A buffer is a required amount of space between features. Buffers are used for many reasons, such as
We assume that, in our hypothetical project, a buffer was put as a constraint on the project to prevent any ground drilling from damaging the mains; this means that we would have to mark the buffer on our map so that we know the area to avoid.
We'll first start with creating a buffer zone for all elements within a layer.
In ArcMap, go to Geoprocessing --> Buffer
In the buffer window input the following:
After a few moments of processing, a new layer will be added to your map. The blue round shapes are the buffer areas around the sewer mains.
In some instances, you will have a single layer with different buffer requirements. In this part, you'll learn how to separate parts of a layer into sub-layers, and then create a different buffer for each sub-layer.
For this hypothetical project, we will create a buffer of 150 ft around the main sewer lines that are adjacent to Charleston Blvd and a buffer of 50 ft around the main sewer lines adjacent to Oakey Blvd.
Step 1: create a separate layer for sewer main adjacent to Charleston Blvd.
Right click on the Sewer Manhole layer, then Selection --> Make this the only selectable layer
Step 2: select the desired area for buffering.
Click on the select features button to turn it on. If needed, choose Select by Rectangle from the drop-down menu.
Click and drag a rectangular selection over the sewer line adjacent to Charleston Blvd. The selected lines will appear highlighted in light blue.
Step 3: create a new layer from the selected lines.
Right-click on the Sewer Mains layer --> Selection --> Create Layer from Selected Features
Clear the selection by going to the main top-level menu, clicking on Selection --> Clear Selected Features.
Step 4: create the buffer from the new layer
Go to the newly created layer, click on the layer's name, then press the F2 button to rename the layer "SewerMains_C_Charleston"
Then go to Geoprocessing --> Buffer, and complete the form like we did above but with 150 feet for the distance. Make sure your rename the buffer to indicate it's the buffer for Charleston.
The form will look like that:
And this is the buffer:
Repeat steps 1-4 to create a 50-ft buffer for the sewer main adjacent to Oakey.
The final map will look like this: