The first water security issues as military/defense/political problems are issues across/beyond boundaries such as transboundary aquifers. The second water security issues as human security are the right to have water for human-being such as access right to the water resources which are deteriorated by wars, social system changes, disasters such as drought, flooding, and earthquakes. Groundwater use for emergency situations (GWES) is one of the security issues as human securities (the second security). The number of legislated wells for emergency situation use of groundwater in Kyoto becomes 574 on 2011. The analyses of groundwater dependency in Asian megacities during the last 100 years showed the dependency decreased gradually, however the groundwater dependency jumped up by 20-30 % after the World War II. The tendency of use of groundwater lasts 20 years after the war, which showed the groundwater use as security. Furthermore, the Great East Japan Earthquake showed the importance of groundwater as security in terms of not only alternative resources, but also steady resources/circulation as resilience. In addition to these, GWES in the area show the strength of the community. The risk management and evaluation of water services are important for the third security as environmental human security. The balance between reducing risk and increasing services, and the effect of long term change such as global change on groundwater should be evaluated for the groundwater security.

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The prolonged interruption of city water supply caused by the Great East Japan Earthquake had severe influences on the daily life of citizens and the economic activities in the quake-hit area. Thus the necessity for alternative water supply system that can complement the existing city waterworks is being recognized. In this study, field tests were conducted on water wells suffered by the compound forces of vibration and tsunami in order to investigate the ground vibration properties, damage in the well structures, and water pumping ability. As a result, no functional losses of the wells were found. This result suggests the technical possibility of constructing an alternative water supply system that utilizes the groundwater as measures against mega-earthquake disaster.

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