Abstract:

Aquatic ecosystems worldwide are being severely altered or destroyed at a rate greater than they are being restored (NRC, 1992). According to the 1994 National Water Quality Inventory of 617,806 miles of rivers and streams, only 56 percent fully supported multiple uses, including drinking water supply, fish and wildlife habitat, recreation, and agriculture, as well as flood protection and erosion control ( FISRWG, 2001). In 2005, the National River Restoration Science Synthesis (NRRSS) working group released the results of a multi-year study of the motivations and subsequent performance of completed river restoration projects within the United States. Through the development of a comprehensive database, the study found that although over $1 billion is spent on restoration projects each year, it was found that more than half the projects failed to meet the intended goals and design criteria (Kondolf and Downs, 2004 ).

River restoration is not a mature science (Brookes and Shields, 1996) and there exists significant gaps in scientific knowledge of river restoration, as well as undetermined biases and errors in the current empirical design formulations and numerical models, resulting in 'uncertainties' that dramatically impact the outcomes of these projects.

River restoration projects fail through the omission of essential parameters in the development and configuration of the project. In order to achieve reliable river restoration projects it is essential that the problem to be remedied is completely and comprehensively defined; that project-related uncertainties (i.e. physical, temporal, financial) be acknowledged, estimated, and accounted for; and interactive management approaches (such as adaptive management) be configured and employed to manage those parameters identified as having significant influence on the project and high magnitudes of uncertainty.

River restoration is evaluated from a life-cycle perspective. Additionally, reliability is a central theme of the research. By including reliability into river restoration, it becomes possible to directly incorporate project performance as well as the plethora of uncertainties that plague many river restoration efforts from achieving their intended outcomes.

Through literature reviews, this research synthesizes the current interdisciplinary river restoration body of knowledge (classified by NRRSS goal categories) and created a river restoration 'checklist' with associated resources (planning guides, design manuals, computer software programs, and GIS data) for planning and design to correlate minimum project requirements with intended restoration goals. Case studies are presented for validation and the case studies also present management strategies for restoration uncertainties and adaptive management.