Exercise to Calculate River Discharge

Nicholas A. Baer, Department of Natural Sciences, Colby-Sawyer College, New London, NH 03257
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This material was originally developed by Spreadsheets Across the Curriculum as part of its collaboration with the SERC Pedagogic Service.

Summary

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In this Spreadsheet Across the Curriculum Activity, students will learn to calculate river discharge from given field data in Excel. Students will be given the background information to understand how to calculate discharge in the equation form (Q=V x A) and then learn how to enter the equations needed to calculate river discharge in Excel. Students are taught about the development of a rating curve from discharge measurements and how rating curves can be used to predict discharge rates at a given stage height.

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Learning Goals

The goals of this module are to:
1. Introduce the method for calculating discharge of flowing waters. This includes having students determining how to calculate the area of a non-uniform shape such as a stream or river cross-section.
2. Expose students to data collection and management skills using a graphical diagram of a stream cross section.
3. Examine environmental and human derived influences on discharge.
4. Encourage students to utilize Excel as an aid in managing and manipulating future data needs.

Context for Use

This tutorial is intended for introductory courses in water resource, hydrology, or aquatic ecology. It allows students to explore one of the greatest physical constraints aquatic organisms are exposed to on a daily basis. The module is also intended to stimulate class discussion on environmental and human induced factors affecting these aquatic habitats and the importance of long-term monitoring.
Additionally, these exercises are designed to give students opportunities to apply their quantitative skills and expand their experience with Excel and data management concepts.

Description and Teaching Materials

The module is a PowerPoint presentation with embedded spreadsheets. The PowerPoint includes links to information about measuring river discharge. If the embedded spreadsheets are not visible, save the PowerPoint file to disk and open it from there.

The above PowerPoint files are the student version of the module. An instructor version is available by request. The instructor version includes the completed spreadsheet. Send your request to Len Vacher (vacher@usf.edu) by filling out and submitting the Instructor Module Request Form.

Teaching Notes and Tips

While this exercise uses river examples from 2 New Hampshire rivers, you should consider utilizing 2 rivers in your region to make the exercise more relevant and compelling for your students.
This exercise can be tailored to your region and an environmental contrast or human disturbance you would like to illustrate.

Assessment

I assess this module and the skills as students turn in their end of module exercises, as well as their responses to the module content questions. The skills used in this module are used by students in future laboratory exercises where students apply these concepts to their own field study of streams in the region. Additionally, key concepts in this exercise are part of future exams.

References and Resources

In this exercises data was used from the US Geological Survey (USGS) website that has data available for gaged rivers and streams throughout the United States. This data is publically available at:
Link to USGS Water Data
For further information about discharge and hydrograph data consult Fluvial Processes in Geomorphology by Luna B. Leopold, M. Gordon Wolman, and John P. Miller, or other water resource texts.