Simulation of Water Quality in Bung Binh Thien Lake, An Giang Province, Vietnam, Using the Delft3D Model

Abstract

Bung Binh Thien Lake, the largest freshwater lake in An Giang, is vital for providing drinking water, supporting agriculture, and sustaining local services. Recently, the lake has been facing organic pollution from household wastewater and local production activities. This study evaluated the water quality using biochemical oxygen demand (BOD₅) and dissolved oxygen (DO) parameters, collecting nine water samples from different locations. The DELWAQ model was applied to assess seasonal changes and water quality distribution. During the 2022 rainy season, the average DO value was 5.42 mg/L, meeting the A2 class standard (≥ 5 mg/L), while the BOD₅ value was 12.25 mg/L, within the B1 class standard (≤ 15 mg/L). In the dry season, the DO value dropped to 4.82 mg/L, and the BOD₅ value increased to 12.63 mg/L, indicating higher phytoplankton density and organic pollution. The simulated DO and BOD₅ values closely matched observed values, with NSE values of 0.74 and 0.87 for DO and BOD₅, respectively, in the flood season, and 0.86 and 0.88 in the dry season. The DELWAQ model proved effective in simulating water quality at Bung Binh Thien Lake, providing valuable data for environmental management and decision-making. This study also serves as a useful reference for further research and water quality management.