water use and management
DESCRIPTION
Water Use and Management. Outline:. Water Availability and Use Freshwater Shortages Water Management and Conservation. WATER RESOURCES. Water, liquid and solid, covers more than 70% of world’s surface. More than 370 billion billion gallons. Hydrologic Cycle. Sources of water. - PowerPoint PPT PresentationTRANSCRIPT
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Water Use and Management
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Outline:
• Water Availability and Use
• Freshwater Shortages
• Water Management and Conservation
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
WATER RESOURCES
• Water, liquid and solid, covers more than 70% of world’s surface. More than 370 billion billion gallons.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Hydrologic Cycle
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Sources of water
Surface fresh water: 3% of liquid fresh water,
which is 13% of all fresh water,which is 2.4% of all water
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Groundwater
Second largest reservoir of fresh water.- Infiltration - Process of water percolating
through the soil and into fractures and permeable rocks.
Zone of Saturation - Lower soil layers where all spaces are filled with water.
Water Table - Top of Zone of Sat.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Groundwater
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Groundwater Aquifer
Technologies for water collection
• Industrialized countries: Drill into aquifers Build dams across rivers to create reservoirs
(hold water in times of excess flow and release water in times of lower flow).
Water is piped to treatment plants. Water is distributed through the water system to
homes, schools, and industry. Water is collected by sewage-treatment plant,
retreated, and sent back out for distribution
Dam Impacts• Fresh water habitats lost, increased salt
concentration, etc. • US: 75,000 dams at least six feet in height,
another 2 million smaller structures.• Around the world: more than 45,000 large
dams (50ft high). 3,000 of these contain storage reservoirs
with volumes greater than 25 billion gallons
Why build dams?
• Combination of flood control, water storage, and hydropower.
Three Georges Dam
Water diversions from rivers
Yellow River (Huang He)In northern China
Three Georges Dam
• Yangtze River in China• Completed in 2006• Largest hydroelectric project in the world• Generates 22,000 MW of electricity• More than 1.2 million people have been
displaced• Critics point to the huge human, ecological, and
aesthetic costs of the dam and claim alternative sources of energy are cheaper
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Diversion of rivers to the Aral Sea
• Once the 4th largest inland body of water in the world
A series of dams was built to irrigate cotton.
• Aral Sea reduced to about 25% of its 1960 volume, quadrupled the salinity of the lake and wiped out the fishery. Pollutants became airborne as dust, causing significant local health problems.
• The environmental damage caused has been estimated at $1.25 -$2.5 billion a year.
Colorado River Deltain U.S./Mexico
US Dam Removal
• 500 dams have already been removed in the US and many await the same fate.
• Pros for removal: reestablish historic fisheries and reestablish the river for recreational and aesthetic value
• Cons: massive sediment from upriver that will be washed downstream; difficult.
US water policy
• No federal US water policy • Clean water act and its subsequent
amendments authorize the US EPA to develop programs and rules to carry out its mandate for oversight of the nation’s water quality.
• EPA does not deal with water quantity.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
U.S. Water Policy
• Through most of US history, water policies have generally worked against conservation. In well-watered eastern states, water
policy was based on riparian use rights. In drier western regions where water is
often a limiting resource, water law is based primarily on prior appropriation rights.
- Fosters “Use it or Lose it” policies.
OK Water Policy• “The Legislature hereby declares that, in order to protect Oklahoma
citizens from increased water supply shortages and groundwater depletions by the year 2060 in most of the eighty-two watershed planning basins in the state as described in the 2012 Update of the Oklahoma Comprehensive Water Plan, the public policy of this state is to establish and work toward a goal of consuming no more fresh water in the year 2060 than is consumed statewide in the year 2012, while continuing to grow the population and economy of the state and to achieve this goal through utilizing existing water supplies more efficiently and expanding the use of alternatives such as wastewater, brackish water, and other nonpotable supplies. Provided, however, that nothing in the Water for 2060 Act shall be construed as amending the provisions of law pertaining to rights or permits to use water.”
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Ogallala Aquifer
High-capacitywellwithdrawals
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Dried-up reservoir
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
WATER AVAILABILITY AND USE
• Renewable Water Supplies Made up of surface runoff and infiltration
into accessible freshwater aquifers. Readily accessible, renewable
supplies are 400,000 gal /person/year.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Types of Water Use
• Withdrawal - Total amount of water taken from a source.
• Consumption - Fraction of withdrawn water not returned to its source.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Quantities of Water Used
• Worldwide, humans withdraw about 10% of total annual renewable supply. Many societies have always treated water
as an inexhaustible resource.• Human water use has been increasing about
twice as fast as population growth over the past century. Average amount of withdrawn worldwide is
about 170,544 gal/person/year.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Global Water Use Growth
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Precipitation Patterns
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Water use
Agriculture
Industry
Household/municipal
How is there not enough?
• If the water cycle is sufficient to provide water for all human needs, why do some go without? Not distributed evenly Scarcity of water in many parts of the
world Deficit in infrastructure Expanding populations
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
FRESHWATER SHORTAGES
• Estimated 1.5 billion people lack access to an adequate supply of drinking water. Nearly 3 billion lack acceptable sanitation.
• A country where consumption exceeds more than 20% of available, renewable supply is considered vulnerable to water stress.
How can we make water use sustainable:
1. Capture more runoff2. Gain better access to groundwater aquifers3. Desalt seawater (microfiltration/reverse
osmosis)4. Conserve present supplies by using less
water. (drip irrigation)
Municipal water conservation
• Flushing 3-5 gallons• Showering 2-3 gallons per minute• Laundry 20-30 gallons per load• Conserve: fix leaky faucets, low-flow
shower heads and faucets, replace lawns with xeriscaping, ban use of water during draughts, gray-water recycling.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Typical US Household Water Use
Xeriscaping
• Landscaping with desert species that require no extra watering (lawn replacement)
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Depleting Groundwater
• Groundwater is the source of nearly 40% of fresh water in the US. On a local level, withdrawing water faster
than it can be replenished leads to a cone of depression in the water table,
- On a broader scale, heavy pumping can deplete an aquifer.
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Depleting Groundwater
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Depleting Groundwater
• Withdrawing large amounts of groundwater in a small area causes porous formations to collapse, resulting in subsidence.
Sinkholes form when an underground channel or cavern collapses.
Saltwater intrusion can occur along coastlines
Cunningham - Cunningham - Saigo: Environmental Science 7th Ed.
Saltwater Intrusion