Abstract
Hydrochemistry and well hydrographs are coupled to assess groundwater recharge in the regional catchment of Samail, Oman. The complex geology comprises three aquifers: limestones of the Hajar Supergroup (HSG) at the highlands of North Oman Mountains (NOM); fractured/weathered ophiolites; and Quaternary alluvium. Groundwater flows south–north from the NOM to the coast. Samples from groundwater wells and springs (38) were analyzed for isotopes and major ions. Corrected 14C dating reveals modern groundwater across the entire catchment, while 87Sr/86Sr (0.70810–0.70895) shows greater homogeneity. Groundwater in the upper catchment is depleted in 2H and 18O, indicating a high-altitude recharge source (NOM), and becomes enriched downstream, with a slope indicating an evaporation effect. The hydrographs of nested piezometers located in the upper, middle and lower catchment show different recharge responses between deep and shallower depths. Head difference in response to recharge is observed upstream, suggesting a lateral recharge mechanism, contrary to vertical recharge downstream reflected in identical recharge responses. The homogeneous 87Sr/86Sr ratio, head changes, downstream enrichment of 2H and 18O, and the presence of modern groundwater throughout the catchment suggest that groundwater recharge takes place across the entire catchment and that the three aquifers are hydraulically connected. The recharge estimated using the chloride mass balance method is in the range of 0–43% of the mean annual rainfall.
Résumé
L’hydrochimie et les chroniques piézométriques sont utilisées conjointement pour évaluer la recharge des eaux souterraines dans le bassin hydrologique de Samail, Oman. La géologie complexe du bassin implique l’existence de trois aquifères: les calcaires du « Hajar Supergroup » (HSG) dans les parties hautes des montagnes nord-omanaises (NOM), les ophiolites fracturées/altérées et les alluvions du Quaternaire. Les directions d’écoulement des eaux souterraines sont Sud–Nord depuis les NOM jusqu’au littoral. La signature isotopique et les concentrations en ions majeurs des échantillons d’eau souterraine issus de forages et de sources (38) ont été déterminées. La datation au 14C corrigée indique des eaux souterraines récentes dans l’intégralité du bassin et le 87Sr/86Sr (0.70810–0.70895) montre une grande homogénéité. Les eaux souterraines dans la partie haute du bassin sont appauvries en 2H et 18O, indiquant une recharge en haute altitude (NOM), alors qu’à l’aval celles-ci deviennent enrichies et suivent une pente indiquant un effet d’évaporation. Les chroniques piézométriques mesurées sur une batterie de piézomètres (en « flûte de pan ») situés dans la partie haute, intermédiaire et basse du bassin présentent des réponses à la recharge, contrastées entre mesures profondes et plus superficielles. Dans la partie haute, les différences de charge observées en réponse à la recharge suggèrent un mécanisme de transfert latéral de la recharge alors que dans la partie basse, la réponse des piézomètres pour une recharge identique indique un transfert vertical. L’homogénéité du rapport 87Sr/86Sr, les variations de charges hydrauliques, l’enrichissement en 2H et 18O vers l’aval, et la présence d’eau souterraine récente dans tout le bassin suggèrent que la recharge des eaux souterraines opère dans l’intégralité du bassin et que les trois aquifères sont hydrauliquement connectés. La recharge, estimée par la méthode du bilan de masse en chlorures, est comprise entre 0 et 43% de la pluviométrie annuelle moyenne.
