Abstract:

 In this paper, we propose a practical method for quantitative assessment of regional water conservation based on regional water balance, actual evapotranspiration from land surfaces calculated by applying the principles of the surface energy balance system, and surface runoff by SCS (Soil Conservation Service) model. Using this method and GIS software platform combined with meteorological data from 1980 to 2003, we calculated and analyzed the spatial distribution and its variation of water conservation in Qilian Mountains.  The result shows that: (1) in the water conversation area of Qilian Mountains, waterholding capacities in central and southeastern region are higher than that of in western region; (2) waterholding capacities in central and southeastern region have been decreasing obviously, and the deterioration area was constantly formed with the Menyuan Hui autonomous county as the center.

Key words:  water conservation, land evapotranspiration, SCS model