A research on the estimation of coefficient roughness in open channel applying entropy concept

Choo, Yeon Moon; Yun, Gwan Seon; Choo, Tai Ho

doi:10.1007/s12665-018-7809-4

Cited by 7 publications

(7 citation statements)

References 9 publications

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“…The discharge estimation of water into open channels is a well-known and complicated problem for both artificial channels such as irrigation systems, water supply systems etc., but even more complicated for natural open channels such as rivers, streams etc., due to their high variability. Until now, the majority of researchers are still using Manning roughness coefficient in terms of hydrodynamics, hydraulics, hydrology and water resource engineering (Choo et al 2018).…”

Section: Introductionmentioning

confidence: 99%

“…In general, the procedure for selecting n values is quite complex and usually requires advanced judgment and expertise (Bahramifar et al 2013). Moreover, one of the best methods is to have field observations from an experienced hydraulic engineer (Choo et al 2018) but such method is both time consuming and costly. In this regard, and because it is an empirically derived coefficient, which is dependent and affected on many factors (Chow 1959), the scientific community has shown in the past great interest in various methods for selecting appropriate values of roughness coefficient for discharge estimation in an open channel (Cowan 1956;Limerinos 1970;Shiono et al 1999;Mailapalli et al 2008;Khatua et al 2012;Dash & Khatua 2016;Pradhan & Khatua 2018).…”

Section: Introductionmentioning

confidence: 99%

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Discharge estimation for trapezoidal open channels applying fuzzy transformation method to a flow equation

Samarinas

Evangelides

2021

Water Supply

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The aim of this paper is to implement the fuzzy logic theory in order to estimate the discharge for open channels, which is a well-known physical problem affected by many factors. The problem can be solved by Manning equation but the parameters present uncertainties as to their true-real values. Especially, the Manning n roughness coefficient, which is an empirically derived coefficient, presents quite high variation for different substrates. With the help of fuzzy logic and utilizing a fuzzy transformation method, it is possible to include the uncertainties of the problem in the calculation process. In this case, it is feasible to estimate the discharge, giving more emphasis on different uncertainty rates of the Manning roughness coefficient, while the rest of the parameters remain with constant or zero uncertainty level. By taking different a-cut levels, it was shown that the methodology gives realistic and reliable results, presenting with great accuracy the variations of the water discharge for trapezoidal open channels. This way, a possible underestimation or overestimation of the actual physical condition is avoided, by helping the engineers and researchers to obtain a more comprehensive view of the real physical conditions, thus making better management plans.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Discharge estimation for trapezoidal open channels applying fuzzy transformation method to a flow equation

Samarinas

Evangelides

2021

Water Supply

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“…Knowledge of the bed shear stress distribution in rivers helps with the evaluation of sediments and pollutants transport, the prediction of erosion and deposition phenomena, the estimation of morphological and geometrical changes, and the calculation of resistance coefficients [1][2][3][4][5][6][7][8][9][10][11]. It can also be useful in planning and designing stable open channels.…”

Section: Introductionmentioning

confidence: 99%

Modeling Bed Shear Stress Distribution in Rectangular Channels Using the Entropic Parameter

Mirauda

Russo

2020

Entropy

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The evaluation of bed shear stress distribution is fundamental to predicting the transport of sediments and pollutants in rivers and to designing successful stable open channels. Such distribution cannot be determined easily as it depends on the velocity field, the shape of the cross section, and the bed roughness conditions. In recent years, information theory has been proven to be reliable for estimating shear stress along the wetted perimeter of open channels. The entropy models require the knowledge of the shear stress maximum and mean values to calculate the Lagrange multipliers, which are necessary to the resolution of the shear stress probability distribution function. This paper proposes a new formulation which stems from the maximization of the Tsallis entropy and simplifies the calculation of the Lagrange coefficients in order to estimate the bed shear stress distribution in open-channel flows. This formulation introduces a relationship between the dimensionless mean shear stress and the entropic parameter which is based on the ratio between the observed mean and maximum velocity of an open-channel cross section. The validity of the derived expression was tested on a large set of literature laboratory measurements in rectangular cross sections having different bed and sidewall roughness conditions as well as various water discharges and flow depths. A detailed error analysis showed good agreement with the experimental data, which allowed linking the small-scale dynamic processes to the large-scale kinematic ones.

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“…The accuracy, stability, and robustness of a hydrodynamic model are affected not only by the detailed basic data used for model development but also by the use of suitable model parameters. Among various model parameters, Manning's roughness coefficient (n), an integrated dimensionless number, is considered a key parameter that has a significant influence on the flow discharge and water level (Choo et al, 2018;Li & Zhang, 2001). It also reflects the influence of flow resistance, which has a real physical interpretation (Chow, 1959;Cowan, 1956).…”

Section: Introductionmentioning

confidence: 99%

“…(Arcement & Schneider, 1989; CONTACT Ziwu Fan zwfan@nhri.cn Barnes, 1967;Chow, 1959Chow, , 1988. However, the value of this empirical parameter not only depends on various factors such as river irregularities, cross-section variations, meandering, vegetation, obstructions, and bed material, but also varies with the effect of unsteadiness (Choo et al, 2018;Chow, 1959;De Doncker et al, 2009;Ding & Wang, 2005). Further, these resistance factors vary along the river, making it difficult to quantify the n values.…”

Section: Introductionmentioning

confidence: 99%

Improved method for identifying Manning’s roughness coefficients in plain looped river network area

Yang

et al. 2020

Engineering Applications of Computational Fluid Mechanics

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A research on the estimation of coefficient roughness in open channel applying entropy concept

Cited by 7 publications

References 9 publications

Discharge estimation for trapezoidal open channels applying fuzzy transformation method to a flow equation

Discharge estimation for trapezoidal open channels applying fuzzy transformation method to a flow equation

Modeling Bed Shear Stress Distribution in Rectangular Channels Using the Entropic Parameter

Improved method for identifying Manning’s roughness coefficients in plain looped river network area

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