[GRASS-dev] [GRASS GIS] #1924: r.watershed - empty stream segment map

[GRASS GIS]

#1924: r.watershed - empty stream segment map
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 Reporter:  jradinger  |       Owner:  grass-dev@…              
     Type:  defect     |      Status:  new                      
 Priority:  normal     |   Milestone:                           
Component:  Raster     |     Version:  svn-trunk                
 Keywords:             |    Platform:  Linux                    
      Cpu:  x86-32     |  
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 I am running GRASS 7 SVN (Rev55666, last revision of r.watershed) and face
 following two problems with r.watershed:

 1) When running with treshhold = 2 I don't get any errors (one warning,
 see below), a flow direction map is produced correctly but the '''stream-
 segments map is empty'''.
 This was (and is still if nothing has changed since one week) in GRASS
 6.5.
 Here the debug output:


 {{{
 r.watershed --overwrite elevation=distance_raster_tmp_27369 at Fidimo_test
 threshold=2 drainage=flow_direction_test stream=segments_test
 D1/1: Mode: All in RAM
 SECTION 1a (of 5): Initiating Memory.
 D1/1: G_find_raster2(): name=distance_raster_tmp_27369
 mapset=Fidimo_test
 D1/1: G_find_raster2(): name=distance_raster_tmp_27369
 mapset=Fidimo_test
 D1/1: G_find_raster2(): name=distance_raster_tmp_27369
 mapset=Fidimo_test
 D1/1: G_find_raster2(): name=distance_raster_tmp_27369
 mapset=Fidimo_test
 D1/1: G_find_raster2(): name=distance_raster_tmp_27369
 mapset=Fidimo_test
 D1/1: G_find_raster2(): name=distance_raster_tmp_27369
 mapset=Fidimo_test
 D1/1: G_find_raster2(): name=distance_raster_tmp_27369
 mapset=Fidimo_test
 D1/1: G_find_raster2(): name=distance_raster_tmp_27369
 mapset=Fidimo_test
 D1/1: G_find_raster(): name=MASK mapset=Fidimo_test
 SECTION 1b (of 5): Determining Offmap Flow.
 SECTION 2: A* Search.
 SECTION 3a: Accumulating Surface Flow with MFD.
 D1/1: MFD convergence factor set to 5.
 D1/1: ns contour: 41.4214
 D1/1: ew contour: 41.4214
 D1/1: diag contour: 41.4214
 SECTION 3b: Adjusting drainage directions.
 SECTION 4: Watershed determination.
 SECTION 5: Closing Maps.
 D1/1: 0 basins created
 WARNING: No basins were created. Verify threshold and region settings.
 D1/1: Too many subbasins to reasonably check for color
 brightness
 D1/1: close segments_test compressed
 D1/1: G_find_raster2(): name=segments_test
 mapset=Fidimo_test
 D1/1: G_find_raster2(): name=segments_test
 mapset=Fidimo_test
 D1/1: close flow_direction_test compressed
 D1/1: G_find_raster2(): name=flow_direction_test
 mapset=Fidimo_test
 D1/1: G_find_raster2(): name=flow_direction_test
 mapset=Fidimo_test
 (Wed Apr 10 09:55:17 2013) Command finished (0 sec)
 }}}


 What does the warning mean? My region settings:

 {{{
 g.region -p
 projection: 1 (UTM)
 zone:       13
 datum:      nad27
 ellipsoid:  clark66
 north:      4928000
 south:      4914000
 west:       590000
 east:       609000
 nsres:      100
 ewres:      100
 rows:       140
 cols:       190
 cells:      26600
 }}}


 2) When running with treshold = 0 (default), I get following Error:


 {{{
 r.watershed --overwrite elevation=distance_raster_tmp_27369 at Fidimo_test
 threshold=0 drainage=flow_direction_test stream=segments_test
 D1/1: Mode: All in RAM
 ERROR: USAGE for basin delineation:
 /usr/local/grass-7.0.svn/etc/r.watershed/ram -4 elevation=elevation_map
 threshold=swale_threshold [flow=overland_flow_map]
 [drainage=drain_direction_map] [depression=depression_map]
 [accumulation=accumulation_map] [basin=watershed_basin_map]
 [stream=stream_segment_map]

 USAGE for slope length determination:
 /usr/local/grass-7.0.svn/etc/r.watershed/ram [-4] elevation=elevation_map
 threshold=swale_threshold [drainage=drain_direction_map]
 [depression=depression_map] [accumulation=accumulation_map]
 [max_slope_length=max_slope_length] [blocking=overland_blocking_map]
 [slope_steepness=slope_steepness_map] length_slope=length_slope_map
 [disturbed_land=rill_erosion_map] [slope_deposition=slope_deposition value
 or map]USAGE for ARMSED FILE creation:
 /usr/local/grass-7.0.svn/etc/r.watershed/ram [-4] elevation=elevation_map
 threshold=swale_threshold [flow=overland_flow_map]
 [drainage=drain_direction_map] [depression=depression_map]
 [accumulation=accumulation_map] [basin=watershed_basin_map]
 [stream=stream_segment_map] [half_basin=half_basin_map]
 ar=ARMSED_file_name

 WARNING: Subprocess failed with exit code 1
 }}}


 I am especially interested in a solution of problem 1 to get also a
 segment map as output of r.watershed.

-- 
Ticket URL: <http://trac.osgeo.org/grass/ticket/1924>
GRASS GIS <http://grass.osgeo.org>