Groundwater quality and irrigation suitability assessment in a semi-arid agricultural aquifer of northern Peru

In semi-arid coastal regions, groundwater mineralization limits water-usage opportunities because of the intersection of natural hydrogeochemical processes with agricultural and urban pressures. The present study analyzed groundwater quality in 25 wells of the Sullana aquifer in northern Peru, within the context of a dry-season campaign. Physicochemical characterization incorporated ionic ratios, the cationic Gibbs relationship, principal component analysis, hierarchical cluster analysis, a weighted arithmetic Water Quality Index, irrigation indicators, and spatial analysis on GIS. Results of our study showed the electric conductivity in the range of 656 - 17290 µS/cm and total chloride amounts of up to 4522.60 mg/L. Comparison data on the electric conductivity showed exceedance for 44% of wells, 40% for total dissolved solids, 88% for chloride levels, and 56% for sulfate levels. The total variance is accounted for by two primary components at 78.46%, where major-ion mineralization is demarcated from Fe–Mn variability. The Water Quality Index labels some 84% of wells either poorly, very poorly, or unsuitable for drinking water due to untreated conditions. Manganese was present in three wells at over 0.40 mg/L, while certain As, Pb, Cd, and Cu findings remain uncertain and need confirmation through calculations based on laboratory reporting parameters, detection parameters, and quantification parameters, Major-ion mineralization and localized manganese accumulation remained as the two main issues regarding the quality of groundwater, causing the necessity for seasonal tracking, hydro-geological monitoring, and more hydrochemical analysis or isotopic tracing for better understanding of salinity origins and leading the way to sustainable extraction of ground waters in the future.