Ability to aggregate fine network to coarse network

[mwtoews]

For example, if a primary 1st order network of lines and polygons is received, but flow data is on 3rd order streams, then there should be a method to aggregate lines and polygons to match the network specification.

A current workflow is established with PostGIS, which takes a list of segment IDs used for the derived network, and aggregates geometries using geometry unions.