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The spur dike groups on river systems (notes: (a). Spur dikes to improve both banks of Rhine River, USA; (b). Spur dikes to reinforce banks of Xijiang River, Guangdong, China; (c). Spur dikes as training works for navigation in Odra River, Poland).
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Concerning the clustering of spur dikes on river systems, the spacing thresholds of twin spur dikes are important parameters to influence the estimations on the impact scales of spur dike groups and the overall responses of river systems. In this study, both numerical investigations and experimental measurements are proceeded to quantify the influe...
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... fact, the health of the river system may be affected or damaged due to the limited recognition of human-being and the unscientific development program of river works [5,6]. As one of the river works, spur dikes (shown in Figure 1) are widely used in river engineering such as channel regulation, flood prevention, river diversion and beach reclamation for maintaining the desired water depth, changing the direction of main flow, protecting river bank and bed, and acquiring land resource [7][8][9][10][11][12]. In spite of different types [8,13], the spur dikes present simple structure and multiple functions, which can be regarded as the simplification of many river works [12,14]. ...
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... construction of spur dikes, the original channel becomes narrower and leads to changes in the moving characteristics of the flow current near spur dikes. In practice, spur dike exerts influences on river system usually in the form of groups as shown in Figure 1. These spur dikes (or groups) interact in a specific range, and such interaction gradually weakens beyond the critical range [2,8,[15][16][17]. ...
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... construction of spur dikes, the original channel becomes narrower and leads to changes in the moving characteristics of the flow current near spur dikes. In practice, spur dike exerts influences on river system usually in the form of groups as shown in Figure 1. These spur dikes (or groups) interact in a specific range, and such interaction gradually weakens beyond the critical range [2,8,[15][16][17]. ...
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... twin-spur-dike is the simplest spur dike group and the fundamental model regardless large-or small-scale spur dike groups, one can realize the clustering of spur dikes through establishing the calculation theory of the spacing threshold of twin spur dikes [2,17]. In this study, according to the flume experimental data, we use CFD (computational fluid dynamics) method [11,14,19,20,27] to quantitatively analyze the spacing threshold of Figure 1. The spur dike groups on river systems (notes: (a). ...
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... B, h and Q fixed (c2, c6-c9 in Table 2), the spur dike played less influence on the flow as b decreased, i.e., the S c of non-submerged twin spur dikes decreased as well. Water 2020, 12, 172 9 of 13 Figure 10b was higher than that in Figure 10a, which indicates the strong impact of B/b on the Sc/b scale. For Figure 10c, Sc/b slightly increased first and then decreased sharply with the increase of B/h as Fr and B/b fixed. ...
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... B, h and Q fixed (c2, c6-c9 in Table 2), the spur dike played less influence on the flow as b decreased, i.e., the S c of non-submerged twin spur dikes decreased as well. Water 2020, 12, 172 9 of 13 Figure 10b was higher than that in Figure 10a, which indicates the strong impact of B/b on the Sc/b scale. For Figure 10c, Sc/b slightly increased first and then decreased sharply with the increase of B/h as Fr and B/b fixed. ...
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... 2020, 12, 172 9 of 13 Figure 10b was higher than that in Figure 10a, which indicates the strong impact of B/b on the Sc/b scale. For Figure 10c, Sc/b slightly increased first and then decreased sharply with the increase of B/h as Fr and B/b fixed. It indicates that the spur dike flow was easier to recover in wide-shallow water. ...
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... results of Figure 10 are further regressed by statistical analysis software SPSS, and a general empirical formula of spacing threshold of non-submerged twin spur dikes was obtained in multiple-regression equation listed as below: Figure 10 further provides the relationships between the relative spacing threshold S c /b with the Froude number F r , the relative dike length B/b, and the section width-depth ratio B/h. As indicated in Figure 10a, S c /b slightly decreased first and then gradually increased as F r increased with fixed B/b and B/h. ...
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... results of Figure 10 are further regressed by statistical analysis software SPSS, and a general empirical formula of spacing threshold of non-submerged twin spur dikes was obtained in multiple-regression equation listed as below: Figure 10 further provides the relationships between the relative spacing threshold S c /b with the Froude number F r , the relative dike length B/b, and the section width-depth ratio B/h. As indicated in Figure 10a, S c /b slightly decreased first and then gradually increased as F r increased with fixed B/b and B/h. ...
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... results of Figure 10 are further regressed by statistical analysis software SPSS, and a general empirical formula of spacing threshold of non-submerged twin spur dikes was obtained in multiple-regression equation listed as below: Figure 10 further provides the relationships between the relative spacing threshold S c /b with the Froude number F r , the relative dike length B/b, and the section width-depth ratio B/h. As indicated in Figure 10a, S c /b slightly decreased first and then gradually increased as F r increased with fixed B/b and B/h. However, F r presents a minor influencing factor concerning the narrow range of S c /b values. ...
