Groundwater over-exploitation driven ground subsidence in the himalayan piedmont zone: Implication for aquifer health due to urbanization

Abstract

Unsustainable groundwater exploitation often triggers inelastic aquifer compaction, endangering future groundwater potential. The Himalayan piedmont fan regions are undergoing fast urbanization and experiencing rapid groundwater depletion and water table drop. The piedmont fans have laterally varying aquifer geometry with slope-dominated aquifer water flow and experience variable spatiotemporal changes in response to groundwater depletion. We estimated the ground deformation over piedmont fans around Chandigarh (India), a growing urban centre, during 2014–2022 using satellite-based Interferometric Point Target Analysis (IPTA). We used both ascending and descending Differential Interferometric Synthetic Aperture Radar (DInSAR) acquisition modes to derive the vertical ground deformation by combining their line of sight (LOS) velocities. The region is experiencing vertical subsidence up to ∼60 mm/yr with prominent hotspots, where the temporal subsidence is compared with the groundwater cone of depression and urbanization over decades. Comparing the subsidence with the aquifer parameters from the bore wells suggests that the clay confining aquifer level III and semiconfined level II in the distal fan are experiencing the highest subsidence. The stress-strain relationship of these hotspot regions reveals the inelastic compaction of the aquifers producing severe subsidence. The piedmont zones of the Himalayas with identical aquifer geometry and population growth are facing similar challenges, and the combined DInSAR-IPTA and observational groundwater data modeling could provide a robust assessment for effective groundwater-aquifer health monitoring and management.