Pub Date : 2022-04-08DOI: 10.1080/20909977.2022.2055829
T. Abdallatif, A. Khozym, A. Ghandour
ABSTRACT Geophysical investigation activities were conducted at ICAD-II, Abu Dhabi, UAE using Multi-Channel Analysis of Surface Waves (MASW) to determine subsurface geology , material stiffness, potential weak zones down to ~35 m depth, and to propose the appropriate seismic site classification for a proper foundation design. A total of 20 MASW lines were carried out over a grid layout of 5 m spacing. Data acquisition, processing and inversion have been parameterised and selected to produce shear velocities that represent subsurface conditions. The estimated average shear-wavevelocity (Vs30 = 577.97 m/s) suggests that the investigated site can be classified as Class C (V.D. Soil & Soft Rock). The constructed geological model comprises sand, weak sandstone, weak mudstone, and hard mudstone. Analysing the shear wave velocities indicates the absence of apparent cavities/ hazardous zone . However, a relatively weak layer of sandstone/mudstone rocks intercalations was detected from ~7m to ~25m. Meanwhile, the uncorrelated part of 2D MASW data indicates potentially harder mudstone encountered at a depth starting from ~25 m to >35 m. Hence, the foundation layer may be placed on the upper surface of the sandstone bed (~7 m) depending on the height and load of the proposed building and following the construction standards and requirements of the structural engineer.
{"title":"Determination of Seismic Site Class and Potential Geologic Hazards using Multi-Channel Analysis of Surface Waves(MASW) at the Industrial City of Abu Dhabi, UAE","authors":"T. Abdallatif, A. Khozym, A. Ghandour","doi":"10.1080/20909977.2022.2055829","DOIUrl":"https://doi.org/10.1080/20909977.2022.2055829","url":null,"abstract":"ABSTRACT Geophysical investigation activities were conducted at ICAD-II, Abu Dhabi, UAE using Multi-Channel Analysis of Surface Waves (MASW) to determine subsurface geology , material stiffness, potential weak zones down to ~35 m depth, and to propose the appropriate seismic site classification for a proper foundation design. A total of 20 MASW lines were carried out over a grid layout of 5 m spacing. Data acquisition, processing and inversion have been parameterised and selected to produce shear velocities that represent subsurface conditions. The estimated average shear-wavevelocity (Vs30 = 577.97 m/s) suggests that the investigated site can be classified as Class C (V.D. Soil & Soft Rock). The constructed geological model comprises sand, weak sandstone, weak mudstone, and hard mudstone. Analysing the shear wave velocities indicates the absence of apparent cavities/ hazardous zone . However, a relatively weak layer of sandstone/mudstone rocks intercalations was detected from ~7m to ~25m. Meanwhile, the uncorrelated part of 2D MASW data indicates potentially harder mudstone encountered at a depth starting from ~25 m to >35 m. Hence, the foundation layer may be placed on the upper surface of the sandstone bed (~7 m) depending on the height and load of the proposed building and following the construction standards and requirements of the structural engineer.","PeriodicalId":100964,"journal":{"name":"NRIAG Journal of Astronomy and Geophysics","volume":"39 1","pages":"193 - 209"},"PeriodicalIF":0.0,"publicationDate":"2022-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81461513","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-04-04DOI: 10.1080/20909977.2022.2057148
Ahmed Elhadary, M. Rabah, Essam Ghanim, Rasha Mohie, A. Taha
ABSTRACT The improvement of unmanned aerial system and photogrammetric computer vision (CV) algorithms has presented an aerial imaging technique for high accuracy and low-cost alternatives for mapping and topographic applications. Structure from motion (SFM) is an automation photogrammetric CV algorithm used for generating 3D coloured point clouds and 3D models from overlapping images. One of the biggest problems preventing the automation extraction and matching key points in the aligning aerial images is the non-texture of the covered area surface. This paper assessed the effect of flight altitude and overlap degree on 3D point clouds’ geometric accuracy and models produced by unmanned aerial vehicle (UAV) images captured over non-textured sandy areas. Four flight altitudes (140, 160, 180 and 200 m) related to spatial resolution (3.41, 3.9, 4.39 and 4.68 cm/pix ground sample distance (GSD)), respectively, and three overlap levels (60%, 70% and 80%) were assessed using RGB images captured by UX5 UAV over a non-textured sandy area in Jahra, Kuwait. The results showed that altitude increment might reduce flight time, processing time and cost, keeping with the acceptable and suitable geometric accuracy. Generally, favourable results are obtained for the four altitudes and overlap degrees of 80% at least. Multivariate nonlinear regression analysis was used to fit the relation between geometric accuracy, image overlap and GSD cm/pixel for the seven missions determining two formulas that predict the geometrical accuracy of the UAV point cloud with a precision of 92.76% and 91.91% for both formulas.
