基于RS和GIS的黄土丘陵沟壑区浅沟侵蚀地形特征研究

Topographic characteristics of ephemeral gully erosion in loess hilly and gully region based on RS and GIS

为了解黄土高原浅沟侵蚀地形特征,基于Qucickbird高分辨率遥感影像和数字高程模型,提取了坡面浅沟及其地形参数,并对浅沟侵蚀的地形特征参数和分布规律进行了统计分析,结果表明:黄土丘陵沟壑区,坡面坡度、长度、坡向以及上坡长度是影响坡面浅沟数量的主要地形要素,而浅沟侵蚀地形特征主要由坡面坡度、坡面长度、上坡长度和汇流面积共同决定;坡面长度与浅沟平均长度呈显著线性关系,坡面坡度与浅沟频度、浅沟坡度与其上坡长度间则均满足二次曲线;发生浅沟侵蚀的上限与下限临界坡度分别介于26～27°和15～20°,临界坡长介于50～80m;由浅沟坡度的正弦值与汇流面积确定出浅沟分布的临界曲线;阳向坡面的平均浅沟长度小于阴向坡面。基于RS和GIS技术能有效确定浅沟侵蚀地形特征,为黄土区坡面水土流失治理提供了技术支撑。

A series of ephemeral gullies and their topographic parameters were extracted from high resolution remote sensing image Quickbird and Digital Elevation Model（DEM）,and analyzed by statistical methods in order to realize the topographic characteristics of ephemeral gully erosion on hill slope in the Loess Plateau.The results showed that the number of ephemeral gully within hill slope was mainly influenced by slope steepness,slope length,aspects and upslope length.The topographic characteristics of ephemeral gully erosion depended on slope steepness,slope length,upslope length and upslope drainage area.The average length of ephemeral gullies within hill slope was linearly correlated with slope length significantly.There was a quadratic curve relation between slope steepness and frequency of ephemeral gully,slope steepness of ephemeral gully and its upslope length.The upper limit of critical slope steepness of ephemeral gully erosion was between 26°and 27°,and the lower limit was between 15°and 20°.In addition,the critical slope length ranged from 50 to 80 m.The critical curve of ephemeral gully distribution was determined based on the sine value of slope steepness of ephemeral gully and upslope drainage area of ephemeral gully.The average length of ephemeral gullies within sunny slope was less than that within shady slope.This study provides an effectual technological support for water and soil conservation on hill slop in loess area.