Optimization of Channel Outlet in the Coastal Area — Application to Da Nang Bay, Viet Nam

Abstract

The water quality of Da Nang Bay (Viet Nam) is one of the major issues on Da Nang City's coast. The discharge of the Phu Loc (PL) channel will be inserted through the outlet into Da Nang Bay. However, the PL channel receives many sources of wastewater so the highly polluted channel water. Therefore, the outlet of PL channel has become the environmental hotspot of the Da Nang Sea. Mike 21 FM Hydrodynamics module coupled with a water quality model using Mike 21 FM ECOLab module is used to simulate water quality and to identify the spreading of NH4+, which is used as a pollutant tracer. Currently, the outlet of PL channel generates the polluted area along the coast in different directions depending on the current and the direction of the wind. This study proposes three scenarios of designing the outlet far from the coastline 400 m, 500 m, and 600 m, respectively. The finding of this research demonstrates that the best way to discharge the wastewater from PL channel would be the outlet to be moved 500 m away from the coastline. NH4+ concentration > 0.2 mg/l will cover an area that distributes about 100 m around the coastline. NH4+ concentration > 0.5 mg/l covers an area approximately 0.03 km2.