Directive 2007/60 / EC on the assessment and management of flood risk, incorporated into Italian law by Legislative Decree 23 February 2010 n. 49, sets the objective for the authorities responsible for soil protection to reduce the negative consequences of floods on human health, the territory, property, the environment, cultural heritage and for economic and social activities. Preliminary risk assessment of floods is represented by an assessment of potential risks, mainly on the basis of recorded data, rapid analysis and studies on long-term developments, including, in particular, the possible consequences due to climate change. The present information layer has been developed starting from the PAI and in accordance with the "Operative Addresses" issued by the Ministry for the Environment, Land and Sea Protection, with the contribution of ISPRA, the Superior Institute for Protection and the Environmental Research, of the National Basin Authorities and of the Regional State Technical Table. The following relative definitions apply to this information layer in Article 2 of the Legislative Decree 49/2010: a) flood: temporary flooding, including transport or mobilization of sediments, even at high densities, of areas that are usually not covered with water. This includes floods caused by lakes, rivers, streams, possibly artificial drainage networks, any other surface water body even under temporary, natural or artificial conditions, marine floods in coastal areas and excludes flooding not directly attributable to meteorological events; ) flood hazard: the probability of occurrence of a flood event in a pre-established time interval and in a certain area.c) flood risk: the combination of the probability of occurrence of an alluvial event and potential negative consequences for health human, land, property, environment, cultural heritage and economic and social activities deriving from this event. In this information layer, the areas potentially at risk of floods are represented (as per article 6-paragraph. 5 of Legislative Decree 49/2010) and indicate the potential negative consequences for human health, the environment, cultural heritage and activities economic activities deriving from flooding phenomena as defined by the hazard maps drawn up by the AdB.The risk is expressed as a product of danger and potential damage at a given event: R = = P x Dp; with P (hazard) = probability of occurrence, within a certain area and in a certain time interval, of a natural phenomenon of assigned intensity and Dp (potential damage) = degree of loss predictable due to a natural phenomenon occurred intensity, function of both the value and the vulnerability of the exposed element. The damage analysis was conducted in a simplified way, associating the categories of elements exposed to homogeneous conditions of Potential Damage. This allowed for the individual four classes of potential damage: D4 (Very high potential damage): areas where the loss of human lives can occur, extensive damage to economic, natural historical and cultural assets of major interest, serious ecological-environmental disasters ; D3 (High potential damage): areas with problems for the safety of persons and for the functionality of the economic system, areas crossed by lines of communication and services of significant interest, the areas where important production activities take place; D2 (potential damage medium): areas with limited effects on people and on the socio-economic fabric. Areas crossed by secondary infrastructures and minor productive activities, mainly destined to agricultural activities or public green areas; D1 (moderate or no potential damage): includes areas free of urban settlements or productive where the free flow of floods is possible. In order to realize the risk map, they are the three levels of hazard (P3, P2, P1) and the four levels of potential damage (D4, D3, D2, D1) were crossed, thus identifying four risk levels resulting from R4, R3, R2 and R1: R4 (very high risk ): for which loss of life and serious injury to people, serious damage to buildings, infrastructure and environmental heritage, the destruction of socio-economic activities is possible.R3 (high risk): for which problems are possible for the safety of persons, damage to buildings and infrastructures with consequent unavailability of the same, the interruption of functionality of socio-economic activities and damage related to environmental heritage;R2 (medium risk): for which minor damages to buildings, infrastructures and environmental heritage are possible which do not affect the safety of persons, the viability of buildings and the functionality of economic activities R1 (moderate or nil risk): which the social, economic and environmental damages are negligible or null. The present informative layer has been submitted to a qualitative validation process for what concerns the topological and geometric consistency. The present informative layer has legal validity as it is an integral part of the Flood Risk Management Plan (Annex II - Draft of the Flood Risk Management Plan - UOM Ombrone Northern District, Tuscany Coast, Northern Tuscany), approved by the Tuscany Region Council on 11/16/2015.
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