Effects of digital terrain model uncertainties on high‐resolution urban flood damage assessment

Abstract

This work investigates the impact of high‐resolution digital terrain model (DTM) uncertainties on the estimation of urban flood losses. Starting from a Light Detection And Ranging (LiDAR)‐derived DTM of an urban area, four digital terrain representations (raw data, building footprints filled, buildings as waterproof blocks, and different elevation data merged) are used to generate a computational mesh to run a 2D flood model for three inundation scenarios, differing in flood volumes. The most detailed DTM is obtained by merging the DTM with elevation points based on a two‐step optimal interpolation algorithm. A flood damage model based on stage‐damage curves is used to estimate monetary losses to structures at the building scale. Flood maps and flood losses are then compared for each terrain representation. The application of the method to an Italian urban district shows that (a) a significant mismatch between manually surveyed elevation points and DTM can be observed, (b) different sources of elevation data can be merged to obtain an optimal representation of the terrain, (c) in dense urban settlements, important differences in flood extent and losses (up to 180%) occur depending on terrain representation. Considerations on time effort required by the increasing detail of the DTM and on the transferability of the results are presented.

DEM Generation from Fixed-Wing UAV Imaging and LiDAR-Derived Ground Control Points for Flood Estimations

“…Highly detailed terrain modelling is usually produced from data obtained by active sensors such as airborne light detection and ranging (LiDAR) [6,7]. The bare ground representation in the form of DEM from these sources is the basis of urban [8,9,10] and peri-urban local flood studies [11]. LiDAR technology have as main advantages of its laser energy penetration to the ground, for instance, through canopies [7]; however, the cost and complexity of the data acquisition involved implies that such airborne data is not always easy to update, or sometimes is only partially available [5].…”

A Framework Proposal for Regional-Scale Flood-Risk Assessment of Cultural Heritage Sites and Application to the Castile and León Region (Central Spain)

“…In this sense, as indicated by Vaze et al [32], the use of LiDAR data has significantly improved the terrain representation in the DTMs. However, the urban areas (the majority in the location of cultural heritage sites) remain the most problematic and have the highest uncertainty, both in the correct representation of urban areas (e.g., References [33][34][35]) and in the results of the hydrodynamic models used to estimate flood hazard (e.g., References [31,36]).…”

The Value of Urban Flood Modeling

“…UFMs can play a key role in flood risk assessment, facilitating the geospatial analysis of flood hazard , the probability that a flood of a given severity will occur at a site, with severity typically measured by hydraulic parameters such as flood depth or velocity (Arrighi & Campo, 2019; Crichton, 1999). Once flood hazard is delineated, UFM results can be utilized to evaluate populations and properties that would potentially be exposed to flooding, as well as to evaluate resulting damages and financial losses (Hammond et al., 2015; Tsakiris, 2014).…”