CLI reference: lsdtt-channel-extraction

Extracts a channel network from a DEM using D8 flow routing and either threshold-based or Wiener-based source extraction. Outputs the network as points, polylines, junctions, or a flow-direction raster. Optionally burns a user-supplied vector channel network into the DEM and writes elevation profiles.

Usage

lsdtt-channel-extraction  <path> <parameter_file>
lsdtt-channel-extraction  <parameter_file>        # path defaults to ./
lsdtt-channel-extraction  -h                      # print help and exit
lsdtt-channel-extraction  -v                      # print version and exit
lsdtt-channel-extraction  -c                      # print citation and exit

Parameter file format

# Lines beginning with # are comments.
key: value

Keys use snake_case. All keys and their defaults are listed below.

Multipart lines

stream_vector_path accepts multipart geometry (MultiLineString and friends). Each feature is split into its parts on read, with the attributes copied onto each, and the split is reported in the log.

Shapefiles are the commonest source of multipart data, and versions before August 2026 discarded it silently — see Vector data.

Pipeline overview

Steps run in this order:

Step	Description
1. Pit filling	Optional; always recommended unless DEM is pre-filled
2. D8 flow routing	Build the D8 flow-info object
3. Source extraction	Find channel heads using `source_extraction_algorithm_choice` (`threshold` or `wiener`)
4. Junction network	Build compact channel link and junction objects
5. Outputs	Write selected outputs

Input / output parameters

Parameter	Type	Default	Description
`read_path`	string	directory of parameter file	Directory containing the input DEM.
`read_fname`	string	parameter file stem	Input DEM filename (with or without extension). Any GDAL-supported format.
`write_path`	string	same as `read_path`	Directory for output files.
`write_fname`	string	same as `read_fname`	Output filename stem.

Threading

Parameter	Type	Default	Description
`n_threads`	int	`0`	Number of OpenMP threads. `0` = all available hardware threads. Applies to pit filling and flow-routing construction.
`boundary_conditions`	string	`oooo`	Four-character boundary condition string (N, E, S, W). `o` = open, `n` = no-flux, `p` = periodic, `b` = forced outlet.

DEM preparation

Parameter	Type	Default	Description
`raster_is_filled`	bool	`false`	Set `true` if the DEM is already pit-filled and ready for routing. If `false`, `fill_pits()` is called automatically.
`fill_min_slope`	float	`0.0001`	Minimum slope (m/m) imposed during pit filling. Used only when `raster_is_filled` is `false`.

Source extraction

Parameter	Type	Default	Description
`source_extraction_algorithm_choice`	string	`threshold`	Source extraction method. Allowed values: `threshold`, `wiener`.
`threshold_contributing_pixels`	int	`1000`	Contributing-pixel count required to define a channel head. Reduce to extract a denser network.

Wiener parameters

Used only when source_extraction_algorithm_choice: wiener.

Parameter	Type	Default	Description
`wiener_pruning_drainage_area_m2`	float	`1000.0`	Minimum drainage area for Wiener channel-mask pruning, in physical square metres (m^2).
`wiener_surface_fitting_radius_metres`	float	`6.0`	Radius (metres) used when fitting surfaces for tangential-curvature estimation.
`wiener_connected_components_threshold_pixels`	int	`100`	Minimum connected-component size (pixels) retained in the Wiener channel mask before skeletonisation.

Wiener diagnostics (optional)

All diagnostics are opt-in and do not alter source extraction output.

Parameter	Type	Default	Description
`write_wiener_filtered_dem_raster`	bool	`false`	Write Wiener-filtered DEM raster as `<write_fname>_wiener_filtered_dem.*`.
`write_wiener_tangential_curvature_raster`	bool	`false`	Write tangential-curvature raster as `<write_fname>_wiener_tangential_curvature.*`.
`wiener_write_qq_table`	bool	`false`	Write QQ diagnostics table CSV.
`wiener_diagnostics_write_output_format`	string	`same_as_input`	Raster-format override for Wiener diagnostics (`cog`, `gtiff`, `same_as_input`, `png`).
`wiener_qq_output_csv`	string	(empty)	Explicit QQ CSV path. If empty and `wiener_write_qq_table` is true, output defaults to `<write_fname>_wiener_qq.csv`.

