Happy Science Friday! Today we will be learning about stream velocity - the speed in which the river flows over a period of time. This variable is crucial in understanding the biological makeup of the river, as some organisms need fast flows and others need stiller pools.
The velocity of the stream is directly related to how much water is flowing through, which is why monitoring this variable is important, as it’s always changing! As snow melts during the spring, more water is flowing to our streams creating a faster velocity. The end of summer and fall marks much lower streams and slower velocities.
Other than the biological makeup of the stream, velocity also determines the amount of sediment that is carried by the stream. Faster streams will cause sediment to be suspended in the water column and thus carried further, whereas slower streams will allow sediment to settle to the bottom.
Fig. 1 Bends and turns in the stream’s channel provide variation in flow, thus variation in habitability.
The speed of water also relates to last week’s Science Friday topic, dissolved oxygen (DO)! With a faster stream, more ambient oxygen will be aerated into the water causing an increase in DO levels.
Stream Teams with WEN test velocity of Rattlesnake Creek every Sunday! We do this by marking a beginning and end of the section we are monitoring, and timing how fast it takes for a tennis ball - mimicking a molecule of water - to reach the other end, as seen below:
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