Open Access Original Research Article

Evaluating the Earth Subsurface for Civil Engineering Site Characterization in Agege, Southwest Nigeria Using Integrated Geoelectrical and Multichannel Analysis of Surface Wave (MASW)

O. J. Airen, K. K. Oboshenure

Journal of Geography, Environment and Earth Science International, Page 1-11
DOI: 10.9734/jgeesi/2021/v25i230268

A geophysical investigation involving 1D Vertical Electrical Sounding (VES), 2D Electrical Resistivity Imaging (2D ERI) and Multichannel Analysis of Surface Wave (MASW) has been carried out at Agege, Lagos, Nigeria with a view to delineating the subsurface stratigraphy and locate some competent strata/stratum for founding civil engineering structures. Six (6) 200 m long traverses were established within the study area. Along these traverses, 2D ERI were carried out adopting Wenner electrode configuration. Vertical Electrical Sounding (VES) adopting Schlumberger electrode array were carried out at selected points along profiles 1, 2 and 3 to determine the lithological sequence at depth. MASW data also were acquired along traverses 1, 2 and 3. The data were processed and the result yielded interpretable 2D resistivity structure and geoelectrical parameters (layer resistivity, thicknesses and depth) from the VES. The interpreted VES results were used to generate geoelectric section while the MASW resulted in 2D velocity sections. Three subsoils including topsoil, clay and clayey sand/sand were delineated beneath the study area. The resistivity and thickness range of the layers are; topsoil (34.0-54.6 ohm-m, 0.9 – 1.7 m), clay (10.3 – 17.7 ohm-m, 8.9 – 12.3 m) and clayey sand/sand (48.9 – 323 ohm-m) while the S-wave velocity range for the subsoil falls between 40 – 500 m/sec.

Open Access Original Research Article

Assessment of Vulnerability of Croplands to Climate Variability in Federal Capital Territory (FCT) Abuja, Nigeria

Dada Ibilewa, Mustapha Aliyu, Samaila K. Ishaya, Joshua I. Magaji

Journal of Geography, Environment and Earth Science International, Page 12-39
DOI: 10.9734/jgeesi/2021/v25i230269

Despite the wide coverage of study on vulnerability in the Federal Capital Territory (FCT) of Nigeria over the years, it was observed that no emphasis has been placed on assessment of vulnerability of croplands to climate variability using the integrated vulnerability assessment and Geo-Informatics technique. This was achieved by determining the climate variability pattern in FCT from 1981 to 2017, determining the exposure index and the degree of sensitivity of croplands to climate variability, assessing the adaptive capacity of farmers to climate variability, evaluating the vulnerability of croplands to climate variability and developing vulnerability maps of croplands using the information produced. Yam, beans and maize were used as referenced crops in this study. Indicators were generated and analyzed on the three components of vulnerability: exposure, sensitivity and adaptive capacity. The study used the mixed research design. The Analytical Hierarchy Process was used to assign weight to the indicators. The weights were used to generate the exposure, sensitivity and adaptive capacity indices which were used to generate the vulnerability index map. Aggregate vulnerability index (AVI) was finally determined from the weighted sum of all indicators and used to produce the vulnerability map of the six Area Councils. The study shows that Gwagwalada Area Council has the highest vulnerability (0.2323) and Abaji Area Council has the lowest (0.005). Kwali and AMAC Area Councils were highly vulnerable to climate variability (Kwali 0.1562, AMAC 0.1565). Kuje Area Council has low vulnerability (0.0273) to climate variability. Bwari Area Council showed moderate vulnerability (0.0982). The implication of the results is that the three crops (maize, beans and yam) will produce moderately at moderate vulnerability while their production will be marginal and optimal at very high and very low vulnerabilities respectively. Crop production will be optimum in Abaji, marginal in Gwagwalada and moderate in Bwari. The study also revealed that vulnerability assessment is essential in determining the varying degrees of vulnerability in different localities. It also provides information that can help researchers, policy makers, private and public institutions in planning location-based adaptation strategies and prioritizing allocating limited resources in FCT. Agriculture should be heavily subsidized in terms of providing irrigation infrastructure to farmers to reduce over-reliance on rain fed agriculture. Installation of early weather warning system manned with expertise should be made available in all the Area Councils to provide timely and accurate climatic information to farmers.

