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Task 1 - Assess water distribution access#

For Camp 18 in Kutupalong Refugee Camp, we have a dataset on the locations of water distribution points. Further we have data on the buildings (footprint and centroid) within camp 18. In the following task we will use the following dataset:

Download all datasets here. Save the folder on your computer. Unzip the .zip file. The unzipped folder is structured according to the recommended folder structure for QGIS projects. Under “data > input” you find the geopackage file task1.gpkg which contains the following vector layers:

  • camp18_waterpoints (points): Water point locations within camp 18

  • camp18_buildings_centroid (points): Centroids of all building objects inside camp 18

  • camp18_buildings_footprint (polygons): Actual footprints of all buildings

  • camp18_boundary (polygons): The camps legal boundary

STEP 1: Catchments with openrouteservice isochrones#

Make sure you installed the ORS Tools plugin and set it up already with an API Key. If not - see the how to here Plugin: Openrouteservice (ORS) tools

Click in the toolbar on the ORS Tools plugin Icon Icon. Click on Batch Jobs -> Isochrones from Layer. Leave all settings at default except:

Travel mode

foot-walking

Input Point Layer

waterpoints

Dimension

distance

Comma separated ranges

500
Watch here:

The result layer shows for every waterpoint a 500 meter catchment area for pedestrian travel mode. 500 meter is the maximum distance from any household to the water point according to The Sphere Handbook: Humanitarian Charter and Minimum Standards in Humanitarian Response p. 106. There are other key indicators like maximum number of people using the facility, queuing time, etc. We will work on the distance as we miss further information like the flow rate per water point or the household size per building.

Question

How is the coverage with water point catchments within camp 18? Any underserved areas?

We proceed to find out how many water point options are there for each building given the 500m constraint. Basically we add a count aggregation of isochrones that intersect with each building.

Open the Processing Toolbox and scroll down to Vector general choose Join attributes by location (summary) or enter “Join attributes by location (summary)” in the search bar. Leave all settings at default except:

Base Layer

buildings_centroid

Join Layer

Isochrones

Geometric Predicate

Intersects

Fields to Summarize

ID

Summaries to Calculate

count
Watch here:

Question

What is the min/max number of waterpoints available to the buildings in camp 18?

STEP 2: Catchments for operational facilities#

Look into the attributes of the waterpoints layer. Filter for all waterpoints that are operational (search for Extract by Attribute). Redo the analysis for operational waterpoints only.

Watch here:

Question

Is the general coverage different, any undersupplied areas? What are the differences in the min/max number of waterpoints available to the buildings in camp 18 compared to using all waterpoints (non-operational, planned)

STEP 3: Waterpoint catchment by closest euclidean distance#

There are other means to generate catchment areas, implemented in QGIS. In the next part we will use the hub distance to calculate the euclidean distance between every building and its closest waterpoint.

Open the Processing Toolbox, choose Vector Analysis,then choose Distance to nearest hub (points)or enter “Distance to nearest hub (points)” in the search bar. Leave all settings at default except:

Source points

buildings_centroid

Destination hubs layer

waterpoints

Hub layer name attribute

id_plastic

Measurement unit

Meters
Watch here:

The output layer has the same point geometry type like the input building_centroid layer. But it now features two attributes:

  • HubName: The name/id of the closest waterpoint.

  • HubDist: The euclidean distance from the building centroid to the closest waterpoint in meters.

Question

What is the shortest / longest euclidean distance from a building to the closest waterpoint.

STEP 4: Hub distance based catchments#

All buildings are assigned to their closest waterpoint. With the minimum bounding geometry tool in QGIS we can use this grouping information to create areas.

Open the Processing Toolbox, choose Vector Analysis, then choose Minimum Bounding Geometry or enter “Minimum Bounding Geometry” in the search bar. Leave all settings at default except:

Input layer

Hub distance

Field

Hubname

Geometry type

Convex Hull
Watch here:

Question

Have a close look at the hub distance based catchments. Can you tell that some buildings are quite far from a waterpoint when considering the paths connecting the two?