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Mineralogical and Geochemical Characterisation of Rocks and Geothermal Fluids in the Olkaria Geothermal Field, Kenya: Potential for Epithermal Deposits

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International Journal of Geosciences 2024年第12期15卷 1113-1133页

作者： Christine Jerotich Kiptoo Isaac Kanda Nicholas Mariita patrick kariuki patrick Kirita Gevera Geothermal Energy Training Institute (GeTRI) Dedan Kimathi University of Technology Nyeri Kenya Geothermal Development Company (GDC) Nakuru Kenya Department of Civil Engineering University of South Africa (Florida Science Campus) Johannesburg South Africa

The Kenyan Olkaria geothermal field has incredibly high geothermal potential in the East African Rift, the Kenyan Rift Valley. While the Olkaria geothermal area has been primarily attributed to electricity generation and direct uses, this research investigates the potential of epithermal deposits in the geothermal systems with particular interests in base metals (Zn, Pb, and Fe) and alkali metals (Li, Na, K) in geothermal rocks and fluids. The study employed geochemical, geological, and well-logging analyses to characterise and assess the conditions in the geothermal system suitable for forming and depositing epithermal minerals. Rock cuttings and fluid samples were collected from geothermal wells, fumaroles, and hot springs. Findings indicate that the mineralisation in the Olkaria wells occurs in microveins and disseminations in the rock matrix, majorly sulfides, and oxides in hydrothermal alteration zones. The reported Zn, Pb, and Fe mineralisation mainly relates to low sulphidation type from the characterised sulphur metal complexes and oxides. Fluid samples recorded the metals as follows: Fe (0.12 - 3.9 ppm), Zn (4.21 - 5.23 ppm), Pb (1.55 - 2.04 ppm), and lithium concentrations at ≤ 3 ppm, which is lower than extractible values in geothermal brines in the Salton Sea and geothermal fields of Europe. The economic characterisation of rocks and fluid samples in our area indicates that the concentration of base and alkali metals has not yielded economically viable values compared to other geothermal systems with economic grades. Detailed studies are recommended to quantify mineralisation in Olkaria geothermal fields and their extractability for sustainable management of the geothermal resource.

关键词： East Africa Rift System (EARS) Epithermal Deposits Geochemistry Geothermal Systems

Structural Controls Analysis and Its Correlation with Geothermal Occurrence at Barrier Volcanic Complex (BVC), Turkana, Kenya

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International Journal of Geosciences 2024年第3期15卷 231-245页

作者： Philip Lomorukai Emekwi Nicholas O. Mariita patrick Chege kariuki Geothermal Training and Research Institute (GeTRI) Dedan Kimathi University of Technology Nyeri Kenya

Geothermal is a clean energy source that is freely available in the subsurface. The exploitation of this vital resource needs intensive exploration in order to identify and quantify its occurrence. The three parameters considered when assessing the viability of a geothermal system include;heat source, fractures and fluids. Geological structures are important in transportation of fluids to and from the heat source aiding in recharge of the geothermal system and enhancing productivity. Remote sensing method was applied in mapping the structures at Barrier Volcanic Complex (BVC) by using hill shading technique which utilized four illumination angles of the sun (azimuth) i.e. 45°, 90°, 150°, and 315°, constant elevation of 45° and exaggeration of 10. The data used was Shuttle Radar Topographic Mission (SRTM) Satellite Imagery. ArcGIS Software was used for lineaments delineation and density mapping, PCI Geomatica was used to generate major faults, while Georose and Rockworks 17 were used to generate the rose diagrams. Geological structural analysis was done by delineating lineaments, determining the density distribution of lineaments and finally determining the structural trends of lineaments. The generated major faults in the area and the location of the occurrence of surface manifestations were compared with the generated lineaments. A total of 260 lineaments were generated whereby at 45° there was a total of 60 lineaments, at 90° 95 lineaments, at 150° 61 lineaments, and at 315° 44 lineaments. The results of structural analysis in the area as shown by the rose diagrams indicate an NNE-SSW and N-S trending of structures. In conclusion, the study area is highly fractured as indicated by the presence of numerous lineaments. These lineaments provide good recharge to the geothermal system and enhance the geothermal reservoir in the area.

