Determine Discharge of Stream
• Ruler or meter stick
• Tape measure
• Watch with second hand or stopwatch
The stream discharge defines the amount of water that passes a point in a given amount of time. Discharge, expressed as cubic feet/second is calculated as:
||140 cu ft/sec
One person (A) stands by the stream and does not move if
the stream is large and all other measurements have been made
you may need to stand in the stream. You are the dropper of
1. Carefully measure the depth of the channel with a ruler
or meter stick. One measurement should be enough as
the stream is small. Be careful not to disturb any sediments
on the bottom of the stream.
2. Carefully measure the width of the channel with a ruler
or meter stick.
3. Calculate the velocity:
A second person (B) measures a 10 foot to 100 foot length
along the stream and marks the point. If the stream is small,
stand on the bank by this point. If the stream is large, stand
in the stream at this point. You are the catcher of the orange.
A third person (C) is the timer of the orange.
Person A (the dropper) drops the orange in the water and
shouts f1start' or 'drop' or some other appropriate remark
so Person C (the timer) can start the timing.
When the orange reaches person B (the catcher) catch the
orange and shout 'stop' so the timer can stop timing. If the
orange does not reach you directly shout stop when it passes
Record the time it took for the orange to travel the distance
and covert to feet per second for velocity. It is recommended
to do this several times and take an average.
Printed with permission from
Michal L. Le Vasseur,
Determine Discharge of Stream (Adobe PDF document)