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Contents
A New Focus on
Groundwater–Seawater Interactions
Edited by Ward Sanford, Christian Langevin, Maurizio Polemio & Pavel Povinec
IAHS Publ. 312(2007) 978-1-901502-04-6 344 + x pp, price £64.00
Water and chemical fluxes across the sea floor provide an important linkage between terrestrial and marine environments. Oceanographers recognize that these fluxes may act as a source of nutrients or harmful contaminants to marine systems. They may also act as a beneficial source of freshwater for coastal estuaries that require relatively low salinities. Hydrologists and hydrogeologists recognize that fluxes across the sea floor comprise an important part of the water balance for coastal aquifers. Most fresh groundwater discharge to the ocean is derived from terrestrial aquifer recharge. However, excessive groundwater withdrawals from coastal aquifers can cause saltwater intrusion by intercepting the seaward flux. Quantitative estimates of fresh groundwater discharge toward the coast can provide a basis for determining safe withdrawal rates.
Oceanographers, marine scientists, and those studying and managing saltwater intrusion in coastal aquifers, share a common goal of quantification and understanding of groundwater and seawater interactions. The papers in this volume,an outcome of a symposium organised jointly by the IAHS International Commission on Groundwater and the International Association for the Physical Sciences of the Oceans, IAPSO, in 2007,present research by those working from the marine and terrestrial sides of the issues, and cover a variety of investigative approaches applied at locations worldwide. Together, they form an important contribution to the literature.
Contents
Preface by Ward Sanford, Christian Langevin, Maurizio PolemioPavel Povinec
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OVERVIEWS
Background and Summary:A new focus on groundwater–seawater interactions Christian Langevin, Ward Sanford, Maurizio Polemio & Pavel Povinec / 3Regional assessment of groundwater discharge into seas: present-day concepts and methods Igor S. Zektser & Roald G. Dzhamalov / 11
Groundwater–seawater interactions in tsunami affected areas: solutions and applications Evgeny A. Kontar / 19
The importance of shallow confining units to submarine groundwater flow
John F. Bratton / 28
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PHYSICAL APPROACHES
Investigations of the brackish karst springs on the Croatian Adriatic Sea coastOgnjen Bonacci & Ivana Gabrić / 39Geoelectric and geochemical studies for hydrological characterization of Sagar Island, South 24 Parganas, West Bengal, India R. K. Majumdar & D. Das / 50
Investigation of submarine groundwater discharge using several methods in the inter-tidal zone Tomotoshi Ishitobi, Makoto Taniguchi, Yu Umezawa,
Shigeru Kasahara, Shin-Ichi Onodera,Masaki Hayashi, Kunihide Miyaoka
Mitsuru Hayashi / 60
Seasonal changes in the groundwater–seawater interaction and its relation to submarine groundwater discharge, Ise Bay, Japan Kunihide Miyaoka / 68
Basin-wide groundwater flow study in a volcanic low permeability bedrock aquifer with coastal submarine groundwater discharge Jun Shimada,
Daisuke Inoue, Sou Satoh, Naohiko Takamoto, Tomoya Sueda, Yoshitaka Hase, Show Iwagami, Maki Tsujimura, Tomotoshi Ishitobi& Makoto Taniguchi / 75
Comprehensive evaluation of the groundwater–seawater interface and submarine groundwater discharge Makoto Taniguchi, Tomotoshi Ishitobi,
William C. Burnett & Jun Shimada / 86
Possibilities of geophysical survey for groundwater contamination and subsurface pollution determination and monitoring in the coastal zone
Yuriy R. Ozorovich & Evgeny A. Kontar / 93
Multi-channel resistivity investigations of the freshwater–saltwater interface: a new tool to study an old problem Peter W. Swarzenski, Sarah Kruse,
Chris Reich& Wolfgang V. Swarzenski / 100
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CHEMICAL APPROACHES
Remaining uncertainties in the use of Rn-222 as a quantitative tracer of submarine groundwater discharge William C. Burnett, Isaac R. Santos,Yishai Weinstein, Peter W. Swarzenski & Barak Herut / 109
