Hi,
I’m using GTOPO30 DEM data and TRMM (rainfall) data, I selected the data for the whole of africa but I’m getting an error when executing v.rast.stats.
Here is a step-by-step of what I did:
- GTOPO30 DEM
- downloaded e020n10,w020s10,e020n40,w020n40 compressed files from “ftp://edcftp.cr.usgs.gov/pub/data/gtopo30/global/”.
- decompressed all the above files.
- Added “PIXELTYPE SIGNEDINT” in all .HDR files
- warp merged all the .DEM file with “gdalwarp *.DEM Africa.tif” command.
- projected it with “gdal_translate -a_srs EPSG:4326 Africa.tif DEM.tif”
- TRMM “rainfall” data
- downloaded 3B42RT.2010061503.1day.tif,3B42RT.2010061503.1day.tfw from “”.
- projected it with "gdal_translate -a_srs EPSG:4326 -projwin -20 40 60 -60 3B42RT.2010061503.1day.tif TRMM.tif ".
Then, imported the two data sets:
r.in.gdal in=/home/tgumede1/grassdem/ict4eo/DEM.tif out=dem
Projection of input dataset and current location appear to match
100%
r.in.gdal complete. Raster map created.
g.region rast=dem
r.in.gdal in=/home/tgumede1/grassdem/ict4eo/CapeTown_TRMMs.tif out=rainfall target=CapeTown
Projection of input dataset and current location appear to match
100%
r.in.gdal complete. Raster map created.
r.watershed elevation=dem accumulation=acc drainage=direction stream=str basin=catch memory=300 threshold=100000
SECTION 1a (of 5): Initiating Memory.
SECTION 1b (of 5): Determining Offmap Flow.
100%
SECTION 2: A * Search.
100%
SECTION 3: Accumulating Surface Flow.
100%
SECTION 4: Watershed determination.
100%
SECTION 5: Closing Maps.
100%
Q: How do one really know the exact threshold value?
r.to.vect in=catch out=catchments feature=area
Extracting areas…
100%
100%
Building topology for vector map …
Registering primitives…
134246 primitives registered
701002 vertices registered
Building areas…
100%
44645 areas built
1 isles built
Attaching islands…
100%
Attaching centroids…
100%
Number of nodes: 89602
Number of primitives: 134246
Number of points: 0
Number of lines: 0
Number of boundaries: 89604
Number of centroids: 44642
Number of areas: 44645
Number of isles: 1
Number of areas without centroid: 3
r.to.vect complete.
g.region rast=rainfall
v.rast.stats vector=catchments raster=rainfall colprefix=precip
WARNING: Area without centroid (may be OK for island)
WARNING: Area without centroid (may be OK for island)
WARNING: Area without centroid (may be OK for island)
DBMI-DBF driver error:
SQL parser error: syntax error, unexpected NULL_VALUE processing ‘NULL’
in statement:
UPDATE catchments SET precip_cf_=-NULL WHERE cat=17
Error in db_execute_immediate()
ERROR: Error while executing: ‘UPDATE catchments SET precip_cf_=-NULL WHERE
cat=17’
- output of r.info -g
r.info -g rainfall
north=40
south=-60
east=60
west=-20
- output of v.info
v.info -g catchments
north=40
south=-60
east=60
west=-20
top=0.000000
bottom=0.000000
output of r.info
Type of Map: raster Number of Categories: 2559
Data Type: CELL
Rows: 400
Columns: 320
Total Cells: 128000
Projection: Latitude-Longitude
N: 40N S: 60S Res: 0:15
E: 60E W: 20W Res: 0:15
Range of data: min = 0 max = 2559
Data Description:
generated by r.in.gdal
Comments:
r.in.gdal input=“/home/tgumede1/grassdem/ict4eo/CapeTown_TRMMs.tif”
output=“rainfall” target=“CapeTown”
- output of r.univar
r.univar rainfall
100%
total null and non-null cells: 115200000
total null cells: 0
Of the non-null cells:
n: 115200000
minimum: 0
maximum: 2559
range: 2559
mean: 22.4897
mean of absolute values: 22.4897
standard deviation: 83.1312
variance: 6910.79
variation coefficient: 369.642 %
sum: 2590809300
–
Kind Regards
TS Gumede
CSIR, Meraka Institute
072 258 1650