基于数字高程模型的流域变动等流时线方法

Watershed variable isochrones method based on DEM

本文探讨了降雨的空间分布和地形对流域等流时线的影响,提出了变动等流时线的新方法,该方法避免了传统等流时线假设流速在全流域均匀分布的缺陷,并且同时考虑了地形和降雨空间分布不均匀性对流速的影响。本文利用数字地形分析技术从DEM数据中提取流域数字水系以及地形地貌等空间特征,在此基础上,对降雨进行空间插值,获得降雨的空间分布,综合考虑地形和降雨因素,推求流域变动等流时线,更进一步真实反映流域的产汇流机制。该方法应用于缺乏实测资料的小流域,应用结果表明基于数字水系推求的变动等流时线体现了地形和降雨的空间分布不均匀性对流域径流的综合影响。

The influences of rainfall and slope on isochrones are discussed based on digital elevation model and a new method of deriving variable isochrones is proposed. The new method takes variability of rainfall and topography into account and overcomes the defect in traditional isochrones method, which assumes the flow velocity distribution is even in the whole watershed. The digital stream networks and topography characteristics are extracted from DEM, on these basis, the spatial distributions of rainfall are obtained by interpolation. Then, rainfall and slope are both being considered to derive watershed varibale isochrones, which can further reflect the transformation process of rainfall-runoff. The method is applied to analyze a small watershed without hydrological record. The result shows that the proposed method can reflect the comprehensive effects of topography and uneven distribution of rainfall on watershed runoff.