Water Resources Use it Wisely

Available Freshwater for Use

Water is an Economic Issue 1. Necessary for reducing poverty 2. Necessary for producing food & energy 3. Women & children in less developed countries carry water 4. ~ ½ of world population does not have running water

Environmental Issues of Water Usage 1.Excessive use from aquifers lowers water table 2.Excessive use from rivers decrease river flow 3.Shrinking lakes 4.Disappearing wetlands Only 0.024% of freshwater is available for use.

Groundwater Recharge 1.Precipitation seeps into ground 2. Percolates through layers of soil, gravel, & rock until it reaches impenetrable layer of rock

Water Table 1. Below a certain depth, water fills all the pores in the soil. This is known as the saturated zone. The top of the saturated zone is called the water table. The water table rises and falls with seasonal changes in precipitation. 2. Recharge: portion of the water that falls as precipitation infiltrates into the ground and becomes groundwater. The area where permeable soil allows water to seep into the ground is known as the recharge area.

Global water use has changed over time. What does this graph tell you about water withdrawal and consumption since 1900?

Water Hotspots 1.95% of US freshwater is underground 2.Ogallala aquifer 800-mile long stretches from TX to S Dakota provides an ~ ⅓ of all US irrigation water. formed over millions of years has since been cut off from its original natural sources and is being steadily depleted. Farmers in North TX are moving away from irrigation intense crops

Leading Factors of Water Scarcity 1. Dry climate 2. Drought 3. Overpopulation 4. Wasteful use of water

China’s Water Problem 1.China has 7% of the world’s potable water but must feed 20% of the world’s population 2.Meanwhile, people in China are living longer and eating more, especially more water intense food such as meat and dairy products.

Advantages of Pumping Water from Aquifers 1. Groundwater can be removed as needed year round. 2. Groundwater is not lost by evaporation 3. Groundwater is less expensive to develop than surface water systems 4. Useful for drinking & irrigation 5. Exists almost everywhere 6. Renewable if it is not over- pumped or contaminated

Disadvantages of Using Groundwater 1. Using groundwater faster than it is replenished results in:  Aquifer depletion  Lowering of the water table  Aquifer subsidence  Saltwater intrusion  Drawing chemical contamination in groundwater into wells  Reduces stream flow  Agricultural, industrial, and septic tanks can contaminate ground water

Aquifers 1. An aquifer is a body of saturated rock through which water can easily move. must be permeable & porous ground water has to squeeze through pore spaces of rock & sediment to move through an aquifer ground water may flow through an aquifer at a rate of 50 feet per year or 50 inches per century water will eventually discharge or leave an aquifer and must be replaced by new water to replenish or recharge the aquifer aquifers are natural filters that trap sediment and other particles (like bacteria) & provide natural purification of the ground water flowing through them

Aquifer Water Usage 1. ½ of world’s drinking water comes from aquifers 2. Almost all of drinking water in rural area in US get drinking water from aquifers 3. 1/5 of drinking water for US urban areas comes from aquifers 4. 37% of water for irrigating crops comes from aquifers

Aquifer Depletion

Falling Water Tables 1. Rate of water use (most from irrigation) is greater than natural recharge from rainwater and snowmelt 2. Result is the level water table gets lower and lower every year 3. When water table falls to low, we have to drill deeper and deeper wells (expensive) & not everyone can afford this

Subsidence 1. The basic cause of land subsidence is a loss of support below ground. 2. Sometimes when water is taken out of the soil, the soil collapses, compacts, and drops 3. Land subsidence is most often caused by human activities, mainly from the removal of subsurface water 4. Damages roadways 5. Damages water and sewage lines 6. Damages building foundation

Subsidence in US Subsidence has caused a lowering of the land in New Orleans, which makes flooding more dangerous for the area

Other Effects of Groundwater Over- pumping Sinkholes form when the roof of an underground cavern collapses after being drained of groundwater.

Saltwater Intrusion 1. Salt water intrusion occurs in coastal freshwater aquifers  different densities of both the saltwater and freshwater allow the ocean water to intrude into the freshwater aquifer. 2. These areas are usually supporting large populations; groundwater withdrawals from these aquifers is exceeding the recharge rate.

