River Discharge Flashcards
Define River Discharge
The volume of water that flows in a river per second.
Measure of River Discharge
Cumecs (cubic metres per second) (m^2/s)
What do hydrographs shows?
Shows how the discharge at a certain point in a river changes over time
What does a storm hydrograph do?
It shows the changes in river discharge around the time of a storm.
Define some basic features of a hydrograph
Peak Discharge, Lag time, Rising Limb, Falling limb
Define Peak Discharge
The highest discharge in the time period
Define Lag time
The delay between peak discharge and peak rainfall
Define Rising Limb
The increase in water discharge as rainwater flows into the river
Define Falling Limb
The decrease in river discharge as the river returns to its normal level
Reason for Lag time
Rainwater does not always land directly into the river. There is a delay. It has to reach the river through transfers such as surface runoff and infiltration.
Describe hydroggraph for Urban area
They have drainage systems and covered with impermeable materials which increase discharge so the hydrograph is steeper
Describe hydroggraph for Rural area
They have vegetation which decrease discharge due to interception. They have less drainage systems and less impermeable buildings or roads.
Factors increasing discharge (steeper hydrograph)
. Heavy rainfall . Impermeable Rock . Less vegetation . Steeper Ground . Previously wet conditions . Freezing conditions/ hot dry conditions . More drainage systems
Factors decreasing discharge (gentler hydrograph)
. Low rainfall . Permeable Rock . More vegetation . Mild conditions . Less drainage systems
