Hi all:
There is likely another method to perfor this task this already so I appreciate any help or ideas offered. I am often asked to find points at a certain distance upstream from a surface water intake. Rather than look at each buffer around each intake manually, I am looking for a method to generate a semicircle of a known radius with its center at the intake and, once generated, align the semicircle's perpendicular radius to the upstream direction in the NHD flowlines. Then a simple select by location can be used.
Right now, I use a set buffer size on the intake points which gives me a conservative distance on the stream. But, I end up looking at each buffer individually so I can identify if the outfall is upstream or downstream. So far this is the method I have explored: 1) generate the buffer around the intake, 2) use the Split Tool to generate four quadrants, 3) delete the bottom half of the semicircle, manually rotate the semicircle tothe upstream direction. I tend to look at upwards of 200 intakes; a simpler or automated method would be great!
I have attached a JPG image with my simplified approach.