Output: general

Parameter	Type	Default	Description
`calculate_spatial_index`	bool	`true`	Build a spatial index for vector outputs. Speeds up GIS spatial queries but requires all features to be buffered in memory before writing. Disable for large datasets.

Output: channel network points

One point per channel pixel, with drainage area as an attribute.

Parameter	Type	Default	Description
`write_channel_network_points`	bool	`false`	Write the channel network as a point layer (one feature per channel pixel).
`channel_network_points_write_vector_format`	string	`same_as_write_vector_format`	Point-output override. `csv`: latitude/longitude in EPSG:4326. `gpkg`: GeoPackage. `flatgeobuf` / `fgb`: FlatGeobuf.

Longitudinal profiles come from the POINTS, not the lines

Each channel point carries flow_distance (distance to the outlet along the routed flow path, in metres) and elevation. Plot one against the other for a longitudinal profile.

Do not derive distance from the line geometry. flow_distance is accumulated from the D8 direction code — one cell size per cardinal step, cell_size × √2 per diagonal — so it is correct on a periodic domain and is unaffected by how the lines are packaged or split. See Vector data.

Output file: <write_fname>_channel_network.<ext>

Output: channel network lines

One polyline per channel link (source-to-junction or junction-to-junction). Smaller file than the point layer; does not record per-pixel drainage area.

Parameter	Type	Default	Description
`write_channel_network_lines`	bool	`false`	Optional channel-network polyline export; off because channel-extraction vector products are opt-in.
`write_vector_format`	string	`flatgeobuf`	Baseline channel-line format. `flatgeobuf` / `fgb` or `gpkg`; CSV is not supported for lines.

Output file: <write_fname>_channel_network_lines.<ext>

The lines are MultiLineString

Channel links are written as MultiLineString, uniformly. An ordinary link is a single-part one whose coordinates are exactly what a LineString would have carried. A link that crosses a periodic boundary (available in lsdtt-lem) is split at the wrap, so no renderer draws a line across the whole domain. link_length is measured along the flow path, so it is correct in either case. See Vector data.

Output: junctions

Parameter	Type	Default	Description
`write_channel_network_junctions`	bool	`false`	Write junction points with attributes `junction_number`, `receiver_junction`, and `stream_order`.
`channel_network_junctions_write_vector_format`	string	`same_as_write_vector_format`	Junction-point override: `csv`, `gpkg`, `flatgeobuf` / `fgb`.

Output file: <write_fname>_junctions.<ext>

Output: D8 flow lines

Parameter	Type	Default	Description
`write_flow_lines`	bool	`false`	Write one line from each valid pixel centre to its D8 receiver.
`flow_lines_write_vector_format`	string	`same_as_write_vector_format`	Flow-line override. `flatgeobuf` / `fgb`, `gpkg`. CSV is not supported.

Output file: <write_fname>_flow_lines.<ext>

Output: ArcMap D8 flow direction raster

Parameter	Type	Default	Description
`write_arcmap_d8_flowdirection_raster`	bool	`false`	Write a D8 flow-direction raster using ArcMap encoding: E=1, SE=2, S=4, SW=8, W=16, NW=32, N=64, NE=128. Outlet pixels are written as 0.
`write_output_format`	string	`cog`	Baseline raster format. `cog`, `gtiff`, or `same_as_input`.

Output file: <write_fname>_d8_flow_direction.<ext>

Output: burned stream profiles

Burns a user-supplied vector polyline network into the DEM and writes an elevation profile showing original and burned elevations. Only burn_in_place mode is currently implemented.

