模拟降雨条件下径流侵蚀力与地貌特征的动态响应关系

Dynamic response relationship between runoff erosivity and topographic feature under the condition of artificial simulated rainfall

本文通过模拟降雨模型试验,用高精度摄影测量、GIS技术和分形理论,对不同雨强条件下小流域模型次降雨径流侵蚀力和地貌形态分形维数变化及其动态响应关系进行了研究。结果表明,基于次降雨洪峰流量模数和径流深乘积的流域尺度径流侵蚀力量化方法揭示了径流的做功效率;大雨强的次降雨径流侵蚀力明显高于小雨强,不同雨强的次降雨径流侵蚀力随模拟降雨场次增加均呈现较为相似的变化趋势;小流域模型历经25场模拟降雨,地貌形态趋于复杂化,地貌形态分形维数呈波动增加趋势;小流域模型地貌形态分形维数的所处取值范围对于相同降雨条件下次降雨径流侵蚀力变化趋势具有决定性影响。本研究揭示了地貌形态特征与次降雨径流侵蚀力空间变异定量作用关系,提高了流域尺度土壤侵蚀预报模型精度和适用性。

The dynamic variation of runoff erosivity in typical small watershed and the response of topographic feature under the condition of single simulated rainfall event with different rainfall intensities were studied. The high precision photogrammetry and GIS technology as well as the fraetal theory were used in data acquisition and analysis. The result shows that the quantitative method for measuring the runoff erosivity, in river basin scale, based on the product of flood peak charge modulus times the mean depth of runoff for single rainfall event can express the power or efficiency of work done by runoff. The magnitude of runoff erosivity in the single rainfall events with high intensity is bigger than those with low intensity, and the runoff erosivity of rainfall event with different rainfall intensities varies in a similar increasing tendency with the number of rainfall event. It tends to increase at first and decreases gradually. The topographic feature of small watershed became more and more complicated and the topographic fractal information dimension tends to increase with the increase of the number of artificial simulated rainfall event. The adopted range of fractal dimension significantly affects the variation tendency of the erosivity. The study result reveals the relationship between topographic characteristics and spatial variation of erosivity and help to elevate the accuracy of soil erosion forecasting.