terminal_reaches: Return terminal reaches from collection intersecting lake

In nhdR: Tools for Working with the National Hydrography Dataset

Return terminal reaches from collection intersecting lake

Description

In the case of a network query, a terminal reach is a stream flowline that has no downstream reaches in-network. In the case of a point query, a terminal reach is a flowline that exits the intersecting surface waterbody.

Usage

terminal_reaches(
  lon = NA,
  lat = NA,
  buffer_dist = 0.01,
  network = NA,
  lakepoly = NA,
  lakewise = FALSE,
  lakesize_threshold = 4,
  approve_all_dl = FALSE,
  temporary = TRUE,
  ...
)

Arguments

lon	numeric decimal degree longitude. optional. See Details section.
lat	numeric decimal degree latitude. optional. See Details section.
buffer_dist	numeric buffer around lat-lon point in dec. deg.
network	sf lines collection. optional. See Details section.
lakepoly	sf polygon. optional. See Details section.
lakewise	logical. If TRUE, return the terminal reaches of all lakes in the stream network rather than a single terminal reach of the focal lake.
lakesize_threshold	numeric above which to count as a lake (ha).
approve_all_dl	logical blanket approval to download all missing data. Defaults to TRUE if session is non-interactive.
temporary	logical set FALSE to save data to a persistent rappdirs location
...	parameters passed on to sf::st_read

Details

There are multiple ways to execute terminal_reaches:

• Only providing lon + lat arguments - this will query the corresponding lake polygon layer and find the terminal reach of the lake intersecting a buffer around the specified point.

• Only providing a lake polygon - this is essentially the same as above except there is no preliminary lake polygon query.

• Only providing a network of stream lines - this provides the most downstream reach irrespective of lakes.

Value

An sf data frame with LINESTRING geometries

Examples

## Not run: 
library(sf)
library(mapview)

coords <- data.frame(lat = 46.32711, lon = -89.58893)
t_reach <- terminal_reaches(coords$lon, coords$lat)

coords <- data.frame(lat = 20.79722, lon = -156.47833)
# use a non-geographic (projected) buffer size
t_reach <- terminal_reaches(coords$lon, coords$lat,
  buffer_dist = units::as_units(5, "km"))

coords  <- data.frame(lat = 42.96628, lon = -89.25264)
t_reach <- terminal_reaches(coords$lon, coords$lat)

coords  <- data.frame(lat = 41.42217, lon = -73.24189)
t_reach <- terminal_reaches(coords$lon, coords$lat)

mapview(st_as_sf(coords, coords = c("lon", "lat"), crs = 4326)) +
  mapview(t_reach$geometry, color = "red")

coords <- data.frame(lat = 41.859080, lon = -71.575422)
network <- nhd_plus_query(lon = coords$lon, lat = coords$lat,
  dsn = "NHDFlowline", buffer_dist = 0.05)$sp$NHDFlowline
t_reach      <- terminal_reaches(network = network)
t_reach_lake <- terminal_reaches(network = network, lakewise = TRUE,
  lakesize_threshold = 1)

mapview(network) + mapview(t_reach_lake, color = "green") +
  mapview(t_reach, color = "red")

## End(Not run)

nhdR documentation built on Aug. 12, 2023, 9:06 a.m.