[GRASSLIST:10010] Re: Filling with flood
hamish_nospam at yahoo.com
Wed Jan 25 17:31:31 EST 2006
Wow, lots of good ideas.
> Creating dam:
> 1) With r.digit digitise map dam line; Assign correct height to it;
> 2) Grow it to 2 cells atleast to avoid any holes in dam;
> 3) With r.mapcalc add dam to DEM.
> Filling lake:
> 1) With r.digit create map with atleast one cell with any value below
> target water level (seed);
> 2) Feed in DEM, seed, target water level to r.lake.
Could the seed be part of the module? seed_location=x,y seed_elevation=z
Could save some effort, the less work that needs to be done by hand the
better / faster.
Another question.. how to model sea level rise / storm surge?
v.in.region to get an outside box -> v.to.rast -> r.lake?
e.g. combine with images like this by Markus + Jachym's v.extrude:
and you have *incredibly* effective graphics to show to planners,
public, etc. Make an animation of the flooding happening in NVIZ,
even more so. e.g. do for Downtown New Orleans.. as most major world
cities are harbour-front, there is much demand and modelling already
happening around this.
In the past I have used a trick in NVIZ with a second, semi-transparent,
constant surface and raised & lowered the z-offset*, but that is really
visualization only qualitative approach.
River flooding is more difficult I guess as the surface is not at a
constant elevation, but it would be nice to transfer watershed volume
accumulations to a flood which rose until volume was exhausted?
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