Spatialization and assessment of flood hazard using 1D numerical simulation in the plain of Oued Laou (north Morocco)

Abstract

The determination of the hazard extent is an essential preliminary step for all strategies that aim at both controlling and reducing flood risk consequences using appropriate tools. The objective of this work is to introduce a probabilistic and preventive approach that calibrates a one-dimensional hydrodynamic model based on the Saint-Venant equations, after providing a multi-criterion analysis of all the morphological, geological, and climatic information available in the catchment, which intervenes in its hydrological response as well as in flood extent management. The adopted approach is initially based on a better knowledge of the flow process, through defining the factors that are likely to influence its regime (the climate, the geology, the morphology of the terrain...), and then the calibration and validation of a one-dimensional hydrodynamic model that preliminarily requires the use of numerical and spatial data (the discretization of the flow field and the river geometry using the tools associated with GIS and data relating to the water level variation in the channel understudy), in order to produce the lateral expansion map of the overflows. This study has allowed us to conclude that in the study area, the nature of the field largely controls the velocity and flow process. Even the quality of the input data controls the quality of the simulation. Moreover, the 100-year (1320 m3/s) flood shows some black spots at the level of constructions, road, or crop fields.