Storm Hydrograph Flashcards
What is river discharge and what measurement is used?
River discharge is the volume of water that passes a measuring point in a river over a period of time.
Measured in cumecs (cubic metres per second).
What does a storm hydrograph show?
It shows the changes in discharge over time.
What is base flow?
The “normal” level of flow in the channel without rainstorm effects.
What is rising limb?
This is the rise in discharge from base level to peak discharge.
What is peak discharge?
This is the highest level of flow in the channel.
What is receding limb?
This is the fall in discharge from the peak back to the base level.
What is the lag time?
This is the delay between maximum rainfall and peak discharge.
How might building roads impact the river during a storm?
- Increases area of impermeable surface.
- Water reaches channel quicker due to surface run-off.
- Leads to reduced lag time and increased peak discharge.
How might straightening river channels impact the river during a storm?
- Cause quicker delivery of water to downstream areas.
- Increase the risk of flooding downstream of the urban area, as the velocity will be faster.
How might building drains and sewers impact the river during a storm?
- Increases speed of transport of water into river channels.
- Reduces lag time.
