Study Reach.--Section 1 is 5,000 ft upstream from cableway at Vernita gage.
Gage Location.--In sec.11, T.13N., R.24E., at the Richmond ferry site, 0.5 mile north of Vernita station. Gage presently operated 50 miles upstream for station called Columbia River at Trinidad, Wash.
Drainage Area.--89,700 sq mi., approximately.
Gage Datum and Elevations of Reference Points.--Not available.
Stage, Discharge Measurements and Computed n-Values.--Gage heights were 48.33 ft at Trinidad gage; 29.5 ft (different datum) at section 1. Peak discharges was 406,000 cfs on May 22, 1949.
Date of Observation | Discharge (ft3/s) | Average Cross Section Area (ft2) | Hydraulic Radius (ft) | Mean Velocity (ft/s) | Slope | Coefficient of Roughness n |
---|---|---|---|---|---|---|
5/22/1949 | 406308.8 | 48566.7 | 27.94 | 8.37 | 0.000194 | 0.024 |
Description of Channel.--Bed consists of slime-covered cobbles and gravel. The straight and steep left bank is composed of cemented cobbles and gravel. The gently sloping right bank consists of cobbles set in gravel and is free of vegetation.