Glacier Water Properties
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Prepared by Kim Morris and Martin Jeffries, Geophysical Institute, University of Alaska Fairbanks (UAF)
The Water Cycle
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The amount of water on
Earth does not change.
It’s place in the water cycle
and its phase do change.
Water is in storage when it is
frozen.
This can be either short(snow and annual ice) or
long- (glaciers) term storage.
http://www.usgcrp.gov/usgcrp/images/ocp2003/ocpfy2003-fig5-1.htm
Prepared by Kim Morris and Martin Jeffries, Geophysical Institute, University of Alaska Fairbanks
April, 2008
Glaciers
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Glaciers are perennial accumulations of ice, snow, sediment, rock and water.
They respond to changes in temperature, snowfall and geologic forces.
Prepared by Kim Morris and Martin Jeffries, Geophysical Institute, University of Alaska Fairbanks
April, 2008
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River Hydrology, I
Hydrology is the science dealing with the
properties, distribution, and circulation of water;
the seasonal patterns of a river’s flow.
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
These hydrographs of the Nenana River near
Healy, AK show the variability of the water flow
within a single year and between years.
Prepared by Kim Morris and Martin Jeffries, Geophysical Institute, University of Alaska Fairbanks
April, 2008
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River Hydrology, II
Sources of
Water for Rivers
Snow melt:
Mid-term (days to weeks),
high volume pulse of water.
Precipitation events (rainfall):
Relatively short (hours to days),
low volume water pulse.
Glacier melt:
Long term (months),
mid-volume pulse of water.
Prepared by Kim Morris and Martin Jeffries, Geophysical Institute, University of Alaska Fairbanks
April, 2008
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River Hydrology, III
An Example of a Glacier-fed
River Hydrology
A simplified diagram of glacier mass budget, showing major
mass input (snowfall) and outputs (melting, and runoff).
www.glaciers.pdx.edu/ Skagit/Basics00.html
Beginning in spring the accumulated snow melts,
feeding alpine streams.
By late summer, much of the seasonal snow
cover has disappeared from the landscape. The
glaciers continue to melt and this water supplies
the river during the driest part of the northwest
summer.
This is particularly important for summer during
drought years.
Average daily discharge per month for the Skagit River
below Ross Dam and average monthly precipitation at
Newhalem Washington.
Prepared by Kim Morris and Martin Jeffries, Geophysical Institute, University of Alaska Fairbanks
April, 2008
River Hydrology, IV
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Diurnal Glacial Water Flow
Meltwater from Vadret da Morteratsch,
Grisons, Switzerland.
The upper picture was taken on a July
morning.
The lower picture was taken in the afternoon
after ablation and subsequent runoff had both
increased considerably.
Photo J. Alean.
http://www.swisseduc.ch/glaciers/glossary/glacier-milk-en.html
Prepared by Kim Morris and Martin Jeffries, Geophysical Institute, University of Alaska Fairbanks
April, 2008
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Erosion
Erosion is the displacement of solids (soil,
mud, rock and other particles) by wind,
water, or ice in downward or down-slope
movement in response to gravity.
Weathering is the breaking down of rock
and particles through processes where no
movement is involved, although the two
processes may be concurrent.
The rate of erosion depends on many
factors including the amount and intensity of
precipitation, the texture of the soil, the
gradient of the slope and ground cover
(vegetation, bare ground, land use).
http://extension.missouri.edu/explore/agguides/agengin/g01509.htm
Prepared by Kim Morris and Martin Jeffries, Geophysical Institute, University of Alaska Fairbanks
April, 2008
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Glacier Erosion, I
Rocks and sediments are added to glaciers through various processes. Glaciers erode the
terrain principally through two methods: abrasion and plucking.
Plucking is a two part process. When glaciers
flow over the fractured bedrock surface,
subglacial water penetrates the fractures. When
this water freezes it expands and breaks the rock.
The ice expansion also acts as a lever that
loosens the rock by lifting it. Consequently,
sediments of all sizes become part of the glacier's
load.
Abrasion occurs when the ice and the load of rock
fragments slide over the bedrock and function as
sandpaper that smoothes and polishes the surface situated
below.
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
This pulverized rock is called rock flour (0.002 and
0.00625 mm).
Prepared by Kim Morris and Martin Jeffries, Geophysical Institute, University of Alaska Fairbanks
April, 2008
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Glacier Erosion, II
Sediment and debris can
also accumulate on a
glacier’s surface due to:
avalanches,
rock falls and
wind deposition.
Prepared by Kim Morris and Martin Jeffries, Geophysical Institute, University of Alaska Fairbanks
April, 2008
Precipitation Erosion, I
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During storms, soil is washed from the stream banks into the
stream. The amount that washes into a stream depends on
the type of land in the river's watershed and the vegetation
surrounding the river.
http://ga.water.usgs.gov/edu/characteristics.html#Sediment
Prepared by Kim Morris and Martin Jeffries, Geophysical Institute, University of Alaska Fairbanks
April, 2008
Precipitation Erosion, II
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Splash erosion: Raindrops splash soil particles short distances.
