延河流域主要水文要素时变过程分析

Temporal Change Analysis of Hydrological Factors in the Yanhe River Basin

对延河流域降水、径流和泥沙等水文要素从20世纪中叶到21世纪初的年内分配及年际变化进行了时变过程分析。以探求区域植被重建对流域水文过程的影响情况。结果表明,三个水文基本要素都有不同程度的年内分布趋于均匀和年际变化趋缓的趋势。20世纪70—90年代比60年代流域平均面雨量分别减少了10.5%,11.7%和14.0%,年径流量分别减少了19.0%,12.9%和22.6%,年输沙量分别减少了21.1%,46.2%和41.7%。

The main hydrology factors in one river includes precipitation, runoff and sediment discharge. These three hydrology factors are impacted largely by regional land use/ land cover change. The Yanhe River Basin with the area of 7 725 km^2 and in middle of the Loess Plateau, is one of the hot-spots for regional afforestation and soil & water conservation in China. So studying on the temporal change of the main hydrology factors in the Yanhe River Basin is very essential for providing the basic information and supporting the decision of local government. We collected the precipitation data and worked out the regional tendency from the 6 wide-spreaded rain gauge stations from the middle of 20^(th) century to 21^(st) century. We also got the runoff and sedimentation discharge data from 2 hydrology stations in the same period. It's founded: (1) The monthly distribution of each of those three main hydrology factors tended to be uniform, and the annual change was prone to be tempered. (2) Compared to the average in 1960s, the annual precipitation in the 1970s, 1980s and 1990s in the basin, has respectively reduced by 10.5%, 11.7% and 14.0%. (3) The annual water yield in the basin has separately reduced by sediment discharge, reduced by 14.1%, 13.1% and 21.4%. (4) The annual sediment discharge reduced by 21.1%, 46.2% and (41.7%.)