Quantitative Skills > Teaching Resources > Activities > Discharge and Sediment Transport in the Field

Discharge and Sediment Transport in the Field

Jeff Clark, Lawrence University
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This activity has benefited from input from a review and suggestion process as a part of an activity development workshop.

This activity has benefited from input from faculty educators beyond the author through a review and suggestion process as a part of an activity development workshop. Workshop participants were provided with a set of criteria against which they evaluated each others' activities. To learn more about this review process, see http://serc.carleton.edu/quantskills/review_processes.html#2005.


This page first made public: Oct 23, 2009

Summary

In this quantitative field activity, students collect field data on channel geometry, flow velocity, and bed materials. Using these data, they apply flow resistance equations (Manning and the depth slope product) and sediment transport relations (Shields curve) to estimate the bankfull discharge and to determine if the flow is sufficient to mobilize the bed. This activity requires students to utilize theoretical and empirical equations derived in class in the context of a field problem.One should allow for 2 hours in the field and assume an additional 2-4 hours of student work outside of class

Learning Goals

Discharge is a fundamental quantity in geomorphology. Not only is it important in determining when sediment will move, and therefore when erosion and deposition will occur, but on a broader scale it (along with sediment supply) governs the size, shape, planform geometry, and longitudinal profile of alluvial rivers and ultimately shapes entire landscapes. In a more practical sense discharge data is essential in flood frequency analysis which in turn is used for insurance purposes (e.g. FEMA's delineation of flood prone areas) and engineering considerations such as bridge, culvert and reservoir sizing.

Context for Use

This field activity is done about half way through a comprehensive unit on rivers in an upper level (300) geology class—Physics of the Earth: Surficial Processes. Prior to taking this class students will have taken introductory geology and should have taken one term of physics and applied calculus, although no calculus is required for this particular activity.

Prior to this exercise:

  1. Resistance equations (Chezy and Manning) and sediment transport relations will have been derived.
  2. Students will have had the opportunity to work through rudimentary examples of these equations.
  3. Students will be familiar with surveying.

Description and Teaching Materials

Teaching Notes and Tips

Assessment

References and Resources

Barnes, H.H., 1967, Roughness characteristics of natural channels: USGS Water-Supply Paper 1849, 213 p.

Ritter, D.F., Kochel, R.C., and Miller, J.R., 2002, Process Geomorphology (4th ed.): WCB/McGraw-Hill, 560 p.

Wolman, M.G., 1954, A method of sampling coarse river-bed material: Transactions, American Geophysical Union, v. 35, n. 6, p. 951-956.

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