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

Abstract

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. Copyright © 1999 John Wiley & Sons, Ltd.

Mapping and analysis of changes in the riparian landscape structure of the Lockyer Valley catchment, Queensland, Australia

“…from headwaters to the mouth of rivers) as well as transverse structures (i.e. the cross section of the flood plain), whose functions and effects to ecological processes vary considerably (Harper et al, 1999;Boon, 1998). Thus, buffering was used in the absence of a more reliable and less complicated mapping technique for the riparian zones.…”

“…If left unabated, the continuous misuse of these resources could bring further ecological problems and economic losses. Hence, there is a need to effectively manage these areas through restoration, rehabilitation, conservation or preservation programmes (Schiemer et al, 1999;Cals et al, 1998;Harper et al, 1999;Piegay and Landon, 1997).…”

Methods to prioritize placement of riparian buffers for improved water quality

“…Including trees in buffers can influence shallow groundwater flow through increased transpiration, even in temperate climates (Komor and Magner 1996;Wagner and Bretschko 2003). Also riparian trees help reduce or denitrify groundwater nitrate (Haycock and Pinay 1993), and provide a range of benefits to aquatic ecosystems (Harper et al 1999). Studies on environmental effects of harvesting trees in riparian buffers are also published (Hubbard and Lowrance 1997;Liquori 2006).…”

Evaluation of the ecological status of an impaired watershed by using a multi-index approach

“…Restoration techniques are often directed towards the reestablishment of natural physical environment, including the riparian gallery (Harper et al 1999;Naiman and Décamps 1997;Piégay and Landon 1997). Many authors have demonstrated significant improvements in water quality and aquatic communities (Lazdinis and Angelstam 2005;Thoms and Sheldon 2000;Vought et al 1995), achieved following rehabilitation of riparian ecotones (Mander et al 1995;Robertson and Rowling 2000;Vought et al 1995).…”