Sürdürülebilir Kalkınma Amaçları
Yayınlar
- MakaleYalnız künye2026Scopus SJRQ2An Investigation of the Variability of Short-Term Drought with SPEI-Based Severity, Duration and Magnitude Parameters in a Transboundary Basin
Akbas, Ergun; Acar, Ramazan; Eşit, Musa; Koycegiz, Cihangir
Climate change-induced variability in the water budget leads to significant drought events. In this study, severity, duration, and magnitude parameters obtained from 1-month and 3-month series of the Standardized Precipitation Evapotranspiration Index (SPEI) were used to investigate short-term drought from different perspectives. The lower part of the Euphrates-Tigris Basin, which is a transboundary basin, was preferred as the study area within the borders of Türkiye. In this study, monthly total precipitation and monthly mean temperature data for the period 1963–2021 were used. Both graphical (Şen Innovative Trend Analysis) and statistical (Mann–Kendall, Spearman’s Rho, Sen’s Slope Estimator) trend analysis methods were applied to detect, categorize, and analyze the variability of drought. The Combination of Wilcoxon Test and Scatter Diagram (CWTSD) method, which offers both graphical and statistical trend analysis capabilities, was preferred to enhance consistency and facilitate comparison of results. According to the findings, more severe droughts are observed in the eastern part of the basin compared to the western part. Across the basin, severity and magnitude are decreasing, while duration is increasing. The increase in duration indicates that droughts are shifting from short-term to long-term periods. This situation is of great importance in terms of planning agricultural strategies.
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İncele - MakaleAçık Erişim2026Scopus SJRQ2Local Scour Process in Conduit Aerated Water Jets
Tuna, M. Cihat; Acar, Ramazan; Tunç, Mustafa
High-velocity water jets emerging from hydraulic structures cause local scouring in downstream areas, creating significant risks to structural safety. In this study, the effects of natural aeration provided through pressurized pipes on jet-induced scouring were investigated through laboratory experiments. A total of 60 experiments were conducted for different gate openings, flow rates, and downstream water levels; the scour geometries created by aerated and non-aerated jets were compared. The aeration level was defined by the dimensionless air-to-water flow ratio (Qa/Qw); maximum scour depth, scour length, scour slope angle, and jet fall distance were considered as basic evaluation parameters. The experimental results showed that increased aeration significantly reduced the maximum scour depth and scour length while moving the point of contact of the jet further upstream. While the scour depth and slope angles reached their highest values in non-aerated jets, shallower and flatter scour profiles were formed in aerated conditions. An empirical relationship predicting the maximum scour depth using experimental data has been developed and found to be in high correlation with the measured values (R2 = 0.93). The findings reveal that channel aeration is an effective method for reducing scouring and demonstrate that this approach can be considered a safe and economical alternative in the design of spillways, wastewater treatment plants, and similar hydraulic systems.
- MakaleAçık Erişim2026Scopus SJRQ1The effect of hydrostatic water level on the local scour downstream of plunging aerated jets
Tunc, Mustafa; Aytac, Ayca; Tuna, M. Cihat; Acar, Ramazan
This paper reports an experimental study on the effect of hydrostatic water level on local scour downstream of plunge aerated jets. To examine the shape of the scour for non-cohesive bed material, different flow and air rates, and different aeration capabilities, hydrostatic water level circumstances were tested. The water jets were aerated using conduit systems with varying cover opening ratios. Measurements were made to determine the length of the scour hole, the value of the maximum scour depth, the location of the maximum scour depth, and the scour hole profile in equilibrium. The current findings show that downstream hydrostatic water levels have a significant impact on the maximum depth and area of scour. Additionally, it was discovered that the conduit gate opening ratio and aeration performance (Qa/Qw) are crucial factors that affect the geometry and diameters of scour holes. The properties of scour caused by various hydrostatic levels were systematically compared to develop empirical correlations for predicting the maximum scour depth. Consequently, predictive emprical formulas incorporating these hydrostatic variations and aeration parameters are presented to improve engineering design accuracy.
