Calculation preference formula (Water Overlay)
This settings influence the timesteps for rain, surfaceflow and groundwater in the calculation model. All settings result in stable solution, however small fluctuations can occur in the hydro-graphs. By default Speed is selected, only change this when your use-case demands it.
- Speed: Larger timesteps (default).
- Normal: Average mode between Speed an Accuracy.
- Accuracy: Smallest timesteps, smoothest hydro-graphs.
Low Impulse Mode
By default the model uses full impulse to simulate waterflow. However when using long term average calculations (e.g. groundwater year round) the (short term) impulse has a very limited effect on the outcome. In this case select the Low Impulse Mode option which reduces gravity in your simulation and thus the impulse. This means that peak velocity in heavy rain-showers or floodings are not accurate, but the average waterflow through the system remains the same.
Warning: Do not use this option with floodings or heavy rain-shower stress calculations.