In situ underwater gamma-ray spectrometry as a tool to study groundwater–seawater interactions Pavel P. Povinec / 119
Temporal variability of submarine groundwater discharge: assessments via radon and seep meters, the southern Carmel Coast, Israel Yishai Weinstein,
Yehuda Shalem, William C. Burnett, Peter W. Swarzenski & Barak Herut / 125
Seasonal changes in the radium-226 distribution on the southeastern USA continental shelf: implications for changing submarine groundwater discharge Willard S. Moore / 134
A box model to quantify groundwater discharge along the Kona coast of Hawaii using natural tracers Richard N. Peterson, William C. Burnett, Craig R. Glenn & Adam J. Johnson / 142
Nutrient dynamics with groundwater–seawater interactions in a beach slope of a steep island, westernJapan Shin-ichi Onodera, Mitsuyo Saito, Masaki Hayashi Misa Sawano / 150
Nutrient inputs through submarine groundwater discharge to AriakeBay, Kyushu Island, Japan Jun Yasumoto, Mamoru Katsuki, Hidetomo Takaoka,
Yoshinari Hiroshiro & Kenji Jinno / 159
Evaluation of fresh groundwater contributions to the nutrient dynamics at shallow subtidal areas adjacent to metro-Bangkok Yu Umezawa, Tomotoshi Ishitobi, Sompop Rungsupa, Sinichi Onodera, Tsutomu Yamanaka, Chikage Yosimizu, Ichiro Tayasu, Toshi Nagata, Gullaya Wattayakorn & Makoto Taniguchi / 169
Influence of groundwater discharge through a coastal sandy barrier in southern Brazil on seawater metal chemistry Herbert Windom, Willard Moore &
Felipe Niencheski / 180
Chemical and isotopic characteristics of stagnant water isolated in a coastal area Yasunori Mahara, Eiji Nakata, Takahiro Ooyama, Kimio Miyakawa,
Yoshihisa Ichihara & Hiroyuki Matsumoto / 189
Existence of stagnant fresh groundwater and diffusion-limited chloride migration in a sub-sea formation at Yatsushiro Bay, Japan Tomochika Tokunaga,
Yuki Kimura & Jun Shimada / 197
Indicators and quality classification applied to groundwater management in coastal aquifers: case studies of Mar del Plata (Argentina) and Apulia (Italy)
E. M. Bocanegra, M. Polemio, H. E. Massone, V. Dragone, P. P. Limoni &
M. Farenga / 201
Isotopic characterization of saline intrusion into the aquifers of a coastal zone: case study of the southern Venice lagoon, Italy Julie C. Gattacceca,
Christine Vallet-Coulomb, Adriano Mayer, Olivier Radakovitch, Enrico Conchetto, Corinne Sonzogni, Christelle Claude & Bruno Hamelin / 212
Modélisation de l’intrusion marine dans l’aquifère côtière du Gabès (sud tunisien) / Seawater intrusion modelling for the Gabes coastal aquifer system (southern Tunisia) Badiaa Chulli,Abdalah Taheri Tizro& Nasime Jabnoun / 219
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MODELLING APPROACHES
Driving while under the influence: pumping-driven circulation under the influence of regional groundwater flow M. Bayani Cardenas & John L. Wilson / 229Evaluation of the hydraulic gradient at an island for low-level nuclear waste disposal Prem Attanayake & Michael Sholley / 237
Climatic variation, recharge and freshwater lens salinity of a coral atoll in the Pacific Ocean M. van der Velde, M. Vakasiuola, S. R. Green, V. T. Manu,
V. Minonesi, M. Vanclooster & B. E. Clothier / 244
Effect of an offshore sinkhole perforation in a coastal confined aquifer on submarine groundwater discharge Sarah E. Fratesi, H. Leonard Vacher &
Ward E. Sanford / 256
Numerical modelling to determine the freshwater/saltwater interface configuration in a low-gradient coastal wetland aquifer
Eric Swain & Melinda Wolfert / 264
Simulation of submarine groundwater discharge salinity and temperature variations: implications for remote detection Alyssa M. Dausman,
Christian D. Langevin & Michael C. Sukop / 272
Submarine groundwater discharge under extreme rainfall events Eunhee Lee, Yunjung Hyun & Kang-Kun Lee / 281
Impact of a water diversion project on the groundwater environment of XiamenIsland Liu Zhenghua, Huang Hao, Liu Jianli, Wang Jinkeng & Chen Bin / 287
Three-dimensional numerical simulation of density-dependent groundwater flow and salt transport due to groundwater pumping in a heterogeneous and true anisotropic coastal aquifer system Ju-Hyun Park, Chan-Sung Oh & Jun-Mo Kim / 294
