Environmental Engineering Reference
In-Depth Information
Left bank
untouched
Spoil used by
landowner on sit
e
2 m wet berm
created
99
Old bank profile
Summer
water level
98
97
96
Silt accretion
and berm extension
Low herby vegetation
(water mint, etc.)
As-dug profile
-5
0
5
10
15
Distance (m)
Fig. 11.5
Creation of on-line bay by re-profiling an old bank on the River Tall, Moy, County Armagh, Northern
Ireland. M.O.D., ordnance datum (in metres).
increased biodiversity, but this is by no means always
the most appropriate method. The recovery of an eco-
system may for example be assisted by less-radical
restoration principles such as re-profiling river banks
and creating wet berms as shown in Fig. 11.5. The fol-
lowing section provides a few examples of the types of
issue impacting rivers and floodplains and also out-
lines those factors that are driving river restoration in
various countries across Europe. The list is by no means
comprehensive and many more examples can be found
in a variety of textbooks (including Ward
et al.
1993,
Middelkoop & Van Haselen 1999, Klijn & Dijkman
2001, Nijland & Cals 2001) and the River Restoration
Centre's
Update for the Manual of River Restoration
Techniques
(RRC 2002); see below for further details.
In the 1980s conservation and river enhancement
was restricted to voluntary bodies and were seen as
add-on works to the statutory duties of flood defence,
fisheries and water quality. Many rivers were still seen
as efficient conduits for the evacuation of troublesome
water. In the early 1990s concern for the UK's rivers
led to the formation of the River Restoration Project
(RRP), and the design and implementation of two RRP
river-restoration demonstration projects on the Rivers
Cole and Skerne. This work, funded by an EU LIFE
grant and in conjunction with works in Denmark (e.g.
the River Brede), acted as a catalyst for change, sup-
porting a rising number of restoration and enhance-
ment projects in the last 10 years. The UK now has
an established River Restoration Centre (RRC) whose
single aim is to provide information and advice on river
management for restoration and enhancement. The
Centre has an inventory of over 900 river-restoration
projects and has produced a manual detailing 47 river-
restoration techniques from 17 UK projects (RRC 1999,
2002, CIRF 2001).
11.5.1 UK
In the UK, rivers have been substantially altered
over the past few centuries, with at least 80% of low-
land river reaches having had at least part of their
channel modified (Raven
et al.
1998). Degradation has
been particularly severe in the last 50 years through
intensive management. Programmes of draining,
dredging and straightening have touched almost all
rivers. Since 1990, various groups and government
agencies have been working to change the perception
of river managers and to promote a more sustainable
approach to river and floodplain use and river man-
agement, rather than purely flood defence.
The River Skerne restoration project
The urban River Skerne in Darlington, County
Durham, had been progressively straightened and
re-aligned during a period of industrial and urban
housing development over a period of some 200 years.
A 2-km reach was chosen for rehabilitation. The works
aimed to re-create a more naturally functioning water-
course which would become an attractive landscape
