Unit 1 – Supplementary Materials
• Hydrograph
• Worked examples
➢ Effective rainfall
➢ Runoff production
➢ Return period concept
• Risks and independent sequence
➢ example calculation
Unit 1 (Week 2) CIVE316 -- Prof Ping Dong -- 1
, Understanding flows
The hydrograph is a time-series of rainfall moving out of the
catchment (unit: m3/s)
Runoff = Hydrograph - Baseflow
Baseflow is the portion of the streamflow that is sustained between
precipitation events, fed to streams by delayed pathways. It should
not be confused with groundwater flow.
Unit 1 (Week 2) CIVE316 -- Prof Ping Dong -- 2
, Understanding flows
Baseflow separation is used to determine what portion of a
streamflow hydrograph occurs from baseflow, and what
portion occurs from overland flow.
Surface runoff hydrograph is derived by separating baseflow
from hydrograph
Straight line method:
Join the starting and end points of surface runoff by straight line
Area under the straight line is baseflow
Unit 1 (Week 2) CIVE316 -- Prof Ping Dong -- 3
• Hydrograph
• Worked examples
➢ Effective rainfall
➢ Runoff production
➢ Return period concept
• Risks and independent sequence
➢ example calculation
Unit 1 (Week 2) CIVE316 -- Prof Ping Dong -- 1
, Understanding flows
The hydrograph is a time-series of rainfall moving out of the
catchment (unit: m3/s)
Runoff = Hydrograph - Baseflow
Baseflow is the portion of the streamflow that is sustained between
precipitation events, fed to streams by delayed pathways. It should
not be confused with groundwater flow.
Unit 1 (Week 2) CIVE316 -- Prof Ping Dong -- 2
, Understanding flows
Baseflow separation is used to determine what portion of a
streamflow hydrograph occurs from baseflow, and what
portion occurs from overland flow.
Surface runoff hydrograph is derived by separating baseflow
from hydrograph
Straight line method:
Join the starting and end points of surface runoff by straight line
Area under the straight line is baseflow
Unit 1 (Week 2) CIVE316 -- Prof Ping Dong -- 3
