How to initialize a groundwater prequel: Difference between revisions

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When working with the [[Ground model (Water Overlay)|complete groundwater model]] of the [[Water Overlay]], it is very likely that any initial configuration for groundwater is not actually the state of the groundwater "at rest", meaning that during the initial period of the simulation the groundwater will always flow to a different location into a more stable configuration. For example, an initial groundwater dataset may have a consistent groundwater level defined for a large plot of land, while the more natural situation may be that the water follows a curve due to the way water flows into and out of the ground.
Initial configurations for the [[Ground model (Water Overlay)|complete groundwater model]] of the [[Water Overlay]] often do not represent the state 'at rest'. Consequently, groundwater typically flows toward a more stable configuration during the simulation's initial period. For example, an initial groundwater dataset may have a consistent groundwater level defined for a large plot of land, while the more natural situation may be that the water follows a curve due to the way water flows into and out of the ground.


The consequence of this phenomenon, especially for short simulations, is that groundwater will not yet have reached a natural state by the the time the main event of the simulation takes place, or even when the simulation ends. To compensate for this, it is possible to prepare the groundwater data by setting up and running a stationary calculation for groundwater, allowing it to settle, and using the (more natural and stable) result as the initial groundwater state for the actual calculation.
In short simulations, groundwater may not reach a natural state before the main event or simulation end. To compensate, run a stationary calculation first to allow the groundwater to settle, then use this stable result as the initial state.


This can also be achieved in a dynamic setup in which the calculation for intialization is set up as a "prequel", an explicit precursor calculation to the actual simulation.
This can also be achieved in a dynamic setup in which the calculation for initialization is set up as a "prequel", an explicit precursor calculation to the actual simulation.


{{howto|title=initialize a groundwater prequel
{{howto|title=initialize a groundwater prequel
| Add a Groundwater Overlay intended to initialize a groundwater level, ahead of the actual intended simulation.
| Add a Groundwater Overlay to initialize the groundwater level before the actual simulation.
| Ensure that the Groundwater Overlay has the [[Ground water (Water Overlay)|groundwater mode]] set to "Complete".
| Ensure that the Groundwater Overlay has the [[Ground water (Water Overlay)|groundwater mode]] set to "Complete".
| Ensure that the Groundwater Overlay has [[Groundwater_depth_prequel_(Water_Overlay)|data for groundwater]] set, if one is available.
| Ensure that the Groundwater Overlay has [[Groundwater_depth_prequel_(Water_Overlay)|data for groundwater]] set, if one is available.
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{{article end
{{article end
|notes
|notes
* It's very likely that at the start of the actual calculation's simulation, the groundwater will still take a moment to settle. However, through these steps the time it takes and the margin of difference is greatly reduced.
* Groundwater may still require a brief period to settle at the start of the actual simulation; however, these steps significantly reduce this duration and the resulting variance.
* If the prequel ground water overlay is good as it is, it is advised to put it on inactive to prevent it being recalculated unnecessarily.
* If the prequel Groundwater Overlay is correct, set it to inactive to prevent unnecessary recalculations.
|seealso=
|seealso=
* [[How to generate an initialized groundwater situation]]
* [[How to generate an initialized groundwater situation]]
|api=*[[Api session event editor overlay add]]
*[[Api session event editor overlay set attribute]]
*[[Api session event editor overlay add result child]]
*[[Api session event editor overlay set prequel]]
*[[Api session event editor update]]
}}
}}


[[Category:How-to's]]
[[Category:How-to's]]

Latest revision as of 14:29, 15 July 2026

Initial configurations for the complete groundwater model of the Water Overlay often do not represent the state 'at rest'. Consequently, groundwater typically flows toward a more stable configuration during the simulation's initial period. For example, an initial groundwater dataset may have a consistent groundwater level defined for a large plot of land, while the more natural situation may be that the water follows a curve due to the way water flows into and out of the ground.

In short simulations, groundwater may not reach a natural state before the main event or simulation end. To compensate, run a stationary calculation first to allow the groundwater to settle, then use this stable result as the initial state.

This can also be achieved in a dynamic setup in which the calculation for initialization is set up as a "prequel", an explicit precursor calculation to the actual simulation.

How to initialize a groundwater prequel:
  1. Add a Groundwater Overlay to initialize the groundwater level before the actual simulation.
  2. Ensure that the Groundwater Overlay has the groundwater mode set to "Complete".
  3. Ensure that the Groundwater Overlay has data for groundwater set, if one is available.
  4. Ensure that the Groundwater Overlay has a ground last value output.
  5. Configure the rainfall for the model to run stationary, for a period of multiple weeks.
  6. Recalculate the Groundwater Overlay.
  7. Add a second Groundwater Overlay, which will use the first Groundwater Overlay's results as input.
  8. Open the second Groundwater Overlay's Water Overlay configuration wizard, and proceed to the groundwater step.
  9. Select the option "Select a Groundwater Depth Grid Overlay".
  10. Select the first Ground Water Overlay as prequel.

See also

API Endpoints

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