[talk-ph] Admin Boundary and Coastline

Marloue Pidor murlwe at mail2Engineer.com
Fri May 20 05:44:30 BST 2011

Maning, we have the need to do that at least in Davao because we have
this Disaster Preparedness project here and it includes monitoring of
passenger sea vessels via GPS/SMS?RF going from Davao to Samal so I need
the boundaries. We are using OSM as the base map. That is also the
reason why I am adding now the Barangay boundaries to have some idea to
where the vessel on the map.

Eugene, that information help me a lot so now I would limit the barangay
boundary to 22kms or 30kms from the shoreline.

Thanks for the info guys.


<-----Original Message-----> 
From: maning sambale [emmanuel.sambale at gmail.com]
>Sent: 5/20/2011 12:15:48 PM
>Cc: murlwe at mail2engineer.com;
>Subject: Re: [talk-ph] Admin Boundary and Coastline
>On Fri, May 20, 2011 at 11:50 AM, Eugene Alvin Villar
<seav80 at gmail.com> 
>> Hi Murlwe,
>> I don't think that municipal/provincial waters should be clamped to
>> the national waters.
>> According to the UNCLOS, national waters are those that are within 12
>> nautical miles (about 22km) from the coastline. According to the
>> Philippine Fisheries Code of 1998, municipal waters are within 15
>> kilometers of the coastline. In addition, there is yet no rule on how
>> to deal with overlapping municipal waters.
>According to the Fisheries Code:
>Where two (2) municipalities are so situated on opposite shores that
>there is less than thirty (30) kilometers of marine waters between
>them, the third line shall be equally distant from the opposite shore
>of the respective municipalities.
>This can be easily done with a GIS buffer operation, but I don't find
>any real need for osm to do that. You can of course download the osm
>data and create your preferred boundary within a GIS app.
>> I couldn't find a law stating anything about provincial waters, but I
>> assume they encompass their municipalities' waters. Same with
>> waters.
>> So the idea is to mark admin boundaries of barangays,
>> municipalities/cities and provinces as just the land portions for
>> This includes islands.
>This is a touchy issue (politically), so for now, I agree with using
>coastlines as part of the admin boundary. Plus, it is easier to
>maintain the data since when we move the the coastline, the admin
>boundary in relation to the coastline move as well.
>Although I have different opinion with "clamping" boundary relations to
>> If the concern is that you want to signify that places/landmarks of
>> LGU are within its boundaries in GIS terms, then the GIS app need to
>> support boundaries that are composed of multiple polygons. For
>> example, Caloocan City is composed of 2 disjoint territories
>> <http://www.openstreetmap.org/?relation=273242>. To say that a street
>> or POI is within Caloocan, the GIS app needs to support multiple
>> polygons.
>I think postgis can do this.
>> Same thing goes currently with LGUs that have islands. The admin
>> boundaries currently include islands as multipolygons. For example,
>> Romblon, whose boundaries are currently clamped to the coastlines of
>> all of its constituent islands:
>> <http://www.openstreetmap.org/?relation=1506343>.
>> Eugene
>> On Fri, May 20, 2011 at 10:27 AM, Marloue Pidor
>> <murlwe at mail2engineer.com> wrote:
>>> Hi Eugene, I find it easier if the Barangay boundaries be extendend
>>> City/Municipal boundary, City/Municipal boundary be extended to the
>>> Provincial boundary, Provincial boundary to the Country boundary.
This is
>>> just a suggestion for the coastal areas as you said to map out the
>>> municipal and provincial waters. If you notice here,
>>> http://osm.org/go/4sY75GPk-- the admin boundaries are clamped to the
>>> shoreline and creating the same to the island when we can include
>>> island to the municipal boundary. I'm suggesting this because on a
>>> of view, it is easier to look for places when it is placed inside
>>> boundaries.
>>> murlwe
>>> <-----Original Message----->
>>> From: Eugene Alvin Villar [seav80 at gmail.com]
>>>>Sent: 5/19/2011 10:13:33 PM
>>>>To: murlwe at mail2engineer.com
>>>>Subject: Re: [talk-ph] Admin Boundary and Coastline
>>>>There's no real need. The idea is that in the future we would be
>>>>to map out the exact municipal and provincial waters. But until
>>>>making the admin boundaries just tackle land for the moment is
>>>>manageable since data is much more readily available.
>>>>Please reply if you have other suggestions. :)
>>>>On Thu, May 19, 2011 at 8:23 PM, Marloue Pidor 
><murlwe at mail2engineer.com>
>>>>> Is there a need to clamp the admin boundaries to the coastline?
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