Parameter	Type	Default	Description
`write_burned_stream_profiles`	bool	`false`	Burn vector channels into DEM and write elevation profiles. Requires `stream_vector_path`.
`stream_vector_path`	string	(empty)	Path to the vector file containing polyline channel features. Must be in the same CRS as the DEM. Supported: GeoPackage, FlatGeobuf, Shapefile, and any GDAL/OGR format.
`stream_burn_mode`	string	`burn_in_place`	Burn algorithm. `burn_in_place`: samples DEM pixels beneath the input polyline and enforces monotone-decreasing elevation downstream. `snap_to_network`: not yet implemented.
`burned_stream_profiles_write_vector_format`	string	`csv`	Output format for the profile table. `csv`: plain table with one row per channel pixel. `gpkg`: GeoPackage point layer. `flatgeobuf` / `fgb`: FlatGeobuf point layer.

Output file: <write_fname>_burned_stream_profiles.<ext>

Profile columns: feature_id, flow_distance, x, y, dem_elevation, burned_elevation.

Minimal example parameter file

# lsdtt-channel-extraction parameter file
read_path:  /data/dems/
read_fname: my_dem.tif

threshold_contributing_pixels: 500
write_channel_network_lines:      true
write_channel_network_junctions:  true

Example: threshold source extraction

read_path: /data/dems/
read_fname: my_dem.tif

source_extraction_algorithm_choice: threshold
threshold_contributing_pixels: 750

write_channel_network_lines: true

Example: Wiener source extraction with diagnostics

read_path: /data/dems/
read_fname: my_dem.tif

source_extraction_algorithm_choice: wiener
wiener_pruning_drainage_area_m2: 2500.0
wiener_surface_fitting_radius_metres: 8.0
wiener_connected_components_threshold_pixels: 80

write_wiener_filtered_dem_raster: true
write_wiener_tangential_curvature_raster: true
wiener_write_qq_table: true
wiener_diagnostics_write_output_format: gtiff

write_channel_network_points: true

Parameters

This section is generated from the executable's -h json registry. Do not edit it manually.

Status: stable.

File I/O

Parameter	Type	Default	Role	Parent	Description	Guidance
`read_path`	`string`	`./`	`io`	-	Directory from which input files are read.	Defaults to the directory holding the parameter file.
`read_fname`	`string`	-	`io`	-	Input filename, with or without extension (e.g. my_dem.tif).	Read from read_path. lsdtt3 uses GDAL, so any GDAL-readable raster format works. If empty, defaults to the parameter filename stem.
`write_path`	`string`	-	`io`	-	Directory to which output files are written.	Defaults to read_path when not set.
`write_fname`	`string`	-	`io`	-	Output filename prefix (no path, no extension).	All outputs are named <write_fname>_<descriptor>.<ext>. Defaults to the stem of read_fname when not set.

Run control

Parameter	Type	Default	Role	Parent	Description	Guidance
`n_threads`	`int`	`0`	`io`	-	Number of OpenMP threads.	0 = use all available hardware threads. Applies to pit filling and flow-routing construction.
`calculate_spatial_index`	`bool`	`true`	`io`	-	Whether or not to calculate a spatial index for vector data writes.	A spatial index helps a GIS to speed up spatial queries, so it is often helpful to have a spatial index calculated. But calculating this requires the entire vector layer to sit in memory, preventing feature-by-feature writes and adding a lot of overhead. In some cases (e.g. large datasets) it may therefore be preferred to generate vectors without spatial index - these can always be calculated later on using e.g. gdal.

Flow routing

Parameter	Type	Default	Role	Parent	Description	Guidance
`boundary_conditions`	`string`	`oooo`	`param`	-	Boundary conditions for flow routing.	Four-character string for north, east, south, west. o = open, n = no-flux, p = periodic, b = forced outlet.

