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How can we increase freshwater supplies for a growing human population?
• Distribution of water on earth, amount of fresh water available?
• U.S. water use, how much, what for
• Unequal Distribution: floods and scarcity
• Reasons for fresh water shortages?
• Some technological solutions to water shortages (Pros and Cons):
• Water Pollution: general definition, analysis, source, major types of water pollution
6 Technological Solutions to “Water Scarcity” or shortages
1. Extract Groundwater
2. Build Dams and Reservoirs to store runoff
3. Bring in surface water from other areas: Watershed Transfer 4. Desalination
5. IPR (Indirect Potable Reuse)
6. Improve Efficiency of Water Use
Zone of aeration, saturation , water table
Ground Water
Aquifers and Aquicludes
Porosity and Permeability
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Zone of Recharge, Zone of Discharge and Artesian Conditions
River Water moves ~meters/sec
Groundwater Flow Rates vary: ~1mm – 1 Km per day
How much groundwater is moving?
Q=KIA, or Q=K*Head*A, or Q=K*Rise/Run* Area K=permeability coefficient or “hydraulic conductivity" , Zone of Discharge, Flow Rates and Artesian Conditions
Cone of Depression
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Cone of Depression
Original
water table
Initial water table
Cone of
depression
Ogallala Aquifer
~450,000km2
Named in 1898 after it’s “type locality” in Ogallala Nebraska.
SOUTH DAKOTA
holds ~3,608 Km3
In some places, water is pumped
out 8 – 10 times faster than
recharge rate. ~30% of all ground water
used for irrigation in US.
WYOMING
Deposition of material occurred between ~30 – 2 million yrs BP. Consists of coarse and fine grain sedimentary rock and sediments.
NEBRASKA
KANSAS
COLORADO
Most of the water came from melting of the last glacial max, 5,000 – 10,000 yrs ago.
Provides drinking water for ~82% of
people living within the area
Between 1980 to present, rate of drop has decreased in areas due better irrigation, wind breaks, crop rotation, terracing.
OKLAHOMA
In 2000, irrigation withdrawals
were ~17 billion gal/day!
NEW MEXICO
Less than 61 meters (200 ft)
61-183 meters (200-600 ft)
More than 183 meters (600 ft)
(as much as 370 meters or 1,200 ft.
in places)
Groundwater
Overdrafts:
Lowered
water table
TEXAS
0
100
0
160
Kilometers
Some areas have been rising.
The Ogallala Aquifer
Subsidence:
High
High
Moderate
Moderate
Minor or none
Minor or none
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Salt Water Intrusion
9 meters of subsidence
in ~52 years, 1925 – 1975
Since late 1970’s
subsidence decreased
to <1m due to reduced
groundwater pumping
• Often problematic in coastal aquifers
– Rate of pumping > rate of recharge
– Inland water table drops
– Seawater begins to fill in voids – Solutions?: dig deeper wells, move well locations, watershed transfer or find other source, use less water?
In Ca: ~17 million acre feet of water are pumped per year (afy)
( 1 acre foot ~ 325,851 gallons)
~1.3 million afy of overdraft
Source SQWD
Summary
Advantages / Disadvantages of Extracting Groundwater
• Year round use
• Provides drinking water for over 2 billion people, >1 billion people in Asia
• No evaporation, responds less to dry seasons
• Often less expensive to develop than surface water systems
• Potential problems caused by overuse
– Water table lowering, “overdraft”, increases cost to “mine” aquifers – Crustal or “Fluid Loss” subsidence
– Chemical contamination of groundwater
– Reduced stream flow
– Salt water intrusion
How can we increase freshwater supplies for a growing human population?
6 Technological Solutions to Water Scarcity:
1. Extract Groundwater 2. Build Dams and Reservoirs to store runoff
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Why Build a Dam?
PROS:
• Hydroelectric Power / Provide Electricity / Improve Economy decrease dependence on coal / nuclear
China’s “3 Gorges Dam” on Yangtze River
Longest river in Asia, 3rd longest in world
#1) Nile, #2) Amazon #4) Mississippi
• Provide New Fishing Industry / Improve Economy
• Provide Water for Human Consumption
• Flood Control / Reduce Downstream Flooding
• Provide Water for Irrigation / Increased Food Production
• Provide Recreation / Swimming, Boating, Fishing
China’s “3 Gorges Dam” on Yangtze River Pros
• Reduced the dependence on Coal
• Generates ~10% of China’s electricity, = to ~10 Hoover Dams, or enough to power a city 10X as large as LA!
