Variability of chemical parameters of irrigation water in Mendoza’s northern and central oases

Abstract

Sustainable development in Mendoza’s oases should guarantee water availability in both quantity and quality. Urban and industrial expansion and agriculture affect the suitability of water for irrigation. The objective of the work reported in this paper is to assess the temporal and spatial variations of the physico-chemical parameters of irrigation water in the Mendoza and Tunuyán rivers as well as in their respective canals and drains. Two hypotheses are formulated based on the monitoring of electrical conductivity, pH, and of cation and anion content: 1) diminishing water quality from the river’s headwaters to the tail end of the irrigation system; and 2) the impact of population, industrial areas and agriculture on water quality. Sampling sites were selected in the Mendoza and in the Tunuyán river basins (11 and 7 sites, respectively). The variables analyzed were flow, electrical conductivity, pH, SAR, chlorine, sodium and bicarbonate. Variations were observed in pH (7.3 to 7.7), electrical conductivity (0.87 dS.m^-1 to 5.07 dS.m^-1), and SAR (0.6 up to 7.0). Sodium values ranged from 0.65 me.L^-1 (canals) to 29.16 me.L^-1 (drains); chlorine from 0.51 me.L^-1 to 13.9 me.L^-1; and bicarbonate from 0.92 me.L^-1 to 6.26 me.L^-1. A differential degree of contamination as a function of location is observed among the sampling sites. This makes it possible to detect contamination levels, which can be useful for water management authorities.