Evaluation and Prediction of the Scour Depth of Bridge Foundations with HEC-RAS Numerical Model and Empirical Equations (Case Study: Bridge of Simineh Rood Miandoab, Iran)

Today, scouring is one of the major issues in the river and coastal engineering. Each year, many bridges around the world are destroyed due to neglecting hydraulic elements. In the present study, scour depth around the piers of the Simineh Rood Bridge in Miandouab, Iran were investigated using empirical relationships and the HEC-RAS numerical model, and the results are compared with each other. Firstly, a hydraulic software model was created from the river where the bridge was located using field data. Then, by entering the scouring data of bridge piers for discharges with a return period of 5 to 1000 years, changes in flow discharge were investigated for scouring around the middle and lateral sides of the bridge. Results of the empirical equations showed that some of the equations are not sensitive to increases in flow discharge, and for each return period, the results are near each other. Also, numerical model results showed that with an increase in discharge, scouring increases in the bridge’s middle and lateral piers. In all discharges, the first and the seventh pier had the lowest and highest scour depth, respectively. Also, the left and right abutments are heavily influenced by increasing discharge. In discharges with a return period of 1000 years, the scour depth was 11.19 and 6.32 m. The Frohlich method is not as sensitive as the CSU method to an increase in discharge when calculating scour depth. Finally, the results of the numerical model were compared with experimental empirical equation

Characteristics of free and submerged hydraulic jumps over different macroroughnesses

AbstractThe present study deals with numerical simulations of the free and submerged hydraulic jumps over different shapes of roughness in various roughness arrangements and different Froude number conditions. The models were studied using three roughness shapes, i.e. triangular, square and semi-oval for 0.2 < T/I < 0.5, where T and I are height and distance of roughness, respectively. The results showed that the numerical model is fairly well able to simulate the free and submerged jump characteristics. The effect of roughness plays a role in the reduction of the relative maximum velocity which is greater in the submerged jump. The thickness of the boundary layer for both free and submerged jumps decreases with increasing the distance between the roughnesses. Triangular macroroughness has a significant effect on the length of the jump and shortest length with respect to the other shapes. The reduction in the submerged depth ratio and tailwater depth ratio depends mainly on the space of the roughnesses. The highest shear stress and energy loss in both jumps occur in a triangular macroroughness (TR) with T/I = 0.50 compared to other ratios and modes. The numerical results were compared with previous studies and relationships with good correlation coefficients were presented for the mentioned parameters

Numerical Simulations of the Flow Field of a Submerged Hydraulic Jump over Triangular Macroroughnesses

The submerged hydraulic jump is a sudden change from the supercritical to subcritical flow, specified by strong turbulence, air entrainment and energy loss. Despite recent studies, hydraulic jump characteristics in smooth and rough beds, the turbulence, the mean velocity and the flow patterns in the cavity region of a submerged hydraulic jump in the rough beds, especially in the case of triangular macroroughnesses, are not completely understood. The objective of this paper was to numerically investigate via the FLOW-3D model the effects of triangular macroroughnesses on the characteristics of submerged jump, including the longitudinal profile of streamlines, flow patterns in the cavity region, horizontal velocity profiles, streamwise velocity distribution, thickness of the inner layer, bed shear stress coefficient, Turbulent Kinetic Energy (TKE) and energy loss, in different macroroughness arrangements and various inlet Froude numbers (1.7 < Fr1 < 9.3). To verify the accuracy and reliability of the present numerical simulations, literature experimental data were considered

Evaluation of Scour Depth around Bridge Piers with HEC-RAS (Case study: Bridge of Simineh Rood, Miandoab, Iran)

In the present study, the scour depth around bridge piers of Simineh Rood Miandoab was investigated through HEC-RAS model using with two of CSU and Froehlich method (two methods of HEC-RAS software) for the discharge with a different return period. For this purpose, first, using a field data, a hydraulic model of the river range, where the bridge is located was created in the software medium. Then for discharges with the return period of 5 to 1000 years, the change in flow discharge for scouring around the middle and lateral sides piers of the bridge was investigated. The results showed that with increasing the discharge (increasing the flow velocity), the flow interference are increased and the amount of scouring in the middle of the piers is reduced relative to the sides. Moreover, for the discharge with a return period of 5 to 40 years, no scouring is observed in the bridge sides. Whereas for the discharge with a return period of 50 to 1000 years, the scouring around the the bridge sides increases significantly. For different return periods, in both CSU and Frohlich methods, pier number 7 has the highest scour and pier number 1 has the lowest value. The Frohlich method is not as sensitive as the CSU in calculating the scour depth compared with increase discharge, and approximately 20% are different in calculating the scour depth. Such difference could be attributed to the applying the pier shape coefficient, the bed conditions, as well as the coefficient of sediment particles in the CSU method

بررسی تأثیر تنگ شدگی های قائم ورودی بر روی مشخصات هیدرولیکی شیب شکن قائم با استفاده از مدل عددی