- MakaleAçık Erişim2026Scopus SJRQ2Using Decision Tree and K-Means to Improve ANFIS for Predicting Missing Flow Data in Çoruh Basin
Acar, Ramazan
Complete and continuous flow data provides contributions to the water resources projects appropriate design. However, both financial and technical factors prevent the regular collection of data and such a situation leads to missing data problems. Input variables are from five stations in the Çoruh Basin in the northeast province of Türkiye, and output variables are from one station. In the study, 75% (171 months of data) of the 228 months flow data between the years 1993–2011 are used in the training phase and 25% (57 months of data) in the testing phase. In the ANFIS models, Decision Tree (DT) and K-means (KM) methods are used in selecting the input variables and determining the number of membership functions. In addition, artificial neural network (ANN), multiple linear regression (MLR), and ANFIS models with randomly determined cluster numbers are also used to compare the model performance of these methods. The results show that using DT and KM methods, the ANFIS models generate more reliable results than other models. During the study, the regression coefficient (R2), weighted mean square error (WMSE), and Wilcoxon (Z) values are taken into account for reliability measure. The DT–K-means–ANFIS model achieved the highest accuracy with R2 = 0.98 and WMSE = 5.89 during the testing phase, demonstrating superior performance to the ANN and MLR models. It is shown that the most successful models can be determined in a shorter time by using DT and KM methods before generating ANFIS models.
AtıfScopus1WoS1OpenAlex1İncele - MakaleAçık Erişim2026Scopus SJRQ1Optimization of scours downstream of conduit aerators
Arici, Erdinc; Tuna, M. Cihat; Aytac, Ayca; Acar, Ramazan; Tunc, Mustafa
Dams, wastewater treatment plants, and aquaculture areas often require aeration, making it crucial for hydraulic engineers to predict the physical properties of scour holes occurring on the downstream side of conduits. Conduit systems that provide high aeration performance necessitate multiple optimization studies to simultaneously maximize the scour parameters and the system’s physical properties. In this study, the physical parameters of conduit systems and downstream scour parameters were optimized using Artificial Neural Networks (ANN). The optimum system parameters were identified based on the experimental results through ANN-based optimization. Additionally, the real and optimal effects of the parameters on aeration performance and scour were determined. The results of the study demonstrated that ANN can be effectively used in studies aimed at optimizing the aeration performance and scour values of conduits. This study is the first to apply ANN for the simultaneous optimization of both aeration efficiency (Qa/Qw) and scour characteristics (dmax and δ) in a conduit-based hydraulic system. Previous studies have typically focused on either scour or aeration individually; this study integrates both through a multi-objective ANN model. The findings provide novel insights for the design and retrofitting of energy-dissipating conduit structures in high-head dam applications. Unlike traditional empirical or regression-based approaches, the ANN model captures complex, nonlinear relationships among multiple interacting hydraulic variables. It identified optimal parameter combinations — such as 70% gate opening, 1.30–1.50 m conduit length, and 9 mm air hole diameter — that improve both aeration and scour behavior. These outcomes offer direct applicability for real-world hydraulic system optimization.
