[GRASS-user] r.mapcalc: compare two maps [RESOLVED]

[Laurent C.]

2017-03-30 16:02 GMT-06:00 Rich Shepard <rshepard at appl-ecosys.com>:
> On Thu, 30 Mar 2017, Laurent C. wrote:
>
>> In that case, you will not see the accumulation upstream the culvert that
>> should normally occur if the pipe is actually higher than the ground.
>
>
> Laurent,
>
>   Both invert and outfall are above ground level and below the road. If
> r.carve used the mean elevation between the two then the 'stream' is higher
> than the bottom of the roadside swale. This should accumulate water until
> the elevation matches the invert, correct?

Rich,

As far as I understand, r.carve interpolate the elevation using as
starting points the DEM bellow the extremities of the vector lines.
So if the DEM at these points is equal to the invert elevation of your
culvert, you're good.

Laurent

>> Please note that in a future version, Itzï will be able to model culverts
>> more accurately thanks to a coupled drainage model. But this might be in a
>> few months.
>
>
>   I'd like to do the best that Itzi can with the current version. I may have
> opportunities to do more flat land hydrologic models so the more fluent in
> Itzi I am the easier it will be and the less I'll be asking for help. :-)
>
>
> Rich
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