Red River Basin River Watch Snow Study Research Project
River Watch has engaged in this monitoring and research project to help gain knowledge on the factors
that contribute to flooding in the Red River Basin and to contribute to the predictably of floods. The
main factors in flooding as determined by the National Weather Service for the Red River Basin are:
(http://www.crh.noaa.gov/fgf/hydro/red_river_flood.php)
1. the freeze/melt cycle
2. early spring rains which increase melting of the snow pack or late spring snow storms adding to
the existing snow pack
3. the actual snow pack depth and water equivalency
4. frost depth
5. soil moisture content
6. river ice conditions
This project will primarily investigate the factors of snow pack depth and water equivalency, frost depth,
early spring storms, and soil moisture content. By investigating how these factors act and interact,
knowledge will be gained which can then be used by the National Weather Service and others to better
understand and more accurately predict flooding.
Specific measurements that River Watch participants will contribute to this project are summarized
below, more detailed standard operating procedures follow.
Snow Pack Depth and Water Equivalency: The amount of water that is contained in the snowpack
waiting to be melted is critical to understanding and predicting floods in the basin. Measuring just
snowpack depth is not sufficient since water content can vary with the same depth. Measuring
depth plus water equivalency—inches of water in the snowpack - is essential for determining the
amount of water on the landscape that can potentially contribute to floods. Also critical is the
spatial arrangement of the levels of snowpack and water equivalency. River Watch network
measurements of these critical factors will provide increased coverage in the basin and establish
how snowpack varies within the basin and major watersheds.
Because snow in this area is subject to wind movement, the selection of where to collect
snowpack measurements is critical. Areas which do not have additions or subtractions of snow are
ideal. Sites like parks with trees without dense canopies or small open areas surrounded by trees
have snowpack that is minimally affected by wind movement or interception by trees. Snowpack
depth is measured by inserting a ruler into the snowpack to the ground and reading the snow
depth. To get water equivalency a tube of known volume is pushed into the snowpack and the
snow trapped inside is melted and then poured into a rain gauge to determine inches of water in
the snowpack.
Frost Depth: Knowledge of frost depth is needed to accurately predict flooding during spring melt
because frozen soils will not allow water to infiltrate. Without any infiltration into the soil, all water
on the landscape at melt will contribute to flooding. When soils are not frozen, a certain amount of
melt water will infiltrate into the soil and this water does not contribute to flooding. Therefore,
knowledge of frost depth is important in predicting the amount of available water that may
contribute to flooding.
Frost depth can vary over the basin due to weather and snow cover. Early season snow cover
insulates the soil preventing development of soil frost. The River Watch network will measure frost
depth in a variety of watersheds within the basin to determine the spatial variation of frost depth
right before and during melt. Knowing this variability will lead to better predictability of flooding.
Red River Basin River Watch Snow Study
International Water Institute
November 27, 2012
Page 1 of 12
At each River Watch site there will be two measurements of frost depth; one where snow cover
is likely, and one where the snow is blown free. These measurements will compare and contrast
the variability of frost depth due to insulating snow cover between proximate sites.
The measurement of frost depth will utilize frost tubes. A Frost tube is a clear tube that is
placed four feet into the ground. The tube is filled with a colored dye solution that turns clear when
frozen. The tube is periodically pulled from the ground and the depth of frost is determined by
observing the level of frozen (clear) water in the tube.
Soil Moisture Content: Even if the soil is not frozen, the amount of soil moisture will control the
amount of melt water that infiltrates into the soil. Soils that are dry and not frozen will allow for
infiltration at the rate that the soil particles will allow. Soils with a high moisture level will impede
the further infiltration of melt water. As soil frost is reduced through the melt process, water
infiltration is determined by soil moisture levels which vary depending on the amount of melt water
and precipitation patterns. Soil moisture levels (and therefore infiltration) will vary within the basin
as does precipitation patterns. Having the River Watch network track soil moisture levels through
infiltration measurements will help determine how infiltration varies in the basin and its influence
on flooding.
