Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Development and Validation of Regression Model via Machine Learning to Estimate Thermal Conductivity and Heat Flow Using Igneous Rocks from the Dikili-Bergama Geothermal Region, Western Anatolia(Pergamon-Elsevier Science Ltd, 2026) Ayzit, Tolga; Sahin, Onur Gungor; Erol, Selcuk; Baba, AlperThermal conductivity is a fundamental parameter that significantly influences the thermal regime of the lithosphere. It plays a crucial role in a variety of geological applications, including geothermal energy exploration, igneous system assessment, and tectonic modeling. In this study, a machine learning approach is used to predict the thermal conductivity of igneous rocks based on the composition of major oxides. A total of 488 samples from different regions of the world were analyzed. The thermal conductivity values ranged from 1.20 to 3.74 Wm(-1) K-1 and the mean value was 2.61 Wm(-1) K-1. The Random Forest (RF) algorithm was used, resulting in a high coefficient of determination (R-2 = 0.913 for training and R-2 = 0.794 for testing) and a root mean square error (RMSE) of 0.112 and 0.179, respectively. Significance analysis of the traits identified SiO2 (>40 %), Na2O (>15 %) and Al2O3 (>10 %) as the most influential predictors. The study presented results from the Western Anatolia region, where felsic rocks had the highest thermal conductivity (mean = 2.69 Wm(-)(1)K(-)(1)) compared to mafic (mean = 2.34 Wm(-)(1)K(-)(1)) and ultramafic rocks (mean = 2.39 Wm(-)(1)K(-)(1)). In addition, the study evaluated the predictive capabilities of machine learning models for the igneous rocks of the Dikili-Bergama region and compared the results with those of saturated models. Using these data, we calculated heat flow values of up to 400 mWm(-2) under saturated conditions in western Anatolia. These results highlight the value of integrating geochemical data with machine learning to improve geothermal resource exploration and lithospheric modeling.Book Part Citation - Scopus: 3High Radiogenic Granites of Western Anatolia for Egs: a Review(CRC Press, 2023) Chandrasekharam, Dornadula; Baba, Alper; Ayzit, TolgaTurkey has made remarkable progress in the hydrothermal sector by promoting both electricity generation and direct application. In terms of power generation, this country is the fourth top country in the world. Nearly 1 billion kWh of energy is being utilized to keep 150,000 homes warm in the winter. In addition, Turkey has huge amounts of uptapped energy in its high radiogenic granites in western Anatolia, spread over a cumulative area of 6,910 km2. The radioactive heat generated by these granites varies from 5 to 13 µW/m3. These granite plutons are located over a region with high heat flow values (120 mW/m2) and the Curie temperature isotherm in this region is located at a depth varying from 6 to 12 km. The heat flow values here are 50% higher than the world average. This thermal regime concurs well with the wet granite melting curve at a heat flow of 85 mW/m2. The entire thermal regime indicates a visco-elastic lower crustal layer in this region. Thus, these granites provide excellent sites for initiating Enhanced Geothermal Systems projects in Turkey. Earlier EGS projects in France and Australia gave power estimates of 79×106 kWh of electricity from 1km3 of such granite. With ongoing development in drilling technology, the classical concept of creating a fracture network is being replaced with loop technology that reduces minor seismic risks and also the cost of power. The most important additional advantage Turkey has is the high-temperature regime at shallow depth, unlike other countries where the granites are located at depths >5km. These factors cause the cost of power to fall below 6 euro cents per kWh. Besides the power and heat, the greatest advantage is the reduction in emissions and achieving UN sustainable development goals. A conservative estimate shows that these radiogenic granites of western Anatolia are capable of generating a minimum of 546×109 kWh of power. Energy from these granites can be utilized to generate freshwater using the desalination method. Earlier studies indicate that to produce 1 m3 of desalinated water, ~16 kWh of electrical energy are needed. The cost of fresh water generated using geothermal energy