Study on the Effect of Land Use Change on Non-point Source Pollution in Chaohu Watershed-Example of Dongpu Reservoir

As one of the pollution management projects. in the "three rivers and three lakes" basin, pollution in Chaohu watershed has been generally concerned. Taked Dongpu reservoir in upper reach of Chaohu watershed as a case study, the non-point nitrogen load in this basin was estimated by Johnes export coefficient method. The traditional Johnes export coefficient method was improved and the rainfall factor was added, considering the impact of rain. The results showed that the total nitrogen load caused by land use increased from 193 tons in 1996 to 277.9 tons in 2005 by. 44 percents. Crop production land contributed highest to the total nitrogen load, 48.9 percents on average, and population contribution accounted for the second, about 35.1 percents on average, which provides reference for non-point source pollution management in Chaohu watershed. The model was examined using water monitoring data from Dongpu reservoir, which indicated that the improved model is applicable to Chaohu watershed.