Groundwater vulnerability in the Arroyo Feliciano basin. Entre Rios. Argentina

Abstract

The study area includes the basin of the Feliciano stream (Arroyo Feliciano) which increasing water resources are affected by the agriculturization rise and the change of soil usage. The 8.199,4 km² basin is undergoing a sudden change in the soil usage that goes from an extensive cattle production to intensive rice – soybean usage. It has an urban population of approximately 11,600 inhabitants and there are a low number of rural settlers. It is unknown if there is pollution produced by agricultural activity. The objective of this paper is to estimate the pollution vulnerability of the aquifers used for supplying water for human consumption to the towns within the basin; irrigation and watered of animals, fundamentally cattle. There are two internationally standard-considered methods that have been used, known as DRASTIC and GOD, in order to establish the capacity of attenuation of pollutants for elimination, delay and dilution, for agrochemical and fertilizers set in the surface. The outcomes of the application of both methodologies indicate that there is high vulnerability to pollution areas which are in the surroundings of the minor riverbeds and the main course of the Feliciano stream, where the depth to the aquifers is minimal. In the rest of the basin the effect that offers the thickness of the silts and clay of the Hernandarias formation, operates protecting the aquifer.