The causes of the 2009 flood in the River Derwent, Cumbria

Use the following presentation to help you complete annotation onto the outline diagram in your notes. Physical causes are shown in blue,

human causes in red. Colour code your annotation accordingly.

The causes of the 2009 flood in the River Derwent, Cumbria

NorthWorkington

Cockermouth

Cumbrian Hills

R. DerwentR. Cocker

Keswick

The various locations mentioned in your notes.

NorthWorkington

Cockermouth

Cumbrian Hills

R. DerwentR. Cocker

Keswick

1. Physical Causes

North

1. Warm, very moist air, blowing from the SW, meets Cumbrian mountains & is forced to rise.

North

2. It cools & condenses, producing cloud & rain – a lot of rain.

In fact, 400mm of rain falls, breaking the previous record for highest 24 hour total in the UK of 316mm.

North

3. There is too much rain to infiltrate into the ground, and so it flows by overland flow to the streams, causing their discharge to rise very quickly.

These feed quickly into the main rivers, the Derwent & the Cocker, increasing their discharge.

North

These feed quickly into the main rivers, the Derwent & the Cocker, increasing their discharge.

3. There is too much rain to infiltrate into the ground, and so it flows by overland flow to the streams, causing their discharge to rise very quickly.

Example of the extreme overland flow produced by the record-breaking heavy rain that fell.

Example of the extreme overland flow produced by the record-breaking heavy rain that fell.

North

This water then flows down towards Workington, causing flooding there.

4. At the confluence of the R. Derwent and R. Cocker, their discharges combine.

NorthWorkington

Cockermouth

Cumbrian Hills

R. DerwentR. Cocker

Keswick

2. Human Causes

1. Urbanisation – the towns such as Cockermouth and Keswick have increased the amount of impermeable surfaces which means that the

water gets to the river more quickly, increasing discharge.

Notice how the water flows over the surface of the road. Similar effects occurred in urban areas as the water could not infiltrate into the tarmac.

Notice how the water flows over the surface of the road. Similar effects occurred in urban areas as the water could not infiltrate into the tarmac.

2. Blocked sewers – inadequate sewer capacity and blockages caused sewers to back up and caused

flooding incidents, for example in Elliot Park, Keswick.