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The 2003 Hokkaido Hidaka flood : sedimentary processes in the open ocean and influence to sea bottom environments

2003年北海道日高洪水：公海沉积过程及其对海底环境的影响

基本信息

批准号：
17340151
负责人：
IKEHARA Ken
金额：
$ 7.88万
依托单位：
National Institute of Advanced Industrial Science and Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2007
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-17340151/
关键词：
flood sea floor environment bottom sediment natural hazard 台風北海道日高地方

项目摘要

Floods supply large amounts of terrigenous materials to marine environments that affects sea bottom environments and strata formation. Quick deposition of large amount of sediments on sea floor may influence to sea floor environments. Because of few marine geological and sedimentological surveys have been conducted immediately after floods, behavior of flood sediments in marine environments and sedimentary processes are not well understood. In August 2003, heavy rain associated with by the typhoon 200310 caused flooding and landslides in Hidaka area, Hokkaido large amount of sand and mud were transported by rivers to ocean. Our survey indicated the two modes of flood mud deposition on the shelf. One is transportation by density (hyperpycnal) flows. Long distance transport across shelf was available by this mechanism. Another is diverse by hypopycnal surface plume. Flood mud was deposited near the river mouth by this system. Inner shelf submarine topography controls such a transportation mode. Taking into account of flood mud deposition on the outer shelf to deep-sea basin floor, the larger amount of terrigenous materials than those previously estimated from river observations were supplied to ocean by this flood. There results verify the importance of the hyperpycnal flow for long-distance transport of the terrigeouns materials to the deep-sea, and flood plays an important role on material supply to deep-sea.

洪水为海洋环境提供了大量的陆源物质，影响海底环境和地层形成。大量沉积物在海底的快速沉积会对海底环境产生影响。由于洪水后立即进行的海洋地质和沉积学调查很少，因此对洪水沉积物在海洋环境中的行为和沉积过程还没有很好的了解。2003年8月，200310号台风带来的暴雨导致北海道日高地区发生洪水和山体滑坡，大量的泥沙通过河流流入海洋。我们的调查表明，陆架上的洪水泥沉积有两种模式。一种是密度（超密度）流。该机制可实现跨货架的长距离运输。另一个是由hypopycnal表面羽多样化。该系统在河口附近沉积了洪水泥浆。内陆架海底地形控制了这种运输方式。考虑到洪水泥沉积在外大陆架的深海盆地底部，大量的陆源物质比以前估计的河流观测提供给海洋的洪水。结果表明，高密度流对陆源物质向深海的长距离输送起着重要作用，洪水对深海物质供给起着重要作用。