Discharge relationships: Flashcards
contains: hydrograph components definitions and storm processes
Hydrograph
A hydrograph plots river discharge against time, and shows the river’s regime. Used to understand nature of a drainage basin and factors that affect discharge.
Annual Hydrograph (river regime)
to study responses of the river to its environment; highlights seasonal characteristics, therefore biggest influencer is climate.
Storm Hydrograph
shows variations of river discharge over a short time period. Includes both discharge and rainfall on the y-axis.
Cumecs
cubic metres per second. Unit of discharge.
Approach Segment
discharge prior to storm.
Rising Limb
shows quick rise in discharge.
Bank full Discharge
channel full. Any further increase in discharge = flood.
Peak Discharge
maximum river discharge.
Lag Time
time between max rainfall and max discharge.
Receding Limb
less steep than rising, shows discharge decline after peak discharge.
Stormflow
stream discharge after rainstorm.
Quickflow
surface runoff reaches channel quickly.
Storm Process
Rain falls on drainage basin in large amounts.
Overland flow occurs as precipitation > infiltration rate. Rising limb builds to peak.
After a few hours, overland flow reduces and stops. Throughflow then contributes to discharge and stops floodwaters going down as quickly as they rose.
Baseflow takes over – back to pre-flood state.
