Groundwater Dynamics and Aquifer Mechanical Properties over North Indian Region using MT-InSAR technique

Rapid urbanization, fast population growth, agricultural and economic development increase the over-drafting of groundwater resources worldwide, which leads to induced land subsidence results in infrastructure damage and loss of the aquifer's storage capacity (Famiglietti et al., 2015; Galloway and Burbey, 2011). In the North Indian region, the GRACE satellite has observed a total water storage loss of about 19.2 Gt yr^-1 (Rodell et al. 2018). Thus, this research is focused on two study areas, Chandigarh and SAS Nagar regions in North India, to analyze the compaction of aquifer systems and groundwater dynamics. We implement the Multi-Temporal Interferometric Synthetic Aperture Radar (MT-InSAR) technique exploring ascending (175 imageries) and descending (170 imageries) passes of Sentienl-1 SAR sensor data of the European Space Agency (ESA) over the study area from 2016 to 2022. The InSAR processing was done for each data stack using an open-source GMTSAR software following a Small BAseline Subset (SBAS) method to generate line-of-sight (LOS) deformation maps (Berardino et al., 2002; Sandwell et al., 2011). The ascending and descending LOS results were further combined, generating vertical land motion (VLM) following Fuhrmann & Garthwaite (2019) approach. We explored and analyzed 12 groundwater head-level data over the study area and integrated with InSAR-derived VLM in a hydro-geophysical model to examine various mechanical characteristics of the aquifer systems (Ojha et al., 2018). Such properties include elastic and inelastic storage coefficients, the aquifer's capacity loss, permanent and seasonal storage loss, etc. The result exhibits a deformation signal of 18 cm/year in Mohali, 16 cm/year in Kharar, 17 cm/year in Dera Bassi, 12 cm/year in Lalru region of SAS Nagar districts, and  8 cm/year of land subsidence in southeast parts of Chandigarh region. We noticed a GW storage loss capacity of about 1.15% of the total aquifer system during the study periods, which occurs due to the inelastic compaction of the aquifer, and the total volume of GW storage loss is about 3 km³. The InSAR-integrated GW observations will provide precise information on understanding groundwater storage change, a necessary precondition for effective water management strategy over such stressed aquifer systems.

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