7) Extract the nearby network for sites

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In this section you will extract the nearby upstream and downstream network for the test sites. You must first add the distance and buffer fields, populate these and then run the tool.


1.If open, close the RivEX dialog and load the point dataset C:\RivEX\Demo_Data\TestSites_Snapped.shp.


2.Open the attribute table.


3.Add a field, call it myUSDSDist and set its type to Long.


4.Add another field called myUSDSBuff and set this to type Long.


5.The Attribute Table should look as below.


Attribute table


6.Right Click on the header of myUSDSDist select Field calculator and populate the field with a value of 2000.


6.Right Click on the header of myUSDSBuff select Field calculator and populate the field with a value of 50.


7.The Attribute table should look as below. You have created 2 new fields and populated them with a set of values. Once you have achieved this close the Attribute table.


Attribute Table with populated fields


8.Open RivEX again by clicking on the Yellow button in the tool bar. Complete the layer to process panel and shown below. If RivEX asks to build a spatial index then accept this. Make sure you set the workspace.


Completed layer to process panel


9.Pressing the Build button tells RivEX to compare the modification date of the dataset with what is stored in the settings file, if it is found to be different then it will rebuild the topology cache otherwise it accepts the dataset and enables the tools.


10.In the Tools panel, expand Site processing, tick on "Extract nearest network" and then press Run Tool to open the Extract nearest network dialog.


11.Complete the dialog as shown below below. You are using one field to define the distance you want extracted upstream and downstream and similarly a single field for the buffer distance. As this tool is taking the distances from the fields in the dataset each point could potentially have a different distance. In this walk through you are extracting a constant distance for each site but in reality these values could have been scaled under some other scenario.


Extract nearest network dialog


12.Press OK to allow the tool to run and accept the dialog asking you to add the data to the map.


13.Close the RivEX form.


14.You can then symbolize your data appropriately, an example is shown below. These spatial datasets could be used in further analysis or visualization.


Nearby network example