中文摘要：

水库汛限水位的动态控制实质上是一种风险调度．在对短期水文预报不确定性分析的基础上，提出了将洪水预报精度等级评定指标转化为入库洪水过程的随机特征值的方法，利用水库调洪演算的随机微分方程，分析了不同预报精度等级和不同预见期条件下水文预报误差的传递与演化过程，并建立了水库汛限水位动态控制的风险率计算模型，以定量评估抬高汛限水位对水库大坝和下游河道防洪安全的影响．算例分析表明，汛限水位的抬高将使水库和下游河道的防洪风险率增大，通过提高预报精度和延长预见期可以降低由汛限水位抬高所增加的风险率．

英文摘要：

The dynamic control of reservoir limited water level during flood seasons is in fact a kind of risk regulation. Based on the analysis of uncertainties of short term hydrologic forecast, it is put forward that the evaluation indices for flood forecast accuracy levels should be transformed into the stochastic values of incident flood hydrograph. The transform and evaluation of errors of hydrologic forecast with different forecast accuracy levels and different expected forecasting periods are analyzed by use of the stochastic differential equations for flood routing of reservoirs. A mathematical model of risk rate for the dynamic control of reservoir limited water level is established so as to quantitatively estimate the impact of the increase of limited water level on the safety of dam and downstream protection area. The results of the adopted examples show that the increase of reservoir limited water level must cause the rising of the flood risk rate of the reservoir and the downstream river. By improving the flood forecasting accuracy and extending the forecasting period, we can lower the risk rising value caused by the increase of the limited water level.