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    黄土丘陵第Ⅲ副区典型流域水沙演变过程及其驱动因素分析

    Runoff-sediment relationship and driving force of typical watershed in the third sub-region of hilly loess area, northwestern China

    • 摘要: 流域水沙演变过程是构建区域水土流失模型及评价水土保持措施效益的基础。为探讨气候与下垫面变化对流域水沙变化的影响,以黄土丘陵沟壑区第Ⅲ副区罗玉沟流域为例,采用水文要素累积距平、Mann-Kendall趋势性检验和双累积曲线等方法,分析了1986—2010年间流域水沙关系演变过程及驱动因素,并定量分析了驱动因素的影响。结果表明:1)流域径流量在1993年发生突变,其中1994—2010年(后期)较1986—1993年(前期)不同降水水平年的径流量和输沙量减少率大多超过50%;2)土地利用结构优化可改变流域水沙过程和水沙量,而沟道淤地坝工程的运行改变了水沙搭配关系,使流域单位径流输沙量显著降低;3)降水和土地利用变化对流域径流减少贡献率分别为18.48%和81.52%;降水和土地利用变化对泥沙减少贡献率则分别为27.15%和72.85%。

       

      Abstract: Research on the relationship between runoff and sediment in the watershed is the foundation of constructing the models of regional water loss and soil erosion and evaluating the benefit of soil and water conservation measures. To investigate the effect of climate and land use change on runoff-sediment relationship, we selected Luoyugou Watershed, a typical small watershed in the hilly loess region, northwestern China, as study object. Hydrological element cumulative anomaly, Mann-Kendall trend test, double mass curve and other methods were applied to analyze the evolution process of the relationship between runoff and sediment and its driving forces in the period of 1986—2010 as well as the quantitative effects of driving factors. The results were as follows: 1) An abrupt change of runoff in the watershed happened in 1993, and runoff and sediment yield during the period of 1994—2010 was reduced by more than 50% compared with that during the period of 1986—1993 under different rainfall conditions. 2) Optimization on land use structures would positively influence the hydrological process and sediment yield. Those warping dams are helpful to reduce significantly the sediment yield in a given unit of runoff through altering the relationship between runoff and sediment. 3) Precipitation and the change of landuse caused by human activities contributed to reductions in runoff by 18.48% and 81.52%, and in sediment yield by 27.15% and 72.85%, respectively.

       

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