PHY
Maître de Conférences
Activité scientifique
Profil chercheur
Enseignant-chercheur à l’Université de Yaoundé I. Grade : Maître de Conférences.
Publications scientifiques
Alain Rodrigue Nzeuga, Justine Yandjimain, Paul Claude Ngoumou, Robert Nouayou, Philippe Njandjock Nouck
Research Square
Alain Rodrigue Nzeuga, Arnold Mony Kenfack Donfack, Robert Nouayou
Discover Geoscience
The KM-90 well located in the Rio Del Rey offshore basin faces major challenges in field maturation and hydrocarbon recovery optimization. To address this question, an integration of dynamic pressure data (Flowing Gradient Survey, FGS) and static pressure data (Static Gradient Survey, SGS) in a nodal analysis was further explored, in order to model the well’s behavior, identify optimization margins, and propose technical solutions adapted to the context of this basin. The collection of this data using slickline technology not only contributes to an accurate characterization of the hydraulic behavior of the wells under real conditions but also helps develop an integrated methodology to optimize gas injection parameters and improve the management of pressure losses, while evaluating the economic impact. These data are then integrated into a nodal model via the PROSPER software, which simulates the complex interactions between the reservoir, the production column, and the gas injection system. This modeling identifies critical pressure drops and allows for the optimization of gas injection parameters, in order to restore and maximize gas lift performance, which has allowed for an increase in the well’s production rate from 70.3583 STB/day to 2558.49 STB/day.
Alain Rodrigue Nzeuga, Baster Kenfack Fokem, Justine Yandjimain, Isaac Daama, Robert Nouayou
The Egyptian Journal of Remote Sensing and Space Science
The Cameroon Adamawa region has significant gold potential, as evidenced by several recent exploration projects and discoveries. Among the proven gold ore concentration areas, we can cite the Mbé site where the project is 80% owned by the British company Oriole Resources with gold grades ranging from 8.17 g/t to 131.1 g/t, and the Bibemi site where the same company has increased the estimated reserves of the region’s deposit by 23% with a potential of 2.3 g/t (Cameroun: De l’or Haute Teneur Découvert à Mbeh, n.d.). The PRECASEM project, funded by the World Bank between 2014 and 2019, identified more than 300 new mining sites in Cameroon, including several in the Adamawa region. Adamawa is a geologically diverse region, with metamorphic and granitic rocks suitable for gold mineralization. Lateritic soils and historical volcanic activity have favored the formation of deposits. Orogenic gold systems, such as those at Mbé, where geological studies were conducted, suggest significant resource potential. Previous studies in demineralization research were carried out on small-scale fields and here we propose to identify these indices at the scale of the Adamawa region by combining remote sensing, gravimetry and geological field study. Basically, based on the results of the mapped mineralization indices and the results of previous work, it seems that the Adamawa region is more than 70% covered by features associated with gold and other minerals, which would make this region a very large gold reservoir that could boost the mining sector’s contribution to Cameroon’s GDP with local benefits, making Adamawa a key region for Cameroon’s mining future, combining geological potential and growing interest from investors.
