Evaluating the potential of TELEMAC2D for modeling salinity propagation in the Vietnamese Mekong Delta

Abstract

Numerical models are essential tools for providing quantitative information to support decision-making in the risk management of salinity intrusion (SI) in coastal areas. The object of this study is to evaluate the applicability of the open-source TELEMAC2D model in simulating salinity propagation in the Vietnamese Mekong Delta (VMD). The simulated results of discharge and water level at the Can Tho and My Thuan stations are of high reliability, with NSE coefficients ≥ 0.78, r² ≥ 0.85, and PBIAS ranging from -16% to 6.0%. SI modeling at the Cau Quan, Tra Vinh, and Hoa Binh stations also yielded NSE coefficients > 0.5 (except during the calibration period, where NSE values were 0.4 and 0.46 at the Cau Quan and Tra Vinh stations, respectively), r² ≥ 0.71, and PBIAS values ranging from -2.53% to 4.96%. The simulated salinity ring (4 g/l) in 2016 and 2020 showed a relatively small discrepancy of 0.9 to 2.9 km compared to observed data. Furthermore, simulated results indicated that the SI dynamics under different scenarios align well with the impacts of upstream flow and downstream coastal water levels on SI progression in the VMD. These findings demonstrate that the model achieves an acceptable level of reliability and has great potential for simulating flow dynamics and SI in an extensive region with complex hydrodynamic regimes like the VMD.