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Abstract The Gulf of Guinea (GoG) is highly vulnerable to sea level rise, with projections indicating a significant increase in permanently inundated land by 2100, ranging from 1,458.1 to 4,331.7 km2. This study evaluates the severity of potential coastal inundation in the GoG by comparing sea level rise projections from eight reliable CMIP6 models with historical sea surface height (SSH) data from 1993 to 2015 and current onshore topography. Eight model simulations were selected based on their accuracy in reproducing sea level variability in the Tropical Atlantic and the GoG, and their consistency in reflecting the one-month connection lag between equatorial-driven waves and Kelvin Coastal Trapped Waves (CTWs) along the GoG, critical for predicting regional ocean dynamics. Our findings indicate that this connection lag will remain consistent over time. Under high-emission scenarios, up to 95% of coastal areas could be inundated, potentially displacing 2 million people posing a socio-economic shock, given the region’s low GDP and heavy reliance on fisheries. The loss of cultural heritage and livelihoods further compounds the challenges. These findings emphasize the urgent need for targeted adaptation strategies and robust early warning systems, in line with the UN’s Sustainable Development Goals (SDGs), particularly SDG 13 (Climate Action) and SDG 14 (Life Below Water). This study offers a precise and regionally relevant assessment of future risks, providing a foundation for informed policy interventions to mitigate the impacts of climate change and protect vulnerable communities in the GoG.

Abstract Sea level rise (SLR) poses a significant threat to coastal regions worldwide, particularly affecting over 60 million people living below 10 m above sea level along the African coast. This study analyzes the spatio-temporal trends of sea level anomaly (SLA) and its components (thermosteric, halosteric and ocean mass) in the Eastern Tropical Atlantic Ocean (ETAO) from 1993 to 2022. The SLA trend for the ETAO, derived from satellite altimetry, is 3.52 ± 0.47 mm/year, similar to the global average of 3.56 ± 0.67 mm/year. Of the three upwelling regions, the Gulf of Guinea (GoG) shows the highest regional trend of 3.42 ± 0.12 mm/year. Using the ARMORD3D dataset, a positive thermosteric sea level trend of 0.88 ± 0.04 mm/year is observed, particularly in the equatorial and southern Atlantic regions. The steric component drives the interannual SLA variability, while the ocean mass component dominates the long-term trends, as confirmed by the GRACE and GRACE-FO missions for 2002–2022. For those two decades, the total SLR from altimetry amounts to 3.80 ± 0.8 mm/year, whilst the steric component is reduced to only 0.19 ± 0.05 mm/year, leaving a residual increase in the ETAO of 3.69 ± 0.5 mm/year. The independent mass change from GRACE amounts to 2.78 ± 0.6 mm/year for this region, which just closes the sea level budget within present uncertainty levels. Spatial analysis of the steric components indicates a warming along the equatorial African coast including the GoG and a freshening near Angola. Strong correlations with regional climate factors, particularly the Tropical South Atlantic Index, highlight the influence of persistent climate modes. These findings underscore the urgent need for mitigation and adaptation strategies to SLR in the ETAO, especially for densely populated coastal communities.

The elastic thickness parameter was estimated using the mobile correlation technique between the observed isostatic disturbance and the gravity disturbance calculated through direct gravimetric modeling. We computed the vertical flexure value of the crust for a specific elastic thickness using a given topographic dataset. The gravity disturbance due to the topography was determined after the calculation. A grid of values for the elastic thickness parameter was generated. Then, a moving correlation was performed between the observed gravity data (representing actual surface data) and the calculated data from the forward modeling. The optimum elastic thickness of the particular point corresponded to the highest correlation coefficient. The methodology was tested on synthetic data and showed that the synthetic depth closely matched the original depth, including the elastic thickness value. To validate the results, the described procedure was applied to a real dataset from the Barreirinhas Basin, situated in the northeastern region of Brazil. The results show that the obtained crustal depth is highly correlated with the depth from known models. Additionally, we noted that the elastic thickness behaves as expected, decreasing from the continent towards the ocean. Based on the results, this method has the potential to be employed as a direct estimate of crustal depth and elastic thickness for any region.

