Geophysical Assessment of Seawater Intrusion into Coastal Aquifers of Bela Plain, Pakistan
Seawater intrusion is a major challenge in many coastal areas all around the world, mainly caused by over-exploitation of freshwater resources, climate change, and sea-level rise. Consequently, seawater intrusion reaches several kilometers inland, thus making the freshwater resources polluted and un...
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MDPI AG
2020-12-01
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| Series: | Water |
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| Online Access: | https://www.mdpi.com/2073-4441/12/12/3408 |
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| author | Muhammad Hasan Yanjun Shang Weijun Jin Peng Shao Xuetao Yi Gulraiz Akhter |
| author_facet | Muhammad Hasan Yanjun Shang Weijun Jin Peng Shao Xuetao Yi Gulraiz Akhter |
| author_sort | Muhammad Hasan |
| collection | DOAJ |
| description | Seawater intrusion is a major challenge in many coastal areas all around the world, mainly caused by over-exploitation of freshwater resources, climate change, and sea-level rise. Consequently, seawater intrusion reaches several kilometers inland, thus making the freshwater resources polluted and unsuitable for human use. Conventionally, the fresh-saline water interface is delineated by the number of laboratory tests obtained from boreholes. However, such tests suffer from efficiency in terms of data coverage, time, and cost. Hence, this work introduces Dar-Zarrouk (D-Z) parameters, namely transverse resistance (T<sub>r</sub>), longitudinal conductance (S<sub>c</sub>), and longitudinal resistivity (<i>ρ</i><sub>L</sub>) computed from non-invasive vertical electrical sounding (VES). Two-dimensional (2D) imaging of D-Z parameters provides a clear distinction of fresh-saline aquifers. Such techniques remove ambiguities in the resistivity interpretation caused by overlapping of fresh and saline aquifers during the process of suppression and equivalence. This study was carried out by 45 VES along five profiles in the coastal area of Bela Plain, Pakistan. D-Z parameters delineate fresh, brackish, and saline aquifers with a wide range of values such as freshwater with T<sub>r</sub> > 2000 Ωm<sup>2</sup>, S<sub>c</sub> < 3 mho, and <i>ρ</i><sub>L</sub> > 20 Ωm; saline water with T<sub>r</sub> < 1000 Ωm<sup>2</sup>, S<sub>c</sub> > 25 mho, and <i>ρ</i><sub>L</sub> < 5 Ωm; and brackish water with T<sub>r</sub> between 1000–2000 Ωm<sup>2</sup>, S<sub>c</sub> from 3 to 25 mho, and <i>ρ</i><sub>L</sub> between 5–20 Ωm. The D-Z results were validated by the physicochemical analysis using 13 water samples and local hydrogeological setting. The obtained results propose that D-Z parameters can be used as a powerful tool to demarcate the fresh-saline aquifer interface with more confidence than other traditional techniques. This geophysical approach can reduce the expensive number of borehole tests, and hence contributes to the future planning and development of freshwater resources in the coastal areas. |
| first_indexed | 2024-03-10T14:20:27Z |
| format | Article |
| id | doaj.art-5f4dc2bd840d4ad3a297664c99ac6479 |
| institution | Directory Open Access Journal |
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| spelling | doaj.art-5f4dc2bd840d4ad3a297664c99ac64792023-11-20T23:26:59ZengMDPI AGWater2073-44412020-12-011212340810.3390/w12123408Geophysical Assessment of Seawater Intrusion into Coastal Aquifers of Bela Plain, PakistanMuhammad Hasan0Yanjun Shang1Weijun Jin2Peng Shao3Xuetao Yi4Gulraiz Akhter5Key Laboratory of Shale Gas and Geoengineering, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, ChinaKey Laboratory of Shale Gas and Geoengineering, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, ChinaKey Laboratory of Shale Gas and Geoengineering, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, ChinaKey Laboratory of Shale Gas and Geoengineering, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, ChinaKey Laboratory of Shale Gas and Geoengineering, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, ChinaDepartment of Earth Sciences, Quaid-i-Azam University, Islamabad 45320, PakistanSeawater intrusion is a major challenge in many coastal areas all around the world, mainly caused by over-exploitation of freshwater resources, climate change, and sea-level rise. Consequently, seawater intrusion reaches several kilometers inland, thus making the freshwater resources polluted and unsuitable for human use. Conventionally, the fresh-saline water interface is delineated by the number of laboratory tests obtained from boreholes. However, such tests suffer from efficiency in terms of data coverage, time, and cost. Hence, this work introduces Dar-Zarrouk (D-Z) parameters, namely transverse resistance (T<sub>r</sub>), longitudinal conductance (S<sub>c</sub>), and longitudinal resistivity (<i>ρ</i><sub>L</sub>) computed from non-invasive vertical electrical sounding (VES). Two-dimensional (2D) imaging of D-Z parameters provides a clear distinction of fresh-saline aquifers. Such techniques remove ambiguities in the resistivity interpretation caused by overlapping of fresh and saline aquifers during the process of suppression and equivalence. This study was carried out by 45 VES along five profiles in the coastal area of Bela Plain, Pakistan. D-Z parameters delineate fresh, brackish, and saline aquifers with a wide range of values such as freshwater with T<sub>r</sub> > 2000 Ωm<sup>2</sup>, S<sub>c</sub> < 3 mho, and <i>ρ</i><sub>L</sub> > 20 Ωm; saline water with T<sub>r</sub> < 1000 Ωm<sup>2</sup>, S<sub>c</sub> > 25 mho, and <i>ρ</i><sub>L</sub> < 5 Ωm; and brackish water with T<sub>r</sub> between 1000–2000 Ωm<sup>2</sup>, S<sub>c</sub> from 3 to 25 mho, and <i>ρ</i><sub>L</sub> between 5–20 Ωm. The D-Z results were validated by the physicochemical analysis using 13 water samples and local hydrogeological setting. The obtained results propose that D-Z parameters can be used as a powerful tool to demarcate the fresh-saline aquifer interface with more confidence than other traditional techniques. This geophysical approach can reduce the expensive number of borehole tests, and hence contributes to the future planning and development of freshwater resources in the coastal areas.https://www.mdpi.com/2073-4441/12/12/3408coastal aquifersfresh-saline interfaceseawater intrusionDar-Zarrouk parameterselectrical resistivityBela Plain |
| spellingShingle | Muhammad Hasan Yanjun Shang Weijun Jin Peng Shao Xuetao Yi Gulraiz Akhter Geophysical Assessment of Seawater Intrusion into Coastal Aquifers of Bela Plain, Pakistan Water coastal aquifers fresh-saline interface seawater intrusion Dar-Zarrouk parameters electrical resistivity Bela Plain |
| title | Geophysical Assessment of Seawater Intrusion into Coastal Aquifers of Bela Plain, Pakistan |
| title_full | Geophysical Assessment of Seawater Intrusion into Coastal Aquifers of Bela Plain, Pakistan |
| title_fullStr | Geophysical Assessment of Seawater Intrusion into Coastal Aquifers of Bela Plain, Pakistan |
| title_full_unstemmed | Geophysical Assessment of Seawater Intrusion into Coastal Aquifers of Bela Plain, Pakistan |
| title_short | Geophysical Assessment of Seawater Intrusion into Coastal Aquifers of Bela Plain, Pakistan |
| title_sort | geophysical assessment of seawater intrusion into coastal aquifers of bela plain pakistan |
| topic | coastal aquifers fresh-saline interface seawater intrusion Dar-Zarrouk parameters electrical resistivity Bela Plain |
| url | https://www.mdpi.com/2073-4441/12/12/3408 |
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