discover_nhdplus_id: Discover NHDPlus ID

In nhdplusTools: NHDPlus Tools

Discover NHDPlus ID

Description

Multipurpose function to find a COMID of interest.

Note that NHDPlusV2 uses "featureid" for catchment polygons and "comid" for flowline linestrings. These two identifiers are the same where a flowline/catchment pair exists. In some cases, a catchment will not have a flowline and in others, a flowline will not have a catchment.

If a point is provided, and raindrop is false, the comid/featureid integer of the catchment the point is in is returned. This options uses a web service here: https://api.water.usgs.gov/fabric/pygeoapi/collections/catchmentsp

If a point is provided, and raindrop is true, the response is the result of a call to get_raindrop_trace.

If no point is provided, the raindrop argument is ignored and the result is a comid integer derived from a call to get_nldi_feature.

Usage

discover_nhdplus_id(point = NULL, nldi_feature = NULL, raindrop = FALSE)

Arguments

point	sfc POINT including crs as created by: sf::st_sfc(sf::st_point(.. ,..), crs)
nldi_feature	list with names 'featureSource' and 'featureID' where 'featureSource' is derived from the "source" column of the response of get_nldi_sources and the 'featureSource' is a known identifier from the specified 'featureSource'.
raindrop	logical if TRUE will call a raindrop trace web service and return will be the same as get_raindrop_trace with direction "none".

Value

integer COMID or list containing COMID and raindrop trace.

Examples

point <- sf::st_sfc(sf::st_point(c(-76.874, 39.482)), crs = 4326)
discover_nhdplus_id(point)

discover_nhdplus_id(point, raindrop = TRUE)

nldi_nwis <- list(featureSource = "nwissite", featureID = "USGS-08279500")
discover_nhdplus_id(nldi_feature = nldi_nwis)

nhdplusTools documentation built on Jan. 21, 2026, 9:06 a.m.