Time And Space Distribution Characteristics Of Eutrophication And Water Quality Prediction Based On WASP Model In Poyang Lake

As China’s first large fresh water lakes, the water quality status and forecast of Poyang lake is the basis for the protection of Poyang Lake lake water. By analyzing the water quality data of 10 monitoring sites of Poyang Lake lake from 2003 to 2012,the indexes including BOD5, NH3-N, TN and TP, the paper researched the variation tendency with time of the water quality about the five rivers and Poyang Lake in ten years, respectively. Based on the data of February, June and October, 2008,and the sampling data of October,2014, the paper showed the pollutant concentration linear figure for each index with Surfer software, and analyzed the spatial characteristics. With the fuzzy comprehensive evaluation model, the paper evaluated the water quality of Poyang Lake in the past ten years, meanwhile, evaluated the nutritional status in 2012, then based on the model of WASP7 to simulate and predict the water quality of Poyang Lake. The main research results are as follows:(1) With the processing, analysis and plots of the data about biochemical oxygen demand, ammonia nitrogen, total nitrogen and total phosphorus in ten monitoring sites of the lake and five rivers, the paper got the conclusions of the annual variation of the index concentrations about the water quality : dry > flat season>flood, and the interannual variation of pollutant concentrations is increasing year by year. The spatial distribution of Poyang Lake on the lake water quality is the North better than the South of the lake.(2) With the water quality evaluation results of 2003~2012 monitoring site monitoring data, there are about 50 percent sites data belong to class III in GB3838-2002, and the evaluation results show that flat and dry season are mid-serious eutrophication in 2012 and the flood season is mid- eutrophication..(3) Using the measured data and the simulated value of 2003~2007 to calibrate parameter, and then determinate the model parameters. Model validation: using the detailed sampling data of the whole lake in 2008 from Poyang Lake Research Center to determination of the data to complete the validation of the model in simulation, then using the data from 2009 to 2012, chosed from the simulation output of KangShan range, TangYin range, DuChang range and Xingzi range for example, and analyzed that the errors between monitoring value and the simulating value were below 40% about 96.53 percent of all data,. and it showed that the Water Quality Analysis Simulation Program is feasible for simulation in Poyang Lake.(4) With analyzed the prediction of water quality from 2015 to 2017 in Poyang Lake with the model,the paper selected KangShan range, TangYin range, DuChang range and Xingzi range from the results to evaluate the water quality about NH3-N, TN and TP in dry, flat and flood. The results showed that, the water pollutant concentrations in Poyang Lake are gradually increased from 2015 to 2017, and the evaluation found that, a great probability of whole lake water qualities are beyond the III limit value in 2017. NH3-N, TN and TP model prediction results showed that the annual variation and spatial distribution characteristics are the same as the actual situation.Based on the all researches, this paper put forward some prevention and control measures for Poyang Lake water quality deterioration and eutrophication trend respectively from controling the point sources and non-point sources pollution.