Comparing flooding in MEDCs and LEDCs

Comparing the effects of flooding in MEDCs and LEDCs

Having studied two flood case studies in countries with contrasting levels of economic development you will have seen that MEDCs usually have much better flood protection than LEDCs and subsequently the effects of flooding are often not as severe in terms of loss of life. However flooding still occurs in MEDCs and as well as some loss of life, the level of economic disruption can still be significant. You need to be aware of the main reasons for the differences in the level of disruption caused by flooding in LEDCs and MEDCs:

Problems faced in LEDCs which make the effects of flooding worse and flood management difficult:

• - poor quality housing can't withstand flood waters
• - poor infrastructure is easily damaged with roads, bridges and communications destroyed by flooding
• - lack of sanitation and clean water supplies resulting in further loss of life during floods through the spread of diseases such as cholera, dysentery etc.
• - difficult to mobilise rescue teams - lack of funding for training but made more difficult by many areas being isolated during flooding due to damage to infrastucture and inundated by flood waters;
• - little political co-operation between Bangladesh and its neighbouring countries - makes it difficult to reduce flood risks by tackling issues in the headwaters of the major rivers which are located in India and Nepal;
• - the country relies on government aid and aid from other countries - with a lack of money many necessary flood defences can not be constructed
• - in order to tackle poverty the government have focused much of their funds on improving exports - again reducing the money available for flood protection.

Reasons why the effects of flooding usually less severe in MEDCs and flood protection is better:

• - homes and possessions are able to be insured against flood damage
  
• - good water and sewage systems are in place providing back up supplies of clean water when local supplies become contaminated - means that disease is not the problem it is during flooding in LEDCs;
• - good infrastructure and communication networks means it is easier to get aid and helpworkers to affected areas increasing survival through rescues and evacuation;
• - planning restrictions are usually in place to discourage new building of houses on floodplain areas or areas prone to flooding;
• - governments in MEDCs are able to invest more heavily in flood defence systems - including channelisation projects; the construction of artifical levees and the development of prediction and warning systems.

You should be prepared in an exam to be able to contrast the effects of flooding in MEDCs and LEDCs and to be able to suggest reasons for the differences.

Flooding in an MEDC - The 2004 Boscastle Flood

The Boscastle Floods of 2004

Flash floods such as those that resulted in the flooding Lynmouth back in 1952 are often caused by a combination of factors which as well as sustained heavy rainfall, includes consideration of the relief and drainage of an area. In 2004, almost exactly 52 years to the day after Lynmouth's disaster, Boscastle, a town in north Cornwall suffered a fate simillar to that of Lynmouth as 6cm of rain fell in two hours resulting in a 3m high wall of water rushing through the village. This BBC newspaper article summaries the causes of the Boscastle flood - look for similarities in the cause between this flood and the one you have studied that affected Lynmouth in 1952.

The village of Boscastle suffered extensive damage after the flood and the Environment Agency have released this excellent (but detailed) document summarising the causes, effects and responses to the Boscastle flood entitled "living with the risk".

6 buildings and many cars were washed into the sea and boats and other debris was washed into the sea. Thankfully unlike Lynmouth, in the Boscastle floods there were no major injuries or loss of life - even more amazing when you see the pictures and video footage of the devastation caused. If you are interested in finding out more the following links provide further information on the causes and effects of the Boscastle flood - there are also some great pictures and short video clips showing the devastation.

Articles
North Cornwall Flooding Updates - provides a useful summary of day by day updates from the time of the flood
Wikipedia Article - Boscastle Flood 2004
Boscastle a 'tourist ghost town' (BBC Article)
Devastation in Boscastle (BBC Cornwall) - great site including audio file interviews with villagers
Villagers describe flood horror (BBC article)
Dozens rescued from flash floods (BBC article)
Village 'unlikely to flood again' (BBC article)

Photo Galleries
In Pictures - Then and Now (Boscastle Flood) (BBC) - excellent site showing very clear photographs of the devasted areas before and after the floods;
The devastation and clean up operation (BBC)
Repair work being undertaken in Boscastle
Photographs of the 2004 Boscastle Flood










Video Reports on the flooding
BBC 2004 video report on the Boscastle Floods (see top side link)
BBC video report on Boscastle as it is now (see bottom video link)

Mr Allway of geographyalltheway.com has added an excellent activity to his website comparing the Boscastle and Lynmouth floods - well worth a look!

