9.1. Theissen Polygon Method

Try these first

1. 1.

   What is the primary purpose of the Theissen Polygon Method?

   Hint

   Think about how rainfall data from multiple sources can be combined.

2. 2.

   List one merit of using the Theissen Polygon Method.

   Hint

   What makes something easy to use in practice?

3. 3.

   What is the main basis of the Theissen Polygon Method?

   • Geometric
   • Arithmetic
   • Statistical

   Hint

   Think about how shapes define regions in this method.

4. 4.

   True or False: The Theissen Polygon Method accounts for topographical variations in rainfall.

   • True
   • False

   Hint

   Recall the limitations we discussed in class.

5. 5.

   In a catchment area with five rain gauges, construct the Theissen polygons based on the following coordinates and rain measurements: Gauge A(1, 1, 10mm), Gauge B(3, 1, 5mm), Gauge C(2, 3, 20mm), Gauge D(4, 2, 15mm), and Gauge E(1, 4, 10mm). Provide a rainfall estimate based on your polygons.

   Hint

   Ensure you measure the areas accurately and consider the contribution of rainfall from each gauge.

6. 6.

   Evaluate how the assumption of homogeneous rainfall impacts the output of rainfall estimates in a scenario where significant elevation changes occur across a catchment.

   Hint

   Reflect on how mountains or valleys might alter rainfall distribution.