Clean Catchment Geometry — clean

Fix common geometry issues in DEM-derived catchments (disjoint fragments, artifacts, invalid topologies) and optionally apply topology- preserving simplification via mapshaper. If `flowlines` are provided, the largest part per catchment is chosen preferentially where it touches the corresponding flowline feature.

Usage

clean_geometry(
  catchments,
  flowlines = NULL,
  fl_ID = NULL,
  ID = "ID",
  keep = NULL,
  crs = 5070,
  grid = 9e-04,
  gb = 8,
  force = FALSE,
  sys = NULL
)

Arguments

catchments: sf POLYGON/MULTIPOLYGON with a unique ID column.
flowlines: optional sf LINESTRING/MULTILINESTRING for picking the "prime" part per catchment (largest piece that intersects the flowline).
fl_ID: character. Unique identifier column in `flowlines` that matches `ID` in `catchments`.
ID: character. Unique identifier column in `catchments`. Default: "ID".
keep: numeric in (0,1]. Proportion of points to retain in simplification. If `NULL`, no simplification is performed. Default: `NULL`.
crs: integer or object accepted by `sf::st_crs`. Should be a projected CRS suitable for area calculations. Default: 5070 (NAD83 / Conus Albers).
grid: numeric. Snap-to-grid size (in target CRS units). Default: 0.0009.
gb: integer. Heap GB for `mapshaper-xl` when `force = TRUE` and `gb > 8`. Default: 8.
force: logical. Use system `mapshaper` / `mapshaper-xl` binaries directly for simplification (faster and more robust on large data). Default: FALSE.
sys: logical or NULL. Use system mapshaper for rmapshaper calls. If NULL, auto-detect. Set env `TURN_OFF_SYS_MAPSHAPER=YUP` to force `FALSE`.

Value

sf with the same ID column and fixed geometry; includes `areasqkm`.

Examples

if (FALSE) { # \dontrun{
divides   <- sf::read_sf("hydrofabric.gpkg", "divides")
flowpaths <- sf::read_sf("hydrofabric.gpkg", "flowpaths")
cleaned <- clean_geometry(divides, flowlines = flowpaths,
  fl_ID = "id", ID = "divide_id", crs = 5070)
} # }