Add layer of Goa plateaus

[planemad]

Is your feature request related to a problem? Please describe.

Laterite capped table lands/plateaus are a unique geological feature of Goa and the Konkani belt. The plateaus play a vital role in water table recharge and supporting life in the settlements around it.

Adding a layer that demarcates the various plateaus will be an important reference for various conservation efforts. There is only one map available online that marks them:

https://www.researchgate.net/figure/Map-of-distribution-of-key-laterite-capped-table-land-plateaux-regions-of-Goa-1_fig1_42800308

Describe the solution you'd like

Polygons of the plateaus do not exist and will have to be created. One way to do it would be to use the terrain map for reference and roughly demarcate them. We can use the research gate map for some of the names, but might have to do further research for more detailed shapes and attributes.

Describe alternatives you've considered

Look online for sources of open data for plateau polygons but none was found

[ramSeraph]

I think the polygons are here - https://bhukosh.gsi.gov.in/arcgis/rest/services/Geomorphology250K/Geomorphology_250K/MapServer/0

[planemad]

@ramSeraph tried via QGIS but not able to get any vectors from the map server. Does it work for you?

[ramSeraph]

@planemad Haven't attempting pulling.. But I was able to see the preview on this page ( You will need to click on the pin and add to map ).

Don't have enough disk space at the moment to pull the whole layer and don't have the code to only pull for a bbox.

[ramSeraph]

I tried downloading and found that the vector data is not accessible from here.
I see it at a different source. I will see if it is downloadable from there.

[ramSeraph]

geomorphology_GA_GM50K_0506.geojsonl.txt Source is Bhuvan. I see some polygon overlaps. Not sure if it is the data or the inability of georss to encode polygon rings( or my inability to understand how georss does polygon rings ).

[planemad]

Looking through the geomorphology data, its likely not directly useful for demarcating the plateau lands which is more closely related with the terrain elevation and slope.

Using DEM generated slope, the outlines of the plateau lands are more clearly visible.

@ramSeraph we do not need to bother with the geomorphology vector for now, although its probably a useful dataset to have in future for other purposes.

[planemad]

Digitized around 100 plateaus using the slope as a reference.

With the slope data enabled, the outline of the plateaus become more visible. The digitized areas were fairly flat areas (<10% slope) surrounded on almost all sides by sloped terrain (>10% slope).

[planemad]

We have a potentially more authentic source of this data from the Bhuvan-Bhujal https://bhuvan-app1.nrsc.gov.in/gwis/gwis.php

Features with LG_2=Plateau Slightly Dissected (PLS) (red) match almost perfectly with what was manually digitized (green).

Manual: https://bhuvan-app1.nrsc.gov.in/gwis/docs/GW_Manual.pdf

[planemad]

Found a great image of a typical laterite soil landscape typical to Goa

https://krishi.icar.gov.in/jspui/bitstream/123456789/56290/1/Characterization%20and%20classification%20of%20Laterite%20landscape%20soils%20of%20Goa.pdf