[GRASS-user] Calculate flooded area based on precipitation

[Rich Shepard]

   My client needs maps that show flooded areas above a specified elevation
based on precipitation rate and time. I can approximate precip rates based
on daily measures at nearby weather stations and can assume saturated soils.
The topography is flat: 0-3% slope is the characteristics of this soil map
unit, and the ~40 ha area is essentially flat.

   Precipitation flows off this land through an under-road culvert with a
known invert elevation. If the culvert is blocked he needs to know the area
inundated with a given precipitation rate for a specified time (e.g., one
day).

   I've looked at the hydrologic models and don't see any that appear to
provide answers to this question. It's not landscape level analyses, nor are
there any defined stream channels, or noticeable slopes. r.lake shows
inundated areas at specified water heights above a given elevation, but
this is independent of precipitation rates and time.

   Laurent's Itzi model calculates accumulation at various elevations for
a specified precipitation rate and time, yet I'm not seeing how to use this
if there is blocked at a specified coordinate along the drainage path.

Pointers needed,

Rich