An investigation of the spatial and temporal variability of the saline interface in a sandy aquifer subject to storm wave runup and rainfall recharge

Springer Science and Business Media LLC - Tập 28 - Trang 1695-1719 - 2020
R. Ian Acworth1, Martin S. Andersen1, Greg R. Dasey2
1Connected Waters Initiative Research Centre (CWI), School of Civil and Environmental Engineering, UNSW Sydney, Manly Vale, Australia
2JBSG Australia Pty Ltd, Sydney, Australia

Tóm tắt

Investigations at Hat Head in northern New South Wales, Australia, have shown that the depth and location of the saline interface changes significantly in response to storm-induced wave runup, rainfall recharge and regional groundwater discharge. The interplay between these three factors creates moving zones of fresh and salty water that displace each other over time, leading to the development of complex geochemical patterns. The results of an extensive hydrogeological investigation incorporating surface and borehole geophysics, drilling, monitoring and hydrochemical sampling on multiple occasions has demonstrated that the mixing zone between fresh groundwater and seawater occurs as zones of variable chemical composition which extend further inland and to greater depths than anticipated. The location and magnitude of these mixing zones varies over time scales of weeks. The chemical processes within these mixing zones are dominated by redox reactions that may never reach an equilibrium, with the system being episodically disturbed by new storm events. Diel changes from tides do not have an observable impact on the interface. An improved understanding of these processes will require regular monitoring and sampling from a range of vertical sampling points in the coastal zone, combined with routine monitoring using borehole induction logs.

