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積雪域に大雨が降った時の雪氷水文現象
石井, 吉之
Permalink : http://hdl.handle.net/2115/73991
JaLCDOI : 10.14943/lowtemsci.77.41
KEYWORDS : ROS イベント;融雪期;模擬降雨散水実験;融雪鉄砲水;Rain-on-snow event;Snowmelt season;Artificial rain sprinkling experiment;Snowmelt flash flood
Abstract
北海道における最近のROSイベントに関係する研究成果の一部を取り上げて解説した．2012年4～5月は，日射が十分な上に気温が高く風も適度な春の好天が20日以上続いたことにより，例年にない速さで融雪が進み，4月下旬から5月初めにはROSイベントが重なって融雪災害が多発した．母子里では，雪面上に著しい大雨が降った場合を想定した模擬降雨散水実験が2通りの方法で行われた．自然積雪法では積雪底面流出が出現する場合と出現しない場合のどちらもが観測された．積雪ブロック法では積雪底面流出の流出率はほぼ1になるが，浸透水の自然の流れを乱している可能性がある．2018年3月9～10日にはROSイベント時に雪泥による河道閉塞が起こり，その後の閉塞部の崩壊によって融雪鉄砲水が発生したと推察される．
Some results of recent rain-on-snow (ROS) event studies in Hokkaido are discussed. Snow melting rates during April to May in 2012 were remarkably fast due to the warm, weak wind and a lot of sunshine conditions. Then, snowmelt hazards occurred many sites during a ROS event from late April to early May. Artificial rain sprinkling experiments were carried out in Moshiri by the two different ways. One was the natural snowpack method, and the other one was the snow block method. Both methods have merits and demerits. Under the ROS event from March 9 to 10 in 2018 in central Hokkaido, stream water level showed the typical changes at the time of the occurrence of snowmelt flash flood.
Some results of recent rain-on-snow (ROS) event studies in Hokkaido are discussed. Snow melting rates during April to May in 2012 were remarkably fast due to the warm, weak wind and a lot of sunshine conditions. Then, snowmelt hazards occurred many sites during a ROS event from late April to early May. Artificial rain sprinkling experiments were carried out in Moshiri by the two different ways. One was the natural snowpack method, and the other one was the snow block method. Both methods have merits and demerits. Under the ROS event from March 9 to 10 in 2018 in central Hokkaido, stream water level showed the typical changes at the time of the occurrence of snowmelt flash flood.
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