黄土高原流域土地利用变化的水土流失效应

Effects of land use changes on river basin soil and water loss in loess plateau

本文以黄土高原中部的河流域为例,利用3个不同时期的遥感影像分析了1977年以来的河流域的土地利用变化特征,在此基础上,选择年径流深度、年侵蚀模数、汛期径流深度、汛期侵蚀模数和枯季径流深度为水土流失过程参数,通过基于流域降水与水土流失过程各参数的统计回归模拟分析,区分出了降水和土地利用等地表属性变化分别导致的流域水土流失变化过程。研究结果认为:1980年以来,流域水土流失明显趋缓,以10年为尺度得出的平均值,径流深度减少了32.75mm,侵蚀模数减少了778t/km2。水土流失的变化主要是由地表属性变化引起的,降水量变化的贡献很小。耕地面积变化和地表属性变化引起的水土流失变化具有显著的相关性,坡耕地改梯田的农田水利建设可能是导致水土流失变化的主要原因。

The changes of land use in the Nahe River basin, China, which located at loess plateau area, was analyzed according to the remote sensing images obtained in last 30 years. On this basis, the annual runoff depth, annual erosion modulus, flood season runoff, flood season sediment transport and dry season runoff were selected as the main parameters to study the variation of soil and water loss of the river basin due to the changes of land use by statistical regression method. The result shows that the soil and water loss tends to be mitigated since 1980＇ s. The decadal average runoff flow depth decreases by 32.75mm, and the erosion modulus reduced by 778t/km^2. This change of soil and water loss is mainly caused by the change of land surface property. The contribution of precipitation is not significant. The transformation of cultivated sloppy land into terraced field leads to the change of soil and water loss.