Prediction of Sand Movement near Port of Kanazawa

Abstract

The accumulation of large quantities of sediments in the port of Kanazawa prevents smooth navigation every year. To find the directions of the sand movement and the sedimentary sources of littoral drift of sand in the port of Kanazawa, the methods of the ratio matching and gradients of kilo count number per second per weight of each element are applied after analyzing geochemical elements in sand samples. According to the correlation numbers obtained from the ratio matching, three kinds of sediments were found near the port, two of which were found in the port. The first kind of sediment is transported by the stationary, strong ocean current, which flows along the coast from the southwest to the northeast. These advected sediments accumulate near the tip of the breakwater because of the decrease of current velocities due to the blocking effect of the breakwater. During the winter season or during storms with incident waves of high amplitude, the accumulated sediments intrude into the port. The second and third kinds of sediment are conveyed into the port along the beach by the back flows of the ocean current. The back flows are caused by the interaction of the strong ocean current with the long breakwater. The historical coastal change near the port of Kanazawa following the construction of the long breakwater is estimated using the present results.