浔江防洪堤对西江中下游洪水的归槽影响

Influence of Xunjiang River Flood Embankment on Flood Retaining to Main Channel in the Middle and Lower Reaches of Xijiang River

基于河道洪水演算原理,建立符合河流水力特性及其变化规律的边滩滞洪水库调节法流量演算模型、校正因数法水位演算模型,利用实测洪水和防洪堤资料进行归槽或还原演算,综合分析防洪堤对洪水归槽的影响。保护区滞洪容积占次洪水总量9.50%的浔江防洪堤对西江中下游洪水过程的归槽影响大于对洪峰的归槽影响,而且洪水类型和干支流组合不同,影响的程度也不相同:对流量过程、洪峰流量影响的最大归槽流量、最大归槽流量比重分别为3 680 m3/s、9.63%,2 700 m3/s、5.90%,对水位过程、洪峰水位影响的最大变幅为0.60、0.22 m。浔江防洪堤造成的洪水归槽并未显著改变西江中下游洪水特性,干支流洪水遭遇、区间降雨和雨洪重叠仍然是形成西江中下游大洪水的主要因素,西江中下游洪涝频繁是气候和流域环境变化综合影响的结果。

Based on river flood calculation principle, the mathematical calculation model of discharge and stage is established based on observed flood and flood embankment data, to analyze synthetically the influence of flood embankment on flood retaining to main channel. The Xunjiang River flood embankment with the largest detention cubage in conservancy area accounting to 9. 50% in the flood volume works on flood process retaining to main channel greater than flood peak in the middle and lower reaches of Xijiang river. Moreover, different types of flood and combination of mainstream and tributaries ha^e different degrees of influence. The biggest discharge and the ratio of discharge retaining to main channel affect discharge process. Peak discharges are 3 680 m3/s, 9. 63%, 2 700 m3/s, 5.90%. The biggest range affecting stage process and flood peak are0. 60 m, 0. 22 m respectively. Flood retaining to main channel does not significantly change flood characteristics. The meeting together of flood in the mainstream and tributaries, interval rainfall and the overlap of rainfall and flood are still the main factors for flood forming in the middle and lower reaches of Xijiang River. The frequent flood in Xijiang River is the result of the synthetic impact of climate and drainage basin environmental change