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River restoration structure’s design features are some of the most important topics for hydraulic engineers. These low-environmental impact structures minimize the impact on natural contexts and at the same time, they do not require frequent anthropic intervention. Generally, these structures are used for river restoration and represent a dynamic system for both river grade-controlling and improving the aquatic habitat. The present paper aims to compare scour downstream of two different low-head rock made control structures; cross-vane and W-weir. The analysis involves the results of laboratory experiments conducted at the PITLAB hydraulic laboratory of University of Pisa and a detailed comparison of scour hole characteristics, highlighting similitudes and differences in the respective ranges of application. All tests are done in clear water conditions using uniform sand as channel bed material.

Log-Vane is a grade-control structure of common use to stabilize river bed and river banks. The purpose of this paper is to study the scour phenomena downstream of Log-Vanes in straight rivers. The main goal is to obtain design equations to determine the main scour parameters and the scour morphology. All the experiments have been carried out in a horizontal channel and in clear water conditions. Log-Vanes made of wood, with different heights and vane angles, were tested. Different hydraulic conditions including densimetric Froude numbers, water drops and tail water values were tested. Results show that the tail water depth is an important variable to determine the maximum scour depth. The vane angle results to be an important parameter to predict the scour parameters. Dimensional analysis allows to derive design equations useful to estimate the maximum scour depth, maximum length of the scour and maximum height and length of the dune.

Maroun River in Khouzestan province in south of Iran is one of the most important Iran water resources and it enters to international Shadegan Wetland (Biggest Iranian Wetland). It is very important that we have Fishways with high efficiency for each obstruction across the river such as Diversion Dams and Regulator Dams. The dominant family of fishes, which live in Shadegan wetland, is Cyprinidae family, which is resident at this wetland and Maroun River. On this river, there is one Reservoir Dam and four Diversion Dams that have been constructed by Khouzestan Water & Power Authority (K.W.P.A.). The Reservoir Maroun Dam has no facilities for fish migration and here is some efforts for finding a possibility for installing a suitable fish facility for this dam. Fishway of Jaeezan diversion dam on Maroun River constructed about 6 years ago and dose not have good efficiency and it is not functioning properly. During the migration season, fishes are trapped downstream of the dam. The first part of this paper belongs to results of study on finding rehabilitation for this Orifice-Weir type Fishway. Behbahan diversion dam on Maroun River, which has been constructed in 20 years ago, has no Fishway and the second part of this paper includes the results of study on finding a possibility for installing a Fishway at this dam.

Migratory Fish travel downstream to reach larger body of water where the food is available. When they grows, migrate upstream to the place of their birth to spawn .In areas where fish have a commercial value and to keep alive these species as a part of environment, care must be done not to stop such migration specially by constructing the dams across the rivers. Diversion dams usually built across the river to divert some portion of the river flow for irrigation lands. In such dams, the engineers must provide a passage called “FISHWAY”; for fish in order that fish can travel from down stream to the upstream of the dam. Of course, if such structure is not considered, the fish can not travel upstream to spawn, therefore in the long term these species will diminish. In this study a hydraulic model was conducted to investigate the hydraulic conditions of vertical-slot type of fishway which has been considered for Ramhormoz diversion dam in the province of Khouzestan, Iran. The Froudian hydraulic model with the scale of 1:5 was constructed at the hydraulic laboratory of Shahid Chamran University. Tests were performed for the original design and two other alternatives slot-opening angles. Another shway called Denil, also was tested. From the observation and data obtained from these tests, it was found that 90-degree slot opening provide suitable hydraulic conditions. Denil fishway also was found to satisfy the hydraulic criteria and due its simplicity and rapid construction was recommended to be used in this diversion dam.

Nowadays stream restoration structure’s design features is an active field of research for river engineers. Low-environmental impact is the main characteristics of these types of structures in needless of frequent human interventions during the operation. These structures are used for riverbank protection, river grade controlling and improving the aquatic habitat. This study aims to compare scour downstream of two different low-head grade-control structures; Log-Vane and Log-Deflectors. The analysis contains the results of laboratory experiments conducted at the hydraulic laboratory of the University of Pisa and a detailed comparison of scour hole characteristics, highlighting similitudes and differences in the respective ranges of application. All tests have been done in clear water conditions using uniform sand as channel bed material.

