STREAM RESTORATION
Stream
Restoration Projects
Sediment
Generation|Surface-Subsurface
Flow Interactions, Nevada|
Anthropogenic and Natural Disturbances
on River Systems, Central Nevada
____________________________________________________________________
Sediment Generation and Transport
River Restoration
In its purest form, stream restoration is defined as the structural and functional return of a degraded riverine ecosystem to its pre-disturbance condition (Berger, 1990; National Resources Council, 1992). The pre-disturbance condition is generally taken as the state of the river prior to European settlement. This ideal objective can rarely, if ever, be achieved because we seldom understand what the structure, function, composition or dynamics of an ecosystem was in pre-Colombian times (National Resource Council, 1992; Hobbs and Norton, 1996). Even if the natural characteristics of the river system were known, the pre-disturbance condition may not fit the modern stable state(s) because of alterations in climate, land-use and system hydrology (Wade et al., 1998). Therefore, some investigators have redefined restoration to mean the return of a degraded ecosystem to a close approximation of its remaining natural potential (USEPA, 2000). Others have chosen to keep the original definition of restoration intact, and to use alternative terms to describe the current global manipulation of stream channels to a more natural state. Perhaps the most commonly used alternative is river rehabilitation which has gained widespread acceptance in the U.K. (see, for example, Waal et al., 1998). I like to think of restoration as the return of a riverine ecosystem to a more natural working order that is not only sustainable over the long-term, but aims to recreate rivers that are more productive, aesthetically appealing, and valuable from a conservation perspective (after Hobbs and Norton, 1996).
Attempts at river restoration have increased dramatically in recent years, both in the U.S. and abroad. The growth of restoration is due, in part, to an increasing commitment by federal and state governments to fund site-specific programs. Take, for example, current federal initiatives which call for the restoration of 25,0000 miles of stream corridor and the re-establishment of approximately 2,000,000 miles worth of buffer zones (USEPA, 2000). The costs for these initiatives will undoubtedly range in the hundreds of millions of dollars. While numerous successes have been described in the literature (National Resources Council, 1992; FISRWG, 1998), it is recognized that riverine ecosystems are extremely complex and their response to physical and biological manipulations are not easy to predict. In fact, many have completely failed, costing taxpayers thousands of dollars in unrealized benefits. The reasons for less than successful projects are numerous, but it is often related to an incomplete understanding of the processes functioning within the river system, particularly with regards to the responses of river systems to both natural and anthropogenic disturbance. My colleagues and I are currently documenting the responses of fluvial systems in central Nevada and western North Carolina in order to develop sound restoration programs.
References Cited Above
Berger, J.J. 1990. Evaluating Ecological Protection and Restoration Projects: A Holistic Approach to the Assessment of Complex, Multi-Attribute Resource Management Problems. Doctoral dissertation. University of California, Davis.
FISRWB (The Federal Interagency Stream Restoration Working Group). 1998. Stream Corridor Restoration: Principles, Processes, and Practices. National Engineering Handbook, NEH 653.
Hobbs, R.J. and Norton, D.A. 1996. Towards a conceptual framework for restoration ecology. Restoration Ecology 4: 93-110.
National Research Council, 1992. Restoration of Aquatic Ecosystems. National Academy Press, Washington D.C. USEPA, 2000. Principles for the Ecological Restoration of Aquatic Resources. EPAA841-F-00-003. Office of Water (4501F), United States Environmental Protection Agency, Washington, D.C., 4 p.
Waal, L.C., Large, A.R.G., and Wade, P.W. (editors). 1998. Rehabilitation of Rivers: Principles and Implementation. John Wiley and Sons, Chichester.
Wade, P.W., Large, A.R.G., and De Waal, L.C. 1998. Rehabilitation of debraded river habitat: an introduction. In: L.C.
Waal, A.R.G. Large, A.R.G., and P.W. Wade, editors, Rehabilitation of Rivers: Principles and Implementation. John Wiley and Sons, Chichester.