r.watershed
How GRASS runs Flow Accumulation: r.watershed.
| Engine | GRASS |
|---|---|
| Tool name | r.watershed |
| Interface | cli |
| Implements | Flow Accumulation |
| Preset | {"flag_s":true,"flag_a":true} |
| Documentation | Not stated |
| Effects | modifies input: no, network: no |
| Notes | Not stated |
| Status | active |
Parameters
| Name | Type | Required | Default | Choices | Note |
|---|---|---|---|---|---|
elevation | string | yes | Not stated | Not stated | cell name |
depression | string | no | Not stated | Not stated | cell name |
flow | string | no | Not stated | Not stated | cell name |
disturbed_land | string | no | Not stated | Not stated | cell name |
blocking | string | no | Not stated | Not stated | cell name |
retention | string | no | Not stated | Not stated | cell name |
threshold | integer | no | Not stated | Not stated | Not stated |
max_slope_length | float | no | Not stated | Not stated | Not stated |
accumulation | string | no | Not stated | Not stated | output cell |
tci | string | no | Not stated | Not stated | output cell |
spi | string | no | Not stated | Not stated | output cell |
drainage | string | no | Not stated | Not stated | output cell |
basin | string | no | Not stated | Not stated | output cell |
stream | string | no | Not stated | Not stated | output cell |
half_basin | string | no | Not stated | Not stated | output cell |
length_slope | string | no | Not stated | Not stated | output cell |
slope_steepness | string | no | Not stated | Not stated | output cell |
convergence | integer | no | 5 | Not stated | Not stated |
memory | integer | no | 300 | Not stated | Not stated |
flag_s | boolean | no | Not stated | Not stated | flag -s |
flag_4 | boolean | no | Not stated | Not stated | flag -4 |
flag_m | boolean | no | Not stated | Not stated | flag -m |
flag_a | boolean | no | Not stated | Not stated | flag -a |
flag_b | boolean | no | Not stated | Not stated | flag -b |
flag_overwrite | boolean | no | Not stated | Not stated | flag --overwrite |
How it maps to the operation
| Operation parameter | Parameter here | Note |
|---|---|---|
raster | elevation | Not stated |
output | accumulation | Not stated |
Differences from the operation
- Multiple flow direction by default; this mapping sets the s flag (single, D8). Also writes basins, streams and other maps when named.
- Without the a flag, cells that may receive flow from outside the region get negative counts (on a plane draining to one edge, every cell); this mapping sets it.
- Cells on the region's border drain straight out of it, so they do not feed their neighbours (on a 20 by 20 plane draining west, the top and bottom rows and the east column were all 1, interior rows counted 19 down to 1).
Harvested by the grass harvester from engine version
8.5.0. Names can change when an engine is harvested again.