104 A Showcase of Undergraduate Research in Hydrogeology (Posters)

This session is designed for undergraduates presenting research and senior theses in the field of hydrogeology. Prizes will be awarded for top presentations. Employers and graduate advisers are encouraged to attend.

Monday, 20 October 2025
8:00 AM - 5:30 PM
HBGCC, Hall 1

Freshwater vs. Saltwater: Subsurface Flow in a 85m Deep Sinkhole in Northeast Yucatán, México

Paper number: 104-11
Program: Technical Sessions
Time: 8:00 AM – 8:00 AM

Authors

Abstract

The Yucatán Peninsula (YP) is characterized by a complex karstic landscape that creates a highly permeable environment, making it a groundwater dependent ecosystem. Understanding groundwater flow dynamics is essential for assessing water availability, evaluating anthropogenic impacts, and protecting the region’s unique ecology. This research aimed to investigate groundwater flow direction and velocity within an 85-meter-deep sinkhole situated within the freshwater lens and underlying saltwater layer, using an Acoustic Doppler Current Profiler (ADCP). A secondary objective was to assess freshwater flow direction within the Holbox fracture zone to contribute to previous analyses and enhance our understanding of groundwater behavior near the tourism-intensive Riviera Maya.

To determine flow dynamics, the ADCP was deployed in 2-meter vertical intervals both above and below the halocline, the transitional layer between freshwater and saltwater. The halocline depth was identified using a multiparameter water quality probe. Results from prior fieldwork suggest that groundwater flow is predominantly east near the coast, aligning with regional hydrogeological models.

The Yucatán’s groundwater system is increasingly threatened by over-extraction, nutrient and chemical pollution from agriculture, and contamination associated with rapid urban and tourism development. As these stressors intensify, understanding the spatial variability of groundwater movement becomes increasingly critical. This study contributes valuable in-situ data to regional hydrogeological models, offering insights into subsurface flow dynamics within karstic systems. These findings support the development of sustainable water management strategies necessary to protect the region’s vulnerable freshwater resources and ensure the long-term health of both ecosystems and local communities.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-414152

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