Discovering Fluvial Geomorphology and Stream Processes
using a Simple Flume Experiment

The goal of this laboratory is to deepen our understanding of fluvial geomorphology by modeling stream processes in a flume. A flume is an artificial channel used to conduct water and sediment.

The stream processes we will focus on include:

Schematic of Flume

Pre-lab Questions

1. Why are streams and rivers important to geology? To humans?

Experiment 1
In this experiment you will hold discharge constant and change the stream gradient. You should record observations of any changes in channel morphology (shape) or sediment transport/deposition throughout the experiment.

1. Once the instructor has inspected your apparatus set-up you can slowly turn on the stream flow.
2. Measure the stream discharge in mL per minute.
3. Once a channel is established you can begin uplifting the stream 3 cm at 15 minute intervals.
4. Prior to each interval of uplift you should measure the streams sinuosity. Sinuosity = Channel Length / Straight Line Length.
5. Use a protractor or a ruler and trigonometry to determine the stream gradient (the slope in degrees of the channel).
6. Do at least 4 intervals of uplift, repeating steps 3 – 5 for each interval.

Schematic of Sinuosity Measurements

Both dashed lines are lines that require measure. The smaller dashed line is straight line length and the bolder dashed line is the channel length.
 

Experiment 2
In this experiment you will hold stream gradient constant and vary discharge. You should record observations of any changes in channel morphology (shape) or sediment transport/deposition throughout the experiment. In particular, your experiment is different from Experiment 1 because you will be using mixed grain-size sediment (poorly sorted, well graded).

1. Use the string provided to layout a square grid over your experiment. Choose several grid cells and outline them using the marker provided. Outline the cells with a permanent marker and write a number (1–10) next to each.
   (Hint: Calculate basin dimensions and grid cell size prior to making grid.)
2. Once the instructor has inspected your apparatus set-up, you can slowly turn on the stream flow.
3. Measure the stream discharge in mL per second.
4. Measure the grain-size distribution of 1 grain in each of the 10 selected cells. (Be sure to always measure grain sizes in these same cells for each “increment.”)
5. Increase the discharge one “increment.”
6. Measure the stream discharge in mL per second.
7. Measure the grain-size distribution of 1 grain in each of the 10 selected cells.
8. Repeat steps 5 – 7 for a total of 5 “increments” of increased discharge.

Schematic of Grid over Flume

White cells are a good example of where to consider selecting cells for measuring grains.

Tables for Recording Data

Data Table for Experiment 1

Data Table for Experiment 2

Record of Observations
(This is not notes; this is for a grade, write sentences summarizing observations made throughout the experiment)
                                                                                                                                           
                                                                                                                                           
                                           

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List of materials

Vernier
Ruler
Tweezers
Flume basin
Fine-grain sediment
Mixed-grain size sediment
3 buckets
3 masonry basins
Silicone tubing
Puddy (sealant)
Calculator with trig functions
Permanent marker

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Contact me if you used this lab or have suggestions: sasrj "at" sfsu.edu

Copyright 2007 Robert J. Sas, Jr.
Can be used without permission for educational purposes and not for profit.