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Stage Discharge Curve :
Discharge of a river/stream varies at different seasons and at different locations
of the same river. Discharges are calculated at a particular point, the control
point, by area velocity method for different seasons. A gauge is installed at the
centre point or near the bank for medium or large rivers and is calibrated with
reference to mean sea level. A graph is then prepared with discharge as
abscissa and corresponding gauge reading as ordinate. This graph is known as
rated graph with known discharge and gauge reading. Subsequently, only by
reading the gauge, discharge can be determined from the graph. For
preparation of rated curve statistical data need to be collected. Fig. 3.4 shows a
stage discharge curve.
Discharge in cumecs
Fig. 3.4 : Stage Discharge Curve
(After Punmia et al, 1992)
Measurement of discharge from Tubewells :
Discharge from the tubewell is measured by (a) Orifice Method and
(b) by V-notch Method.
Orifice Method :
Fig. 3.5 : Orifice Weir Method
(After Karanth, 2004)