A new prediction formula is proposed to determine wave-induced pore pressure height distribution inside the core of rubble mound breakwaters. Existing observed field and experimental data in the literature have been examined, and a valuable database has been obtained. Using dimensional analysis, a new wave damping parameter has been derived. In comparison with the existing empirical Biesel’s formula, the proposed prediction formula directly takes into account the influence of the mean diameter of the core material, water depth, and important wave parameters such as incident wave height and wavelength, and there is no more necessity to assume appropriate values for the seepage coefficient and the material coefficient that are essentially needed for Biesel’s formula. The new prediction formula presented here has its merits in providing an alternative form and insight into the physics of phenomena.

A simple formula to determine the wave breaking depth index for regular waves is proposed. In the literature, there are several formulas for determining the breaker depth index, which, over...

River restoration aims to improve physical natural form and processes of a river. Techniques to control the riverbed, stabilize channel alignment, protect stream banks, and rebuild the natural habitat are an important part of river restoration projects. Rivers can be stabilized and habitat restored through techniques such as rebuilding meanders and pool-riffle sequences and managing large wood. Structures that limit channel width to accelerate the normal flows through the constricted section are referred to as stream deflectors. Single-wing, double-wing and triangular deflectors are the most commonly used types of this measure. Log-frame deflectors consist of a triangular log frame filled with rock. Deflector constructions singly or in series in low gradient meandering streams, divert base flows toward the center of the channel and, under certain conditions, increase the depth and velocity of flow thereby creating scour pools and enhancing fish habitat. Scour characteristics and morphologies downstream of log-frame deflectors have been analyzed at the hydraulic laboratory of the University of Pisa. All experiments have been carried out in clear water conditions. The results showed that the tailwater depth plays an important role on scour characteristics. In addition, it was experimentally proven that using log-frame deflectors instead of log-deflectors result in a better river bank protection. In this case, for all the tested hydraulic conditions, the scour hole never occurred close to the channel bank. Useful empirical relationships have been proposed in order to evaluate the main features of the scour geometry.

Stream deflectors are grade-control structures of common use to control riverbed evolution, stabilize channel alignment, protect stream banks, and rebuild the natural habitat. Among them, log-frame deflectors consist of a triangular log frame filled with rocks. Log-frame deflectors, constructed either singly or in series in low gradient meandering streams, divert base flows toward the center of the channel. Under certain hydraulic conditions, they modify both the depth and velocity of flow, resulting in scour pool formation and fish habitat improvement. The main purpose of the current study is to analyze the effect of the distance between log-frame deflectors on the scour morphology, when installed in series. Therefore, experimental tests have been carried out in a horizontal channel and in clear water conditions at the hydraulic laboratory of the University of Pisa. Results show that the meandering process in rivers is deeply influenced by the distance between log-frame deflectors, when located at both left and right river banks. Furthermore, scour characteristics and morphologies downstream of log-frame deflectors have been analyzed, resulting in useful suggestions for a correct design of such structure typology.

In-stream grade-control hydraulic structures have been employed to reinstate riverbeds, to protect riverbanks, and to improve aquatic habitats. This paper aims to study scour phenomena and morphologies downstream of cross-vane structures installed in curved channels, and structure orientation with respect to the flow direction. Experiments have been conducted in clear-water conditions. The results showed the important effect of the channel curvature on the maximum scour depth value and position.Increasing of the bend radius leads to a decrease in the value of the maximum scour depth. The scour morphology has been classified in three types. Observations showed that the scour typology affects the maximum scour depth value. The variation of the structure orientations has been experimentally analyzed and results showed a significant effect on the maximum scour depth position.

Supercritical flow below chute piers generates an aerated flow known as rooster tail. Their behavior varies along the spillway or chute for different Froude numbers. This paper aims to analyze the effect of various parameters including the Froude number, approach flow depth, chute pier width, and presence of a deflector ramp on the rooster tail geometry. Aerator systems, which generally include deflectors in chutes, are effective in the generation of rooster tails. The interaction between a deflector and supercritical flow of chutes causes a higher rooster tail. New equations define the rooster tail geometry in the presence of a deflector. The air concentration profile was measured and the effects of deflectors on the air entrainment were studied.

