Civil Engineering / İnşaat Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/13
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Article Citation - WoS: 2Citation - Scopus: 2Assessment of Future Water Demand in a Semiarid Region of Turkey: a Case Study of Tahtali–seferihisar Basin(Springer, 2023) Karahan, S. M.; Elçi, ŞebnemWater is a vital resource for society and nature, and its scarcity has consequences in all aspects of existence. Today, issues including the inability to preserve the status of existing water resources and excessive water withdrawal are causing the amount of water to diminish day by day. Furthermore, factors such as urbanization and industrialization, population growth, water quality degradation owing to agricultural pesticides, and climate change, all have a negative impact on water supplies. A basin-based water management analysis was carried out in this study by applying the "Integrated Water Resources Management" strategy to the Tahtalı–Seferihisar sub-basin in Turkey, where water stress is expected in the future. Using the WEAP (Water Evaluation and Planning System) model, the hydrological (precipitation, flow, evaporation) data of important water resources for the basin and Izmir (Tahtalı, Seferihisar, Ürkmez, and Kavakdere Dams) were used to predict the availability of water resources in the future, and several possible scenarios for water demands/supplies were analyzed. The water budget balances projected in 2050 have been calculated by considering six different scenarios: Reference Scenario, Report Consumption Scenario, Optimistic Case Scenario, Pessimistic Case Scenario, Return Flow Scenario, and Various Forecast Scenario. The water balances that can be obtained in each scenario under various situations were computed and compared. For all considered scenarios, unmet water demand in the basin is found to be significant (157.52 hm3 in the Optimistic Case Scenario and 373.16 hm3 in the Pessimistic Case Scenario).Article Citation - WoS: 4Citation - Scopus: 4Destratification of Thermally Stratified Water Columns by Air Diffusers(Elsevier, 2023) Elçi, Şebnem; Hazar, Oğuz; Bahadıroğlu, Nisa; Karakaya, Derya; Bor, AslıThis study aims at improving the understanding in order to optimise an aeration system for artificial destratification to control cyanobacteria growth in the reservoirs. Previous applications for artificial destratification in reservoirs were based on installations based on computational methods, where neither the effect of air bubble size and configuration nor the effect of air density in the bubble plume could be investigated. This study seeks for an optimized design with the help of experimental and numerical analyses. In order to perform experimental studies, a novel water tank enabling the heating/cooling of the water column as desired and a diffuser system were manufactured. During the experimental studies, effect of bubble size, bubble slip velocity, and other parameters of air diffuser on destratification efficiency were investigated. Based on the nondimensional parameters, a new destratification efficiency formula is obtained by the Genetic Algorithm (GA) approach. Additionaly, the hydrodynamics of the water tank during the mixing process by air diffuser was simulated via 3D numerical model and validated with experimental results. The Eulerian multiphase model with the ‘degassing’ boundary condition and k-ω turbulence model are found to be suitable for the purposes of the study. Based on the error analysis of comparisons of the model and observations, the best configuration of air diffuser is proposed, and the numerical model is found to be successful in simulating the destratification of thermally stratified water columns by air diffuser.Article Citation - WoS: 10Citation - Scopus: 11Experimental Investigation of Sediment Movement as a Result of Homogeneous Earth-Fill Dam Overtopping Break Over a Simplified Urban Area(Elsevier, 2023) Taşkaya, Ebru; Bombar, Gökçen; Tayfur, GökmenWhen an earth-fill dam breaks, dam body sediment and water flow simultaneously move to downstream area causing devastation. Dam break studies in the literature have concentrated mostly on the water flow part while ignoring the sediment movement by designing the dam body as a movable metal gate. This study, however, is the first one experimentally investigating flow and sediment transport due to an earth-fill dam break by constructing the dam body from sediment. Sediment propagation as a result of homogenous earth-fill dam overtopping break was experimentally studied in a laboratory flume of 18.4 m long and 2.0 m wide, and 0.88 m in height in the Hydraulics Laboratory of Izmir Katip Celebi University, Izmir, Turkey. Downstream section right after the dam body was designed as a smooth bed and rough bed. The rough bed, resembling a simplified urban area, was created by using