This publication provides guidance to water-sector decision makers and planners on how to deal with the quality dimension of groundwater resources management in the World Bank's client countries. There is growing evidence of increasing pollution threats to groundwater and some well-documented cases of irreversible damage to important aquifers. This guide has been produced in the belief that groundwater pollution hazard assessment must become an essential part of environmental best practice for water supply utilities. The guide is particularly relevant for the World Bank's Latin American and Caribbean Region, where many countries have initiated major changes to modernize their institutional and legal framework for water resources management, but may not yet have considered groundwater at the same level as surface water, because of lack of awareness and knowledge of groundwater issues and policy options.

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The provision of sufficient drinking water for domestic consumption in Mexican cities such as Guadalajara, Monterrey or Mexico City is a great challenge. With an urban population that has grown significantly since the second half of the 20th century, water demands are increasing faster than supply. Urban water consumption is determined by socioeconomic factors such as population, income level, or hydraulic infrastructure, but also by climatic conditions. Access to water resources in Mexican cities is unequal, since those who have more economic resources tend to consume more. Climate is also important in water consumption, since the maximum temperature factor is a demand modulator and its effect is detectable in the warmest periods of the year, prior to the start of the summer rainy season. The above suggests that the formation of Urban Heat Islands (UHIs) could increase the demand and consumption of water. However, in large cities in Mexico, per capita water consumption tends to decrease in recent decades because the supply of water does not increase at the rate at which the number of users grows. In. this way, the main climatic modulator of water consumption is meteorological drought, since its occurrence results in low availability of water and, frequently, in socioeconomic drought. Therefore, better urban water management must include strategies for using climate information, where provision to cities is prioritized. | La provisión de suficiente agua potable para consumo doméstico en urbes mexicanas como Guadalajara, Monterrey o la Ciudad de México es un gran reto. Con una población que ha crecido significativamente desde la segunda mitad del siglo XX, las demandas de agua aumentan más rápido que la oferta. Los consumos urbanos de este recurso están determinados por factores socioeconómicos como la población, el nivel de ingresos, o la infraestructura hidráulica, pero también por condiciones climáticas. El acceso al agua en ciudades de México es desigual, pues tiende a consumir más quien más recursos económicos tiene. El clima también es importante en el consumo de agua, pues el factor temperatura máxima es un modulador de la demanda y su efecto es detectable en los periodos más cálidos del año, previo al inicio de la temporada de lluvias de verano. Lo anterior hace pensar que la formación de islas de calor urbanas (ICU) pudiera incrementar la demanda y los consumos de agua. Sin embargo, en grandes ciudades de México, estos consumos per cápita tienden a disminuir en décadas recientes porque la provisión de este recurso no aumenta al ritmo con que crece el número de usuarios. Así, el principal modulador climático de los consumos de agua es la sequía meteorológica, pues su ocurrencia da como resultado una baja disponibilidad de agua y, con frecuencia, sequía socioeconómica. Por lo tanto, una mejor gestión hídrica urbana debe incluir estrategias de uso de información climática, en donde se priorice la provisión a las ciudades.

En este trabajo se realiza una revisión de distintas metodologías seguidas en estudios de calidad y contaminación de aguas superficiales y subterráneas, comentándose distintos aspectos prácticos y sus aplicaciones. | In this paper we review some methodologies for the quality and pollution of the water (groundwater and surface water). It is studied their practical aspects and applications.

