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流域水沙关系对降水量变化和水土保持的响应可为水土保持效益评价提供科学依据。根据黄土丘陵沟壑区第三副区典型小流域桥子东沟和桥子西沟1987—2010年的水文泥沙数据,用Mann-Kendall法检验流域年降水量和水沙变化趋势,采用双累积曲线法分析径流量和输沙量之间的关系,探讨降水量变化和水土保持措施对流域水沙关系的影响。结果显示,年降水量和水沙变化趋势基本一致,降水量是流域产流和输沙的主要影响因素。桥子东沟在1987—2006年和桥子西沟在1987—2010年时期的年单位径流输沙量没有发生显著变化,表明降水量变化、坡面工程措施和植被措施对流域水沙关系没有显著影响;桥子东沟在2007—2010年期间的年单位径流输沙量显著减小,表明流域水沙关系发生显著改变,这是由于2006年建设的淤地坝通过拦蓄径流泥沙和减少下游沟道侵蚀,导致流域减沙比例大于减水比例。
The relationship between water and sediment in the basin and the response of precipitation and soil and water conservation can provide a scientific basis for evaluating the benefits of soil and water conservation. According to the hydrological and sediment data of Shizi Donggou and Shizi Xigou from 1987 to 2010 in the typical small watershed of the third sub-region of the Loess Plateau, the Mann-Kendall method was used to test the trend of annual precipitation and sediment change. Curve method to analyze the relationship between runoff and sediment load and discuss the influence of precipitation variation and water and soil conservation measures on the relationship between water and sediment. The results show that the trend of annual precipitation and that of water and sediment are basically the same, and the precipitation is the main influencing factor of runoff and sediment transport. There was no significant change in sediment discharge per unit runoff from 1987 to 2006 and from Xizigou at Qiazi in 1987 to 2010, indicating that the change of precipitation, the relationship between slope engineering measures and vegetation measures did not affect the water and sediment discharge in the basin Significantly affected; the annual runoff sediment discharge of Qiaobidonggou decreased significantly during 2007-2010, indicating a significant change in the water and sediment relationship in the basin due to the check and dam sediment reduction in 2006 Downstream channel erosion, resulting in the basin sediment reduction is greater than the proportion of water.