Effect of a Sea Dike Closing a Bay on Tidal Decrease

Abstract

During the construction of a sea dike that closes a bay, the tide decreased gradually. Both the diminution of depth at the dike and the breadth of its opening affected the tidal decrease. At present, there is an insistence that, before the Isahaya sea dike was practically closed up the construction of the dike did not cause the decrease of the tide which is actually observed, because only the diminution-effect of the opening-breadth of the dike was taken into consideration. However, this conclusion will not be recognized because the important effect of diminution of the depth was not considered.