Elsevier

Journal of Hydrology

Volume 409, Issues 3–4, 9 November 2011, Pages 650-662
Journal of Hydrology

Estimating recharge in fractured aquifers of a temperate humid to semiarid volcanic island (Jeju, Korea) from water table fluctuations, and Cl, CFC-12 and 3H chemistry

https://doi.org/10.1016/j.jhydrol.2011.08.060Get rights and content

Summary

Groundwater table fluctuations (WTF), chloride mass balance (CMB), apparent groundwater chlorofluorocarbon (CFC-12) ages and tritium (3H) mean residence times were used to assess recharge rates on Jeju Island (Korea), where groundwater is the main source of potable water. Given the limitations of various techniques and the respective data, the methods yield median values of 687 mm/yr (WTF), 429 mm/yr (CMB), 423 mm/yr (CFC-12) and 394 mm/yr (3H), which are lower than the multi-annual (1993–2002) average value calculated using the soil water budget (SWB) method (911 mm/yr). These underestimates are mainly due to most groundwater samples used for the analyses being located in the more arid lowland areas of the island. All methods yield highest recharge rates in the southern and eastern districts of Jeju implying a strong control of rainfall on the spatial recharge distribution. The spatial variability of recharge at the catchment scale is caused by spatially and temporally variable rainfall and evapotranspiration as well as the wide range in effective porosity and specific yield values of the aquifer lithologies. The WTF method yields reliable results in the coastal regions where low hydraulic gradients prevail. The CMB technique underestimates the recharge values of the SWB in all geographic districts probably as a result of anthropogenic Cl additions to groundwater and unaccounted for atmospheric Cl dry deposition. Median recharge estimates from the CFC-12 and 3H data show the lowest spatial correlation with those from the SWB mainly as a result of vertical anisotropies and uncertainties in the determination of effective aquifer thicknesses particularly in the perched, high level areas. The here applied methods are useful for local calibration and validation of SWB estimates in lower parabasal regions where thin unsaturated zones prevail; however, due to their inability to predict recharge in the more remote upslope areas from which, as of yet, no groundwater data could be obtained, they cannot be applied to predict average recharge values representative for the whole island.

Highlights

► Comparison of different methods for predicting groundwater recharge. ► Estimates from water table fluctuations, and Cl, CFC-12 and 3H chemistry are lower than those from a soil water budget. ► All methods yield highest recharge rates in areas of highest rainfall. ► Complex climate and fractured aquifers inhibit regional extrapolations of point estimates of recharge.

Introduction

On Jeju Island (Korea), surface water resources are unreliable because aquifers with high hydraulic conductivity limit permanent surface runoff to only a few select locations near the coast (Hamm et al., 2005, Kim et al., 2003, Won et al., 2005, Won et al., 2006). Given that groundwater provides ∼92% of the potable water for the island’s ∼600,000 residents (Kim et al., 2003), a detailed assessment of the temporal and spatial variations of recharge is important to evaluate and manage the island’s water resources sustainably.

Recharge on islands is generally estimated as the residual in a soil water budget (SWB) (Engott and Vana, 2007, Giambelluca, 1983, Giambelluca et al., 1996b, Izuka et al., 2007, Shade, 1995). The method is popular, considering that it is not hindered by limiting assumptions regarding the mechanisms that control the individual budget components (i.e., rainfall, evapotranspiration, direct runoff, baseflow/interflow in and outflow, vegetation interception and soil water storage) (Dripps and Bradbury, 2007, Scanlon et al., 2002, Tindall and Kunkel, 1999). In addition, the method does not require the drainage-basin boundary and groundwater divides to coincide; a condition that is hard to satisfy (Izuka et al., 2010). The major limitation of the approach is that the accuracy of the recharge estimate depends on the accuracy of the estimates of the other components in the SWB. This limitation is critical when the magnitude of the recharge rate is small relative to that of the other variables. As an illustration, on Jeju Island, direct runoff only occurs when a rainfall event exceeds a threshold value of 40–50 mm over several days (KOWACO, 2003). In this case, averaging over longer time periods may dampen out extreme precipitation and runoff events, which mainly control recharge. The usefulness and reliability of the SWB has therefore been questioned in regions with low runoff (Gee and Hillel, 1988, Hendrickx and Walker, 1997, Lerner et al., 1990). Recharge estimates using SWB models can also differ substantially depending on whether irrigation is carried out (Giambelluca et al., 1996a), which adds another source of uncertainty if averaging values over time periods longer than days. Oki (2008) concluded that the accounting order of recharge and evapotranspiration may result in a large uncertainty of the estimate if soil moisture storage capacity is small and when water budgets are computed using monthly time intervals as compared to daily time steps. Furthermore, as the SWB yields recharge values only for below the root zone, it is not clear where and when exactly the infiltrating rainwater will cause the water table to rise if the unsaturated zone is thick and heterogeneous (Dripps and Bradbury, 2007, Westenbroek et al., 2010). It becomes clear that recharge estimates from the SWB method should be validated and refined by incorporating other independent estimates.

