西江归槽洪水研究展望

西江流域由于大量兴建堤防工程导致洪水归槽,改变了原天然河道的洪水槽蓄关系,使得用于防洪规划和洪水灾害风险评估的洪水序列失去了一致性。目前洪水归槽问题研究主要集中在出槽洪水的归槽还原计算方面,对于干支流洪水与区间洪水的遭遇考虑不足,对洪水发生变异的成因及非一致性洪水的频率计算方法也缺乏系统性的研究。建议采用水文变异诊断系统对西江流域的水文要素进行变异分析,以识别其时空变异规律;研制西江中下游干支流洪水及区间暴雨洪水的多输入单输出概念性水文模型,以模拟其洪水形成过程;提出基于MISOCHM模型的非一致性洪水频率计算方法、基于HHT变换的非一致性洪水频率计算方法,以推求变化环境下河道断面的洪水频率分布,并结合西江流域防洪规划评价西江堤防现状和未来的防洪能力。其研究成果不仅对变化环境下的水循环和水安全研究具有重要的理论意义,而且对于流域防洪规划和洪水灾害风险评估具有重要的实际应用价值。

Future Research Prospects on Flood Returning to Main Channel of Xijiang River

The projects of constructing embankment massively on Xijiang River Basin not only lead to flood returning to main channel,but also change the flood channel storage relationship of the original natural river,making that the flood sequences which are used for flood control planning and the risk assessment of flood disaster have lost their consistency.At present,the research of flood retaining to main channel is concentrated on the computation aspect of the flood＇s return to channel and modification to original state after the flood overflowing the channel,and lacks sufficient consideration of the encounter experience of main and branch flood and the interval flood,and also lacks systematic research of the causes of flood variation and frequency analysis method of inconsistency flood.This article suggested that use the hydrologic variation diagnosis system to carry on variation analysis towards hydrologic features in Xijiang River Basin,and then distinguish its space and time variation rule;Develop conceptive hydrological model of multi-input and single-output（MISOCHM） on the main and branch flood and the interval rainstorm and flood of middle and lower reaches of Xijiang River to simulate its flood forming process;Propose two frequency analysis method of inconsistency flood that one is based on MISOCHM model and another is based on Hilbert-Huang transformation to inquire into the flood frequency distribution of the river cross section under change environment and to appraise the Xijiang River embankment present situation and future flood prevention ability combined the flood prevention plan of Xijiang River Basin.The study results not only has important theoretical significance to water cycle and water environment security research under change environment,but also has important practical applications for river basin flood control planning and flood risk assessment.