7.5.2. Normal Ratio Method

Try these first

1. 1.

   Define the Normal Ratio Method.

   Hint

   Consider what happens when data is lacking.

2. 2.

   What is normal rainfall?

   Hint

   Think about how we calculate averages.

3. 3.

   What does the Normal Ratio Method estimate?

   • Missing data
   • Average data
   • Overall statistics

   Hint

   Think about the context when data is lacking.

4. 4.

   True or False: Normal Ratio Method can be used when the normal rainfall significantly varies.

   • True
   • False

   Hint

   Reflect on why variability is important.

5. 5.

   A researcher has three stations with normal rainfall figures of 400mm, 500mm, and 300mm. Their recorded rainfalls are 50mm, 70mm, and 60mm respectively. If the normal rainfall at a missing station is 600mm, what should the estimated rainfall be?

   Hint

   Don’t forget the formula as you calculate for each station!

6. 6.

   In a dataset, two out of five stations report problems with their gauges. Known normal rainfalls are 100mm, 150mm, and 200mm with recorded values of 10mm, 20mm, and 25mm. How would you apply the Normal Ratio Method to estimate the missing data assuming normal rainfall for the network is around 300mm?

   Hint

   Remember to focus on how each gauge points its contribution.