Surface water assessment availability and potential impacts on Mexico’s 757 hydrographic basins for future hydroelectric development

This study evaluates Mexico’s surface water availability across 757 hydrographic basins, organized into 37 hydrological regions, projecting scenarios for 2034. Using NOM-011-CONAGUA-2015 methodology, availability was determined by subtracting downstream commitments from runoff volume, analyzing historical climate (1976-2018) and water use trends. Significant regional disparities exist. Northern basins, like those in HR 8 (Sonora Norte) and 24 (Río Bravo Conchos), face severe water stress, with availability as low as 050 Hm3/year. Southern regions, such as HR 30 (Grijalva-Usumacinta), have higher availability, exceeding 10 000 Hm3 year–1. Projected scenarios for 2034, using Turc’s formula and the runoff coefficient (Rc), indicate 154 (Turc) and 103 (Rc) basins will face water scarcity. Northwest basins, including HR 9 (Sonora South) and 25 (San Fernando Soto la Marina), are projected to have availability below 100 Hm3 year–1, exacerbating stress. South-central basins, like HR 18 (Balsas) and HR 30 are expected to maintain high availability, exceeding 500 Hm3 year–1. The study also identified basins suitable for hydroelectric development, focusing on flows above 2 m3 s–1 and slopes over 2%. However, ecological and legal constraints, like protected areas and environmental flow requirements, limit development, especially in HR 30. These findings underscore the need for integrated water management to address regional disparities, promote sustainability, and mitigate the impacts of climate variability on Mexico’s water resources.