模拟降雨下流域不同地貌单元形态演变特征

Geomorphic Evolution Characteristics of Different Topographic Units in Small Watershed

利用室内小流域概化模型和人工模拟降雨试验,分析了在60、90、120、150 mm/h降雨强度下概化流域内支沟和全流域等不同地貌单元形态演变特征。结果表明:随着模拟降雨场次增加和降雨强度的增大,地貌分形信息维数呈明显的增大趋势,各支沟和全流域沟网不断发育,各地貌单元的地貌形态逐渐复杂,而且支沟和全流域地貌形态变化过程呈现出不同的阶段性,支沟地貌形态变化较全流域更为剧烈;随降雨强度增大和降雨场次的增加,支沟和全流域等地貌单元地貌信息熵单调增大,且支沟沟网起伏程度大于全流域,随着空间尺度增大,地貌形态演变剧烈程度有所降低。

Geomorphic evolution characteristics of the different topographic units in small watershed were quantified under the rainfall intensities of 60,90,120 and 150 mm/h using generalized small watershed model with the simulated rainfall experiment. The results show that with the increase of simulated rainfall and rainfall intensity,the fractal dimension of the different topographic units increase obviously. So,the gully network of each branch ditch and the whole basin develops continuously and the geomorphologies of the different topographic units are complicated gradually. Moreover,the processes of geomorphic evolution of the different topographic units are different at the different rainfall intensities. With the increase of simulated rainfall and rainfall intensity,geomorphic comentropy of the different topographic units increases monotonically. And the network evolution fluctuation of each branch is greater than that of the whole basin. With the increase of spatial scale,the intensity of geomorphic evolution decreases.