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30 Cards in this Set

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List different types of hard engineering

Flood control dam


Flood channel


Wing dykes


Relief channel


Flood barrier


Flood embankments


Emergency action plan

What is a flood control dam and where is the one?

A dam and when a flood is expected the gates are closed to prevent flooding below


Los Angeles


It's very expensive

What is a flood channel and whee is there one?

It is a straight channel that drains water directly the sea (though some just drain downstream)


The purpose is to get the water away from the city as quickly as possible


These channels can cause flooding downstream


Los Angeles

What are wing dykes and where are they found?

They are walls built at right angles to the river channel going halfway across the river.


As a result more erosion occurs on one side of the river which makes it deeper. This means the river can hold more water.


The are wing dykes on the Missouri River in America.

What is a relief channel? Give an example

When the a river can't carry all of its water, the excess water goes down a completely artificial alternative channel


When the River Thames can't carry all of its water, the excess water goes down the jubilee river which is man made.

What is a flood Barrier? Give an example.

Blocks of the river if it is about to flood. This may cause a flood up steam, but this will protect the city downstream.


There is a Flood Barrier on the River Foss near York

What are flood embamkents? Give an example of whee they can be found.

Flood embankments are artificial levees. They are built up really high so even if there lots of water it won't flood the road/city next door.


River Trent

What is an emergency action plan where hard engineering is concerned? Give an example

They are short term barriers that are put up between the river and the town to protect the town from flooding

Name an example of hard engineering case study and explain its purpose

The Three Gorges Dam


Yangtze River, China


Its purpose:


- reduce flood risk for 15 million people


- improve navigation along the river


- generate hydroelectric power for central and eastern China.

Explain the impacts , difficulties and environmental effects of an example of hard engineering.

The amount of sediment transported by the river below the dam fell by 50%, leading to increased rates of erosion downstream.


Sediment will acquire behind the dam and this will require dredging.


Afforestation on the slopes of the drainage basin is needed to reduce sediment washed into the river and reservoir behind the dam


There is now an increased liklihood of la d's lies in the immediate area


Many species such as the white flag dolphin will have their habitats disrupted


1.2 million people had to be resettled due to the creation of the reservoir

When was the Three Gorges dam completed?

2009

When were the Bangladesh floods?

2007

List physical and human causes of the Bangladesh floods

Physical:


South Asia has a monsoon climate (the monsoon rain also helps melt ice)


90% of land in Bangladesh is less than 10m above sea level


Melting snow and ice from the himalayas increases river discharge


Heavy, prolonged rainfall



Human:


Deforestation in Nepal means less water intercepted


Growth of urban areas due to migration

What are the short and long term social impacts of Bangladesh floods

25 million people homeless - properties destroyed so took shelter at government relief shelters.


100,000 houses destroyed as porous mud bricks became saturated with floodwater


100,000 people caught waterborne diseases such as cholera


Around 1,000 people died due to flooding and disease.


4,000 schools affected, so it was a while until education could resume.

What were the short and long term economic impacts of the Bangladesh floods?

Widespread loss of cattle - 80% of Bangladesh people rely on agricultural and so many lost their livelihoods.


10,000km of roads destroyed


High costs to housing and infrastructure,lots of repairs needed


Loss of raw materials and factories.


Lots of land couldn't be planted with rice at peak time (world cost of basmati rice rose by 10%)

What human factors made the impacts of the Bangladesh floods worse?

Bangladesh is a poor country so few flood defences systems or warning systems were in place


Low incomes, few savings and little insurance limited people's ability to recover from the flood


Corrupt officials diverted aid money away from those who needed it most.

What were the environmental impacts of the Bangladesh floods?

Rivers had sewage in them - water supplies became contaminated


Fertile soil was deposited onto floodplain.

Name a soft engineering case study

The River Quaggy restoration scheme, UK

Discuss the River Quaggy resort action scheme. Include location, purpose, types of engineering, and advantages/disadvantages

The river Quaggy runs through south east London


The was hard engineering the is the 1960s - artificial channels and culverts were built to divert the river beneath the ground surface as it passed through Greenwich


More recently, a new lake has been created to take over when the culvert is full. The park was lowered and shaped to create a floodplain were water could collect naturally.


The flood plain has reduced risk of flooding for 600 homes nearby.


The scheme has created a diverse wildlife wetland environment with reed beds wild flower meadows and trees.

List four types of soft engineering flood protection strategies.

Flood plain zoning


Afforestation


Wetland restoration


River bank conservation

What is flood plain zoning? Give an example

The parkland at Shrewsbury


The floodplains are let as grassland despite pressure to build there.

What is afforestation? Give an example

The Lake District national park.


Planting trees in ceases interception. This gives more time for infiltration to occur. There will also be more infiltration loss.


Farmers are encouraged to plant trees, and if they do they are given money.

What is wetland restoration? Give an example

The Somerset Levels.


You set aside ares and allow them to flood.

What is river bank conservation? Give an example

The Norfolk Broads.


There are lots of boats on the Norfolk Broads, and the swash created by the boats causes erosion of the river banks and this causes flooding. Reeds are replanted on the river banks, and some areas have boat speed restrictions.

Explain (in lots of detail) how meanders form

Even in a straight line channel, the river will deposit load at times of low flow. These areas are called riffles and between them are depressions called pools.


Once riffles form friction increase, hydraulic radius decreases and flow is inefficient.


The river the for tries to flow around these riffles, and the channel becomes slightly deeper on one side of the riffle.


This causes the thalweg to move towards one side of the river, which then starts to become the outer bank of the new meaner.


Energy is at its greatest at the outer bank and so it is undercut. This creates a river cliff.


On the inside bank, energy is low and so deposition builds up creating a point bar deposit.


As erosion continues, migration occurs both laterally and downstream.

When were the cumbria floods?

2009

What were the causes of the Cumbria floods?

Large amounts of storm flow


The landscape is hilly and overland flow the is quicker


More rapid through flow a the area is rural and so thee are more underground channels and tunnels created by animals and plant roots.


Heavy rainfall the week before the flood meant the ground was already saturated - the soil had already reached its infiltration capacity.


Cumbria experienced re Ord daily rainfall for the UK in 24 hours.

What were the impacts of the Cumbria flood?

Someone died


2,000 properties affected


250 farms affected


500 additional pupils requiring school transport


Damage to historic buildings


£300 million damage


Tourism suffered loss


Gravel and debris deposited on farmland making it impossible for farmers to work the land

What was done to alleviate the effects of the flood in Cumbria?

Insurance industry pay outs of £174 million


Army built a footbridge so people from one side of the river could get to the other


Health authorities provided a special vaccination to help prevent people catching diseases and infections from the polluted flood water.


Local people moved historic artefacts to higher floors of buildings


Flood recovery work.

List flood prevention techniques

Afforestation


Reservoir construction


Controlled flooding


By-pass channel


Enlarging channel by dredging/channel straightening


Embankments