Thanks for the various comments on the thread.
Having looked at the data in detail, my inclination is to bring in the
remainder of the named watercourse data for NSW (the Hawkesbury and
Sydney Coast/Georges River catchments according to Andrew Davidson).
It looks like there will still be a fair bit of data wrangling.
For the Hawkesbury, there are around 1800 named watercourses. Of those,
about 25% seem to be already fully in OSM, and another 25% partly in
OSM. That's using a 100m buffer around the OSM data, and checking if the
DCS data falls within it, and has the same name. There are many reasons
why this can fail:
- streams not fully digitised
- disconnected geometries
- names incorrect or not matching
- geometries out by > 100m (may be legit)
I assume these all need to be validated and fixed first, before being
able to import the remainder - which need to have their own validation
eg sanity checks, connecting up to other streams etc.
If anyone has any comments or suggestions for making this process less
manual, I'm happy to hear them. I'm mainly using QGIS for the initial
validation
In terms of bringing in unnamed streams, there's a few issues:
1. All the problems above with named stream import are present in the
unnamed streams, with the added problem of names not being able to be
used to help with matching.
2. The fact that the existing data quality from DCS is not that great.
They will presumably update it given time, but that will then need to be
re-imported, with the same issues as above.
3. The sheer quantity of unnamed streams
So at this stage I'm not going to bother with the unnamed stream data
cheers
Tom
----
Canyoning? try http://ozultimate.com/canyoning
Bushwalking? try http://bushwalkingnsw.com
On 25/05/2023 10:21 pm, Tom Brennan wrote:
I'm looking at adding missing stream data in national parks around Sydney.
However, how much value is there in bringing in all of the stream data
in say the DCS Base Map vs just the named streams?
I can see for example, the value in bringing in named streams. But there
are huge numbers of smaller (unnamed) streams.
I have a follow up question about how best to input stream data, but
that probably depends on the views to the question above.
cheers
Tom
----
Canyoning? try http://ozultimate.com/canyoning
Bushwalking? try http://bushwalkingnsw.com
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