Resumen: El objetivo de este artículo es probar la hipótesis de la curva U invertida de Kuznets en la relación entre el consumo de agua per cápita para uso agrícola y ganadero, que representa en promedio 75% del consumo total, y el PIB per cápita para los municipios en la cuenca Lerma-Chapala. En el contexto de cambio climático, la relación entre consumo de agua y PIB es muy importante, pues la variabilidad en la disponibilidad del agua ha aumentado, forzando a los usuarios y gobiernos a considerar estrategias para su uso eficiente, en donde se incluyan los posibles impactos económicos y ambientales. Al llevar a cabo el análisis a nivel de una cuenca hidrográfica es necesario considerar los efectos espaciales entre municipios vecinos a través de la aplicación de modelos autorregresivos espaciales. Al incluir errores correlacionados espacialmente en los modelos de regresión, no se rechaza la hipótesis de la curva U invertida de Kuznets. Por tanto, cualquier estrategia de mitigación del cambio climático relacionada con el uso eficiente del agua debe ser evaluada en sus costos y beneficios en el PIB municipal en relación con la curva de Kuznets estimada en este artículo. | Abstract: The main objective of this article is to test the Kuznets inverted U-curve hypothesis in the relation between water consumption, for which agriculture and farming represent on average 75% of total consumption, and the GDP in municipalities located in the Lerma-Chapala hydrographic basin. Given the context of climate change, it is essential to understand the relationship between water consumption and GDP: the increased variability in the availability of water has forced governments and users to implement strategies for the efficient use of water resources, and thus they must consider not only likely environmental problems but also economic impact. Using data at the municipal level in a hydrographic basin, we consider the spatial effects among the different municipalities; these effects are modeled using spatial autoregressive models. The Kuznets inverted U-curve hypothesis is not rejected when allowing for spatially correlated errors. Thus, any strategy for mitigating climate change by making an efficient use of water resources must be evaluated in terms of its costs and benefits in the PIB of the municipality in relation to the fitted Kuznets curve presented in this article.

Groundwater use for agricultural purposes has been intensified in the State of Sergipe, mainly in the regions with more serious water shortage from surface sources. However, irrigation is still restricted to small areas like home gardens. In part, this problem is due to lack of studies on characterization of water resources, including availability and quality of groundwaters, detecting the spatial distribution of viable sources of groundwater for different uses. The potential hazards related to soil salinity and sodicity, toxicity of specific ions for crops, and clogging of components of microirrigation systems were evaluated. Physicochemical data of water from 278 deep wells located in Piauí River Basin, in the State of Sergipe, Brazil, were used considering the FAO restriction criteria for irrigation purposes. Maps of spatial distribution of groundwater quality indicators in the watershed were prepared by ordinary kriging procedures. Groundwaters showed good quality for irrigation use, mainly in the center-downstream portion of the river basin. There was a trend in increasing the salt concentration in water from the coast to inland in the Piauí River Basin area. | O uso de água subterrânea para fins agrícolas tem-se intensificado no Estado de Sergipe, sobretudo na região de maior escassez de águas superficiais; no entanto, a irrigação ainda está restrita a pequenas áreas, como hortas familiares, justificado, em parte, pela ausência de estudos de caracterização hídrica, incluindo disponibilidade e qualidade das águas subterrâneas, que permitam o conhecimento da distribuição espacial das fontes de água viáveis para uso. Avaliaram-se os riscos potenciais relativos à salinização e sodificação de solos, à toxicidade de íons específicos às culturas e à obstrução em sistemas de irrigação localizada, a partir de dados secundários de 278 poços localizados na bacia hidrográfica do Rio Piauí, considerando-se os critérios de restrição ao uso da água para irrigação estabelecidos pela FAO. Mapas de risco foram gerados por procedimentos de krigagem ordinária, para as variáveis indicadoras de qualidade da água, que possibilitaram a visualização do comportamento espacial das águas na bacia. Verificou-se que as águas subterrâneas apresentam boas condições para uso na irrigação, principalmente na porção centro-litorânea da bacia, visto que houve tendência de aumento na concentração de sais das águas no sentido centro-cabeceiras.

In spite of several international efforts promoting quality of surface water through low sediment generation, this issue has not been undertaken in Chile. Environmental management can be a complex matter due to a deficiency in information or knowledge about causal relationships. This study shows applicability of spatial analysis techniques and Knowledge-Based Systems for modeling probability of supply of free-sediment waters in different areas of three southern counties in Chile. The method considered selection of variables through experts' opinion and the application of Analytic Hierarchy Process (AHP), where physical and social variables were standardized for the analysis to be carried out. A free-sediment water probability map was produced through fuzzy sets (membership functions) of every spatial unit. The model validation was carried out by turbidity measures in streams. These measures indicated a correlation between low turbidity areas (high quality waters) and forested, low access and good drainage zones. These maps constitute a supporting tool for the sustainable development of fish farming, fly fishing and tourism activities. | A pesar de las numerosas iniciativas internacionales que promueven prácticas para minimizar la producción de sedimentos y cuidar la calidad de las aguas superficiales en el territorio, en Chile este es aún un tema pendiente. El desconocimiento de relaciones causales o carencias de información sistémica y agregada dificulta en muchos casos la adecuada toma de decisiones. Este estudio demuestra la aplicabilidad de técnicas de análisis espacial y modelación basada en el conocimiento disponible de factores del territorio, para estimar la probabilidad de generación de agua libre de sedimentos sobre 2.547,6 km² en cuencas de tres comunas del sur de Chile. El método comprendió la selección de variables mediante consulta a expertos y la utilización del proceso analítico jerárquico. Diferentes atributos fisicosociales fueron categorizados para realizar el análisis. Esta información se integró para cada unidad de área estudiada mediante un modelo que empleó clasificación difusa (funciones de pertenencia), generando un mapa de probabilidad de producción de agua libre de sedimentos. Se comprobó la validez del modelo mediante mediciones directas de turbidez en los cauces. Estos mapas pueden ser de utilidad para planificar el desarrollo sustentable de actividades como acuicultura, pesca deportiva y turismo.