Vulnerabilidad intrínseca a la contaminación del Sistema Acuífero del Altiplano Nariñense aplicando el método GOD

Abstract

The capacity of an aquifer to be contaminated depends on its intrinsic properties, that is the possibility of substances entering on it, due to hydraulic properties of the overlying lithology. The main cause of contamination is given by anthropogenic activities on the surface. The Altiplano Nariñense Aquifer System (SAAN) is influenced by geomorphological features that allow the recharge of the system, from this, it was proposed that the infiltration of polluting loads is correlated with the topography. To estimate vulnerability, geological, hydrogeological information and water points sampled in 2005-2006 were collected, which allowed us to apply the GOD method that involves three parameters related to the type of aquifer, lithology of the unsaturated zone and depth of groundwater. Three of the five vulnerability indices proposed by this method were evident, associated to the classification “very low”, “medium” and “high”, where medium vulnerability predominates with 51.09% of the total area. Because the main use of land in the Altiplano Nariñense (AN) is for agriculture and this activity requires agrochemicals, there is a probability that these are the main contaminants, and it is also evident that a part of the surface water system has a high index of potential alteration of water quality and its interaction with the aquifer system would also contribute to the dispersion of contaminants. The result was compared with the vulnerability map with the land cover map in the AN, which indicates that 88.44% is destinated to agricultural territories.