Water on the land 2

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  • Created by: Jan Shah
  • Created on: 22-04-13 19:46

Flood management strategies

Advantages of building 12 to 15 floodwater storage basins to hold flood water diverted from the main rivers.

  • It if a form of soft engineering and it would create a diversion for the water so it would not flood the main rivers. Also it would decrease the percentage of land underwater.

Disadvantages of building 12 to 15 floodwater storage basins to hold flood water diverted from the main rivers.

  • It would take a long time to build and for it to work.
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The costs and benefits to soft engineering

Benefits

  • It has less impact to the environment and is sustainable since it uses living structures for construction meaning that it doesn't harm plants or wildlife.
  • It is cheaper to construct since it makes use of what is already available.
  • It can reduce flooding e.g if afforestation it occurring then it reduces the surface run off.
  • It does not require maintenenace e.g planting trees

Costs

  • It restricts housing development as it makes use of living structures and can not support hard structures above it.
  • Some types can be slow to take effect e.g creating room for the river.
  • Some may not be strong enough to reduce most of the effects of the flood e.g earth embankments.
  • It is not as effective in reducing floods and takes a long time to take effect.
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Costs and benefits of hard engineering

Costs

  • It tends to be quite expensive and sometimes ugly.
  • They are not sustainable or environmentally friendly.
  • It could involve the relocation of people who live in the area.
  • The short term engineering requires maintenance.

Benefits

  • They are long term investments meaning that they will work without any cost for maintenance.
  • Can be multipurpose e.g dams and reservoirs could produce HEP and prevent flooding. e.g 3 gorges dam
  • It reduces damage of the floods by preventing them.
  • It reduces flooding effectively.
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Case study of Malton flooding

Physical Long term causes

  • Changes to the drainage basin since the ice age. An ice sheet from Scandinavia diverted the rivers.

Human causes

  • Deforestation as the Bronze age farmers cut down the forests on the hills to make space for arable land.
  • Building on a flood plain increases the risk of flooding as there is nowhere for the water to go asthe flood plain has been used for properties.
  • When they built the new estate they did not put in any new sewers so the water overflowed them.
  • The estate made the ground impermeable so the water could not sink into the soil.
  • Changes in land use - urbanization on the River Derwent flood plain.
  • Expansion of human use of the flood plain e.g sewage plants, impermeable surfaces deforestation.
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Case study of Malton flooding

Physical short term causes

  • Prolonged rainfall over 125mm of rain fell in two days.
  • Heavy rain ran off very quickly and flowed into the River Derwent.
  • Snow melt made the water flow straight into the river.
  • Hydrological cycle in a drainage basin / river discharge.
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Case study of the three gorges dam

The main reasons for the flooding on the Yangtze river was that in summer there was very heavy rainfall which falls straight into the river causing flooding. Snowmelt in the spring, when the snow melts it flows straight into the river.

The consequences for large scale flooding was that in the rural areas due to flooding their homes had been destroyed, crops were ruined and their was a lot of trauma for the people. Unemployment was a bit high because the machinary in factories were damaged so a lot of people lost their jobs.

Floods are problematic in poor countries because of the cost of massive infrastructure that has to be built to regulate the river floods. It is hard for the people to recover and they are reliant on agriculture so with the floods it eliminates their food source.

The three gorges dam was built to control flooding, to create hydroelectric power and to improve shipping to make it safer and more effective.

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Case study of the three gorges dam

Advantages and disadvantages of the dam (hard engineering)

Advantages

  • Less flooding
  • Good long term investment, it is sustainable and economy efficient as it requires no extra cost for maintenance.
  • Better infrastructure by the rebuild of major cities.

Disadvantages

  • The cost of the megadam is very expensive.
  • Rebuild the cities that were going to be flooded.
  • Less compensation to people making them poorer.
  • A lot of people had to relocate or migrate.
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Water supply in England

Supply and demand of the water in the UK

The average British person gets through 150 litres a day per person.

Renewing leaking pipes so tht water doesn't get wasted but it is very expensive.

To bring water where it is most needed is to transfer water to the South and East where there is a shortage of water from the North and West where there is more water.

There is an increasing demand of water because of population growth therefore more water is needed. They are building more housing so more water is needed. The areas where the housing is, is in areas of water stress. As we develop we have an increase in number of water dependent appliances. Climate change is also an issue.

Areas with relatively low rainfall tend to be areas with relativelyhigh population densities. People tend to settle where there is flat land, good soils for agriculture, plenty of resources available and good infrastructure.

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Water supply in the UK

To ensure that water demand in the UK can be met in a sustainable way are that houses are being designed with a better water efficiency, devices are fitted to toilet cisterns to reduce water use, Rainwater can be collected, bath water can be recycled to flush toilets, more people are taking showers than baths.

Environmental issues

The River Severn water has different mineral, nutrient, acidity and temperature characteristics from Thames river water.

Social issues

Land will be lost, and river habitats and salmon migration disturbed, without any benefits to Welsh people and local economy.

Political issues

This will lead to political issues since the people will demand the governement to do something about it.

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Water supply in the UK

Economic issues

The total bill for increasing dam sizes in Wales and building tunnels netween the Severn and Thames valleys would hundreds of millions of pounds.

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