Interplay between man and karst hazards: are we victims or triggering factors?

Fragility of karst territories is well known, and repeatedly pointed out by several episodes of dangers threatening human communities and population in many karst areas worldwide. In karst, man plays actually a two-fold role: on one side, he may be victim of hazards occurring in these areas (from sinkholes to flash floods, to pollution events, to groundwater and/or landscape degradation, etc.). On the other hand, many human activities can result in predisposing the environment to hazards, or may represent the triggering factors of dangerous events. Such twofold role is not always easy to be ascertained, and in many cases the two actions are actually intermingled. This often results in confusion and wrong decisions in the management of karst lands, or in land use planning. Some considerations are presented on this issue, based upon experiences in Italy and abroad, and also taking advantage of existing indices for karst environments, such as the Karst Disturbance Index [North et al., J. Environm. Manag., 2009; van Beynen and Townsend, Environ. Manag., 2005] , through which it is possible to evaluate the degree of disturbance induced by human activities on the natural karst environment.