The DRASTIC-Sg model: an extension to the DRASTIC approach for mapping groundwater vulnerability in aquifers subject to differential land subsidence, with application to Mexico City

• Published in: Hydrogeology journal Vol. 22; no. 6; pp. 1469 - 1485
• Main Authors: Hernández-Espriú, Antonio, Reyna-Gutiérrez, J. Antonio, Sánchez-León, Emilio, Cabral-Cano, Enrique, Carrera-Hernández, Jaime, Martínez-Santos, Pedro, Macías-Medrano, Sergio, Falorni, Giacomo, Colombo, Davide
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.09.2014; Springer Nature B.V
• Subjects: Aquatic Pollution; Aquifers; basins; cities; Contaminants; deformation; Earth and Environmental Science; Earth Sciences; geographic information systems; Geology; Geophysics/Geodesy; Global positioning systems; GPS; Grounds; Groundwater; Hydrogeology; Hydrology/Water Resources; Infrastructure; Land; Land subsidence; Mathematical models; Metropolitan areas; Mexico; Propagation; Risk; Subsidence; Waste Water Technology; Water Management; Water Pollution Control; Water Quality/Water Pollution; Water supply; Mexico; Mexico City Mexico; Mexico, Distrito Federal, Mexico City; Groundwater vulnerability; DRASTIC-Sg; Mexico; Subsidence; Synthetic aperture radar (SAR)
• DOI: 10.1007/s10040-014-1130-4
• ISSN: 1431-2174

Mexico City relies on groundwater for most of its domestic supply. Over the years, intensive pumping has led to significant drawdowns and, subsequently, to severe land subsidence. Tensile cracks have also developed or reactivated as a result. All such processes cause damage to urban infrastructure, increasing the risk of spills and favoring contaminant propagation into the aquifer. The effects of ground deformation are frequently ignored in groundwater vulnerability studies, but can be relevant in subsiding cities. This report presents an extension to the DRASTIC methodology, named DRASTIC-Sg, which focuses on evaluating groundwater vulnerability in urban aquifers affected by differential subsidence. A subsidence parameter is developed to represent the ground deformation gradient (Sg), and then used to depict areas where damage risk to urban infrastructure is higher due to fracture propagation. Space-geodetic SqueeSAR data and global positioning system (GPS) validation were used to evaluate subsidence rates and gradients, integrating hydrogeological and geomechanical variables into a GIS environment. Results show that classic DRASTIC approaches may underestimate groundwater vulnerability in settings such as the one at hand. Hence, it is concluded that the Sg parameter is a welcome contribution to develop reliable vulnerability assessments in subsiding basins.