Statistical analysis of variability in properties of soils in gully erosion sites of Agulu-Nanka-Oko area, southeastern Nigeria

Osadebe, CC; Akpokodje, EG

doi:10.4314/jmg.v43i2.47912

Cited by 4 publications

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“…The five sections from which samples were studied are labelled with closed circles. General environments for the Imo Formation from Obi (2000; fluvio-deltaic); the Imo Formation from Reyment (1965; shallow marine) and Anyanwu and Arua (1990; deltaic); and the Ameki Formation from White (1926; estuarine), Nwajide (1979) and Arua (1986; both lagoonal), and Adegoke (1969) and Fayose and Ola (1990; both shallow marine). The Palaeocene–Eocene boundary is placed between the Imo and Ameki formations following Nwajide (1990) and Oboh-Ikuenobe et al (2005) and shown as a dashed line to indicate uncertainty.…”

Section: Methodsmentioning

confidence: 99%

Descriptive systematics of Upper Palaeocene–Lower Eocene pollen and spores from the northern Niger Delta, south-eastern Nigeria

Mander

Oboh‐Ikuenobe

2023

Palynology

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Fossil pollen and spores are a vital source of information on the geological history of tropical vegetation including reconstructions of vegetation diversity and composition. However, such work relies on a sound taxonomic framework, and this is challenging to achieve because of the large number of pollen and spore morphotypes that are encountered in palynological preparations from tropical sediments. In tropical West Africa, for example, extensive taxonomic work on Cretaceous-Paleogene pollen and spores was undertaken in the later part of the twentieth century, but more recent palynological work has focussed on stratigraphy and basin evolution, and there is a need for additional taxonomic work on the pollen and spores of this region. We have undertaken a descriptive systematic study of pollen and spores (sporomorphs) from 15 sediment samples spanning the Upper Palaeocene-Lower Eocene of south-eastern Nigeria. A palynoflora consisting of 29 spores, two gymnosperm pollen grains, and 138 angiosperm pollen grains is described. Two new spore species are proposed, and one new genus and 18 new species of angiosperm pollen are proposed. The general vegetation type represented by the palynoflora consists of palm-dominated swamps, perhaps with mangroves. The richness of each sample ranges from 29 to 76 sporomorph taxa, and rarefaction analysis suggests an increase in diversity from the Palaeocene to the Eocene in this region. Samples from the Palaeocene Upper Nsukka Formation are dominated by pollen with botanical affinities to the Arecaceae (palms) and Araceae (arums), and this assemblage is very similar to the Palaeocene in the Neotropics.

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Section: Methodsmentioning

confidence: 99%

Descriptive systematics of Upper Palaeocene–Lower Eocene pollen and spores from the northern Niger Delta, south-eastern Nigeria

Mander

Oboh‐Ikuenobe

2023

Palynology

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“…The Nanka Formation is predominantly composed of loose and poorly consolidated fine-grained sand materials with low clay content and little or no coarse-grained aggregates (Igwe & Egbueri, 2018). It is noted as the loose sand facies of the Ameki Group (Nwajide, 1979(Nwajide, , 1980, outcrops over an area in excess of 1,400km exclusively east of the Niger and noted to be very susceptible to erosion. The Formation is made up of loose, tabular to planar cross bedded, flaserbedded, fine to medium grained sand, with a few mudrock breaks.…”

Section: The Setting Of the Study Areamentioning

confidence: 99%

Comparative Analysis of the Expansion Rate and Soil Erodibility Factor of Some Gullies in Nnewi and Nnobi, Southeastern Nigeria.

