Rainfall volume =
Bar chart x surface area
Lag time:
The time between max rainfall and peak discharge.
The return period, use for flood prediction, is…
The discharge plotted against time interval before a similar discharge occurs again.
The river stage (river height) is the….
Elevation of water surface above a fixed height - used for flood warnings.
Base flow (B) is estimated by
The horizontal line at the bottom of the stream discharge line.
Annual variation: (3)
Base flow maintains the flow of rivers in dry periods.
High base flow levels at the end of winter from seasonably high precipitation.
Decline throughout summer into autumn - evaporation is higher than precipitation.