Increasing the sustainability and resilience of coastal communities by improving tide gate operation

Improving the operation of tide gates to better protect people and ecosystems is the focus of a three-year project recently funded by the National Science Foundation (NSF).

Global Resilience Institute (GRI) Associate Director Mark Patterson will work alongside Northeastern professors Brian Helmuth and Loretta Fernandez on the tide gate management study, in the town of Revere, at tide gates in Marshfield and at a control site, in Plum Island.

Ed Renier, Senior Wetlands Scientist, EPA, sitting on a a tide gate along Route 1A in Revere, near the Rumney Marsh. Photo credit: Mark Patterson — Ed Renier, Senior Wetlands Scientist, EPA, sitting on a tide gate along Route 1A in Revere, near the Rumney Marsh. Photo credit: Mark Patterson

Tide gates exist to drain tidelands for agriculture and other purposes and consist of a large pipe with a hinged door that opens outwards towards the estuary. Thousands of tide gates exist all across the United States and poor management of these valves can lead to damaging events, including flooding and fire. For example, if too little seawater passes through the gate per tidal cycle, a flammable grass called Phragmites australis can invade, posing a severe seasonal fire risk. If too much seawater comes through, during a king tide or a storm surge, the wetland upstream of the tide gate can be inundated and flood homes adjacent to the wetland.

Tide gates also affect the transport of pollutants through the wetlands – often nursery areas for fish – the pollutants can then potentially be consumed by people if they eat fish or shellfish

“In a nutshell, we hope to do enough monitoring, stakeholder work, and modeling to give towns with tide gates a smartphone app for decision support to minimize the risk of fire and flood and maximize ecosystem health of the wetlands,” Patterson explains.

In cooperation with local stakeholders, tide gate function will be examined in three environments: a large urban coastal marsh with a history of toxin exposure, a smaller urban marsh used recreationally, and a “pristine” marsh.

During the project, Northeastern students working as research assistants at GRI will have opportunities for field study, will meet project stakeholders, and help devise resilient strategies. In addition, two undergraduates working on six month co-ops, and a graduate student, will be trained to help the research team.

“Tide gates are valves that are designed to protect life and property but often negatively affect wetlands.”

The data gathered from field study, along with user community input from workshops, will help the team develop the decision support tools for tide gate operators. The tools will provide advice on when and how much to open the gates under many different scenarios.

Additionally, a dedicated website will provide an online visualization of tide gate state, water chemistry, biota, and toxins, to educate managers, the public, and K12 programs.

“Wetlands are critical to protection of coastal infrastructure,” the group explains in its proposal. “In the face of sea level rise, tide gate use is increasing, but research is lacking on sustainable engineering practice.

“Our research will increase the sustainability, resilience, and anti-fragility of coastal communities because existing tide gates will be better managed, reducing risk of fire and flooding (and toxin dispersal for some sites), while increasing ecosystem services like essential fish habitat and storm mitigation.”