seaward admin boundaries

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seaward admin boundaries

Warin
Hi,

Someone has been working on the hi water coastline and that has mucked
up the suburban admin boundaries near Sydney. Looking at the DCS Base
Map these boundaries look to be further seaward than the hi water mark
.. possibly the low water mark, though I have not investigated this. I
have roughly moved these admin boundaries to where I think they are
according to the DCS Base Map. Certainly this would stop any further
problems with edits to the coastline vs the admin boundaries.

Personal view: sorta makes sense that the council should have control
out to low water mark so they can police it. And would reduce OSM
problems with edits of the coastline.

Thoughts on legalities, bad idea etc ... ???


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Re: seaward admin boundaries

Phil Wyatt
Hi Warin,

You can probably get some definitions of the boundaries from the metadata for the respective layers in DCS. It probably differs between states even though we are meant to be a federation...

In Tasmania .....

* LIST Coastline depicts Mean High Water Mark for the State of Tasmania and offshore islands excluding Macquarie Island.

* Local Government Boundaries legally extend to Low Water Mark and include offshore rocks and islands adjacent to the coastline, irrespective of where the digital boundary may portray.

* Locality Boundaries generally extend to High Water Mark and may not include uninhabitable offshore rocks and small islands.

Of course there are always a few anomalies!

Cheers - Phil

-----Original Message-----
From: Warin <[hidden email]>
Sent: Tuesday, 19 January 2021 8:35 AM
To: talk-au <[hidden email]>
Subject: [talk-au] seaward admin boundaries

Hi,

Someone has been working on the hi water coastline and that has mucked up the suburban admin boundaries near Sydney. Looking at the DCS Base Map these boundaries look to be further seaward than the hi water mark .. possibly the low water mark, though I have not investigated this. I have roughly moved these admin boundaries to where I think they are according to the DCS Base Map. Certainly this would stop any further problems with edits to the coastline vs the admin boundaries.

Personal view: sorta makes sense that the council should have control out to low water mark so they can police it. And would reduce OSM problems with edits of the coastline.

Thoughts on legalities, bad idea etc ... ???


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Re: seaward admin boundaries

cleary
In reply to this post by Warin

As with other boundaries, I'd prefer to keep administrative boundaries separate from natural features even where they approximate and may once have precisely aligned.  I'd like to see administrative boundaries consistent with the authoritative government source/s while natural features such as rivers, coastline etc. are mapped from satellite imagery.  Even where coastline erodes or changes in other ways, I think the administrative boundaries in OSM should remain unchanged until the relevant government authority redraws them.

In regard to high-water and low-water marks, I defer to others with better knowledge.




On Tue, 19 Jan 2021, at 8:35 AM, Warin wrote:

> Hi,
>
> Someone has been working on the hi water coastline and that has mucked
> up the suburban admin boundaries near Sydney. Looking at the DCS Base
> Map these boundaries look to be further seaward than the hi water mark
> .. possibly the low water mark, though I have not investigated this. I
> have roughly moved these admin boundaries to where I think they are
> according to the DCS Base Map. Certainly this would stop any further
> problems with edits to the coastline vs the admin boundaries.
>
> Personal view: sorta makes sense that the council should have control
> out to low water mark so they can police it. And would reduce OSM
> problems with edits of the coastline.
>
> Thoughts on legalities, bad idea etc ... ???
>
>
> _______________________________________________
> Talk-au mailing list
> [hidden email]
> https://lists.openstreetmap.org/listinfo/talk-au
>

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Re: seaward admin boundaries

Warin
On 19/1/21 11:45 am, cleary wrote:
As with other boundaries, I'd prefer to keep administrative boundaries separate from natural features even where they approximate and may once have precisely aligned.  I'd like to see administrative boundaries consistent with the authoritative government source/s while natural features such as rivers, coastline etc. are mapped from satellite imagery.  Even where coastline erodes or changes in other ways, I think the administrative boundaries in OSM should remain unchanged until the relevant government authority redraws them.

In regard to high-water and low-water marks, I defer to others with better knowledge.


Just checked a small sample with the PSMA data and that confirms the DCS Base Map that at least some of theboundaries in NSW are to wards the low tide mark, not th eOSM coastline/hi tide. 




On Tue, 19 Jan 2021, at 8:35 AM, Warin wrote:
Hi,

Someone has been working on the hi water coastline and that has mucked 
up the suburban admin boundaries near Sydney. Looking at the DCS Base 
Map these boundaries look to be further seaward than the hi water mark 
.. possibly the low water mark, though I have not investigated this. I 
have roughly moved these admin boundaries to where I think they are 
according to the DCS Base Map. Certainly this would stop any further 
problems with edits to the coastline vs the admin boundaries.