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İncele - MakaleAçık Erişim2025Su Kalitesi Parametreleri için Mann-Kendall ve Yenilikçi Trend Yöntemlerinin Karşılaştırılması
Acar, Ramazan
Günümüzde farklı veri setleri (su kalitesi, akım, yağış, sıcaklık vb.) ile eğilimlerin tespit edilmesi için pek çok yöntem mevcuttur. Bu çalışmada trend analizi çalışmalarında yaygın bir şekilde kullanılan Mann-Kendall (MK) test istatistiği ile Spearman Rho test istatistiği ve son yıllarda popüler hale gelmiş olan Şen’in yenilikçi trend yöntemi (ITA), Yenilikçi eğilim çözümlemesi için geliştirilmiş görselleştirme (IV-ITA) yöntemlerinin performansları karşılaştırılmıştır. Bu amaçla Akdeniz Bölgesi’nde yer alan Ceyhan Nehri’ne ait 20-06-00-001 numaralı istasyonundan alınan 1986-2013 su yıllarına ait yıllık ortalama ve mevsimlik ortalama 8 adet su kalitesi parametresi kullanılmıştır. Öncelikle her bir parametrenin değerleri YSKYY’nde verilen su kalite değerleriyle karşılaştırılmış ve her bir parametreye göre su kalitesi sınıfları belirlenmiştir. Daha sonra her mevsim kendi içinde ve yıllık ortalama değerlerin trendleri karşılaştırılmıştır. Bu nedenle 5 farklı trend testinin karşılaştırılması yapılmıştır. Ancak sırasıyla yapılmış olan homojenlik ve otoregresif korelasyon testi işlemlerine göre hem %95 güven aralığında homojen olmayan hem de korelasyon değeri 0.30’un üzerinde kalan bazı veriler kıyaslamada kullanılmamıştır. Makalede elde edilen sonuçlar değerlendirildiğinde farklı analizlerin birlikte yapılarak kullanılması testlerdeki yanılma payını azaltacağı kanısına varılmıştır.
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İncele - MakaleYalnız künye2025Scopus SJRQ1Median-Linear model for solar radiation estimation by comparison with ANFIS and Angström-Prescott methods
Acar, Ramazan; Saplıoğlu, Kemal; Güçlü, Yavuz Selim
This paper aims to propose a novel approach to estimating solar radiation in relation to sunshine duration. A hybrid Median-Linear (MedLin) model is presented including both the median value and the linear solar radiation equation. First stage is concerned with two-stage alternative of the proposed model with inputs and outputs exhibiting a seasonality structure and it is seasonally adjusted using median values. In the second stage, the linear equation for the difference values is determined with estimations the difference in solar radiation. Finally, the median value and the estimated difference value are added. Monthly total solar radiation values are estimated using monthly total sunshine duration data from Mardin, Adana, Bozova, Hakkari, Şırnak, and Van stations in Southeast of Türkiye for the application. The predictions of the MedLin approach are compared with the results of the Angström-Prescott, ANFIS, and Mean-Linear (MeanLin) models. As for the prediction of monthly total solar radiation data at Mardin and Hakkari stations, the proposed MedLin approach yields the best results compared to other methods with mean absolute percentage error 3.508% and 8.951%, respectively. Angström-Prescott model for Adana, MeanLin method for Bozova, ANFIS model for Şırnak, and MeanLin model for Van provided the best predictions with mean absolute percentage error 3.721%, 3.285%, 4.278%, and 13.101%, respectively. The results show that the MedLin technique proposed in this paper is useful for solar radiation estimation.
AtıfWoS1İncele - MakaleYalnız künye2025Scopus SJRQ1Rainfall trends in the transboundary Euphrates-Tigris River Basin
Acar, Ramazan; Akbas, Ergun; Koycegiz, Cihangir; Esit, Musa
Climate change and anthropogenic factors have a significant impact on rainfall variability. In this study, the trends of monthly total precipitation in the transboundary Euphrates-Tigris River Basin (ETRB), where these effects are intensely observed, were analyzed by trend analysis methods with various perspectives. After decomposing the monthly total rainfall series (1964–2021) obtained from 18 stations representing 12 months of the year, statistical (Mann-Kendall, Wilcoxon, Onyutha), graphical (Innovative Polygon Trend Analysis, IPTA), Trend Polygon Star Concept, TPSC), sub-trend (Onyutha) and spatial trend analyses were performed. Based on the results, it was observed that rainfall in the basin has significant spatial and temporal variability. A monotonic strong decreasing trend was observed in cold months with high rainfall, while an increasing trend was observed in warm months with low rainfall. Extreme rainfall during the winter months has shifted towards the end of the cold months. Graphical and statistical analysis methods have shown strong consistency in identifying monotonic trends. However, the implementation of various methods provides specific insight (transition, sub-trend, etc.) into the temporal and spatial variability of rainfall. Sub-trend analysis shows that rainfall characteristics in the cold months show a significant change before and after the 1990–2000 period. In warmer months, this variability is significantly affected by local and global driving forces. The central and marginal parts of the ETRB have different rainfall characteristics. During cold months, the monotonic trend (decreasing) is significant in the central part. In warm months, the monotonic trend (increasing) increases its intensity in the eastern parts.
