In this module we will download human settlements for the Himachal region from Open Street Maps and play around with various visualizations in QGIS suitable for this high volume (thousands of items) data sets. We will get a better understanding of distribution of different type of settlements including hamlets, villages, isolated dwellings (more details in module 7C) as per geography and elevation.
Open up the QGIS “QuickOSM” plug-in and query “place” = “hamlet” for “layer extent” = “HP_DEM” (Himachal region). Around 9972 hamlets will be downloaded and visualized on the base map. Set “color” as yellow under “Symbology”. See Images 1+2 below.
Zoom into any hamlet (yellow dot) on a Google Sattelite base map to verify the existence of individual hamlets. Save the downloaded hamlets as an ESRI shapefile for future QGIS sessions. See Images 3+4 below.
Downloading hamlets from Open Street Maps
9971 hamlets downloaded from OSM for the Himachal region
Individual hamlets shown on a Google Satellite map
Save hamlets as an ESRI shapefile
Types of Settlements
Similar as above let’s query for “place” = “isolated_dwelling” to download smaller / more remote dwellings, usually located closer to forest regions (color these as green). Finally query “place” = “village” to download larger settlements (villages with basic facilities) usually located inside main valleys / along roads (color these as red). Save both vector layers as “ESRI Shapefiles. See Images 1+2 below.
In the 2×3 degree region we downloaded approximately:
1872 villages
9971 hamlets
3202 dwellings
As mentioned in earlier bootcamp chapters, these settlements are very useful for the alpine hiker to plan your route / night halts / food ration.
When visualized on a satellite map we can see that the larger villages are usually located in the main valleys / along roads while smaller hamlets are located higher up the valley slopes (farming settlements) and isolated dwellings are located more remotely / inside the forest. See Image 3 below.3202 Isolated dwellings across Himachal shown as green dots
1872 villages shown as red dots across Himachal
Hamlets (yellow), dwellings (green) and villages (red) in Himachal shown on a Google Satellite base map
Visualization
Larger / denser data sets (thousands of itmes) can be visualized more effectively in QGIS at larger scale / lower zoom level. Open up “Symbology” for the “isolated_dwellings” and change to “Point Cluster” to visualize denser clusters of dwellings using numbers instead of individual dots. See Images 1+2 below.
Similarly we can also visualize dwellings as “Point Displacement”. Zoom in and out and pan around the downloaded region to understand each type of visualization. See Images 3+4 below.
Yet another useful way to visualize density of high volume data in QGIS is using heatmaps. Open up “Symbology” for dwellings and use “Heatmap” with a green color ramp to visualize density of dwellings as shades of green (light = sparse, dark = dense). See Images 5+6 below.Visualize dwellings as “Point Cluster” in QGIS
Isolated dwellings downloaded from OSM shown as “Point Cluster” in QGIS
Show dwellings as “Point Displacement” in QGIS
Show dwellings as “Point Displacement” in QGIS
Show dwellings as heatmaps in QGIS using green color ramp
Density of isolated dwellings in Himachal visualized as a heatmap in QGIS
Elevation
Let’s take a closer look now at the altitude of settlements. To do so let’s first “Drape” the “hamlets” vector layer using the downloaded DEM data for the Himachal region. This will add a new “draped” vector layer in QGIS. See Image 1 below.
Next, let’s open up the “Open Attributes Table” for layer “draped” and add a new attribute “Z”. Update the values for this attribute with “z($geometry)” (altitude of current feature / hamlet). See Images 2+3 below.
Click on the column “Z” to sort hamlets as per elevation, “Bharatpur Tent Colony” being the highest at 4705 meters altitude. Right click on this feature / row and choose “Pan to Feature” to show the location of this highest hamlet in the QGIS main screen. See Images 4+5 below.Draping hamlets using the downloaded DEM data for the Himachal region
Add a new attribute “Z” to draped hamlets vector layer
Update attribute “Z” to z($geometry) or elevation of current feature
Sorting hamlets as per altitude – right click on any hamlet and chose “Pan to Feature” to zoom into the hamlet in the main QGIS window
Bharatpur Tent Colony, highest hamlet in the Himachal region
Distribution
Next, let’s take a look at the distribution of hamlets as per altitude. Open up “Symbology” for the “draped” hamlets and select a “Graduated” style with a “Turbo” color ramp using “Equal Interval” for 10 classes. This gives a comprehensive visualization of the spread of hamlets as per their altitude on the main QGIS window. See Images 1+2 below.
Finally, open up a “Vector Layer Histogram” plot in the QGIS “processing toolbox” on “draped” hamlets to generate a hamlet altitude distribution chart. Maximum hamlets (3410) are located between 1500 to 2000 meters altitude. See Images 3+4 below.Visualizing “draped” hamlets using a Turbo color spectrum as per their elevation downloaded from DEM data for Himachal region
Visualizing hamlets as per elevation in Himachal region
Create a distribution of elevation of hamlets in Himachal region
Hamlet elevation histogram for Himachal region
