不同尺度下影响水土流失地形因子指标的分析与选取

Analysis and selection of topographical indices influencing soil loss on different scales

回顾了国内外土壤侵蚀模型中不同地形指标及地形因子的提取技术,认为无论是统计模型还是物理模型,其采用的地形指标均局限于坡面或沟道,而对大尺度范围内的地形因子研究较少。本研究根据地貌学意义和水土保持学意义的不同,以宏观水土流失评价与预测为目的,主要选取了宏观尺度上的地形指标,认为坡度是微观尺度(如1∶1万,1∶5万)的最佳应用指标,而在宏观尺度上(如1∶100万)则可选择地形起伏度、河网密度、地形粗糙度和高程变异系数等作为分析指标。

Landform is one of the most important factors influencing soil loss.Developing and establishing soil erosion models is an important approach to monitor and evaluate soil loss and soil and water conservation.However,for different scales and different purposes of research,the topographic factors to be considered are selected differently.In this paper,firstly,the topographical indices employed in international and domestic soil erosion models and their extraction technology are reviewed.The result of the review suggests that,regardless of the models employed,be they statistic models based on the experimental materials or models based on the soil erosion mechanism,the topographical indices used mostly derive from small areas such as slope land or small watersheds.Research at the regional scale has been limited.Based on the analysis of significance in geomorphology and soil erosion,this paper concludes that slope gradient is the optimal index used in micro-scale research.Relief,drainage networks density,landform roughness and variance coefficient in elevation,which are regional characteristics,are better used in macro-scale research.However,to determine which regional index or indices are optimal in a specific macro-scale study,concrete research or experimentation must be carried out.