Water Module Changes

This page describes the changes between the Water Module LTS 2024 -> LTS 2026. These changes will result in a faster en more realistic result, but can be reversed for full backwards compatibility.

Updates

The Water Module 2026 has several changes, most changes only make it faster or contain additional functionality. The changes listed below could also influence the outcome.

• Polygon rasterization: is now much faster and more accurate by using the center point. The old outline method could overshoot rasterize more cells that needed, this has been fixed by using center points. This can result in e.g. small differences in the way water flows between e.g. buildings.

• Drainage height: is not always set to the datum height provided, cells that are above the surface are now ignored. This creates easier drainage usage because in the old method the drain could be lowered due to 1 cell with a to low surface level.

• Groundwater: Minimal saturation Unsaturated Zone is now set by default around 10%. This prevents the unsaturated zone from completely drying up and compensates for e.g. capillary effects. It can be adjusted via the MIN_UNSATURATED_FRACTION attribute.

• Groundwater: Infiltration active for waterways by default. This GROUND_INFILTRATION_MD attribute used to default to zero (0) thus prevented proper interaction between the groundwater and the waterway in 'complete' groundwater mode. Note: in 'infiltration only' mode the waterway infiltration is still disabled by default preventing the waterway from leaking.

Revert

By adjusting these items you get the identical results as in the LTS 2024:

• Rasterization: Switch to the old "outline" mode in the Calculation panel.

• Drainage height: Set Water Overlay attributte MIN_DRAIN_SURFACE_DISTANCE_M to a large negative value, e.g. -1000. This will cause the drain to be lowered again when a cell's drainage datum height is above the surface.

• Groundwater: Minimal saturation: Set attribute MIN_UNSATURATED_FRACTION to zero (0) for all underground terrains in your project. Or by using the MIN_UNSATURATED_FRACTION prequel with a combo with only zero (0) values.

• Groundwater: Infiltration waterways: Set attribute GROUND_INFILTRATION_MD to zero (0) again for waterway surface terrains.