Effectiveness of Spur Jetties at Siuslaw River, Oregon. Report 2. LocalizedCurrent Flow Patterns Induced by Spur Jetties: Airborne Current Measurement System and Prototype/Physical Model Correlation

摘要

The development of an airborne current measurement system that can provide a near-synoptic view of near-bottom currents in extremely hostile wave and current environments is described. A helicopter is used as the support platform from which an electromagnetic current meter is suspended by cable to within one meter of the sea floor. The helicopter hovers overhead while data acquisition is accomplished at each spatial location. Maneuvering ease of the helicopter above the sea surface allows the system to be operated in almost any wave or current environment, around structures, or in dynamic bathymetry. The ability of the helicopter to move quickly from point to point allows nearshore bottom currents to be measured at several locations in a short period of time. Because the meter is not deployed at a stationary location, the use of only one current meter is required, and in situ deployment problems with scour or burying are alleviated. To demonstrate the capabilities of the system, data obtained under high-energy wave conditions at the structured entrance to the Siuslaw River, Florence, OR, are presented, and prototype current patterns are compared with results from sediment tracer tests performed in a previous physical model test. (MM).