Groundwater supply under land subsidence constrains in the Nobi Plain

Abstract

Groundwater overdraft resulted in land subsidence throughout the Nobi Plain, central Japan. To cope with the growing water demand in the region, a numerical model was used to determine the maximum withdrawal capacity of two confined aquifers without causing undesirable consequences. Results were validated against field data and by analytical solutions. The analysis focused in Aburashima, a site expected to experience a rapid development in the forthcoming years. Calculations showed the water availability in the upper aquifer is limited. Moreover, seasonal fluctuations in heads reduce its extraction capacity up to 44%. In contrast, storage is substantially higher in the deep aquifer. Larger quantities and lower extraction costs make this layer a more reliable source for water supply. Findings from this study will be used by authorities to update the current legislation on groundwater abstraction. Nevertheless, it is argued that to achieve a long-term sustainability, policies should not limit solely to control regulations but also to economical strategies and the expansion of the infrastructure system.