How mapping coastal areas could prepare for an oil spill

A team of researchers is mapping part of Nova Scotia's South Shore coastline in an effort to understand how to protect vulnerable ecosystems if an oil spill ever happened in the province's waters. 

It's all about how the water moves and carries the oil, explained Tim Webster, a research scientist who heads the team at the Applied Geomatics Research Group (AGRG) in Middleton, a division of the Nova Scotia Community College.

"The oil spill recovery people have good models to tell them how quick the oil will come from the deep water. But once it gets near the shore, they don't really have good models to tell them current speeds and current directions," Webster said. 

That might mean cleanup teams wouldn't be able to move fast enough to block oil from moving into fishing grounds, animal habitat, or coastal communities. 

'White ribbon' of blank information

Webster and his team are using LIDAR, a laser sensor mounted on a plane, to build a model of underwater elevations near shore. The model will show how the coastal water moves around those reefs and shoals. 

Underwater elevation mapping, or bathymetry, is typically done from boats using sonar. However, Webster said that means there is no bathymetric data for any areas that are too shallow for boats, leading to a so-called "white ribbon" of blank information along the shorelines of hydrographic charts.

There's also little bathymetric data on areas that haven't been deemed commercially important. 

"This is what's exciting about this technology," Webster said. "We're mapping this section of the near-shore environment that really has never been mapped at this level of detail before."

Verifying the results

The team uses a sensor mounted on a plane that makes multiple passes over a survey area, sending laser pulses downward. The pulses that bounce back to the sensor allow the team to create a topographical map that shows different objects like rocks, buildings and vegetation. 

In late August, Webster's team took a survey of the area around Williams Lake Beach, a salt marsh area just outside of Lockeport, N.S. The team chose the area because the beach was a good representative of a sensitive ecosystem, was close to prospective oil drilling sites, and was known for strong waves. 

The LIDAR technology is new and has rarely been used in this way before, so the team is carefully sampling and recording points on the water and the land, matching and verifying the results from the sensor to what is actually on the ground. 

"We can understand how accurate those [sensor] measurements are, and therefore just give us extra faith in any conclusions we draw from the data," Webster said. 

Targeting spill cleanup

Some of the funding for the project comes from the Offshore Energy Research Association, a non-profit agency whose members include academic institutions and the provincial Department of Energy.

"We tend to know quite a bit about offshore currents," said Stephen Dempsey, OERA's executive director. "They tend to be well-known, predictable. Their movements are well-tracked and well-understood. But in the near shore, in coves, bays, inlets, estuaries, there's really very little understanding about how a contaminant might move inland.

"Let's just use a simple example: is it more likely to come into Halifax harbour, or is it more likely to go into Ship Harbour or Clam Bay? The answers to those questions aren't as well understood." 

Answers like that would be a practical help to staff at the Eastern Canada Response Corporation, a marine oil spill response service. Right now, the company uses trajectory modelling to get an estimate of where oil may go, then places floating curtains called booms to slow the spill down.

The LIDAR map would improve on current trajectory models for oil, and allow people who are trying to clean up a spill to use their limited resources better in a vast ocean. 

"It's driven by the wind and driven by surface currents," said Robert Starkes, manager for ECRC's Atlantic region. "So by better understanding of the surface currents, we can help improve our trajectory modelling, and then we're able to target where best to put our response resources.

"We'd be able to improve where we actually put that boom." 

Thousands of kilometres left to map

However, with more than 13,000 kilometres of coastline in Nova Scotia, the NSCC team has mapped only a fraction of the area in the province during their attempts to prove the new technology works. There is much work left to do, but this is the final year for the oil spill survey. The total cost of the project was $80,000. 

"It would be nice if it could develop into an annual program where we are just sort of chipping away at different sections of the coast to build that up. But we don't have that funding secured at this point," Webster said.

Information available to the public

The topo-bathymetric LIDAR sensor is a technology that has only been in existence for approximately five years. NSCC purchased the sensor in 2013 through a $800,000 grant from the federal Canada Foundation for Innovation, and a matching $800,000 grant from the provincial Nova Scotia Research and Innovation Trust. 

These models are beautiful things. It's like a scratch and win on beautiful data, every day.- Kevin McGuigan, AGRG research associate

Kevin McGuigan, a research associate at Webster's AGRG lab, is usually the first person to see the completed map after he processes the information from the sensor.

He takes the raw information, strips out the "noise" or irrelevant information, and boils the remainder down into the shapes and colours that accurately represent what's on the ground. He says it's a thrill when he sees the finished work. 

"I get the whole emotional roller-coaster ride," he says. "I love the stuff I do. These models are beautiful things. It's like a scratch and win on beautiful data, every day." 

For now though, the NSCC team is among a minority of people who get to see that beautiful data. Webster says to his knowledge, NSCC is the only academic institution in Canada to own such a sensor, and one of only two in North America. 

Other uses for LIDAR

That might not last long. Webster sees plenty of other uses in addition to the oil spill research. The team has used the same technology to predict coastal flooding, and has partnered on work with companies like Acadian Seaplants Ltd. 

"Once we collect these data, they can be used for a variety of applications. Looking at the distribution of kelp beds, where sea urchin habitat could be, seagrass," he said. 

"If there were any aquaculture development in the area, this near-shore information would be invaluable in terms of looking at where perhaps contaminants would move, or other waste products from such an operation." 

Stephen Dempsey of OERA says the public will have access to the oil spill survey maps.

"We make our research all publicly available, so once research is completed, we publish it and we put it on our website, so we want to make sure that everybody has access to it," he said. 

Dempsey said he hopes other groups will use it to develop spill responses for their communities.