冀北土石山区坡面尺度径流特征及其影响因素

为了揭示区域水土流失规律,以冀北土石山区坡面径流小区定位观测资料为基础,对坡面尺度产流特征与地形因子、降雨因子、植被覆盖、水土保持工程措施等主要影响因素的关系进行分析,拟为该区水土流失防治及生态建设提供科学参考。研究结果表明:坡面径流小区的年径流量随坡度的增加出现先增后减的趋势,坡度临界值在11°00′左右;坡面径流小区的年径流量随坡长的增加而增加;不同坡度和不同坡长条件下,径流量与有效降雨量及平均降雨强度都成正相关,但与有效降雨量的相关系数要大于平均降雨强度的相关系数且在0.01水平上显著,与平均降雨强度的相关系数不显著;坡面径流小区的年径流量随着植被覆盖度的增加而减少,但覆盖度为60%和90%的草地径流小区的年径流量相差甚小,说明在水土保持治理过程中存在着临界植被覆盖度;水平阶、鱼鳞坑、梯田等水土保持工程措施通过改变下垫面状况,可以有效拦蓄径流,从而削弱降雨特征对径流的影响。

Characteristics of surface runoff and its influencing factors on slope scale in rocky mountain area of northern Hebei province

In order to reveal the rules of water and soil losses in different regions,the relations between runoff yield characteristics and its main influencing factors including landform factors,rainfall factors,vegetation coverage and engineering measures for soil and water conservation on slope scale were discussed based on observed data of runoff plots in rocky mountain area of northern Hebei province.The result showed that the annual runoff yield in the runoff plots firstly increased,and then decreased with increasing slope gradients,the critical slope gradient was about 11°00’.The annual runoff yield in the runoff plots increased with increasing slope lengths.There was a positive correlation between the surface runoff and effective rainfall as well as average rainfall intensity in different slope degree and slope length.However,the correlation between the surface runoff and effective rainfall was significance at 0.01 level,while the correlation coefficient between the surface runoff and average rainfall intensity was not noticeable.The annual runoff yield in the runoff plots decreased as vegetation coverage increased,there was little difference between the runoff yields of the grassland runoff plots with vegetation cover rate of 60% and 90%,which indicated that there existed a critical vegetation coverage in the harnessing of soil and water conservation.Soil and water conservation engineering measures such as level bench,fish-scale pits and terrace can retain surface runoff effectively as well as reduce the impacts of rainfall characteristics on surface runoff through changing underlying surfaces.The research can provide a scientific reference for soil erosion control and ecological construction in rocky mountain area of North China.