Multi-criteria evaluation of suitable sites for termite mounds construction in a tropical lowland

© 2019 Elsevier B.V. Termite mounds influence ecosystem heterogeneity and contribute to the stabilization of the system under global change. A number of environmental factors influence the distribution, height, diameter and designs of termite mounds but these factors are not only poorly understood, they cannot be extrapolated for everywhere. In this study, we employed a ground based survey and Geographical Information System (GIS) technique to map 156 km 2 study area in Keffi, Nigeria. The aims were to (1) estimate the density and area covered by termite mounds, (2) sample and identify species types and how they are distributed, and (3) use five environmental factors (elevation, geology, surface water drainage, land use/land cover and static water level) to model suitable sites for mounds construction. A total of 361 mounds were mapped representing a density of about 0.8 mounds ha −1 and covering only about 0.31% of the studied area. Next, the effect of the five chosen environmental factors on the geographic distribution, life status, height and diameter of mounds and species diversity were analysed and their relationships plotted in pairwise comparison matrices using the Saaty's Analytical Hierarchy Process. Normalized rates for classes in each factor and corresponding weights were computed and aggregated using the Weighted Linear Combination method. The result depicted that moderate to low elevation (270–330 m amsl), rock cover types that are more susceptible to weathering (schist), cultivated areas and shallow water table zones are most favourable for termites to build mounds. The result obtained in this study shows a promising correlation between the environmental factors and termite mounds distribution. The proposed model can easily be replicated in a different but similar multi-land use and rock cover types

Aquifer potential assessment in termites manifested locales using geo-electrical and surface hydraulic measurement parameters

In some parts of tropical Africa, termite mound locations are traditionally used to site groundwater structures mainly in the form of hand-dug wells with high success rates. However, the scientific rationale behind the use of mounds as prospective sites for locating groundwater structures has not been thoroughly investigated. In this paper, locations and structural features of termite mounds were mapped with the aim of determining the aquifer potential beneath termite mounds and comparing the same with adjacent areas, 10 m away. Soil and species sampling, field surveys and laboratory analyses to obtain data on physical, hydraulic and geo-electrical parameters from termite mounds and adjacent control areas followed. The physical and hydraulic measurements demonstrated relatively higher infiltration rates and lower soil water content on mound soils compared with the surrounding areas. To assess the aquifer potential, vertical electrical soundings were conducted on 28 termite mounds sites and adjacent control areas. Three (3) important parameters were assessed to compute potential weights for each Vertical Electrical Sounding (VES) point: Depth to bedrock, aquifer layer resistivity and fresh/fractured bedrock resistivity. These weights were then compared between those of termite mound sites and those from control areas. The result revealed that about 43% of mound sites have greater aquifer potential compared to the surrounding areas, whereas 28.5% of mounds have equal and lower potentials compared with the surrounding areas. The study concludes that termite mounds locations are suitable spots for groundwater prospecting owing to the deeper regolith layer beneath them which suggests that termites either have the ability to locate places with a deeper weathering horizon or are themselves agents of biological weathering. Further studies to check how representative our study area is of other areas with similar termite activities are recommended

Geophysical and Geotechnical Investigations of Failed Sections of Road Pavements in Parts of Northcentral Nigeria

Communication in Physical Sciences, 2023, 9(3):256-268 Authors: Ernest Orji Akudo*, Kizito Ojochenemi Musa, Fabian Apeh Akpah, Jamilu Bala Ahmed II, Simeon Idowu, Mary Shaibu Received: 12 May 2023/Accepted 28 June 2023/ Due to the incessant failure of roads in Nigeria, geophysical and geotechnical studies were conducted along Crusher-Felele Road and Natako-Felele Road in Lokoja, Northcentral Nigeria to unravel the lithology, deformational features, underlying geology, and ultimately the causes of such failures. The geophysical methods involved electrical resistivity, while the geotechnical methods include Grain size analysis, Liquid limit (LL), Plastic limit (PL), Plasticity index (PI), Linear shrinkage (LS), Compaction, and California bearing ratio (CBR) tests respectively. From the 3geoelectric parameters retrieved by interpreting the VES soundings quantitatively, 3 to 4 geoelectric layers exist (topsoil/unweathered layered, weathered layer, partially weathered layer, and fresh basement layer) accordingly. The second layer possesses a low resistivity range (1.2-88.7 Ωm), revealing weak and saturated zones capable of jeopardizing the integrity and stability of the road pavement. The grain size analysis results show that the percentage of soils passing sieves No. 10, 40, and 200 falls within the range of 55-98.3%, 21-50.6%, and 2.0-8.2% respectively. The range of the result for the LL (21.1-38.6%,), PL (6-23.1%), PI (0.0-17.1%), LS (5.0-9.3%), Optimum moisture content (11-17%), Maximum dry density (1835-1980 kg/m3), unsoaked CBR (27-62%) and soaked CBR (15-35%) reveals the properties of the soils. Based on AASHTO classification, the soils are grouped as A-2-4, A-1-b, and A-2-6 representing silty sand, or silty gravelly, and clayey sand respectively. The soils are fairly good as pavement subgrade but poor as sub-base materials

Facies, textural and geochemical evaluation of the post-Santonian sandstones in the Bida basin, Nigeria: Implications for control on hydrocarbon sandstone reservoir characteristics and paleoenvironments

Using a combination of field observations, textural analysis, scanning electron microscopy (SEM), mineralogical X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF), and thin-section analysis, the hydrocarbon and paleoenvironmental characteristics of the Cretaceous sandstones of the southern Bida Basin, Nigeria, were evaluated. SEM data were used to display the mineral morphology, degree of cementation and presence of clay minerals on the grain surfaces and their pores on both sandstones of the Patti and Lokoja formations. The lithofacies analyses revealed three distinct facies associations. The XRD data showed that for the Lokoja and Patti sandstone reservoirs contained quartz from 49 to 67% and 43–68%, respectively. The XRF data also showed that both formations' sandstone reservoirs have a high percentage of silicon and low aluminum content. The grain size study showed that the Lokoja sandstone reservoirs include medium-coarse sandstone (−0.63 to 1.30 ф) that are poorly-moderately sorted (0.72–1.82 ф). In contrast, the Patti Formation is primarily made up of fine-medium sandstones at investigated outcrops, which typically display reasonably good to poor sorting (0.70–2.53 ф). The skewness of the sandstone reservoirs ranged from fine to coarse, and their kurtosis ranged from very platykurtic to leptokurtic. The research area's predominant depositional environments include shoreface/foreshore, estuary mudflat, and estuarine delta with fluvial interference, according to an analysis that combined sedimentary facies and textural data. This demonstrates that the sandstones from the two units have moderate quality prospective hydrocarbon reservoirs based on their physical and chemical characteristics