Alain Rodrigue Nzeuga, Justine Yandjimain, Paul Claude Ngoumou, Robert Nouayou, Françoise Martine Enyegue A Nyam
SSRN Electronic Journal
Alain Rodrigue Nzeuga, Justine Yandjimain, Paul Claude Ngoumou, Robert Nouayou, Françoise Martine Enyegue A Nyam
Advances in Water Resources
Benoit Diponbe, Robert Nouayou, Justine Yandjimain
Modeling Earth Systems and Environment
Zambou Tsopgni Yasmine, Franck Eitel Kemgang Ghomsi, Robert Nouayou, Luan Thanh Pham, Zakari Arétouyap, Janvier Domra Kana et 3 autre(s)
Journal of Geodynamics
Cyrille Armel Cheunteu Fantah, Alain Pierre Tokam Kamga, Marcelin Pemi Mouzong, Robert Nouayou, Sévérin Nguiya
Acta Geophysica
Zakari Arétouyap, William Assatsé Teikeu, Sandra Céleste Tchato, Franck Eitel Kemgang Ghomsi, J. K. Domra, Dieudonné Bisso et 2 autre(s)
International Journal of Energy and Water Resources
Alain Rodrigue Nzeuga, Franck Eitel Kemgang Ghomsi, Luan Thanh Pham, Ahmed M. Eldosouky, Zakari Arétouyap, Janvier Domra Kana et 6 autre(s)
Frontiers in Earth Science
The southwest part of Cameroon is composed of a range of geological structures and sedimentary basins, whose geological history dates from the Cretaceous, and their establishment would have originated from the opening of the South Atlantic. Among these structures, the most important is the Cameroon Volcanic Line, generally denoted CVL, followed by the southern part of the Central African Shear Zone (CASZ) called the Foumban Shear Zone (FSZ), the Ntem Complex, the Benue Trough, the northern margin of the Congo Craton, and many others. The major structures identified in this part are formed as a result of geodynamic activity between the Oligocene and the recent period, to which we can add the volcanism that exists along with the continental limit. The XGM201e_2159 model is used to highlight the geological structures of Southwestern Cameroon. First, we separated the regional and residual anomalies from Bouguer gravity data. Then, we used a combination of filters to enhance the signature of the residual anomalies in Southwest Cameroon. These filters identified various geological structures in the area. Finally, we applied the enhanced horizontal gradient amplitude (EHGA) and multi-scale horizontal derivative of the vertical derivative (MSHDVD) methods to reveal the geological contacts, allowing us to establish the corresponding structural map of the region. In addition, the results obtained in this study are the first to precisely define the circumferential demarcation of the continental and oceanic expansions of Mount Cameroon, while clearly illustrating the Bao, Bomana, Tiko, and Ekona faults that extend to the Bakassi Peninsula and the Douala outlet. Furthermore, they highlight the strike–slip faults in the summit vicinity. The structural map shows that most of the geological boundaries identified in the area are trending in the NE–SW, NNE–SSW, ENE–WSW, N–S, and NW–SE directions.
Zakari Arétouyap, Dieudonné Bisso, William Teikeu Assatsé, Janvier Domra Kana, Franck Eitel Kemgang Ghomsi, Robert Nouayou et 2 autre(s)
Environmental Earth Sciences
Ibrahim Njouenwet, Derbetini A. Vondou, Elisabeth Fita Dassou, Brian Ayugi, Robert Nouayou
Natural Hazards
Françoise Martine Enyegue A Nyam, Albert Eyiké Yomba, Anita Ngouokouo Tchikangoua, C.P. Bounoung, Robert Nouayou
Groundwater for Sustainable Development
Franck Eitel Kemgang Ghomsi, Nelson Ribeiro‐Filho, Raissa Moraes Baldez, Róbert Tenzer, Cristiano Mendel Martins, Chikondi Chisenga et 2 autre(s)
Journal of African Earth Sciences
Franck Eitel Kemgang Ghomsi, Sévérin Nguiya, Animesh Mandal, Françoise Enyegue A. Nyam, Róbert Tenzer, Alain Pierre Tokam Kamga et 1 autre(s)
Journal of African Earth Sciences
Franck Eitel Kemgang Ghomsi, Róbert Tenzer, Sévérin Nguiya, Animesh Mandal, Robert Nouayou
Geodesy and Geodynamics
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.
Loudi Yap, Robert Nouayou, Depesquidoux Tchaptchet Tchato, Joseph Kamguia, Apollinaire Bouba
Open Journal of Geology
The existence of mafic bodies at mid crustal level beneath the Pan-African Central Cameroon Shear Zone is still a matter of debate. To provide additional constrains on this issue, the crust of the west region of Cameroon has been investigated using gravity data. Analyses of these data show N40-50°E oriented iso-anomal contours in the Bafoussam area, interpreted as the N40-50°E branch of the Central Cameroon Shear Zone. In addition, spectral analysis and 2.5D gravity modeling reveal intrusions of mafic bodies at depth between 3.2 and 14.2 km under N40-50°E aligned volcanic centers, namely Mt Bambouto and Mt Mbapit. The above observations suggest a structurally controlled emplacement of the mafic bodies. In the light of the recent geophysical data, the interaction between the NE-ward channel flow operating at the bottom of the lithosphere or the asthenosphere upwelling and the Cameroon Shear Zone could better explain the magma upwelling in the upper crust. This result is the novelty of the present work.