Nzereogu

Igwe

Emeh

et al. 2023

Preprint

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The study involved an integration of field observations, geotechnical analysis, slope stability analysis, gully expansion rate analysis and determination of the soil erodibility factor (K). Fifteen representative gullies were studied extensively. The Grain size distribution analysis revealed that the soils are composed of gravel (5.77–17.67% and 7.01–13.65%), sand (79.90-91.01% and 82.47–88.67%), and fines (2.36–4.05% and 3.78–5.02%) for Nnewi and Nnobi respectively. The cohesion and internal friction angle values range from 1–5kPa and 2-5kPa and from 29–38° and 30–34° for Nnewi and Nnobi respectively, which suggests that the soils have low shear strength and are susceptible to shear failure. The plasticity index (PI) of the fines showed that they are nonplastic to low plastic soils and highly liquefiable with values ranging from 0–10% and 0–9% for Nnewi and Nnobi respectively. Slope stability analysis gave factor of safety (FoS) values in the range of 0.50–0.76 and 0.82–0.95 for saturated condition and 0.73–0.98 and 0.87–1.04 for unsaturated condition for both Nnewi and Nnobi respectively indicating that the slopes are generally unstable to critically stable. The erosion expansion rate analysis for a fifteen-year period (2005–2020) revealed an average longitudinal expansion rate of 36.05m/yr and 10.76m/yr for Nnewi and Nnobi gullies respectively. The soil erodibility factor (K) are 8.57x10− 2 and 1.62x10− 4 for Nnewi and Nnobi respectively indicating that the soils in Nnewi have higher erodibility potentials than those of Nnobi. Conclusively, both the Nnewi and Nnobi areas are highly prone to erosion.

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“…This is especially applicable to regions with excessive gullying, given variability in potential size, shape, and occurrence (Knight et al 2007 Data extracted from remotely sensed imagery have been used to provide specific information for policy makers to enable reclamation of degraded areas like gullies and landslides (Nwilo, et al 2011 andOkereke, et al 2012). Recent advances in satellite technology, GIS, and digital image processing, have led to the development of new techniques for semi-automatic and/or automatic gully detection (Nweze 2011 andOsadebe andAkpokodje 2007).…”

Section: Assessmentmentioning

confidence: 99%

Determining Causes of Gully Erosion and Associated Rates of Change in South-east Nigeria, Using a Remote Sensing and GIS Methodology

Iro

2020

Preprint

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In this work a study of gully erosion in southeast Nigeria is presented. The study of gully development on a regional scale is currently undermined by the inherent costs associated with consistent field monitoring and the lack of historic measurements to perform time series analysis. The analysis of study area topography at 30m resolution reveals 85% of the surveyed gullies develop on concave slopes with high values of 6 plan curvatures and >50 inclines. Results also reveal high association with ferralsols soils. Statistical analysis to determine significance of variables on the proportional yearly gully change in metre squared per square metre were conducted via principle component analysis. The analysis of this work was restricted to the time periods 2006/7, 2009/10, and 2014/15. The approach did not report any existence of one singular driver of erosion across the studied years and multiple sites confirming the complexity of gullies. The PCA showed that the level of variance explained in the yearly gully change variable was most similar in PC1 (representing the component with the highest eigenvalue) to Vegetation loss, Vegetation loss and slope in the respective years.The study offers a method of monitoring gully development from early stage to maturity and exemplifies the complexity and variability of erosion drivers in the SE Nigeria region. It presents a verified approach to local and regional monitoring of gullies, enacted through use of low budget/computing cost remote sensing and classification technologies, and serves to embolden civilian and governmental efforts to manage the societal and environmental menace of gully erosion.

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Statistical analysis of variability in properties of soils in gully erosion sites of Agulu-Nanka-Oko area, southeastern Nigeria

Cited by 4 publications

References 0 publications

Descriptive systematics of Upper Palaeocene–Lower Eocene pollen and spores from the northern Niger Delta, south-eastern Nigeria

Descriptive systematics of Upper Palaeocene–Lower Eocene pollen and spores from the northern Niger Delta, south-eastern Nigeria

Comparative Analysis of the Expansion Rate and Soil Erodibility Factor of Some Gullies in Nnewi and Nnobi, Southeastern Nigeria.

Determining Causes of Gully Erosion and Associated Rates of Change in South-east Nigeria, Using a Remote Sensing and GIS Methodology

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