The value of hazard zone mapping: Water Authority 'Section 24(5) surveys' in England and Wales

Successful problem-solving is usually based upon a sound knowledge of the problem. Where the problem is a hazard, the impossibility of a 'solution' in terms of complete prevention is well known but proper problem assessment is still required. Detailed hazard zone mapping can be a valuable aid to planning to reduce hazards and to avoid disasters. A map is a powerful visual medium for conveying information where awareness of disaster proneness amongst public officials and others is limited. However, a map is also a comparatively limited medium for analysing risks and is most useful to planners if combined with detailed supporting documentation. Maps and related documents are particularly useful if they provide a complete assessment of risk, are periodically updated, are integrated with the planning process and are systematically compiled and presented at an appropriate scale. Map scale often presents problems. The larger the scale, the less limited the map will be in recording useful detail but updating becomes more costly and therefore less likely. The Water Authorities Section 24(5) surveys are remarkably detailed and are valuable planning and research materials. They demonstrate the widespread nature of flooding problems and the need for decades of flood alleviation and drainage expenditure in England and Wales. Further standardisation of content and presentation could enhance the value of the survey reports but their value depends ultimately upon regular and systematic updating.