中文摘要：

流域水土保持措施改变了下垫面条件,从而导致洪水洪峰和洪量减小。根据冷口以上流域以工程为主的水土保持措施特点,提出了采用水土保持工程修建前后两场相似大暴雨产生的洪水过程来估算水土保持工程蓄水容量的方法,计算出冷口以上流域水土保持工程蓄水容量约为7.8mm,并采用统计方法估算了水土保持工程措施集水面积约占全流域面积的73%。在此基础上,推求了冷口以上流域水土保持工程对历史洪水洪峰和洪量的影响程度。结果表明,水土保持工程对冷口以上流域历史洪水洪量的影响程度随洪水量级增加而减小,对洪峰的影响程度与暴雨的时程分配有关,对主雨峰靠前的洪峰影响程度大,对主雨峰靠后且前期有降雨的洪峰影响程度小。研究结果对于水土保持措施保水效益评价提供了参考。

英文摘要：

Underlying ures, which influence surface has changed due to human activities, especially soil and water conservation meas- runoff generation and road response. In Lengkou watershed, engeneering such as check dam is the main soil and water conservationmeasure. Due to the large number of engineering in the watershed, it is impossible to calculate the water storage capacity and drainage area of the soil and water conservation engi- neering. So in this paper, a method was presented to estimate the water storage capacity of the soil and water conseration engineering using historical hydrlogical data, and the water storage capacity is about 7.8mm. The relationship between maximum 1h rainfall amount and flood peak was established, and according to this equa- tion, the drainage area of engineering was estimated as 73 % of the whole drainage area of Lengkou watershed. On the basis of the water storage capacity of the soil and water conservation engineering, the effects of soil and water conservation engineering on flood peak and flood volume were assessed. The results showed that the decreased percentage on flood volume was reduced with the increasing flood volume, but the decreased percentage on flood peak was influenced by rainfall timedistribution. The results can give support to soil and water conservation benifit assessment.