Numerical modelling of saltwater–freshwater interaction in the Walawe River basin, Sri Lanka Priyantha Ranjan, So Kazama& Masaki Sawamoto / 306
Seawater intrusion in the coastal aquifer of Wadi Ham, UAE
Mohsen Sherif & Anvar Kacimov / 315
A simulation of groundwater discharge and nitrate delivery to Chesapeake Bay from the lowermost Delmarva Peninsula, USA Ward E. Sanford &
Jason P. Pope / 326
Effect of tidal fluctuations on contaminant transfer to the ocean Ivana La Licata, Christian D. Langevin & Alyssa M. Dausman / 334
Key word index / 343
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A New Focus on Groundwater–Seawater Interactions (Proceedings of Symposium HS1001 at IUGG2007, Perugia, July 2007). IAHS Publ. 312, 2007, 3-10.
BACKGROUND AND SUMMARY
A new focus on groundwater–seawater interactions
Christian Langevin1, Ward Sanford2, Maurizio Polemio3 & Pavel Povinec4
1Florida Integrated Science Center, US Geological Survey, Fort Lauderdale, Florida, USA
2National Center, US Geological Survey, Reston, Virginia, USA
3Consiglio Nazionale delle Ricerche, Istituto di Ricerca per la Protezione Idrogeologica, Bari, Italy
4Mathematics, Physics, and Informatics, ComeniusUniversity, Bratislava, Slovakia
A New Focus on Groundwater–Seawater Interactions (Proceedings of Symposium HS1001 at IUGG2007, Perugia, July 2007). IAHS Publ. 312, 2007, 11-18.
Regional assessment of groundwater discharge into seas: present-day concepts and methods
IGOR S. ZEKTSER & ROALD G. DZHAMALOV
Water Problems Institute, RussianAcademy of Sciences, 3 Gubkina Street, 119991 Moscow, Russia
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Abstract Studies of groundwater discharge into the seas and oceans are part of a complex hydrological–hydrogeological problem of underground water exchange between land and sea. Submarine discharge into seas and oceans is the least studied element of the present and prospective water and salt balance of the seas. Primarily, this is because groundwater inflow is the only water balance component that cannot be measured, and data needed for a well-grounded calculation of a water balance underground component are often missing. Therefore, it is important to determine this directly by hydrogeological methods. These methods permit areas of submarine groundwater discharge to be singled out and quantitatively characterized and, in some cases, make it possible to calculate the value of groundwater discharge causing these anomalies. The results of estimating the groundwater discharge to some seas and major lakes are considered.
Key words groundwater discharge; water balance; subsurface water exchange; subaqueous groundwater
A New Focus on Groundwater–Seawater Interactions (Proceedings of Symposium HS1001 at IUGG2007, Perugia, July 2007). IAHS Publ. 312, 200, 19-27.
Groundwater–seawater interactions in tsunami affected areas: solutions and applications
EVGENY A. KONTAR
International Commission on Groundwater–Seawater Interactions (CGSI), Moosstrasse 25, CH-3113 Rubigen, Switzerland and P. P. Shirshov Institute of Oceanology, Russian Academy of Sciences, 36, Nakhimovsky Prospekt, Moscow 117851, Russia
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Abstract The December 2004 tsunami in the Indian Ocean caused a disaster affecting thousands of kilometres of coastal zone in SE Asia. Many coastal wetlands were affected in the short term bythe large inflow of salt seawater and littoral sediment deposited duringthe tsunami, and in the longer-term by changes in theirhydrogeology caused by changes to coastlines and damage to sea-defences.Many water quality and associated problems were generated by the tsunami. The tsunami has createdan accelerating process of salt-water intrusion and freshwatercontamination in the affected regions that now require drastic remediationmeasures. According to the International Commission on Groundwater–Seawater Interaction (CGSI) these measures have to be economically feasible,environmentally sound and socially acceptable. We report here some results of preparation of the CGSI EU FP7 project related to the study of the processes of groundwater–seawater interactions in tsunami affected areas.
