I just spent the last 5 years doing this exact thing for the BC Government - mapping all hydrographic data across BC,
(which they are now giving away for free :) ). The development was all done in PostGIS, spanning 150GB in tables. It's
definitely possible.
Have you tried simply querying which stream segments spatially touch your
specified segment?
-- Assuming your dataset is properly noded, directionalized
-- and digitized in a downstream direction, this will find
-- all streams that enter into stream with id = 1
SELECT b.*
FROM streams a, streams b
WHERE a.stream_id = 1 -- your specified segment
AND a.the_geom && b.the_geom
AND ST_Distance(
ST_StartPoint(a.the_geom),
ST_EndPoint(b.the_geom)
) = 0;
There is also an interesting concept where you can attribute the stream segments with a precomputed "hierarchical key".
Once done, you can quickly query all streams that are upstream of a given segment ... non-spatially.
This very old document may be of some interest to you.
ftp://ftp.geobc.gov.bc.ca/pub/outgoing/FreshWaterAtlasDocuments/HierarchicalKeysTechnicalDocumentation.doc
The doc came from this site
http://aardvark.gov.bc.ca/apps/metastar/metadataDetail.do?from=search&edit=true&showall=showall&recordSet=ISO19115&recordUID=4212.
Cheers,
Kevin
surya wrote:
Dear Bruce,
I need to query which river segment flowing into a specified segments.
best regards,
surya
----- Original Message ----- From: "Bruce Rindahl" <[email protected]>
To: <[email protected]>; "PostGIS Users Discussion"
<[email protected]>
Sent: Thursday, February 19, 2009 12:02 AM
Subject: Re: [postgis-users] river network
Do you need to perform routing or some other analysis on the network?
Bruce
[email protected] wrote:
Dear List,
does anyone has experience or references on how to store river
network segments of a watershed in Postgis database?
bestregards,
surya
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