Ningaloo Reef Circulation Study, Western Australia (1997)

Full description

An observational instrument array consisting of three Acoustic Doppler Current Profilers, six S4 Vector Averaging Current Meters (four of which were capable of wave measurements) one SeaPac 2100 Wave Gauge and four Water Level Recorders was deployed in a section of Ningaloo Reef for a period of fourteen days in November/December 1997. In addition a Waverider buoy was deployed well offshore and approximately 2.6 nautical miles north of the study region.

The study site was chosen to fulfil two criteria:
1. the reef system had to be typical of the other reefs in the area: a series of reefs running approximately parallel to the coast separated by deep, narrow channels, and separated from the coast by wide lagoons open at both the north and south ends.
2. the area had to be sufficiently small to allow adequate coverage by the observational instrument array.

The study location consisted of two reefs, each approximately 1km long, separated by a 100m wide channel. A shallow, 500m wide lagoon separated the reefs from the beach. Both reef faces had slopes of approximately 1 to 25 and rose from a depth of 10m to between 0m and 1m on the reef top. Instrument locations were chosen to observe all physically significant, short-term oceanographic processes that occur in, and influence the study region.

Bathymetry data was also recorded using a downward looking Acoustic Doppler Current Meter mounted on the transom of a small boat and a DGPS positioning system.

Meteorological data was obtained from the AIMS automatic weather station at the Milyering Visitor Centre, 30km south of the study region.


The Ningaloo Reef study was undertaken to obtain a comprehensive dataset on the physical oceanographic processes that influence the circulation and flushing of the reefs in the Ningaloo region. Data obtained will be utilised to verify theoretical and numerical models of these oceanographic processes, such that these models can be generically applied to the Ningaloo Reef region as a whole.


Instruments were deployed as follows:
(a) An S4 current meter with an internal water level sensor was located in the northern entrance to the northern lagoon (Site 1) to measure flow into and out of the lagoon from the north.

(b) An S4 current meter and Water Level Recorder (tide gauge) were located in the southern entrance to the southern lagoon (Site 2) to measure flow into and out of the lagoon from the south.

(c) An S4 Current meter/Wave gauge was deployed in the channel between the two reefs (Site 3) to observe flow through this entrance.

(d) A Water Level Recorder (tide gauge) was located within the lagoon, but in line with the channel between the two reefs (Site 4), to provide water level data within the lagoon relative to the water levels observed at both the northern and southern entrances.

(e) Two Water Level Recorders (tide gauges) and two Acoustic Doppler Current Profilers were located In the deeper water immediately seaward of both the Northern (Site 5) and Southern (Site 6) reefs, to observe the water level and current structure in front of the reefs, and give some indication of the flow of water towards the reef front.

(f) Current meter/Wave gauges were deployed near the reef break (Site 7) and slightly landward of the reef break (Site 8) of the northern reef and near the reef break (Site 9) and slightly landward of the reef break (Site 10) of the southern reef, to observe flow and wave height over the reef top.

(g) A Waverider buoy was deployed offshore (Site 11) to observe swell incident on the study area.

Lineage

Maintenance and Update Frequency: notPlanned

Statement: Statement: Data will be supplied in raw form. It is up to the person requesting the data to apply QAQC procedures.Position finding:Position finding was accomplished using hand-held Garmin SurveyII GPS. A temporary base station was established for the duration of the study and Differential GPS accuracy was achieved by post-processing field and base station data. The WGS84 datum was used for all positions.

Notes

Credit
Brinkman, Richard M, Dr (Co Investigator)

Credit
Massel, Stanislaw R, Dr (Principal Investigator)