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Sustainability and Conceptual Groundwater Hydraulic Models of Basement Aquifers

Abstract

Groundwater flow of the basement terrains of the Ibarapa region was studied by carrying out pumping test and measurement of borehole inventory. The view was to identify the associated aquifer systems from the time-drawdown curves, quantify the estimable hydraulic properties and develop hypothetical models for the understanding of the groundwater flow in the area underlain by diverse crystalline bedrocks. Three aquifer types were identified namely, dual, leaky and regolith. The yield of groundwater in dual and leaky aquifers that dominated terrains underlain by amphibolite and gneisses was sustainable, but the discharge of regolith aquifers mainly associated with migmatite and granite terrains declined at late pumping stage. The transmissivities of the dual and leaky aquifers were between 2.02 and 11.65 m2/day, while those of regolith aquifers were mostly less than 1.00 m2/day. The average aquifer transmissivities in m2/day by bedrocks were: 6.85, 2.57, 0.76 and 1.72, correspondingly. The inter-relationships between transmissivities and groundwater discharge showed diverse aquifer representations, from sustainable high-yielding to unsustainable low-yielding types. Conscientious effort is, therefore, required for well construction in the area.

Open access
Photovoltaic Solar Energy: Is It Applicable in Brazil? –A Review Applied to Brazilian Case

Abstract

The photovoltaic technologies have been developed year by year in different countries; however, there are some countries where this kind of energy is being born, such as the Brazilian case. In this paper, some important parameters are analysed and applied to different solar cell materials, identifying that if the fossil fuels were substituted by solar cells, it would reduce the CO2 emissions by 93.2%. In addition, it is shown that the efficiency of solar cells is not as farther as it could be thought from coal thermoelectrical plants in Brazil and the cost of energy using solar cells could be as good as these thermoelectrical plants. Finally, the potentiality of Brazilian territory to implant this technology is presented, identifying that with the use of 0.2% of the territory, the energy demand could be supplied.

Open access
Electrical Resistivity Tomography for Sustainable Groundwater Development in a Complex Geological Area

Abstract

Electrical resistivity tomography (ERT) was used for delineating significant subsurface hydrogeological features for sustainable groundwater development in Etioro-Akoko area, Southwestern Nigeria. This study was necessitated by challenges posed on groundwater supplies from wells and boreholes in Etioro-Akoko and the neighbouring fast growing towns and villages. Field data were acquired over the area with ABEM Lund Resistivity Imaging System and were subsequently processed and inverted through RES2DINVx64 software. Results showed four distinct subsurface layers: topsoil, weathered layer, fractured bedrock and fresh bedrock (basal unit). Localised bedrock depressions occasioned by fracturing and deep weathering of less stable bedrock minerals were delineated with resistivity and thickness values ranging from 50 to 650 Ωm and 12 to > 25 m, respectively. The localised depressions mirrored uneven bedrock topography and served as the preferential groundwater storage and hydrogeological zones in the area. The two hydrogeological zones significant for groundwater development included overburden-dependent aquifers and fractured dependent bedrock aquifers. It was, therefore, concluded that groundwater storage potential was depended on hydrogeological zones particularly at major localised bedrock depressions where fractures and groundwater recharges/discharges were evident. Wells and boreholes were proposed at bedrock depressions with thickness value not less than 12 and > 25 m, respectively, for enhanced groundwater sustainability and quality assurance in the area.

Open access
Contribution to Understanding of Ore Fluids in the Zletovo Mine Based on Fluid Inclusion Data

Abstract

The Zletovo is lead–zinc (Pb–Zn) deposit, adjacent to the Plavica volcanic centre (R. Macedonia) with high-sulphidation and porphyry mineralisation. The analysis of fluid inclusions showed homogenisation temperatures in the range 335–145°C, which reflects phases of pulsation of hydrothermal solutions and defined into four groups from the lowest to the highest temperatures. The frequency of the homogenisation temperatures ranged from 265 to 125°C and with the most dominant from 245 to 225°C, from 225 to 205°C and from 145 to 125°C. Also, it was confirmed that hydrothermal ore-bearing solutions were defined as Na-Cl-type with range from 4.4 to 8.6 wt% NaCl equivalent. The latest stage salinities ranged from 3 to 12 wt% NaCl equivalent, where those from 10 to 12 wt% and from 6 to 8 wt% NaCl equivalent, prevailed. This suggests that hydrothermal solutions within analysed quartz grains were at final mineralizing phase. Density of fluid inclusions ranged from 0.7 to 0.95 g/cm3. Calculated pressures and paleo-depths of mineralisation ranged from 14 to 130 bar and from 0.6 to 0.8 km.

Open access
Estimation of Magnetic Contact Location and Depth of Magnetic Sources in a Sedimentary Formation

Abstract

The aeromagnetic data of Idogo, Southwestern Nigeria, have been used to study the lithology and to determine the magnetic source parameters within Idogo and its environs. Idogo lies between latitudes 6°30′N and 7°00′N and between longitudes 2°30′E and 3°00′E. The magnetic anomaly map, the regional geology, the analytic signal and the local wavenumber were used to identify the nature and depth of the magnetic sources in the region. Data enhancement was carried out to delineate the residual features relative to the strong regional gradients and intense anomalies due to the basin features. The estimated basement depth using the horizontal gradient method revealed depths ranging between 0.55 km and 2.49 km, while the analytic signal amplitude and local wavenumber methods estimated depth to the magnetic sources to range from 0.57 km to 4.22 km and 0.96 km to 2.43 km, respectively. Depth computations suggested the presence of both shallow and deep sources. The total magnetic intensity values ranged from 3.1 nT to 108.3 nT. The area shows magnetic closures of various sizes in different parts of the area trending West, with prominence at the centre and distributed East–West.

