image credit : pixel boy
Down Poole Harbour Way
by Jo Abbess
16th April 2008
A report on rising sea levels has been presented today at the European Geosciences Union in Vienna, showing that improved models have been able to accurately mimic sea level rises, as reliably observed by tide gauges over the last 300 years :-
This work from the the Proudman Oceanographic Laboratory near Liverpool in England confirms projections from ice sheet melt measurements, that sea levels could rise somewhere between 0.8m and 1.5m by the year 2100.
Down Poole Harbour way, we take news like this very seriously. Or rather, we ought to. The 1 metre and 2 metre land contours above sea levels around the historic port of Poole take in major points of infrastructure.
Development for the area includes thousands of new affordably housing "dwelling units", massive retail renovation and expansion, a new railway station, moving the train station from a bend to the straight, a new road bridge over the Harbour and investment in tourism in the area, including the famous Quay.
Poole is set to become famous in the next few years, as it is on the railway from London to Weymouth where the water sports for the 2012 Olympics will take place.
A part of Poole has been made famous over the last year with the televising of a documentary about Sandbanks, a zone of large properties where the very wealthy people of South England like to live.
A lot of the town is low-lying, as befits a Harbour and coastal town, so what could the impacts be if sea levels rise at twice the rate of current IPCC projections ?
Every day, boats the size of several hundred large elephants chug slowly in and out of the Main Channel at Poole, bound for or returning from the Channel Islands, and St Malo and Cherbourg in France.
The Main Channel is very narrow and has a rapid flow of very large volumes of water, gushing back and forth with the tides.
Massive quantities of sediment are carried from the rivers that feed the Harbour, and from silt in the Harbour itself, in and out of the Harbour mouth.
Every year there is dredging of thousands of tonnes of material from the Main Channel, to keep it seaworthy and protect the Harbour.
With the rainfall change predicted for Climate Change, it is likely that the amount of run-off from the land around the Harbour will increase, bringing more sediment into play.
What would happen if economic recession and escalating sedimentary deposition were to strain the dredging budget to breaking point ?
The new road bridge, "Twin Sails" has been designed and planned for a while now, and should be a triumph of engineering, and very beautiful too, and will permit increasing volumes of road traffic over the Harbour at quite some cost.
Looking into the engineering designs, the bridge span has been designed to rise over 4.5 metres above the current water flow. Why this high ? Is it that the good engineers anticipate not only small watercraft making their way under the bridge, but also want to ensure the road stays above any storm surge and flooding ?
What height could the flood waters and storm surge reach ?
The railway system around Poole is already easily compromised. Despite works to protect the tracks, they are actually roughly at sea level, and so any increase in average sea level, and any major storm turbulence would threaten passage beyond the town.
What would happen if Weymouth became inaccessible by railway during the Olympics, and all the major roadways were inundated as well ?
Local Sustainable Development group Poole Agenda 21 has had oversight of some of the plans for the new North Poole retail and car parking area.
Millions of Pounds Sterling is going to be sunk into this project, to provide more retail, more car parking facilities, and of course, some affordable housing.
PA21 couldn't see anything in the designs for new style "flood basements" that provide protection from storm surge by bulwarking.
Given that the North Poole area is within the 2 metre above sea level contour lines for the town, how will this new development fare ?
Why is sea level rise so invisible to planners in Poole ? Someone in Poole Agenda 21 has suggested the Developers of Poole could follow the example of those inventive folks over the North Sea Channel in Holland and go for amphibious housing in areas such as Hamworthy.
Amphibious houses either float up and down according to water levels, or are designed to withstand serious flooding, with design measures such as having all electrical wiring and points halfway up the walls :-
The railway station has suffered from being "on the curve", but a new plan to re-locate it on a straight section of the track and add new facilities (including the inevitable car parking) will just add to the risk of the train station being flooded, as the straight section of track is below 2 metres above current sea level.
The Quay, where many a fishing trip has started, where people take pleasure boats to tourist destinations such as Brownsea Island (Baden Powell, Be Prepared), and have many a boozy night outside the public houses that line the waterfront.
A sea level rise of 1 metre will completely compromise the safe public use of this area of town.
And if sea levels rise anywhere near a metre in the near future, and dredging of the Main Channel is curtailed, you can forget about living on Sandbanks.
It will be cut off from the mainland, and properties worth hundreds of millions of pounds will be storm-damaged on a regular basis, even be permanently flooded on the ground floor.
There is cause for optimism. Most of the plans for the re-development of Poole are still at the drawing board stage. There could be changes made.
For example, it's not too late to get the "Twin Sails" bridge re-designed to incorporate tidal turbines underneath it to generate power, and get a bicycle lane on top. But who with any planning influence is going to propose it ?
People still seem oblivious of changes going on around them, even though they are widely reported in the general media.
Town planning and renovation developments are still based on standards and guidance that are over ten years' old in some cases.
New Government-led frameworks on, for example, Sustainable Development, have not yet been implemented down to planning level. A lot of new codes are "voluntary".
The story of the drowning of Poole could be repeated hundreds of times over around the British Isles.
It's time to wake up.
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