Prioritization of areas for groundwater monitoring using analytic hierarchy process method in Geographic Information Systems: a case of Mexico

In developing countries, the increase in anthropogenic activities has aggravated the possibilities of groundwater resources pollution, which threatens water sustainability. It is, therefore, necessary to have monitoring networks that provide information that could influence decision-making both on the current and the future situation. The objective of this study was to identify priority zones where monitoring points are required for the optimization of the groundwater quality network in the Toluca Valley aquifer (Mexico), both under current (2020) and future conditions (2030). The analytical hierarchical process method was used in a Geographic Information Systems environment. The density of wells, hydraulic gradient, groundwater pollution hazard, water bodies as well as mountain zones were the analyzed criteria, as advised by expert opinion. The results are prioritization maps for every scenario. The low and moderate priority zones show the highest extension percentage in the current scenario but tend to decrease in future ones. The high-priority zones in the metropolitan area of the Toluca Valley show a 5% increase in the period and stand out for both scenarios. Finally, overlapping the current quality network with the high-priority zones for 2020 and 2030 enabled for concluding that 40.5% of wells in the existing network are essential for the current and future monitoring. The adaptation of this methodology, considering future scenarios of the conditions of the aquifer, will enable to have a monitoring network that is adaptable to these conditions over time, which in turn will facilitate the obtaining of timely data and information.