Evaluations of the downward velocity of soil water movement in the unsaturated zone in a groundwater recharge area using δ18 O tracer: the Kumamoto region, southern Japan

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Azusa Okumura
Takahiro Hosono
Dennis Boateng
Jun Shimada

Abstract

Water and substances from the surface infiltrate the unsaturated zone before reaching groundwater. Yet, little study has been done on the unsaturated zone due to the difficulty of sampling. A lot of studies have been carried out on the top soil down to a depth of one metre and on shallow aquifers because they are easily accessible for sampling. The unsaturated zone of the Kumamotoregion recharge areas is important due to concerns about groundwater pollution from agriculture. The aim of this study was to estimate the downward velocity of soil water movement through the unsaturated zone and the recharge rate using δ18O as a tracer. Five sampling sites were selected and a core was taken from each site. The cores were cut into 0.1 m pieces and soil water was extracted from each to analyze for δD and the δ18O content. Average δD and δ18O compositions of soil water were similar to the isotopic compositions of summer precipitation. Annual average recharge rate and the downward velocity of soil water in each site were estimated by fitting a vertical δ18O profile pattern to a precipitation δ18O time series as a theoretical water displacement flow model for recharge. An estimated annual average recharge rate in the recharge area ranged from 745 to 1058 mm/yr with the annual average downward velocity of 1.37 to 2.34 m/yr. Based on the estimated downward velocity, the infiltration time for soilwater to reach the aquifer was determined as ranging from 9 to 24 years, which corresponds with previous groundwater age estimations presented in an earlier published study on the same area. It was assumed that contaminants will reach aquifers in 9 to 25 years if the effects of diffusion and microbiological reaction are not taken into account.

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Original Scientific Papers

References

ANDERSEN, L. J. & SEVEL, T. (1974): Six Years Environmental Tritium Profiles in the Unsaturated Zones, Gronhoj, Denmark.– Isotope Techniques in Groundwater Hydrology, IAEA Vienna, 1, 3–20.

BAHARATI, L., LEE, K.H., ISENHART, T.M. & SCHULTZ, R.C. (2002): Soil-water Infiltration Under Crops, Pastures, and Established Riparian Buffer in Midwestern USA.– Agroforestry Systems, 56, 249–257.

BARNES, C. & ALLISON, G.B. (1983): The Distribution of Deuterium and 18O in Dry Soils, 1 Theory.– Journal of Hydrology, 60, 141–156.

BARNES, C.J. & TURNER, J.V. (1998): Isotopic Exchange in Soil Water – Isotope Tracers.– In: KENDALL, C. & MCDONNELL, J.J. (eds.): Catchment Hydrology, Elsevier, Amesterdam, 137–163.

BARTH, S.R. (2000): Stable isotope geochemistry of sediment-hosted groundwater from a Late Paleozoic-Early Mesozoic section in central Europe.– Journal of Hydrology, 235, 72–87.

BEVEN, K. & GERMANN, P. (1982): Macropores and Water Flow in Soils.– Water Resources Research, 18, 1311–1325.

CLARK, I. & FRITZ, P. (1997): Groundwater – Environmental Isotopes in Hydrogeology.– CRC Press/Lewis Publishers, 85–89.

CLOUTIER, V., LEFEBVRE, R., THERRIEN, R & Savard, M.M. (2008): Multivariate statistical analysis of geochemical data as indicative of the hydrogeochemical evolution of groundwater in sedimentary rock aquifer system.– Journal of Hydrology, 353, 294–313.

CRAIG, H. (1961): Isotope Variations in Meteoric Waters.– Science, 133, 1702–1703.

De VRIES, J.J., SELAOLO, E.T. & BEEKMAN, H.E. (2000): Groundwater Recharge in the Kalahari, with Reference to Paleo-hydrologic Conditions.– Journal of Hydrology, 238, 110–123.

DELIN, G.N. & HERKELRATH, W.N. (2017): Effects of crude oil on water and tracer movement in the unsaturated and saturated zones.– Journal of Contaminant Hydrology, 200, 49–59.

DEMLIE, M., WOHNLICH, S., WISOTZKY, F. & GIZAW, B. (2007): Groundwater recharge, flow and hydrogeochemical evolution in a complex volcanic aquifer system, central Ethiopia.– Hydrogeology Journal, 15, 1169–1181.