Nitrogen (N) pollution in shallow groundwater within the Jianghan Plain—a depositional basin along the Yangtze River in China—is a serious issue affecting the local water supply. There is little concern regarding temporal variation patterns of groundwater N in regions with intensive groundwater/surface-water interactions thus far. In this study, a 2-year field monitoring program and a set of incubation experiments were jointly applied to characterize the seasonal variation mechanisms of groundwater N. Groundwater monitoring suggested that temporal N variations in monitoring wells of 25 and 10-m depth were correlated with fluctuations in water levels, with lower NH₄-N and higher NO₃⁻-N concentrations corresponding to groundwater discharge during the dry season, and with higher NH₄-N and lower NO₃⁻-N concentrations corresponding to groundwater recharge during the wet season. Batch sediment incubation experiments showed that buried organic carbon in sediments from the field site could not promote NH₄-N release, but exogenous organic carbon and oxidant input could catalyze organic N mineralization, resulting in NH₄-N release. Nevertheless, NO₃⁻-N release was limited in all incubations. Thus, the temporal variation patterns could be divided into (1) groundwater N in type-1 wells (25 and 10 m), controlled by the annual reversal of groundwater flow gradient, which determined whether there was input of exogenous organic carbon or oxidants, ultimately affecting organic N mineralization, denitrification and other transformation processes, and (2) groundwater N in type-2 wells (<4 m depth), which showed no significant seasonal variation, implying the process is mainly controlled by surface inputs in the shallower subsurface.

The suitability of a combined water system (CWS) is assessed for meeting drinking-water demand for the city of Arkhangelsk (northwestern Russian Federation), instead of using the polluted surface water of the Northern Dvina River. An appropriate aquifer system (Permilovo groundwater basin) was found and explored in the 1980s, and there were plans then to operate an abstraction scheme using traditional pumping methods. However, the 1980s planned water system was abandoned due to projected impermissible stream depletion such that complete interception of the cone of depression with the riverbed would cause the riverbed to become dry. The design of a CWS is now offered as an approach to addressing this environmental problem. Several sets of major pumping wells associated with the CWS are located on the banks of Vaymuga River and induce infiltration from the stream. The deficiency of the stream flow in dry seasons is compensated for by pumping from aquifer storage. A numerical model was constructed using MODFLOW-2000. The results of the simulation showed the efficiency of the compensation pumping. The streamflow depletion caused by the CWS is equal to the minimum permissible stream flow and is lower than the depletion projected by the abandoned plan. Application of the CWS in the Permilovo groundwater basin makes it possible to meet water demands during water-limited periods and to avoid environmental problems.

A água é um bem essencial à vida e para muitas atividades econômicas. Contudo, sua degradação ocorre de forma acelerada, tornando-a inutilizável para os múltiplos usos da sociedade. Os municípios fluminenses de São José de Ubá e Itaperuna abrigam a bacia hidrográfica do rio São Domingos (BHRSD) no Rio de Janeiro, que apresenta elevados índices de desflorestamento, presença extensiva de agropecuária, centros urbanos com baixos índices de saneamento básico e intensiva extração de água subterrânea para uso doméstico e irrigação. Diante dessa situação, o presente trabalho tem como objetivo analisar a qualidade da água superficial da BHRSD a partir de dois Índices de Qualidade de Água (IQA): o IQA CETESB e o IQA BASCARÁN. Para tal, amostras de águas superficiais foram obtidas em 19 pontos da bacia nos anos de 2004 e 2005. Os parâmetros avaliados e utilizados para compor os índices foram: oxigênio dissolvido, coliformes termotolerantes, pH, demanda bioquímica de oxigênio, nitrato, fosfato, turbidez, temperatura, sólidos totais e aspecto visual da água. Os resultados da aplicação dos índices foram espacializados para a área da BHRSD. O índice da Cetesb apresentou resultados mais positivos, na maioria das amostras, a água foi classificada como "Boa". Enquanto que, pelo índice de Bascarán, a qualidade da água da BHRSD apresentou pior qualidade, com amostras predominantemente classificadas como "Média" e "Ruim" e, em menor número, como "Muito Ruim". Quando não aplicada a constante K presente no IQA BASCARÁN , os resultados desse índice apresentaram- se similares ao do IQA CETESB. Já quando utilizada esta constante, as classificações foram mais distintas entre os índices. Os resultados gerais mostram que do ano de 2004 para 2005 a qualidade da água piorou. Recomenda-se o IQA BASCARÁN para o monitoramento da qualidade da água superficial nesta bacia por descrever mais severamente a qualidade da água, garantindo, assim, maior segurança hídrica à saúde da população.