Pit filling

Parameter	Type	Default	Role	Parent	Description	Guidance
`raster_is_filled`	`bool`	`false`	`switch`	-	Assert that the input raster has ALREADY been pit-filled.	ASKS: has the input already been filled? Filling is REQUIRED for this analysis, so this switch does not choose whether to fill -- it only lets the tool skip filling a surface that is filled already. Setting it true for a DEM that still contains pits gives BAD routing, not different routing. Do not confuse this with fill_before_routing, which asks whether to fill at all.
`fill_min_slope`	`float`	`0.0001`	`param`	-	Minimum slope (m/m) imposed by pit filling or flat resolution.	inline_gradient (default): imposed during the Priority-Flood fill, so used only when raster_is_filled is false. barnes2014b_gradient: the minimum gradient across flats, also on a raster_is_filled input. barnes2014b_float_step: ignored.
`fill_flat_resolution_choice`	`string`	`inline_gradient`	`param`	-	How flats are made drainable: inline_gradient, barnes2014b_gradient or barnes2014b_float_step.	inline_gradient (default, unchanged): the Priority-Flood fill imposes fill_min_slope during the flood. The barnes2014b options make flow converge across flats (Barnes et al. 2014, doi:10.1016/j.cageo.2013.01.009). barnes2014b_gradient uses fill_min_slope (m/m, must be > 0) as the minimum gradient; flats are raised about 3-4x more, capped below their rims, and capped flats are reported. barnes2014b_float_step is equivalent to RichDEM ResolveFlats on float32 in its first pass: it ignores fill_min_slope and its slopes depend on elevation (of order ULP(z) / cell size). With either barnes2014b option the result is always routable: cells the first pass leaves without a lower neighbour are refilled and resolved again (up to 4 rounds), and any still left are raised by a final priority-flood pass by one float32 step each; the report gives the rounds and the cells changed after the first pass.

Channel network

Parameter	Type	Default	Role	Parent	Description	Guidance
`threshold_contributing_pixels`	`int`	`1000`	`param`	-	Contributing-pixel threshold defining a channel head.	The total number of upslope contributing pixels from the flow-routing object, not the number of direct donors to a pixel. Reduce this value to extract a denser network. This is a PIXEL COUNT and therefore depends on the grid resolution: the equivalent drainage area is threshold_contributing_pixels x cell area. Where a genuine area is wanted instead, the convention is <what>_area_threshold_m2.

Channel sources

Parameter	Type	Default	Role	Parent	Description	Guidance
`source_extraction_algorithm_choice`	`string`	`threshold`	`switch`	-	Source extraction algorithm.	Allowed values: threshold, wiener. Threshold uses threshold_contributing_pixels. Wiener uses filtered-DEM curvature, QQ thresholding, and area pruning.
`wiener_pruning_drainage_area_m2`	`float`	`1000.0`	`param`	`source_extraction_algorithm_choice`	Minimum drainage area for Wiener channel pixels (m^2).	Wiener-only parameter. Channel pixels with drainage area below this physical-area threshold are removed before skeleton endpoint extraction.
`wiener_surface_fitting_radius_metres`	`float`	`6.0`	`param`	`source_extraction_algorithm_choice`	Surface-fitting radius for Wiener tangential curvature (m).	Wiener-only parameter. Passed to local polynomial fitting used for tangential curvature computation.
`wiener_connected_components_threshold_pixels`	`int`	`100`	`param`	`source_extraction_algorithm_choice`	Minimum connected-component size in Wiener channel mask (pixels).	Wiener-only parameter. Components smaller than this are removed before skeletonisation.
`write_wiener_filtered_dem_raster`	`bool`	`false`	`param`	`source_extraction_algorithm_choice`	Write Wiener-filtered DEM diagnostic raster.	If true, writes <write_fname>_wiener_filtered_dem with the format set by wiener_diagnostics_write_output_format.
`write_wiener_tangential_curvature_raster`	`bool`	`false`	`param`	`source_extraction_algorithm_choice`	Write Wiener tangential-curvature diagnostic raster.	If true, writes <write_fname>_wiener_tangential_curvature with the format set by wiener_diagnostics_write_output_format.
`wiener_write_qq_table`	`bool`	`false`	`param`	`source_extraction_algorithm_choice`	Write Wiener QQ diagnostic table as CSV.	If true, writes QQ data to wiener_qq_output_csv, or to <write_fname>_wiener_qq.csv when that parameter is empty.
`wiener_diagnostics_write_output_format`	`string`	`same_as_input`	`param`	`source_extraction_algorithm_choice`	Raster format for Wiener diagnostic rasters.	Allowed values: cog, gtiff, same_as_input, png.
`wiener_qq_output_csv`	`string`	-	`param`	`source_extraction_algorithm_choice`	Output CSV path for Wiener QQ diagnostics.	Wiener-only parameter. If empty and wiener_write_qq_table is true, the CLI writes <write_fname>_wiener_qq.csv.

