Movement and locations of water. Underground water. Soil water belt, subsurface flow. Percolation. Porosity and Permeability. Hydrologic Zones. Zone of aeration, zone of saturation, water table, effluent and influent condition. Zone of confined water, aquaclude, aquifer, artesian well. Waterless zone. Groundwater management. Groundwater management issues. Aquifer recharge, cone of depression, subsidence, groundwater contamination. The case of Venice Italy. Hydrothermal activity. Hot springs, geysers, fumaroles. Permafrost, melting permafrost. Glaciers, alpine and continental glaciers. Melting glaciers. Lakes. Destruction of the Aral Sea. Swamps and marshes. Streams.

1. Water Resources
Chapter 8
Water and Ice:
Underground and on the Surface

2. Movement:
1. Surface-to-Air
2. Air-to-Surface
3. On/Beneath the Surface

4. Subjects you’ll be studying in
this segment:
•Underground water
–Groundwater
–Hydrothermal sources
•Ice on the surface
–Permafrost
–Glaciers
•Water on the surface
–Lakes
–Swamps and Marshes

5. Underground Water
•Small portion of Earth’s total water (0.5%)
•Significant source of water for humans
•But how did it get there?

6. Surface and Sub-surface Water:
Into and Under the Ground
•Precipitation adds to the surface soil water
belt
•Water not taken up by plants and soil flows
downward under the influence of gravity
•Once saturation is reached, water flows
laterally (sideways), following topography—
this movement is called subsurface flow

8. Subsurface Flow
•At the base of a slope or
at a surface depression
that is lower than the
water table, subsurface
flow may reemerge
(return flow).

9. Percolation
•The downward flow of water through pore
spaces in soil or rock under the influence of
gravity is called percolation (just like water
percolating through coffee grounds)
•Different types of subsurface material will
hold or pass water through in different ways.

10. Porosity and Permeability
•Porosity—A measure of the total volume of
pore spaces through which liquids or gases
can pass, in relation to the total volume of
solid ground material
–Sand and sandstone have coarse grains and open
textures, making them very porous
–The more porous the material, the more water it
can hold (like a sponge)

11. Porosity and Permeability
•Permeability—How easily soil, rock
fragments, or solid rock allow water to enter
and pass through (how easily does the water
flow?)
–Dry clay is very porous (lots of spaces between
particles for holding water)
–Once water is added, clay particles hold the water
very tightly (water is held but can’t flow through)
–Clay is very porous, but not permeable—it is
impermeable

12. Hydrologic Zones

13. Hydrologic Zones
•Zone of Aeration—The soil water belt; this
zone is not completely saturated—some pore
spaces are filled with air, some with water.
•This is where infiltration and percolation
happen—water is just passing through.

14. Hydrologic Zones
•Zone of Saturation—All pore spaces in rock
or sediment filled with water
–The top of the zone of saturation (groundwater
layer) is called the water table
–The shape of the water table follows topography—
it is highest where elevations are highest and
lowest in areas of low elevation
–This groundwater flows slowly toward
depressions or lower elevations
•Note: Groundwater is NOT an underground stream!

15. Hydrologic Zones
•Zone of Saturation
–Effluent condition—The water
table is higher than a surface
depression; groundwater flows out
onto the surface
–Influent condition—The water
table is lower than a surface
depression; water in the
depression (a stream or a lake)
seeps downward until it reaches
the groundwater layer

16. What does a spring look like?

17. Hydrologic Zones
•Zone of Confined
Water—separated from the
zone of saturation by an
impermeable layer, called
an aquaclude
•This underground water
storage layer is called an
aquifer
•Artesian well—A well
drilled into the aquifer that
is lower than the top of the
water table and flows to
release pressure, without
any pumping

18. Aquifers and Artesian Wells

19. Hydrologic Zones
•Waterless Zone—A few miles down, the
pressure too great; pore spaces collapse and
water can’t flow

20. Groundwater Management
•A lack of careful management can endanger
humans, wildlife, and vegetation
•Depletion and contamination are serious
threats to global health and well-being
•Competition and conflicts over adequate,
clean water supplies may become the
dominant issue, world-wide.

21. Groundwater Management:
Issues
•Removal of groundwater faster
than natural recharge can
replace it may lead to a
depleted and unusable water
source
•The case of the Ogallala
Aquifer

22. Groundwater Management:
Issues
•As water is removed from the groundwater layer, it doesn’t
drop the water level uniformly across the surface of the
water table
•An area of empty pore spaces surrounds the well in a cone
shape. This cone-shaped lowering of the water table is
called a cone of depression.

23. Groundwater Management:
Issues
•When pore spaces are left unrecharged, they collapse and
the ground sinks. This ground subsidence can be
significant and environmentally destructive.

24. The Case of Venice, Italy
The worst acqua alta in memory, the one
that truly woke Venetians up to how bad
things could get, occurred on November
3, 1966. The high tide that swept into all
corners of the city that night lasted an
astonishing 22 hours (typical high tides
last six).

