Hydraulic Roughness of Ice Covers

Cold region rivers and canals covered with ice have been found to develop ripple-like reliefs on the ice underside causing head losses considerably in excess of those of smooth boundaries. Observations showed that ice thickness near the banks was several times that of the conveying part of the waterway. It is postulated that these features are caused by heat transferred from the bottom of the waterway. Note that observed ratios of wave height to wave length of the ripples do not exceed approximately 0.12. This is the approximate upper limit of wave index number of separation free flow over sinusoidal waviness. Some measured values of ice roughness coefficient (Mannings n) are given. A graph presenting a dimensionless solution for composite roughness coefficient as a function of ice underside and channel bed coefficients is included.