关键词： Geothermal Resource Lineaments Lineaments Density Structural Controls

Groundwater Resource Mapping through the Integration of Geology, Remote Sensing, Geographical Information Systems and Borehole Data in Arid-Subarid Lands at Turkana South Sub-County, Kenya

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Journal of Geoscience and Environment Protection 2019年第12期7卷 53-72页

作者： Daniel Nyaberi Justus Barongo patrick kariuki George Ogendi Evans Basweti Kisii University Kisii Kenya

The integrated approach of various techniques which historically have been used independently is key to successful exploration, development, exploitation and management of the groundwater resources. The integration of Remote Sensing (RS), Geographical Information Systems (GIS) and Borehole data has been used in the study area to assess their applicability in groundwater investigation. The area of study lies in the arid and semi-arid lands (ASALs) where principally remote sensing data has been used in extraction of various thematic maps (lithology, lineament, drainage density, and Digital Elevation Model Maps) for groundwater assessment. The GIS platform was used in integrating the RS data and data of productive boreholes. The lineaments generated through remote sensing agree well with structural geology of the area, where high density lineament points overlays the points of intense faulting. Lineaments found in the area correlate well with fault zones, fractures, and lithological contrasts as supported by geological map and structural map. Weathering, faulting and fracturing of the rocks mean a possible increase or a reduction in specific capacities as observed in productive boreholes in sedimentary rocks or igneous/basaltic rocks of the area. Similarly, it is noted that the degree of faulting affects the degree of radius of influence of a borehole in a particular area. These analyses show that groundwater potential within the Sub-County varies spatially with high dependency on geological structures in the basement region and more on geology within the volcanic and younger sediments.

关键词： Arid-Subarid Groundwater GIS Remote Sensing Borehole Data Integration

Socioeconomic Determinants of Farmers’ Vulnerability to Climate Variability and Extreme Events in Kitui County, Kenya

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American Journal of Climate Change 2024年第4期13卷 647-663页

作者： Evelyn J. Mutunga Charles K. Ndungu Moses Mwangi patrick C. kariuki Department of Environmental Science and Land Resources Management South Eastern Kenya University Kitui Kenya Department of Hydrology and Aquatic Sciences South Eastern Kenya University Kitui Kenya Geothermal Energy Training and Research Institute Dedan Kimathi University of Technology Nyeri Kenya

A field survey was carried out to model farmers’ vulnerability to climate variability and extreme events in selected agroecological zones in Kitui County. The indicator approach was used to calculate the overall household vulnerability index, where Principal Component Analysis (PCA) was used to allocate weights to indicators of exposure, sensitivity and adaptive capacity. Multinomial logistic regression was run in Stata to model the influence of socioeconomic characteristics on farmers’ vulnerability levels. The study established that different socioeconomic characteristics of households had a varying influence on the households’ vulnerability levels. Proximity to the Market and the arid agroecological zone significantly reduced the probability of a household belonging to the low and moderate vulnerability categories. On the other hand, the education level and the semi-humid zone significantly increased the odds of a household belonging to the low vulnerability category. Further, access to credit facilities and the semi-humid agroecological zone significantly increased the odds of a household belonging to the moderate vulnerability category. The study thus recommends that policy interventions should target specific socioeconomic characteristics that influence households’ vulnerability to climate variability and extreme events.

关键词： Vulnerability Index Principal Component Analysis Multinomial Logistic Regression Households

Mapping of Groundwater through the Integration of Remote Sensing and Vertical Electrical Sounding in ASALs: A Case Study of Turkana South Sub-County, Kenya

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Journal of Geoscience and Environment Protection 2019年第11期7卷 229-243页

作者： Daniel Mogaka Nyaberi Evans Basweti Justus Obiko Barongo George Mokua Ogendi patrick Chege kariuki Department of Natural Resources and Environmental Science Kisii University Kisii Kenya Department of Geology University of Nairobi Nairobi Kenya Department of Geological Sciences South Eastern Kenya University Kitui Kenya

