Transcript Slide 1

Soil Water
Water as a Resource
CIA Global Trends: Natural Resources and Environment
(projections for 2015)
Overall food production will be adequate to feed the world's growing
population, but poor infrastructure and distribution, political instability, and chronic
poverty will lead to malnourishment in parts of Sub-Saharan Africa. The potential
for famine will persist in countries with repressive government policies or internal
conflicts. Despite a 50 percent increase in global energy demand, energy
resources will be sufficient to meet demand; the latest estimates suggest that
80 percent of the world's available oil and 95 percent of its gas remain
underground.
In contrast to food and energy, water scarcities and allocation will pose
significant challenges to governments in the Middle East, Sub-Saharan
Africa, South Asia, and northern China. Regional tensions over water will be
heightened by 2015.
Fastest growing countries
India
China
Pakistan
½ the world’s
total agricultural
groundwater use
In India, 80% of domestic supply and 70%
of agricultural supply is from groundwater
The water table under some of the major
grain-producing areas in northern China is
falling at a rate of five feet per year, and
water tables throughout India are falling
an average of 3-10 feet per year.
½ China’s wheat, 1/3 corn
Shallow aquifer largely depleted (replenishable)
Shift to Deep fossil aquifer (non-replenishable)
Agricultural well depths can exceed 1000 feet ($)
Municipal well depths can exceed 3000 ft.
Levels dropping 10 ft. or more / year
China’s grain production has fallen from its historical
peak of 392 million tons in 1998 to an estimated 358
million tons in 2005, a drop of 34 million tons.
China largely covered the drop-off in production by
drawing down its once vast stocks until 2004, at
which point it imported 7 million tons of grain.
India
Population
21 million wells
water table is falling by 6 meters (20 feet) per year
falling water tables have dried up 95 percent
of the wells owned by small farmers
drilling 1000m to reach water
agriculture is rain-fed and drinking water is trucked in
Pakistan
Quetta
Pakistan is growing by 3 million per year,
In the Punjab plain, the drop in water tables appears to be similar to that in India.
In the province of Baluchistan, water tables are falling by 3.5 meters per year.
within 15 years Quetta will run out of water if the current consumption rate continues
Saudi Arabia
al-Disi aquifer
sandstone aquifer not subject to recharge
Shared by Saudi Arabia and Jordan
1984 Saudi national survey reported
fossil water reserves at 462 billion tons
½ has been depleted
irrigated agriculture could last for
another decade
Wheat and Soybeans
U.S. Water
Rainfall: 4,200 billion gal/day
408 billion gallons per day total withdrawal
Thermoelectric power = 50%
Irrigation = 30%
Public-supply = 10%
Industrial = 5%
1.6-2.5 gpm
Guilty Pleasures
5-8 gpm
http://www.youtube.com/watch?v=vMITcQUe-9M
How much water do you use?
http://ga.water.usgs.gov/edu/sacsq.html
Water Usage
Use
Gallons per Capita
Percentage of Total
Daily Use
Showers
12.6
17.3%
Clothes Washers
15.1
20.9%
Dishwashers
1.0
1.3%
Toilets
20.1
27.7%
Baths
1.2
2.1%
Leaks
10.0
13.8%
Faucets
11.1
15.3%
Other Domestic
Uses
1.5
2.1%
Total
74 gallons
How do you conserver water?
Peanuts:
1pound = 100 gal
Domestic water use:
Industrial water use:
Irrigation water use:
1 pound of Rice
1 pound of Wheat
1 pound of Sugar
1 pound of coffee
650 gallons
130 gallons
400 gallons
2650 gallons
1 beer: 66 gallons
10%
20%
70%
4800 pounds
1000 pounds
3000 pounds
10 tons
Secondary Water
Grain
Livestock
¼ pounder
3000 gallons
11 tons
Quart of milk
1000 gallons
>3 tons
Pound of cheese
650 gallons
2.5 tons
Carnivores consume 100 times their weight in water each day
Vegetarians consume about ½ as much.
Breakfast
Toast:
Eggs:
Milk:
Coffee:
Sugar:
40 gal
130 gal
265 gal
37 gal
3 gal
Total: 475 gal
Yearly Totals
Drinking water: 250 - 300 gallons
Total water: 1500 – 3000 tons
Factoids
Americans drink more than 1 billion
glasses of tap water per day.
On average, 50 to 70 percent of home
water is used outdoors for watering
lawns and gardens.
Average household water use annually: 127,400 gallons
Average daily household water use : 350 gallons
Factoids
It takes about 4,776 gallons of water to raise a
Christmas tree. To raise the 35 million Christmas
trees U.S. families enjoy each year, a total of 167
billion gallons is required.
If mothers refresh their floral arrangements and
flowering plants during the Mothers' Day week, they
will use 2,835,000 gallons of water.
After Thanksgiving dinner in 1999, 16.4 million
Americans watched football. At halftime, American
toilets flushed 16.4 million times and used 48.5
million gallons of water.
Water efficient toilets would save us 22.3 million
gallons of water.
Where is all the Water?
How much water is there?
400 billion billion gallons
326 million mi3
(one estimate)
Total Earth Water = 326 million mi3
688 miles
1 cubic mile
Distance to the sun?
93 million miles
326 million mi3
0.12% of the earth’s volume
Where is all this water?
Where is all the Water?
Oceans, Seas, & Bays
Wetlands, Swamps
Lakes
Soil Moisture
Atmosphere
Biological Water
Rivers
Groundwater
Ice caps, Glaciers, & Permafrost
Where is all the Water?
Water source
Oceans, Seas, & Bays
Percent
of fresh
water
Percent
of total
water
--
96.5
Ice caps, Glaciers, & Permafrost
69.6
1.79
Groundwater
30.1
1.7
Lakes
0.26
0.013
Soil Moisture
0.05
0.001
Atmosphere
0.04
0.001
Wetlands, Swamps
0.03
0.0008
Rivers
0.006
0.0002
Biological Water
0.003
0.0001
Source: USGS
Freshwater
Atmosphere
Groundwater
Lakes
Soils
Wetlands
Rivers
0.775%
Biological
0.8%
Cycling of Water in the Environment
Hydrologic Cycle
The hydrologic cycle takes place in the
hydrosphere, this is the region containing
all the water in the atmosphere and on the
surface of the earth. The cycle is the
movement of water through this hydrosphere.
Condensation
Evaporation
Infiltration
Runoff
Precipitation
Fate of Precipitation
Evaporation/Transpiration
infiltration
overland flow
interflow
percolation
groundwater
Understanding Soil Water: The Water Molecule
Water Molecule
Shared electrons
Bond of shared
electrons
O
H
H
O
H
H
Shared electrons
Electrons are negatively charged, protons positive
Oxygen is “electron greedy”
Oxygen pulls electrons toward itself and away from hydrogen
e- eee-
O
e-
ee-
H
eP+
P+
P+
H
P+
This pulling of electrons toward itself is called “electronegativity”
Abundant electrons (negative charge)
e- eee-
O
e-
P+
ee-
e-
H
P+
H
Two protons (+ charge)
Polarity
_
+
+
+
Electric Dipole
Red = lots of eBlue = few e-
Polarity
+
Slight positive charge
Slight negative charge
Electric
Dipole
Orientation
+
+
Bond
-
-
Opposite charges attract each other
Hydrogen Bonding in Water
Bonds are ephemeral, continuously breaking and reforming
Cohesion
The cohesion of water molecules is partly responsible
for the overall movement and retention of water in soils
Next:
Movement of water: Forces and Energies