基于WEP-L模型的寒区流域径流演变模拟及归因分析

寒区在我国分布广泛，且多为我国主要江河的源头区，其水循环演变会对地区乃至全国的水资源情势产生重要影响。针对寒区冻土作用下特殊的水文特性，研究选择松花江、黄河、黑河、长江、雅鲁藏布江流域内5个典型寒区流域，采用改进的WEP-L模型模拟分析了寒区径流在1960—2010年的时空变化规律。同时，基于水文模拟法，设计不同气候变化与土地利用情景对各寒区流域径流变化进行了归因分析。研究表明：WEP-L针对不同的寒区流域逐月径流过程，取得了较好的模拟效果，NSE（纳什效率系数）基本在0.7以上，相对误差控制在±15%内。5个流域的径流量变化趋势表现为弱显著性，但是黄河流域（唐乃亥以上）和黑河流域（莺落峡以上）的基流指数显著增加，说明这两个流域的河川基流占比不断增加，主要原因可能在于冰川融雪的增加。除了松花江流域（阿彦浅以上）外的四个寒区流域的气候变化对径流的影响较高，贡献率达到78%以上，是径流演变的主导作用。研究结果有助于增强对寒区水循环和水资源演变的认识，为应对未来变化环境下寒区水问题提供参考。

Runoff evolution simulation and attribution analysis in cold region basin based on WEP-L model

Cold regions are widely distributed in China， most of which are the headwaters of major rivers of China. Their runoff evolution will have an important impact on the regional even the whole country water resources. Aiming at the special hydrological characteristics under the action of frozen soil in cold region， five representative watersheds in cold regions including in Songhua River， Yellow River， Heihe River， Yangtze River and Yarlung Zangbo River basins are selected. The improved WEP-L model is used to simulate and analyze the temporal and spatial variation of runoff in cold region from 1960 to 2010. Meanwhile， based on the hydrological simulation method， different climate change and land use scenarios are designed to analyze the attribution of runoff changes in cold regions. The results show that： （1） The improved WEP-L has a good fit for runoff in different cold regions. The Nash efficiency coefficient is above 0.72， and the absolute relative error is within ±11%. （2） The trend of runoff change in five typical basins is not significant， but the base flow index of Tangnaihai and Yingluoxia increased significantly， and passed the 0.01 significance test， indicating that the proportion of basal flow in these two basins is increasing. （3） In addition to the A’yanqian and A’nen watershed of the climate change in the four cold basins has a greater impact on runoff， more than 78%， which is the dominant role in runoff evolution. Relevant studies can provide reference for the study of water cycle and water resources evolution in cold regions.