陕北无定河流域土壤侵蚀与植被覆盖和降雨关系研究

基于2000—2014年陕北无定河流域日降水、DEM、土壤类型、MODIS NDVI等数据,利用修正通用土壤流失方程(RUSLE)估算了流域土壤侵蚀情况,定量分析了植被覆盖和降雨在土壤侵蚀中的作用,结果表明:(1)无定河流域土壤侵蚀以微度侵蚀为主,平均占流域面积的88.35%,各土壤侵蚀等级面积比例随等级的升高而降低。2000—2014年微度侵蚀面积比例为下降趋势,轻度及以上等级面积比例均为上升趋势。(2)不考虑降雨因子影响时,无定河流域仍以微度侵蚀为主,且为增加趋势,而其他土壤侵蚀等级均为下降趋势。不考虑植被覆盖因子时,流域土壤侵蚀与模型计算结果的变化趋势基本一致。(3)植被覆盖对土壤侵蚀面积比例和变化速率的贡献率分别为13.67%和24.55%,而降雨作用达到86.33%和75.44%,表明降雨是流域土壤侵蚀的主要动力和控制因子,降雨变化主导着流域土壤侵蚀变化过程。

Study on relationship between soil erosion and vegetation cover & rainfall of Wudinghe River Watershed in northern Shaanxi Province

Based on the data of daily rainfall， DEM， soil type， MODIS NDVI， etc. from 2000 to 2014 of Wudinghe River Watershed in the northern Shaanxi Province， the status of soil erosion in the watershed is estimated herein with the Revised Universal Soil Loss Equation， and then the effects from both vegetation cover and rainfall on soil erosion is quantitatively analyzed as well. The result shows that （1） the soil erosion in Wudinghe River Watershed is mainly the slight erosion， which is 88.35% of the area of the watershed， while the area ratios of all the erosion degrees decrease along with the increases of the degrees. The area ratios of the slight erosion presents a decreasing trend from 2000 to 2014， while all the area ratios of light degree and above show increasing trends； （2） when the impact from the rainfall factor is not considered， the soil erosion in Wudinhe River is mainly the slight erosion with a creasing trend yet， however， all the other soil erosion degrees present decreasing tends. When the factor of vegetation cover is not taken into account， the changing trends of the soil erosion in the watershed and that from the model calculation are basically coincided； （3） the contribution rates from vegetation cover to the area ratio of soil erosion and the changing rate are 13.67% and 24.55% respectively， while the effect from rainfall reaches to 86.33% and 75.44% respectively， which shows that the rainfall is the main motive force and control factor of soil erosion， thus the change of rainfall dominates the changing process of soil erosion in the watershed.