Abstract: Rivers are generally facing the interception by dams all over the world, leading to the conversion of rivers from natural state into “impounding river”. The transport fluxes and retention of nitrogen and phosphorus in the river system are key issues for evaluating the water environmental impact of reservoirs. In this study, three cascade reservoirs (Hongjiadu, Dongfeng and Wujiangdu) along the upper reaches of Wujiang River basin were investigated to understand the distribution patterns, transport fluxes and retention of nitrogen and phosphorus in these reservoirs. The annual retention rates of total nitrogen (TN) of Hongjiadu, Dongfeng and Wujiangdu reservoirs were 20.2%, 36.0%, and -21.1%, while that of total phosphorus (TP) were 5.4%,56.5% and -84.9%, respectively. The three reservoirs had different retention effects and spatiotemporal patterns due to differences in hydrologic conditions, reservoir running time and anthropogenic factors. The annual retention rates of TN and TP in Wujiangdu Reservoir were negative due to the influence of cage fishery. However, Dongfeng Reservoir showed obvious nutrient retention. The nutrient retention in Hongjiadu Reservoir was weaker than that in Dongfeng Reservoir because of the degradation of plants previously buried in Hongjiadu Reservoir.

Key words: Tengger Desert, soil particles, soil physical and chemical properties, straw checkerboard, sand-binding revegetation, soil fractal dimension