Study On The Water Quality Model Of South Lake

South Lake is located in the Hongshan Block of Wuhan and it is at the south of East Lake and Sha Lake, at the north of Tangxun Lake and Huangjia Lake. For a long time, untreated life trash and sewage are discharged to the lake, which contributed to the increasingly polluted situation of South Lake, where is in eutrophication and ecological function of the water body degenerates dramatically.The sources of South lake pollutants contain city sewage industrial waste surface runoff underground runoff atmosphere rains falling dust and endogene and so on . It can be divided into two main types: the extraneous source and the endogene. The extraneous source includes the point source pollution, with city sewage and industrial waste as its main origin, and non-point sources pollutition, which includes the pollutants of running land surface and the non-land surface running pollutants (rains, falling dust, recreational activity on water surface and so on. The endogene pollution mainly includes the silt in the lake bottom, nutrients of the water body and pollutants discharged by fishery.The necessity of building a water quality model of South lake is studied in this paper, researches on the transformation progress of nutrient elements in deposits in lakes and reservoirs done in China and foreign countries are summarized, Three aspects of research fruits is available:1.Fielding test is introduced in investigating the contamination release rule of sediment in South Lake in Wuhan. The change rules of three indexes, including COD, TN and TP are investigated at the same time. Relationship between these index is probed.2.Theory model of sediment release rule is explained with the kinetics aspect. Release constant of sediment is simulated with the data gained through field test.3. Water quality change model of South Lake is built to simulate the water quality after sewage interception, which is useful for wastewater treatment in South Lake. There are three conclusions as following: (1) One year after sewage interception, COD of Big South Lake is reduced to 33.25 mg/L without change and COD of Small South Lake is increased to 44.34mg/L. (2) When contamination (6 cm depth) release over, the COD of Big South Lake reduced to 19.72 mg/L.(3) About one year after sewage interception, the value of TN of Big South Lake reduced to 6.57 mg/L;theTN value of Small South Lake reduced to 11.60 mg/L then keep unchanging. (4) Two years after sewage interception, the value of TP in Big South Lake reduced to 0.43 mg/L, when contamination (6 cm depth) release over, the TP value reduced to 0.22 mg/L. Wherever, TP value of Small South Lake reduced to 0.49 mg/L after one year of sewage interception.