Socio-hydrological analysis of disaster emergency wells in Tokyo: a novel application of the pendulum-swing framework

Despite its significance in urban water policy, few studies have examined water security during emergencies. This paper reconstructs the long-term history of the human–groundwater coupled system in Tokyo using government reports, official questionnaire surveys, newspapers, and assembly minutes. It shows how disaster emergency well systems—the public use of local wells following disaster-induced water supply cutoffs—have evolved over time. This evolution is interpreted through a pendulum-swing between normal and emergency situations. Under normal conditions, groundwater development for industrial purposes led to extensive land subsidence. This problem was addressed after the 1950s through legal regulation of groundwater extraction and the expansion of industrial waterworks, marking a shift in water sources from groundwater to surface water. In the 1960s, growing recognition of earthquake risk introduced an emergency consideration into urban water governance. Efforts to ensure water security during disasters promoted the expansion of emergency water distribution stations and disaster emergency wells across Tokyo. This constituted a pendulum swing, in which groundwater regained social attention as a resource for disaster mitigation. More recently, growing attention has been paid to groundwater-based energy use, showing a pendulum swing back toward groundwater use under normal conditions while maintaining its importance for emergency use. This study thus presents a novel application of the pendulum-swing framework, highlighting how water uses shift between normal and emergency situations. In addition, it provides a detailed account of a hitherto underexplored practice: groundwater utilization for disaster preparedness. Promoting interaction between theoretical and practical spheres remains a key challenge in socio-hydrological research, and this paper represents an effort to bridge that gap by linking conceptual insights with concrete policy experiences.