Loudi Yap, Ludovic Houetchak Kandé, Robert Nouayou, Joseph Kamguia, Abdou Nasser Ngouh, Marie Brigitte Makuate
International Journal of Digital Earth
Digital Elevation Models (DEMs) contain topographic relief data that are vital for many geoscience applications. This study relies on the vertical accuracy of publicly available latest high-resolution (30 m) global DEMs over Cameroon. These models are (1) the ALOS World 3D-30 m (AW3D30), (2) the Shuttle Radar Topography Mission 1 Arc-Second C-Band Global DEM (SRTM 1) and (3) the Advanced Spaceborne Thermal Emission and Reflection Global DEM Version 2 (ASTER GDEM 2). After matching their coordinate systems and datums, the horizontal positional accuracy evaluation was carried out and it shows that geolocation errors significantly influence the vertical accuracy of global DEMs. After this, the three models are compared among them, in order to access random and systematic effects in the elevation data each of them contains. Further, heights from 555 GPS/leveling points distributed all over Cameroon are compared to each DEM, for their vertical accuracy determination. Traditional and robust statistical measures, normality test, outlier detection and removal were used to describe the vertical quality of the DEMs. The test of the normality rejected the hypothesis of normal distribution for all tested global DEMs. Overall vertical accuracies obtained for the three models after georeferencing and gross error removal in terms of Root Mean Square (RMS) and Normalized Median Absolute Deviation (NMAD) are: AW3D30 (13.06 m and 7.75 m), SRTM 1 (13.25 m and 7.41 m) and ASTER GDEM 2 (18.87 m and 13.30 m). Other accuracy measures (MED, 68.3% quantile, 95% quantile) supply some evidence of the good quality of AW3D30 over Cameroon. Further, the effect of land cover and slope on DEM vertical accuracy was also analyzed. All models have proved to be worse in the areas dominated by forests and shrubs areas. SRTM 1 and AW3D30 are more resilient to the effects of the scattering objects respectively in forests and cultivated areas. The dependency of DEMs accuracy on the terrain roughness is evident. In all slope intervals, AW3D30 is performing better than SRTM 1 and ASTER GDEM 2 over Cameroon. AW3D30 is more representative of the external topography over Cameroon in comparison with two others datasets and SRTM 1 can be a serious alternative to AW3D30 for a range of DEM applications in Cameroon.
Zakari Arétouyap, Njandjock Nouck Philippe, Robert Nouayou, William Teikeu Assatsé, Jamal Asfahani
Environmental Earth Sciences
Diponbe Benoit, Robert Nouayou, Kenfack Jean Vıctor, Momo Tonfack Christian
Journal of Geology & Geophysics
A study is conducted in South-West of Chad with the goal of underlining the different lineaments of the region, which are entirely or partially hidden by the sedimentary cover. Different gravity data processing techniques including horizontal gradient of vertical derivative coupled with upward continuation and Euler’s de-convolution are used. These methods revealed a number of lineaments describing gravity density discontinuities whose directions are N-S, NE-SW, ENE-WSW, and WNW-ESE at NNW-SSE. However, the predominant direction for major lineaments is WNW-ESE. The major lineaments associated to the faults are: F1, F2, F3, F6, F7, F8, F9, F10, F14, F21, F22, F23, F24 and F28. Euler’s solutions indicate depths up to 9.2 km for the anomaly sources. Such lineaments are very useful for groundwater and oil exploration, but also for risk assessment.
Zakari Arétouyap, Philippe Njandjock Nouck, Robert Nouayou
Renewable and Sustainable Energy Reviews
Zakari Arétouyap, Philippe Njandjock Nouck, Robert Nouayou, Franck Eithel Ghomsi Kemgang, Axel Dorian Piépi Toko, Jamal Asfahani
SpringerPlus
[This corrects the article DOI: 10.1186/s40064-016-2142-4.].
