Dominant Discharge as a Design Criteria in River Restoration

Field studies by fluvial geomorphologists provide valuable information about the existing characteristics, stability, and likely pattern of evolution of an alluvial river system . If the existing or future conditions are found to be unsatisfactory for ecological or land use reasons, restoration or enhancement measures may be attempted. Experience during the past two decades has shown that the greatest chance for successful ecological restoration occurs if the natural physical processes are accommodated, rather than forcing a local reach into an unnatural or static configuration. This restoration approach requires an understanding of the natural form of the river channel under dynamic equilibrium conditions. One of the design parameters is the concept of the dominant (or channel forming) discharge. Quantitative approaches for estimating the dominant discharge are presented and the reason for the robustness of this design parameter is demonstrated.