Browsing by Author "AKPINAR, ADEM"

Now showing 1 - 20 of 24

Assessment of swan and wavewatch-iii models regarding the directional wave spectra estimates based on eastern black sea measurements
(Pergamon-elsevier Science Ltd, 2023-02-16) Rybalko, Aleksandra; Myslenkov, Stanislav; Akpınar, Adem; AKPINAR, ADEM; Amarouche, Khalid; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü.; 0000-0001-7983-4611; 0000-0002-9042-6851; AFR-7886-2022; AAC-6763-2019
The spectral wave models are often calibrated or validated based on bulk wave data derived from spectral in-formation such as the significant wave height (Hs) and mean period (Tm). However, the precision in the hind-casted spectral data was not evaluated in many seas, such as the Black Sea, due to the lack of spectral wave measurements. As part of this study, a spectral wave measuring buoy was installed near the cape Small Utrish to collect the spectral measurement data. The study objective is to assess the SWAN and WAVEWATCH-III (WWIII) models regarding the directional wave spectra estimates based on measurements conducted in the eastern Black Sea. For this purpose, the estimated spectral density distribution and spectral mean direction in terms of spectral frequency bins are assessed for both SWAN and WWIII outputs. The biases in variance densities are firstly calculated for both models at each frequency based on 14 710 spectral measurements, as well as the biases in the annual and seasonal averages. In addition, the correlation coefficients and root mean squared errors at each frequency are calculated and discussed. The accuracies in the mean direction at each spectral shape over the whole measurement period are secondly evaluated. Thirdly, the annual and seasonal averaged two-dimensional wave spectrums are discussed compared to measurements. The performances of both models are lastly verified based on bulk data measured at 8 locations on different coasts of the Black Sea. The results show that SWAN output fits better the average variance density shape at all frequency ranges f > 0.08Hz. However, it slightly overestimates the variance density in the 0.13-0.17 Hz range. In contrast to the SWAN model, WWIII data show only better correspondence in the 0.13-0.17 Hz frequency range but underestimate the lower frequency energies and overestimate higher frequency ranges. The SWAN model is therefore recommended for the spectral density estimate at seasonal and annual scales.
Characterization and classification of wave storm events and wave climate on the sea of Marmara
(Pergamon-elsevier Science Ltd, 2023-04-21) AKPINAR, ADEM; Kutupoğlu, Volkan; Akpınar, Adem; Çalışır, Emre; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü.; 0000-0002-5422-0119; 0000-0002-0440-1202; 0000-0002-9042-6851; AAC-6763-2019
This study aims to conduct a wave climate study and provide a detailed analysis of wave storm events on the Sea of Marmara based on a 40-year (1979-2018) hindcast dataset. The accuracy of the used dataset was initially investigated in terms of both climatic and storm conditions using five-year (2013-2017) measurements of sig-nificant wave height (Hm0) at the Silivri buoy station. For the wave climate, the measurements' 5-year mean and maximum Hm0 values were compared with SWAN hindcasts. To detect wave storm events from a time series, a critical value was determined by using the mean and standard deviation of the measurements. After that, the corresponding hindcasted storms with the measurements were detected. This analysis showed that the hindcasts are compatible with the measurements not only for climatic conditions but also for storm conditions. Monthly and annual variations of mean and maximum Hm0 were examined based on a 40-year long-term wave dataset and different return period Hm0 values based on annual maximums were determined at various locations. Wave storm events in the long-term analysis have been characterized and classified based on the storm energy density (Es) in five storm categories according to their energy. Temporal analysis of wave storm events shows that there has been an increase in the number and severity of storm events in recent years. The middle regions of the sea and the northeastern coasts of Marmara Island and Kapidag Peninsula are the most affected regions by extreme sea conditions.
