The Influence of tidal distortion on extreme water levels in Casamance estuary, Senegal.

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Amadou Diouf, Issa Sakho, Bamol Ali Sow, Julien Deloffre, Mouhamadoul Bachir Diouf, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4202876/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 03 Jan, 2025 Read the published version in Estuaries and Coasts → Version 1 posted 5 You are reading this latest preprint version Abstract The Casamance estuary in Senegal is experiencing hypersalination and silting, which are negatively impacting its mangrove ecosystem and maritime navigation. This is a critical issue for both biodiversity preservation and economic development. However, research and documentation on this estuary, particularly with regard to tides, have been relatively neglected. The focus of this study is on the impact of tidal asymmetry on extreme water levels in the region. Tide data was collected at the river entrance and at Ziguinchor, and analysed using digital tools such as Tide Peaks Toolbox and UTide. The results indicate that the average tidal range at Ziguinchor varies from 33 cm to 65 cm, with peaks in February and March and troughs in January and March. The duration of the ebb tide varies, with a duration of over 4 hours during spring tides and 2 hours during neap tides. During the dry season, the duration is extended to 3 hours and 30 minutes, leading to a greater accumulation of water upstream of the estuary, particularly in July. Maximum velocities of up to 30 cm/s are observed at the start of high tide, mainly in February. Harmonic analysis conducted over a six-month period indicates a reduction in amplitude of over 45% for semi-diurnal and diurnal waves. Additionally, there is a significant amplification of the upper diurnal waves, with a more asymmetry upstream of the estuary. Additionally, the analysis of residual water levels and currents emphasizes the complexity of tidal dynamics, particularly due to non-tidal influences. This study constitutes a good contribution to the understanding of the hydrodynamic functioning of estuarine systems in West Africa marked by a strong climatic contrast. tide Casamance estuary asymmetry extreme water levels Senegal Full Text Cite Share Download PDF Status: Published Journal Publication published 03 Jan, 2025 Read the published version in Estuaries and Coasts → Version 1 posted Reviewers agreed at journal 09 Apr, 2024 Reviewers invited by journal 09 Apr, 2024 Editor invited by journal 05 Apr, 2024 Editor assigned by journal 03 Apr, 2024 First submitted to journal 02 Apr, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4202876","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":289294887,"identity":"e9ce9cb1-1f38-44cf-8e70-89844e4952fe","order_by":0,"name":"Amadou Diouf","email":"","orcid":"","institution":"Université Assane SECK de Ziguinchor: Universite Assane SECK de Ziguinchor","correspondingAuthor":false,"prefix":"","firstName":"Amadou","middleName":"","lastName":"Diouf","suffix":""},{"id":289294888,"identity":"5f5e522a-5b4a-418e-b6e5-b3f86e0c5b9e","order_by":1,"name":"Issa 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