AtıfScopus12WoS10OpenAlex14İncele - MakaleYalnız künye2025Scopus SJRQ2Using Meta-Heuristic Optimization Algorithms to Determine Baseflow and Comparing Their Temporal Performance
Acar, Ramazan; Sapliogu, Kemal
Accurate and simple determination of baseflow is an extremely important issue. In this study, the baseflow levels of Göksu station number 1805 in the Seyhan basin were determined by calibrating the Lyne and Hollick, Chapman, Chapman and Maxwell methods available in the literature using meta-heuristic optimization methods. The meta-heuristic algorithms used for calibration in the study were run thirty times each. Thus the reliability, the reliability of the algorithms was tested with the standard deviations obtained. The study also measured the temporal performance of the algorithms. In addition, the baseflows of Göksu station were determined and their percentage rates were found separately according to all three methods and intuitive methods, and the results obtained were compared. By examining the results obtained in this section, the average baseflow rate of the basin was also determined. Furthermore, each phase of the study was repeated over a five-year period, with the objective of measuring its sustainability. Consequently, it has been demonstrated that the method can be employed over extended periods.
AtıfOpenAlex1İncele - MakaleYalnız künye2025Scopus SJRQ1Seasonally adjusted periodic time series for Mann-Kendall trend test
Güçlü, Yavuz Selim; Acar, Ramazan; Saplıoğlu, Kemal
In this study, temperature data trend analysis is conducted, which is thought to be influenced by global warming, climate change, and local factor impacts. The main objective of this paper is to obtain an acceptable autoregressive correlation value for the MK test. For this purpose, seasonality (periodicity) especially in monthly time series is adjusted. Autoregressive correlation and homogeneity test values decrease after seasonal adjusting, but reasonable results are not achieved. Then, prewhitening procedure is also applied to the seasonally adjusted data. This process resulted in the data becoming both homogeneous and free autoregressive correlation. The final version of the time series is suitable for the MK test. Furthermore, the time series are divided into different time intervals, and the efficacy of the method is investigated. The results demonstrated that the method is suitable for time series with less than 30 years of data. The study demonstrated that the proposed method enhances the reliability of the data. Also, multiplication by 12 (months) allows the MK test with Z score in place of the Student's t-test in short-term data sets. This suggested methodology can be used to identify MK trend conditions in monthly time series. The application is based on monthly and annual average temperature data between 1957 and 2022 from three stations within the Kızılırmak basin (Çankırı, Kırşehir, Sivas stations) and one station within Seyhan Basin (Adana station) in Türkiye. The test results exhibited a significant increasing trend.
AtıfScopus37WoS34OpenAlex41İncele - DüzeltmeAçık Erişim2025Scopus SJRQ1Correction: Median-Linear model for solar radiation estimation by comparison with ANFIS and Angström-Prescott methods (Modeling Earth Systems and Environment, (2025), 11, 5, (352), 10.1007/s40808-025-02554-1)
Acar, Ramazan; Saplıoğlu, Kemal; Güçlü, Yavuz Selim
The Funding information section was missing from this article and should have read ‘This research was supported by the Scientific Research Projects Coordination Unit of Istanbul Technical University under Project Number MGA-2025-46432’.The original article has been corrected.
- MakaleAçık Erişim2024Evaluation of Susurluk Basin Flows Using Trend Analysis Methods
Acar, Ramazan
Trend analysis of annual average flow data is very important for better water resources management, planning and operation. In this study, annual average flow data from M. Kemal Paşa, Orhaneli and Simav flow observation stations located in Susurluk Basin were tested with Mann-Kendall, Spearman Rho and Şen's Innovative trend methods and the trends of the stations were tried to be determined and the performances of these methods were evaluated. In addition, annual average flow data were submitted to regression analysis, yielding equation sets. For each station, the annual and 100-year changes in m3/s were determined. Analyzing the results, only Şen's Innovative Trend Method analysis found a general decreasing trend for all 3 stations. In the analyses of Mann-Kendall and Spearman’s Rho methods, no trend was detected in all 3 stations. In addition, 100-year percentage change values of the data of 3 stations were determined. According to these values, it is concluded that there will be a significant decrease in the flow values of the stations in the future.