Source of Photographs: Wikipedia Creative Commons - Benjamin Evans

Flooding in an MEDC - The 1952 Lynmouth Flood

LYNMOUTH FLOOD 1952 (Devon)

The Lynmouth Flood
It happened in August of 1952,
The size of the river suddenly grew;
It tossed and turned and ruined lives,
It killed husbands, children and wives;
The sun disappeared, they sky turned grey;
This was no longer an ordinary day.
The water rose to 40ft high,
You could here all around the people cry.
In the months before there had been lots of rain,
The ground no longer became a drain.
The ground trembled, water came crashing,
Parents were runnning, children were splashing;
When the water came in there was no place to, hide
The river was loud, fast and wide;
It came thundering in and over took the land,
Destroying houses like a giant's hand. (Chloe - Yr 8)

The flood which hit the Devon village of Lynmouth on August 15th 1952 was one of the worst in living memory in Britain. This BBC article from the time gives an introduction to the disaster. Floods the size of that which struck Lynmouth may occur only every 100 - 200 years. For your exam you will need to know the causes of the floods and the effects on the people, environment and economy of Lynmouth.

CAUSES OF THE LYNMOUTH FLOOD


So what did cause the River Lyn following through Lynmouth to burst its banks in such a devasting way in August 1952? The answer to this question involves consideration of several contributing factors which had increased the likelihood of such a flood taking place (click on diagram for a summary of the factors).

• The small but steep sided drainage basin in which Lynmouth was situated increased the risk of flooding in the area. The steep sides encouraged greater surface runoff and combined with the small drainage basin size meant any water could reach the river fairly quickly;
• This was made worse by the high drainage density of the area due to the impermeable rocks of the area around Exmoor which formed the source of the river; again increasing the amount of surface runoff following rainfall;
• Prior to August 15th 1952 Lynmouth had received above average rainfall for 12 out of the first 14 days of the month meaning the soils were already saturated and the river levels high.
• On August 15th a heavy thunderstorm resulted in 200mm falling in 14 hours, one of the three heaviest rainfalls recorded in the UK. This heavy rain combined with the saturated ground and rapid surface runoff resulted in a huge volume of water flowing down the river. As Lynmouth is situated at the confluence of the East and West Lyn rivers the volume of water was increased further at this point and the was far beyond the capacity of the river channel causing the river to burst its banks. This resulted in devastating floods as the West Lyn which had been diverted during the construction of parts of Lynmouth retook its natural course, flowing straight through the village.

EFFECTS OF THE LYNMOUTH FLOOD

You will need to make sure you learn place specific facts about both causes and effects in order to achieve the full marks in case study questions - here are a list of some of the effects of the Lynmouth Flood:

• Debris built up behind bridges resulting in the build up of a flow of water which eventually burst resulting in torrents of water flowing through Lynmouth with 34 people being killed in the disaster
  
• The West Lyn river took its original course flowing straight through Lynmouth destroying 90 houses and hotels;
• 130 cars and 19 boats were also lost, swept into the river or out to sea as the force of water was able to transport large amounts of debris (including gigantic boulders)
• Debris transported by the River Lyn resulted in the enlargement of the River Delta

This link to audio clips features interviews with some survivors of the Lynmouth Flood

Flood Management

Following the Lynmouth flood disaster, flood management plans were put in place to try and ensure such a disaster could not happen again by managing any excess rain water so that the River could cope in the future.


A number of flood management strategies were put in place:

1. The mouth of the East Lyn was widened to increase capacity and allow water to quickly pass into the Bristol Channel
2. The West Lyn was straightened to increase channel efficiency - straightening the channel reduces friction and increases velocity, enabling water to travel through the channel as quickly as possible making it more efficient in coping with flood waters;
3. The West Lyn was not rediverted, instead being allowed to follow its natural course
4. Floodplain zoning was used to identify areas around the river most at risk from flooding. Building restrictions were then put in place with areas close to the river which are most prone to flooding being left as open spaces such as car parks.
5. Bridges were made wider and taller to allow flood water to tr avel quickly beneath them and to reduce the likelihood of debris becoming trapped and acting like a dam as had happened in 1952;
6. Embankments were built by the river to increase channel capacity and reduce the likelihood of flooding;
7. More trees were planted upstream in the source area to try and reduce initial surface runoff through interception and the soaking up of water. Tree roots also help to improve infiltration by opening up the soil and slowing down the rate at which water reaches the ground;
   

Follow up links:
The following links provides further useful background on the Lynmouth Flood
Lynmouth Flood of 1952
Exmoor National Park - the Lynmouth Flood
2002 Memorial for the Lynmouth Disaster
Rain Making link to killer floods - an interesting twist in the tale which some people have said could explain the higher than usual levels of rainfall!

Source of Photographs www.geographyphotos.com / A Lawson