Geoscience Reference
In-Depth Information
Ex-TC Sid (embedded
in monsoon trough)
(a)
Monsoon trough
and TC Steve
12000
Low pressure system.
Record rainfall in parts
of Burdekin catchment
10000
TC Justin
Low pressure
system along
coast
8000
TC Ita
TC Barry (Gulf
of Carpenteria)
6000
Monsoon low
TCs in
coral Sea
4000
TC Gillian
2000
0
1995 1996 1997 1998 1999 2000
12000
(b)
Discharge
SSC
900
800
700
600
500
400
300
200
100
10000
8000
6000
4000
2000
22 23 24 25 26 27 28 29 1 2 3 4 5 6 7 8
February March
Fig. 1.12
(a) Data from hydrographs recording fluvial discharge between 1995 and 2000 in the lower part of the Burdekin River
catchment. (b) Detail of discharge and suspended sediment concentrations (SSC) between February and March 2000. Note that
SSC generally decreased through the discharge event and that, in this catchment, SSC levels appear to be supply limited.
(Adapted from Amos et al. 2004.)
system response occur, for example, in areas
where construction or resource extraction activ-
ities in the upstream sectors of catchments result
in downstream sediment starvation and/or ero-
sion. At a global scale, the transport of sediment
through river systems represents a major path-
way of sediment movement from upland 'source'
to marine 'sink'. The transport of such sediment-
ary material is, however, highly sensitive to
a range of anthropogenic influences, including
reservoir construction, land-use change, soil and
water conservation activities, and sediment con-
trol programmes (Walling & Fang 2003). Some
of these activities lead to increased sediment loads
but others, and in particular reservoir construc-
tion, lead to reduced sediment transport. The
impacts vary between catchments, but in some
regions reduced sediment supply has resulted in
marked changes in the behaviour and geomor-
phology of fluvial systems (see Chapters 2 and
3). In the Alpine region of Europe, for example,
sediment deficits have been recorded in many
rivers over the past 30 - 40 years. Such reduc-
tions have resulted from excessive gravel extrac-
tion from rivers and the retention of sediment
behind dams. The result, on many upland rivers,
has been widespread erosion and entrenchment
(Descroix & Gautier 2002).
