily river flows

    Directory of Open Access Journals (Sweden)

    P. Elek

    2004-01-01

    Full Text Available We present the analysis aimed at the estimation of flood risks of Tisza River in Hungary on the basis of daily river discharge data registered in the last 100 years. The deseasonalised series has skewed and leptokurtic distribution and various methods suggest that it possesses substantial long memory. This motivates the attempt to fit a fractional ARIMA model with non-Gaussian innovations as a first step. Synthetic streamflow series can then be generated from the bootstrapped innovations. However, there remains a significant difference between the empirical and the synthetic density functions as well as the quantiles. This brings attention to the fact that the innovations are not independent, both their squares and absolute values are autocorrelated. Furthermore, the innovations display non-seasonal periods of high and low variances. This behaviour is characteristic to generalised autoregressive conditional heteroscedastic (GARCH models. However, when innovations are simulated as GARCH processes, the quantiles and extremes of the discharge series are heavily overestimated. Therefore we suggest to fit a smooth transition GARCH-process to the innovations. In a standard GARCH model the dependence of the variance on the lagged innovation is quadratic whereas in our proposed model it is a bounded function. While preserving long memory and eliminating the correlation from both the generating noise and from its square, the new model is superior to the previously mentioned ones in approximating the probability density, the high quantiles and the extremal behaviour of the empirical river flows.

  1. Assessing juvenile native fish demographic responses to a steady flow experiment in a large regulated river

    Science.gov (United States)

    Finch, Colton G.; Pine, William E.; Yackulic, Charles B.; Dodrill, Michael J.; Yard, Michael D.; Gerig, Brandon S.; Coggins,, Lewis G.; Korman, Josh

    2016-01-01

    The Colorado River below Glen Canyon Dam, Arizona, is part of an adaptive management programme which optimizes dam operations to improve various resources in the downstream ecosystem within Grand Canyon. Understanding how populations of federally endangered humpback chub Gila cypha respond to these dam operations is a high priority. Here, we test hypotheses concerning temporal variation in juvenile humpback chub apparent survival rates and abundance by comparing estimates between hydropeaking and steady discharge regimes over a 3-year period (July 2009–July 2012). The most supported model ignored flow type (steady vs hydropeaking) and estimated a declining trend in daily apparent survival rate across years (99.90%, 99.79% and 99.67% for 2009, 2010 and 2011, respectively). Corresponding abundance of juvenile humpback chub increased temporally; open population model estimates ranged from 615 to 2802 individuals/km, and closed model estimates ranged from 94 to 1515 individuals/km. These changes in apparent survival and abundance may reflect broader trends, or simply represent inter-annual variation. Important findings include (i) juvenile humpback chub are currently surviving and recruiting in the mainstem Colorado River with increasing abundance; (ii) apparent survival does not benefit from steady fall discharges from Glen Canyon Dam; and (iii) direct assessment of demographic parameters for juvenile endangered fish are possible and can rapidly inform management actions in regulated rivers.

  2. Water-sediment flow models for river reaches sediment related pollution control.

    Science.gov (United States)

    Sil, Briti Sundar; Choudhury, Parthasarathi

    2012-07-01

    Hybrid water-sediment flow models for river reaches have been for predicting sediment and sediment related pollutions in water courses. The models are developed by combining sediment rating model and the Muskingum model applicable for a reach. The models incorporate sediment concentration and water discharge variables for a river reach; allow defining downstream sediment rating curve in terms of upstream water discharges. The model is useful in generating sediment concentration graph for a station having no water discharge records. The hybrid models provide forecasting forms that can be used to forecast downstream sediment concentration/water discharges 2kx time unit ahead. The forecasting models are useful for applications in real time namely, in the real time management of sediment related pollution in water courses and in issuing flood warning. Integration of sediment rating model and the Muskingum model increases model parameters and nonlinearity requiring efficient estimation technique for parameter identification. To identify parameters in the hybrid models genetic algorithm (GA) based optimization technique can be used. The new model relies on the Muskingum model, obey continuity requirement and the parameters can be used in the Muskingum model with water discharges to estimate/predict downstream water discharge values. The proposed model formulations are demonstrated for simulating and forecasting sediment concentration and water discharges in the Mississippi River Basin, USA. Model parameters are estimated using non-dominated sorting Genetic Algorithm II (NSGA-II). Model results show satisfactory model performances.

