Get Waterbody Polygons Upstream or Downstream of a Network Position

Returns lake or wetland polygons upstream or downstream of a given blue line key and downstream route measure. Polygon tables (fwa_lakes_poly, fwa_wetlands_poly) have NULL localcode_ltree, so fwa_upstream() / fwa_downstream() can't query them directly. This function bridges through the stream network: it runs the traversal on stream segments (which have localcode_ltree), extracts distinct waterbody_key values, then joins to the polygon table.

Usage

frs_waterbody_network(
  conn,
  blue_line_key,
  downstream_route_measure,
  table = "whse_basemapping.fwa_lakes_poly",
  cols = c("waterbody_key", "waterbody_type", "gnis_name_1", "area_ha", "blue_line_key",
    "watershed_group_code", "geom"),
  direction = "upstream"
)

Arguments

conn: A DBI::DBIConnection object (from frs_db_conn()).
blue_line_key: Integer. Blue line key of the reference point.
downstream_route_measure: Numeric. Downstream route measure of the reference point.
table: Character. Fully qualified polygon table name. Default "whse_basemapping.fwa_lakes_poly".
cols: Character vector of column names to select from the polygon table. Default includes the most commonly used attributes.
direction: Character. "upstream" (default) or "downstream".

Value

An sf data frame of waterbody polygons.

Details

See fresh#8 for background.

Examples

if (FALSE) { # \dontrun{
conn <- frs_db_conn()

# Upstream lakes from the Neexdzii Kwa / Wedzin Kwa confluence
lakes <- frs_waterbody_network(conn,
  blue_line_key = 360873822,
  downstream_route_measure = 166030
)

# Upstream wetlands
wetlands <- frs_waterbody_network(conn,
  blue_line_key = 360873822,
  downstream_route_measure = 166030,
  table = "whse_basemapping.fwa_wetlands_poly"
)
DBI::dbDisconnect(conn)
} # }