无人机系统和摄影测量计算机视觉(CV)算法的改进为测绘和地形应用提供了一种高精度和低成本的航空成像技术。SFM (Structure from motion)是一种自动摄影测量CV算法，用于从重叠图像中生成3D彩色点云和3D模型。被覆盖区域表面的非纹理性是阻碍对直影像中关键点自动提取与匹配的最大问题之一。本文评估了飞行高度和重叠度对无人机(UAV)在非纹理沙区捕获的三维点云几何精度和模型的影响。利用UX5无人机在科威特Jahra无纹理沙地上拍摄的RGB图像，分别评估了与空间分辨率(3.41、3.9、4.39和4.68 cm/pix地面样本距离(GSD))相关的4个飞行高度(140、160、180和200 m)和3个重叠水平(60%、70%和80%)。结果表明，高度增加可以减少飞行时间、加工时间和成本，保持可接受的、合适的几何精度。一般来说，在四个高度，重叠度至少达到80%时，都能得到较好的结果。采用多元非线性回归分析，拟合了7个任务的几何精度、图像重叠与GSD cm/pixel之间的关系，确定了2个预测无人机点云几何精度的公式，其精度分别为92.76%和91.91%。
{"title":"The influence of flight height and overlap on UAV imagery over featureless surfaces and constructing formulas predicting the geometrical accuracy","authors":"Ahmed Elhadary, M. Rabah, Essam Ghanim, Rasha Mohie, A. Taha","doi":"10.1080/20909977.2022.2057148","DOIUrl":"https://doi.org/10.1080/20909977.2022.2057148","url":null,"abstract":"ABSTRACT The improvement of unmanned aerial system and photogrammetric computer vision (CV) algorithms has presented an aerial imaging technique for high accuracy and low-cost alternatives for mapping and topographic applications. Structure from motion (SFM) is an automation photogrammetric CV algorithm used for generating 3D coloured point clouds and 3D models from overlapping images. One of the biggest problems preventing the automation extraction and matching key points in the aligning aerial images is the non-texture of the covered area surface. This paper assessed the effect of flight altitude and overlap degree on 3D point clouds’ geometric accuracy and models produced by unmanned aerial vehicle (UAV) images captured over non-textured sandy areas. Four flight altitudes (140, 160, 180 and 200 m) related to spatial resolution (3.41, 3.9, 4.39 and 4.68 cm/pix ground sample distance (GSD)), respectively, and three overlap levels (60%, 70% and 80%) were assessed using RGB images captured by UX5 UAV over a non-textured sandy area in Jahra, Kuwait. The results showed that altitude increment might reduce flight time, processing time and cost, keeping with the acceptable and suitable geometric accuracy. Generally, favourable results are obtained for the four altitudes and overlap degrees of 80% at least. Multivariate nonlinear regression analysis was used to fit the relation between geometric accuracy, image overlap and GSD cm/pixel for the seven missions determining two formulas that predict the geometrical accuracy of the UAV point cloud with a precision of 92.76% and 91.91% for both formulas.","PeriodicalId":100964,"journal":{"name":"NRIAG Journal of Astronomy and Geophysics","volume":"1 1","pages":"210 - 223"},"PeriodicalIF":0.0,"publicationDate":"2022-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90035696","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-03-30DOI: 10.1080/20909977.2022.2057147
K. O. Olomo, S. Bayode, O. A. Alagbe, G. Olayanju, Oluwatoyin Khadijat Olaleye
ABSTRACT Airborne magnetic and radiometry data sets over potential gold mineralisation associated with mesothermal alteration zones in the western Ilesha schist belt, Southwestern Nigeria, were interpreted. This was done to provide information on possible extent of geologic transformations that accompanied gold mineralisation in the area. Interpreted gamma spectrometric data were successfully used in delineating zones of hydrothermal alteration associated with potassium K enrichment as the target for gold deposits. The geological structural features that host the ore deposits were identified as lineament represented by lithological contacts and faults/fractures that were successfully exacted from the airborne magnetic data. The potassium deviation (KD) map was computed to enhance the potassium signature of rocks in the area of study. Thus, the KD map represents real potassium distribution across the study area emanated from hydrothermal alteration where hydrothermalised zones were displayed by high KD values. First vertical derivative (FVD) and total horizontal gradient (THG) maps were used to delineate lineaments. These lineaments were connected using the frequency rose diagram with two main lineament set,; major and minor lineaments observed. The 3D Euler deconvolution (EUD) method was also applied on the THG map to locate and evaluate depths to subsurface structures. The best 3D EUD solution for dykes and contacts modelled using the Structural Index of zero (S.I = 0) was used to estimate the depth to these anomaly sources at 300 to 700 m in the study area. The EUD results also revealed several subsurface structures which were hidden in the existing geological map of the study area. A prospective mineralisation map was produced from the synthesis of both magnetic lineaments and alteration zones maps derived for the study area, showing the areas of probable high mineral resources. Strong relationships were observed between the mapped hydrothermal altered zoneseologic structures and superimpose known gold mining pits.
