Real-Time Reservoir Operation For Drought Management Considering Ensemble Streamflow Predictions Derived From Operational Forecasts Of Precipitation In Japan

Ensemble hydrological predictions are considered to be useful for robust reservoir operation as they include multiple possible hydrological scenarios in the future as well as dispersion of the predictions, from which the degree of prediction uncertainty can be estimated. Although operational ensemble hydrological predictions have been available in many regions, they have not yet been widely used in the actual reservoir management due to the difficulty in the handling such complex information. In order to facilitate effective utilization of ensemble hydrological predictions in the actual reservoir management, a real-time reservoir operation method for drought management is developed considering operational ensemble forecasts of precipitation in Japan. One-week and one-month ensemble predictions of precipitation (EPPs) with respectively 51 and 50 ensemble members provided by Japan Meteorological Agency are employed here. Firstly, an ensemble prediction of daily precipitation in the target basin is estimated for the coming one month from EPPs by using artificial neural networks (ANNs), which are developed so as to model the statistical relationships between predicted values and observed basin precipitations. An ensemble streamflow prediction is then estimated by use of Hydrological River Basin Environment Assessment Model (Hydro-BEAM), a distributed rainfall-runoff model. Reservoir operation for drought management is then optimized considering the prediction for the coming one month by using sampling stochastic dynamic programming, which can consider both the stochastic and time-series natures of the ensemble prediction, so as to minimize drought damage caused by deficit in release waters. Water release is conducted according to the optimized operation strategy, updating EPPs and ensemble streamflow prediction. The proposed method is applied to water supply operation of Sameura Reservoir in the Yoshino River basin in Japan, demonstrating effectiveness of considering operational EPPs as well as the effects of uncertainty contained in the predictions on performances of the reservoir operation

Decision Support For Flood Control Operation Of A Multi-Purpose Reservoir Considering Operational One-Week Ensemble Forecast Of Precipitation

atoMulti-purpose reservoirs, which are operated for both of flood control and water use purposes, play an important role in water resources management. Consideration of operational hydrological predictions can potentially provide an improvement in operations of a multi-purpose reservoir by allowing adaptive operation according to the predicted future condition of the reservoir and the target river basin. In this paper, a decision support tool for flood control operation of a multi-purpose reservoir considering middle-range operational ensemble prediction is proposed. One-week Ensemble Forecast of precipitation, which is provided by Japan Meteorological Agency with 51 ensemble members for the coming eight days, is considered to support decision making for conducting preliminary water release from the reservoir to secure empty storage capacity for flood control. Firstly, ensemble streamflow prediction for the coming one week is estimated from One-week Ensemble Forecast of precipitation using Hydro-BEAM, a distributed rainfall-runoff model. Reservoir states such as inflow or storage volume are then estimated for each ensemble member of streamflow prediction to decide the amount and the timing of the preliminary release for flood protection. Chance and the expected amount of recovery in water storage at the end of the flood event is also calculated for each scenario of reservoir operation to estimate the impact of the flood control operation on water supply for the long term. Trajectories of the predicted streamflows and expected reservoir states are shown to reservoir managers with the possible flood damages and the potential water deficits for the decision support of operation. The amount and the timing of the preliminary release are finally decided with consideration of expected situations and their variance taking uncertainty into account. The proposed method and the tool were applied to multi-purpose reservoirs in Japanese river basins, demonstrating their effectiveness and applicability in the real-time operation of multi-purpose reservoirs

An integrated assessment approach for fossil groundwater quality and crop water requirements in the El-Kharga Oasis, Western Desert, Egypt

