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Lateral intakes are very important for diverting a portion of the river flow and providing the proper flow depth. In cases where small dams are used to operate and control the river's water level for the intake and to meet downstream water needs, the opening and closing of the dam gates before the construction of the intake and during its operation are important. In the current study, the problem of reducing the water head in the intake basin of the Hemmat dam pumping station, especially in the seasons of low water and the accumulation of sediment in the intake inlet of the Hemmat dam located in the Khuzestan province of Iran, has been investigated. Focusing on different arrangements of opening and closing gates, using a spur dike and flow rates of 143, 100, 62, 32, and 12 m3/s to investigate velocity changes and the depth of flow at the water inlet, computational fluid dynamics (CFD) simulations were done. With the spur dike, the water intake efficiency is increased by 384% compared to the project's current state (operation without any flow control structure), and the hydraulic conditions resulting in sedimentation are eliminated. The flow depth of the water intake channel, with the spur dike, increases by 10% compared to the condition without it. It is worth mentioning that gate management also affects water supply efficiency. The results of the current study are a good example of the successful application of computer simulations for sustainable systems engineering. [ABSTRACT FROM AUTHOR]

A river's planform pattern changes due to erosion of banks and the bed near the outer bend. The primary cause of these planform changes is the formation of helical flow patterns in response to centrifugal forces. Uncontrolled bed scouring can have a negative impact on the river's geometry, aquatic habitat, and floodplains. To alleviate this scouring, various structures, such as spur dikes, can be placed at any accessible location along the bend. The current research was accomplished by installing two meandering models with different sinuosities of 1.3 and 1.5, in a flume. For both sinuosities, the maximum bed scour was observed at an approximate angle of 45° relative to the bend apex. Thus, the main objective was to control this maximum scour by installing spur dikes with varying porosities, ranging from 0% to 75%, at five locations along the outer bend. The spur dikes were found to divert the helical flow regime away from the outer bend and protect the riverbed from severe scouring. However, the results show that the effectiveness of spur dikes decreases as sinuosity increases. Furthermore, for both meandering models, a 50% permeable spur dike installed at the +30° location yielded the best performance. Finally, a regression-based predictive equation is proposed to determine the proportion of scouring around a spur dike in a meandering channel. [ABSTRACT FROM AUTHOR]

Spur dikes are river training structures that have been extensively used worldwide for towards enhancing flood control and the stability of embankments and riverbanks. However, scour around spur dikes can be a major problem affecting their stability and hydraulic performance. The precise computation of temporal scour depth at spur dikes is very important for the design of economical and safe spur dikes. This study focuses on experimentally assessing the temporal variation of scour depth around a vertical wall spur dike and identifying the parameters, which mostly influence spur dike performance for a channel bed surface comprised of sand-gravel mixtures. In the current study, the authors did physical experiments in a flume based study to obtain new data, aimed at deriving a new predictive model for spur dike scour and comparing its performance to others found in the literature. It was found that the dimensionless temporal scour depth variation increases with an increase in (i) the threshold velocity ratio, (ii) the densimetric Froude number of the bed surface sediment mixture, (iii) the flow shallowness (defined as the ratio of the approach flow depth, y , to the spur dike's transverse length, l), and (iv) the flow depth-particle size ratio. It is also concluded that the temporal scour depth variation in the sediment mixture is influenced by the non-uniformity of sediment and decreases with an increase in the non-uniformity of the sediment mixture. A new mathematical model is derived for the estimation of temporal scour depths in sand-gravel sediment mixtures. The proposed equation has been calibrated and validated with the experimental data, demonstrating a good predictive capacity for the estimation of temporal scour depth evolution. [ABSTRACT FROM AUTHOR]

Abstract: Three-dimensional turbulent flow field was measured around an experimental spur dike by using a micro-acoustic Doppler velocimeter. Time fractions of turbulent burst events including outward interaction, ejection, inward interaction, and sweep were analyzed in each quadrant at the neighbor of the dike before and after the formation of scour hole. Over 80% of burst events near the bed have lower-order of magnitudes for both flat and scoured bed surfaces. Ejections and sweeps are prevalent before the local scour was initiated, and then outward interactions are dominant after the scour hole was formed. Conditional Reynolds stresses and high-order moments of turbulent velocities were analyzed along the thalweg. The magnitudes of u′–w′ pair were much larger than those of v′–w′ pair in the scour zone. Among four burst events, ejections and sweeps are the higher order events contributing to the Reynolds stresses. Since sediment entrainment and transport are closely associated with turbulent bursts near bed, the development of scour hole greatly depends on the higher order event near the bed. [Copyright &y& Elsevier]

Abstract: In this paper results of experimental study on scour and flow field around a T-shape spur dike in a 90 degree channel bend are presented. Experiments were conducted in a laboratory channel to measure the variations of bed topography under a clear water condition. The three dimensional flow field was measured by an Acoustic Doppler Velocimeter in a scour hole due to a T-shape spur dike. It was found that by increasing the Froude number and length of spur dike the amount of scour increases. Increasing the wing length of spur dike decreases the scour. The amount of scour at the upstream of spur dike is much more as compare to that at the downstream of spur dike. By increasing the wing length of spur dike the zone of flow separation expands. As a result the sizes of vortex increase. Details of flow field are also addressed in the paper. [Copyright &y& Elsevier]

Abstract: Spur dike is an important element in river training that creates rapid variations in flow field, sediment transport and bed topography. The mechanism of flow and sediment transport in a channel bend is very complex, especially when a spur dike is constructed in a bend. Most of previous investigations on flow behavior and scour around spur dike were carried out in straight channels. In this paper results of experiments on flow field and scour around a spur dike in a 90 degree channel bend are presented. Sand with uniform grain size was used as the bed material. Experiments were conducted for different locations and different lengths of spur dikes at the bend with different values of discharge. The three dimensional flow fields around a spur dike were investigated. The maximum depth of scour was correlated to the Froude numbers, lengths and the locations of spur dike in the bend. [Copyright &y& Elsevier]