Parameter Estimation and Vulnerability Assessment of Coastal Unconfined Aquifer to Saltwater Intrusion
Publication: Journal of Hydrologic Engineering
Volume 17, Issue 8
Abstract
The focus of the present work is to characterize a tropical, coastal aquifer and to carry out its vulnerability to saltwater intrusion using hydrogeological parameters. The characterization of the aquifer involves pumping tests, vertical electrical sounding, and water quality analysis carried out at 41 monitoring wells. The area under investigation lies between two tropical, seasonal, tidal rivers, i.e., Pavanje and Gurpur rivers, joining the Arabian on the west coast of India. The aquifer is predominantly shallow and unconfined, having moderate to good groundwater potential with transimissivity and specific yield ranging from 49.2 to and 0.00058 to 0.2805, respectively. The electrical resistivity tests indicated that the thickness of the aquifer ranges from 18 to 30 m. The study also investigates the saltwater affected areas in the region the vertical electrical sounding and water quality analysis. The resistivity results revealed several probable isolated saltwater intruded pockets in the region with resistivity less than 70 Ωm. From the salinity analysis of water, the locations that are affected during February to May (summer) and throughout the year are identified. The wells that are located close to the coast () and at lower elevations (well bottom ) were found to be saline throughout the year. Also, wells along the banks of the river show considerable salinity () during the summer period from tidal inflow along the rivers. The water samples were also analyzed for chloride to bicarbonate ratios during December to May at all the monitoring wells and were found to be exceeding the allowable limit at several locations. The saltwater vulnerability maps are derived for the area by the index-based method using the hydrogeological parameters. The method was found to be effective while compared to the field observations. The results from the analysis indicate that the aquifer is medium to highly vulnerable to saltwater intrusion at majority of the locations. The impact of projected sea level rise by 0.25 and 0.50 m from the climate change is also assessed on the vulnerability of the region to saltwater intrusion.
Get full access to this article
View all available purchase options and get full access to this article.
Acknowledgments
The authors are grateful to the Indian National Committee on Hydrology (INCOH), Ministry of Water Resources, Government of India (Grant No. 23/24/2002-R&D/2056 dtd. September 12, 2004) for the financial support to carry out the investigation.
References
Aggarwal, D., and Lal, M. (2001). “Vulnerability of Indian coastline to sea level rise.” Proc., APN/SURVAS/LOICZ Joint Conf. on Coastal Impacts of Climate Change and Adaption in the Asia-Pacific Region, Mimura, N. and Yokki, H., eds., Asian-Pacific Network for Global Change Research, Kobe, Japan, and Center for Water Environment Studies, Ibaraki Univ., Japan, 65–73, 〈www.survas.mdx.ac.uk/kobeproc〉 ( Jul. 10, 2007).
Aller, L., Bennett, T., Lehr, J. H., and Petty, R. J. (1987). “DRASTIC: A standardized system for evaluating groundwater pollution potential using hydrogeologic settings.” U.S. Environmental Protection Agency Rep. 600/ 2-85/018.
Barrocu, G., Muzzu, M., Staffa, F., Testa, M., Uras, G. (2006). “The GALDIT method to map the vulnerability to saltwater intrusion in the Arborea coastal aquifer (central-western Sardinia).” Programme Abstracts, Ist SWIM-SWICA, 19th Saltwater Intrusion Meeting, 3rd Saltwater Intrusion in Coastal Aquifers, 24–29.
Bear, J., and Verruijt, A. (1987). Modeling groundwater flow and pollution, D. Reidel Publishing, Dordrecht, Holland.
Boulton, N. S. (1954). “Unsteady radial flow to a pumped well allowing for delayed yield from storage.” Int. Assn. Sci. Hydrol., Rome, Publ., 37, 472–477.
Boulton, N. S. (1963). “Analysis of data from non-equilibrium pumping tests allowing for delayed yield from storage.” Proc., Institute of Civil Engineers, 26, 469–482.
Chachadi, A. G., and Ferreira, J. P. L. (2001). “Sea water intrusion vulnerability mapping of aquifers using GALDIT method.” Proc., Workshop on Modeling in Hydrogeology, Anna Univ., Chennai, India, 143–156.
Chachadi, A. G., Ferreira, J. P. L., Ligia, N., and Choudri, B. S. (2005). “Assessing the impact of sea-level rise on saltwater intrusion in coastal aquifers using GALDIT model.” 〈http://www.dha.lnec.pt/nas/estudos/COASTIN.htm〉 (Nov. 2, 2006).
Dept. of Applied Mechanics and Hydraulics. (1996). “Testing and analysis of soil samples.” A Report, National Institute of Technology Karnataka, Surathkal, India.