Many techniques exist for quantifying recharge rates. These include numerical modeling of groundwater flow, lysimeters installed in the soil zone, remote sensing, water table fluctuations, radioactive (e.g., 3H, 14C) or other (e.g., chlorofluorocarbons) tracers, and chemical mass balance (see, e.g., the reviews by Walker et al., 2002, Scanlon et al., 2002, Cartwright et al., (2007) and Brunner et al. (2007)). However, choosing appropriate techniques for a specific site is not straightforward, considering that a particular method can be more suitable for certain time and spatial scales. For example, water table fluctuations are more suitable for estimating local recharge over a few days to a few years, while 3H, chlorofluorocarbons (CFCs), 14C and Cl in groundwater provide average local recharge estimates over years to millennia (Herczeg and Edmunds, 2000, Scanlon et al., 2002, Walker et al., 2002). On Jeju Island, the residence time of groundwater is generally less than 50 years (Koh et al., 2007b, Koh et al., 2006a), there is low direct runoff (Won et al., 2006) and water table fluctuations show direct responses to episodic rainfall events (Koh et al., 2006c, Won et al., 2006). Considering these characteristics, recharge is estimated at multiple point locations from water table fluctuations (WTF), chloride mass balance (CMB), apparent CFC-12 ages and modeled 3H mean residence times. The main objectives of this study are to: (1) assess the applicability of these recharge estimation techniques to Jeju and similar settings, and (2) validate and refine previous recharge estimates based on the SWB method published by the Korean Water Resources Corporation (KOWACO, 2003). Special attention is given to Jeju’s volcanic island setting where water levels can be as low as 300 m below the land surface (Koh et al., 2006c), fractured high and low conductivity aquifers may alternate over several meters (Hahn et al., 1997), and rainfall minus potential evaporation is high, but direct runoff is low (KOWACO, 2003).

Section snippets

Topography, climate and land use

Jeju Island is comprised of a dormant shield volcano with one central mountain peak, Mt. Halla, rising to an elevation of 1950 m (Fig. 1a). The island is elliptical in shape with a semi-major axis width of 74 km, a semi-minor axis width of 32 km, and a total area of 1830 km2. The smooth flanks of Mt. Halla are disrupted by about 360 secondary cinder and tuff cones that are mainly located along the eastern and western coastal regions (Hahn et al., 1997). The 16 watersheds of the island are

Data

In this study, recharge (R in mm/yr) was calculated from available climate, physical hydrogeology and geochemistry data from the literature. Porosity and specific yield values were taken from Kwon et al. (1993) and Hahn et al. (1997), respectively. Hourly groundwater levels for the time period 01/01/2008 till 12/31/2009 used in the WTF method were provided by the Institute of Environmental Resource Research, Jeju Special Self-Governing Province (IERR-JSSGP, 2010). For the CMB approach, rainfall

Water table fluctuations

Bore hydrographs recorded at regular intervals from multiple wells across the island show that recharge is episodic (Koh et al., 2006c, Won et al., 2006) and linked to seasonal rainfall cycles (Fig. 4). The variations in the water tables allow calculating recharge using the WTF method (Healy and Cook, 2002):R=Sydh/dtwhere dh = change in water level (mm), dt = change in time (years), and Sy = specific yield (dimensionless), defined as the volume of water released from an unconfined aquifer per unit

Conclusions and Implications

This study clearly demonstrates that the magnitude and spatial distribution of recharge may vary on Jeju depending on which estimation technique is chosen (Fig. 5). Relying solely on one method to quantify recharge can therefore be very misleading.

The main advantage of the WTF method in comparison to the CMB, CFC-12 and 3H techniques is that, alike the SWB, it can be used to detect both short-term interseasonal and long-term average recharge rates making it a useful calibration tool for local

Acknowledgements

The authors would like to thank D.-C. Koh, G.-W. Koh and Y.-C. Kim for providing helpful information on the hydrogeology of Jeju Island. We also thank G.-P. Kim for providing hourly groundwater level data. L. Charlet, N. Goldscheider, P. Cook and an anonymous reviewer are acknowledged for their insightful suggestions that improved the manuscript. This work was supported by the Korea Institute of Geoscience and Mineral Resources for the Leading Industry Development of Jeju Economic Region.

References (109)

  • S.-Y. Hamm et al.

