Papers by Mehmet Ishak Yuce

International Journal of Scientific and Technological Research, 2015
The world energy consumption has increased with rising of living standards, since the industrial ... more The world energy consumption has increased with rising of living standards, since the industrial revolution. Conventional power production methods trigger the climate change with environmental pollution. A considerable number of scientists believe that the current rate of fossil fuel consumption will not provide enough energy to human being for more than a few centuries. The concerns about fossil fuel based energy methods have led researchers to explore alternative, renewable, environmental friendly, cheaper and sustainable energy methods. The aim of this study is to provide an overview of global energy consumption by drawing attention to the environmental impacts of both fossil and renewable resources. In this study, an outlook of the world's energy production methods has been given and different type of energy production methods have been evaluated. The environmental impacts of current energy production methods have been outlined. The interrelation between the energy and climate change was illustrated.
Fosil yakitlarin cevreye verdigi zararlarla birlikte fosil yakitlarin tukenmesi alternatif enerji... more Fosil yakitlarin cevreye verdigi zararlarla birlikte fosil yakitlarin tukenmesi alternatif enerji kaynaklari arayisina neden olmaktadir. Bu durum yenilebilir enerji konusuna ilgiyi arttirmaktadir. Yenilenebilir enerji kaynaklarindan olan su, hayatimizin vazgecilmez bir parcasidir. Hem yasamimizi idame ettirmek hem de enerji uretmek icin kullanilan su, elektrik enerjisi uretiminde onemli bir yer tutmaktadir. Su dagitim sebekelerinden elektrik uretme fikri bircok makalenin konusunu olusturmustur. Bu makalede su dagitim sebekelerinde olusan fazla basinci kullanarak boru ici turbinle elektrik uretmektir. Fazla basinc; basic kirici valfler, maslak vs. ile sonumlenmesi yerine elektrik enerjisi elde etmek hem maliyet hem de cevre icin faydali olacaktir.

Environmental earth sciences, Apr 18, 2024
Drought, a major phenomenon impacting water resources, viability, sustainability, and the economy... more Drought, a major phenomenon impacting water resources, viability, sustainability, and the economy, has been one of the most important hydrological concerns. In the literature, it has been classified into four groups that are meteorological, agricultural, hydrological, and socio-economic. Meteorological drought expresses the precipitation deficits when they are significantly below those recorded normal times. In this study, using the Standard Precipitation Index (SPI) and mean monthly precipitation records of 17 stations which have been obtained from the General Directorate of Meteorology of Türkiye, a drought monitoring analysis has been conducted for Kızılırmak Basin, which is the second largest water basin of the country and water source of many provinces allowing for the time scales of 1, 3, 6, 9, 12, and 24 months considering the cases of "dry" (SPI ≤ -1.5) and "wet" (SPI ≥ 1.5). To detect the possible trends in two categories of Severe and Extreme Drought, SED (SPI ≤ -1.5), and Severe and Extreme Wet, SEW (SPI ≥ 1.5) of all time scales, a developed form of innovative trend analysis (ITA) is performed by adding two vertical lines. In addition, a traditional the Mann-Kendall test is applied to the SPI series. The findings indicate that dry occurrences tend to outnumber wet occurrences across various time scales. Analysis reveals that a significant majority of results across all time scales exhibit a consistent trend (89%), with a notable increase in the SEW category (62.74%) and a decrease in the SED category (60.78%). Mann-Kendall analysis demonstrates that 67% of the observed trends show a decrease, while 33% show an increase across all time scales.

International Journal of Technology, 2014
This paper presents the outcome of the trend analysis of hydro-meteorological variables in the Ni... more This paper presents the outcome of the trend analysis of hydro-meteorological variables in the Niger River and the Benue sub-basins in Nigeria. A non-parametric Mann-Kendall trend test was used to analyse the trends exhibited by the variables. The results revealed that precipitation exhibits insignificant positive trends in five locations, while insignificant negative trends were exhibited in the remaining six locations. This implies that the increase or decrease in precipitation would not be noticeable in all the locations, since the changes are statistically insignificant. The evaporation exhibits a significant positive trend in three locations, while in another three locations it exhibits an insignificant positive trend and also exhibits an insignificant negative trend in the remaining five locations. This is an indication that the incremental change in evaporation would be noticeable in three locations, while the increase or decrease would not be noticed in the remaining eight locations. In the case of minimum and maximum temperature, the trends in almost all the locations, except Ibi, are statistically significant positive. However, the runoff and water level in five locations out of six locations exhibit a significant negative trend. The downward trends exhibited by the runoff and water level in the two sub-basins may be due to the effect of climate variability on the hydrometeorological variables. The reduction of runoff is an indication of the decrease in water resources in the sub-basins and this can result in low reservoir inflow to the Kainji and Jebba hydropower dams located in the basin.
Journal American Water Works Association, May 1, 2016

