Download a subset of the NHDPlus v2.1 flowlines that covers a list of detection sites.
queryFlowlines(
sites_sf = NULL,
root_site_code = NULL,
min_strm_order = 0,
max_upstream_comid = NULL,
combine_up_down = TRUE
)An `sf` class object containing points of all detection sites. Must contain a column named `site_code` containing the site code of each site.
Site code for the starting detection site.
minimum stream order to query flowlines for. Default value is `0`.
if provided, this function will filter out any flowlines upstream of this unique identifier (COMID) in the NHDPlus stream network. Default value is `NULL`. For assistance identifying a COMID, please see the `nhdplusTools` package, specifically the `discover_nhdplus_id()` function.
Should the flowlines upstream and downstream of the starting point (`root_site_code`) be combined into a single object, or be returned as separate elements? The default value is `TRUE`
list with at least two elements: `flowlines` is the `sf` object of flowlines downloaded from NHDPlus. `basin` is the polygon representing the catchment upstream of the root site. If `combine_up_down` is `FALSE`, there is a third element in the list, called `dwn_flowlines`, containing an `sf` object of flowlines downstream of the root site.