AtıfOpenAlex11TR Dizin4İncele - MakaleAçık Erişim2024Scopus SJRQ2A comparison of the performance of different innovative trend assessment approaches for air temperature and precipitation data: an application to Elazığ Province (Turkey)
Acar, Ramazan
In this study, the temporal variability of monthly total precipitation and monthly average temperature data of Palu station were analyzed. In addition to statistical analysis such as Mann–Kendall (MK) and SR, innovative polygon trend analysis (IPTA), innovative trend analysis (ITA), and combination of Wilcoxon test and scatter diagram (CWTSD) methods were used in the study. A total of 24 trend analyses (for 12 months of precipitation and temperature data) were conducted for each method used for temperature and precipitation parameters in the study. Look-ing at the results of these methods, a decreasing trend was detected only in December for precipitation data, common to all methods. For temperature data, an increasing trend was detected only in February and March. With the application of the IPTA, an increasing trend in some months and a decreasing trend in other months were detected for the two parameters. The Wilcoxon test exhibits significant consistency with the MK and Spearman's Rho (SR) in terms of the statistical trend, according to the examination of temperature and precipitation data using the CWTSD approach, which is relatively recent. Furthermore, the visual trend analysis demonstrates high consistency between the NO-ITA and Sȩn-ITA approaches.
AtıfScopus23WoS20OpenAlex34İncele - MakaleAçık Erişim2022Etkili Girdi Parametrelerinin Çoklu Regresyon ile Belirlendiği Su Sertliğinin ANFIS Yöntemi ile Tahmin Edilmesi
Acar, Ramazan; Saplioglu, Kemal
Su sertliği; özellikle içme suları, endüstri suları ve hizmet suyu alanlarında kullanım hususunda önemli bir kalite özelliğidir. Kalsiyum (Ca), magnezyum (Mg) ve bikarbonat (HCO3) tuzları ile suyun geçici sertliği; klor (CL), fosfat (PO43), nitrat (NO3), sülfat (SO4) ve silikat tuzlarıyla da suyun kalıcı sertliği oluşmaktadır. Çalışmada, Fırat Havzası üzerinde bulunan 2119 nolu Kemahboğazı akım gözlem istasyonu (AGİ) için Anfis modelleri ile su sertliğinin tahmin edilmesi amaçlanmıştır. Bu amaçla Na, K, CO3, HCO3, CL, SO4, EC, sıcaklık (T), pH ve su miktarı (SM) verileri girdi olarak kullanılmıştır. Ancak modeller oluşturulurken parametre sayısının fazla olması kurulacak Anfis modellerinin sayısını arttırmakta ve bu modeller içerisinden en iyi modeli seçmeyi de zorlaştırmaktadır. Bu zorluğun üstesinden gelebilmek için Anfis modellerinde kullanılacak etkili parametrelerin belirlenebilmesi için çoklu regresyon modeli kurulmuştur. Oluşturulan çoklu regresyon modeline her parametre sırası ile eklenerek Düzeltilmiş R² değerlerindeki değişmeler gözlemlenerek Anfis modelinde kullanılacak etkili parametreler belirlenmiştir. Çoklu regresyon sonucu girdi parametrelerinin CL, EC, HCO3 ve SO4 olarak seçilmesine karar verilmiştir. Çalışmanın ikinci kısmında bu parametrelerin farklı kombinasyon ve alt küme sayıları ile Anfis modellemeleri oluşturulmuştur. Tüm sonuçlar eğitim ve test verileri için R², ağırlıklı karesel hata ve Wilcoxon testi değerleri belirlenmiş ve su sertliğinin belirlenmesinde kullanılabilecek modeller gösterilmiştir.
