分水江流域半分布式洪水预报实践

Practice of Semi-distributed Flood Forecasting in Fenshui River Basin

分水江属钱塘江水系,是钱塘江下游左岸最大支流,流域面积3444 km^(2),主流全长164.2 km。洪水预报将分水江流域划分成48个子流域单元,以半分布式新安江模型进行产汇流计算,通过分水江流域拓扑结构以马斯京根模型进行逐级演算,对分水江水库等4座大中型水库及10个重点预报断面进行洪水预报,并通过SCE-UA算法进行参数调优。在分布式洪水预报过程中,通过已率定断面的流域特征值及率定结果,采用多元回归法的参数移植方案,逐级演算后,分水江水库的44场洪水的合格率为100%,模拟误差均在许可误差内,确定性系数均在0.7以上,其中0.9以上19场,洪水预报方案满足乙级精度标准。

Fenshui River belongs to the Qiantang River system,and it is the largest tributary of the left bank of the lower reaches of the Qiantang River.The basin area is 3444 km^(2),and the mainstream length is 164.2 km.The flood forecast divides the Fenshui River Basin into 48 sub-basin units,and calculates the runoff and confluence with the semi-distributed Xin’anjiang model.Through the topological structure of the Fenshui River Basin,the Muskingum model is used to calculate the flood forecast of 4 large and medium-sized reservoirs such as the Fenshuijiang Reservoir and 10 key forecast sections,and the SCE-UA algorithm is used to optimize the parameters.In the process of distributed flood forecasting,the parameter transplantation scheme of multiple regression method is adopted through the basin eigenvalue and calibration results of the calibrated section.After step-by-step calculation,the qualified rate of 44 floods in Fenshuijiang Reservoir is 100%,and the simulation error is within the allowable error.The deterministic coefficient is above 0.7,of which 19 are above 0.9,and the flood forecasting scheme meets the B-level accuracy standard.