Thiessen polygon method of regional delimitation UPSC ~ Civil Services Self Study

The Thiessen polygon method is used to mark the functional region boundaries.

This method was used in the USA to identify the rainfall region. There is a unique property of the Thiessen polygon that there is only one node in each polygon.
The following three steps were used to mark the boundaries of the region.

Step-1:

Identify the major function nodes' location over geographical areas for finding the functional region of nodes. In the below figure, A, B, and C are the functional node of geographical areas.

Step-1

Step -2:

Connect all nodes with the line. In the below figure, Triangle ABC will form by connecting the functional notes of A, B, and C.

Step -2

Step -3:

Mark the middle point of the line AB, BC, and CA.

step-3

Step-4:

Create the longitudinal line from the middle point from each edge. The intersection of all these longitudinal lines will create one center node.

step-4

Step-5:

Connect the line starting from the center node ( i.e "O") to the middle note of each edge and extend it up to geographical boundaries (marking A1, B1, and C1). A polygon drawn from connecting to this longitudinal line in which only one node should be there is called Theissen polygon.

step 5

Finally:

The functional region of A will be the area of A1OC1.
The functional region of B will be the area of A1OB1.
The functional area of C will be the area of C1OB1

Uses of Theissen polygon:

In land-use planning
Identifying the functional area of hospitals, Schools, Shopping malls, cities, etc.
Rainfall pattern area identification

Try to solve the following questions.

What is a ‘region’? Describe the ‘Thiessen’ polygon method of regional delimitation. (2016, 15 marks)

Civil Services Self Study

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