Output

Parameter	Type	Default	Role	Parent	Description	Guidance
`write_output_format`	`string`	`cog`	`io`	-	Raster output format: cog, gtiff, png or same_as_input.	cog is a Cloud Optimised GeoTIFF and is the project default. It falls back to gtiff for small rasters, where the tiling overhead is not worth it. There is ONE raster format parameter per CLI: it governs every raster the tool writes. Vector outputs are governed separately by write_vector_format.
`write_vector_format`	`string`	`flatgeobuf`	`io`	-	Vector output format: flatgeobuf or gpkg.	Governs every vector layer this tool writes. FlatGeobuf is preferred: it is compact, carries its own georeferencing, and does not have GeoPackage's problems writing across drives (a common WSL2 situation). CSV is available only through selectors for point/table outputs. Per-output overrides exist only where a container genuinely differs. Raster outputs are governed separately by write_output_format.

Channel network output

Parameter	Type	Default	Role	Parent	Description	Guidance
`write_channel_network_points`	`bool`	`false`	`switch`	-	Write the channel network as point data, where each channel pixel is a feature with attribute values, such as drainage_area.	Compared to write_channel_network_lines, this write will be larger because there are more features, but it does record the drainage area at each channel pixel.
`channel_network_points_write_vector_format`	`string`	`same_as_write_vector_format`	`param`	`write_channel_network_points`	Output format for the exported channel network.	csv: writes latitude/longitude point rows in EPSG:4326. gpkg: writes a GeoPackage in the raster CRS. flatgeobuf or fgb: writes FlatGeobuf in the raster CRS.
`write_channel_network_lines`	`bool`	`false`	`switch`	-	Write the channel network as vector lines, where each channel link (defined between source or upstream junction and outlet or downstream junction) is a feature.	Does not support csv writes, only gpkg and flatgeobuf/fgb. It is off by default because channel-extraction vector products are opt-in. Compared to write_channel_network as points, the lines filesize will be smaller (there are fewer features), at the cost of not recording drainage area at each channel pixel.
`write_channel_network_junctions`	`bool`	`false`	`switch`	-	Write the channel network junctions as point data	Contains feature attributes: junction_number, receiver_junctionand stream_order
`channel_network_junctions_write_vector_format`	`string`	`same_as_write_vector_format`	`param`	`write_channel_network_junctions`	Output format for the exported channel network.	csv: writes latitude/longitude point rows in EPSG:4326. gpkg: writes a GeoPackage in the raster CRS. flatgeobuf or fgb: writes FlatGeobuf in the raster CRS.

Channel slopes

Parameter	Type	Default	Role	Parent	Description	Guidance
`write_channel_slope_points`	`bool`	`false`	`switch`	-	Write every channel cell with its along-channel gradient and smoothed elevation.	A channel cell has at least threshold_contributing_pixels contributing pixels. Each point carries flat, drainage_area_m2, flow_distance_m (to the outlet along D8), elevation_m (the pit-filled DEM), smoothed_elevation_m and slope_m_per_m (the least-squares line of elevation against along-channel distance over +/- slope_window_half_length_metres: its value at the cell, and its gradient), slope_valid and slope_window_length_m (the span used). Output: <write_fname>_channel_slope_points.<ext>. lsdviztools3 lsdviz3-channel-slopes plots it (profiles, slope against distance and drainage area, map).
`slope_window_half_length_metres`	`float`	`25.0`	`param`	-	Half-length of the along-channel slope-fit window [m].	Slope is the least-squares slope of pit-filled elevation against along-channel distance over +/- this distance (the window spans twice it), so it has no cross-channel component; the fitted line's value at the cell is the smoothed elevation. Upstream the window follows the tributary with the largest drainage area. Must be at least two cell sizes; use roughly 5-10 channel widths. Near the source or outlet a one-sided window is accepted only if the valid cells span at least this distance, otherwise slope_valid is 0.
`channel_slope_points_write_vector_format`	`string`	`same_as_write_vector_format`	`param`	`write_channel_slope_points`	Output format for the channel slope points.	csv: writes latitude/longitude point rows in EPSG:4326. gpkg: writes a GeoPackage in the raster CRS. flatgeobuf or fgb: writes FlatGeobuf in the raster CRS.

