Flood hydrographs

Flood risk factors Increase riskDecrease risk Impermeable rockPermeable rock Urbanisation (towns/cities with surfaces such as tarmac) Afforestation (planting trees) Steep slopesFlat land Heavy precipitationLittle precipitation

The Boscastle flood, 16 th August 2004 – MEDC flood Boscastle is situated on the North Cornwall coast. For a hundred years the village was a thriving port but the coming of the railways soon saw its decline as a trading port. About 90% of Boscastle’s economy is now reliant on tourism. On Monday 16 th August 2004 major flooding occurred in North Cornwall. The small village of Boscastle was devastated.

What were the causes of the Boscastle Flood? Climatic conditions were the main reason for the floods in Boscastle. 200mm fell over Ottersham Moor, to the east of Boscastle, within a 4 hour period. This was combined with coastal winds and a rising tide. The ground was also already saturated from previous rainfall events. Explain why these conditions would cause major flooding.

Effects of the Boscastle flood

How can flood risk be managed?

Boscastle flood management The Environment Agency is calling for the post-flood features that were removed by human intervention to be reinstated, such as the floodplain pools above the car park and the valley floor debris traps up the Valency. Meanwhile, the Met Office says it is using new technology to try and predict local weather conditions more accurately. Additional web research: at-Boscastle

Bangladesh 1998 LEDC flood - effects 70% of country covered in flood water affecting 2/3 of population Dhaka, the capital – water 2 metres deep. Electricity supply cut off for several weeks Lack of safe drinking water – polluted water in wells due to death and sewage 7 million homes destroyed, 25 million people homeless 1300 deaths – dirty water diseases – dysentry and cholera 500,000 cattle and poultry died 2 million tonnes of rice destroyed Dhaka’s international airport, a third of railways and thousands of kilometres of roads were all flooded so the delivery of emergency food and medical supplies was hampered. $1.5 billion was the estimated cost of the damages

Bangladesh flood - management Embankments, dams, shelters and warning systems were all part of the Flood Action Plan in ,000 shelters in the areas most at risk. Cheap and easy to construct. Improve flood forecasting system using satellite and computer technology Dams costing £500 million build to hold back the monsoon rainwater in reservoirs that would be used for irrigation and generating electricity Complete and strengthen the embankments along all main river channels to a height of 7 metres. This scheme should prevent serious flooding from river overflow.

Management problems Many people are concerned about the unknown effects of these schemes and are worried that a shortage of money will result in only the urban areas being protected. Up to half a million people will lose their land to reservoirs and embankments. Flood shelters save lives but don’t help protect our property and livelihood. The embankments will restrict river access for fishing people.

Nile Delta - River landform Deltas are created at the river mouth where the river speed slows down leading to increased deposition of finer material such as alluvium (silt). The River Nile flows into the Mediterranean Sea which is shallow and has no tide therefore insufficient energy to remove silt. The River Nile carries a huge amount of silt rich in nutrients for fish and fertile for farmers land. The accumulation of silt over the centuries has formed a flat and fertile delta which is now a densely populated area. Another feature of the Nile delta are distributaries (small rivers that branch out from the main river at the mouth). The delta stretches about 160 km in each direction

Nile Delta 2 Silt is ideal as fertiliser for farmers and as food for the fish stock. However the creation of Lake Nasser and the Aswan Dam traps the silt and has a negative impact for the Alexandria fishermen and farmers. Valuable nutrients are lost and fish stocks have gone down. Consequently the delta is shrinking which means people are losing their homes and land. The soil is less fertile without the annual replenishment of silt. Farmers must now buy artificial fertilisers for their land. These are expensive and can cause pollution.

Waterfalls

Case Study 2007 questions CASE STUDY: The effects of a flood on people in a More Economically Developed Country (MEDC). (i) Name and locate an area of an MEDC where flooding has taken place. (ii) Describe how the flood affected different groups of people. (iii) Explain the causes of the flood. CASE STUDY: A river landform. (i) Name and locate a river landform you have studied. (ii) Describe the main features of the landform. (iii) Explain how the landform was formed.

Case study 2006 questions CASE STUDY: A river landform For a river landform you have studied: (i) Name and locate the landform (ii) Describe the landform. (iii) Explain how it was formed. Use diagrams to help. CASE STUDY: A place that has been affected by flooding. (i) Name the place that has been affected by flooding. (ii) Describe the effects of the flooding on people and the environment. (iii) Explain what caused the place to flood.

Case Study 2005 questions CASE STUDY: A landform created by the work of the sea. (i) Name and locate a landform that has been created by the work of the sea. (ii) Describe how the landform was created by the sea. (iii) Explain any advantages and disadvantages that the landform brings to the area around it. CASE STUDY: A coastal management scheme that protects the coast from the action of the sea. (i) Name and locate a coastal management scheme that has taken, or is taking, place to protect the coast. (ii) Describe the scheme. (iii) Explain why the scheme was, or is, necessary.