What lies beneath

NEW study has found that examining the layers of sediment beneath Cumbrian lakes could help us to be more prepared for future flooding. Currently, we rely on precipitation and river-flow records to gauge flood risk. However, our rainfall data only goes back a couple of hundred years or so in a handful of locations, with measurements of river flows going back only decades.

This investigation, funded by UK Natural Environment Research Council’s Urgency Programme and carried out by a team from Liverpool, Southampton, Durham and King’s College London universities, tells a story of the area’s flood history dating back as far as 1400 and beyond, capturing a far fuller range of possibilities in flood frequency and magnitude.

Fortunately, the Lake District’s history of metal mining has left its mark at the bottom of the four lakes involved—buttermere, Bassenthwaite, Ullswater (above) and Brotherswater—with traces

Aof copper, lead, zinc and even barytes acting as useful markers, reflecting the periods when particular industries were dominant and thus showing exactly how often floods have occurred. In Bassenthwaite, for example, two-thirds of the biggest floods in the 600-year sediment record have occurred in the past 20 years.

This information could be all the more vital, as the National Flood Resilience Review—published this month—which anticipates 20%–30% more extreme downpours than before, calls for greater use of ‘information from historic sources (for example, newspaper reports, photographs, and sediments)’.

The Government has committed £12.5 million to increase and improve temporary flood defences and Bob Ward of the Grantham Research Institute on Climate Change says that it ‘deserves credit for admitting that Ministers have previously misunderstood and significantly underestimated the probability of flooding’.