Hydrographs

Question 1

What do hydrographs show?

Answer 1

The discharge of a river at a given point over a period of time

Question 2

What is discharge?

Answer 2

Water which reaches the river channel by surface runoff, throughflow and baseflow

Question 3

How do you measure discharge?

Answer 3

Discharge= cross-sectional area X velocity
Units = m3/sec or cumecs

Question 4

What are the 8 factors controlling discharge and hydrograph shape?

Answer 4

Basin size, shape and relief
Types of precipitation
Temperature
Land use
Rock type
Soil type
Drainage density
Tides and storm surges

Question 5

Name all the variables on a hydrograph

Answer 5

Peak discharge
Falling or recession limb
Lag time
Rising limb
Stormflow
Baseflow
Bankful discharge
Time difference between end of storm and peak discharge
Peak rainfall
River in flood