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    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 Ulke
    Turkey 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.
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    Öğe
    Detrended fluctuation analyses of rainfall intensities: a case study
    (Inderscience Enterprises Ltd, 2020) Zeybekoglu, Utku; Keskin, Asli Ulke
    The 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.
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    Öğe
    Evaluation of the relationships between atmospheric indices and rainfall intensities: Black Sea region Türkiye
    (Elsevier, 2024) Keskin, Asli Ulke; Kazembeigi, Reza; Zeybekoglu, Utku
    Recent 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.
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    Öğe
    Investigation of Applicability of Artificial Bee Colony Algorithm on Rainfall Intensity Duration Frequency Equations
    (Polish Soc Ecological Engineering, 2020) Zeybekoglu, Utku; Keskin, Asli Ulke
    The 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.