Aaron Coutino | Applied Math, University of Waterloo
Measuring and Modeling the Hydrogeology of the Yucatan Peninsula
The Yucatan peninsula is composed of Miocene to Late Pleistocene biogenic limestone with both a surface portion and a submerged shelf. The surface portion encompasses three Mexican states and has a total area of 165,000 km squared. As a result of the karst platform which makes up the geology of the low-lying regions of the peninsula, the subsurface is extremely porous and results in no naturally flowing rivers. Freshwater, in the form of rainfall, percolates directly into the aquifer or flows into fissures and sinkholes which occur commonly throughout the landscape. The extreme porosity of the subsurface further results in seawater infiltrating from the coasts and flowing under a freshwater lens. The aquifer located within the Yucatan peninsula is extremely important from both an economic and ecological standpoint, for both modern and historical societies like the Maya. We have conducted multiple measurement campaigns within the cave networks. The resulting data has been analyzed with time series methods such as wavelets, wavelet coherence and Empirical Orthogonal Functions. The results suggest that mixing of the stratified fluid in the cave networks is profoundly influenced by large rain events, such as the passage of hurricanes. Since parts of the cave network are open, we have contrasted the behaviour of open and cave portions, finding differences in the timing of response to rain events. The results of the measurement campaigns will be synthesized to a model of long term climate variability, with possible implications for the decline of late period Mayan cities.