Abstract:

Watershed of Sanshuihe which lied in southern part of Ziwuling mountains on the Loess Plateau was chose as a case in this paper, and depth of annual runoff, maximum monthly runoff, erosion modulus and sediment content were chose as parameters of hydrological process. Deforestation of last 26 years was obtained by remote monitor and interpolation. The relationships between deforestation and parameters of hydrological process were analyzed quantitatively, and the regression models of hydrological process were established depending on rainfall and deforestation. The results showed: Deforestation in Sanshuihe watershed has led up to increasing in annual runoff depth by 62.85%, in annual erosion modulus by 90.76%, in maximum monthly runoff by 58.36% and in sediment content by 63.21%. Respectively over the past three decades. The contribution percentage of the reduction in forest area to the increase in annual runoff depth was 72.35%, to the increase in maximum runoff was 45.18%, to the increase in erosion modulus and mean sediment content of river by 86.73% and 79.61% respectively.

Key words: deforestation, the Loess Plateau, dydrological process, Sanshuihe watershed