That's right! Hydrologist use the six-tenths rule to estimate stream velocity at a particular spot. The average velocity at that spot can be determined by measuring the velocity at six-tenths of the depth of the stream. If the stream is 3.2 meters deep, the average velocity at that spot can be estimated by measuring the velocity at 3.2 m times 0.6, which equals 1.92 m.

Next we are going to estimate the discharge of a simple stream where the velocity changes with depth. Below is a cross section of a stream with a "wading rod" tool, which you can move back and forth. Attached to the rod is a velocity sensor (a propellor device), which you can move up and down. The velocity and depth sensor readings can be seen below to the left.

1. What is the maximum depth of water in this hypothetical stream?	meters
2. At what depth should the velocity meter be set so to record the average velocity? ( Remember that in the last exercise the average velocity was at 6/10^th's of the total depth.)	m
3. What is the average velocity of this stream, as measured by the virtual stadia rod and velocity meter?	m/sec
4. What is the distance on the tape of the left edge of water?	m
5. What is the distance on the tape of the right edge of water?	m
6. Compute the width of the stream.	m
7. Discharge is computed as the volume of water in the stream passing by in a second. DISCHARGE = depth times width times velocity. What is the discharge of this stream? (in cubic meters per second)	cms