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Vignette: dual stream order for VCA + patch connectivity #27
Description
Vignette: dual stream order for VCA + patch cleanup
Show the pattern of using different stream orders for floodplain modelling vs connectivity checking. Short vignette with tables and interactive leaflet map.
Pipeline
# Order 4+ for VCA (clean floodplain, no headwater noise)
streams_vca <- frs_network_prune(blk, drm, stream_order_min = 4, ...)
# Order 2+ for connectivity anchor (sees tributaries connecting patches)
streams_anchor <- frs_network_prune(blk, drm, stream_order_min = 2, ...)
# Waterbodies fill lake/wetland donut holes
waterbodies <- rbind(lakes[, "geom"], wetlands[, "geom"])
# VCA with waterbodies + channel buffer
valleys <- fl_valley_confine(dem, streams_vca, ..., waterbodies = waterbodies)
# Connectivity check uses 2+ anchor
anchor_r <- fl_stream_rasterize(streams_anchor, dem, field = "upstream_area_ha")
valleys <- fl_patch_conn(valleys, anchor_r)
valleys <- fl_patch_rm(valleys, min_area = 5000)Results from Neexdzii Kwah test
| Step | Cells | Area (ha) | Dropped |
|---|---|---|---|
| VCA + waterbodies | 1,751,906 | 17,519 | — |
| fl_patch_conn (anchor 4+) | 1,282,144 | 12,821 | 4,698 ha |
| fl_patch_conn (anchor 2+) | 1,409,432 | 14,094 | 3,425 ha |
| fl_patch_rm (5000 m²) | 1,403,362 | 14,034 | 60 ha |
Anchor 2+ retains 1,268 ha more than anchor 4+ — large wetland complexes near Buck Creek/Bulkley confluence that connect via order 2-3 tributaries. Foxy Creek floodplain also retained.
Include
- Summary table (above)
- Interactive leaflet toggling old/new/anchor variants
- Link to fresh for stream/waterbody queries
- Note on ZM geometry (Default to dropping Z/M coordinates from query results fresh#30)
Discovered during NewGraphEnvironment/diggs#20
Activity