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WATER RESEARCH TECHNIQUES
Table of Contents
Precipitation and Climate Data ....................................................................................... 2
Using a rain gauge ...................................................................................................... 2
Existing Precipitation Data ......................................................................................... 3
Water Research Techniques: Infiltration, Percolation and Compaction .................... 4
Choosing sample sites ................................................................................................. 4
Testing Compaction .................................................................................................... 4
Testing Infiltration ...................................................................................................... 4
Testing percolation...................................................................................................... 5
Water Research Techniques: Transpiration .................................................................. 7
Transpiration monitoring techniques .......................................................................... 7
Water Research Techniques: Identifying the Unknowns For Water Data ............... 10
Identifying the Unknowns......................................................................................... 10
Thinking about the holes in the data ......................................................................... 10
BioComplexity and the Habitable Planet
Unit 1 – Handbook - 1-17-08 draft
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WATER RESEARCH TECHNIQUES
PRECIPITATION AND CLIMATE DATA
Included are two methods of gathering precipitation data. The first uses a rain
gauge to collect precipitation as it falls during rainstorms. The second provides a guide
for finding data on precipitation and other climate factors from other sources.
Using a rain gauge
A rain gauge provides a method of measuring precipitation in a given area. For
this exercise you will only record precipitation of the two-week period you are in your
research groups. As you collect your data think about how your recordings from the rain
gauge might vary over the course of the year. How might the amount precipitation in
February differ from the amount of precipitation in July in your area. You can also set up
your rain gauge to catch irrigation water from overhead sprinklers, if that happens to be
the main source of water for certain areas of your school grounds during the two week
period in which you collect in your expert groups.
Constructing a Rain Gauge
Materials
Low-cost / less accurate option
 Flat bottomed containers (marked or unmarked)
 Large Funnels (optional)
Higher-cost / more accurate option

All you need is a flat-bottomed container such as a plastic gallon milk container to
catch and hold the rain. Inserting a funnel will minimize water evaporation.
Placing your rain gauges
Carefully choose the placement of your rain gauges and record the location on
your map.
Alternatively, place your rain gauges in sprinkler irrigated areas to
estimate the amount of irrigation water pumped onto your school grounds.
Measure the volume of rainfall
Empty the contents of the rain gauge into a beaker after each rainfall event to
measure the volume of rain that fell. To express this as a volume of rain per unit area,
remember that the area of the funnel mouth represents the “catchment area.”
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WATER RESEARCH TECHNIQUES
Existing Precipitation Data
Since you will be unable to monitor the amount of precipitation that falls at your
site for an extended period of time, look for precipitation data recorded close to your
school and find the average monthly precipitation for your area.
The national weather service (http://www.nws.noaa.gov) and other government
agencies have this data on their websites. Weather websites such as
www.wunderground.com or www.weather.com may also assist you in your search.
Also look up average monthly temperature. Create a graph for each. You can
even combine these two data into one graph, called a climatogram.
Compare climate data over various years. What patterns do you see? How do
temperature and rainfall relate to one another? How do you think this might influence
other factors in an ecosystem, such as vegetation growth or nitrogen flow?
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WATER RESEARCH TECHNIQUES
WATER RESEARCH TECHNIQUES: INFILTRATION,
PERCOLATION AND COMPACTION
Choosing sample sites
Choose a number of spots in each different type of land cover that appear to be
representative of that type of land cover. Alternatively, you might consider choosing
spots that are close to the sample sites chosen by the Biotic Factors expert group. Use a
1x1 meter square quadrat to create the boundaries of your sample plot and make sure to
mark down the location of the sample plot on a copy of your base map,
Use the plots for three tests: infiltration; percolation; and compaction,
conducting them in separate locations within the sample plot since the tests could
interfere with each other.
Testing Compaction1
Materials:
Pencil
Ruler.
1) One student should press the sharp end of a pencil into the ground with the palm
of the hand. The pencil should be vertical, and the student should apply exactly
the same amount of pressure on the pencil for every measurement.