sources will be <1.5 euros per 1m3. Turkey can utilize the energy from granite for water and food security in the future. © 2024 selection and editorial matter, Dornadula Chandrasekharam and Alper Baba.Book Enhanced Geothermal Systems (egs): the Future Energy-Road Ahead(CRC Press, 2023) Chandrasekharam, Dornadula; Baba, AlperPeter Meisen, Past President, Global Energy Network Institute, asked in 1997, “What if there was an existing, viable technology, that when developed to its highest potential could increase everyone’s standard of living, cut fossil fuel demand and the resultant pollution?" After 23 years of sustained effort by the global scientific community, this is becoming a reality. The technology to extract heat from granite has been revolutionized in the last few years. The classical method of creating fracture networks by hydrofracturing is being replaced by a closed-loop method where fluids are not in contact with the hot granite. Supercritical CO2 is replacing water as a circulating fluid. Certainly, the future energy road is going to be led by highly radiogenic granites. While hydrothermal sources are site-specific and have their limitations, EGS can be initiated anywhere on earth. EGS is removing all such obstacles and, in the future, will provide uninterrupted electricity for all. Energy-deficient countries can have surplus electricity; water-stressed countries can have a perennial freshwater supply; and countries can become food-secure and rise above poverty levels. Countries need not depend on energy imports and can independently evolve into carbon neutral or low carbon societies. The contributions made by experts will help researchers and investors to close the energy demand and supply gap in the very near future by tapping the unlimited energy of the Earth. Opportunities available for investors in Turkey are well documented with field, geophysical, and geochemical data and information on the energy generating capacity of the granite intrusive spread over a cumulative area of 6,910 km2 in western Anatolia. With the signing of the Global Geothermal Alliance (GGA) by several countries during the December 2015 CoP 21 (Conference of Parties) summit in Paris, countries are obliged to reduce CO2 emissions by increasing the footprint of renewable energy in the primary source mix. Information provided in this book will lead the way to establishing a clean energy future for millions of people for sustainable development and help to mitigate crises arising due to food, water, and energy shortage issues. Academic and research institutes will benefit to a large extent from the expertise of the top contributors in this book. This information provided in this book will help to lay the foundation for super-hot EGS research in future. © 2024 selection and editorial matter, Dornadula Chandrasekharam and Alper Baba.Book Part Citation - WoS: 7Citation - Scopus: 7Application of Geophysical Methods in Gulbahce Geothermal Site, Urla-Izmir, Western Anatolia(Taylor & Francis, 2014) Pamukçu, Oya; Gönenç, Tolga; Sındırgı, Petek; Baba, AlperThe western Anatolian region is considered to be one of the most tectonically active, rapidly deforming, and extending areas in the world (Bozkurt 2001; Dewey and Sengor 1979; Jackson and McKenzie 1984; S¸engör et al. 1985; Seyitog˘lu and Scott 1992) (Fig. 14.1). The region is rich with geothermal potential. Systematic geothermal exploration of the region began in 1960s. Medium-and high-temperature fields in and around Izmir city (Fig. 14.1) have been identified. There are a number of district heating systems, greenhouses, and spa complexes commercially utilizing geothermal energy in the region.Article Citation - WoS: 8Citation - Scopus: 8Estimation Groundwater Total Recharge and Discharge Using Gis-Integrated Water Level Fluctuation Method: a Case Study From the Alasehir Alluvial Aquifer Western Anatolia, Turkey(Springer Verlag, 2020) Şimşek, Celalettin; Demirkesen, Ali Can; Baba, Alper; Kumanlıoğlu, Ahmet; Durukan, Seda; Aksoy, Niyazi; Tayfur, GökmenThe estimation of groundwater recharge is an essential process for hydrogeological study. Realistic determination approach is crucial for assessing groundwater potential in an aquifer system and estimating of groundwater levels and/or changes in dry periods. Based on these matters, we employ a