Changes in the sediment load of a river can have important impacts on river channel evolution,nutrient fluxes,aquatic ecology and delta erosion and sedimentation,and the possibility of changes in the sediment load of ...Changes in the sediment load of a river can have important impacts on river channel evolution,nutrient fluxes,aquatic ecology and delta erosion and sedimentation,and the possibility of changes in the sediment load of the Lancang-Mekong River has attracted increasing concern in recent years.Existing studies present conflicting findings regarding the nature and magnitude of recent changes in the sediment load of the Lancang-Meking River and the authors have attempted to assemble the most reliable data on annual sediment loads for the period 1965-2003,to assess recent trends in the sediment load of the river.The changes in annual sediment load at 7 stations on the river are analyzed.Important sediment contributing areas are found in the reaches between Gajiu and Yunjinghong,Chiang Saen and Luang Prabang and downstream of Nong Khai.The sediment load increased at Gajiu,Yunjinghong and Chiang Saen over the period 1985-1992 because of serious soil erosion caused by the expansion of cultivation,the replacement of natural forest by plantations and land disturbance associated with hydropower dam construction.A marked reduction in sediment load occurred at Gajiu after the impoundment of the Manwan Hydropower dam on the Lancang River,but this reduction was not evident downstream at Yunjinghong and the stations further downstream.Significant increases in sediment load appeared at Mukdahan and Khong Chiam.These contrasting patterns of change reflect the influence of sediment contributions from the intervening catchment areas and channel systems as well as storage and remobilization of sediment from the channel system and the impact of hydraulic works such as irrigation systems.The long term mean annual sediment load of the Mekong River at its mouth is estimated to be ca.145×106ta-1,which is lower than previously reported values and it seems likely that this will be reduced in the foreseeable future.展开更多
受气象、自然地理、流域特性等因素的影响,径流水电出力为矩不确定的随机变量。故采用矩不确定分布式鲁棒优化方法(Distributional Robust Optimization Under Moment Uncertainty,DRO-MU)解决含径流式水电的系统安全经济调度问题。以...受气象、自然地理、流域特性等因素的影响,径流水电出力为矩不确定的随机变量。故采用矩不确定分布式鲁棒优化方法(Distributional Robust Optimization Under Moment Uncertainty,DRO-MU)解决含径流式水电的系统安全经济调度问题。以不确定集合刻画径流水电出力期望和协方差的不确定性,并对含水电出力的不等式约束进行处理,将其转化为具有数学凸性的条件期望约束;采用拉格朗日对偶原理将模型转换为确定性的半定规划模型。仿真结果表明,该方法随着不确定集范围或置信水平的增大,系统总成本增加;与矩确定的CVaR方法相比,所得系统总成本稍高,但安全性更高。该方法是采用鲁棒思想利用分布参数的随机规划方法,可有效处理带有矩不确定随机变量的电力优化调度问题,对其他随机变量分布未知的问题同样适用。展开更多
Hydrological data on the Upper Qingjiang River from 1960 to 2012 document trends of runoff caused by hydropower engineering projects and long-term changes in rainfall. Annual runoff correlates strongly with annual pre...Hydrological data on the Upper Qingjiang River from 1960 to 2012 document trends of runoff caused by hydropower engineering projects and long-term changes in rainfall. Annual runoff correlates strongly with annual precipitation, but is significantly reduced after reservoir construction compared to earlier values. Comparisons of intense, pre- and post-construction rainfall events suggest that the Chebahe and Dalongtan reservoir projects respectively clips the magnitude of the flood peaks and delays runoff delivery.展开更多
Hydrological models within inflow forecasting systems for high-alpine hydropower reservoirs can provide valuable information as part of a decision support system for the improvement of hydropower production or flood r...Hydrological models within inflow forecasting systems for high-alpine hydropower reservoirs can provide valuable information as part of a decision support system for the improvement of hydropower production or flood retention. The information, especially concerning runoff, is however rarely available for the calibration of the hydrological models used. Therefore, a method is presented to derive local runoff from secondary information for the calibration of the model parameters of the rainfallrunoff model COSERO. Changes in water levels in reservoirs, reservoir outflows, discharge measurements at water intakes and in transport lines are thereby used to derive the local, "natural" flow for a given sub-catchment. The proposed method is applied within a research study for the ?BB Infrastructure Railsystem division in the Stubache catchment in the central Austrian Alps. Here, the ?BB operates the hydropower scheme "Kraftwerksgruppe Stubachtal", which consists of 7 reservoirs and 4 hydropower stations. The hydrological model has been set up considering this human influences and the high natural heterogeneity in topography and land cover, including glaciers. Overall, the hydrological model performs mostly well for the catchment with highest NSE values of 0.78 for the calibration and0.79 for the validation period, also considering the use of homogeneous parameter fields and the uncertainty of the derived local discharge values. The derived runoff data proved to be useful information for the model calibration. Further analysis, examining the water balance and its components as well as snow cover, showed satisfactory simulation results. In conclusion, a unique runoff dataset for a small scale high-alpine catchment has been created to establish a hydrological flow prediction model which in a further step can be used for improved and sustainable hydropower management.展开更多
