Unit 1: Exploring the Reservoirs and Pathways and Methods to Measure the Hydrologic Cycle
How does water move throughout the Earth system? How do scientists measure the amount of water that moves through these pathways? This unit provides an alternative way for students to learn the major components of Earth's water cycle, which includes actively thinking about how we measure the water system. In this unit, students annotate a schematic diagram to identify the major reservoirs and fluxes in the hydrosphere. They also work in teams of different "experts" to identify traditional and geodetic techniques that are used to measure components of the hydrosphere and the changes over time. Using their recently acquired knowledge about these techniques, they make inferences about which methods are best for measuring different components of the hydrosphere. Measurement methods include stream gauges, groundwater wells, snow pillows, vertical GPS changes, reflection GPS for snow depth, and GRACE satellite (Gravity Recovery and Climate Experiment).
Unit 1 Learning Outcomes
- Illustrate the major reservoirs and fluxes ("transport pathways") in the hydrosphere and relevant measurement techniques using a schematic diagram.
- Compare and contrast the strengths, limitations, and spatial/temporal coverage of different traditional and geodetic methods for measuring the hydrosphere
Unit 1 Teaching Outcomes
- Cognitive: Facilitate students' ability to diagram principal hydrosphere reservoirs and fluxes (transport pathways) and decide which traditional and geodetic methods are most useful for measuring specific hydrosphere components.
- Behavioral: Promote skills in reading and interpreting maps and graphs that show change over time.
Context for Use
The content in Unit 1 is appropriate for introductory geology, environmental geoscience, natural hazards, climate science, and other geoscience courses; sophomore-level courses in which geodesy and/or hydrology concepts are introduced; or non-geoscience courses where water resources and/or the nature and methods of science are being investigated. Unit 1 activities can easily be adapted to serve small or large-enrollment classes and can be executed during class as an interactive lecture/discussion, in-class activity in which students work in small groups; or as part of a 2-3 week investigation of the use of geodesy and other methods to study water resources using the entire Water Hazards and Resources module. If the entire module will not be utilized, we recommend pairing Unit 1 with Unit 2: Monitoring surface and groundwater supply in the western US to allow students to apply their content knowledge of hydrosphere reservoirs and fluxes and the methods to measure them to address water issues in different study areas.
Description and Teaching Materials
Unit 1 of this introductory-level module largely focuses on qualitative understanding of the water cycle. GETSI also has a majors-level module Measuring Water Resources with GPS, Gravity, and Traditional Methods that is much more quantitative. Optional Slides for this unit (PowerPoint 2007 (.pptx) 15.7MB Feb14 22) draw from that more advanced module. It includes quantitative approaches to the water cycle and images related to the different measurement methods covered in the Unit 1.2 readings. Some introductory instructors may choose to refer to slides in this presentation as students are working or to facilitate student summing up of work at the end of a discussion/activity in Unit 1.1 and Unit 1.2.
Unit 1.1: Reservoirs and transport pathways of the hydrosphere
Preparation prior to class:
Optional reading: As an introduction to the societal relevance of measuring water distribution and water's movement through the hydrosphere, instructors may ask students to read one or more of the following articles from the InTeGrate Project's Water: Science and Society module related to the interaction between humans and water resources:
- Societal and Economic Implications of Floods
- How do you know when you're in a drought?
- Floods and droughts impact ecosystems
- Salt Lake City: a case study in water development history and planning for the future
- The survival of Las Vegas
- Cities in peril: LA
- Identify the major reservoirs represented in the diagram and label these reservoirs with words;
- Identify the major transport pathways between reservoirs using arrows and process names/descriptions.
- Unit 1.1 - Student Preparation Exercise (Microsoft Word 2007 (.docx) 203kB Feb14 20)
- Water cycle diagram color (Acrobat (PDF) 2.6MB Feb26 20)
Water cycle diagram black-white (Acrobat (PDF) 2.1MB Feb26 20)
During the class meeting:
Begin the class meeting by placing in students in groups of 2-3 and give them an identical, blank diagram to the one that they used for the preparation exercise. Instruct students to look for commonalities and differences between the diagrams that they prepared and compile a group diagram. Depending on time constraints, classroom configuration, and enrollment, instructors may choose to have each group of students sketch their diagram on the board to give everyone an opportunity to see all of the diagrams. This, along with the supporting slides for Unit 1.1, provides the basis for a whole-group discussion about major hydrosphere reservoirs and transport pathways. For the purposes of this exercise, student diagrams should include at lest most of the following reservoirs and transport pathways (additional components are fine):
- Reservoirs: surface water (ocean/lakes/rivers/streams/inland seas); atmosphere; cryosphere (snow/glaciers); snow; vegetation/soil moisture; groundwater
- Transport pathways: evaporation; evapotranspiration; condensation; precipitation; runoff; infiltration; groundwater outflow to rivers/lakes/streams and ocean
This exercise could alternatively be assigned as a homework, and class time could be used to focus on the ensuing discussion.
