Assessment of water quality vulnerability of duero river basin (Michoacán, Mexico) by means of sintacs method

The concept of aquifer vulnerability is defined as the probability of groundwater contamination by any substance in concentrations above the values established in the official Mexican Norms for drinking water or the values recommended by the World Health Organization. Although the concept was initially related to qualitative contamination aspects, nowadays it can include quantitative elements, by applying various methods. The main aim of this study was to determine the levels of aquifer vulnerability to groundwater in the Duero river watershed, Michoacán, by using the SINTACS method. The watershed is located northwest of the state of Michoacán, at the Hydrological Region No. 12, Lerma-Santiago, specifically in the Río Lerma-Chapala Hydrologic Area. In the region, volcanic sedimentary environment prevails, highlighting stratovolcano type structures, as well as alluvial and lacustrine deposits. The hydraulic behavior of the basin aquifers varies from free to semi-confined. The economy is based on the production of berries, a cultivation highly water demanding, aspects that promotes groundwater extraction by operating approximately 805 wells, and generating overexploitation in the main valleys. We determined two principal vulnerability levels: (1) low, 80-105 points, covering most of the watershed (50 %) and associated with semi-confined aquifer conditions and related to low hydraulic conductivity clay materials and (2) medium (105-140 points) in 25 % of the surface for aquifers in free hydrogeological condition, associated with alluvial deposits. Very low and high vulnerabilities were detected in few zones. Information focused on this area, helps the establishment of public policies for the protection of groundwater, by zoning potential sites to be contaminated as results of unplanned anthropogenic activities.