Hydrological Sciences Journal-journal Des Sciences Hydrologiques, Aug 1, 2007
There is no doubt that so-called "artificial neural networks" (ANN) are powerful computational to... more There is no doubt that so-called "artificial neural networks" (ANN) are powerful computational tools to model complex nonlinear systems. In my view, an ANN establishes a data-driven nonlinear relationship between inputs and outputs of a system. The fact that such a nonlinear model is generally very complicated (usually one does not even write down the equations) renders it a black-box model. The fact that the model contains numerous parameters makes imperative the use of an advanced optimization method to calibrate its parameters. Once an ANN is fitted, it can be used to predict outputs from known inputs. Thus, there have been numerous successful applications of ANN in forecasting the future evolution of complex systems (e.g. Casdagli & Eubank, 1992; Weigend & Gershenfeld, 1994). However, I am afraid that there has also been an abuse in other cases, indirectly assisted by the numerous technical details, inapproachable for the majority of scientists (in our case hydrologists), and even by the exotic ANN vocabulary. The paper by Kişi (2006) stimulated my "reflex" questions about "neural networks", their use and abuse, and helped me to organize them so that they can be addressed to the "central nervous system". I start with the vocabulary itself. How "neural" are ANN? This question may be philosophical and related to the nature of the so called "artificial intelligence". I am not prepared to discuss in depth this type of question, for which profound analyses can be found in Dreyfus & Dreyfus (1986), Penrose (1989, 1994, 1996) and Hodges (2000-2002). However, I thought of a simplified version of this question: Is it necessary to call these mathematical models "neural" networks? Structures such as graphs and networks are very common in science (including hydrology, hydraulics and water resources), and consist of nodes (or vertices) and arcs (edges, or arrows in directed graphs and networks). Why in this case should we speak of "neurons" instead of nodes or arcs? After all, while in other cases (e.g. a river network, a water distribution network) the network has a physical hypostasis, in ANN the network is just a convenient pictorial representation of a complicated mathematical nonlinear relationship, which could be handled even without the notion of a network. A lot of similar questions can arise: Why use such terms as "one-pass learning algorithm with a highly parallel structure" or "training vector"? Isn't it more understandable to speak about "model calibration", "model fitting" and "parameter optimization" instead of "learning" or "training"? If yes, why have these anthropomorphized terms been so prevalent? Furthermore, is an ANN approach appropriate for any type of problem? Kişi (2006) seems to reply positively to this question. His motivation for the paper is simply this: "However, the application of ANN to evapotranspiration modelling is limited in the literature. ... To the knowledge of the author, no work has been reported
Trend and variability analysis in rainfall and temperature records over Van Province, Türkiye
Theoretical and Applied Climatology

International Journal of Applied Science and Engineering
Cylindrical weirs are one of the most commonly employed hydraulic structures to measure flow, com... more Cylindrical weirs are one of the most commonly employed hydraulic structures to measure flow, compare to other types of the same width they pass larger discharge. This paper presents an experimental work together with a CFD simulation to study the effects of the geometric characteristics of a cylindrical weir and a ramp placed upstream or downstream of the same weir on the discharge coefficient. Three different weir diameters and three ramp angles under three different discharges were utilized. The results show that the geometric characteristics represented by the diameter of the weir affects the discharge coefficient when there is no ramp. The discharge coefficient was observed to decrease as the slope of the upstream ramp was increased, however as the slope of the downstream ramp was increased the discharge coefficient was noted to increase. A mathematical relationship was developed in order to calculate the discharge of flow passes over the cylindrical weir depending on its diameter.

