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La Serena, Chile

Ribeiro L.,University of Lisbon | Nascimento J.,University of Lisbon | Buxo A.,University of Lisbon | Rotting T.S.,Northumbria University | And 6 more authors.
Mine Water and the Environment | Year: 2014

Multivariate data analysis techniques were used to identify the interrelationships between the physical-chemical analyses of 22 parameters sampled monthly from 1991 to 2007 at 16 monitoring stations along the Elqui river and its tributaries to characterize the scale of the geogenic and anthropogenic impacts on the river's water quality. Principal component analysis was used to identify the differences and similarities between variables in the watershed. Factorial indices, computed to highlight the sections of the river and tributaries more influenced by hydrothermal, mining or agricultural activities, made it possible to synthesize groups of parameters with similar characteristics into a single value. © 2014 Springer-Verlag Berlin Heidelberg. Source


Ribeiro L.,University of Lisbon | Nascimento J.,University of Lisbon | Buxo A.,University of Lisbon | Rotting T.,Northumbria University | And 5 more authors.
Hydrological Sciences Journal | Year: 2015

Today, more than ever, there is a need to implement robust statistical methods to ensure the proper evaluation of water resources data to support decision makers in water resources planning and management. Graphing or mapping data for visualization is the easiest way to communicate trends, especially to a non-technical audience. This paper describes the use of an approach that combines the Mann-Kendall test, Sen slope test and principal component analysis to detect and map the monthly trends of piezometric time series and their magnitude in the period 1979–2008. The data were obtained in 23 shallow wells in the alluvial aquifers of the Elqui River basin in central Chile, an area characterized by scarce water resources and intense agricultural and mining activities. The results show significant downward trends at the majority of the wells. Because groundwater in these shallow wells is highly dependent on the water in the river and its tributaries, the reasons for these downward trends are mainly related to a decrease of streamflow observed in the Elqui River. The streamflow is derived from mountain snowmelt rather than from rainfall, which showed no flow trend during the same period. © 2015 IAHS. Source

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