9. Unit Hydrograph UH

Try these first

1. 1.

   What is runoff?

   Hint

   Think about what happens to rainwater.

2. 2.

   Define effective rainfall.

   Hint

   Consider what happens to rainfall before it becomes runoff.

3. 3.

   What does the Unit Hydrograph represent?

   • Total rainfall
   • 1 cm of effective rainfall
   • Total runoff

   Hint

   Consider what 'unit' refers to in this context.

4. 4.

   True or False: Runoff includes losses from infiltration.

   • True
   • False

   Hint

   Think about the definition of runoff.

5. 5.

   A particular watershed has a known Unit Hydrograph with a peak discharge of 150 m³/s for a 1 cm unit rainfall. If 5 cm of effective rainfall occurs, calculate the expected peak discharge.

   Hint

   Simply multiply the peak discharge by the amount of effective rainfall.

6. 6.

   Consider a watershed that has undergone significant land use change from agricultural to urban development. Discuss how this might affect the Unit Hydrograph and provide a rationale.

   Hint

   Think about how land use impacts infiltration and runoff characteristics.