| 摘要 |
PURPOSE:To permit tidal current of slow flow rate to pass as it is but the current of fast flow rate to pass at delayed flow rates by using a fence having holes of a given opening degree which is to be fixed to the seabed. CONSTITUTION:In case where the size and shape of holes are fixed, the resistance of a perforated fence 1 is reduced when the flow rate of tidal current is slow, where the flow rate of the current passing through the fence 1 is not decelerated. When the flow rate of tidal current passing through the fence 1 is so fast as to move sand, grains, the resistance of the fence 1 is greater, where the flow rate of tidal current passing through the fence 1 is greatly reduced. The resistance of the fence 1 is determined by the opening degree of the fence 1, or an opening degree of 20-95% gives rise to remarkable effects. Therefore, scouring occurs beneath the fence 1 to form sedimented areas on the front and back sides of the fence 1, and the emvironments suitable for sources of living things can thus be obtained.
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