Browsing by Author "Aizebeokhai, Ahzegbobor P."

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Assessing subsurface heterogenenity and infiltration capacity at a restored wetland using geophysical imaging and infiltration tests
(2025) Otchere, Nana-Aboagye; Aizebeokhai, Ahzegbobor P.; Martin-Hayden, James; Doro, Kennedy O.
Wetland soil properties and stratigraphic heterogeneity influence their water-holding capacity, 15 infiltration, and subsurface flow. Infiltration, however, depends on the soil’s saturated hydraulic 16 conductivity (Ksat) whose spatial variability at field scale is difficult to quantify. In this study, we 17 combined electromagnetic imaging (EMI) and electrical resistivity (ER) with infiltration tests to 18 assess the spatial variation in the shallow subsurface stratigraphy and Ksat at a restored wetland in 19 northwest Ohio. We used a Geonics EM38-MK2, with a transmitter and two receivers spaced 0.5 20 and 1.0 m to map the spatial distribution of the soil’s apparent electrical conductivity (ECa). The 21 ER measurements were acquired along nine transects using a SuperSting R8 resistivity meter 22 with 84-electrode and a dipole-dipole electrode array. The ER results, constrained with 23 lithostratigraphic logs, showed 0.7 m thick topsoil (silty loam) underlain by 0.5 m thick clayey 24 loam interspersed with coarser materials and alternating units of diamictons. The observed ECa 25 were relatively higher (10 – 40 mS/m) for the 0.5 m T-R spacing compared to the 1.0 m spacing 26 (8 – 36 mS/m). The spatial distribution of Ksat ranged from 0.01 – 0.9 mm/min with higher 27 values at areas with high silt and sand content. A least-squared linear regression between Ksat 28 and ECa yielded coefficient of determination (R2) values >0.62 indicating the effectiveness of 29 EMI for predicting the spatial variation of Ksat. Thus, combining geophysical imaging with field 30 infiltration tests provided valuable insights into infiltration through the soil and potential 31 subsurface flow at the restored wetland with limited details on subsurface flow.
High-resolution non-invasive mapping of vertical heterogeneity in sandy soils of the Oak Openings Region using electromagnetic imaging and ground penetrating radar
(Research Square, 2025-08) Aizebeokhai, Ahzegbobor P.; Urom, Obinna; Doro, Kennedy O.
Abstract 10 Traditional soil investigation methods involve laboratory analysis on soil cores or direct 11 measurements of soil properties with in-situ sensors. These methods are, however, destructive, 12 labour-intensive, and ineffective in capturing the spatial variation of soil properties. Geophysical 13 methods provide a non-invasive approach to rapidly characterize soil properties distribution. Gaps, 14 however, exist in the use of non-contact-based geophysical methods such as ground penetrating 15 radar (GPR) and electromagnetic imaging (EMI) for characterizing the vertical variation of soil 16 properties. This study assesses the use of EMI and GPR for quantifying the vertical variation of 17 soil moisture content (SMC), soil organic matter (SOM), and soil texture. Co-located EMI and 18 GPR surveys were conducted along 12 transects at the Stranahan Arboretum research site in 19 Toledo, Ohio. Soil samples collected from nine locations along the transects were segmented into 20 63 subsamples and analysed for SMC, SOM, and soil texture. Apparent electrical conductivities 21 (ECa) from EMI were inverted to obtain lateral and vertical variations of soil electrical conductivity 22 (EC), which captures three major lithostratigraphic units (sand, silty loam, and silt) found in soil 23 cores within the top 2.0 m. Soil EC correlates with SMC, SOM and soil texture, with coefficient 24 of determination (R2) ranging from 59-91%. The GPR radargrams show reflectors consistent in 25 delineating sandy and silty clay soils but unable to distinguish between sand and silt. These results 26 validate the effectiveness of using EMI and GPR to delineate vertical variation of soil properties 27 and characterize stratigraphic heterogeneity, expanding the possibilities for non-invasive three28 dimensional (3D) soil properties mapping
Hydrogeophysical Investigations for Groundwater Resources Sustainability in Parts of the Eastern Dahomey Basin, Nigeria
(ImprintCRC Press, 2024) Oyeyemi, Kehinde D.; Aizebeokhai, Ahzegbobor P.; Okon, Emmanuel E.; Oladunjoye, Michael A.
