The separate and cumulative effect of climate and land use changes on river discharge and sediment load of the Srepok basin, Vietnam

Understanding the relationship between climate change (CC), land use change (LUC), and water resources is a considerable problem for sustainable water and soil management. Additionally, the CC and LUC effects vary across different regions. Therefore, further investigations at a regional scale are necessary for a better understanding of the future. In this work, the separate and cumulative effects of CC and LUC on river discharge and sediment yield (SSL) were investigated for the Srepok River, an important Mekong River tributary. The investigation utilized the calibrated SWAT (Soil and Water Assessment Tool) model under future CC and LUC scenarios. The future CC scenarios were produced utilizing five General Circulation Models (GCMs) under the SSP2-4.5 emission scenario. Moreover, the future LUC scenarios were generated utilizing the calibrated CLUE-s (Conversion of Land Use and its Effects) model rely on historical LUC trends coupled with future population growth and future rainfall scenarios. Results indicated that CC can lead to reductions in discharge and SSL by 3.2–3.3 % and 1.7–3.0 % in the 2030s and 2055s, and rises in discharge and SSL by 6.9 % and 9.7 % in the 2080s, respectively. Besides that, LUC can lead to rises in discharge and SSL by 2.3–3.4 % and 3.5–4.9 %, respectively. The cumulative effect of CC and LUC will reduce the discharge by 1.4–1.6 % and rise SSL by 0.1–1.6 % in the 2030s and 2055s. Further, the cumulative effect may cause rises in river discharge by 3.4 % and SSL by 7.1 % in the 2080s. The findings achieved from this investigation are expected to assist managers and policymakers in developing efficient and practical sustainable water management strategies in the context of CC and LUC.