RECHARGE ESTIMATION AND SITE IDENTIFICATION FOR MANAGED AQUIFER RECHARGE IN SUPHANBURI, THAILAND USING GIS AND MODFLOW

Abstract

This study focuses on groundwater recharge estimation and site identification for Managed Aquifer Recharge (MAR) in Suphanburi, Thailand, an agriculturally intensive region increasingly affected by floods and droughts. An integrated approach combining Geographic Information Systems (GIS), water balance analysis, and groundwater simulation using Visual MODFLOW was applied to assess recharge potential. Key factors, including land use, slope, and hydrogeology, were analyzed to delineate 5 suitable recharge zones. Field data from 13 observation wells collected between 2014 and 2024 were used to calibrate and validate the groundwater model. The model has high accuracy with R² values of 0.983 (Calibration) and 0.992 (Validation), and normalized RMSEs of 5.97% and 5.20%, respectively. The result showed that the highest recharge rates were 343.42 and 320.39 m³/day, observed in urban and industrial zones near the Tha Chin River, with capacities sufficient to support over 1,600 people. This research provides a practical and replicable framework for MAR site selection and implementation, supporting data-driven water management strategies in flood and drought-prone regions.