Provides water for year-round irrigation of cropland Flooded land destroys forests or cropland and displaces people Large losses of water through evaporation Provides water for drinking Downstream cropland and estuaries are deprived of nutrient-rich silt Reservoir is useful for recreation and fishing Risk of failure and devastating downstream flooding Can produce cheap electricity (hydropower) Downstream flooding is reduced Migration and spawning of some fish are disrupted Dams and Reservoirs

1.Description: a dammed stream that can capture & store rainwater and snow melt 2. Benefits: hydroelectric power, provides water to towns, recreation, flood control downstream 3. Problems: Reduces downstream flow; prevents water from reaching the sea (Colorado River) devastates fish life; reduces biodiversity. Dams and Reservoirs

The Goats

Colorado River Basin 1. It includes some of the driest land 2. Only a modest flow of water 3. Legal pacts between US & Mexico allocate more water for human use than the river can supply 4. Since 1960, river has rarely flowed all the way to the Gulf of California 5. River receives huge amounts of polluted water from urban areas, animal feedlots, and industries

Fig , p. 325 Center pivot Drip irrigation Gravity flow (efficiency 60% and 80% with surge valves) Above- or below- ground pipes or tubes deliver water to individual plant roots. Water usually comes from an aqueduct system or a nearby river. (efficiency 90–95%) (efficiency 80%–95%) Water usually pumped from underground and sprayed from mobile boom with sprinklers.

Flood Irrigation How it works:  Water is obtained from groundwater well or surface water source  Water flows by gravity through unlined ditches in crop fields so crops can absorb it Advantages:  Low tech & inexpensive  Can be used by poor farmers Disadvantages:  Delivers much more water to area than needed  40% of water is lost through evaporation, seepage, and runoff 97% of China’s irrigated land is through flood irrigation There is a danger of creating salinity in the soil in the ridges between furrows.

Center Pivot Irrigation System How it works  Uses pumps to spray water on crops; 80% efficient  Low pressure and low energy precision application systems; 90-95% efficient Advantages  Less water waste  Ensures water gets to crop Disadvantages  Requires technology that no all farmers can afford

Drip or Trickle Irrigation How it Works  Perforated plastic tubes installed at or below ground level  Small pinholes in tubing delivers drops of water at slow, steady rate close to roots of individual plants Advantages  Most efficient way to deliver water in small amounts to crops; 90-95% of water reaches crop  Lees problem of creating saline soil Disadvantage  Technology is very expensive; most farmers cannot afford  Only use on 4% of US crops 66% of Israel & 90% of Cyprus water crops with Drip / Trickle irrigation systems

INCREASING WATER SUPPLIES BY WASTING LESS WATER 1. Sixty percent of the world’s irrigation water is currently wasted, but improved irrigation techniques could cut this waste to 5-20%. 2. Center-pivot, low pressure sprinklers sprays water directly onto crop. –It allows 80% of water to reach crop. –Has reduced depletion of Ogallala aquifer in Texas High Plains by 30%.

Groundwater Depletion: Prevention and Control

1. Description: Removing salt from salt water, commonly by reverse osmosis 2. Benefits: Freshwater 3. Problems: Uses lots of energy; expensive, what do we do with the salt? 4. Who uses Desalination?  In developing countries: most important users of desalinated water are in the Middle East; 6% of world’s capacity  In developed countries: US (California & Florida) 6.5% of total water Desalinization Parameters for saline water: Fresh water - Less than 1,000 ppm Slightly saline water - From 1,000 ppm to 3,000 ppm Moderately saline water - From 3,000 ppm to 10,000 ppm Highly saline water - From 10,000 ppm to 35,000 ppm ****** ocean water contains about 35,000 ppm of salt.

Reducing Water At Home 1. Greywater: water from your bathroom sinks, showers, tubs, and washing machines. 2. It is not water that has come into contact with feces, either from the toilet or from washing diapers. 3. Use it to water ornamental plants or fruit trees. 4. Greywater can be used directly on vegetables as long as it doesn't touch edible parts of the plants 5. Use all-natural, biodegradable soaps (salt-free liquid soaps) whose ingredients do not harm plants.

Indoor Water Use 1. In the US, an average family of four uses 400 gallons of water every day 2. Older toilets use between 3.5 and 7 gallons of water per flush. 3. A leaky toilet can waste about 200 gallons of water every day. 4. A bathroom faucet generally runs at 2 gallons of water per minute.  Turning off the tap while brushing your teeth or shaving, a person can save more than 200 gallons Flushing toilets uses the most water

Who has Access to Clean Water?

Overview of Clean Water Act The objective of the CWA is to restore and maintain the chemical, physical, and biological integrity of the nation's waters by preventing point and nonpoint pollution sources, providing assistance to publicly owned treatment works for the improvement of wastewater treatment, and maintaining the integrity of wetlands.

Standards Standards for water quality are set by the EPA. Water quality standards can vary from state to state.