干旱对南水北调中线工程水源区降水-径流关系的影响机理

The central route of South to North Water Diversion Project (SNWDP) is one of important water diversion projects in China’s water resources planning, aiming to alleviate the water resources shortage in the North China Plain. Under the impacts of global change, the increasing drought results in the change in rainfall-runoff relationship in the water source catchment of SNWDP, which brings a new challenge for reasonable runoff prediction. Therefore, investigating the influence mechanism of drought on the rainfall-runoff relationship is crucial to understand the reasons of runoff change and provide an accurate runoff prediction. To achieve this objective, first we will analyze the spatial and temporal changes of hydrometeorological characteristics and identify the drought. Secondly, we will analyze the drought’s "cumulative effect" and "continuing effect" on rainfall-runoff relationship by field experiments and hydrological statistics. Then a distributed hydrological model considering the drought impact on rainfall-runoff relationship will be developed to evaluate quantitatively the influence of change in rainfall-runoff relationship caused by drought on runoff prediction in the water source catchment of the central route of SNWDP. The results could be helpful to evaluate the drought influence on water resources, and also provide reference for drawing up the adaptive strategies of water diversion for the central route SNWDP under global change.

南水北调中线工程作为我国“四横三纵”水资源调配格局的重要“一纵”，是缓解华北地区水资源短缺的大型跨流域调水工程。在全球变化影响下，频繁发生的干旱事件引起中线工程水源区降水-径流关系发生了显著变化。降水-径流关系的变化对水源区入库径流的准确预测带来挑战。揭示干旱对降水-径流关系的影响机理是认识水源区水循环演变规律和预测水源区径流的前提。本项目在水源区水文气象要素变化特征分析和干旱过程识别的基础上，基于野外实验和水文分析揭示干旱对水源区降水-径流关系影响的“累积”和“滞后”效应，构建能反映干旱对降水-径流关系影响的流域分布式水文模型，模拟水源区“降水-蒸散发-土壤水-径流”动态转化过程，定量评估干旱引起的降水-径流关系变化对丹江口水库入库径流预测的影响。研究成果对评估干旱对流域水文水资源的影响具有科学意义，并可为全球变化影响下中线调水适应性对策的制定提供参考。

南水北调中线工程是缓解我国华北地区水资源短缺的大型跨流域调水工程。近年来，工程水源区来水量显著下降，干旱被认为是导致工程水源区径流下降的重要原因之一。干旱对降水-径流过程的影响机理非常复杂，揭示干旱对降水-径流关系的影响机理是认识水源区水循环演变规律和合理预测径流的前提。本项目基于野外实验、水文统计以及分布式水文模型，1）分析了研究区干旱的时空演变格局，发现研究区干旱频率在过去50多年间呈增加趋势；2）揭示了干旱对降水-径流关系影响的“累积”和“滞后”效应，结果发现，干旱年径流系数要小于非干旱年份，且减少是程度与干旱的强度呈正相关，且严重干旱对径流系数的影响常常会持续到下一年；3）开展了野外人工降雨产流实验，构建了考虑植被变化影响的分布式水文模型，模型显著提高了植被显著变化时期的水文模拟效果；4）比较了四种水文模型目标函数在干旱年份径流预测的适用性；5）发展了兼顾径流和水储量综合模拟效果的模型调参方案，6）模拟了全国尺度1982-2014年的蒸散发和径流变化。发表论文8篇，其中包括SCI论文7篇。