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Öğe A multiseries stochastic model for synthetic monthly flows(Taylor & Francis Ltd, 2022) HaktanIr, Tefaruk; Kara, Meltem Bircan; Acanal, NeseA new multiseries stochastic model is developed that takes n-year-long monthly stream flows observed at as many as 20 stations in a group and computes N-year-long synthetic monthly flows for up to 10 000 years. Initially, any series that exhibit trends with a 99% confidence level are detrended. The monthly flows of each observed series are transformed to standard-normal variates, and a variate is related to those of the other series of the same month, those of the previous month of all series, the lag-one moving-average component, and the random component. 2 M parameters of each series are iteratively computed by the least squares method, such that the variance of the random component determined using the observed variates and those computed by the model equals the variance given by the model. The model was applied to five groups in Anatolia. The relevant peculiarities of the observed and synthetic flows were in harmony.Öğe A study on three different hydropower operation rules by monthly and daily time steps(Ice Publishing, 2021) HaktanIr, Tefaruk; Aydemir, Alper; Acanal, NeseOperation simulation models are developed for monthly and daily time steps for computing the hydroelectric energy and its financial benefits in an economic life by three different operation policies: steady-rate, three-shift and pumped-storage rules. The pump is operated during the night and consumes low-cost energy. The resulting computer programs, three on monthly and three on daily steps, are applied to the Yamula dam - which is a fairly large dam generating energy, located in the Inland Anatolia region of Turkey - over a period of 35 years using the gauged daily stream flows and daily pan evaporations. The results indicate that the pumped storage is more profitable than the other two rules aside from the intangible benefits of regulating the within-day fluctuations of demand for electrical energy. Another result is that both the average annual energy and the financial benefits given by the three rules computed by the monthly time steps are about 1-2% greater than those given by the daily time steps. This study is the first one comparing all these three operation schemes quantitatively in a realistic way both in monthly and daily time steps.Öğe An Experimental Study for Radial-Gated Ogee Spillway Discharge and Comparison with Other Model Studies(World Scientific and Engineering Academy and Society, 2024) HaktanIr, Tefaruk; Bor, ErolThe book "Design of Small Dams" is a renowned reference publication used for the design of dams in America and it is commonly used in Turkey as well. Flood spillways of many dams are ogee profile radial-gated weirs, and accurate calculation of discharges passing over a partially open radial-gated ogee spillway is important in flood routing computations. Because each spillway and its appurtenant structures have geometrical and hydraulic properties peculiar to their own, a generalizable method for calculating the discharge over a partially open radial-gated spillway should not be realistic. Therefore, many laboratory experimental studies are done both in America and in Turkey for more accurate calculation of spillway discharge of dams individually. With the objective of comparing the results of these studies and the method given in that book another experimental study is performed as summarized in this paper. For this purpose, experiments for the partially open radial gate in a laboratory setup having a 95 mm high, 10 cm wide ogee spillway model with an adjustable radial gate of proportionate dimensions both placed in a 5 meter long, 10 cm wide and 30 cm high channel are done with many combinations of flow rates and gate openings as allowed by the physical dimensions of the open channel setup available in our laboratory and the maximum flow rate its pump can generate. Taking a scale ratio of 1/100, the relative differences of the discharge coefficients given in the above-mentioned book from the experimental discharge coefficients measured in this study for the same configurations are found to be between +3% and +34%. Although the discharge coefficients determined by this experimental study are not too deviant from those obtained from 15 laboratory model studies done by the United States Bureau of Reclamation and the United States Army Corps of Engineers in America and seven such studies done by the State Water Works in Turkey, it is concluded that the discharge – head relationship of a radial-gated spillway of a dam should be determined by a laboratory experiment on a model of not too small a scale, and a generalized method cannot be applicable to all spillways in the world as a whole. © 2024, World Scientific and Engineering Academy and Society. All rights reserved.