防洪堤对洪水的归槽影响研究

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流量和水位演算模型,利用实测洪水和防洪堤资料进行洪水演算,经洪水水文要素变化变化规律及其合理性的综合分析,确定防洪堤对洪水的归槽影响。应用实例的多方案演算成果表明:保护区滞洪容积占次洪水总量最大比重为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、最大归槽流量比重为36 200 m3/s、9.50%,2 600 m3/s、5.78%,对水位过程、洪峰水位影响的最大水位变幅为0.58 m、0.21 m;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;多方案演算成果相互参证,可减少误差、提高成果精度。大江大河洪水频繁并非归槽影响的结果,应结合气候和土地利用及覆被变化对水文循环影响的研究,探索流域变化环境下的洪水形成机理和演变规律。

Studies on the Influence of Prevent-food Dam on Flood Retaining to Main Channel

Based on river flood calculations principle,the mathematical calculations model was established for conforming river hydraulic characteristic and its law of change.The influence of prevent-flood dam on flood retaining to main channel was determinel by synthetically analyzing based on calculation using observed flood and prevent-flood dam data.Multi-schemes figure results in applied examples show that Xunjiang River prevent-flood dam which flood detention volume on the protected areas accounted for 9.50% at largest in the hypo-flood gross affects flood process retaining to main channel bigger than flood peak 's in the middle and lower reach of Xijiang river.Moreover,different types of flood and combination of mainstream and tributaries have different extent of impact: the biggest runoff and the biggest ratio of runoff retain to main channel affecting runoff process and flood peak runoff are 36 200 m3 /s,9.50%,2 600 m3 / s,5.78% and the biggest stage range affecting process and flood peak are 0.58m,0.21m reopectively;Flood retaining to main channel don 't significantly change flood characteristics and flood which are from mainstream and tributaries encountering.Range rainfall and the overlap of rainfall and flood still are the main factors for form flood in the middle and lower reach of Xijiang river.Multi-schemes figure results proof each other,reduce error and improve the accuracy of the results.Rivers flood frequently are not the result of flood retaining to main channel.As a result,the impact of climate,land use and vegetation covering change on the hydrological cycle to explore flood formation mechanism and evolution law under the environment change in river basin should be taken into consideration.