Environmental Engineering Reference
In-Depth Information
Left bank
untouched
Spoil used by
landowner on site
2 m wet berm created
(bur-reed, etc.)
99
Old bank profile
Summer
water level
98
97
96
Silt accretion
and berm extension
Low herbaceous vegetation
(water mint, etc.)
As-dug profile
-5
0
5
10
15
Distance (m)
Figure 17.3
Creation of online bay by reprofi ling an old bank of a previously trapezoidal channel. Herbaceous - herbaceous
vegetation; water mint -
Mentha aquatica
; as - dug profi le - refers to the designed dug profi le for the specifi c project; and
ordnance datum (m) - height above sea level.
defence, fi sheries and water quality. Many rivers were
still seen as effi cient conduits for the evacuation of
troublesome water. In the early 1990s, concern for the
United Kingdom's rivers led to the formation of the
River Restoration Project, and the design and imple-
mentation of two RRP 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,
supporting a rising number of restoration and
enhancement projects in the last 10 years. The RRC is
now well established in the United Kingdom with the
principle aim to provide information and advice on
river management for restoration and enhancement.
The RRC holds the National River Restoration Inven-
tory of over 2000 river restoration projects and has
produced a manual detailing 47 river restoration tech-
niques from 17 UK projects (RRC 1999, 2000; Centro
Italiano per la Riqualifi cazione Fluviale (CIRF) 2001).
One example of restoration to 're-meander' a river in
the United Kingdom is presented in Box 17.1 and
depicted in Figure 17.4 .
The aspiration to restore rivers continues, but the
focus is now on delivering individual projects within
the context of linking projects benefi ts at a catchment
scale. The London Rivers Action Plan (http://
www.therrc.co.uk/lrap.php) is an example of this
approach, through improving urban watercourses,
and includes examples of restoration work within the
River Thames catchment, such as de-culverting (River
Ravensbourne at Norman Park), re-meandering (River
Quaggy at Chinbrook Meadows, River Brent at Toking-
ton Park, River Roding at Ray Lodge Park), the removal
of tidal sluice gates (Rainham Creek) and the creation
of wetland habitats (Watermeads Island on the River
Wandle).
Denmark
It is estimated that 97% of Denmark's 40 000 km of
natural rivers have been altered in their physical form
(Brookes 1984 ). In addition, another 30 000 km of
human-made watercourses exist; these channels were
designed to drain wetlands and fl oodplains and to
increase agricultural production. Much of the work to
drain Denmark was undertaken in the twentieth
century, together with fi sh farming and industrial and
urban expansion. Channelization was also frequently
accompanied by mills and other structures, effectively
denying free passage to fi sh and macro-invertebrates.
Through legislation and changes to the administration
of Danish watercourses, management improvements
and river restoration have been implemented since the
mid-1980s. Twenty-four such schemes are detailed in
Hansen (1996). Many of these are intended to natural-
ize the physical form after water quality standards have
been achieved. In 1996, arising from a joint Danish-
UK collaboration, Denmark became the fi rst base for
the European Centre for River Restoration. Since that
time, the directorate of the centre has passed through
various member states and is currently housed in the
Netherlands. Two effective examples of restoration in
