Modeling Paleorecharge on the Yucatan Peninsula, Mexico

The decline of the Mayan Civilization is thought to be caused by a series of droughts that affected the Yucatan Peninsula during the Terminal Classic Period (TCP) 800-1000 AD. This study modeled groundwater recharge for the TCP and the historical period (1979-2005). Precipitation was reconstructed using proxy data for the Yucatan Peninsula. Drought periods were identified, but the annual time scale for the proxy data precluded their use for recharge modeling. A daily time series representative of the TCP climate was thus generated using a novel backward shift factor approach using output from the Community Climate System Model Version 4 (CCSM4). Shift factors (for precipitation and temperature) were applied to observed precipitation data for recharge modeling. Average annual recharge was 1.7% higher during the TCP, and the majority of this higher recharge occurred during the wet season. These changes indicate the Yucatan Peninsula may have been susceptible to dry season droughts.