AtıfOpenAlex8TR Dizin5İncele - MakaleYalnız künye2020Akarsulardaki sediment taşınımının yapay sinir ağları ve anfıs yöntemleri kullanılarak tespiti
Acar, Ramazan; Saplioglu, Kemal
İçme suyu ile kullanma suyunun temini, akarsulardaki kirlilik seviyesi ve baraj, bağlama gibi su yapılarınınprojelendirilmesi gibi çalışmalarda sediment miktarının tahmini çok önemlidir. Bu çalışmada, Fırat Havzası üzerindeki Göynük Çayı, Murat Nehri ve Peri Suyu gibi nehirler sediment taşınımı konusunda irdelenmiştir. Bölgedeki istasyonlar için yapay sinir ağları (YSA) ve uyarlamalı ağ tabanlı bulanık çıkarım sistemi (ANFIS) gibi yöntemler denenmiştir. Bu üç istasyona ait uygulamalarda debi(Q), sediment(Qs), sıcaklık(T) ve yağış(P) verilerinden faydalanılmıştır. Bu veriler ile üç istasyon için sediment tahmin modelleri oluşturulmuştur. Oluşturulan bu modeller hem eğitim hem de test aşamalarında regresyon katsayısı (R2) ve ortalama yüzde hatası (OYH) bakımından karşılaştırılmıştır. Regresyon katsayısı bakımındaneğitim ve test aşamalarında en başarılı sonuç yapay sinir ağlarından elde edilmiştir. Ortalama yüzde hatası bakımından ise YSA ve ANFIS yöntemlerinden hem eğitim hem de test aşamalarında birbirlerine yakın sonuçlar elde edilmiştir.
AtıfTR Dizin4İncele - MakaleYalnız künye2020Detection of Sediment Transport with Artificial Intelligence Models Formed by Using K-Means Clustering Algorithm
Acar, Ramazan; Saplioglu, Kemal
It isimportant to detect sediment load truly in the project process of water structures such as both dam and regulator to determine pollution level, to use and to supply potable water. In this work, methods such as Adaptive Neuro Fuzzy Interference Systems (ANFIS), Artificial Neural Networks (ANN) and Multiple Linear Regression (MLR) are experienced for three Flow Observation Stations on Fırat Basin. K-Means Clustering Algorithm is used to select Clustering numbers of ANFIS Models being formed. Sediment (Qs), Precipitation (P), Flow rate (Q) and temperature (P) data from each station are used in this study. Sediment estimation model is developed for each station by using the data. The value of the day when precipitation occurs (P), the value of the day before precipitation occurs (P-1), flow and temperature rates are used as input factors; sediment concentration is used as output factors. The model being formed is compared for all of the stations with regard to regression coefficient (R2 ) and mean percentage error (MPE) in both education and test stages. As a consequence of the analysis, subset numbers of ANFIS model being formed by determining subset of K-Means Clustering Algorithm has more successful results instead of ANFIS Models being randomly formed. It is also observed that the Models of ANFIS and ANN methods have closer results to the values being observed when they are compared to MLR methods.
AtıfTR Dizin7İncele - MakaleYalnız künye2020Scopus SJRQ2Optimization of open channels using particle swarm optimization algorithm
Saplioglu, Kemal; Ozturk, Tulay Sugra Kucukerdem; Acar, Ramazan
Due to recent increasing water demand, planning and projecting of water resources has resulted in increased costs. There-fore, it is important to obtain optimum results in project planning. In this study, dimensioning of open channels used espe-cially for irrigation purposes has been studied using a particle swarm optimization algorithm to investigate optimum base width, channel height, and slope angles. The results are summarized in graphs and tables. In the study, it was found that the optimum slope angle varied between 0. 200. 45. Furthermore, it was found that increasing the slope angle significant-ly increased costs. Finally, the increase in flow increases costs but the rate of increase diminishes.
AtıfScopus6WoS6OpenAlex9İncele