Turkana South Sub-County falls in the arid and semi-arid lands of Kenya, which are characterized temperatures of 20°C to 41°C with an average of 30.5°C and precipitation in the range of 52 mm to 480 mm per year. The area has limited availability of water resources. The area has a land surface of 18,000 km2 and lies between Longitudes 35°10'00" and 36°45'00" East and between Latitudes 1°0'00" and 3°0'00" North. The study area faces immense difficulties in trying to meet its water requirements for her rapidly increasing populace, livestock needs and other developmental programmes. Surface water in the area is becoming unobtainable, thus the choice of groundwater exploitation. Indeed with the snowballing demand necessitated by energy, agricultural and livestock production needs in this area, there is an appeal into investigation for groundwater in this greatly remote and extensive area. Thus, the success in the exploration, development and management of groundwater in such a large area calls for such methods that can easily be used to zero down to exploitable targets. Given the expansiveness of the study area, remote sensing (RS) has been used to map lineaments which in turn have been used to deduce faulting affecting the geology of the area. The mapping by RS helped in identifying weathered zones, the fracture systems and fault zones sign of deeper weathered zones which are interpreted to be potential areas since mainly water is stored within fractures and the weathered zones in subterranean and in hard rocks. In the field topographic expressions of faults and fractures which include;joints, fractures, scarps, river channels and slope breaks were mapped and it was observed that there was a comparison of the features to the coincidence raster and aspect interpreted lineaments. The earmarked points were later investigated using vertical electrical sounding (VES) to establish their feasibility for groundwater availability and extraction. The i

关键词： Groundwater Assessment Remote Sensing Lineaments VES

An Inventory of the Above Ground Biomass in the Mau Forest Ecosystem,Kenya

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Open Journal of Ecology 2014年第10期4卷 619-627页

作者： Mwangi James Kinyanjui Petri Latva-Kayra Prasad Sah Bhuwneshwar patrick kariuki Alfred Gichu Kepha Wamichwe Department of Resource Surveys and Remote Sensing NairobiKenya Arbonaut Oy Ltd. HelsinkiFinland PASCO Corporation TokyoJapan Kenya Forest Service NairobiKenya Natural Resource Information&Technology Ltd. NairobiKenya

Biomass assessment of the Mau Forest Ecosystem (MFE) was done as part of Kenya’s greenhouse gas inventory. Trans Mara and Mount Londiani forest blocks representing extremes of vegetation types in the MFE were selected for ground data. Based on canopy closure, four forest strata were identified as very dense, moderately dense, open and bamboo. In each stratum, 5 clusters each with 4 plots measuring 30 m × 30 m were located. Big trees (D1.3 ≥ 10 cm) were measured per species for diameter at breast height (D1.3) in the whole plot while height was measured for every 5th tree. Poles (10 cm > D1.3 ≤ 5) were measured for D1.3 in a 10 × 10 m concentric sub plot. Saplings (5 cm > D1.3;ht ≥ 1.5 m) and seedlings (ht < 1.5 m) were enumerated per species within 5 × 5 m and 2 × 2 m concentric sub plots, respectively. Data were recorded in a Personal Digital Assistant (PDA) and quality checked with Open Foris Collect software. Allometric equations that have been used for similar vegetation in Kenya were used to relate D1.3 and height with biomass. The tree data were uploaded to ArboWebForest (AWF) cloud-service and using the AWF-SIMO calculation tool, average values of diameter, height, and biomass were calculated for each plot. The data were generalised to cover all areas for each block using the Sparse Bayesian linear regression process on the vegetation characteristics with 10 m resolution ALOS-AVNIR-2 images of the MFE. ANOVA was used to compare biomass generated from several allometric equations. Results show that the average biomass of the MFE was 236 Mg·ha1. Degradation that converts dense forests into open and moderately dense forests contributed to a biomass loss of 228 Mg·ha1 and 194 Mg·ha1 respectively. Four allometric equations gave no significant difference (P < 0.05) in biomass for the 80 plots implying that costly processes of developing new equations may not improve accuracy. The study offers a learning lesson in Kenya’s forest inventory processes and the biomass v

关键词： Forest Biomass Inventory

Human endogenous retrovirus type-W and multiple sclerosis–related smoldering neuroinflammation

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Neural Regeneration Research 2025年第3期20卷 813-814页

作者： Joel Gruchot Laura Reiche Andrew Chan Robert Hoepner patrick Küry Department of Neurology Medical Faculty and University Hospital DüsseldorfHeinrich Heine University DüsseldorfDüsseldorfGermany Department of Neurology InselspitalBern University Hospital and University of BernBernSwitzerland

Introduction to human endogenous retrovirus type-W(HERV-W): Genomic inheritance from the past includes retroviral sequences that have been stably incorporated into our genomes and account for up to 8% of human DNA.

