In recent years in the UK there have been a number of occasions when flooding has hit the headlines. Television pictures of emergency services using boats to rescue people or home owners mopping up after dirty flood water has swept through their houses seem to have become more common.

Coupled with an increasing public awareness of the dangers of flooding has come an increased recognition that often the flooding is linked to human activities. Example of this are houses built in areas prone to flooding and upstream flood defences increasing flood damage downstream by reducing the buffering effect provide by flood storage. There is also a possibility that climate changes are increasing the frequency of extreme weather.

As a result of this, much more scrutiny is being given to flooding. Whilst the Flood Estimation Handbook published by the Centre for Ecology and Hydrology gives general guidelines, local conditions and the type and quantity of available data mean that it is often necessary to examine each case in detail. We give below two examples of how WRA has tackled specific projects.

Killingholme power station is located 1 km from the Humber estuary but the pumping station for cooling water is only 50 m from the coastal flood wall. As part of a review of the power station undertaken after a change of ownership, WRA was asked to give expert advice on flood risk. This involved determining the relative risk of river and coastal flooding. In the case of coastal flooding data on maximum flood levels were collected, including a few levels from the 19th century, and these were analysed to assess the frequency of flooding which might occur at the power station and the pumping station.

This project was related flooding on a "brown field" development site. During the planning process a major flood occurred which caused flooding to adjoining properties. There were concerns that this flood indicated that development of the site would be inadvisable. WRA obtained data on the flood, including a survey of flood levels from marks still visible at the site and flow and level data from gauging stations upstream and downstream of the site. Analysis of these data suggested that statistically the flood had  rate of return well in excess of that required for planning consent.

Killingholme power station

Evidence of flood level