Get split catchment — get_split_catchment • nhdplusTools

Uses a catchment splitting web service to retrieve the portion of a catchment upstream of the point provided.

get_split_catchment(point, upstream = TRUE)

Arguments

point: scf POINT including crs as created by: sf::st_sfc(sf::st_point(.. ,..), crs).
upstream: logical If TRUE, the entire drainage basin upstream of the point provided is returned in addition to the local catchment.

Value

sf data.frame containing the local catchment, the split portion and optionally the total drainage basin.

Details

This service works within the coterminous US NHDPlusV2 domain. If the point provided falls on an NHDPlusV2 flowline as retrieved from get_raindrop_trace the catchment will be split across the flow line. IF the point is not along the flowline a small sub catchment will typically result. As a result, most users of this function will want to use get_raindrop_trace prior to calls to this function.

An attempt is made to eliminate polygon shards if they exist in the output. However, there is a chance that this function will return a multipolygon data.frame.

Examples

# \donttest{
point <- sf::st_sfc(sf::st_point(x = c(-89.2158, 42.9561)), crs = 4326)

trace <- get_raindrop_trace(point)

if(inherits(trace, "sf")) {

(snap_point <- sf::st_sfc(sf::st_point(trace$intersection_point[[1]]),
                          crs = 4326))

(catchment <- get_split_catchment(snap_point))

bbox <- sf::st_bbox(catchment) + c(-0.005, -0.005, 0.005, 0.005)

nhdplusTools::plot_nhdplus(bbox = bbox, cache_data = FALSE)

plot(sf::st_transform(sf::st_geometry(catchment)[2], 3857), add = TRUE, col = "black")
plot(sf::st_transform(sf::st_geometry(catchment)[1], 3857), add = TRUE, col = "red")
plot(sf::st_transform(sf::st_sfc(point, crs = 4326), 3857), add = TRUE, col = "white")

(catchment <- get_split_catchment(snap_point, upstream = FALSE))

bbox <- sf::st_bbox(catchment) + c(-0.005, -0.005, 0.005, 0.005)

nhdplusTools::plot_nhdplus(bbox = bbox, cache_data = FALSE)

plot(sf::st_transform(sf::st_geometry(catchment)[1], 3857), add = TRUE, col = "red")
plot(sf::st_transform(sf::st_geometry(catchment)[2], 3857), add = TRUE, col = "black")
plot(sf::st_transform(sf::st_sfc(point, crs = 4326), 3857), add = TRUE, col = "white")

pour_point <- sf::st_sfc(sf::st_point(x = c(-89.25619, 42.98646)), crs = 4326)

(catchment <- get_split_catchment(pour_point, upstream = FALSE))

bbox <- sf::st_bbox(catchment) + c(-0.005, -0.005, 0.005, 0.005)

nhdplusTools::plot_nhdplus(bbox = bbox, cache_data = FALSE)

plot(sf::st_transform(sf::st_geometry(catchment)[1], 3857), add = TRUE, col = "red")
plot(sf::st_transform(sf::st_geometry(catchment)[2], 3857), add = TRUE, col = "black")
plot(sf::st_transform(sf::st_sfc(pour_point, crs = 4326), 3857), add = TRUE, col = "white")
}
#> Spherical geometry (s2) switched off
#> although coordinates are longitude/latitude, st_intersects assumes that they
#> are planar
#> Spherical geometry (s2) switched on
#> Zoom set to: 10

#> Spherical geometry (s2) switched off
#> although coordinates are longitude/latitude, st_intersects assumes that they
#> are planar
#> Spherical geometry (s2) switched on
#> Zoom set to: 12

#> Spherical geometry (s2) switched off
#> although coordinates are longitude/latitude, st_intersects assumes that they
#> are planar
#> Spherical geometry (s2) switched on
#> Zoom set to: 12

# }