Integrated geospatial modelling and preliminary geophysical appraisal for artificial recharge site selection in the upper tapi basaltic aquifer system, India

Abstract

Selecting suitable sites for artificial recharge in basaltic terrain is difficult because storage and percolation are governed by weathered flow tops, fractures, intertrappean beds, and discontinuous alluvial cover. The Upper Tapi River Basin (UTRB) in western India typifies this hydrogeological complexity and has experienced growing groundwater stress. This study integrates remote sensing, GIS, the analytic hierarchy process (AHP), and electrical resistivity tomography (ERT) to delineate recharge-prone sectors and prioritise locations for field verification. Seven thematic layers (geology, geomorphology, soil, slope, drainage density, lineament density, and land use/land cover) were prepared and weighted to derive an aquifer recharge potential index (ARPI). The basin was classified into four recharge categories: poor (4.5%), moderate (26.0%), good (56.0%), and very good (13.5%). High-ranking sectors occur mainly in the western and north-eastern parts of the basin, whereas the central hilly basaltic tract is comparatively unfavourable. Four ERT profiles were used as site-scale subsurface checks rather than basin-wide validation. Moderate to good classes are hydrogeologically compatible with thicker conductive to moderately resistive intervals interpreted as weathered, fractured, or alluvial storage units, whereas poor classes are dominated by shallow massive basalt with limited storage. Five candidate locations were shortlisted by combining recharge zonation with drainage-lineament intersections. The workflow therefore provides a practical basin-scale screening framework for recharge planning in heterogeneous basalt–alluvium aquifer systems. The ERT-ARPI comparison further shows that favourable profiles have thicker low-resistivity storage intervals (median 21 m) than poor profiles (median 8 m), and higher representative weathered-zone resistivity (44 Ω m versus 16 Ω m), although the two-sided Mann-Whitney U test remains exploratory (U = 4.0, p = 0.333) because only four profiles were compared.