Freshwater - Issues & Conflicts

Hydrological cycle

1) Water balance = relationship between inputs and outputs of a drainage basin.

Precipitation = Q (runoff/discharge) + E (evapotranspiration) +/- changes in storage.

2) Stores and transfers of water in the hydrological cycle.

3) Recap water cycle (simple animation),

4) Problem of less water being stored as ice in the water cycle

4) Maximum sustainable yield - what?

"The maximum level of extraction that can be maintained indefinitely for a given area."

water mining - sustainable? sea level?

Global business & water shortages

Middle East running dry?

Key terms: evaporation, transpiration, evapotranspiration, condensation, precipitation,interception, infiltration, percolation, surface runoff, throughflow, baseflow, groundwater.

Drainage Basins

5) Features of drainage basins: source, tributary, confluence, channel, floodplain, mouth, delta, distributaries.

6) River profile & characteristics: upper, middle & lower valley. Bradshaw model. Waterfalls.

7) River discharge: define, measurement (cumecs).

Storm/flood Hydrographs

8) What is a hydrograph? Key characteristics (discharge, rising limb, recessional/falling limb, peak flow, baseflow, runoff, lag time).

9) Factors affecting the hydrograph: basin shape/size, drainage density, human influence, slope gradient, climate, soil type, vegetation,

10) Purpose & use of hydrographs in flood prediction.

Flooding

1) Physical & human causes of flooding.

Dams & Resovoirs

Floodplain Management

• Home
• Erosion
• Transportation
• Deposition
• Bradshaw Model

River Processes

Erosion - Transportation - Deposition

4 main forms of erosion in rivers:

• Hydraulic action: force of water widening cracks & loosening material.
• Abrasion: scraping action of material (stones/rocks etc) in the river as they move.
• Attrition: Stones/rocks breaking into smaller pieces when they collide.
• Corrosion: Rock such as limestone is dissolved by acids in the river water.

4 main methods of transportation of material in rivers:

• Traction: larger stones/rocks are rolled along.
• Saltation: smaller stones/pebbles may bounce along.
• Suspension: much smaller material (sand/soil) can be carried along.
• Solution: disloved material is transported in the water (cant see it).

Deposition in rivers

As rivers flow through floodplains, the flatter land and wider chanel results in a reduced capaity for a river to carry material. This causes deposition.

Heavier materials are deposited first, with the finer silt being carried the furthest.

Features formed by deposition in: braided channels, levees, floodplains, oxbow lakes, deltas.

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

Storm channels through cities

Upstream measures:

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.

Question Paper

Resource Paper

Groundwater Management

Irrigation & Agriculture

1) Irrigation - p.490 (Waugh) define & why used? What are boom & drip irrigation (p.491).

2) Salinisation - p.496 (Waugh) why can irrigation cause salinisation & how can it be managed?

3) Chemicals & eutrophication - p.494 (Waugh) side effects of chemicals on water supplies. What is eutrophication & why is it a problem

nitrate pollution & effect in UK

Conflict over water - National or local scale

1) P.490 Waugh.

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

The Andes: The farmers' struggle

The Andes: Water wars

Peru's water protests halt Machu Picchu tourism

Conflict over water - International Scale

Case Study (password required)

Interactive guide (2010)

The Nile River Basin

Water politics in the Nile Basin

How should the Nile's waters be shared? (2004)

East African nations to challenge colonial Nile treaty (2010)

Egypt cuts water use as Ethiopia dams for power (2010)

Extra reading: Water Conflict and Cooperation/Nile River Basin (2003)

Complete:

Storm hydrograph past paper Q

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]

Guideline to help answer this

Lake Mead & the Hoover Dam

Age of Limits: 21st Century Water Management from Alexandra Cousteau on Vimeo.

Tanning Factories & the River Ganges

Check your knowledge