rivers pt 2

Case Study of Recent Flooding in either a MEDC or a LEDC and Its Effects on People, Property .and the Land

Somerset Levels, England. January 2014

Physical causes of flooding rainfall - more rainfall

Three times more rainfall than usual over the drainage basin in December 2013 and January 2014.

• Over 180mm of rainfall fell in January 2014

• Jet stream over South of England - the jet stream's location was further south than usual

• Jet stream brought 13 depressions in from the Atlantic Ocean

• Soils already saturated wet weather since October 2013, infiltration stopped. Water lay on the surface of the land and moved by surface runoff to the river.

Physical causes of tidal Range and Siltation of Channel

• Land low lying (less than 8m above sea level) + very flat

• River Parrett and River Tome slow flowing affected by tides

• Area has second highest tidal range in the world with sea water flowing 18 miles inland twice a day

• High tide and strong westerly winds caused river water to back up and overtop the channel rather than flow into the Bristol Channel

• Tidal water carries a lot of silt, some of which is deposited when the seawater flows inland during each high tide - this gradually reduces the ability of the channel to hold river water.

Human causes to flooding land drainage

Land Drainage by Monks in Middle Ages

• Marshes were drained to create land for farming

• Drainage networks divert water to the river channel through below-surface pipes

• Soil stores and groundwater stores were reduced due to drainage which lowered the height of the surrounding land.

• Pumps keep the land flood free but could not be turned on due to the extreme height of the water

Change. In Vegetation cover

• Grassland (permanent vegetation cover) has been replaced with cereal crops.

• At end of summer when crops are harvested, the land is left bare - this changes the stores and transfers of water in the Somerset Levels

• There is less interception, less infiltration and less water being stored in the soil stores and groundwater stores. When soils are bare surface runoff brings a huge volume of water the river over a short time.

Lack of river maintenance

• River had not been dredged of silt since 1995 which decreased the capacity of the river channel.

• Some argue that the authorities deliberately allowed the Somerset Levels to flood to prevent flooding of larger settlements downstream.

Impact on people

• No lives were lost

• 600 homes were flooded with foul sewage laded water(175 under water for several weeks)

• •Moorland - 120 families had to live in rented housing, including caravans - strain in family relations due to cramped conditions. 30 of these families were out of their homes for around 12 months.

• Many families left the Somerset Levels due to fear of another flood event

• The impact on public mental health was "devastating"

• Challenge to get homes insured

Impact on property

• Homes, businesses, farms and a wood flooring factory were flooded

• Properties suffered damage to skirting boards, kitchen cupboards and were flooded with sewage-laden water

• Many properties left empty e.g. Moorland village - 6 months for properties to dry out, insurers to assess damage and builders to fix their homes

• People and farm animals were evacuated

• Cost to farming - £19 million

• Reports of thefts - 900litres of oil stolen from a Westonzoyland, quad bikes and heating oil were stolen from people's homes

• £2 million - cost to local council for clean-up

• Cost of insuring properties increased

• Value of properties fell to 2/3 that of the pre-flood valuation

• The impact on residential property was up to £20 million

Impact on Land

• Almost 7000 hectares of farmland flooded (some under water for several months)

• Following the recession of floodwaters, a significant amount of debris covered the land.

• Newly planted grasslands were destroyed or badly damaged.

• Increase in the number of ducks.

• Decrease in the number of golden plover and teal.

• For some farms, it took two years for productivity of the soil to return to normal.