Resumen
Se acoplaron la hidroquímica y los hidrogramas de pozos para evaluar la recarga del agua subterránea en la cuenca regional de Samail, Omán. La compleja geología comprende tres acuíferos: calizas del Supergrupo Hajar (HSG) en las tierras altas de las montañas del norte de Omán (NOM); ofiolitas fracturadas/erosionadas; y aluvión cuaternario. El agua subterránea fluye al sur–norte desde la NOM a la costa. Las muestras de los pozos y manantiales del agua subterránea (38) se analizaron para detectar isótopos e iones mayoritarios. La datación corregida de 14C revela la presencia de agua subterránea moderna en toda la cuenca, mientras que 87Sr/86Sr (0.70810–0.70895) muestra una mayor homogeneidad. El agua subterránea en la cuenca superior se empobrece en 2H and 18O, lo que indica una fuente de recarga a gran altitud (NOM), y se enriquece aguas abajo con una pendiente que indica el efecto de la evaporación. Los hidrogramas de piezómetros anidados ubicados en la cuenca superior, media e inferior muestran diferentes respuestas de la recarga entre las mayores y menores profundidades. La diferencia de la carga hidráulica en respuesta a la recarga se observa aguas arriba, lo que sugiere un mecanismo de recarga lateral, contrariamente a la recarga vertical aguas abajo reflejada en idénticas respuestas de recarga. La relación homogénea 87Sr/86Sr, los cambios de carga hidráulica, el enriquecimiento aguas abajo de 2H y 18O, y la presencia de agua subterránea moderna sugieren que la recarga de agua subterránea se realiza en toda la cuenca y que los tres acuíferos están conectados hidráulicamente. La recarga estimada utilizando el método de balance de masa de cloruro está en el rango de 0-43% de la precipitación media anual.
摘要
结合水化学和井水位图评价了阿曼Samail区域汇水区地下水补给量。复杂的地质条件包括三个含水层:阿曼山脉北部高原Hajar超级组石灰岩层;断裂/风化蛇绿岩层;第四纪冲积层。地下水从阿曼山脉北部自南向北流向沿海。对地下水井和泉的水样进行了同位素和主要离子分析。校正的14C测年结果揭示整个汇水区为现代地下水,而87Sr/86Sr (0.70810–0.70895)显示出更高的均质性。在汇水区上游地下水中的2H 和 18O所剩无几,表明存在着高海拔补给源(阿曼山脉北部),在下游呈坡度富集,表明有蒸发效应。位于汇水区上游、中游和下游的测压计水位图显示,在深的和较浅的深度,补给响应不同。在上游观测到对补给响应的水头差,表明有侧向补给机理,与相同补给响应中反映出的下游垂直补给形成对比。均质的87Sr/86Sr比值、水头变化、2H 和 18O在下游的富集以及整个汇水区为现代水表明,整个汇水区都有地下水补给,三个含水层水力上有联系。采用氯化物质量平衡法估算的补给量为平均每年降水量的0-43%。
Resumo
Hidrogeoquímica e hidrografas de poços são acopladas para avaliar a recarga das águas subterrâneas na bacia regional de Samail, Omã. A geologia complexa compreende três aquíferos: calcários do Supergrupo Hajar (SGH) nos planaltos das Montanhas do Norte de Omã (MNO); ofiolitos fraturados/intemperizados; e aluviões Quaternários. A água subterrânea flui do norte para o norte do MNO até a costa. Amostras de poços e nascentes de água subterrânea (38) foram analisadas para isótopos e íons principais. A datação 14C corrigida revela águas subterrâneas modernas em toda a bacia, enquanto 87Sr/86Sr (0.70810-0.70895) mostra maior homogeneidade. A água subterrânea na bacia superior está esgotada em 2H e 18O, indicando uma fonte de recarga de alta altitude (MNO), e torna-se enriquecida a jusante com um declive indicando o efeito da evaporação. Os hidrogramas de piezômetros aninhados localizados na bacia superior, média e inferior mostram diferentes respostas de recarga entre profundidades profundas e rasas. A diferença de carga em resposta à recarga é observada a montante sugerindo um mecanismo de recarga lateral, ao contrário da recarga vertical a jusante refletida em respostas de recarga idênticas. A relação homogênea 87Sr/86Sr, mudanças de carga, enriquecimento a jusante de 2H e 18O e a presença de águas subterrâneas modernas em toda a bacia sugerem que a recarga de água subterrânea ocorre em toda a bacia hidrográfica e que os três aquíferos estão conectados hidraulicamente. A recarga estimada usando o método de balanço de massa de cloreto está na faixa de 0-43% da precipitação média anual.
