Flood damage to road networks primarily manifests as a loss of transportation functionality. Current analyses of road network functionality loss during floods are based on specific flood scenarios. This study analyses flood risk to road networks by assessing the probability of stability loss for various vehicle types (SUVs/emergency vehicles, and cars). Eventually, a flood risk map of the road network is generated. The flood risk of each road is computed as reduced accessibility, measured in this paper via isochrones. Bristol (UK) is used as the case study area, with all hospitals as starting points to study the coverage area of emergency vehicles within a given time frame. The results indicate that road network functionality for SUVs/emergency vehicles has a lower flood risk than that for cars. Additionally, the city centre of Bristol exhibits a higher flood risk, hindering emergency medical vehicles from reaching high-risk flood areas. The findings of this research offer strategies to mitigate the impact of floods on road networks and prepare emergency medical services before flood disasters occur.

Flood hazards can affect road networks by closing roads, extending travel distances and lengthening travel times. This paper innovatively integrates flood hazard, road network topology and vehicle vulnerability via a severity factor to assess the accessibility of exposed links and the performance of the whole network. The overall network functionality loss under different flood return periods is assessed by evaluating the functionality of each network link for cars and SUVs. The most vulnerable links are identified and used to assess the performance of the entire network using topology-based metrics such as average shortest paths and isochrones. The case study of Bristol (UK) is investigated. It is demonstrated that network status is a function of vehicle typology, with SUVs exhibiting naturally stronger resistance to flood than cars. This finding can support preparedness strategies of road networks in the face of future flood events.

This chapter provides an overview of global and low-cost topographic data to support flood studies, with a focus on usefulness of shuttle radar topography mission (SRTM) topography in supporting two-dimensional hydraulic modeling of floods. In particular, flood propagation and inundation modeling of a 10-km reach of the River Dee (United Kingdom) was performed by using LISFLOOD-FP to simulate the December 2006 flood event. Flood extent maps from satellite imagery (ERS-2 Synthetic Aperture Radar SAR) and hydrometric information (downstream water levels) were used as evaluation data. Uncertainty analysis was carried out within the generalized likelihood uncertainty estimation framework using the roughness coefficients and downstream water surface slope as free parameters. The results of this study showed: (1) the potentials and limitations of SRTM topographic data in flood inundation modeling; (2) the value of downstream water levels in constraining uncertainty in hydraulic model of floods; and (3) the impact of setting a water surface slope as downstream boundary on the results of the hydraulic model (e.g., predictions of water stages and flood extent).