Environmental

Author: Fidelis A. Abija Abstract The coastal zone is a dynamic environment under hydrodynamic forcings and adverse consequences of geohazards with potential for disasters. In this this studies, ASTER DEMs and LandSat 4,5 imageries have been analyzed in ArcGIS to determine the amount and rates of coastal subsidence, shoreline movements and coastal erosion and supplemented with secondary tide and wave data to model wave conditions in the face of climate change. Results indicates that the average ground subsidence was -2.6m at a rate of – 0.144m/yr. on the Bayelsa coast and -3.75m at a rate of -0.208m/yr on the Rivers coast. The rate of coastal erosion along the Akwa Ibom, Rivers and Bayelsa States in the Niger Delta coastline depicts a linear erosion of -13,054m, -17,519m and -81,532m in Akwa Ibom, Rivers andBayelsa respectively with erosion rates of -5.5m/yr along Akwa Ibom, -7.2m/yr along Rivers and -11.1m/yr along the Bayelsa coastline. The net shoreline retreat equivalent of incidental erosion was -8,590m along the Akwa coastline, – 9,240m along Rivers coastline and -70,383m along the Bayelsa coastline. Modeled hydrodynamics parameters predicted waves with mean wavelength of 178.95m, wave celerity of 13.01m/sec, group wave celerity of 11.27m/sec with maximum horizontal velocity of 0.4m/sec exerting an energy flux of 15, 902.00w/m. In considerations the stack realities of climate change, vulnerability assessment, integrated coastal zone management and climate change adaptation strategies for coastal protection are recommended.

Authors: Abam, T.K.S., Giadom, F.D. and Abija, F.A. Abstract The short service life of pavements in the Niger Delta has resulted in high recurrent maintenance cost of roads. Pavement failures have been attributed to widespread weak, expansive clays and silty soils, which lead to high water table issues and poor drainage without an understanding of the mechanisms involved and an appreciation of theadequacy of the codes used in their design. This paper explores the concepts of pavement design, assessing the necessity and functions of individual layers as well as the geological materials they are made of. The paper then identifies the weaknesses in the pavement design culture practiced in Nigeria to include poorly prepared subgrades, use of unsuitable aggregates, insensitivity to the environmental conditions among others. It further investigates the relationship between the distribution of axial load and the thicknesses of pavement layers to identify vulnerabilities particularly in the Niger Delta that can promote pavement failure. It examines the influence of moisture on the attainment of adequate compaction as well as on the resilience of pavements. The paper argues that the extensive weak subgrades and rapid variability of superficial geology such as exist in the Niger Delta demands a review of the national design code to accommodate the peculiarities of the region. To ensure resilient pavements, understandingsoil and environmental conditions is paramount. This involves integrating soil-structure interaction principles, ground improvement and stabilization techniques, as well as risk assessment methodologies to enhance structural integrity and sustainability of pavements.

Authors: Owoyemi, O.O., Ejikunle, O.B. and Afolagboye, L.O. Abstract Recycling waste glass for subgrade soil improvement not only contributes to the development of sustainable and resilient highways but also mitigates the environmental impact of the vast quantities of glass generated daily. This study examines the potential of using waste glass to enhance the geotechnical properties of soil intended for highway subgrade applications. Soil sample was obtained from a borrow pit in Oyun, Southwestern Nigeria, where lateritic soils are quarried for construction purposes. The mineralogical and geochemical properties of the natural soil were analyzed using X-ray diffraction (XRD) and X-ray fluorescence (XRF). Pulverized waste glass underwent grain size distribution analysis, and the soil samples were mixed with waste glass in proportions of 0.5%, 1%, 1.5%, and 2% by weight. The impact of waste glass powder addition on Atterberg limits, linear shrinkage, compaction parameters, swell potential, and both soaked and unsoaked California Bearing Ratio (CBR) was investigated. The aging effect on the CBR of the stabilized samples was assessed by repeating the soaked CBR tests after 7, 14, and 21 days. Results indicated that the liquid limit, plastic limit, plasticity index, linear shrinkage, swell potential, and of the stabilized soils decreased with increasing glass content. Conversely, the maximum dry density and both soaked and unsoakedCBR values increased, while the optimum moisture content decreased with higher glass content. The stabilized soils maintained their strength even after 21 days of soaking. Waste glass, even at a 0.5% inclusion by weight, acts as an effective cementing agent, improving soil properties for highway foundations.