Ice Engineering. Method to Evaluate Potential for Ice Impacts on Sediment Stability

摘要

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 uncertainty and risk results from the fact that no adequate analytical or numerical models exist to predict sediment transport under ice covers. This technical note presents a practical method to assess ice jam occurrence and evaluate potential for ice-related impacts on sediment stability. The approach combines a review of historical ice jam information and analyses of geomorphic and hydrometeorological data with field observations. The primary objectives of the method are to determine if and where ice events occur. and whether or not these events affect sediment stability at locations of interest. This type of evaluation can be accomplished quickly and at a reasonable cost. If it is found that ice-related transport of contaminated sediment has occurred, or is a real possibility, further investigation would be required. This could consist of bathymetric surveying and sediment sampling in suspected ice jam scour areas. Analysis of river-bed stratigraphy can provide more information on where and when ice-hydraulic scour and deposition occurred. Detailed numerical modeling of ice events can be used to calculate average under-ice water velocities and provide approximate estimates of shear stresses on the sediments.