Skip to contents

Reconcile divides to refactored flowlines (CRS-aware, lr-capable)

Source: R/reconcile_divides.R
reconcile_divides.Rd

Raster-aware divide reconciliation with two key properties:

(1) CRS from rasters: all metric spatial operations (gap fill, area calculations, MULTIPOLYGON cleanup) use the native CRS of the FDR raster instead of a hardcoded EPSG:5070. Required for datasets outside CONUS (e.g. PRVI, Alaska).

(2) lr flag: when lr = TRUE, each reconciled divide polygon is further split left/right along its associated flowline using lwgeom::st_split, matching the reference split_catchment_divide(lr = TRUE) approach. Output flowpath_id values are suffixed "_L" and "_R".

Usage

reconcile_divides(
  flowline,
  divides,
  fdr_path,
  fac_path,
  fallback_fdr_path = NULL,
  fallback_fac_path = NULL,
  lookup_table = NULL,
  lr = FALSE,
  lr_densify_m = 100,
  lr_snap_thresh_m = 100,
  parallel = TRUE,
  num_workers = NULL
)

Arguments

flowline

sf LINESTRING. Refactored flowlines with flowpath_id and flowpath_toid columns. Typically out$refactored from refactor_flowlines().

divides

sf POLYGON. Input divide polygons with flowpath_id.

fdr_path

Character. Path to D8 flow-direction raster (required).

fac_path

Character. Path to flow-accumulation raster (required).

fallback_fdr_path, fallback_fac_path

Optional paths to fallback FDR / FAC rasters, used when the primary rasters return NoData at a split point. NULL disables the fallback (default); ignored when equal to the primary paths.

lookup_table

The out$reconciled sf from refactor_flowlines(), or NULL. When provided (must have ID and member_flowpath_id columns) it is used for reconciled-aware deduplication before splitting.

lr

Logical. If TRUE, apply left/right bank split along the flowline after D8 reconciliation. Requires lwgeom. Default FALSE.

lr_densify_m

Numeric. dfMaxLength for st_segmentize when densifying divide boundary before lr split. Default 100. Units match raster CRS.

lr_snap_thresh_m

Numeric. Distance threshold (raster CRS units) for snapping flowline endpoints to divide boundary. Default 100.

parallel

Logical. Enable parallel multi-parent divide splitting. Default TRUE.

num_workers

Integer or NULL. Parallel workers. NULL uses 4.

Value

sf POLYGON with columns divide_id, flowpath_id, and geometry. When lr = TRUE, flowpath_id values are suffixed "_L" / "_R".

See also

refactor_flowlines()

Examples

if (FALSE) { # \dontrun{
out <- refactor_flowlines(flines, split_flines_meters = 2000,
                          collapse_flines_meters = 1000,
                          out_refactored = "refactored.gpkg",
                          out_reconciled = "reconciled.gpkg")
rec_div <- reconcile_divides(flowline      = out$refactored,
                             divides       = divides_sf,
                             fdr_path      = "fdr.tif",
                             fac_path      = "fac.tif",
                             lookup_table  = out$reconciled)
} # }