Channel point attributes

Parameter	Type	Default	Role	Parent	Description	Guidance
`run_channel_point_attributes`	`bool`	`false`	`switch`	-	Snap points (e.g. field sites) to the nearest channel cell and add drainage area and along-channel slope.	Reads channel_points_fname with all its attributes. Each point moves to the channel cell (>= threshold_contributing_pixels) whose centre is nearest in straight-line distance, within channel_points_snap_max_search_radius_pixels; it does not follow the D8 path. Added fields: original_x, original_y (raster CRS), snap_distance_m, snap_status, snapped_flat, contributing_pixels, drainage_area_m2, flow_distance_m, elevation_m (pit-filled DEM), smoothed_elevation_m, slope_m_per_m, slope_valid, slope_window_length_m (slope as for write_channel_slope_points, over +/- slope_window_half_length_metres). An added field whose name is already in the input gets the suffix _lsdtt. The geometry is the snapped cell centre; a point that did not snap keeps its own position with empty added values. Output: <write_fname>_channel_points.<ext>; lsdviztools3 lsdviz3-channel-slopes --field-points overlays it on the channel profiles.
`channel_points_fname`	`string`	-	`param`	`run_channel_point_attributes`	Point file to snap: csv with latitude/longitude (WGS84), or any OGR point layer.	Relative to read_path unless absolute. csv needs latitude and longitude columns (or easting/northing in the raster CRS); fgb, gpkg, shp and geojson are read through OGR and reprojected to the raster CRS. Every attribute is kept.
`channel_points_layer`	`string`	-	`param`	`run_channel_point_attributes`	Layer of channel_points_fname to read (empty: the first).	Only for multi-layer inputs such as GeoPackage.
`channel_points_snap_max_search_radius_pixels`	`int`	`10`	`param`	`run_channel_point_attributes`	Furthest a point may move to a channel cell, in pixels (Chebyshev rings).	A point with no channel cell within this many pixels keeps its position, with snap_status threshold_not_found_in_search_window.
`channel_points_write_vector_format`	`string`	`same_as_write_vector_format`	`param`	`run_channel_point_attributes`	Output format for the snapped channel points.	csv: writes latitude/longitude point rows in EPSG:4326. gpkg: writes a GeoPackage in the raster CRS. flatgeobuf or fgb: writes FlatGeobuf in the raster CRS.

Flow routing output

Parameter	Type	Default	Role	Parent	Description	Guidance
`write_flow_lines`	`bool`	`false`	`switch`	-	Write D8 receiver links as a vector line layer.	Writes one line from each valid donor pixel centre to its receiver pixel centre, following the D8 directions.
`flow_lines_write_vector_format`	`string`	`same_as_write_vector_format`	`param`	`write_flow_lines`	Output format for D8 flow-line visualisation.	Allowed values: flatgeobuf, fgb, gpkg. FlatGeobuf is the default. GeoPackage may have file I/O issues on some filesystems.
`write_drainage_area_raster`	`bool`	`false`	`switch`	-	Write the D8 drainage-area raster.	Contributing area at every pixel, from the same flow routing used for channel extraction. Pair it with write_distance_to_farthest_ridge_raster for the length-area (Hack) scaling, or use it to weight channel lines by discharge. Output: <write_fname>_drainage_area.
`write_distance_to_farthest_ridge_raster`	`bool`	`false`	`switch`	-	Write the D8 flow-path length from the farthest upslope headwater to each pixel.	This is the L of Hack's law (L ~ A^h); pair it with the drainage-area raster to get the length-area scaling of the network. Headwater pixels are 0. Output: <write_fname>_distance_to_farthest_ridge.
`write_arcmap_d8_flowdirection_raster`	`bool`	`false`	`switch`	-	Write a D8 flow-direction raster using ArcMap conventions.	ArcMap D8 codes are used: E=1, SE=2, S=4, SW=8, W=16, NW=32, N=64, NE=128. Outlet pixels are written as 0.

