Spatial and depth distribution of salinity and nitrate in a depleted alluvial aquifer (Haouz plain, Morocco)
Understanding groundwater contamination processes in depleted aquifers is needed to improve their integrated management. The present study aims to understand how the conditions prevailing in a depleting detritic unconfined aquifer could affect the salinity and nitrate contamination. The depletion ha...
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| Format: | Article |
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Elsevier
2025-02-01
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| Series: | Journal of Hydrology: Regional Studies |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2214581824004920 |
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| author | Hamza Sahraoui Younes Fakir Houssne Bouimouass Sarah Tweed Marc Leblanc Rabia Benaddi Abdelghani Chehbouni |
| author_facet | Hamza Sahraoui Younes Fakir Houssne Bouimouass Sarah Tweed Marc Leblanc Rabia Benaddi Abdelghani Chehbouni |
| author_sort | Hamza Sahraoui |
| collection | DOAJ |
| description | Understanding groundwater contamination processes in depleted aquifers is needed to improve their integrated management. The present study aims to understand how the conditions prevailing in a depleting detritic unconfined aquifer could affect the salinity and nitrate contamination. The depletion has caused a shift in our alluvial aquifer from dominant very shallow groundwater (< 20 m) in the 1970s to dominant deep groundwater (> 40 m) currently. It was found that (i) groundwater was moderately affected by salinity and nitrate, (ii) the dominant hydrochemical factors are rock weathering, halite dissolution, and reverse ion exchange, and (iii) the nitrate contamination is higher in shallow groundwater but it was detected at all depths. The thick unsaturated zone, which has developed because of the decline of the water table, would have mitigated the surface-borne contamination and reduced the direct effects of evapotranspiration. Using tritium as age indicator, it was suggested that nitrate in deep groundwater could originate from a historical use of fertilizers. In addition, vertical flows induced by decreasing water-table from pumping could transport younger groundwater with high loads of nitrate to mix with older deep groundwater with low nitrate. Serious problems could arise from further mobilization of salts by pumping deep groundwater and from the effects of downward movement of contaminants accumulated in the thick unsaturated zone after sufficient migration time or increases in groundwater recharge rates. |
| format | Article |
| id | doaj-art-592c596459b94f10a16a7cbf4f0a4165 |
| institution | Kabale University |
| issn | 2214-5818 |
| language | English |
| publishDate | 2025-02-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Journal of Hydrology: Regional Studies |
| spelling | doaj-art-592c596459b94f10a16a7cbf4f0a41652025-01-22T05:42:12ZengElsevierJournal of Hydrology: Regional Studies2214-58182025-02-0157102143Spatial and depth distribution of salinity and nitrate in a depleted alluvial aquifer (Haouz plain, Morocco)Hamza Sahraoui0Younes Fakir1Houssne Bouimouass2Sarah Tweed3Marc Leblanc4Rabia Benaddi5Abdelghani Chehbouni6Geosciences Semlalia laboratory, Cadi Ayyad University, Marrakech, MoroccoGeosciences Semlalia laboratory, Cadi Ayyad University, Marrakech, Morocco; CRSA, Center for Remote Sensing Applications, Mohammed VI Polytechnic University, Ben Guerir, Green City, Morocco; Correspondence to: Geosciences Semlalia laboratory, Cadi Ayyad University, Bd. Prince My Abdellah, PO box 2390, Marrakech 40000, Morocco.CRSA, Center for Remote Sensing Applications, Mohammed VI Polytechnic University, Ben Guerir, Green City, MoroccoUMR G-eau, IRD, Montpellier, FranceUniversity of Avignon, FranceABHT, Agence du Bassin Hydraulique du Tensift, Marrakech, MoroccoCRSA, Center for Remote Sensing Applications, Mohammed VI Polytechnic University, Ben Guerir, Green City, Morocco; CESBIO, UMR IRD, Toulouse, FranceUnderstanding groundwater contamination processes in depleted aquifers is needed to improve their integrated management. The present study aims to understand how the conditions prevailing in a depleting detritic unconfined aquifer could affect the salinity and nitrate contamination. The depletion has caused a shift in our alluvial aquifer from dominant very shallow groundwater (< 20 m) in the 1970s to dominant deep groundwater (> 40 m) currently. It was found that (i) groundwater was moderately affected by salinity and nitrate, (ii) the dominant hydrochemical factors are rock weathering, halite dissolution, and reverse ion exchange, and (iii) the nitrate contamination is higher in shallow groundwater but it was detected at all depths. The thick unsaturated zone, which has developed because of the decline of the water table, would have mitigated the surface-borne contamination and reduced the direct effects of evapotranspiration. Using tritium as age indicator, it was suggested that nitrate in deep groundwater could originate from a historical use of fertilizers. In addition, vertical flows induced by decreasing water-table from pumping could transport younger groundwater with high loads of nitrate to mix with older deep groundwater with low nitrate. Serious problems could arise from further mobilization of salts by pumping deep groundwater and from the effects of downward movement of contaminants accumulated in the thick unsaturated zone after sufficient migration time or increases in groundwater recharge rates.http://www.sciencedirect.com/science/article/pii/S2214581824004920Groundwater depletionGeochemical processesNitrate levelsAridTensift basin |
| spellingShingle | Hamza Sahraoui Younes Fakir Houssne Bouimouass Sarah Tweed Marc Leblanc Rabia Benaddi Abdelghani Chehbouni Spatial and depth distribution of salinity and nitrate in a depleted alluvial aquifer (Haouz plain, Morocco) Journal of Hydrology: Regional Studies Groundwater depletion Geochemical processes Nitrate levels Arid Tensift basin |
| title | Spatial and depth distribution of salinity and nitrate in a depleted alluvial aquifer (Haouz plain, Morocco) |
| title_full | Spatial and depth distribution of salinity and nitrate in a depleted alluvial aquifer (Haouz plain, Morocco) |
| title_fullStr | Spatial and depth distribution of salinity and nitrate in a depleted alluvial aquifer (Haouz plain, Morocco) |
| title_full_unstemmed | Spatial and depth distribution of salinity and nitrate in a depleted alluvial aquifer (Haouz plain, Morocco) |
| title_short | Spatial and depth distribution of salinity and nitrate in a depleted alluvial aquifer (Haouz plain, Morocco) |
| title_sort | spatial and depth distribution of salinity and nitrate in a depleted alluvial aquifer haouz plain morocco |
| topic | Groundwater depletion Geochemical processes Nitrate levels Arid Tensift basin |
| url | http://www.sciencedirect.com/science/article/pii/S2214581824004920 |
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