Geology Reference
In-Depth Information
elsewhere in river systems, produced a spur for changes in
management practices. Mounting evidence and theory
demanded a geomorphological approach to river man-
agement (e.g. Dunne and Leopold 1978; Brookes 1985).
Thus, to control bank erosion in the UK, two major
changes in the practices and perceptions of river man-
agers took place. First, they started thinking about bank
erosion in the context of the sediment dynamics of
whole river systems, and began to examine upstream and
downstream results of bank protection work. Second,
they started prescribing softer, more natural materials
to protect banks, including both traditional vegetation,
such as willow, osier, and ash, and new geotextiles to
stimulate or assist the regrowth of natural plant cover
(Walker 1999). River management today involves scien-
tists from many disciplines - geomorphology, hydrology,
and ecology - as well as conservationists and various user
groups, such as anglers (e.g. Douglas 2000). Thus, in
Greater Manchester, England, the upper Mersey basin
has a structure plan that incorporates flood control, habi-
tat restoration, and the recreational use of floodplains;
while, in the same area, the Mersey Basin Campaign
strives to improve water quality and river valley ameni-
ties, including industrial land regeneration throughout
the region (Struthers 1997).
climate, vegetation cover, and land-use. Many river
valleys record a history of changing conditions during
the last 10,000 years, induced by changing climates and
changing land-use, that have produced adjustments in
the fluvial system. Human agricultural, mining, and
urban activities cause changes in rivers. Overall, they
increase the flux of fluvial sediments. Dams affect stream-
flow, sediment transfer, and channel form downstream.
Human actions modify many rivers, which need manag-
ing. Fluvial geomorphology lies at the heart of modern
river management.
ESSAY QUESTIONS
1 How would you convince a sceptical
friend that rivers carved the valleys
they flow through?
2 Why do river channel patterns vary?
3 To what extent have humans
modified fluvial landscapes?
FURTHER READING
Acreman, M. (2000)
The Hydrology of the UK: A Study
of Change
. London: Routledge.
Not strictly geomorphology, but highly relevant to the
subject.
SUMMARY
Flowing water is a considerable geomorphic agent in
most environments, and a dominant one in fluvial envi-
ronments. It carves many erosional landforms, including
rills and gullies, bedrock channels, and alluvial chan-
nels. River profiles, drawn from source to mouth, are
normally concave, although they often possess knick-
points marked by steeper gradients. Rivers form networks
that may be described by several geometrical and topo-
logical properties. Valleys are an overlooked erosional
landform. Flowing water deposits sediment to build
many depositional landforms. The smallest of these are
features on channel beds (riffles and dunes, for exam-
ple). Larger forms are floodplains, alluvial fans, playas,
river terraces, and lake deltas. Flowing water is sensitive
to environmental change, and especially to changes of
Bridge, J. S. (2003)
Rivers and Floodplains: Forms,
Processes, and Sedimentary Record
. Oxford: Blackwell Sci-
ence.
A useful text for more advanced readers.
Brookes, A. J. and Shields, F. D. (1996)
River Channel
Restoration: Guiding Principles for Sustainable Projects
.
Chichester: John Wiley & Sons.
If you are interested in applied fluvial geomorphology,
try this.
Jones, J. A. A. (1997)
Global Hydrology: Process, Resources
and Environmental Management
.
Harlow,
Essex:
Longman.
Gives a hydrological context for fluvial processes.
