UK case study EQ2- Mid latitude depression and relief rainfall Flashcards
(23 cards)
what were the physical causes of the 2015 storm Desmond and Cumbrian floods?
Low pressure and midlatitude depressions- 3 months of rainfall (mainly frontal and orographic/relief)
Antecedent conditions- high topography, downhill slopes caused fast water transportation downhill- short lagtime, ALREAdY SATURATED SOILS
Jet stream- fast flowing currents of air, over 200mph, polar and subtropical sharper trough- deeper lower pressure systems at surface- storms
human causes
1) land use change- urbanisation, building of homes, roads and other infrastructure on natural flood zones (like parts of Carlisle and Keswick) reduced the lands ability to soak up floodwaters and put more people at risk.
Increasing number of homes being built on Greenfield sites - impermeable surfaces
deforestation- reduces interception, few trees-more water enters rivers and streams
2) Mismanagement of rivers- river straightening in some areas to improve drainage and land use- made water flow faster downstream- increasing flood risk in towns.
- some argue that dredging and levees (rater than natural flood management such as restoring wetlands) made rivers less able to cope (resilience) with flood events.
3) Anthropogenic-driven climate change- indirect cause, increased the intensity of storm Desmond. Warmer air holds more moisture, so storms bring heavier rainfall- and scientists have found that climate change made such heavy rainfall about 40% more likely.
How much did anthropogenic climate change increase chance of heavy rainfall
By 40% (storm Desmond)
What was storm Desmond?
An extratropical cyclone- Desmond directed a plume of moist air (atmospheric river) which brought record amounts of rainfall to upland areas (such as Cumbria) and subsequent major floods.
in Lancashire and Cumbria, how many homes across the north of England were left without power?
Over 43k homes north England
How many homes were affected by flooding
Estimated 5.2k
Did the storm kill anyone?
Yes, it claimed 2 lives- in cumbria and the Republic of Ireland
How many £ of damage across cumbria?
Storm Desmond caused an estimated £500 million of damage across Cumbria- almost double the cost of floods that hit parts of the county six years ago.
How many being evacuated across cumbria?
over 1k
What did the Met Office say
That Storm Desmond had more impact because the ‘exceptional’ levels of rain fell on already saturated land.
social services closure
- about 40 schools in Cumbria closed
- appointments and routine business across NHS hospitals were cancelled
- a train en route to Glasgow had been left stranded at Carlisle station overnight, with passengers having to sleep onboard (discomfort, distress)
how many homes were flooded in 2005 Vs 2015?
- immediate social impacts
- 3000 homes flooded in 2005
- Over 5.2k in 2015
medium social impacts
- residents had to live in temporary accommodation
- some local services, such as schools, healthcare shops and offices forced to close temporarily
long term social impacts
many residents suffered anxiety, stress and psychological trauma
immediate economic impacts
- many businesses closed and transport/infrastructure were damaged (bridges, roads and sewers).
medium economic impacts
- businesses and shops closed
- house prices fell in flood-risk areaa
- risk of repeated flooding deterred tourists from visiting
cost of flooding in 2005 vs 2015
2005- £100 million
2015- £400 to 500 million
how much did insurance claims sum to in the UK 2015?
exceeded £6 million
agricultural loss (economic)
long term
farmers lost hedgerows
expensive dry-stone walls were washed away
many sheep drowned
immediate environmental impacts
- rivers were choked with debris and contaminated with sewage and effluents/pollutants
medium environmental impacts
- soils eroded, habitats destroyed and ecosystems affected
- saturated soil led to landslides
- saturated ground led to the decomposition of dead plants and animals- giving off gases such as hydrogen sulphide ( highly toxic)
- other poisons contaminated the food chain and threatened wildlife.
long term environmental impacts
many river banks eroded- added to future flood risks
how many homes and businesses at risk of flooding in England?
In England, approximately 6.3 million homes and businesses are at risk of flooding from rivers, the sea, and surface water. This means roughly one in five properties in England are susceptible to flooding.
