Carlisle Case Study: What was the hydrology of the January 2005 flood?
Carlisle Flooding © Prestwood
The January 2005 flood was a major event. Rainfall was very high for the period 6 to 8 January, during which two months' worth of rainfall were released in 24 hours. However, it followed a month of high rainfall in the Carlisle area, so the ground was saturated and would no longer allow water to infiltrate, and surface run-off was excessive. The result was rapidly rising water levels in a number of rivers including the Eden.
During the flood, the flows in rivers such as the Eden, Kent and Derwent were the highest on record. The flood peaked in the upper parts of the Eden and Derwent catchments in the early hours of 8 January. The River Kent in Kendal peaked at a similar time.
In Carlisle, the River Eden peaked at an estimated 1520 m3/s at the Sheepmount Gauging Station at 1430hrs on 8 January. This flow has a return period in the order of 175 to 200 years (0.5%). The previous highest recorded flow on the River Eden at Carlisle was 1,075 cusecs in 1987.
The first warning of flooding in Carlisle by the Environment Agency was at 17:18 on 7 January and further warnings were given in the early hours of 8 January. The Agency did not predict that the Carlisle flood defences would be breached but the exceptional river flows made it hard to predict the height of the water. A feature of the event was that flooding was often initially caused by surface water flows as the local drainage networks were overwhelmed.
- 67% of the flooding resulted from rivers and watercourses
- 25% of flooding was caused by surface water
- 8% was due to flooding from sewerage and infrastructure
Many lakes and reservoirs reached their highest recorded level. Haweswater Reservoir did not start to spill until after the flow peaked downstream in the River Lowther, so it was a factor in reducing the magnitude of the peak.
The hydrograph to the right shows the sequence of flooding for the River Eden between 1 and 12 January.
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