Water balance: relationship between inputs and outputs of a drainage basin.
Precipitation = Q (runoff/discharge) + E (evapotranspiration) +/- changes in storage.
1. Define the different stages in the hydrological cycle:
- surface runoff
- groundwater flow
2. You should also be able to identify stores (groundwater, lakes, clouds) and transfers (precipitation, evaporation, throughflow etc).
Changing Balance of Ice and Water
Climate change is reducing the volume of water stored as ice.
- Watch video A1, describe why mountain glaciers are so important for many people and economies.
- What are the likely effects of reducing mountain glaciers?
- Read this article and describe the concerns of the local Nepalese regarding the glacial lakes forming in the Himalayas
Maximum Sustainable Yield: The maximum level of extraction that can be maintained indefinitely for a given area.
- Use Video A2 and the links below to make Case Study notes about groundwater extraction.
Drainage Basin: The area drained by a river and its tributaries.
Drainage Divide: Also known as a watershed, it is the line defining the boundary of a river or stream drainage basin separating it from adjacent basin(s).
You should have an understanding of the following river features:
*source, tributary, confluence, channel, floodplain, mouth, delta, distributaries.
* River profile & characteristics: upper, middle & lower valley. Bradshaw model. Waterfalls.
* River discharge: define, measurement (cumecs).
- Describe the factors affecting the hydrograph: basin shape/size, drainage density, human influence, slope gradient, climate, soil type, vegetation.
- How do these affect the lag time and peak discharge?
- Explain the purpose & use of hydrographs in predicting floods and the frequency of occurance of floods.
CASE STUDY: Bangladesh flooding
Case study notes (password required)
Use this pdf to make notes about the Bangladesh floods.
You should draw a sketch map showing the main physical features that contribute to the flooding.
You should be able to discuss the relative importance of human and physical causes. Banagladesh has experienced rapid poulation growth and has a high population density.
Case Study: Aswan Dam - Egypt
Costs/benefits of the dam
Case study notes (password required)
Case Study: 3 Gorges Dam - China
- Read these links below and watch Video to answer the following questions.
- Describe the main purposes of the dam.
- What benefits was it intended to bring (environmental, economic,social)
- What negative impacts has it had (environmental, economic,social)?
- Evaluate whether the benefits outweigh the various costs.
- 3 Gorges Dam: China
- Chinas 3 Gorges Dam Issues
- Cracks in the Three Gorges Dam, (300,000 people can wave goodbye to their homes)
- Three Gorges dam wall completed
- Three Gorges dam's social impact
- More people moved in China near Three Gorges dam
- Three Gorges dam resists surging Yangtze floods - images
- Urgent social & environmental problems
1) Factors affecting erosion: velocity, gradient, human activities.
2) Levees, meanders & oxbow lakes.
3) Notes about deposition: deposition features (deltas, braided channels, levees), reason for increased deposition & benefits brought by deposition..
4) Human modifications of floodplain & effect on flooding
- urbanisation & impermeable surfaces - reduced infiltration, faster & increased runoff.
- extraction of water - irrigation, wells
- River channel adjustments - building development, bridges,
- Chinas River Diversion - video
5) Management Strategies
Case Study: London, UK
short guides looking at some of the causes & solutions to flooding in London
Flood barriers such as the Thames Barrier, London
Yangtze River: China.
3 Gorges Dam upstream to hold back floodwater & release it slowly.
Jingjiang flood diversion scheme - area allowed to flood to protect large urban areas downstream.
Mississippi flood gates opened (Telegraph 2011)
Practise Exam Q
You may use your books, research etc to answer this - make it thorough & treat it as a learning execise rather than a test.
Read this article for an introduction to the unit Groundwater. Published by http://www.yearofplanetearth.org/
Unsustainable use of groundwater: India
New reserves of groundwater discovered: Namibia
Pollution of groundwater and health implications: Bangladesh
Case Study: Kissimmee River Restoration
Wetlands: Areas that are regularly saturated by surface water or groundwater, including freshwater marshes, swamps and bogs.
Wetlands are an important ecosystem supporting a wide species diversity. They also filter water passing through them removing many pollutants. In addition they can play a significant role in reducing flood risk.
Many wetland systems around the world are under threat due to development.
Watch the videos opposite to make case study notes about the Kissimme river project and restoration. Make sure that you answer the following questions in your notes
- Where is the Kissimmee river.
- How, why & when was it altered?
- Why is it being restored?
- How is it being restored?
- What is the financial cost of restoring the wetlands?
- Read & make notes about the the impact on a global scale that fertilisers are having.
- Why have they become so essential for food supplies, but also for economies that rely on agriclture?
- What is micro-dosing and how can it help overcome?
Case study (password required)
Water Conflict: National Scale: Peru
Mini-series looking at water shortages in Peru. Watch the 3 videos (A5 to A7).
- Make Case Study notes about:
- The causes
- The effects on the local people
- Ideas about what can be done
Conflict over Water - International Scale; River Nile
Case Study (password required)
- Use the links below to make a Case Study about the conflicting demands for water from the River Nile. Include the following sections:
- A map showing the countries that the Nile flows through.
- Describe the historical agreements over the Niles water.
- Why are Ethiopia and Uganda wanting to use more of the Niles water upstream?
- Why is Egypt strongly opposed to other countries using more of the water from the Nile.
- Do you think that the other African countries should be allowed to take more water from the Nile and to dam it?
The Nile River Basin
Past Exam Q essay:
“The lower courses of rivers are more important to people than the upper courses.”
Discuss this statement with reference to located examples. [20 marks]
Lake Mead & the Hoover Dam
Water wars in the USA: BBC video clip about state conflicts over the use of the Rio Grandes water.