Upstream segment identifier

• You can use RivEX to extract all upstream polyline ID's for a single polyline or process the whole network in one go and store the data on a catchment basis.  The output are stored as tables in a Geodatabase.

• This tool will generate very large tables for large river networks and will therefore take a long time to process such networks. A walk through example of using the segment identifier tables with the standard ArcMap RELATE function can be seen here.

• To identify upstream polyline ID's you must complete the parameters section of the main interface and press the Build button.

• Click on the Analyse network tab and then tick the segment identifier check box. Click on Go! to start the processing.

• The following dialog allows you to specify what you want processed.

• If you want to process a single polyline to find all upstream polylines, click on the upper radio control () and then type in the polyline ID you wish to process.  RivEX will reject an ID number that does not exist.

• If you want this process to be run for all polylines within your river network, click on the lower radio control and then select the field that holds the catchment ID's.  Catchment ID's are used to group the output into separate tables and thus avoids producing a huge table which few applications can handle.

• Once the processing has competed, RivEX attempts to locate a Geodatabase in C:\RivEX\Output and removes all tables ending with "Upstream_IDs".  If your river layer was called RivNet then the GeoDatabase will be named RivNet_Tables.mdb.

• The Geodatabase is then repopulated with Tables listing the polyline IDs.    Each Table uses the naming convention Catch_XXX_Upstream_IDs where XXX is the catchment ID or Polyline_ZZZ_Upstream_IDs where ZZZ is the ID of your chosen polyline.

• RivEX finishes by building an attribute index to optimise any future querying.

• In the image below, the network is colour coded by catchment ID. Catchment ID was generated with the force furthest route option turned on and we see the majority of the network is coloured blue whilst a small drain is coloured brown as it flows to an unconnected mouth (the magenta coloured node).  The furthest source is indicated by the red node and the arrow indicates the node at which the drain connects to the main catchment.

• Upstream of the arrow, are the polylines part of the blue or brown segment ID tables?  The answer is both as the segment ID tables are only storing topological information and use the catchment ID as a convenient method of grouping the data.  Thus all polylines  upstream of the arrow appear in both segment ID tables.  If a survey site happened to be on the the brown drain then it's segment ID tables would allow you to search upstream to the source of the river and not terminate at the arrow.