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4.2. ACCESS TO FRESH WATER (water as a critical resource (1.1 billion…
4.2. ACCESS TO FRESH WATER
Knowledge and Understanding
supplies of fresh water are unevenly distributed - can lead to conflict and concerns over water security
fresh water sources can be sustainably managed using a variety of approaches
Freshwater supplies may become limited due to contamination and unsustainable abstraction
Climate change may affect rainfall patterns and further affect access to water
Water supplies can be enhanced through reservoirs, redistribution, desalination, artificial recharge of aquifers, and rain water harvesting - water conservation (including grey water recycling) can help reduce demand but often requires a change in attitude by water consumers
water as a critical resource
1.1 billion people live without clean drinking water
2.6 billion lack adequate sanitation
1.8 million people die ever year from diarrheal diseases
3900 children die every day from water borne diseases
1300 l : 1 kg of beef
most water is saline and desalinisation is possible but expensive and only feasible in wealthy countries which are near the sea and water stressed e.g. Aus or Saudi Arabia - costs in terms of energy (especially burning fossil fuels) may not be worth it
salt is also a byproduct left over so making the seas denser and possibly damaging ocean bottom ecosystems
Sustainability and fresh water usage
Sustainable use - allows full natuural replacement of the resources exploited and full recover of the ecosystems affected by their extraction and use
sources of fresh water
surface fresh water - rivers, streams reservoirs and lakes
underground aquifers - porous rock - years to generate therefore can never be used sustainably
human population is increasing and average quality of life is improving - increased freshwater use leads to water scarcity and water degradation
Issues related to freshwater use
climate change may interrupt rainfall patterns - can change monsoon rains and cause further inequality of supplies
low water levels in rivers and streams - e.g. Colorado river
Slow water flow in the lower courses of rivers results in sedimentation - makes already shallow river even shallower - could extend deltas further out into the sea
Underground aquifers are being exhausted - simply means that the aquifer can not be used anymore which strongly affects agriculture. - Buildings can also be damaged when the soil is shrinking because the water has been taken away
Fresh water becomes contaminated and therefore unusable
Irrigation often results in soil degradation especially in dry areas - most of the water evaporates before it is absorbed by crops so dissolved minerals stay at the top of the soil making it too saline - salinisation
Fertiliser and pesticide use can often pollute streams and rivers
Industries and electricity plants release warm water into rivers - warm water can hold less dissolved oxygen than cold so marine animals that take oxygen from the water are negatively affected
Solutions
increase fresh water supplies by
reservoirs
redistribution
desalination plants removing salt from sea water
rain water harvesting systems - large and small scale
artificially recharging aquifers
reduce domestic use of fresh water by using more water efficient showers, dishwashers and toilets
wash cars in car washes with a closed water system - not in the street - also reduces pollution by oil
grey water (water from shower, baths, household laundry, sinks etc) recycling - e.g. for garden irrigationn
drought resistant crops to reduce the need for irrigation
reduce the amount of pesticide and fertiliser used, and replacing chemical fertilisers with organic ones
Water wars
scarcity of water resources can lead to conflict between human populations especially where sources are shared