River restoration refers to the environmental and ecological aspect of river engineering and aims to improve the natural habitat of a river system using eco-friendly methods. This paper introduces a new river restoration technique for bank protection and restoration of meander bends by combining a permeable groin with a triangular vane. Nine different combinations of permeable groins with triangular vane including three different effective lengths and three angles of vane were investigated in a 180° mild laboratory flume bend in clear water conditions. Based on experimental tests, scour geometrical patterns were analyzed, classified, and compared with each other. This analysis showed that a triangular vane dramatically enhances the performance of the permeable groin to protect the outer bank from erosion. Then, using Buckingham’s theorem of the dimensional analysis and the incomplete self-similarity (ISS) condition, generalized functional relationships for estimating scour main characteristics around an enhanced permeable groin (EPG) were deduced. This analysis showed that scour patterns depend on the upstream densimetric particle Froude number ($A_{50}$ ) and the ratio between the effective lengths of the triangular vane and the permeable groin ($L_t/L_p$ ). The results showed that scour geometric characteristics estimated by the proposed equations agree reasonably well with the experimental values.

The enhanced permeable groin is a novel eco-friendly and cost-effective technique for bank protection and restoration of meander bends. The behavior of bed deformations due to the distance between the structures has to be studied to design enhanced permeable groins in series properly. In this study, scour morphologies around enhanced permeable groins in series, characterized by four different distances and located in a 180° mild flume bend, for clear water conditions were investigated. The analysis indicated that scour geometrical patterns such as the maximum scour depth nearby the structures and the maximum deposition height between them are strongly affected by the distance between the groins. The results revealed that the maximum scour depth around the structures increases with the distance between structures, the scour holes develop towards the outer bank and create a series of pools that can lead to the bank collapse. All experiments, carried out with different structure distances, demonstrated that the location of thalweg effectively shifted towards the middle of the channel and near the inner bank for high and low particle Froude numbers, respectively. As a general result, a distance between enhanced permeable groins equal to four times the effective length of the structure is recommended for a 180° mild flume bend for the investigated particle Froude numbers. Finally, a general design guideline is presented to a proper design of enhanced permeable groins in series.

A common and practical type of hydraulic jump at sloping bed (e.g., concrete, gabion or rock cover bed chutes) is B-jump which its toe located on the sloping bed and ended at the downstream horizontal channel. Determination of hydraulic jump characteristics such as the sequent depth ratio can help to design a safe and economic stilling basin. Many studies have been carried out for B-jump on smooth sloping bed; however on the effect of roughness on jump characteristics no relation is available. In this paper first a general non-dimensional relation was developed using Buckingham theorem. Then by applying the incomplete self similarity theory and using a new dimensionless parameter, N, a new non dimensional relation was developed. The significant of such relation is that it is independent of bed slope. To verified such relation two series of tests were conducted at the hydraulic lab using three different slope angles, five different roughness heights and five different flow conditions both on smooth and roughened bed. The collected data were analyzed by SPSS15.0 software and the required coefficients were obtained. The proposed expression was tested using wide range of data and the average absolute error was found to be 6.4%.

Rock chutes are widely used to control erosion of river beds because of their high energy loss, low environmental impact, simple construction and low cost. They typically include a negatively sloped stilling basin, which leads to formation of a little-understood ‘B-F’ hydraulic jump. This has its toe located on the upstream positive slope of the chute and its roller length ending on the downstream negative slope of the stilling basin. In this study, a general equation for computing the sequent depth ratio of a B-F jump was developed using Buckingham dimensional analysis and the incomplete self-similarity theorem. A new non-dimensional parameter, E₀, including the effects of the jump toe and the location of the end of the roller length, was introduced. Laboratory experiments of B-F hydraulic jumps were conducted for a wide range of upstream Froude numbers, relative bed roughness, three different upstream channel slopes and three different negative downstream channel slopes. The sequent depth ratio on rough rocky beds was found to be considerably smaller than those on a smooth concrete bed. Two new prediction equations, for smooth and rough bed slopes, are presented and the results show that the predictions agree reasonably well with the experimental data.

In this paper, the sequent depth ratio of a sill-controlled B-jump on sloping beds was investigated. Experiments were carried out to characterize the effect of the different design parameters such as the sill height, sill position relative to the jump toe, and chute slope on the sequent depth ratio under various up - and downstream hydraulic conditions. By applying the momentum conservation principle, a generalized relationship to estimate the sequent depth ratio was deduced. This analysis demonstrated that the sequent depth ratio depends on the upstream Froude number, the chute slope, the jump toe location on the chute, the sill height and its position, and the tail-water depth. Furthermore, the energy dissipation efficiency of a sill-controlled B-jump resulted greater than that for a free B-jump. Based on results of this investigation, the sill-controlled B-jump can be used as a novel alternative to the classical hydraulic jump to reduce cost where the length of the stilling basin must be shortened due to site restrictions and arrangement.