Sailing through nature's obstacle course

April 29, 2015— Shippagan Gully, New Brunswick

Assuring safe passage for Acadian fishing vessels

The Shippagan Gully in northeastern New Brunswick is a direct route between the open waters of the Gulf of St. Lawrence and the commercial harbours of Baie des Chaleurs. In peak fishing season, more than 15,000 tonnes of seafood caught in the Gulf travel inland to be processed and sold. This generates $30 to $50 million in revenue each year that translates into jobs and other benefits for the local economy.

Despite the fact that sailing through this channel is the most direct route, many fishing vessels avoid the Gully, navigating instead around the Acadian Peninsula to offload their catch. Deterring them is a combination of high winds, rough seas, strong tidal currents and accumulated sand that leaves the passage too narrow and too shallow to pass through safely.

Acknowledging the value of Shippagan Gully to the economy, the Department of Fisheries and Oceans (DFO) initiated a project to find the best way to improve the navigation conditions in the channel. But before any infrastructure building could begin, they needed to assess the impact that any new structures would have on wave and current activity. To do so, they turned to engineers at Public Works and Government Services Canada (PWGSC), researchers from the University of Ottawa and technical experts from the National Research Council (NRC) for help.

Channelling success through new waters

"A project in such a complex coastal environment called for a strong team of experienced coastal engineers," says Alain Drouin, a Coastal Engineer at PWGSC. He knew that the National Research Council's (NRC) experts with world-class knowledge and competencies with numerical modelling tools could successfully simulate and forecast the performance of various types of solutions.

In the past, jetties had been constructed at the channel entrance for reducing waves, trapping sand and protecting vessels passing through. However, relentless battering over the years has caused them to deteriorate, leaving the channel less protected. With each boat making an average of 40 trips a season, the additional fuel and time—about six hours every trip—required for the detour has had a substantial impact on profits and productivity.

To analyze and evaluate new options, NRC's team of coastal engineers and scientists relied heavily on numerical modelling tools—CMS-Wave and CMS-Flow—designed to model dynamic coastal processes at tidal inlets like Shippagan Gully. "The models provided us with the intelligence we needed on how each potential solution would affect the movement of water and sediment during storms and over the long term," says Dr. Andrew Cornett, Leader of NRC's Marine Infrastructure, Energy and Water Resources program.

Smooth sailing ahead

Guided by consultations with all stakeholders, NRC modelled more than 20 potential solutions and detailed the advantages and disadvantages of each option, among them, dredging the channel to remove sand accumulation and—to weaken the waves and steer the tidal and wave-driven currents—erecting a retaining wall or constructing an outer jetty. "NRC was a natural choice to do this applied research, since their expertise in such issues, along with sophisticated tools and equipment, can lead to optimum solutions," says Drouin.

Based on this research, DFO made the decision to permanently enlarge the channel, making it both deeper and wider, as well as to construct a new 150-metre outer jetty to block the wave action, deflect the wave-induced currents along the shore and prevent sediment from entering the channel. Once implemented, these measures will ensure cost savings and safer, easier navigation for vessels sailing through the Shippagan Gully. Construction is expected to begin within a few years.

"This is a good-news solution that should have a big impact on the local economy," concludes Drouin. "The increased safety of this waterway will encourage more fishing traffic as well as help tourism." And with the obstacles out of the way, the fleets will soon be netting greater profits.

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