How to Measure Stream Flow Rate

DIY Stream Check Use an orange, some string and your wristwatch to measure a streams flow. How rapidly a stream flows can tell you a good deal about stream health. Sluggish or stagnant creeks can develop into collecting pools for trash and pollutants. However, streams that chronically run too quick for their banks can erode and carry sediment far downstream.
Lots of bigger streams and rivers have official monitoring gauges that measure stream flow, temperature and sediment But it is possible to collect basic hydrologic information and facts having a handful of household items. An orange, a length of stout string or rope along with a watch will enable you to calculate your stream’s flow.

1: Measure at least 50 feet along the bank of a straight section of stream. You need to pick a reach of stream that has a fairly consistent flow-no eddies or slow-moving pools or branches that could snag your orange.

2: Stretch half your string across the upper end of your section, holding it in place with rocks or tying it to streamside vegetation. Do the identical using the other half of your string in the lower end of your stream stretch. Note the width (in feet) from bank to bank on both strings and average the results.

3: Use a branch or a yardstick to figure out the typical depth of the stream. Take depth measurements each and every 1 to two feet, from the deepest portion to areas near the shore. Average the outcomes.
Now you’ll have the ability to establish the location of an average cross section of your stream. Multiply the average width (W) by the typical depth (D), or WxD=Area.

The solution will be measured in square feet. Say your typical width is 5 feet and your typical depth is three feet. Then your region is 15 square feet

4: It’s time to deploy your orange. Release the orange in the upstream string and, employing your watch, record the time, in seconds, it takes to reach the downstream string. (Bring along a fishing net to retrieve the orange.) Do this various times and combine the outcomes.

5: You can now calculate the velocity of your orange, which is distance divided by time. If your stream section is 50 feet and your orange took an typical of 100 seconds to float that distance, your velocity is 0.5 feet per second.

6: You have to adjust for the surface speed of the water, compared towards the speed closer to the bottom, so multiply your velocity by 0.85. In our case, that’s 0.five x 0.85, which is 0.43 ft/sec.

7: Now calculate stream flow by multiplying your corrected velocity (0.43 ft/ sec) by the cross-sectional area of your stream (15 square feet). The flow is 6.45 cubic feet per second.

Streams vary an excessive amount of for us to give a “correct” flow, but you are able to check your results against official monitoring USGS website data.