Water balance: relationship between inputs and outputs of a drainage basin.
Precipitation = Q (runoff/discharge) + E (evapotranspiration) +/- changes in storage.
Ensure you understand the different stages in the water cycle. You should also be able to identify stores (groundwater, lakes, clouds) and transfers (precipitation, evaporation, throughflow etc).
You are required to be able to discuss the impact of climate change and its impact on the amount of water stored as ice: Problem of less water being stored as ice in the water cycle
Maximum Sustainable Yield: The maximum level of extraction that can be maintained indefinitely for a given area.
water mining - sustainable? sea level?
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:
* Features of drainage basins: source, tributary, confluence, channel, floodplain, mouth, delta, distributaries.
* River profile & characteristics: upper, middle & lower valley. Bradshaw model. Waterfalls.
* River discharge: define, measurement (cumecs).
Make notes about 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?
Be able to explain the purpose & use of hydrographs in predicting floods and the frequency of occurance of floods.
CASE STUDY: Bangladesh flooding
See slide show below.
Include - Geographical location, physical & human causes, effects & preventative efforts.
Case study notes (password required)
Case Study: Aswan Dam - Egypt
Costs/benefits of the dam
Case study notes (password required)
Case Study: 3 Gorges Dam - China
- Read these links to make case study notes on:
- the purpose,
- costs & benefits of the dam.
- has it been worth the cost & disruption?
Damming the Mekong, Laos building new megadam (BBC)
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
Wetlands: Areas that are regularly saturated by surface water or groundwater, including freshwater marshes, swamps and bogs.
Case Study: Kissimmee River Restoration
Where is the Kissimmee river.
How, why & when was it altered?
Why and how is it being restored? (and at what cost?)
- 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)The Guardian.co.uk - The Andes
Mini-series looking at water shortages in Peru - causes, effects and some ideas about what can be done.The Andes: Retreat of the glacier
bbc.co.uk: Chiles water conflicts between mining & agriculture in the Atacama Desert.
Conflict over water - International Scale
Case Study (password required)
The Nile River Basin
Extra reading: Water Conflict and Cooperation/Nile River Basin (2003)
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.