Assessment of the Sedimentological and Geotechnical Characteristics of Soil Sediments in Selected Coastal Islands in the Niger Delta, Nigeria

Abstract

Sedimentological and geotechnical characteristics of soils in selected coastal communities of the Niger Delta have been studied. Eight soil samples in total were examined to ascertain their sedimentological and geotechnical characteristics using sieve analysis and Casagrande methods. Using statistical metrics, it was discovered that the sediments of Okerenkoko are mostly well-sorted fine sands that are almost symmetrical and leptokurtic, with values averaging 2.06, 0.59, -0.093, and 1.09 for grain sizes, sorting, skewness, and kurtosis. Cumulative frequency curves plotted, showed that these sediments deposited in low energy environments. Sediments from Kurutie community were predominantly moderately sorted medium sands that are strongly fine skewed and very platykurtic with values averaging 1.35, 0.967, 1.45 and 0.051 for grain sizes, sorting, skewness and kurtosis. Sediments from Kurutie were determined to have been deposited in high energy conditions. The bivariate plot showed that sediments from Okerenkoko were deposited by beach influenced depositional processes while sediments from Kurutie were fluvial influenced. Atterberg limit results showed that soil sediments collected from Okerenkoko had liquid limit values ranging between 13%-17% while that of Kurutie was between 10%-20%. No plastic limit values were recorded, hence the plastic indices values corresponded with liquid limit values. The results show that the soil sediment in these islands may have been deposited under medium to high energy environment and the environment ranged from fluvial to beach marine environments which is characteristics of the Niger Delta. Assessment of the geotechnical properties of the soil indicate that they can support engineering constructions.