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Öğe Analysis of temperature and precipitation series of Hirfanli Dam Basin by Mann Kendall, Spearman’s Rho and Innovative Trend Analysis(Murat Yakar, 2024) Gunduz, Fatma; Zeybekoglu, UtkuIn this study long-term trend analysis of precipitation and temperature series are determined in the Hirfanli dam basin of Turkey. Data is obtained from the Turkish State Meteorological Service for the period of 1968 to 2017 for Gemerek, Kayseri, Kirsehir, Nevsehir, Sivas and Zara. Mann-Kendall, Spearman's Rho and Innovative Trend Analysis are used for trend analysis with 95% confidence levels. According to the results of the temperature series upward trend were determined. The results of all methods are similar but increasing significant trends were determined by Mann Kendall and Spearman's Rho except Zara. According to the precipitation series results, with decreasing trends in Gemerek, Kirsehir, Nevsehir and Zara, increasing trends were determined in Kayseri and Sivas. The results of Mann Kendall and Spearman's Rho methods show parallelism with each other. Contrary to other methods, Innovative Trend Analysis determined a decreasing trend in Kayseri. As a result of the analysis, the trends in the precipitation series are not significant at the 95% confidence level. In addition to statistical analyzes, evaluations were made in terms of integrated disaster management for drought disaster in the basin with arid climate characteristics. © 2024, Murat Yakar. All rights reserved.Öğe Bulanik C Ortalamalar Yöntemi ile Karadeniz Bölgesi Standart Süreli Yagis Siddetlerinin Kümelenmesi(Gümüshane Üniversitesi, 2018) Zeybekoglu, UtkuHidrometeorolojik veriler kullanilarak yapilanmühendislik çalismalarinda, verilerin eksiksiz ve yeterli uzunlukta olmasiçalismalarin verimliligini arttirmaktadir. Bölgesel mühendislik çalismalardaise verilerin istenen sekilde olmasinin yaninda uygun bölgelerin debelirlenmesi tasarim ve uygulama çalismalarinin daha verimli olmasinisaglayacaktir. Bu bölgelerin belirlenmesinde hidrometerolojik verilerin yanindacografi konum verilerin de kullanilmasi gerekmektedir. Bu çalisma kapsaminda Karadenizbölgesindeki Devlet Meteoroloji Islerine ait meteoroloji gözlem istasyonlarindagözlemlenen, Standart Süreli Yagislarin Siddetlerine ait veriler kullanilarakbölgesel kümelerin olusturulmasi amaçlanmistir. Bu amaçla Bulanik C Ortalamalaryöntemi kullanilmistir. . Kümeleme çalismalari iki farkli küme sayisi içinyapilmis olup en uygun küme sayisi 4 olarak belirlenmistir.Öğe Clustering of Black Sea Region Stations Using K-Means, Fuzzy C-Means and Silhouette Index Analysis Methods(Eskisehir Teknik Üniversitesi, 2023) Kir, Gürkan; Keskin, Asli Ülke; Zeybekoglu, UtkuIn recent years, there has been a noticeable increase in the number of disasters caused by the effects of global climate change. In this context, various studies are carried out in our country and in the world in order to reduce the effects of climate change. The classification of regions affected by climate change into similar classes in terms of climate parameters is important in terms of applying similar methods in studies to be carried out in these regions. Thus, a correct strategy will be determined in the studies to be carried out in order to reduce the effects of climate change. Within the scope of the study, annual temperature records of 31 stations in the Black Sea Region belonging to the Turkish State Meteorological Service for the period 1982-2020 were evaluated. Cluster analysis was carried out using the Fuzzy C-Means and K-Means methods. As a result of the study, the optimum number of clusters was determined by Silhouette index analysis. The most suitable classification for the temperature observations was obtained by the K-Means method by choosing the number of clusters as 5.Öğe Comparison of four precipitation based meteorological drought indices in the Yesilirmak Basin, Turkey(Hungarian Meteorological Service, 2023) Zeybekoglu, Utku; Hezarani, Alyar Boustani; Keskin, Asl UlkeDrought, which is often defined as not enough precipitation, does not a mean simple lack of precipitation. This condition, which occurs when humidity is less than the average value for many years, is caused by a disrupted balance between precipitation and evaporation in a region. It is very difficult to predict the start and the end time of drought. In the present study, the drought conditions of the stations selected from Yesilirmak Basin between 1970 and 2014 were determined by using Z-Score Index (ZSI), China-Z Index (CZI), Modified China-Z Index (MCZI), and Standard Precipitation Index (SPI), and the compliance of these indices to the SPI was investigated. It was determined that these indices gave parallel results to each other, and SPI detected drought earlier than other indices.