Extreme precipitation event is one of the most extensive and harmful meteorological disasters in China and even the world. Discussing the research situation of extreme precipitation under the background of climate change can grasp the research status and hot spots in this field from a macro perspective and provide a reference for in-depth understanding of the causes and trends of extreme precipitation. Since 1992, the research on extreme precipitation has been gradually carried out, so this study systematically counts and analyzes the scientific literature from the CNKI database from 1992 to 2022 by bibliometric. It shows that the frequency and intensity of extreme precipitation events increase in the China monsoon region, and the regional differences are obvious. It also has a great impact on agricultural production and vegetation coverage. In addition, in recent years, scholars have gradually carried out research on the relationship between extreme precipitation and atmospheric circulation, especially the relationship between the spatial and temporal characteristics of extreme precipitation and ENSO events, which has become a new research hotspot. It is suggested that future studies should comprehensively analyze various influencing factors, quantitatively analyze the impact of extreme precipitation on agricultural production and vegetation coverage, and put forward corresponding solutions.

The sedimentary facies exposed at Ogbunike Area belong to the Eocene Formation that made up the Anambra Basin. This research estimates the lithology, thickness, sedimentary succession, paleo-environment, reservoir quality and source area tectonics using geological mapping, petrography, grain size distribution and statistical analysis. Geological mapping shows that the section is approximately 27m thick and consists of sandstone, shale, siltstone and ironstone lithofacies. Granulometric analysis performed on selected samples shows that the sandstones are fine to medium grained (1.15 to 2.17 ϕ), moderately sorted (average 0.96 ϕ), fine skewed (average 0.16 ϕ) and leptokurtic (average 1.17 ϕ). Bivariate plot of skeweness against sorting and mean against sorting pinpoint a fluvial origin for the sandstones. The results from rose plot point to a bimodal-bipolar paleocurrent pattern while the bi-directional paleo-flow is in the northeastern-southwestern directions, which is an indication of tidal influence suggesting shore environment of deposition. Average permeability values derived from an empirical formula indicate good potential for reservoir rock. Deductions from field observations and petrographic analysis suggests that the sandstones are submature, with angular to sub-rounded quartz. The high percentage of goethite (average 30.4%) in the ferrugenized sandstones samples suggests an environment of low oxidation. Provenance and tectonic assessment reveal metamorphic source, humid climate, high relief, recycled orogeny, and derived primarily from Cameroon Basement Complex rocks.

The quality of groundwater depends on its physiochemical and microbial characteristics. This study is aimed at analyzing the physiochemical quality of groundwater and was carried out to assess the quality of groundwater samples obtained from five different boreholes within Eliozu (the study area). Total of seven major parameters were analyzed, they are potency of hydrogen (PH), electrical conductivity (EC), total dissolved solids (TDS), dissolved oxygen (DO), salinity and concentration of nitrate (NO3 ̅) and sulphate (SO ■(2-@4)). The results obtained were compared with standards prescribed by WHO, and showed that groundwater samples from these boreholes have PH value between 3.9 and 4.5 thus, are acidic and not suitable for drinking purposes, electrical conductivity value range from 50 to 208µΩ/cm, BH3 has low organic matter contaminants because its DO value is the least, TDS values is between 66 and 114.4mg/L which is within the limit desirable for drinking water supplies by WHO, salinity values range from 16.5 to 29.7mg/L, indicating that BH3 and BH5 have the most suitable water for drinking. The knowledge of this study can be applied in water resources management, hydrological activities and environmental and health management.

The research was conducted to open up further unexploited areas for gold mineral exploitation in part of Ilesha schist belt using geological and geophysical approach. Itagunmodi was used as a control in order to determine the mineralization potentials of Osu as a case study. Both towns lie within Ilesha schist Belt, Southwestern Nigeria. The residual magnetic anomaly map of the study area revealed magnetic low in the two towns indicating the presence of geological structure serving as a conduit for mineralizing fluid. Airborne radiometry interpretation showed that both Itagunmodi and Osu are affected by hydrothermal alteration which is an indication of gold mineralization. Overall interpretation of aeromagnetic and airborne radiometry datasets show that hydrothermal alteration generally is associated with fault and shear zones in the study area. The isolated altered zones were subjected to further investigation by using six samples of stream sediment collected along Imo (Itagunmodi) and Olomumu (Osu) stream channels for the grain size and geochemical analyses. The results from the grain size analysis revealed that sediments in both areas are fine to medium grained, poorly sorted, fine to moderately fine skewed, which implied fluvial depositional settings, and revealed that the occurrences of gold mineralization in both areas are of secondary deposits (alluvial). The concentration of identified trace elements as related to their threshold values revealed similar contents of low to high concentrations in both areas. The results of the analyses observed in Itagunmodi are similar to that of Osu, which implies that Osu is also mineralized will gold deposit.