    Relationship between transmissivity and specific capacity in the volcanic aquifers of Jeju Island, Korea

    J. Hydrol.

    (2005)
  • S.R. Hinkle et al.

    Aquifer-scale controls on the distribution of nitrate and ammonium in ground water near La Pine, Oregon

    USA J. Hydrol.

    (2007)
  • S.K. Izuka et al.

    Simple method for estimating groundwater recharge on tropical islands

    J. Hydrol.

    (2010)
  • D. Kaown et al.

    Effects of groundwater residence time and recharge rate on nitrate contamination deduced from δ18O, δD, 3H/3He and CFCs in a small agricultural area in Chuncheon, Korea

    J. Hydrol.

    (2009)
  • B.G. Katz et al.

    Using Cl/Br ratios and other indicators to assess potential impacts on groundwater quality from septic systems: a review and examples from principal aquifers in the United States

    J. Hydrol.

    (2011)
  • Y. Kim

    Hydrogeochemical and isotopic evidence of groundwater salinization in a coastal aquifer: a case study in Jeju volcanic island, Korea

    J. Hydrol.

    (2003)
  • D.-C. Koh et al.

    Baseline geochemical characteristics of groundwater in the mountainous area of Jeju Island, South Korea: Implications for degree of mineralization and nitrate contamination

    J. Hydrol.

    (2009)
  • D.-C. Koh et al.

    Evidence for terrigenic SF6 in groundwater from basaltic aquifers, Jeju Island, Korea: implications for groundwater dating

    J. Hydrol.

    (2007)
  • D.-C. Koh et al.

    Application of environmental tracers to mixing, evolution, and nitrate contamination of ground water in Jeju Island, Korea

    J. Hydrol.

    (2006)
  • K.S. Lee et al.

    Using H- and O- isotopic data for estimating the relative contributions of rainy and dry season precipitation to groundwater: example from Cheju Island

    J. Hydrol.

    (1999)
  • C. Le Gal La Salle et al.

    Renewal rate estimation of groundwater based on radioactive tracers (3 H,14 C) in an unconfined aquifer in a semi-arid area, Iullemeden Basin, Niger

    J. Hydrol.

    (2001)
  • N.N. Ozyurt et al.

    LUMPED: a visual basic code of LP models for mean residence time analysis in groundwater systems

    Comput. Geosci.

    (2003)
  • N.N. Ozyurt et al.

    LUMPED Unsteady: a Visual Basics® code of unsteady-state lumped-parameter models for mean residence time analyses of groundwater systems

    Comput. Geosci.

    (2005)
  • S.-U. Park et al.

    Estimation of nitrogen dry deposition in South Korea

    Atmos. Environ.

    (2002)
  • S. Roy et al.

    Geochemistry of dissolved and suspended loads of the Seine river, France. Anthropogenic impact, carbonate and silicate weathering

    Geochim. Cosmochim. Acta

    (1999)
  • P. Schlosser et al.

    Tritiogenic 3He in shallow groundwater

    Earth Planetary Sci. Lett.

    (1989)
  • P.A. Tanner et al.

    Comparison of aerosol and dry deposition sampled at two sites in Southern China

    J. Aerosol Sci.

    (2001)
  • Belcher, W.R., Elliott, P.E., Geldon, A.L., 2002. Hydraulic-Property Estimates for Use With a Transient Ground-Water...
  • G. Blackburn et al.

    Salinity of atmospheric precipitation in the Murray–Darling Drainage Division, Australia

    Aust. J. Soil Res.

    (1983)
  • P. Brunner et al.

    How can remote sensing contribute in groundwater modeling?

    Hydrogeol. J.

    (2007)
  • E. Busenberg et al.

    Use of chlorofluorocarbons (CCl3F and CCl2F2) as hydrologic tracers and age-dating tools: the alluvium and terrace system of central Oklahoma

    Water Resour. Res.

    (1992)
  • C.-H. Chung

    Vegetation response to climate change on Jeju Island, South Korea, during the last deglaciation based on pollen record

    Geosci. J.

    (2007)
  • P. Cook et al.

    The transport of atmospheric trace gases to the water table: implications for groundwater dating with chlorofluorocarbons and krypton-85

    Water Resour. Res.

    (1995)
  • P. Cook et al.

    Chlorofluorocarbons as tracers of groundwater transport processes in a shallow, silty sand aquifer

    Water Resour. Res.

    (1995)
  • P.G. Cook et al.

    Determining timescales for groundwater flow and solute transport

  • L.A. Corcho Alvarado

    36Cl in modern groundwater dated by a multi-tracer approach (3H/3He, SF6, CFC-12 and 85Kr): a case study in quaternary sand aquifers in the Odense Pilot River Basin, Denmark

    Appl. Geochem.