thirteen 10 × 10 × 10 cm sized concrete blocks. The dam body was constructed as homogenous with uniform material having D50 = 0.441 mm. The earth-fill dam body was built using the standard compression methods; each layer of sediment with a thickness of 10 cm was laid in layers, and the body was prepared with a crest width of 10 cm, a transverse base width of 200 cm, a longitudinal base width of 202 cm and height of 60 cm with upstream and downstream slopes of 1:1.6. The water level behind the dam was gradually raised until it overtopped the crest level. A pre-breach was formed at the top of the dam to trigger the break. During each dam break event, water depths were measured by three ULS-40D level meter sensors at different locations, and the final sediment bathymetry map was generated using the ULS-40D Probes at 10 × 10 cm grids. The results showed that, in both smooth and rough downstream bed cases, the dam body eventually collapsed while a great portion of it was carried away by the flood flow. The sediment spreading occurred all over the downstream area, showing significant non-uniform variation in thickness both longitudinally and transversely, especially in the simulated urban area. All the residential areas, while breaking in motion, were submerged under the muddy flow. Some blocks were almost submerged while sediment heights reached half level of some blocks at the end of the experiment. Sediment heights were higher in the urban area.Article Citation - WoS: 8Citation - Scopus: 13Masonry Buildings Subjected To Settlements: Half-Scale Testing, Detailed Measurements, and Insights Into Behaviour(Elsevier, 2023) Dalgıç, Korhan Deniz; Gülen, Burcu; Liu, Yiyan; Açıkgöz, Sinan; Burd, Harvey; Maraşlı, Muhammed; İlki, AlperIndustry procedures to assess the risk of settlement-induced damage to masonry buildings ignore key aspects of the problem, such as the influences of building weight, façade openings, and floor structures. Experimental data are needed to characterise the influence of these aspects on damage. This paper describes tests on three brick masonry half-scale building models subjected to settlements. The use of scaling rules in choosing the model materials and kentledge, the settlement apparatus, and the cross-validation of displacement and strain measurements are presented. Comparative evaluation of building responses show that: (i) the distribution of building weight and the resulting in-situ stresses play a key role in determining compliance to settlements, (ii) openings make the structure vulnerable to cracking and (iii) floor slabs stiffen and strengthen the building and prevent the formation of damage in the upper floors, leading to a concentration of damage at the ground storey.Article Citation - WoS: 112Citation - Scopus: 137Autonomous Electric Vehicles Can Reduce Carbon Emissions and Air Pollution in Cities(Elsevier, 2022) Ercan, Tolga; Onat, Nuri C.; Keya, Nowreen; Tatari, Ömer; Eluru, Naveen; Küçükvar, MuratHeavy dependence on personal vehicle usage made the transportation sector a major contributor to global climate change and air pollution in cities. In this study, we analyzed autonomous electric vehicles and compared their potential environmental impacts with public transportation options, carpooling, walking, cycling, and various transportation policy applications such as limiting lane-mile increases, and carbon tax. Fractional split multinomial logit and system dynamics modeling approaches are integrated to create a novel hybrid simulation model to process data from 929 metro/micropolitan areas in the U.S. for transportation mode choice behavior. The results show that the adoption of autonomous electric vehicles can reduce greenhouse gas emissions by up to 34% of the total emissions from transportation by 2050. This study has revealed that transportation-related impacts can only be reduced with a paradigm shift in the current practices of today's transportation industry, with disruptive reforms of automation, electrification, and shared transport.Article Citation - WoS: 3Citation - Scopus: 4Geothermal Potential of Manuguru Geothermal Field of Godavari Valley, India(Elsevier, 2022) Singh, Hemant K.; Chandrasekharam, Dornadula; Minissale, A.; Raju, N. Janardhana; Baba, AlperThe Godavari geothermal field in India is one of the potential areas manifested by several geothermal waters and groundwaters. The geothermal waters of the area are near neutral (pH: 6.5–7.3) with surface temperature ranging from 30 to 55 °C while groundwaters are also near neutral (pH: 6.6–7.5) with surface temperature ranging from 24 to 28 °C. The hydrogeochemistry of the geothermal waters suggests that the geothermal waters show a Na-Ca-SO4-HCO3 to a Ca-HCO3 type and groundwaters are of the Ca-HCO3 to Na-Ca-HCO3 type while groundwaters and river waters are of the Ca-Na-SO4 types. The geothermal