River Eden, Carlisle Cumbria Flashcards
Location
- The river Eden is located in the city of Carlisle, Cumbria North west England
- Population of 71,000 people
- Carlisle is situated on a flood plain of the river Eden
- three rivers meet in the city and therefore there is an potential of flooding
General facts
- the river Eden is 130km long, flowing north to south
- the geology which dominates the river Eden is primarily limestone, which is permeable and slate which is impermeable
- the catchment is made up of the river Eden, Eamont, petteril, Irthing and caldew and several other rivers as well as smaller rivers and streams therefore providing it with a high drainage density.
Physical causes of flooding
The river Edens catchment is 2400km3 with an annual average precipitation of 2800mm in upper Eden and 760mm in Carlisle
- however in late December 2004 there was 2 weeks of heavy continuous rainfall followed by extreme rainfall between the 6th and 8th of January - 15% average annual rainfall fell in 36 hours - 200mm of rainfall was recorded - equivalent to 4 months of rain.
- the rain fell on saturated ground as there was a surplus in the ground water stores and the water table was at the surface and therefore was unable to infiltrate therefore resulting in increased surface runoff, reduced lag time and an increased discharge
- geology and soils - catchment includes impermeable skiddaw slate and thin soils in the upland resulting in increased surface runoff
- Carlisle is located at the confluence of the river Eden, Petteril and Caldew - therefore there is a high drainage density and an increased potential of flooding
- steep gradient in the upper Eden, providing the water with high potential energy and a higher velocity - increased likelihood of flooding.
Human causes of flooding:
URBANISATION - Carlisle is a large built up area consisting of impermeable concrete and tarmac surfaces - little vegetation to act as interception
- little soil for infiltration of rainfall - increased surface runoff - reduced lag time, increased discharge
DRAINS & SEWAGE SYSTEMS - result in the water reaching the river within a shorter period of time, increasing discharge
- however the problem was exacerbated by the drains becoming blocked by debris - increasing the scale of the flood risk - 25% of the flooding problems were associated with overflowing drains
INADEQUATE HARD MANAGEMENT TECHNIQUES - the defences were not able to withstand 1 in 170 year event
- flood levels in some areas ended up 1 metre higher than the defences constructed after the last floods in 1968
Social impacts
- 3 people died in the floods
- over 3000 people were made homeless for up to a year and thousands of personal possessions were damaged - living in temporary accommodation disrupted lives in many ways - e.g. travel arrangements, many were separated from their community network and friends and they had problems receiving post
- children lost out on education as schools had to shut temporarily whilst the flood damage was sorted
Economic impacts of the flooding:
- 1,600 homes flooded at an estimated cost of £100 million
- 350 businesses had to shut down as there was no electricity, telephone service or transport
- all shops closed - loss of trade
Environmental impacts
- flooding increased river bank erosion
- rivers were polluted with rubbish and sewage
- thousands of trees felling in the winds
management
The environment agency spent £12 million on a project to improve defences along the river Eden and Petteril:
- embankment along the two rivers were rebuilt to make them higher and wider new flood walls were built
- promoting awareness of flooding so that organisations, communities and individuals are aware of the risk and prepared in case they need to take action
- flood risk mapping - understanding where flooding is likely to occur
- operation of a flood line and warning services to over 2,000 properties
