constrain parameters for stability of raster-to-network grid conversion & NetSedTransporter

[shelbyahrendt]

Just a couple of notes to add to the jupyter notebook or raise errors in the code:

• limit the number of watersheds in the ChannelProfiler to 1 (otherwise you'd have to set up multiple network-sediment models and that's beyond the scope of this lab): number_of_watershed = 1

• keep the watershed threshhold specified in the ChannelProfiler above a certain limit-(I think I tested it at 10,000 m^2, we could maybe go a bit more refined than that, but I'm not sure how the sediment-tranporter will handle a dense network) i.e. minimum_channel_threshold > 8,000 #m^2 as long as channel_definition_field='drainage_area'

• desired node spacing should be greater than the grid resolution but less than the minimum ChannelProfiler segment length: in psuedocode: d_node_spacing > (rmg.dx & rmg.dy) & d_node_spacing < min(profiler.seglength)