Recent recurring earthquakes in Japan have prompted a renewed focus on the long-standing question of how to provide water for drinking and domestic use during emergencies. Among various options, local groundwater supplies, or disaster emergency wells, have attracted a great deal of attention. Waterworks are generally vulnerable to earthquakes because they comprise long-distance pipes that are often not resistant to earthquakes. However, groundwater which moves in a wide area, can typically be found directly below the area where water is needed and could serve as an alternative water source after an earthquake. While disaster emergency wells were used after recent major earthquakes in Japan, little is known about how widely such wells have been adopted in municipalities throughout the country. The present study investigated local disaster management plans to assess the spatial distribution of emergency wells throughout Japan's 1,741 municipalities.

The provision of the domestic water supply after an earthquake poses a large societal concern. While the water supply systems across Japan are presently being reconstructed to ensure they are earthquake resistant, preparing alternative water supplies has also been proposed. Local groundwater sources, also known as disaster emergency wells (DEWs), are an example of an alternative water source. This study investigated the current prevalence of DEWs throughout Japan's municipalities and classified them by purpose. The municipalities used DEWs as a source of drinking water and domestic water and also for fire protection, medical use, and livestock farming use. Some municipalities have plans to use snow-melting wells and agricultural wells for an alternative water source in emergency. A spatial distribution of such uses is presented, which shows local diversity in groundwater use.

Disaster emergency wells are an alternative to municipal waterworks to supply water in emergencies such as natural disasters. This study investigated local disaster management plans to classify the ownership of disaster emergency wells and the subsidy policies across all municipalities in Japan. This study identified the following points. First, disaster emergency wells are mainly composed of private wells and are used for various purposes under normal circumstances. Second, some municipalities have implemented subsidies for the creation of privately owned disaster emergency wells. The subsidies are various in terms of the objective which range from installation of hand-pump, water quality inspection to water delivery. Moreover, an evaluation of institutional effectiveness is done by using criteria including use of private wells, acceptable use policy, subsidy, positional information to find out municipalities which makes advanced efforts on disaster emergency wells.

To evaluate the impact of excess air on the SF₆-based groundwater age estimation, the dissolved nitrogen and argon concentrations in groundwater at 70 points in the Chubu region were measured, and the excess air was estimated. The groundwater from all points contained supersaturated nitrogen and argon, indicating that excess air was generated during groundwater recharge. The average excess air calculated based on dissolved nitrogen content was 2.2 cc STP / kg for the springs in a small mountainous catchment area, 2.8 cc STP / kg for the springs at the foot of a Quaternary volcano, and 3.7 cc STP / kg for the groundwater in an alluvial fan. The groundwater residence time was estimated to be 4 to 18 years longer based on the excess air correction of SF₆ . The corrected residence time was consistent with the residence time estimated from other age-dating tracers or hydrogeological settings. These results indicate that excess air correction is an important process in SF₆ dating applications in Japan, especially in highly permeable areas such as Quaternary volcanoes and alluvial fans.

This study was conducted to elucidate spatial and seasonal change in hydrochemistry of spring and well waters by collecting and analyzing water in the Owasawa River alluvial fan, located in the southern part of Hirosaki City, Aomori Prefecture, Japan. Water samples in the alluvial fan are dominated by Ca-HCO₃ or Na-Cl type and increase the concentrations of NO₃^– from the apex to the toe of the fan, which were significantly higher in urban areas. The seasonal variation in chemical composition of Tomita's spring water indicates that the concentration of NO₃^– was higher in early spring than that in rainy season. Nitrate in groundwater originates primarily from fertilizers which used to be sprinkled during late autumn and early spring in apple orchards. Significant high NO₃^－ value in early spring suggests the effect of spring snowmelt infiltration in a seasonal soil frost area on groundwater recharge.