Personal view: sorta makes sense that the council should have control 
out to low water mark so they can police it. And would reduce OSM 
problems with edits of the coastline.

Thoughts on legalities, bad idea etc ... ???


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Re: seaward admin boundaries

Andrew Harvey-3
In reply to this post by cleary

On Tue, 19 Jan 2021 at 11:48, cleary <[hidden email]> wrote:

As with other boundaries, I'd prefer to keep administrative boundaries separate from natural features even where they approximate and may once have precisely aligned.  I'd like to see administrative boundaries consistent with the authoritative government source/s while natural features such as rivers, coastline etc. are mapped from satellite imagery.  Even where coastline erodes or changes in other ways, I think the administrative boundaries in OSM should remain unchanged until the relevant government authority redraws them.

In regard to high-water and low-water marks, I defer to others with better knowledge.

In my opinion, where the boundary is defined by the natural feature (coastline, river, road centerline etc) then the boundary way should be snapped (share nodes) with the natural feature. This provides the most accurate representation and encodes the "defined by the natural boundary" information which would otherwise be lost. As the coastline/river etc changes then the boundaries are kept up to date because they have shared nodes, this is a feature, not a bug.

This is in contrast to your preference cleary. The PSMA and other government datasets aren't the exact boundary definition, only a digital representation of it, if we have a better coastline or river data we should use ours.

Of course this is all based on that assumption about what defines the legal boundary, but I doubt it is the GIS files the government and it's 3rd parties (PSMA) produce. Phil's comments seem to backup this claim too.

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Re: seaward admin boundaries

Ian Sergeant-2
In reply to this post by cleary
If the "authorative government source" is *right*, then this is all good.

What are the possible cases/issues here?  I can think of a few

1. Accretions and erosion actually change the boundary in real time.  The boundary is dynamic.
2. Accretions and erosion actually change the boundary - but this only has administrative effect when the changes are surveyed and updated.
3. The government source is an approximation and doesn't necessarily correspond to the actual boundary, which is actually administratively defined by a physical feature.
4. The government source administratively defines the boundary.  Any correspondence to the physical feature is historical,  or otherwise not relevant. 
5. The government source administratively defines the boundary, but that data isn't available for us to use, and it seems to closely track a physical feature which we can use.

If we're certain that OSM data is correct (in cases 1 & 3), I see no reason to wait for the government authority to correct its data for OSM use it.

If the boundary is the dynamic physical feature, I see no harm is overloading the physical feature with the boundary relation.

Of course, the actual issue here is more about aligning a physical feature to the boundary that's approximate in itself (coastline)

Ian. 

On Tue, 19 Jan 2021 at 11:48, cleary <[hidden email]> wrote:

As with other boundaries, I'd prefer to keep administrative boundaries separate from natural features even where they approximate and may once have precisely aligned.  I'd like to see administrative boundaries consistent with the authoritative government source/s while natural features such as rivers, coastline etc. are mapped from satellite imagery.  Even where coastline erodes or changes in other ways, I think the administrative boundaries in OSM should remain unchanged until the relevant government authority redraws them.

In regard to high-water and low-water marks, I defer to others with better knowledge.




On Tue, 19 Jan 2021, at 8:35 AM, Warin wrote:
> Hi,
>
> Someone has been working on the hi water coastline and that has mucked
> up the suburban admin boundaries near Sydney. Looking at the DCS Base
> Map these boundaries look to be further seaward than the hi water mark
> .. possibly the low water mark, though I have not investigated this. I
> have roughly moved these admin boundaries to where I think they are
> according to the DCS Base Map. Certainly this would stop any further
> problems with edits to the coastline vs the admin boundaries.
>
> Personal view: sorta makes sense that the council should have control
> out to low water mark so they can police it. And would reduce OSM
> problems with edits of the coastline.
>
> Thoughts on legalities, bad idea etc ... ???
>
>
> _______________________________________________
> Talk-au mailing list
> [hidden email]
> https://lists.openstreetmap.org/listinfo/talk-au
>

_______________________________________________
Talk-au mailing list
[hidden email]
https://lists.openstreetmap.org/listinfo/talk-au

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Re: seaward admin boundaries

Warin
In reply to this post by Andrew Harvey-3
On 19/1/21 2:50 pm, Andrew Harvey wrote:

On Tue, 19 Jan 2021 at 11:48, cleary <[hidden email]> wrote:

As with other boundaries, I'd prefer to keep administrative boundaries separate from natural features even where they approximate and may once have precisely aligned.  I'd like to see administrative boundaries consistent with the authoritative government source/s while natural features such as rivers, coastline etc. are mapped from satellite imagery.  Even where coastline erodes or changes in other ways, I think the administrative boundaries in OSM should remain unchanged until the relevant government authority redraws them.

In regard to high-water and low-water marks, I defer to others with better knowledge.

