雨-雪-冰不同产流下河川基流过程模拟方法研究

The alpine mountain areas are the origins of runoff. Runoff in most of the rivers in the mountain areas, is mainly from melt-waters of snowpacks and glaciers, and/ or from rainfall in alpine mountain areas. Base flow is the main component of runoff, particularly during low flow periods, no matter what types of runoff generation. To carry out the simulation of base flow process for different runoff generation from rainfall, snow and/or glacier, has a significant meaning for the basin water resources management and the river health maintenance. However, reliable separation of base flow under different hydrological conditions is the key problem. The nonlinear aquifer storage-discharge approach will be used in the study, which has a physical meaning with only two parameters and is easy to parameterize. The parameters in the exponential function that describes the aquifer storage-discharge relationship could be optimized independent of the SWAT model by using observed streamflow data during recession periods. The functions of base flow calculation will be constructed based on the aquifer storage-discharge relationship and the methods of base flow simulation in the distributed hydrological model under different hydrological conditions will be developed. Moreover, the equations of the digital filter used for base flow separation applicable for the basins dominated by snowmelt and glacier melt will be developed, which is based in signal analysis and processing for rainfall-dominated basins. By collecting the data, the improved model will be established for the typical catchments in the Manas River Basin (dominated by snow/ glacier melt) in the arid-cold mountain areas, Shaying River Basin (dominated by rainfall) in the semi humid-humid areas, and will be calibrated, validated and assessed. Based on the simulation by the improved model, the spatial and temporal variations in base flow will be analyzed, the mechanism will be discussed, the contribution of base flow to runoff will be quantified, and the similarities and differences of the base flow characteristics between the arid-cold mountain areas and semi humid-humid areas will be revealed.

山区水资源主要来自降雨、积雪、冰川融水产生的径流。无论以何种产流为主的流域，基流都是其河川径流的重要组成部分，是枯水季节径流的主要来源。开展雨-雪-冰不同产流下河川基流过程模拟研究对流域水资源管理和河流健康维护具有重要意义。不同产流下可靠的基流分割是面临的关键问题。本项研究创新地引入具有物理意义、含有较少参数、参数化简便的非线性库理论，构建基流过程模拟方程，发展不同产流下分布式水文模型中河川基流过程模拟方法；将源于降雨径流流域的数字滤波法，拓展到雪-冰产流流域，建立适用于雪-冰产流流域的数字滤波基流分割方程；利用改进的模型，在干旱-高寒山区以雪冰产流为主的玛纳斯河流域和半湿润-湿润区以降雨产流为主的沙颍河流域，检验和完善理论研究成果，研究雨-雪-冰不同产流下河川基流过程的季节、年际变化特征及控制机理，量化地下水对河川径流的贡献，揭示干旱-高寒山区和半湿润-湿润区河川基流过程特征的异同。

基流是河川径流的重要组成部分，是枯水季节径流的主要来源，由于基流难以直接观测，主要通过不同的基流分割方法由径流数据得到，可靠的基流分割对于基流研究尤为关键。本项研究探讨雨-雪-冰不同产流下基流退水过程曲线，发展不同产流下分布式水文模型中河川基流过程模拟方法；将源于降雨径流流域的数字滤波法，拓展到雪-冰产流流域；利用改进的模型，在干旱-高寒山区以雪冰产流为主的玛纳斯河流域和半湿润-湿润区以降雨产流为主的沙颍河流域进行应用，解析雨-雪-冰不同产流下河川基流过程的季节、年际变化特征。主要取得了以下结论：.（1）阐述了不同产流流域基流退水曲线本质。在前期对西北干旱区雪冰流域地下水出流分析的基础上，采用线性关系和非线性关系对沙颍河流域（降雨产流为主）的地下水退水曲线进行拟合对比，非线性模拟值与观测值的判定系数达到0.91，而线性模拟值与观测值的判定系数为0.76，非线性模拟效果比线性拟合效果好。.（2）改进了雨-雪-冰不同产流下SWAT模型基流算法。为进一步验证“非线性单库”在降雨-径流型流域的适用性，以降雨产流为主的沙颍河流域为研究区，引入具有物理意义、含有较少参数、参数化简便的非线性库理论，构建基流过程模拟方程，发展适用于雨-雪-冰不同产流下SWAT模型基流模拟方法。.（3）修正了数字滤波法在雪冰流域的适用性。数字滤波得到的基流量在雪冰流域偏大，特别是在汛期，可能是因为冰川融水相对稳定，在基流分割时，将冰川融水作为了基流量。将冰川融水量引入到数字滤波法中，提高了数字滤波法在雪冰流域基流分割的适用性。.（4）揭示了不同产流流域的基流过程特征。玛纳斯河流域地表径流、壤中流和基流分别占31.5%、22%和46.5%，基流量大于表面径流量；沙颍河流域其比例分别为55.5%、25.4%和19.1%，以表面径流为主。玛纳斯河基流不均匀系数为0.84，集中度为0.46；沙颍河基流年内不均匀系数仅为为0.37，集中度为0.25。冬季径流均主要由基流补给。.