{"title":"Aeromagnetic Mapping and Radioelement Influence on Mineralogical Composition of Mesothermal Gold Deposit in Part of Ilesha Schist Belt, Southwestern Nigeria","authors":"K. O. Olomo, S. Bayode, O. A. Alagbe, G. Olayanju, Oluwatoyin Khadijat Olaleye","doi":"10.1080/20909977.2022.2057147","DOIUrl":"https://doi.org/10.1080/20909977.2022.2057147","url":null,"abstract":"ABSTRACT Airborne magnetic and radiometry data sets over potential gold mineralisation associated with mesothermal alteration zones in the western Ilesha schist belt, Southwestern Nigeria, were interpreted. This was done to provide information on possible extent of geologic transformations that accompanied gold mineralisation in the area. Interpreted gamma spectrometric data were successfully used in delineating zones of hydrothermal alteration associated with potassium K enrichment as the target for gold deposits. The geological structural features that host the ore deposits were identified as lineament represented by lithological contacts and faults/fractures that were successfully exacted from the airborne magnetic data. The potassium deviation (KD) map was computed to enhance the potassium signature of rocks in the area of study. Thus, the KD map represents real potassium distribution across the study area emanated from hydrothermal alteration where hydrothermalised zones were displayed by high KD values. First vertical derivative (FVD) and total horizontal gradient (THG) maps were used to delineate lineaments. These lineaments were connected using the frequency rose diagram with two main lineament set,; major and minor lineaments observed. The 3D Euler deconvolution (EUD) method was also applied on the THG map to locate and evaluate depths to subsurface structures. The best 3D EUD solution for dykes and contacts modelled using the Structural Index of zero (S.I = 0) was used to estimate the depth to these anomaly sources at 300 to 700 m in the study area. The EUD results also revealed several subsurface structures which were hidden in the existing geological map of the study area. A prospective mineralisation map was produced from the synthesis of both magnetic lineaments and alteration zones maps derived for the study area, showing the areas of probable high mineral resources. Strong relationships were observed between the mapped hydrothermal altered zoneseologic structures and superimpose known gold mining pits.","PeriodicalId":100964,"journal":{"name":"NRIAG Journal of Astronomy and Geophysics","volume":"105 1","pages":"177 - 192"},"PeriodicalIF":0.0,"publicationDate":"2022-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91351412","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-03-17DOI: 10.1080/20909977.2022.2027594
Daniel Hervé Gouet, Janvier Domra Kana, Jean Jacques Kouoh Guimbous, Fontama Yuka Ewembe, André Mbabi, S. Ngos
ABSTRACT This study is based on the analysis and interpretation of remote sensing and electrical data. This allows to characterise the geological formations in Figuil and to evaluate a basement-sediment contact or contact line (CL) of the Babouri-Figuil basin’s SE flank in the north Cameroon region. Manual and automatic extraction techniques applied on the Landsat 8 images brought out 130 lineaments following E – W (90°–100°N), N-S (0°- 10°N) and NNE-SSW (60–70°N) main directions. According to the lineaments map, the lineaments’ density map and the geological background mainly, the basement formations witness a high density of lineaments, while the low density of lineaments matches with the sedimentary formations. Meantime, in the western of Figuil, the geoelectrical surveys using DC electrical method was realised. The quantitative and qualitative interpretations of results revealed an electrical contrast between the basement characterised by high electrical gradients and the sedimentary formations characterised by low electrical gradients. This electrical contrast makes it possible an electrical discontinuity which materialises the real position of the basement–sediment contact or contact line of the SE flank of the Babouri-Figuil basin. The abovementioned information reveals proper electrical and reflection conditions for an efficient structural and geological evaluation.