Unit 1.2: Traditional and geodetic methods for tracking water
Preparation prior to class:
Each student is assigned one of the traditional or geodetic techniques used to measure/characterize hydrosphere components below and is instructed to be ready to teach his/her/their group members about the technique during the next class meeting.
The 1-pagers for each technique include some brief explanatory text and supporting figure(s) about how the method works, an example time-series, a link to some type of multimedia (animation, film clip, tutorial, etc.) about the method, and a couple of additional web resources that provide additional information. Some instructors might choose to distribute these 1-pagers to students, while other instructors might choose to only give students the preparation instructions and web resources and instruct them to make their own summary documents about their assigned technique.
- Stream gaging: Unit 1.2 student preparation materials: stream gaging (Microsoft Word 2007 (.docx) 543kB Feb14 20)
- Short video: Streamflow Gaging Station and Measurement
- Depth to groundwater: Unit 1.2 student preparation materials: depth-to-groundwater (Microsoft Word 2007 (.docx) 502kB Feb14 20)
- Vertical GPS: Unit 1.2 student preparation materials: vertical GPS (Microsoft Word 2007 (.docx) 1.4MB Feb14 20)
- GRACE: Unit 1.2 student preparation materials: GRACE (Microsoft Word 2007 (.docx) 1.6MB Jul17 20)
- Reflection GPS to measure snow depth: Unit 1.2 student preparation materials: reflection GPS and snow depth (Microsoft Word 2007 (.docx) 593kB Jul8 20)
- Short video: Measuring Snow and Soil with GPS
- SNOTEL: Unit 1.2 student preparation materials: SNOTEL (Microsoft Word 2007 (.docx) 1.8MB Feb14 20)
- Short video: Snow Science: Measuring Snowpack and SNOTEL
During the class meeting:
- Unit 1.2 Slides walking through the exercise's steps (PowerPoint 2007 (.pptx) 1017kB Jul15 20)
- These couple slides include the same instructions as described below to provide visual support to the instructions given.
- These couple slides include the same instructions as described below to provide visual support to the instructions given.
At the beginning of the next class meeting, students will convene with other students who were assigned the same technique and be given the following instructions:
First, please meet with your classmates who researched the same technique as you did for today. In your groups, please spend several minutes discussing the answers to the following questions. If there is any disagreement or uncertainty about any of these questions, please ask so that the discrepancies/uncertainty can be resolved before you teach your colleagues who are unfamiliar with the technique that you have researched. For Unit 1.2, it can be helpful to pass out sheets on which to take notes about the methods they learn about, with prompting questions to make sure to answer about each method. Unit 1.2 Student expert group notes sheet (Microsoft Word 2007 (.docx) 205kB Jul15 20)
- What is the name of the method?
- What type of equipment is used in conjunction with this method?
- How does this method work?
- Over what timescale(s) is the method used?
- If the data for this method are plotted, what does a time-series look like?
- What might different patterns in the data indicate about what is happening hydrologically in the area being studied?
- For which reservoir(s) and/or transport pathway(s) of the hydrologic cycle is the method typically used?
- Discuss the thought questions that went along with your method.
Students will then form teams with one SNOTEL, GRACE, vertical GPS, reflection GPS, depth-to-groundwater, and stream gaging representative and be given the following instructions:
You will now be paired with classmates who researched different methods for measuring parts of the hydrologic cycle. Your group should have a representative for stream gaging, depth-to-groundwater, vertical GPS, GRACE, reflection GPS, and SNOTEL.
First, each person should provide a ~5 minute summary of his/her/their method, including the items that you just discussed with your previous group. If you have any questions about a particular method, please ask during the presentation of that method. Once you have completed the presentations, please complete together as a group.
- Unit 1.2: How do we measure the hydrosphere? - student group exercise (Microsoft Word 2007 (.docx) 529kB Feb14 20)
This portion of the class meeting could be implemented as a modified gallery tour in which these questions are displayed on large pieces of paper around the classroom; teams rotate from station to station, answer the questions, and place their answers to the questions in an envelope next to the station to archive their answers and provide some formative assessment data. Alternatively, teams could work through these questions in a handout with their group members.
Finally, students should add each of the six techniques to their hydrologic cycle diagrams adjacent to the appropriate reservoir(s) and/or transport pathway(s) for which each traditional/geodetic technique is suitable. Instructors may choose to collect students' diagrams for formal assessment purposes or have a class report-out and discussion of any disparities in student responses.
Student Discussion Questions for unit 1
Some instructors might choose to pose some discussion questions for students to consider as an entire class or in smaller groups. Think-pair-share, small-group discussion, gallery tour, or whole-group discussion formats are equally appropriate. Faculty may choose to select a subset of these questions depending on time constraints, enrollment, etc.
- Identify the following as either transport pathways (TP) or reservoirs (R) in the water cycle: lake, river, tropical storm, spring, aquifer, groundwater withdrawal.
