The Dykes and Sea Level Rise
The main stream media are reporting the release of a new BC government report – instead of sending you to a paywalled site (one of the reasons there is less on this blog lately is I have made a commitment to my readers not to do that) here is the local CBC as one example
The network of dikes protecting Metro Vancouver will require billions of dollars in upgrades in coming years because of rising sea levels,according to a new report issued by the B.C. government.
The cost of dike improvements over the next 90 to 100 years could hit $9.5 billion, according to a report released today by the Ministry of Forests, Lands and Natural Resource Operations.
Well that was going to be a relief until I read a bit further.
It followed a 2011 report which predicted a sea level rise of one metre along B.C.’s coast by the turn of the next century.
Which is not comforting at all when you consider that the (US) National Oceanic and Atmospheric Administration’s latest assessment was that sea level rise could reach 6.6ft – or two metres – by 2100. But not, apparently, in the Pacific North West according to the side bar in this US Today story
I have had a new book “High Tide on Main Street” on my reading pile for a while now – since superstorm Sandy raised awareness of things like king tides. But I must admit I feel a bit out of my depth [groan] so I have not really felt able to post a review on it – yet.
I am not at all an expert in this area, but for as long as I have lived in Richmond I have wondered about the adequacy of the dyke system – and I have never found the attitudes of the local politicians especially comforting. Complacency has no place in this issue, as far as I am concerned.
Works currently underway in Richmond on the
No 1 Road North Drainage Pump Station Renovation
Stephen Rees's blog 
Great review Stephen.
A comment regarding the NOAA report: it may true that the US North-West is rising (isotactic rebound, the continent breathing a sigh of relief after shedding the weight of the glaciers), but this is not the case for Richmond, in particular. As far as I know, Lulu Island is generally considered to be sinking (a combination of weird isotactic rebound causing the crust to flex, taking the coast down somewhat, and drainage subsidence). Whatever the reasons, if it is sinking, it will experience a relative rise higher than the 1 meter by 2100 figure commonly used; and this figure is now considered a bit rosy. So, complacency is not good news…
Thanks for the post Stephen!
Paul Richard
December 11, 2012 at 1:20 pm
[…] persuade Richmond and Delta to raise their dykes enough to keep the water out of the tunnel itself. (see next post) But secondly, the expansion of Roberts Bank is going to provide a lot more berthing capacity for […]
The Massey Tunnel’s future « Stephen Rees's blog
December 11, 2012 at 3:48 pm
Stephen, I didn’t hit a paywall on the BCMoE site, where the report on costs is discussed, as well as the (more contentious, in my opinion) draft policy where the 1 meter rise was selested. (At least, for Richmond, an extra 0.2 meter was added to account for subsidence.) Upon first look it seems, as i mentioned, a bit of a rose-tinted outlook, especially given the new understanding of the speed at which the glaciers are melting. I’m really not comfortable with the speed at which policy is made regarding Richmond – never mind actually deciding on and buliding adaptation structures. Richmond, with Delta, is the most likely to get flooded the worse if a huge spring storm coincides with spring tides and the Fraser freshet – it’s a given to eventually happen with the current dikes.
Which brings a comment related to your Massey Tunnel post: given the risk of flooding at either end, what are the implications for the tunnel? The mind reels…
Paul Richard
December 11, 2012 at 5:44 pm
You will not hit a paywall from links on this blog. That means that newspaper sites like the Vancouver Sun or the Toronto Globe & Mail are no longer being linked from here. Which is a pity when journalists like Pete McMartin confess to voting Green.
Stephen Rees
December 11, 2012 at 6:10 pm
Thanks for this post, Stephen.
There is the possibility that billions in dike construction may not save Richmond and Delta in the end.
I believe some these reports address (perhaps too limitedly) the salt water infiltration of land behind the dikes i.e. as the current tide rises above the average elevation of the land, the hydrostatic pressure in saturated soils percolates upwards through the ground. This is bound to increase significantly with rising seas no matter how high they build the dikes.
The other issue is that alluvial soils may not be able to bear the weight of higher and broader dikes without sinking. Designing “light weight” dikes with Styrofoam blocking and some kind of internal reinforcement (geotextiles?) would be a good test of the mettle of geotechnical engineers. Trouble is, in some areas with deep soft saturated soils, any additional weight (even just a few centimeters high) will sink over time. Maybe there’s a way to accommodate the sinking with planned increases in dike height, but sooner or later it becomes a question of just how long can this go on in a seismic area.
Richmond (and senior governments) may eventually need to adopt a science fiction attitude and start thinking about creating a floating city, especially when the Metro population tops 4 million by mid-century and other cities are eroding at the seashore edges and end up with a shrinking land base and an unwillingness to accept climate refugees, even those from just across the North Arm of the Fraser.
MB
December 13, 2012 at 12:03 pm
>Which is a pity [MSM paywalls] when journalists like Pete McMartin confess to voting Green.
And when oil-saturated Calgary Centre garners 25% of the popular vote for the Green Party in a bielection.
This is real news. Unfortunately, a hefty portion of the rest of the MSM content is now dreck, and certainly can’t afford to be protected behind a paywall.
MB
December 13, 2012 at 12:20 pm