findWBD breaks topology about hydrodata HOT 1 CLOSED

Hi Joseph,

Thanks! This is an interesting point.

Looking at two offenders from your example:

library(leaflet)
leaflet() %>% addTiles() %>% addPolygons(data = h4s$huc4[c(1,8), ])

doesn't reveal any obvious overlap. Since this is a big request (25 HUC4s) it is coming from the staged USGS data found at their FTP - so a pretty nice dataset.

My guess is this is not a break in topology but rather a byproduct of findWBD() downloading and returning a merged file of polygons features.

Each feature is a unique, complete HUC boundary so any lines shared by two adjacent HUCs (eg 1 and 8) will be contained in the polygon of both feature 1 and 8. Therefore when compared, those lines will overlap simply because they are identical. I do not believe they are crossing each other in anyway so this issue should not impact any sort of analysis.

Let me know if you think I am off on this!

Mike

from hydrodata.