Worksheet 4 - Classroom Debate

INTRODUCTION

Dams (and their accompanying reservoirs) have been constructed for a variety of reasons.  They can bring stable water resources to region and economic prosperity, but there are also many risks and consequences associated with them.  This seminar will consider the wide range of environmental impacts of dams on river systems.

The construction of the colossal Hoover Dam in the 1930s heralded the start of the economic and political trend for large (or mega-) dams (over 100m high) that still continues today.  The most topical and controversial large dam scheme is undoubtedly be the Three Gorges Dam on the Yangtze River, China.  This will be the largest man-made structure in the world.  It has been constructed not only for the purposes of flood protection, navigation and hydroelectric power generation, but as a political statement to the world.  However, such a large structure inevitably has considerable impacts on the local inhabitants and the environment.   Often there are contrasting opinions between fluvial geomorphologists and dam engineers as to the most environmentally-friendly type of dam, whether to continue to build mega-dams or to build more, but smaller dam structures.

Remit

Come along to the session having done some background reading on the pros and cons of dams, in particular their socio-economic, political and archaeological consequences, as well as their environmental consequences.  The seminar will take place in a debate format.  In class you will be allocated to either support and oppose the construction of mega-dams.  

Preparatory Questions

1. For what purposes are dams constructed?

2. How big are dams? Where are the largest dams and reservoirs?

3. What are the environmental requirements (e.g. geology, location) for building a dam?

4. What is the history of the construction of ‘big dams’ (those over 100 m high)?

5. Referring to water levels in the reservoir and water discharge releases, explain how dams operate.

6. What are the (upstream and downstream) effects of dam construction on:

1. the hydrology of the river?

2. the geomorphology and sedimentology of the river?

3. the water quality and ecology of the river?

7. Once constructed, what are the (upstream and downstream) effects of a dam operation on:

1. the hydrology of the river?

2. the geomorphology and sedimentology of the river?

3. the water quality and ecology of the river?

8. Do all dams prevent floods?

9. What are the socio-economic impacts of dams, particularly in Developing countries?  Who are the ‘winners’ and ‘losers’ and why?

10. What are the recent trends in dam construction?

Format

1. Groups will be given time to muster their arguments and co-ordinate their response.  [15-20 minutes]

2. The group ‘For’ the issue will be asked to put forward their arguments.  Each member of the group is encouraged to contribute something to the presentation. [10 minutes]

3. The group ‘Against’ the issue then puts forward their arguments. [10 mins]

N.B. All points should be addressed to the Chair and not to the other delegates.

4. Cross-questioning via the Chair is then allowed (and encouraged). [15+ mins]

All viewpoints must be given to the Chairperson, not directly to another debater.  The Chair will not allow delegates to argue with one another.

5. The debate will be summed up by the Chair. [3-4 mins]

Other resources:

• Synopsis

• Three Gorges Dam - A Review

• Worksheet 1 - Introductory Questions

• Worksheet 2 - Advanced Questions

• Worksheet 3 - Role-play Game

• Worksheet 4 - Classroom Debate

• Notes for Teachers

• Further Reading

• Web Links

Adapted from:

• RiversWEB: www.smuc.ac.uk/RiversWEB/index.html

• Simm DJ (2002) Using the internet as a teaching tool: Three Gorges Dam, China. Teaching Geography, 27(2), 82-86.

© British Society for Geomorphology (Education and Outreach). Author: Dave Simm, Bath Spa University College (2004).