106
(Wohl et al. 2005). This definition is broad in that it allows for diverse interpretations of what constitutes improved. Improvements could include activities as diverse
as stabilizing banks to protect private property or introducing large wood to enhance
fish habitat (Abbe and Brooks 2011). Ecological river restoration can be further
specified as restoration that assists the recovery of ecological integrity in a degraded
watershed by reestablishing the processes necessary to support the natural river ecosystem within the watershed (Wohl et al. 2005). Restoration is sometimes distinguished from rehabilitation by emphasizing that restoration focuses on processes
that create and maintain a desired river condition, whereas rehabilitation is more
likely to focus on form, such as stabilizing stream banks or beds. In this chapter,
restoration is used in a broad, generic sense and includes rehabilitation.
Restoration designed to increase the esthetic appeal of a river has been undertaken for centuries. Kondolf (2006) traces the still-widespread preference for a
slightly sinuous channel bordered by open, park-like woodland to the parks designed
for wealthy British landowners by late eighteenth-century landscape architect
Capability Brown (Fig. 4.1). Restoration designed to enhance specific river functions also goes back more than century, primarily in the context of recreational fishing, as traced in detail by Douglas Thompson in his book The Quest for the Golden
Trout (Thompson 2013).
Restoration as a multibillion-dollar industry, however, is a phenomenon of the
very late twentieth and early twenty-first centuries (Bernhardt et al. 2005). The
objective of many restoration projects has shifted during this period. Many of the
first restoration projects focused on creating a desired channel configuration at the
reach-scale of tens to hundreds or thousands of meters in length, typically to enhance
fisheries, esthetic appeal, or to improve water quality. Recently, restoration has
focused more on creating desired processes, commonly for similar endpoints of
fisheries or water quality enhancement (Beechie et al. 2010; Wohl et al. 2015b).
Desired processes include channel-floodplain connectivity (Tockner et al. 1999;
Hughes et al. 2001; Shields et al. 2011; Gumiero et al. 2013), hyporheic exchange
(Hester and Gooseff 2011), ecological productivity (Lepori et al. 2005; Palmer et al.
2010a, b), longitudinal connectivity (Shafroth et al. 2010; Konrad et al. 2011), and
the space to adjust to changes in water and sediment inputs (Kondolf 2011).
Bernhardt and Palmer (2011) distinguish reconfiguration and reconnection.
Reconfiguration efforts are designed to change the physical structure of the river
corridor through reshaping, replanting, or reconstruction. Reconnection efforts
involve the removal or retrofitting of infrastructure that was previously installed to
limit connectivity within the river corridor, such as dams and levees. Although
reconnection or reconfiguration can be undertaken at any spatial scale, reach-scale
projects are more likely to focus on reconfiguration and watershed-scale projects on
reconnection (Wohl et al. 2015b). Kondolf et al. (2006) develop simple conceptual
models and bivariate plots to visualize how human alterations have changed different dimensions of connectivity and how restoration can mitigate these changes.
The majority of river restoration projects are undertaken in the United States
(Bernhardt et al. 2005, 2007), Europe and the UK (Brookes 1990; Sear 1994;
McDonald et al. 2004; Clifford 2012), and Australia (Brierley and Fryirs 2000,
4 Toward Sustainable Rivers and Water Resources
(Wohl et al. 2005). This definition is broad in that it allows for diverse interpretations of what constitutes improved. Improvements could include activities as diverse
as stabilizing banks to protect private property or introducing large wood to enhance
fish habitat (Abbe and Brooks 2011). Ecological river restoration can be further
specified as restoration that assists the recovery of ecological integrity in a degraded
watershed by reestablishing the processes necessary to support the natural river ecosystem within the watershed (Wohl et al. 2005). Restoration is sometimes distinguished from rehabilitation by emphasizing that restoration focuses on processes
that create and maintain a desired river condition, whereas rehabilitation is more
likely to focus on form, such as stabilizing stream banks or beds. In this chapter,
restoration is used in a broad, generic sense and includes rehabilitation.
Restoration designed to increase the esthetic appeal of a river has been undertaken for centuries. Kondolf (2006) traces the still-widespread preference for a
slightly sinuous channel bordered by open, park-like woodland to the parks designed
for wealthy British landowners by late eighteenth-century landscape architect
Capability Brown (Fig. 4.1). Restoration designed to enhance specific river functions also goes back more than century, primarily in the context of recreational fishing, as traced in detail by Douglas Thompson in his book The Quest for the Golden
Trout (Thompson 2013).
Restoration as a multibillion-dollar industry, however, is a phenomenon of the
very late twentieth and early twenty-first centuries (Bernhardt et al. 2005). The
objective of many restoration projects has shifted during this period. Many of the
first restoration projects focused on creating a desired channel configuration at the
reach-scale of tens to hundreds or thousands of meters in length, typically to enhance
fisheries, esthetic appeal, or to improve water quality. Recently, restoration has
focused more on creating desired processes, commonly for similar endpoints of
fisheries or water quality enhancement (Beechie et al. 2010; Wohl et al. 2015b).
Desired processes include channel-floodplain connectivity (Tockner et al. 1999;
Hughes et al. 2001; Shields et al. 2011; Gumiero et al. 2013), hyporheic exchange
(Hester and Gooseff 2011), ecological productivity (Lepori et al. 2005; Palmer et al.
2010a, b), longitudinal connectivity (Shafroth et al. 2010; Konrad et al. 2011), and
the space to adjust to changes in water and sediment inputs (Kondolf 2011).
Bernhardt and Palmer (2011) distinguish reconfiguration and reconnection.
Reconfiguration efforts are designed to change the physical structure of the river
corridor through reshaping, replanting, or reconstruction. Reconnection efforts
involve the removal or retrofitting of infrastructure that was previously installed to
limit connectivity within the river corridor, such as dams and levees. Although
reconnection or reconfiguration can be undertaken at any spatial scale, reach-scale
projects are more likely to focus on reconfiguration and watershed-scale projects on
reconnection (Wohl et al. 2015b). Kondolf et al. (2006) develop simple conceptual
models and bivariate plots to visualize how human alterations have changed different dimensions of connectivity and how restoration can mitigate these changes.
The majority of river restoration projects are undertaken in the United States
(Bernhardt et al. 2005, 2007), Europe and the UK (Brookes 1990; Sear 1994;
McDonald et al. 2004; Clifford 2012), and Australia (Brierley and Fryirs 2000,
4 Toward Sustainable Rivers and Water Resources