Predictive Analysis Of Non-point Source Pollution Load In Jialing River Watershed

Non-point source pollution becomes the first pollution source to water environment with controlling of point source pollution. Jialing River is the biggest tributary of the Three Gorges Reservoir, its water quality has direct relationship with the water environment of the Three Gorges Reservoir and even the Changjiang River. Setting up the predicted research on the non-point nitrogen(N) and phosphorus(P) pollution of Jialing River watershed is of important significance to the socioeconomic environment's continuous development of Jialing River watershed and the Three Gorges Reservoir.In the paper, it chooses 2020～2030 as the predicted year and 1997～2007 as the basic year. The research divides the non-point source pollution of Jialing River watershed into three pollution sources: land-use output, live-stocks and agriculture population. It establishes the non-point source pollution load model on the combination of the improved Export Coefficient Approach and the SLURP hydrological model which fit to a large watershed. After the model established, tests and verifies it. Under the verified model, the research uses the following methods to predict the non-point source pollution of Jialing River watershed:①Use the Markov transfer matrix to predict the change of land-use/land-cover.②Choose the B2 climatic change scene of the British Meteorological Bureau Hadley Center's future climatic change model to predict the rainfall runoff in the predicted year.③Predict the live-stocks and agriculture population under the socioeconomic development level and the strategy development goal. Comparing and analysing the predicted year and the basic year's non-point source pollution loads, the main conclusions are as follows:①The non-point source nitrogen and phosphorus pollution loads of Jialing River watershed's outlet has a increasing tendency from the predicted year 2020～2030 to the basic year 1997～2007. Its increasing tendency is similar to the regular pattern of the rainfall runoff.②The three pollution sources'contribution of Jialing River watershed's outlet and the provinces in the watershed has the same change tendency from the predicted year 2020～2030 to the basic year 1997～2007. The contribution of live-stocks'load has an apparent increasing tendency with the time going, the contribution of agriculture population's load has a decreased tendency, the contribution of land-use output has no apparent change with the time going. In the land-use output, farmland's contribution is the biggest and urban area's contribution is the least. The main reasons of this phenomenon are as follows: Firstly, the live-stocks'cultural scale is gradually expanding with the development of the social economy. Secondly, the agriculture population is gradually decreasing with the development of urbanization. Finally, the total area of Jialing River watershed has no changes, the urban area is gradually increasing and farmland is gradually decreasing.③The load intensity of non-point source pollution in Chongqing province and Sichuan province are bigger than the average load intensity in Jialing River watershed, the load intensity of Gansu province and Shanxi province are lower than the average. The load intensity of the all four provinces in the watershed have a increasing from the predicted year 2020～2030 to the basic year 1997～2007, and the load intensity of Sichuan province is increasing fastest. The main pollution source in Sichuan province is live-stocks'load, land-use output is the main pollution source in Gansu and Shanxi province. The main reason is that the pollutant load intensity of the provinces in Jialing River watershed has a close relationship with the socioeconomic development level and the industrial constitution.