5.5 Flashcards
What are 3 causes of flooding
Jet stream and low pressure
Monsoonal seasons
Ice melt
What are causes of flooding?
- Jet steam and low pressure weather
- Monsoon
- Ice melt
What is an example of an area which has a jet stream and low pressure weather for a cause for flooding?
UK
What is an example of an area that experiences flooding due to Monsoonal rainfall?
India
What is an example of an area that experiences flooding as a result of ice melt?
Siberia
Why does the UK experience flooding?
- Prolonged and heavy rain associated with the passage of low-pressure systems and depressions.
- This time period is called the progressive cycle, occurring at autumn and early winter - however this can occur at other times of the year due to unusual positioning of the jet set.
Why is their flooding in India?
Monsoonal rainfall can lead to damaging flooding in Southern and Eastern Asia.
- 70% annual rainfall occurs in 100 days ( July to September)
- Low-lying plains of South and East Asia most at risk.
Why is ice melt causing flooding in Siberia?
Melting snow in late spring causes extensive flooding.
The quick transition from winter to summer causes rapid snow melting which means a build up of meltwater at the surface
- The Siberia rivers Ob and Yensei often build up.
- Ice dams in Siberia are used to hold flood water.
What is an example of flooding occurring in the UK?
Cumbria floods (2015)
Why did Cumbria flood in 2015?
- Storm Desmond - Cumbria received a month’s rainfall in one day (Honister received 341.1mm of rain in 24hours. Low pressure 946 millibars)
- Conventional and orographic precipitation - combined with already saturated ground - created conditions for extreme flooding.
- Impermeable rock type in Lake District impeded infiltration.
What was Storm Desmond?
A deep Atlantic low-pressure system east of Iceland, with associated fronts stretching across Northern Britain.
What were the impacts of Storm Desmond?
- Flooding of homes - 5,200 homes affected
- Extensive disruption due to travel and evacuation
- 2 deaths due to flooding
- 40 schools closed and routine appointments cancelled.
- Lancaster Universoty closed early for Christmas due to power cuts
- Many homes left without electricity
- West Coast mainline route to Scotland closed due to flooding
- Government provided £50 million to Cumbria and Lancashire county councils to provide money to sacred households.
What were the human causes of Cumbria flooding?
- Population growth lead to an increase of housing = increase impermeable surfaces
- Speeding up flow by building via artificial conducts e.g. drains and sewers.
- Changing land use associated with agricultural development e.g. deforestation, overgrazing, ploughing etc…
What are the three types of rainfall?
Orographic rainfall - when air is forced to rise over areas, making it condense and form precipitation
Conventional rainfall - hot air rises. As it rises it cools, condenses and forms a cloud leading to precipitation.
Cyclonic - cyclonic rainfall is when a high pressure system is forced over a low pressure system. This causes the air to cool, condense and eventually fall as rainfall.
