Enhancing digital elevation models for hydraulic modelling using flood frequency detection

Georgina Ettritch, Andrew Hardy, Landing Bojang, Donall Cross, Peter Bunting, Paul Brewer

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Medium-resolution DEMs have limited applicability to flood mapping in large river systems within data sparse regions such as Sub-Saharan Africa. We present a novel approach for the enhancement of the SRTM (30 m) Digital Elevation Model (DEM) in The Gambia, West Africa: A time-series analysis of flood frequency and land cover was used to delineate differences in the vertical limits between morphological units within an alluvial floodplain. Combined with supplementary river stage data and vegetation removal techniques, these methods were used to improve the estimation of bare-earth terrain in flood modelling applications for a region with no access to high-resolution alternatives. The results demonstrate an improvement in floodplain topography for the River Gambia. The technique allows the reestablishment of small-scale complex morphology, instrumental in the routing of floodwater within a noise-filled DEM. The technique will be beneficial to flood-risk modelling applications within data sparse regions
Original languageEnglish
Pages (from-to)506-522
Number of pages17
JournalRemote Sensing of Environment
Early online date07 Sept 2018
Publication statusPublished - 30 Nov 2018


  • DEM
  • Digital elevation model
  • Flood modelling
  • Landsat
  • River Gambia
  • SRTM


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