Subcatchment Parameterization for Runoff Modeling Using Digital Elevation Models

by Jurgen Garbrecht, (M.ASCE),
Lawrence W. Martz,
David C. Goodrich, (M.ASCE),

Document Type: Proceeding Paper

Part of: North American Water and Environment Congress & Destructive Water


Numerical algorithms are presented to estimate the length, width and slope of rectangular planes representing irregularly shaped overland contributing areas defined on raster Digital Elevation Models (DEM). The strength of the procedure lies in that each flow path on the raster overland area is considered in the determination of the representative value for the entire rectangular plane as opposed to relying on a lumped, single flow path approach. The flow path parameters required by the algorithms are derived from raster maps of elevation (DEN), flow direction and upstream area. Qualitative cause-effect relations between flow path and runoff characteristics are used to emphasize those flow paths that are important to runoff formation and propagation. Based upon these considerations, the plane length and slope are computed as a weighted mean flow path length and slope over all flow paths of the overland area. Several alternative weighting factors are proposed. Based on area conservation, the plane width is computed as the overland area divided by the plane length.

Subject Headings: Runoff | Numerical models | Slopes | Algorithms | Parameters (statistics) | Mapping | Computing in civil engineering

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