Comparative performance analysis of different wind fields in the southern and north-western coastal areas of the black sea
(Natl Centre Marine Research, 2019-01-01) Çakmak, Recep Emre; Akpınar, Adem; Van Vledder, Gerbrant Ph; ÇAKMAK, RECEP EMRE; AKPINAR, ADEM; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü; 0000-0002-5422-0119; 0000-0001-6314-9118; JAO-0761-2023; ABE-8817-2020; AAC-6763-2019; AAG-8624-2021
This study determines the qualities of atmospheric wind field data in comparison with wind measurements at five locations along the Black Sea coast. For this purpose, four different wind fields were obtained from three different weather centers (NCEP, NASA, and ECMWF). Three of these are reanalyzed winds (Climate Forecast System Reanalysis CFSR, Modern-Era Retrospective-analysis for Research and Applications MERRA. ECMWF reanalyses ERA-Interim), and one is an operational dataset (ECMWF operational). Their performances were determined using the wind measurements from 2000 to 2014 at five coastal locations along the southern coastline of the Black Sea (Kumkoy, Amasra, Sinop, Giresun, Hopa) and from 2006 to 2009 at the offshore location (Gloria) off the coast of Romania. The performances of these wind fields were determined based on statistical characteristics (mean, standard deviation and variation coefficient, etc.), the statistical error analysis for all data and for different wind speed intervals, the wind roses and the probability distributions. Additionally, long-term variations of the yearly error values (SI and bias) of wind speeds from wind data sources during 2000 - 2014 were discussed. Finally, it was concluded that the CFSR wids give the best performance at most stations. The ECMWF datasets yield better results along the western side but the CFSR wind fields have shown better performances along the eastern side of the Black Sea coast and at the Gloria offshore location.
Dimensionless normalized wave power in the hot -spot areas of the Black Sea
(E D P Sciences, 2020-01-01) Majidi, Ajab Gul; Bingölbalı, Bilal; Akpınar, Adem; Rusu, Eugen; Kolhe, M. L.; Majidi, Ajab Gul; BİNGÖLBALİ, BİLAL; AKPINAR, ADEM; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü.; Kolhe, M. L.; 0000-0003-0006-5843; 0000-0003-4496-5974; 0000-0002-5422-0119; AAB-4152-2020 ; AAC-8011-2021; AAC-6763-2019
The main objective of this study is to identify and compare wave power sources in the high potential areas in nearshore and shallow water regions of the Black Sea. To achieve the goal, 23 locations were selected on two parallel lines around 5 m (10 sites) and around 25 m (13 sites) depth along the shoreline. The data needed to do the required analyzes at these locations were produced by using the calibrated nested layered 31-year wave hindcast SWAN model, which is operated between 1979-2009 with CFSR winds. The wave data were collected at a 2-hour time resolution for the sub-grid domains (SD3, SD2, and SD1) developed for the vicinity of Karaburun, Filyos, and Sinop coasts. HeaveBuoy, Oyster, Seabased AB, WaveDragon, WaveStar, Oyster2, and SSG, the most common known wave energy converters, were evaluated in the analysis. To ensure a more comprehensive analysis of the geographic variation of the predicted electrical power for each considered wave energy converter system, dimensionless normalized wave power and efficiency index were calculated separately for each wave energy converter devices at each location. From the results, it is recognized that generally, all the WEC systems performances are decreasing from Karaburun to Sinop while FB1 (13 m depth) the lowest, and KA2 (25 m depth) has the highest wave power capability. The most and the least energetic years were 1998 and 1989, repectively.
