Modeling Organic Pollutants in Tolo Harbour for Waste Load Allocation

Principal Investigator:
Chen, David Yongqin

Co-investigator(s):
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Summary:
Tolo Habour is an important marine water body located in the northeastern part of Hong Kongˇ¦s New Territories. Because of the increasing polluting loads and the limited capacity of the system to assimilate anthropogenic pollutants, the water quality conditions of the Harbour, especially organic pollution and the resulting eutrophication, have been dramatically deteriorating over the past two decades. In order to develop an effective tool for water environment restoration and protection, a comprehensive water quality and watershed modeling study is pressingly needed for the Harbour and its catchment. The first phase of this study is proposed for conducting calibration and validation of a hydrodynamic and water quality model for the receiving water body. The Water Quality Analysis Simulation Program ˇV 5 (WASP5), a highly acclaimed surface water quality model developed and supported by the United States Environmental Protection Agency, will be adopted and applied to simulate the dynamics of Biological Oxygen Demand (BOD5) and nutrients (nitrogen and phosphorus) in Tolo Harbour. This modeling effort will establish the dynamic relationship between the input of pollutants and the spatial and temporal distribution of water quality constituents. A variety of management-oriented applications of site-specific water quality predictions by the modeling system can be made to support environmental decision-making. An important and direct application is waste load allocation that translates ambient water quality objectives into end-of-pipe effluent limits for individual dischargers and acceptable non-point source loadings. An Earmarked Grant proposal will be prepared to request funds for developing a comprehensive modeling framework which will include a GIS-based watershed model for the catchment draining into Tolo Harbour and the WASP5 water quality model.