978-0-00-812422-9 COLLINS CAMBRIDGE AS AND A LEVEL GEOGRAPHY

River groups
Group 1
Group 2
Group 3
Group 4
Group 5
Group 6
Group 7
Group 8
Group 9
Group 10
Group 11
Group 12
figure 1.8 (a) Drainage patterns in France. The map shows the drainage basins colour coded to their respective graphs on the facing page.
Storm hydrographs
Hydrographs enable us to look at the relationship between rainfall and
discharge after each rainfall event as river levels top up and subsequently
drop over time. The response of a catchment to a rainfall event may be rapid
or gradual depending on many factors (outlined below). The shape of the
hydrograph may reflect the speed at which the water has travelled and the
obstacles and stores in its way.
Hydrographs are particularly important for identifying the potential risk of
flooding to an area.
There are several key features to any hydrograph. They represent the various
stages to the graph and help to identify the nature of the discharge. Most
hydrographs show time or duration on the x-axis followed by two scales on
the y-axis – one for the rainfall/precipitation and one for discharge. Be sure to
identify which is which.
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Hydrology and fluvial geomorphology