集水区尺度降雨侵蚀力空间分布对土壤流失的影响

Effect of spatial distribution of rainfall erosivity on soil loss at catchment scale

为探讨降雨侵蚀力空间分布对土壤流失的影响效应,该文以黄土丘陵沟壑区子长集水区为例,将区域重心概念应用到降雨侵蚀力的空间分布研究中,基于GIS探讨了降雨侵蚀力重心在不同年份间的变迁对土壤流失的影响。研究结果表明:降雨侵蚀力重心与水文站点、大于15?坡度重心的距离会显著影响土壤流失;当降雨侵蚀力重心位于水文站点和较陡坡度重心中间位置时,也会产生较多土壤流失;降雨侵蚀力重心在南北方向上变化对土壤流失影响不大,但在东西方向上的移动能够明显改变土壤流失。在集水区尺度上,随着降雨侵蚀力空间分布的变化,降雨侵蚀力与坡度、土地利用、水文站点的空间耦合关系将发生改变,从而导致土壤流失量的增加或减少。

For identifying the effects of spatial distribution of rainfall erosivity on soil loss,Zichang catchment of Chinese loess hilly-gully area was taken as an example,and the concept of regional gravity center was used to analyze the spatial distribution of rainfall erosivity.The effect of the spatial movement of rainfall erosivity gravity center on soil loss in different years was analyzed based on GIS tools.The results indicated that the distance between gravity centers of rainfall erosivity and hydrological station and that between gravity centers of rainfall erosivity and gravity centers of steep slope grade（higher than 15°）had significant influence on soil loss.When gravity center of rainfall erosivity was in the middle place between hydrological station and gravity centers of steep slope grade（higher than 15°）,there would also be more soil loss.The changes of gravity centres of rainfall erosivity from north to south had little effect on soil loss. However,the changes from west to east had much effect.For catchment,with the changes of spatial distribution of rainfall erosivity,the fitting relations between rainfall erosivity and slope grade,and land use,and hydrological station would be changed,which would lead to the amount of soil loss increased or decreased.