This purpose of this study is to evaluate the petrophysical properties of hydrocarbon bearing reservoirs in ‘Glory Field’ onshore Niger Delta using well log data from five wells. Petrophysical properties evaluated are shale volume, thickness, porosity, net to gross, formation factor, irreducible water saturation, permeability, water saturation, hydrocarbon saturation and pay thickness. The well logs suite contained the following logs: gamma ray, resistivity, density and neutron logs. A total of three reservoir sands (Sand A, Sand B, and C) were identified and correlated across all five wells using Schlumberger Petrel Software. From the result, on average density, Vp/Vs ratio, AI, shale volume, net to gross ratio, net thickness, effective porosity, permeability, water saturation and hydrocarbon saturation values are 2.15g/cm3, 2.28, 5406.67gcm3ms-1, 26%, 74%, 66.99ft, 25%, 2331.14mD, 48% and 52% respectively for sand A reservoir, while 2.17 g/cm3, 2.05, 6117.38 gcm3ms-1,14%, 86%, 185.04 ft, 26%, 2359.88mD, 56% and 46% respectively for sand B reservoir, and 2.18g/cm3, 2.01, 6275.95gcm3ms-1, 14%, 86%, 197.52ft, 25%, 2121.27mD, 53% and 47% respectively for sand C reservoir. The results of this research revealed very good effective porosity (>20%), excellent reservoir permeability (>1500mD) and pay zone thicknesses exceeding 70ft which are sufficient for hydrocarbon production and field development.

This study petrologically and mechanically assesses and compares five of the seven stratigraphic units of the Sekondi Group comprising Elmina sandstone from Central region; Ajoa, Takoradi, Takoradi Harbour and Essipong shales from the Western region in Ghana. All the studied shales were detrital clastic sedimentary rocks observed to have angular, near rounded and elongated crystal habits which are randomly distributed within fine-grained clay minerals as cementing matrix. These characters were clearly observed in the Ajua shales than the others. Unlike the shales, no chlorite, organic materials or foliations were observed in the Elmina sandstone. Also, the most consisted minerals in the shales were the feldspars (K- and plagioclase) and quartz, whereby the K-feldspar dominated the other crystals in the sandstone. The finer texture of the shales may be inferred that the shales have undergone longer times and distances of transportation process. The UCS test carried out on the Elmina sandstone reveals it to be a weak rock with a strength value of 37.3 MPa whilst the Schmidt Hammer test carried out on the four shale rock samples define the shales to be delaminated with the average rebound value of zero (0) each. Both results confirm the megascopic and microscopic petrological results, since both revealed the occurrences of laminated sections within the rocks, and the fissile property of all the shales. It also proves megascopic observation of Elmina sandstone being the hardest of the rocks observed, although the sandstone is still relatively weak from the rock hardness classification.

Very low frequency electromagnetic (VLF-EM) survey was conducted along failed segments of some roads in Ota, southwest Nigeria to reveal the geologic dispositions of subsurface material underlying the road pavements. Geonics EM-16 VLF was employed for data acquisition across a total distance of about 2.6 km. Fourteen traverses were positioned along failed road segments with one control traverse arranged along stable road segments. Real and quadrature field data components were processed via Fraser and Karous-Hjelt filtering to suppress noise and enhance signal strength. Positive peaks of filtered real component on Fraser plots depict the presence of conductive subsurface materials. Good correlation exists between positive peaks on Fraser plots and conductive zones on 2-D current density at several lateral distances and depths across all the traverses. Delineated VLF anomalies represent weak zones that might pose serious threat to road stability. These conductive anomalies are presumably composed of clayey bodies (laterite/lateritic soil) in the subgrade soil used for road construction or unexcavated host materials in the subsurface. Changing volume of clayey materials under varying climatic conditions is a major cause of distress to engineering structures. Clayey materials by virtue of their pore characteristics (high porosity and low permeability) tends to undergo alternating series of expansion and contraction under different climatic conditions. These seasonal dispositions would eventually manifest as cracks and potholes on road pavements. Uneven distribution of different adjacent subsurface lithologies contributes to differential settlement, which is a possible catalyst of road failure.

