3.6 Water resources

external image earth-water-tap-supply-thumb4824558.jpg

3.6.1: Describe the Earth’s water budget.

Salt Water
Oceans and Sea

Glaciers and Ice Caps

Freshwater Lakes
Inland Seas
Soil Moisture
Rivers and Streams

Only a small fraction (2.6% by volume) of the Earth’s water supply is fresh water. Of this, over 80% is in the form of ice caps and glaciers, 0.6% is groundwater and the rest is made up of lakes, soil water, atmospheric water vapour, rivers and biota in decreasing order of storage size.

Turnover time: The time it takes for water to completely replace itself in part of the system it is in, this charges from different parts of the systems.

The degree to which water can be looked at as renewable or non-renewable depends on where it is found in the hydrological cycle. Renewable water resources are renewed yearly or even more frequently, however groundwater is non-renewable resource.

external image 400px-Earth's_water_distribution.svg.png

3.6.2: Describe and evaluate the sustainability of freshwater resource usage with reference to a case study.

Irrigation, industrialization, and population increase all make demands on the supplies of fresh water. Global warming may disrupt rainfall patterns and water supplies. The hydrological cycle gives humans fresh water but we are withdrawing water from underground aquifers and degrading it with wastes at a greater rate than it can be replenished

The demand of water has increased in both MEDCs and LEDCs, as populations are increasing as well as agriculture changing and expanding industry. MEDCs need more water as they wash more often, water their gardens, and wash their cars.

Managing water

This can be reached by:
  • making new buildings water efficient (rainwater for sanitation and showers)
  • fitting new homes with more water-efficient appliances (dishwashers and toilets)
  • expand metering to encourage households to use water more efficiently
  • in some rural areas drought resistant crops should be planted to reduce the need for irrigation
  • organic fertilizers cause less pollution and bio-control measures can be used to reduce crop pests

Case study: Murray-Darlin Basin
  • Increase in water demand: increase in population; higher standard of living; agri-business demand; inequality distribution
  • Most water had been used for dry-land agriculture use
  • Agriculture: covers 80% of the Basin and high use of the river
  • Urbanization: increase in chemicals in the river
  • -Land clearing: cleared nature vegetation
  • Irrigation: 60% of its water use is for irrigation
  • Salinity: dominant issue of the river
  • Low water flow: Been reduced by 61%
  • Wetlands disturbed: cause of modernization

external image 320px-Water_cycle.png