The November 2009 floods in Cumbria, north-west England: an analysis of the rainfall and river flows in two catchments

In November 2009, prolonged heavy rainfall brought extensive flooding to many parts of the western UK and Ireland, with the worst flooding concentrated in west Cumbria in north-west England. For two of the most affected catchments, the Derwent and the Leven, this paper presents an analysis of the rainfall, river flows and lake levels, including a comparison with other recent flood events. Spatial analysis of rainfall illustrates that the return period of flood peaks in these catchments is influenced not just by the return period of the causative catchment average rainfall, but also by its spatial distribution and intensity – particularly in a catchment less dominated by a large lake system. A combined assessment of rarity in terms of both rainfall and flows demonstrates the extreme nature of the November 2009 event and the complexity of the re-lationship between the estimated return periods of catchment average rainfall and peak flow.