Papers by Muhammet Ikbal Yilmaz
Assessing the main drivers of low flow series in Turkey
Natural Hazards
Predicting monthly streamflow using artificial neural networks and wavelet neural networks models
Modeling Earth Systems and Environment
Improving predicting methods for streamflow series is an important task for the water resource pl... more Improving predicting methods for streamflow series is an important task for the water resource planning, management, and agriculture process. This study demonstrates the development and effectiveness of a new hybrid model for streamflow predicting. In the present study, artificial neural networks (ANNs) coupled with wavelet transform, namely Additive Wavelet Transform (AWT), are proposed. Comparative analyses of Discrete wavelet transform (DWT) based ANN and conventional ANN techniques with the proposed method were presented. The analysis of these models was performed with monthly streamflow series for four stations on the Çoruh Basin, which is located in northeastern Turkey. The Bayesian regularization backpropagation training algorithm was employed for the optimization of the ANN network. The predicted results of the models were analyzed by the root mean square error (RMSE), Akaike information criterion (AIC), and coefficient of determination (R2). The obtained revealed that the proposed hybrid model represents significant accuracy compared to other models, and thus it can be a useful alternative approach for predicting studies.
Impact of climate change on meteorological and hydrological droughts for Upper Coruh Basin, Turkey
Natural Hazards, 2022
Drought is a multifaceted natural hazard that occurs in almost every component of the hydrologica... more Drought is a multifaceted natural hazard that occurs in almost every component of the hydrological cycle. This study investigated future hydro-meteorological droughts using climate projections from an ensemble of 13 European Coordinated Regional Downscaling Experiments (CORDEX) domain outputs under two alternative scenarios of representative concentration pathways (RCP 4.5 and RCP 8.5) for the 2030–2059 and 2070–2099 periods across Upper Coruh Basin, Turkey. The bias-corrected CORDEX climate projections were incorporated into the Soil and Water Assessment Tool (SWAT) hydrological model. In this study, two optimisation algorithms (the sequential uncertainty fitting algorithm of SWAT calibration and uncertainty and the shuffled complex evolution (SCE) algorithm in parameter estimation tool (PEST)) were tested for the automatic parameter calibration of a complex hydrologic model, SWAT, in the study area. Results show that SCE reached better parameter solutions than the other algorithm. This study investigated for the first time a comprehensive analysis of the projected droughts in the Upper Coruh Basin, Turkey. The standardised precipitation index and standardised streamflow index were used to evaluate the meteorological and hydrological droughts, respectively. Overall, the future annual precipitation and the maximum and minimum temperatures are projected to change from − 15.46% to 8.74%, 0.02 °C to 8.74 °C and − 2.69 °C to 5.27 °C, respectively. The results show that the frequency of hydrological drought durations will be higher under RCP4.5 and RCP8.5 during the period 2030–2059. In addition, the frequency of hydrological high-severity droughts (> ~ 5) and low-severity droughts (< ~ 2) will be more likely under RCP4.5 and RCP8.5 during the period 2030–2059 and 2070–2099, respectively. Other than this, not enough evidence exists to claim that hydrological and meteorological drought will become more significant in the twenty-first century.
Gunumuzde cok hizli gelisim gosteren bilisim teknolojilerin egitim surecinde etkin kullanilmasi, ... more Gunumuzde cok hizli gelisim gosteren bilisim teknolojilerin egitim surecinde etkin kullanilmasi, egitim-ogretim etkinliklerinin daha verimli hale getirilmesi acisindan cok onemlidir. Bilisim Teknolojileri, 2005 yilindan beri yapilandirmaci yaklasimin temel alindigi egitim sistemimizde ogretmenlerin, ogrencinin ogrenmesine rehberlik etmesindeki en onemli yardimcisidir. Bu calisma ogretmen adaylarinin teknolojiye karsi tutumlarini ve bilisim teknolojileri konusunda kendilerini ne kadar yeterli gorduklerini farkli degiskenler acisindan belirlemek amaciyla yapilmistir. Calismada TINMAZ (2004) tarafindan gelistirilen Teknoloji Algi Olcegi (T.A.O.) ve Algilanan Bilgisayar Yeterlilik Olcegi (A.B.Y.O.) kullanilmistir. Calismada dort adet bagimsiz degisken (cinsiyet, sinif duzeyi, bilgisayara sahip olma, internete sahip olma) ve iki adet bagimli degisken (algilanan bilgisayar yeterlilik duzeyi ve teknolojik algi) bulunmaktadir. Calisma 2013-2014 Egitim-Ogretim yilinda Mersin Universitesi Sin...