{"title":"Remote sensing and DC electrical investigations in the Figuil area (North-Cameroon): structural and geological implications","authors":"Daniel Hervé Gouet, Janvier Domra Kana, Jean Jacques Kouoh Guimbous, Fontama Yuka Ewembe, André Mbabi, S. Ngos","doi":"10.1080/20909977.2022.2027594","DOIUrl":"https://doi.org/10.1080/20909977.2022.2027594","url":null,"abstract":"ABSTRACT This study is based on the analysis and interpretation of remote sensing and electrical data. This allows to characterise the geological formations in Figuil and to evaluate a basement-sediment contact or contact line (CL) of the Babouri-Figuil basin’s SE flank in the north Cameroon region. Manual and automatic extraction techniques applied on the Landsat 8 images brought out 130 lineaments following E – W (90°–100°N), N-S (0°- 10°N) and NNE-SSW (60–70°N) main directions. According to the lineaments map, the lineaments’ density map and the geological background mainly, the basement formations witness a high density of lineaments, while the low density of lineaments matches with the sedimentary formations. Meantime, in the western of Figuil, the geoelectrical surveys using DC electrical method was realised. The quantitative and qualitative interpretations of results revealed an electrical contrast between the basement characterised by high electrical gradients and the sedimentary formations characterised by low electrical gradients. This electrical contrast makes it possible an electrical discontinuity which materialises the real position of the basement–sediment contact or contact line of the SE flank of the Babouri-Figuil basin. The abovementioned information reveals proper electrical and reflection conditions for an efficient structural and geological evaluation.","PeriodicalId":100964,"journal":{"name":"NRIAG Journal of Astronomy and Geophysics","volume":"182 1","pages":"147 - 165"},"PeriodicalIF":0.0,"publicationDate":"2022-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73447260","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-03-14DOI: 10.1080/20909977.2021.1953297
O. Ademila
ABSTRACT Frequency of structural failure globally has necessitated geophysical investigation of subsurface geology of a site for engineering construction works. Combined very low frequency electromagnetic (VLF-EM) and electrical resistivity methods were used to provide detailed information on subsoil profile for documentation and references for durable and sustainable construction works. Thirteen traverses were established from which geophysical data were acquired. Major conductive geological interfaces suspected to be faults/fractured zones were identified from the plots of VLF-EM data. These points serve as 50 sounding stations further investigated using Schlumberger electrode array with vertical electrical sounding technique and electrical resistivity imaging on selected four traverses of the site. The acquired data were processed, inverted and interpreted. VLF-EM 2-D inverted models revealed conductive zones at some locations suggesting incompetent zones, responsible for structural instability. Saturated clayey subsoil and uneven bedrock topography with depressions at some points could cause differential settling which has negative impact on engineering structures. Structural failure may arise from existence of concealed geological structures, deep weathering/fractured bedrock, heterogeneous and structurally deformed (F1–F16) subsurface geological setting. Thus, classified unstable sections are considered priority in structural design and construction to mitigate unforeseen challenges. Deep foundations in form of piers and piles are encouraged to avert structural failure.
