Flood plains and Flooding

Aims To know and understand how flood plains are formed To know and understand the causes, effects and solutions of a flooding event

Floodplains

Floodplain formation Floodplains and levees are formed by deposition in times of river flood. The river’s load is composed of different sized particles. When a river floods it deposits the heaviest of these particles first. The larger particles, often pebble-sized, form the leveés. The sands, silts and clays are similarly sorted with the sands being deposited next, then the silts and finally the lightest clays. This deposition makes up the floodplain.

Copy out the following paragraph and fill in the missing words: A _________ is an area of flat land either side of a ___________ .When a river _________ it deposits the __________ particles first. This forms deposited features called _________ . The lightest materials which are sand, clay and ________are deposited further onto the __________ . Missing words: silt, flood plain, river, heaviest, flood plain, levees, floods

Flooding

What is a flood? A flood occurs whenever a river overflows its banks (over ‘bankfull discharge’). However, a flood becomes a problem when the water rises to a level where it threatens property and/or life. bankfull discharge Meander cross section

What do you think causes a flood?

Draw a table like the one below in your exercise books Factors Reduce floods Increase floods Natural Human

Now look at following statements and put them into the correct place in your table Heavy rainfall Dry, sunny weather Tree covered mountains An urban area Few tributaries Permeable rock Impermeable rock Reservoir created by a dam

Look at the following photographs: Where do you think they were taken? What do you think were the causes of the flood? What happened to people and the environment?

Where was the flood? Answer Bangladesh Were you right?

What are the main causes of flooding in Bangladesh? 70% of the land area is less than 1 metre above sea level Prolonged monsoon season Snow melt in the Himalayas Deforestation in Nepal There are three main rivers – Brahmaputra, Meghna and Ganges

Video You are now going to watch a video on flooding in Bangladesh. You are to make notes on the worksheet that has been provided The notes that you make will help you complete a newspaper article which will be your assessment for this term.

What are the solutions to help prevent flooding in Bangladesh?

Assessment You have to write a newspaper article both describing and explaining the causes, effects and solutions of the flooding in Bangladesh, 1998. You need to make sure that you have a newspaper outline and level descriptor sheet You need to make sure you know how to achieve the highest level you are capable of achieving