Spatiotemporal variability of hydrogen stable isotopes at a local scale in shallow groundwater during the warm season in Tottori Prefecture, Japan

Yumi Yoshioka, Hidekazu Yoshioka
Received 2021/11/12, Accepted 2021/02/02, Published 2022/03/19

Yumi Yoshioka1), Hidekazu Yoshioka1)

1) Academic Assembly, Shimane University, Japan

Oxygen and hydrogen stable isotopes are key hydrological tracers for identifying groundwater flow paths, groundwater recharge sources, and related hydrogeological processes. This study aims to identify the spatiotemporal variability in isotopic compositions of hydrogen (δ2H) measured in shallow groundwater, river water, paddy water, and precipitation collected from two catchments in Tottori Prefecture, Japan. A total of 613 surface water and groundwater samples were collected from 45 sites (wells) in five different landscapes during a two-year survey. The enriched groundwater δ2H values were in the range –52‰ to −36‰, and large isotopic variations were observed in the coastal regions of the study area. The lower groundwater δ2H compositions were in the range −61‰ to −53‰ in high elevation areas. Our study shows that the spatial variation in groundwater δ2H (23‰) was larger than the temporal variation (12‰) within the 3,500 km2 total area of Tottori Prefecture. At this scale, clear correspondence between the temporal standard deviations of the δ2H values and landscape characteristics was not found, suggesting that spatial scales should be considered carefully when analyzing the temporal evolution of hydrological tracers.

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Copyright (c) 2022 The Author(s) CC-BY 4.0

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