What does a hydrograph show?
Two graphs - a bar chart showing rainfall and a line graph showing discharge from before, during and after the rainstorm shown in the bar graph
The differences between two rivers over time
One graph - a line graph showing discharge from before, during and after the rainstorm
What is meant by the term 'rising limb'?
This indicates the speed at which the river returns to its previous state before the storm
This indicates how quickly the level of water in a river rises after a storm
The amount of water discharged by the basin in an allotted time
What is meant by the term 'lag time'?
This is the difference in time between the height of the storm and the highest flow of the river
The time over which the runoff is measured
The difference between the amount of water in the river at the beginning and end of the storm
What effect does a steep slope have on a storm hydrograph?
Flow tends to be faster down a steep slope, resulting in a shallower rising limb and a longer lag time
Flow tends to be slower down a steep slope, resulting in a steeper rising limb and a shorter lag time
Flow tends to be faster down a steep slope, resulting in a steeper rising limb and a shorter lag time
What effect does rock type have on a hydrograph?
Rock type has no effect on a hydrograph
Permeable rocks mean rapid infiltration and little overland flow, resulting in a shallow rising limb
Impermeable rocks will lead to a decrease in overland flow and a shallow rising limb
What effect does urbanisation have on a hydrograph?
Urbanisation, with bare concrete and tarmac, form impermeable surfaces, creates a steep rising limb and shortens the time lag
Urban areas have longer lag times and shallower rising limbs
Urbanisation has no effect on a hydrograph
Look at the diagrams of Areas A and B. Which of the following statements is true?
Diagram A
Diagram B
Diagram A and B would produce the same hydrograph
Diagram A would produce a hydrograph with a steeper rising limb and a shorter lag time than Diagram B
Diagram A would produce a hydrograph with a shallower rising limb and a longer lag time than Diagram B