Lowest Value Polygon Topography Application Method

2D solver includes a new application method for polygons, which allows any model bed elevations within the polygon to be set to the lowest existing bed elevation within the polygon. This feature can be used to model underpasses in embankments.

For example, an underpass exists under and embankment whose crest is at 10.0 mAOD and the base of the embankment is approximately 5 mAOD. By drawing a polygon over the area we wish to lower as well as some of the surrounding, lower ground levels, the minimum value of 5 mAOD will be applied to the whole polygon, lowering the embankment to allow flow through the underpass.

Polygons used for applying the lowest elevation must have an integer attribute called lowest_val which must be set to a non-zero value.