[GRASS-user] r.lake questions

[Rich Shepard]

On Wed, 5 Oct 2016, Thomas Adams wrote:

> You understand, don't you, that the point you are using to define your
> 'dam', delineates a watershed;

Tom,

   Yes, I do understand.

> You also need to generate a storage-elevation curve, which will relate the
> water level (which r.lake needs) to the volume behind your dam (assuming
> none escapes, otherwise the problem gets more complicated) -- the change in
> volume depends on the inflow rate, which a hydrologic model will provide.

   This is flat, agricultural land with no defined streams. The only inflow
comes from precipitation; what does not infiltrate into the soil and drains
to the swale adjacent to the county road, along with surface runoff, flows
through a culvert (the 'dam.')

> Typically, hydrologic models are calibrated against observed flow data.
> There is the further assumption that the inflow spreads over the lake
> surface instantaneously, which for a small surface area is not altogether
> unreasonable...

   My reading of the manual pages for r.sim.water and Itzi suggest they, too,
require perennial streams in defined channels. There should be a set of
modules that work for my need here. If you have suggestions please share
them with me.

Thanks,

Rich