scholarly journals Geology and Geotechnical Investigations of the Anambra Basin, Southeastern Nigeria: Implication for Gully Erosion Hazards

2021 ◽  
Author(s):  
Azuka Ocheli ◽  
Ovie Benjamin Ogbe ◽  
Godwin Okumagbe Aigbadon
Keyword(s):  
Mean Value ◽  
Gully Erosion ◽  
Plasticity Index ◽  
Sand Content ◽  
Southeastern Nigeria ◽  
Average Value ◽  
Compaction Test ◽  
Silt Content ◽  
Anambra Basin ◽  
Geotechnical Investigations

Abstract BackgroundGeologic and geotechnical conditions of soils where Nanka and Ajali Formations outcropped in Anambra Basin, Southeastern Nigeria were investigated and accessed. This was done using detailed mapping and mechanical soil laboratory tests to unravel the genesis and continued expansion of gully erosion in the study areas. ResultsField study revealed that gully erosions are more pronounced in the study area with poor vegetation cover and a high degree of slope steepness. Grain size analysis revealed that the soils of the Nanka Formation have an average sand content value of 90.90% (sandy) and silt content value of 3.0% (low fine portions). The plasticity index of the fine portions indicates that the soils are weak plastic, with a mean value of 5.29%. The soils have an average cohesion value of 0.30kg/cm2 indicating a very weak cohesion. The soils are highly permeable; with an average value of 2.67x10-3 cm/sec. The compaction test further revealed that the soils are loosely compacted. The soils for the Ajali Formation have an average sand content value of 95.10% (sandy) and silt content value of 1.43% (low fine portions). The plasticity index of the fine portions indicates that the soils are weak plastic, with a mean value of 2.70%. The soils have an average cohesion value of 0.30kg/cm2 indicating a very weak cohesion. The soils are highly permeable; with an average value of 2.70x10-3 cm/sec. The compaction test revealed that the soils are loosely compacted.ConclusionsAfter field surveys and laboratory analyses, it was found that the gully erosions have been developing respectively on steep slopes and non-vegetated areas, and their genesis facilitated by the cohesionless and very permeable nature of the sandy formations. Following those key findings, it was proposed many practices (agronomic and engineering mainly) that can help mitigate the formations as well as the expansion of this very damaging hazard type. The potential implications of these gully erosion include damaging of buildings, residential houses, bridges and roads, loss of farmland and vegetation, isolation of villages and towns, increased migration of inhabitants as well as degradation of agricultural fertile land.

scholarly journals Geology and geotechnical investigations of part of the Anambra Basin, Southeastern Nigeria: implication for gully erosion hazards

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Azuka Ocheli ◽  
Ovie Benjamin Ogbe ◽  
Godwin Okumagbe Aigbadon
Keyword(s):  
Mean Value ◽  
Gully Erosion ◽  
Plasticity Index ◽  
Sand Content ◽  
Southeastern Nigeria ◽  
Average Value ◽  
Compaction Test ◽  
Silt Content ◽  
Anambra Basin ◽  
Geotechnical Investigations

Abstract Background Geologic and geotechnical conditions of soils where Nanka and Ajali Formations outcropped in Anambra Basin, Southeastern Nigeria were investigated and accessed. This was done using detailed mapping and mechanical soil laboratory tests to unravel the genesis and continued expansion of gully erosion in the study areas. Results Field study revealed that gully erosions are more pronounced in the study area with poor vegetation cover and a high degree of slope steepness. Grain size analysis revealed that the soils of the Nanka Formation have an average sand content value of 90.90% (sandy) and silt content value of 3.0% (low fine portions). The plasticity index of the fine portions indicates that the soils are weak plastic, with a mean value of 5.29%. The soils have an average cohesion value of 0.30 kg/cm2 indicating a very weak cohesion. The soils are highly permeable; with an average value of 2.67 × 10–3 cm/s. The compaction test further revealed that the soils are loosely compacted. The soils for the Ajali Formation have an average sand content value of 95.10% (sandy) and silt content value of 1.43% (low fine portions). The plasticity index of the fine portions indicates that the soils are weak plastic, with a mean value of 2.70%. The soils have an average cohesion value of 0.30 kg/cm2 indicating a very weak cohesion. The soils are highly permeable; with an average value of 2.70 × 10–3 cm/s. The compaction test revealed that the soils are loosely compacted. Conclusion After field surveys and laboratory analyses, it was found that the gully erosions have been developing respectively on steep slopes and non-vegetated areas, and their genesis facilitated by the cohesionless and very permeable nature of the sandy formations. Following those key findings, it was proposed many practices (agronomic and engineering mainly) that can help mitigate the formations as well as the expansion of this very damaging hazard type. The potential implications of these gully erosion include damaging of buildings, residential houses, bridges, and roads, loss of farmland and vegetation, isolation of villages and towns, increased migration of inhabitants as well as degradation of agricultural fertile land.

