Abstract

To restore a stream to a more natural condition and still minimize flooding and erosion, the optimal longitudinal bed slope and meander sinuosity are needed. A straight channel can reduce flooding but cause excessive velocity and concomitant bed degradation, incision, and riverbank collapse. Conversely, a highly meandering channel will have slower velocity but higher flow depths that can lead to flooding. A meandering channel provides for the diversity of habitat needed for the ecosystem to be healthy. Balancing these needs can be difficult. To aid in the selection of bed slope and sinuosity, the optimal slope was found here using a multi-objective optimization formulation that minimizes both flooding and erosion. The Pareto front was established and the closest point to the origin of zero depth and velocity was the optimal combination of these two inversely proportional variables. It was found that, for a wide range of channel roughness, width, and flow values, a slope of approximately 0.0002-0.0004 was desirable.

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