Öğe Defining rainfall intensity clusters in Turkey by using the fuzzy c-means algorithm(Univ Zagreb , Andrija Mohorovicic Geophys Inst, 2020) Zeybekoglu, Utku; Keskin, Asli UlkeTurkey has seven traditionally accepted climatic zones that are defined primarily by maritime and topographic influences. Across these zones, the annual amount of rainfall, including its intensity and its seasonal distribution, vary considerably. These variations, which impact on both urban and rural communities, including the occurrence of water shortages and flash flooding events. are increasing in both frequency and magnitude due to global warming and climate change. Several types of climate occur in Turkey where climate zones have been defined with various methodologies. To better understand rainfall intensity patterns across Turkey, this study used the Fuzzy C-Means (FCM) algorithm to define their spatial distribution. In the first stage, the annual maximum rainfall intensity records for periods ranging from 30 to 78 years were obtained from 95 stations operated by the Turkish State Meteorological Service, and the longitude, latitude and altitude data for the stations were compiled for cluster analysis. Secondly, all rainfall intensities and geographical values were normalized, and in the third stage. the FCM algorithm was applied. The comparison of annual maximum rainfall intensities revealed five clusters. Four clusters were identified as discrete zones and one was identified as a transitional zone. Weather stations located in different geographical regions sometimes fell into the same clusters. In other words, rainfall events of similar intensity can occur in different climatic zones. This study, which brought a different perspective to clustering studies, showed that rainfall intensity values can be successfully analyzed at a national scale with the FCM technique.Öğe Detrended fluctuation analyses of rainfall intensities: a case study(Inderscience Enterprises Ltd, 2020) Zeybekoglu, Utku; Keskin, Asli UlkeThe main source of the irregularity in the rainfall regimes is global climate change. These irregularities in the precipitation regime cause sudden and heavy rains, which increases the risk of flooding especially in cities. Therefore, the investigation of the change in precipitation intensities over time has great implications in terms of hydrology, water resources and urbanisation. In this study, rainfall intensity of Artvin meteorological station which is located in the Black Sea Region of Turkey is investigated. This station differs from the other stations in the Black Sea Region with extreme rainfall characteristics. Data of 14 standard duration rainfall intensity series with durations of 5 min to 24 h were used. First of all, two methods were applied for homogeneity control and then trend analysis was performed. Assuming that the factor destabilising the homogeneity is the trend, a detrended fluctuation analysis (DFA) was performed. After the implementation of DFA, homogeneity and trend analysis were reapplied to the data. In conclusion, it was determined that the main reason for the deterioration of rainfall intensity was the trend.Öğe Drought Investigation Using SPI and SPEI Methods: A Case Study in Kirikkale(Kirikkale Üniversitesi, 2022) Aktürk, Gaye; Zeybekoglu, Utku; Yildiz, OsmanDrought is one of the most important natural disasters with various social and environmental effects. Therefore, it is very important to choose a particularly suitable index for monitoring drought. Standardized Precipitation Index (SPI) and Standardized Precipitation Evapotranspiration Index (SPEI) are widely used in drought monitoring. In this study, drought analysis was carried out using SPI and SPEI methods in order to examine the development and characteristics of drought in the city of Kirikkale, which has semi-arid characteristics. SPI and SPEI values were calculated on 1, 3, 6, 9 and 12-month time scales by using monthly precipitation and temperature data from Kirikkale meteorology station between 1963 and 2018. While calculating the potential evapotranspiration (PET) values in the SPEI calculation, Thornthwaite and Hargreaves models were used and two different SPEI values were obtained. As a result, high correlation values were obtained between all indices in the same time scale. It has been concluded that SPI and SPEI methods are applicable in the detection and monitoring of drought in the study area.