Study region: The El-Kharga Oasis in the Western Desert of Egypt is selected as the study area due to its hyberarid climate condition and water scarcity. In this region, the fossil groundwater is the main water source; therefore, preserving groundwater quality and quantity is mandatory. Study focus: This study evaluated groundwater suitability for irrigation purposes and assessed the water requirements of cultivated crops to optimize the water supply in hyperarid climate regions. In total, 79 deep groundwater samples were hydrochemically tested to determine the suitability for irrigation by assessing the key water quality parameters. Spatial distribution maps of all chemical parameters, such as pH, EC, SAR, RSC, SSP, TDS, total hardness, Na+, K+, Ca++, Mg++, Fe, Mn, Cl-, and SO4—, were developed. The FAO CROPWAT 8.0 model, based on the Penman–Monteith equation, was used to forecast agricultural water requirements for three years, 2010, 2011, and 2012. New hydrological insights for the region: The groundwater had medium salinity and low sodium in 84% of the cases. In comparison, high salinity was found in 16% of the samples, indicating that groundwater can be used for many soil types with a low risk of exchangeable sodium. Except for 15 of the 79 wells, all groundwater samples had chloride concentrations less than 100 mg/l. The sulfate ion distribution map showed a low sulfate ion content in the extreme western south. The total annual irrigation water requirements of all crops for 2010, 2011 and 2012 were 199.4, 215.1, and 231.7 million m3/year, respectively, reflecting a gradual increase of approximately 16.57 million m3/total area/year due to the expansion of the cultivated area. The analysis showed that modern irrigation systems reduced the amount of irrigation water by 32% and increased the cultivated area by 45% compared to conventional irrigation methods. Severe groundwater depletion occurred during the dry season from March to July, which exacerbated the water stress in the study region. The results confirmed that the region is under water stress. Accordingly, water conservation is urgently recommended

Revisiting Flood Management Process in Transboundary Koshi River in Nepal and India

This study aims to investigate the various aspects of flood management process in the transboundary Koshi River between India and Nepal focusing on the institutional framework. The technical and administrative cause of the most disastrous and most recent flood in 2008 are discussed. Existing policies and institutional mechanism between Nepal and India on the management of the Koshi River are analyzed. In reference to such policies and institutional mechanism, lack of proper co-ordination and complex organizational structure was identified as one of the major element that has hindered the effective flood management along with other few elements. Finally, based on the experiences of the transboundary river flood management around the world as well as considering the unique nature of Koshi, different key elements that might be helpful in improving the management of floods are proposed

Estimation of field irrigation water demand based on lumped kinematic wave model considering soil moisture balance

An estimation model of farm field irrigation water demand is developed. The model is based on the lumped kinematic wave model considering soil water balance. The lumped model approach reduces the computational load in rainfall–runoff analysis and allows application to large river basins. Evapotranspiration is estimated on hourly basis by the improvement of FAO’s method. Not only water volume necessary for farm field irrigation but also the number of the water charge and its interval can be estimated by the combined use of the lumped runoff model and the hourly evapotranspiration model

Real-Time Reservoir Operation for Flood Management Considering Ensemble Streamflow Prediction and its Uncertainty

A real-time operation method of a multi-purpose reservoir for flood management considering an ensemble streamflow prediction (ESP) is investigated in this study. The ESP is derived by a distributed rainfall-runoff model from an operational ensemble prediction of precipitation. Japan Meteorological Agency’s One-week Ensemble Forecast of precipitation, which is provided every day and has 51 ensemble members of six-hour precipitations for the coming eight days, is employed here. ESPs with 51 members for the coming eight days are calculated from the ensemble predictions of basin precipitation by use of Hydrological River Basin Environment Assessment Model (Hydro-BEAM), a distributed rainfall-runoff model. Reservoir states such as release or storage are then estimated for each ensemble member of the streamflow predictions to decide the amount and the timing of preliminary release for flood protection. Chance and the expected amount of recovery in storage water at the end of the flood event are also estimated for each scenario of reservoir operation to estimate impact of the operation for flood control on that for water supply for the following period in order to help reservoir manager with making a decision on preliminary release considering the prediction and its uncertainty and variety. The presented method was applied to Nagayasuguchi Reservoir, a multi-purpose reservoir for flood and drought managements located in the Naka River basin in Japan, demonstrating the effectiveness and potential to provide useful information for real-time preliminary release operation of reservoirs.Nohara Daisuke, Nishioka Yuya, Hori Tomoharu. Real-Time Reservoir Operation for Flood Management Considering Ensemble Streamflow Prediction and its Uncertainty. In: SimHydro 2014. New Trends in Simulation. 11-13 June 2014 Ecole Polytech’ Nice (France) 2014