Rainfall Variability along the Southern Flank of the Bambouto Mountain(West-Cameroon)

This paper presents the rainfall variability along the southern flank of the Bambouto mountain. Data were collected from rain gauges, while spatial variability was estimated through daily recorded data. Monthly and annual data were used to draw isohyetes via the triangular method, with linear interpolations between observation points. Results show that rainfall is highly variable along the slope. Daily rainfall amounts range from 0.1 mm to 120 mm. Mean yearly rainfall is 1918.1 mm. Rainfall amount does not have a linear relationship with altitude. Dschang is characterised by abnormally high rainfall. Following a North-South direction, rainfall decreases from Dschang to a Melang-Loung-Djuttitsa axis. From this axis, the gradient reverses as rainfall increases rapidly towards the Mélétan mountain. The existence of the relatively dry zone within the hillside seems to be due to the influence of two air masses. The first is cold and very wet which moves from the Mamfe basin to the summit zone where it starts to warm up as it flows towards Melang and Loung where temperature increases. The second comes from the south to south-east monsoon which is also impoverished during the ascension to higher altitudes. It is also likely that a third air mass from the dry harmattan is involved depending on the position of the ITCZ

Geotechnical Suitability of Soils in Road Construction for Sustainable Development in Tropical Africa: Case of Lateritic Graveled Soils of Bandjoun (West, Cameroon)

The environmental impact of the exploitation of geomaterials and their relatively high cost, coupled with the increasingly low financial capital in developing countries, are pushing road actors to turn to inexpensive local ecological materials. The present study is conducted on lateritic graveled soils of Bandjoun (LGSB) in the West Cameroon Region. The aim is to determine whether lateritic gravel soils, particularly those in Bandjoun, can be an ecological and economical alternative to rock aggregates in road construction, considering their geotechnical parameters and environmental impact. These soils were described in the field and were also subjected to complete geotechnical identification in the laboratory. The LGSB presents Californian bearing ratio indices ranging from 26% to 83.3%, a plasticity index of 10.11%, a fines content of 12.05%, an average methylene blue value of 4.25, a water content at the Proctor optimum of 27.6% and a dry density of 1.75 g/cm3. They are silty or clayey gravels and sands of subgroup A-2-7 according to the Highway Research Board classification; sandy and gravelly soils with fines of class B according to the classification of the Road Construction Guide; and silty gravels according to the classification of the Central Laboratory of Bridges and Highways. These soils can be used naturally in pavement layers, in particular in subgrade for all traffic classes and in subbase for low traffic. The tonnage of these soils has been estimated at 18,389 t. The global warming index shows that the use of these soils (18,389 t) in road construction can reduce 31,629–62,706 kg of carbon emissions. The use of lateritic soils in road construction is a very interesting alternative to reduce the environmental impacts associated with the manufacture of rock aggregates. So, lateritic soils should be used instead of rock aggregates for cleaner, more environmentally friendly road construction. The present work presented a specific evaluation of the geotechnical properties and ecological impact of lateritic graveled soils for road construction, as well as their potential for ecological and economic utilization

Dynamics of the transport of total suspended sediments in the Mefou watershed at Nkolbisson-Yaounde

This study carried out in the Mefou watershed aimed to assess the quantity of suspended solids in suspension. For this study, a water level gauge was installed at the main station at Etoud, four discharge measurements representing the seasons were carried out and water samples were collected. The maximum liquid discharge to the Lake Mefou was 3.92 m3/s observed during the long rainy season, while the minimum observed during the long dry season was 0.58 m3/s. Meanwhile, the maximum solid discharge to the Lake Mefou observed during the short rainy season was 598.8 mg/s and the minimum of 14.85 mg/s was observed in June during the short dry season. It is then evident that the amount of suspended sediments in the river is not proportional to the flow rate. The mobilization of solid particles in the watershed resulted in an annual total flux of 5.74 T/year into the lake reservoir. This result is not yet alarming for the reservoir lifespan but testify to the permanent activity of erosion in this environment caused by the combination of various natural and anthropogenic processes such as climate change and land use activities. HIGHLIGHTS The Mefou watershed is subject to erosion phenomena.; Liquid and solid flows change proportionally to precipitation.; Suspended matter concentrations are integrated into liquid flow rates to obtain solid discharges.; The temporal data which are the liquid flow and the solid flow are used to estimate the specific degradation.; The soil degradation process is not yet critical because it is a peri-urban environment.

Contribution des sondages géoélectriques et des puits pédologiques à l'estimation du tonnage des graviers latéritiques du flanc nord du Mont Bangou : implications pour la construction de routes.

