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

MIRIAN R. CALDERON; CÉSAR A. ALMEIDA; MILAGROS GALLARDO QUIROGA; MARIANA B. JOFRÉ; SILVIA P. GONZÁLEZ ; MARÍA L. MISERENDINO

Congreso; VIII SIMPÓSIO DE ECOLOGIA DE RESERVATÓRIOS; 2021

UNIFAL

The unprecedented population growth, the need for economic development, trends in climate change, and the demand for new ways of energy production have led to an increase in the implementation of water storage structures. San Luis, located in the Dry Chaco Ecoregion of Argentina, is an area that due to its semi-arid nature has seen its socioeconomic growth conditioned to the availability of water, resulting in the development of a water policy focused on the generation of water reservoirs. The aim of this study was to assess the influence of flow regulation on the habitat and water quality characteristics in pre and post dam segments at 13 high-gradient streams. Twenty four physicochemical parameters were analyzed and two water quality indices (ISQA and ICG) were applied. Habitat quality (HMA), sediment size, and discharge were evaluated at each site. Mann Whitney analysis to pre- and post-reservoir comparisons and a Principal Component Analysis (PCA) to explore 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