[postgis-users] river network

[storma-ipb at indo.net.id]

Dear Kevin,

thank you very much for the information and also for SQL query.
I will certainly exercises it in my data set.   I am pleased to
know that at least it is possible to use PostGIS for this type
of data set.   My data set consist of 117 rivers sorounding one
big city. Four of them are very large rivers having width up to
500 m. Therefore,  the rivers are used as a means of 
transportation and also recreational area. Part of the river
are under influence of dynamic tidal. The Major of the city is
promoting his city to be one of river-related touristic area
and would like to take inventory of all river characteriistics
sorounding his city. Knowing which rivers flowing into which
rivers is important to know the interrelation of each rivers
(otherwise tourist will get lost in swampy area and end up in
the ocean). Some rivers might not connected at all to other
rivers. To capture this interrelation, one river is divided
into segments. One segment has the following  attributes;- start node-end node (Nodes representing points where other
river entering the river under consideration),- river depth,
- river width,
- having tidal influence or not,
- intermittent or not,
- blocked or not
- dead end or not
- Turbidity
- Nitrate content
- Salinity
- Orthofosfate content
- Distance to Hotels
.....

If this project is succesful, two other similar  cities are
waiting in the queue..
You said that the river should be digitized in downstraem
direction (mimicing the river flow??). Is there any different
when we digitized them in upstream direction?


best regards,
surya



> 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"
>> <rindahl at lrcwe.com> To: <storma-ipb at indo.net.id>; "PostGIS
>> Users Discussion"
>> <postgis-users at postgis.refractions.net>
>> 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
>>>
>>>
>>> storma-ipb at indo.net.id 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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>>
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