Sustainable Development Goal "Goal 13: Climate Action" ile 'a göz atma
  • Öge
    10th International Symposium on Atmospheric Sciences : e-proceedings, 18-21 October 2022
    (İTÜ Yayınevi, 2023) Meteoroloji Mühendisliği ; Kahya, Ceyhan ; Öztopal, Ahmet
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    Appraising science-policy interfaces in local climate change policymaking: Revealing policymakers’ insights from Izmir Development Agency, Turkey
    (Elsevier, 2022) Eroğlu, Mehmet ; Öğüt Erbil, Aslı ; https://orcid.org/0000-0003-3127-8905 ; Department of Sociology
    Developing knowledge-based and usable climate change policies requires establishing science-policy interfaces through which knowledge producers and policymakers cooperate. Current research reveals that co-production- based interfaces dominated neither by knowledge producers nor policymakers succeed in facilitating the transformation of knowledge into politics. From this point of view, this paper explores how Izmir Development Agency (IZKA), a regional development agency in Turkey, utilizes scientific knowledge and science-policy interfaces in its activities on climate change. Based on the analysis of agency documents and semi-structured interviews with experts from and outside IZKA, the findings indicate that IZKA thrives in integrating scientific knowledge on climate change in its activities drawing from multi-stakeholder and multi-level science-policy interfaces that have significant similarities with the co-production model. In these interfaces, international, national, regional, and local stakeholders share their resources, knowledge, and experience on climate change. Although legal, geographical, and demographic conditions also have an impact, the main reason behind IZKA’s success is the agency’s climate-focused vision that shapes decisions, strategies, organizational structure, and activities. In parallel to the indicated finding, this paper also discloses that the perspective of not prioritizing climate change and considering the potential benefits as only “co-benefit” does not yield results with the desired efficiency. Another finding is that even though the national government is the main actor on climate in Turkey, development agencies are capable of carrying out transformative activities in their regions, albeit limited.
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    Bridging climate change science and policy through TMNs in Turkey : CoM as a boundary-object
    (Oxford University Press, 2022) Öğüt Erbil, Aslı ; Eroğlu, Mehmet ; Türk, Ebru Gönül ; https://orcid.org/0000-0003-3127-8905 ; Department of Sociology
    This paper qualitatively investigates one of the influential transnational municipal networks, Covenant of Mayors for Climate and Energy (CoM)’s position in three Turkish municipal governments in bridging the climate change science and climate change policy gap. In the last two decades, the importance of science-based policymaking for climate mitigation and adaptation and transnational municipal networks empowered by municipalities that guide city policies linked to international agreements has been recognized. In this paper, we argue that CoM has acted as a boundary-object in producing climate change policies and plans in Turkish municipal governments. However, CoM has done so to a certain extent; their effectiveness was limited due to the general atmosphere on climate change policies in Turkey. We substantiate this claim through a two-layer examination: a case-specific analysis of three municipalities and semi-structured interviews with thirteen experts in climate change policy-related issues.
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    Data-driven modeling for the prediction of stack gas concentration in a coal-fired power plant in Türkiye
    (Springer, 2024) Mohammadi, Mandana ; Saloğlu, Didem ; Dertli, Halil ; Ghaffari-Moghaddam, Mansour ; Mohammadi, Mitra ; 0000-0002-1119-1047 ; 0000-0003-0503-056X ; 0000-0001-6498-7594 ; 0000-0002-2925-7286 ; 0000-0003-3231-0946 ; Afet ve Acil Durum Yönetimi Anabilim Dalı
    In this research, deep learning and machine learning methods were employed to forecast the levels of stack gas concentrations in a coal-fired power plant situated in Türkiye. Real-time data collected from continuous emission monitoring systems (CEMS) serves as the basis for the predictions. The dataset includes measurements of carbon monoxide (CO), sulfur dioxide (SO2), nitrogen oxides (NOx), oxygen (O2), and dust levels, along with temperatures recorded. For this analysis, deep learning methods such as multi-layer perceptron network (MLP) and long short-term memory (LSTM) models were used, while machine learning techniques included light gradient boosted machine (LightGBM) and stochastic gradient descent (SGD) models were applied. The accuracy of the models was determined by analysing their performance using mean absolute error (MAE), root means square error (RMSE), and R-squared values. Based on the results, LightGBM achieved the highest R-squared (0.85) for O2 predictions, highlighting its variance-capturing ability. LSTM excelled in NOx (R-squared 0.87) and SO2 (R-squared 0.85) prediction, while showing the top R-squared (0.67) for CO. Both LSTM and LGBM achieved R-squared values of 0.78 for dust levels, indicating strong variance explanation. Conclusively, our findings highlight LSTM as the most effective approach for stack gas concentration forecasting, closely followed by the good performance of LightGBM. The importance of these results lies in their potential to effectively manage emissions in coal-fired power plants, thereby improving both environmental and operational aspects.
