Waiapu River, New Zealand

Plume

Funding Agency: NSF

 Summary: Continental margins have long been recognized as important and rich reservoirs of  information on earth history, and contain a detailed record of climate, geomorphic evolution and land-use practices, sea level, tectonics, and oceanographic processes.  As compared with the deep-sea record, margins have a far greater potential to preserve high-resolution continental records because of their proximity and high sediment inputs from rivers.  Despite this recognition and concerted scientific efforts over past decades, scientists presently lack the ability either to accurately predict stratigraphic development of margins given a realistic set of controlling processes, or to reconstruct these processes from the stratigraphic record.

Collaborators

VIMS: Carl Friedrichs, Courtney Harris, Jesse McNinch, Don Wright

NIWA: Malcolm Green, Alan Orpin, Terry Hume

Victoria: Lionel Carter

NCSU: Neal Blair and Lonnie Leithold

Field Methods, Equipment and Vessels

The proposed study combines field observations (see table) and models to elucidate sediment dynamics and resulting stratigraphy.  Bottom-boundary layer measurements of resuspension and transport due to waves and currents will be made under a range of forcing conditions on the inner and middle shelf using near-bottom tripods.  An instrument array moored along-shelf on the ~30 m isobath will complement the bottom boundary measurements.  Seabed sampling and measurements will document deposition from the initial flood pulse as well as the subsequent redistribution of material by waves and currents, and examine both the fine-scale stratigraphy developed over a flood season and longer-term accumulation and stratigraphic signatures.  We expect to find evidence in the seabed of the massive increase in sediment discharge resulting from European deforestation.  All of these observations will be used to calibrate analytical and numerical models of sediment transport and deposition that will be refined to test emerging hypothesis of transport processes, and to extend the observations to longer spatial and temporal scales.

Field equipment included the EM1002 Swath Bathymetric System, Chirp 512i, 3.5 kHz pinger, kasten, box, and multi-corers, and x-ray device. 

Research Vessels used were the RV Tangaroa (8/2003) and the RV Kilo Moana (05/2004).