Planning flood risk reducing measures based on combined hydraulic and socio-economic impact modelling at a micro-scale

Risk management is currently shifting from the full protection against flooding towards the management of the
consequences of flooding. To reduce these consequences, micro-scale analysis is compelled. In addition to the
hydraulic modelling of the inundation flow, nearby land use and vulnerability of elements-at-risk are taken into
consideration. This new approach requests an interdisciplinary collaboration of scientists from hydraulic and social
science, as is the case for this paper. The research teams have developed a methodology to evaluate socio-economic
consequences of flooding based on the analysis at the micro-scale of the flood characteristics, the exposure and the
vulnerability of elements-at-risk and the adaptive capacity of society. The hydrodynamic simulations are conducted
by means of 2D flow modelling run on a highly accurate Digital Surface Model - DSM with a resolution of 2 by 2
meters. The two-dimensional modelling provides high resolution flood maps detailing the distribution of water depth
and flow velocity field in the floodplains, which constitute key inputs for the subsequent flood risk analysis. The
methodology will be illustrated for a case study along River Ourthe, which is the main tributary of River Meuse in
Belgium, for selecting and designing flood protection measure. The geographic data in this area are available at a
resolution consistent with the conducted micro-scale risk analysis. They include data on social vulnerability coming
from the most recent socio-economic national survey (NIS).