Modeling the Influence of River Inflow on Jiaozhou Bay Water Quality Based on FVCOM
|School||Ocean University of China|
|Keywords||FVCOM Jiaozhou Bay Water Quality Simulation River Input Environmental Impact|
Since the 1970s, with the rapid development of Jiaozhou Bay Area and accelerated urbanization process, a large number of industrial wastewater, domestic sewage were discharged into the Jiaozhou Bay through coastal rivers, vertical way of exit port and scramble into the coastal waters of Jiaozhou Bay, it caused Jiaozhou Bay deterioration of water quality. River is the main way of pollutants into the Bay among many sources of pollution.Therefore, it’s necessary to study the major rivers’distribution rate to Jiaozhou Bay water quality, so as to provide quantitative basis to improve the environment and management, and provide scientific basis and technological support for the full implementation of the "Central Bay protection, owned Bay" strategic plan, accelerating the Central Bay watershed pollution comprehensive treatment, and overall improvement in the quality of the ecological environment in Jiaozhou Bay.This thesis simply introduces the background of this kind of study, and summarizes in details the hydrodynamic model and water quality model developing at domestic and foreign. Specific works are listed as follows:1.The barotropic current, in order to provide a dynamic field to the spread of pollutants transport, is calculated by FVCOM tidal numerical model, and verified by comparing with the observationary data obtained in three current stations and two tidal stations.2.On basis of correct calculation of tide current, this thesis sets up three-dimensional conservative substance transport model, and simulate the concentration of CODMn, DIN, and Phosphate in 2007 in Jiaozhou Bay, verified by comparing with the observationary data and previous studies.3.This model was applied to simulate the pollutants’concentration and distribution rate when the major rivers separate sink into Jiaozhou Bay. analyzed and discussed the results in detail.The results shows that:besides the pollution emission, the concentration distribution trends and influence to Jiaozhou Bay water quality of the river discharge is also inextricably linked to the strength of the exchange capacity.(1)As the Dagu River discharge is large, the momentum is large when pollutants sink into the sea, so east-west pollutant diffusion range is larger than other rivers, concentration contours are dense in Dagu River estuary adjacent waters. The tide current direction this area is almost north-south, so the north and south distribution rate is basically the same. The distribution rate in the central Jiaozhou Bay is among 18%-52%,23%-45% in the bay mouth, less than 10% in the northeast coast, the distribution rate in the range within 10.5km-12.15km from Dagu River is larger than 30%.(2)Moshui River is in the northeast corner of Jiaozhou Bay, affected by the landform, the current this area is smaller, water exchange ability is weak, and not conductive to the pollutant dispersion, so the concentration distribution is relatively centralized, concentration contours are dense, the major impact of Jiaozhou Bay water quality is in the northeastern coast, distribution rate is between 35%-58%, is 9%-22% in the central coast, less than 12% in western and bay mouth.(3)Loushan River estuary is more open, water exchange ability is superior to the Moshui River estuary, thus, although emissions is larger than Moshui River,the concentration is lower, and dispersion range is larger. The impact to Jiaozhou Bay is mainly in the area between Licun River estuary and Loushan River, the distribution rate is 30%-52%,20%-35% in northeast, about 7%-24% in central, less than 15% in western coast and bay mouth.(4)There is a clockwise residual gyres in the western coast of Licun River estuary, which reduced pollutants westward diffusion, the pollutant is mainly in the estuary and northeast coast.However, as the influence of Moshui River and Loushan River to this area, the distribution rate of Licun River is lower this area. The impact to Jiaozhou Bay is mainly in the area between Licun River and Haibo River, the distribution rate is 22%-44%, less than 10% in western coast,10%-20% in central and bay mouth, less than 15% in northeast.(5)As clockwise residual gyres has weakened the westward, the pollutant sinked by Haibo River is mainly distributed in the east and northeast coast. However, as the influence of Moshui River and Loushan River to this area is larger, the impact to northeast coast is little, and the impact to Jiaozhou Bay is mainly in the coast nearby the estuary, the distribution rate is 28%-68%, less than 12% in western coast,15%-33% in central coast, less than 15% in northeast coast, and about 17% in the bay mouth.