{"title":"Pre-foundation geophysical investigation of a site for structural development in Oka, Nigeria","authors":"O. Ademila","doi":"10.1080/20909977.2021.1953297","DOIUrl":"https://doi.org/10.1080/20909977.2021.1953297","url":null,"abstract":"ABSTRACT Frequency of structural failure globally has necessitated geophysical investigation of subsurface geology of a site for engineering construction works. Combined very low frequency electromagnetic (VLF-EM) and electrical resistivity methods were used to provide detailed information on subsoil profile for documentation and references for durable and sustainable construction works. Thirteen traverses were established from which geophysical data were acquired. Major conductive geological interfaces suspected to be faults/fractured zones were identified from the plots of VLF-EM data. These points serve as 50 sounding stations further investigated using Schlumberger electrode array with vertical electrical sounding technique and electrical resistivity imaging on selected four traverses of the site. The acquired data were processed, inverted and interpreted. VLF-EM 2-D inverted models revealed conductive zones at some locations suggesting incompetent zones, responsible for structural instability. Saturated clayey subsoil and uneven bedrock topography with depressions at some points could cause differential settling which has negative impact on engineering structures. Structural failure may arise from existence of concealed geological structures, deep weathering/fractured bedrock, heterogeneous and structurally deformed (F1–F16) subsurface geological setting. Thus, classified unstable sections are considered priority in structural design and construction to mitigate unforeseen challenges. Deep foundations in form of piers and piles are encouraged to avert structural failure.","PeriodicalId":100964,"journal":{"name":"NRIAG Journal of Astronomy and Geophysics","volume":"11 1","pages":"81 - 112"},"PeriodicalIF":0.0,"publicationDate":"2022-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86919732","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-03-02DOI: 10.1080/20909977.2022.2040174
Y. Hendy, H. A. Abdel Rahman
ABSTRACT We present the BV photometric observations of the open cluster M67 using the Kottamia Faint Imaging Spectro-Polarimeter (KFISP), mounted at the 74-inch telescope. We build three colour-magnitude diagrams of the Gaia EDR3 and the BV. We derived the photometric and astrometric parameters of the cluster. The mean parallax is 1.167 mas (distance is 857 ± 22 pc). The age and the reddening E(B-V) of the open cluster are 4.00 Gyr and 0.03 mag, respectively. We identified 434 members from the Gaia EDR3, with a probability >70%. The mean proper motion is obtained as mas/yr and mas/yr. We used statistical comparisons to test the quality of the observations taken from the KFISP. The statistical comparisons in the BV bands showed that there are no significant differences between observations and published catalogues.
{"title":"Photometric and statistical comparisons of the old open cluster M67 (NGC 2682) using KFISP and Gaia EDR3 astrometry","authors":"Y. Hendy, H. A. Abdel Rahman","doi":"10.1080/20909977.2022.2040174","DOIUrl":"https://doi.org/10.1080/20909977.2022.2040174","url":null,"abstract":"ABSTRACT We present the BV photometric observations of the open cluster M67 using the Kottamia Faint Imaging Spectro-Polarimeter (KFISP), mounted at the 74-inch telescope. We build three colour-magnitude diagrams of the Gaia EDR3 and the BV. We derived the photometric and astrometric parameters of the cluster. The mean parallax is 1.167 mas (distance is 857 ± 22 pc). The age and the reddening E(B-V) of the open cluster are 4.00 Gyr and 0.03 mag, respectively. We identified 434 members from the Gaia EDR3, with a probability >70%. The mean proper motion is obtained as mas/yr and mas/yr. We used statistical comparisons to test the quality of the observations taken from the KFISP. The statistical comparisons in the BV bands showed that there are no significant differences between observations and published catalogues.","PeriodicalId":100964,"journal":{"name":"NRIAG Journal of Astronomy and Geophysics","volume":"1 1","pages":"166 - 177"},"PeriodicalIF":0.0,"publicationDate":"2022-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89096426","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-02-14DOI: 10.1080/20909977.2021.2000267
M. Abdelfatah, N. M. Elhaty, A. Mousa, G. El-fiky
ABSTRACT Precipitable water vapour (PWV) plays an important role in rain prediction; up to now, lots of different measuring methods and devices are developed to observe PWV. In this paper, radiosonde techniques are used to compute PWV’s spatial and temporal variations and GNSS (Global Navigation Satellite Systems) using in spatial only. GNSS data (GPS and GLONASS) from eight Egyptian stations were processed for the year 2014. Five radiosonde stations for the period from 2005 to 2016 were used. Time series is constructed using the daily surface measurements of radiosonde stations. The linear trend is estimated by straight line fit over 12 years of seasonally adjusted PWV time series. The PWV in Egypt has a positive trend in time series at more than five radiosonde sites with a rate of 0.3 mm/year. The monthly cycle is a near sine curve and the stochastic errors are from 0% to 5.4% over 12 years. The comparison between PWV estimated from GNSS data using the PPP approach and radiosonde data for each station in year 2014 was done in the near station. The nearest two stations, GNSS station “MTRH” and radiosonde station “62,306”, get a bias of 0.66 mm. Three common interpolation techniques (Inverse Distance Weighting, Kriging, and Minimum Curve) are used. The biases of the three used methods were 1.65 mm, 1.96 mm and 0.61 mm, respectively. The statistical methods of Minimum Curve interpolation are found superior to other methods with mean error at Mersa-Matrouh, Aswan and Al-Arish stations reaching 0.1 mm, 1.0 mm and 0.30 mm, respectively. The minimum curve technique is recommended in spatial interpolation for the prediction of PWV amount.Abbreviations: PWV: precipitable water vapour; PPP: precise point positioning; GNSS: global navigation satellite system; ZPD: tropospheric zenith path delay; ZWD: zenith wet delay; IDW: inverse distance weighting; MC: minimum curvature; IGS: International GNSS service.
