Groundwater depletion in Central Mexico: Use of GRACE and InSAR to support water resources management

• Published in: Water resources research 2016-08, Vol.52 (8), p.5985-6003
• Main Authors: Castellazzi, Pascal, Martel, Richard, Rivera, Alfonso, Huang, Jianliang, Pavlic, Goran, Calderhead, Angus I., Chaussard, Estelle, Garfias, Jaime, Salas, Javier
• Format: Article
• Language: English
• Subjects: Agricultural management; Agronomy; Algorithms; Availability; Budgets; Depletion; Economic activities; Economic conditions; Economic models; Exploitation; Flow system; Fracturing; Geology; GRACE; GRACE (experiment); Ground motion; Groundwater; groundwater deficit; Groundwater depletion; Groundwater flow; Groundwater management; Groundwater quality; Groundwater storage; Hydrogeology; InSAR; land subsidence; Mapping; Mathematical models; Mexico; Moisture; Movement; Reliability; Reliability analysis; Remote sensing; Resolution; Satellites; Series (mathematics); Soil; Soil moisture; Soils; Subsidence; Surface water; Time measurement; wastewater infiltration; Water quality; Water resources; Water resources management; Water storage; Watersheds
• ISSN: 0043-1397; 1944-7973
• DOI: 10.1002/2015WR018211

Groundwater deficits occur in several areas of Central Mexico, where water resource assessment is limited by the availability and reliability of field data. In this context, GRACE and InSAR are used to remotely assess groundwater storage loss in one of Mexico's most important watersheds in terms of size and economic activity: the Lerma‐Santiago‐Pacifico (LSP). In situ data and Land Surface Models are used to subtract soil moisture and surface water storage changes from the total water storage change measured by GRACE satellites. As a result, groundwater mass change time‐series are obtained for a 12 years period. ALOS‐PALSAR images acquired from 2007 to 2011 were processed using the SBAS‐InSAR algorithm to reveal areas subject to ground motion related to groundwater over‐exploitation. In the perspective of providing guidance for groundwater management, GRACE and InSAR observations are compared with official water budgets and field observations. InSAR‐derived subsidence mapping generally agrees well with official water budgets, and shows that deficits occur mainly in cities and irrigated agricultural areas. GRACE does not entirely detect the significant groundwater losses largely reported by official water budgets, literature and InSAR observations. The difference is interpreted as returns of wastewater to the groundwater flow systems, which limits the watershed scale groundwater depletion but suggests major impacts on groundwater quality. This phenomenon is enhanced by ground fracturing as noticed in the field. Studying the fate of the extracted groundwater is essential when comparing GRACE data with higher resolution observations, and particularly in the perspective of further InSAR/GRACE combination in hydrogeology. Key Points: InSAR and GRACE observations are compared with the groundwater management scheme Discordance between GRACE, InSAR, and water budgets suggests important wastewater recharge Cointerpreting GRACE and InSAR brings an unprecedented insight into groundwater sustainability