Groundwater as emergency water supply: case study of the 2016 Kumamoto Earthquake, Japan

Abstract

Securing water supply is an extremely important issue following an earthquake. Recent earthquakes in Japan have prompted focus on the use of groundwater or disaster emergency wells (DEWs). Water supply networks are vulnerable to earthquakes because they comprise long-distance pipelines that are not always earthquake-resistant. Groundwater, however, can usually be found directly below an area where water is required and can serve as an alternative water source. Although previous studies discussed the importance of groundwater in relation to natural disasters, with special reference to drought, little attention has been given to the use of groundwater following earthquakes. In this study, two questionnaire surveys were conducted of DEW owners and welfare facilities for elderly people in Kumamoto (Japan), which was struck by an Mw 7.3 earthquake in 2016, to identify the advantages and disadvantages of using groundwater as an emergency water supply and ascertain policy issues to be resolved for making DEWs effective. Results showed that not only 30 DEWs but also at least 25 privately owned wells not registered as DEWs were open to the public in the early restoration stage, improving people’s access to water and decreasing the burden on the Kumamoto city government’s emergency water supply. However, it was revealed that groundwater might not always be potable owing to quality concerns. Additionally, only a limited number of welfare facilities used the available adjacent DEWs and DEW recognition level remains low. These findings indicate that improving information disclosure regarding emergency groundwater use is a policy issue to be resolved.