River Derwent: Causes Of Flooding

Question 1

Background information [3]

Answer 1

1. In March 1999, people living near the River Derwent in Yorkshire experienced its worst flooding in 70 years.
2. Places nearby were flooded up to 1.5 metres deep.
3. Two main roads had to be closed.

Question 2

Heavy rainfall

Answer 2

1. Between 28 February and 11 March, over 250 mm of rain fell on the North York Moors, which usually falls over 3 or 4 months
2. There was a lack of infiltration as rainfall fell to ground that was almost completely saturated from previous rainfall

Question 3

Snow melt

Answer 3

Due to the time of year, snow melt also contributed to the river discharge from the North York Moors source region

Question 4

Extraction of peat

Answer 4

The extraction of peat from the source region reduced the soil’s storage capacity there, thus increasing discharge

Question 5

Urbanisation

Answer 5

Areas of the floodplain were being urbanised, such as the new estate built at Malton. This reduced infiltration because the ground was impermeable and hence increased surface run-off.

Question 6

List the four main causes of the River Derwent flood in March 1999.

Answer 6

1. Heavy rainfall
2. Snow melt
3. Extraction of peat
4. Urbanisation