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Act now to prevent flood conditions in South Delta, warns SFU geologist
While the end of the century may seem like a long way off from now, a professor of geology at SFU warns now is the time to act to protect South Delta from the possibility of widespread flooding caused a gradually warming global climate and subsequent rising sea levels.
But Delta officials are not rushing to commit a vast amount of funds to deal with the projected problem.
In an interview with the Leader, SFU professor John Clauge said due to the effects of global warming sea levels are currently rising three millimetres each year.
"A warming climate results in melting of glaciers and increasingly it is having effect on the big ice sheets in Greenland," said Clague who talked on the subject Sunday (Feb. 19) at the AGM of the American Academy of the Advancement of Science in Vancouver.
Given that rate, Clague said sea levels could rise by 30 centimetres in 80 years, which if nothing more was done to reinforce and raise Delta's dykes could result in frequent flood conditions.
"Thirty centimetres—well that's a foot," Clague said. "And while you may think that's not very much, we can deal with that, it requires actions up front."
One is building a sea wall to protect some areas of Beach Grove that are not protected by a dike. And raising and strengthening of other dikes would be needed.
Clague added he believes the 30 centimetre scenario is a low-ball estimate.
"It assumes that sea levels in the future to climb at the rate it's presently climbing," he said. "But as the climate gets warmer, we will probably see an acceleration of melting of glaciers and ice sheets and that will result in a more rapid rise in sea level."
So how much could it rise?
Clague said the best estimates from the scientific community peg it at one metre.
"That's kind of at the limit of what we can deal with through hard engineering, through improving protective dikes" he said. "It still can be done, but it's very costly."
So could the damage be, as well, if nothing more was done over the coming decades.
"Almost the entire surface of the entire jurisdiction (South Delta) would flooded on occasion, at times of high tide and storms," he said. "That option of doing nothing, if the projections play out, is unreasonable. There has to be some action taken."
Delta Mayor Lois Jackson said the notion of rising sea levels is nothing new to the region and the Corporation of Delta has been taking proactive measures in raising dike levels in some areas.
"This is not news to us," Jackson said. "This is an old story, really. These things are known to our staff. It's unfortunate it has come out this way without them having talked to our staff to find what we have been doing."
"I think they were telling us the same things in the 1950s about flooding and raising our dikes in Richmond and Ladner," added Coun. Ian Paton. "I'm not disbelieving that it's probably a concern, but just imagine the cost of the infrastructure to raise the dikes all over Delta. For a population of 97,000 where would we possibly get the money for such a project?"
Paton said Delta has made grant applications to the federal government for three separate dike raising projects in East Delta.
"And we're slowly working our way west to Beach Grove," he said.
But will that by itself be enough?
SFU's Clague said there are other defensive strategies that can be employed to hold the waters back.
One is to develop protective barriers offshore.
"These would probably be engineered but more like natural barriers of sand that would mimic some of the barrier islands we see in parts the southern U.S.," Clague said.
While that wouldn't affect the level of the sea, it would reduce the impact of waves on the foreshore area.
"These issues largely come into play when you have severe storms, typically storms in the Straight of Georgia will drive water to the west or into Boundary Bay and raise water levels on their own, irrespective of what the sea level is," Clague said.
Other options include developing elevated living spaces for houses or important infrastructure to allow occasional storm waters to flood the surface to shallow depths, but not damage homes and businesses.
"That seems to me as not a very viable solution," Clague said. "First of all it's quite costly, and it doesn't take into account you have buried utilities—gas lines and all sorts of things are going to be affected by flooding."
With housing stocks turning over every 50 years or so, another option is to take your community and retreat to higher ground," Clague said.
"Yield that area to the sea, but over a long period of time. It's tough. Communities like Ladner there's going to be considerable pressure to protect, so the options of hard infrastructure of improving and extending the diking system is likely going to be the preferred option. And that's certainly feasible at the lower end of the projections."