003 - Flood Mitigation
Geographic Knowledge and Understanding
Flood mitigation, including structural measures (dams, afforestation, channel modification and levee strengthening) and planning (personal insurance and flood preparation, and flood warning technology).
All countries have the possibility to monitor and control the discharge of water in different places within their national boundaries. Flood mitigation can allow a country to have power over their natural water sources.
To have a knowledge and understanding of different flood mitigation (management) approaches including structural measures (dams, afforestation, channel modification and levee strengthening) and planning (personal insurance and flood preparation, and flood warning technology).
To develop two contrasting detailed examples of flood mitigation.
Define the key terms above by using the 'Freshwater' textbook by Codrington and the 'useful links' below.
Activity One - Structural Measures
We will be looking at four different ways that are used to mitigate floods; dams, afforestation, channel modification and levees. We are looking at these three categories as you are required to look at a river in its entirety and not just a specific section.
Dams are often found in the upper course of the river where the store of water is easier due to the shape of the landscape. Dams are expensive to build and therefore are often used for a variety of purposes. Those dams that have a number of uses are called 'multi purpose dams'. But how successful are dams in controlling the flow of water in a drainage basin? To answer that question we are going to be exploring the impact that the Three Gorges Dam has had on China.
Using the link below in the 'Useful Resource' box create a detailed example of the cost and benefits of using a dam to control flooding. You could use the worksheet to help you structure your notes.
Afforestation is used as a more natural way to prevent flooding. The idea is that the precipitation will be intercepted by the trees and therefore slow down the water reaching the river. It is seen as a less intrusive way to control the flow of water in a drainage basin but how successful is it?
Read the article in the 'Useful Resources' box below and make notes on how afforestation is being used in the UK.
Channel Modification and Levees
Channel modification is when the river channel is altered to either make the carrying capacity of the river greater or to move the water away from the area more efficiently. Channels can be dredged, straightened or even diverted but does it work?
Write a summary of what dredging, channelisation and bank protection is.
Complete a cost-benefit analysis of channel modification.
Complete a detailed example of the Mississippi River and discuss how successful the hard management has impacted the river and the surrounding area.
Our Planet's Freshwate Textbook by Codrington.
The Atlantic - What we've done to the Mississippi River: An Explainer
Scientific America - Levees and the illusion of Flood Control
Flood Plain Management
Lots of houses are built on flood plains as the land is flat and easy to construct on. Transport networks also criss cross the area in the lower course of the river. As flood plain areas have increasingly been seen as areas of value, rivers in these areas are being managed. For this example we are going to focus on the Kissimmee River Drainage Basin.
Read the article and watch the youtube clip in the 'Useful Resources' box to create a detailed example of what has happened to the Kissimmee River.
Activity Two - Planning Measures
As well as hard management of a river to control the flow of water there are a series of different planning processes that can occur to reduce the impact of flooding. How successful though can planning actually be when the severity of flood events is not always predictable? Read the three articles in the 'Useful Resources' box and describe how personal insurance, flood preparation and flood warning technology can mitigate floods.
Activity Three - Debate
For this activity the class is going to be divided into two. One team will argue whether structural measures of control are more effective than planning measures and the second team will do the opposite. The resultant discussion from this debate will help you to answer the essay question in the 'exam style question' section.
Exam Style Question
“People should not try to prevent rivers from flooding.” Discuss this statement. [10 marks] May 2012
This lesson was development in collaboration with Richard Allaway from geographyalltheway. For more resources please visit www.geographyalltheway.com