Vertical axis current meter with cable suspension.
This set-up, consisting of a current meter and a sounding weight, is used to measure stream discharge from bridges, boats, and cable cars. (See photo of cable car below.) The stream current causes the cups to rotate. The sounding weight helps to keep the current meter level. Stream discharge measurements are taken from bridges, cable cars, or boats when the river is too deep or fast moving for a person to safely stand in the stream. Wading discharge measurements do not require the sounding weight. Instead, the current meter is attached to a wading rod.
For every revolution of the cups, a "click" is transmitted from the current meter to headphones worn by the field technician. The field technician counts the number of "clicks" per unit time to determine the velocity of the water (usually in feet per second). Mulitplying the velocity of the water by the cross-sectional area (in square feet) of the stream results in the discharge of the stream (usually in cubic feet per second).
Sitdown cable car with current meter and sounding weight attatched to reel.
Wading discharge measurement.