为了在量化入库径流预报误差的条件下有效提高调度方案制作的精度,基于高斯混合模型(GMM)良好的自适应性,能更准确地描述单一预见期径流预报误差分布的特点,以及高维meta-student t Copula函数具有将多个类型边缘分布有机耦合的优势,建...为了在量化入库径流预报误差的条件下有效提高调度方案制作的精度,基于高斯混合模型(GMM)良好的自适应性,能更准确地描述单一预见期径流预报误差分布的特点,以及高维meta-student t Copula函数具有将多个类型边缘分布有机耦合的优势,建立了多个预见期入库径流预报误差的GMM-Copula随机模型。以雅砻江流域锦屏一级水电站水库为例,对预见期分别为6 h、12 h、18 h、24 h的入库径流预报误差进行了分析与随机模拟。结果表明,随着预见期的增加,模拟误差与实际误差的主要统计特征值相差不大,满足预设精度要求,且变化规律一致,验证了模型的可行性与有效性,为水库调度方案的编制与实施提供了参考依据。展开更多
基金supported by the China Institute of Water Resources and Hydropower Research (Grant No. Shaji-1230)the 12th Five-Year National Science and Technology Support Program of China (Grant No.2012BAB02B01)the University of Exeter and the University of New Brunswick (Canada Research Chairs Program)
文摘Changes in the sediment load of a river can have important impacts on river channel evolution,nutrient fluxes,aquatic ecology and delta erosion and sedimentation,and the possibility of changes in the sediment load of the Lancang-Mekong River has attracted increasing concern in recent years.Existing studies present conflicting findings regarding the nature and magnitude of recent changes in the sediment load of the Lancang-Meking River and the authors have attempted to assemble the most reliable data on annual sediment loads for the period 1965-2003,to assess recent trends in the sediment load of the river.The changes in annual sediment load at 7 stations on the river are analyzed.Important sediment contributing areas are found in the reaches between Gajiu and Yunjinghong,Chiang Saen and Luang Prabang and downstream of Nong Khai.The sediment load increased at Gajiu,Yunjinghong and Chiang Saen over the period 1985-1992 because of serious soil erosion caused by the expansion of cultivation,the replacement of natural forest by plantations and land disturbance associated with hydropower dam construction.A marked reduction in sediment load occurred at Gajiu after the impoundment of the Manwan Hydropower dam on the Lancang River,but this reduction was not evident downstream at Yunjinghong and the stations further downstream.Significant increases in sediment load appeared at Mukdahan and Khong Chiam.These contrasting patterns of change reflect the influence of sediment contributions from the intervening catchment areas and channel systems as well as storage and remobilization of sediment from the channel system and the impact of hydraulic works such as irrigation systems.The long term mean annual sediment load of the Mekong River at its mouth is estimated to be ca.145×106ta-1,which is lower than previously reported values and it seems likely that this will be reduced in the foreseeable future.
文摘受气象、自然地理、流域特性等因素的影响,径流水电出力为矩不确定的随机变量。故采用矩不确定分布式鲁棒优化方法(Distributional Robust Optimization Under Moment Uncertainty,DRO-MU)解决含径流式水电的系统安全经济调度问题。以不确定集合刻画径流水电出力期望和协方差的不确定性,并对含水电出力的不等式约束进行处理,将其转化为具有数学凸性的条件期望约束;采用拉格朗日对偶原理将模型转换为确定性的半定规划模型。仿真结果表明,该方法随着不确定集范围或置信水平的增大,系统总成本增加;与矩确定的CVaR方法相比,所得系统总成本稍高,但安全性更高。该方法是采用鲁棒思想利用分布参数的随机规划方法,可有效处理带有矩不确定随机变量的电力优化调度问题,对其他随机变量分布未知的问题同样适用。
基金supported by the National Natural Science Foundation of China (No. 31460132)the Scientific Research Project of Hubei Provincial Department of Education (No. Q20122901)
文摘Hydrological data on the Upper Qingjiang River from 1960 to 2012 document trends of runoff caused by hydropower engineering projects and long-term changes in rainfall. Annual runoff correlates strongly with annual precipitation, but is significantly reduced after reservoir construction compared to earlier values. Comparisons of intense, pre- and post-construction rainfall events suggest that the Chebahe and Dalongtan reservoir projects respectively clips the magnitude of the flood peaks and delays runoff delivery.
基金This study was funded by the OBB Infrastructure.
文摘Hydrological models within inflow forecasting systems for high-alpine hydropower reservoirs can provide valuable information as part of a decision support system for the improvement of hydropower production or flood retention. The information, especially concerning runoff, is however rarely available for the calibration of the hydrological models used. Therefore, a method is presented to derive local runoff from secondary information for the calibration of the model parameters of the rainfallrunoff model COSERO. Changes in water levels in reservoirs, reservoir outflows, discharge measurements at water intakes and in transport lines are thereby used to derive the local, "natural" flow for a given sub-catchment. The proposed method is applied within a research study for the ?BB Infrastructure Railsystem division in the Stubache catchment in the central Austrian Alps. Here, the ?BB operates the hydropower scheme "Kraftwerksgruppe Stubachtal", which consists of 7 reservoirs and 4 hydropower stations. The hydrological model has been set up considering this human influences and the high natural heterogeneity in topography and land cover, including glaciers. Overall, the hydrological model performs mostly well for the catchment with highest NSE values of 0.78 for the calibration and0.79 for the validation period, also considering the use of homogeneous parameter fields and the uncertainty of the derived local discharge values. The derived runoff data proved to be useful information for the model calibration. Further analysis, examining the water balance and its components as well as snow cover, showed satisfactory simulation results. In conclusion, a unique runoff dataset for a small scale high-alpine catchment has been created to establish a hydrological flow prediction model which in a further step can be used for improved and sustainable hydropower management.
