17 WorkflowLooprunner

What is the WorkflowLooprunner?

To decrease the run time length the SOBEK model for the Rhine basin is only run for periods where the discharge at Lobith exceeds a given threshold. Respectively the SOBEK model for the Meuse basin is only run for periods where the discharge at Borgharen exceeds a given threshold. To achieve this a so called WorkflowLooprunner was configured in FEWS. There are two options to select the periods for which the SOBEK model shall be run. The first option is to define a threshold for a given time series. If this threshold is exceeded the SOBEK model will be run. The second option is to define the length of a time interval, e. g. yearly. In each time interval SOBEK is run for a defined time window around the maximum value.

These options can be configured in the WorkflowLoopRunner "GRADE_SBKdag_Rijn_SelectedPeaks_Update.xml" for the Rhine basin and in the file "GRADE_SBKdag_Maas_SelectedPeaks_Update.xml" for the Meuse basin. Currently the WorkflowLoopRunners are configured such that the SOBEK model is run within a period of ten days before and two days after the maximum value of the discharge in Lobith respectively Borgharen in a time interval of 40 years.

In the next two sections how to configure the different options in FEWS is explained.

Run SOBEK around the maximum value of a given period

In the Workflow LoopRunner the following things have to be defined:

• trigger option
• trigger time series
• relative view period
• step value option
• step size
• relative run window

First, choose the trigger option "Step Value Trigger" to run SOBEK for a period around a maximum in a pre-defined time interval. Then define the trigger time series to which the maximum is referred to and the relative view period for which the WorkflowLoopRunner shall be run. After that define the step value option, you can choose between maximum and minimum. The step size defines the time interval within the relative view period. For each time interval the maximum/minimum value of the trigger time series will be defined.
The relative run window defines the period over which the SOBEK model is run around the maximum/minimum discharge value.

As an example see the schema of the WorkflowLoopRunner configuration file in Figure 1. This example shows how to run SOBEK for a period around one maximum value in 40 years time.

Figure 1 WorkflowLoopRunner with trigger option "step value trigger"

In the example file the trigger time series is Q.uh, the discharge at Lobith calculated from HBV. The step value option is the maximum value of the time series. According to the relative run window the SOBEK model is run from ten days before the maximum value until two days after the maximum value.

In Figure 2 you can see how the relative run window is defined. On the left hand side of the figure the step size (time interval) is a third of the relative view period. For each time interval the maximum value is defined. Around that maximum the relative run window for SOBEK is defined. If the relative run windows from different time intervals overlap, SOBEK is run for the merged relative run window. On the right hand side of the figure the step size equals the relative view period, thus resulting in one relative run window.

Figure 2: Definition of the relative run window for the trigger option "step value trigger" for step size unlike relative view period (left) and step size equal to relative view period (right)

It is recommended to choose the time step size in such a way that the relative view period is a multiple of the time step size. If this is not the case, the last part of the relative view period is not taken into account, e.g. if the relative view period contains ten days and the time step size is three than the last day of the relative view period will be ignored in the WorkflowLoopRunner. Furthermore, choose an adequate time period before the maximum value, so that the model can simulate the peak sufficiently. Also keep in mind that the run time increases if the relative run window increases. Besides, one single SOBEK run must not be longer than 30 days, due to an internal setting in the SOBEK model.

Run SOBEK where the discharge exceeds a pre-defined threshold

In the Workflow LoopRunner the following things have to be defined:

• trigger option
• trigger time series
• relative view period
• value option
• value
• relative run window

Choose the trigger option "Value Trigger" to run SOBEK for a period where the trigger time series exceeds a given threshold. Then define the trigger time series and the relative view period for which the WorkflowLoopRunner shall be run. With the value option you can configure in which direction the trigger is activated. You can choose between "below" and "above" a given threshold. Define the threshold value in the field "value".

The relative run window defines the period over which the SOBEK model is run. The period contains the whole period where the trigger time series exceeds the defined threshold and optional a period before and after that time. The additional time you can define with the start and end time of the relative view period. The start time is relative to the time where the threshold is exceeded. The end time is relative to the time where the trigger time series goes back to threshold value again. In Figure 4 you can see how the relative run window is defined. The green line demonstrates the part of the relative run window where the threshold is exceeded. the red parts of the relative run window represent the additional time which can be optionally added to increase the relative run window. If the relative run windows of two different peaks overlap, SOBEK is run for the merged relative run window.

_Figure 3 Definition of the relative run window for the trigger option "value trigger"_

When you define the threshold value you should take into account that the relative run window must not get too long. Otherwise the workflow might fail, because of a time out error. Nevertheless SOBEK has to run for an adequate time to simulate the peaks sufficiently. Also keep in mind that the run time increases if the relative run window increases. Besides, one single SOBEK run must not be longer than 30 days, due to an internal setting in the SOBEK model.

As an example for configuring the WorkflowLoopRunner see Figure 4.

_Figure 4 : WorkflowLoopRunner with trigger option "value trigger"_

In the example file the trigger time series is Q.uh, the discharge at Lobith calculated from HBV. The relative view period is 14610 days (40 years). For each time interval the maximum value of the trigger time series will be defined. As value option "above" was chosen. The threshold value is 4000. The relative run window includes the period where the discharge at Lobith exceeds the threshold value as well as to days before and after that period.

Run Model for entire view period if pre-defined threshold is exceeded

Next to running the model for a relative run window with respect to
threshold values found in the relative view period of the indicated
timeSeriesSet, an option exsists run the model for the entire view period in
this event.
This implies that the relative run window is similar to the total relative
view period, independant of the instance at which the threshold value is
exceeded. This is illustrated in Figure 5.

Figure 5: Definition of the run window for the runPeriodOption alwaysFullPeriod="true".

This feature is enabled by setting the alwaysFullPeriod flag to true at
runPeriodOptions. This is illustrated in Figure 6.

_Figure 6: Run model for entire view period by selecting
alwaysFullPeriod="true"._