Estimating stream discharge at various stages of flow

The diagram below illustrates the cross-section of a stream. The diagram is interactive in that depth can be determined using a "wading" rod, and velocity estimated from the propeller device (a velocity sensor).

Remember that stream discharge is the product of its cross-sectional area and velocity. The actual determination of a stream's discharge can be very involved. For example just estimating the cross-sectional area is not easy. (It's not a simple rectangle.) Also, because of friction with the sides and bottom of the channel, the stream's velocity varies from one side to side and from top to bottom. (It's greatest near the surface over its deepest part.)

For each state (high, low and flood) mouse drag the green vertical line to estimate and record the stream's width. Click the "Done measuring width" button and use the wading rod and its velocity sensor along with the calculator to complete the table below.