Determining Flow Rate in a Stream: Measuring and Calculating Water Speed, Study notes of Water Resources Planning and Management

Name_____________________________________ Date___________________

Determining Flow Rate

Based on your knowledge of how water moves through a stream, choose two small sections (called

“reaches”) of the stream equal in length (3 to 10 meters long). One of these should be a stretch

that you think will have a lower (slower) flow speed, and one should be a section you believe will

have a higher (faster) flow speed. The speed is determined by timing how long it takes for an object

to float from one point to another, along a measured stretch of stream; and then dividing the time

Materials per group:

 1 clipboard, pencil and set of student sheets

 1 small floating object

 1 stop watch

 4 tent stakes

 1 measuring tape

 Calculators or scrap paper

Procedure:

1. Divide into groups of at least 4 students per group. Assign jobs to the members of your

 Floating Object Observer

 Data Recorder

2. Mark off two lengths of stream:

 Choose the two lengths of stream: One length should include a section of slow

moving water. The other length should include a faster section of water.

 Measurers: You may choose for the sections to be any length between 3 and 10

meters long. The two reaches of stream should be of equal length.

 Installers: You will use two tent stakes to mark each length of stream. One stake

will be the starting point of the measurement and the other stake will be the

ending point that is the chosen length (3 to 10 meters) downstream on the