Study On Simulation Of The Water Environmental Capacity Change And Controlling Measures Of The Total Amount Pollutants Discharge In Jiulong River Watershed

The total amount control of water pollutants based on the water environmental capacity theory is the trend of water pollution control. With the rapid development of society and economy, the water pollution problem is becoming increasingly serious in China; the total amount control of water pollutants must be launched effectively with sound scientific and tenologic basis. It is theoretically and practically significant to study the simulation of the water environmental capacity and controlling mesarues of the total amount pollutants discharge in the Watershed.In this study, the QUAL2K water quality model was applied to establish the Jiulong River water quality model. The trial and error method was used to simulate the water environmental capacity of the abundance, peace, dry period respectively in the Jiulong river watershed. A series of measures and recommendations for the total amount control of water pollutants of Jiulong river watershed were brought forward.The main conclusions are as follows:First, the main sources of water pollution in Jiulong river watershed are identified by investigation, including industrial wastewater, sewage, solid waste pollution, animal excrement and agricultural runoff pollution, and so on. The main pollution items are identified through water quality assessment, including biochemical oxygen demand, ammonia nitrogen, total phosphorus and fecal coliform. These four pollutants are chosen as the indicators of water qulity modeling and water environmental capacity calculation.Second, the QUAL2K water quality model is chosen and applied to establish the Jiulong River water quality model through the segment division and model parameter calibration. The Beixi river is divided into 20 reachs, and the Xixi river is divided into 6 reachs. The model parameter, including the the oxidation rate of fast CBOD, the nitrification rate of ammonia nitrogen, the hydrolysis rate of organic phosphorus, and the decay rate of the pathogens are calibrated. The model validation shows that the model has good precision and is suitable for the Jiulong River water quality simulation and forecasting.Third, the historical hydrological monitoring data of the Hydrologic Stations in Jiulong River Watershed are used to calculate the flow frequency, and the 90%, 75%, 50% guaranteed rate runoff are used to represent the flow of the dry, peace, abundance period respectively. The water environmental capacity of the mainstream of the Jiulong River is quantitatively simulated in different flow conditions, including the capacity of the biochemical oxygen demand, the ammonia nitrogen, the total phosphorus and the fecal coliform.Fourth, the predicted water pollution load of the late "11th Five-Year Plan" in 2010 is compared with the simulation results of the water environmental capacity. The pollutants reduction amounts and rates that should be cut down are calculated in different reaches to make sure that the water quality of all fuction zones could reach the requirement according to the water quality standard. The Proposals to the layout adjustment of the industry, aquaculture, and etc. are brought forward. Finally, according to the actual situation of Jiulong River Basin, several economic, technical and supervision measures were brought forward to guarantee the total amount control of water pollutants could be launched effectively.