Uncertainty surrounding ice and sediment interaction introduces a high-level risk in the design of contaminated sediment remediation measures in rivers. Because much of the historic industrial activity in the United States is concentrated along northern rivers, many contaminated sediment sites are ice-affected. Furthermore, a high level of design uncer-tainty and risk results from a lack of adequate analytical or numerical models to predict sediment transport under ice covers. Significant amounts of contaminated sediment can pose potential risk to habitat and human health. The presence of ice has a range of possible influences on the sediment regime. A floating ice cover can dramatically increase turbulent shear stress on the bed, thereby causing peak annual sediment-transport events for northern rivers to occur during the dynamic breakup of an ice cover or the release of a breakup ice jam. These events often involve high discharges, with gouging and abrasion of the bed and banks by moving ice. Ice in a river channel can reduce the flow area, increasing under-ice water velocity, scouring bed sediments, and possibly shifting the path of the deepest flow. Ice accumulations also may impinge flow against the channel sides, thus contributing to bank erosion.
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Description of Research