Stream restoration and mitigation is a complex process that involves recognizing natural and human induced disturbances that degrade the form and function of stream and riparian ecosystems or prevent its recovery to a sustainable condition. Restoration includes a broad range of activities designed to enable stream corridors to recover dynamic equilibrium and function to maintain channel dimension, pattern, and profile so that over time the stream channel does not degrade or aggrade. The Stream Corridor Restoration: Principles, Processes, and Practices manual published by the Federal Interagency Stream Restoration Working Group in 1998 identifies three levels of stream improvement: 1) restoration, 2) rehabilitation, and 3) reclamation. Restoration is defined as the reestablishment of the structure and function of ecosystems. Ecological restoration is the process of returning an ecosystem as closely as possible to predisturbance conditions and functions. Ecosystems are dynamic and therefore it is not possible to recreate a system exactly. The restoration process reestablishes the general structure, function, and dynamic but self-sustaining behavior of the ecosystem. Rehabilitation is defined as a procedure for making the land useful again after a disturbance. It involves the recovery of ecosystem functions and processes in a degraded habitat. Rehabilitation does not reestablish the predisturbance condition but does establish geological and hydrologically stable landscapes that support biological diversity. Reclamation is defined as a series of activities intended to change the function of an ecosystem, such as changing wetland to farmlands.
For this project, stream restoration is defined as returning a degraded stream ecosystem to the highest level of stream potential available for the surrounding landform. This includes reestablishment of stream channel that maintains its dimensions, pattern and profile such that over time it does not aggrade or degrade. This definition also implies that the restoration will provide the highest level of aquatic habitat and biological diversity possible.
This project included a thorough review of scientific literature related to stream restoration techniques and practices in addition to development of a design handbook. Literature review topics included fluvial processes, bioengineering, natural channel design, habitat improvement structures, stream stability, and sediment transport. An annotated bibliography of the relevant stream restoration literature was posted to the NCSU Water Quality Group Web Site at: http://www.bae.ncsu.edu/programs/extension/wqg/
The document "Stream Restoration: A Natural Channel Design Handbook" was prepared and distributed to 35 NCDOT participants in a 4-day workshop held in Raleigh, NC January 22-26, 2001. The Handbook includes detailed descriptions of successful current and proven stream restoration practices integrated into a usable and reliable cost-effective process for NCDOT. Chapter 11 in the Handbook is a comprehensive process to support evaluation of successful stream restoration.
