不同集水面积阈值确定方法在典型黄土侵蚀地貌区的适用性分析

针对不同集水面积阈值确定方法的适用性问题,结合流域地貌侵蚀发育理论和侵蚀阶段—水系分维数关系判断了理论水系分维数大小,以水系分维数作为评判指标,分析了不同集水面积阈值确定方法的适用性,并以此为基础建立了一套无“蓝线”河网情况下检验集水面积阈值确定方法合理性的完整体系。实例应用结果表明,泾河流域水系结构具有典型的分形特征,其理论水系分维数应在1.4~1.6之间;受黄土地貌软弱岩性的影响,河网密度法及河道分支法在黄土沟壑地貌中具有良好的适用性,能较为细致地反映沟谷河道的准确信息;河源最小误差法及试错法下的水系分维数与理论值存在较大偏差,只适用于地形地貌变化不大的小型流域。

Applicability Analysis of Different Flow Accumulation Threshold Determination Methods in Loess Eroded Area

A method based on the theory of geomorphic development and drainage fractal dimension is proposed for testing the rationality of different threshold determination methods for catchment area. Selecting drainage fractal dimension as identification index, the applicability of different catchment area threshold is analyzed. The results show that water system structure of Jinghe basin has a typical fractal characteristics and the theoretical drainage fractal dimension is in the range of 1.4 and 1.6. The drainage density method and channel branch method have a good applicability in the watershed of the loess hilly landform and can reflect the accurate information of gully channel. There is larger deviation between the theoretical value and the drainage fractal dimension obtained by the river source minimum error method and trial and error method, which is only applicable to small watershed with little change of topography.