What do you need to know? This resource looks at the difference between Hazard, Risk and Disaster!

Flood risk Flood Hazard Flood disaster Impact Probability (high/low)

What does low probability mean? What about high probability? What does low impact and high impact mean? So knowing these terms: What would a low probability river look like and why may it have a high impact on the area? Write a brief explanations for all 4 statements?

Low probability High Impact High probability High impact Low probability Low impact High probability Low impact Not much chance of a flood happening, but if it does it will be a disaster. A great chance that a flood will hit, and will be a disaster. Not much chance of a flood happening, and will not be a being problem if it does A great chance that a flood will hit, but it will not cause lots of devastation if it does.

Which river has the highest and probability of flooding? Which river will have the least/highest impact? Can you explain your reasons Remember; social, economic, environmental

Discuss in pairs Possibilities: River 1 What is the probability of a river flooding and what type of impact will the river have socially, environmentally and economically? River 2 What is the probability of a river flooding and what type of impact will the river have socially, environmentally and economically? Compare the probability and impact of flooding in area 1 and 2. Feel free to annotate your booklet

 In which of the two areas would a flood be most likely to cause a disaster? Explain why? (8)

 A disaster would be more likely to occur in area B, this is because when it rains in area 1 the water will travel straight to the river and will flood the town and factories, whereas there is dam in area A which will stop the water, it can be held in the reservoir, then gradually released into the river over a period of time. (4).  In area A there are lots of trees, which will absorb the water and transpire it back into the atmosphere before it can get to the river, whereas in area B the trees have been deforested, so the water will run straight into the river and result in the town and factories being flooded. (4)  In area A there are lots of trees, so the roots will hold the soil together, so it will not be washed into the river, wheras in area B the trees have been deforested, so the soil/silt will wash into the river, fill it up and cause a flood.(4)  In area A they have only got a small village, so the impacts of a flood will not be as great a disaster as in area B, where they have built a large town and factories on the flood plain, leaving them vulnerable to flooding.(4)

Where would you place area 1 and area 2 on the graph (2b)? Why? Which area is more likely to have the largest impact?

This resource shows potential flood levels from floods of different ‘return periods’ on a floodplain.

Return period also known as a recurrence interval is an estimate of the interval of time between events like an earthquake, flood or river discharge flow of a certain intensity or size. It is a statistical measurement denoting the average recurrence interval over an extended period of time, and is usually required for risk analysis (i.e. whether a project should be allowed to go forward in a zone of a certain risk) and also to dimension structures so that they are capable of withstanding an event of a certain return period (with its associated intensityearthquakefloodriver discharge flow Can some tell be what this means?

A return period is to do with the probability of the river flooding in a time period. For example, a 10-year flood has a 1 / 10 = 0.1 or 10% chance of being exceeded in any one year and a 50-year flood has a 0.02 or 2% chance of being exceeded in any one year. Or in other words the river has a possibility of flooding 1 in every 10 years, 100 years etc to a specific level

What does is show?

Floodplain zoning

Look at all the pictures. Memorise them You have I minute Now take it in turns to describe a picture and mentioning its location. Describe and explain the human’s use of floodplains around the world?

How and why does the a ‘return period’ influence the land use on a floodplain? Which areas will impacted the most if the river flooded and why? Suggest and explain where you would locate the following uses on the hazard zone.

 Discuss as a class  How are the floodplains used?

Describe two pictures and explain why they are located on a floodplain?

 Describe two ways groups of people use floodplains and explain why they use them. One in an MEDC and one in an LEDC. (8)

Residents in MEDCS want to live in towns on flood plains because they are attractive areas with lovely views, they can also easily go canoeing or sailing on the river, or fishing. (4) Farmers in MEDC’s want to farm on land near to rivers, this is because the land will be fertile, so the grass will grow for grazing, so they can make more money. (4) Farmers in MEDC’s want to farm the land near to rivers, this is because the land is cheap because no houses will be built next to the river due to flooding, therefore the farmer can make more profit. (4)

 Governments and Energy companies in MEDC’s will build power stations on flood plains, because no-one lives nearby, so local residents will not complain about noise and pollution. (4)  People owning caravan sites will locate sites on flood plains because tourists want to stay by rivers, because they are attractive, and they can participate in watersports and admire the views. (4)

 Residents in LEDC’s will want to live near rivers, so they have access to drinking water, so they can wash and collect fresh water without walking a long way. (4)  Farmers in LEDC’s will farm on flood plains because the land is fertile due to the silt washing up from the river, therefore they will grow more crops and make more money. (4)

Which is the most effective way of reducing the impact of a flood? What factors do you need to consider before defending a river? Create a spider diagram

Type of defenceDescriptionAdv/Dis Monitoring Zoning Dams/ Straighten channels

Describe and explain one advantage and disadvantage of flood defence system of your choice. Which strategy would be the most effective for a 25 year; 50 year; 100 flood return? Rank the flood defences in order of: Cost Effectiveness Visually ascetic

How should the flood risk be managed? Which scheme received the best score? Explain why.

Dams on the Rhône This is a dam generating HEP near Beauchastel. Dams can be multi-purpose: They hold back the spring meltwater and so stop the floods. They release this water in the dry summer to irrigate the intensive fruit and vegetable growing areas. The water is also used for cooling in the two nuclear power plants near Genissiat – Beugy and Creys-Malville. In addition, the dams produce hydroelectric power (HEP). What are the disadvantages of building dams?

After the Lynmouth floods in 1952 revetments wider channel concrete banks Study the photograph. Explain how the changes will help to prevent flooding. What action was taken after the Lynmouth floods in 1952?

Case study: Brisbane Describe the location of Brisbane