Influences of topographic index distribution on hydrologically sensitive areas in agricultural watershed
2014
Xue, Lianqing | Bao, Ruiling | Meixner, Thomas | Yang, Guang | Zhang, Jingnan
A hydrologically sensitive area (HSA) is an area with a very quick response to runoff and higher surface runoff probability since all watersheds are prone to generate runoff in one way or the other. The accurate description of runoff generation in time and space has important practical significance for land use and watershed management. The aim of this article was to establish HSAs identification method based on topographic index, and to estimate the spatio-temporal variability of surface runoff probability in different periods. The sensitive month was defined using critical monthly surface runoff probability combined with topographic index. Then the corresponding spatial and temporal boundary of HSA was estimated by the relation of average annual runoff and topographic index. The presented approach was applied in Meishan watershed, which is humid in the summer and has a monsoon climate. The analysis results indicated the probably sensitive months are from February to October with spatial topographic index distribution ranging from 13.02 to 17.13. April–October was estimated as seasonal HSAs with topographic index ranging from 9.21 to 14.05. In addition, the inter-annual variability of seasonal HSAs is much greater and the critical topographic index is 9.21 in July.
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