Zakari Arétouyap, Robert Nouayou, Njandjocknouck Philippe, Jamal Asfahani
Journal of Earth System Science
Janvier Domra Kana, Noël Djongyang, Danwé Raïdandi, Philippe Njandjock Nouck, Robert Nouayou, Tabod Charles Tabod et 1 autre(s)
Journal of African Earth Sciences
Zakari Arétouyap, Njandjock Nouck Philippe, Dieudonné Bisso, Robert Nouayou, Lengue Beatrice, Lepatio Tchieg Steve Alain
Journal of Applied Sciences
Marcelin Pemi Mouzong, Joseph Kamguia, Sévérin Nguiya, Robert Nouayou, Yves Shandini, Eliézer Manguelle-Dicoum
European Journal of Biological Research
The Garoua sedimentary basin is the eastward branch of the Benue Trough in north Cameroon and is characterized by its potential hydrocarbons resources. Statistical spectral analysis of the residual gravity field values obtained by bandpass filtering of Bouguer gravity anomalies was employed to determine the depth to the basement rocks of parts of Garoua Basin. The depth to basement in the area is found to be 4.4 km to 8.9 km. This represents the thickness of the sedimentary formation overlying the basement complex. This increases the possibility of hydrocarbon accumulation in the area. Horizontal gradient analysis enabled tracing deep faults that are mainly striking in the NW-SE direction. Interpretation of horizontal gradient of the gravity data indicated that the potential hydrocarbon field area is structurally controlled. Euler deconvolution method has been applied to the gravity data and provided information about both the depth and trends of the subsurface faults structures in the area.
Ludovic Houetchak Kandé, Joseph Kamguia, Jean Marie Tadjou, Robert Nouayou
International Journal of Geosciences
The South Adamawa trough represents a major structure associated to the tectonic activity in the Adamawa region. The Mbere and the Djerem troughs represent the eastern and the western parts of the South Adamawa trough respectively. The audio-magnetotelluric (AMT) method is used to study the Mbere trough and to bring out tectonic features that affect the basement of this region during the Cretaceous. From analysis and interpretation of AMT data, based on pseudo-section and geoelectric section, two geologic models are constructed across the trough at Belel and Nyambaka. Those models bring more information on the sediments thickness and the borders faults of the trough compared to previous studies. The results shows that the Mbere trough is dissymmetric, and bounded on its northern side by an intra-gneissic fault and on its southern side by two faults with at least one considered as a faulted contact between the granitic and gneissic rocks. The sediments filling of the trough are consist mainly of conglomerates on which lay sandstones. The thickness of these sediments is about 2060 m at Belel and decreases to about 1800 m at Nyambaka, with a low sandstones thickness, which does not exceed 360 m. The basement consists of granite in the South of the trough and gneiss in the North, with resistivity more than 10,000 Ω.m. The Moho is located between 25 and 35 km in the South Adamawa region.
Jean Jacques Nguimbous-Kouoh, Eric M. Takam Takougang, Robert Nouayou, Charles T. Tabod, Eliézer Manguelle-Dicoum
ISRN Geophysics
Five audiofrequency magnetotelluric AMT soundings were collected northwest-southeast along the Manyu river in the Mamfe sedimentary basin of southwestern Cameroon. The soundings were performed with frequencies in the range 3 to 2500 Hz and covered a distance of approximately 28 km. Sounding curves and geoelectric and geological sections were processed, and the results were compared with rocks' resistivity to characterize the lithostratigraphy of the eastern part of the basin. The results show above 1000 m depth, sedimentary layers with resistivities in the range of 1 to 100 Ohm-m, which decrease with depth. We identified three types of sedimentary rocks: laterite-clay mixture, shale, and sandstones. Various faults were also identified, illustrating the structural complexity of the Mamfe basin, along the Manyu River.
Akoumou Manga Ngando, Robert Nouayou, Tabod Charles Tabod, Eliézer Manguelle-Dicoum
Geofísica Internacional
La falla de Adamawa es una estructura tectónica relacionada con la línea volcánica de Camerún. Se han obtenido datos ATM a lo largo de una superficie de case 1,600 km² alrededor de la ciudad de Tibati. El conocimiento geológico del área es escaso; los últimos datos se recopilaron hace 50 años. Este artículo describe las etapas principales, seguidas de la determinación de la firma electromagnética de la falla. Los resultados muestran numerosas zonas anómalas atribuidas a la zona de Cizalla. Todo ello nos permiten inferir la estructura de la resistencia eléctrica y hacen posible tener conocimiento acerca de la falla Tibali. Estos resultados son preliminares a un estudio de la estructura de esta falla precámbrica. En este estudio se produjeron valores y variaciones importantes de la aparente resistencia. La falla de Tibali se caracteriza por su gran complejidad y estrechez.