{"title":"Derived precipitable water vapour from GNSS and radiosonde data using time series and spatial least-square","authors":"M. Abdelfatah, N. M. Elhaty, A. Mousa, G. El-fiky","doi":"10.1080/20909977.2021.2000267","DOIUrl":"https://doi.org/10.1080/20909977.2021.2000267","url":null,"abstract":"ABSTRACT Precipitable water vapour (PWV) plays an important role in rain prediction; up to now, lots of different measuring methods and devices are developed to observe PWV. In this paper, radiosonde techniques are used to compute PWV’s spatial and temporal variations and GNSS (Global Navigation Satellite Systems) using in spatial only. GNSS data (GPS and GLONASS) from eight Egyptian stations were processed for the year 2014. Five radiosonde stations for the period from 2005 to 2016 were used. Time series is constructed using the daily surface measurements of radiosonde stations. The linear trend is estimated by straight line fit over 12 years of seasonally adjusted PWV time series. The PWV in Egypt has a positive trend in time series at more than five radiosonde sites with a rate of 0.3 mm/year. The monthly cycle is a near sine curve and the stochastic errors are from 0% to 5.4% over 12 years. The comparison between PWV estimated from GNSS data using the PPP approach and radiosonde data for each station in year 2014 was done in the near station. The nearest two stations, GNSS station “MTRH” and radiosonde station “62,306”, get a bias of 0.66 mm. Three common interpolation techniques (Inverse Distance Weighting, Kriging, and Minimum Curve) are used. The biases of the three used methods were 1.65 mm, 1.96 mm and 0.61 mm, respectively. The statistical methods of Minimum Curve interpolation are found superior to other methods with mean error at Mersa-Matrouh, Aswan and Al-Arish stations reaching 0.1 mm, 1.0 mm and 0.30 mm, respectively. The minimum curve technique is recommended in spatial interpolation for the prediction of PWV amount.Abbreviations: PWV: precipitable water vapour; PPP: precise point positioning; GNSS: global navigation satellite system; ZPD: tropospheric zenith path delay; ZWD: zenith wet delay; IDW: inverse distance weighting; MC: minimum curvature; IGS: International GNSS service.","PeriodicalId":100964,"journal":{"name":"NRIAG Journal of Astronomy and Geophysics","volume":"213 1","pages":"113 - 119"},"PeriodicalIF":0.0,"publicationDate":"2022-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79476377","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-02-02DOI: 10.1080/20909977.2021.2005336
K. Ozegin, S. O. Salufu
ABSTRACT Accurate information about soil properties is required in plant growth and yield. Hence, the rising knowledge in the preservation of favourable soil properties is basically driven by its vital role in agricultural crop productivity. Electrical Resistivity Tomography (ERT) and GIS were used for site selection, soil suitability for agricultural use and topographical effect on soil properties distribution in Ambrose Alli University. Twelve traverses were conducted across the study area using Wenner array configuration. The least-square inversion method was adopted for the inversion model using RES2Dinver. Seven soil samples were collected from the selected site for soil test and grain analysis using IS standard in order to validate the ERT results. The results of the ERT gave resistivity signatures in the form of colour variations that depict the organic matter and mineral constituents of the soil. Soil in the valley side of the study area showed low resistivity signatures < 100 Ωm, slopy portion ranged from 100 to 600 Ωm, and soil at the top of the slope has resistivity values > 600 Ωm. GIS results generally classified spatial distribution of soil parameters across the area. Soil with low resistivity values < 100 Ωm has Organic Matter (OM): 4.27–4.80 %, Phosphorus (P): 50.23–54.22 mg/kg, Potassium (K): 290.0–340.0 cmol/kg, Total Nitrogen (TN): 62.20–65.11%, and pH: 6.8 to 6.9. Soil with resistivity values ranging from 100 to 600 Ωm has OM: 2.21–2.75%, P: 30.14–34.00 mg/kg, K: 100.2–107.2 cmol/kg, TN: 54.00–59.20%, and pH: 6.7–6.8. Soil with resistivity values > 600 Ωm showed lowest value ranges for OM: 0.51–0.61%, P: 10.20–15.20 cmol/kg, K: 37.20–40.20 mg/kg, TN: 10.20–15.20 %, and pH: 7.0 − 7.2. This study has shown that the study area with resistivity values < 100 Ωm would be most appropriate for high agricultural productivity as well as soil management.