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References
Abdalla O (2008) Groundwater discharge mechanism in semi-arid regions and the role of evapotranspiration. Hydrol Process 22:2993–3009
Abdalla O (2009) Groundwater recharge/discharge in semi-arid regions interpreted from isotopes and chloride concentration in North White Nile Rift, Sudan. Hydrogeol J. https://doi.org/10.1007/s10040-008-0388-9
Abdalla O, Al-Abri R (2011) Groundwater recharge in arid areas induced by tropical cyclones, lessons learned from Gonu 2007 in Sultanate of Oman. Environ Earth Sci J 63(2):229–239. https://doi.org/10.1007/s12665-010-0688-y.
Abdalla O, Suliman FO, Al-Ajmi H, Al-Hosni T, Rollinson H (2010) Cyanide from gold mining and its effect on groundwater in arid areas, Yanqul mine of Oman. Environ Earth Sci (Springer) 60(4):885–892. https://doi.org/10.1007/s12665-009-0225-z
Abdalla O, Al-Rawahi AS (2013) Groundwater recharge dams in arid areas as tools for aquifer replenishment and mitigating seawater intrusion: example of Alkhod, Oman. Environ Earth Sci 69:1951–1962. https://doi.org/10.1007/s12665-012-2028-x
Abdulrazzak MJ, Jurdi M, Basma S (2002) The role of desalination in meeting water supply demands in Western Asia. Water Int 27(3):395–406
Anderson EI (2003) The effective resistance to vertical flow in Dupuit models. Adv Water Resour 26(5):513–523
Bazuhair A, Wood W (1996) Chloride mass-balance method for estimating ground water recharge in arid areas: examples from western Saudi Arabia. J Hydrol 186(1996):153–159
Clark ID, Fritz P (1997) Environmental isotopes in hydrogeology. CRC Press/Lewis Publishers, Boca Raton
De Vries JJ, Selaolo ET, Beekman HE (2000) Groundwater recharge in the Kalahari, with reference to paleo-hydrologic conditions. J Hydrol 238(1–2):110–123
Dewandel B, Lachassagne P, Boudier F, Al-Hattali S, Ladouche B, Pinault J-L, Al-Suleimani Z (2005) A conceptual hydrogeological model of ophiolite hard-rock aquifers in Oman based on a multiscale and a multidisciplinary approach. Hydrogeol J 13(5-6):708–726
Gayo EM, Latorre C, Jordan TE, Nester PL, Estay SA, Ojeda KF, Santoro CM (2012) Late quaternary hydrological and ecological changes in the hyperarid core of the northern Atacama Desert (~21°S). Earth Sci Rev 113(3-4):120–140
Hanna SS (1995) Field guide to the geology of Oman. Western Hajar Mountains and Musandam vol. 1. The Historical Association of Oman, Ruwi, Sultanate of Oman 180 pp
Healy RW (2010) Estimating groundwater recharge. Cambridge University Press
Izady A, Abdalla O, Joodavi A, Karimi A, Chen M, Kudoda A (2017) Groundwater recharge estimation in arid hardrock-alluvium aquifers using combined water-table fluctuation and groundwater balance approaches. J Hydrol Proc 31(19):3437–3451. https://doi.org/10.1002/hyp.11270
Kacimov AR, Sherif MM, Perret JS, Al-Mushikhi A (2009) Control of sea-water intrusion by salt-water pumping: coast of Oman. Hydrogeol J 17:541–558. https://doi.org/10.1007/s10040-008-0425-8
Kawahata H, Nohara M, Ishizuka H, Hasebe S, Chiba H (2001) Sr isotope geochemistry and hydrothermal alteration of the Oman ophiolite. J Geophys Res 106(B6):11,083–11,099
Macumber PG (1997) Al Khawd Fan groundwater investigation. Ministry of Water Resources, Sultanate of Oman
Manna F, Cherry JA, McWhorter DB, Parker BL (2016) Groundwater recharge assessment in an upland sandstone aquifer of southern California. J Hydrol 541:787–799
Moe CL, Rheingans RD (2006) Global challenges in water, sanitation and health. J Water Health. https://doi.org/10.2166/wh.2005.039
Munson BR, Young DF, Okiishi TH (1994) Fundamentals of fluid mechanics. Wiley, New York