M.L.C. Owona Angue, Sévérin Nguiya, Robert Nouayou, Alain Pierre Tokam Kamga, Eliézer Manguelle-Dicoum
South African Journal of Geology
Three different sets of geophysical data are used to investigate the structure of the transition zone between the north-western boundary of the Congo Craton (CC) and the Kribi-Campo sedimentary basin. These are shear wave velocity, gravity and magnetotelluric (MT) data, respectively. The combined use of these data helps to reduce the non-uniqueness of solutions inherent to forward models, leading to a better inference of the structure of the transition zone. The interpretation of shear wave velocity models enhanced the difference in composition of upper crustal layers against the similar composition (densities of ~3.0 g/cm 3 ) of the lower crust, with different thicknesses beneath both tectonic regions. The analysis of gravity maps obtained from the area shows the signature of the main geological units and particularly the north-south gradient correlating with the strike direction of the so-called Kribi-Campo fault (KCF). Using constraints from shear wave velocity models together with surface geology observations, a 2D1/2 gravity model was obtained along a profile crossing the CC margin and the Kribi-Campo sedimentary basin. The new model is consistent with the presence of a thick mafic layer (>10 km) at depth below 18 km beneath both geological units, and also with crustal thicknesses of 28 km and 45 km beneath the basin and CC, respectively. The model also suggests that KCF resulted from the intrusion of magmatic rocks during the continental collision, which were later metamorphosed into granulites. The resulting suture may be interpreted from the model as the thrusting of the Panafrican Mobile Belt rocks onto the CC. Similar conclusions are inferred from the MT model and the signature of the above mentioned presence of granulites is interpreted in this case as low resistive rocks emplaced into high resistive materials. This provides additional support for the gravity model.
Jean Marie Tadjou, Robert Nouayou, Joseph Kamguia, Houetchack Ludovic Kande, Eliézer Manguelle-Dicoum
A gravity-based geophysical study was performed across the southern part of Cameroon to investigate the important Precambrian boundary between the Archean Congo craton and the Pan-African metamorphic belt. The study includes analyses of results from a long section of profiles in which allochthonous Pan-African rocks have been juxtaposed against the craton. Interpretations of gravity data from these profiles, combined with 2-D spectral analysis permit deep structures to be identified and depths of major crustal discontinuities to be determine. The later allow the evaluation of the mean Moho depth in the region at around 47 km and determining variations in the crustal density across the tectonic boundary between the Congo craton and the Pan-African fold belt. 2D1/2 modeling provides images of deep structures in the region. These reveal that the crust of the Congo craton is relatively thick and consists predominantly of low-density rocks. In contrast, Pan-African belt rocks are mostly relatively dense. The images suggest that a fault zone juxtaposed the high-density Pan-African domain in the north against the low-density Archean rocks in the south, at nearly 20 km crustal depth. An explanation for the enhanced low densities is that part of the lower crust beneath the craton domain is subsiding. In this case, a probable source for the enhanced high-density rocks is Pan-African ocean margin units, as suggested by their location at the edge of the Pan-African continental block. Eine Gravimetriestudie wurde im den Sudteil Kameruns durchgefuhrt um die bedeutende prakambrische Grenze zwischen dem archaischen Kongokraton und dem Panafrikanischen Metamorphose-Gurtel zu untersuchen. Die Studie beinhaltet Analysen der Resultate mehrerer Langsschnitte, in denen allochthone Panafrikanische Gesteine an den Kraton grenzen. Die Interpretation der Gravimetriedaten kombiniert mit einer 2-D Sprektralanalyse erlaubt es, Tiefenstrukturen zu identifizieren and die Tiefe der bedeutendsten Diskontinuitaten zu bestimmen. Daraus ergibt sich eine Abschatzung der mittleren Moho-Tiefe von 47 km in dem Untersuchungsgebiet, und die Bestimmung der Variationen der Krustendichte entlang der tektonischen Grenze zwischen dem Kongokraton und dem Panafrikanischen Gurtel. Eine 2D1/2 Modellierung ergibt eine kartenmasige Darstellung der Tiefenstrukturen des Gebietes. Daraus ergibt sich, dass die Kruste des Kongokratons relativ dick ist und im wesentlichen aus Gesteinen niedriger Dichte bestehen, wahrend die Panafrikanischen Gesteine vorwiegend hohe Dichten aufweisen. Aus der Modellierung ist abzuleiten, dass eine Storung die Panafrikanischen Gesteine hoher Dichte im Norden gegen Archaische Gesteine niedriger Dichte im Suden in einer Tiefe von 20 km abgrenzt. Die auffallenden niedrigen Dichten werden dadurch erklart, dass Teile des Kratons samt der unteren Kruste absinken. Eine wahrscheinliche Quelle fur die Gesteine hoherer Dichte kann die Situation eines ehemaligen Panafrikanischen Ozeanrandes darstellen, wie auch durch die Lage am Rand des Panafrikanischen Kontinentblockes nahe legt.
