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internetofwater / nldi-services

Network Linked Data Index Navigation Web Services
https://waterdata.usgs.gov/blog/nldi-intro/
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Issue with split_catchment for a station #355

Open cheginit opened 1 year ago

cheginit commented 1 year ago

I found an issue with NLDI's basin endpoint for station ID of 08074500. Here's what it looks like w/o splitCatchment:

image

The small bit in the right corner of the left subplot is where the station is located.

Here's the request URL: https://labs.waterdata.usgs.gov/api/nldi/linked-data/nwissite/USGS-08074500/basin?simplified=true&splitCatchment=false

cheginit commented 1 year ago

For reference, I got the basin from gagesii_basins layer of WaterData's GeoServer: image

dblodgett-usgs commented 1 year ago

Thanks for this @cheginit -- I've shared this with @Anders-Hopkins to see if he can look into the little dangler polygon.

The gagesii polygon is derived from a different source -- so going to be different in many cases.

cheginit commented 1 year ago

I found another station (USGS-03238140) where NLDI with split set to true returns a very large geometry that has an area of, 188221 sqkm while the original drainage area of the basin is 11 sqkm!

dblodgett-usgs commented 1 year ago

@Anders-Hopkins can you look into this?

Anders-Hopkins commented 1 year ago

Just got back from some vacation. I'm catching up on work, but I'll look at this as soon as I can. Just shooting from the hip on this one, my guess is that the query point is snapping to the next major river (which looks like the Ohio in this case) and delineating the basin from there. Not sure why this is happening but I'll get to the bottom of it.