Effects of forest change on runoff and sediment in Three-Gorge Region of Yangtze River

Based on the observations on forest, runoff, sediment, from Wuduhe watershed in Three-Gorge Region of Yangtze River, The properties of runoff and sediment movement are studied by the method of watershed comparison with itself. The influence of forest change on annual runoff, scanty runoff, ratio of peak discharge to low flow and annual sediment delivery modulus is also studied. The results show that annual runoff will increase by 3.75mm and scanty runoff will decrease by 4.61mm if forest cover decreases by 1%, and annual runoff will increase by 3.75mm and scanty runoff will decrease by 4.87mm if forest volume decreases by 10,000 m(3). At the same time, ratio of peak discharge to low flow will increase by 0.83 and annual sediment delivery modulus will increase by 67.5 t.km(-2).a(-1) if forest cover decreases by 1%, and ratio of peak discharge to low flow will increase by 0.88 and annual sediment delivery modulus will increase by 71.3 t.km(-2).a(-1) if forest volume decreases by 10,000 m(3).