New feature: have the create polygon tool also create polygons along a stream network with branches

[jrutyna]

A new feature should be developed that allows the create polygon tool also create polygons along a stream network with branches. This could be accomplished with having additional polylines features in the input centerline shape file and by iterating on each feature in this shape file and looping over the existing create polygon tool for each centerline feature in the branched stream network. The tricky part may be implementing how the transects/polygons are constructed at the confluences.

[jrutyna]

An existing/functioning/calibrated CE-QUAL-W2 model with stream branching should be identified and acquired so the this new feature can be tested. This model should also have the associated DEM that was previously used to create the bathymetry input.