    (2005)
  • L. Dassi

    Use of chloride mass balance and tritium data for estimation of groundwater recharge and renewal rate in an unconfined aquifer from North Africa: a case study from Tunisia

    Environ. Earth Sci.

    (2010)
  • G.H. Davis et al.

    Geohydrologic interpretations of a volcanic island from environmental isotopes

    Water Resour. Res.

    (1970)
  • W.R. Dripps et al.

    A simple daily soil–water balance model for estimating the spatial and temporal distribution of groundwater recharge in temperate humid areas

    Hydrogeol. J.

    (2007)
  • S.A. Dunkle

    Chlorofluorocarbons (CCl3F and CCl2F2) as dating tools and hydrologic tracers in shallow groundwater of the Delmarva Peninsula, Atlantic Coastal Plain, United States

    Water Resour. Res.

    (1993)
  • EANET, 2010. Acid Deposition Monitoring Network in Aast Asia. Data Report on the Acid Deposition in the East Asian...
  • B. Ekwurzel

    Dating of shallow groundwater: comparison of the transient tracers 3H/3He, chlorofluorocarbons, and 85Kr

    Water Resour. Res.

    (1994)
  • Engott, J.A., Vana, T.T., 2007. Effects of agricultural land-use changes and rainfall on ground-water recharge in...
  • G. Favreau et al.

    Estimate of recharge of a rising water table in semiarid Niger from3 H and14 C modelling

    Groundwater

    (2002)
  • Feth, J.H., 1981. Chloride in natural continental water – a review. USGS Water Supply Paper, p....
  • R.A. Freeze et al.

    Groundwater

    (1979)
  • G.W. Gee et al.

    Groundwater recharge in arid regions: review and critique of estimation methods

    Hydrol. Process.

    (1988)
  • Giambelluca, T.W., 1983. Water balance of the Pearl Harbor-Honolulu basin, Hawaii, 1946–1975. Water Resour. Res. Center...
  • T.W. Giambelluca et al.

    Water balance, climate change, and land use planning in the Pearl Harbor basin, Hawai‘i

    Int. J. Water Resour. Dev.

    (1996)
  • Gingerich, S.B., 2002. Geohydrogeology and Numerical Simulation of Alternatuve Pumping Distributions and the Effects on...
  • Cited by (34)

    • Application of novel data-mining technique based nitrate concentration susceptibility prediction approach for coastal aquifers in India

      2022, Journal of Cleaner Production
      Citation Excerpt :

      Baker (1992) and Liu et al. (2005) states about ‘cumulative effect’ of livestock residues which are used as fertilizer that leach towards subsoil by irrigation or rainfall significantly, and contaminate the shallow aquifer groundwater. The groundwater level is shallow in coastal areas because of its closer location towards sea level instead of central areas (mid and high altitude) (Chang, 2014; Hagedorn et al., 2011). Therefore, this is the only source for drinking water in coastal areas and nitrate contamination has been gradually increase day by day in coastal India (Khan et al., 2021; Mondal et al., 2008; Saranya et al., 2011).

    • Statistical analysis relating variations in groundwater level to droughts on Jeju Island, Korea

      2021, Journal of Hydrology: Regional Studies
      Citation Excerpt :

      This accounts for only 64.6 % of the typical average annual rainfall over the last 12 y (2162 mm/y; Korea Meteorological Administration, 2018). Over the past decade, there have been many studies related to variations in groundwater levels on Jeju Island (Won, 1994; Koh, 1997; Won et al., 2005; Kim et al., 2006; Choi and Lee, 2009; Hagedorn et al., 2011). However, limited research has been conducted on groundwater-level variations under drought conditions using statistical methods.

    • Comparisons and uncertainties of recharge estimates in a temperate alpine catchment

      2020, Journal of Hydrology
      Citation Excerpt :

      Determining the location and magnitude of groundwater recharge in higher rainfall regions is also important for understanding the impacts of large-scale groundwater use, contaminant transport, and groundwater-river interactions (Döll and Fiedler, 2008; Wada et al., 2010; Gleeson et al., 2012; Moeck et al., 2020). Recharge in higher rainfall areas is likely to be less episodic (Hagedorn et al., 2011; Crosbie et al., 2012; Jasechko et al., 2014; Allocca et al., 2015; Eaton, 2019), which simplifies the determination of representative recharge rates; however, a larger volume of rainfall is potentially removed as surface runoff, which complicates the application of many techniques used to estimate recharge. Despite its importance, many studies use data or infrastructure that was not originally intended to study recharge (e.g., regional geochemistry datasets or suites of monitoring wells screened below the water table).

    View all citing articles on Scopus
    View full text