Flood Risk Management Plan for the Sardinia Hydrographic District Sara Frongia1, Marco Melis2, Giovanni M. Sechi3 & Roberto Silvano4 1Department of Civil and Environmental Engineering and Architecture, University of Cagliari, Cagliari, Italy, e-mail: [email protected] 2Regional Water District Authority, Cagliari, Italy, e-mail: [email protected] 3Department of Civil Engineering, University of Cagliari, Italy, e-mail: [email protected]. 4Regional Water District Authority, Cagliari, Italy, e-mail: [email protected] Abstract: Following the European Council Floods Directive (2007/60/EC) and the Italian National Legislation (DL n. 49/2010), the Sardinian (Italy) Hydrographic District Authority defined the main directives on the assessment and management of flood risk in related basins. This planning phase is subsequent of a detailed flood risk mapping and consequent identification of flood prone areas. Recent historical events highlighted on this necessity as the Sardinia region was affected by important floods, typical of the Mediterranean area. In December 2004 the territory of Eastern Sardinia was the scenario of a massive flood event characterised by 500 mm rainfall in five hours. In October 2008 a storm hit the South-Eastern territory and 350 mm of rain was gauged in less than 3 hours. More recently, in November 2013 the Cleopatra hurricane affected the North East of Sardinia causing huge damage. Following these emergencies and legislation directives, the Sardinian Hydrographic Authority is working on flood risk management plans involving researchers, communities and stakeholders. In this paper we focused on a framework plan to describe the assessment of flood risk management plans and consider some pilot areas to define a decision support tool with priorities in flood mitigation measures. Preliminary results are illustrated for these pilot areas observing different mitigation options (structural and non-structural). Key words: Sardinia Flood Risk Management Plan; Flood Directive 2007/60/EC; JRC Model economic assessment methodology; Costs-Benefits Analysis 1. INTRODUCTION The Sardinian region (Italy) flood protection policy is characterised by two important flood plans: the Hydrogeological Settling Plan (P.A.I., 2008) and the Fluvial-Zones Definition Plan, (P.S.F.F., 2013). Nevertheless, these two plans are not enough in answering to the requirements of points raised in the European Flood Directive 2007/60 and the National Italian Legislation, DL 49/2010. As a matter of fact, the two already existing regional plans identify potential flood damaged areas (defined varying the return-time period) and damaged elements, but they need to be completed defining structural and non-structural actions to be provided in order to mitigate risk in flood prone areas. Moreover, these requirements have been highlighted to political and stakeholders by massive flood disasters caused by recent floods and hurricanes. In December 2004 the Eastern Sardinian territory has been hit by extremely heavy precipitation: the rain gage of Villagrande Strisaili gauged 21.2 mm in 10 minutes and 86.4 mm in 1 hour between the 5:10 P.M. and the 6:10 P.M. (ARPAS, 2004). Four years later, in October 2008 a storm hit the South-Eastern territory: 58 mm of rain in 15 minutes and 350 mm in less than 3 hours were gauged in Capoterra territory. In November 2013 the Cleopatra hurricane ruined a big part of the Sardinia territory: a maximum of 440 mm of rainfall has been gauged in less than 24 hours causing 13 dead and a massive amount of damages, mainly around the Olbia town. The disasters consequently to the above cited storm events are just few examples of recent floods urging the Regional Government to specifically engage the Flood directive 2007/60 to Sardinian region requirements. Flood-Risk management can be viewed as a process that involves three different set of actions, depending on aims and operators involved. The first set of actions is necessary to operate on an existing system achievable with a deep analysis of the actual system peculiarities (e.g. changes in 2 land use, urbanization, climate change, etc.), while the second step starts planning for a new or revised system according with the changed conditions. Finally, the planning process step leads to decisions for the mitigation measures supported by an optimum design (Plate, 2002). All previous aspects are embedded in the Flood Directive approach running scheme. The definition of the concept of risk, as combination of flood hazard and flood consequences, and the way in which it is calculated should ideally run starting from the preliminary flood risk assessment, over the mapping of hazards and risks, up to the setting of objectives and planning solutions. Focusing the attention