InSAR Reveals Recovery of Stressed Aquifer Systems in Parts of Delhi, India: Evidence for Improved Groundwater Management

Abstract

While most recent assessments of groundwater resources disclose drastic overexploitation in the Northwestern parts of India, for the first time, we reveal that effective regulatory measures have resulted in substantial recovery of heavily stressed aquifer systems in India's capital (Delhi). We use advanced InSAR techniques to derive high-quality vertical displacement time series for October 2014–October 2023. Our results reveal a halting of subsidence since mid-2016 in the Dwarka area and subsequent rebound of the aquifer system by 5–10 cm at an uplift rate reaching ∼2 cm/year. Even the subsidence zone located north of Gurgaon, which subsided by more than 1 m during the study period, exhibits exponential decay of subsidence. A significant reduction in the magnitude of subsidence in the central (from 15 to 7 cm/year) and southern parts (from 7 to 2 cm/year) is observed during 2019−October 2023 as compared to November 2014−18. In contrast, the subsidence rate in Faridabad, located outside the administrative boundary of Delhi, increased by 2 cm/year from August 2017 onwards. Our analysis suggests a gain in groundwater storage (0.002–0.007 km³/year) and the onset of pore pressure saturation due to groundwater level recovery in the Dwarka area. The decay of subsidence in the subsidence zone near Gurgaon suggests reduced groundwater extraction/enhanced recharge. The recovery of groundwater levels by more than 1.5 m over the entire Delhi is evident from 2018 onwards despite decreasing rainfall trend and is attributed to improved groundwater management.