A catchment-scale approach to the physical restoration of lowland UK rivers

✍ Scribed by David M. Harper; Mohammad Ebrahimnezhad; Eliot Taylor; Steve Dickinson; Oliver Decamp; Giselle Verniers; Tony Balbi

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 201 KB
• Volume: 9
• Category: Article
• ISSN: 1052-7613
• DOI: 10.1002/(sici)1099-0755(199901/02)9:1<141::aid-aqc328>3.0.co;2-c

✦ Synopsis

1. This paper advocates a catchment-scale perspective for river restoration and for individual rehabilitation works even though, at present, such works are often small-scale and ad hoc in nature. The catchment-scale approach is the logical consequence of the application of fundamental principles of river science to the philosophy of river restoration.

2. The five principles that river restoration should incorporate are: i) the hierarchy of river systems; ii) the proportional relationships between discharge and channel dimensions; iii) the importance of the physical and biological continua of natural rivers; iv) the four-dimensional nature of river systems; and v) the role of heterogeneity in maintaining biodiversity and that of disturbance in maintaining heterogeneity.

3. Two sets of examples are given to illustrate the need for these five principles. One set relates to the role of trees in river processes (and in river restoration), while the other relates to the rehabilitation of physical structures in rivers at a different scale.

4. The value of trees both for the maintenance of water quality and for their conservation value in upper-order rivers is demonstrated. This, combined with evidence elsewhere for trees as an integral part of the river-riparian ecotone, suggests the restoration of lowland headwater streams as being totally tree-influenced. In middle and lower reaches of rivers, it is important to restore the river-floodplain interactions. Continuity with groundwater through the hyporheos as a result of riffle-pool rehabilitation and flood-regeneration of meadows and alluvial forests should be the long-term vision for lower-reach restoration.

5. In the interim, piecemeal rehabilitation of the physical heterogeneity of the bed and banks in large rivers can be locally successful provided that it restores coarse particles and interstices where they are absent through artificial material and/or siltation, but not if it fails to recognize fully the importance of replacing lost heterogeneity.