結氷河川における河道形状を考慮したアイスジャム発生条件に関する研究

抄録

This study aims to clarify the relationship between ice jam occurrence and the cross-sectional profile of ice-covered rivers. We carried out hydraulic experiments in a test channel that reproduced an ice- covered river. The test channel had four sections, each with a different river width and river bed slope. The hydraulic conditions that were varied were ice sheet area, ice sheet discharge and flow discharge. The research clarified the following. Ice sheets tend to deposit at places of great water depth and low flow velocity. Ice jams are generated under the following conditions: large ice sheet area, high ice sheet discharge and low flow discharge. Moreover, the relationship between ice sheet transportation and water slope was inferred. The probability of ice jam occurrence can be estimated from the ice sheet's Froude number by using ice sheet thickness and ice sheet velocity. When the ice sheet's Froude number is small, the ice sheet velocity is low.