scholarly journals Thinner Sea Ice Contribution to the Remarkable Polynya Formation North of Greenland in August 2018

2021 ◽  
Author(s):  
Xiaoyi Shen ◽  
Chang-Qing Ke ◽  
Bin Cheng ◽  
Wentao Xia ◽  
Mengmeng Li ◽  
...  
Keyword(s):  
Sea Ice ◽  
Ice Cover ◽  
Reanalysis Data ◽  
Mean Value ◽  
Ocean Model ◽  
North Coast ◽  
Average Value ◽  
The North ◽  
Wind Sea ◽  
The One

AbstractIn August 2018, a remarkable polynya was observed off the north coast of Greenland, a perennial ice zone where thick sea ice cover persists. In order to investigate the formation process of this polynya, satellite observations, a coupled ice-ocean model, ocean profiling data, and atmosphere reanalysis data were applied. We found that the thinnest sea ice cover in August since 1978 (mean value of 1.1 m, compared to the average value of 2.8 m during 1978–2017) and the modest southerly wind caused by a positive North Atlantic Oscillation (mean value of 0.82, compared to the climatological value of −0.02) were responsible for the formation and maintenance of this polynya. The opening mechanism of this polynya differs from the one formed in February 2018 in the same area caused by persistent anomalously high wind. Sea ice drift patterns have become more responsive to the atmospheric forcing due to thinning of sea ice cover in this region.

Resistance of a Ship Undergoing Oscillatory Motion

2010 ◽  
Vol 54 (02) ◽  
pp. 120-132
Author(s):  
Lawrence J. Doctors ◽  
Alexander H. Day ◽  
David Clelland
Keyword(s):  
Finite Depth ◽  
Mean Value ◽  
Wave Resistance ◽  
General Effect ◽  
Towing Tank ◽  
Ship Model ◽  
Average Value ◽  
Unsteady Effects ◽  
Oscillatory Cycle ◽  
Resistance Tests

In this paper, we describe extensions to the research of Doctors et al. (Doctors, L. J., Day, A. H., and Clelland, D., 2008, Unsteady effects during resistance tests on a ship model in a towing tank, Journal of Ship Research, 52, 4, 263–273) and Day et al. (Day, A. H., Clelland, D., and Doctors, L. J., 2009, Unsteady finite-depth effects during resistance tests in a towing tank, Journal of Marine Science and Technology, 14, 3, 387–397) in which the oscillations in the wave resistance during the constant-velocity phase of a towing-tank resistance test on a ship model were measured and predicted, in the cases of relatively deep and relatively shallow water. In the current study, the ship model was towed with a harmonic velocity component superimposed on the usual constant forward velocity. This work constitutes a first step in the understanding of the unsteady hydrodynamics of a racing shell (rowing boat). We show here that the unsteady wave resistance varies considerably from the traditional (steady) average value. Indeed, the wave resistance is frequently negative during part of the oscillatory cycle. However, the general effect is an increase in the temporal mean value of the wave resistance; this suggests that every effort should be made to reduce the unsteadiness of the motion. We also demonstrate that the unsteady wave-resistance theory provides an excellent prediction of the measured effects summarized here. These predictions are often within a few percent of the measured values of the resistance.

scholarly journals Mandibular Morphology Differences Between Edentulous And Dentate Assessed By Panoramic Radiographs

2017 ◽  
Vol 16 (2) ◽  
Author(s):  
Lidya Irani Nainggolan ◽  
Aude Layakni Girsang
Keyword(s):  
Panoramic Radiography ◽  
Mechanical Stimulus ◽  
Mean Value ◽  
Notch Depth ◽  
Cross Sectional ◽  
Gonial Angle ◽  
Average Value ◽  
Mandibular Morphology ◽  
Edentulous Patients ◽  
Ramus Height

Introduction: Facial profile can be influenced by edentulous condition that can change mandibular morphology that can affect mastication, digestion and psychosocial life. Edentulism causes absence of occlusal mechanical stimulus, decrease the activity of mastication muscles and increase mandibular bone resorption. These changes can be assessed using panoramic radiography by looking at the vertical dimension of the head of the condyle and its shape, ramus, and the angle of the mandible. The aim of the study was to assess the mean value and differences of mandibular morphology in edentulous and dentate patients using panoramic radiography. Materials and Methods: This was an analytical study with cross-sectional approach using purposive sampling methods. 50 dentate and edentulous patients who came to Dentistry Hospital of University of Sumatera Utara were used as sample. Data analysis was done using Independent T test and MannWhitney test. Results: Results showed that the average value of gonial angle, ramus height, condylar height, antegonial notch depth and ramus notch depth in edentulous patients were 125,38 ± 9,51; 35.98mm ± 4.26; 5.58mm ± 0.90; 2.11mm ± 1.04; and 2.73mm ± 0, 88, and the results showed that the average value of mandibular morphology in dentate patients were 123.34 ± 7.07; 38.15mm ± 3.23; 6.95mm ± 1.25; 1.41mm ± 0.77; and 2.15mm ± 0.59. Conclusion(s): There were significant differences in the values of ramus height, condylar height, antegonial notch depth, and ramus notch depth. Difference was also found in gonial angle value, but was not statistically significant.