2) Once the pencil has been pushed into the ground, grasp the pencil right near the
ground and carefully remove it.
3) Use a ruler to measure how many centimeters the pencil penetrated the soil. This
test will indicate how compaction may vary at different locations on the study
site.
4) Record your findings in your journal.
Testing Infiltration
Materials:
Tin can
Board.
Hammer
Beaker
1
Adapted from Global Lab Unit II: Our Earth: Land.
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WATER RESEARCH TECHNIQUES
100ml water.
1) Working in pairs, place a mark on the inside of a tin can 3-5 cm from the
bottom edge of the can.
2) Drive the can into the ground 3-5 cm deep. You may have to remove leaves,
stones, twigs, and excess vegetation to ensure the can is flush against the soil.
If the soil is too hard, place a board over the can and tap it with a hammer
until the desired depth is reached. Make sure that the entire bottom edge of
the can is sufficiently buried so that no water can leak from the side of the
can. (If the land cover you are studying is a hard impervious surface, you will
obviously not be able to conduct this test, but will instead assume - and
record- no infiltration.)
3) One student should start a timer as another pours 100ml of water into the can.
4) Watch as the water drains into the soil. As the water drains, the soil surface
will first shine and then become dull. Record the time in minutes and seconds
went the soil first becomes shiny and then when it becomes dull.
5) Record your findings in your journal.
Testing percolation
Materials:
Scissors
1-liter plastic bottle
elastic band
Cheese cloth or filter paper
Measuring cup
Masking tape
Pitcher
Stopwatch or clock with second hand.
Conduct the following procedure for soil samples taken from each of your sample
plots in each of the different land cover areas of your school. After you have tested
infiltration, take a sample of the soil for the percolation test, which you will conduct in
the lab. Be sure to label each soil sample with the location and record the location on
your map.
1) With the scissors, cut off the bottom of a 1-leter plastic bottle so when inverted, it
makes a funnel. Using an elastic band, securely fasten a piece of cheesecloth or
filter paper across the bottle’s mouth.
2) Place the funnel in the measuring cup. Place part of a sand sample in the funnel
and use a piece of masking tape to mark the level it reaches in the funnel.
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WATER RESEARCH TECHNIQUES
3) Fill the pitcher with a measured amount of water. Record eh amount of water
used. Pour the water into the funnel, noting the time when you start.
4) Note how long it takes the water to flow though the sand in the funnel into the
measuring cup. Record this time.
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WATER RESEARCH TECHNIQUES
WATER RESEARCH TECHNIQUES: TRANSPIRATION
Transpiration monitoring techniques
You will measure water loss via transpiration from the plants in your schoolyard
ecosystem using the following two techniques. One is a field technique while the other is
done in the classroom laboratory. Choose whichever technique is most appropriate for
your research situation.
Field Based Transpiration Activity
Starter Questions:
What factors do you think determine how much water plants lose through transpiration?
Overview:
In this study you will have a chance to investigate first hand the process of transpiration,
or the loss of water from plants via evaporation. You might want to compare leaves in
different micro-environments, (e.g., sunny vs. shaded) of two kinds of plant (e.g., oak vs.
maple). You also will have to consider how many replicates you will need so that you
will have confidence in your results.
Materials:
1-qt or 1-gal clear plastic bags (at least 4 per group)
Masking tape for sealing bags on twigs
Twist ties or masking tape for marking twigs
Permanent marker for marking twigs
Ruler for measuring leaves and twigs
Graph paper for tracing and measuring leaf area
Graduated cylinder or marked beaker (for final day only)
Hand lopping sheers or strong scissors (for final day only)
Procedure:
1. Decide on what comparison you want to make, then select and bag branches.
Choose at least two branches approximately 15cm long (as replicates) in each of the
situations you've decided to focus on. All branches should be as similar as possible, and
each should be able to fit into the plastic bag.
2. Mark each branch with a twist tie or tape, and label them in some way (e.g., 1 to 4).
Record which number corresponds to which branch.
3. Carefully place the branch with all its leaves in the bag and seal the bag onto the
branch at tightly as you can without damaging it.
