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.