Water - Flood

1. Floods can be deadly, particularly when they arrive without warning

2. Some floods occur as a result of sudden torrential rain in local areas, others are caused by melting snow

3. Occasionally, a river bursts its banks or the sea might surge over a coastline during a storm causing floods.

4. When rain pours for weeks at a time, the land becomes saturated and the natural drainage system is likely to fail.

5. Upper reaches of the river fill quickly and force excess water downstream.

6. Lower reach water flows slower and the extra water causes the river to break its bank.

7. Flash floods are sudden, unexpected floods.

8. They happen when lots of heavy rain falls over a short period of time, snow melts quickly or water defences fail.

9. The ground becomes saturated with water so quickly that it can’t absorb it.

10. The water runs off the soil instead of soaking into it.

11. Floods can cause damage and death.

12. People and animals die due to drowning and structures, such as houses and bridges, can be destroyed.

13. One of the worst aspects of flooding is that sewage and other waste contaminates drinking water supplies.

14. People are advised to stay in during floods, as six inches of rapidly moving water can knock someone over.

15. People are warned never to drive through flood water, as vehicles can be swept up by just two feet of water.

16. Flood plains are a river’s natural defence mechanism to provide relief and take up excess water.

17. Floodplains are areas of flat land around river channels.

18. They are formed during times of flood when the amount of water is greater than the river can hold.

19. The floodplain becomes covered with water and mud, known as alluvium, is left behind when the floodwaters go away.

20. Alluvium is made up of silt, sand, clay and gravel.

21. It often contains a great deal of organic matter which makes the soil very fertile.

22. The size of a floodplain depends on the nature of and number of floods experienced.

23. Clearing land, cutting down trees and allowing animals to graze near rivers adds to the risk of flooding.

24. There is not as much vegetation to trap the rain, so the ground has to absorb more.

25. Building can also create problems, as water is not easily absorbed by man-made building materials.

26. Flood defences are used to help prevent flooding.

27. Embankments of soil and earth, called levees, man-made lakes and reservoirs, dams, barriers, dykes and weirs provide defence.

28. The Thames Flood Barrier has been built to protect London’s highly-populated, low-lying areas from flooding

29. If a dangerously high tide is threatened, a continuous steel wall is formed measuring 520m from bank to bank

30. Flooding may become an even greater concern in the future.

31. More people are living near coasts and rivers, or in houses built on flood plains.

32. There could be a rise in sea levels due to the melting ice in Antarctica, which will put more people at risk.

33. There may be an increase in stormy weather due to climate change.