三峡库区张家冲小流域降雨-径流模拟

以三峡库区的张家冲小流域为例,对降雨—径流过程进行模拟,以期为库区小流域水土流失和非点源污染过程研究提供借鉴,并为控制三峡库区的水土流失和非点源污染,保障库区的水资源安全,缓解日趋严重的环境压力提供科学支撑。首先以研究区的水文、气温观测资料以及数字高程模型为基础,利用半分布式水文模型TOPMODEL模型对日径流进行模拟,选用Nash—Sutcliffe效率系数、均方根误差RMSE以及相关系数r作为目标函数。模拟结果表明,研究区径流的模拟值与实测值变化趋势较为一致;丰水期的模拟精度和拟合效果都优于枯水期,且差异较大;依据《水文情报预报规范》SL250—2000,确定该区丰水期的模拟精度为丙级,枯水期在丙级以下。研究发现,TOPMODEL比较适用研究区丰水期的日径流模拟,不适用于枯水期的日径流模拟。

Rainfall-Runoff Simulation for Zhangjiachong Small Watershed in the Three Gorges Reservoir

By taking the Zhangjiachong small watershed in the Three Gorges Reservoir for an example,rainfall—runoff process simulation is conducted to provide references to the researches on soil and water loss and non-point source pollution process and scientific supports to control soil and water loss and non-point source pollution,to ensure water security,and to alleviate the growing pressures on ecological environment.Based on the observed data of hydrology and temperature and digital elevation model,TOPMODEL,a half-distributed hydrological model,is used to simulate daily runoff in the study area.Nash—Sutcliffe coefficient,Root Mean Squared Error(RMSE) and correlation coefficient are taken as objective functions.Simulation results show that the measured values of runoff dynamics are roughly consistent with the simulated values.Simulation accuracy and fitting efficiency in wet season are better than those in dry season and they vary greatly.According to the "hydrological forecasting standards" SL250—2000,runoff simulation accuracy grade is in C class in wet season and below C class in dry season.TOPMODEL is appropriate for the daily runoff simulation in wet season,but not appropriate in dry season.