Infiltration is measured through the use of infiltration rings. A ring 6 to 12 inches in diameter is
pounded 1.5 to 2 inches into the ground. With the ring in good contact with the soil, water to a
certain depth is poured into the ring. The water in the ring is then periodically measured to
determine how far the water drops over time. By measuring infiltration several times at - and
during melt - information will be gained on how infiltration is affected by soil moisture and frost
depth. The infiltration rates at different times and at varying locations in the basin will be used to
better understand flooding and increase the predictability of floods.
Utilizing the River Watch network to measure; 1) snowpack and water equivalency, 2) frost depth, and
3) infiltration, will allow for better understanding and increased predictability of spring floods within the
basin. Individually knowing these factors will help in understanding and predictability, but by combining
the results together and interpreting how these factors interact a better overall understanding of
flooding will be gained. Knowing that a snowpack has a significant amount of water in comparison to
snowpacks from other floods is critical to prediction, but also knowing that this water will or will not
infiltrate into the soil is vital to help understand the potential flood magnitude.
Additional Monitoring and Research Opportunities
In order to better understand factors that influence flooding and contribute to the predictability of
floods, the critical period of monitoring is just prior to and during spring melt. However, monitoring of
snow and frost throughout the winter provides further opportunity to understand the interplay of
conditions that lead up to and can produce significant variability in the factors that influence flooding.
The additional measurements that River Watch teams are encouraged to take throughout the winter
relate to standard snow measurements that are part of the Community Collaborative Rain, Hail, and
Snow Network (CoCoRaHS), http://www.cocorahs.org/Content.aspx?page=snow, specifically:
1.
2.
3.
4.
The accumulation (depth) of new snow (new snowfall)
Liquid water equivalent of new snow
The total depth of new snow and old snow and ice at observation time
Snow Water Equivalent (SWE) of total snow on the ground
Red River Basin River Watch Snow Study
International Water Institute
November 27, 2012
Page 2 of 12
These additional measurements will depend on access to the monitoring site, time constraints, and
availability of volunteers. Following is a minimal and optimal schedule for measurements to be taken. It
is recognized that since the monitoring sites for this project will often be near the participating school,
regular readings over weekends and holidays may not be possible. Participants are encouraged to make
their best efforts and enjoy the activity. After a period of time, participants will get a better idea of what
is involved and the interesting results that can be obtained from regular monitoring.
The minimal measurement guidelines noted below relate to the primary objectives of this project and
the readings most desired by the National Weather Service for flood forecasting at the critical time of
spring snowmelt and runoff. Additional measurements throughout the winter will aid the NWS in
preparing preliminary flood forecasts and will begin building a research data base for long term analysis
and understanding of these flood forecasting factors.
Measurement Optimal frequency
Minimal/alternate frequency
New Snowfalldepth
Total snow and
ice depth
New Snowfallsnow water
equivalency
Total Snow
Water
Equivalency
Frost Tube –
open wind
blown area
Frost Tube –
normal snow
area
Infiltration Ring
Daily—after each new snowfall. Also daily
reporting of no snowfall is useful information.
Daily (but not necessary)
Can do multi-day accumulation
report or measure/report weekly
Weekly or after new snowfalls or
during significant melt periods
After each new snowfall both from 1.) snow that
falls in outer rain gauge and from 2.) snowboard
core
Weekly as time and schedule allows—Monday
morning before 9 a.m. preferred.
Multi-day accumulation or
weekly
Daily to weekly readings - begin as soon as frost
starts forming. Continue through spring melt as
frost comes out of ground.
As directed by NWS at time of spring snowmelt—
otherwise avoid compacting snow at this site
which would compromise insulating effect of snow
At time of spring snowmelt as directed by NWS
Monthly and at spring snowmelt
when called for by NWS and Flood
Forecasting Center
At time of spring snowmelt when
infiltration ring measurement is
taken or directed by NWS
Following initial reading, can take
as often as desired till frost leaves
ground
After initial reading, can move
ring to do additional trials
Acknowledgement
This snow study research is part of a larger project made possible due to a special two year grant
provided by the Minnesota Clean Water Fund (from the Clean Water, Land and Legacy Amendment).
