Groundwater Volume Change in an Aquifer in Southern Mexico as a Monitoring Variable for Adequate Water Management

ABSTRACT A hydrological model for the water management of an aquifer implies many parameters. Furthermore, the adequate water management of a poorly monitored unconfined aquifer of irregular geometry represents a challenge. This paper proposes a new methodology to assess groundwater storage change over a period of 22 years in such an unconfined aquifer located in Southern Mexico as a monitoring variable for an adequate water management. This change in storage is determined by two temporal measurements of the vertical component of gravitational acceleration in the alluvial aquifer of the Valle de Etla, Oaxaca, considering fluctuations in the water table through the inverse modelling of gravimetric differences, based on the Parker–Oldenburg algorithm. One of the two resulting cones of depression contributes to 13 × 10 6 m 3 of urban water of a total estimated 140 × 10 6 m 3 groundwater loss for the period. The proposed methodology contributes to the development of an innovative strategy aimed at enhancing water management, as it employs as input gravimetric data to estimate the spatio‐temporal groundwater storage change. This methodology offers the advantage of not requiring additional monitoring, in contrast to that needed to obtain other hydrogeological variables, commonly employed for adequate monitoring. Furthermore, the gravimetric modelling for the estimation of the groundwater storage change based on the Parker–Oldenburg algorithm enhances the mapping of the water table by assuming an irregular geometry of the aquifer, allowing for a better understanding of how a peri‐urban area causes changes in aquifer storage.