The aim of this review is to gain insights of the geotechnical properties of lateritic soil that make it suitable to be used as a subbase material, and discuss the improvements done on the properties to further strengthen them. Several additives are reviewed for the lateritic soil stabilization, and fly ash is chosen to be the material of interest. This is so to answer the problem statement of would fly ash be a potential material for soil stabilization. Based on this review, it is understood that lateritic soil is commonly found in tropical and subtropical regions and is classified as sandy clay or silty clay. Studies also have shown that fly ash is potential to be used as a stabilizer in soil improvements. The presence of free lime may react with the silicates and aluminates, resulting to a long-term strength gain in soil. Class C fly ash contains more free lime that would lead to better strength gain in the earlier stage as compared to Class F fly ash. In addition to that, the particle size of the fly ash would also affect the improvement results, as smaller particle size allows more effective surface for the pozzolanic reaction to occur. The significance of this review is to show the potential of fly ash in improving lateritic soil, other than providing more evidence to encourage the incorporation of industrial waste in soil stabilization.

In the present work, we deal with the geomorphological features formed by karstification in the dolomite of the Drinjal Formation. The study area is located on the southeast wall of the Saddat Sirize iron mine, which is mostly covered by the sedimentary sequence of the Drinjal Formation. The geomorphological features have a direct effect on the slope stability, extraction of the orebody, etc., in a mining project. The aim of this study is to determine the effect of karst geomorphology on the mining project. For this purpose, fields methods were used to examine the dolomite of Drinjal formation. Dolomite in the study area has a variety of developed karstic geomorphological features such needle shape karrens, solution runnel karrens and cryclastic karrens, conical shape doline and Collapse dolines, Karstic cavity and Karst windows. karst geomorphology makes it highly susceptible to a variety of different geological hazards. These karstic geomorphologies can cause the instability of the Saddat Sirize iron mine wall.

Due to the occurrence of earth tremors which leads to the vibrations of foundations and perhaps failure of buildings and roads, it is therefore important to understand and have knowledge of the geomechanical soil properties for foundation design, assessment of risks and suggestion of mitigation plans in engineering structures and road construction. A total of 3 boreholes were drilled with the Standard Penetration Test (SPT) performed and Downhole Seismic Test (DST) carried out in the boreholes located within Assa to investigate the Geomechanical soil properties in the area. For the geophysical survey, the downhole seismic test was carried out to determine the P-wave and S-wave. The results were processed using the generalized reciprocal method (GRM) with the Seisimager program. The results of soil dynamic modulus (shear, young and bulk modulus) and Poisson ratio recorded from DST conducted in BH1, BH2 and BH3 ranges from 7300 KPa to 72390 KPa, 0.31 to 0.41 for the Poisson ratio. Meanwhile, soil static modulus and Poisson’s ratio recorded from SPT conducted in BH1, BH2 and BH3 ranges from 2520 to 44687.0 KPa, 0.20 to 0.55 for the Poisson ratio respectively. The results of this study have shown that there is a wide variation between geomechanical properties derived from geotechnical investigations (static properties) and geophysical investigations (dynamic properties). Based on depth trend analysis, the dynamic and static soil elastic properties all increases with depth. Generally, the dynamic soil properties were significantly higher than the static elastic properties. At shallow depths (<12.0 m), the difference between static and dynamic soil modulus was relatively small, but increased with increasing depth. Meanwhile, the difference between static and dynamic Poisson ratio was high at shallow depth and it decreased with increased depths where they almost overlap. Correlation between the derived static and dynamic properties all revealed positive correlation trends. The strength of the correlation was highest for young modulus (r=0.87) which was closely followed by the shear modulus (r=0.63). Meanwhile, Poisson ratio (r=0.40) and bulk modulus (r=0.23) revealed weak positive correlation trends. The regression models generated from this study were used to derive static elastic properties and compared with the static properties obtained from geotechnical investigation thereby deriving the equations Dynamic Shear Modulus = (1.4207 x Static Shear Modulus) + 5022, Dynamic Young Modulus = (2.0241 x static young modulus) + 5054.8, Dynamic Bulk Modulus = (1.7852 x static bulk modulus) + 15458, Dynamic Poisson’s ratio = (0.1812 x Static Poisson’s ratio) + 0.3154. The results showed fairly good match between static (geotechnical) shear modulus and static (from regression model) shear modulus, static (geotechnical) young modulus and static (from regression model) young modulus. There was no good match obtained for bulk modulus and Poisson ratio generally, except at shallow depth (< 12 m depth) where Poisson ratio revealed a good match.