• Help reduce CO2 emissions, fewer coal burning plants
• Reduce flooding; over 500,000 have been killed by floods on the Yangtze River in last 100 years, 4,000 in 1998
• The cost of damage from the 1998 flood equals the cost of the dam
• Increases irrigation for cropland below dam
• Increases rivers shipping capacity
Why Build a Dam? CONS:
China’s “3 Gorges Dam” Cons
• Cost is at least 26 billion
• Expensive to build, danger of collapse, seismic issues, many built long ago. Since 1949, >3,200 dams in China collapsed killing several 100,000 people
• Displaced over 1.24 million people, 1,350 villages and cities, many with archeological sites
• Loss of water through evaporation
• Floods large areas of croplands and forests
• Loss of biodiversity; sardines, mackerel, shrimp, lobster industry loss in Egypt, 17 of 47 fish species left in Nile, loss of ~30,000 jobs
• Created a 600 km long reservoir that will collect waste, untreated sewage, sediment and cause crustal subsidence (SF to LA ~ 600Km)
• Deltas receive less sediment and coastal erosion occurs, i.e. Nile and Mississippi River Delta
• The large reservoir is eroding shorelines, causing slope instability / landslides along edge of reservoir
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China’s “3 Gorges Dam” Cons
• It’s built on a seismically active area, ~80 small cracks already discovered, risk of dam breaking?
• Disrupts spawning and migration of some fish downstream
Sierra de la Laguna, near the town of Miraflores
Other dams completely filled with sediment in Ca:
San Clemente Dam on Carmel River
Gibraltar Dam on Santa Ynez River
Matilija Dam on the Ventura River
Rindge Dam on Malibu Creek
• Releasing lots of methane
• Farming regions below dam will not receive nutrient rich sediments from floods
• Lack of sediment in delta cause saltwater to move inland
Aswan Dam was
completed in 1970.
Located ~600 miles
south of Cairo.
Dam enables year
round irrigation which
also contributes to a
regional rise in water
table.
Aswan dam displaced
~125,000 people
Fertilizers, pesticides,
soil additives needed.
Costs: ~100 million/yr,
uses up much of the
hydroelectric energy
created from the dam.
Mississippi River Delta
~40% of all coastal wetlands in US, ~35 Sq miles lost per year on avg
The height of a storm surge is reduced by ~1 foot for every 3 Sq miles of marsh that it crosses. (3 mi2 = 1,920 acres) Over 1.2 million acres or 1,875 mi2 have already been lost
Mississippi River discharges
~3.7 million gal/sec into
the Gulf of Mexico
The sediment supply
has Decreased ~50%
in last 100 years
Dams and artificial levees
ultimately lead to erosion.
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Dams & the Mississippi River Delta
• Further loss of delta and salt marsh comes from “diking, draining and filling” for agriculture, industry and residential
• compaction, subsidence, SL rise & wave erosion VS deposition or “sedimentation”
Currently: ~11‐13mm/yr……. VS ~5.9‐7.5 mm/yr……
• Solutions: “Move the Mississippi”
Web Link http://www.usatoday.com/news/nation/2005‐11‐21‐wetlands‐
restoration_x.htm (for over 3 billion $$) (geologist Sherwood Gagliano)
• Re‐channel / redirect sediment to starved areas, Stop draining / filling, establish zoning of coastal areas, Build dams / retaining walls to prevent saltwater flooding of freshwater marshes
Dams and Development
year
1900
# of dams 0
>15m high
worldwide
1950
5270
1980
36,562
1998
47,655
(China
22,000)
• Developed countries
– some new dams planned; many dams being decommissioned; in US decommissioning>construction
compaction, subsidence, SL rise & wave
erosion VS deposition or “sedimentation”
Klamath River Dams
• Four dams on the Klamath River (J.P.Boyle, Copco 1 & 2 and Iron Gate) are all coming down…….. Starting in 2020. “World’s biggest dam removal project…”
Dams supply enough electricity for 70,000 homes
• Future challenges: ecosystem disruption, salmon restoration • To Help Salmon, 4 Klamath Dams Coming Down
• Developing countries
– Many new large dams under construction for irrigation, flood control, hydropower, water supply
– India, China, Turkey, Iran and Indonesia, Japan are currently most active dam building countries
Dams in California, some #’s about SAND
16,000 mi2
11-13mm/yr VS 5.9 – 7.5mm/yr
Read this after class
•
of states coastal watersheds are effected by dams.
• Flow of sand to beaches has been reduced by ~25% or 3.6 million Yds3/yr or 360,000 dump trucks/yr
• Total sand trapped behind Ca’s coastal dams is ~ 200 million Yds3, which = to a line of dump trucks bumper to bumper around the word 4 times. Varies with location: ~5% in northern Ca, 31% in central Ca and 50% in southern Ca.