Water Science and Technology, 2021
This study aims to investigate the effectiveness of the low impact development (LID) practices on... more This study aims to investigate the effectiveness of the low impact development (LID) practices on sustainable urban flood storm water management. We applied three LID techniques, i.e. green roof, permeable pavements and bioretention cells, on a highly urbanized watershed in Istanbul, Turkey. The EPA-SWMM was used as a hydrologic-hydraulic model and the model calibration was performed by the well-known Parameter ESTimation (PEST) tool. The rainfall-runoff events occurred between 2012 and 2020. A sensitivity analysis on the parameter selection was applied to reduce the computational cost. The Nash-Sutcliffe efficiency coefficient (NSE) was used as the objective function and it was calculated as 0.809 in the model calibration. The simulations were conducted for six different return periods of a storm event, i.e. 2, 5, 10, 25, 50 and 100 years, in which the synthetic storm event hyetographs were produced by means of the alternating block method. The results revealed that the combination...
Journal of the Institute of Science and Technology, 2021
Flood frequency analysis is very important in the design of water structures, planning and projec... more Flood frequency analysis is very important in the design of water structures, planning and projecting of flood control. One of the important steps of flood frequency analysis is to estimate a suitable distribution model and its parameters for the data. In this study, optimization based DEoptim algorithm is proposed to estimate the parameters of probability distribution functions and is compared with the traditional maximum likelihood method (MLM) and Method of moments (MOM). Annual maximum flow data of 2 stations on the Eastern Black Sea Basin are used. Gamma, Weibull, Log-Normal, Logistic and Normal probability distributions were used to determine flood recurrences flows. To determine the most appropriate probability distribution, Kolmogorov-Smirnov (KS) test, mean square error (RMSE), Kling-Gupta efficiency coefficient (KGE), mean absolute error (MAE), Nash-Sutcliffe efficiency coefficient (NSE) and Akaike information criterion (AIC) tests were used. According to the results, it was seen that the DEoptim method is a more effective method in estimating the probability distribution function parameters compared to the MLM and MOM methods. Finally, using the most appropriate probability models, flood estimates that may occur in different recurrence periods (5, 10, 20, 50, 100, 200 and 500) were calculated and the results were discussed.
Water, 2020
Bivariate modeling and hazard assessment of low flows are performed exploiting copulas. 7-day low... more Bivariate modeling and hazard assessment of low flows are performed exploiting copulas. 7-day low flows observed, respectively, in the upper, middle and lower parts of the Çoruh basin (Turkey) are examined, considering three pairs of certified stations located in different sub-basins. A thorough statistical analysis indicates that the GEV distribution can be used to model the marginal behavior of the low-flow. The joint distributions at each part are modeled via a dozen of copula families. As a result, the Husler–Reiss copula adequately fits the joint low flows in the upper part, while the t-Student copula turns out to best fit the other parts. In order to assess the low-flow hazard, these copulas are then used to compute joint return periods and failure probabilities under a critical bivariate “AND” hazard scenario. The results indicate that the middle and lower parts of the Çoruh basin are likely to experience the largest drought hazards. As a novelty, the statistical tools used a...
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Papers by Muhammet Ikbal Yilmaz