Continuous measurement of the snow surface heightand ice bottom height in a frozen river

摘要

To obtain knowledge on the breakup phenomenon for use in the management offrozen rivers, non-contact continuous measurement of ice sheet thickness was con-ducted to examine the weather/hydraulic conditions that lead to breakup. From fieldobservations and numerical calculation, the process of the breakup phenomenon at theMaruyama Observatory of the Teshio River in the Japan was presumed to be as fol-lows: The flow rate increased as snow changed to rain with increased temperatures,thus causing the occurrence of breakup in the upper reaches. The flow rate increasedas river ice and water flowed down to the Maruyama Observatory, and the flow veloc-ity under the ice sheets became higher. Subsequently, as the melting of the ice bottomaccelerated with the increased flow velocity under the ice sheets, the sheet thicknessand strength decreased as a result of the higher water level and led to the occurrenceof breakup.