Stream burning

Parameter	Type	Default	Role	Parent	Description	Guidance
`write_burned_stream_profiles`	`bool`	`false`	`switch`	-	Burn a user-supplied vector polyline into the DEM and write an elevation profile showing original and burned elevations.	Requires stream_vector_path to be set. The routine finds pixels beneath each polyline feature, builds a flow-distance/elevation profile, and enforces a downhill-flow constraint on the burned elevation. Output columns: feature_id, flow_distance, x, y, dem_elevation, burned_elevation.
`stream_vector_path`	`string`	-	`param`	`write_burned_stream_profiles`	Path to the input vector file containing polyline channel features.	Required when write_burned_stream_profiles is true. The file must contain polyline or multilinestring geometries in the same CRS as the DEM. Supported formats: GeoPackage (.gpkg), FlatGeobuf (.fgb), Shapefile (.shp), and any other GDAL/OGR-supported format.
`stream_burn_mode`	`string`	`burn_in_place`	`param`	`write_burned_stream_profiles`	Method used to construct the burned channel profile.	burn_in_place: pixels directly beneath the input polyline are sampled from the DEM and a monotone-decreasing burned elevation is computed by linking low-lying points along the profile. snap_to_network: not yet implemented.
`burned_stream_profiles_write_vector_format`	`string`	`csv`	`param`	`write_burned_stream_profiles`	Output format for the burned stream profile table.	csv: writes a plain CSV table with one row per channel pixel. gpkg: writes a GeoPackage point layer in the raster CRS. flatgeobuf or fgb: writes a FlatGeobuf point layer in the raster CRS.

Interior nodata

Parameter	Type	Default	Role	Parent	Description	Guidance
`interior_nodata_method`	`string`	`sink`	`param`	-	How nodata pixels inside the DEM are treated: sink or fill.	Interior nodata are nodata pixels not connected to the raster edge through other nodata (isolated voids, moulins, masked lakes). sink (the default, unchanged behaviour): they are outlets, so flow that reaches them ends there, as at the DEM edge; use this for real internal drainage (e.g. moulins on an ice sheet). fill: they are interpolated with nodata_fill_method_choice before any filling or routing, so flow passes across them; use this for data voids. Nodata connected to the edge (e.g. sea removed by min_elevation) is never filled and always acts as an open boundary.
`nodata_fill_method_choice`	`string`	`laplacian`	`param`	`interior_nodata_method=fill`	Method for filling interior nodata pixels.	laplacian: smooth Dirichlet interpolation (recommended). iterative_weighted_average: fast, well-suited to thin voids. Used when interior_nodata_method is fill.
`nodata_fill_max_iter`	`int`	`10000`	`param`	`interior_nodata_method=fill`	Maximum iterations for iterative nodata fill methods.	Used when interior_nodata_method is fill.