Funding was provided to expand and enhance the Red River Basin River Watch Program, expanding on
opportunities to advance watershed science through youth leadership, curriculum integration, and
applied research.
The Clean Water Fund: Protecting and restoring
Minnesota’s waters for generations to come
Red River Basin River Watch Snow Study
International Water Institute
November 27, 2012
Page 3 of 12
SNOW DEPTH AND WATER EQUIVALENCY STANDARD OPERATING PROCEDURES
Note: Monitoring methods used by the National Weather Service will be used for snow depth and SWE.
An excellent training slide show, “In Depth Snow Measuring” should be watched by all monitoring
participants (http://www.cocorahs.org/Content.aspx?page=training_slideshows). The slide show can
also be downloaded as a PDF for reference. The following is a summary of these methods.
New Snowfall Measurements:
Depth: Measured with a ruler which is pushed down through the new snowfall to the base of the
snowboard. Readings are recorded in inches to the nearest tenth of an inch.
Snow Water Equivalency: two methods are to be used:
1.) Rain gage deposition: snow that falls into the 4” outer tube of a rain gage that is placed near the
snow board. Transfer this new snowfall to a plastic bag, container, or bring entire tube inside to
melt the snow. Pour melted water into the inner rain gage tube to measure as normally done
with precipitation and report as inches of precipitation to the nearest hundredth of an inch.
2.) Snow Board Core: take a snow core from the snow board by pushing the 4” outer tube of the
rain gage down into the snow on the snow board and slip spatula or similar rigid material under
the rain gage to hold snow in the tube while inverting (or lift board and slide trapped snow into
a bag or container). Melt and measure snow as above.
Total Snow and Ice Measurements:
Depth: Measured with a yard/meter stick which is pushed down through all new and old snow and ice
to the ground. Take depth readings in several spots (6-10 spot readings are recommended to provide a
good average) in a large area that represents “normal” snowfall (not open, blown area). Average your
depth readings and record in inches to the nearest half of an inch. It is preferable to take multiple
measurements over a larger area to account for natural variability.
Snowpack Snow Water Equivalency: From sites that are representative of your average depth, take
two (2) snow cores [ideally, up to four (4) snow cores can be collected and melted to provide a more
accurate SWE value] by pushing the 4” outer tube of the rain gage into the snowpack to the ground
surface. Transfer this snow core to a plastic bag. Collect the remaining core(s) in same manner. Bring all
samples inside to melt individually. Pour melt water into the inner rain gage tube to measure as
normally done with precipitation and record as inches to the nearest hundredth of an inch. Repeat with
the other individual core sample(s) and average your results for your final Total SWE value.
Points to consider when coring snow:
1. When coring, it may help to use a spatula like device or piece of sheet metal that is slid under the
tube to trap the snow in the tube. Light fluffy snow can easily be lost from the tube when lifted
from the ground surface. Use of the spatula like device helps avoid snow loss and undermeasurement of SWE.
2. For deep snow, the outer tube may not be long enough to take just one core. When encountering
deep snow successive cores will be needed or use a longer tube with a four inch inside diameter.
This much snow when melted may be more than can be measured in the inner tube at one time.
Successive measurements of the water from one sampling site might be needed.
3. Melting snow can take a long time. So plan to let the snow stand overnight in the bag. Make sure
the bag does not leak. Putting the bag of snow in a warm water bath will speed the melting
process. Use of a microwave should be avoided. Microwaves on high power can burn snow
before melting.
Red River Basin River Watch Snow Study
International Water Institute
November 27, 2012
Page 4 of 12
Below are a series of pictures demonstrating the coring of snow from the National Weather Service. See
“In Depth Snow Measuring” at http://www.cocorahs.org/Content.aspx?page=training_slideshows.