International audienceVertical drops are used in irrigation and drainage networks and surface run-off collection channels. In the present study, the impact of vertically constricted entrance on hydraulic characteristics of drops is numerically study utilizing FLOW-3D®. In the first step, for choosing the best model of turbulence, two types of turbulence models k -e and RNGk -e were used. In the next step, four constriction layouts of S/H=0.312, 0.500, 0.875, 2 (ratio of constriction distances to drop height) were utilized as long as the case without any constriction. The results showed that the RNGk -e turbulence model has less relative error percentage and RMSE in comparison with k -e model and more efficiency to simulate hydraulic characteristics on drops. Based on the obtained results, it was observed that the vertically constricted entrance would result in decreasing the relative depth of water in the pool, the depth of downstream water and normal residual energy by 42.31%, 47.23%, and 23.59%, respectively.Presence of entrance constriction results in increasing the velocity at drop edge and thus the kinetic energy decreases by flow turbulence increment caused by divided jet falls and production of more airwater mixing region. Some relations are proposed to calculate pond depth ratio, downstream depth ratio and normal residual energy with acceptable correlation coefficients which are in accordance with those of other researchers

Functioning of the multilinear lag-cascade flood routing model as a means of transporting pollutants in the river

AbstractThe purpose of this paper is to use the application of the multilinear lag cascade model as a contaminant transport model through river networks. Monocacy River and Antietam Creek data, which were collected by USGS with different reach lengths and discharge conditions, have been used in the current study. It was found that the multilinear discrete lag-cascade (MDLC) model is capable of reconstructing contaminant breakthrough curves. A complete study was performed to estimate the reach length for use in the accurate simulation, and it was concluded that by assuming a uniform flow through the reach, the length unit should be obtained by applying Pe = 12. Moreover, by using temporal moment matching, explicit relationships for MDLC model parameters (k, n, and τ) and based on conventional advection-dispersion equation (ADE) parameters (D, u, x) were extracted. MDLC parameters of the field breakthrough curves were extracted, and it was found that the increase of Pe number caused an increase in delay time and the number of cascades. However, the residence time was obtained to be fixed. Additionally, by assuming the dispersivity parameter (D/u) is constant, the changes in the MDLC parameters were investigated by velocity variation, and new relationships were proposed to estimate the parameters under different hydraulic conditions. Using presented equations provided in this study for residence time (k), cascade number (n), and delay time (τ), the sensitivity analysis was performed, and it was found that the parameters of velocity (u), dispersion coefficient (D), and velocity (u) have the most important effect in calculation of them, respectively

Estimation of Actual Evapotranspiration Using the Remote Sensing Method and SEBAL Algorithm: A Case Study in Ein Khosh Plain, Iran

The aim of this study was to estimate evapotranspiration (ET) using remote sensing and the Surface Energy Balance Algorithm for Land (SEBAL) in the Ilam province, Iran. Landsat 8 satellite images were used to calculate ET during the cultivation and harvesting of wheat crops. The evaluation using SEBAL, along with the FAO-Penman–Monteith method, showed that SEBAL has a sufficient accuracy for estimating ET. The values of the Root Mean Square Error (RMSE), Mean Absolute Percentage Error (MAPE), Mean Bias Error (MBE), and correlation coefficient were 0.466, 2.9%, 0.222 mm/day, and 0.97, respectively. Satellite images showed that rainfall, except for the last month of cultivation, provided the necessary water requirements and there was no requirement for the use of other water resources for irrigation, with the exception of late May and early June. The maximum ET on the Ein Khosh Plain occurred in March. The irrigation requirements showed that the Ein Khosh Plain in March, which witnessed the highest ET, did not experience any deficiency of rainfall that month. However, during April and May, with maxima of 50 and 70 mm, respectively, water was needed for irrigation. During the plant growth periods, the greatest and least amount of water required were 231.23 and 19.47 mm/hr, respectively

Prediction of Hydraulic Jumps on a Triangular Bed Roughness Using Numerical Modeling and Soft Computing Methods

This study investigates the characteristics of free and submerged hydraulic jumps on the triangular bed roughness in various T/I ratios (i.e., height and distance of roughness) using CFD modeling techniques. The accuracy of numerical modeling outcomes was checked and compared using artificial intelligence methods, namely Support Vector Machines (SVM), Gene Expression Programming (GEP), and Random Forest (RF). The results of the FLOW-3D® model and experimental data showed that the overall mean value of relative error is 4.1%, which confirms the numerical model’s ability to predict the characteristics of the free and submerged jumps. The SVM model with a minimum of Root Mean Square Error (RMSE) and a maximum of correlation coefficient (R2), compared with GEP and RF models in the training and testing phases for predicting the sequent depth ratio (y2/y1), submerged depth ratio (y3/y1), tailwater depth ratio (y4/y1), length ratio of jumps (Lj/y2*) and energy dissipation (ΔE/E1), was recognized as the best model. Moreover, the best result for predicting the length ratio of free jumps (Ljf/y2*) in the optimal gamma is γ = 10 and the length ratio of submerged jumps (Ljs/y2*) is γ = 0.60. Based on sensitivity analysis, the Froude number has the greatest effect on predicting the (y3/y1) compared with submergence factors (SF) and T/I. By omitting this parameter, the prediction accuracy is significantly reduced. Finally, the relationships with good correlation coefficients for the mentioned parameters in free and submerged jumps were presented based on numerical results