Rivers (continued) Flashcards
What happened to the transport in Bangladesh after the flood?
The airport in Dhaka was flooded
Bridges destroyed
Railways damages
How much of Dhaka was underwater after the flood in Bangladesh?
40%
How many deaths after the Bangladesh flood?
750 deaths
How many people displaced and homeless after the Bangladesh floods?
30 million
When were the floods in Bangladesh?
2004 from July to September
How many people suffered from disease after Bangladesh?
100,000 people suffered from diarrhoea as the floodwaters left raw sewage in towns
What are the causes of floods?
Prolonged rainfall which causes saturated soul so rain can’t infiltrate and so surface runoff is increase
Relief - steep sided valley causes a faster release of water
Snowmelt - lots of water produced in a short amount of time
Heavy rainfall - lots of surface runoff
What type of energy is hydraulic action?
Kinetic
What type of energy does the upper course have?
Gravitational potential energy
Where does deposition occur?
Anywhere along the river
Where is large material deposited?
Near the source
How does the amount of sediment deposited change downstream?
Increases with distance from the source but is increasingly fine sediment
What type of rock is graphite?
Metamorphic
What does pervious?
Permeable
Let’s water through due to clints and grykes
Formation of an oxbow lake?
- fastest flow of water on outside bend of river
- slower flow on the inside
- this results in erosion outside and deposition on inside
- eventually the neck is Brocken creating a straight channel
- over time deposition occurs and seals the old meander
- leaving an ox bow lake
Problems with flood zoning?
Limited building limits industrial development and job creation
Disadvantage of warnings as a flood response?
Threat remains and dosent prevent damage stress as people have to claim on insurance and in future years
What is it called when a meander shifts downstream?
Meander migration
What is the long profile?
Change in altitude and gradient from the rivers source to its mouth
What is the cross profile of a river?
The change from one valley side
Across the valley floor which contains the channel to the other valley side
Advantages of using embankments as a hard engineering strategy?
Could be also used as a path
Concrete embankments are effective at stopping bank erosion
Earth embankments provide habitat for plants
Disadvantages of embankments as a hard engineering strategy?
Ugly
Often not high enough
Disadvantages of warning systems?
Does not save property
Might not be sufficient time for residents to respond
Effects of Queensland floods?
35 died 100,000 no electricity 78% of the state damaged 2.1 million affected 25,000 homes flooded Area larger than France and Germany flooded
Responses to the Queensland floods?
Nadal vs Federer raised $750,000
Australian defence force raise
Rest of country taxed
AUSTRALIAN DEFENCE FORCE made a live appeal and raised $10 million
England vs Australia cricket donated match fee