When measuring snow
depth read it at eye level
Trapping snow with
spatula like tool
Coring the
snowpack
Snow core ready
to be melted
Reading amount of water in snow
core – snow water equivalency
Pouring melted snow
core into inner tube
Red River Basin River Watch Snow Study
International Water Institute
November 27, 2012
Page 5 of 12
In summary, the final slide in the “In Depth Snow Measurement” slide show is shown below with yellow
areas highlighting the more fundamental measurements requested (and easiest to take) with the
turquoise cells showing “optional” snow water equivalency measurements for new snowfall and total
snow on ground.
Red River Basin River Watch Snow Study
International Water Institute
November 27, 2012
Page 6 of 12
FROST TUBE STANDARD OPERATING PROCEDURES
NOTE: For most participating schools two frost tubes will be installed; one where average snow cover is
present—likely in the vicinity of your snow measurement area, and one where snow is likely to blow
free. Regular measurements can be taken at the frost tube in the blown/open area. For maximum
usefulness in providing representative frost depth readings from the tube in the snow covered area for
spring flood forecasting, it is recommended that NO readings be taken of this tube until needed at the
time of spring snow melt. The National Weather Service will provide guidance on the optimal timing for
this reading. If at all possible, foot traffic that could cause compaction and loss of insulating properties
of the snow cover should be avoided in the vicinity of the frost tube in the snow covered area.
OPERATING PROCDURE

To read the depth of frost,
remove the insulated cover
and pull out the inner tube.
Where the lime green dye
starts is the depth of the frost.
The dye turns clear when it is
frozen. Find the frost depth in
tenths of an inch by
measuring down with a ruler
or tape measure from the
ground surface mark to the
color change in the dye. If
there are no clear spots on
the tube the soil would be
deemed to be frost free.
Ground Level
Frozen Solution
=Frozen Ground
(dye turns clear)
Frost Depth
(dye colored
-not frozen)

The number of readings of the
snow site frost tube is
dictated by how often the NWS wants readings and/or the availability and interest from study
participants in data collection and research beyond the minimum forecasting needs. At minimum
the tubes will be read at spring runoff. Frost tubes in the blown/open areas where compaction is
not an issue can be read regularly to gauge the depth of frost through the winter.

At this time, frost tube readings will be placed in the “Observations” section of the online
CoCoRaHS data entry form as there is not a specific entry line for frost tube readings. Participants
will be notified if an alternative data entry process is developed for entering data directly to the
River Watch data website. An Excel data entry template is available for those interested in tracking
their data in this manner as well— http://www.iwinst.org/education/projects/snow-studies-2
NOTE: During spring melt the center of the tube may remain frozen (clear) as frost recedes from both
top and bottom due to surface and geothermal warming respectively. There could also be a secondary
frost from the top if a cold spell settles in after initial thawing.
CAUTION: After reading frost depth of inner tube, place it gently back into outer tube in ground as the
frozen top is susceptible to breaking if dropped back into outer tube.
Red River Basin River Watch Snow Study
International Water Institute
November 27, 2012
Page 7 of 12
INFILTRATION RING STANDARD OPERATING PROCEDURES
Infiltration rate: The infiltration ring is designed to measure infiltration rates of water into the soil. Prior
to and during melt is when the ring will be operational. The process for taking measurements is:
1.) If your infiltration ring still has snow in it, gently scoop it out—a little snow in the bottom will not
hurt since the water poured into the ring will melt that snow turning it to water. You do not need to
clear all leaves or grass to bare dirt—minimal debris such as this will not impede water infiltration.
2.) Stick a ruler into the ring to ground level and leave there while taking your infiltration
measurements. You may want to use a clamp or vice-grip to attach your ruler to the inside of your
infiltration ring so it stays at the same level throughout the recording period or note a reference
height on the ruler at the top of the ring when it is at ground level inside the ring.
3.) Fill the ring with COLD water so that there is approximately 4 inches of water standing in the ring.
