With hurricanes and storms around the world making the headlines recently, the issue of global warming and climate change has a high profile. We have already been seeing record-breaking floods in the UK, and more is being spent on flood defences and contingency plans in the face of a serious event.
In the winter of 2013-2014, the conveyer belt of storms that battered the British Isles left large areas of land underwater for weeks, notably the Somerset Levels. Villages in this area were cut off for weeks, while farms and local business were significantly impacted. Fears for the long-term effect on the local economy include the impact on the value of property and land and the fertility of the fields that were left flooded for months.
With the increasing risk of storms and flooding, more has needed to be done to counter the problem. In the case of the Somerset Levels, a 20-year plan was put in place. This has already started with the dredging of two rivers, including bank repairs, and the assessment of further sites that may need the same treatment. Dredging is not a one-off solution, however; instead, it needs to be a continuous process to prevent rivers silting up again. Another solution as part of the plan is a Thames Barrier-style tidal barrier to be situated north of Bridgwater, which would cost upwards of £32m.
What about your area? How will you know whether your locality is likely to suffer from flooding?
Fortunately, there are some quick and easy ways to estimate the flood risk in your area. The Environment Agency has a new service whereby you can simply key in your postcode and it will tell you straight away whether you are in or near a flood risk area. The service provides information and advice on what to do in the event of a predicted flood and how to protect your property. It also provides maps and information on where the expected flood areas are likely to be and their cause, such as seawater, surface water or reservoir flooding. This is useful when preparing for an imminent storm event or for long-term planning, such as insuring your business and property.
If you are planning to build on land and need information about long-term flooding in the future, maps containing detailed information drawn from numerous sources are required. This data is also needed as part of the planning application process. Map data providers such as Flood Maps | UK Flood Map | Floodplain Maps | UK Flood Areas can provide detailed information on flood data, which is ideal when submitting planning applications.
With a full suite of maps showing data from different sources, these providers can deliver a full picture of long-term and short-term flood risk; for example, the Environment Agency’s Flood Map can identify risk areas based on the risk of being flooded by the sea, by rivers, and by level of frequency. It can also provide a separate map showing the increased extent of flooding based on what might happen in an extreme event.
The National Flood Risk Assessment provides maps of flood risk at a national level, calculating areas likely to be flooded in an extreme event, including the risk of flood defences being breached.
Source protection zones are important when planning, as groundwater sources such as boreholes and springs can be at risk of contamination depending on the purpose of any new-build planned nearby.
Historical flood event data maps provide a good indicator of past flood events. Most records go back to 1947, with a few going back as far as the 18th century. Not only are these good predictors but also they show how effective flood defences that have been subsequently installed have been.
Since groundwater flooding can last much longer than other types of flooding, maps such as the British Geological Survey’s groundwater flooding maps are invaluable. Intense storms in areas in which groundwater levels are high can have a heavy impact on the local economies, since it can take months to subside. The data providing groundwater flooding susceptibility is very useful when deciding how land will be used and when making planning application decisions.
In addition to these data sources, there is the RMS pluvial flood data. This uses land height and rain prediction, amongst numerous other environmental factors, to indicate the risk of river flooding and groundwater flooding, which is a relatively new and very welcome tool for Great Britain.