38-11 Prediction of Karst Aquifer Recharge Through a Hybrid Explainable Artificial Intelligence and Hydrological Modeling Approach

Session: Geoscience and Hydrogeology in the AI Era: From Predictive Models to Real-Time Applications

Presenting Author:

Hakan Basagaoglu

Authors:

Basagaoglu, Hakan¹, Sharma, Chetan², Schmidt, Logan³, Yoosefdoost, Icen⁴, Wootten, Adrienne⁵, Bertetti, Paul F.⁶, Sahinli, Arif⁷, Arshad, Arfan⁸, Samimi, Maryam⁹, Sharp, John M.¹⁰, Yang, Changbing¹¹, Mirchi, Ali¹², Chakraborty, Debaditya¹³

(1) Edwards Aquifer Authority, Edwards Aquifer Authority, San Antonio, TX, USA, (2) School of Civil and Environmental Engineering, and Construction Management, University of Texas at San Antonio, San Antonio, TX, USA, (3) Edwards Aquifer Authority, San Antonio, TX, USA, (4) School of Civil and Environmental Engineering, and Construction Management, University of Texas at San Antonio, San Antonio, TX, USA, (5) South Central Climate Adaptation Science Center, The University of Oklahoma, Norman, OK, USA, (6) Edwards Aquifer Authority, San Antonio, TX, USA, (7) Faculty of Agriculture, Department of Agricultural Economics, Ankara University, Ankara, Turkey, (8) Research Applications Laboratory, NSF National Center for Atmospheric Research, Boulder, CO, USA, (9) Edwards Aquifer Authority, San Antonio, TX, USA, (10) Department of Earth and Planetary Sciences, Jackson School of Geosciences, The University of Texas Austin, Austin, TX, USA, (11) Edwards Aquifer Authority, San Antonio, TX, USA, (12) Department of Biosystems and Agricultural Engineering and Oklahoma Water Resources Center, Oklahoma State University, Stillwater, OK, USA, (13) School of Civil and Environmental Engineering, and Construction Management, University of Texas at San Antonio, San Antonio, TX, USA,

Abstract:

Reliable prediction and long-term projection of aquifer recharge are essential for evaluating the sustainability and climate resilience of groundwater resources. However, recharge estimates are inherently uncertain due to the absence of direct measurements. To address this challenge, we developed a serial hybrid modeling framework in which historical recharge estimate from the U.S. Geological Survey's hydrological model were used to train and evaluate the prediction performance of Artificial Intelligence (AI) models.  The framework was applied to two hydrologically distinct basins in the Edwards Aquifer Region: the Bexar basin and the Nueces basin. Historical climate data were derived from local meteorological stations and remote-sensing products, while statistically downscaled climate data from global climate models with intermediate- and high-emission scenarios informed recharge projections through 2100.  

Among the AI models tested, the Extremely Randomized Trees (ERT) achieved the best prediction accuracy on the test data for both basins.  Notably, ERT and other AI models consistently predicted nonzero recharge during three instances in the test dataset for the Bexar basin when the hydrological model estimated zero recharge. These AI model predictions were corroborated by multiple independent indicators, including precipitation records, groundwater levels from an index well, GRACE-derived groundwater storage anomalies, and recharge estimates from the Hydrological Simulation Program—FORTRAN model, providing compelling evidence of the AI model’s ability to learn intricate hydroclimatic relationships and predict a critical and challenging aquifer recharge.

To enhance interpretability, we coupled the ERT model with the Shapley Additive eXplanation (SHAP) to form a comprehensive XAI model.  The XAI model revealed that previous-month recharge and current-month precipitation emerged as the most influential predictors of aquifer recharge in the Bexar and Nueces basins, respectively, accounting for 32% of the variability in model predictions. XAI-based aquifer recharge projections through 2100 suggest a potential reduction in large recharge events under future climate scenarios. This study underscores the value of XAI as a robust and interpretable tool for assessing long-term aquifer sustainability in the face of a changing climate.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-10638

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