ABSTRACT
As with the variances in the methods used to define and determine “physical, chemical, and biological integrity,” a number of definitions have been developed for restoration. One common difference in the definitions is in the stated goals of what condition, by restoration, a river should be returned “to.” For example, the U.S. Environmental Protection Agency (U.S. EPA) (USEPA 2000) defined restoration as “the return of a degraded ecosystem to a close approximation of its remaining natural potential.” Cairns (1991) defined restoration as the “complete structural and functional return [of the river] to a pre-disturbance state.” Similarly, the Society for Ecological Restoration Science and Policy Working Group (2002) indicates that restoration may be thought of as an “attempt to return an ecosystem to its historic (predegradation) trajectory.” In addition, a variety of other terms have been associated with river restoration, such as (Shields et al. 2003a, 2008; National Research Council 1992; Brookes and Shields 1996; FISRWG 1998):
• Rehabilitation: Activities to facilitate the partial recovery of ecosystem processes and functions, making them useful again, such as restabilizing a riverbank
• Preservation (or protection, maintenance): Activities to maintain the current functions and characteristics of an ecosystem or to protect it from change or loss
• Mitigation: Activity to compensate for or alleviate environmental damage, such as creating wetlands to mitigate the loss of wetlands elsewhere
• Naturalization: Activity that results in creating a natural and sustainable environment, although not necessarily that which existed prior to the disturbance
• Creation: Activities to create a new system that does not currently exist, such as a wetland or a riparian zone
• Enhancement: Activities to improve some aspect of the existing system’s quality, such as riparian vegetation
• Reclamation: Traditionally used to adapt systems to human needs (such as “reclaim” or drain wetlands), but now commonly used to refer to bringing about a stable, self-sustaining ecosystem (but not necessarily the original ecosystem)
Restoration projects do not necessarily return a river or a stream to its undisturbed or natural condition, because either that condition is not well described or a complete return is not feasible. As a result, Copeland et al. (2001) suggested that a realistic goal of a restoration project should be a partial recovery of the natural geomorphic, hydraulic, and ecological functions of the stream. In
this chapter, we will first review some of the common causes of the degradation of the “physical, chemical, and biological integrity” and then some of the common methods used in restoration.
