inundation modelling as well as on high resolution topographic and land use database.The flow model is based on the shallow-water equations, solved by means of a finite volume scheme on multiblock structured grids. Using highly accurate laser altimetry, the simulations are performed with a typical grid spacing of 2m, which is fine enough to represent the flow at the scale of individual buildings.Consequently, the outcomes of hydraulic modelling constitute suitable inputs for the subsequent exposure analysis, performed at a micro-scale using detailed land use maps and geographic database. Eventually, the procedure incorporates social flood impact analysis and evaluation of direct economic damage to residential buildings.Besides detailing the characteristics and performance of the hydraulic model, the paper describes the flow of data within the overall flood risk analysis procedure and demonstrates its applicability by means of a case study, for which two different flood protection measures were evaluated.

Abstract. Managing flood risk in Europe is a critical issue because climate change is expected to increase flood hazard in many european countries. Beside climate change, land use evolution is also a key factor influencing future flood risk. The core contribution of this paper is a new methodology to model residential land use evolution. Based on two climate scenarios ("dry" and "wet"), the method is applied to study the evolution of flood damage by 2100 along the river Meuse. Nine urbanization scenarios were developed: three of them assume a "current trend" land use evolution, leading to a significant urban sprawl, while six others assume a dense urban development, characterized by a higher density and a higher diversity of urban functions in the urbanized areas. Using damage curves, the damage estimation was performed by combining inundation maps for the present and future 100 yr flood with present and future land use maps and specific prices. According to the dry scenario, the flood discharge is expected not to increase. In this case, land use changes increase flood damages by 1-40 %, to C 334-462 million in 2100. In the wet scenario, the relative increase in flood damage is 540-630 %, corresponding to total damages of C 2.1-2.4 billion. In this extreme scenario, the influence of climate on the overall damage is 3-8 times higher than the effect of land use change. However, for seven municipalities along the river Meuse, these two factors have a comparable influence. Consequently, in the "wet" scenario and at the level of the whole Meuse valley in the Walloon region, careful spatial planning would reduce the increase in flood damage by no more than 11-23 %; but, at the level of several municipalities, more sustainable spatial planning would reduce future flood damage to a much greater degree.

Successfully modelling flows over a spillway and on strongly vertically curved bottoms is a challenge for any depth-integrated model. This type of computation requires the use of axes properly inclined along the mean flow direction in the vertical plane and a modelling of curvature effects. The proposed generalized model performs such computations by means of suitable curvilinear coordinates in the vertical plane, leading to a fully integrated approach. This means that the flows in the upstream reservoir, on the spillway, in the stilling basin and in the downstream river reach are all handled in a single simulation. The velocity profile is generalized in comparison with the uniform one usually assumed in the classical shallow water equations. The pressure distribution is modified as a function of the bottom curvature and is thus not purely hydrostatic. Representative test cases, as well as the application of the extended model to the design of a large hydraulic structure in Belgium, lead to satisfactory validation results RÉSUMÉModéliser avec succès les écoulements au-dessus d'un déversoir et sur des fonds fortement incurvés verticalement est un défi pour n'importe quel modèle intégré en profondeur. Ce type de calcul exige l'utilisation d'axes correctement inclinés le long du sens d'écoulement moyen dans le plan vertical et de modéliser les effets de la courbure. Le modèle généralisé proposé exécute de tels calculs au moyen de coordonnées curvilignes appropriées dans le plan vertical, menant à une approche entièrement intégrée. Ceci signifie que les écoulements dans le réservoir amont, sur le déversoir, dans le bassin d'amortissement et dans tout le fleuve à l'aval sont traités dans une même simulation. Le profil de vitesse est généralisé par comparaison avec le profil uniforme habituellement considéré dans les équations classiques en eau peu profonde. La distribution de pression est modifiée en fonction de la courbure du fond et n'est donc pas purement hydrostatique. Les cas tests représentatifs, aussi bien que l'application du modèle général à la conception d'une grande structure hydraulique en Belgique, donnent des résultats de validation satisfaisants.

ABSTRACT:With the availability of high resolution DEMs, relevant and detailed inundation maps may now be routinely computed provided that suitable flow models are available. The full 2D flow model presented in this paper has been used to compute such maps on 800 km of the main rivers of the Walloon Region in Belgium. The use of grid spacing of 1 m, similar to the DEM resolution, enables the accurate prediction of the pattern of flood depth. This is confirmed by several application examples, which also demonstrate the ability of the model to reproduce depth measurements for a wide range of flood discharges without the need for recalibration of the roughness coefficient. The numerical model has been systematically validated by comparison with observations during recent real flood events. It shows a very good agreement with field data, in particular the free surface elevations and inundation extension.

A practical methodology has been developed for predicting flows generated by dam failures or malfunctions in a complex or a series of dams. A twofold approach is followed. First, the waves induced in the downstream reservoirs are computed, as well as hydrodynamic impacts induced on downstream dams and dikes are estimated. Second, the flood wave propagation and the inundation process are simulated in the downstream valley, accounting for possible dam collapse or breaching in cascade. Two complementary flow models are combined: a two-dimensional fully dynamic model and a simplified lumped model. At each stage, the methodology provides guidelines to select the most appropriate model for efficiently computing the induced flows. Both models handle parametric modeling of gradual dam breaching. The procedure also incorporates prediction of breach formation time and final width, as well as sensitivity analysis to compensate for the high uncertainties remaining in the estimation of breach parameters. The applicability of the modeling procedure is demonstrated for a case study involving a 70-m high-gravity concrete dam located upstream of four other dams.