关键词： endogenous inflammation Human

Significant Advancements in UAV Technology for Reliable Oil and Gas Pipeline Monitoring

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Computer Modeling in Engineering & Sciences 2025年第2期142卷 1155-1197页

作者： Ibrahim Akinjobi Aromoye Hai Hiung Lo patrick Sebastian Ghulam E Mustafa Abro Shehu Lukman Ayinla Department of Electrical and Electronics Engineering Universiti Teknologi PETRONASSeri IskandarPerak32610Malaysia Interdisciplinary Research Centre for Aviation and Space Exploration(IRC-ASE) King Fahd University of Petroleum and Minerals(KFUPM)Dhahran31261Saudi Arabia Department of Computer Engineering University of IlorinIlorin240003Nigeria

Unmanned aerial vehicles(UAVs)technology is rapidly advancing,offering innovative solutions for various industries,including the critical task of oil and gas pipeline ***,the limited flight time of conventional UAVs presents a significant challenge to comprehensive and continuous monitoring,which is crucial for maintaining the integrity of pipeline *** review paper evaluates methods for extending UAV flight endurance,focusing on their potential application in pipeline *** an extensive literature review,this study identifies the latest advancements in UAV technology,evaluates their effectiveness,and highlights the existing gaps in achieving prolonged flight *** techniques,including artificial intelligence(AI),machine learning(ML),and deep learning(DL),are reviewed for their roles in pipeline ***,DL algorithms like You Only Look Once(YOLO)are explored for autonomous flight in UAV-based inspections,real-time defect detection,such as cracks,corrosion,and leaks,enhancing reliability and accuracy.A vital aspect of this research is the proposed deployment of a hybrid drone design combining lighter-than-air(LTA)and heavier-than-air(HTA)principles,achieving a balance of endurance and *** vehicles utilize buoyancy to reduce energy consumption,thereby extending flight *** paper details the methodology for designing LTA vehicles,presenting an analysis of design parameters that align with the requirements for effective pipeline *** ongoing work is currently at Technology Readiness Level(TRL)4,where key components have been validated in laboratory conditions,with fabrication and flight testing planned for the next *** design analysis indicates that LTA configurations could offer significant advantages in flight endurance compared to traditional UAV *** findings lay the groundwork for future fabrication and testing phases,which will be critical

关键词： Airship vehicle UAV technology endurance enhancement lighter-than-air vehicle pipeline monitor-ing sustainable infrastructure drones

Paleomapping:Creating testable visual hypotheses of ancient worlds

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Journal of Palaeogeography 2025年第01期14卷 91-104页

作者： Holger Petermann Annaka M.Clement patrick M.Sullivan Hannah M.Bonner James W.Hagadorn Department of Earth and Space Sciences Denver Museum of Nature & Science Colorado School of Mines Department of Geology and Geologic Engineering Division of Water Quality Utah Department of Environmental Quality

The story of the Earth's changing landscapes is often told through paleogeographic maps. These images are some of the most accessible and widely used illustrations in the Earth sciences. However, no formal procedure for the creation of photorealistic paleomaps(i.e., paleosatellite images) exists. Using an example from the Late Jurassic of the Rocky Mountain region, we present a method for making paleoenvironmental and paleosatellite maps that is scalable, reproducible, testable, and incorporates peer review. The process includes a literature review followed by data-visualization, paleoenvironmental interpretation, peer-review,iterative revisions, and the creation of a false contour map and color gradient used to render a paleosatellite image. Paleosatellite images are photorealistic versions of paleoenvironmental maps that incorporate global climatic and tectonic information as well as principles of actualism; they can be made through comparison to analogous modern landscapes. An important component of this process is that the data maps that ground this paleomapping process allow evaluation of where paleoenvironmental interpretations are wellsupported by outcrop and subsurface data, and where such visualization is highly interpretive-often because of lack of available rocks or studies in a given area. As such, our paleoenvironmental maps and paleosatellite images are testable pictorial hypotheses. By outlining a procedure that produces referenced,data-rich, and visually realistic maps, we hope to demystify the paleoenvironmental map-making process and improve accessibility of paleomaps for the broader geoscience community. Where resources and complementary data are available, such maps also have potential for georeferencing and integration with larger continent-scale paleogeographic maps.

关键词： Ancient landscapes Cartography Paleogeography Paleoenvironments Jurassic