Abstract

PARIS, Marta; TUJCHNEIDER, Ofelia; PEREZ, Marcela  and  D'ELIA, Mónica. Supply Well Protection: Groundwater Quality Indicators. Tecnol. cienc. agua [online]. 2014, vol.5, n.4, pp.5-22. ISSN 2007-2422.

An indicator is a quantitative or qualitative attribute used to describe and evaluate a specific aspect of a system. It must be simple, buildable with available data and easily represented. Different organizations and programs have developed a compilation of indicators that provide synthetic information of the state and evolution of water systems. Nevertheless, these indicators may need to be adapted in order to reflect the particularities of each environment. This paper presents the indicators defined to monitor groundwater quality for the aquifer underlying the city of Esperanza (Santa Fe, Argentina), the only source of supply for the region. The disruption of the hydraulic equilibrium of the multilayer aquifer system that is being exploited has produced significant chemical changes in the water supply. The results show that, although the electrical conductivity (EC) values (usually used as a quality indicator) of the water have changed, this parameter is not a sufficient indicative of the deterioration of water quality in the exploited aquifer system. Cluster (hierarchical and K-means) and principal methods have made it possible to verify this process, to determine the affectation level and its temporal occurrence for each exploitation well. Other attributes show evidence of the rise in the overlying salt water and of downward flows from the overlying unconfined aquifer, resulting in values for EC threshold and alert levels, total dissolved solid, chlorides, sulfates, nitrates and calcium.

Keywords : Cluster analysis; groundwater quality indicators; well head protection.