| After industry point source pollution is effectively controlled, the non-point source pollution control technologies and measures have become main research directions. Land use is one of driving forces of non-point source pollution, different kinds of land use and their combinations affect various transformation processes of nutrient substance, then lead to different pollutant loads.DanJiangKou Reservoir are the source of Sourth to North Water Transfers, and it is essential to protect its water quality. HuangShui River watershed is a typical representative in DanJiangKou Reservoir, the elevation changes largely and the precipitation is concentrated, so the soil and water loss is severe in the watershed. Besides, the use of pesticides, fertilizers and sewage discharge also result in non-point source pollution to some extent. Therefore, with the support of ArcGIS, SWAT model was used to simulate the non-point source pollution load and their spatial distribution under landuse change by parameterization. Land use optimization management was put forward for water quality protecting in HuangShui River watershed. The main contents are as follows:1. Establishment of basic geographic information system databases in HuangShui River Basin. Land use maps of2000and2007have been acquired with ENVI which is a remote sensing interpretation software. Using ArcGIS software as platform, the soil and land use spatial databases are established. With the help of SPAW, MATLAB, Excel, Dew02and PcpSTAT, the parameters in SWAT model databases are calculated, and soil attribute database and meteorological databases are built.2. Analysis of the sensitivity and application of SWAT module is to ensure that it is applicability in HuangShui River watershed. Firstly, sensitivity parameters are selected, such as, Alpha_Bf, Cn2, Esco, Sol_Z, Sol_Awc, Revapmn, Canmx, Surlag, Sol_K and Gw_Delay. The measured flow data in2009are set as based data, and automatic calibration module was used to adjust SWAT model. Measured flow in2010are set as reference, and the errors between measured and simulated values are less than40%. The correlation in June, July, August, September are0.7768,0.9367,0.8686and0.8909respectively. And the deterministic coefficient are respectively0.9509,0.8951,0.9025and0.8911respectively.3. Simulating non-point sources pollution loading based on different land use (2000and2007), and the impace of land use to non-point sources pollution are analyzed. The results show that:(1) the land use patterns in2007are more rational in general.(2) the unit load of N-NO3is2-4times of organic nitrogen, and the organic phosphorus content is much higher than that of dissolved phosphorus. Phosphorus and nitrogen load and surface runoff are positively correlated, and organic phosphorus and sediment load are remarkablely positive correlation.(3) the bigger the slope, the more serious the non-point source pollutions is.(4) The southwest of HuangShui River is covered with forest, the non-point pollution is smaller, while the northeast is covered with cultivated land and construction land, and the non-point source pollution load is bigger.(5) The ecotone of woodland and cultivated land is more prone to change, and these regions produce more non-point source pollution, of which the most is woodland transferring to cultivate land.(6) The outlet of watershed and main river produce more non-point source pollution.4. Set four different scenarios, the influnences of land use to non-point source pollution is analyzed. The results show that:(1) woodland can be very good to weaken the non-point source pollution;(2) the total nitrogen and total phosphorus concentration produced in woodland is4.15kg/hm2and0.15kg/hm2in scenario1. The total nitrogen and total phosphorus concentration produced in cultivated land are9.67kg/hm2-12.34kg/hm2and4.59kg/hm2-5.43kg/hm2calculated in scenario2and3. |
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