Homogeneity and Change Point Detection Analysis of Seasonal and Annual Precipitation and Temperature Series Van, Turkiye
Yüzüncü Yıl Üniversitesi Fen Bilimleri Enstitüsü Dergisi
: Researcher which study water resources, hydrological processes, and climate change fields are g... more : Researcher which study water resources, hydrological processes, and climate change fields are given of high importance to the accuracy and consistency of historical temperature and precipitation series. In this regard, Homogeneity tests are a helpful tool to manage the accuracy and consistency of the data. In this study, the homogeneity of seasonal and annual temperature and precipitation is examined using Standard Normal Homogeneity (SNHT), Pettitt (PT), Buishand Range (BR), and Cumulative Deviation (CD) tests at a significance level of 0.05. The four homogeneity tests are assessed using long-term annual and seasonal precipitation and temperature records obtained from five meteorological stations located in Van, Turkey. Finally, change point detection is investigated for each station. According to the results, the annual mean temperature rejects H0 hypothesis for all stations by four tests. While Ha alternative hypothesis is accepted for stations 17172 and 17852 and 17880 at annual total precipitation, stations 17784 and 17812 are observed as doubtful. Seasonal results revealed that although it is rarely seen that there is homogeneity, it can be concluded that the homogeneity is broken in the precipitation and temperature data, especially in the temperature data. It can be seen that stations 17784 and 17852 generally experienced changes after 2000, whereas stations 17172, 17812, and 17880 experienced changes before this year in the series. The results of this study constitute a source of information in terms of the reliability of the meteorological data series used in climate research, hydrological modeling, and statistical research to be carried out in this region. As a result, the reliability of the data should be questioned in the studies to be carried out in the Van region and the data should be made reliable in the projects to be carried out.

Bitlis Eren Üniversitesi Fen Bilimleri Dergisi
Drought is a natural disaster that is generally defined as precipitations which are significantly... more Drought is a natural disaster that is generally defined as precipitations which are significantly below the precipitation recorded in normal times. Drought has been classified as meteorological, hydrological, agricultural, and socio-economic by many researchers. Hydrological drought takes place when deficiencies in the surface and ground waters occur as a result of the long-term lack of precipitation. In this study, a hydrological drought analysis has been performed for Kızılırmak Basin which is the second biggest basin of Turkey by using streamflow drought index (SDI) and innovative trend analysis (ITA) for the time scales of 1, 3, 6, 9, 12-month. Monthly mean streamflow records of 7 stations are obtained from the General Directorate of State Hydraulic Works (DSİ). Drought severity and drought duration which is two important drought characteristics have been calculated for each time scale with their occurrence term. Results have shown that Mild Drought and Wet (SDI≥0) have the high...

Doğal Afetler ve Çevre Dergisi
Kuraklık, mevsimsel veya daha uzun süreli yağış eksikliğinin bir sonucu olarak neredeyse tüm ikli... more Kuraklık, mevsimsel veya daha uzun süreli yağış eksikliğinin bir sonucu olarak neredeyse tüm iklim bölgelerinde meydana gelen doğal bir afettir. Küresel ısınma, yağış yetersizliği, düşük yağış miktarı ve süresi, düşük bağıl nem ve diğer faktörlerin tümü, kuraklığın yaygınlaşmasına sebep olmaktadır. Bu çalışmada, Kahramanmaraş ilinin çok değişkenli kuraklık frekans analizi ve risk değerlendirilmesi kopula fonksiyonları kullanılarak yapılmıştır. Kuraklık parametreleri (süre ve şiddet), SPI (Standartlaştırılmış Yağış İndeksi) indeksi yöntemi ile elde edildikten sonra, her bir parametreye en uygun marjinal dağılımlar bulunmuştur. Son olarak, elde edilen en uygun marjinal dağılımlara bağlı olarak, en uygun kopula fonksiyonu hesaplandıktan sonra, Kahramanmaraş ilinin kuraklık parametrelerinin şartlı dönüş olasılıkları ve süreleri elde edilmiştir. Bu çalışma sonucunda, en yüksek şartlı kuraklık şiddeti dönüş periyodu Kahramanmaraş merkezde görülürken, en düşük dönüş periyoduna ise Elbistan...
Performance Evaluation of Using Sbs Polymer and Pomace Waste as Modified Bitumen in Hot Mix Asphalt
SSRN Electronic Journal
Hydrological drought analysis of Yeşilırmak Basin of Turkey by streamflow drought index (SDI) and innovative trend analysis (ITA)
Theoretical and Applied Climatology

