[GRASS-user] Unique value v. raster maps for infiltration rates using r.sim.water - inconsistent results?

[Rafael Lemieszek Pinheiro]

Hi all,

I'm trying to simulate overland flow for permeable v. partially impervious
land using r.sim.water. I'm using these files
<https://ufmgbr-my.sharepoint.com/:u:/g/personal/lemieszek_ufmg_br/EbtEZBPx3TZDmWp-kUycTxYBhfzG_8XOYxPOoMl50hsvVg?e=8LtqAH>
for testing. I'm getting unexpected results as follows:

First I run a simulation using 50mm/h as an unique value for rainfall
excess rate and 10mm/h for runoff infiltration, simulating one hour of
rain. The resulting depth map seems pretty consistent with what you'd
expect from a rain like that over natural soil that doesn't infiltrate much:

[image: image.png]

I then replace the 10mm/h unique value for a raster that has 0 in some
areas and 10 in others, as follows (yellow = 10, purple = 0):

[image: image.png]

What I'm doing is keeping the value of 10 for certain areas and turning the
value down to 0 in others. All other values and maps are the same (using
r.sim.water's defaults). I expected that the resulting map would show
larger depth values in some areas since less water is being infiltrated.
But the pervious areas (value of 10 in the raster) seem to be draining all
the water going through it:

[image: image.png]

Which doesn't make any sense since rainfall is still at 50mm/h and some
areas are now infiltrating 0mm/h. I didn't change Manning's coefficient.

I thought maybe this was a case of using different units - maybe the
infiltration rate raster is supposed to be expressed in meters? So I
changed the "10" to "0.01" and got yet another unexpected result:

[image: image.png]

Now there are no blank areas anymore, but the map looks exactly like the
first one, where I used 10mm/h for infiltration rate. This map has 0 or
close to 0 values, so that doesn't add up.

Anyway, I'm either hitting a bug (not likely) or I'm missing something
that's painfully obvious (very likely).

Any help would be greatly appreciated.

Cheers,

Rafael
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/grass-user/attachments/20220506/06e77394/attachment-0001.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image.png
Type: image/png
Size: 828794 bytes
Desc: not available
URL: <http://lists.osgeo.org/pipermail/grass-user/attachments/20220506/06e77394/attachment-0004.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image.png
Type: image/png
Size: 124646 bytes
Desc: not available
URL: <http://lists.osgeo.org/pipermail/grass-user/attachments/20220506/06e77394/attachment-0005.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image.png
Type: image/png
Size: 648886 bytes
Desc: not available
URL: <http://lists.osgeo.org/pipermail/grass-user/attachments/20220506/06e77394/attachment-0006.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image.png
Type: image/png
Size: 828934 bytes
Desc: not available
URL: <http://lists.osgeo.org/pipermail/grass-user/attachments/20220506/06e77394/attachment-0007.png>