  3. Groundwater-flow model for the Wood River Valley aquifer system, south-central Idaho

    Science.gov (United States)

    Fisher, Jason C.; Bartolino, James R.; Wylie, Allan H.; Sukow, Jennifer; McVay, Michael

    2016-06-27

    A three-dimensional numerical model of groundwater flow was developed for the Wood River Valley (WRV) aquifer system, Idaho, to evaluate groundwater and surface-water availability at the regional scale. This mountain valley is located in Blaine County and has a drainage area of about 2,300 square kilometers (888 square miles). The model described in this report can serve as a tool for water-rights administration and water-resource management and planning. The model was completed with support from the Idaho Department of Water Resources, and is part of an ongoing U.S. Geological Survey effort to characterize the groundwater resources of the WRV. A highly reproducible approach was taken for constructing the WRV groundwater-flow model. The collection of datasets, source code, and processing instructions used to construct and analyze the model was distributed as an R statistical-computing and graphics package.

  4. Creepy landscapes : river sediment entrainment develops granular flow rheology on creeping bed.

    Science.gov (United States)

    Prancevic, J.; Chatanantavet, P.; Ortiz, C. P.; Houssais, M.; Durian, D. J.; Jerolmack, D. J.

    2015-12-01

    To predict rates of river sediment transport, one must first address the zeroth-order question: when does sediment move? The concept and determination of the critical fluid shear stress remains hazy, as observing particle motion and determining sediment flux becomes increasingly hard in its vicinity. To tackle this problem, we designed a novel annular flume experiment - reproducing an infinite river channel - where the refractive index of particles and the fluid are matched. The fluid is dyed with a fluorescent powder and a green laser sheet illuminates the fluid only, allowing us to observe particle displacements in a vertical plane. Experiments are designed to highlight the basic granular interactions of sediment transport while suppressing the complicating effects of turbulence; accordingly, particles are uniform spheres and Reynolds numbers are of order 1. We have performed sediment transport measurements close to the onset of particle motion, at steady state, and over long enough time to record averaged rheological behavior of particles. We find that particles entrained by a fluid exhibit successively from top to bottom: a suspension regime, a dense granular flow regime, and - instead of a static bed - a creeping regime. Data from experiments at a range of fluid stresses can be collapsed onto one universal rheologic curve that indicates the effective friction is a monotonic function of a dimensionless number called the viscous number. These data are in remarkable agreement with the local rheology model proposed by Boyer et al., which means that dense granular flows, suspensions and bed-load transport are unified under a common frictional flow law. Importantly, we observe slow creeping of the granular bed even in the absence of bed load, at fluid stresses that are below the apparent critical value. This last observation challenges the classical definition of the onset of sediment transport, and points to a continuous transition from quasi-static deformation to

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

    Science.gov (United States)

    Sauquet, Eric

    2015-04-01

    . A model of water management similar to the tools used by Electricité De France was calibrated to simulate the behavior of the three reservoirs Serre-Ponçon, Castillon, Sainte-Croix on present-day conditions. This model simulates water releases from reservoir under constraints imposed by rule curves, ecological flows downstream to the dams and water levels in summer for recreational purposes. The results demonstrate the relatively good performance of this simplified model and its ability to represent the influence of reservoir operations on the natural hydrological river flow regime, the decision-making involved in water management and the interactions at regional scale. Four territorial socio-economic scenarios have been also elaborated with the help of stake holders to project water needs in the 2050s for the area supplied with water from the Durance River basin. This presentation will focus on the specific tools developed within the project to simulate water management and water abstractions. The main conclusions related to the risk of water shortage in the 2050s and the level of satisfaction for each water use will be also discussed.

  6. Frequency and magnitude of debris flows on Cheekye River, British Columbia

    Science.gov (United States)

    Jakob, M.; Friele, P.