Edet, A. E., Okereke, C. S. (2001). “A regional study of saltwater intrusion in Southeastern Nigeria based on the analysis of geoelectrical and hydrochemical data.” Environ. Geol.ENGOE9, 40(10), 1278–1289.
Ferreira, J. P. L., and Cabral, M. (1991). “Proposal for an operational definition of vulnerability of the European community’s Atlas of groundwater resources.” Meeting of the European Institute for Water, Groundwater Work Group, Brussels, Belgium.
Ferreira, J. P. L., Chachadi, A. G., Catarina, D., and Henriques, M. J. (2005). “Assessing aquifer vulnerability to sea-water intrusion using GALDIT method: Part 1.” IAHS and LNEC, Proc., 4th Inter Celtic Colloquium on Hydrology and Management of Water Resources, Universidade do Minho, Guimaraes, Portugal.
Fitterman, D. (1996). “Geophysical mapping of the freshwater/saltwater interface in Everglades National Park, Florida.” U.S. Geological Survey Fact Sheet, FS-173-96.
Fretwell, J. D., and Stewart, M. T. (1981). “Resistivity study of a coastal karst terrain, Florida.” Ground WaterGRWAAP, 19(2), 156–162.
Intergovernmental Panel on Climate Change. (2001). “Climate change 2001: Synthesis report.” Third Assessment Report, Intergovernmental Panel on Climate Change, 〈http://www.ipcc.ch/publications_and_data/publications_and_data_reports.shtml〉 (Nov. 11, 2007).
Jayappa, K. J. (1991). “A textural and mineralogical study of the beach sands between Talapady and Surathkal, Karnataka.” J. Geotechnical Society of IndiaIGTJAG, 37, 151–163.
Loke, M. H. (2004). “2D, 3D electrical imaging survey.” 〈www.geoelectrical.com〉.
Lokesh, K. N. (1989). “Rainfall distribution and trend analysis of Sitanadi basin in Dakshnina Kannada district of the west coast of India.” Proc., WMD/IAHS/ETH Int. Workshop on Precipitation Measurement, Sevruk, B., ed., Swiss Federal Institute of Technology, Zurich, 293–298.
Lokesh, K. N. (1997). “Some principles and methods for mineral exploration: An overview.” National Seminar on Emerging Technology in Surface Mining and Environmental Challenges, Dept. of Mining Engineering, Karnataka Regional Engineering College, Surathkal, India, 63–66.
Masterson, J. P., and Garabedian, S. P. (2009). “Effects of sea level rise on groundwater flow in a coastal aquifer system.” Ground WaterGRWAAP, 45(2), 115–250.
Moench, A. F. (1994). “Specific yield as determined by type-curve analysis of aquifer-test data.” Ground WaterGRWAAP, 32(6), 949–957.
Nath, S. K., Patra, H., and Shahid, S., Eds.(2000). Geophysical prospecting for ground water, Balkema, Rotterdam, The Netherlands.
Neuman, S. P. (1972). “Theory of flow in unconfined aquifers considering delayed response of the water table.” Water Resour. Res.WRERAQ, 8(4), 1031–1045.
Neuman, S. P. (1974). “Effects of partial penetration on flow in unconfined aquifers considering delayed aquifer response.” Water Resour. Res.WRERAQ, 10(2), 303–312.
Raghunath, R., Murthy, S. T. R., and Raghavan, B. R. (2001). “Aquifer parameter evaluation of Nethravathi River basin, Karnataka State, India.” J. Applied HydrologyJAHOCA, 12(1), 46–51.
Ranganna, G., Gajendragad, M. R., Lokesh, K. N., and Harshendra, K. (1985). “Hazardous effects of salinity in coastal area affecting crop yield.” Res. Project Rep., Ministry of Water Resources, G. O. I., Dept. of Applied Mechanics and Hydraulics, Karnataka Regional Engineering College, Surathkal, Karnataka State, India.
Rao, B. N. (1974). “Geotechnical investigations of the marine deposits in the Mangalore harbor project.” Indian Geotech. J.IGTJAG, 4(1), 78–92.
Srikantiah, H. R. (1987). “Laterite and lateritic soils of west coast of India.” Proc. 9th South-east Asian Geotechnical Conference, Asian Institute of Technology, Bangkok, Thailand, 5–159–5–169.
Information & Authors
Information
Published In
Journal of Hydrologic Engineering
Volume 17 • Issue 8 • August 2012
Pages: 933 - 943
Copyright
© 2012. American Society of Civil Engineers.
History
Received: Nov 19, 2010
Accepted: Oct 20, 2011
Published online: Oct 24, 2011
Published in print: Aug 1, 2012
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.