Methodological proposal to assess groundwater contamination danger: study case of Bajo Cauca aquifer (Colombia)

Interaction between vulnerability and contaminating charge was used in order to determine the groundwater contamination danger. The result of danger being adapted to the scale of impact on human or animal health and ecosystems is known as “risk”. Index and overlapping methodologies such as EPNNA, DRASTIC, SINTACS, GOD AVI, and Ekv were used and compared to evaluate vulnerability. Contaminating charge to the subsoil, which is generated from specific human activity, has four characteristics: kind of contaminant, means of disposal, intensity, and duration. Interaction among these characteristics obtains a Contaminating Charge Index. In the Bajo Cauca Antioqueño region, over 150,000 inhabitants require ground water for meeting their basic needs at home, for cattle breeding activities, and for irrigation. For this region, an assessment of the groundwater contamination of the free aquifer, as well as an estimation of its impact and the danger this contamination may pose to ecosystems or communities has been performed. Analysis of the interaction between vulnerability and threat allows for the creation of danger and risk maps.