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WATER RESEARCH TECHNIQUES
4. Collecting data about transpiration.
Carefully remove the plastic bag from the branch, making sure you don't spill any water.
Pour the water into a marked beaker or graduated cylinder to determine the volume of
water that was lost from the twig. Record this amount.
Repeat this procedure for each branch.
5. Calculate the amount of water that transpired per square cm of leaf:
(1) Clip the part of the branch that was in the bag, or just its leaves.
(2) Lay the clear cm grid over each leaf and estimate its area.
(3) Add up the areas of all of the leaves to get a total amount of leaf area that was in each
bag.
(4) Divide the volume of water by the total leaf area to express transpiration as ml water
per square cm of leaf.
6. Extrapolate to water loss from the schoolyard
(1) Estimate how many leaves are contained in the schoolyard by counting leaves on a
subset of branches and then calculating the total number.
(2) Things to consider:
- Length of time you measured transpiration
- Possible impact of current conditions, e.g., humidity, temperature, solar
radiation, on transpiration rate
- Aligning your transpiration estimate with the units you’re using to construct the
model of water flow for the whole schoolyard.
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Unit 1 – Handbook - 1-17-08 draft
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WATER RESEARCH TECHNIQUES
Laboratory Based Transpiration Activity2
Materials for each lab group:
4 test tubes
4 corks, stoppers with holes, or balls of modeling clay
4 plant cuttings
Large graduated cylinder
Water
Fan
Grease pencil.
Safety
Follow standard safety rules and school safety rules for laboratory activities.
Procedure: Set Up
1) Cut two stems of similar size from selected plants. The stems should contain three
or four healthy leaves of approximately the same size (leaf surface area).
2) Carefully cut the end of the stem while it is under water to prevent air pockets
from forming in the stem.
3) Insert the stems through the holes in the stoppers or ball of modeling clay. Use
modeling clay to seal the hole.
4) Insert the stopper with the stem into a test tube that is 3/4 full of water. The stem
should be well below the waterline.
5) For all for plants, mark the water level on the test tube with a grease pencil.
6) Place the stems in a similar environment in a location where they receive
adequate light.
7) Make a data table to record the height of water each day and the general health of
the plant stem. Record your observations.
Procedure: On-going Observations
1) Record the water level daily by using a ruler to measure the distance from the
mark you made to the new level.
2) Graph your results, putting time (days) on the x-axis and water height (cm) on the
y-axis. Discuss your results with your team.
3) If there is time, devise new experiments to investigate the impact of
environmental factors on transpiration rate, e.g., relative humidity, light levels,
etc.
2
Adapted from Edelson, D. (2006). – Investigations in Environmental Science Unit 3: Water Management .
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WATER RESEARCH TECHNIQUES
WATER RESEARCH TECHNIQUES: IDENTIFYING THE
UNKNOWNS FOR WATER DATA
Although you are measuring many aspects of the flow of water through
your school ecosystem, there are still inputs and outputs on which you don’t have data.
You will draw a visual representation of the flows of water though your school’s
ecosystem to assist you with identifying these unknowns.
Identifying the Unknowns
1) Using the water flow diagram pictured below as an example, draw a diagram of
all of the potential flows of water though your school ecosystem. The Water
Flow section of the Primer provides a good reference.
2) Label the inputs and outputs for which you have data and mark the inputs and
outputs for which you don’t have data with a question mark.
3) How does your data help you understand the water flow through your school’s
ecosystem? How might you deal with the gaps in your data? If you had
unlimited time and resources to research the flow of water through your school
ecosystem, what would you collect data on? What research questions would you
like to answer?
Thinking about the holes in the data
Ecosystem scientists also run into the problem that they can’t study every aspect
of the flow of water. Limits in time, money and practicality set limits onto what can be
researched. If this is the case, they might rely on studies conducted by other scientists in
similar systems, thus obtaining data to help ‘fill in the holes.’
BioComplexity and the Habitable Planet
Unit 1 – Handbook - 1-17-08 draft
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