Flood modeling and groundwater flooding in urbanized reclamation areas: The case of Rome (Italy)

Coastal regions below the sea level, subject to reclamation, are becoming more and more exposed to flooding following increasing urbanization and hydrological changes. In these areas, groundwater and water table dynamics during intense rainfall events can be an important component of flooding and inundation, leading to groundwater flooding. Thus, the commonly employed hydrological models based on only the surface component of flow may result in a poor estimation of the extension and persistence of inundation events. We introduce here a simple and parsimonious approach for handling the groundwater contribution to flooding in such areas, which can be easily implemented and introduced into surface hydraulic models for flood management and the delineation of inundation maps. The approach involves few relevant parameters, requiring a minimum of information regarding the hydrogeological setup. The method is exemplified through the flood analysis of a wide reclamation area located in the southern part of Rome, Italy. The introduction of the groundwater component could explain the large water volumes pumped by the stations, which are much larger than excess rainfall. The application confirmed the validity of the proposed approach, emphasizing the important role played by groundwater to flooding in areas similar to the one considered here.