peer reviewedThe increasing demands on lateritic gravels in road construction presently make it necessary to quantify the available resources that can be used in road construction. This study aims to estimate the tonnage and to valorize the lateritic gravels of the north flank of Mount Bangou (west Cameroon) in road construction. Interpretation of 48 vertical electrical soundings coupled with 20 pedological wells from five lateritic gravel sites was carried out to determine the thickness of the lateritic gravel level. The thickness of the lateritic gravel level obtained from the geoelectrical soundings is the greatest (8.88–12.45 m) compared to that obtained from the pedological wells (1.23–1.98 m), and thus shows the inadequacy of the pedological wells for the determination of the thickness of the lateritic gravels. Thus, the electrical resistivity method is appropriate to estimate the thickness of the lateritic gravel level. The lateritic gravels studied are characterized by the electrical resistivity curves of type K, HK, Q, QH, KQ, HKH, H, and KH. The medium-thick (8–36 m) and thick (13–44 m) zones are areas of high potential lateritic gravels. The proven reserves of lateritic gravels at the Chenye, Sekakouo, Bamendjou 1, Bamendjou 2, and Bangam sites are, respectively, 3,479,003 t, 1,389,522 t, 5,002,505 t, 839,455 t, and 2,663,105 t and can build, respectively, 53,298 m; 226,167 m; 131,574 m; 778,314 m and 401,068 m of road, either as a subgrade layer or sub-base layer.13. Climate actio

Évaluation des matériaux gravillonnés latéritiques pour les chaussées routières au Cameroun

peer reviewedEarly surface and structural deterioration of new pavements are becoming increasingly perceptible in Cameroon. This raises serious concerns regarding the nature, spatiotemporal evolution, and quality of materials used. Therefore, this study uses geotechnical identification, X-ray diffractometry, and statistical methods to optimize the durability of lateritic gravelled material (LGM) pavements. The CBR values within the study sites are dispersed and present low variability (coefficient of variation-CV 35%). Three groups of LGM were distinguished at the Bamileke Plateau: firstly, LGM at the BAN site were characterized by CBR (31%). Secondly, LGM of Bamendjou 1 and Bamendjou 2 sites, characterized by CBR varying between 25 and 27%, CI between 1.3 and 1.5, gravel content among 62.7 to 64.7%, and MDD between 1.76 and 1.82 g/cm3. Thirdly the Sekakouo and Chenye sites LGM are dominated by fines with C80µm between 38 and 44%. Swelling clay minerals are absent in these materials. It results that, these materials are suitable for use as a subgrade layer for any type of traffic, and as a sub-base for low-volume traffic T1 to T3, except those at the Sekakouo and Chenye sites. Prospecting of LGM deposits should be directed towards those with high proportions of Gm, gravel content, MDD, CI, SG, and low proportions of Pm, C80µm, C400µm, Pp, ɛs and C2mm.12. Responsible consumption and productio

Rainfall Variability along the Southern Flank of the Bambouto Mountain (West-Cameroon)

This paper presents the rainfall variability along the southern flank of the Bambouto mountain. Data were collected from rain gauges, while spatial variability was estimated through daily recorded data. Monthly and annual data were used to draw isohyetes via the triangular method, with linear interpolations between observation points. Results show that rainfall is highly variable along the slope. Daily rainfall amounts range from 0.1 mm to 120 mm. Mean yearly rainfall is 1918.1 mm. Rainfall amount doesnot have a linear relationship with altitude. Dschang is characterised by abnormally high rainfall. Following a North-South direction, rainfall decreases from Dschang to a Melang-Loung-Djuttitsa axis. From this axis, the gradient reverses as rainfall increases rapidly towards the Mélétan mountain. The existence of the relatively dry zone within the hillside seems to be due to the influence of two air masses. The first is cold and very wet which moves from the Mamfe basin to the summit zone whereit starts to warm up as it flows towards Melang and Loung where temperature increases. The second comes from the south to south-east monsoon which is also impoverished during the ascension to higher altitudes. It is also likely that a third air mass from the dry harmattan is involved depending on the position of the ITCZ.Key words: rainfall, spatial variability, gradient, slope, mountai

Hydrogeochemistry of Surface and Ground Water in Alatening Village, Northwest Region, Cameroon

The purpose of this study was to evaluate petrography and the quality of water for drinking purposes in Alatening, Northwest Cameroon, with respect to the World Health Organization (WHO) standards. The indigenes of the study area, as well as other dwellers in rural areas, consume water from these sources whose quality is unknown; thus, it can lead to contamination and waterborne diseases. Three springs and two streams of Alatening village were investigated in early December 2017 and late July 2018 for organoleptic, physicochemical, and bacteriological parameters using standard methods. The petrographic studies revealed trachyte and benmoreite, and weathering of minerals from these rocks into the soil leads to the water-rock interaction, thus water hydrogeochemistry. All the water samples were clean except that of Alabong which had slight odour due to leaf fall. pH showed acidic water with the springs of Ngog and Alabong falling below the WHO limit in the dry season. Electrical conductivity and total dissolved solids (TDS) were low implying low mineralised water which can also lead to shortage of important minerals in humans. All the essential ions were found within the WHO guideline values without any significant change in concentrations between seasons (p>0.05). The water facies were such as Mg-Ca, Cl-Ca, and HCO3-CO3, suggesting an influence of rock silicate weathering and anthropogenic influence. Aluminium and iron contents were above the WHO limit in both seasons due to their abundance in the soils which could be a risk factor for the local population. Faecal coliforms as well as specific bacteria such as Enterobacter, Escherichia coli, Streptococcus, Salmonella, and Shigella were found in all the water samples, attributable to poor hygiene. Health data in the locality indicated the prevalence of typhoid, dysentery, and amoebiasis with a total of 2702 cases recorded between 2016 and 2017, therefore requiring treatment before consumption