{"title":"Electrical Geophysical method and GIS in Agricultural Crop Productivity in a Typical Sedimentary Environment","authors":"K. Ozegin, S. O. Salufu","doi":"10.1080/20909977.2021.2005336","DOIUrl":"https://doi.org/10.1080/20909977.2021.2005336","url":null,"abstract":"ABSTRACT Accurate information about soil properties is required in plant growth and yield. Hence, the rising knowledge in the preservation of favourable soil properties is basically driven by its vital role in agricultural crop productivity. Electrical Resistivity Tomography (ERT) and GIS were used for site selection, soil suitability for agricultural use and topographical effect on soil properties distribution in Ambrose Alli University. Twelve traverses were conducted across the study area using Wenner array configuration. The least-square inversion method was adopted for the inversion model using RES2Dinver. Seven soil samples were collected from the selected site for soil test and grain analysis using IS standard in order to validate the ERT results. The results of the ERT gave resistivity signatures in the form of colour variations that depict the organic matter and mineral constituents of the soil. Soil in the valley side of the study area showed low resistivity signatures < 100 Ωm, slopy portion ranged from 100 to 600 Ωm, and soil at the top of the slope has resistivity values > 600 Ωm. GIS results generally classified spatial distribution of soil parameters across the area. Soil with low resistivity values < 100 Ωm has Organic Matter (OM): 4.27–4.80 %, Phosphorus (P): 50.23–54.22 mg/kg, Potassium (K): 290.0–340.0 cmol/kg, Total Nitrogen (TN): 62.20–65.11%, and pH: 6.8 to 6.9. Soil with resistivity values ranging from 100 to 600 Ωm has OM: 2.21–2.75%, P: 30.14–34.00 mg/kg, K: 100.2–107.2 cmol/kg, TN: 54.00–59.20%, and pH: 6.7–6.8. Soil with resistivity values > 600 Ωm showed lowest value ranges for OM: 0.51–0.61%, P: 10.20–15.20 cmol/kg, K: 37.20–40.20 mg/kg, TN: 10.20–15.20 %, and pH: 7.0 − 7.2. This study has shown that the study area with resistivity values < 100 Ωm would be most appropriate for high agricultural productivity as well as soil management.","PeriodicalId":100964,"journal":{"name":"NRIAG Journal of Astronomy and Geophysics","volume":"299 1","pages":"69 - 80"},"PeriodicalIF":0.0,"publicationDate":"2022-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76362336","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-02-02DOI: 10.1080/20909977.2022.2031555
Ifedayo Fadakinte
ABSTRACT Simawa town, Ogun state, lacks the required water infrastructure for rapid urban development. This study seeks to use the geoelectric method – taking into account the geology and hydrogeology of the study area – to determine the groundwater potential of the town. Fifteen Vertical Electrical Sounding (VES) stations were spread across the town to characterise the subsurface layers. Interpretation of the VES data yielded five geoelectric layers. A lithology log from a prior borehole was used as a geologic control to confirm the validity of the VES results. The five geoelectric layers correspond to the topsoil (layer 1), Akinbo clay (layer 2), Akinbo shale (Layer 3), Ewekoro limestone (Layer 4), and Abeokuta sandstone (layer 5). The Abeokuta sandstone represents the main aquifer unit, a confined aquifer that can serve as a suitable source of potable water. Boreholes drilled in Simawa town should target the confined sandstone aquifer at a minimum depth of 80 m.
