Water Conservation

Market-based approaches to conservation End government subsidies of inefficient practices – Let the price of water reflect its true cost of extraction – But since industrial uses are more profitable than agricultural uses, poorer, less developed countries suffer Privatize water supplies: construction, maintenance, management, and ownership – May improve efficiency – There is little incentive to provide access to the poor Decentralization of water control may conserve water – Shift control to the local level

Human Impacts on the Hydrologic Cycle Humans change the surface of the Earth: Overgrazing Improper irrigation Cutting down trees Consequences Flooding Erosion Sediment deposition Less infiltration Less rainfall Depleted groundwater Depleted rivers and streams Less evaporation

Dwindling Water Supplies Withdrawing Water Supplies Demand is outpacing supply – Increasing the world population will only make this worse over time Annual global water withdrawal is expected to rise by 10% each decade – Scientists expect wars to be fought over water rights in the near future

Consequences of Overdrawing Groundwater Consequences of overdrawing groundwater Falling water tables and water shortages – Less water for crops, leading to food shortages or higher prices Diminishing surface water – Possible drying up of wetlands, springs, streams, and rivers

Water Resources Over the last century – Human population has increased 3x – Global water withdrawal has increased 7x – Individual water usage has increased 4x – About 1/6 of the world’s population don’t have easy access to safe water 2.6 billion people! Most water resources are owned by governments and are managed as publicly owned resources

Human water needs A person needs about 4-5 gallons water/day for biological needs – In the US each person uses about 188 gallons/day An additional 657 gallons/person/day are used for irrigation, industrial use. Including all agricultural and industrial use, per person total use is about 2000 gal/person/day – If world’s water supply were 100 liters, the usable supply would be about 0.5 tsp US has highest per capita water withdrawal, followed by Canada, Australia, Russia, Japan

Water usage U.S. water use: – 85% of freshwater is used for irrigation Worldwide water usage – 70% for irrigation – 20% for industry – 10% for human use 1.1 billion people do not have regular access to fresh, clean water – 80% of diseases in developing countries are from water-borne pathogens

Where can we get more water? Of all the water on Earth, only 2.5% of it is freshwater – Most of that freshwater is in ice caps or underground—not easily accessible

Possible sources of water Potential alternative sources of water – Oceans – Storm water – Recycled water

Desalination Desalting Ocean Water Desalination—the removal of salts from sea water – Typically uses extremely large amounts of energy, high carbon footprint, and specialized, expensive infrastructure Vey costly compared to the use of fresh water – However, it’s necessary for some countries in order to get enough fresh water (Australia, China, Aruba, Israel)

Storm Water Storm water—Water that comes from precipitation (rain, snow, etc) A good option for countries that experience high amounts of rain or snow – However, it’s not pure, and must be treated before use

Recycled Water Gray water—slightly dirty water from sinks, showers, washing clothes, etc – Gray water can be treated to be used for watering lawns Water-sensitive landscaping is encouraged to cut down on the amount of water required

Water Uses in the USA Average water use in Charlotte, NC—190 gallons per day Common uses – Showers and baths – Washing laundry by hand or machine – Washing dishes by hand or dishwasher – Swimming pool maintenance – Lawn watering – Flushing toilets

Water Stewardship Water Stewardship: – We must realize we have a large impact on the water cycle – We must conserve what we can – We must take responsibility for our actions – We need to plan ahead for the future