Warning and recommendations (Water Overlay)
When the water overlay is used and calculations take place, there are some problems or points of attention the calculation can run into. Where possible, the water overlay will show appropriate warnings when running into any issues.
Configuration wizard warnings
While configuring the water overlay using the configuration wizard, each type of data loaded in or found in the project must meet certain requirements to be functional. For example, configured water levels may deviate greatly from the mean terrain height in the project, or certain hydrological constructions may not be shaped appropriately or intersect with required features. In these cases, the configuration wizard will show the warnings in the steps related to the specific type of data.
When the project is created, the advanced options allow for selecting a high-resolution height map to be loaded in. The default, low resolution height map can introduce artifacts in the calculation due to inaccuracy. This issue can currently only be resolved by reloading the project area.
If the overlay is recalculated, but the (re)calculation is halted, the water overlay will not contain meaningful results. A warning will be displayed indicating that the calculation did not complete.
Large cell size
The water overlay performs its calculations based on a discretization of the project area. This means both that areas of water are considered a single block, and that obstacles and hydrological properties are averaged out over the extent of a cell. To best approach a realistic, continuous water flow and a realistic model of obstacles and values, it is sufficient to reduce the size of the cells the calculation uses.
When a grid based overlay is added to a project, the default size of 10m x 10m is usually not acurate enough. This will be indicated by a (yellow flashing) warning on the right side panel when the overlay is selected. This grid size can be adjusted by selecting the "Change grid" option on the right side panel. Selecting this option opens a new panel. When adjusting the grid size, please note that the smaller the grid size, the longer the calculations will take. If the new grid size is set to 5m x 5m, the amount of cells quadruples. A grid of 4 cells will now contain 16 cells!
The Water overlay simulation time (in timesteps) is too long. Currently the maximum amount of timesteps on a 10x10km map is 100.000.000. You can resolve this by lowering the simulation time, larger grid size or change the Calculation preferences
Calculation time impacts