[GRASS-user] r.lake questions

[Thomas Adams]

Rich,

You understand, don't you, that the point you are using to define your
'dam', delineates a watershed; so, there is runoff from the watershed,
which will not be uniform in its contribution -- a fundamental issue in
hydrology, which is more critical to quantify accurately at smaller spatial
scales -- knowing the rainfall rate alone will not give you what you need.
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.
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...

Tom

On Wed, Oct 5, 2016 at 11:48 AM, Rich Shepard <rshepard at appl-ecosys.com>
wrote:

>   I want to ensure my understanding how to use r.lake for my need.
>
>   It would be good to produce animation of flooded area with increasing
> precipitation; use of the '-o' option is required. But, perhaps I need to
> produce a large series of individual maps.
>
>   Under what condition is use of the '-n' option appropriate?
>
>   If I want a final water_level of 1 m above the elevation of the specified
> coordinates in increments of 0.254 mm how can I specify this for the
> animation? The manual's description tells me that the 1 m water_level is
> the
> final height and the elevation of the specified coordinates is the starting
> height. How are map-to-map increments specified? A related question is
> whether the water level associated with a given map can be produced. That
> is, can individual maps in the animation be related to specific water
> levels? This quantification of output map and water level above the
> starting
> elevation is very important.
>
>   All thoughts, suggestions, and pointers to more information are welcome.
>
> Rich
> _______________________________________________
> grass-user mailing list
> grass-user at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/grass-user
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/grass-user/attachments/20161005/b7c512a7/attachment.html>