Computation of discharge using the index-velocity method in tidally affected areas

Abstract

CONVERSION FACTORS Multiply By To obtain foot (ft) 0.3048 meter foot per second (ft/s) 0.3048 meter per second square foot (ft 2) 929.0 square centimeter cubic foot per second (ft 3 /s) 0.02832 cubic meter per second inch (in.) 2.54 centimeter inch per hour (in/hr) 2.54 centimeter per hour ABBREVIATIONS ADVM acoustic Doppler velocity meter Bay San Francisco Bay bins range gated sample volume Delta Sacramento-San Joaquin River Delta GPS geographic positioning system < less than PST Pacific Standard Time UVM ultrasonic velocity meter mean velocity V i index velocity V p water velocity along the acoustic path

Evaluation of the potential for hysteresis in index-velocity ratings for the Chicago Sanitary and Ship Canal near Lemont, Illinois

“…The sixth technical review committee expressed concern that the index-velocity rating at this gage may be subject to hysteresis due to the unique, unsteady hydraulics of the canal. Hysteresis in index-velocity ratings can occur at sites where the flow distribution in the channel varies significantly between the rising and falling limbs of the hydrograph for the same discharge (Ruhl and Simpson, 2005). Presently, hysteresis in index-velocity ratings has been documented only at tidally affected sites.…”

“…Specifically, the rating curves for the rising and falling limbs of a flood wave are not coincident, resulting in a loop-shaped rating curve for the entire event. Hysteresis in index-velocity ratings has been documented at tidally affected sites (for example, Ruhl and Simpson, 2005) due to the large changes in flow distribution in the measurement section over the course of the tidal cycle. Changes in flow distribution in the section can result in two separate index velocities for the same discharge (or same mean cross-sectional velocity), leading to hysteresis.…”

Hydrologic characterization of Bushy Park Reservoir, South Carolina, 2013–15

“…The computation of continuous streamflow data at the velocity sites is accomplished in three steps (Ruhl and Simpson, 2005;Lanier and Conrads, 2010;Levesque and Oberg, 2012). The first step is the development of a stagearea curve that establishes a relation between the river stage at each site and the cross-sectional area.…”

Hydrology, phosphorus, and suspended solids in five agricultural streams in the Lower Fox River and Green Bay Watersheds, Wisconsin, Water Years 2004-06

“…An acoustic Doppler current profiler (ADCP) was installed at the East River site to measure water velocities because this site is affected by backwater and seiche effects from Green Bay. Water velocities and the cross-sectional areas were then used to determine the discharge at this site (Laenen, 1985;Oberg and others, 2005;Ruhl and Simpson, 2005) Each station was equipped with a stage-activated, refrigerated sampler for automated collection of water samples that are representative of different flow conditions (increasing and decreasing flow). A data logger was programmed to collect a sample with each 0.2-ft increase in stage once the stage reached an initial sampling threshold.…”