Athenree Estuary mangrove forest. Photo: Supplied/ NIWA- Lana Young
Special monitoring equipment is being installed in Bay of Plenty estuaries to understand how wetlands will fare as sea levels rise.
Wetlands' survival is critical, as they act as a long-term sink for stormwater pollution, and as a habitat for coastal species, NIWA principal scientist Dr Andrew Swales said.
Swales specialises in coastal processes, and led the project to install the monitoring equipment in Athenree Estuary and Ōhiwa Harbour.
Environmental changes mean that in order to survive, wetlands with mangrove and saltmarsh habitats must accumulate sediments and gain elevation at the same rate or faster, than the rise in sea levels.
The five-year study will measure that rate and look at the effect of catchment sediments.
Technicians drive anchoring rods deep into the mud to install RSET monitoring equipment, in Athenree estuary. Photo: Supplied/ NIWA- Lana Young
As sea levels rise, coastal wetlands often shift landwards with the changing waterline. But in many estuaries development along shorelines would prevent the movement, with barriers such as roads, rail or stop banks near the shoreline, Swales said.
"The rate of sea-level rise is accelerating around the New Zealand coast at different rates. This is an opportunity to work with the Bay of Plenty Regional Council to manage these systems and understand the pressures on them."
The research was initiated by the Bay of Plenty Regional Council, who contracted NIWA.
Swales' team installed 12 devices, called Rod Surface Elevation Tables (RSET), that are now used internationally for measuring estuary level changes.
One of the 12 RSET monitoring devices installed at Athenree estuary to measure changes in the sediment level of the estuary over time. Photo: Supplied/ NIWA- Lana Young
Bay of Plenty is only the second place in New Zealand to install the devices for long-term monitoring. The Firth of Thames was the first in 2007, Swales said.
Regional council environmental scientist Shay Dean said the results will be part of local estuarine wetland monitoring.
"Over time, this will be used to interpret any changes in vegetation, the health of saltmarsh wetlands, and their responses to changing environmental conditions," Dean said.
It will also contribute to a five-year study that will design tools and guidance for rural coastal communities nationwide to adapt to sea-level change, called Future Coasts Aotearoa, which is being led by NIWA.
As part of the Future Coasts study NIWA hopes that more RSET sites could be installed in other communities within the next year.