Dams in the Mekong: A comprehensive database, spatiotemporal distribution, and hydropower potentials

Abstract. Dams have proliferated along the Mekong, spurred by energy demands from economic development and capital from private companies. Swift dam evolution has rendered many databases outdated, in which mismatches arise from differing compilation methods. Without a comprehensive database, up-to-date spatial assessment of dam growth is unavailable. Looking at future development, hydropower potential specifically within the Mekong remains to be systematically evaluated. In this paper, we offer (1) an open-access and unified database of 1,055 dams, (2) a spatiotemporal analysis of dams on a sub-basin and country level from the 1980s to the post-2020s, and (3) a grid-based assessment of the theoretical basin-wide hydropower potential, using present-day discharge from the CaMa-Flood model (2011–2015, 0.05 degree), and future discharge from the WaterGAP2 model used for ISIMIP2b (2021–2030, 0.5 degree). The dam count of 1,055 is more than twice the largest existing database, with 608 hydropower dams generating a boom in hydropower capacity from 1,242 MW in the 1980s to 69,199 MW post-2020s. While China had the largest capacity increase from the 2000s to the 2010s (+16,854 MW), Laos has the most planned dams and the highest projected growth post-2020s (+18,223 MW). Based on present-day discharge, we estimate a basin-wide hydropower potential of 1,334,683 MW, where Laos is the highest at 514,887 MW. Based on future discharge modeled with climate change, hydropower potential could grow to over 2,000,000 MW. Laos and China are the highest at around 900,000 MW each, together forming over 80 % of the total potential. Our database facilitates research on dam-induced hydrological and ecological alterations, while spatiotemporal analysis of hydropower capacity could illuminate the complex transboundary electricity trade. Through both spatiotemporal and hydropower potential evaluation, we address the current and future vulnerability of countries to dam construction, highlighting the need for better planning and management in the future hydropower hotspot Laos. The Mekong dam database is publicly available at https://doi.org/10.21979/N9/ACZIJN (Ang et al., 2023).