Effects of dams on habitat characteristics and water quality of high-gradient streams in a semiarid region, San Luis, Argentina.

CESAR ALMEIDA; PATRICIA GONZALEZ; GALLARDO MILAGROS; MARÍA LAURA MISERENDINO; MIRIAN CALDERON; MARIANA JOFRE

Alfenas

Congreso; VIII SIMPÓSIO DE ECOLOGIA DE RESERVATÓRIOS ?Visão Múltipla e Integrativa de Conhecimentos?; 2021

UNIFAL-UFSCAR-ABLIMNO

The unprecedented population growth, the need for economic development, trends inclimate change, and the demand for new ways of energy production have led to an increase in theimplementation of water storage structures. San Luis is located in Dry Chaco Ecoregion of Argentinawith a semi-arid climate. Consequently, its socioeconomic growth has always been conditioned tothe availability of water, resulting in the development of a water policy focused on the generation ofwater reservoirs. The aim of this study was to assess the influence of flow regulation on the habitatand water quality characteristics in pre and post dam segments at 13 high-gradient streams. Twentyfour physicochemical parameters were analyzed and two water quality indices (ISQA and ICG) wereapplied. Habitat quality (HMA), sediment size, and discharge were evaluated at each site. MannWhitney analysis to pre- and post-reservoir comparisons and a Principal Component Analysis (PCA)to evaluate spatial variations in sites integrity were applied. Nine downstream sites showed increases in mineral parameters and indicators of organic contamination, such as: conductivity, total solids, turbidity, color, phosphates, ammonia, among others (p 0.05). However, the qualification in terms of possible uses of water downstream the reservoirs decreased at six of the sites, remained constant at another six (classifying as suitable for all uses), and improved at one of the studied sites. HMA was significantly different between pre and post reservoir sites (p