Assessment of climate change impact on the inflows to Gatun Lake, Panama

The Panama Canal is a critical waterway for international maritime trade. The canal's operations rely heavily on Gatun Lake, a 425 km² reservoir situated approximately 26 m above sea level, which supplies the water required for its lock system. Each lockage consumes 50 to 120 million gallons (0.19 to 0.45 hm3) of water, with 32 to 36 lockages typically occurring daily. Gatun Lake also provides drinking water to about half of the metropolitan population in Panama. Over the past decade, Gatun Lake's water levels have been significantly impacted by three major droughts, raising concerns about the Panama Canal's reliability for shipping traffic. Modelling inflows to Gatun is essential for assessing the impacts of climate change on its water level as well as developing robust management strategies. To this end, hydrological models of three major representative sub-catchments contributing to Gatun Lake were developed using HEC-HMS and future scenarios were simulated using climate projections from CMIP6. Results show a projected decrease in mean annual flow of 10% to 25% with respect to historical conditions for two out of the three sub-catchments studied.