Stream gauging

Stream gauging means measuring how much water flows past a point in a river or canal. The usual method is the velocity-area method: the channel is divided into vertical sections, a current meter measures the water velocity in each, and velocity times area gives the discharge. Lakshmi Engineering Works makes the instruments for every part of that work.

The current meter

• Cup type current meter: a rotor of cups, made to IS 3910, for velocities from 0.3 to 3.5 m/s (up to 6 m/s on request). A robust choice for routine gauging.
• Propeller current meter: a propeller on a horizontal axis, for 0.04 to 6 m/s in rivers, canals and the sea.
• Pygmy current meter: a small cup meter for shallow water and low velocities, used on a wading rod.

Reading the meter

A water velocity indicator counts the meter revolutions and, with the meter calibration, gives the velocity on site. It can store readings from several meters and pass them to a computer for the discharge calculation.

Getting the meter into the water

In shallow water the meter is held on a wading rod. From a bridge, a bridge outfit (a wheeled crane with a gauging reel) lowers the meter and its sinker weight. Where there is no bridge, a cableway across the river carries the meter from the bank, and a sounding reel with a depth counter positions it at the right depth.

Tell us the width, depth and highest velocity of your channel, and whether you gauge by wading, from a bridge or from the bank. We will put together the right set.