scholarly journals Pengembangan LKPD Tema Tanah Airku Sub Tema Kota Palembang untuk Anak Kelompok B

2019 ◽  
Vol 1 (2) ◽  
pp. 129-141
Author(s):  
Gustiana Yuantini ◽  
Hasmalena Hasmalena ◽  
Syafdaningsih Syafdaningsih
Keyword(s):  
Small Group ◽  
Mean Value ◽  
Average Score ◽  
Self Evaluation ◽  
Average Value ◽  
Expert Review ◽  
Group Evaluation ◽  
Observation Methods ◽  
Evaluation Stage ◽  
Group B

This research aims to develop valid and practical student worksheet. Subjects in this research were B2 and B3 groups in state kindergarten of Pembina 2 Palembang. The model developed in this development was Rowntree consisting of One to one evaluation and small group evaluation. It was aimed to see the practicality and it used the Tessmer evaluation stage which consisted of self evaluation, expert review. Data collection techniques used in this research were interview, walkthrough and observation methods. According to the results of the research, it showed that the validity of the material and design obtained an average value of 3.77 in very valid categories. Student worksheet practicality test in terms of observations with a mean value of 95% in very practical category. The small group evaluation stage obtained an average score of 92% in the very practical category. Questionnaire result was 97% in valid category. From the result, it can be concluded that student worksheet theme of my homeland and sub-theme of Palembang city for group B children is valid and practical. It is also worth to use as learning student worksheet with Theme of my homeland

scholarly journals Pengaruh Model Pembelajaran Problem Based Learning pada Materi Hukum-Hukum Dasar Kimia terhadap Hasil Belajar Siswa Kelas X MAN 2 Model Palu

2018 ◽  
Vol 7 (3) ◽  
pp. 102
Author(s):  
Tri Sulistiyawati Lamalat ◽  
Supriadi Supriadi ◽  
Siti Nuryanti
Keyword(s):  
Statistical Analysis ◽  
Learning Outcomes ◽  
Problem Based Learning ◽  
Sampling Technique ◽  
Learning Model ◽  
Mean Value ◽  
Control Group ◽  
Control Group Design ◽  
Average Value ◽  
Quasi Experimental

Research on the effect of the problem-based learning model in the basic laws of chemistry on student’s learning outcomes in class X MAN 2 Model Palu has been done. This study aimed to determine the effect of the application of the problem-based learning model in the basic laws of chemistry on student’s learning outcomes in class X MAN 2 Model Palu. The type of research was a quasi-experimental study non-randomized design with pretest-posttest control group design. The sample was conducted with a purposive sampling technique. The study sample was students in class X MIA 6 as an experimental group (n = 22) and students in class X MIA 3 as a control group (n = 22). The data testing of students' learning outcomes used a non-parametric statistical analysis, the analysis of Mann-Whitney U-Test. The research results indicated that the mean value of the experiment class was high compared to the control class, 22.61 >18.39. The statistical analysis obtained that sig. 2-tailed (0,032) ˂ 0.05 and Zcalculation (-2.149) ˂ Ztable (-1.96). The average value of the experiment class was 82.95 while the average value of the control class was 73.64. So it can be concluded that there is the effect of applying the problem-based learning model in the basic laws of chemistry on student’s learning outcomes. 

scholarly journals Effects of the Dictogloss Method in Teaching Listening Skills to Students

2019 ◽  
Vol 8 (2) ◽  
pp. 69
Author(s):  
Muhaiminah Akib ◽  
Dian Saputra
Keyword(s):  
Mean Value ◽  
Control Group ◽  
Test Results ◽  
Listening Skills ◽  
Initial Test ◽  
Final Test ◽  
Learning Skills ◽  
Average Value ◽  
Quasi Experimental ◽  
Experimental Group

The purpose of this study was to investigate the effect of the dictogloss method in teaching listening to students' listening skills. This research was designed as a quasi-experimental. This study aims to investigate whether a material or treatment yields a different outcome for participants. There are two classes in this study, namely the experimental class (which is a sample to be treated with the dictogloss method) and the control class (using a method other than dictogloss). The results of this study are the results of data analysis showing that the results of learning skills in listening to the experimental group obtained the average value for the initial test of 60.33 and 71 for the final test score. While the control group using conventional methods has a mean value for the initial test of 60.1 and 70 for the final test. T test results also indicate that the significance value is 0,000. The significance value states smaller 0.05, it can be stated that Ha is accepted and Ho is rejected, which means that there is an influence of the dictogloss method in improving listening skills in students

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