The topographic data source of digital terrain models as a key element in the accuracy of hydraulic flood modelling

Abstract

The effects of the topographic data source and resolution on the hydraulic modelling of floods were analysed. Seven digital terrain models (DTMs) were generated from three different altimetric sources: a global positioning system (GPS) survey and bathymetry; highresolution laser altimetry data LiDAR (light detection and ranging); and vectorial cartography (1:5000). Hydraulic results were obtained, using the HEC-RAS one-dimensional model, for all seven DTMs. The importance of the DTM's accuracy on the hydraulic modelling results was analysed within three different hydraulic contexts: (1) the discharge and water surface elevation results from the hydraulic model; (2)

Modeling and visualizing uncertainties of flood boundary delineation: algorithm for slope and DEM resolution dependencies of 1D hydraulic models

“…Croke et al 2014 who stressed the importance of geomorphological understanding during flood risk management). Casas et al (2006) argued that coarser resolution will have less consequence when discharge increases, i.e., floodplain areas will be more accurately mapped than near river areas. This may be true with respect to difference in total surface area of the true and modeled inundation.…”

“…By comparing these modeled levels with measured levels, several studies have shown that the accuracy of predicting correct levels is surprisingly high, irrespectively of the quality of DEM (e.g. Casas et al 2006;Yacoub and Sanner 2006;Brandt 2009). …”

“…Another study was undertaken by Casas et al (2006). They looked at an area next to the Ter River, Spain, and tested different DEMs ranging from 1 to 4 m in cell size.…”

“…Although modelers have acknowledged the implications of roughness for a long time, it is not until recent years that any efforts have been made to see how much this type of uncertainty affects the results (see e.g. Pappenberger et al 2005;Werner et al 2005;Casas et al 2006;Schumann et al 2007;Wilson and Atkinson 2007;Brandt 2009;Warmink et al 2013;Wu in press). This is probably due to the type of uncertainty which earlier has been considered the main constraint for successful modeling, viz.…”

Effects of Land Use Changes on the Runoff in the Landscape Based on Hydrological Simulation in HEC-HMS and HEC-RAS Using Different Elevation Data

“…The processes of acquiring elevation data for generation of a DTM vary and may be based on methods of geodetic measurement, methods of remote sensing, or may come from a variety of available geodatabases. Casas et al (2006) in their study focused on the comparison of elevation models created using Global Navigation Satellite Systems (GNSS), Airborne Laser Scanning (ALS) system and contour line data of the Fundamental Base of Geographic Data of the Czech Republic (ZABAGED®). Diff erences in the accuracy of DTMs were tackled by many authors (Uhlířová, 2010;Šilhavý and Čada, 2013).…”