on the assessment and management of flood risks, the European Flood Directive requires the development of the three important reports: 1) The Preliminary Flood Risk Assessment Plan; 2) The achievement of the Flood Hazard Maps and Flood Risk Maps; 3) The Flood Risk Management Plans (FRMP). In real-cases implementation, different methods will be used depending on the scale and level of detail of the assessments (F.Raymaekers, 2012). The second step is one of the most important aspects of the Flood Directive as maps are instruments not just for defining and communicating flood risks, but, mainly, for regulating territory uses and for rationalising the inevitable limits and failures of controls (Demeritt, 2012). In contrast to engineered defences designed to keep water away, it will be important to understand the potential consequences and help communities to become more resilient and adapt to changing levels of flood risk (Demeritt, 2012). Especially because of the lack of infrastructures completely controlling floods and the need of education on flood risks and related misunderstanding, the third step, the Flood Risk Management Plan, holds a relevant position on the Flood Directive 2007/60/EC. In Sardinia we can consider the first two steps have been mainly settled. Relating to the third step, the project for Sardinian Flood Risk Management Plan is still under development. The Sardinian Government commissioned to Sardinian Hydrographic District Authority and Hydraulic Researchers of the University of Cagliari for the achievement of the Flood Risk Management Plans (FRMP) in order to define a clear framework made up not only by engineering ways to reduce flood risks, but also non-structural alternatives like flood warning, emergency response or land use planning (RAS-UNICA, 2013). 2. FRMP: FRAMEWORK IN SARDINIAN HYDROGRAFIC DISTRICT The development of the Flood Risk Management Plan requires the analysis of the current regulations recognised by the Hydrographic District Authority. The European Flood Directive Italian implementation into the National Legislation, (DL 49/2010), expects the preparation of the FRMP by every Hydrographic District. These Hydrographic Districts were defined in a previous act of Italian Legislation (L.n. 152/2006). The main aim of the FRMP is to improve the knowledge and preparedness on flood events to avoid negative consequences in healthy conditions of human being, territory, environmental, historical and architectural heritages and, at the same time, to enhance business safety and social activities. According with the main features of hydrographic districts, a shortlist of non-structural measures has been defined in terms of prevention, protection and preparation to deal with potential flood events. The FRMP operating and governance tools (e.g.: guides lines, institutional agreements, dissemination knowledge, community involvement, etc) are focused on the flood management also in terms of flood emergency plan. In fact, the article n°67 of the D. Lgs. 152/2006 underlines the fundamental existence of a partnership with the Civil Protection Agency in order to improve the alert flood system. Moreover the D. Lgs. 152/2006 requires a clear assessment of every plan in terms of environmental to prevent possible nature devastation. Furthermore to make consciousness the population about the development of the framework project of the Flood Risk Management Plan, as public dissemination knowledge tool the Provisional Comprehensive Assessment (VGP) has been published. The VGP gives in advance an idea of the general potential framework of the FRMP and reveals its aims to reduce negative consequences of floods using structural and no structural mitigation measures. The Sardinian region Flood Risk Management Plan proposed scheme, (RAS-UNICA, 2013), consists in ten sections starting with the European and national institutional politics framework, in order to stress the main aims into the plan. FRMP defines the potential mitigation measures and reconnaissance actions paying attention of flow rates, evaluated floodplains, stream ways and potential natural expansion flood prone areas, environmental aims pinpointed in D. Lgs. 152/2006, land and water resources management, natural, urban and business development, cost-benefit analysis, coastal and meteorological conditions. All of the specified points would be coupled with a solid support of strategic stations (prevision, monitoring, supervision types). Strategic actions are focused not only in management of hydraulic aspects but also in compelling emergency management aspects following the Alert Operating Instructions for Civil Protection Agency, AOICP (Sardinian Region, 2014). The AOICP considers the update of the actual regional flood plans, dam