Many hydrological applications employ conceptual-lumped rainfall-runoff models to support water resource management techniques. Because of their ability to exploit minimal data and provide enough credible information, they provide an edge in data-scarce domains. The purpose of this research is to evaluate the feasibility of using multiple rainfall-runoff hydrologic models Génie Rural à 4, 5, 6 paramètres Journalier (GR4J, GR5J, and GR6J) in the Upper Benue River (UBR) in Northern Cameroon. The models were calibrated using Michel's calibration algorithm implemented in airGR packages, while considering different objective functions (NSE, KGE, composite criterion). The objective here was to find the optimum objective function that takes into account the various components of the hydrographs in this watershed and to assess the impact of the chosen objective function on parameter optimization. The results reveal that the model performance as well as the optimized parameters of the different GR models vary according to the selected objective function. According to the study, adopting the composite criterion as an objective function during model calibration improves model accuracy. The model's performance reveals that two of the three models (GR5J and GR6J) reproduced the discharge well in the considered catchment, with NSE and KGE greater than 0.62 during the model validation. This highlights how these two GR models can be applied to various water management concerns in the UBR.

Abstract Coastal zones with dense populations, low elevations and/or inadequate adaptive capacity are on the frontline of unprecedented impacts from climate change. The Gulf of Guinea (GoG), stretching from Liberia to Gabon, is in particular vulnerable to coastal flooding caused by local and/or climate-induced sea level rise. In this region, interannual to decadal coastal sea level changes remain poorly understood, mainly due to a lack of tide gauge stations. Here we use nearly three decades (1993–2021) of satellite altimetry data to study the link between the Equatorial Atlantic and coastal GoG sea level variability. The rate of mean sea level rise increased from 3.47 to 3.89 ± 0.10 mm/yr from the Equatorial oceanic domain to the GoG coastal area, with an acceleration of 0.094 ± 0.050 mm/yr2. This corresponds to a mean sea level rise of about 8.9 cm over the entire altimetry period, 1993–2021. We focus on the (extreme) warm/cold events that occur in both the GoG during Atlantic Niños, and along the Angola-Namibia coast during Benguela Niños. Both events are driven by remote forcing via equatorial Kelvin waves and local forcing by local winds, freshwater fluxes and currents intensifications. Analysis of altimetry-based sea level, sea surface temperature anomalies, 20 °C isotherm based PIRATA moorings, and the Argo-based steric and thermometric sea level allows us to follow the coastal trapped waves (CTWs) along the GoG, and its link with major events observed along the strong Equatorial Atlantic warmings in 2010, 2012, 2019 and 2021. Both 2019 and 2021 warming have been identified as the warmest event ever reported in this region during the last 40 years. A lag of 1 month is observed between equatorial and West African coastal trapped wave propagation. This observation may help to better anticipate and manage the effects of extreme events on local ecosystems, fisheries, and socio-economic activities along the affected coastlines. In order to enable informed decision-making and guarantee the resilience of coastal communities in the face of climate change, it emphasises the significance of ongoing study in this field.

Water stress is an everyday issue in developing countries and especially in Foumban, a municipality located in the West Region of Cameroon between longitudes 10°40’-11°10’E and latitudes 05°30’-05°55’N. The failure of the water distribution system in the Municipality of Foumban (MoF) led the citizens as well as the municipal authorities to exploit groundwater. Unfortunately, an extensive hydrogeophysical field campaign, with incidental cost, is required because the groundwater potential is not priorly assessed. The main objective of this article is to demarcate groundwater potential zones of MoF. For this, six thematic layers contributing to groundwater occurrences are combined using analytical hierarchy process (AHP) on a GIS environment to produce a sound groundwater potential map. This map is classified into three zones: low potential for 39.06%, acceptable potential for 27.27% and high potential for 33.68% of the study area. This may help to increase the rate of productive wells (by focusing hydrogeophysical investigation on areas with high groundwater potential) using little financial resources.

The objective of the present study was to assess soil contamination by mercury and hydrocarbon products used in gold mining in the Kadey catchment area. The results obtained show that gold mining by the small mine is the cause of chemical contamination of the soil caused by hydrocarbon products with concentrations 800 times higher than the threshold value on certain points of the former mining sites. The use of mercury has led to an increase in its concentration to values that are still below the critical thresholds. It also appears from this work that organic matter plays a very important role in the retention of mercury on the soil surface. In the case of hydrocarbons are concerned, although high concentrations above are found exclusively at the surface, the rainfall contributes to their infiltration into the soil and to a horizontal redistribution of the contamination.

