Impact of hydropower development on annual runoff and sediment transport distribution

Based on the conception of Gini coefficient and the relationship between downstream and upstream natural runoff and sediment and the regional precipitation, we establish computational models of annual distribution of runoff and sedmient transport from Lancang River, southwest China.The results from the contrast between reconstructed and measured data show that the annual runoff distribution evenness of Lancang River increases by 1.14% and varies between 7.32% and 10.81%; however, the annual sediment transport distribution evenness decreases by 0.23% and ranges from 18.98% to 26.76% since the construction of Manwan and Dacaoshan hydroelectric power plants, and during the operation period of Manwan and Dacaoshan power plants, the annual runoff distribution evenness of Lanchang River is an increase of 3.90% and the annual sedmient transport distribution evennessis down by 0.42%.After the construction of Dacaoshan hydroelectric power plant, it is shows the trend of growth continuously of the annual runoff distribution evenness of Lancang River, but the annual sediment transport distribution evenness has no sign ificant change.All of these indicate that the interaction between runoff and sediment transport has changed, whereas the change is smoothly.The research results not only can provide a way for the relevant research but also offer new evidence to scientifically evaluate the influence of hydropower development on annual runoff and sedmient transport distribution of Lancang River.