§ Richard OttawayTo ask the Secretary of State for Environment, Ford and Rural Affairs what circumstances have led to an increase in use of the Thames Barrier; and whether this has been due to long-term changes in national phenomena. [166014]
§ Mr. MorleyThe Thames Barrier is closed to protect London from extreme high tidal waters generated by 'storm surge' in the North Sea and to provide storage for extreme freshwater flows, which would threaten West London, and combinations of these phenomena.
The Thames Barrier has been closed on 67 occasions in the last 10 years during the winter flood seasons.
Mean sea level and extreme tidal waters are expected to increase as the south east of England continues to fall relative to sea level. This was factored into the design of the barrier and closures for extreme high tides are within those expected when the barrier began operation. Closures due to extreme freshwater flows are harder to predict, but the winters of 2000–01 and 2002–03 were two of the wettest on record.
It is too early to say whether these trends are anthropogenically driven or part of the natural variance. It is also possible that extreme freshwater flows have been affected by changes in the land use of the Thames catchment.
Sea level rise, tidal surge extremes, tidal propagation, wave driven storminess, freshwater flows and combinations of these phenomena are all expected to be affected by climate change. The uncertainty for the future flood regime is high and creates a challenge for the long term financial and environmental planning in the Thames Estuary.
The Environment Agency are aware of these challenges and are already two years into TE2100, a project that will deliver by 2008–09 a flood risk management plan for the next 100 years. As well as the continued use of the Barrier, a number of flood risk management measures are also being considered.