Influence of ice and ice booms on water flow at semi-closed water areas

In Hokkaido, Japan more than 30 semiclosed water areas exist, and aquaculture has been performed in many of those water areas. Since semiclosed water areas connected to open sea by a narrow inlet are very calm water area, such areas are suitable for the aquaculture of scallops, oysters, and other marine products. However there is also the risk that the water quality may suddenly decrease with change of the surrounding environment. For permanent use for aquaculture, maintenance of the water quality is needed. As one of the water quality preservation methods, promotion of water exchange has been pointed out. Since Hokkaido is located in a cold region, in winter, semiclosed water areas freeze over, and ice floes drift into water areas though openings. Although ice cover and be floes are factors that worsen water exchange, flow analysis and evaluation of the amount of water exchange in considering the influence of ice has not been performed. Influence of the ice on water exchange clarified by flow analysis that set up fluid resistance is described.