Downscaling wave energy converters for optimum performance in low-energy seas
(Elsevier, 2021-05-01) Iglesias, Gregorio; Majidi, AjabGul; Bingolbali, Bilal; BİNGÖLBALİ, BİLAL; Akpinar, Adem; AKPINAR, ADEM; Jafali, Halid; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi.; 0000-0003-0006-5843; 0000-0003-4496-5974; 0000-0002-5422-0119; AAB-4152-2020; AAC-8011-2021; AAC-6763-2019
As wave energy converters (WECs) are typically designed and optimized for ocean wave conditions, they struggle to perform in low-energy seas or bays, where wave conditions are very different. This work investigates the hypothesis that downscaled versions of WECs may well be more suited for such conditions. More specifically, fifteen downscaled WECs are considered for deployment in the Black Sea. The resizing (downscaling) of the WECs is based on Froude scaling law. Ten values are considered for the scaling factor (lambda(L) = 1/4 1.0, 0.9, 0.8 ... 0.1), and the value that yields the highest capacity factor is selected for downscaling the WEC. The downscaled WEC is then compared with the original (full-scale) WEC in terms of performance (capacity factor, full-load hours, and rated capacity). This analysis is carried out for fifteen WECs and 62 locations at different water depths (5, 25, 50, 75, and 100 m), distributed on 13 lines perpendicular to the shoreline along the south-western coast of the Black Sea. The highest capacity factor was obtained by Oyster, whereas the highest energy output was achieved by SSG and WaveDragon for the locations with 4-16 m depths. For deeper waters (25, 50, 75, and 100 m), the highest capacity factor was obtained by Oceantec. In terms of energy output, the best performers were WaveDragon (at 25 m water depth) and Pontoon (at 50, 75, and 100 m water depths). The interest of this approach, however, lies not only in that it enables a scaling factor to be determined for downscaling a WEC for a given site, but also and more generally in that it proves the initial hypothesis that downscaled WECs may provide a better alternative for low-energy seas than their full-scale counterparts.
Editorial: Advances in sea state modeling and climate change impacts
(Frontiers Media Sa, 2023-03-03) Besio, Giovanni; Kamranzad, Bahareh; Akpınar, Adem; AKPINAR, ADEM; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü.; AAC-6763-2019
Editorial: Offshore wind and wave energy and climate change impacts
(Frontiers Media Sa, 2022-09-01) Rosa-Santos, Paulo Jorge; Carvalho, David; Akpinar, Adem; AKPINAR, ADEM; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü.; AAC-6763-2019
Global extreme wave estimates and their sensitivity to the analysed data period and data sources
(Elsevier Sci Ltd, 2023-07-13) Kamranzad, Bahareh; Khames, Ghollame-Ellah-Yacine; AKPINAR, ADEM; Amarouche, Khalid; AMAROUCHE, KHALID; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü.; 0000-0002-9042-6851; AFR-7886-2022; AAC-6763-2019
In the absence of wave measuring buoys operating over extended periods, wave hindcast data or satellite observations are indispensable for estimating global extreme wave heights. However, the results may depend on the analysed wind wave sources and the period's length. The sensitivity of the estimated extreme significant wave heights (SWH) to the analysed data sources and periods is investigated in this study. Global extreme wave heights are estimated using ECMWF Reanalysis v5 data (ERA5), global wave hindcast developed based on Simulating WAves Nearshore forced by the Japanese 55-year Reanalysis (SWAN-JRA55), satellite altimeter observations, and long-term wave buoy measurements. Both Annual Maximum fitting to the Generalized Extreme Value Distribution (AM-GEV) and Peaks Over Threshold fitted to the Generalized Pareto Distribution (POT-GPD) models are used. The results show that the global extreme SWH estimates considerably depend on the analysed data sources. The relative differences observed between the analysed data sources are >20% in large parts of the world. Thus, the relative differences in extreme SWH are mainly lower by increasing the analysed data periods. However, they can reach 30% and are more critical using AM-GEV. Besides, by comparing the extreme values from reanalysis and hindcast wave data to those from long-term wave measurements, underestimations of up to 2 m are observed for a return period of 100 years in the North-West Atlantic and North-East Pacific.
