Chapter 11-Water Water Resources
Water • “Water Planet”- Earth has an abundance of water in all forms: solid, liquid, and gas. • Renewable resource because it is circulated in the water cycle. • Humans can only survive a few days without water. • Two kinds of water on Earth: • Fresh water- Can drink because it contains little salt. • Salt water- Ocean water with a high concentration of salt.
Global Water Distribution • 97% salt water • 3% fresh water • 77% of fresh water frozen in icecaps and glaciers • 22% ground water • 1 % other
Global Water Distribution • Surface water- Fresh water on Earth’s land surface. • Lakes, rivers, streams, and wetlands • River systems- Flowing network of water comprised of streams and rivers. • Amazon river system- largest in the world • Watershed- Area of land that is drained by a river.
Global water Distribution • Ground Water- Water stored beneath the Earth’s surface in sediment and rock formations. • Water table- Level where the rocks and soil are saturated with water • Aquifer- Underground formation that contains water • Porosity- Amount of space between the particles that make up a rock. • Permeability- The ability of rock or soil to allow water to flow through it. • Permeable- Allows the flow of water. • Impermeable- Does not allow the flow of water.
Ground Water- Cont’d. • The Recharge Zone- The area of the Earth’s surface where water percolates down into an aquifer. • Wells- A hole that is dug or drilled to reach groundwater
Chapter 11-Water Water Use and Management
Global Water Use • Most freshwater used globally to water crops. • 19% of global water use for industry • Only 8% of global water used for washing and drinking.
Residential Water Use • Striking differences among countries around the world • U.S. residents use on average 300 L of water per day • Indian residents use on average 41 L of water per day
Water Treatment • Potable- Safe to drink. • Treatment must remove elements: mercury, arsenic, and lead • Found in polluted and ground water • Pathogens- Organisms that cause illness or disease • See Figure 6, Pages 276-277
Industrial- 19% of water use in world Manufacture goods Dispose of waste Generate power Most used to cool power plants Agricultural- 67% of water use in world 80% of water used in agriculture evaporates Irrigation- Method of providing plants with water from sources other than direct precipitation. Water Use
Water Management Projects • Aqueducts- Huge canals that brought water from the mountains to dry areas. • Dams and water diversion canals used today. • Water management projects today: • Bring in water to make a dry area habitable • Create a reservoir for recreation or drinking water • Generate electric power
Water Management Projects • Water Diversion Projects- To supply dry regions with water, all or part of a river can be diverted into canals that carry water across great distances.
Water Management Projects • Dam- Structure built across a river to control the river’s flow. • Can be used to generate electricity. • Problems: flooding, ecosystem destruction, and dam failure • Fertile sediment builds up behind dams • Reservoir- Artificial lake formed behind a dam.
Water Conservation • Water becomes more expensive as it depletes. • Agriculture: Most water loss from evaporation, seepage, and runoff • Drip Irrigation System- Small amounts of water delivered directly to roots using perforated tubing.
Water Conservation • Home: • Water-saving technology such as low-flow toilets and shower heads • Water lawns at night • Xeriscaping- Designing landscapes that require minimal water use. • Industry: • Recycling of cooling water and wastewater • City wide/company wide water saving plans
Solutions for the Future • Desalination- Process of removing salt from salt water • Heats water and collects evaporation • Middle East/Kuwait has desalination plants • Transporting Water • Transporting in bags and/or large plastic containers from abundant supplies to low supplied regions • Towing icebergs??
Chapter 11-Water Water Pollution
Water Pollution • The introduction of chemical, physical, or biological agents into water that degrade water quality and adversely affect the organisms that depend on the water.
Types of Water Pollution • Nonpoint-source Pollution • Pollution that comes from many different sourecs • Difficult to identify and trace/regulate and control • 96% of polluted water in U.S • Point-source Pollution • Pollution discharged from a single source • Can be identified and traced • .
Wastewater • Water that contains waste from homes or industry. • Treating • Most contaminates are biodegradable • Some toxic substances cannot be removed by standard treatment
Wastewater • Sewage sludge • Solid material that remains after treatment • Sometimes hazardous waste • Often incinerated and ash buried • Can be used as fertilizer or bricks
Eutrophication Containing an abundance of nutrients Leads to swamp or marsh Artificial Eutrophication- Sewage and fertilizer runoff enhances Ex: Algal blooms Thermal Pollution- Increased temperature of water sources caused by factories and industries cooling systems Decreases oxygen levels Kills organisms Water Pollution
Groundwater pollution- Polluted surface water percolates down to groundwater Leaking underground storage tanks are large problem Remains for 100s to 1000s of years Ocean pollution Coastal ecosystems most affected Legal to dump in some parts of ocean Oil spills 5% of ocean pollution Nonpoint-source pollution from land 10 times more than tanker spills Water Pollution
Biomagnification- Accumulation of pollutants at successive levels of the food chain. Many pesticides Example: DDT and the Bald Eagle Clean Water Act of 1972- To restore and maintain the chemical, physical, and biological integrity of the nation’s waters. Goal to make fishing and swimming safe by 1983. Not achieved 30% increase Opened door for more legislation Water Pollution