Characterizing gully‑prone zones using geophysical and geotechnical approaches: a case study of Njaba South‑Eastern Nigeria
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Date
2023-11-14
Journal Title
Journal ISSN
Volume Title
Publisher
SPRINGER
Abstract
Over the years, Njaba has been known to be bedeviled with worrying gully erosion challenges. This is attributed to the geologic
makeup of the soil and other environmental factors. Geophysical and geotechnical characterization of the soil within
Njaba and its environs has been carried out with the aim of determining the potentials in the development and enhancement
of gullies within the area. 23 vertical electrical sounding were conducted using Schlumberger array configuration with
maximum current electrode spacing of 350 m, while two soil samples were also collected for geotechnical studies. The
first layers were used to categorize the soils into competence and corrosive soils. Qualitative interpretation reveals that the
sites are characterized by six (6) resistivity type curves, namely; 6-HK, 2-AK, 3-KH, 2-QH, 4-KK, 2-AH. The results from
the iso-resistivity showed that the resistivities of the layers increased progressively with depth as the maximum electrode
spacing increased. The transverse resistance calculated varies from 1408950 to 30987 Ωm, and the longitudinal conductance
varies from 0.03163 to 0.00099876 mho. From the competence and corrosivity rating, the soils were categorized from
highly competent to moderately competent for the competence categories with varying resistivities of 2800 to 154 Ωm and
for the corrosivity category, soils were categorized from essentially non-corrosive to mildly corrosive soils with varying
resistance of 182.0 to 154.0 Ωm. The coefficient of anisotropy determined averages 1.25, 1.14 and 1.06 at three different
sites. The results of the compaction tests indicate that the Optimum Moisture Content ranged from 11.1–11.5% is required
to achieve Maximum Dry Density of the samples ranging from 0.18–2.15 mg/m3. From the study, it can be ascertained that
the soil is of low compressibility. The study suggests among others that surface and subsurface flows and drainage should be
controlled by directing water through concrete channels into lined artificial reservoirs or straight into lakes or river plains.
Description
Keywords
Geophysical Analysis · Azimuthal Resistivity · Competence and Corrosivity · Gully Erosion · Geotechnics
Citation
https://doi.org/10.1007/s13762-023-05301-0