GUYMON, G.L. (1994): Preface and Introduction – Unsaturated Zone Hydrology.– P.T.R. Prentice Hall, 1–6.

HARRIS, R.C. (2000): Tritium as a tracer of groundwater sources and movement in the Safford Basin, Graham County, Arizona.– Arizona Geological Survey, 9, 1–56.

HORITA, Y. (1985): The Measurement of Physical Soil by the Actual Volume.– Research of forest in Kyusyu, 38, 139–141 (in Japanese).

HOSONO, T., TOKUNAGA, T., KAGABU, M., NAKATA, H., ORISHIKIDA, T., LIN, I.T. & SHIMADA, J. (2013): The Use of δ15N and δ18O Tracers with an Understanding of Groundwater Flow Dynamics for Evaluating the Origins and Attenuation Mechanisms of Nitrate Pollution.– Water Research, 47, 2661–2675.

HOSONO, T., TOKUNAGA, T., TSUSHIMA, A. & SHIMADA, J. (2014): Combined use of δ13C, δ15N, and δ34S tracers to study anaerobic bacterial processes in groundwater flow systems.– Water Research, 54, 284–296.

HEM, J.D. (1985): Study and Interruption of the Chemical Characteristics of Natural Water.– United States Geological Survey Water-Supply Paper, 2254, 174–180.

JOHNSTORN, G.T., COOK, P.G., FRAPE, S.K., PLUMMER, L.N., BUSENBERG, E, & BLACKPORT, R.J. (1998): Groundwater age and nitrate distribution within a glacial aquifer beneath a thick unsaturated zone.– Ground Water, 36, 171–180.

KAYANE, T., TANAKA, T. & SHIMADA, J. (1980): The Transportation of Soil Water in Kanto Loam Formation Using Environmental Tritium as a Tracer.– Geographical Review of Japan, 53–4, 225–237 (in Japanese).

KABEYA, N., OHTE, N., SUGIMOTO, A., YOSHIKAWA, K. & WANG, L. (2002): Effects of the Ground Cover Conditions on Horizontal Profiles of Chloride Concentration, Oxygen and Hydrogen Stable Isotope Ratios of Groundwater in Mu Us Desert, China.– Journal of Japan Society of Hydrology and Water Resources, 15, 13–22 (in Japanese with English Abstract).

KAGABU, M., MATSUNAGA, M., IDE, K., MOMOSHIMA, N. & SHIMADA, J. (2017): Groundwater Age Determination Using 85Kr and Multiple Age Tracers (SF6, CFCs and 3H) to Elucidate Regional Groundwater Flow Systems.– Journal of Hydrology, Regional Studies, 12, 165–180.

KUDO, K., SHIMADA, J., MARUYAMA, A. & TANAKA N. (2016): The Quantitative Evaluation of Groundwater Recharge Rate Using Displacement Flow Model with Stable Isotope Ratio in the Soil Water of Different Vegetation Cover.– Journal of Japan association of Groundwater Hydrology, 58, 31–45 (in Japanese with English Abstract).

LIN, R. & WEI, K. (2006): Tritium profiles of pore water in the Chinese loess unsaturated zone: Implications for estimation of groundwater recharge.– Journal of Hydrology, 328, 192–199.

MAHARA, Y. (1995): Noble Gases Dissolved in Groundwater in a Volcanic Aquifer: Helium Isotopes in Kumamoto Plain.– Environmental Geology, 25, 214–224.

MIYAGIMA, T. & NAGATA, S. (2008): The Stable Isotope and the Evaluation of Watershed Environment.– The Academic Publisher in Kyoto University, Japan, 59–65 (in Japanese).

MIYOSHI, M., FURUKAWA, K., SHINMURA, T., SHIMONO, M. & HASENAKA, T. (2009): Petrography and Whole-rock Geochemistry of Pre-Aso Lavas from the Caldera Wall of Aso Volcano, Central Kyusyu.– Journal of the Geological Society of Japan, 115, 672–687. (in Japanese with English Abstract).

NICHOL, C., SMITH, L. & BECKIE, R. (2005): Field-scale experiments of unsaturated flow and solute transport in a heterogeneous porous medium.– Water Resour. Res., 41/5, W05018.