Increasing trends in spectral peak energy and period in a semi-closed sea
(Pergamon-elsevier Science Ltd, 2023-02-13) Acar, Emine; Akpınar, Adem; AKPINAR, ADEM; Kankal, Murat; KANKAL, MURAT; Amarouche, Khalid; AMAROUCHE, KHALID; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü.; 0000-0002-9042-6851; 0000-0003-0897-4742; 0000-0001-7983-4611; JTU-9268-2023; AAC-6763-2019; AAZ-6851-2020; AFR-7886-2022
This study aims to investigate long-term trends in the Black Sea's spectral wave peak energy and periods. Improved Visualization of the Innovative Trend Analysis and the Mann-Kendal methods was applied to the maximum and mean spectral peak energies and peak periods between 1979 and 2020. Long-term spectral data are obtained from the ERA5 reanalysis and two spectral wave models, SWAN and WWIII. The innovative trend analysis method has the particularity to examine trends in higher and lower value categories. Studies of long-term changes in spectral wave characteristics are rare, and trends in spectral peak parameters are evaluated in this study for the first time in the Black Sea. It was detected that both spectral peak energies and peak periods tend to increase predominantly over most of the time scales. Furthermore, while the change rates for peak en-ergies do not exceed 40% annually and seasonally, change rates exceeding 100% are observed on a monthly basis. Besides, the change rates of the peak periods vary in the +/- 5% band and usually do not exceed 15%. Moreover, despite a few differences, trend analysis results obtained using SWAN and WWIII models were close to the global ERA5 results. The results may provide insight into the design and durable development of coastal and marine structures as well as the evaluation of wave climate change based on spectral wave data.
Inter- and intra-annual wave energy resource assessment in the south-western black sea coast
(Pergamon-Elsevier Science Ltd, 2021-01-22) Bingolbali, Bilal; BİNGÖLBALİ, BİLAL; Majidi, Ajab Gul; Akpinar, Adem; AKPINAR, ADEM; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi.; 0000-0003-4496-5974; 0000-0003-0006-5843; 0000-0002-5422-0119; AAB-4152-2020; AAC-6763-2019; AAC-8011-2021
This study focuses on the inter- and intra-annual variation in theoretical wave power along the southwestern coast of the Black Sea. Long-term (1979-2009) hindcast developed using the calibrated three-layer nested SWAN model was used for a detailed assessment of wave energy resource. Annual change, monthly and seasonal wave power variability indices were evaluated, and the Optimal Hotspot Index (OHI) was calculated for 62 sites along the coast to rate the hotspot locations. The assessment shows the highest wave energy resources in western Karaburun with higher variability. However, the western Sinop sites have lower wave energy resources compared to western Karaburun sites, in spite of considering the lower variability, these sites are more appropriate for wave energy extraction. The location with the highest potential (KAS 100 m depth) has an average of 8.4 kW/m and a maximum of 1015 kW/m wave power capacity. The east sites of Sinop and Filyos are comparatively less dynamic. Moreover, it was found that the average peak values of wave heights are in February, and the lowest sea state was in June. 2003 was the most, and 1989 was the least energetic years in the 31-year period.
Long-term characterisation of directional wave spectra in the black sea and the sea of azov
(Elsevier, 2023-11-07) Amarouche, Khalid; Akpınar, Adem; AMAROUCHE, KHALID; AKPINAR, ADEM; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü; 0000-0001-7983-4611; 0000-0002-9042-6851; AFR-7886-2022; AAC-6763-2019
Directional wave spectra describe complex sea-states in frequency and directional domains and provide more detailed information than the bulk wave parameters. Using hourly directional wave spectra hindcasted for 42 years (1979-2020), this study aims to assess long-term spectral wave climate in the Black and Azov Seas. Variance densities are averaged over the frequencies and directions for annual, seasonal, and monthly scales to determine spectral wave climate. Furthermore, The individual wave systems observed in each directional wave spectra are determined by referring to the independent spectral peak at each observation. The different sea state conditions, including the uni-modal and multi-modal wave systems, are classified and analysed; The energy, frequency, and direction of the three first prominent individual wave system peaks are deeply evaluated as a function of the sea state conditions. Occurrences as the function of spectral peak density and directions of the prominent individual wave system peaks are also computed and discussed. The results reveal that multi-modal spectra are more frequent, although the highest peak density values and lowest peak frequencies were observed within the wave spectra of uni-modal sea states. The spectral peak densities, frequencies, and directions depend on the number of wave systems in the wave spectrum and geographic location. The first peaks in the wave spectra are primarily derived from two dominant directions, and similar to 54 % of the peaks had a density greater than 2 m(2)/Hz. In contrast, second and third peaks in the wave spectra are typically derived from three or more dominant directions and rarely exceed 2 m(2)/Hz density.