Tài liệu tham khảo

Acworth RI (2007) Measurement of vertical environmental-head profiles in unconfined sand aquifers using a multi-channel manometer board. Hydrogeol J 15(7):1279–1289. https://doi.org/10.1007/s10040-007-0178-9 Acworth I (2019) Investigating groundwater. International Contributions to Hydrogeology 29, Taylor and Francis. https://doi.org/10.1201/9781351008525 Acworth R, Dasey G (2003) Mapping of the hyporheic zone around a tidal creek using a combination of borehole logging, borehole electrical tomography and cross-creek electrical imaging, New South Wales, Australia. Hydrogeol J 11(3):368–377. https://doi.org/10.1007/s10040-003-0258-4 Acworth R, Jorstad L (2006) Integration of multi-channel piezometry and electrical tomography to better define chemical heterogeneity in a landfill leachate plume within a sand aquifer. J Contam Hydrology 83(3–4):200–220. https://doi.org/10.1016/j.jconhyd.2005.11.007 Acworth R, Jankowski J, Soriano R, Turner I (1998) Interaction between coastal sand-dune aquifers, adjacent wetlands and sea water. In: Brahana JV (ed) Proceedings of XXIX IAH Congress: Gambling with Groundwater, Balkema, Rotterdam, The Netherlands, pp 461–468 Acworth R, Soriano R, Turner I (2000) The vertical head distribution in a coastal sand-dune aquifer. In: Sililo O (ed) Proc 30th IAH Congress on Groundwater: Past Achievements and Future Challenges, Cape Town, 26 Nov–1 Dec 2000, pp 67–72 Acworth RI, Hughes C, Turner I (2007) A radioisotope tracer investigation to determine the direction of groundwater movement adjacent to a tidal creek during spring and neap tides. Hydrogeol J 15(2):281–296. https://doi.org/10.1007/s10040-006-0085-5 Acworth RI, Rau GC, McCallum AM, Andersen MS, Cuthbert MO (2015) Understanding connected surface-water/groundwater systems using Fourier analysis of daily and sub-daily head fluctuations. Hydrogeol J 23:143–159. https://doi.org/10.1007/s10040-014-1182-5 Akumu CE, Pathirana S, Baban S, Bucher D (2011) Examining the potential impacts of sea level rise on coastal wetlands in north-eastern NSW, Australia. J Coast Conserv 15(1):15–22. https://doi.org/10.1007/s11852-010-0114-3 Andersen MS (2001) Geochemical processes at a seawater–freshwater interface. Environment and Resources DTU, Technical University of Denmark, Lyngby, Denmark Andersen MS, Nyvang V, Jakobsen R, Postma D (2005) Geochemical processes and solute transport at the seawater/freshwater interface of a sandy aquifer. Geochim Cosmochim Acta 69(16):3979–3994. https://doi.org/10.1016/j.gca.2005.03.017 Andersen MS, Baron L, Gudbjerg J, Chapellier D, Jakobsen R, Gregersen J, Postma D (2007) Discharge of nitrate-containing groundwater into a coastal marine environment. J Hydrol 336:98–114. https://doi.org/10.1016/j.jhydrol.2006.12.023 Andersen MS, Jakobsen R, Nyvang V, Christensen F, Engesgaard P, Postma D (2008) Density driven seawater plumes in a shallow aquifer caused by a flooding event: field observations, consequences for geochemical reactions and potentials for remediation schemes. In: GQ07: Securing Groundwater Quality in Urban and Industrial Environments, Proc. 6th International Groundwater Quality Conference, Fremantle, Western Australia, 27 December 2007, IAHS Publ. 324, IAHS, Wallingford, UK, pp 483–490 Appelo CAJ, Postma D (2005) Geochemistry, groundwater and pollution, 2nd edn. Balkema, Leiden, The Netherlands Archie G (1942) The electrical resistivity log as an aid in determining some reservoir characteristics. Trans ASCE 146:54–62. https://doi.org/10.2118/942054-G Barlow P (2003) Ground water in freshwater–saltwater environments of the Atlantic Coast. US Geol Surv Circ 1262 Beekman HE, Anthony C, Appelo CAJ (1990) Ion chromatography of fresh- and salt-water displacement: laboratory experiments and multicomponent transport modelling. J Contam Hydrol 7:21–37. https://doi.org/10.1016/0169-7722(91)90036-Z Berner RA (1981) A new geochemical classification of sedimentary environments. J Sedimeny Petrol 51:359–365. https://doi.org/10.1306/212F7C7F-2B24-11D7-8648000102C1865D Brooke B, Preda M, Lee R, Cox M, Olley J, Pietsc T, Price D (2008) Development, composition and age of indurated sand layers in the Late Quaternary coastal deposits of northern Moreton Bay, Queensland. Aust J Earth Sci 55:141–157. https://doi.org/10.1080/08120090701689316 Chapelle FH (2001) Ground-water microbiology and geochemistry. Wiley, New York Dasey GR (2010) Geophysical and hydrogeological assessment of the interaction of saline and fresh groundwater near a tidal creek. PhD Thesis, School of Civil and Environmental Engineering, UNSW, Sydney, Australia Fairbanks RG (1989) A 17,000-year glacio-eustatic sea level record: influence of glacial melting rates on the Younger Dryas event and deep-ocean circulation. Nature 342:637–642. https://doi.org/10.1038/342637a0 Jakobsen R, Postma D (1994) In-situ rates of sulphate reduction in an aquifer (Rømø, Denmark) and implications for the reactivity of organic matter. Geology 22:1103–1106. https://doi.org/10.1130/0091-7613(1994)022<1103:ISROSR>2.3.CO;2 Jankowski J, Beck P (2000) Aquifer heterogeneity: hydrogeological and