# Effective Discharge in Fluvial Geomorphology

#### Summary

Use statistically and empirically based solution techniques to calculate the effective discharge of a stream. Students are given a 10-year record of river data on water and bedload discharge, flow frequency, and maximum daily discharge for each year. They must use the data to construct a rating curve for bedload transport, determine total volume of sediment transported by each flow-magnitude class, and discuss the recurrence interval of the effective discharge. Real and fictional data can be used.

## Learning Goals

- Encourage a realistic view of the importance of various flow regimes in sediment transport.
- Introduce students to the concept of effective flow.

## Context for Use

This activity is appropriate for upper-level undergraduate geoscience students and can be adapted for graduate students.

## Teaching Notes and Tips

To adapt this exercise to a graduate level class:

- Compute a cumulative probability curve for streamflow instead of using flow classes.
- Generate a theoretical lognormal probability-density function for daily streamflow.
- Develop and compare separate equations for suspended load and bedload.
- Develop separate transport equations for the rising versus falling limb on a flood hydrograph.
- Develop unique sediment transport relationships for different climate scenarios.

## References and Resources

Activity from:

- Orndorff, R.L., and Stamm, J.F., 1997, A Laboratory Exercise Introducing the Concept of Effective Discharge in Fluvial Geomorphology, Journal of Geoscience Education, v. 45, p.326

Stream data can be obtained from several sources including the following:

- Publications:
- Kircher, J.E., 1981, Sediment transport and effective discharge of the North Platte, South Platte, and Platte Rivers in Nebraska: U.S. Geological Survey Open File Report 81-53, 26 p.
- Meade, R.H., Yuzyk, T.R., and Day, T.J., 1990, Movement and storage of sediment in rivers of the United States and Canada, in Wolman, M.G., and Riggs, H.C., editors, Surface Water Hydrology, v. 0-1, The Geology of North America: Boulder, Colorado, Geological Society of America, p. 255-280.
- Leopold, L.B., 1994, A view of the river: Cambridge, Massachusetts, Harvard University Press, 298 p.
- Andrews, E.D., and Nankervis, J.M., 1995, Effective discharge and the design of channel maintenance flows for gravel-bed rivers, in Costa, J.E., Miller, A.J., Potter, K.W., and Wilcock, P.R., editors, Natural and anthropogenic influences in fluvial geomorphology: Washington, DC, American Geophysical Union, p. 45-56
- Schmidt, J.C., and Rubin, D.M., 1995, Regulated stream-flow, fiine-grained deposits, and effective discharge in canyons with abundant debris fans, in costa, J.E., Miller, A.J., Potter, K.W., and Wilcock, P.R., editors, Natural and anthropogenic influences in fluvial geomorphology: Washington, DC, American Geophysical Union, p. 177-195.
- Leopold, L.B., Wolman, M.G., and Miller, J.P., 1964, Fluvial processes ingeomorphology: San Francisco, California, W.H. Freeman and Company, 522 p. and others, 1964

- Other:
- USGS Real-Time Data for the Nation: Daily Streamflow Conditions (more info) - The USGS makes data available for free on this website.
- EarthInfo sells environmental databases on CDs for a fee.

## Contact the Author

## Controlled Vocabulary Terms

**Subject**: Geoscience:Hydrology:Ground Water, Ground Water:Water supply/water resource evaluation

**Special Interest**: Quantitative

**Quantitative Skills**: Logarithms/Exponential Functions, Problem Solving, Geometry and Trigonometry, Probability and Statistics:Probability, Data Trends:Curve Fitting/Regression

**Theme**: Teach the Earth:Course Topics:Hydrology/Hydrogeology, Teach the Earth:Teaching Topics:Water

**Quantitative Skills Activity Type**: Problem Set, Classroom Activity, Lab Activity

**Topics**: Hydrosphere/Cryosphere:Groundwater, Groundwater:Water supply/water resource evaluation