Perception and communication of drought risk for mitigation measures development

A dynamic indicator relating supply and demand, related to some threshold levels that describe the hydrological state of the system, is here defined. Threshold values, considering the probability to assure a given fraction of the demand in a certain time horizon, are identified. Normal, pre-alarm, alarm, and emergency states are individuated and some mitigation measures are related to each state. Moreover, since drought is a slow onset risk, the promotion of perception of natural hazards and the communication of alarms can assume paramount importance in the development of effective mitigation measures. People, in fact, do not react to certain hazards or risks because the inability to perceive the considered "long term" disasters, i.e. that they not necessarily occur within a short time. In other words if the environmental disaster takes place on a long time span, the people predisposition is not to perceive it and then not to react. An adequate assessment of exposure and perception of the population to risk, becomes fundamental, also to reduce economic losses. The procedure for mitigation can be applied to all the water supply systems with the resource coming from water bodies regulated with a reservoir or a system of reservoirs. Once proper values for the three threshold levels are defined and the related demand reduction is accepted by the stakeholders, the proposed mitigation rules are able to reduce the effects of most severe droughts. In the same framework, suitable communication procedures can be activated in order to promote people perception to drought risk.