    2010-01-01

    Natural hazard and risk assessments are predicated on a detailed understanding of the relationship between frequency and magnitude of the hazardous process under investigation. When information is sought from the deep past (i.e., several thousand years), continuous event records do not exist and the researcher has to rely on proxy data to develop the frequency-magnitude ( F- M) model. Such work is often prohibitively expensive and few well-researched examples for mass movement are available worldwide. The Cheekye fan is a desirable location for land development and has a depth and breadth of previous research unprecedented on any debris-flow fan in Canada. We pursued two principal strains of research to formulate a reliable F- M relationship. The first focuses on stratigraphic analyses combined with radiometric dating and dendrochronology to reconstruct a comprehensive picture of Holocene debris-flow activity. The second approach examines hydrological limitations of rock avalanche evolution into debris flows through either entrainment of saturated sediments or by failure of a landslide-generated dam and upstream impoundment. We thus hypothesize that debris flows from Cheekye River can be separated into two quasi-homogenous populations: those that are typically triggered by relatively small debris avalanches, slumps, or rock falls or simply by progressive bulking of in-stream erodible sediments; and those that are thought to result from transformation of rock avalanches. Our work suggests that debris flows exceeding some 3 million m 3 in volume are unlikely to reach the Cheekye fan as a result of limited water available to fully fluidize a rock avalanche. This analysis has also demonstrated that in order to arrive at reasonable estimates for the frequency and magnitude of debris flows on a complex alluvial fan significant multidisciplinary efforts are required. Without the significant precursor investigations and the additional efforts of this study, life and

  7. Surface flow observations from a gauge-cam station on the Tiber river

    Science.gov (United States)

    Tauro, Flavia; Porfiri, Maurizio; Petroselli, Andrea; Grimaldi, Salvatore

    2016-04-01

    Understanding the kinematic organization of natural water bodies is central to hydrology and environmental engineering practice. Reliable and continuous flow observations are essential to comprehend flood generation and propagation mechanisms, erosion dynamics, sediment transport, and drainage network evolution. In engineering practice, flood warning systems largely rely on real-time discharge measurements, and flow velocity monitoring is important for the design and management of hydraulic structures, such as reservoirs and hydropower plants. Traditionally, gauging stations have been equipped with water level meters, and stage-discharge relationships (rating curves) have been established through few direct discharge measurements. Only in rare instances, monitoring stations have integrated radar technology for local measurement of surface flow velocity. Establishing accurate rating curves depends on the availability of a comprehensive range of discharge values, including measurements recorded during extreme events. However, discharge values during high-flow events are often difficult or even impossible to obtain, thereby hampering the reliability of discharge predictions. Fully remote observations have been enabled in the past ten years through optics-based velocimetry techniques. Such methodologies enable the estimation of the surface flow velocity field over extended regions from the motion of naturally occurring debris or floaters dragged by the current. Resting on the potential demonstrated by such approaches, here, we present a novel permanent gauge-cam station for the observation of the flow velocity field in the Tiber river. This new station captures one-minute videos every 10 minutes over an area of up to 20.6 × 15.5m2. In a feasibility study, we demonstrate that experimental images analyzed via particle tracking velocimetry and particle image velocimetry can be used to obtain accurate surface flow velocity estimations in close agreement with radar records

  8. Effect of Flow and Fluid Structures on the Performance of Vertical River Hydrokinetic Turbines

    Science.gov (United States)

