HC Deb 19 April 2004 vol 420 cc153-5W
Norman Baker

To ask the Secretary of State for Environment, Food and Rural Ai fairs if she will list the occasions on which the Thames Barrier has been closed in each of the last 10 years; and what estimate she has made of the number of occasions when it will be closed in (a) 2010, (b) 2020, (c) 2050 and (d) 2100. [165740]

Mr. Morley

The Thames Barrier is closed to protect London from high water levels in the River Thames resulting from tidal surge conditions in combination with high freshwater flows in the river following rainfall over the Thames catchment. The Barrier closures may be characterised as predominantly tidal-influenced (T) or predominantly rainfall/fluvial-influenced (F). Over the last 10 years the Thames Barrier has been closed to prevent flooding during the winter flood season (generally October to April) on 67 occasions as follows:

  • 1994–95:4 (T = 2, F = 2)
  • 1995–96: 4 (T = 4, F = 0)
  • 1996–97: 1 (T = 1, F = 0)
  • 1997–98: 1 (T = 1, F = 0)
  • 1998–99: 2 (T = 2, F = 0)
  • 1999–2000: 6 (T = 3, F = 3)
  • 2000–01: 24 (T= 16, F= 8)
  • 2001–02: 4 (T= 3,F = 1)
  • 2002–03: 20 (T = 8, F =12)
  • 2003–04: 1 (T = 1, F = 0)

Forecasting the frequency of closure of the Thames Barrier in the future depends on two principal factors:

  1. (a) The impacts of climate change on sea and river levels—based on the climate change scenarios currently available; and
  2. (b) The extent to which these levels may be reduced by other flood risk management measures used within the Thames Estuary in conjunction with operation of the Thames Barrier.

Depending on the balance of factors described above, The Environment Agency's early studies indicate estimated frequency of closures as follows:

  • 2010: 10–20 closures per year
  • 2020: 20–35 closures per year
  • 2050: 6*–75 closures per year
  • 2100: 30*–325 closures per year

The lower figure for each year indicates the best predicted outcome based on lowest climate change scenario impacts and maximum use of flood management mitigation measures implemented from 2030 (shown by *). The higher figure for each year indicates the worst potential outcome based on maximum climate change predicted impacts with no additional flood management mitigation measures implemented from 2030.

The Environment Agency is currently planning for the future of flood risk management within the Thames Estuary and has for this purpose established a project called Thames Estuary 2100 based at the Thames Barrier. The purpose of the project is to produce a flood risk management plan for the tidal part of the Thames Estuary covering the next 100 years.

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