Flood damage modelling is becoming an essential component in flood risk management. However damage assessments are affected by large uncertainty, mainly related to the use of depth–damage functions. In some countries, where no site‐specific curves are available, a transfer of damage models developed from other areas is required, adding extra uncertainty in the modelling process. This paper discusses the transferability in space of damage curves from literature, with a focus on ‘function uncertainty’, pointing out, especially for mesoscale ones, the lack of detailed information in terms of flood and/or building characteristics that can allow to identify the conditions of applicability of the models. New site‐specific depth–damage functions are then developed for the residential sector, at meso‐ and microscale, based on damage data from the 2010 flood in Veneto, Italy. The application of the new curves reveals a better performance of the mesoscale model compared with the more detailed microscale one, probably due to the small extent of the inundated area.

Abstract. This paper investigates the effect of systematic mean-field and rangedependent radar rainfall errors on the accuracy of runoff simulation in mountainous basins. Statistical analysis of radar rainfall and runoff simulation error is performed on six flood events for two medium size watersheds in northern Italy, located at 38 and 60 km basin-to-radar distances, respectively. We show significant range-related rainfall biases, which are due to the high elevation radar scans used to minimize the interception of the radar beam with the topography. These biases are corrected by converting radar reflectivity measurements at a given altitude into their equivalent surface values, using real-time identification of the mean vertical reflectivity profile. The mean-field bias is adjusted using a multiplicative factor determined based on real-time radar-rain gauge comparisons. The impact of the above radar rainfall biases, and the improvements obtained from the proposed corrections, on areal-rainfall estimation and runoff simulation are evaluated. It is shown that radar rainfall biases magnify through the rainfall-runoff transformation and preclude the accurate simulation of runoff, particularly for the distant basin. The combined correction procedure results in significant reduction of the hydrologic prediction error, especially at the distant basin.

Uncertainties in topographic data may have a significant influence on morphological and hydraulic predictions. In this work, the effects of topographic data resolution and model resolution (dimension of the cell) on the results of a morphological and sediment transport model are analysed using the morphological bi-dimensional curvilinear model MIKE 21C. The study was carried out on the river Torre, located in north-east Italy. Two sources of topographic data were used to create model bathymetry, one based on high-resolution LiDAR (Light Detection And Ranging) data, and the second on river cross-section data. Digital elevation models were created with these topographic data, in order to test the effect of various spatial resolutions. Numerical simulation was carried out for each digital elevation model with different cell dimensions. The impact of topographic information on hydraulic and morphological model results was evaluated by means of three criteria: a) comparison of hydrodynamic results, b) analysis of morphologic variations along the watercourse, c) position of erosional and depositional zones along the watercourse. This study emphasises the importance of input quality information for reliable results of morphological and sediment transport models. Criteria for selecting the optimal dimensions of the cell model are suggested, based on the quality of available data.

Following severe floods in 2008 and 2010, the Government of Moldova requested assistance to improve flood protection throughout the country. The European Investment Bank has funded a Technical Assistance project to develop a programme of flood risk management measures. The project included the detailed 2D hydraulic modelling of the high-risk rivers (about 3400 km) to produce flood hazard and flood risk maps, the identification of measures to reduce the flood risk, the prioritisation of measures and the development of a phased investment programme and a Short-Term Investment Plan. Flood risk was assessed using 12 flood risk indicators representing social, economic and environmental impacts of flooding. Prioritisation of measures took account of: (i) the urgency of the measure; (ii) the magnitude of the risk that can be reduced with the measure; (iii) the benefit-cost ratio of the measure. The approaches used and in particular the methodologies implemented and the results obtained for flood risk assessment and for prioritisation of measures proved to be valuable tools to reach the objective of the study and, in particular, to facilitate the discussion with the stakeholders and the decision-making process.

Abstract.A Technical Assistance project funded by the European Investment Bank has been undertaken to develop a programme of flood risk management measures for Moldova that will address the main shortcomings in the present flood management system, and provide the basis for long-term improvement. Areas of significant flood risk were identified using national hydraulic and flood risk modelling, and flood hazard and flood risk maps were then prepared for these high risk areas. The flood risk was calculated using 12 indicators representing social, economic and environmental impacts of flooding. Indicator values were combined to provide overall estimates of flood risk. Strategic approaches to flood risk management were identified for each river basin using a multi-criteria analysis. Measures were then identified to achieve the strategic approaches. A programme of measures covering a 20-year period was developed together with a more detailed Short-Term Investment Plan covering the first seven years of the programme. Arrangements are now being made to implement the programme. The technical achievements of the project included national hydrological and hydraulic modelling covering 12,000 km of river, the development of 2-dimensional channel and floodplain hydraulic models from a range of topographic and bathymetric data, and an integrated flood risk assessment that takes account of both economic and non-monetary impacts.