基于机理模型的兰江洪水复盘分析

Lanjiang River flood re-simulation based on the mechanism model

为提高洪水预报水位精度,结合水文和水动力模型,对钱塘江2022年“6·21”洪水计算过程进行复盘,分析洪水成因。收集降雨量、水位、流量等水文监测数据及水利工程调度信息,建立兰江流域半分布式水文和分段水动力模型,完成模型率定和验证。基于模型分析洪水成因,分析降雨时空变化、梯级水利枢纽调度、区间水库拦蓄对洪水过程的影响。结果表明:洪水主要由自北向南移动的强降雨形成,在水利枢纽调度影响下,洪水水位过程线由尖瘦型演变为头肩型,其中干流水利枢纽调度影响低水水位上涨和消落,上游水库调蓄可有效削减洪峰并推后峰现时间。通过洪水成因分析,在机理模型中加入水利工程调度影响,计算的洪水水位过程与实际更加吻合。

In order to improve the accuracy of flood level forecast,the calculation process of the "June 21st" flood of Qiantang River in 2022 is reviewed based on hydrological and hydrodynamic models,and the causes of flood are analyzed.Hydrological observation data is collected including rainfall,water level,discharge and scheduling information of water conservancy projects.The semi-distributed hydrological and segmented hydrodynamic model of the Lanjiang River basin is schematized,and the model calibration and verification are completed.Based on the model,the analysis is carried out,including flood causes,the effects of temporal and spatial changes of rainfall,and the operation of cascading water projects and reservoir storage on flood process.The results show that the flood is mainly caused by heavy rainfall moving from north to south,and flood processes change from sharp-thin type to headshoulder type due to the operation of water conservancy projects.The dispatching of projects in main stream can affect the rise and fall of the low water level,and the regulation and storage of upstream reservoirs can effectively reduce the high-water level peak and postpone the peak time.The processes of calculating flood level turn out to be more consistent with the observed water level,when the influence of water conservancy engineering scheduling has been applied into the mechanism model by analyzing the causes of floods.