Calculation time (Water Overlay): Difference between revisions
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Ensure that the [[Project area]] and the modeled water system are large enough to account for all effects relevant for the case, but avoid introducing water in locations where not is required. Use [[Limit area (Water Overlay)|Limit Area]]s, and/or [[Rain area (Water Overlay)|Rain Area]]s to restrict the calculations or the introduction of water into the system. | Ensure that the [[Project area]] and the modeled water system are large enough to account for all effects relevant for the case, but avoid introducing water in locations where not is required. Use [[Limit area (Water Overlay)|Limit Area]]s, and/or [[Rain area (Water Overlay)|Rain Area]]s to restrict the calculations or the introduction of water into the system. | ||
=== | ===Applicable models=== | ||
The {{software}} uses a number of different formulas to compute the movement of water across different parts of the water system. Depending on the fidelity and complexity of the models used, it may take time to compute small enough steps for water to move, or to synchronize different models so water can move across them. The most important impactors are the formulas used for the above-ground water flow, and whether the groundwater model is active. | |||
When simulating surface effects, be sure to take into account whether complete groundwater simulation will significantly impact the results for your use-case, and [[Ground water (Water Overlay)|refrain from using full groundwater simulation]] where possible. If groundwater is the main interest, the extended simulation time required to properly propagate groundwater effects will mean the [[Surface water (Water Overlay)|surface simulation can be simplified instead]]. | |||
==Aspects which do not impact calculation time== | ==Aspects which do not impact calculation time== | ||
Revision as of 07:46, 3 May 2023
Aspects which impact calculation time
The following aspects can negatively impact the calculation time of the Water Overlay:
Simulation time
The simulation of the Water Overlay requires that the movement of water is computed in small enough steps that the natural flow of water can be accurately simulated. This means that for any given simulation time, the total simulation time is divided into calculation timesteps of less than a second. For each timestep, all grid cells must undergo a calculation. The longer the simulation time, the more individual timesteps must be computed, and therefor the longer it takes to fully calculate the entire duration of the intended simulation.
Ensure the duration of the simulation is set to a timespan suitable for the intended use-case, but not longer than neccesary.
Grid cell size
The more cells requiring calculation, the more time is requires to perform the neccesary calculations for every cell in the project area. The Tygron Platform can run many calculations as such in parallel, but with large enough quantities more cells means it may take multiple passes to compute them all. A smaller grid cell size means a quadratic increase in the amount of cells. Halving a cell's size means 4 times as many cells to compute.
In addition, smaller grid cells means that to properly calculate the flow of water, the amount of time per computational timestep is reduced. This is because water with the same impulse can travel just as quickly, but must not be allowed to overshoot any cells in between.
Ensure the grid cell size is set small enough that any significant waterways in the Project area are at least 4 grid cells in width, and water is allowed to flow through any other significant routes. But do not reduce the grid cell size significantly beyond that size.
Geographical spread of water
The Tygron Platform relies on an parallelized but also algorithmically optimized system. This means that although calculations of cells happen at the same time as much as possible, the Tygron Platform will also take note of where there is water to perform calculations with, and ignore regions where there is nothing to calculate. This means the calculations will only be performed for relevant areas where water is present, meaning fewer calculations are required overall, and the calculation may therefor complete quicker.
Ensure that the Project area and the modeled water system are large enough to account for all effects relevant for the case, but avoid introducing water in locations where not is required. Use Limit Areas, and/or Rain Areas to restrict the calculations or the introduction of water into the system.
Applicable models
The Tygron Platform uses a number of different formulas to compute the movement of water across different parts of the water system. Depending on the fidelity and complexity of the models used, it may take time to compute small enough steps for water to move, or to synchronize different models so water can move across them. The most important impactors are the formulas used for the above-ground water flow, and whether the groundwater model is active.
When simulating surface effects, be sure to take into account whether complete groundwater simulation will significantly impact the results for your use-case, and refrain from using full groundwater simulation where possible. If groundwater is the main interest, the extended simulation time required to properly propagate groundwater effects will mean the surface simulation can be simplified instead.
Aspects which do not impact calculation time
Timeframes
