Accuracy of Computed Water Surface Profiles

by Darryl W. Davis, Hydrologic Engineering Cent, Davis, CA, USA,
Michael W. Burnham, Hydrologic Engineering Cent, Davis, CA, USA,



Document Type: Proceeding Paper

Part of: Hydraulic Engineering

Abstract:

Stream cross-sectional geometry obtained from aerial surveys (aerial spot elevations and topographic maps) that conform to mapping industry standards are more accurate than is often recognized. Cross-sectional geometry obtained from the aerial spot elevation surveys is about twice as accurate as cross-sectional geometry obtained from topographic maps derived from aerial surveys for the same contour interval. The effect of aerial spot elevation survey or topographic mapping accuracy on the accuracy of computed water surface profiles can be predicted using the mapping industry accuracy standards, reliability of Manning's coefficient, and stream hydraulic variables. The reliability of the estimation of Manning's coefficient has a major impact on the accuracy of the computed water surface profile.

Subject Headings: Topographic surveys | Mapping | Water surface profiles | Geodetic surveys | Computing in civil engineering | Aerial surveys | Geometrics

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