Shallow geoelectrical characterization of a small portion of the Basin of Mexico aquifer: Towards a better resource management

Shortage in supply of fresh water in megacities is becoming increasingly common. Mexico City is part of this problem because dramatic reductions in groundwater levels have been observed in recent years along with associated problems such as subsidence and poor water quality, endangering access to this resource. The Ciudad Universitaria campus is located in the southern part of this mega city and has over 150,000 users, whose clean water demand is met from three abstraction wells supplying almost three million cubic meters per year. However, the configuration of this portion of the Mexico Basin aquifer is not well known and has shown a strong depletion in the water table. Thus, an integrated study was conducted with the aim to characterize this portion of the aquifer to provide information that allows carrying out a better assessment of its current situation and improving its management. Despite the difficulty to conduct a direct characterization of the hydrogeological units outcropping in the area since almost all the campus is covered with infrastructure (i.e. academic facilities, roads, gardens), a geological reconnaissance was carried out in the vicinity of exploitation wells and a geophysical characterization was performed using time-domain electromagnetics. Additionally, a pumping test was conducted in the main exploitation well in order to estimate hydraulic properties of the aquifer. Thus, the integration of these techniques allows inferring some important issues regarding the aquifer and its exploitation in this area.