Rain model (Water Overlay)
Rain can be implicitly activated and deactivated by defining an appropriate period of rainfall as weather effect. If a period with no rainfall is defined, that period is simulated but no rain is simulated.
Currently, during a period in the simulation where rainfall is defined, water is uniformly added to the surface of all cells in the project area. During any single defined period of rain, the amount of rain is consistent over time. At the end of the defined period of rain, exactly the defined amount of rain will have fallen on each cell.
Dynamic rainfall
It is possible to add up to 50 consecutive rain periods. See the table below:
| Time key (minutes) | Amount of rainfall (mm/m2) |
|---|---|
| 35 | 15 |
| 42 | 19 |
| 120 | 5 |
This format can be interpreted as followed:
The first period is starts at t=0 minutes and ends at t=35 minutes. In this first period, 15 mm/m2 of rain will fall. Uniformly this gives 15 / ((35 - 0) * 60) = 0.00714 mm per second.
The second period starts at t=35 minutes and ends at t=42 minutes. In this period, 19 mm/m2 of rain will fall. Uniformly this is 19 / ((42 - 35) * 60) = 0.04524 mm rain per second.
The last period starts at t=42 minutes and ends at t=120 minutes. In this period, 5 mm/m2 of rain will fall. Uniformly this is 5 / ((120 - 42) * 60) = 0,00107 mm rain per second.
In total it can be expected that per m2 15 + 19 + 5 = 39 mm rain has fallen in a total simulation time of 120 minutes.
Notes
- The rainfall table is stored as an attribute array in the Weather selected by the Water Overlay
- The time keys in seconds.
- The last time key also determines the total simulation time.