Physically based coefficient for streamflow estimation in ice-covered channels

Measuremental and methodological problems arising from the presence of ice cover on waterways have seriously hindered the progress in predicting timely and accurate streamflow, which is a prerequisite for the effective management of ice-covered waterways (e.g. streams, rivers, channels, and canals). Among various methods in the attempt to address this issue, the most attractive is the physically-based method, which does not require abundant, and often unobtainable, data. This paper develops a physically based K-factor method, in the form of a generalized Manning equation, for discharge estimations in ice-covered channels. The main advantage of this method is that it enables the prediction of streamflow in ice-affected seasons by a K-factor adjustment of the stage-discharge relationship developed in the open-water seasons. The results of parameter estimation show that the K-factor is only related to the boundary resistance ratio, which is parameterized by two exponents of the two-power law for describing the vertical streamwise velocity profile. Experimental measurements collected from the literature were used to test the applicability of the proposed formula, and to compare its relative accuracy with the Sabaneev and Larsen formulae. The comparative results indicate that the proposed method is more accurate in estimating streamflow of ice-covered channels than these two widely-used formulae based on traditional two-layer hypothesis.