Estimation of the vulnerability to saline intrusion of the coast of Hermosillo aquifer, Sonora, Mexico

Abstract

Vulnerability of aquifers is evaluated with methods such as DRASTIC, AVI, GOD, EPIK, SINSTACS, where pollutants are added near the surface. Intrusion by seawater involves hydrogeologic characteristics completely different from those used in vertical vulnerability assessment. In northwestern Mexico, coastal aquifers are heavily affected by high pumping rates. The coastal aquifer of Hermosillo has been intruded up to 32 km inland, and in some areas the water quality was degraded reaching EC of up to 40 000 J.lS/cm. In this study, the most vulnerable zones through which the seawater penetrates over the last 37 years are identified with the migration and position of the intrusion front. Vulnerability is studied in three risk zones: 1) Zone of high vulnerability due to tectonic subsidence, 2) Zone of medium vulnerability due to permeability of the aquifer, and 3) Zone of low vulnerability due to high gravimetric anomalies.