地形指数算法设计对分布式水文模型径流模拟影响研究

Study on Effects of Topographic Index Algorithm Design Effects on Runoff Simulation of Distributed TOPMODEL

阐述了单流向、多流向的地形指数算法设计思想,介绍了改进的多流向IMFD算法并对其进行了修正,构建了基于TOPMODEL概念的分布式水文模型。以汉江上游的酉水街流域为例,利用不同算法计算地形指数并代入模型检验。结果表明,不同的地形指数算法得到的地形指数及地形指数空间分布曲线均有较大的差别,但对分布式水文模型的径流模拟系数及径流总量模拟影响不大,仅在地表径流和地下径流量的模拟有一定的差别。采用改进的多流向算法模拟精度较高。

On the basis of discourse upon the principle of algorithm design of single flow direction （SFD） and multi flow direction （MFD） involved in Topographic Index （TI） calculation, the IMFD algorithm based on MFD was introduced and an improved IMFD was proposed further to develop a distributed TOPMODEL based on TOPMODEL concepts. In order to classify the role and effects of different topographic index algorithms on the final runoff simulation with the distributed TOPMODEL, we chose a Youshuijie watershed with drainage area of about 946 km^2 on the upper stream of the Hanjiang River Basin as the study site for examination. Four different algorithms were used to compute the TI of the watershed as one driving parameter to run the distributed TOPMODEL. The simulated results suggested that big different existed in the max, rain and mean of the TI computed with these four algorithms and the frequency distribution curve of TI also differed considerably. Rainfall-runoff simulation efficiencies under the 4 differed TI regimes, however, were affected only slightly, only certain differences in the surface runoff and subsurface runoff emerged in simulations. Comparison with the SFD, the MFD leads to a bit higher subsurface runoff and lower surface runoff in simulations generally.