Cowlitz Continuous Non-Contact Discharge Experiment

In December 2003, Hydro21 initiated a significant field experiment at the Cowlitz River streamgaging station in Castle Rock, Washington. The experiment continued Hydro 21's ongoing research into the development of a "non-contact method" that could be used in routine river discharge monitoring by direct measurement of river cross-sectional area, water surface elevation, and water velocity distribution across the river. If the direct, non-contact approach can be proven to be accurate, it would reduce streamgaging costs, improve accuracy, and reduce hazards associated with the traditional methods.

Dangerous measuring conditions by current meter on the Cowlitz River, Washington.

Non-contact radars are much safer to use in high flows.

The Cowlitz continuous non-contact discharge experiment has three components:

a. A series of eight continuous-wave radar antennas were mounted under a bridge pointing upstream, continuously recording surface velocity along streamlines. This work is being done by Bill Plant of the Applied Physics Lab, University of Washington, under a National Science Foundation-supported research grant.

Continuous-wave circular antennas mounted under the Cowlitz River bridge in Castle Rock, Washington.

b. A bankside-mounted microwave pulsed Doppler radar system (10 gigahertz ) like the one used in the Vernalis, California, and Skagit River, Washington, Hydro 21 experiments, built and operated by Bill Plant and the Applied Physics Lab, University of Washington. This system continuously scans the river and measures surface velocity in three- to five-meter bins across the river.

Dish antennas of University of Washington Applied Physics Lab pulsed microwave radar system on roof of shed.

c. A bankside-mounted yagi antenna designed by CODAR that used a 350-megahertz frequency to continuously scan the water-surface velocity on the river. CODAR has a contract with the USGS to design and test their HF radar system for monitoring surface velocity.

CODAR HF radar system with weather station scanning the Cowlitz River, Washington.

d. A new continuous-wave radar (24 gigahertz) antenna (RiverScat) developed by Bill Plant of the University of Washington to be mounted on the top of a ground-penetrating radar (GPR) system that is capable of measuring channel cross-section and surface velocity in one pass from the bank-operated cableway.

RiverScat antenna mounted on ground-penetrating radar antenna collecting cross-sectional and surface-velocity data from a bank-operated cableway without touching the water.

e. Testing an Aquadopp ADCP from the bank-operated cableway as truth data for river currents and geometry.

Aquadopp mounted between catamaran hull of another ADCP for stability in high-velocity flows on Cowlitz River, Washington.

The experiment is designed to run through the end of February 2004. After that time, extensive testing of remote-sensing data will be made against truth data obtained from the streamgaging station, current meter measurements, and ADCP data.