Joseph Kamguia, Robert Nouayou, Charles T. Tabod, Jean Marie Tadjou, Eliézer Manguelle-Dicoum, H.L. Kande
Journal of African Earth Sciences
Joseph Kamguia, Charles T. Tabod, Robert Nouayou, Jean Marie Tadjou, Eliézer Manguelle-Dicoum, H.L. Kande
Abstract: This paper deals with the geoid determination in Cameroon by a gravimetric solution. A number of data fi les were compiled for this work, containing about 62,000 points on land and ocean areas and also including data derived from satellite altimetry. A hybrid global geopotential model (EGM-GGM) supplied the longer wavelength components of this geoid model, CGM05. This global model is obtained by adjusting the GRACE model GGM02C to degree and order 360 using the harmonic coeffi cients of the model EGM96 beyond the maximal degree 200 of GGM02C. The medium wavelength components were computed using the best gridded residual gravity anomalies, by integration in Stokes ’ formula. The digital terrain model GLOBE contributed to its short wavelength components. The residual terrain model (RTM) was applied to fi rst determine a quasi-geoid model. This intermediate surface was converted to the geoid using a grid of simple Bouguer gravity anomalies. The validation of CGM05 is based on comparisons to global and regional geoids. A GPS/levelling geometric geoid computed in a small part of the target area shows that the absolute accuracy of this local geoid model is 14 cm. After a four-parameter fi tting to the GPS/levelled reference surface, this absolute accuracy reduced to 11 cm.
Abdus Salam, Eliézer Manguelle-Dicoum, Robert Nouayou, Sévérin Nguiya
Audio-magnetotelluric (AMT) data has been used to study the eastern margin of the Mamfe sedimentary basin along two profiles. Both profiles run across the sedimentary-metamorphic transition zone in this part of the basin. A 1-D interpretation of these data has been carried out using frequency profiling, pseudosections and geoelectric sections. Studying the propagation of the electric field at each station also gives an initial qualitative understanding of the possible layering of the subsurface at the station. A dioritic basement intrusion into the sediments has been identified along one of these profiles and a granitic intrusion under the other. Faults have been identified along both profiles marking the transition from sedimentary to metamorphic rocks at the eastern edge of the basin. However, this transition is complex and not smooth. This complexity can probably be explained by the fact that regional lithospheric stretching must have been responsible for the formation of this basin resulting in faulting in the eastern margin, thus strengthening the link between this basin and the Benue Trough of Nigeria.
JM Tadjou, Eliézer Manguelle-Dicoum, CT Tabod, Robert Nouayou, Joseph Kamguia, NP Njandjock et 1 autre(s)
Journal of the Cameroon academy of sciences
Eliézer Manguelle-Dicoum, Robert Nouayou, A S Bokosah, T.E. Kwende-Mbanwi
Journal of African Earth Sciences
Cyrille Armel Cheunteu Fantah, Cyrille Adiang Mezoue, Marcelin Pemi Mouzong, Alain Pierre Tokam Kamga, Robert Nouayou, Sévérin Nguiya
Earth Planets and Space
Abstract The cartography of lineaments across a territory can be optimized using geophysical potential field data. In this study, land gravity and EMAG2 (Earth Magnetic Anomaly Grid) data were simultaneously used to identify and characterize the major lineaments that spread across Cameroon. The data were filtered using a multi-scale approach including horizontal and vertical gradient analyses. The Euler Deconvolution method was later applied to the filtered data to estimate the extension and depth of the identified lineaments. Results show that the main lineaments across Cameroon are laterally extended with a dominant N45°E orientation. Some of these lineaments correlated well with the geographical location of some known major tectonic structures found across the country. The depth of these lineaments varies between 1 and 35 km. Some of the identified faults are still active as their location correlated with the location of some recent earthquakes that occurred in Cameroon. This work, therefore, highlights some hidden tectonic features which knowledge generally precedes exploration for subsurface resources. Graphical Abstract
Ibrahim Njouenwet, Lucie Angennes Djiotang Tchotchou, Brian Ayugi, G. M. Guenang, Derbetini A. Vondou, Robert Nouayou
Atmosphere