New wind-wave climate records in the Western Mediterranean Sea
(Springer, 2021-11-03) Amarouche, Khalıd; Bingölbalı, Bilal; Akpınar, Adem; AMAROUCHE, KHALID; BİNGÖLBALİ, BİLAL; AKPINAR, ADEM; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü; 0000-0001-7983-4611; 0000-0002-9042-6851; AFR-7886-2022; AAB-4152-2020; AAC-6763-2019
This study presents a detailed analysis of changes in wind and wave climate in the Western Mediterranean Sea (WMed), based on 41 years of accurate wind and wave hindcasts. The purpose of this research is to assess the magnitude of recent changes in wave climate and to locate the coastal areas most affected by these changes. Starting from the Theil-Sen slope estimator and the Mann Kendall test, trends in mean and Max significant wave heights (SWH) and wind speed (WS) are analysed simultaneously on seasonal and annual scales. Thus, the new wave records observed since 2010 have been located spatially and temporally using a simple spatial analysis method, while the increases in maximum wave heights over the last decade have been estimated and mapped. This work was motivated by evidence pointed out by several authors concerning the influence of global climate change on the local climate in the Mediterranean Sea and by the increase in the number and intensity of wave storm events over recent years. Several exceptional storms have recently been observed along the Mediterranean coasts, including storm Adrian in 2018 and storm Gloria in 2020, which resulted in enormous damage along the French and Spanish coasts. The results of the present study reflect a worrying situation in large part of the WMed coasts. Most of the WMed basin experiences a significant increasing trend in the annual Max of SWH and WS with evident inter-seasonal variability that underlines the importance of multi-scale analysis to assess wind and wave trends. Since 2013, about half of the WMed coastline has experienced records in wave climate, not recorded at least since 1979, and several areas have experienced three successive records. Several WMed coasts are experiencing a worrying evolution of the wave climate, which requires a serious mobilisation to prevent probable catastrophic wave storms and ensure sustainable and economic development.
On the assessment of the wave modeling uncertainty in wave climate projections
(Iop Publishing Ltd, 2023-12-01) Lobeto, Hector; Semedo, Alvaro; Menendez, Melisa; Lemos, Gil; Kumar, Rajesh; Akpınar, Adem; Dobrynin, Mikhail; Kamranzad, Bahareh; AKPINAR, ADEM; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü.; 0000-0002-9042-6851 ; AAC-6763-2019
This study investigates the epistemic uncertainty associated with the wave propagation modeling in wave climate projections. A single-forcing, single-scenario, seven-member global wave climate projection ensemble is used, developed using three wave models with a consistent numerical domain. The uncertainty is assessed through projected changes in wave height, wave period, and wave direction. The relative importance of the wave model used and its internal parameterization are examined. The former is the dominant source of uncertainty in approximately two-thirds of the global ocean. The study reveals divergences in projected changes from runs of different models and runs of the same model with different parameterizations over 75% of the ensemble mean change in several ocean regions. Projected changes in the wave period shows the most significant uncertainties, particularly in the Pacific Ocean basin, while the wave height shows the least. Over 30% of global coastlines exhibit significant uncertainties in at least two out of the three wave climate variables analyzed. The coasts of western North America, the Maritime Continent and the Arabian Sea show the most significant wave modeling uncertainties.
Performance based assessment of a small-scale artificially nourished beach
(Elsevier, 2023-08-30) Karasu, Servet; Marangoz, Hasan Oğulcan; Gülkaya, Enes; Akpınar, Adem; Ceylan, Yusuf; Yılmaz, Enver; AKPINAR, ADEM; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü; AAC-6763-2019
In coastal engineering studies, coastal protection procedures can be provided by hard and soft methods. Soft methods applied using the right techniques and methods are not only long-lasting but also adapt to the natural structure of the coast. This study aims to present monitoring the development of a small-scale artificial nourished beach between the groins for 15 months and analyze its performance. For this purpose, field studies were carried out with land and sea observations taken once before nourishment and at 8 different times after nourishment. The seabed and profile variations observed at different sections were analyzed after processing field data. For determining the characteristics of the natural beach and borrow area before nourishment a sieve analysis was done for sediment samples taken from the shoreline, beach face, and 1-m depth on the nourished area. Sediment transportation of nourished material was observed by monitoring the amount of material remaining in 3 subregions (a nearshore region between the groins - A, a region representing the seaward end of the groins - B, and a region offshore of the groins - C) in the nourished region over time. The relationship between this behavior and waves was examined by considering the wave roses and time series of wave parameters produced as a result of wave simulations performed with the third-generation wave hindcast model SWAN. Lastly, as well as the variation of the mean layer thickness, the retreat of coastline, and mean beach width on the nourished area by the time were extracted for 8 different surveys. The results show that artificial beach nourishment materials were eroded in less than five months and the beach width returned to its initial position. The nourished material transported out groin-protected area moved eastward due to north-west dominated waves and the eastward longshore transport.
