Introduction
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To create a default operations scenario in Source:
- First, create a manager scenario;
- Choose Tools » River Operations to open the River Operations dialog (Figure 1); and
- Click on the slider below Operations Mode to ON.
Once you have created forecast models, you can disable operations, but retain these models or overrides using the buttons under Operations Data. The first two buttons in this dialog deal with removing input data, whereas the third one deletes all output data that was created for the forecast models. To clear all operations related data (input, output as a well as overrides), click Clear ALL Operations Data.
Figure 1. River Operations
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The Unaccounted difference node and the Gauged Level unaccounted difference at the storage node forecast unaccounted difference forecast the possible error. The default value in the absence of a forecast model is zero. The Unaccounted Difference is a time series computed during the historic phase of the run, and is the difference between the modelled value at a point in the system and the actual historic value which has been played in at that point. In the forecast phase, applying the forecast unaccounted difference (a positive value represents a gain; a negative value, a loss) is an attempt to compensate for the known over or under estimation inherent in the model.
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| Note: Unaccounted difference is named so because if the model were perfect, this would always be zero (the modelled value would match the actual values). In reality, the model does not simulate everything and this typically leads to the systematic over or under estimating of flows. |
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A collection of one or more forecasting models is known as a forecast scenario. You can define one or more scenarios for each node. For example, you might define "wet year", "dry year" and "normal year" scenarios, or variations that reflect your most optimistic or pessimistic expectations. To add a forecast scenario, right-click on the item you want to forecast in the relevant node's feature editor and choose Add Forecast Scenario (Figure 4). You can choose the input set that will be associated with a particular forecast scenario. Right click on Forecast Scenario #<number>, then choose Add Forecast Model to add a model.
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| Note: Only one forecast model can be active at a point in time during the simulation. |
When more than one forecast model has been assigned to a forecast scenario, they are ordered from top to bottom in the hierarchical list. The model at the top of the list runs first. You can change the order of model run by dragging the forecast model to the required position in the list. For each model, you must also specify the number of time-steps it will be active for before moving onto the next model in the list. The last model in the list always has a Time Steps value of All Remaining and will be active for the remainder of the forecast period.
Figure 4 shows a forecasting scenario (associated with Wet Input Set) with two forecast models. Both Forecast Model #1 (which will run for the first 10 time-steps) and Model #2 (which will run for the remaining time-steps) have been configured as Expression models. To change the name of a forecasting scenario or model, right-click and choose Rename. Choose Delete to remove the scenario or model.the Forecast item for the Inflow node. Choose the forecast model you wish to specify by clicking the appropriate forecast model under Additional Flow Forecast (on the right). The forecast model that is active at the node is indicated by a green tick on the left of the model. In Figure 4, the Trend forecast model is the active model.
Figure 4. Inflow node, Operations forecasting
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| Note: Forecast scenarios are unique to a node and must be configured individually for each node. |
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Forecast model type | Description |
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| Average | Average over the last specified time-steps |
ExpressionFunction | User defined arithmetic expressions/functions |
Monthly Average | Daily average for the month in megalitres per day. |
Time Series | Supports the inclusion of forecast data using data sources. |
Trend | A single target value (either positive or negative) plus a recession rate. |
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This allows you to define the average over the last specified number of time-steps.
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Function forecast model
You can define an expression expression or function to return any value you choose for each time-step in the forecast period. For example:
- a fixed value; or
- a fixed proportion of a variable that is available to the expression editorFunction Editor.
Monthly Average forecast model
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To trend from "today" to the monthly average, enable the Trend to Value at Rate checkbox and enter a trend rate which is a real number greater than zero but less than one. The observed daily flow rate for the previous month and the number of days of the current month are used to determine the initial flow volume.
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The results of executing one or more forecast scenarios can be viewed using the Recording Manager or the tabular editor (to view and override individual values). Ensure that you enabled recording for the parameter that you are forecasting. For example, to forecast flow, enable recording of the Inflow attribute in the Recording Manager. Figure 5 shows an example of the forecasted inflow for a modeloutput of a forecasted model. This forecasting scenario consists of two forecast models. A Trend forecast model is run for the first 10 time-steps and the remaining time-steps have a Function forecast model configured.
Figure 5. Charting tool, forecast models
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