The Spy Who Came in From the Marsh: New Sensors Gather Intelligence on Storms Like Joaquin

October 2, 2015

Dear Joaquin,

I’ve been watching the news coverage of your impending arrival. They’ve been interviewing coastal scientists in the mid-Atlantic states. They’re onto you. Head out to sea!

Sandy

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A team of intrepid scientists from US FWS and USGS venture out in Nor’easter conditions to deploy sensors designed to measure wave dynamics during storms. Credit: Laura Mitchell/USFWS

If you happened to be at Prime Hook National Wildlife Refuge on Friday, October 2 — just 48 hours before the anticipated arrival of Hurricane Joaquin — you might have wondered if you were witnessing a qualifying event for the next season of “Survivor,” or perhaps just an ill-advised dare.

You would have been witnessing something much more exciting: coastal resilience science in action.

In spite of the conditions — extreme high tides, poor visibility, gale-force winds — a team of scientists from the Coastal Delaware National Wildlife Refuge Complex and the U.S. Geological Survey were out on foot and in canoes installing wave sensors at docking poles, many of which were under water at the time.  

Perhaps it’s a little misleading to say the scientists went out “in spite of” the conditions; they went out because of the conditions. Prime Hook is one of dozens of study sites in the Surge, Wave, and Tide Hydrodynamics (SWaTH) Network – an effort initiated in the wake of Hurricane Sandy to measure wave height, force, speed, and extent during hurricane-induced storm surges. It’s just one of a suite projects supported by Department of Interior Hurricane Sandy Recovery Funding to help natural and human communities weather the storms that are predicted to become increasingly frequent and intense as a result of climate change.

The data collected by the SWaTH sensors will be used to refine storm-surge models, create more accurate flood forecasts, design more effective flood-protection infrastructure, and develop wiser land-use policies.

Although Joaquin veered off into the Atlantic before reaching Prime Hook, the preceding Nor’easter provided useful wave data for SWaTH, that will also provide positive reinforce for another project inspired by Hurricane Sandy: the restoration of 4,000 acres of marsh that had been impounded in the 1980s to create freshwater habitat for waterfowl.

Just after the turn of the 21st century, a succession of major storms breached the barrier dunes between Delaware Bay and the impoundments, inundating them with saltwater to the dismay of the freshwater vegetation within.

“Sandy was the final nail in the coffin,” explained Restoration Project Manager Bart Wilson. “About four breaches turned into seven, and suddenly we had this huge area of free-flowing water between the bay and the refuge.”

In the wake of Hurricane Sandy, Prime Hook received resilience funding to dredge 1.1 million cubic acres of sand from a historic salt marsh to restore natural flow, and ultimately, restore the system’s natural capacity to serve as a buffer for storm surges. Credit: Richard Weiner

But Sandy was also an opportunity. Prime Hook received $38 million in recovery and resilience funding to fill the breaches in the barrier dunes, and dredge more than a million cubic yards of sand from the historic salt marsh channels.

“Once the breaches have been filled, and we have natural channels flowing again, the water level will drop, exposing mud flats that will recolonize with saltmarsh vegetation over the next several years,” Wilson said.

Prime Hook Restoration Manager Bart Wilson. Credit: FWS

Although the primary motivation for the project was to restore salt marsh habitat, Wilson pointed out that in the context of future storms, local communities will reap the benefits as well. Literally. As a result of severe flooding from storms, farmers neighboring the refuge have seen the edges of their fields go fallow. Thousands of acres of healthy saltmarsh would have provided a tremendous natural buffer for upland areas.  

“If we had a giant marsh where we have open water now, we wouldn’t even blink an eye during these storms,” Wilson said. “Seawater would wash over the dunes, saltmarsh grass would catch the sand, life would go on.”

It’s a plausible scenario, but Wilson explained that the added value of Prime Hook’s participation in the SWaTH Network is that it will enable them to quantify the value of the restoration project in terms of increasing storm-surge protection. By continually deploying the sensors in advance of storms throughout the multi-year restoration process, scientists will be able to measure how wave dynamics change as the area transitions from open water, to mudflats, to 50-percent vegetation, to a fully restored marsh.

“We can say that salt marshes reduce wave action and flooding, but it will be great to have data to back that up,” he said.

In time, that data can be used to support similar salt marsh restoration projects that will help fortify human and natural coastal communities that are most vulnerable to sea-level rise and major storms.

Considering climate change predictions, Wilson noted, “It’s great timing that we’re doing this now.”

Spread the word, Joaquin.