Characterization and mapping of gully erosion features in two geological formations of eastern nigeria

Project Abstract

Gully erosion is a significant environmental issue in many parts of Nigeria, leading to land degradation, loss of agricultural productivity, and infrastructure damage. This study focuses on the characterization and mapping of gully erosion features in two geological formations in eastern Nigeria, namely the Abakaliki Shale and the Mamu Formation. The objective of this research is to analyze the spatial distribution, morphological characteristics, and factors contributing to gully erosion in these geological formations. Field surveys were conducted to identify and map gully erosion features in the study area using GPS technology and GIS software. The gully morphology was classified based on size, shape, depth, and width to understand the variations in erosion features within the different geological formations. Soil samples were collected from the gully sites for laboratory analysis to determine the physical and chemical properties influencing erosion processes. The results revealed that gully erosion features in the Abakaliki Shale formation were predominantly V-shaped with sharp incised walls, while gullies in the Mamu Formation exhibited a wider and shallower morphology. The spatial distribution of gullies showed clustering patterns in certain areas, indicating localized erosion hotspots. The soil analysis indicated that the Abakaliki Shale had higher clay content and lower infiltration rates compared to the Mamu Formation, contributing to increased erosion susceptibility. Geospatial analysis was employed to create maps depicting the extent and severity of gully erosion in the study area. The maps highlighted areas with high erosion risk, providing valuable information for land use planning and erosion control measures. Furthermore, statistical analysis was conducted to assess the relationship between geological parameters, land cover, and gully erosion occurrence. In conclusion, this study contributes to the understanding of gully erosion dynamics in different geological formations of eastern Nigeria. The findings emphasize the importance of considering geological characteristics and soil properties in assessing and managing gully erosion. The generated maps and analysis can support policymakers, land managers, and researchers in implementing targeted interventions to mitigate the impacts of gully erosion and promote sustainable land use practices in the region.

Project Overview

<p> </p><p>With the aid of Global Positioning System (GPS) and Satellite Aerial Photo, a comparative<br>characterization and mapping of soil gully erosion features on two geological formations<br>were carried out in Nsukka area of eastern Nigeria. The two geological formations were<br>Ajali and Mamu formations. The study involved the use of base map created using a<br>Geographic Information System (GIS) (GPS Track Marker) and Satellite Photo downloaded<br>from the internet using the same GIS (GPS Track Marker). This aided the field work for<br>erosion site study and data collection. A total of seventy (70) erosion sites with an average<br>length of about 1606.5 meters, average width of about 64.2 meters and average depth of 8.6<br>meters were visited in Ajali formation. On the other hand, only nine with an average length<br>of about 484.2 meters, average width of about 6.5 meters and an average depth of about 3.7<br>meters were visited in Mamu. In Ajali formation, forty three new erosion sites were<br>identified to add to the twenty seven old sites while in Manu formation only five new sites<br>were identified to add to the four old sites. Three profile pits were dug in each formation to<br>represent the soils. They are sites of Ada (Mpt1), Agu-Orba (Mpt2) and Agu-Ekwegbe<br>(Mpt3) on Mamu Formation while Iheaka (Apt1), Ede-Oballa (Apt2) and Aku (Apt3) were<br>sites on Ajali Formation.</p><p>The soils from the pits were sampled and analyzed for some physical and chemical properties. The properties were, colour, texture, soil reaction, organic matter, exchangeable bases, total nitrogen and available phosphorus, exchangeable acidity, cation exchange capacity, and aggregate stability. There was a significant difference in the value of gully length and width while the depth was statistically the same. There was a positive significant correlation between length and width (r = 0.409), depth and width (r = 0.862), but non significant correlation between length and depth (r = 0.188) in Mamu Formation, while a positive and significant correlation was found between length and depth (r = 0.635), length and width (r = 0.578), depth and width (r = 0.689) in Ajali formation. The results of the soil percentage state of aggregation (PSA) and percentage aggregate stability (PAS) was low at both soils. There was no significant difference between their mean weight diameters (MWD). Their low MWD values (1.1mm) in the soil of Mamu formation and 1.2mm in the soil of Ajali formation were indication that the soil were highly susceptible to erosion. Both soils of the studied area have low silt content (8% in the soil of Ajali and 5% in the soil of Mamu), but moderate to high fine sand values (18% in Ajali and 49% in Mamu). These could be one of the factors promoting the soil erodibility. At micro</p> <br><p></p>