Statistical filtering of river survey and streamflow data for improving At-A-Station hydraulic geometry relations

•AHG relations developed from raw river-gaging observations distorted by local and temporary hydraulic effects.•The distortion can be removed by data-filtering procedures.•Undistorted AHG relations are established for 4472 USGS sites.•The statistical and geographic distributions of the AHG exponents are described.•AHG exponents are employed for estimating the asymptotic power-law riverbed geometry.