Characteristics of water quality and estimation of the recharge area in the northern part of the coastal area, Fukushima prefecture

Abstract

The objective of this study was to determine water quality and estimate the groundwater recharge area in the northern part of the Fukushima prefecture. Water samples were collected during the period April 2014-October 2017. The water quality of shallow groundwater and spring water mainly indicate Ca-HCO₃, while deep groundwater and artesian wells indicate Na-HCO₃. At the tsunami-affected site, Na-Cl was recognized, along with confirmed Ca-SO₄ and mixed types. Water quality could be determined by residence time, geology, land use, and other parameters. As a result of groundwater recharge area estimation at each observation site using a recharge-water line, the recharge area of middle and deep groundwater and artesian wells located in the southern part of Minamisoma City was estimated to be in the vicinity of the Abukuma Mountains with relatively long residence times. In the case of shallow groundwater and spring water in the same area, the recharge area was estimated to be upland near the coast, with relatively short residence times. These results suggest the possible existence of multiple aquifers in this area.