The Sudano-Sahelian region of Cameroon is mainly drained by the Benue, Chari, and Logone rivers; which are very useful for water resources; especially for irrigation, hydropower generation, and navigation. Long-term changes in mean and extreme rainfall events in the region may be of crucial importance in understanding the impacts of climate change. Daily and monthly rainfall data from fifteen climate stations in the study area from 1980 to 2018 and measurements from the Expert Team on Climate Change Detection and Indices (ETCCDI) were estimated using the non-parametric innovative trend analysis (ITA) and the Sen slope estimator. The precipitation concentration index (PCI), the precipitation concentration degree (PCD), and the precipitation concentration period (PCP) were used to explore the spatiotemporal variations in the characteristics of rainfall concentrations. The results showed complex spatial patterns of the annual average PCI values across the Sudano-Sahelian region; which varied from values lower in the south to higher in the far north, which were the characteristic of seasonality and a strong seasonal precipitation distribution throughout the year; respectively. The PCD results revealed that the annual rainy days in a year decreased from the south to the far north. Additionally, the PCP results indicated a slightly later occurrence of precipitation. A significant trend toward more intense–extreme rainfall events was observed in most parts of the study area, but a significant trend toward more humid days was observed in the southeastern part. Trends in dry days significantly increased in the central and southwestern parts of the study area. This could mean that the prevalence of flood and drought risks are higher in the study area. Overall, the increase in annual rainfall could benefit the hydro-power sector, agricultural irrigation, the availability of potable water sources, and food security.
Ibrahim Njouenwet, Derbetini A. Vondou, Stephanie Vanessa Ngono Ashu, Robert Nouayou
Sustainability
Cotton yields in the Sudano-Sahelian region contribute to food security through their role in agricultural productivity. Daily precipitation data and cotton yield data were synthesized from nine agricultural regions obtained from the “Société de Développement du Coton (SODECOTON)”. The following seasonal rainfall indices—from Cameroon’s cotton zone—were mapped with geographic information systems for spatial analysis: wet season onset and retreat date, rainfall amount, number of rainy days, rainfall intensity (SDII), heavy-rainfall events (R95p), consecutive dry days (CDD), annual highest daily precipitation (Rx1day) and number of very heavy precipitation days (R20mm). Linear regressions were used as statistical tools for analysis. The strongest relationships were observed between cotton yields and the heavy-rainfall events, closely followed by seasonal rainfall amount. An increase in consecutive dry days (CDD) and heavy events, and a decreased seasonal rainfall amount, have a negative impact on cotton yield trends. Overall, the critical breakpoint analysis between cotton yields and all rainfall indices showed that the cotton yield was particularly negatively impacted before a 251 retreat date, 591 mm seasonal rainfall amount and 33 rainy days. By contrast, an onset date, rainfall intensity, heavy rainfall, CDD, Rx1day and R20mm of 127, 12.5 mm·day−1, 405 mm, 27 days, 67 mm and 22 days, respectively, were identified for an optimum cotton yield. These results can be used as information for agricultural activity and management, civil planning of economic activities and can also contribute to furthering our understanding of the management impacts on future food security.
Alain T. Tamoffo, Grigory Nikulin, Derbetini A. Vondou, Alessandro Dosio, Robert Nouayou, Minchao Wu et 1 autre(s)
Climate Dynamics
Ibrahim Njouenwet, Lucie A. Djiotang Tchotchou, Brian Ayugi, G. M. Guenang, Derbetini A. Vondou, Robert Nouayou
Research Square
Alain T. Tamoffo, Derbetini A. Vondou, Wilfried M. Pokam, Andreas Haensler, Zéphirin D. Yepdo, Thierry C. Fotso‐Nguemo et 2 autre(s)
Theoretical and Applied Climatology
Alain Rodrigue Nzeuga, Françoise Enyegueà Nyam, Robert Nouayou, J.D. Fairhead
Open Journal of Earthquake Research
The coastal and intracontinental sedimentary basins of Cameroon owe their origins to the opening of the South Atlantic. Among these sedimentary basins, we can mention those of Mamfe, Douala and Rio Del Rey, which are the subject of our current study. These were formed following geodynamic processes between the periods from the lower Cretaceous to the Neogene. These processes have significantly affected the basement of these basins leaving as consequences of multiple faults which would in their turn favor a rise of the magma towards the surface which then cooled to give birth to the volcanic rocks which exist there today. A study of the impact of the opening of the South Atlantic on the tectonics of these basins will be made from a geodynamic approach, relying in the first time on a qualitative and quantitative analysis of the anomaly map of the total magnetic intensity field reduced to the pole of each basin, then in a second time on the interpretation of the 2D geological models realized on a profile chosen on the anomaly map of the total magnetic intensity field reduced to the pole of each basin. At the end of this study, we will show that the opening of the South Atlantic has similarly impacted the structure of the three basins and the results of the spectral analysis show that the oceanic crust is thinner than the continental crust.
