By Christopher Williams

Called the Wolastoq, a Maliseet word meaning “bountiful beautiful river”, the Saint John River is about 700 kilometres long. About 30 per cent of the watershed are the headwaters in Maine and Quebec. From there, the river flows through the north-south length of eastern New Brunswick before emptying into the Bay of Fundy.

The fresh water also carries a varying load of suspended sediment, also known as silt. At the mouth of the river, where port operations take place, tides in excess of eight metres push the sediment, along with some originating in the Bay of Fundy, back again.

These natural phenomena require Saint John Port Authority to spend an average of $2.5 million annually to dredge the harbour to provide sufficient draft. Of greatest concern is the siltation in Courtenay Bay channel and turning basin through which tanker traffic and vessels using the potash terminal must travel. This area represents over 70 per cent of annual dredging costs.

Fortunately, SJPA began partnering with the Canadian Rivers Institute (CRI), and the Ocean Mapping Group (OMG) at the University of New Brunswick (UNB) three years ago to study the sedimentation, circulation and currents in Saint John Harbour. “Our goal is to understand these patterns and seek ways to improve methods in order to reduce cost to the Port Authority and its users,” says Jim Quinn, President and CEO of Saint John Port Authority.

With another year of study ahead, the work of a dynamic research team is already shedding new light on the effects of tides and currents. “Our fieldwork and modelling has revealed points of interest in the harbour for us to focus on more closely, such as the tip of the breakwater at the end of Courtenay Channel,” observes Dr. Katy Haralampides, Associate Professor of Civil Engineering at UNB, who leads the study. “There are interesting hydrodynamics and sediment transport occurrences at the end of the breakwater.”

Dr. Haralampides, who holds a Ph.D. in Engineering and Applied Science from the University of New Orleans, says the collaborative research team conducted ship-based analyses at various times of the year over a full tidal cycle, and deployed two Acoustic Doppler Current Profilers on the bed of the inner harbour to collect continuous data.

“We were able to view the tidal environment with fresh water from the river at the top of the water column, and the salt wedge from the Bay that comes in and goes out with the tide, bearing the bulk of the sediments that build up in the harbour.” Dr. Haralampides says the field data are helping create a model for four distinct hydrological seasons: March (low winter flows), April (spring freshet), June (low summer flows), and November (high fall flows).

The researchers have also been collecting turbidity measurements from a near-shore station and a probe in the channel. What do they do with these data? “We are trying to correlate the observed suspended sediment mobilization in the river with regularly monitored hydro-meteorological data using statistical frequency analyses,” adds Dr. Haralampides, who teaches courses in water resources.

The CRI team is also looking at the ecology of the port area by mapping seasonal distributions of the animals throughout the Saint John Harbour to determine actual and potential impacts of the present harbour management program.

It sounds easy the way she describes it, but the complex and dangerous currents and extreme tidal range in the harbour make the fieldwork and instrument deployments very challenging.  “Add the Canadian East Coast weather, winds, storms, and strong spring freshet from the Saint John River, and you have very small windows of opportunities for sampling safely and effectively in the harbour.”

Jim Quinn, President and CEO, SJPA says New Brunswick is fortunate to have research facilities such as the Canadian Rivers Institute (CRI) and the Ocean Mapping Group located here. “They have world-class expertise available to examine the diverse ecosystems,” affirms Quinn. “Port Saint John has been engaged in a fundamentally important multi-year study with CRI with the goal to seek a better understanding of the various factors which lead to siltation in our harbour. The continued research provides answers to long-term questions from the port while maintaining and expanding a research capability at UNB.”