Long-term responses of maar lakes water level to climate and groundwater variability in central Mexico

Abstract

Besides water level (WL) variability, several lakes worldwide have shown water level decline trends and total desiccation. In maar lakes, there is paleoenvironmental evidence of water level responses to climate and groundwater inflow changes; however, historical studies are scarce. Understanding the relative contributions of natural variability and anthropogenic impacts to the decline of lakes' water level is fundamental to preserving these ecosystems. In this study, we developed a conceptual baseline of the response of tropical maar lakes to climate and groundwater variability at different time scales in near natural conditions. The four analyzed maar lakes are in a semiarid, endorheic basin in central Mexico and the study time frame (1959 to 1992) includes a historical period before direct human impact. We analyzed the effects of meteorological records, large-scale climate phenomena indices (ENSO, PDO, and AMO), and regional groundwater levels on WL datasets using multiple linear regression models, trend analysis and cross correlations. WL responded to meteorological seasonality and climate variability indices. All lakes lost more water to evaporation than they gained from precipitation, which partially explains long-term WL declines. Regional groundwater levels decreased, suggesting a reduction of groundwater inflow to the lakes, which contributed to WL declines. The latter may reflect a lagged effect of long-term recharge decrease, probably due to long-term climate change in the region since the formation of the lakes evidenced in previous studies. The results add to evidence of water level declines caused by groundwater-mediated natural variability, warning about how this process is being exacerbated by anthropic activities under the context of global change.