Presentation Information
[O13-P02]An Integrated Geospatial Modeling Framework for Predicting Groundwater Contamination Risk of Quarried Karst under Post-Mining Reclamation Scenarios
*Kaitlyn Tran1 (1. Cedar Park High School)
Keywords:
groundwater,mining,hydrogeology,GIS,contamination,karst
Up to 25% of the world relies on karst aquifers for freshwater, yet karst remains highly vulnerable to contamination due to its porous, heterogeneous structure. The common practice of limestone quarrying compounds this vulnerability. Despite growing trends in repurposing karstic quarries worldwide, regulations on groundwater quality under post-mining conditions remain scarce. The Lime Creek Quarry in Cedar Park, Texas, situated on the Edwards Aquifer Recharge Zone (EARZ), exemplifies this challenge. Although mining ended in 2023, 173 years of excavation removed protective geology, exposing the groundwater table. The city's proposed urbanization of the 216-acre site introduces contaminated runoff into the Edwards Aquifer, the most vulnerable karst system in the USA. The objective of this study was to develop and apply the first systematic modeling framework for delineating groundwater contamination risk zones in reclaimed, quarried karst. First, the EPIK vulnerability method was optimized by reweighing Epikarst, Protective Cover, Infiltration, and Karst conditions derived from aerial imagery and elevation data. Subsequent hazard modeling involved digitizing proposed development and pollutant loads. Overlaying vulnerability and hazards generated scenario-specific risk models. Results showed that revegetation reduces high-risk area by 39.4% and park development by 58.1% compared to minimal remediation, with highest reductions at open-pit regions. Risk models were validated through sensitivity analysis and hydrochemical testing, with NO3 levels correlating with modeled vulnerability (r = 0.82). This study demonstrates that the GIS-based framework, supported by field validation, provides a transferable, cost-effective approach for predicting groundwater contamination risk, offering a scientific basis for sustainable reclamation in karst regions worldwide.