Assessing the efficiency of mitigation measures to reduce groundwater depletion and related land subsidence in Querétaro (Central Mexico) from decadal InSAR observations

Abstract

Groundwater overexploitation occurs throughout Central Mexico and is a major threat to the sustainable development of the region. The two most direct impacts are on groundwater/surface water interactions and uneven land subsidence causing ground fracturing. The latter implies frequent and costly repairs to linear urban infrastructure such as roads or water/gas distribution conduits. In 2011, the state of Querétaro drastically changed the water management scheme to solve the groundwater depletion and ground fracturing issues in the Querétaro Valley. Groundwater extraction was decreased by half and the missing portion was replaced by water imports transported through a major 123 km-long aqueduct infrastructure. In this paper, we evaluate if this change in the water sourcing strategy has helped reducing groundwater overexploitation and the related ground fissuring. We present four consecutive radar interferometry-derived ground deformation time-series covering ∼75% of the period 2004–2020. We observed that maximum ground deformation has drastically decreased by a factor of ∼5 after 2011, from −25 to −50 mm/yr to ∼−10 mm/yr, suggesting the effectiveness of the drastic water management change. However, while groundwater static pressure has recovered in the range [4, 10] m in the six years following the change, extraction has been constantly increasing. Interferometric observations based on Radarsat-2 and Sentinel-1 data, in 2013–2014 and 2017–2020 respectively, detect increasing subsidence rates up to ∼−15 mm/yr. This suggests that the water management change only reduced the problem, and that a longer-term strategy will have to be implemented to fulfill the ever-increasing water demand in the region.