Explore topological enforcement of shared boundaries between active channel and active floodplain, and active floodplain and inactive floodplain, and the plausible valley bottom extent and all of these (potentially).

[joewheaton]

@philipbaileynar and I started discussing this over in Riverscapes/riverscapes-tools#362

[joewheaton]

@philipbaileynar, this is a throwback discussion to what we discussed the other night with the problem of making sure that Tier 1 Valley Bottom polygons are actually mutually exclusive mappings of the valley bottom. I know we have containers for some of these, not all (i.e. only Active and Inactive not Active Channel, Active Floodplain, Inactive Floodplain.

BTW, the workflow I was struggling with was I drew a "Inactive" polygon representing the whole valley bottom. I had mapped "Active Channel" separately. There was no "Active Floodplain". I wanted to clip out of the "Inactive" polygon (i.e. my entire VB) the "Active" polygon representing my channel. In ArcGIS this is simple during an edit session. In QGIS, I had to stop editing both those feature classes, and run Symmetrical Difference from the processing toolbox with "Active Extents" as the input layer and "Inactive Extents" as the overlay layer. We discussed ways of bringing some of these commands into the QRiS workflow.

More to follow...