Thank you, that is a useful discussion to link to.
Processing Steps
@clay, every option here involves a process of:
- Download observations from iNaturalist or GBIF (usually in CSV format)
- Run some GIS tools on those observations
- See if any new observations show up since the previous run
There won’t be any way to get in instant notification that a new observation has shown up. It would be nice, but that option isn’t available here.
How up to date you are depends on how often you run these steps. It is possible to automate the GIS part, but it is also important not to download your observations too often. Also, this is easier to set up if you download all observations (of your taxa and rectangle of interest), but you will cause less server load if you work out a way to only download new observations and then merge them with your existing ones.
Location Error
As noted in the discussion @pisum linked to, not all observation coordinates are meaningful. In CSV data from iNaturalist, location error is stored in a field called public_positional_accuracy. This isn’t really accuracy, it is possible error in metres. Also, it is often undefined. Whatever your road “buffer radius,” you should screen out observations with a possible error higher than that.
A very common GPS measurement error is 10 metres, and I would suggest your radius at least that size. I have done work looking at flowering plant observations close to walking tracks. Having looked at common measurement errors in the observations, plus measurement errors in the walking tracks, I chose a 100 metre radius, because that was near enough for my project.
GIS Tools
As others have suggested, someone with GIS skills can do this fairly simply, once you define the problem the right way around. You may need to pay for their time if they aren’t already a volunteer on your project. However, you shouldn’t need to pay for data or tools; OpenStreetMap hopefully has enough road geometry in your area that you can download through the Overpass API, and QGIS is an open source GIS application that can do the analysis you need. (Some alternative tools exist too; I name QGIS because it’s the one I’m most familiar with.) If you may have ongoing questions of this sort, it’s worth learning QGIS yourself. The learning curve is steep, but there are many things involving iNaturalist observations that suddenly become easy to investigate with it.