GIS-Based Identification of Groundwater Recharge Zones under Urban Expansion and Climate Variability: A Study of Ranchi, Jharkhand

Abstract

Rapid urban expansion and increasing climate variability have intensified pressure on groundwater systems in hard rock regions of India. In such environments, groundwater recharge is spatially heterogeneous and highly sensitive to land-use transformation and rainfall characteristics. This study employs a GIS-based multi-criteria decision analysis (MCDA) framework to delineate groundwater recharge potential zones in Ranchi, Jharkhand, integrating hydrogeological parameters, land-use change, and rainfall variability. The Analytical Hierarchy Process (AHP) was used to assign weights to thematic layers including slope, drainage density, soil type, geology, lineament density, rainfall, and land-use/land-cover (LULC). A weighted overlay technique was then applied to generate a composite groundwater recharge potential map.

Results indicate that approximately 43% of the study area falls within high to very high recharge potential zones, while 27% lies within low to very low suitability categories. Multi-temporal land-use analysis reveals significant urban expansion over the past two decades, with built-up area increasing from 16% to 32% of the total area. Overlay analysis demonstrates that several moderate and high recharge zones have been converted into impervious built-up areas, leading to reduced recharge capacity. Rainfall variability further influences recharge efficiency, as high-intensity precipitation events contribute more to surface runoff than infiltration in urbanized sectors.

The findings highlight that recharge suitability is dynamic and strongly governed by the interaction between hydrogeological conditions, urban growth patterns, and climatic variability. The GIS–AHP framework developed in this study provides a spatially explicit decision-support tool for prioritizing artificial recharge interventions and integrating groundwater considerations into urban planning. The approach is transferable to other rapidly urbanizing hard rock cities seeking to enhance groundwater sustainability under conditions of climate uncertainty.