    Birjandi, Amir Hossein

    Field and laboratory measurements characterize the performance of vertical axis hydrokinetic turbines operating in uniform and non-uniform inflow conditions for river applications. High sampling frequency velocity measurements, taken at 200 Hz upstream of a stopped and operating 25-kW H-type vertical axis hydrokinetic turbine in the Winnipeg River, show the existence of large eddies with an order of magnitude of the turbine's diameter. Scaling laws allow modeling river conditions in the laboratory for more detailed investigations. A small-scale, 30 cm diameter, squirrel-cage vertical turbine designed, manufactured and equipped with a torque and position sensors is investigated for the detail behavior of the turbine subjected to different inflow conditions in a laboratory setting to study the effect of flow and fluid structures. The adjustable design of the laboratory turbine enables operations with different solidities, 0.33 and 0.67, and preset pitch angles, 0°, +/-2.5°, +/-5° and +/-10°. Tests are first performed with uniform inflow condition to measure the sensitivity of the turbine to solidity, preset pitch angle, free-surface, and Reynolds number to obtain the optimum operating conditions. During the free-surface testing a novel dimensionless coefficient, clearance coefficient, is introduced that relates the change in turbine efficiency with change in the free-surface height. High-speed imaging at 500 fps of semi-submerged blades visualizes the vortex-shedding pattern behind the blades and air entrainment. High-speed imaging results of large eddy pattern behind the vertical turbine are consistent with theory and measurements. Subsequently, cylinders of different diameters create non-uniform inflow conditions in the water tunnel by placing them at different longitudinal and lateral locations upstream of the model turbine. Thus, the effects of non-uniform inflow generated under controlled settings shows the impact of eddies and wake on the turbine

  9. Impact of climate change and anthropogenic activities on stream flow and sediment discharge in the Wei River basin, China

    Directory of Open Access Journals (Sweden)

    P. Gao

    2013-03-01

    Full Text Available Reduced stream flow and increased sediment discharge are a major concern in the Yellow River basin of China, which supplies water for agriculture, industry and the growing populations located along the river. Similar concerns exist in the Wei River basin, which is the largest tributary of the Yellow River basin and comprises the highly eroded Loess Plateau. Better understanding of the drivers of stream flow and sediment discharge dynamics in the Wei River basin is needed for development of effective management strategies for the region and entire Yellow River basin. In this regard we analysed long-term trends for water and sediment discharge during the flood season in the Wei River basin, China. Stream flow and sediment discharge data for 1932 to 2008 from existing hydrological stations located in two subcatchments and at two points in the Wei River were analysed. Precipitation and air temperature data were analysed from corresponding meteorological stations. We identified change-points or transition years for the trends by the Pettitt method and, using double mass curves, we diagnosed whether they were caused by precipitation changes, human intervention, or both. We found significant decreasing trends for stream flow and sediment discharge during the flood season in both subcatchments and in the Wei River itself. Change-point analyses further revealed that transition years existed and that rapid decline in stream flow began in 1968 (P P P P P < 0.05, respectively. The impact of precipitation or human activity on the reduction amount after the transition years was estimated by double mass curves of precipitation vs. stream flow (sediment. For reductions in stream flow and sediment discharge, the contribution rate of human activity was found to be 82.80 and 95.56%, respectively, and was significantly stronger than the contribution rate of precipitation. This evidence clearly suggests that, in the absence of significant decreases in precipitation

  10. Summary of environmental flow monitoring for the Sustainable Rivers Project on the Middle Fork Willamette and McKenzie Rivers, western Oregon, 2014–15

    Science.gov (United States)

    Jones, Krista L.; Mangano, Joseph F.; Wallick, J. Rose; Bervid, Heather D.; Olson, Melissa; Keith, Mackenzie K.; Bach, Leslie

    2016-11-07

    This report presents the results of an ongoing environmental flow monitoring study by The Nature Conservancy (TNC), U.S. Army Corps of Engineers (USACE), and U.S. Geological Survey in support of the Sustainable Rivers Project (SRP) of TNC and USACE. The overarching goal of this study is to evaluate and characterize relations between streamflow, geomorphic processes, and black cottonwood (Populus trichocarpa) recruitment on the Middle Fork Willamette and McKenzie Rivers, western Oregon, that were hypothesized in earlier investigations. The SRP can use this information to plan future monitoring and scientific investigations, and to help mitigate the effects of dam operations on streamflow regimes, geomorphic processes, and biological communities, such as black cottonwood forests, in consultation with regional experts. The four tasks of this study were to:Compare the hydrograph from Water Year (WY) 2015 with hydrographs from WYs 2000–14 and the SRP flow recommendations,Assess short-term and system-wide changes in channel features and vegetation throughout the alluvial valley section of the Middle Fork Willamette River (2005–12),Examine changes in channel features and vegetation over two decades (1994–2014) for two short mapping zones on the Middle Fork Willamette and McKenzie Rivers, andComplete a field investigation of summer stage and the growth of black cottonwood and other vegetation on the Middle Fork Willamette and McKenzie Rivers in summer 2015.