waters of the study area are enriched in SO42– and Cl–, due to the interaction with the pyrite-bearing Gondwana sediments and granitic gneiss basement rocks. Furthermore, enrichment of Ca2+, Mg2+ and an increased HCO3/Cl ratio in geothermal water is caused by the exchange and/or mixing process that takes place during water-rock interaction at an elevated temperature while ascending to the surface. This type of behavior of water is also observed during the water-rock interaction experiment at 100 °C. Studies on geothermal gas geochemistry suggest the deeper circulation of geothermal waters in the crust and high helium concentration as a thermal gas that can be utilized for commercial purposes. Estimated reservoir temperatures from quartz and Na-K-Ca geothermometry are in the range 110–195 °C. Therefore, the geothermal water of the study area is categorized as a moderate enthalpy geothermal system. Thermal logging in the borewell and depth range from 50 to 1000 m suggest that the geothermal gradient in the Manuguru area ranges from 22.5 to 105.5 °C/km and heat flow ranges from 83 to 388 mW/m2, which is higher than the regional condition. Therefore, 3584 MWe power can be produced by using the Organic Rankine Cycle (ORC) from the Manuguru geothermal area of Godavari valleyArticle Citation - WoS: 1Citation - Scopus: 1Comparison of the Predicted and the Observed Wave Spectral Parameters During the Storms at Filyos Coasts, the Southwestern Black Sea(Elsevier, 2022) Öztunalı Özbahçeci, Bergüzar; Güler, MuzafferIn-situ wave measurement data are mainly used to validate the bulk wave parameters predicted by numerical models. Although the frequently used third-generation wave models are spectral models, determination of various spectral parameters and validation with the observed data are not common. This study covers the spectral analysis of selected storm records of a nearshore wave measurement campaign carried out at Filyos coasts with the complex bottom topography in Turkey, Southwestern Black Sea. The bulk wave and the spectral parameters are also calculated by a third-generation nearshore wave model, SWAN (Simulating Waves Nearshore), forced by the ERA5 offshore wave data, which is the newest re-analysis of the European Centre for Medium-Range Weather Forecasts (ECMWF) for the selected storms. Before using ERA5 offshore wave data, they are calibrated by the wave data of the satellite radar altimeter. In-situ measured bathymetry data are used in the SWAN model. Observed and predicted bulk wave and spectral parameters are compared, and the statistical error measures are calculated not only for the significant wave height, the peak period, and the peak wave direction but also for the three different spectral periods, three different frequency width parameters, a directional width and, a spectral peakedness parameter for the first time. Low values of statistical error measures show that the current wave predictions have a good agreement with the observed ones in terms of the significant wave height, Hs, and the peak period, Tp. However, the SWAN model predicts a slightly narrower frequency and directional spectrum with higher peaks, although the error measures are low. Moreover, SWAN can not predict the wide range of spectral shape occurrences that the observed spectra have. The development of the various spectral parameters during the storms is also investigated for the first time. It is found that the frequency and directional spreading of the observed spectra become wider and unsharpened in the late stages of the storm compared to the early stages. However, the same tendency is not observed clearly in the predicted directional spreadingArticle Citation - WoS: 24Citation - Scopus: 27Drought Assessment in the Aegean Region of Turkey(Springer, 2022) Mersin, Denizhan; Gülmez, Ayşe; Safari, Mir Jafar Sadegh; Vaheddoost, Babak; Tayfur, GökmenDrought indices are commonly used to monitor the duration and severity of droughts. In this regard, the continuously changing climate regardless of its cause or effect pushes the limit of the water deficit through time and space. Izmir is a raising city in Turkey, which owns various water resources including but not limited to seashores, lakes, river streams, and groundwater aquifers. In this study, the long-term precipitation and temperature records from 14 meteorological stations between 1973 and 2020 (for 47 years) are used to investigate the drought characteristics in Buyuk Menderes, Kucuk Menderes, and Gediz basins located in the Aegean region of Turkey. For this, the Standardized Precipitation Index (SPI) and the Standardized Precipitation Evapotranspiration Index (SPEI), Percent of Normal (PNI), and the so-called Discrepancy Precipitation Index (DPI) are used with consideration to 1-, 3-, 6-, and 12-month moving averages to investigate the drought patterns. Results