Perimeter sources

Parameter	Type	Default	Role	Parent	Description	Guidance
`run_perimeter_sources`	`bool`	`false`	`switch`	-	Find channel sources where valleys enter the DEM across its edge.	Traces the outer edge of the valid data, finds wide, gentle, low runs along it (valley crossings), selects the n_perimeter_outlets outlet runs with the largest summed drainage area, and keeps as sources the crossings whose flow goes into the DEM, stays gentle for perimeter_inward_check_distance_metres and reaches a selected outlet. The sources file can be passed to the surface CLIs as source_points_fname. Requires boundary_conditions: oooo. Interior nodata holes are not traced.
`n_perimeter_outlets`	`int`	`1`	`param`	`run_perimeter_sources`	Number of outlet runs kept, largest summed drainage area first.	Outlet cells inside one low-spot gentle run are summed (a wide floodplain leaves through many parallel D8 outlets); every other outlet cell is its own run. The run summary gives the ratio of the n-th to the (n+1)-th area, to show near-ties.
`perimeter_min_valley_width_metres`	`float`	`300`	`param`	`run_perimeter_sources`	Minimum length of a gentle perimeter run for a valley crossing (m).	Set for 30 m global DEMs, where 300 m is 10 cells. Lower it for better data: on 1 m lidar, valleys of about 100 m are resolved.
`perimeter_max_gradient`	`float`	`0.05`	`param`	`run_perimeter_sources`	Gradient (m/m) below which a perimeter cell is gentle.	Gradient from a least-squares plane through the valid cells within perimeter_gradient_radius_metres.
`perimeter_gradient_radius_metres`	`float`	`-1`	`param`	`run_perimeter_sources`	Radius (m) of the plane fit giving the perimeter gradient.	Negative = max(5 cells, 10 m). Only valid cells are fitted, so a window cut by nodata still gives a gradient.
`perimeter_gap_closing_metres`	`float`	`-1`	`param`	`run_perimeter_sources`	Steep gaps up to this length (m) inside a gentle run are absorbed.	Negative = max(2 cells, 20 m); 0 = off. A valley floor holds its channel, whose banks are steep for a few metres on lidar; without this the floor splits at the channel.
`perimeter_min_relief_metres`	`float`	`5`	`param`	`run_perimeter_sources`	Low-spot test: rise (m) required on both sides of a crossing.	Measured from the run's lowest cell to the highest perimeter cell within max(run width, perimeter_min_valley_width_metres) beyond each end. Rejects gentle shoulders on side slopes.
`perimeter_inward_check_distance_metres`	`float`	`500`	`param`	`run_perimeter_sources`	Flow-path length (m) checked inward from a crossing.	A crossing whose path steepens beyond perimeter_inward_max_gradient within this distance is a flat divide or shoulder, not a valley.
`perimeter_inward_max_gradient`	`float`	`0.1`	`param`	`run_perimeter_sources`	Maximum flow-path gradient (m/m) on the inward check.	Measured as drop over path length across perimeter_inward_gradient_window_metres, on the routed DEM.
`perimeter_inward_gradient_window_metres`	`float`	`-1`	`param`	`run_perimeter_sources`	Path length (m) over which the inward gradient is measured.	Negative = max(5 cells, 25 m).
`perimeter_min_source_path_metres`	`float`	`-1`	`param`	`run_perimeter_sources`	Minimum flow-path length (m) from a source to its outlet.	Negative = 2 x perimeter_min_valley_width_metres. Guards against a gentle strip beside an outlet that drains along the edge into it.
`perimeter_trim_pixels`	`int`	`0`	`param`	`run_perimeter_sources`	Erode the valid region by this many cells before tracing.	Reprojected DEMs carry interpolated values along their nodata edges; trimming moves the traced perimeter onto clean data. Trimmed cells still take part in flow routing.
`write_perimeter_sources`	`bool`	`true`	`switch`	`run_perimeter_sources`	Write the perimeter sources (points).	Output: <write_fname>_perimeter_sources.<fgb\|gpkg>. Fields: source_id, outlet_id, row, col, elevation, crossing_width_m, crossing_relief_m, path_length_to_outlet_m, drop_to_outlet_m.
`write_perimeter_outlets`	`bool`	`true`	`switch`	`run_perimeter_sources`	Write the perimeter outlet runs (points at each run's largest-area cell).	Output: <write_fname>_perimeter_outlets.<fgb\|gpkg>. Fields: outlet_id, rank, summed_drainage_area_m2, n_cells, width_m, on_crossing, selected.
`write_perimeter_crossings`	`bool`	`true`	`switch`	`run_perimeter_sources`	Write every gentle perimeter run with its verdict (lines).	Output: <write_fname>_perimeter_crossings.<fgb\|gpkg>. Verdicts: source, outlet_crossing, failed_inward, drains_elsewhere, too_close_to_outlet, not_low_spot, too_narrow. A missed valley shows up here with the reason.
`write_perimeter_profile`	`bool`	`true`	`switch`	`run_perimeter_sources`	Write the perimeter profile as CSV.	Output: <write_fname>_perimeter_profile.csv, one row per trace step: visit, s_m, row, col, x, y, elevation, gradient, gentle, run_id, outlet_cell, outlet_run_id, repeated_visit.