RivEX

Step

Processing Task

1

You have prepared your river network and added the required attribution to the network so you can use the Create downstream reach for site tool.  How do you know which attributes you need to add to the network so this tool will function? The answer is in the help file, under the usage section. You need to have attributed your river network with Source ID.

2

Your Sewage Treatment Works (STW) dataset must conform to the specifications as discussed in the limitations section of the tool. The STW dataset should ideally be a point dataset in a File GeoDatabase. Avoid using shapefiles these are an old data format with limitations.

3

You will have added and populated a numeric field in your STW dataset that uniquely identifies each point. The points have been snapped to the network.

4

Run the STW data through the Extract positional information for site tool, to create a table, in this example it is called STW_Position.  One of the outputs is the distance to next downstream tributary (Dis2DSTrib).

5

The output table returns amongst other information the distance to the first downstream tributary visited when heading towards the network mouth. For clarity only a few fields are shown below, the output table typically consists of 12 attributes for each point.

6

You need to copy the downstream tributary distance field (Dis2DSTrib) into the STW data, you achieve this with the Join Field tool. A completed tool is shown below. We are joining the output of the site positional tool to the STW data based upon the STW ID and transferring a single field.

7

With the STW data now attributed with the distance to tributary junction we complete the Create downstream reach for site tool specifying the joined field as the field which holds the distance of the reach for the STW point that is to be created.  A completed tool is shown below.

8

The reach from the STW point to the first downstream tributary displayed as a pink line. The output of the site positional tool was used to attribute each STW point with the required distance to build the downstream reach. You may only be interested in the distance value, in this case the output of the site positional tool gives you what you need, but being able to visualise it can help with reporting as well as being a geometry that can feed into further spatial analysis such as intersecting with vulnerable species site data.

This worked example shows that RivEX can compute the required data and by simply joining the output of one tool to another you then have the inputs that can feed into another RivEX tool to generate useful data.  Such a workflow could easily be captured in model builder. In this example the input has been STW but they could also represent any site where you need to know the distance to the downstream tributary.