Abstract
In Tokyo, land subsidence has occurred since about the beginning of Taishou Era, and has developed according to revival in the post-war days. The land subsidence became acceleated especially in the third and the fourth decade of Showa Era.
For such a situation, Tokyo Metropolitan Government is positively working on managing groundwater in order to avoid land subsidence with such efforts as groundwater withdrawal management, groundwater level monitoring, and promotion of rain water infiltration, which are based on the laws and ordinances.
As a result, land subsidence in Tokyo tends to remission, however, it has not ended. Moreover, the groundwater level is reaching the ceiling from the marginal rise to level-off. So there remains a possibility that land subsidence would relapse if the present withdrawal management is eased. Therefore, it is necessary to maintain the withdrawal management and to increase the amount of recharge to avoid future land subsidence.
In this text, the situation and the management of land subsidence in Tokyo are retraced and future tasks are described.