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... relation of S c /b-F r can be approximately described by concave quadratic function. For Figure 10b, S c /b increased first and then decreased slightly with B/b increasing under fixed F r and B/h. The relation between B/b and S c /b was approximated by the convex quadratic function. ...
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... relation between B/b and S c /b was approximated by the convex quadratic function. Moreover, the value range of S c /b in Figure 10b was higher than that in Figure 10a, which indicates the strong impact of B/b on the S c /b scale. For Figure 10c, S c /b slightly increased first and then decreased sharply with the increase of B/h as F r and B/b fixed. ...
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... relation between B/b and S c /b was approximated by the convex quadratic function. Moreover, the value range of S c /b in Figure 10b was higher than that in Figure 10a, which indicates the strong impact of B/b on the S c /b scale. For Figure 10c, S c /b slightly increased first and then decreased sharply with the increase of B/h as F r and B/b fixed. ...
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... the value range of S c /b in Figure 10b was higher than that in Figure 10a, which indicates the strong impact of B/b on the S c /b scale. For Figure 10c, S c /b slightly increased first and then decreased sharply with the increase of B/h as F r and B/b fixed. It indicates that the spur dike flow was easier to recover in wide-shallow water. ...
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... results of Figure 10 are further regressed by statistical analysis software SPSS, and a general empirical formula of spacing threshold of non-submerged twin spur dikes was obtained in multiple-regression equation listed as below: ...
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... results of Figure 10 are further regressed by statistical analysis software SPSS, and a general empirical formula of spacing threshold of non-submerged twin spur dikes was obtained in multiple-regression equation listed as below: ...
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... examine the fitting effect of Equation (3), the calculated values S c for cases c1-c13 from Equation (3) were compared with corresponding CFD results and shown in Figure 11. Good agreement between two data sets illustrated a satisfactory fitting effect of Equation (3). ...
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... agreement between two data sets illustrated a satisfactory fitting effect of Equation (3). Similarly, in a previous study [17], we proposed an empirical formula, i.e., Equation (4), to estimate the spacing threshold of non-submerged twin spur dikes with ipsilateral layout as: The performance comparison between Equations (3) and (4) is expressed in Figure 11. The figure indicates that Equation (3) offers higher accuracy than Equation (4), especially in the range of small S c values. ...
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... examine the fitting effect of Equation (3), the calculated values Sc for cases c1-c13 from Equation (3) were compared with corresponding CFD results and shown in Figure 11. Good agreement between two data sets illustrated a satisfactory fitting effect of Equation (3). ...
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Citations
... Training structures are required to resist the current load to protect the channel against these changes. Controlling bank erosion has become necessary to stabilize the profile, dimensions, and pattern of the river (Gu et al., 2020;Hamidifar et al., 2018). If these processes of riverbank migration and erosion are left uncontrolled, they can cause severe damage to the river ecosystem and its intended natural function. ...
... Most spur dikes are impermeable for practical purposes, as shown in Fig. 2 (Gu et al., 2020). However, permeable spur dikes can help maintain hydraulic efficiency in meandering channels by reducing energy losses associated with flow redirection. ...
... Spur dike groups on river systems: (a) spur dikes to improve both banks of the Rhine River, Germany; (b) spur dikes to reinforce banks of Xijiang River, Guangdong, China; and (c) spur dikes as training works for navigation in Odra River, Poland(Gu et al., 2020). ...
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 þ30 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.
... Gu et al. quantitatively studied the influence of the spacing threshold of non-submerged double spur dikes on the spacing threshold of non-submerged double spur dikes arranged orthogonally on the same side in a straight rectangular river by combining numerical research and experimental measurement [11]. Jiao et al. studied the influence of different spur dike lengths and riverbank elevation differences on hydraulic power through physical model experiments [12]. ...
A curved channel with intersecting streams can be easily scoured by incoming flow, and the concave bank is badly damaged. This research showed that the twin-groyne could effectively adjust and optimize the flow velocity distribution, change the shape of the free water surface of the bend, prevent erosion, and promote silting on the concave bank, and it could provide a scouring and silting effect on the convex bank. When the spacing of twin-groyne was increased to more than four times the body length of the single-groyne (spur dike), the protective effect on the concave bank was weakened, and the scouring and silting effect of the convex bank was reduced. Excessive spacing of the twin-groyne could cause local erosion damage to the concave bank. When the distance exceeded the theoretical optimum, it was equivalent to the effect of single-groyne. With the increase in the submergence degree, the velocity of the concave bank decreased first and then increased, while the velocity of convex bank decreased continuously. The protective effect of a non-submerged twin-groyne with a dam spacing of four times the body length of the single-groyne was better than that of other conditions, and it is recommended to be used in practice.
