Measuring Rate of Flow

Teacher/procedure page - Global Lab

Rate of flow is a measurement of the speed of moving water, usually a stream, river, or estuary during tide change. (This measurement may not be appropriate for still or slowly moving water, such as a pond or lake.)

Why We Care

Two examples: Water managers want to be able to tell how much water is being diverted for irrigation and other purposes. Toxicologists want to be able to estimate when a toxic plume will reach local well.

Materials

ball or another floating object apple, pinecone, etc.
stopwatch or watch with a second hand
GL Journals

Procedure

This activity can be practiced in the classroom, before going into the field, by measuring a distance of 10 meters and timing how long it takes for a ball to roll the entire length. Repeat this several times and average your results.

1 Measure a distance of 10 meters along the bank of stream, river, or other flowing water.
2 Drop a floating object into the water, above the start the 10-meter mark. This object can be an orange, apple, tennis ball, pinecone, or basically anything that can float and is visible. Start timing when the floating object reaches the beginning of the 10 meters.
3 Measure the amount of time it takes for the floating object to travel the 10 meters.

Repeat this measurement several times and average your results. Divide your average by 10 and you will have the rate of flow for the water in meters per second (m/s).
 

Recording results:

Time ______ (minutes: seconds) to cover 10 meters
Divided by 10 = Rate of flow ______ per second (m/s)

(Other methods)

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