Water
Resources
• 
• 
• 
• 
The
Hydrologic
Cycle
Soil‐Water‐Budget
Concept
Groundwater
Resources
Our
Water
Supply
HYDROLOGIC CYCLE: A SIMPLIFIED MODEL OF THE FLOW OF WATER,
ICE AND WATER VAPOR FROM PLACE TO PLACE
WATER FLOWS THRU THE ATMOSPHERE, ACROSS THE
LAND, WHERE IT IS STORED AS ICE AND WITHIN
GROUNDWATER
SOLAR ENERGY EMPOWERS THE WHOLE CYCLE
97% OF EARTH’S WATER IS IN THE OCEAN SO . . .
THIS IS WHERE MOST EVAPORATION AND
PRECIPITATION OCCUR
87% OF ALL EVAPORATION CAN BE TRACED TO THE
OCEAN
THE OTHER 14% COMES FROM LAND INCLUDING
WATER PASSING THROUGH PLANT LEAVES AS
TRANSPIRATION
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INTERCEPTION:
OCCURS WHEN WATER STRIKES VEGETATION OR
OTHER GROUND COVER
DELAYS THE FALL OF PRECIPITATION TOWARDS
EARTH’S SURFACE
THROUGHFALL:
PRECIPITATION THAT FALLS DIRECTLY TO
THE GROUND . . .
AND WATER THAT DRIPS ONTO THE GROUND
FROM VEGETATION
INFILTRATION:
WATER SOAKS INTO SUBSURFACE OR PENETRATES
THE SOIL SURFACE
WATER ACCESS TO SUBSURFACE REGIONS OF SOIL
MOISTURE STORAGE 2
PERCOLATION:
WATER PERMEATING SOIL OR ROCK THROUGH
DOWNWARD MOVEMENT
THE PROCESS BY WHICH WATER PERMEATES THE
SOIL OR POROUS ROCK INTO THE SUBSURFACE
ENVIRONMENT
Soil‐Water‐Budget
Concept
•  The
Soil‐Water
Balance
Equa:on
•  Water
Budget
and
Water
Resources
THE SOIL-WATER BUDGET
A SOIL-MOISTURE BUDGET CAN BE ESTABLISHED FOR ANY AREA
OF THE EARTH’S SURFACE BY MEASURING:
1. THE PRECIPITATION INPUT
AND
2. ITS DISTRIBUTION TO SATISFY THE DEMANDS OF
PLANTS
EVAPORATION
AND SOIL MOISTURE STORAGE IN THE AREA CONSIDERED
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Groundwater
Resources
•  Groundwater
Profile
and
Movement
•  Groundwater
U:liza:on
•  Pollu:on
of
Groundwater
Resources
GROUNDWATER RESOURCES
WATER BENEATH THE SURFACE THAT IS BEYOND THE SOILROOT ZONE LIES BENEATH THE GROUND AND IS THEREFORE TIED TO
SURFACE SUPPLIES
A MAJOR SOURCE OF DRINKING WATER
NOT AFFECTED BY SHORT-TERM DROUGHTS
50% OF US POPULATION GETS SOME OF ITS FRESH WATER
FROM GROUNDWATER – CAN BE AS HIGH AS 100% IN RURAL
AREAS
GROUNDWATER PROFILE AND MOVEMENT
BEGINS AS SURPLUS WATER AND PERCOLATES
DOWNWARD AS GRAVITATIONAL WATER MOVES THRU ZONE OF AERATION:
A ZONE ABOVE THE WATER TABLE, WHICH HAS
AIR IN ITS PORES AND MAY OR MAY NOT HAVE
WATER
SOIL AND ROCK ARE LESS SATURATED HERE
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WATER EVENTUALLY REACHES AN AREA WHERE
SUBSURFACE WATER ACCUMULATES THIS IS THE ZONE OF SATURATION –
A GROUNDWATER ZONE BELOW THE WATER
TABLE IN WHICH ALL PORE SPACES ARE FILLED
WITH WATER
USUALLY COMPOSED OF SAND, GRAVEL AND ROCK
THE UPPER LIMIT OF THE WATER THAT
COLLECTS IN THE ZONE OF SATURATION IS
CALLED THE WATER TABLE -
THE UPPER SURFACE OF GROUNDWATER
THE CONTACT POINT BETWEEN THE ZONE OF
SATURATION AND AERATION IN AN UNCONFINED
AQUIFER
THE ZONE OF SATURATION CAN FORM AN
AQUIFER:
ROCK LAYER THAT IS PERMEABLE TO GROUND
WATER FLOW IN USABLE AMOUNTS
BY CONTRAST, AN AQUICLUDE IS A BODY OF ROCK THAT DOES NOT
CONDUCT WATER IN USABLE AMOUNTS
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CONFINED AQUIFER :
BOUNDED ABOVE AND BELOW BY IMPERMEABLE
LAYERS OF ROCK OR SEDIMENT – HIGH WATER
PRESSURE
UNCONFINED AQUIFER:
HAS A PERMEABLE LAYER ON TOP AND AN
IMPERABLE LAYER BELOW
IT IS THE ZONE OF SATUARATION IN WATERBEARING ROCK-STRATA
RECHARGE GENERALLY ACCOMPLISHED BY
WATER PERCOLATING DOWN FROM ABOVE
LOW WATER PRESSURE
AQUIFER RECHARGE AREA:
THE SURFACE AREA WHERE WATER ENTERS AN
AQUIFER TO RECHARGE THE WATER-BEARING
STRATA IN A GROUND-WATER SYSTEM
Our
Water
Supply
•  Water
Supply
in
the
United
States
•  Instream,
NonconsumpBve,
and
ConsumpBve
Uses
•  DesalinaBon
•  Future
ConsideraBons
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