Quality of the ERA5 and CFS winds and their contribution to wave modelling performance in a semi-closed sea
(Taylor & Francis, 2021-03-12) Çalışır, Emre; Soran, Mehmet Burak; Akpınar, Adem; Çalışır, Emre; Soran, Mehmet Burak; AKPINAR, ADEM; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü.; 0000-0002-5422-0119; AAC-6763-2019; JJU-1857-2023; GCE-1854-2022
This study aims to investigate the quality of ERA5, a recent reanalysis wind product, and its contribution to wave modelling performance in a semi-closed sea, the Black Sea. This investigation includes a comparison of ERA5 surface wind fields with the ones from the CFSR to assess if this latest reanalysis improved the representation of the surface winds. Wind speeds from both reanalyses were validated with measurements at Gloria, the only sea wind measurement station on the Black Sea. Validations were also conducted using altimeter and scatterometer satellite data after which results were later compared against each other. The second aim of this study investigates whether a wave hindcast model forced with the ERA5 wind fields has improved prediction of wave parameters. A SWAN model with default settings was used to compare the results under the same conditions. Performance analyzes of the default SWAN wave estimates with both ERA5 and CFSR winds were conducted using three offshore buoy measurements and altimeter data of satellites over the Black Sea. Results show that ERA5 winds are more biased compared to CFSR winds at Gloria location. Both CFSR and ERA5 underestimate wind speeds. ERA5 performs better than the CFSR in lower wind speeds and worse in higher wind speeds. However, ERA5 winds have less bias and are more scattered than the CFSR winds against the satellite data. SWAN driven by CFSR winds performs better than the one driven by ERA5 winds against both buoy and satellite data.
Regional wave climate projections forced by EURO-CORDEX winds for the Black Sea and Sea of Azov towards the end of the 21st century
(Wiley, 2023-07-21) Çakmak, Recep Emre; Çalışır, Emre; Lemos, Gil; Akpınar, Adem; Semedo, Alvaro; Cardoso, Rita M.; Soares, Pedro M. M.; ÇAKMAK, RECEP EMRE; Çalışır, Emre; AKPINAR, ADEM; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü.; 0000-0002-9042-6851; KGQ-6522-2024; JJU-1857-2023; AAC-6763-2019
Wave phenomena impact high commercial value coastal and offshore activities, infrastructures and transportation. The knowledge of future wave conditions allows for consistent long-term planning and decision-making. The present study aims to provide robust, reliable projections of the potential future wave conditions of the Black Sea under the influence of climate change. For this purpose, an eight-member dynamic wave climate ensemble that accurately represents the Black Sea's present wave climate has been produced, and future projections are assessed and analysed here. The wave climate ensemble was obtained by forcing the Simulating Waves Nearshore spectral wave model with eight regional wind fields from the EURO-CORDEX. The future simulations of the regional wind fields are based on the RCP8.5 high-emission scenario. The historical wave climate of the ensemble was evaluated against ERA5 reanalysis data. Projected changes in the mean wind and wave characteristics are examined by comparing historical and future simulations. In addition, the projected trends in the annual means during the future period of the wave simulations for significant wave height (H-s) and wave energy flux are also analysed. The projections for H-s and wind speeds are pronounced with significant decreases down to -10% across the basin, especially in the eastern region of the Black Sea. Changes in the H-s 99% percentiles of up to 16% are projected to occur. The projected changes in the annual mean of the wave energy flux are close to the projected changes in H-s means, while the seasonal changes (between -15% and 12%) are expected to be higher.
