2018 Matt Blacka Installing a shallow water monitoring station between the motus of Oneroa and Motutapu 2_Muri Lagoon

Update: Hydrodynamics investigation, Muri Lagoon, Cook Islands

Matt Blacka installing a wave, infragravity surge, water level and current monitoring station in Muri LagoonOver the past fortnight, engineers Matt Blacka and Chris Drummond have been hard at work setting up our hydrodynamics investigation at Muri Lagoon for the Mei Te Vai Ki Te Vai project.

On this deployment their work has included:

  • A full RTK-UAV survey of the lagoon system undertaken at low tide, to map outer reef crest debris, intertidal sand shoals, and sediment deposits at each of the stream outlets.
  • A hydrosurvey of the lagoon bathymetry, which has included shallow water echosounding and wading RTK-GPS surveys – most of the lagoon has now been mapped.
  • Configuration and deployment of 6 monitoring stations at strategic locations around the lagoon, which include high frequency water level gauging (for infragravity surge measurements), low frequency water level gauging, current metering and wave gauging.  

This data will help quantify how the lagoon has changed over time, by comparing to similar investigations undertaken several decades ago.

Matt Blacka undertaking a RTK-GPS survey of the lagoonCoupled with results from a wave flume physical modelling investigation, the data will form the backbone of a numerical hydrodynamic model of the Muri Lagoon system. This model along with the collected data sets will be used to investigate the influence of hydrodynamics on ecological processes – in particular the high growth rates of marine algae, and to help develop future management strategies for the lagoon.

In taking a holistic approach, WRL’s monitoring has been undertaken in parallel with other investigations on nutrient discharges into the lagoon through groundwater and sediments (GHD, Southern Cross University), and monitoring of the lagoon ecology (Ministry of Marine Resources Cook Islands).

Keep an eye out for further updates on WRL’s work at Muri, or register your interest in the overall project at the Me Te Vai Ki Te Vai website to receive news updates.

Chris Drummond inspiring the local kids to be involved with science and their environment as he shows off one of the drones at Muri Lagoon

Matt Blacka echosounding and current profiling from the custom designed RV Ocean Kayak. This sophisticated research vessel is equipped with on-board RTK-GPS positioning and an M9 Riversurveyor for acoustic profiling of currents and shallow-water bed mapping

Infragravity surge, water level and current monitoring station

Matt Blacka installing a shallow water monitoring station between the motus of Oneroa and Motutapu

For further information contact:

Matt Blacka | Principal Engineer - Coastal | m.blacka@wrl.unsw.edu.au

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