Saturday, April 16, 2011

Guest Post: Relocating London

This is a guest post from Douglas Coker, and absolutely rock solid Green in Enfield. A great start to the discussion on what climate change means for our cities.

London is under threat. Key parts of central London are built on a flood plain. A stretch of the South Bank, including part of Southwark, and Docklands are examples. The extent and timescale of the threat are difficult to predict exactly but at some point in the future low lying parts of London run an increasing risk of being flooded.

The North Sea flood of 1953 in which thousands of lives were lost in the Low Countries and Suffolk and Essex was a warning. This prompted the building of the Thames Barrier during the 1970s. It became operational in 1982 and has been used with increased frequency over subsequent years. Currently the Barrier protects billions of pounds of infrastructure including buildings, parts of the underground network and electricity distribution facilities. Some experts expect it to be fit-for-purpose until 2030, others say 2060 or later.

Now global warming and rising sea levels are increasing the threat. Add a repeat of the 1953 event with a storm surge bringing huge volumes of water up the Thames and the Barrier failing. In addition consider this. The Thames catchment area extends as far as Basingstoke, Swindon, Banbury and Luton. Imagine exceptionally heavy rainfall in this area and the subsequent large volumes of water travelling downriver to London just as the storm surge arrives from the sea. You don’t want to be strolling along the South Bank or travelling in a tube under the Thames when this happens! OK enough scary stuff. What do we do about this?

Big cities need big infrastructure and these projects should last for hundreds of years. Take Bazalgette’s sewer system. The combination of the Thames being used as an open sewer and an unusually hot summer in 1858 gave rise to the Great Stink so awful that members of the House of Commons considered relocating upstream to Hampton Court. Joseph Bazalgette was commissioned to build a substantial London sewer system to carry the offending effluent down river. We still depend on this today in part due to Bazalgette’s deployment of the precautionary principle. He doubled the size of the sewer tunnels to future proof them. What an example he set. His sewers will have a lifetime measured in hundreds of years.

Bazalgette could not have been expected to know about global warming back in the 1850s. But we are all too aware now. Why are we continuing to construct large civil engineering projects, including infrastructure and buildings in vulnerable areas? I question whether we should be building, the Thames Gateway project, the Olympic Games site, Crossrail and the Super Sewer. Huge amount of concrete and steel will go into these projects with all their attendant CO2 emissions and all or part of these projects are in areas of London increasingly vulnerable to flooding. Projects which should last, not mere tens of years, but hundreds of years should surely not be built in areas which within 50 or maybe 100 years will be inundated with water.

The London Thames Gateway development has the insurance industry worried. They are reluctant to insure homes and shops unless extra measures are taken to protect against flooding. Maybe the buildings should be built on stilts! The Olympic Games site is in the Lea Valley an area which has experienced flooding in recent decades. Measures have been put in place to prevent flooding of the site but will they prove to be adequate?

Crossrail is intended to transport commuters at high speed from Maidenhead in the west to Stratford and Canary Wharf and other places in the east. Putting aside the question of whether this is a good idea in principle this huge civil engineering project will run through and to parts of London vulnerable to flooding at some point in the future. Whether in tunnels or on the surface how is this to be protected?

Finally the Super Sewer, or more correctly the Thames Tunnel, is intended to extend for 20 miles from west to east to help prevent sewage entering the Thames when we have increasingly heavy rain (caused by climate change) overwhelming the Victorian sewage system (built by Bazalgette). All this diverted sewage is intended to end up in a sewage works at Beckton which, situated on the north bank of the Thames estuary, is right in the firing line of a surge of flood water heading up river for London! Surely a better plan is to remove all impervious surfaces in front gardens, car parks and similar places, install soak-aways and encourage the maximum use of water-butts and other storage containers before boring a huge tunnel under the Thames.

Global warming and climate change have received less attention than warranted as we experience an economic depression. But let’s not forget the economy is a sub-set of the environment and business-as-usual thinking needs to be challenged. We should not be pursuing developments which take little if any account of the prospect of London and the Thames estuary flooding. We need a new planning regime which sets strict criteria informed by a proper understanding of the risks to London from a rise in sea-level and large volumes of water. We need to plan to give places back to the river and sea as they are ultimately not protectable.

Relocate London? We need a plan for relocating vulnerable parts of London on a timescale which will prevent foreseeable disasters.


Natalie Bennett said...

As the current situation with the M1 shows, thinking "what could go wrong" isn't currently a common practice, but it clearly should be!

David Flint said...

Ok Douglas - but what degree of warming should we plan for? For some a new barrier might be the best choice. For others we'll lose the central parts of London and need much more radical measures.

David Flint said...

OK Douglas but what degree of warming should we plan for - and by when? For small changes a new barrier might be best. Large changes will flood central London and require much more radical change.

Jim Jepps said...

I have a technical question.

When we talk about flooding are we generally talking about increasing flood risks and new areas at risk off floodiing or, because of rising sea levels, are we talking about permanent or semi-permanent flooding of areas?