In the wake of a number of extreme rainfall events in the last few years, such as Storm Desmond wreaking havoc in the North West in December 2015 and the conveyor belt of storms that hit the UK during the winter of 2013-2014, an innovative new method has been developed to assess the likelihood of such events occurring in the future. Quantifying risks of extreme events using older data is no longer relevant, says the Met Office, because our climate has changed over the past 100 years.
The Met Office turned to their new computer to simulate huge numbers of variations in the weather in winter based on current climate patterns. They then analysed the data in order to understand more about possible extreme weather events, which allowed them to predict a level of risk for a UK region experiencing record-breaking rainfall.
Dr. Vikki Thompson, who is the lead author of the report, explained that the computer had generated 100 times more data than they could possibly glean from previously observed records. She said that record rainfall could happen at any time, with one of the UK regions likely to experience record monthly rainfall in the next few years.
With unprecedented levels of rainfall come unprecedented levels of flooding. One area that was badly hit during the storms of 2013-2014 was Somerset. The Somerset Levels, land that is artificially drained for agriculture and is prone to flooding, saw 17,000 acres under water that winter, with entire villages cut off or evacuated. The flooding was so severe that high-volume water pumps were sent from the Netherlands to help clear the water, and the army was called in to help. Lessons were learned about the importance of the regular dredging of rivers, a practice that had been paused in the area since the ’90s.
The extreme rainfall events that have hit the UK have given flood risk a higher profile, and greater attention is being given to assessing and preventing flooding events. It’s standard practice to make flood risk assessments as part of any preparation for the approval of a new land development, however great or small. Maps providing information about flood risks can be produced by map providers such as http://www.promap.co.uk/maps-and-data/flood-data and other sources that specialise in producing maps that need to conform to specific planning requirements.
These maps can show different flood zones based on risk, source protection zones that detail the risk of ground-water source contamination, British Geological Survey data on flooding risks and more. They’re used to help identify how susceptible site is likely to flooding as well as identify places where better defences may be needed.
With our climate continuing to change, and with indications showing that rainfall events of the magnitude we’ve seen in recent years are likely to happen more frequently, flood risk assessments and improving flood defences have become a greater priority.