Development of a Hydrodynamic Model for Regulating Water Drainage of Reservoir and Water Resources Management, Lamtakong Watershed of Thailand

The goal of this research was to develop a hydrodynamic model (HDD-M) for water resource management in the Lamtakong Watershed (LTKW), as well as to simulate three scenarios: 1) Current land use conditions in 2021, 2) Forecasting predicted land-use changes in 2024, and 3) Water drainage regulation of the Lamtakong Reservoir (LTKR) for water resource management in 2024. The Soil and Water Assessment Tool (SWAT) model and Geographic Information System (GIS) program were used to estimate and simulate the amount of Surface Runoff (S), Sediment Yield (SED), Carbonaceous Biochemical Oxygen Demand concentration (CBOD), and Nitrate concentration (NO3) based on a comparison of simulated and observed data. In scenario 1, the S, SED, CBOD, and NO3 were calculated to be 238.44 million cubic meters (MCM), 840,613.68 tons per year, 2.38 mg/L, and 7.36 mg/L, respectively. In the second scenario, the S decreased to 14.75 MCM, whereas SED, CBOD, and NO3 increased to 56,757.48 tons, 0.56 mg/L, and 0.79 mg/L, respectively, when compared to scenario 1, (Scenario 2). Scenario 3 demonstrated that during the dry season of November to June, the standards of surface water were CBOD and NO3, and that increasing LTKR drainage can help prevent the deterioration of water yields. As a result, the HDD-M, which includes the reservoir's controlling water drainage, may need to be considered to satisfy water resource management goals.