Source vulnerability mapping in carbonate (karst) aquifers by extension of the COP method: application to pilot sites

A step from resource to source vulnerability mapping is presented, based on the European COST Action 620 approach for karst groundwater protection. Guidelines on vulnerability assessment of the horizontal groundwater flow path within the karst saturated zone (K factor) are proposed. By integrating this into the previously existing COP method for intrinsic resource vulnerability mapping, adequate source protection can be assessed. The proposed “Karst saturated zone (K) factor” assessment considers groundwater travel time (t subfactor), connection and contribution to the source (r subfactor) and active conduit or fissured network (n subfactor). The extended COP method was applied in two carbonate aquifers in southern Spain with different geological, hydrogeological and climate settings. The results are coherent with previous research results of the studied areas. Moreover, they are consistent with the occasional groundwater contamination detected in one of the springs. On the other hand, an absence of contamination, despite high risk, justifies the lower degrees of vulnerability assigned to the sources surveyed. The source vulnerability maps obtained can thus be used as a basis for the delineation of protection zones.