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Title: ANALYSIS OF DEM ACCURACY, GRID CELL SIZE, AND ALTERNATIVE FLOW ROUTING ALGORITHMS FOR ESTIMATING TOPOGRAPHIC ATTRIBUTES

Author
item Erskine, Robert - Rob
item Green, Timothy
item RAMIREZ, JORGE - COLORADO STATE UNIVERSITY
item MACDONALD, LEE - COLORADO STATE UNIVERSITY

Submitted to: Annual Hydrology Days Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 2/13/2004
Publication Date: 3/10/2004
Citation: Erskine, R.H., Green, T.R., Ramirez, J.A., Macdonald, L.H. 2004. Analysis of dem accuracy, grid cell size, and alternative flow routing algorithms for estimating topographic attributes. Annual Hydrology Days Conference Proceedings. Fort Collins, CO. March 10-12, 2004.

Interpretive Summary: Landscape topographic attributes are widely used to describe the spatial variability in various hydrological, geomorphological, and biological processes. These attributes are readily estimated from digital elevation models (DEMs), however these estimates are sensitive to the DEM accuracy and grid cell size. Flow-path dependent attributes, such as specific catchment area, also vary with the flow routing algorithm. This paper examines the effects of DEM accuracy and grid cell size on the estimation of slope, aspect, and curvature on three agricultural fields (approximately 65 ha each) in northeastern Colorado. DEM accuracy varies with data source, sampling method, and interpolation scheme. DEM errors due to the data source selection were greatest. Estimates of slope, aspect, and curvature are sensitive to these elevation errors and their spatial distributions. Specific catchment areas (a) are then computed for selected DEMs using six different flow routing algorithms. The sensitivity of ln(a) to the algorithm selection is quantified for 10-m and 30-m DEMs from two data sources. Applications relating winter wheat crop yield and soil moisture to topographic attributes are presented.

Technical Abstract: Landscape topographic attributes are widely used to describe the spatial variability in various hydrological, geomorphological, and biological processes. These attributes are readily estimated from digital elevation models (DEMs), however these estimates are sensitive to the DEM accuracy and grid cell size. Flow-path dependent attributes, such as specific catchment area, also vary with the flow routing algorithm. This paper examines the effects of DEM accuracy and grid cell size on the estimation of slope, aspect, and curvature on three agricultural fields (approximately 65 ha each) in northeastern Colorado. DEM accuracy varies with data source, sampling method, and interpolation scheme. DEM errors due to the data source selection were greatest. Estimates of slope, aspect, and curvature are sensitive to these elevation errors and their spatial distributions. Specific catchment areas (a) are then computed for selected DEMs using six different flow routing algorithms. The sensitivity of ln(a) to the algorithm selection is quantified for 10-m and 30-m DEMs from two data sources. Applications relating winter wheat crop yield and soil moisture to topographic attributes are presented.