These particles are then much more vulnerable to erosion by water
flowing over the surface.
Sheet erosion: When rain falls faster than the soil can absorb it, water begins
to collect and flow over the ground surface. Sheet erosion begins when this
surface water begins to carry along particles that were detached by raindrops.
Rill and gully erosion: A rill is a narrow and shallow incision into soil resulting
from erosion by overland flow that has been focused into a thin thread by soil
surface roughness. As the rill increases in size it becomes a gully, a highly erosive
water structure. These usually occur due to a high water flow.
Stream and channel erosion: This is mostly caused by downward scour due
to flow shear stress. Side wall sluffing can also occur during widening of the
channel caused by large flows.
Prepared by Kim Morris and Martin Jeffries, Geophysical Institute, University of Alaska Fairbanks
April, 2008
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River Sediment Transportation, I
For a fluid to begin transporting sediment, the bed shear stress exerted by the fluid must exceed
the critical shear stress of the bed.
Rivers pick up and carry material as they flow downstream. A river may transport material in four
different ways:
Traction - large boulders and rocks are rolled
along the river bed
Saltation - small pebbles and stones are
bounced along the river bed
Suspension - fine light material is carried along
in the water
Solution - minerals are dissolved in the water
Rivers need energy to transport material, and levels of energy change as the river moves from
source to mouth.
Prepared by Kim Morris and Martin Jeffries, Geophysical Institute, University of Alaska Fairbanks
April, 2008
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River Sediment Transportation, II
When energy levels are very high, large rocks and boulders can be transported.
Energy levels are usually higher near a river's source, when its course is steep and
its valley narrow. Energy levels rise even higher in times of flood.
When energy levels are low, only small particles can be transported (if any). Energy
levels are lowest when the river enters the final stages of its journey (at the
mouth).
When a river loses energy it deposits some of the material it has been carrying.
Sediment class
Size (mm)
Sand
V. Coarse
Medium
V.Fine
1.5
0.375
0.094
Silt
V. Coarse
Medium
V.Fine
0.047
0.0117 (no longer visible to the human eye)
0.0049
Clay
< 0.00195
http://www.water.ncsu.edu/watershedss/info/turbid.html
Prepared by Kim Morris and Martin Jeffries, Geophysical Institute, University of Alaska Fairbanks
April, 2008
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River Water Conductivity
Water is called the “universal solvent”. This means it
has the ability to dissolve other substances. There is
hardly a substance known which has not been identified
in solution in the earth's waters.
Electrical conductivity is the ability of a material to carry
electrical current. In water, it is generally used as a
measure of the mineral or other ionic concentration.
High Purity Water Conductivity vs Temperature
Conductivity is a measure of the purity of water or the
concentration of ionized chemicals in water.
However, conductivity responds to all ionic content and
cannot distinguish particular conductive materials in the
presence of others.
Only ionizable materials will contribute to conductivity;
materials such as sugars or oils are not conductive.
Conductivity vs Concentrations at 25°C
Conductivity is affected by temperature since water becomes less viscous and ions can move more
easily at higher temperatures. Conventionally, conductivity measurements are referenced to 25°C though
occasionally a 20°C.
http://www.wileywater.com/Contributor/Sample_2.htm
Prepared by Kim Morris and Martin Jeffries, Geophysical Institute, University of Alaska Fairbanks
April, 2008
River Water Turbidity
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Turbidity is a unit of measurement quantifying the
degree to which light traveling through a water
column is scattered by the suspended particles.
The scattering of light increases with a greater
suspended load. The more total suspended solids
in the water, the murkier it seems and the higher the
turbidity.
There are various parameters influencing the cloudiness of water.
Some of these are:
Phytoplankton
Sediments from erosion
Re-suspended sediments from the bottom (frequently stir up by bottom dwellers)
Waste discharge
Algal growth
Urban runoff
Prepared by Kim Morris and Martin Jeffries, Geophysical Institute, University of Alaska Fairbanks
April, 2008
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River Water Quality - Field Sampling, I
Measuring turbidity provides a cheap estimate of the total suspended
solids or sediments (TSS) concentration (in milligrams dry weight/L).
Field Procedure
1) Label the sampling bottle lids before a water sample is
taken. Use masking tape and marker pen (Sharpie) and
include the location (Anderson, Healy, DEC, Cantwell)
and date (expressed as YY/MM/DD, e.g., 07/10/06). A
sample number, e.g., #1, should also be included, even if
only one sample is taken.
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
2) Obtain a water sample from a free-flowing part of the river.
Rinse the bottle in the river water before collecting a
water sample. Fill the 500 mL sampling bottle to nearly
full. If sampling is to be done by walking part way into the
water USE EXTREME CAUTION. Students should never
enter the water unsupervised by an adult.
