基于地形带分类的最佳阈值与河网密度关系研究

Research on the Relationship Between Optimal Drainage Area Threshold and River Network Density by Terrain Classification

为了使分布式水文模型计算单元更好地反映垫面特性,基于地形带的分类,运用ArcGIS软件的划分单元面积功能,采用改进的适度指数法推求长江上游研究区流域的最佳阈值,能够最终确定不同地形带流域河网密度与最佳阈值的关系。实例结果表明:采用改进的适度指数法可以生成反映实际水系,且与蓝网拟合程度高的模拟河网;根据不同地形带的河网密度与最佳阈值关系和已知蓝线河网密度,可以快速得到流域的最佳阈值。

The objective of this research is to better reflect the watershed land surface characteristics of computing units in distributed hydrological model. According to selected indexes,the terrain in the studied watershed was classified. On the basis of the classification and the division unit area function of ArcGIS,the optimal drainage area threshold of the studied area in the upstream of Yangtze River is obtained by using improved fitness index method, then the relationship between drainage area threshold and river network density could be determined. Results show that by using improved fitness index method,the simulated river network could reflect the actual river system and is reasonably close to the reality. According to the relationship,the optimal drainage area threshold could be obtained quickly given the blue line network density.