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    Design and nonlinear dynamic response of a steel stack
    (Springer, 2024) Vatansever, Cüneyt ; Çayır, Haşim ; 0000-0002-9954-925X ; 0000-0001-8131-4703 ; İnşaat Mühendisliği
    Industrial stacks are built in order to reduce atmospheric pollution and release gases to the higher level of the atmosphere. Since they are high and slender structures, they are significantly affected by lateral forces, in particular, induced by winds and earthquakes. This paper aims to summarize the design principles for steel stacks given in the international standards, codes and specifications considering the evaluation of the results from the investigation on nonlinear dynamic response of a typical steel stack subjected to the earthquake. For this purpose, a typical self-supporting steel stack has been designed and its performance under earthquake and wind forces has been investigated in terms of the applied design principles, such as the displacement limit and the potential plastic deformations. The study is accomplished by using finite element models employing nonlinear time history and pushover analyses. The numerical results are presented particularly by considering the design principles used for the model. The results show that wind loads considered are more pronounced in the design of industrial steel stacks than earthquake especially in terms of limiting top displacement. The flue openings which reduce strength and lateral stiffness of the stack web is significantly effective in the lateral behavior of the stack. Moreover, the principles considered are found applicable for the design of such steel stacks. Based on the results from nonlinear time history analyses, no yielding and plastic deformation are detected along the stack.
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    Development of drought intensity-duration-frequency curves based on standardized climatic indices using physical variables, deficit in precipitation and deficit in streamflow
    (Graduate School, 2023-11-13) Çavuş, Yonca ; Aksoy, Hafzullah ; Stahl, Kerstin ; 501192503 ; Hydraulics and Water Resources Engineering
    Drought is a natural disaster that causes water scarcity and affects the population seriously in many ways such as economic, social and environmental impacts. These effects have been further aggravated by rising demands for agricultural, municipal and industrial water, etc. due to the growing population coupled with rising life standards and increasing industrialization in the world. Compared to other natural hazards, drought is among the most damaging disasters as it develops slowly over a considerable period of time that may linger for several years even after the drought has terminated. How important the drought is in the sustainability of water resources requires an extra effort to understand and explain. Domestic use, agriculture, industry, energy, tourism and many more sectors are exposed to drought, which has a direct impact on ecology, economy and society. As one of the least understood hydrological phenomena, drought stands as both a technical and social problem. This is a great motivation to explore drought concepts and methodologies in this thesis by extending them from their quantitative technical context to qualitative social context. Case studies were performed in two river basins with different climatic characteristics. One is Seyhan River Basin in the south of Turkey with a Mediterranean climate, and another is the Kocher catchment in the southwestern corner of Germany with a humid subtropical climate. In the literature, the drought is commonly analyzed by the use of available hydroclimatic or hydrologic data with little in-depth consideration of specific major dry periods experienced over a region. Also, it is not a common practice to assess the probability of drought categories with a rolling time series and hence the changing knowledge for operational drought monitoring. A combination of such quantitative analysis with a comprehensive qualitative assessment of drought as a human-water relation aimed to fill this gap by performing a case study in the Seyhan River Basin, Turkey. Therefore, the first part of this thesis focuses on non-stationary rolling time series analysis together with the stationary full-record time series analysis and the individual major dry period analysis. Six major dry periods were identified from the precipitation time series of 19 meteorological stations. Dry periods extended over 1970-1974, 2002-2008, and 2013-2015, known also as droughts of 1974, 2008, and 2014, respectively, should particularly be noted among all as they affected several sectors in the river basin with the long-lasting deficit in water. Major dry periods were analyzed by rolling time series and full time series, and they were also analyzed individually. The results show that significantly higher probabilities were calculated for extreme droughts with the use of individual major dry periods. An important outcome of the study is that drought is underestimated in practice with the sole use of the whole data record. Also, a major dry period could be important in terms of its duration while another in terms of its severity or intensity. Each major dry period has its own impact on human-water relations that can be influential on drought mitigation, management and governance. The second part of the thesis investigates the statistical properties of drought characteristics for a better understanding of drought to mitigate its negative impacts and improve