GIS-integrated groundwater level fluctuation method to determine the groundwater recharge for a hydrological period in the Alasehir alluvial aquifer (W. Anatolia). The method basically takes into account both increasing and decreasing of the groundwater levels due to the recharge and discharge mechanisms in the aquifer. In this study, 16 pumping and monitoring wells were drilled with a total depth of 1300 m, and water level data loggers were installed into the monitoring wells to determine the groundwater level changes. The spatial distribution of the monthly groundwater level change map was multiplied by the aquifer storage distribution map and then the accurate water volume is calculated by using the 3-D spatial analysis. According to our evaluation in the aquifer, positive volume change of the groundwater is 187 hm(3) in a year, which is considered as a recharge value of groundwater. It is concluded that the GIS-integrated water table fluctuation method gave rise to estimate the total recharge amount of the groundwater in the Alasehir aquifer. The total groundwater recharge indicates that total inflow in the aquifer from precipitation, leakage from surface water and irrigation waters. It can be stated that the recharge estimation of groundwater in a surficial aquifer, like the Alasehir aquifer, is fairly easy using the GIS-integrated water table fluctuation method.Article Citation - WoS: 2Citation - Scopus: 1Investigation of Groundwater Potential and Groundwater Pollution Risk Using the Multi-Criteria Method: a Case Study (the Alasehir Sub-Basin, Western Turkey)(Springer, 2020) Demirkesen, Ali Can; Budak, Seda; Şimşek, Celalettin; Baba, AlperDetermination of the groundwater potential (GWP) and groundwater pollution risk (GWPR) areas is a very important tool in the semi-arid regions in the world. Like many countries in the world, most of the major settlements in the cities of Turkey are located in permeable alluvial plains. Therefore, significant groundwater pollution is encountered in an alluvial plain containing settlements and industrial sites. This study focuses on the determination of the GWP and GWPR areas in the Alasehir sub-basin, which is one of the economically important districts of the Aegean region, located in the Gediz River basin in western Turkey. In this study, the GWP and the GWPR areas were identified and a GWP index map was generated. The GWP areas in the study basin were determined using different proxies as a multi-criteria method based on geographic information system (GIS) integrated with remote sensing (RS). The result of the study indicates that the most GWP locations in the basin are seen in the west and southeast of the study region. Based on these results, it is understood that the significant GWP and GWPR areas are near the big settlement districts such as Alasehir and Salihli. In particular, the 115-ha organized industrial zone located in the Salihli district is an important factor of the potential for consuming and contaminating water resources. This study method is so important for the selection of both city and industrial areas as well as for regional environmental planning in terms of the GWPR management.Conference Object Citation - WoS: 2Citation - Scopus: 2Arsenic in Groundwater in Western Anatolia, Turkey: a Review(University of Silesia Press, 2010) Gündüz, Orhan; Baba, Alper; Elpit, HandanOccurrence of arsenic (As) in groundwater has been a major problem worldwide for the last hundred years. Considering its toxic effects on human health, the presence of elevated levels of arsenic in groundwater resources used in drinking water supply has been an active research field throughout the world (Van Halem et al., 2009). In this regard, case studies from Bangla-desh, India, Nepal, El Salvador, Ecuador, Honduras, Mexico, Chile, China, Canada, Argentina, Peru, Taiwan, United States, Bolivia and Turkey have been documented with regards to the detection of natural levels in groundwater, the occurrence and distribution mechanisms, the human health effects and the in-situ and ex-situ treatment techniques (Jean et al., 2010). In many of these locations, arsenic is naturally found in the subsurface strata within volcanic and sedimentary formations as well as in areas of geothermal systems related to tectonic activity. Western Anatolia in Turkey is one