Module 3: Rivers and Watersheds
In this module, we investigate the processes by which precipitation accumulates in, moves through, and is transported out of a landscape. We especially focus on flow of water in streams and rivers, including how these important features form and change over time.
The goal of Module 3, Rivers and Watersheds, is for students to learn the basic characteristics and processes of rivers and watersheds and to develop skills analyzing and interpreting data. After completing the module, students will be able to:
- identify and describe the processes by which precipitation accumulates, moves through, and is transported out of a watershed;
- describe the physical differences between terrestrial and stream systems;
- quantitatively describe streamflow, including metrics for characterizing magnitude, duration, and variability of streamflow;
- evaluate stream gauge data to compare variability of streamflow in different locations;
- visually identify various common channel morphologies in Google Earth;
- describe physical characteristics of a river channel, including stream order, number of channels, and sinuosity;
- analyze how topography influences water movement over land.
Context for Use
Overall, this one-week module is intended for use as a standalone lesson or as part of an online or blended general education or introductory-level course that would satisfy a science distribution requirement. The module would be appropriate for non-majors and undeclared students looking for a major. There are two formats: (1) blended where the students meet at least once to perform the activities in teams; and (2) 100% online. As a general guideline, the delivery of content and assessment of learning goals/objectives have been designed to accommodate the logistics of large class sizes where students are expected to work approximately three hours per week covering lecture content with an additional six hours per week of additional reading and work on assessments. Note that some students will require more or less time to meet the goals and objectives of the module.
Description and Teaching Materials
In this module, students will:
- interact with online teaching materials pertaining to rivers and watersheds;
- observe and describe the watershed they live in using Google Earth;
- interpret USGS river gauge data available online;
- find examples of river channel systems using Google Earth;
- use a topographic map to create a cross section and predict surface water flow patterns.
All materials for students are available online using the Student Materials link below. These can be implemented entirely in the context of distance learning, with students completing any discussion questions in the form of a blog or discussion group. In a traditional or blended classroom setting, students can complete the online unit as homework, using class time to address the discussion questions and/or complete the Summative Assessment.
Teachers can find documentation of the activities as well as rubrics for students at this location. Rubrics for teachers are compiled under Assessment on this site. Suggestions for teaching and a list of the assessments are found below.
Teaching Notes and Tips
What works best for the module?
Much of this module covers conceptual content that students find relatively easy to relate to. It helps to obtain data for a local stream that students might already be familiar with to discuss in class. Students exhibited a wide range of abilities with the Summative Assessment (topo map assignment). Even students with some GIS experience found this manual mapping exercise to be useful. A brief tutorial on how to read the map and use topo lines helped get everyone on the same page.
What students found difficult
Some students had trouble with the first Google Earth exercise (Formative Assessment 1), but most found it very valuable, so even if you use it to get students "flying" around looking at watersheds, it can be a worthwhile exercise. For students who are struggling, make sure they review the tutorials and consider providing a brief in-class (or after-class) tutorial:
- Getting started resources from the Google Earth Help Center website.
- The Science Education Resource Center (SERC) hosts an extensive tutorial document that is extremely useful. Google Earth User Guide from the Pedagogy in Action project.
For Formative Assessment 2, students may need some help finding data on the USGS website.
The Summative Assessment takes 45–60 minutes to complete in class. For the Summative Assessment, most students needed help deciding how to sample the topo map to create the cross section. This is an interesting opportunity to discuss matters of data collection/resolution and surveying. Optimally, students would draw elevation/distance points on the cross section that correspond to each change in gradient. This results in the most accurate topo map. An easier but less accurate method would be to extract points at given intervals. One point per 1000 linear feet yields a relatively poor cross section; one point per 500 linear feet is better.
Some students also had difficulty determining how to calculate "slope" or "gradient." The Math You Need page on this topic: How do I calculate slope/gradient?, could be suggested, or the instructor could lead a short discussion.
It is important that the students are exposed to the section on flow, hydrographs, and flow duration curves in this module before proceeding to Module 4, which goes into greater detail about how different hydrologic processes and watershed modifications influence the hydrograph.
- Formative Assessment 1: Watershed
- Formative Assessment 2: River Flow
- Formative Assessment 3: Channel Systems
- The Summative assessment for this module is Topographic Maps and Surface Water.
References and Resources
- Readings from Student Materials - Module 3: Rivers and Watersheds
- The Big Thirst: The Secret Life and Turbulent Future of Water by Charles Fishman: Chapters 6 and 7
- Getting started resources from the Google Earth Help Center website
- The Science Education Resource Center (SERC) hosts an extensive tutorial document that is extremely useful: Google Earth User Guide from the Pedagogy in Action project
- How do I calculate slope/gradient? - a tutorial from Math you Need