Intro to Quantifying Stream Discharge and Base Flow

Calla Schmidt, University of San Francisco

Sarah R. Hall, College of the Atlantic

Becca Walker, Mt. San Antonio


In this exercise, students calculate stream discharge from sample field data using the velocity-area method. They compare multiple measurements of discharge to determine base flow in a sample river reach.

Used this activity? Share your experiences and modifications

Learning Goals

Content/Concept Goals:

Students will...

  • Learn the velocity-area method for determining stream discharge.
  • Determine groundwater base flow and tributary inputs along a river.

Other Skills Goals for this Activity:

Students will...

  • Build an Excel table with formulas for computing total discharge that they can use with future field data.

Context for Use


This activity was completed during the 2-week summer E-STEM Field Course with ~20 undergraduate students interested in environmental science.

Prerequisite Skills and Concepts:

This activity assumes no prior knowledge about stream hydrology.

How the Activity is Situated in the Course:

This is an introductory activity which students complete before collecting any field data. View the E-STEM field course timeline for more information about how this activity is situated in the course.

Description and Teaching Materials

Student Handout

into_discharge_base_flow_handout.docx (Microsoft Word 2007 (.docx) 1.6MB Sep11 20)

Teaching Notes and Tips

I had pairs of students calculate discharge in 3 flow cells manually and check their work with another group that made calculations in the same flow cells. The class then shared data to arrive at a total discharge number for the stream. Students then worked to build an Excel table that could calculate total discharge from any field dataset using the manual calculations to validate their model.

Note: Students find it confusing that the edge flow cells are calculated using a different formula. I suggest teaching the formulas for the non-edge flow cells first, returning to a conversation about the edges after students have made a few calculations.


Assess the data table and cross-section figure with rubric for the Hydrology Badge.

References and Resources

Original exercise written by James Reichard, Georgia Southern University, modified by Calla Schmidt, University of San Francisco.