Öğe Evaluation of The Homogeneity and Trends of Precipitation, Temperature and Wind Speed Parameters in The Black Sea Region(Hakan ÇAGLAR, 2023) Keskin, Asli Ülke; Kir, Gürkan; Zeybekoglu, UtkuIn recent years, there has been a noticeable increase in the number of disasters caused by the effects of global climate change. In this context, various studies are carried out in our country and in the world in order to reduce the effects of climate change. In the study, homogeneities and trends of precipitation, temperature and wind speed series of 31 stations in the Black Sea region were investigated. In addition, evaluations were made considering possible tendencies to disrupt homogeneity. In homogeneity analysis, Standard Normal Homogeneity Test (SNHT), Buishand Range Test (BRT), Pettitt Test (PT) and Von Neumann Ratio Test (VN), known as Absolute homogeneity tests, were used. Possible trends of stations were investigated using Spearman's Rho (SR) and Mann Kendall (MK) tests. According to the results of the homogeneity analysis, while the precipitation series of 30 stations were homogeneous, three stations were determined as homogeneous in the wind speed results. When the temperature series of the stations were examined, it was determined that the homogeneity was impaired in all stations. According to the results of the trend analysis, the significant increase trends determined especially in the temperature series show that the region started to warm up over time as an effect of global climate change.Öğe Evaluation of the relationships between atmospheric indices and rainfall intensities: Black Sea region Türkiye(Elsevier, 2024) Keskin, Asli Ulke; Kazembeigi, Reza; Zeybekoglu, UtkuRecent studies show that global atmospheric oscillations are effective on climate parameters. In this study, the relationship between the North Atlantic Oscillation and the Arctic Oscillation with the annual maximum rainfall intensity series throughout the Black Sea region of T & uuml;rkiye was investigated. In this context, the correlation coefficients between atmospheric oscillations and rainfall intensities were calculated. The correlations obtained were evaluated at the significance levels of alpha = 0.01, alpha = 0.05 and alpha = 0.10 according to Student t test. As a result of these evaluations; It was determined that the Arctic Oscillation was effective on rainfall intensities in & Ccedil;orum, Artvin, Rize and Bart & imath;n. In particular, significant correlations were found in all standard times in Artvin. Significant correlations were found between the North Atlantic Oscillation and the standard rainfall intensity series in & Ccedil;orum, Sinop, Artvin, Rize and Bayburt.Öğe Hydrological and Meteorological Drought Forecasting for the Yesilirmak River Basin, Turkey(Hakan ÇAGLAR, 2021) Hezarani, Alyar Boustani; Zeybekoglu, Utku; Keskin, Asli ÜlkeDrought is the most dangerous natural disaster. It differs from the other disasters in that it occurs insidiously, its effects are revealed gradually, and it persists for a long period. Drought has huge, negative effects on both society and natural ecosystems. In this study, values from the Standardized Precipitation Index (SPI) were used to generate drought estimation models by using Artificial Neural Networks (ANN). In addition, the probability of hydrological drought was determined by using SPI values to predict Streamflow Drought Index (SDI) values with ANN. Also, the SPI and SDI were used as the meteorological and hydrological drought indices, respectively, in conjunction with Feed Forward Neural Networks (FFNN), in ANN models. For this purpose, three rainfall and three flow gauging stations located in the Yesilirmak River Basin of Turkey were selected as the study units. The SPI and SDI values for the stations were calculated in order to create ANN estimation models. Different ANN forecasting models for SPI and SDI were trained and tested. In addition, the effects of the spatial distribution of precipitation on flows were determined by using the Thiessen Method to develop the SDI prediction model. The results generated by the ANN prediction models and resulting values were compared and the performances of the models were analyzed. The combination of ANN and SPI predicted meteorological drought with high accuracy but the combination of ANN and SDI was not as good in predicting hydrological drought.