drought management strategies. Differently from the common approach based on the run theory, the hypothesis is that drought is different from the dry period and dry periods identify droughts of different durations. Up to now, no attention has been paid in this sense to the statistical properties of dry periods versus those of more severe and impactful droughts as separate phenomena. The study shows how different the statistical properties of dry periods and droughts are by quantifying them with the Standardized Precipitation Index (SPI) together with the total probability theorem-coupled frequency analysis. The study tests four concepts in this context: (1) Dry period, (2) Critical drought for a dry period, (3) Critical drought for a year. The results uncover the high number of droughts, which are not addressed in the run theory, and reveal more intense droughts that are masked within the dry periods. Specifically, the drought impact is more often related to drought intensity than severity and duration. In addition, the dry period is less intense than other concepts. Among the droughts newly proposed, critical droughts are the most intense concepts. This demonstrates that drought characteristics calculated for the drought concepts are different from the common approach of the dry period. The difference among the concepts is large enough to carry potential implications for local or regional scale drought management planning. In the third study, drought intensity-duration-frequency (IDF) curves were developed by using the critical drought identified in the second study. The drought IDF curves are based on precipitation and streamflow deficits because drought estimates in terms of physically measurable variables are key knowledge for effective water management. However, how these deficits vary with the drought event severity indicated by commonly used standardized indices is often unclear. Drought characteristics assigned the same value in the index are not necessarily the same in different regions, and in different months of the same region. The study investigates drought to remove this disadvantage of the index-based drought IDF curves and develop intensity-duration-frequency (IDF) curves in terms of the associated deficit. In order to study the variation of deficits, the link between precipitation and streamflow was used, and the associated indices, standardized precipitation index (SPI) and standardized streamflow index (SSI). More specifically, the analysis relies on frequency analysis combined with the total probability theorem applied to the critical drought severity. The critical drought has varying durations and it is extracted from dry periods. IDF curves in terms of precipitation and streamflow deficits for the most severe drought of each drought duration in each year are then subject to the comparison of statistical characteristics of droughts for different return periods. Precipitation and streamflow data from two catchments, the Seyhan River (Turkey) and the Kocher River (Germany) provide examples of two climatically and hydrologically different cases. A comparison of the two cases allows to test a similar method in different hydrological conditions. The results show that precipitation and streamflow deficits vary systematically reflecting seasonality and the magnitude of precipitation and streamflow characteristics of the catchments. Deficits change from one month to another at a given station. Higher precipitation deficits were observed in winter months compared to summer months. Additionally, major droughts experienced in both catchments on the IDF curves show that the major droughts have return periods at the order of years at short durations. This coincides with the observation in the catchments and shows the applicability of the IDF curves. The IDF curves can be considered a tool for the use in a range of specific activities of agriculture, ecology, industry, energy, water supply, etc. This is particularly important to end-users and decision-makers to act against the drought quickly and precisely in a more physically understandable manner. Other than quantitative methodologies, drought was also analyzed by a qualitative approach. Using the causal loop diagram, the drought event of 2008 observed in the Seyhan River Basin was taken as an example to focus on the identification of bidirectional feedback between humans and water under drought conditions. This particular drought is short but severe as it coincided with the least amount of precipitation ever recorded in the river basin. It is an important example because it gave an impetus to the governmental water authorities to initiate basin-scale drought management plans. The quantitative and qualitative data collected for this drought were used in the causal loop analysis. The causal loop diagram shows that short-term measures under economic, structural and conservation frameworks can only provide temporary solutions which may aggravate drought impact. A sustainable water availability under drought conditions can only be achieved by long-term reactions such as drought management plans. In summary, the thesis contributes to drought analysis research by proposing new methodologies and drought concepts. The outcomes of the study underline the need for such drought analyses. The analysis of the conceptualization reveals strong differences among the statistical properties of the drought characteristics. Moreover, the thesis emphasizes the region-specific characteristics of drought that need to be considered for drought management strategies.
