Climate Change Impacts on Water Scarcity and Hydrological Dynamics in a High-Andean Basin: SWAT Modeling of the Coata River, Peru

Climate change is expected to significantly affect hydrological processes in high-Andean basins, where water availability depends strongly on seasonal precipitation and groundwater recharge. This study evaluates future impacts on runoff, groundwater recharge, renewable water resources, and water stress in the Coata River basin (Lake Titicaca watershed, Peru) using the SWAT model forced with CMIP5 climate projections (MPI-ESM-MR and ACCESS1-0 under RCP 4.5 and RCP 8.5 for the period 2025–2100). Model calibration showed satisfactory performance (R2 = 0.86; NSE > 0.80). Results indicate a pronounced reduction in groundwater recharge, strong variability in runoff, and persistently high water stress across scenarios. Although some projections show increases in runoff, reduced infiltration and subsurface storage limit effective water availability. Renewable water resources exhibit contrasting responses depending on the scenario, with both increases and decreases relative to historical conditions, but with greater variability overall. These findings highlight the high sensitivity of the Coata River basin to climate variability and emphasize the need to incorporate climate projections into water management strategies, including recharge zone protection, improved storage capacity, and more efficient water use.