佳芦河流域1988—2013年土壤侵蚀时空变化特征

为了研究陕北风沙区近26年来的土壤侵蚀变化特征,利用中国坡面水蚀预报模型结合GIS和RS技术,定量估算了1988-1996,1997-2004,2005-2013年3个时段陕北佳芦河流域土壤平均侵蚀量,分析了不同植被覆盖条件下和不同土地利用类型下的土壤侵蚀时空变化特征.结果表明:(1)中国坡面水蚀预报模型适用于该地区;(2)土壤侵蚀等级和降雨侵蚀力,地貌和土地利用类型关系密切;(3)将26年划分为3个时段,第1时段1988-1996年、第2时段1997-2004年和第3时段2005-2013年.多年平均降雨侵蚀力分别为923.09,1 010.75,1 551.40 MJ·mm/(hm2·h),对应土壤侵蚀模数分别为4 513,5 855,3 556t/(km2·a).第1时段和第3时段总侵蚀量分别为5.10×106,4.02×106 t,相比减少了21.18％.还林还草工程后,流域内土地利用发生较大变化,耕地所占比重由53.38％减少到25.87％,草地所占比重由38.64％增加到69.64％,不同土地利用类型的水土保持效益从大到小分别是未利用土地,草地,林地和耕地.说明当还林还草工程后,佳芦河流域土壤侵蚀呈现总量减少,强度降低的趋势,表明还林还草工程取得了明显的水土保持效益.

The Characteristic of Temporal and Spatial Variation of Soil Erosion Change in Jialu River Watershed from1988 to 2013

In order to characterize the soil erosion change in windy desert region of northern Shaanxi Province in the last 26 years,the Chinese Water Erosion on Hillslopes Model was combined with GIS and RS technic to assess the average erosion amount of Jialu River watershed in 3 period years (1988-1996,1997-2004 and 2005-2013),and analyze temporal and spatial variation characteristics of soil erosion under different vegetation coverage and different land use patterns.The results showed that (1) the Chinese Water Erosion on Hillslopes Model is suitable to predict erosion in the study area;(2) Soil erosion intensity was closely related to the spatial distribution of rainfall erosivity (R),topography and land use patterns;(3) 26 years were divided into three periods,the first period of 1988-1996,the second period of 1997-2004 and the third period of 2005-2013,the corresponding mean annual R factor were 923.09,1 010.75 and 1 551.40 MJ · mm/(hm2 · h).The soil erosion modulus were 4 513,5 855 and 3 556 t/(km2 · a).The total soil loss of the first and third periods respectively were 5.10 × 106 t and 4.02 × 106 t,reduced by 21.18 ％.The land use patterns greatly changed in the watershed after Green for Grain Project.The area of cultivated land decreased from 53.38％ to 25.87％,while the grassland increased from 38.64％ to 69.64％.The descending order of soil erosion intensity in different land use was unused land,grassland,forestland and cropland,so the benefit of soil and water conservation was the most obvious in unused land and grassland.So Green for Grain Project has already obtained obvious benefit of water and soil conservation.