Transcript CEE 113 Groundwater Hydrology

EEOS 350 – Quantitative
Hydrogeology
Syllabus  an (optimistic)
approximation of what we will cover.
 Text: Fundamentals of Ground Water,
Schwartz and Zhang, 2003.
http://www.wiley.com/WileyCDA/WileyT
itle/productCd-0471137855.html
 ERRATA!! Need to go through and
highlight the errors in your text!

September 4, 2007
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EEOS 350 – Quantitative
Hydrogeology
Field trip at Nantucket Field site
http://www.umb.edu/nantucket/
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– Water level map
– Slug tests
– Install transducers
– Run pumping test
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Water Facts
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Requirements:
– A person requires 3 liters/day (3.2 qts/day) of water for
drinking (minimum survival requirement)
– 50 liters/day (13.2 gal/day) for drinking, sanitation and
hygiene.
– 1300 m3/yr (940 gal/day) when food production is included.
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Uses:
– Average US citizen uses 80 to 100 gal/day. During medieval
times, a person only used 5 gal/day (didn’t shower much, I
guess).
– A single flush of a toilet requires 2-7 gal (same as King
Arthur used in a whole day!)
– 2 gal to brush teeth, 25-50 gal for shower
– It takes 1 gal of water to process a quarter pound of
hamburger.
– It takes 2072 gal to make 4 tires.
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How much water stored (in %)?
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Oceans
Ice caps/glaciers/snow
Groundwater
– Fresh
(0.76%)
– Saline (0.94%)
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Freshwater lakes
Inland seas/salt lakes
Soil moisture
Atmosphere
All Rivers
Biological water
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96.5
1.74
1.7
0.007
0.008
0.001
0.001
0.0002
0.0001
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The Hydrologic Cycle
Fluxes (flows)
Stocks (storage)
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Source: www.cet.nau.edu/Projects/ SWRA/research.html
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Components of the water cycle
Fluxes (flows)
– Units = volume/time or
depth/time(in/yr, mm/hr)
– These are the
“renewable” components
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Precipitation
Evaporation
Transpiration
Infiltration
Recharge
Runoff
Streamflow
Groundwater flow
Storage (stocks)
– Units = Volume (ft3, m3)
– These are the
components that are
emptied or filled by the
fluxes
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Soil moisture storage
(unsaturated zone)
Surface storage (lakes,
ponds, puddles)
Atmospheric storage
(water vapor)
Aquifer storage
(saturated zone)
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Source: Jackson et al, 2001
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Global renewable water resources
~ 40,000 billion cubic meters (BCM)
 Accessible in both space & time
~ 20,000 BCM
 Minimum human freshwater
requirements = 1,300 m3/yr per person
~ 7,800 BCM
 Human requirements
~ 39% of total supply and yet…
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…in the year 2000:
– 1 billion people lacked access to
improved drinking water
»2 out of 5 Africans
– 2.4 billion lacked access to improved
sanitation
»fewer than half of all Asians
Source: Global Water Supply and Sanitation
Assessment 2000 Report, WHO
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…because freshwater is not evenly distributed.
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What makes water so unique?
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Water is the only substance found in all
three states (phases) at ambient
temperatures.
– Water has unusually high melting and
boiling points.
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What makes water so unique?
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Water expands when both heated or
cooled from 4°C.
– This makes fish VERY happy, but
sometimes not water fowl!
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What makes water so unique?
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Water is a “universal solvent”.
– High dielectric constant because of it’s
polar structure
– Strong hydrogen bonds
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What makes water so unique?
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Water has a:
– Extremely low compressibility (water is
considered essentially incompressible).
– high thermal conductivity (that’s why we
get cold even when the pool is heated)
– Low electrical conductivity
– High viscosity (relative to other liquids)
– High surface tension (making water
skippers happy, too!). Surfactants reduce
surface tension.
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Physical properties of water
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Density, r:
– 1,000 kg/m3 at 4°C
– 1.94 slugs/ft3 at 40°F
  rg

f
 Specific gravity:
SG 
w
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Specific weight:
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Hydrologic Cycle
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Water Balance
Inflow - Outflow = change in storage
*assumes conservation of mass mass (in
this case, water) is neither created nor
destroyed within the control volume)
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Water balance
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For a water balance (or any mass
balance), you need:
– Control volume  the boundaries of your
analysis
– Water balance terms  inputs and outputs
across the CV, storage within CV
– Time step  time frame over which your
water balance terms are estimated.
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Control Volume
For mass (or water) balance analysis,
need to establish the size (scale) of the
problem.
 For a surface water balance, the control
volume is the watershed. (Control
volume is much harder to establish in
groundwater balance).
 What is a watershed?
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Delineating a watershed
boundary
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Pick a point of interest on the stream
Start on right or left bank, draw a line away from that
point, always maintaining the line perpendicular to
contours
continue line until it is going opposite of starting
direction (in general).
WS boundaries tend to follow ridge lines.
Always ask “If I was a drop of water, which way
would I fall”
A WATERSHED BOUNDARY NEVER CROSSES A
STREAM CHANNEL.
Start on opposite bank and do the same for other
side of watershed.
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