Machine Learning–Based Characterization of Groundwater Recharge in Semi-Arid Drylands
摘要
This study investigates groundwater recharge dynamics in the semi-arid Karkheh Plain of southwestern Iran using an integrated approach that combines satellite-based water-balance modeling with machine-learning analysis for the period 2001–2024. Monthly recharge was estimated using CHIRPS precipitation, MODIS evapotranspiration and land cover, and GLDAS soil-moisture and runoff datasets. Results show substantial month-to-month fluctuations, while the long-term mean remains close to zero. A notable decline in positive recharge peaks is observed in recent decades. Correlation and feature-importance analyses identify that ΔSoil Moisture as the dominant driver of recharge variability, while precipitation acting as a secondary but significant factor. Among the machine-learning models tested, Linear Regression achieved the highest performance (R² = 0.999), outperforming Random Forest and AdaBoost. K-Means clustering further identified three recharge regimes—wet, transitional, and dry—corresponding to seasonal and interannual hydroclimatic variations. These findings highlight increasing groundwater vulnerability driven by climatic pressures and land-cover changes, emphasizing the need for adaptive land-water management strategies under semi-arid conditions.