Mapping our future

One NSCC researcher says the key to avoiding the worst of in-land flooding during increasingly more common, more severe storm events is to get ahead of them with potentially life-saving predictive mapping.

NSCC’s Coastal Flooding Map. Photo courtesy of NSCC Geomatics Dept.

Dr. Tim Webster loves Nova Scotia. It’s safe to say that simple truth is at the core of where life and work have taken him up to now.

A research scientist within the NSCC’s Applied Geomatics Research Group, Webster, who focuses on coastal zone management, river and coastal flood assessments, erosion studies, and land stability analysis, also has a love of the coast, fostered, he says, at a young age.

“My family, from the time I was born, had a cottage on the Northumberland Strait.”

The Northumberland Strait, where Webster now has his own family cottage, runs along the north coast of Nova Scotia and is one of the areas of the province Webster points to as most at risk from the challenges presented by climate change activity and storm surge.

“When any given event happens, the storm surges are typically higher in the Strait,” he says. “It also has relatively easily erodible material — it’s either glacial material, in terms of mud or rock, or it’s sandstone, unlike the Atlantic coast, where we have harder metamorphic rocks or granite.”

And it’s that risk of flooding and threats to coastal communities that spurs on his work to map areas through lidar mapping technology. Mapping that could, if implemented across the province, possibly save lives in future flooding events, much like the in-land river flooding we saw in 2023 and 2024, says Webster.

“I think there’s a lot more that could be done in terms of warning people, giving them a heads up, and showing them the worst case scenario; that even if it’s predicted to be “x,” if it’s x plus 25 per or 50 percent, here’s the situation — you better really pay attention, and not just go to bed assuming it’ll all be according to plan,” he says.

Webster, through his work mapping river and coastal flooding assessments, says the large Nova Scotia storm of July 2023 is a good example of a weather event that didn’t go as predicted.

“We had four people perish. It was terrifying near Windsor, and it of course flooded Bedford. And then last year we had a youth die in the Wolfville area because of one of these heavy rainfall events,” he says. “I think it’s something we need to try to develop an early warning system for, even though it’s quite challenging.

Top photo from an area of the Northumberland Shoreline and bottom of same area during a storm event. Photos courtesy of NSCC Geomatics Dept.

In 2014, and as a direct result of winning a Canada Foundation for Innovation award, Webster was able to purchase Topo-Bathymetric lidar technology (and related equipment), which goes beyond regular lidar, and is the key to good predictive coastal and mapping, he says. Regular Lidar technology surveys land elevation, but Bathymetric can also survey under the water out to 15 to 20 metre depths — giving a better idea of where water will go on land during storm events, but also how it behaves in a coastal zone.

“During a storm, how does that water move and circulate and then inundate the land,” Webster says.

Between 2009 and 2012, Webster and his team, working in conjunction with the NS Department of Environment and Climate Change, mapped five Nova Scotian coastal communities, generating flood maps, and since then, he says, they’ve continued to work with the provincial government agency to figure out where, for instance, forested wetlands are, as the newer lidar technology has the ability to see between the trees [to a certain extent].

So where are we now in terms of coastal and river flooding mapping? And more importantly, a business or property owner’s access to that information? Webster says the key is more mapping; work which increasingly, in the absence of a province-wide Coastal Protection Act, is now falling to often ill-prepared municipalities.

“Let’s say there’s a hurricane approaching, at our lab we would proactively be generating maps and sharing those with our EMO (Emergency Management Office) colleagues,” he says. “And the big issue with a lot of the municipalities is flood risk, which the province is somewhat dealing with through their flood line mapping program, but I’d like to see them push it to the municipalities a little sooner.”

And people he says are “thirsty for information” about how to best protect their property, where they should build, and what type of protection they should be looking at.

“Nature-based solutions are highly promoted, and I believe in them 100 per cent in the right environment,” he says. “But that environment is not when you’re exposed to the North Atlantic, whether it be the Northumberland Strait, the South Shore, the Eastern Shore, etc.”

In that case, Webster says landowners need to be looking at the large boulder-like rocks you often see along coastline properties in his neck of the woods up on the Northumberland Shore.

Additionally, he adds that the LaHave area of the South Shore and its connection with Bridgewater is one of several areas of the province more at risk as a result of that sea-river connection. It’s a similar situation for the town of Oxford, where River Phillip can cause over-land flooding due to the influence of tide and sea level, even though they’re 18 km from the coast; and is the case for many other Nova Scotian communities built along estuaries influenced by tides and river outflow.

“Believe it or not the tide goes all the way up to Bridgewater,” he says. “So, we have this unique situation of the river runoff interacting with the coastal processes…if you have elevated sea levels it actually slows the river discharge down and river starts to back up.”

In other words, tides, not just storm surge, play a large role in how a river (like the LaHave) will react during a weather event.

And to add insult to injury, the province, says Webster, is sinking.

“As a result of the last glaciation, isostatic adjustment taking place of the crust, we’re actually sinking by about 15 cm per century.”

That subsidence, or gradual caving in or sinking, is built into the approximately 32 centimetres per century of relative sea level rise we see across the province, and more climate-change related storms hitting us.

Webster says there’s more needed in terms of mapping the entire province. Something he and the rest of his Geomatics department are eager and able to do if they can access the right funding. Relative sea level rise is measured at tide gauges in the region (Halifax, Yarmouth, etc.) and is a combination of global sea level rise and crustal subsidence, so it shows the change in sea level relative to the land.

His team recently applied for Research Nova Scotia funding for a seven-year project that would see his department work to develop an early (real time) warning system for storm surges and river flooding; collaborate with a local indigenous-owned company on wildfire behaviour software; focus on coastal erosion work, and do geo-forensic mapping after a storm event, but they unfortunately weren’t one of the chosen proposals. That has left them, says Webster, looking for alternate funding and partnership opportunities.

“We could easily map the entire province if we could get funding,” he says. “That’s the frustrating part — we know what needs to be done, we have the skill, and we have the tools, as well as most of the data.”

In the meantime, Webster recommends checking out NSCC’s online Coastal Flooding Mapping site (https://agrgims.cogs.nscc.ca/CoastalFlooding/Map/) to get a sense of where and how they’ve mapped to date. It also provides a peek into what could be done across the entire province if Tim Webster and his group gained access to the necessary long-term funding to do so.

Climate Stories Atlantic is an initiative of Climate Focus, a non-profit organization dedicated to covering stories about community-driven climate solutions.

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