拉萨河流域不同植被类型坡面砾石形态与分布特征

坡面砾石的分布特征显著影响着地表土壤侵蚀及水文过程，而目前针对高寒区坡面砾石形态与分布特征的研究较为薄弱。为此，在西藏拉萨河流域选择9个典型坡面的山坡及其下堆积坡，将其按山坡—堆积坡的植被类型分为草—草坡面(A)、灌草—草坡面(B)和灌草—灌草坡面(C)3类，并对各坡面样点进行现场拍照采样，利用ImageJ软件获取砾石粒径、圆度、形状比率以及覆盖度，分析不同类型坡面砾石的粒度组成、形态特征以及覆盖度，研究坡面砾石的形态与分布特征。结果表明：(1) A类坡面山坡砾石平均粒径显著大于堆积坡，B类坡面山坡和堆积坡砾石平均粒径无显著性差异，C类坡面山坡砾石平均粒径显著小于堆积坡；同一类坡面之间的砾石粒度组成存在差异。(2)整体上A,B,C这3类坡面的山坡和堆积坡砾石圆度和形状比率无显著性差异。(3) A类坡面山坡砾石覆盖度大于堆积坡，B类坡面山坡和堆积坡砾石覆盖度相差不大，C类坡面山坡砾石覆盖度小于堆积坡；同一类坡面之间的砾石覆盖度大小存在差异。(4)同一坡面山坡和堆积坡砾石平均粒径及覆盖度主要受坡度的影响，而同一类坡面之间的砾石粒度组成及覆盖度大小因受植被、气候、岩性、海拔等的影响也存在差异...

Morphology and Distribution Characteristics of Gravel on Slopes of Different Vegetation Types in Lhasa River Basin

The distribution characteristics of gravel on slope have a significant impact on soil erosion and hydrological processes. However, the research on the morphology and distribution characteristics of gravel on slope in alpine region is little known. Nine typical slopes(including hillslope and accumulating slope)in Lhasa River Basin in Tibet were taken as examples. The slopes were divided into three types according to the vegetation types of hillslopes-accumulation slopes: grass-grass slope(A), shrub-grass slope(B)and shrub-grass slope(C). The sample sites of each slope were photographed and sampled on site, and the grain size, roundness, aspect ratio and coverage of gravel were obtained by ImageJ software, and the grain size distribution, morphological characteristics and coverage of gravel on slopes of different types were analyzed, morphology and distribution characteristics of gravel on slopes were studied. The results are as follows.(1)The mean grain size of gravel on hillslope A is significantly larger than that on accumulation slope, but there is no significant difference between hillslope B and accumulation slope, and the average particle size of gravel on hillslope C is significantly smaller than that on accumulation slope There are differences in gravel grain size distribution between the same types of slopes.(2)On the whole, there is no significant difference in the roundness and aspect ratio of the gravels on A, B and C.(3)The gravel coverage of hillslope A is larger than that of the accumulation slope, while the gravel coverage of hillslope B slope is similar to that of accumulation slope, while that of hillslope C is smaller than that of accumulation slope. There are differences in gravel coverage between the same types of slopes(4)The mean grain size and coverage of gravel on the hillslope and accumulation slope of A, B and C are mainly affected by the slope gradient, while the grain size distribution and coverage of gravel on the same types of slopes are also different due to the influence of vegetation, climate, lithology and altitude. The research results can provide a theoretical basis for the study of soil erosion and hydrological process in the Qinghai-Tibet Plateau, and provide scientific support for the control of soil and water loss in this region.