[GRASS-user] r.hazard.flood erroneous results.

[Rengifo Ortega]

Dear community,I gave a try to r.hazard.flood and  got  som  erroneous results, that indicate flood hazard (value 1) on  the hillsides. Is that possible?

I am running  r.flood.hazard in GRASS GIS 7.2.0 on a windows 10 machine. The DTM used has 1m resolution.
Not error messages are produced-- (below  the command output), but the  results do not represent the reality. The MTI map on the other hand, looks correct to me. Negative values on the hillside and positive values in the floodplain (see attachments).

(Fri Feb 24 07:54:22 2017)                                                      
r.hazard.flood --overwrite map=driva_sk_1m at PERMANENT flood=floodHazard mti=MTIFlood
Cellsize : 1.0
SECTION 1a (of 4): Initiating Memory.
SECTION 1b (of 4): Determining Offmap Flow.
SECTION 2: A* Search.
SECTION 3a: Accumulating Surface Flow with MFD.
SECTION 3b: Adjusting drainage directions.
SECTION 4: Closing Maps.
Writing out only positive flow accumulation values.
Cells with a likely underestimate for flow accumulation can no longer be identified.
Flow accumulation done.
Slope raster map <r_slope> complete
Slope map done.
Exponent : 0.016
MTI threshold : 2.45624
Calculating MTI raster map..
Cleaning up..
Calculating flood raster map..
Running r.clump..
Pass 1 of 2...
Generating renumbering scheme...
Pass 2 of 2...
r.clump complete. 19533 clumps.
Deleting areas of less than 1000000 cells..
Reading...
Writing...
Done!
Cleaning up..
Removing raster <r_clump>
Removing raster <r_flood_th>
Removing raster <r_flood>
Done.
(Fri Feb 24 07:54:53 2017) Command finished (31 sec)  

Some other statistics...

r.univar map=MTIFlood at PERMANENT                                                 
total null and non-null cells: 9016440
total null cells: 77829
Of the non-null cells:
----------------------
n: 8938611
minimum: -3.67184
maximum: 11.1875
range: 14.8593
mean: 1.74111
mean of absolute values: 1.95274
standard deviation: 2.18821
variance: 4.78828
variation coefficient: 125.679 %
sum: 15563100.8518932
(Fri Feb 24 08:05:33 2017) Command finished (1 sec)                             

                       

I would  appreciate any hint.Have a nice Weekend
Rengifo




   

   
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