Quantifying the Impacts of Climate Change and Human Interventions on Flow Alterations in a Tropical River

This study aims to quantify the effects of climate variability, dams, and land use/land cover (LULC) changes on the alterations in the monthly, seasonal, and annual discharge in the Sai Gon Dong Nai (SGDN) River basin, a tropical river system in Vietnam. We employed statistical methods (statistical tests, linear regression, and double mass curves) combined with the Soil and Water Assessment Tool (SWAT) model. We found that (1) climate variability is the primary driver of natural flow, but human activities are essential contributors to statistically significant flow alterations. (2) Dams and reservoirs in the SGDN River basin may have dampened the effects of LULC changes on reducing downstream flood discharge. (3) The Da Nhim and Dai Ninh diversion reservoirs may have had a limited impact on flow alterations in the Dong Nai River. (4) In contrast, the Phuoc Hoa diversion reservoir may have reduced flooding in the Be River but partially increased flooding in the Sai Gon River. (5) Quantitatively, human activities contributed -14.2% to + 22.3% and -55.7% to + 66.5% of the annual and monthly discharge changes in the SGDN River Basin. The findings of this study provide valuable insights for strategic water management in the SGDN River Basin and contribute to efforts to promote sustainable development in river basins within tropical monsoon regions.