Geophysical surveys including geoelectrical resistivity and time-domain induced polarization (IP) techniques have been conducted in Ota in Eastern Dahomey Basin. Thirty vertical electrical sounding (VES) profilings were conducted using a Schlumberger array with an AB/2 range of 180–240 m. Two profiles of 2D electrical resistivity imaging and IP surveys were conducted with Wenner array configuration. The delineated geoelectric layers are topsoil (lateritic clay), clayey sand, sandy clay, sand, and shale or clay units. Two aquifers were delineated in the area with the upper aquifer being a fine-to-medium sand and the lower aquifer of a poorly medium-to-coarse sand unit. The aquifer resistivity ranges are 347.4–411.4 https://www.w3.org/1998/Math/MathML" display="inline"> Ω m https://www.w3.org/1999/xlink" xlink:href="https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west 1.amazonaws.com/9781003454908/c35032d3-f666-459f-b1ca a1b405d5a7b1/content/C025_equ_0001.tif"/> and 104.5–143.3 https://www.w3.org/1998/Math/MathML" display="inline"> Ω m https://www.w3.org/1999/xlink" xlink:href="https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west 1.amazonaws.com/9781003454908/c35032d3-f666-459f-b1ca a1b405d5a7b1/content/C025_equ_0001.tif"/> for the upper and lower aquifer, respectively. The hydraulic parameters of both aquifers were estimated using established mathematical relations. The upper aquifer has porosity, hydraulic conductivity, and transmissivity ranges of 19.1% 21.8%, 10.8 × 10−2 (m/s)–17.0 × 10−2 (m/s), and 1.49–2.4 (m2/s), while the lower aquifer unit has porosity, hydraulic conductivity, and transmissivity values of 43%–55%, 248 × 10−2–782 × 10−2 (m/s), and 34.72–101.66 (m2/s). High hydraulic parameters in the two aquifers are important for sustainable groundwater development, ensuring efficient use and protection of this vital resource. Their significance extends to promoting regional economic growth by supporting agriculture, industries, and tourism. Mapping faults in the area highlights the need for hydrogeological modeling to discern their impact on aquifer parameters, vital for precise resource management, and predicting potential effects on availability and quality.
NS23C-03 Geophysical Imaging for Assessing Restored Wetlands' Soil Properties, Infiltration Rates, and Potential Surface Groundwater Interaction
(AGU24, 2024) Aizebeokhai, Ahzegbobor P.; LaPoint, Hannah N.; Doro, Kennedy O.
Efforts to reduce nutrient loading into Lake Erie include restoring old farm fields within Northwestern Ohio to wetlands. With a history of intensive farming, these fields are characterized by legacy nutrients, altered soil structure and drainage tiles. Inadequate knowledge of soil properties distribution, drainage tile locations and potential surface groundwater interaction at the sites limits restoration projects' effectiveness. This study combined a rapid geophysical site characterization framework with in-situ soil cores and hydraulic tests to assess variations in soil properties and hydraulic processes. We used a 250MHz PulseEkko ground penetrating radar (GPR) system and an EM38-MK2 conductivity meter to acquire GPR and electromagnetic imaging (EMI) measurements at selected wetlands with the equipment towed behind a utility terrain vehicle to allow extensive spatial coverage. Electrical resistivity (ER) data were acquired along transects using a Supersting R8 resistivity meter with an 84-electrode switch box. The ER measurement was done using a dipole-dipole array with 1m electrode spacing. Co-located soil cores were collected along the transects for laboratory soil moisture content, organic matter and texture measurements. In contrast, in-situ measurement of soil-saturated hydraulic conductivity was done using a SATURO infiltrometer. The apparent electrical conductivity (ECa) and ER distribution show comparable subsurface structures and parameter zones, and ECa correlates strongly with soil moisture, organic matter and silt contents (R2 >0.7; p-value <0.002). The ECa also notably correlates with the soil saturated hydraulic conductivity (R2 = 0.85), indicating the possibility of using EMI to rapidly characterize potential water retention zones (low Ksat) in restored wetlands. The spatial distribution of geophysical parameters depends linearly on soil properties distribution. This geophysical-soil-property relation, developed through a rapid site characterization framework, allows for improved soil sampling and monitoring plans. This study shows the effective application of EMI, GPR, and ER for pre- and post restoration characterization of old farm fields with legacy nutrients and drainage tiles that contribute to nutrient loading into Lake Erie.