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 Polemio & Pavel Povinec		v
1	OVERVIEWS
Background and Summary: A new focus on groundwater–seawater interactions Christian Langevin, Ward Sanford, Maurizio Polemio & Pavel Povinec		3
Regional 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
2	PHYSICAL APPROACHES
Investigations of the brackish karst springs on the Croatian Adriatic Sea coast Ognjen Bonacci & Ivana Gabrić		39
Geoelectric 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
3	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, western Japan Shin-ichi Onodera, Mitsuyo Saito, Masaki Hayashi & Misa Sawano		150
Nutrient inputs through submarine groundwater discharge to Ariake Bay, 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
4	MODELLING APPROACHES
Driving while under the influence: pumping-driven circulation under the influence of regional groundwater flow M. Bayani Cardenas & John L. Wilson		229
Evaluation 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 Xiamen Island 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