Dynamique du maximum de turbidité dans le système estuarien du Wouri (Cameroun)

Fotsi, Yannick Fossi; Brenon, Isabelle; Pouvreau, Nicolas; Onguéné, Raphaël; Ferret, Yann; Djombe, Dieudonné; Coulombier, Thibault; Étamé, Jacques

doi:10.5150/jngcgc.2020.025

Cited by 4 publications

(3 citation statements)

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“…This is certainly related to the complexities of oceanographic phenomena that affect the city owing to its location in the estuary (Sone et al 2023). This is corroborated by the fact that only few investigations have been published (Kourtitonsky 2005;Onguene et al 2015;Fotsi Fossi 2022) in the lower part of this estuary leaving the upper section unexplored. Inversely, it is the upper section of this estuary that provides the city of Douala with the required ecosystems services (aquatic animals as food, medical plants, sand for construction, freshwater for domestic and agricultural uses.).…”

Section: Introductionmentioning

confidence: 93%

Salinity Distribution in a Tropical River-Estuary Continuum through Numerical Modelling: Case of the Wouri-Nkam River Estuary, Cameroon

Besack,

Ebonji,

Ajonina

et al. 2024

Preprint

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In estuaries environments, the distribution of salinity controls the resourcing of freshwater for agriculture, aquaculture and human consumption; it also regulates the functioning of critical natural habitats. Consequently, there is a particular need for a better understanding of the salinity distribution along river estuaries continuum and for simple predictive relationships linking salinity to estuarine characters and hence environmental conditions. Despite numerous global insightful studies, there are limited studies regarding the spatial patterns of salinity distribution in African estuarine systems. The present study fills this gap using idealized 1-dimentional (1-D) modelling of the Wouri-Nkam River Estuary, Cameroon under various seasonal and tidal conditions. The model results reveal a seasonal tidal excursions varying from 21.4 km (dry season), 18.1 km (transition season), and 14.66 km (wet season). The model performs best during the wet and transition seasons. The year 2050 and 2100 predictions reveal salt intrusion distance of 21 km and 41 km, respectively, indicating that the whole estuary and its surrounding environment will be polluted by marine water in the latter year. The results of this study are important for the region's water resource managers and decision-makers in mitigating the effects of climate change and associated Sea Level Rise (2100 scenario) on the coastal ecosystems since their continuous modification will negatively impact the living standard of Cameroon’s growing population, and the sub region at large.

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Section: Introductionmentioning

confidence: 93%

Salinity Distribution in a Tropical River-Estuary Continuum through Numerical Modelling: Case of the Wouri-Nkam River Estuary, Cameroon

Besack,

Ebonji,

Ajonina

et al. 2024

Preprint

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“…Instantaneous residuals are highly sensitive to temporal shifts in observations. The authors identify several artificial over-and undershoots that can be attributed solely to the time lags between flood and ebb (Fossi, 2022;Latapy et al 2023). Therefore, a detailed analysis of residual water levels and currents was conducted during High Water Springs (HWS), Higher High Water (HHW), Lower…”

Section: Instantaneous Anomalies In Water Levels and Currents At Zigu...mentioning

confidence: 99%

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

Diouf,

Sakho,

Sow

et al. 2024

Preprint

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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.

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“…The hypothesis of the study is that Manoka Island, like other localities of Douala 6th subdivision and its mangrove forests, is under natural and anthropogenic influences [24,25,[33][34][35][36], which reduce the carbon storage potential and exacerbate the vulnerability of this ecosystem and populations to climate change [37][38][39]. To help provide a database on the subject, it is necessary to study the dynamics of land use on Manoka Island using remote sensing in order to better understand its vulnerability to climate change.…”

Section: Introductionmentioning

confidence: 99%

Land Cover and Land Use Changes between 1986 and 2018, and Preliminary Carbon Footprint Implications for Manoka Island (Littoral Region of Cameroon)

Tagne

Sonwa²,

Awono³

et al. 2022

Sustainability

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Land and resource use patterns in coastal areas play a key role in the resilience of ecosystems and populations to climate change. Knowing their spatiotemporal dynamics therefore constitutes a strategic tool to help decision-makers. Based on documentary research, geographic information system (GIS), image processing, and field work, this article maps land use on Manoka Island between 1986 and 2018 and identifies the drivers of change and avenues for intervention with a view to strengthening climate change mitigation. The results show a decrease of 4% in forest area on Manoka Island, representing an average of 112 ha of inland forest and 267 ha of mangrove converted between 1986 and 2018. This increases the degraded forest area by 268% (degraded mangrove and degraded inland forest) and exposes some camps to erosion and flooding. Reduction in forest area is mainly linked to the harvesting of fuelwood and the conversion of forests into farmland and residential areas. Settlements have increased in area from 15 ha in 1986 to 90.4 ha in 2018 to the detriment of natural spaces.

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Dynamique du maximum de turbidité dans le système estuarien du Wouri (Cameroun)

Cited by 4 publications

References 0 publications

Salinity Distribution in a Tropical River-Estuary Continuum through Numerical Modelling: Case of the Wouri-Nkam River Estuary, Cameroon

Salinity Distribution in a Tropical River-Estuary Continuum through Numerical Modelling: Case of the Wouri-Nkam River Estuary, Cameroon

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

Land Cover and Land Use Changes between 1986 and 2018, and Preliminary Carbon Footprint Implications for Manoka Island (Littoral Region of Cameroon)

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