Relative Proliferation of Gullies on Three Geological Sediments: The Influence of Soil Consistency Limits and Shear Strength

Louis A Oparaku,Joseph E Edeh,Raphael T Iwar

doi:10.4236/jep.2018.91003

Abstract

This study was carried out to evaluate the influence of soil consistency limits and shear strength on the relative proliferation of gullies on three geological sediments, namely: the Upper Coal Measures (UCM), the Ajalli Sandstones (AS), and the Lower Coal Measures (LCM), which has been ranked as AS > UCM > LCM. Soil samples were collected from a depth range of 60 - 90 cm of sampling pits dug at a selected location on each of these texturally homogenous and unique formations. These were analysed for consistency limits and shear strength using standard methods and procedures. Results showed that the plasticity index (PI) of the UCM (PIUCM) was 24.49%; PIAS, 5.89%; and PILCM, 44.85%. The shear strength (S) of the UCM (SUCM) was 314.74 KN/m2; SAS, 196.23 KN/m2; and SLCM, 321.72 KN/m2. The results of the study show that rankings of the respective contributions of these two geotechnical properties to the vulnerability of the sediments to gully (soil) erosion follow the same order of proliferation of gullies on the plateau landscape: AS > UCM > LCM. Hence, consistency limits and shear strength parameters partly influence and explain the relative proliferation of gullies on the three formations. Further studies are required to determine other soil factors of gully erosion in the area in order to evolve appropriate management strategies for these sediments.

Highlights

This study was carried out to evaluate the influence of soil consistency limits and shear strength on the relative proliferation of gullies on three geological sediments, namely: the Upper Coal Measures (UCM), the Ajalli Sandstones (AS), and the Lower Coal Measures (LCM), which has been ranked as AS > UCM > LCM
An assessment of the textural characteristics of the sediments showed that the proliferation of gullies on each unit was related to its vulnerability to erosion, which was ranked as AS > UCM > LCM [10]
This study leads to the following conclusions: 1) The plasticity indices of the geological sediments of the Idah-Ankpa Plateau can be ranked as PlAS < PlUCM < PlLCM. 2) Because Pl is inversely related to soil erodibility, the vulnerability to erosion of the sediments can be ranked as AS > UCM > LCM based on the plasticity index (PI) criterion

Summary

Introduction

Nigeria, which is underlain 100% by three geological sediments [1]. That the proliferation of gullies on the IAP can be ranked as AS > UCM > LCM. He noted that the relative proliferation of gullies on these geological units bears a relationship with the vulnerability to erosion of the sediments of which each unit is composed. Soil erodibility is a measure of a soil’s vulnerability to erosion [3]. When two or more soils located in the same ecological region are exposed to the same management practices, they suffer different amounts of erosion which are attributable to their inherent erodibility [3]. When two or more soils located in the same ecological region are exposed to the same management practices, they suffer different amounts of erosion which are attributable to their inherent erodibility [3]. [4] identified the different soil factors that influence erodibility to include texture, structure, aggregate stability, shear strength, permeability, infiltration capacity, organic matter, and other chemical properties

Methods

Results

Conclusion