Open Access Original Research Article

Engineering Geophysical Investigation of Road Failure in a Basement Complex Terrain, Southwestern Nigeria

Ismaila Abiodun Akinlabi, Christianah Oluwakemi Adegboyega

Journal of Geography, Environment and Earth Science International, Page 40-51
DOI: 10.9734/jgeesi/2021/v25i230270

Geoelectrical and geotechnical investigations were conducted to determine factors responsible for pavement failure in some segments of Adebayo Alao-Akala road in Ibadan, southwestern Nigeria. The geoelectrical investigation employed Schlumberger vertical electrical sounding conducted at fifteen stations occupied along two failed segments and one stable segment of the road, using station spacing of 25 m and maximum electrode spread of 100 m. 2D electrical resistivity survey was also conducted using the dipole-dipole electrode array with electrode spacing, a, of 1 m and expansion factor, n varied from 1 to 5 m. The VES data were interpreted quantitatively by partial curve matching and computer iteration technique and geoelectric sections were generated while 2D resistivity structures of the subsurface were produced from the inverted 2D resistivity data. The geotechnical investigation involved Grain size distribution, Atterberg limits, Compaction and California Bearing Ratio tests conducted on subsoils collected beneath the segment. The failed segments are underlain by low-resistivity clayey subgrade of resistivity mostly less than 100Ωm while the stable segment overlies sandy clay/clayey sand mixture of relatively higher resistivity, ranging from 200Ωm to 530Ωm. The subsoils of the failed segments comprise high-plasticity sandy clay and sandy gravelly clay while those of the stable segment are medium plasticity sandy clayey gravel. The values of maximum dry density are 1.46 Mg/m3-1.73 Mg/m3, 1.71 Mg/m3-1.86 Mg/m3 and 1.75 Mg/m3-1.82 Mg/m3 respectively, with corresponding optimum moisture content of 7%-8%, 11%-20% and 10%-17% and California bearing ratio under soaked condition for 48 hours of 7%-8%, 17%-20% and 11%-17% respectively. The failure of the road pavement is attributable to the clayey nature of the subgrade, and poor drainage. The stable segment is underlain by excellent-to-good subgrade materials. Ingress of surface water into the clayey subgrade occasioned by poor drainage of run-off resulted in deformation of the road pavement in response to vehicular load.

Open Access Original Research Article

Mid-afternoon Outdoor Biometeorological Conditions in a Hot-humid Climate of Minna in Nigeria, West Africa during the Year 2012

Christian A. Njoku, Ikenna Orisakwe, Vincent N. Ojeh

Journal of Geography, Environment and Earth Science International, Page 52-62
DOI: 10.9734/jgeesi/2021/v25i230271

The human biometeorological conditions at mid-afternoon during 12 months of 2012 in the city of Minna North-Central Nigeria have been evaluated based on energy budget indices (UTCI and PET) using climate parameters -air temperature, relative humidity, wind speed and solar radiation) observed at 15:00LST as input into the Rayman model. Air temperature demonstrated strongest significant correlation coefficient (r) with UTCI and PET (r= 0.91, r= 0.93) (P<0.0001) while windspeed show weakest association with them(r=-0.10, r=-0.20) (P<0.03, P<0.001) respectively. March and August were characterized by peak and slightest monthly thermal stress conditions according to both indices. The correlation coefficient between both indices was significantly (P<0.0001) very strong (r=0.98) and more noticeable for equivalent temperatures in strong stress thresholds (UTCI>=32°C, PET>=35°C), which shows that both indices can be used indifferently in warm climates. However, during May to October, UTCI better expressed warm conditions than PET mainly due to the difference in the definition of reference environment for both indices; this study is relevant to the urban sightseeing industry as tourists would most likely opt for a period of lesser thermal discomfort.

Open Access Original Research Article

Institutional Dynamics of Municipal Solid Waste Management in the Bamenda Metropolis

Victor Konfor Ntoban, Mbanga Lawrence Akei, Clarkson Mvo Wanie

Journal of Geography, Environment and Earth Science International, Page 63-78
DOI: 10.9734/jgeesi/2021/v25i230272

Rapid and uncontrolled urbanization in several parts of sub-Saharan Africa (SSA), has introduced a plethora of urban development challenges. This has left city governments ‘standing in their sleep’, as they strive to deal such issues. A classic example is solid waste management – with waste considered to be principally an urban problem. While the issue of waste has been belaboured in the literature, there is a dearth in geographical literature on the institutional dynamics of solid waste management. Viewed as structures and processes, institutions demonstrate potentials to determine the intentions and actions of urban waste managers and urban dwellers, within the waste management spectrum. Taking the case of Bamenda – a primate city par excellence – this paper explores the dynamics of institutions and their implications for solid waste management. Specifically, it explores the waste management institutional transition and its bearing on current and potentially, future waste management practices. Household surveys, complemented by expert interviews provided data for the study. Through narratives and descriptive statistics, we observed that despite the litany of institutions involved in solid waste management and their related institutional frameworks, their effectiveness remains questionable. This rests, in part, on the inadequacy in personnel, and the lack of law enforcement in the courts and city judiciary systems. The ineffectiveness of these instruments in the Bamenda Municipality is as a result of weak legal institutional setup, the absence of courts and a city judiciary system to handle environmental issues (solid waste), irregular or poorly enforced laws, inaccessible neighbourhood, and organizational lapses. Furthermore, the socio-political climate, characterised by insecurity, mars the effective implementation of waste management approaches. This paper argues that the institutional change process in waste management should strive towards the introduction of economic incentives that can motivate urban dwellers to fully engage in the process. Further empirical evidence on the right business-oriented waste management models are required to ground this claim.