HPU NCS2200 earth science for elementary education majors summer 2014 online class water resources lecture

1. Chapter 14
Water

2. Hydrosphere
 All the water on and above the earth
 100 % of earth’s water existed since
formation of the planet
 97.5 % seawater
 2.5 % fresh
 1.7% locked in glaciers and ice caps
 0.78% in Groundwater – including soil
moisture and swamp water
 0.02% in rivers and lakes

4. Properties of Water
 Adhesion – ability to stick to other things
 Cohesion – ability to stick to itself
 Surface Tension – through hydrogen bonding water
forms a “skin” on its surface
 Capillarity – ability of water to be drawn up
 Universal Solvent – ability to dissolve a wide range
of substances

5. Properties of Water
 Exists in 3 forms – solid, liquid, gas
 Changes temperature slowly – stores
large quantities of heat
 Takes a lot of heat to evaporate water due
to strong attractive forces
 Universal solvent
 Water can ionize
 Surface can contract due to strong
cohesive forces
 Expands when freezes

6. 12.1 Water supply and demand
 Domestic water use – 10%
 Flushing, bathing, drinking
 Industrial – 49%
 ¾ goes to cooling of electrical power plants
 ¼ to all other industry
 Agriculture – 41%
 Irrigation feeds most of the world

7. Fig. 12.4, p.298

8. Hydrologic Cycle
Where does the energy for the hydrologic cycle come from??

10. Aquifer Vocab
Zone of aeration – area of an aquifer
where there is air between particles
Zone of saturation – area of an aquifer
where there is water between particles
Recharge zone – area where an
aquifer receives water from the surface
Confined aquifer – an aquifer that has
an impermeable layer above and below
it
Unconfined aquifer – an aquifer that
has an impermeable layer below it but
is open above

12. 11.2 Streams
 Flowing water in a channel
 River: large stream fed by tributaries
 Stream flow & velocity
 Gradient – steepness
 Discharge – volume of water flowing/unit time
 Channel characteristics
• Bank
• bed

13. 11.2 Streams
 Stream erosion and transport
 Competence – how big
 Capacity – how much
 Dissolved load – i.e.; like salt
 Suspended load – portion that remains
suspended
 Bed load – load that rolls, skips or bounces along
the bottom

14. 11.2 Streams
 Drainage basins (ie watershed)
 All the land drained by a body of water
 Separated by mountains, ridges, or plateaus
• E.g.; Mississippi Embayment – Drains 2/3 of the U.S.
land area between the Appalachians and the Rockies
• Smaller drainage basins exist within these larger
basins –
 North Carolina has 13 major basins
• Cape Fear & Yadkin Pee Dee are the two closest

15. US Watersheds
 Mississippi is the
largest river basin in
the US covering
almost 2/3 of the
continental land mass.
 The river itself is the
14th longest in the
world at 2350 miles

16. Fig. 11.12, p.270

17. World Watersheds
The Nile (N. Africa)
– 4160 miles
The Yangtze (China) – 3964 miles
The Congo (C. Afri
- 2718 miles
Amazon – Brazil – S. America
- 4000 miles

18. Stress on the World’s River Basins
 Comparison of the amount of water available
with the amount used by humans.
Figure 14-6

19. TOO LITTLE FRESHWATER
 Cities are outbidding farmers for water
supplies from rivers and aquifers.
 Countries are importing grain as a way to
reduce their water use.
 More crops are being used to produce
biofuels.
 Our water options are:
 Get more water from aquifers and rivers,
desalinate ocean water, waste less water.

20. Water Resources in US
 Eastern US
 Flooding
 Urban shortages
 Pollution
 Western Arid Regions
 Low precipitation
 High evaporation
 Recurring prolonged
drought
These conditions result in water scarcity:
1) Dry climate
2) Drought
3) Desiccation
4) Water stress

21. WITHDRAWING GROUNDWATER
TO INCREASE SUPPLIES
 Most aquifers are renewable resources
unless water is removed faster than it is
replenished or if they are contaminated.
 Groundwater depletion is a growing problem
mostly from irrigation.
 At least one-fourth of the farms in India are being
irrigated from overpumped aquifers.

22. Fig. 14-7, p. 313
Trade-Offs
Withdrawing Groundwater
Advantages Disadvantages
Useful for drinking
and irrigation
Aquifer depletion from
overpumping
Available year-
round
Sinking of land
(subsidence) from
overpumping
Exists almost
everywhere
Polluted aquifers for
decades or centuries
Renewable if not
overpumped or
contaminated
Saltwater intrusion into
drinking water supplies
near coastal areas
Reduced water flows
into surface waters
No evaporation
losses
Cheaper to extract
than most surface
waters
Increased cost and
contamination from
deeper wells

23. Groundwater Depletion:
A Growing Problem
 The Ogallala, the world’s largest aquifer, is
most of the red area in the center (Midwest).
 Areas of
greatest aquifer
depletion from
groundwater
overdraft in the
continental U.S.
Figure 14-8

24. Fig. 12.17b, p.306

25. Fig. 12.15, p.304

26. Fig. 12.16, p.305

27. Other Effects of Groundwater
Overpumping
 Groundwater
overpumping can
cause land to sink,
and contaminate
freshwater aquifers
near coastal areas
with saltwater.
Figure 14-11

28. Other Effects of Groundwater
Overpumping
 Sinkholes form when
the roof of an
underground cavern
collapses after being
drained of
groundwater.
Figure 14-10

29. Fig. 12.18, p.306
►Subsidence
– a sinking of
the Earth’s
surface caused
by loss of
aquifer
porosity
►The land in
this San
Joquin Valley
region has
subsisted by
30 feet in 50
years.

30. Fig. 14-12, p. 316
Solutions
Groundwater Depletion
Prevention Control
Waste less water Raise price of water
to discourage waste
Subsidize water
conservation
Ban new wells in
aquifers near
surface waters
Tax water pumped
from wells near
surface waters
Buy and retire
groundwater
withdrawal rights
in critical areas
Do not grow water-
intensive crops in
dry areas
Set and enforce
minimum stream
flow levels