Airborne coastal current survey system for difficult to access areas

Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to digital@library.tamu.edu, referencing the URI of the item.Includes bibliographical references.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 insitu 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, Oregon are presented, and phototype current patterns are compared with results from sediment tracer tests performed in a previous physical model test