3) Secure the lid tightly to the bottle once the sample is
obtained.
4) Return water samples to the classroom for analysis.
Prepared by Kim Morris and Martin Jeffries, Geophysical Institute, University of Alaska Fairbanks
April, 2008
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River Water Quality - Field Sampling, II
ENVIRONMENTAL OBSERVATIONS
Select (X) one from each catagory:
Sky:
(can subsititute cloud
protocol here)
Wind:
Precipitation:
clear
few
scattered
broken
overcast
(0-5%)
(5-25%)
(26-50%)
(51-90%)
(>90%)
calm
light wind
windy
none
snow flurries
snowing
drizzle
rain
freezing raining
Additional Comments:
QuickTime™ and a
TIFF (Uncompress ed) dec ompres sor
are needed to s ee this pic ture.
QuickTime™ and a
TIFF (Uncompress ed) dec ompres sor
are needed to s ee this pic ture.
Prepared by Kim Morris and Martin Jeffries, Geophysical Institute, University of Alaska Fairbanks
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
April, 2008
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RIVER
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River Water Quality - Conductivity
Laboratory Procedure
1) Set-up the Conductivity/TDS Meter
as per the instructions in the manual.
2) Shake the 500 ml sampling bottle.
3) Immerse the head of the
Conductivity/TDS Probe into the water
up to the immersion level.
Nenana River
During the measurement the lower LCD
display will show the temperature of the
solution.
4) Record the water temperature value.
5) Record the conductivity values (mS).
6) Record the TDS (P)
Conductivity/TDS
Meter
Note: From time to time it will be
necessary to re-calibrate the
conductivity meter.
Prepared by Kim Morris and Martin Jeffries, Geophysical Institute, University of Alaska Fairbanks
April, 2008
River Water Quality - Suspended Sediment, I
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Laboratory Procedure - Part I
1) Shake the 500 mL sampling bottle to make sure that the sediment is evenly
distributed throughout the water (depending on how long the sample has been
in the bottle sediment may have begun to settle on the bottom of the bottle).
2) Pour the water into one of the graduated cylinders until the water level
reaches the 250 mL mark.
3) Fold a paper filter and place it in the filter funnel.
4) Place the filter funnel and paper into the second 250 ml graduated cylinder.
5) Pour ALL of the water in the first 250 mL cylinder into the second 250 mL
cylinder through the funnel and paper. This may take a few minutes, and it
may be necessary to support the funnel so that the cylinder does not fall over.
5) Remove the paper filter (with sediment) from the filter funnel, and set
aside.
6) Dry the filter paper and sample in a location where it will not be disturbed.
(This can be done in the oven at 200°F - do not unfold the filter.)
Prepared by Kim Morris and Martin Jeffries, Geophysical Institute, University of Alaska Fairbanks
April, 2008
River Water Quality - Suspended Sediment, II
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Laboratory Procedure - Part II
Once the sediment sample is completely dry:
1) Set up the digital balance on a level surface. Calibrate if
necessary. Make sure that the scale is set to grams.
Do not use in a draughty place.
2) Place a dry, unused paper filter on the balance,
record its mass, then tare the scale.
3) Weigh the dried sediment sample filter
and sample and record its mass.
Calculate TSS
QuickTime™ and a
TIFF (U ncompressed) decompressor
are needed to see t his picture.
TSS(mg/L) = A/B
where:
A = Dried weight of the sediment (in milligrams)
B = Volume of water filtered (in Liters)
Note: 1 g = 1000 mg and 1 liter = 1000 milliliters
Prepared by Kim Morris and Martin Jeffries, Geophysical Institute, University of Alaska Fairbanks
April, 2008
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Water Quality Data Sheet
Freshwater Quality Protocols
Laboratory Data Sheet
Location: __________________________
Date: _______________ (YY/MM/DD)
Observer: ___________________
_______
SAMPLE NAME:
TOTAL DISSOLVED SOLIDS (CONDUCTIVITY)
Sample temperature ЎC:
Sample conductivity (mS):
Sample TDS (P):
SUSPENDED SEDIMENTS
Volume of water sample (L):
Weight of dry paper filter (mg):
Weight of dry sample and paper filter (mg)
Weight of dry sediment sample:
Total Suspended Solids (mg/L)
SAMPLE NAME:
TOTAL DISSOLVED SOLIDS (CONDUCTIVITY)
Sample temperature ЎC:
Sample conductivity (mS):
Sample TDS (P):
SUSPENDED SEDIMENTS
Volume of water sample (L):
Weight of dry paper filter (mg):
Weight of dry sample and paper filter (mg)
Weight of dry sediment sample:
Total Suspended Solids (mg/L)
Prepared by Kim Morris and Martin Jeffries, Geophysical Institute, University of Alaska Fairbanks
April, 2008