Structures

Structures represent building footprints or other solid obstacles within the domain. They modify both the elevation and the friction of the mesh.

Not for culverts, bridges, or weirs

"Structures" here means buildings and solid obstacles that block or impede flow. It is not for hydraulic conveyance structures (culverts, bridges, weirs). Those are modelled in ANUGA with the Inlet_operator, Weir_operator, and Culvert_operator operators, which the hosted scenario package does not yet expose as a dedicated input field. If your model needs them today, you can configure operators when you run ANUGA yourself. For the modelling expectation a reviewer will check, see the Verification checklist, section 7 (invert and capacity).

How structures work

When structures are present, two things happen during mesh setup:

1. Elevation burn: Building footprints are rasterised onto the DEM with a height of 5.0m added (using gdal_rasterize). This raises the ground surface to prevent water flowing through buildings.

2. Friction override: Building polygons receive a Manning's roughness coefficient of 10.0, further impeding any flow that does reach the raised elevation.

Methods

Each structure feature has a method property:

Method	Behaviour
Mannings	Applies high friction (n=10) to the polygon
Holes	Removes the polygon from the mesh entirely
Reflective	Creates a reflective internal boundary

Note

The Holes and Reflective methods are experimental. For most use cases, the default Mannings method with elevation burn is recommended.