ABSTRACT
The COP acronym comes from the three initials of the factors used, flow Concentration, Overlying layers and Precipitation. The COP method was developed by the Hydrogeology Group of the University of Malaga and has been tested on two carbonate aquifer pilot sites in southern Spain with different climatological, hydrogeological and geological characteristics (Vías et al., 2003). The COP method assumes that contaminant transport to a groundwater resource depends predominately on the ability of water to move through the unsaturated zone and that the contaminant infiltrates from the surface by means of rainfall. The “O” factor indicates the capability of the unsaturated zone, by means of various processes, to filter out or attenuate contamination. The “C” and “P” factors are used as modifiers that correct the degree of protection provided by the overlying layers (O factor).The “C” factor takes into account the surface conditions that control water flowing towards zones of rapid infiltration and can reduce or even nullify the protection capacity of groundwater described by the “O” factor. The “P” factor considers the characteristics of the transport agent in the unsaturated zone, i.e. precipitation. While the “P” and “O” factors can be used to evaluate the vulnerability of any type of aquifer, the “C” factor is specific to karst aquifers (Vías et al., 2003). The three factors are multiplied to obtain the final vulnerability index and classified into five classes ranging from Very Low to Very High.
