大潟海岸・上下浜における海底地形と海底底質の粒度組成 -海底地形の変形と海底底質の粒度組成の岸沖方向変異-

Abstract

大潟海岸において，自然海岸である上下浜で，深浅測量と海底底質採取を，2001年8月6日，2002年9月20日，2003年8月23日，2003年10月7日に行った。深浅測量は，1日に，汀線から沖へ約200mの地点を汀線に沿った1測線と岸沖方向の2測線を行った。また，海底底質採取は，岸から沖へ水深1mごとに，2測線の弧状沿岸砂州中心部，接合部(深浅測量も同様)で行った。海底地形の変形と海底底質の粒度組成の岸沖方向変異の考察から，冬季にそれぞれ最も顕著であることが示された。また，海底底質と海岸砂丘砂との相関関係も示された。

This author has considered the grain size composition of the sediment of the sea bottom, which movedalong a natural providence, at Jogehama's coast. This author has carried out the sounding and thegathering of sediment off of the sea bottom, here, on Aug.6.2001, Sept.20.2002, Aug.23.2003, andOct.7.2003. This author has carried out sounding, from south west to north east 200m offshore on ameasuring line, along the shoreline, and from shoreline to offshore on two measuring lines, each day. Also, this author has carried out the gathering of sediment off of the sea bottom, from the shoreline to offshore, every 1m in depth, at both the central measuring line on the crescent-shaped bar and the jointed measuringline on the crescent-shaped bar, each day. In doing this, this author has considered the changes in the seabottom profile, and variation from the shoreline to offshore, in the grain size composition of the sedimentof the sea bottom. Also, this author has been able to show by means of evidence, that both the sea bottomprofiles and the grain size composition of the sediment of the sea bottom, have changed dramatically inthe winter season. Furthermore, this author has examined the correlation between the sediment of the seabottom and the recent coastal sand dune.