{"title":"3D geophysical mapping of the subsurface to support urban water planning: a case study from Simawa, Nigeria","authors":"Ifedayo Fadakinte","doi":"10.1080/20909977.2022.2031555","DOIUrl":"https://doi.org/10.1080/20909977.2022.2031555","url":null,"abstract":"ABSTRACT Simawa town, Ogun state, lacks the required water infrastructure for rapid urban development. This study seeks to use the geoelectric method – taking into account the geology and hydrogeology of the study area – to determine the groundwater potential of the town. Fifteen Vertical Electrical Sounding (VES) stations were spread across the town to characterise the subsurface layers. Interpretation of the VES data yielded five geoelectric layers. A lithology log from a prior borehole was used as a geologic control to confirm the validity of the VES results. The five geoelectric layers correspond to the topsoil (layer 1), Akinbo clay (layer 2), Akinbo shale (Layer 3), Ewekoro limestone (Layer 4), and Abeokuta sandstone (layer 5). The Abeokuta sandstone represents the main aquifer unit, a confined aquifer that can serve as a suitable source of potable water. Boreholes drilled in Simawa town should target the confined sandstone aquifer at a minimum depth of 80 m.","PeriodicalId":100964,"journal":{"name":"NRIAG Journal of Astronomy and Geophysics","volume":"3 1","pages":"120 - 131"},"PeriodicalIF":0.0,"publicationDate":"2022-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82318214","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-16DOI: 10.1080/20909977.2021.2023999
A. Basheer, N. Salama
ABSTRACT The new city of El Alamein is one of the cities that the Egyptian government seeks to make it a tourist resort area that attract local and international tourism. This study examines how to apply geophysical methods to achieve soil study for foundational and construction purposes, especially near the seacoast. It also seeks to capture evidence of the presence of any clay lenses, as well as the intrusion of seawater into the shallow soil layers. The study uses two effective geophysical methods, the electrical resistivity tomography (ERT) and shallow seismic refraction (SSR). ERT method gained two layers, the appearance of seawater intrusion begins in the second layer. SSR method assigned the same two layers according to the seismic velocities with a thickness close to that determined by the ERT method. From seismic wave velocities, a set of geotechnical properties were calculated. From the integration of all the results, the study area divided into two zones; (1) cohesive soil zone is suitable for construction with low heights, provided that the architectural foundations are placed in the second layer, (2) loose soil and is affected by the intrusion of seawater, so it is not suitable for any construction purposes.
{"title":"Application of ERT and SSR for geotechnical site characterization: A case study for resort assessment in New El Alamein City, Egypt","authors":"A. Basheer, N. Salama","doi":"10.1080/20909977.2021.2023999","DOIUrl":"https://doi.org/10.1080/20909977.2021.2023999","url":null,"abstract":"ABSTRACT The new city of El Alamein is one of the cities that the Egyptian government seeks to make it a tourist resort area that attract local and international tourism. This study examines how to apply geophysical methods to achieve soil study for foundational and construction purposes, especially near the seacoast. It also seeks to capture evidence of the presence of any clay lenses, as well as the intrusion of seawater into the shallow soil layers. The study uses two effective geophysical methods, the electrical resistivity tomography (ERT) and shallow seismic refraction (SSR). ERT method gained two layers, the appearance of seawater intrusion begins in the second layer. SSR method assigned the same two layers according to the seismic velocities with a thickness close to that determined by the ERT method. From seismic wave velocities, a set of geotechnical properties were calculated. From the integration of all the results, the study area divided into two zones; (1) cohesive soil zone is suitable for construction with low heights, provided that the architectural foundations are placed in the second layer, (2) loose soil and is affected by the intrusion of seawater, so it is not suitable for any construction purposes.","PeriodicalId":100964,"journal":{"name":"NRIAG Journal of Astronomy and Geophysics","volume":"17 1","pages":"58 - 68"},"PeriodicalIF":0.0,"publicationDate":"2022-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82309566","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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