Seyhan Havzası Yağış Verilerinin Eğilim Analizi
Kuresel veya yerel iklim degisiklikleri neticesinde, yagis miktarlarinda meydana gelen degisimin ... more Kuresel veya yerel iklim degisiklikleri neticesinde, yagis miktarlarinda meydana gelen degisimin temiz su kaynaklari uzerindeki etkilerinden dolayi hidro-meteorolojik verilerindeki egilim (trend) analizleri onem arz etmektedir. Bu calismada, Seyhan Havzasinin yagis verilerinde gidis olup olmadigi, parametrik olmayan Mann-Kendall testi, Spearmanin Rho, Mann Kendall Mertebe Korelasyon ve Sen’in Egim Analiz Testleri kullanilarak incelenmistir. Havzada bulunan 12 yagis gozlem istasyonu verilerinin en kisa sureli olani 21, en uzun sureli olani 52 yillik ( 1964-2016 ) bir periyodu kapsamaktadir. Yillik toplam yagis verileri %95 ve %85 guven araliklarina gore analiz edilmistir. Yagis verilerinin degerlendirilmesi sonucunda Pinarbasi istasyonunda her iki guven araliginda, Camardi istasyonunda ise sadece %85’lik guven araliginda azalan yonde egilim tespit edilmistir. Diger istasyonlarin verilerinde herhangi bir egilim gozlenmemistir.

In this article simulation analyses have been performed using computational fluid dynamics techni... more In this article simulation analyses have been performed using computational fluid dynamics techniques to investigate the performance of helical and straight-bladed cross flow hydrokinetic turbines with a horizontal layout and similar dimensions. The length and diameter and the type of the hydrofoil of both turbines are selected to be the same. A symmetrical NACA hydrofoil has been used in blade design for both turbines. The simulation analyses were performed for a 2-D NACA0018 hydrofoil and 3-D four bladed turbines. The skewness coefficient and the orthogonal quality tests have been dependent as statistical tools to examine the quality of the mesh for all models. The obtained results have shown that the helical turbine reaches the stall condition at the tip-speed ratio (TSR) of 3.75, while the straight-bladed turbine stops converting energy at 3.1. The highest power coefficient for the helical turbine was about 0.37, while it was found to be around 0.29 for the straight-bladed turbi...

Düşük Akımların Frekans Analizi ve Çevresel Akış ile İlişkisi
Yillik akis rejiminin bir bileseni olan dusuk akimlar yilin belli zamanlarinda akarsuda gorulebil... more Yillik akis rejiminin bir bileseni olan dusuk akimlar yilin belli zamanlarinda akarsuda gorulebilmektedir. Dusuk akimlarin akarsudan su saglanmasi, su kalitesi, ulasim ve canlilarin yasami uzerinde etkileri vardir. Bir akarsu havzasinda dusuk akimlarin uzun bir sure devam etmesi durumunda havzada kurakligin meydana gelme olasiligi artar. Bu donemlerde suyun ne sekilde kullanilacagina karar vermek icin dusuk akimlarin incelenmesi onem tasir. Kurak donemlerde her turlu maksatla kullanilacak suyun miktarinin belirlenmesinde bir arac olarak kullanilmak uzere dusuk akim ile ilgili calismalar yaygin olarak yapilmaktadir. Frekans analizi bu amacla kullanilan bir yontemdir. Bu calismada, Meric-Ergene, Gediz, Seyhan ve Ceyhan havzalari icin dusuk akim frekans analizi yapilmistir. Dusuk akimlarin frekans analizinde 2- ve 3-parametreli Gamma, log-normal ve Weibull dagilimi ile Genel Ekstrem Deger dagilimi secilmistir. Dusuk akimlari temsil etmede Meric-Ergene, Gediz ve Ceyhan havzalarinda cogu...
SN Applied Sciences
In this study, the hydraulic transient in a pipeline model was considered by utilizing the method... more In this study, the hydraulic transient in a pipeline model was considered by utilizing the method of characteristics. The pipeline conveys water from the upstream reservoir to the downstream one, while a valve was set at the downstream end of it. The effect of sudden, linear and stepwise valve closure schemes were analysed by employing a stainless-steel pipe and a ductile pipe. Sudden valve closure was noted to generate higher-pressure transients than linear and stepwise schemes. As the closure time period increases, the value of the maximum pressure transient decreases, in both linear and stepwise arrangements. The transient pressure was perceived to be higher in stainless-steel pipe than in ductile one, in three closure schemes. The simulations were performed by a purpose-developed MATLAB code.