such area of complex geology with active tectonics and high geothermal potential. This natural setting serves as a suitable environment for the presence of high levels of arsenic in subsurface waters. Based on these fundamentals, this study presents a general overview of arsenic presence in western Anatolia.Conference Object Tracing the Relative Distribution of Arsenic Species in Groundwater and Its Association With Soil Arsenic Levels in the Simav Graben Area, Turkey(2016) Gündüz, Orhan; Şimşek, Celalettin; Elçi, Alper; Baba, Alper; Gürleyük, HakanA comprehensive hydrogeochemical assessment was conducted in the Simav Plain, Turkey where major health concerns were reported and elevated arsenic (As) levels were previously found. Boreholes drilled in the plain were used to take core samples from the alluvial aquifer from which most groundwater was extracted. The results of core analyses revealed several orders of magnitude higher values than global average. Groundwater samples were later collected from these boreholes and analyzed for arsenic and its species as well as other related hydrochemical parameters. The results of groundwater quality assessment revealed that the groundwater in the plain was enriched with arsenic that exceed 1 mg/L level and was mostly under reducing conditions. The dominant arsenic specie in groundwater was arsenite in more than 70% of all samples.Conference Object Occurrence of Arsenic and Related Microbial Signature of Hydrothermal Systems in Western Turkey(Taylor & Francis, 2012) Chen, Chienyen; Maity, Jyoti Prakash; Bundschuh, Jochen; Bhattacharya, Prosun; Baba, Alper; Gündüz, OrhanThe naturally occurring aqueous Arsenic (As) and other toxic elements are found around the world. The present study concentrates on arsenic concentrations, speciation and related microbial diversity in a hydrothermal system in Western Turkey. The surface temperatures of hot springs reach up to 90°C and deep well (reservoir) temperatures vary in the range of 40 to 230°C. The elements such as As, B, Br, Ba, Cr, Fe, Mn, V and Zn are found in high concentration in hydrothermal waters. Hydrogeochemically, Seferihisar hot spring exhibited a Na-Cl water type. On the other hand, Karahayit, Pamukkale, Emirfaki, Alaşehir and Sart exhibit a Ca-HCO 3 water type and Çitgöl exhibited a Na-HCO 3-SO 4 water type. The arsenic (As) concentrations in geothermal waters of Western Anatolia have been detected to range from 0.03 mg/L to 1.5 mg/L, including Buharkent (İnalti) (1.50 ± 0.005 mg/L), Kizildere (1.13 ± 0.005 mg/L), Eynal (0.71 ± 0.005 mg/L) and Sarayköy (0.06 ± 0.004 mg/L). Arsenic (III) is the dominant species in geothermal water of Western Anatolia. The 16S rRNA gene sequences of bacterial diversity show that the thermophilic, sulfur/thiosulfate-oxidizing bacterium (Thiobacter subterraneus) is present in Kula geothermal water and mesophilic sulfur- and thiosulfate-oxidizing Sulfurovum lithotrophicum bacterium occurs in Sarayköy geothermal spring. Also, Bacillus fumarioli, (a thermophilic, aerobic endospore forming bacterium growing on (NH 4) 2 SO 4, MgSO 4 and MnSO 4 at 50-55°C), Schlegelella thermodepolymerans and Methylocaldum szegediense are rich in geothermal water.Conference Object Citation - Scopus: 4High Arsenic Levels in Groundwater Resources of Gediz Graben, Western Turkey(CRC Press, 2016) Baba, Alper; Gündüz, Orhan; Şimşek, Celalettin; Elçi, Alper; Sözbilir, Hasan; Murathan, AlimGediz Graben situated in western Turkey is an area containing extensional structures with active tectonics and geothermal systems that serves as a suitable environment for the presence of high levels of arsenic (As) in groundwater. The results of a comprehensive monitoring program in the basin revealed that the maximum As concentration detected during the monitoring program was 3086 ppb and the average value was calculated to be 23.63 ppb. In addition, As levels in 28% of the water samples were above the 10 ppb limit value making them unsuitable for drinking water supply. These high As concentrations in the basin was mostly associated with long detention times of water in altered rocks located along detachment faults, strong water–rock interaction processes in the alteration zones and anthropogenic influences made within the geothermal fluid reservoir. © 2016 Taylor & Francis Group, London.