局地暴雨对南水北调中线水位流量的影响

为准确分析短历时强暴雨对渠道水位流量的影响,以南水北调中线北拒马河节制闸区域为例,建立考虑降雨过程的一维非恒定流仿真模型,设定不同的雨区覆盖范围,模拟了降雨频率P=1%、降雨历时120min典型设计暴雨下渠道的响应过程。仿真表明,暴雨使雨区上游流量减小,距离雨区越近,减幅越大;使雨区内渠道的流量增大,且距离雨区中心越近,增幅越大。暴雨过程中,无论雨区范围大小,最大水位升幅均出现在北拒马河节制闸闸前,幅度与暴雨强度相关,降雨频率P=1%、降雨历时120min暴雨条件下为0.09m。暴雨结束后,随雨区覆盖范围的差异,北拒马河节制闸的闸前水位分别呈现下降、不变或上升趋势。当雨区范围达76km时,水位开始上升;当雨区范围达180km时,水位历时48h升至预警水位。

Influence of Rainstorm on Water Level and Flow of the Middle Route of South-to-North Water Diversion Project

To study the influence of regional torrential rainstorm on water level and flow of the canal, 1-D unsteady flow model considering rainstorm inflow was developed for the middle route of South-to-North Water Diversion Project. A 120 min design rainstorm with the return period of 100-year near Beijuma regulating sluice region was proposed. Test cases with variant covering areas were generated to examine the influence of the rainstorm. Simulation results show that the check gate flow upstream of the rainstorm area decreased extensively. The one closest to the upstream side of the rainstorm area reduced mostly. All check gate flows within the rainstorm area rise. The one closest to the central of the rainstorm area increased mostly. The maximal water level rise located at the upstream side of the Beijuma regulating sluice. The growth was determined by the intensity of rainstorm. The value was 0.09 m for a 120 min storm with a 100-year return period. The maximal water level increase after the rainstorm was determined by the rainstorm coverage area. When the coverage was 76 km, water level began to rise. When the coverage reached 180 km, water level rose to the warning level after duration 48 hours.