The aggregation of dipolar chains driven by thermal fluctuations in an external strong (electric or magnetic) field is investigated theoretically. We discover a new simple electrostatic mechanism that rationalizes the counter-intuitive lateral coalescence of dipolar chains. There, we first demonstrate that two bent dipolar chains can either attract or repel each other depending if they possess similar or opposite curvatures, respectively. Upon bending, dipolar chains become the siege of polarization-induced local charges that in turn lead to quadrupolar couplings. This striking feature is then exploited to understand our conducted Monte Carlo simulations at finite temperature where thermal fluctuations cause local curvatures in the formed dipolar chains. The related quadrupolar attractive mode with correlated chain-curvatures is clearly identified in the simulation snapshots. Our findings shed new light on a longstanding problem in soft matter and related areas. [ABSTRACT FROM AUTHOR]

The Atlas region in northwest Africa is characterized by the Quaternary volcanism and elevated topography with past complex tectonic mitigation between the African and European plates. Geodynamics of this atypical region has left indubitably imprints in crustal architectonics, mainly regarding the crustal thickness as well as the crustal density structure. The knowledge of crustal thickness variations is of a significant interest, since it provides a crucial constraint to geodynamic and geophysical modelling of this region. In this study, we use gravity, topographic, bathymetric and sediment data together with results of seismic surveys to image the Moho topography beneath the Atlas region. The Bouguer gravity anomalies used for a gravimetric Moho recovery are obtained from the free-air gravity anomalies after subtracting the gravitational contributions of topography, bathymetry and sediments. The regional gravimetric Moho inversion constrained on seismic data is carried out by applying a regularized inversion technique based on Gauss-Newton's formulation of improved Bott's method, while adopting Earth's spherical approximation. The numerical result reveals relatively significant Moho depth variations in the Moroccan Atlas, with minima of approximately 24 km along continental margins of the Mediterranean Sea and maxima exceeding 51 km beneath the Rif Cordillera. The Moho depth beneath the West African Craton varies from 32 km in its southern margin to 45 km beneath the Middle Atlas. The Tell Atlas is characterized by the shallow Moho depth of approximately 22 km and further deepening to 42 km towards the northern edge of the Aures Mountains. Our findings indicate a limited tectonic shortening of the High Atlas with the crustal thickness mostly within 36–42 km. Topographic discrepancies between the Rif Cordillera and the Atlas Mountains suggest that the hypothesis of isostatic compensation cannot be fully established. Keywords: Atlas, Gravity, Inversion, Moho, Seismic data

In the context of geological research, the delineation of structural lineaments beneath sedimentary basins is pivotal for understanding subsurface features. This study presents a comprehensive analysis of the Garoua sedimentary basin (GSB) utilizing the high-resolution SGG-UGM-2 model, which offers a refined depiction of the Earth's gravity field. The primary objective was to elucidate the structural lineaments underpinning the basin. To achieve this, a suite of advanced edge-detection filters was employed, including the analytical signal, the total horizontal gradient, a modified version of the tilt angle, the gradient amplitude's tilt angle, and the fast sigmoid function. Each method was meticulously applied to the gravity data covering the Garoua basin. The application of these techniques was critically evaluated, focusing on their effectiveness in enhancing the resolution and clarity of the detected structural features. The results indicated that the fast sigmoid function filter exhibited superior performance, delineating more distinct edges with a notable absence of fictitious anomalies. This filter demonstrated a unique capability in balancing the anomalies attributed to both shallow and deep sources, thereby providing a more precise localization of edge structures within the basin. The ensuing structural map, primarily oriented along the NW-SE and ENE-WSW axes, emerges as a crucial resource. It offers invaluable insights for further investigations into potential hydrocarbon accumulations and groundwater sources. By pinpointing favorable locations for the existence or emergence of these resources, this map enhances the efficiency of exploratory efforts in the Garoua basin. The findings underscore the efficacy of the fast sigmoid function filter in geological studies, particularly in the context of gravity data analysis. This approach not only refines the understanding of subsurface structures but also paves the way for more targeted and effective exploration strategies in sedimentary environments. [ABSTRACT FROM AUTHOR]

This paper focuses on assessing and development of water purification system for addressing water quality effects associated with sand mining in Toutsang locality, West-Cameroon. The study approach involved field investigations, laboratory analysis and design of waste water treatment system. Water samples were randomly collected from the study into well-labeled containers and conveyed to Unité de Recherche d’Analyse des Sols et Chimie de l’Environnement, Faculté d’Agronomie et des Sciences Agricoles (FASA) at the University of Dschang for analysis. Results from the physico-chemical analysis show elevated levels of total suspended solids (TSS), magnesium (Mg), turbidity and iron (Fe) in water samples collected downstream of the River close to the mining site, which exceeds the World Health Organization (WHO) standards. Based on the results of the physico-chemical analysis, a waste water treatment comprising of sedimentation tanks is proposed to treat waste water from the sand mining site. The designed water treatment system can be used to treat contaminated water from sand mining sites for domestic use. The proposed model tank needs to be implemented to restore Toutsang Water quality for indoor purpose and household use.