Öğe Computation of Maximum-Likelihood Parameters of the Generalized Logistic Distribution by Three-Step Newton-Raphson Algorithm(Springer, 2022) Acanal, Nese; HaktanIr, TefarukThe skewness coefficient (G) of the generalized logistic (GLO) distribution is a function of its shape parameter (a) only. Both the methods of probability-weighted moments and maximum-likelihood (ML) mostly yield magnitudes for the shape parameter much different from that by the method of moments, the gap narrowing with increasing length of the sample series. The computation of ML parameters by the conventional Newton-Raphson method is problematic with no solution for a nonnegligible number of sample series. Here, the three-step Newton-Raphson algorithm, which was previously proposed for the generalized extreme values distribution, is adapted to the GLO distribution, and on many recorded annual flood peaks and annual maximum rainfalls series and through a comprehensive Monte-Carlo experiment it is shown to improve the rate of convergent solutions considerably.Öğe Discharge Coefficients for Radial-Gated Ogee Spillways by Laboratory Data and by Design of Small Dams(Turkish Chamber Civil Engineers, 2021) HaktanIr, Tefaruk; Khalaf, Mohammed A.Using the measured data on 15 laboratory models in USA, six models and one prototype in Turkey, the discharge coefficients (C's) of radial-gated ogee spillways for various gate openings and lake water surface elevations are computed. Comparison of these C's for 22 spillways with the ones given by Figure 9-31 of Design of Small Dams does not show close agreements. It is determined that C depends on both the angle O and the ratio d/H-1, rather than O only where d and H-1 are the gate opening and the upstream head, and statistically significant regression equations are computed individually for each one of 22 cases.Öğe Göl Su Seviyesi Tahmininde Alt Bant Ayrıştırma Tekniklerinin Performanslarının İncelenmesi(Erciyes Üniversitesi, 2022) Latifoğlu, Levent; HaktanIr, TefarukBu çalışmada, doğal bir gölde ortalama su seviyesinin bir aydan altıncı aya kadar olan aylık ileri tahmini için hibrit yöntemler geliştirilmiştir. Göl su seviyesi verileri Ayrık Dalgacık Dönüşümü (DWT), Ampirik Kip Ayrıştırma (EMD), Tekil Spektrum Analiz (SSA) teknikleri kullanılarak ön işleme tabi tutulmuştur ve elde edilen bu alt bant sinyalleri Yapay Sinir Ağlarına (YSA) giriş verileri olarak uygulanmıştır. Böylece üç farklı hibrit model elde edilmiş olup bu modellerin tahmin performansı analiz edilmiştir. Elde edilen sonuçlara göre, su seviyesi verilerine uygulanan ön işleme yöntemleri ile elde edilen hibrit yaklaşımların model performansını iyileştirdiği gözlemlenmiştir ve EMD-ANN ve SSA-ANN hibrit modellerinin bir ila altı aylık bir tahmin dönemi için ortalama aylık göl suyu seviyelerini ANN ve DWT-ANN modeline göre daha iyi tahmin ettiği görülmüştür.Öğe Simulation Models for Hydro-Electric Energy by Steady-Rate and Night-Shift-Pumped-Storage Operations(Turkish Chamber Civil Engineers, 2023) HaktanIr, Tefaruk; Aydemir, AlperNew operation simulation models for hydroelectric energy and its financial benefit over an N-year period in daily time steps by the steady-rate and the open-loop night-shift-pumped -storage rules are developed. These models are applied on 11 existing dams in Turkiye, which reflect a wide range of hydrologic and hydraulic peculiarities, for regulations between 90% through 40% and the outputs are compared. Regulation is the ratio of (outflow for energy generation, hm3/day) / (average inflow, hm3/day). The present worth of energy benefits and of that of pumping costs computed with a discount rate of 9.5% over a 35-year period yield that the night-shift pumped-storage operations are more profitable than the steady-rate rule. Finally, generalized regression equations for average annual produced energy and for present worth of net benefits by both operation rules against statistically significant explanatory variables are developed using the results of these 11 dams, which are all meaningful by relevant statistical criteria.Öğe Versions of the drainage area ratio method for transfer of daily or monthly stream flows(Emerald Group Publishing Ltd, 2023) HaktanIr, Tefaruk; Aydemir, Alper; Acanal, NeseBy the drainage-area ratio method, the daily or monthly flows gauged at a nearby station are transferred to an ungauged section where a dam is to be built by multiplying them by the real number resulting from raising the ratio of the drainage areas of the dam section and of the station to an exponent (n). Commonly n is taken as 1. First, using the daily flows of two stations nearby the dam section on the same stream or on a neighboring stream, having a common N-year long gauging record, it is proposed that 365 linear regressions be fitted to N pairs of 365 daily flows, and relating them to the drainage area ratios, daily flows at the dam section be computed using 365 n's each belonging to a day. Next, by the same analytical model applied to the monthly flows, 12 monthly flows are transferred to the dam section. Five versions of the drainage-area ratio method, three of which with constant exponents, are investigated, and the last one with n = 1 is found to be relatively the worst.