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    Effects of climate trends and variability on tree health responses in the Black Sea and Mediterranean forests of Türkiye
    (Springer, 2024) Dogan Ciftci, Nida ; Şahin,, Ahmet Duran ; Yousefpour, Rasoul ; Christen , Andreas ; Meteoroloji Mühendisliği
    To adapt forest ecosystems and forest management to climate change, it is essential to know which forest regions and which tree species are resilient to climate variability and which ones are possibly affected most by past and anticipated future changes. In this contribution, for the main forest regions of Türkiye and six tree species, recent climate variability and trends were quantified and statistically correlated to record tree defoliation and vitality. Climate variables considered are maximum temperature (Tmax), minimum temperature (Tmin), mean temperature (Tmean), and total precipitation (Prcp), which are compared to forest health responses recorded as part of the International Cooperative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests) on 277 plots across forests along the Black Sea and Mediterranean regions. In addition, long-term data on satellite measurements of the normalized difference vegetation index (NDVI) were extracted for the same 277 plots for the period 2008–2020. Firstly, 30 years (1991–2020) of reanalysis of climate variables from ECMWF were extracted for all plots; secondly, individual correlations and cross-correlations of climate variables and tree health and vitality were computed for the period 2008–2020 (significance level of 95%) for the four most dominant species from the Black Sea forests (F. orientalis, Q. cerris, P. sylvestris, P. orientalis) and two species from Mediterranean forests (P. brutia and C. libani). Temperature showed a stronger effect on most species than precipitation. Finally, time-lagged correlations were analyzed for seven-time lags (significance level of 95%) to evaluate legacy effect. The analysis revealed that different tree species from the two regions show different responses to climate variables. Species in the Mediterranean region are more resistant to droughts and climatic variations. Legacy effects of defoliation and NDVI have lasted for at least 2 years.
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    Electric vehicles as an emission mitigation option : expectations and reality
    (Springer, 2024) Tetik Kollugil, Esin ; Sarıca, Kemal ; Topcu, Yusuf İlker ; 0000-0002-5824-9517 ; 0000-0001-9717-7854 ; Endüstriyel Tasarım
    Globally, the reliance on thermal power, constituting 67% of electricity generation, prompts questions for many countries regarding the viability of electric vehicles (EVs) for emission reduction in the transportation sector. This study comprehensively analyzes CO2 emissions in the small family car segment, considering engines powered by different energy sources. The analysis is coupled with Worldwide Harmonized Light Vehicle Test Procedure driving profiles, accounting for specific ambient temperature structures representative of densely populated areas in Türkiye. The constructed model incorporates the hourly temperature of the relevant cities and the hourly electricity production mix by considering the indirect emissions and comparing the ICEVs (Internal Combustion Engine Vehicles) and EVs in different time frames from 2015 to 2020. The resulting emissions from each vehicle type in each city and driving profile, along with the ratio of instances in which EVs exhibit higher emissions than ICEVs, are presented.The findings reveal the intricate interplay between vehicle type, climate conditions, and driving profiles. While the urban driving profile emerges as superior for EVs regarding CO2 reduction, offering a comfortable driving experience without range anxiety and mitigating local pollutants, it exhibits less significant carbon emission reductions at lower and higher speed profiles, particularly in cold climate conditions. EVs are not a silver bullet but a valuable technology for emissions reduction under specific conditions. Policymakers are urged to consider factors favoring EVs over ICEVs regarding CO2 emissions, such as driving profiles, time and climatic conditions when formulating investment policies and subsidies.
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    Enhanced energy recovery in municipal wastewater treatment plants through co-digestion by anaerobic membrane bioreactors : current status and future perspectives
    (Springer, 2024) Cengiz, Ali İzzet ; Güven, Hüseyin ; Özgün, Hale ; Erşahin, Mustafa Evren ; 0000-0002-4715-9567 ; 0000-0001-6754-0106 ; 0000-0001-8784-8351 ; 0000-0003-1607-0524 ; Çevre Mühendisliği
    Today, the transition to renewable energy from conventional energy practices is more important than ever to establish energy security and mitigate climate change. The wastewater treatment plants (WWTP) consume a remarkable amount of energy and cause significant greenhouse gas emissions. The energy balance of WWTP can be improved by implementing energy-efficient applications such as anaerobic digestion. However, most of the existing WWTPs utilize only sewage sludge in conventional anaerobic digesters (CAD) which results in low biogas generation. Generally, co-digestion is indicated as an effective solution for the low biogas generation faced in mono-digestion. Moreover, recently, anaerobic membrane bioreactors (AnMBR) have been promoted as a prominent alternative to CADs. This paper overviews the current situation of co-digestion applications by AnMBRs for municipal WWTPs. Furthermore, the environmental and economic aspects of these applications were reviewed. Lastly, challenges and future perspectives related to the co-digestion applications by AnMBR were thoroughly discussed.