showed that the monthly indices depict very similar results for the entire region. However, in the 1980s and 2010s droughts were more severe than the rest of the historical records. When the moving average operator is implemented in the analysis (3-, 6- and 12-month periods), neither SPI nor the SPEI showed the same results at any stations. It is illustrated that the periods of severe and normal drought have occurred in the past, yet the indices that are obtained using average values are generally within the normal limits, but extreme values (extremely arid or extremely wet) occurred occasionally. It is also concluded that although there is a similarity between the implemented indices, the DPI and PNI depict the highest resemblance.Article Citation - WoS: 2Citation - Scopus: 3Site Assessment of Surface Texture and Skid Resistance by Varying the Grit Parameters of an Sma(American Society of Civil Engineers (ASCE), 2022) Gökalp, İslam; Uz, Volkan Emre; Saltan, Mehmet; Tepe, MehtapFor the sale operation of vehicles, pavement should provide adequate skid resistance, which can be achieved by using high polishing-resistant aggregate in wearing courses. However, supplying high-quality aggregate is not always feasible due to high transportation costs. For this reason, a method called gritting was adapted to meet the Highway Technical Specification (HTS) of Turkey in 2013. According to the method, for certain parts of the country, the wearing course can be constructed with local aggregates that have minimum polished stone value (PSV) of 40 (PSV >= 40), but, in this case, the surface must be covered with a high polishing-resistant aggregate (PSV >= 50), after the rollers' first pass. The objective of this study was to improve the present gritting method by investigating the effect of grit parameters on pavement performance under real traffic conditions. In this regard, during its construction, the wearing course of 0-51 Highway was gritted with different aggregate types (slags and natural), sizes (1-3; 1-5 mm), spreading amount (1.5; 2; 2.5 kg/m(2)), and spreading time (before and after the first pass of a roller) on eight test sections. Then, the macrotexture and skid resistance performance of these sections were evaluated under real traffic and environmental conditions for longer than 4 years. Changes in surface texture and skid resistance with respect to traffic were determined for each section. The results showed that higher skid resistance values were obtained at the sections gritted with metallurgical slags. Additionally, the sections gritted with 1-5 mm aggregates had better skid resistance than those gritted with 1-3 mm, while the change in mean texture depths were not very significant.Article Citation - WoS: 8Citation - Scopus: 11Geothermal Potential of Granites: Case Study- Kaymaz and Sivrihisar (eskisehir Region) Western Anatolia(Elsevier, 2022) Chandrasekharam, Dornadula; Baba, Alper; Ayzit, Tolga; Singh, Hemant K.Radiogenic granites are gaining importance due to their ability to generate a substantial amount of electricity and support the advancement of agricultural and water sectors. In the western Anatolian region, such granites occupy a cumulative area of 6910 km2 varying from 7 to 20 μW/m3, far above the heat generated by the average continental crust of 5 μW/ m3. One cubic. The granite plutons of the Eskisehir region are amongst such granites with radioactive heat generation kilometer of such granite can generate 79 × 106 kWh of electricity. In the present case, the Eskisehir granites are capable of generating 616 million kWh of carbon-free electricity. Besides electricity, the heat from the granites can be utilized for space heating and greenhouse cultivation. This energy can also be utilized for the generation of fresh water from the sea through the desalination process. Hydrofracturing of the granites to create a fracture network connecting injection and production well is being replaced with closed-loop system that do not require knowledge about the stress pattern of the region and reduce the risk of induced micro-seismicity that was a bottleneck for developing EGS projects. Although the currently estimated cost of electricity generated from EGS projects is 9 euro cents/kWh, this cost will get reduced due to technological development in drilling technology. The Western Anatolian region has an additional advantage over the cost, since the drilling depth to capture the heat from the granites is shallow (∼3 km) which gives further benefit to the cost due to the reduction in drilling depth cost. In addition to high radiogenic granites, the presence of curie point temperature at shallow depth, high heat flow, and high geothermal gradient makes this region a warehouse of energy making Turkey energy-food and water independent in the future.
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