Hydrochemical and isotopic investigation to characterize the effect of snowmelt infiltration on groundwater in a snowy landslide area of Japan

• Published in: Environmental earth sciences Vol. 80; no. 12
• Main Authors: Tsuchihara, Takeo, Okuyama, Takehiko, Shirahata, Katsushi, Yoshimoto, Shuhei, Nakazato, Hiroomi, Ishida, Satoshi
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.06.2021; Springer Nature B.V
• Subjects: Biogeosciences; Chemical composition; Chemical precipitation; Earth and Environmental Science; Earth Sciences; Electrical conductivity; Electrical resistivity; Environmental Science and Engineering; Flow system; Geochemistry; Geology; Groundwater; Groundwater table; Hydrochemicals; Hydrology/Water Resources; Infiltration; Isotope composition; Isotope ratios; Landslides; Landslides & mudslides; Melting; Original Article; Precipitation; Seasonal variation; Seasonal variations; Seasons; Snowmelt; Stable isotopes; Terrestrial Pollution; Water table; Japan; Heterogeneity; Landslide; Snowmelt; Deuterium excess; Groundwater
• DOI: 10.1007/s12665-021-09722-3
• ISSN: 1866-6280

Snowmelt infiltration is one of the key factors that trigger landslides. This study focused on characterization of snowmelt infiltration in the Shimekake landslide block in northeastern Japan via long-term monitoring of major ion concentrations and stable isotope ratios of groundwater and precipitation. Results revealed seasonal variations of the d-excess values of precipitation, which were significantly higher in winter. Likewise, the d-excess values of the groundwater increased during the melting season. Groundwaters collected from 17 sites in the landslide blocks were classified into five types based on a comparison of hydrochemical and isotopic compositions between melting and non-melting seasons. Groundwater with significantly higher d-excess values during the melting season was diluted by infiltration of snowmelt, which resulted in a decrease in ion concentrations. Three groundwater types underwent large changes in electrical conductivity and/or ion concentrations during the melting season, even though the d-excess values did not change significantly. These groundwaters were inferred to have been affected by the arrival of groundwater with different chemical compositions as a result of elevation of the water table by infiltration of snowmelt. The fifth type of groundwater was less affected by snowmelt infiltration. The results indicated the existence of preferential subsurface flows and a heterogeneous flow system in this landslide block.