[OSGeo Africa] SA NLC class shifts per StatsSA region

Gavin Fleming gavinjfleming at gmail.com
Mon Sep 23 02:47:12 PDT 2019

Hi Chris

Great initiative

I would push the custodians of each dataset to fix the source data they supply else complain to the CSI to hold the custodians to account. And in the meantime just fix it yourself. Taking it through GRASS’s v.clean process will clean it and build perfect topology. 

For the SAL that would be StatsSA and for place names I’m not sure who the definitive custodian is or if it’s a combination of StatsSA, NGI, DWA and DAC. DAC is the custodian of geographical place names (e.g. https://www.gov.za/services/place-live/change-names-geographical-names-list) and used to maintain a gazetteer - I had a copy many years ago at the CSIR. Back then it was in a spreadsheet that I had to phone around to have someone send me, which you’d probably still have to do since a link I found, which is where I’d expect it to be, is down: http://sagns.dac.gov.za/


> On 02 Sep 2019, at 12:03, Chris Berens <chris at mapland.co.za> wrote:
> Hello listers,
> I feel like things change fast in this sector. The tools we use and the content we work with are both rivers of change. Currently I am working with a group of NGOs engaged with the Western Cape Government's Informal Settlement Support Programme <https://www.westerncape.gov.za/general-publication/informal-settlement-support-programme-issp-2016-western-cape>  to provide information for state planning purposes in this fluid environment.
> Together with OpenUp <https://openup.org.za/> we aim to take the  Wazimap <https://wazimap.co.za/profiles/province-WC-western-cape/> web census platform down to settlement level (currently you can only drill down to ward level), add a PDF report export function and ultimately a user interface.
> One extra element that we are adding is a Land Use Land Class change analysis graphic and tabular report by region with the smallest building block being  the Census Small Area Layer (SAL). In other words provide  a current local context to the 2011 Census data by presenting the Level 2 urban LULC class prevalence from the 2000, 2013 and 2018 NLC layers. We are mostly using QGIS <https://qgis.org/en/site/> for our layer preparations and the new Zonal histogram tool (available since v3.2) rips through this task quite smartly. If there is a better tool in the FOSS4G stable then let's hear about it too.
> Where I would like some help is in identifying a source for topologically correct Census 2011 geography. 
> The set I have from StatsSA have dozens of problematic sub-place objects (I haven't run the SAL yet). QGIS3 can skip past corrupt objects which is great but we'd rather go for gold.
> Another input which would be welcome is knowledge of current gazetteers which might identify the names of settlements at a sub sub-place level. The old DWAF Communities layer was such a source. Just not sure if it has been kept updated.
> Kind regards,
> Chris Berens
> -- 
> Chris Berens, Pr.GISc
> SAGC No.1308
> +27 (0)82 567 9322
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