Impact of hydraulic structures and water use on solids in water in the Andean Argentinian piedmont: case studies of Tunuyán and Mendoza river valleys

Abstract

The province of Mendoza has a tradition of irrigation inherited from the Incas, from pre-Columbian times. It contains 36,000 ha irrigated and distributed in oases located on the banks of snow-glacial water-regime rivers from the Andes Mountains. After several years of monitoring the quality of irrigation water in two of the largest basins (Mendoza and Tunuyán rivers; latitude 32°30’S, 33º50’S and longitude 67°50’W, 69°30’W, respectively), this survey seeks to evaluate the quantitative and qualitative variations of dissolved (TDS) and suspended (TSS) solids in water flows. The study takes place in a context of decreasing water availability over short and long temporal scales (future scenarios of climate variability). Methodologically, the historical records of 12 strategically-selected sampling points (6 in each basin) were studied. The results show that the rivers and irrigation canals exhibit a good physical quality (turbidity and salinity) of the natural water used for irrigation. However, the combination of (i) a possible quantitative decrease in supply, (ii) an inadequate maintenance of the hydraulic structures due to regulation (clear water), and (iii) the negative impact of anthropogenic pollution (occasional industrial, domestic, and agricultural wastes, etc.) requires permanent monitoring in order to encourage effective decisions designed to preserve both the quantity and quality of the water for agriculture.