In this section you will start RivEX, load the sample data and build the node information required for further processing.

1.Having downloaded RivEX with its sample data you will have enabled the AddIn following the instructions on the website. Install instructions can also be found here.

2.The RivEX tool bar will not enable until you have added the demonstration dataset C:\RivEX\Demo_Data\AlaskanNHDSample.shp to the map.

3.If you open the layers Attribute Table you will observe that it has only 3 fields: FID, Shape and an ID field called ComID. These are shown in the image below. You can close the Attribute Table when you have finished reviewing it.

Layer and attribute table

4.Click on the enabled RivEX tool bar button (Enabled tool bar); you will be presented with the following message box. Read it!

5.The main interface of RivEX opens, more information about the interface is found here. Complete the layer to process section as shown below, select the layer, ID field and set the FROM and TO node fields to *** ? ***.

Main interface

6.You must now set the workspace, this is the folder than your dataset is in. In this case the AlaskanNHDSample is in C:\RivEX\Demo_Data. Click on the Workspace button (Set Workspace button) and navigate to C:\RivEX\Demo_Data. Do not navigate into this folder. The interface must look as below.

Layer and workspace set corretly

7.Click on the Build button. RivEX will now extract out the topological information and write this to the cache folder. When the build process finishes the Tools panel will activate. RivEX will have also written this information back into two new fields Fnode and Tnode. This information is used by many other tools.

WarningAll because RivEX was able to extract the information it does not mean that the network conforms to standard topological rules. With your data you must always run it through the Quality Controls to identify any errors and correct them before using any of the processing tools.