12.4. Derivation of DAD Curves

Try these first

1. 1.

   What is the primary use of the isohyetal method?

   Hint

   Think about visualizing rainfall distribution.

2. 2.

   Name one data requirement for deriving DAD curves.

   Hint

   Consider what type of information is needed to understand rainfall.

3. 3.

   What do DAD curves help estimate?

   • Only rainfall amount
   • Rainfall distribution over area and time
   • Flood probability

   Hint

   Think about the relationship between rainfall and area.

4. 4.

   True or False: Isohyets represent lines of different rainfall depths.

   • True
   • False

   Hint

   Recall what isohyets represent on a map.

5. 5.

   Given a storm that produced 100 mm of rain over an area of 10 km², calculate the average depth using the isohyetal method with a surrounding area having 200 mm rainfall over another 20 km².

   Hint

   Combine the rainfall and area first.

6. 6.

   Discuss how the assumptions made in DAD curve derivation might affect flood risk estimations in light of climate change.

   Hint

   Consider how patterns of rainfall might shift.