利用近50 a的实测数据,分析了泾河流域的径流时空变化规律和主要驱动因子。研究表明:年降水量和径流深的空间分布均呈现从南到北的明显减少趋势,并在上游山区出现高值区。流域径流总量自20世纪60年代到21世纪初显著减少,由50.1 mm减到22.3 mm,但各区域的变化很不均匀,其中西部、西南和东南的子流域径流大量减少,可达17.5 mm/10 a;北部和东北则减少不明显,最大减少率仅为1.3 mm/10 a。降水量变化曾是径流减少的重要原因,但20世纪90年代后实施的退耕还林等生态工程在2000年后已经成为引起径流减少的最主要原因。
The spatio-temporal variation of annual runoff in the Jinghe River Basin of Northwest China and its main driving forces were studied based on the meteorological and hydrological data over 50 years in this paper. It showed that the precipitation and runoff presented an obvious decreasing trend from south to north in the Jinghe River Basin, the high value areas of both precipitation and runoff existed in the upstream mountainous parts. While the averaged temperature in the basin increased significantly in last 50 years since the 1960s, the pan evaporation decreased slightly and the precipitation decreased insignificantly, the annual runoff of the whole Jinghe Basin decreased significantly from 50.1 mm in the 1960s to 22.3 mm at the beginning of the 21st century. However, the runoff reduction among subbasins differed significant, which manifested the highest runoff decrease in the west, southwest and southeast parts of Jinghe River Basin, with a reduction rate up to 17.5 mm/10a; while the runoff reduction in the north and northwest parts of Jinghe River Basin presented an unobvious runoff reduction, with a maximum reduction rate of 1.3 mm/10a. The change of annual precipitation is an important cause for the runoff reduction, but the change of soil surface characteristics due to human activities became more profound cause for the runoff reduction since the 1990s, including the increasing terrace field and forest/vegetation coverage resulted from a series of ecological restoration projects, such as grain for green and nature forest protection.
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