Browsing by Author "Okan, M."

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Citation - Scopus: 1
Application of Artificial Neural Network for Predicting Peak Discharge from Breached Embankment Dam
(International Association for Hydro-Environment Engineering and Research (IAHR), 2024) Okan, M.; Bor, A.; Tayfur, G.
Estimation of peak discharge is a key parameter for risk assessment in case of dam failure, and has attracted great attention from researchers in recent years. Many formulas are available in the literature, but these cannot cover all experimental scenarios. Existing models are typically inadequate to address the complexities of dam breaches. This research attempted to predict the peak discharge in the breached embankments with an artificial neural network (ANN) model, which is effective in nonlinear problems, using datasets obtained from various dam breaches cited in the literature. The ANN model is useful in the preparation of emergency action plans since it enables prediction of peak discharge. Multilayer Perceptron (MLP) with Levenberg-Marquardt (LM) and Bayesian Regularization (BR) algorithms was used to predict peak discharges from breached embankments. The dataset was divided into three: 56% for training, 20% for validation and 24% for testing. Different scenarios were created using different input combinations. Performance evaluation was based on the root-mean squared error (RMSE), percent bias (PBIAS), determination of coefficient (R2), Nash-Sutcliffe efficiency (NSE) and RMSE-observations standard deviation ratio (RSR). A comparison of training algorithms revealed that LM showed the best performance when the best ANN was selected from 1000 networks. Volume of water above the breach bottom (Vw) had a greater effect on model performance than the depth of water above the breach bottom (Hw). The best performance was obtained when both Vw and Hw were used as input. © 2024 ISHS. All Rights Reserved.
Comparison of the Evolutions of Internal Erosion When Seepage Is at Top, Bottom or Middle Part of the Homogeneous Earth-Fill Dam Built With Fine Sand and Clay Mixture
(International Association for Hydro-Environment Engineering and Research (IAHR), 2024) Güney, M.S.; Dumlu, E.; Okan, M.; Kalyoncu, Y.
One of the most prominent failure reasons for earth-fill dams is internal erosion resulting from piping. This failure mode may cause irreversible weakened structural integrity, loss of properties, and even loss of lives. Therefore, it is important to understand the breaching process due to piping by providing reliable data for the decision-makers in case of emergency. This study was supported by the Scientific and Technological Research Council of Turkey with project number 119M609 and involves experimental investigation on piping under three different weak zone scenarios to examine the breach process and provide the data for more realistic numerical evaluations. The experiments were conducted in the hydraulic laboratory of Izmir University of Economics and Dokuz Eylul University. The initiation of piping was triggered from seepage in weak layers at the bottom, middle, and upper parts, along the centerline of homogenous earth-fill dams in a rectangular flume. As a result of the experiments, the magnitude of the peak discharges and their durations as well as the eroded breach areas were found to be affected by the locations of the seepage and initial water heads acting on the weak zones. Also, in the experiments, at the beginning of the breaching, initial cascading surface flow resulted in sheet and rill erosion. © 2024 ISHS. All Rights Reserved.