Field Observation of Anchor Ice Formation and Contained Materials

Abstract

Anchor ice is a phenomenon to accumulate of frazil ice on the river bed. This is formed due to the super cooling and a shallow, turbulent section of the river. But, it is a poorly understood and little studied topic. Our study focuses on elucidate the material cycle of freezing river. We had a continuous observation of air temperature, water temperature, water level and all day shooting of anchor ice formation using IP-camera during an anchor ice presence-absence cycles. From the result, we found the critical element of anchor ice presence-absence is under super cooling condition. We attempted to analyze two-dimensional flow calculation and spatial distribution of photo image analysis of an anchor ice. As a result, we found spatial distribution of anchor ice is proportional to the Froude number. We analyzed the contained materials of an anchor ice. As a result, a lot of algae (Hydrurus foetidus and diatoms) existed in the anchor ice. We showed the possibility that anchor ice affected the material cycle of freezing river.