Abstract
Local scour plays an important role on sinking phenomena of artificial fish reefs placed on sand bed in shallow
seas. If artificial fish reefs sink into sea bottom, they lose their ability to gather fishes. In order to clarify
this sinking mechanism and to overcome this problem, an experimental study on local scour around an artificial
fish reef was initiated. This paper presents the results of experiments on scour around cylindrical artificial fish
reef models in one way currents in an open channel. The local scour around artificial fish reefs is substantially
different from that of bridge pier which have been investigated by many researchers because the artificial fish
reef inclines and slides into the scour hole developed in scouring process. In addition to actual scour tests, a flow
visualization study was carried out to understand the flow pattems around cylindrical shape models. The important
parameter for estimation of the equilibrium local scour depths around the artificial fish reefs was found to
be the ratio of the sediment number (Ns) to the critical sediment number (N*sc ), when the model width to
water depth ratio was constant.
