Tairua and Pauanui Physical Processes Studies

A range of data was collected to better understand sediment dynamics and sediment facies on the seabed immediately offshore from Tairua and Pauanui Beaches, on the eastern coast of the Coromandel Peninsula. The study also aimed to investigate sand system evolution and processes, beach-shelf linkages, sand supplies. It also provided information for models - e.g. parameters for roughness. Sidescan sonar and other data identified complex sedimentary facies, including shallow depressions (<0.5 m deep) in the sandy seafloor that are floored with coarse rippled sediment. The sharp facies boundaries around these ares maintained their location at annual time scales despite large sotrm events. Researchers concluded that sand supplies are insufficient to bury the mega-rippled coarse sediments and/or the coarse patches are maintained with the assistance of turbulent induced resuspendsion over the rough bed.

Sidescan sonar and echo sound data throughout the Tairua-Pauanui embayment. Ground truthing included sediment samples, SCUBA observations and video drops. Instrument tripods measured waves, currents and sediment transport at 15 m and 22 m water depth over a period of 37 days. Ground penetrating radar and sub-bottom profiling of the sand barriers and offshore. Numerical modelling of waves and currents was undertaken.

Tairua-Pauanui Embayment

2001

C-max sidescan sonar (300 kHz), shore parallel tracks 350 m apart, with a range of 200 m each side of the vessel (50 m overlap). Seabed mapped to approximately 5 km offshore. Sidescan mapping undertaken twice, in September 2000 and September 2001. ECHOTRAC depth sounding system with heave compensation. Three tripods measuring beform development and suspension dynamics, two in 22 m water depth, one in 15 m. All tripods had pressure sensor for waves, current meters, and multi-frequency acoustic backscatter sensor. Model runs undertaken using MIKE21

Varied with data type and methodologies.

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The work was undertaken in cooperation with the Virginian Institute of Marine Sciences.