TAKING CONCEPT TO DESIGN: TRANSLATING GEOMORPHIC ANALYSIS INTO SUCCESSFUL RIVER RESTORATION ENGINEERING

River restoration projects often develop via regulatory and planning processes that include separate conceptual, permitting and engineering design phases. Transferring knowledge of restoration functions among scientists, planners and engineers is a critical element of the restoration design process, but one that is often under appreciated. Scientists typically view projects from the perspective of understanding complex interactions among process and function, while engineers often view projects in terms of form and implementation. More effective designs can be accomplished when scientists can articulate a vision beyond broad objectives (e.g. restoring floodplain connectivity) by translating key concept components into specific design functions (e.g. increase frequency of overbank flooding to improve soil water storage capacity thus increasing vegetative diversity and improving baseflows). Often, this requires identifying specific functional requirements during concept design phases that describe not only the form of restoration, but the intended functions and the ecogeomorphic constraints associated with those functions. Such an approach is important when restoring floodplain river reaches, since desirable functions often rely upon co-dependent relationships between floodplain maintenance and storage processes, sedimentation controls, flow conveyance and the dynamic response in the geomorphic character of the river. Simply restoring the form of a river to one that existed under a previous time period or land-use is unsustainable without thoroughly understanding how key supporting processes and functions have changed, and how the new process regime can sustain designed forms. Therefore successful long-term restoration requires that designers articulate how to restore specific functions and processes of the river/floodplain system so that they respond well to imposed modifications. Examples from specific project will be discussed.