Water Sources Increasing Water Availability Water Uses Future of Water Water Resources Water Sources Increasing Water Availability Water Uses Future of Water

Water Sources

Water Sources Water is abundant but usable water is rare. Of the portion of water that is freshwater, ¼ is below groundwater, less then ¾ is locked in ice, glaciers, the atmosphere and in the soil. Therefore, less than one percent is accessible for human use. Freshwater Initiative

Groundwater Aquifers are sources of usable groundwater. Unconfined aquifers are rapidly recharged by water that percolates downward from the land surface. The water table marks the upper limit of the aquifer. Confined aquifers are capped by an impermeable layer of rock or clay, which can cause water pressure to build up underground. Artesian wells are formed when a well is drilled into a confined aquifer and the natural pressure causes water to rise toward the surface.

Groundwater Recharge Groundwater recharge is through precipitation percolating through soil. Confined aquifers can be recharge through openings in the land called recharge areas. It generally takes 10,000 – 20,000 years to recharge. The rate of recharge is dependent on geology and precipitation rates, and affects the long term availability for water.

Ogallala Aquifer Groundwater of the world The Ogallala aquifer in the Great Plains The largest aquifer in the U.S. A confined aquifer with slow recharge Predicted, at currents rates of water withdrawal and recharge, to run out of water this century Waters most of our ‘breadbasket’

Impacts on Groundwater When water is rapidly withdrawn the following may occur: Cone of depression – region is which there is no longer any groundwater, causing the main well and surrounding wells to dig deeper to obtain water Saltwater intrusion – occurs with water is rapidly withdrawn from aquifers that are adjacent to coastlines. As water is withdrawn, the pressure in the aquifer is reduced allowing for the infiltration of saltwater in the region.

Surface Water Surface Water of the World Civilizations typically settled along the banks of rivers because of transportation, fertile soils of the floodplains. Largest rivers by volume include the Amazon, the Congo and the Yangtze Lakes are classified by their nutrient loads: Mesotrophic, oligotrophic and eutrophic Largest lakes include (in order by volume): Caspian Sea (salty lake), Baikal, Tanganyika,Superior, Michigan, Huron, Victoria Wetlands Absorb and retain water, act like a spnge/filter Largest is the Pantanal of Brazil, followed by the Everglades

Atmospheric Water Atmospheric water is essential to the distribution of water across the globe. Under drought situations, heavy rainstorms can create flashfloods. These floods may also be created by increases in impermeable surfaces.

Water uses

Water Uses On average it is estimated that 70% of freshwater is used for agriculture, 20% for industry and 10% for household uses. Over the past 50 years, agriculture output has kept up with the human population but the water use has more than doubled. In the U.S., 1/3 of freshwater is used for agriculture

Irrigation The greatest potential for conserving water is by changing irrigation practices Irrigation techniques include: Furrow – easy and inexpensive. Trenches are filled with water that seeps through the soil. Has 65% efficiency. Flood – floods the entire field; more disruptive to plant growth. Has 70-80% efficiency Spray – more expensive and energy consuming; sprinkler devices are used to spray water across fields. Has 75-95% efficiency Drip – water is slowly dripped from a hose; reduces weed growth Has 95% efficiency. Hydroponic agriculture – uses up to 95% less water

Industrial Uses Water is required for Generating electricity (in U.S. 50%) Cooling machinery Nuclear reactors and power plants; can cause thermal pollution Refining materials 116 gallons (440 L) per 1 kg of copper Paper production Requires 33 gallons (125 L) per 1 kg of paper

Household Uses Indoor uses Outside Toilet Laundry Bathing Faucets Leaks Cooking and drinking Outside Watering lawns Washing cars Swimming pools

Increasing Water Availability

Levees An enlarged bank built up on each side of a river Prevents flooding into floodplains where humans have established residency and industry Reduced fertility of floodplains Sediments are not deposited throughout the length of the river but at the mouth of the river Force greater flooding downstream Encourages development in floodplains

Dikes Similar to levees but are typically built to prevent the ocean from flooding adjacent land Common in Europe Pumps water back out to the ocean. Originally powered by windmills

Dams A barrier that runs across a river to control the flow of water Water that collects behind the dam (upstream) is called the reservoir Dams hold water for human consumption, energy generation (hydroelectric power), flood control and recreation. There are approximately 845,000 dams in the world and 82,642 in the U.S. In the U.S., most dams were constructed for flood control and recreation (~56%)

Financial, social and environmental costs Ex. Three Gorges Dam across the Yangtze River Took 13 years to construct, 2 years to fill with water Displaced 13 cities, 140 towns, 1350 villages and forced 1.3 million people to relocate Increased pollution and effects of eutrophication

Dams Interrupts the natural flow of water Blocks migration of fish like salmon, which can have a cascading effect on the other organisms that depend on them. Reduces water flow down stream Shifts seasonal flooding as operators release excess water Concentrations pollution in the reservoir

Aqueducts Canals, channels or ditches that carry water to a new location Can lose as much as 55% of the water through evaporation New York (Catskills) and L.A. (Colorado river) rely on aqueduct for water Construction fragments habitats May be built underground to reduce water loss Diverts water from natural course

Water Diversion Projects China Diversion of water from Bangladesh to India India will gain 170 billion liters of water a year May increase movement of saltwater upstream of estuaries Reduce flow severely restricting habitat downstream Aral Sea Diversion by USSR in ‘50s (Kazakhstan/Uzbekistan) Increased salinity in Aral sea due to reduced freshwater input Surface area reduced by 60%, increased dust storms, erosion and pesticide residues Affected climate, summers are hotter and winters are colder

Desalination Processes that remove salt to obtain freshwater 50% of the water in the Middle East is produced by desalinization Distillation – uses heat to boil water, leaving salts behind, and then capture and condense the steam. Reverse osmosis – Pressure is applied to push water through a semipermeable membrane which leaves salt behind. More efficient and often less costly then distillation, however, waste brine can contaminate region

Water Availability Varies greatly around the world Middle East and North Africa represent 5% of the world’s population but have less than 1% of the world’s freshwater 1.2 billion people live in regions with scarce water Water Burden

Future of Water

Water Ownership Who has rights? Regional and national government Private and public ownership Conflicts are created over water rights Bangladesh-India Iran-Iraq Florida-Georgia Arizona, New Mexico, California, Mexico Chile and free-market systems

Water Conservation Federal standards were set in 1994 for improved efficiency: Double flush toilets Reduce volume toilets Reduced flow showerheads Front-loading washing machines High efficiency washing machines Xeriscaping of land Recycling of water (gray water systems) Treated wastewater for drinking water

Protecting Wetlands Wetlands provide many vital ecological and economic services The U.S. has lost up to 80% of wetlands since 1962 to today. To reduce loss, mitigation banking was put into effect Wetlands may be destroyed as long as an equal area of the same type of wetland is created or restored

Florida Everglades U.S. Army Corps of Engineers straightened the Kissimmee River in 1960’s to provide ample water to growing cities and agricultural lands Ag lands led to increased P in the everglades leading to eutrophication Decreased flow of water led to increased wildfires, loss of habitat and biodiversity (90% of the birds, 75- 95% of turtles) $7.8 billion and 20 years later restoration began …but is still fighting big sugar and anti-environmental movements

Protecting Rivers and Lake Lakes Invasion by non native species (zebra mussels, asian carp) Eutrophication Water diversions Filling-in for development Rivers Damming Interfer with migratory fish, esp. salmon Diversions