Pour the water into the ring to avoid disturbing the soil or making a gap at the edge of the ring.
Often a piece of plastic is laid in the ring and water is poured onto the plastic to reduce soil
disturbance. Remove the plastic after pouring.
4.) Right after pouring water into the ring the height of water is read on the ruler and the timing begins.
After this first water height reading the height of the water will then be read at the recommended
schedule of: 1 min, 2 min, 5 min, 10 min, 15 min, 30 min, 1 hour, and 2 hours later (and 4 hours
later, optional). Record and report these results.
The rate at which the water recedes is the infiltration rate in inches per unit of time. Because infiltration
rate is nonlinear the rate is generally faster right after the water is added and slows with longer times.
Normally infiltration rates slow significantly with time and stop after several hours, so the four hour
reading may be nearly the same as the two hour; that is why it is optional.
Several conditions should be avoided when operating the infiltration ring:
1. Avoid cold days where the water in the ring will freeze. Try and operate the infiltration ring when
temperatures are above freezing.
2. Do not use hot water—or even inside room temp water. Water should be cold to match current
conditions. Hot water will cause the soil to thaw leading to erroneous readings.
3. Make sure the frost and freeze action has not caused the ring to shift making gaps between the
bottom of the ring and the soil where water can bypass the soil and flow under the ring.
With soils that are deeply frozen there may only be a small amount of infiltration. In soils that are not
completely frozen or where frost is not deep there may be higher rates of infiltration. As the melt
continues the frost in the soil will erode from the top and bottom resulting in more infiltration potential.
This potential infiltration can be reduced if the soils have high levels of moisture. If the infiltration rate is
high enough such as found in sandy soil the water in the ring may drop to the soil surface level in less
than an hour. This is fine and there is no need to put in more water.
Repeated use of the infiltration ring in the same location should be avoided because the water from the
previous operation affects the subsequent operation of the ring. Once the frost has disappeared from
the upper couple inches of the soil the ring can be moved to another location close by, avoiding the
effects of the prior operation. The number of times to operate the infiltration ring will be a yearly
decision dependent on the changing conditions and needs. The ring can be removed after the last
measurement in the spring and then reinstalled next fall. Fall measurements can also be taken to assess
soil moisture content at the start of the winter.
Red River Basin River Watch Snow Study
International Water Institute
November 27, 2012
Page 8 of 12
Following is a table you can use for recording your infiltration rates (also available on infiltration rate
worksheet in Excel snow study data entry template noted above.
Date: ___________________
Site
(CoCoRaHS
ID)
Time
(hrs:min)
0:00
Start time: ______________
Water height
on ruler
(to nearest
tenth of an
inch)
Notes (observations, photos…)
Water height after initial pour
0:01
0:02
0:05
0:10
0:15
0:30
1:00
2:00
4:00 (optional)
Decimal
conversions
1/16" =.1
1/8" =.1
3/16" =.2
1/4" =.3
5/16" =.3
3/8" =.4
7/16" =.4
1/2" =.5
9/16" =.6
5/8" =.6
11/16"=.7
3/4" =.8
13/16"=.8
7/8" =.9
15/16" =.9
Snow depth in immediate vicinity of
your infiltration ring (nearest half inch): __________
General observations: (e.g. frost depth from nearest frost tube, vegetative cover, any
disturbances or compaction of snow near the ring, air temperature, etc.)
Red River Basin River Watch Snow Study
International Water Institute
November 27, 2012
Page 9 of 12
Data Management
Participants in this study will use the Community Collaborative Rain, Hail, and Snow (CoCoRaHS)
network for data entry. Users will be notified if any changes are made such that data would be entered
directly to the existing River Watch data site (and automatically linked/entered into CoCoRaHS).
