Hydrodynamics and sediment transport on the North Canterbury Shelf, New Zealand

Abstract

This study uses a combination of regional ocean modelling systems (ROMS), a sediment transport model (sedtrans05) and detailed grainsize data with the aim of determining the hydrodynamics and primary sediment transport pathways on the North Canterbury Shelf (NCS), South Island of New Zealand. Combining the results from the hydrodynamic model, sediment grainsize data and sediment transport model in an unsupervised classification scheme, highlights 5 classes of sediment on the shelf. These classes include a high energy inner shelf with coarse sands and gravels (Class 1), a low to medium energy mid shelf allowing for the deposition of fine sediments in a large depocenter (Class 2 and 3), and an area on the mid to outer shelf of relict coarse sediments (Class 4). With the exception of Class 4, the sediment distribution is in equilibrium with the modern hydrodynamics and validates the ROMS and SedTrans05 models. This understanding of the NCS hydrodynamic and sedimentary system will help with the management of the marine environment, with the caveat that this is a highly dynamic environment which is influenced of earthquakes and large storms influencing erosion, transport and distribution of sediment in this region.

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