Calculations of Environmental Capacity and Pollutant Load Reduction by the Delft3d Model for the Development of Aquaculture in the Bach Dang Estuary Area

Duc Cuong Le^1,2, LuLu Qiao³, Thi Thu Trang Cao², Dinh Lan Tran², Anh Tu Tran², Thanh Nghi Duong², and Bui Van Vuong²

1. Graduate University of Science and Technology, Hanoi, Vietnam

2. Institute of Marine Environment and Resources, Hai Phong, Vietnam

3. College of Marine Geosciences, Ocean University of China, Qingdao, China

Abstract: This study presents the results of research on water exchange and the environmental capacities of total suspended sediment (TSS), inorganic nutrients (PO₄^3-, NO₃^- and NH₄⁺), and heavy metals (As, Hg, Cu, Cd, Pb, and Zn) in the receiving water of the Bach Dang estuary area. The database used in this study is from a collaboration project between Vietnam and China called “Comparative study of Holocene sedimentary evolution of the Yangtze River Delta and Red River Delta”. The data were collected in Vietnam during another project by the Institute of Marine Environment and Resources (IMER). The results of the environmental carrying capacity of water are used to manage the carrying capacity to ensure sustainable development. The simulation was performed by using numerical models, and the patterns were established by applying the three-dimensional Delft3D model (Delft3D) to verify the water level data. The data were calculated in July and March, which represent the wet and dry seasons in the region, respectively. The results showed that the volumes of TSS, nutrients, and heavy metals in the waters met their potential carrying capacities. During the aquaculture processes in the wet season, the TSS and NO₃^- factors polluted the water in Vietnam, with average values of 98 g/m³ and 0.081 gN/m³, respectively, while the other factors did not cause pollution in the study area. During the dry season, only the NO₃^- factor was polluted in the water body, with an average value of 0.096 gN/m³, and the other factors were not polluted in the water environment.

Key words: delft3D, environmental capacity, bach dang estuary, TSS, nutrients, heavy metals