Page History

...

Where:
Qm = backwater affected discahrgedischarge
Qr = reference discharge
Fm = measured fall
Fr = reference fall
p = power, with 0.4 < p < 0.6

...

In this method the reference fall Fr is taken as a constant. A special case of the constant-fall method is the unit-fall method, where Fr = 1m is applied. In the computational procedure a value for Fr is assumed. Then a rating curve is fitted to the values:

normal fall method

...

In this method the reference fall (Fr) is modelled as a funtion of the water level; Fr = f(h). This funtion is represented by a parabola:

Image Added

In Fews you should specify the a, b and c parameters and also a value of hmin, below which the backwater correction is not valid.

Rating Curve Table

ratingCurveTable this allows you to simply enter the pairs of q and h values.

  </ratingCurve>
  <ratingCurve ratingCurveId="TheBigRiver">
    <location>
      <locationId>X1123</locationId>
    </location>
    <ratingCurveType>LevelToFlow</ratingCurveType>
    <reversible>true</reversible>
    <ratingCurveTable>
      <ratingCurveTableRecord flow="0.100" level="0.054"/>
      <ratingCurveTableRecord flow="0.500" level="0.155"/>
      <ratingCurveTableRecord flow="1.000" level="0.244"/>
      <ratingCurveTableRecord flow="1.479" level="0.317"/>
    </ratingCurveTable>
  </ratingCurve>

Rating Curve Equation

...

008