ASR - A Global Partner for the Sustainable Management of Coastal and Marine Resources

Port Taranaki

Location: Port Taranaki, New Plymouth, New Zealand

Type of Project: Ports Operations, Numerical Modeling

Client: Westgate Transport Ltd, New Zealand

ASR Projects- Port Taranaki

(Center): The MV Pelican dumping sand at the new deposition ground. (Clockwise from upper left): Predicted change in the wave propagation direction due to the sediment dumping. This illustrates how the mound of dredge spoils would modify the wave propagation direction; Recorded positions of the MV Pelican during both offshore and nearshore dumping operations; modelled wave height patterns without the offshore mound; digitized map of the December 2003 side-scan sonar survey.

Project Overview:

Westgate Transport Ltd applied to the Taranaki Regional Council (TRC) for the renewal of permits to continue maintenance dredging of the navigation channels at Port Taranaki. ASR Ltd were commissioned by Westgate Transport Ltd to seek the best sites for placement of the dredged material and, once selected, to measure and predict the effects on the environment in relation to the port’s regular maintenance dredging program.

Project Outcomes:

Large-scale field experiments were conducted at New Plymouth in order to examine the coastal and sediment dynamics and provide data for the calibration and validation of the numerical models. A one-year experimental program was designed and implemented with the following components: a trial nearshore placement of dredged material; monthly hydrographic surveys of the trial placement and the breakwater tip shoal; quarterly side-scan sonar surveys; a sediment tracer release and sampling program, a two-month measurement of suspended sediment profiles from 23 sites; a two-month deployment of 13 wave and current meters; a one-year deployment of directional wave and current meters inshore and offshore, and one-year recording of tides and weather conditions. The data were combined with extensive numerical modelling to paint a clear picture of the effects of the dredging operations. This information was used by Westgate and the TRC to make sensible decisions regarding future dredging operations.

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