降水和土地利用变化对罗玉沟流域水沙关系的影响

为探讨降水和土地利用变化对流域水沙关系的影响,以黄土高原丘陵沟壑区罗玉沟流域为研究区域,利用流域25年(1986—2010年)的年降水量、年径流量和年输沙量以及土地利用变化资料,分析罗玉沟流域水沙演变规律和水沙关系变化。结果表明:在1986—2010年罗玉沟流域年降水量和汛期降水量基本保持平稳,无明显的增减趋势,而流域年径流量和年输沙量整体呈波动递减的变化趋势,降水与径流相关分析得出,汛期产流产沙对流域年径流量和年输沙量影响最显著。对不同时期流域水沙变化分析,土地利用方式改变,主要是梯田、林草等水土保持措施,对于流域减水减沙作用有限,梯田和林草面积的增加并未明显改变流域水沙关系,淤地坝等工程措施对黄土高原丘陵沟壑区流域减水减沙具有重要作用。研究结果可为黄土丘陵沟壑区水土流失治理及水土保持措施布设提供理论依据。

Impacts of Precipitation and Land Use Change on Runoff and Sediment in Luoyugou Watershed

The objective of this study was to understand the influence of precipitation and land use change on water and sediment yield in Luoyugou watershed in the loess hilly gully region, which based on the annual precipitation data, runoff and sediment yield data and land use change data collected from 1986 to 2010. The results indicated that during 1986 to 2010, the annual precipitation and precipitation of flood season were basically stable, and there was no obvious increase or decrease trend, while the annual runoff and annual sediment discharge in Luoyugou watershed were fluctuating and decreasing during this period. The precipitation and runoff correlation analysis showed that the runoff and sediment yield in the flood season had the greatest significant influence on the annual runoff and annual sediment discharge in the watershed. Through analyzing the change of water and sediment in different periods, we found that the change of land use mode, mainly the change of soil and water conservation measures such as terraced fields and forest grass, had limited effect on water reduction and sediment reduction in the watershed. The increase in the area of terraced fields and forest grass did not significantly change the relationship of water and sediment in the watershed, and the engineering measures such as silt dams played important role in reducing the water and sediment in the hilly and gully region of the Loess Plateau. The results could provide some theoretical basis for soil erosion management and dispose of soil and water conservation measures in loess hilly and gully region.