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Paper title Determination of aquifer-system parameters in San Luis Potosí Valley (México) from space using PS-InSAR
Authors
  1. María Navarro-Hernández Universidad de Alicante Speaker
  2. Roberto Tomás Jover Universidad de Alicante
  3. Juan M. Lopez-Sanchez University of Alicante
  4. Abraham Cárdenas-Tristán
  5. Jordi J. Mallorquí
Form of presentation Poster
Topics
  • A7. Hydrology and Water Cycle
    • A7.05 InSAR for the groundwater management
Abstract text Land subsidence is a geological hazard, which can be induced by anthropogenic factors, mainly related with the extraction of fluids. The San Luis Potosí metropolitan area has suffered considerable damage induced by the overexploitation of the aquifer-system over the past decades. The city is placed on a tectonic graben delimited by mountain systems. The basin was filled over the years by pyroclastic material and alluvial and lacustrine sediments, which compose the upper aquifer, and the top layer of the deep aquifer. With a semi-arid climate and no permanent watercourse, the population water supply depends on small surrounding dams and groundwater resources. Owing to these conditions, nowadays 84% of the water demand in the valley is covered by groundwater. Consequently, the aquifer static level depletion has fallen up to 95 m from 1970s. The continuous decline increases the effective stress acting on unconsolidated Quaternary sediments, and therefore, the areas with higher accumulated thickness (up to 600 m in the center of the aquifer) consolidate. In this study the relationship between piezometric level evolution and land subsidence is analyzed. To this aim, we applied Coherent Pixels Technique (CPT), a Persistent Scatterer Interferometry (PSI) technique, using 112 Sentinel-1 acquisitions from October 2014 to November 2019 to estimate the distribution of deformation rates. Then, we compared the PSI time-series with the piezometric level changes using 24 wells records for the period 2007-2017. The results indicate a clear relationship between these two factors. The zones with the greatest drawdowns in the piezometric levels match those areas exhibiting the greatest thickness of deformable materials and maximum subsidence. Therefore, the storage coefficient (S) of the aquifer-system was calculated, using the vertical compaction (∆D) measured by means of PS-InSAR data, for a ∆h piezometric level change. The ratio of the change in displacement to the change in ground water level for the continuous and permanent drawdown represent the inelastic storage coefficient (Skv). Skv values obtained from this analysis show an agreement with previous in situ studies, highlighting the usefulness of PS-InSAR derived data to calculate hydrological parameters in detritical aquifers systems affected by land subsidence owing to groundwater withdrawal.