Groundwater-surface water interactions in a volcanic maar lake (Hule maar, Costa Rica)

These data include stable isotopes of carbon and water, radon-222 in water, hydrochemistry, and weather data. This study was carried out at Lake Hule, a volcanic lake in northern Costa Rica, and aimed to better understand the interactions between groundwater and surface water. Our results showed little difference in evaporation-to-inflow ratios between dry (December-April) and wet (May-November) seasons. Groundwater, precipitation, and runoff contributed ~61.3%, 24.4%, and 14.3% of total inflow to the lake, respectively. We found that carbonate buffering also played a key role in the lake chemistry, with greater carbon dioxide degassing from groundwater sources in the wet season. This study provides insight into groundwater-surface water interactions in Central America's volcanic front.