Öğe Investigation of annual droughts of Boyabat region using different meteorological drought indices(Hakan ÇAGLAR, 2022) Zeybekoglu, Utku; Sahin, AhmetDrought, which is a natural disaster that increases its effects day by day, can cause significant damage. Several drought indices were carried out to determine drought. By means of these indices, drought can be determined and necessary precautions can be taken against drought. In this study, an annual drought survey was conducted using the rainfall records of the Boyabat meteorological observation station in the Kizilirmak River Basin in the 1976-2017. In the drought analysis, the meteorological drought indices Z-Score Index, China-Z Index and Modified China-Z Index were used. The dry and wet periods of the station were determined by means of meteorological drought indices, and the driest and wettest years were also determined. In the study, which also examined the compatibility between indices, it was determined that the coefficient of determination values of MCZI-ZSI and MCZI-CZI were higher than the ZSI-CZI. Drought events in Boyabat region should be investigated using different indices.Öğe Investigation of Applicability of Artificial Bee Colony Algorithm on Rainfall Intensity Duration Frequency Equations(Polish Soc Ecological Engineering, 2020) Zeybekoglu, Utku; Keskin, Asli UlkeThe main objective of this study was to investigate the applicability and efficiency of an artificial bee colony optimization algorithm to determine two statistical-based rainfall intensity duration frequency equations' weighting parameters. For this aim, the annual maximum rainfall records were obtained from seven meteorological stations of seven geographic regions in Turkey. It was observed that the Artificial Bee Colony algorithm, which is an alternative technique for solving the rainfall intensity duration frequency equations, gives very good results in selected seven meteorological stations.Öğe Investigation of the Performance of Metaheuristic Optimization Methods by Using a Simple Water Distribution Network(Giresun Üniversitesi, 2017) Zeybekoglu, UtkuScientific and technological developmentstogether with the effect of increasing population, the sharing and usage ofwater on the earth gains more importance from day to day. It is a necessitythat this material which is so valuable on the earth is to be saved and usedadequately. In this study, it is aimed to determine the optimum conditions ofthe water in the pipes in a simple water distribution network. For thispurpose, the solution of the sample network has been realized by using theCuckoo Search and Firefly Algorithms and examined together with the results inthe literature. It has been determined that the solution of the network usingthe Cuckoo Search Algorithm is better than the other algorithms.Öğe PRECIPITATION REGIMES IN KIZILIRMAK BASIN, TURKEY(Gh Asachi Technical Univ Iasi, 2023) Zeybekoglu, Utku; Gunduz, FatmaChanging precipitation patterns and greater variations in precipitation cause flooding and flash flooding. Considering the future scenarios, it is predicted that the number and severity of floods and flood disasters will increase. The annual precipitation concentration and the temporal trend of precipitation concentration of the Kizilirmak Basin in Turkey were investigated. In addition, evaluations were made in terms of public administration against climate change and possible disasters. Precipitation Concentration Index (PCI) and Innovative Trend Analysis (ITA) were used with precipitation records for the period 1976-2017 in the Kizilirmak Basin. The results show a moderate precipitation regime at Kizilirmak Basin. According to ITA results, no significant trends were found at the 0.05 significance level. However, insignificant negative trends and positive trends were detected for PCI. It should not be forgotten that there will be changes in the frequency and severity of disasters such as floods and droughts, in which regions with irregular precipitation regimes are determined in the future. Within the scope of the modern disaster management approach, it is necessary to make preparations for reducing risks and damages and to raise awareness about disasters.