基于改进型多流向算法的地形指数空间尺度变化分析

Analysis of the Variation of Topographic Index Spatial Scale Based on the Modified Multiple Flow Direction Algorithm

地形指数ln(α/tanβ)是流域径流源面积和地下水水位空间分布特征的近似表征,是地形特征参数化的重要指标。基于改进后的地形指数多流向计算方法,在0.5°×0.5°的区域气候模式尺度框架下,探讨了地形离散和平滑效应分别对地形指数尺度变化的影响程度;研究了地形指数在100和1 000 m栅格尺度上的相关性,给出两者在空间尺度上的转换关系;分析区域尺度和全球尺度下地形指数尺度转换的差异及原因。研究结果可以增强地形信息在大尺度水文模型及陆面水文过程中的适用能力。

Topographic index is an important parameter of topographic characteristics, which is normally used to approximately characterize the spatial distribution of source area of surface runoff and ground water tables in a catchment. Under the 0.5°×0.5° regional climate model scoop, calculated by the modified multiple flow direction algorithm, resulted from the terrain discretization and smoothing effects was explored, the statistic correlations of topographic indexes in 100 m and 1000 m grid size scales were quantitatively analyzed respectively and the transferring relations between these two resolutions in regional scale modeling applications were given. Consequently, differences in mean topographic indexes computed from regional climate model grid-size scale and GCMs were discussed and compared. This result has a practical implication for large scale hydrological model. Especially, this study opens a way to accurate terrain analyses to be used in the land-surface process modeling for regional scale application.