Lecture 6b - Runoff Prediction - Unit Hydrograph Methods

Question 1

What are unit hydrographs used for?

Answer 1

translating rainfall excess amounts into catchment outlet flow rates

Question 2

What does a unit hydrograph represent?

Answer 2

the characteristic flow rate response of a watershed to 1 cm of rainfall excess occuring over a defined time step

Question 3

What are the ways unit hydrographs can be developed?

Answer 3

using measured flow and rainfall data OR generated using theoretical equations which relate runoff response to physical catchment attributes

Question 4

What is Snyder’s Unit Hydrograph based on?

Answer 4

channel length, length of main channel from outflow point of watershed to point opposite centroid of watershed, watershed area, empirical parameters

Question 5

What process is used to generate a Storm Hydrograph with a Unit Hydrograph?

Answer 5

convolution, numerous short duration storm hydrographs are lagged and added together to build a full storm hydrograph