Forecasting daily streamflow discharges using various neural network models and training algorithms

WOS: 000441994400049Streamflow forecasting based on past records is an important issue in both hydrologic engineering and hydropower reservoir management. In the study, three artificial Neural Network (NN) models, namely NN with well-known multi-layer perceptron (MLPNN), NN with principal component analyses (PCA-NN), and NN with time lagged recurrent (TLR-NN), were used to 1, 3, 5, 7, and 14 ahead of daily streamflow forecast. Daily flow discharges of Haldizen River, located in the Eastern Black Sea Region, Turkey the time period of 1998-2009 was used to forecast discharges. Backpropagation (BP), Conjugate Gradient (CG), and Levenberg-Marquardt (LM) were applied to the models as training algorithm. The result demonstrated that, firstly, the forecast ability of CG algorithm much better than BP and LM algorithms in the models; secondly, the best performance was obtained by PCA-NN and MLP-NN for short time (1, 3, and 5 day-ahead) forecast and TLR-NN for long time (7 and 14 day-ahead) forecast

The effects of nourishment material size, wave and berm heights on artificial nourishment

7th International Conference on the Mediterranean Coastal Environment, MEDCOAST 2005 -- 25 October 2005 through 29 October 2005 -- Kusadasi -- 105144Coastal erosion is one of the most important problems of beaches. Traditional methods, including groins, detached breakwaters, revetments and seawalls, can be effective at local scale and generally cause erosion problems in the vicinity (especially at the down drift sides) of the coasts on which they are applied, while protecting the coasts near them. Artificial beach nourishment is one of the modern methods to be employed in protecting coasts from erosion. The performance of a nourishment project is generally determined by percent remaining material (the ratio of material volume remained at a time to the total material volume used in the nourishment). This ratio (M) depends on various wave, coast and material parameters. In this study, the results of a series of experimental studies, performed to study the effects of wave height (H), nourishing berm height (B) and nourishment material size (D) on M are presented. Experimental studies were performed at the Hydraulic Laboratory Basin, with the dimensions 30*12*1.2 m, in the Civil Engineering Department of Karadeniz Technical University (KTU), Trabzon. The initial bed slope (m=1/15) and wave period (T=1.2s) were constant for each experiment. The length and width of nourishing berm were 2.15 m and 0.30 m. The duration of an experiment was t=90 minutes. During each experiment, bed profiles were measured at 5, 10, 20, 30, 45, 60 and 90 minutes. The measuring area was divided 20*20 cm measuring grids. The remaining material volume and remaining ratio were calculated by using the results of the measurements. Three kinds of material (D=0.18, 0.40 and 0.80 mm), three wave heights (H=4.0, 5.5 and 7.0 cm) and two berm heights (B=5 and 8 cm) were employed. According to the results of the experiments, M decreases with H. This decrease is especially significant for fine material (D=0.18mm). For medium (D=0.40 mm) and coarse (D=0.80 mm) material, M values also significantly decrease for high waves (H=7 cm), however, for medium (H=5.5 cm) and small (H=4 cm) waves, the changes in M values are small. For all wave and berm conditions, M increases with D and B. But, the dependence of M to B is less than that to D

Energy situation and renewables in Turkey and environmental effects of energy use

The effects on global and environmental air quality of pollutants released into the atmosphere from fossil fuels in power plants provide strong arguments for the development of renewable energy resources. Clean, domestic and renewable energy is commonly accepted as the key for future life, not only for Turkey but also for the world. In this regard, the objective of this paper is to present a review of the energy situation, technical and economical potential and utilization of renewables, including hydraulic energy, biomass energy, solar energy, wind energy and geothermal energy, in Turkey and then concerned with greenhouse gas emissions status, especially in air pollution, and environmental impacts of renewable energy sources. The renewable energy potential of the country, their present utilization, and greenhouse gas emissions status are evaluated based on the available data. The present paper shows that there is an important potential for renewables in Turkey and making use of renewable energy and energy efficiency resources to provide energy services to the electricity consumers can provide significant environmental benefits for Turkey. © 2007 Elsevier Ltd. All rights reserved