Like the hurricane of 1987, the floods seen in the UK in recent years won’t easily be forgotten. While the floods of winter 2013/2014 highlighted how inadequate the prevention and protection plans had been, the floods of winter 2015/2016 were considered to be the most extreme since records began, back in 1910.
With climate change now a recognised and accepted phenomenon, it’s reasonable to expect more extreme weather in the future. Now more than ever, flood data mapping is essential in the process of pre-site planning, not just for the environmental risk but also the effect it will have on the economic and social aspects of the area.
Lessons learned from the last few winters have helped the government develop plans for new flood defences around England. Over £2 billion is being invested in separate projects to protect homes and businesses over the next five years, targeting flood zones identified by new flood modelling techniques. Another new development is that the Environment Agency’s flood risk modelling will be linked with extreme weather forecasts from the Met Office so that new flood risk assessments can be provided.
The flood zone data provided by the Environment Agency is just one of the essential elements that go into a comprehensive flood risk assessment. Flood maps from Promap are a good example of how a variety of types of flood data can be pulled together and superimposed on OS maps. For example, the Environmental Agency not only provides current flood zone risk but has a historical flood data going back to 1947, and in some areas as far back as the 18th century.
In addition to the EA flood data, flood zone maps provided by the British Geological Survey highlight areas that are most susceptible to floods based on geological data, ignoring the effect any man-made constructions might have. For example, the BGS will identify inland flood zones from silt and mud deposits from previous floods, and coastal flood zones from evidence of where the land has previously been under seawater.
While flooding from rivers and the sea is well known, groundwater flooding can have a greater economic and social impact. Since it rises from underground, it has nowhere to go, and so it takes longer to disappear. The British Geological Survey also provides a groundwater flooding susceptibility map to help assess this risk.
Together with the National Flood Risk Assessment maps, which give a national overview of areas likely to be flooded if flood defences are breached, these flood maps provide a range of different risk scenarios that need to be considered during any feasibility study or analysis.
Planning for the Future
Flood risk maps are an essential part of future planning, whether it’s for existing building developments or new ones. As a result of the recent flooding events, there’s been a greater focus on understanding the extent and severity of the risks, as well as improving the technology with which to predict them, so that action can be taken in good time.