  11. Morphology and River Monitoring - Topobathymetry as a new level of monitoring and managing the morphology at the river Isar, Munich after the flood flows 2013

    Science.gov (United States)

    Steinbacher, Frank; Schaufuß, Daniela; Aufleger, Markus; Baran, Ramona; Dobler, Wolfgang

    2014-05-01

    Topobathymetry is a new approach for the very detailed bathymetric survey of water bodies (rivers, lakes, nearshore) as well as the topographic side in a same resolution. This technique was made possible within the scope of a research project between the University of Innsbruck and Riegl LMS (Horn, Lower Austria). This airborne-operated, water-penetrating laser system capturing both sides of water's edge is considered as a technical revolution for the comprehensive and simultaneous survey and research of our countryside. Monitoring our waters area-wide and with a point density lager 20 points/m² a new data level is reached for managing them and performing research on hydraulics and morphology. By now operating the system over three years and due to the flood flows in Austria and Germany in 2013 a dataset before and after the effects of the flood could be analyzed at the river Isar. The changes monitored at the river Isar due to the flood flow will be presented as well as the new possibilities in calibrating hydro- morphologic numerical models. The project offers the city of Munich new knowledge and ways in managing inner-city river structures and planning the future of the close-to-nature approaches at the river Isar.

  12. Comparison of the molecular mass and optical properties of colored dissolved organic material in two rivers and coastal waters by flow field-flow fractionation.

    Science.gov (United States)

    Zanardi-Lamardo, Eliete; Clark, Catherine D; Moore, Cynthia A; Zika, Rod G

    2002-07-01

    Colored dissolved organic material (CDOM) is an important sunlight absorbing substance affecting the optical properties of natural waters. However, little is known about its structural and optical properties mainly due to its complex matrix and the limitation of the techniques available. A comparison of two southwestern Florida rivers [the Caloosahatchee River (CR) and the Shark River (SR)] was done in terms of molecular mass (MM) and diffusion coefficients (D). The novel technique Frit inlet/frit outlet-flow field-flow fractionation (FIFO-FIFFF) with absorbance and fluorescence detectors was used to determine these properties. The SR receives organic material from the Everglades. By contrast, the CR arises from Lake Okeechobee in central Florida, receiving anthropogenic inputs, farming runoff, and natural organics. Both rivers discharge to the Gulf of Mexico. Fluorescence identified, for both rivers, two different MM distributions in low salinity water samples: the first was centered at approximately 1.7 kDa (CR) and approximately 2 kDa (SR); the second centered at approximately 13 kDa for both rivers, which disappeared gradually in the river plumes to below detection limit in coastal waters. Absorbance detected only one MM distribution centered at approximately 2 kDa (CR) and 2.2-2.4 kDa (SR). Fluorescence in general peaked at a lower MM than absorbance, suggesting a different size distribution for fluorophores vs chromophores. A photochemical study showed that, after sunlight, irradiated freshwater samples have similar characteristics to more marine waters, including a shift in MM distribution of chromophores. The differences observed between the rivers in the optical characteristics, MM distributions, and D values suggest that the CDOM sources, physical, and photochemical degradation processes are different for these two rivers.

  13. CHNHYD: a channel hydrodynamic model for simulating flows and water surface elevations in a stream/river network

    Energy Technology Data Exchange (ETDEWEB)

    Yeh, G.T.

    1982-01-01

    A description is given of the development of a channel hydrodynamic model for simulating the behavior of flows and water surface elevations in a river network that may consist of any number of joined and branched rivers/streams, including both tidal and nontidal rivers. The model employs a numerical method, an integrated compartment method (ICM). The basic procedures of the ICM are first t