NIMMO, J.R. (2007): Simple predictions of maximum transport rate in unsaturated soil and rock.– Water Resour. Res., 43/5, http://onlinelibrary.wiley.com/doi/10.1029/2006WR005372/pdf

RUSSELL, E.W. (1973): Soil Conditions and Plant Growth.– 10th ed., Longman, London.

SHIMADA, J. (1988): The Mechanism of Unsaturated Flow through a Volcanic Ash Layer under Humid Climatic Conditions.– Hydrological Processes, 2, 43–59.

SHIMADA, J. (2012): Sustainable Management of Groundwater Resources for 700.000-Plus Residents: A Practional Example of the Transboundary Management of Groundwater Resources in the Kumamoto Area, Japan. The Dilemma of Boundaries. TANIGUCHI, M. & SHIRAIWA, T. (eds.) Springer Japan, 235–246.

SHIMADA, J. & UENO, M. (2016): The Challenge to Sustainable Groundwater Use.– Seibundo, 8, 144–151 (in Japanese).

SHIMOZU, M. (1986): On the Characteristics of groundwater in the Hydrologic Cycle of the Aso Volcano.– Journal of Japan Association of Groundwater Hydrology, 28, 1–13.

SPALDING, R.F., EXNER, M.E., LINDAU, C.W. & EATON, D.W. (1982): Investigation of source of groundwater nitrate contamination in Burbank-Wallula area of Washington, U.S.A.– Journal of Hydrology, 58, 307–324.

TAKAHASHI, K. (1979): Expression to estimate evapotranspiration using monthly average temperature and monthly precipitation.– Journal of Meteorological Society of Japan, 26, 29–32 (in Japanese).

TANIGUCHI, M., SHIMADA, J. & UEMURA, T. (2003): Transient effects of surface temperature and groundwater flow on subsurface temperature in Kumamoto Plain, Japan.– Physics and Chemistry of the Earth, 28, 477–486.

THORNTHWAITE, C.W. (1948): An approach toward a rational classification of climate.– Geographical Review, 38, 55–94.

TOMIIE, K., IWASA, Y., MAEDA, K., OTSUZUKI, M., YUNOUE, T., KAKIMOTO, R. & KAWAGOSHI, Y. (2009): Present Status and Feature of Groundwater Contamination by Nitrate-nitrogen in Kumamoto City.– Journal of Water and Environment Technology, 7, 19–28.

TSUJIMURA, M. (1994): Dynamic Behaviour of Soil Water Movement in a Headwater Basin.– Unpubl. Ph.D Thesis, University of Tsukuba, Japan, 132 p.

TSUJIMURA, M. & TANAKA, T. (1998): Evaluation of Evaporation Rate from Forested Soil Surface Using Stable Isotopic Composition of Soil Water in a Headwater Basin.– Hydrological Processes, 12, 2093–2103.

UMEZAWA, Y., HOSONO, T., ONODERA, S., SIRINGAN, F., BUAPENG, S., DELINOM, R., YOSHIMIZU, C., TAYASU, I., NAGATA, T. & TANIGUCHI, M.
(2008): Source of nitrate and ammonium contamination in groundwater under developing Asian megacities.– Science of the Total Environment, 404, 361–376.

YABUSAKI, S., TASE, N. & SHIMADA, J. (2011): Vertical Profile of Stable Isotopes in Soil Water through the Volcanic Ash Soil Layer in Japan.– The Earth Environmental Research, 13, 43–57 (in Japanese with English Abstract).

ZHANG, Y., LI, F., ZHANG, Q., LI, J. & LIU, Q. (2014): Tracing nitrate pollution sources and transportation in surface- and ground-waters using environmental isotopes.– Science of Total Environment, 490, 213–222.

ZIMMERMANN, U., EHHALT, D., MUNNICH, K.O., ROETHER, W., KREUTZ, W., SCHUBACH, K. & SIRGEL, O. (1966): Using Tracers to Determine Movement of Soil Moisture and Evapotranspiration.– Science, 152, 346–347.

LAND USE CONTROL BACK-UP SYSTEM (May 11, 2017). Land Use Control backup System, Retrieved from http://lucky.tochi.mlit.go.jp/

JAPAN METEOROLOGICAL AGENCY (March 20, 2018), Past climate data, Retrieved from http://www.data.jma.go.jp/gmd/risk/obsdl/index.php