Deciphering morphometric and terrain-driven controls on groundwater recharge and agricultural suitability using geospatial and multivariate modeling

This study presents an integrated assessment of basin morphometry, groundwater recharge potential, and agricultural suitability in the Lower Thamirabarani River Basin, Tamil Nadu, using geospatial datasets and statistical analyses. The morphometric results indicate an elongated basin (Rf = 0.268; Re = 0.584) with a moderate drainage density (1.4 km/km 2 ), reflecting a balanced runoff response and a reduced tendency toward flash flooding. High relief (820 m), steep terrain (17.23%), and a high Melton Ruggedness Number (0.0333) signify strong erosional forces in the western highlands. Flow accumulation analysis shows that 18.7% of the basin experiences concentrated runoff, while curvature mapping identifies concave surfaces that enhance infiltration. Land-use and land-cover mapping indicates agricultural predominance (59.9%) and highlights the influence of expanding settlements on hydrological processes. The Recharge Potential Index (RPI) mapping reveals that moderate recharge zones cover 67.6% of the basin, with high recharge areas primarily located in the eastern floodplains. The Agricultural Suitability Index (ASI) indicates that over half of the basin is of low to moderate suitability, and unsuitable areas coincide with rocky, saline, or steep landscapes. A strong positive correlation exists between ASI and RPI ( R = 0.78, p < 0.001), indicating a close relationship between agricultural potential and groundwater recharge conditions. Principal Component Analysis and Hierarchical Cluster Analysis identify relief-related parameters as the major contributors to spatial variability. The novelty of this study lies in the development of an integrated framework that links basin morphometry, recharge potential, and agricultural suitability, supported by multivariate validation. The results support the prioritization of watersheds, erosion control, and sustainable land and water management practices.