Key words coastal zone; submarine groundwater discharge; salt-water intrusion; tsunami; groundwater–seawater interactions
A New Focus on Groundwater–Seawater Interactions (Proceedings of Symposium HS1001 at IUGG2007, Perugia, July 2007). IAHS Publ. 312, 200, 28-36.
The importance of shallow confining units to submarine groundwater flow
JOHN F. BRATTON
US Geological Survey, 384 Woods Hole Rd, Woods Hole, Massachusetts 02556, USA
Abstract In addition to variable density flow, the lateral and vertical heterogeneity of submarine sediments creates important controls on coastal aquifer systems. Submarine confining units produce semi-confined offshore aquifers that are recharged on shore. These low-permeability deposits are usually either late Pleistocene to Holocene in age, or date to the period of the last interglacial highstand. Extensive confining units consisting of peat form in tropical mangrove swamps, and in salt marshes and freshwater marshes and swamps at mid-latitudes. At higher latitudes, fine-grained glaciomarine sediments are widespread. The net effect of these shallow confining units is that groundwater from land often flows farther offshore before discharging than would normally be expected. In many settings, the presence of such confining units is critical to determining how and where pollutants from land will be discharged into coastal waters. Alternatively, these confining units may also protect fresh groundwater supplies from saltwater intrusion into coastal wells.
Key wordsAtlantic; coastal aquifer; confining unit; glaciomarine; groundwater; mangrove; peat; salt marsh; saltwater intrusion; nutrients
A New Focus on Groundwater–Seawater Interactions (Proceedings of Symposium HS1001 at IUGG2007, Perugia, July 2007). IAHS Publ. 312, 2007, 39-49.
Investigations of the brackish karst springs on the Croatian Adriatic Sea coast
OGNJEN BONACCI & IVANA GABRIĆ
Faculty of Civil Engineering and Architecture, University of Split, Matice hrvatske15, 21000Split, Croatia
Abstract The Croatian Adriatic Sea coast is a highly and deeply karstified area. Thus its coastal aquifers are open to seawater intrusion. There are many coastal karst springs, and the vast majority of them are brackish year round, or during periods of low summer discharges. Increasing development of these areas threatens to cause a shortage of fresh water. Consequently, there is an increased need for developing water reserves in the coastal aquifers and understanding the mechanism of seawater intrusion. This paper gives an overview of eight selected coastal brackish karst springs along the Croatian Adriatic Sea coast. An explanation of their functioning, an overview of measures taken for the prevention of seawater intrusion in some of them, and the practical success of those measures is given.
Key words coastal karst; brackish karst springs;seawater intrusion;Croatia
A New Focus on Groundwater–Seawater Interactions (Proceedings of Symposium HS1001 at IUGG2007, Perugia, July 2007). IAHS Publ. 312, 2007, 50-59.
Geoelectric and geochemical studies for hydrological characterization of Sagar Island, South 24 Parganas, West Bengal, India
R. K. MAJUMDAR & D. DAS
Department of Geological Sciences, JadavpurUniversity, Kolkata-700032,West Bengal, India
Abstract Integrated geoelectric and geochemical investigation were carried out in the SagarIsland region to assess the prevailing groundwater conditions and chemical quality of groundwater. Geologically, the area is constituted of alluvial and marine sediments of Quaternary age. Vertical electrical soundings (VES) in the area of investigation mostly show five layers consisting of topsoil, saline water, brackish water, a clay layer and freshwater-bearing zones. The VES findings show the potential freshwater-bearing zone to be of appreciable thickness at depths of 175.0 to 220.0 m under confined conditions. The surface true resistivity contour map shows the intrusion of saline water in the southern part of SagarIsland at shallower depths. The results of VES studies significantly correspond with the borehole data. Chemically, the fresh groundwater is Na-HCO3 type with TDS ranging from 465 to 645 mg/L. The water is safe for drinking and domestic purposes but unsuitable for irrigation purposes. The concentrations of arsenic, iron, lead and mercury in the samples are below the recommended limit for drinking water of the World Health Organization (WHO).
