AdjustQUsingInstantaneousDischarge
Input
- observedDischarge
- simulatedInstantaneousDischarge
Coefficient set
- blending steps
- interpolations type
Output
- adjustedForecastDischarge
Description
This procedure uses an observed instantaneous discharge to correct a simulated discharge. If there is an observed value for a certain time step then that value will be used instead of the simulated value. If there is no observed data is available the correction procedure will calculate a value or in some cased use the simulated value.
The configuration has two configuration options which will influence the behaviour of the correction procedure. The first one is blending steps. If there is a gap in the observed data which is
x time steps large and x < blending steps then the output values for the gap will be determined using an interpolation procedure. If x >= blending steps then a blend procecure will be used to
fill the gap.
correctNegativeFlowValuesToZero is an optional field in the configuration. Default value is true. If it is set to true, any negative delta values will be adjusted to zero.
Interpolation procedure
The second configuration option which influence the behaviour of the correction procedure is the interpolation type. Two options are available:ratio and difference. To calculate the value of the adjusted time series a correction procedure is used for the simulated discharge. When the ratio-option is selected the the simulated values will be corrected by multiplying the simulated value with a correction factor based on the ratio's between the observed and simulated discharge at the start of the gap and at the end of the gap. The correction factor will be linearly interpolated between the ratio at the beginning of the gap and the ration at the end of the gap. When the difference option is selected the simulated value will corrected by adding a correction value to it. This value will be based on the difference between the observed and simulated discharge at the beginning of the gap and the difference between the simulated and observed value at the end of the gap. In some cases it is possible that the program overrules the configured interpolation option. When the ratio between the ratio's is larger than 2 or one of the ratio's is larger than 5 than the program will switch to interpolating by difference even if ratio's was configured.
Blend procedure
When the gap in the observed data is to large to fill with a interpolation procedure then the gap in the observed data will be filled with the blend procedure. This procedure is also used to provide a smooth transition between the observed data and the simulated at T0. The blend procedure will provide a smooth transition between the observed data and the simulated data. The difference between the simulated discharge and the observed discharge at the beginning of a gap, end of a gap or at the latest observed value will be used to correct the simulated value. The following formula will be used to correct the simulated value.
Qadjusted = Qsim + (1 - i/N)*Difference
i=number time steps between observed value and simulated value
N=blending steps
Difference=observed value - simulated value (at the last observed value)
config example:
<transformation id="ADJUST_Q">
<adjust>
<adjustQUsingObservedInstantaneousDischarge>
<correctNegativeFlowValuesToZero>false</correctNegativeFlowValuesToZero>
<observedDischarge>
<variableId>observed</variableId>
</observedDischarge>
<simulatedInstantaneousDischarge>
<variableId>simulated</variableId>
</simulatedInstantaneousDischarge>
<coefficientSetFunctions>
<blendingSteps>@BLENDINGSTEPS@</blendingSteps>
<interpolationType>@INTERPOLATIONTYPE@</interpolationType>
</coefficientSetFunctions>
<adjustedForecastDischarge>
<variableId>forecast</variableId>
</adjustedForecastDischarge>
</adjustQUsingObservedInstantaneousDischarge>
</adjust>
</transformation>