SN Applied Sciences
Depth, width, velocity and suspended load are critical fluvial hydraulic characteristics, which m... more Depth, width, velocity and suspended load are critical fluvial hydraulic characteristics, which mainly determine the shape of the cross-section of a river. The aim of this study is to determine at-a-station and the downstream hydraulic geometry parameters and obtain a relationship between sediment discharge and flow discharge of the Ceyhan River. Eleven hydrological stations were utilised in the analyses which are located on the river and its tributaries. Three of these stations have sediment, flow discharge and cross-sectional data, while four of them have only sediment and flow discharge and the other four have only flow discharge and cross-sectional data. The downstream hydraulic geometry parameters b, f, m, a, c and k were found to be 0.33, 0.38, 0.29, 14.82, 0.61 and 0.12, respectively. At-a-station hydraulic geometry parameters b, f, m, a, c and k were found to be 0.1676, 0.00654, 0.7669, 25.676, 1.8542 and 0.0901, respectively. A good power function correlation was noted between the sediment discharge and flow discharge with the average coefficient and exponent of 1.23 and 2.05, respectively. The results of the study are expected to be valuable for water resources planning and management projects in the basin.

Kızılırmak Havzasının Hidrometeorolojik Verilerinin Trend Analizi
Nevşehir Bilim ve Teknoloji Dergisi
Yillik yagis ve sicakligin trend analizi; su kaynaklari yonetimi, hidrolik muhendislik projeleri ... more Yillik yagis ve sicakligin trend analizi; su kaynaklari yonetimi, hidrolik muhendislik projeleri gelistirme, cevre koruma ve surdurulebilir kentlesmede onemli bir yere sahiptir. Bu calismada, Turkiye’de yer alan Kizilirmak Havzasinda ve cevresinde bulunan 36 istasyonun yillik toplam yagis ve yillik ortalama sicaklik verilerinde herhangi bir artis ya da azalis trendi olup olmadigini belirlemek icin egilim analizleri yapilmistir. Parametrik olmayan bir egilim analiz yontemi olan Mann-Kendall testi, 1975 ile 2015 yillari arasinda degisen yaklasik 40 yillik bir periyodun verilerinin egilim hareketlerinin arastirilabilmesi icin kullanilmistir. Istasyonlarin cogunda toplam yillik yagista bir trend egilimi gozlenmemesine ragmen, ortalama yillik sicaklik degerlerinde % 95'lik onem araligina gore artan bir egilim gozlendi.

Water Science and Technology: Water Supply
This study attempts to find out the best-fit probability distribution function to low flows using... more This study attempts to find out the best-fit probability distribution function to low flows using the up-to-date data of intermittent and non-intermittent rivers in four hydrological basins from different regions in Turkey. Frequency analysis of D = 1-, 7-, 14-, 30-, 90- and 273-day low flows calculated from the daily flow time series of each stream gauge was performed. Weibull (W2), Gamma (G2), Generalized Extreme Value (GEV) and Log-Normal (LN2) are selected among the 2-parameter probability distribution functions together with the Weibull (W3), Gamma (G3) and Log-Normal (LN3) from the 3-parameter probability distribution function family. Selected probability distribution functions are checked for their suitability to fit each D-day low flow sequence. LN3 mostly conforms to low flows by being the best-fit among the selected probability distribution functions in three out of four hydrological basins while W3 fits low flows in one basin. With the use of the best-fit probability dist...
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Papers by Mehmet Ishak Yuce