Hydrological Effects of Forest Landscape Patterns in the Qilian Mountains
2005
Guojing, Yang | Duning, Xiao | Lihua, Zhou | Cuiwen, Tang
The relationship between vegetation and water budgets in mountain catchments has been the subject of intense debate from an ecological as well as a hydrological point of view. In the present article, we evaluate forest landscape patterns and their hydrological effects on the Qilian Mountains of northwest China, using GIS and 15 years (1987 to 2001) of hydrological databases to illustrate the cases of 2 catchments, Dayekou (DYK) and Haichaoba (HCB). Landsat ETM⁺ remote sensing satellite data (1:50,000) taken in May 2001 and topographic maps (1:50,000) were used to produce the landscape maps. The results showed that the main landscape elements affecting hydrological processes were grassland and Picea crassifolia forest in the lower areas in DYK, while the main landscape elements affecting hydrological processes in the higher areas in HCB were shrub-land and barren land. Observations over many years indicate that the water retention capacity of Picea crassifolia forest makes it the best of all vegetation types for hydrological purposes in the area. In DYK, evapotranspiration was 61%, and runoff was 39% of rainfall, whereas in HCB, evapotranspiration was 41%, and runoff was 59% of rainfall. However, dry season runoff in DYK (25.2%) was higher than in HCB (17.7%). Our results show that the various forest landscapes cause different hydrological processes in arid mountain areas in northwest China.
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