A better representation of risks and opportunities in the Thames Estuary
Time to make decisions
If nothing is done, London and the surrounding areas will experience serious flooding within a few decades. The current high water defences like the Greenwich Barrier are no longer adequate. In the Thames Estuary TE2100 project the British are considering short and long term measures. The technical research has been done; all the stakeholders have been or will be informed about it. It is time to make decisions. Royal Haskoning is advising the project management and the decision makers about the impact of (combinations of) alternatives.
TE2100 is developing a flood risk management plan for London and the Thames Estuary. This plan is based on risks such as outdated water barriers and takes all interests into account; it is sustainable and asks stakeholders to play an active part in the consultations. It also entails climate change and various socio-economic scenarios for the next hundred years. Marnix de Vriend, senior consultant at Royal Haskoning, has devised ‘Opportunity Mapping’, a system of risk analysis that can be used to weigh up all the aspects. ‘Solutions and research can be presented together in a manner accessible to everyone. The cost-benefit analysis for the Thames Estuary, and for the entire river basin if necessary, is done with pictograms. By giving them a colour you can see at a glance which scenarios to consider and why. Green: no problem, go for it. Orange: doubtful, capable of improvement. Pink/red: poor, uncertain, (too) complex.’
Conditions
‘The main condition for deciding on schemes like these is that the data used are correct and properly applied, and that all facets are taken into account. A lot of conversations with experts and literature research go into it beforehand. It is also crucial to know about local circumstances and impact perceptions, which are sometimes culture-specific, in order to be able to interpret social and aesthetic effects. For example, you have to realize that economic risks are rated differently in the United Kingdom. If the costs of the annual management of a water barrier are twenty times higher than the value of the land and buildings, the government would in principle opt for evacuation.’ Opportunity Mapping can also be used in decision making in the Netherlands. This has already been done in a high water strategy for the Arnhem-Nijmegen Hub. But it can also be employed in places like New Orleans and Jakarta and in cities where there are similar problems, such as Paris, Hamburg, and Lisbon.
Water in or water out?
According to De Vriend it seems that the most suitable scenario for the Thames is to move with the river wherever possible. ‘Look at the elasticity of the entire system, not just at the river in the city, and primarily get the water into the estuary. The east side offers possibilities which could mean that expensive modification works in London itself can be postponed and possibly even avoided. Transform agricultural land into nature reserves. Give natural processes free rein. Beautiful (natural) areas will be created and as a result the value of property will rise and there will be opportunities for recreational facilities. But put hospitals and schools in dry places. There will come a point when just continuing to raise barriers no longer works. Look ahead, but leave scope for good risk management. And accept that some processes cannot be stopped. If a village is on the edge of an eroding cliff that is in danger of falling into the sea you can try to stop this happening, but the costs are enormous. It’s a better idea to move or buy a boat.’
Contact: Marnix de Vriend
+31 (0)24 3284 176
m.devriend@royalhaskoning.com
