RESUMENFactores que influyen en las fuentes de abastecimiento de agua potable a la Ciudad de México 410 / Boletín de la Sociedad Geológica Mexicana / 2016 410 IntroducciónEl aumento de la densidad de población y la dinámica de la expansión urbana, con una marcada tendencia al crecimiento de las zonas urbanas y disminución de la población rural, hacen a las megaciudades focos de vulnerabilidad y de alta complejidad en la tarea de prestar los servicios urbanos básicos (Martínez et al., 2011;Kraas, 2008;Mitchell, 2006). El concepto de vulnerabilidad enfocado en los recursos hídricos ha sido aplicado desde diferentes perspectivas. Pinto et al. (2010) analizaron la vulnerabilidad de redes de tuberías de agua para identificar posibles escenarios de falla de la infraestructura; Sena et al. (2012) evaluaron la vulnerabilidad de ríos en la Cuenca del Amazonas ante eventos climáticos extremos, considerando aspectos geo-ecológicos y socio-ambientales; Wilhelmi y Morss (2013) evaluaron la vulnerabilidad ante precipitaciones extraordinarias en Fort Colins, Colorado, considerando los aspectos sociales; Pandey et al. (2010) analizaron la vulnerabilidad a sequías en la cuenca Sonar en India, considerando aspectos como la topografía, uso del suelo, demanda de agua, disponibilidad de agua y registros de precipitación; Hamouda et al. (2009) analizaron la vulnerabilidad en la cuenca del Río Nilo con base en 31 indicadores que consideran aspectos hidro-físi-cos y socio-económicos; Chia-Ling y Chung-Hsu (2010) analizaron la vulnerabilidad en una cuenca de Taiwán considerando factores meteorológicos y geográficos. Sin embargo, definir criterios para cuantificar la vulnerabilidad de las fuentes de abastecimiento de agua potable no es tarea sencilla debido a la falta de consenso en el verdadero significado del término, la complejidad de los sistemas analizados y al hecho de que la vulnerabilidad no es frecuentemente un fenómeno observable (Downing et al., 2001;Luers et al., 2003;Pritchett et al., 2000). La dificultad puede aumentar cuando se evalúa un fenómeno gradual y continuo tal como el impacto del cambio climático (Olmos, 2001) o la degradación de ecosistemas. A pesar de la complejidad, se han propuesto métodos de medición cuantitativos y semi-cuantitativos utilizando, en gran parte de los casos, un conjunto o combinación de indicadores. La utilidad de usar variables (o atributos) en las determinaciones de la vulnerabilidad radica en que simplifican y resumen la información relevante; por un lado, hacen visible o perceptible el fenómeno de interés, por otro cuantifican, miden y comunican información relevante. El desarrollo de variables e indicadores para uso en modelación y evaluación, permite llevar a cabo análisis de vulnerabilidad que integran perspectivas sociales y ambientales (Moss et al., 2002). En el presente trabajo se realiza un diagnóstico de las fuentes actuales de abastecimiento de agua potable a la Ciudad de México y se analizan los factores o atributos que influyen en su vulnerabilidad, considerando los factores amb...

In the context of growing urbanization and climate change, the issue of how to best secure and increase future water supply in developing countries is key. To support informed decision-making in Mexico City, a comprehensive study was conducted to assess the potential effects of climate change and the vulnerability of water sources. The infrastructural, environmental and administrative factors affecting the water available from each source were identified and evaluated, and then combined with the likely impacts in regional water availability estimated using results from two global circulation models and two emission scenarios. The results obtained indicate that the water sources outside Mexico City, such as the Cutzamala and Lerma systems, are the most vulnerable. The current situation is likely to become worse as a result of climate change, as projections suggest a 10–17% reduction in water availability by 2050. When responsible agencies decide the strategies to secure and increase water supply, they will have to consider the prevailing and potential conflicts, the local water demand, the contribution to the city's greenhouse gas emissions and future changes in water availability.

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Significant changes in the isotopic composition of groundwater in the upper catchment of Rio Guanajuato, Mexico, were detected in two independent sets of samples for 3 % of the 1600 high–production wells in the area. Sampling was done in December 1998 (53 samples), and in July – August 2003 (41 samples). Average deuterium concentration did not change between 1998 and 2003 but the average oxygen–18 concentration suggested a generalized dilution from deep water from infiltrated local precipitation. This regional change occurred within 56 months, indicating a highly dynamic hydrogeologic system. Fast replenishment of aquifer storage, or non sustainable over–pumping of old aquifer reserves, are possible explanations.

Background. The concept of "environmental flow" is defined as hydrologic regimes that are required to sustain ecosystem health and functions in rivers. In Mexico, it has become an important topic, not least because a 2012 legal standard (NMX-AA-159-SCFI-2012), establishes procedures for determining instream flow requirements. Goals. The aim of this paper is to propose an acceptable environmental flow requirement for a regulated river segment in the Duero River Basin in, Michoacan, Mexico. Methods. Of the many methods of establishing environmental flows in rivers, this article is concerned with the habitat simulation method. This is based on the IFIM theoretical framework and the PHABSIM mathematical model, by which the WUA-Q curves were obtained for five species of fish. Results. From these curves, we determined that the Goodea atripinnis species has the greater habitat area and reached a maximum of 4338 m 2 /km for a flow of 5 m 3 /s; Alloophorus robustus maintained a constant habitat of 2000 m 2 /km between flow rates of 5 to 15 m 3 /s. With smaller area, Menidia jordani had a maximum habitat of 1323 m 2 /km for 4.5 m 3 /s; and with WUA less than 500 m 2 /km the curves of the species Algansea tincella and Aztecula sallaei were obtained. Conclusions. The average regulation in March and April was 3.61 and 3.44 m 3 /s and with the EFR proposal it was 5.11 and 5.00 m 3 /s for March and April, respectively. In general, the monthly environmental regime is to maintain 80% of the natural flow regime, generating an increase in habitat during the dry season of 24% for A. robustus and 23% for A. sallaei.