Evaluation of aquifer contamination risk in urban expansion areas as a tool for the integrated management of groundwater resources. Case: Coffee Growing Region, Colombia

Abstract

In Colombia, hydric resources research has focused mainly on surface water sources. However, the use and protection of groundwater has become important in regions where the access to surface water is difficult. In the city of Pereira, Colombia, it is estimated that the population growth rate is of 0,47% per year; growing from 457,667 inhabitants in 2011, to 481,080 inhabitants in 2020. Facts like this have generated great interest in the study and protection of groundwater. The objective of this study was to evaluate the risk of groundwater contamination in the aquifer of Pereira within the limits of the Urban Expansion Zone of the municipality of Pereira (Colombian Coffee Growing Region), by determining the intrinsic vulnerability using the modified DRASTIC method, and the identification of anthropic threats in the study area. According with the findings, the moderate vulnerability class is the dominant one, representing the 58,3% of the aquifer's area, followed by high vulnerability class with 33,3% of the total area, and the class of very high vulnerability with 8,3% of the area, associated with a zone with high hydrogeological recharge conditions and shallow phreatic levels. Inadequate disposal of domestic wastewater, the existence of hydrocarbon conduction pipes and agricultural activity were identified as the activities that generate a high threat of contamination. Finally, the evaluation of the risk of contamination of the aquifer in the Urban Expansion Zone through the superposition of maps of intrinsic vulnerability and anthropic threats, allowed to differentiate the zones of the aquifer where groundwater presents a high risk of contamination. The obtained results provide information for knowledge and sustainable management of the aquifer, since it allows the delimitation of the areas where it's necessary to restrict the development of activities that deteriorate the quality of groundwater.