Obnosov YUV, Kacimov AR, Castro-Orgaz O (2015) An exact analytical solution for steady phreatic flow disappearing/re-emerging towards/from a bedrock/caprock isobaric breach: the Polubarinova-Kochina-Numerov and Pavlovsky problems revisited. Transp Porous Media 109(2):337–358. https://doi.org/10.1007/s11242-015-0522-9
Robertson AHF, Searle MP (1990) The northern Oman Tethyan continental margin: stratigraphy, structure, concepts and controversies. In: Robertson AHF, Searle MP, Ries AC (Eds), The geology and tectonics of the Oman Region. Geol Soc Lond Spec Publ 49:3–25
Scanlon BR, Keese KE, Flint AL, Flint LE, Gaye CB, Edmunds WM, Simmers I (2006) Global synthesis of groundwater recharge in semiarid and arid regions. Hydrol Process 20(15):3335–3370
Scanlon BR, Mukherjee A, Gates J, Reedy RC, Sinha AK (2010) Groundwater recharge in natural dune systems and agricultural ecosystems in the Thar Desert region, Rajasthan, India. Hydrogeol J 18(4):959–972
Semhi K, Abdalla O, Al Abri R, Al-Hosni T, Clark I (2017) Strontium isotopes as tool for estimation of groundwater recharge and aquifer connectivity. Groundwater Sustain Dev 4:1–11. https://doi.org/10.1016/j.gsd.2016.11.001
Stone AEC, Edmunds WM (2016) Unsaturated zone hydrostratigraphies: a novel archive of past climates in dryland continental regions. Earth Sci Rev 157:121–144
Sturchio NC, Du X, Purtschert R, Lehmann BE, Sultan M, Patterson LJ, Lu Z-T, Muller P, Bigler T, Bailey K, OConnor TP, Young L, Lorenzo R, Becker R, El Alfy Z, El Kaliouby B, Dawood Y, Abdallah AMA (2004) One million year old groundwater in the Sahara revealed by krypton-81 and chlorine-36. Geophys Res Lett 31(5):L05503. https://doi.org/10.1029/2003GL019234
Sultan M, Metwally S, Milewski A, Becker D, Ahmed M, Sauck W, Soliman F, Sturchio N, Yan E, Rashed M, Wagdy A, Becker R, Welton B (2011) Modern recharge to fossil aquifers: Geochemical, geophysical, and modeling constraints. J Hydrol 403(1-2):14–24
Toth J (2009) Gravitational systems of groundwater flow. Cambridge University Press, Cambridge
Weyhenmeyer CE, Burns SJ, Waber HN, Aeschbach-Hertig W, Kipfer R, Loosli HH, Matter A (2000) Cool glacial temperatures and changes in moisture source recorded in Oman groundwaters. Science 287:842–845
Weyhenmeyer CE, Burns SJ, Waber HN, Macumber PG, Matter A (2002) Isotope study of moisture sources, recharge areas, and groundwater flow paths within the eastern Batinah coastal plain, Sultanate of Oman. Water Resour Res 38(10):1184. https://doi.org/10.1029/2000WR000149.
Young ME, Macumber PG, Watts M, Al-Toqy N (2004) Electromagnetic detection of deep freshwater lenses in a hyper-arid limestone terrain. J Appl Geophys 57(2004):43–61
Zekri S, Maktoumi A, Abdalla O, Akil J, Charabi Y (2014) Hydrogeological and economical simulation: water provision in emergency situation for Muscat. Water Policy 16(2):340–357. https://doi.org/10.2166/wp.2013.187
Acknowledgements
This study was funded by the Sultan Qaboos University projects no. SR/SCI/ETHS/11/01 and no. IG/SCI/ETHS/09/01. Thanks are due to the Ministry of Regional Municipalities and Water Resources for providing hydrograph data.
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This article is part of the topical collection “Coastal aquifers in the Middle East and North Africa region”
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Abdalla, O.A.E., Al-Hosni, T., Al-Rawahi, A. et al. Coupling isotopic and piezometric data to infer groundwater recharge mechanisms in arid areas: example of Samail Catchment, Oman. Hydrogeol J 26, 2561–2573 (2018). https://doi.org/10.1007/s10040-018-1818-y
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DOI: https://doi.org/10.1007/s10040-018-1818-y