Qualitative assessment in river and phreatic aquifer water in a rural watershed in the Atlantic Forest biome

Abstract

Watersheds have different water compartments (surface, subsurface, and underground) connected by the soil-water interface. In order to be able to relate these compartments, monitoring data are necessary, such as the case of the Ribeirão Concórdia watershed, in Lontras, Santa Catarina (SC). This study aimed to evaluate the behavior and the correlation between rainfall-runoff and phreatic surface levels with chemical species concentrations in surface and groundwaters in a rural watershed. Data of 3 piezometers installed in the hydrographic basin were used: PZ2127, PZ3, and PZMC. The piezometers are equipped with hydrostatic level sensors. A fluviometric station is located adjacent to PZ2127 (near the catchment outlet). Concentrations of anions and carbon forms were analyzed in water samples (river and piezometers) taken every 2-3 weeks, from January 14, 2012, to December 23, 2016, totaling 103 samples. Correlations between daily data were verified using Pearson’s correlation coefficient (ρ). The river presented a dilution effect, while the adjacent piezometer had the highest average concentrations of chemical species. Precipitation and chemical species concentration showed no seasonal pattern, with events/peaks throughout the year. Higher concentrations of carbon forms were found in the summer, while lower concentrations were observed in the winter. Positive correlations between concentrations of anions and carbon forms in surface and groundwaters were obtained.