横浜市帷子川の河床堆積物の供給源について

概要

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For the purpose of offering some clarification on their origin, we analyzed rock composition of gravels of riverbed sediments in the River Katabira which streams from west to east in the central part of Yokohama City. The gravels of the riverbed sediments are mainly composed of Miocene green tuffs and igneous rocks originated from the Tanzawa Mountains, and Mesozoic and Paleozoic sedimentary rocks originated from the Kanto Mountains. The gravels shoud be considered as secondary origin, because the River Katabira has run only in the Pleistocene Tama Hills and Shimosueyoshi Plateau, and has not connected to boss the Tanzawa- and Kanto Mountains since the river has occurred. The gravels were probably derived from the Middle Pleistocene Hodogaya Gravels Bed distributed along the middle to lower catchment areas of the river. In addition, it was studied for data of volume of dredged sediments in the river during 29 years from 1972 to 2000 to consider the origin of the sediments at the duration. It was too big, 22,064m^3 for accumulation of the dredged sediments volume in the river for 29 years to sediment only in natural condition. The dredged sediments are considered to result from many exploitations with large area for housing land around wide regions along the river from about 45 years ago.
横浜国立大学の論文