26. •Contamination of groundwater
–Percolation through compromised landfills and
waste dump sites carrying pollutants into
groundwater sources
–Surface and buried pollutants seeping into
groundwater from industry and energy sources
–Seepage from septic systems
–Seawater intrusion into coastal groundwater
sources turning them saline and undrinkable
Groundwater Management:
Issues

28. Hydrothermal Activity
•Occurs where underground water comes into
contact with magma sources
•Temperatures as high as 400ºF; water
remains liquid because of the extreme
pressure of the rocks above
•Heated water dissolves minerals, especially
silica, which are carried away and deposited
on the surface

29. Hydrothermal Features
•Hot springs
–Heat is dissipated evenly as the water rises to the
surface, so it flows slowly
Morning Glory Pool, Yellowstone N.P.

30. Hydrothermal Features
•Geysers
–Heat is not lost, so
that water shoots
rapidly to the surface
as if exploding
Old Faithful, Yellowstone N.P.

31. Hydrothermal Features
•Fumaroles (steam vents)
–Above the water table, so little water is present; only
steam and volcanic gases are released from surface
cracks and fissures
Green Dragon Fumarole,
Yellowstone N.P.

32. Surface Water: Ice
•Permafrost—Permanently frozen ground
water; any subsoil that stays frozen for two
consecutive years is considered permafrost

34. Melting permafrost is a serious problem
•Building foundations cracking as surface turns
to mud, broken pipelines, etc. (This is why the
Alaska Pipeline sits above ground)
•Once-frozen, decaying vegetation and biota
releasing methane
Yukon, Canada
Pipeline in northern Russia
The Alaska Pipeline

35. Surface Water: Glaciers
Extent of ice sheets
during last glacial
maximum (the last
Ice Age)

36. Current global extent of glacial ice

37. Surface Water: Ice
•Glaciers
–Large, moving mass of ice, forming on or adjacent
to a land surface through the accumulation and
consolidation, under pressure, of snow falling at
higher elevations
–The ice mass moves outward and downward from
the zone of accumulation to lower elevations
–Glaciers are in constant motion

38. Glaciers

39. Glaciers
•Constant motion scrapes away surface
material wherever the glacier is flowing

40. Glacial Moraines in Northern U.S.
•Glacial till (scraped material) is trapped and
transported by moving ice, then deposited at the
end and sides of the glacier in a chaotic jumble
–The Great Plains, U.S. and Michigan

41. Glaciers
•Two types of glaciers
–Alpine glaciers (mountain glaciers or valley
glaciers)
•Form in mountain valleys
–Continental glaciers (ice sheets)
•A continuous mass of thick ice moving outward in all
directions from the center of accumulation
•So large that they bury the entire landscape
–Greenland and Antarctica

42. Continental and Alpine Glaciers

43. What will happen when the
world’s glaciers melt?
•Melting sea ice is increasing temperatures in
the Arctic Ocean, reducing albedo and
creating a positive feedback loop that is
increasing warming
–Melting of sea ice will not raise sea level
–Melting of ice on land, which then flows to sea,
has already significantly raised sea level (low-lying
islands disappearing, coral forests “drowning”)
•Greenland’s ice sheets melting completely would raise
sea level by 6 m (~18 feet)

44. Lakes

45. Lakes
•A body of water surrounded by land (no size
definition)
•Many lakes, esp. in dry regions, are ephemeral (dry
for part of the year)
•Water balance maintained by sfc. inflow and/or
springs beneath the sfc.
•Drainage can occur by stream, or into the
subsurface where aquacludes are not present
•Movement of water is always downward in elevation
toward the ocean

46. Lakes
•Lakes can be created by glaciation, crustal activity,
volcanism, sinkhole collapse, etc.
•The destiny of most lakes is infilling by sediments
or destruction by humans

47. The Destruction of the Aral Sea

48. The Destruction of the Aral Sea

49. The Destruction of the Aral Sea

50. 50
An alkali dust
storm building
along the shores of
Owens Lake, CA
Salts blowing across
Paoha Island, Mono
Lake, CA

51. Swamps and Marshes
•Associated with coastal
plains (like the area
surrounding S.F. and S.P.
Bays), broad river valleys,
and recently glaciated areas
•May be an intermediate
stage during the infilling of
a lake
Swamps—plant growth dominated by trees
Marshes—dominated by grasses/rushes
shallow enough for plants to grow

52. Surface Water: Streams
•Runoff—water that flows downslope along the
surface is called overland flow
–Runoff that flows downslope in sheets, where the
ground surface is slick or solid and water can’t infiltrate
easily is called sheet flow
•If runoff occupies a narrow channel confined by its
banks, it is a stream or river
•Rivers and Streams flow to lowest possible elevation,
powered by:
Gravity!