Keywords SagarIsland; Vertical Electric Sounding (VES); litho-resistivity relation; seawater contamination (SWC); freshwater aquifer
A New Focus on Groundwater–Seawater Interactions (Proceedings of Symposium HS1001 at IUGG2007, Perugia, July 2007). IAHS Publ. 312, 2007., 60-67
Investigation of submarine groundwater discharge using several methods in the inter-tidal zone
TOMOTOSHI ISHITOBI1, MAKOTO TANIGUCHI1, YU UMEZAWA1,
SHIGERU KASAHARA2, SHIN-ICHI ONODERA3,MASAKI HAYASHI4, KUNIHIDE MIYAOKA5 MITSURU HAYASHI6
1 Research Institute for Humanity and Nature, 457-4 Motoyama, Kamigamo, Kita-ku, Kyoto 603-8047,Japan
2 Sohgoh kagaku Inc., 1-4-8 Minami-Shin-Machi, Chuo-ku, Osaka 540-0024, Japan
3 Faculty of Integrated Arts and Sciences, HiroshimaUniversity, 1-7-1 Kagamiyama, Higashi-Hiroshima 739-8521, Japan
4 GraduateSchool of Biosphere Science, HiroshimaUniversity, 1-7-1 Kagamiyama, Higashi-Hiroshima 739-8521, Japan
5 Faculty of Education, MieUniversity, 1577 Kurimamachiya-cho, Tsu 514-8507, Japan
6 ResearchCenter for InlandSeas, KobeUniversity, 5-1-1 Fukae-Minami-Machi, Higashi-nada-ku, Kobe 658-0022, Japan
Abstract To accurately estimate the flux of terrestrial groundwater discharge into the sea, a study using several methods was done in the coastal zone of Osaka Bay, Japan. The seepage-meter method and the measurement of temperature near the seabed were applied based on the hypothesis that seawater temperature in summer would decrease, reflecting the extent of active mixing with colder fresh groundwater. As a result, it was confirmed from the seepage-meter method that submarine groundwater discharge rates decreased with the distance from the coast. Evaluations of groundwater discharge rates from seabed temperature showed similar values to the results using the seepage meter, which means that the values were reasonable. Finally, the total groundwater discharge flux from this beach was estimated at 36.7% of the river discharge rate.
Key words submarine groundwater discharge; inter-tidal zone; seepage meter; seabed temperature
A New Focus on Groundwater–Seawater Interactions (Proceedings of Symposium HS1001 at IUGG2007, Perugia, July 2007). IAHS Publ. 312, 2007,68-74
Seasonal changes in the groundwater–seawater interaction and its relation to submarine groundwater discharge, Ise Bay, Japan
Kunihide MIYAOKA
Department of Geography, MieUniversity, 1577 Kurima-machiya, Tsu, Mie 514-8507, Japan
Abstract The purpose of this study is to elucidate the conditions of seasonal changes in the fresh and salt water distribution, and the control factors of the relationship between the groundwater flow system and submarine groundwater discharge (SGD) at Ise Bay, Japan. The results indicate that the groundwater levels and qualities have different seasonal change patterns in each depth at the measurement sites. Deep freshwater discharges as SGD in the irrigation season. The water quality of the SGD changes is affected by groundwater–seawater interaction. Seasonal changes in the groundwater–seawater interaction are controlled by geology, recharge water, and tidal conditions.
Key words geological conditions; groundwater flow system; resistivity; seasonal changes; submarine groundwater discharge (SGD); tidal conditions
A New Focus on Groundwater–Seawater Interactions (Proceedings of Symposium HS1001 at IUGG2007, Perugia, July 2007). IAHS Publ. 312, 2007, 75-85.
Basin-wide groundwater flow study in a volcanic low permeability bedrock aquifer with coastal submarine groundwater discharge