In my opinion, where the boundary is defined by the natural feature (coastline, river, road centerline etc) then the boundary way should be snapped (share nodes) with the natural feature. This provides the most accurate representation and encodes the "defined by the natural boundary" information which would otherwise be lost. As the coastline/river etc changes then the boundaries are kept up to date because they have shared nodes, this is a feature, not a bug.

This is in contrast to your preference cleary. The PSMA and other government datasets aren't the exact boundary definition, only a digital representation of it, if we have a better coastline or river data we should use ours.


OSM data is also not exact. So I don't think claims of OSM being more exact than other data is an argument I would make ... considering the number of 'inexact' OSM data I come across. And yes I correct it where I can.


Of course this is all based on that assumption about what defines the legal boundary, but I doubt it is the GIS files the government and it's 3rd parties (PSMA) produce. Phil's comments seem to backup this claim too.


Looks like the area of NSW that does not conform to the PSMA/DCS Base map (I think those are both the same) is simply around Sydney and Newcastle  ... so I think I'll change those and be done. All the rest looks to use the PSMA data.... which looks to be the low water mark and that is not mapped in OSM (yet)... would be difficult to map and given the number of contributors willing to map it ... it is never going to be done. So you my way of thinking it is the PSMA data that is the way forward.


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Re: seaward admin boundaries

cleary


My knowledge of legislation etc. is limited and primarily about NSW legislation. I know nothing about other jurisdictions.  In NSW, it seems that definitions by word in the Government Gazette have been replaced by maps.  Some years ago, boundaries used to be "gazetted" in word form but now it seems that graphical representation in maps are the defining form of documentation. If anyone can direct me to an authoritative verbal description of LGA or suburb boundaries in NSW, I would happily accept whatever it stated.

However, the only authoritative source I can now locate is the NSW Spatial Services office. Their website refers to their maps of various administrative boundaries and asserts that they are joint custodian of these layers which are maintained by them.  They go on to state that most of these layers are described by legislation, notifications described by the NSW Government Gazette or more recently by changes described in the register of public surveys and that Spatial Services tracks temporal and spatial changes to these layers through an authority reference layer.

If there is an authoritative source providing verbal descriptions of boundaries passing along the centre of a river or the midline of a particular road (or whatever) then we could accurately align administrative boundaries with those features. However, unless such sources can be referenced, it seems to me that the official administrative boundary maps from NSW Spatial Services  (and replicated by PSMA) are the accurate boundaries.

Incidentally, in quickly looking again this evening, I did find that section 205 of the NSW Local Government Act (1993) as amended specifies that the coastal boundaries of local government areas extend to the low-water mark. I could find no other verbal descriptions of administrative boundaries.







On Tue, 19 Jan 2021, at 7:02 PM, Warin wrote:

> On 19/1/21 2:50 pm, Andrew Harvey wrote:
> >
> > On Tue, 19 Jan 2021 at 11:48, cleary <[hidden email]> wrote:
> >>
> >> As with other boundaries, I'd prefer to keep administrative boundaries separate from natural features even where they approximate and may once have precisely aligned.  I'd like to see administrative boundaries consistent with the authoritative government source/s while natural features such as rivers, coastline etc. are mapped from satellite imagery.  Even where coastline erodes or changes in other ways, I think the administrative boundaries in OSM should remain unchanged until the relevant government authority redraws them.
> >>
> >> In regard to high-water and low-water marks, I defer to others with better knowledge.
> >
> > In my opinion, where the boundary is defined by the natural feature (coastline, river, road centerline etc) then the boundary way should be snapped (share nodes) with the natural feature. This provides the most accurate representation and encodes the "defined by the natural boundary" information which would otherwise be lost. As the coastline/river etc changes then the boundaries are kept up to date because they have shared nodes, this is a feature, not a bug.
> >
> > This is in contrast to your preference cleary. The PSMA and other government datasets aren't the exact boundary definition, only a digital representation of it, if we have a better coastline or river data we should use ours.
>
>
> OSM data is also not exact. So I don't think claims of OSM being more
> exact than other data is an argument I would make ... considering the
> number of 'inexact' OSM data I come across. And yes I correct it where
> I can.
>
> >
> > Of course this is all based on that assumption about what defines the legal boundary, but I doubt it is the GIS files the government and it's 3rd parties (PSMA) produce. Phil's comments seem to backup this claim too.
>
>
> Looks like the area of NSW that does not conform to the PSMA/DCS Base
> map (I think those are both the same) is simply around Sydney and
> Newcastle  ... so I think I'll change those and be done. All the rest
> looks to use the PSMA data.... which looks to be the low water mark and
> that is not mapped in OSM (yet)... would be difficult to map and given
> the number of contributors willing to map it ... it is never going to
> be done. So you my way of thinking it is the PSMA data that is the way
> forward.
>
> _______________________________________________
> Talk-au mailing list
> [hidden email]
> https://lists.openstreetmap.org/listinfo/talk-au
>

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Re: seaward admin boundaries

Phil Wyatt
In Tassie they are still described, often by reference to other plans in the Central Plan Register (CPR)

https://www.tec.tas.gov.au/House_of_Assembly_Elections/img/Maps/2009/CPR/Franklin_09.pdf - found one on the internet....