Öğe Spatiotemporal analysis of droughts in Hirfanli Dam basin, Turkey by the Standardised Precipitation Evapotranspiration Index (SPEI)(Springer Int Publ Ag, 2022) Zeybekoglu, UtkuDrought is generally defined as a disaster affecting vital activities negatively because of water scarcity as a result of precipitation falling below the recorded normal levels. In the present study, the Standardized Precipitation Evapotranspiration Index was applied for the first time in Hirfanli Dam basin, which has the characteristics of a semiarid climate in Turkey. The annual drought events in the basin between 1968 and 2017 were investigated by using the precipitation and temperature data obtained from Gemerek, Kayseri, Kirsehir, Nevsehir, Sivas, and Zara meteorology observation stations located in Hirfanli Dam basin. The dry and wet years were determined in the basin, and evaluations were made in this respect. The years when the most severe droughts happened in the basin were determined, and drought maps, which showed the spatial distribution of drought, were prepared. In the light of the analyses and maps made, it was found that the most severe drought happened in 2001 in Hirfanli Dam basin.Öğe Temperature series analysis of the Hirfanli Dam Basin with the Mann-Kendall and Sequential Mann-Kendall tests(Murat Yakar, 2023) Zeybekoglu, UtkuGlobal warming is a result of the greenhouse effect caused by the gases released into the atmosphere; It is usually expressed as an increase in the measured average temperatures. In addition to this, extreme weather events such as droughts, floods, and severe hurricanes become more frequent, and the specified extreme events become more severe. The effects of global climate change on hydrological and meteorological variables are increasing day by day. Therefore, hydro-meteorological parameters should be examined carefully. In this study, the effects of global climate change on the Hirfanli Dam Basin temperature series were investigated using the Mann-Kendall Test and Sequential Mann–Kendall Test. The annual mean temperature series of six stations recorded between 1965 and 2017 were analyzed and evaluated. It has been determined that the annual mean temperature has increased throughout the basin and significant increases started since the 1990s. Researches analysing the effects of global climate change on hydro-meteorological parameters related to the Hirfanli Dam Basin should be increased. These studies may be the investigation of the trends of climate parameters with different methods, as well as their relations with global atmospheric indices such as the North Atlantic Oscillation and Southern Oscillation. In the Hirfanlı Dam Basin, which shows semi-arid climate characteristics, especially drought disaster should be investigated. In addition to drought detection, these studies should be conducted with an integrated disaster management perspective in order to prepare for drought disasters. With the perspective of integrated disaster management, it will be more resilience to disasters with plans in which all components in the basin are together and effective against many disasters, especially drought. © Author(s) 2023.Öğe Türkiye Yagis Siddeti Serilerinin Homojenlik Analizi(Hakan ÇAGLAR, 2022) Zeybekoglu, Utku; Keskin, Asli ÜlkeBu çalismada, Meteoroloji Genel Müdürlügü tarafindan isletilen 103 istasyondan 30 ile 78 yil arasinda degisen periyotlar için yillik maksimum yagis siddeti serilerinin homojenlik kontrolü yapilmistir. Mutlak homojenlik testleri olarak bilinen Standart Normal Homojenlik Testi (SNHT), Buishand Aralik Testi (BRT), Pettitt Testi (PT) ve Von Neumann Oran Testi (VNRT) %95 güven araliginda uygulanmistir. Standart süre verilerinden en az biri süpheli veya sorunlu ise, istasyon homojen degil olarak siniflandirilmistir. Homojenligi bozan faktörün muhtemel trend bilesenleri oldugu varsayilarak, trend bilesenleri ayrilmistir. Daha sonra, yagis siddeti serilerin mutlak homojenlik testleri yeniden uygulanmistir. Analizler sonucunda 103 istasyonun 49'u 14 standart sürenin tamaminda kullanilabilir olarak siniflandirilmistir. Kalan 54 istasyonun 45'i, trend bilesenlerinden sonra tüm standart süreleri kullanilabilir olarak siniflandirilmistir. 103 istasyondan geriye kalan 8’inde ise trend bilesenleri ayrildiktan sonra homojen olmayan degerlere sahip oldugu tespit edilmistir.
