Stream Gauging Methods

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Stream gauging is the technique to measure a river discharge. Stream gauging can be divided into several methods; Pitot Tube method, Float Gauging method, Volumetric method, Velocity-Area method and Slope-Area method (Deakin, 2004). In this chapter, all the methods will be explained in details.

Pitot Tube Method

Pitot tube method is named after a French Hydraulic engineer, Henri Pitot as he invented the Pitot tube which is consists of a bent glass tube. Pitot used this method in the River Seine to measure the velocities of stream flow (illustrated in Figure 1.0). Figure 2.0: Pitot Tube

The figure above shows that one end of the tube is immersed in the stream at depth H and the water rises up the tube until all its kinetic energy is converted into potential energy; a height h above the surface of the stream. As Bernoulli's law stated that

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This is the simplest method in measuring the stream velocity. The surface velocity at any section may be measured by a single surface float but velocity may be affected by wind and air resistance (Lewitt, Stream Discharge Measurement, 1961).

Figure 2.1: The float method for velocity determination
In the figure above, the cross section of the stream is divided into three channels. Then, a starting and finishing line is set at a certain distance; this is to specify the area and the time taken for the object to float. The object is then placed at the surface of the river, and let it float at particular cross section. The product of the time taken and the area of the cross section will result in the velocity of the stream

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