Journal cover Journal topic
Hydrology and Earth System Sciences An interactive open-access journal of the European Geosciences Union
Hydrol. Earth Syst. Sci., 21, 3417-3425, 2017
https://doi.org/10.5194/hess-21-3417-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
11 Jul 2017
Temporal variations of groundwater tables and implications for submarine groundwater discharge: a 3-decade case study in central Japan
Bing Zhang1,2,3, Jing Zhang2,1, and Takafumi Yoshida1 1Northwest Pacific Region Environmental Cooperation Center, 930-0856, Toyama, Japan
2Earth and Environmental System, Graduate School of Science and Engineering, University of Toyama, 930-8555, Toyama, Japan
3Tianjin Key Laboratory of Water Resources and Environment, Tianjin Normal University, 300387, Tianjin, China
Abstract. Fresh submarine groundwater discharge (SGD) is the key pathway of flux and nutrients for the groundwater from land to the ocean. SGD flux is a current issue of discussion and a means to clarify the coastal marine system under climate change. SGD flux accounts for about one-quarter of the river runoff in the Katakai alluvial fan in Uozu, Toyama, Japan, which is an ideal area to study SGD flux considering the need for a rapid response to climate change and the prior research on SGD there. In this paper, the monthly groundwater table's condition over 30 years is analyzed using monthly rainfall, snowfall, and the climate change index. Rainfall has been on an upward trend, but the snowfall has decreased over 40 years. Furthermore, the groundwater table at monitoring wells in the coastal area increased, as a result of the increased rainfall. However, the relationship between snowfall and groundwater is negative. As expected by Darcy's law, SGD flux was controlled by the hydraulic gradient of the coastal groundwater. The estimated historic SGD flux by groundwater table variation shows an upward trend of SGD. Considering the increase in precipitation and the groundwater table, SGD flux may increase under climate change.

Citation: Zhang, B., Zhang, J., and Yoshida, T.: Temporal variations of groundwater tables and implications for submarine groundwater discharge: a 3-decade case study in central Japan, Hydrol. Earth Syst. Sci., 21, 3417-3425, https://doi.org/10.5194/hess-21-3417-2017, 2017.
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Short summary
Since groundwater is the linkage between climate changes and fresh submarine groundwater discharge, the variations of and relationships among monthly groundwater table, rainfall, snowfall, and climate change events from 1985 to 2015 were analyzed by wavelet coherence to discuss the implications for climate changes. The results show the increase in precipitation and the groundwater table, indicating that fresh submarine groundwater discharge flux may increase under climate change.
Since groundwater is the linkage between climate changes and fresh submarine groundwater...
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