北方干旱化和土地利用变化对泾河流域径流的影响

Studies on the Effects of Climatic Warming-drying Trend and Land Use Change on the Runoff in the Jinghe River Basin

论文以在黄土高原上发育，流经中国北方干旱、半干旱地区的黄河二级支流——泾河为研究对象，基于20世纪八九十年代的土地利用影像资料，以及泾河流域1970～2002年的气候、水文资料，采用美国农业部开发的分布式流域水文模型SWAT，分析了20世纪80～90年代泾河流域的降雨量和径流量的变化。从80到90年代，流域年降雨量呈逐年递减趋势，80年代多年平均月降雨量明显大于90年代多年平均月降雨量，尤其在7～9月，平均降雨量明显减少。受气候干旱化和土地利用／覆被变化的共同作用，80～90年代，流域多年平均年径流减少了8．92m^3s^-1。为了区分气候变化和土地利用变化对流域径流的影响，采取分别固定气候因子与土地利用／覆被变化因子的方法，将模拟情景输入模型，定量区分气候和土地利用／覆被变化对流域径流的影响方式和程度。结果表明，气候干旱化趋势使流域多年平均年径流减少28．08m^3s^-1，为气候、土地利用／覆被变化共同影响径流变化量的314．80％；土地利用／覆被变化使流域多年平均年径流增加26．57m^3s^-1，为气候、土地利用／覆被变化共同影响径流变化量的297．87％．

Based on the analysis of nearly thirty years meteorological and hydrological data （ 1970 -2002） and remote sensing data of the 1980s and the 1990s, SWAT model （ Soil and Water Assessment Tool） developed by USDA Agricultural Research Service （ARS） was adopted to study the change of the eco-hydrological characteristics in the Jinghe River Basin under the conditions of climatic warming - drying trend and aggravated human activities. After model validation and field verification, our results showed that the model SWAT could precisely predict the ecohydrological processes in the Jinghe River Basin. Results showed that from the 1980s to the 1990s the mean annual precipitation decreased, especially in July, August and September. Affected by climate warming - drying trend and land-use change, the mean annual runoff reduced 8.92 m^3s^-1. By respectively fixing the climatic factors and the land-use factors in the Jinghe River Basin, and putting the simulated scenarios into the SWAT model, the effects of climate change and land- use change on the mean annual runoff in the Jinghe River Basin were obtained. From the 1980s to the 1990s, the climatic warming-drying alone could reduce the mean annual runoff by 28.08 m^3s^-1, which is about 314.80% of the actual runoff reduction. Meanwhile, the land-use change alone could increase the mean annual runoff by 26.57m^3s^-1, which is about 297.87 % of the actual runoff change from the 1980s to the 1990s. Both the climate and land use changes significantly affect the runoff in the Jinghe River Basin.