Abstract
Almost a decade ago, the Mexican government targeted to establish environmental water reserves (EWR)—a volume of water allocated for ecological protection based on the Environmental Flow Mexican Norm (eflows, NMX-AA-159-SCFI-2012, ratified in 2017)—in strategic low-pressured for water use and high conservation importance river basins throughout the country. To date, 12 EWRs have been declared for up to 50 years, which encompass 295 river basins and ~55% of the national mean annual runoff (MAR). In this article, we conducted a quality evaluation of the EWRs established. First, the EWR level was analyzed against the MAR and according to wider hydrological conditions. The EWR fulfillment was evaluated by comparing the volumes enacted against the theoretical (Norm implementation). Our findings revealed that independently of individual and regional water use and conservation merits context, ~75% of the EWRs met theoretical volumes at least at an acceptable level, of which medians ranged from 24% to 73% MAR (natural parametrization and A–D environmental objectives). These outcomes prove the usefulness and consistency of the Mexican strategic hierarchical approach for eflow assessments. We aim for them to be considered as the baseline for future on-site eflow implementation and environmental water policy assessments, to show the nationwide potential benefits for protecting free-flowing rivers and to encourage a regional escalation of the strategy.
Highlights
environmental water reserves (EWR) established per hydrological were in Lerma-Santiago 17%, Río Ameca 55%, Costa de Jalisco 54%, Costa Grande de Guerwere in Lerma-Santiago 17%, Río Ameca 55%, Costa de Jalisco 54%, Costa Grande de rero 43%, Costa Chica de Guerrero 42%, San Fernando-Soto La Marina 29%, Panuco 15%, Guerrero
The Mexican government set the ambitious commitment in public policies of enacting water for ecological protection based on the strategic identification of river basins for feasible environmental water allocation at the country scale
There is an array of eflow assessment outcomes and literature available, from the desktophydrology-based to an expert panel and research-driven methods based on on-site information and detailed models
Summary
The water fluxes throughout the atmosphere, from oceans to continents, have driven physical, ecological, and societal processes; they have sustained life all over the world for millennia. The aquatic ecosystems throughout river basins conduct and store water that has been a source of prosperity in the environment. Despite that the freshwater ecosystems represent ~2% on Earth’s surface, by their location in the landscape they possess around. 10% of all described animals and one-third of known vertebrate species [1,2,3,4,5]. It is widely accepted that the rivers, lakes, lagoons, and other wetlands provide a wide array of ecosystem services that sustain people’s welfare, yet degradation and biodiversity loss on these ecosystems have occurred at alarming rates, far beyond that in comparison with marine
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