4.2 Notes Access to freshwater

Uses for freshwater:

• domestic purposes

• agriculture

• industry

• power

• transportation

• marking boundaries

Contamination limits fresh water supply. Industries and electricity plants release warm water into rivers and lakes. Warm water holds less dissolved oxygen, so aquatic organisms are negatively affected.

Unsustainable extraction limits fresh water supply. With the rigs, there is les surface water available. It also slows water flow due to sedimentation.

Unsustainable abstraction (depletion of natural aquaphors) limits fresh water supply. It takes away the natural water storage underground, pumped out faster than it can naturally replenish. Can also cause the land to sink with less aquaphors supporting it.

Irrigation limits fresh water supply. Uses large quanitites of water while being highly ineffcient. Much is lost due to evaporation or doesn’t hit the desired plants. Irrigation often leads to soil degradation. After water evaporates, dissolved minerals from the water are left behind and can make it too saline for future agriculture there, causing salinization.

Strategeis to increase freshwater supplies include reservoirs and redistribution.

Desalination plants are able to enhance water supplies.

Pros:

• Salaination: removing salt from water

• Can create create freshwater

Cons:

• Very costly

• kills organims

• creates briny wastewater

Irrigation techniques can help enhance water supplies.

• selecting drought resistant crops canr educe the need for irrigation

• closed pipes instead of open canals

• trickle systems instead of sprayign water

Other water conservation techniques:

• greywater systems

• using water-efficient appliances

• rainwater harvesting systems

• naturally recharging aquaphors