Author(s): Edistri Nur Fathya, Shinichiro Yano, Akito Matsuyama, Akihide Tada
Linked Author(s): Edistri Nur Fathya
Keywords: : Lifetime of reclamation wall, sediment transport, suspended solid, mercury, Minamata Bay
Abstract: More than 25 years after the dredging and reclamation projects of high mercury-contaminated sediment were conducted, the possibility of sludge leakage from the reclaimed area to Minamata Bay may threaten the lives of the marine environment and people around the bay. The inevitable problem could occur because the wall sheet will deteriorate as time goes by. In order to predict the condition of sediment leakage, we conduct the numerical simulation of sediment transport and suspended solid (SS) distributions from the reclaimed wall area to the bay. Delft3D software including the rectangular variable grid and 40 tidal components as boundary condition is imposed, also we assume a part of the wall in the north and south part collapsed and for one day in rainy season, the high contaminated sediments including mercury are released to the bay. The results show that SS distribution to the Minamata Bay is more significant when the south part of reclamation wall collapses than the north part. In the upper layer, when the low tide occurs, barotropic and baroclinic flow move SS to southwest direction entering Minamata Bay and the results of baroclinic flow show a faster current velocity and larger area of distribution than barotropic flow. On the other hand, at high tide, the SS can be distributed around the northern area. After 30 days, both barotropic and baroclinic flows finally spread and move the SS to Fukuro Bay, which is a small semi-enclosed bay at the head of Minamata Bay, and the sediment above seabed to south entering the Minamata Bay. From the result, in the upper layer, it can be assumed that baroclinic flow is significantly distributing SS to Minamata Bay. Meanwhile, in deeper layer, barotropic and baroclinic flow almost have a similar contribution in transporting the sediment from reclamation wall to the bay
Year: 2017