Spatial calibration of wavewatch iii model against satellite observations using different input and dissipation parameterizations in the black sea
(Pergamon-elsevier Science Ltd, 2022-06-01) Akpınar, Adem; AKPINAR, ADEM; Soran, Mehmet Burak; Amarouche, Khalid; AMAROUCHE, KHALID; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü.; 0000-0001-7983-4611; 0000-0002-9042-6851; AFR-7886-2022; AAC-6763-2019
The quality of the third generation wave model WAVEWATCH III, referred WW3, using the different source term packages is investigated in the context of wave growth and dissipation in a semi-closed sea, Black Sea. Accuracy in wave height hindcast is tested for five different source term parameterizations ST1, ST2, ST3, ST4, and ST6 in WW3 against the 2020-year multi-mission satellite observations over the entire sea. The aims are to determine the most appropriate formulation and optimum tuneable coefficients for wind waves modelling in the Black Sea. For this purpose, significant wave heights (Hm0) are produced using five different source term packages implemented in the WW3 model. A sensitivity test was applied to define the tuneable parameters that contributes to the accuracy of the models, and subsequently the coefficient values of each parameters was turned to calibrate the WW3 models. The tuneable parameter allowing to obtain the most accurate result in each package are defined for each source term package. Comparing between model results and satellite observations, we found that the default WW3 model with all source terms as well as the calibrated ST2 model underestimate Hm0 in the entire domain and mainly in the eastern Black Sea region and are not suitable physical source term for the Black Sea. In the Black sea, the calibrated ST1, ST3 and ST4 forced with ERA5 wind are recommended for long term wave climate simulation, and the calibrated ST6 is recommended for extreme wave simulation.
Spatial characteristics of wind and wave parameters over the Sea of marmara
(Elsevier, 2021-01-23) Kutupoğlu, Volkan; Bingölbalı, Bilal; Çalışır, Emre; Akpmar, Adem; Kutupoğlu, Volkan; BİNGÖLBALİ, BİLAL; Çalışır, Emre; AKPINAR, ADEM; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü; Bursa Uludağ Üniversitesi/İnegöl Meslek Yüksekokulu; 0000-0002-5422-0119; 0000-0003-4496-5974; 0000-0002-0440-1202; 0000-0002-9042-6851; AAB-4152-2020; AAC-6763-2019; JJU-1857-2023
This study aims to determine long-term spatial variability of wind and wave characteristics over the Sea of Marmara. For this purpose, we produced four different wind and wave datasets for a period of 40 years (1979-2018) using the calibrated and default-setting SWAN models forced with both CFSR and ERA-Interim winds and inter-compared. The performance of these datasets is examined against the wave height measurements of 2015 at the Silivri buoy station and 27-year (1991-2018) satellites data (ENVISAT, ERS-1, ERS-2, JASON-1, JASON-2, JASON-3, SENTINEL-3A, SENTINEL-3B, TOPEX). Then, for wind and wave climate analysis, the spatial distributions of the wind and wave characteristics over the study area are determined in terms of seasonal and annual averages. 40-year averages of 95th and 99th percentile significant wave heights, probabilities of being larger than significant wave heights exceeding a critical value, and 40-year maximum significant wave heights are spatially analyzed. Finally, the calibrated SWAN model using CFSR winds presents the most accurate results. Therefore, the effects of different model inputs and settings on the model results are examined by creating spatial distributions of the biases of the other three model results and comparing them to those of the calibrated model results using CFSR winds. The CFSR forced and calibrated model predicts the largest average wind speed and average wave height in the central regions of the Sea of Marmara in comparison with the other three models. The shores of Kapidag Peninsula and Marmara Island are exposed to be with the highest wave conditions.