- From which reservoirs do human beings take water for municipal, agricultural, and industrial use? Which transport pathways deliver water to and remove water from these reservoirs?
- How, if at all, do you think storage in each hydrosphere reservoir changes over 1 year? What is driving these changes in a year's time?
- Which components of the water cycle are particularly important to your community?
- Which components of the water cycle are particularly vulnerable to climate change?
- How might rising sea levels impact water resources near coastlines?
- In what type(s) of watersheds would SNOTEL stations be important for monitoring water supply?
- Compare and contrast the usefulness of 'depth-to-groundwater' well data vs. GRACE satellite data.
- Name 2 ways that GPS stations can provide data about a particular area's water supply/water availability.
- How might the way water managers track water in a humid region of the eastern US be different than in a dry, mountainous region of the western US?
- Give an example of a hydrologic reservoir on Earth that is particularly vulnerable to climate change. What instruments/techniques might permit detection and measurement of that loss of water storage?
- How might folks have kept track of water resources 100 years ago? How many of those technologies are still in use today?
Teaching Notes and Tips
- To save time, Unit 1.1 can be implemented as pre-class homework whereby students come to class with a labeled diagram that can be subsequently modified during the class meeting. Some instructors may choose to assign the hydrologic cycle diagram for homework at the same time that they assign the Unit 1.2 preparation exercise.
- The class period that you assign the Unit 1.1 prep exercise, if you have students with mostly urban experiences, you may want to quickly walk them through the diagram when you give the assignment. Students who have rarely seen an agricultural field may not recognize everything in the picture.
- Forming jigsaw groups can be chaotic in large classes. Expect it to take some class time, unless you pre-assign jigsaw groups. (For example, you could have students break into groups of 6 during the previous class meeting. Then, each group of students gets a SNOTEL handout, a reflection GPS handout, etc., and they assign themselves a method. The next class meeting, they know who is in their group because they chose last time.)
- Have a plan for students who missed the previous class meeting and do not have an assigned technique. One potential solution to this problem is to assign the techniques 2 class meetings before they will be used, then if any students were absent, hopefully they will be present during the next class meeting and have the opportunity to receive a technique to prepare. Referring students to the "Student Materials" page at the onset of the module may also be useful because absent students can access materials if they miss a class meeting.
- Students may need additional help answering some questions about the technique/method that they were assigned. The most common problematic questions during testing were as follows:
- If the data for this technique are plotted, what does a time-series look like?
- What might different patterns in the data produced by this technique indicate about what is happening hydrologically in the area being studied?
- During the jigsaw, it is very important to keep students 'spiels' from dragging on too long. Consider using a timer with a loud 'ding.'
- If students do not have time to go through the example questions, consider running through a few of them as a class.
- Expect to use roughly 1.5-2 hours for Unit 1 to work well, provided that students are prepared for the discussion. It was useful to spread Unit 1 over two consecutive class meetings (not entire class meetings, necessarily) to give students repeated exposure to the content.
Example #1: Students complete discussion questions (see teaching materials section) in small groups, then report-out their responses. Alternatively, the discussion questions could be posted on large pieces of paper around the room and the questions answered as a gallery walk with report-outs for each question.
Example #2: The Unit 1.2: How do we measure the hydrosphere? - student group exercise (Microsoft Word 2007 (.docx) 529kB Feb14 20) has a multiple-choice question for each of the 6 measurement techniques in which students look at a representative time-series and decide whether they are looking at stream gaging, groundwater well, GRACE, vertical GPS, reflection GPS, or SNOTEL data. Instructors could choose to have students answer these questions as a conceptest with clickers, different colors of index cards, or IF-AT scratch-off cards.
The student exercises are the main summative assessment for Unit 1, particularly the last question in Unit 1.2. An answer key is provided for assessment of the Unit 1.2 student group exercise:
If additional summative assessment questions are desired, they are provided in this document:
Note that we define level-1, level-2, and level-3 assessments throughout the module based on Bloom's Taxonomy levels and examples of skills/tasks/actions involved in answering the question. Guide to GETSI Assessment Levels 1, 2, and 3 (Microsoft Word 2007 (.docx) 304kB Jun11 17)
References and Resources
- InTeGrate module, An Ecosystem Services Approach to Water Resources
- UCAR Center for Science Education Water Cycle page
- USGS Water Cycle School
- USGS Water Use in the United States
- USGS Estimated Use of Water in the United States in 2010
- Bellingham, WA Residential Water Consumption Calculator
- Penn State Extension Service: Water System Planning, Estimating Water Needs
- GRACE Follow-On mission page from NASA - includes a variety of visual resources, including diagrams, datasets, and animations
- GRACE FollowOn: Tracking Water from Space (NASA video)
- Additional GRACE preparation questions from GETSI Ice Mass and Sea Level Change module
- NASA Earth Observatory article, The Gravity of Water
- UNAVCO GPS Spotlight GNSS videos