[GRASS-user] Help needed with interactive selection of vectors

[Thomas Adams]

List:

I work for the US National Weather Service at the Ohio River Forecast 
Center. We generate, on a daily basis, a graphic that looks like this: 
http://www.erh.noaa.gov/er/ohrfc/fop.html

The linked graphic would be pretty trivial to create in GRASS using 
ps.map. However, during times where there is a reasonable risk for 
significant flooding, the map must be altered to designate the smaller 
subbasins (or areas) that are at risk and to annotate the period over 
which the threat exists. I'm sorry I can not link an example to show, 
since there is no current flooding in the US or risk thereof.

Currently, the process is carried out interactively using ArcGIS. I am 
trying to offer up an open source alternative with GRASS. I am sure a 
more sensible, non-interactive way of generating the map explicitly 
through a modeling approach would be best (and we do, of course, base 
designating the basins at risk on hydrologic modeling), but there is no 
*direct* link. Currently human interaction is used and some will insist 
on this.

So, I am left wondering how to best approach this is GRASS, namely, either:

(1) have the ability to manually select smaller subbasins and group them 
together to designate the area at risk, or

(2) hand draw/digitize the area

Any suggestions are appreciated!

Regards,
Tom

-- 
Thomas E Adams
National Weather Service
Ohio River Forecast Center
1901 South State Route 134
Wilmington, OH 45177

EMAIL:	thomas.adams at noaa.gov

VOICE:	937-383-0528
FAX:	937-383-0033