This is for an Electoral boundary but you see the reference to road centrelines, other titles and in this case even "the centreline of the power transmission line".

I know each council has a plan in the Central Plan Register but again they may refer to other plans etc so it would be a long process to get down to the actual written boundaries (possibly of many private titles) plus, in Tassie you pay to get the plans so it would cost you a fortune!

I would go with the NSW Spatial Services/PSMA boundaries.

Cheers - Phil

-----Original Message-----
From: cleary <[hidden email]>
Sent: Tuesday, 19 January 2021 7:41 PM
To: OpenStreetMap <[hidden email]>
Subject: Re: [talk-au] seaward admin boundaries



My knowledge of legislation etc. is limited and primarily about NSW legislation. I know nothing about other jurisdictions.  In NSW, it seems that definitions by word in the Government Gazette have been replaced by maps.  Some years ago, boundaries used to be "gazetted" in word form but now it seems that graphical representation in maps are the defining form of documentation. If anyone can direct me to an authoritative verbal description of LGA or suburb boundaries in NSW, I would happily accept whatever it stated.

However, the only authoritative source I can now locate is the NSW Spatial Services office. Their website refers to their maps of various administrative boundaries and asserts that they are joint custodian of these layers which are maintained by them.  They go on to state that most of these layers are described by legislation, notifications described by the NSW Government Gazette or more recently by changes described in the register of public surveys and that Spatial Services tracks temporal and spatial changes to these layers through an authority reference layer.

If there is an authoritative source providing verbal descriptions of boundaries passing along the centre of a river or the midline of a particular road (or whatever) then we could accurately align administrative boundaries with those features. However, unless such sources can be referenced, it seems to me that the official administrative boundary maps from NSW Spatial Services  (and replicated by PSMA) are the accurate boundaries.

Incidentally, in quickly looking again this evening, I did find that section 205 of the NSW Local Government Act (1993) as amended specifies that the coastal boundaries of local government areas extend to the low-water mark. I could find no other verbal descriptions of administrative boundaries.







On Tue, 19 Jan 2021, at 7:02 PM, Warin wrote:

> On 19/1/21 2:50 pm, Andrew Harvey wrote:
> >
> > On Tue, 19 Jan 2021 at 11:48, cleary <[hidden email]> wrote:
> >>
> >> As with other boundaries, I'd prefer to keep administrative boundaries separate from natural features even where they approximate and may once have precisely aligned.  I'd like to see administrative boundaries consistent with the authoritative government source/s while natural features such as rivers, coastline etc. are mapped from satellite imagery.  Even where coastline erodes or changes in other ways, I think the administrative boundaries in OSM should remain unchanged until the relevant government authority redraws them.
> >>
> >> In regard to high-water and low-water marks, I defer to others with better knowledge.
> >
> > In my opinion, where the boundary is defined by the natural feature (coastline, river, road centerline etc) then the boundary way should be snapped (share nodes) with the natural feature. This provides the most accurate representation and encodes the "defined by the natural boundary" information which would otherwise be lost. As the coastline/river etc changes then the boundaries are kept up to date because they have shared nodes, this is a feature, not a bug.
> >
> > This is in contrast to your preference cleary. The PSMA and other government datasets aren't the exact boundary definition, only a digital representation of it, if we have a better coastline or river data we should use ours.
>
>
> OSM data is also not exact. So I don't think claims of OSM being more
> exact than other data is an argument I would make ... considering the
> number of 'inexact' OSM data I come across. And yes I correct it where
> I can.
>
> >
> > Of course this is all based on that assumption about what defines the legal boundary, but I doubt it is the GIS files the government and it's 3rd parties (PSMA) produce. Phil's comments seem to backup this claim too.
>
>
> Looks like the area of NSW that does not conform to the PSMA/DCS Base
> map (I think those are both the same) is simply around Sydney and
> Newcastle  ... so I think I'll change those and be done. All the rest
> looks to use the PSMA data.... which looks to be the low water mark
> and that is not mapped in OSM (yet)... would be difficult to map and
> given the number of contributors willing to map it ... it is never
> going to be done. So you my way of thinking it is the PSMA data that
> is the way forward.
>
> _______________________________________________
> Talk-au mailing list
> [hidden email]
> https://lists.openstreetmap.org/listinfo/talk-au
>

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