A study on DEM-derived primary topographic attributes for hydrologic applications: Sensitivity to elevation data resolution |
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| Authors: | Simon Wu Jonathan Li GH Huang |
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| Institution: | aEnvironmental Systems Engineering, University of Regina, Box 413, 4246 Albert Street, Regina, Saskatchewan, Canada S4S 3R9;bDepartment of Geography, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1;cDepartment of Civil & Environmental Engineering, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1 |
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| Abstract: | Primary topographic attributes play a critical role in determining watershed hydrologic characteristics for water resources modeling with raster-based digital elevation models (DEM). The effects of DEM resolution on a set of important topographic derivatives are examined in this study, including slope, upslope contributing area, flow length and watershed area. The focus of the study is on how sensitive each of the attributes is to the resolution uncertainty by considering the effects of overall terrain gradient and bias from resampling. Two case study watersheds of different gradient patterns are used with their 10 m USGS DEMs. A series of DEMs up to 200 m grid size are produced from the base DEMs using three commonly used resampling methods. All the terrain variables tested vary with the grid size change. It is found that slope angles decrease and contributing area values increase constantly as DEMs are aggregated progressively to coarser resolutions. No systematic trend is observed for corresponding changes of flow path and watershed area. The analysis also suggests that gradient profile of the watershed presents an important factor for the examined sensitivities to DEM resolution. |
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| Keywords: | Digital elevation model Grid size Topographic attributes Hydrologic modeling |
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