Looking for Network Generation Tool

[Anonymous User]

Original User: dnagel

Hello -

This is a two part question. I'm new to Arc Hydro Tools and having some trouble understanding the full scope of the software. Utlitmatetly I want to generate network topology on a stream network. This stream network is the NHDPlus data that has been resplit into 1 km segments. For each 1 km segment I want to know the downstream link ID, and the 1 or 2 upstream link IDs (upstream and downstream neighbors). Ideally this data model would be a line shapefile with attributes directly in the line attribute table. I'd rather not deal with the whole edge/junction topology in a geodatabase. This project covers 250 4th code HUCs of NHD data in the NW.

1) Does anyone know of any software that will ingest a shapefile stream network and compute all of the upstream and downstream links and attribute the shapefile with this information?

2) I've been told that Arc Hydro is a way to generate network topology, but it appears to me that a catchment polygon file is required to generate the topology. Is this true? There's no way we're going to generate catchments from a DEM for every 1 km stream segment in the NW US.

I would really appreciate any guidance and would appreciate emailing someone who might have experience with these issues.

Thank you! Dave

[Anonymous User]

Original User: cdarti

For 1:

You can use the Attributes Tools>Generate From/To Node for Lines and then Find Next Downstream Line in Arc Hydro to determine the ids of the next downstream line. Your input line may be a shapefile for these 2 tools but must contain the field HydroID (long integer) storing IDs that uniquely identify your source line features. The HydroIDs will be used to populate the NextDownID field storing the HydroID of the next downtream lines. The most downstream lines will have NextDownID=-1.
If one line has more than one downstream lines, then the HydroIDs/NextDownIDs will be stored in an additional table called "sourceline"_FS, where FS stands for flow split and "sourceline" is the name of your input feature class. This table has 2 fields (FEATUREID=line HydroID, NEXTDOWNID).

For 2:

The network generated by Arc Hydro requires a polygon feature class as it establishes some additional relationship between the traditional geometric network that can contain only line and points and the area represented by polygons. In you case since you are interested only in points and lines you can use the traditional geometric network that can be created in the Catalog window or the geoprocessing tool. You stream features will become traceable edges in the network (just make sure you also set the flow direction in the network).

Christine Dartiguenave
Esri Water Resources Team