降水与农业种植变化对黄河流域径流影响研究

黄河是我国西北、华北地区重要水源,了解其径流变化特征及成因有着重要意义。论文基于趋势性分析、广义可加模型（GAMLSS）等方法,采用黄河流域近60 a来流量、降水、主要农业种植面积及大型水库资料等数据,通过细化农业小麦生长期与玉米和大豆生长期以及假定不同降水情景,在季节尺度上深入分析了1960—2005年黄河流域气候、农业种植面积等变化对径流的影响。研究结果表明：1）黄河流域5个水文站点小麦生长期与玉米和大豆生长期径流变异点均发生于20世纪80年代中后期和90年代初期,且除花园口站小麦生长期间径流有少部分呈上升趋势外,黄河流域径流整体呈下降趋势,其中,唐乃亥、兰州的小麦生长期、玉米和大豆生长期及龙门、花园口的玉米和大豆生长期趋势均达到了0.05的显著性水平,呈显著下降趋势;2）对比两种降水假设状态,暴雨年的径流始终高于小雨年的径流,因此,降水仍是影响径流的主要因子之一,而农业种植面积变化对径流的影响程度,不仅与降水量的多少有关,还与流量分位数的大小有关,对于唐乃亥站小麦生长期的暴雨年时期,增加农作物种植面积,在低流量分位数时可以增加径流,而在高于0.75分位数时会减小径流,小雨年时期规律相反。该研究结果对变化环境下黄河流域水资源管理与优化配置具有一定理论与现实意义。

Quantification of Fractional Contributions of Seasonal Changes in Climate and Cropland to Streamflow Changes Across the Yellow River Basin

The Yellow River is important water source in Northwest and North China. It is of great significance to understand the characteristics and causes of its streamflow changes. In this paper, impacts of climate changes and human activities such as cropland changes and water reservoirs on streamflow variations at seasonal scale were thoroughly quantified using daily streamflow data, daily precipitation data, cropland data, and information of water reservoirs in the Yellow River Basin. Firstly, multi-year trends of streamflow and change points at seasonal scale during 1960-2005 were evaluated, and then the streamflow changes during the growth period of wheat and growth period of maize and soybean were estimated by Generalized Additive Models for Location, Scale and Shape (GAMLSS) model. Besides, two different precipitation scenarios were proposed to elucidate the impacts of changes in precipitation and cropland at seasonal scale on different streamflow components defined by different percentiles. The results indicated that: 1) The change points of streamflow during the growth period of wheat and growth period of maize and soybean at the five hydrological stations in the Yellow River Basin occurred during the mid- and late-1980s and early 1990s. Except at Huayuankou Station, the streamflow in the Yellow River Basin was generally in decreasing tendency and the decreasing tendency at most hydrological stations was significant at 95% confidence level. 2) Based on two precipitation scenarios set in this study, the streamflow during years with high precipitation was always higher than that during years with low precipitation, implying that precipitation still plays the critical role in streamflow changes. The impacts of cropland changes on streamflow were related with both changes in precipitation and the percentiles of streamflow components. At Tangnaihai Station, the increasing cropland increased the lower quantile of streamflow and decreased the upper quantile of streamflow during the growth period of wheat of high precipitation years while did the opposite during the growth period of wheat of low precipitation years. Results of this study can provide theoretical and practical grounds for water resources management and allocation across the Yellow River Basin.