Between barrier analysis
- RivEX is capable of computing available river lengths between barriers or river source. Upstream available length is defined as all upstream polylines reached from a starting barrier until they are stopped by another barrier or river source.
- A barrier is a point snapped to the network. Such points represent real world structures such as weirs, dams or any other feature blocking the path upstream.
- For more information about the specifics of how the code runs, click here. The rest of this page deals with how to use the tool.
- To compute between barrier lengths RivEX requires you to have processed your network for catchment ID and accumulated upstream lengths. You must have done these BEFORE attempting to use this barrier tool. Please refer to the appropriate sections of this manual for how to calculate these values.
- To use the barrier analysis tool you must complete the parameters section of the main interface and press the Build button.
- Click on the between barrier analysis tab.
- In the select barrier layer frame, identify the point layer that represents the barriers and the unique ID field as shown below. This point layer must be loaded into the map document before you open the main RivEX interface.
- You will asked to confirm that the point layer is a layer with points snapped to the network. Go here to find out about using RivEX for snapping points to the network.
- You must now identify the catchment ID field and upstream accumulated fields. These are RivEX generated fields and must have been created before you use the barrier tool.
- Click on Go! and the tool will run and and when finished, announce that it will send the data directly to MS Excel. The tool will terminate early if any of the barriers do not have a unique ID or identify a single starting polyline (i.e. not snapped to the network).
- The Excel file will contain an initial worksheet listing all barrier IDs, the catchment number they are within, the polyline ID they intersect and total upstream length (as if there were no barriers).
- For each catchment the barriers lie within; a list of barrier IDs and available upstream length are listed. In the example image below the network run through RivEX only had one catchment which was numbered 1.
