Visualising DEM-related flood-map uncertainties using a disparity-distance equation algorithm
2016 (English)In: The spatial dimensions of water management: Redistribution of benefits and risks / [ed] A. H. Schumann, G. Blöschl, A. Castellarin, J. Dietrich, S. Grimaldi, U. Haberlandt, A. Montanari, D. Rosbjerg, A. Viglione, and S. Vorogushyn, Göttingen: Copernicus Publications on behalf of International Association of Hydrological Sciences (IAHS) , 2016, 153-159 p.Conference paper (Refereed)
The apparent absoluteness of information presented by crisp-delineated flood boundaries can lead tomisconceptions among planners about the inherent uncertainties associated in generated flood maps. Even mapsbased on hydraulic modelling using the highest-resolution digital elevation models (DEMs), and calibrated withthe most optimal Manning’s roughness (n) coefficients, are susceptible to errors when compared to actual floodboundaries, specifically in flat areas. Therefore, the inaccuracies in inundation extents, brought about by thecharacteristics of the slope perpendicular to the flow direction of the river, have to be accounted for. Instead ofusing the typical Monte Carlo simulation and probabilistic methods for uncertainty quantification, an empiricalbaseddisparity-distance equation that considers the effects of both the DEM resolution and slope was used tocreate prediction-uncertainty zones around the resulting inundation extents of a one-dimensional (1-D) hydraulicmodel. The equation was originally derived for the Eskilstuna River where flood maps, based on DEM dataof different resolutions, were evaluated for the slope-disparity relationship. To assess whether the equation isapplicable to another river with different characteristics, modelled inundation extents from the Testebo Riverwere utilised and tested with the equation. By using the cross-sectional locations, water surface elevations, andDEM, uncertainty zones around the original inundation boundary line can be produced for different confidences.The results show that (1) the proposed method is useful both for estimating and directly visualising modelinaccuracies caused by the combined effects of slope and DEM resolution, and (2) the DEM-related uncertaintiesalone do not account for the total inaccuracy of the derived flood map. Decision-makers can apply it to alreadyexisting flood maps, thereby recapitulating and re-analysing the inundation boundaries and the areas that areuncertain. Hence, more comprehensive flood information can be provided when determining locations whereextra precautions are needed. Yet, when applied, users must also be aware that there are other factors that caninfluence the extent of the delineated flood boundary.
Place, publisher, year, edition, pages
Göttingen: Copernicus Publications on behalf of International Association of Hydrological Sciences (IAHS) , 2016. 153-159 p.
Proceedings of the International Association of Hydrological Sciences (PIAHS), ISSN 2199-8981, 2199-899X ; 373
River floods, Hydraulic modelling, Inundation mapping, Digital elevation models (DEM), Uncertainty
Ocean and River Engineering Oceanography, Hydrology, Water Resources Physical Geography Remote Sensing
IdentifiersURN: urn:nbn:se:hig:diva-21496DOI: 10.5194/piahs-373-153-2016OAI: oai:DiVA.org:hig-21496DiVA: diva2:928034
7th International Water Resources Management Conference of ICWRS, Bochum, 18-20 May 2016