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    Enhancing the sustainability of Poly(lactic acid) (PLA) through ketene-based chain extension
    (Springer, 2024) Alkan Göksu, Yonca ; Metalurji ve Malzeme Mühendisliği
    The widespread utilization of nonrenewable fossil-based polymers has led to significant environmental damage. Bio-based Poly(lactic acid) (PLA) has garnered substantial academic and industrial interest in the last two decades due to its advantageous characteristics for food packaging applications. Nonetheless, the improper disposal of PLA continues to contribute to the plastic waste problem. PLA recycling mainly involves thermal processes, facing challenges due to PLA’s limited stability. This study aims to enhance PLA’s molecular weight and melt viscosity by using chain extenders to increase its degree of branching. A modular chain extender capable of thermally forming highly reactive ketene intermediates is employed to react with PLA’s hydroxyl and carboxyl end groups in a single step. For this purpose, copolymers of styrene and 2,2,5-trimethyl-5-(4-vinylbenzyl)-1,3-dioxane-4,6-dione were synthesized using free radical polymerization and characterized through 1H-NMR, TGA, and DSC analyses. The chemical interaction between these chain extenders and molten PLA was also explored, resulting in increased PLA molecular weight and higher melting temperature (Tm), reaching 155.1 for PLA_2.5CE2. Additionally, the branching introduced through this process led to a notable increase in the UV absorption of PLA, suggesting potential applications in the packaging industry. The chemical tunability of this functional ketene-based chain extender holds promise for tailoring PLA’s structure for diverse applications, further advancing its sustainability and utility.
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    Thermodynamic investigations for combustion-assisted synthesis of lithium orthosilicate powders
    (Springer, 2024) Benzeşik, Kağan ; Yücel, Onuralp ; 0000-0003-0996-5151 ; 0000-0002-3879-0410 ; Metalurji ve Malzeme Mühendisliği
    The study investigates the combustion-assisted synthesis of lithium orthosilicate (Li4SiO4) powders for potential CO2 capture applications. Technical-grade lithium carbonate and metallic silicon powders were used as starting materials. Synthesis conditions were explored across temperatures ranging from 500 to 900 °C and different holding durations. Thermodynamic modeling using FactSage 8.2 software suggested that Li4SiO4 production is feasible at temperatures of 700 °C and higher with metallic silicon as the silicon source, which was confirmed experimentally. Characterization of the synthesized powders involved X-ray diffraction, specific surface area determination, particle size distribution analysis, scanning electron microscopy, and CO2 uptake tests. Despite having the lowest Li4SiO4 content as 83.7%, the sample synthesized at 700 °C with 45 min of holding time showed the best CO2 uptake performance as 12.80 wt% while having the lowest crystallite size value (126.58 nm), the highest specific surface area value (4.975 m2/g) and the lowest average particle size value (10.85 µm) which are highly effective on the CO2 uptake performance of such solid sorbents. The study concludes that while challenges remain in achieving optimal CO2 capture performance, it lays a foundation for utilizing lithium orthosilicate in carbon capture applications.
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    Variables controlling growing season carbon dynamics in desert shrub ecosystem
    (Springer, 2024) Şaylan, Levent ; Kimura, Reiji ; Başakın, Eyyup Ensar ; Kurosaki, Yasunori ; 0000-0003-3233-0277 ; 0000-0001-7700-3566 ; 0000-0002-9045-5302 ; 0000-0002-9595-0484 ; Meteoroloji Mühendisliği
    Arid and semi-arid lands (drylands) are under the influence of extreme environmental conditions and cover large areas on Earth’s land surface. Determining temporal and spatial variations of the greenhouse gas and energy exchange in these ecosystems will provide a better understanding of both, the dynamics between the drylands’s surface and the atmosphere and the importance in climate change. In this study, CO2 exchanges over a shrub steppe ecosystem were determined using the Eddy Covariance method during both dry and wet growing seasons in the Gobi Desert, Mongolia. The net ecosystem exchange (NEE) was modeled using the extreme gradient boosting method (XGBOOST). Variables influencing NEE were estimated employing the SHapley Additive exPlanations algorithm (SHAP). The XGBOOST predictions demonstrated impressive results across all growing seasons, with high performance metrics (R2 = 0.821; NSE = 0.817), particularly notable during the wet season (R2 = 0.932; NSE = 0.929). The total NEE changed between 79.7 and -110.4 gC m−2 throughout the growing seasons. Especially the precipitation before the growing period has a positive impact on carbon sequestration in the shrub ecosystem in the following dry season. A high similarity was found in the patterns of daily NEE of all growing seasons and normalized difference vegetation index (NDVI), albedo, soil water content, temperature, sensible heat flux, the difference between air and soil temperature in desert shrub ecosystem. Although NDVI was the dominant factor during the wet season, there was a weaker relationship between these factors and NEE in the dry season than in the wet season.