Alain T. Tamoffo, Wilfran Moufouma‐Okia, Alessandro Dosio, Rachel James, Wilfried M. Pokam, Derbetini A. Vondou et 11 autre(s)
Climate Dynamics
Alain T. Tamoffo, Wilfran Moufouma‐Okia, Alessandro Dosio, Rachel James, Wilfried M. Pokam, Derbetini A. Vondou et 11 autre(s)
Climate Dynamics
Apollinaire Bouba, Joseph Kamguia, Tabod Charles Tabod, Loudi Yap, Robert Nouayou, Kandé Houetchak Ludovic et 1 autre(s)
International Journal of Geosciences
In order to analyze and determine the geological structures of the Adamawa plateau, the terrestrial gravity data were combined to data computed from GGM02C gravity model. The dense gravity net obtained were further introduced into qualitative and quantitative interpretations. The resulting Bouguer anomaly map obtained from combined data shows NE-SW direction which nearly coincides with the main direction of the fractures affecting the basement in the region and indicates strong gradients marking the presence of discontinuities between heavy and negative gravity anomaly. In order to conduct the quantitative interpretation of the combined gravity data, three profiles were drawn on the residual Bouguer anomaly map and therefore were interpreted using spectral analysis method and 3D density inversion. The knowledge of the depth and density of the geological structures show an uplift of dense rocks under the granite-gneiss substratum. This dense material found in the ENE-WSW direction of the Adamawa Plateau is interpreted as basaltic intrusion probably resulting from tectonic processes. According to this study, the depths of 3.83 km and 9.62 km are the new values of depths obtained for futures investigations in the Adamawa plateau.
Zakari Arétouyap, Philippe Njandjock Nouck, Robert Nouayou, Franck Eithel Ghomsi Kemgang, Axel Dorian Piépi Toko, Jamal Asfahani
SpringerPlus
OBJECTIVE: Many parameters in environmental, scientific and human sciences investigations need to be interpolated. Geostatistics, with its structural analysis step, is widely used for this purpose. This precious step that evaluates data correlation and dependency is performed thanks to semivariogram. However, an incorrect choice of a semivariogram model can skew all the prediction results. The main objectives of this paper are (1) to simply illustrate the influence of the choice of an inappropriate semivariogram model and (2) to show how a best-fitted model can be selected. This may lessen the adverse effect of the semivariogram model selection on an interpolation survey using kriging technique. METHODS: The influence of the semivariogram model selection is highlighted and illustrated by thematic maps drawn using four different models (Gaussian, magnetic, spherical and exponential). Then, a guideline to select the most suitable model, using mean error (ME), mean square error (MSE), root mean square error (RMSE), average standard error (ASE), and root mean square standardized error (RMSSE), is proposed. RESULTS: The choice of a semivariogram model seriously influences the results of a kriging survey at both endpoints and amplitude of the range of the estimated values. However, the direction of variation of the interpolated values is independent of the semivariogram model: different semivariogram models (with the same characteristics) produce different thematic maps but, the areas of minimum and maximum values remain unchanged. Yet, the suitable model can be selected by means of ME, MSE, RMSE, ASE and RMSSE. CONCLUSION: The present article illustrates how the use of an inappropriate semivariogram model can seriously distort the results of an evaluation, assessment or prediction survey. To avoid such an inconveniency, a methodical approach based on the computation and analysis of ME, RMSE, ASE, RMSSE and MSE is proposed.
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