Storm Desmond

The Lake District has experienced a series of recent extreme floods, 2005, 2009 and 2015, with each of these associated with warm, moist south-westerly airstreams and with deep Atlantic depressions tracking north-eastwards across the UK. During Storm Desmond from 4 to 6 December 2015, the northwest of England was hit by exceptional and record-breaking precipitation.

The event set new records for 24 hour rainfall totals e.g. Honister Pass 341.4 mm and 322.6 mm at Thirlmere, with rainfall frequency models estimating a local return period of about 1300 years, a 0.08% annual probability. Flood levels for the River Derwent at Portinscale evidence a high magnitude event (365 m3 s-1), impacting catastrophically on the population and infrastructure.

Our long-term monitoring at Brotherswater shows that these floods delivered the coarsest sediments in our grain size record, which extends back ~1500 years.