Water Stress in Mexico Under two Approaches of Water Scarcity Footprint

The water footprint is the measurement of the total amount of environmental impacts related to the water used in a product, process or service (Kounina et al., 2012). The method to evaluate the impacts associated with the use of water are standardized in ISO 14046: 2014 Environmental management-Water footprint (principles, requirements and guidelines). The evaluation of the impacts is made based on the LCA life cycle analysis technique (NTC-ISO 14040-2007), where scarcity indicators have been included for the evaluation of the potential impacts of freshwater consumption. The integral report of the water footprint is the one that evaluates all impact categories both in the intermediate point (impact) and in the final point (damage).

The non-comprehensive report of the water footprint includes only one category of impact, adding to the report the name of the impact qualifier (eg scarcity water footprint).

These categories provide the impact on the use of water used in equivalent cubic meters of water (m ^ 3eq). This conversion is carried out by means of coefficients called characterization factors, derived from various methods.

A characterization factor emerges from an analytical model, which contains the analysis of a database related to a category indicator (scarcity, availability, eutrophication, ecotoxicity, etc.).

Since the publication of ISO 14046 (2014), some water footprint studies have been carried out using characterization factors for the different categories. Its application has been in processes such as the manufacture of cement, or beer, as well as agricultural products (Farell et al., 2013, Álvarez et al., 2013, Vallejo, 2015). In this way, there are characterization factors to evaluate the water footprint of public use and the ecocosts of the water footprint as a way to report environmental impacts in monetary terms (Embarcadero, 2014, Farell et al., 2013).

Organizations such as UNEP (United Nation Enviroment Program) -SETAC (Society of Environment Toxicology and Chemistry) (2012) and ISO (International Organization for Standardization) (2017), develop indicators by impact categories. One of these impacts is vulnerability to water resources, either in terms of scarcity or water stress (WULCA, 2014, Brown & Matlock, 2011).

This research reviews the criteria and procedures of the AWARE indicators (Boulay et al.,) And WSI (Pfister et al., 2009) for the assessment of water stress under the scarce water footprint category, considering national data from the regions hydrological that make up the Mexican territory on an annual scale.