The adoption of 2007/60/EC Directive requires European countries to implement flood hazard and flood risk maps by the end of 2013. Flood risk is the product of flood hazard, vulnerability and exposure, all three to be estimated with comparable level of accuracy. The route to flood risk assessment is consequently much more than hydraulic modelling of inundation, that is hazard mapping. While hazard maps have already been implemented in many countries, quantitative damage and risk maps are still at a preliminary level. A parsimonious quasi-2-D hydraulic model is here adopted, having many advantages in terms of easy set-up. It is here evaluated as being accurate in flood depth estimation in urban areas with a high-resolution and up-to-date Digital Surface Model (DSM). The accuracy, estimated by comparison with marble-plate records of a historic flood in the city of Florence, is characterized in the downtown's most flooded area by a bias of a very few centimetres and a determination coefficient of 0.73. The average risk is found to be about 14 € m⁻² yr⁻¹, corresponding to about 8.3% of residents' income. The spatial distribution of estimated risk highlights a complex interaction between the flood pattern and the building characteristics. As a final example application, the estimated risk values have been used to compare different retrofitting measures. Proceeding through the risk estimation steps, a new micro-scale potential damage assessment method is proposed. This is based on the georeferenced census system as the optimal compromise between spatial detail and open availability of socio-economic data. The results of flood risk assessment at the census section scale resolve most of the risk spatial variability, and they can be easily aggregated to whatever upper scale is needed given that they are geographically defined as contiguous polygons. Damage is calculated through stage–damage curves, starting from census data on building type and function, for the main categories in the study area: structures, household contents and commercial contents. This method is tested in the area of the St. Croce district in Florence, one of the most seriously affected in the famous 1966 flood

Flood risk assessment is a crucial step for flood risk management purposes, thus answering the requirements of the European Flood Directive 60/2007/EC (European Commission). In this work, a census data scale, which has been considered as a good compromise between spatial resolution and availability of open socio‐economic data, is adopted for risk analysis. The damage categories included are structures, household contents and the most representative economic activities in the city of Florence (Italy). Moreover, since Florence is an important art city, a preliminary evaluation of risk to cultural heritage is carried out. Data from hydraulic simulations, historical reports of the devastating 1966 flood and the cultural heritage recognition sheets allow estimating and mapping the annual expected number of works of art lost in the absence of risk mitigation strategies.

The estimation of flood losses is crucial for the quantitative estimation of risk and the cost-benefit analysis of risk mitigation and prevention measures. Flood losses are usually estimated by means of vulnerability functions, which are often developed in a synthetic way by experts, since loss datasets collected after events are sparse or lacking and mostly refer to slow riverine inundations. Simple univariable empirical vulnerability functions are recognized as a more valuable tool with respect to synthetic curves developed for different contexts. The aim of this work is to derive empirical vulnerability functions for a flash flood event which occurred in Livorno (Italy) in September 2017, based on the hydrologic-hydraulic reconstruction of the flood and observed losses to residential properties. The hydrologic processes are reproduced with a distributed hydrologic model, and the flood propagation is simulated with a full 2D model. Many open GIS data are used and combined with virtual on-site inspection in the study area to analyze building exposure. Different regression curves are tested to fit the data and obtain damage curves. The results show (i) a poor correlation between relative or absolute losses and flow velocity, (ii) a low correlation between relative losses and water depth, thus confirming the existing literature. More significant correlation is found between absolute losses and water depths. The curves here derived provide a first attempt to develop damage functions for flash flood in Italy, which could be applied in similar urban and morphologic contexts.

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The Pilot Arno Water Accounts (PAWA) project was recently funded under the Call “Preparatory Action on Development of Prevention Activities to Halt Desertification in Europe” of the Directorate- General for the Environment of the European Commission to promote preventive actions to manage water scarcity and drought phenomena and to meet one of the main goals under European environmental legislation: the effective and sustainable management of water resources. The partners involved in the implementation of the PAWA project (ISPRA, Arno River Basin Authority, SEMIDE/EMWIS) will carry out a pilot initiative in the Arno River Basin, an area severely affected by water scarcity and droughts phenomena and characterized by water withdrawals and land use changes. In the area a large experience about water balance application was already performed, for example in the context of the Water Framework Directive Common Implementation Strategy. Moving from this knowledge, the objective of the project is the definition of water accounting processing based on the UN System of Environmental Economic Accounts for Water, with the final goal to optimize a list of effective measures to face water scarcity phenomena. By the end of project (March 2015) the PAWA partnership aims at preparing physical water stock accounts, using the best available data resulting from field measurements or models, on a monthly step for the period 1999–201. The quality of each dataset will be assessed; tables, maps and graphs will be produced as outputs of the projects in cooperation with local stakeholders and players of the water sector. Furthermore, water accounts will be used to assess the potential impact of various measures related to water resource efficient exploitation in the most vulnerable sub-basins; their tolerability will be tested during workshops with stakeholders. Finally, water efficiency targets for potential future integration into Arno River Basin Management Plan will be identified.