View source for How to modify evaporation factor from trees to forests

Default values for the evaporation factor of trees are set to a value consistent with the placement of individual trees. This means that if an individual tree is loaded in as a singular polygon, their evaporation factor is set properly. However, when an entire forest is loaded in, the entire forest is loaded in as a singular polygon. Where a polygon representing an individual tree may have about 1{{m2}} of polygon per tree, a forest may have closer to 30{{m2}} or 40{{m2}} per tree. This means the evaporation factor would also be multiplied with a greater surface area, and the resulting evaporation would be a similar factor too great. To correct this, you can take the following steps.

{{Editor location|building}}

{{Editor steps|title=change the evaporation factor for forests
| Determine the forest (or larger group of trees) for which the evaporation factor should be changed.
| Determine the ratio of surface area to amount of trees, for example by dividing the area of the forest by the amount of trees in the forest.
| Select the Construction which represents the forest in the Editor.
| Go to the "Details" tab.
| Find the "Water evaporation" Function Value.
| Divide the "Water evaporation" value by the rato determined earlier, to get a new, lower evaporation factor.
| Enter that new factor as the "Water evaporation" Function Value for this forest.
}}

{{article end
|notes=
* To do this en-masse for Constructions with a tree-line function, consider modifying the [[Function Value]]s of the relevant Functions instead. Note that this may mean you will want to perform the opposite operations on individual trees where appropriate.
* If you have a [[GeoJSON]] file with data on tree density, you can combine that file with a GeoJSON file containing exported Constructions from your Project. You can use that information to calculate a new evaporation factor for all tree-like Functions, and then [[Geo Data#Import Geo data|import]] that data into your Project again as update for your existing Constructions.
|seealso=
* [[Water evaporation (Function Value)]]
* [[Evaporation model (Water Overlay)]]
}}

[[Category:How-to's]]