Open access
Geotechnical Terrain Models and Types of Instabilities in the Durmitor Flysch Complex

Abstract

The Durmitor flysch complex represents a specific formation both in lithological and engineering geological sense. In the engineering geological sense this lithological formation is characterized by anisotropic and heterogeneous geotechnical properties, which depend on the dominant members within each individual package, as well as their spatial position.The Durmitor flysch complex consists of five superposition bed packages, which are mutually substantially different in their lithological, hydrogeological and geotechnical properties. For the first time in geological literature, this paper distinguishes five types of terrain construction within the Durmitor flysch complex. Contemporary geodynamic processes and their character within the flysch formation are defined. Particular emphasis is put on landslides, which represent a contemporary geodynamic phenomenon with certain specificities.

Open access
High resolution airborne radiometric and magnetic studies of ilesha and its environs, southwestern Nigeria

Abstract

The study of the nature of distribution of natural radioelements in Ilesha and its environs with its geological structure has been studied using aeroradiometric data. Aeromagnetic data have also been subjected to three automated gradient techniques to delineate the sub-surface structure of the study area. From the study, it can be found that maximum values of “eU” (ppm) and “eTh” (ppm) fall within the branded gneiss, whereas the maximum value of K (%) falls within porphyritic granite regions. eTh had the highest radioactive content. The environmental dose rate of Ilesha was between 0.1817 and 3.9296 msv/yr. Although there were extreme values, but the mean dose rate was 0.522 ± 0.310 msv/yr (within acceptable safe limit of 1.0 msv/yr). eU/K, eU/eTh and eTh/K ratios were analysed for enrichment or depletion of radioisotopes. eU/eTh >1 showed uranium depletion, while eTh >2 showed eTh enrichment. The magnetic intensity values ranged from -79.41 to 140.93 nT. The horizontal gradient method (HGM) and analytic signal amplitude (ASA) revealed that depth to magnetic sources ranged from 0.478 to 4.112 km and 0.348 to 2.551 km, respectively, whereas local wavenumber (LWN) depth ranged from 0.478 to 5.48 km, which overestimated those compared using HGM and ASA functions. The apparent susceptibility ranged from -0.00325 to 0.00323 SI, showing that ferromagnetic and diamagnetic mineral ranges control apparent susceptibility in Ilesha.

Open access
Investigation of Land Use Types on Physical and Chemical Properties of Soil in a Basement Terrain

Abstract

We assessed the effect of different land use types on the physical and chemical properties of soil. We analysed three cases. Nine soil samples were taken at different depths (0–10, 10–20 and 20–30 cm) from three locations, namely, sawmill, dumpsite and market. Analyses were carried out to determine the influences on the physical and chemical properties of the soil. All the land types had considerably high sand contents, with minor silt and clay. Available phosphorus and the exchangeable bases were significantly (p ≤ 0.05) affected by land use and soil depth. Moisture content (p ≤ 0.05) was significantly affected by land use, while bulk density (p ≤ 0.01) was significantly affected by soil depth. Soil organic matter and carbon were also generally low in all three locations. Consequently, ameliorative land management practices have to be adopted to prevent nutrient loss and land degradation.

Open access
New Method of Visibility Network and Statistical Pattern Network Recognition Usage in Terrain Surfaces

Abstract

Many problems in the analysis of natural terrain surface shapes and the construction of terrain maps to model them remain unsolved. Almost the whole process of thematic interpretation of aerospace information consists of a step-by-step grouping and further data conversion for the purpose of creating a completely definite, problematically oriented picture of the earth’s surface. In this article, we present application of a new method of drawing 3D visibility networks for pattern recognition and its application on terrain surfaces. For the determination of complexity of 3D surface terrain, we use fractal geometry method. We use algorithm for constructing the visibility network to analyse the topological property of networks used in complex terrain surfaces. Terrain models give a fast overview of a landscape and are often fascinating and overwhelmingly beautiful works by artists who invest all their interest and an immense amount of work and know-how, combined with a developed sense of the portrayed landscape, in creating them. At the end, we present modelling of terrain surfaces with topological properties of the visibility network in 3D space.

Open access
Decarburization of the Carbon Steel C45 During Annealing in Air

Abstract

In production it is necessary to achieve conditions that lead to the minimum decarburization of a steel product’s surfaces. In this study, the hypo-eutectoid carbon steel C45 was annealed in air in the temperature range T a = 600–1100 °C. The annealing times were between t a = ½ h and t a = 2 h. Different decarburizations occurred in different microstructures: ferrite–pearlite (T a = 600 °C and 700 °C, T a < AC1, no visible decarburization); ferrite–austenite (T a = 760 °C, AC1 < T a < AC3, visible decarburization); austenite at the beginning, ferrite– austenite after the incubation period (Ta = 850 °C, AC3 < T a < 912 °C, visible decarburization); and austenite (T a= 950 °C and 1100 °C, T a> 912 °C, visible decarburization and overheating of steel). The edges were more prone to decarburization and to overheating. Stress relieving, normalizing and annealing before quenching of the steel C45 can be carried out in air.

Open access