hydrochemical properties of the Botany Sands aquifer and their impact on contaminant transport. Aust J Earth Sci 47(1):45–64. https://doi.org/10.1046/j.1440-0952.2000.00768.x Jiao J, Post V (2019) Coastal hydrogeology. Cambridge University Press, Cambridge, UK Kiss E (1984) Investigation of some asymmetric triazines as reagents for the spectrophotometric microdetermination of the iron oxidation state in silicates. Anal Chim Acta 161:231–244 Loke M (2001) RES2DINV Ver 3.4 manual: rapid 2D and 3D resistivity and IP inversion using the least squares method, https://www.geoelectrical.com. Accessed 30 September 2018 Loke M (2016) Tutorial: 2-D and 3-D electrical imaging surveys. https://www.geotomosoft.com. Accessed 26 June 2016 Lusczynski N (1961) Head and flow of groundwater of variable density. J Geophys Res 66:4247–4255. https://doi.org/10.1029/jz066i012p04247 Malott S, O’Carroll DM, Robinson CE (2016) Dynamic groundwater flows and geochemistry in a sandy nearshore aquifer over a wave event. Water Resour Res 52:5248–5264. https://doi.org/10.1002/2015WR017537 Manson F, Loneragan N, Skilleter G, Phinn S (2005) An evaluation of the evidence for linkages between mangroves and fisheries: a synthesis of the literature and identification of research directions. Oceanogr Mar Biol 43:485–515 McAllister SM, Barnett JM, Heiss JW, Findlay AL, MacDonald DJ, Dow CL, Luther III GW, Michael HA, Chan CS (2015) Dynamic hydrologic and biogeochemical processes drive microbiologically enhanced iron and sulfur cycling within the intertidal mixing zone of a beach aquifer. Limnol Oceanogr 60:329-345 Postma D, Jakobsen R (1996) Redox zonation: equilibrium constraints on the Fe(III)/SO4– reduction interface. Geochim Cosmochim Acta 60:3169–3175. https://doi.org/10.1016/0016-7037(96)00156-1 Rau GC, Post VEA, Shanafield MA, Krekeler T, Banks EW, Blum P (2019) Error in hydraulic head and gradient time-series measurements: a quantitative appraisal. Hydrol Earth System Sci. https://doi.org/10.5194/hess-23-3603-2019 Reid N, Nunn P, Sharpe M (2014) Indigenous Australian stories and sea-level change. In: 18th Conference of the Foundation for Endangered Languages (FEL): Indigenous Languages: Value to the Community, Okinawa, Japan, 17–20 September 2014 Robinson C, Gibbes B, Carey H, Li L (2007) Salt–freshwater dynamics in a sub-terranean estuary over a spring-neap tidal cycle. J Geophys Res C: Oceans 112(C9). https://doi.org/10.1029/2006JC003888. Robinson C, Xin P, Li L, Barry D (2014) Groundwater flow and salt transport in a subterranean estuary driven by intensified wave conditions. Water Resour Res 50(1):165–181. https://doi.org/10.1002/2013WR013813 Roy P, Zhuang W-Y, Birch G, Cowell P, Congxian L (1997) Quaternary geology of the Forster - Tuncurry coast and shelf, southeast Australia. Technical report, Geological Survey of New South Wales, NSW Department of Mineral Resources, Sydney Saenger P, Gartside D, Funge-Smith S (2013) A review of mangrove and seagrass ecosystems and their linkage to fisheries and fisheries management. RAP Publ. 2013/09, Food and Agriculture Organization of the United Nations, FAO Regional Office for Asia and the Pacific, Bangkok Thailand Sheaves M, Baker R, Nagelkerken I, Connolly RM (2015) True value of estuarine and coastal nurseries for fish: incorporating complexity and dynamics. Estuar Coasts 38(2):401–414. https://doi.org/10.1007/s12237-014-9846-x Shen C, Zhang C, Kong J, Xim P, Chunhui L, Zhao Z, Li L (2019) Solute transport influenced by unstable flow in beach aquifers. Adv Water Resour 125:68–81. https://doi.org/10.1016/j.advwatres.2019.01.009 Simmons CT, Fenstemaker TR, Sharp JM Jr (2001) Variable-density groundwater flow and solute transport in heterogeneous porous media: approaches, resolutions and future challenges. J Contam Hydrol 52(1-4):245–275. https://doi.org/10.1016/S0169-7722(01)00160-7 Soriano RS (2004) Groundwater dynamics in coastal sand-dune aquifers: the impacts of transient boundary conditions. PhD Thesis, School of Civil and Environmental Engineering, University of New South Wales, Sydney Turner IL, Coates B, Acworth RI (1997) Tides, waves and the super-elevation of groundwater at the coast. J Coastal Res 13(1):45–60. https://doi.org/10.1021/BI00235A008 Turner IL, Acworth RI (2004) Field measurements of beach face salinity structure using cross-borehole resistivity imaging. J Coastal Res 20(1):194–201. https://doi.org/10.2112/1551-5036(2004)20[753:FMOBSS]2.0.CO;2 Turner IL, Rau G, Andersen MS, Austin M, Puleo J, Masselink G (2013) Coastal sand barrier hydrology: observations from the BARDEX II prototype-scale laboratory experiment. J Coastal Res 65:1886–1891. https://doi.org/10.2112/SI65-319.1 Turner IL, Rau GA, Austin MJ, Andersen MS (2016) Groundwater fluxes and flow paths within coastal barriers: observations from a large-scale laboratory experiment (BARDEX II). Coast Eng 113:104–116. https://doi.org/10.1016/j.coastaleng.2015.08.004 Van Camp M, Vauterin P (2005) TSoft: graphical and interactive software for the analysis of time series and Earth tides. Comput Geosci 31(5):631–640. https://doi.org/10.1016/j.cageo.2004.11.015