[GRASS-user] river and dams in netwok analysis

[Etienne DELAY]

Dear all,
I'm try to understand network analysis fonction in grass 6.4. I have 2 
layers :
* Points layer with the spatial dams repartition
* polylines layer with rivers
I would like to know for each dam how is before and how is after in the 
network. I at the end I would like to export a shp files with those data 
in the attribute table.

I have find some informations here : 
http://www.ing.unitn.it/~grass/docs/tutorial_641_en/htdocs/esercitazione/network_analysis/node1.html

And I have done that :

##save a region
v.in.region --overwrite --verbose output=region_central

## clip rivers
v.overlay --overwrite --verbose ainput=troncon_dordogne at PERMANENT 
atype=line binput=region_central output=rivers_central operator=and

v.overlay --overwrite --verbose ainput=troncon_dordogne at PERMANENT 
atype=line binput=bv_dordogne at PERMANENT output=rivers_bv operator=and
v.select ainput=barrage_energie at PERMANENT binput=bv_dordogne at PERMANENT 
output=barrage_e_bv
##Connect dam points to the network
## thresh=500 means that only points within
## the distance of 500 metres are connected to the lines
v.net --overwrite --verbose input=rivers_bv 
points=barrage_e_bv at PERMANENT output=network operation=connect thresh=500

## link the attribute table of the fire stations to layer 2 of the 
network map
v.db.connect -o --verbose map=network table=barrage_e_bv at PERMANENT layer=2

But I'm not so smart with data manipulation in GRASS so If someone can 
give me a hand it's nice :-)

Thank you

Best regards

E.

-- 
Cordialement

Etienne DELAY
Chaire: Capital environnemental et gestion durable des cours d'eau
laboratoire GEOLAB UMR 6042 CNRS
Université de Limoges, FLSH
39E rue Camille Guérin 87036 Limoges
blog : http://elcep.legtux.org