Outfalls Optimization Settings Of Xiangshan Bay

Xiangshan Bay is an important harbor of the city of Ningbo, with a unique geographical location and resource advantages. The Xiangshan regional marine development and protection have been included in China Ocean Agenda, and also the21st century’s ocean plan of Ningbo City.This paper firstly introduced the unique geographical conditions of Xiangshan Bay, and did the research on the simulation of the current state of the discharge of pollutants let into the sea along the bay, utilizing the FVCOM three dimensional coastal ocean model based on the measured data of the year2009. As Xiangshan Bay is a semi-enclosed narrow shaped bay, its environmental capacity is not large owing to the weak hydrodynamic conditions. The environmental degradation happened along with more and more serious eutrophication, mainly polluted by the factors like inorganic nitrogen and active phosphate, most of the sea water can not meet the appropriate function zoning requirements under the conditions of the emission of pollutants in the status quo. The environment will continuely deteriorate if the conditions of discharge doesn’t change, and result in not able to meet the requirements of the regional development planning.Therfore, on the basis of the research results created by the previous scholars, and concerning the requirements of the regional planning of Xiangshan Bay, simulated the case of setting up a single outfall in different single administrative regions, and did analysis of the results of concentration distribution and the compliance status of the key water quality factors, in order to determine the rationality of the setting up of outfalls in each administrative region.The results shows that:simulating the hydrodynamic conditions of Xiangshan Bay applying the FVCOM model can be more natural to demonstrate its complex geographical construture with many islands and branches, and so, the results of the hydrodynamic conditions can be much closer to the measured data. The survey data of the existing outfalls of Xiangshan Bay is not complete, which is bad for the environmental protection of Xiangshan Bay. Additionally, there were irregularities and even indiscriminate discharge phenomenon in the bay, what resulting the environment of Xiangshan Bay from bad to worse. So the status of discharging needs to be regulated and standarized. After simulations, we come to the conclusion which is consistent with the previous studies, that Xiangshan Bay has a weak hydrodynamic condition and long updating cycle which is not conductive to the sustainable development both of the environment of Xiangshan Bay and the industry along the bay. Althouah we need to consider the balance of economic and environmental benefits in the actual project implementations, from the long run, to meet the environmental constraits and the basis principles in setting outfalls, the location of outfalls can only be adjusted to the door of the bay or the outside sea where the flow has an enough depth, updated rapidly and has little effect on the marine environment of Xiangshan Bay.