Effects of Data Errors on Computed Steady‐Flow Profiles

Abstract

The effect of stream cross‐sectional geometry and hydraulic roughness data errors on the accuracy of computed steady‐flow water surface profiles is reported. Stream cross‐sectional geometry may be developed by several survey methods. The survey methods studied herein include field surveys, aerial spot elevation surveys, and topographic maps. The different survey methods and associated accuracy specification result in different stream geometry errors. Error in Manning's n‐value is also an important contributing factor to error in computed steady‐flow water surface profiles. A Monte Carlo simulation strategy was applied to develop an array of computed steady‐flow profile errors for the survey methods for 2‐, 5‐, and 10‐ft contour interval accuracy specifications, and Manning's n‐value reliability. Regression equations were derived for estimating computed steady‐flow profile errors. The regression equations relate survey methods, survey accuracy specification, reliability of Manning's n‐value, and stream hyd...