Incorporating the effect of DEM resolution and accuracy for improved flood inundation mapping

Abstract

Topography plays a major role in determining the accuracy of flood inundation areas. However, many areas in the United States and around the world do not have access to high quality topographic data in the form of Digital Elevation Models (DEM). For such areas, an improved understanding of the effects of DEM properties such as horizontal resolution and vertical accuracy on flood inundation maps may eventually lead to improved flood inundation modeling and mapping. This study attempts to relate the errors arising from DEM properties such as spatial resolution and vertical accuracy to flood inundation maps, and then use this relationship to create improved flood inundation maps from coarser resolution DEMs with low accuracy. The results from the five stream reaches used in this study show that water surface elevations (WSE) along the stream and the flood inundation area have a linear relationship with both DEM resolution and accuracy. This linear relationship is then used to extrapolate the water surface elevations from coarser resolution DEMs to get water surface elevations corresponding to a finer resolution DEM. Application of this approach show that improved results can be obtained from flood modeling by using coarser and less accurate DEMs, including public domain datasets such as the National Elevation Dataset and Shuttle Radar Topography Mission (SRTM) DEMs. The improvement in the WSE and its application to obtain better flood inundation maps is dependent on the study reach characteristics such as land use, valley shape, reach length and width.Application of the approach presented in this study on more reaches may lead to development of guidelines for flood inundation mapping using coarser resolution and less accurate topographic datasets.Highlights  DEM resolution and vertical accuracy are related to flood inundation maps  DEM properties are linearly related to water surface elevation  DEM properties are linearly related to flood inundation area  Improved flood inundation maps can be obtained from coarser resolution DEM

Effects of variability in probable maximum precipitation patterns on flood losses

“…Altarejos-García et al (2012), Chatterjee et al (2008), Bates (2001, 2002), Kvočka et al (2015), and Neal et al (2012b) discuss the effects of the chosen inundation model, its parametrization, and the role of input data on flood modelling results. Other uncertainties in flood modelling outputs are related to uncertainties in levee heights (Sanyal, 2017) or digital elevation models (Saksena and Merwade, 2015). Beside the uncertainties in flood modelling, observational uncertainties also need to be recognized with recent studies highlighting the importance of observational errors in rainfall and discharge data (McMillan et al, 2012;Coxon et al, 2015).…”

Effect of Digital Elevation Model Mesh Size on Geomorphic Indices: A Case Study of the Ivaí River Watershed - State of Paraná, Brazil

“…The drainage network extracted from the 30 m GDEM and TOPODATA showed a difference in the stream network compared with that extracted from the topographic map. In the floodplain areas, the movement of water is hardly detected using a DEM as it is controlled by very small topographic features, specifically if the mesh size is not fine enough to represent these small features such as narrow channels connecting main rivers and floodplains (Yamazaki et al 2012, Saksena andMerwade 2015). Moreover, the presence of noise and canopy in the DEM highly affect the drainage network in these regions, specifically with small mesh sizes (Lane, James andCrowell 2000, Polidori andSimonetto 2014).…”

Effects of variability in probable maximum precipitation patterns on flood losses

“…30 Altarejos-García et al (2012), Chatterjee et al (2008), Horritt and Bates (2001), Horritt and Bates (2002), Kvočka et al (2015), and Neal et al (2012b) discuss the effects of the chosen inundation model, its parametrization, and the role of input data on flood modelling results. Other uncertainties in flood modelling outputs are related to uncertainties in levee heights (Sanyal, 2017), or in the digital elevation models (Saksena and Merwade, 2015). Beside the uncertainties in flood modelling, observational uncertainties also need to be recognized with recent studies highlighting the importance of observational errors in rainfall and discharge data (McMillan et al, 2012;Coxon et al, 2015).…”