Ralph T. Cheng

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Conceptual models for tidal period and low-frequency variations in sea level, currents, and mixing processes in the northern and southern reaches of San Francisco Bay describe the contrasting characteristics and dissimilar processes and rates in these embayments: The northern reach is a partially mixed estuary whereas the southern reach (South Bay) is a(More)
To fully understand the hydraulic properties of natural rivers, velocity distribution in the river cross-section should be studied in detail. The measurement task is not straightforward because there is not an instrument that can measure the velocity distribution covering the entire crosssection. Particularly, the velocities in regions near the free surface(More)
A RiverSonde radar system, operating at a frequency of approximately 350 MHz in the ultrahigh frequency (UHF) band, was installed on the Cowlitz River at Castle Rock, Washington, USA during October 2003 and has been operating for several months. Using techniques and equipment developed over several decades for measuring ocean surface currents at much lower(More)
Two RiverSondes were operated simultaneously in close proximity in order to provide a two-dimensional map of river surface velocity. The initial test was carried out at Threemile Slough in central California. The two radars were installed about 135 m apart on the same bank of the channel. Each radar used a 3-yagi antenna array and determined signal(More)
A UHF RiverSonde system, operating near 350 MHz, has been in operation at Threemile Slough in central California, USA since September 2004. The water in the slough is dominated by tidal effects, with flow reversals four times a day and a peak velocity of about 0.8 m/s in each direction. Water level and water velocity are continually measured by the U. S.(More)
The hydrodynamic and constituent transport model UnTRIM was used to simulate hydrodynamics in Upper Klamath Lake, a shallow, hypereutrophic lake in which currents are responsive primarily to wind forcing. A simplified version of a dissolved oxygen model was used to simulate the transport of oxygen-depleted water from a deep trench on the western shoreline(More)
Two-dimensional river flow patterns have been measured using a pair of RiverSondes in two experiments in the Sacramento-San Joaquin River Delta system of central California during April and October 2007. An experiment was conducted at Walnut Grove, California in order to explore the use of dual RiverSondes to measure flow patterns at a location which is(More)
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