Each participating school needs to initially individually register as a CoCoRaHS Observer. Go to “Join
CoCoRaHS” at http://www.cocorahs.org/Application.aspx. There is no cost to sign up as an observer. At
this online registration, for your “Station Information” enter information related to the “snow” site
location where you will be collecting snow depths and snow water equivalency data from. If you don’t
have lat/long coordinates for your site go to Google maps and zoom in on your site and copy the
coordinates that would put you close to your site—enter this on the CoCoRaHS registration form.
In the rain gauge section, mark that you already have this type of gauge (one will be provided if you
don’t have one already). As for time of day gauge will be emptied, I would suggest 8 a.m. rather than the
7 a.m. they recommend—or whatever you feel will work best for you. You can always change this later
after you become more familiar with what works best for you, etc. As for training preference at the
bottom, I believe “on-line” will likely be our only option, though we will have several technical resource
experts at our disposal to assist in any needed training.
Once you submit your registration you’ll receive confirmation and an email welcoming you to CoCoRaHS
in Minnesota with an attached PDF that provides more background information about the program and
instructions for logging into the CoCoRaHS website. Your Station Name and number will be explained
along with how to report data to the system including multi-day accumulation reporting if daily readings
are not possible. Reviewing your data in various formats is explained.
To enter your data you’ll need to log in and fill out the precipitation reporting form shown on the
following page. It will automatically assign your station number and name based on your login.
Additional information on most fields is available by selecting a “?” icon next to the field. From the
Printable Forms web link, http://www.cocorahs.org/Content.aspx?page=PrintableForms, you can access
a data reporting form in PDF format or in Excel. The Excel format has a worksheet for each month with
some automatic graphing functions built in. An alternative Excel template which includes frost tube
entry cells is available at http://www.iwinst.org/education/projects/snow-studies-2.
The above procedures will undoubtedly be modified based on lessons learned and suggestions from
project participants. Ideas are welcome/encouraged as we strive to better understand flooding issues in
the Red River Basin. For your reference, the following contacts are included as resources for you to call
upon if you have questions, observations, or ideas about the current project or further study. Thank you
for your participation! Have Fun-Stay Warm!
Contacts:
Wayne Goeken-International Water Institute: 218-574-2622
Jack Norland-NDSU-Prof Range Science-Project Advisor: 701-231-9428
Mark Ewens-NWS-Grand Forks: 701-772-0720x327
Michael Lukes-NWS-Grand Forks: 701-772-0720x493
Andrea Holz-NOAA-Chanhassen: 952-368-2535
David DeMuth-VCSU STEM Ed Center: 701-845-7437
Red River Basin River Watch Snow Study
International Water Institute
November 27, 2012
Page 10 of 12
Following is the CoCoRaHS basic data entry form for daily precipitation. It is quite straightforward. It also
allows you to go back to previous days if you recorded data on hard copy field data sheets but just
haven’t had an opportunity to enter it electronically yet. Your frost tube depths would go into the
“Observation Notes” section.
Red River Basin River Watch Snow Study
International Water Institute
November 27, 2012
Page 11 of 12
The following field sheet can be used prior to transferring data to Excel files or to the online reporting format.
Red River Basin Snow Study Field Sheet
Station #
Date
Time
Sampler
(eg.)MN-PK-2
Open site-Frost
Tube snow cover
Open Site-Frost
Tube Depth
Open site-Frost
free top of tube
New Snow Depth
(snow board)
New Snowfall
SWE-snobd core
New Snowfall
SWE—from gage
Total Snow
Depth 1
Total Snow
Depth 2
Total Snow
Depth 3
Total Snow
Depth 4
Total Snow
Depth 5
Total Snow
Depth 6
Sum of Total
Snow Depths
Average Total
Snow Depth
Total Snow
Depth SWE
Snow Site Frost Tube data below taken in spring when directed (likely same time as infiltration ring measures)
Snow site-Frost
Tube snow cover
Snow Site-Frost
Tube Depth
Snow site-Frost
free top of tube
NOTES: (separate page) air temp, wind, other observations
Red River Basin River Watch Snow Study
International Water Institute
November 27, 2012
Page 12 of 12