• Effects of beach widths??? Not that much in So Ca. Coastal engineering structures (dredging new marinas, construction on dunes) has led to 170 million cubic yards of new sand between 1930 ‐ 1993 (2.7 million Yds3/yr) between Santa Monica and San Diego. • Engineering + wave climate (El Nino / La Nina) partially overshadows reduction of sand from dam construction. http://www.seattlepi.com/national/article/To‐help‐salmon‐4‐Klamath‐dams‐
coming‐down‐883692.php Web Link
• Tearing Down The Elwah River Dam
(ended 3/12) Web Link
http://seattletimes.com/html/localnews/2021975641_elwhariverxml.html
How can we increase freshwater supplies for a growing human population?
6 Technological Solutions to Water Scarcity:
1. Extract Groundwater 2. Build Dams and Reservoirs to store runoff
3. Bring in surface water from other areas: Watershed Transfer
Long history: Asia, Middle East, Roman Empire (38mill gal/day), CA, politics, power, greed, pop growth, ecosystem disruption
PROS: development, (humans living in cities) can help control flooding, provide water for industry, agriculture, domestic use, source: Gary Griggs
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Pont Du Gard Aqueduct, France
Roman Empire, ~2,000 years old,
~51 kilometers long, bridge carried 44 mill/gal/day
Eventually Roman Empire had 12 Aqueducts, >577Km, most underground, some still used today
Begins in 1909
Completed in 1913
Completed in 1941
• LA Aqueduct: designed by William Mulholland & begins in 1909, cost 24 million, opens November 13th, 1913, pop of LA doubles in 10 yrs, provides 200mill gal/day to LA. Stress in Owens Valley. (Collapse of St Francis Dam (1926 – 1928 / Mulholland project) 20 bill gal water, 100 ft high, ~600 killed)
108 meters (608ft) long
St. Francis Dam
1926 ‐ 1928
59 meters (195ft) tall
• California Aqueduct: completed in 1941, longest in world at ~440 miles, brings 500 mill gal/day to LA region. Population of LA county ~10 million, without aqueducts, LA has enough water to support ~250,000. Water pump over Tehachapi Mnts (up 600m) is largest in world: >2mill gal water/minute! ~600 killed; worst civil eng disaster
in history of Ca. 2nd only to 1906 E-Quake
for loss of life
• Hetch Hetchy Aqueduct: completed in 1934, took 20 years to build, 176 miles of dams, reservoirs, tunnels, pump stations provides ~240 mill gal/day to SF Bay region
• New York City: three aqueducts bring 1.3 billion gal/day from Catskills, one completed in 1967, the other two in 1936 and 1917, much repair work needed.
California Water Project
Transferring water from one place to another
LA relies on aqueducts for ~85% of its water. Water flows by
pumps and gravity to heavily populated areas and arid
agricultural regions in southern California.
~20% of the En in Ca is used for pumping water, CO2 output
Reduces flushing capacity, lowers groundwater table,
lowers lake levels, threatens aquatic organisms
The Aral Sea Disaster
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Soviet Government started diverting rivers with irrigation canals
in the early 1960’s to grow rice, melons, cotton.
The Aral Sea (ecological, economical and health) Disaster
• The Aral Sea was once the world’s 4th largest fresh water lake.
• World’s largest irrigation canal (~1,300Km) transfers water • Since 1961 the salinity has tripled, 58% less surface area, water level dropped 72 feet, ~83% of water is lost, >14,000 sq mi!!
• ~85% of regions wetlands lost, and ~1/2 bird and mammal species disappeared, >80% of native fish species.
• Exposed salt and dust blows over 300Km: pollutes water, kills wildlife, harms crops, causes health problems.
• Dust is accumulating on Himalayan glaciers possibly causing them to melt faster than normal.
• Farmers have increased insecticides and fertilizers: chemicals are leaching into the groundwater, the source of drinking water for many of the regions 45 ‐ 58 million that live within the areas watershed.
The Aral Sea (ecological, economical and health) Disaster
• Greatly increased health problems from a combination of toxic dust, salt and contaminated water for a growing number of the 58 million people living in the Aral Sea's watershed. Such problems include abnormally high rates of:
• infant mortality, tuberculosis
• Anemia, respiratory illness (one of the world's highest)
• eye diseases (from salt dust), throat cancer
• kidney and liver diseases (especially cancers)
• arthritic diseases, typhoid fever, hepatitis
March 2011
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