Spatio-temporal changes in downstream river bed during a dam construction
(Korean Society Of Civil Engineers-ksce, 2022-02-12) Can, Murat; Çalışır, Emre; Akpınar, Adem; AKPINAR, ADEM; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü.; 0000-0002-1693-5877; 0000-0002-0440-1202; 0000-0002-9042-6851; AAC-6763-2019
This study investigates the spatio-temporal changes in the downstream river bed during a dam construction on the Buyukkumla river channel in Bursa's Gemlik district in Turkey. To achieve this goal, an evaluation of the seasonal and annual effectiveness of dam construction activities in the study area, identifying geomorphological effects during dam construction, determining the spatio-temporal changes in the downstream river bed based on the comprehensive field observations, and analyzing the impacts on erosion-accumulation dynamics caused during the establishment of the dam is discussed. Measurements along the river stream were measured for different times, starting from the dam downstream. The two methods, satellite technology Global Navigation Satellite System (GNSS), also known as Global Positioning System (GPS) and terrestrial methods were used. GNSS was applied to fewer vegetation areas, whereas terrestrial methods were employed for areas with dense vegetation. Using the real point data obtained from the measurements, applying the kriging interpolation method, a Digital Elevation Model (DEM) was created by the Geographical Information Systems (GIS) programs, with similar resolution (each pixel with a 10(-5) x 10(-5) degree resolution). The results dividing the downstream side from the dam to the sea into two parts were obtained. In the upper zone of the study area, just downstream of the dam, accumulation in summer and scouring in winter were observed during the dam construction activities. Contrarily, in the lower part of the study area where the river flows into the sea, scouring in summer and accumulation in winter were dominant. One and half years later, after the dam excavation was over, with a little accumulation, the river bed reached an equilibrium condition. In the previous periods, while scours and accumulations higher than 6,000 m(3) were observed, the net change was, respectively, 933 m(3) erosion and 963 m(3) accumulation in the last two semi-annual periods.
Trend detection by innovative polygon trend analysis for winds and waves
(Frontiers Media Sa, 2022-08-10) Akcay, Fatma; Bingölbali, Bilal; BİNGÖLBALİ, BİLAL; Akpınar, Adem; AKPINAR, ADEM; Kankal, Murat; KANKAL, MURAT; Bursa Uludağ Üniversitesi/Mühendislik Fakültesi/İnşaat Mühendisliği Bölümü.; Bursa Uludağ Üniversitesi/İnegöl Meslek Yüksekokulu.; 0000-0003-4496-5974; 0000-0002-9042-6851; 0000-0003-0897-4742; AAZ-6851-2020; AAC-6763-2019
It is known that densely populated coastal areas may be adversely affected as a result of the climate change effects. In this respect, for coastal protection, utilization, and management it is critical to understand the changes in wind speed (WS) and significant wave height (SWH) in coastal areas. Innovative approaches, which are one of the trend analysis methods used as an effective way to examine these changes, have started to be used very frequently in many fields in recent years, although not in coastal and marine engineering. The Innovative Polygon Trend Analysis (IPTA) method provides to observe the one-year behavior of the time series by representing the changes between consecutive months as well as determining the trends in each individual month. It is not also affected by constraints such as data length, distribution type or serial correlation. Therefore, the main objective of this study is to investigate whether using innovative trend methods compared to the traditional methods makes a difference in trends of the climatological variables. For this goal, trends of mean and maximum WS and SWH series for each month at 33 coastal locations in Black Sea coasts were evaluated. Wind and wave parameters WS and SWH were obtained from 42-year long-term wave simulations using Simulating Waves Nearshore (SWAN) model forced by the Climate Forecast System Reanalysis (CFSR). Monthly mean and maximum WS and SWH were calculated at all locations and then trend analyses using both traditional and innovative methods were performed. Low occurrence of trends were detected for mean SWH, maximum SWH, mean WS, and maximum WS according to the Mann-Kendall test in the studied months. The IPTA method detected more trends, such as the decreasing trend of the mean SWH at most locations in May, July and November December. The lowest (highest) values were seen in summer (winter), according to a one-year cycle on the IPTA template for all variables. According to both methods, most of the months showed a decreasing trend for the mean WS at some locations in the inner continental shelf of the southwestern and southeastern Black Sea. The IPTA method can capture most of the trends detected by the Mann-Kendall method, and more missed by the latter method.