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Idowu TE, Jepkosgei C, Nyadawa M, Korowe MO, Waswa RM, Lasisi KH, Kiplangat N, Munyi J, Ajibade FO. Integrated seawater intrusion and groundwater quality assessment of a coastal aquifer: GALDIT, geospatial and analytical approaches. Environ Sci Pollut Res Int 2022; 29:36699-36720. [PMID: 35064491 DOI: 10.1007/s11356-021-18084-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 12/09/2021] [Indexed: 06/14/2023]
Abstract
The pressure and dependence on coastal aquifers are on the rise in many parts of the globe. These lead to overexploitation, aggravated levels of groundwater pollution, and seawater intrusion. Integrated analyses can create holistic insights into the quality and the vulnerability of aquifers to seawater intrusion. In this study, Mombasa North coast's coastal aquifer was characterized by integrating multiple approaches-GALDIT overlay index, seawater intrusion groundwater quality index GQISWI, total hardness, water quality index (WQI)-and the results were further explored and interpreted with geospatial analysis techniques. The study suggests that the predominant water type in areas under moderate or high vulnerabilities to seawater intrusion is the Na-Cl water type. However, similar Na-Cl water types can produce a range of total hardness from soft to hard. GQISWI classification can be used to narrow down the observations from Stuyfzand's TH-based classification system. In the aquifer studied, the results of the GALDIT overlay index, a weighted aggregation of intrinsic parameters contributing to seawater intrusion, show that 29%, 59%, and 12% of the aquifer have low, moderate, and high vulnerabilities, respectively. The GQISWI analysis indicates that the groundwater is largely brackish (68%) but saline towards the southern end of the aquifer at 32%. Total hardness values indicate that 67% of the aquifer's coverage falls under the "moderately hard" category. The geodatabase creation introduced in the study provides a template for similar studies and a baseline for future WQI and water quality monitoring. However, temporal studies on chronological timescales are recommended for sustainable management of the aquifer.
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Affiliation(s)
- Temitope Ezekiel Idowu
- School of Civil and Resource Engineering, Technical University of Kenya, P.O Box 52428-00200, Nairobi, Kenya.
- Center for Applied Coastal Research, University of Delaware, Newark, DE, USA.
| | - Charlynne Jepkosgei
- Department of Geoinformation & Earth Observation, Technical University of Kenya, Nairobi, Kenya
| | - Maurice Nyadawa
- Inst. for Basic Sci. Tech & Innovation-Pan African University at JKUAT, Juja Main Campus, Juja, Kenya
| | - Maurice O Korowe
- Inst. for Basic Sci. Tech & Innovation-Pan African University at JKUAT, Juja Main Campus, Juja, Kenya
- Department of Physics, Jomo Kenyatta University of Agriculture and Technology, Juja, Kenya
| | - Rose M Waswa
- Regional Centre for Mapping of Resources for Development, Nairobi, Kenya
| | - Kayode H Lasisi
- Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China
- Department of Civil and Environmental Engineering, Federal University of Technology Akure, Akure, PMB704, Nigeria
| | - Nelly Kiplangat
- School of Civil and Resource Engineering, Technical University of Kenya, P.O Box 52428-00200, Nairobi, Kenya
| | - Jane Munyi
- School of Civil and Resource Engineering, Technical University of Kenya, P.O Box 52428-00200, Nairobi, Kenya
| | - Fidelis O Ajibade
- Department of Civil and Environmental Engineering, Federal University of Technology Akure, Akure, PMB704, Nigeria
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