[GRASS-user] Calculate flooded area based on precipitation

[Rich Shepard]

On Wed, 15 Feb 2017, Laurent C. wrote:

> The h_max output map of Itzï will correspond to the maximum water level
> reached during the simulation.

Laurent,

   I did this to reveal water accumulation with un-blocked flows and did not
see how to modify it to show blocked flow accumulations.

> To simulate the blockage, you might need to change the DEM locally. But in
> the case of a under-road culvert, just leaving the measured elevation of
> the road might be enough.

   I'll need to experiment with this to understand how to 'leave the road
elevation' when the culvert's blocked. Perhaps increasing the DEM of all
cells to that of the road elevation will do it.

> If you use direct rainfall, all the cells in the h_max map will appear wet
> (although with very small depth). You will need to clean up the map using
> r.mapcalc to keep only the cells with a water depth above a threshold of
> your choice.

   Don't completely understand this now; thinking about it and trying various
simulations will probably help.

Thanks,

Rich