An experimental research on snowmelt with hot sediment supply for elucidation of snowmelt-type volcanic mudflow initiation processes

Keiki MURASHIGE, Daizo TSUTSUMI, Shusuke MIYATA, Masaharu FUJITA, Hideo SAKAI and Isao KAMIISHI

Eruptions at snow covered volcano enhance very intensive snow melt and can trigger mudflow. Although such mudflow sometimes causes severe damage and loss in downstream areas, triggering mechanism of this type of mudflow is not understood yet. In the present study, a fundamental experiment is conducted to examine the processes of snow melting and water infiltration to the snow layer using experimental column and hot sediment (500�Ž) supplying equipment. The snowmelt and infiltration processes in the experiment were the follows; 1) hot sediments melt the snow layer, 2) the water infiltrates in snow layer, 3) water table is formed on the bottom of the column, and 4) hydrograph(melting water discharge from the column bottom)shows sharp peak at the early stage of the water discharge. To simulate the melting water discharge, simple mathematical models for heat conductivity between sediment and snow, snow melt and deformation of snow layer, and water infiltration in the snow layer were developed. The model reproduced the observed water discharge due to snow melt well. The model can be applicable for the prediction of mudflow behavior due to the volcanic eruption and snow melt to mitigate the sediment related disasters.