Stream deflectors are in-stream hydraulic structures that limit the flow channel width, thereby accelerating the flow through the constricted section. Single-wing and double-wing log deflectors are the two most commonly used types of in-stream eco-friendly structures. The purpose of this paper is to investigate the scour phenomena downstream of log deflectors in straight horizontal channels. The main goal is to obtain design equations to predict the main scour parameters and describe the scour morphology. All the experiments have been carried out in a horizontal channel and in clear water conditions. Log deflectors with different heights and angles were tested. Different hydraulic conditions including densimetric Froude numbers, water head drops, and tailwater values were studied. Results show that the tailwater depth and deflector angle are important variables to determine the scour parameters. Dimensional analysis leads to design equations to estimate the maximum scour depth, maximum length of the scour, and maximum height and length of the dune. Two types of scour morphology downstream of log deflectors have been defined.

Low-environment impact structures have the advantage to conjugate both hydraulic functioning and environmental care. In particular, these structure typologies are widely used for river restoration both to control sediment transport and to dissipate flow energy. In the present paper, rock grade control structures, stepped gabion weirs, block ramps, and cross-vane weirs are analyzed and compared. Both similitudes and differences in terms of scour characteristics and dissipative efficiency are highlighted. The comparison shows that block ramps are the most efficient structures among those tested. Useful practical relationships are proposed in order to estimate both scour characteristics downstream of each structures and energy dissipation.

J-Hook Vanes are in-stream river grade-control structures to reduce stress along the outside of the river bends and to promote scour in the pools and improving the aquatic habitat. The main purpose of this study is to investigate the effect of the channel curvature on the scour hole characteristics and morphologies downstream of J-Hook structures. The main scour geometry parameters have been analyzed at the hydraulic laboratory of the University of Pisa. Three different channel bends were studied. All experiments have been carried out in clear water conditions. Scour morphologies were surveyed using 3D laser technology. The results showed that an increase of the bend radius causes a decrease in the value of the maximum scour depth. The observations showed that the channel curvature is an important parameter to classify the scour morphology and directly affects the position of the maximum scour depth. Finally, different scour morphology types downstream of J-Hook Vanes are formed.

Scour characteristics downstream of rock W-weir structures were studied in a horizontal straight channel and under clear water conditions. For each structure, different hydraulic conditions were considered, including densimetric Froude numbers, water drops, and tailwaters. Results showed that the tailwater depth plays an important role in predicting the scour parameters. Dimensional analysis was used to derive equations to predict the maximum scour depth and length and the maximum dune height and length. Selected tests were conducted with an open W-weir. In this case, results show that the maximum scour depth decreases and its location shifts downstream with respect to classical W-weirs. Three types of scour morphology were classified: Type A, characterized by one scour hole and two ridges; Type B, with two scour holes and two ridges; and Type C, characterized by only one scour hole and one ridge.

River and stream restoration structure’s design features have been an active field of research for hydraulic engineers. Generally, these low-environmental impact structures minimize the impact on natural contexts in needless of frequent human interventions during the operation and are used for riverbank protection, river grade controlling and improving the aquatic habitat. The main objective of this paper aims to compare scour downstream of two different low-head control structures; Log-Vane and Hook vane. The analysis contains the results of laboratory experiments conducted at the PITLAB hydraulic laboratory of University of Pisa and a detailed comparison of scour hole characteristics, highlighting similitude and differences in the respective ranges of application. All tests have been done in clear water conditions using uniform sand as channel bed material.

J-Hook vanes are grade control structures used to stabilize the riverbed. This paper aims to investigate the behaviour of J-Hook vanes as a grade-control structure in straight rivers. Scour downstream of J-Hook vane structures like other grade-control structures depends on the shape of the structure and the river hydraulic conditions. The purpose of this study is classifying the scour geometry and predicting the main scour parameters such as the scour depth, length, width, and the ridge height and length downstream of the J-Hook vanes in straight rivers. Experiments were carried out in a horizontal channel. For each length of the structure, three heights in different hydraulic conditions, including densimetric Froude numbers, water drops, and opening ratios, were tested. Results show that the densimetric Froude number, the drop height, and the height of the structure are the key parameters to form and classify the scour. Equations have been derived using dimensional analysis and experimental data to predict the maximum scour depth, the maximum length of the scour, the maximum scour width, and the maximum height and length of the dune. All the experiments were conducted in clear water conditions.

Cross-Vanes are hydraulic structures used to stabilize the riverbed and control the grade for river restoration. Scour downstream of Cross-Vane structures depends on the shape of the structure, the bed material and the river hydraulic conditions. This paper aims to predict the maximum scour depth and classify the scour morphology. Two series of experiments were carried out. In the first series, two types of structures, which are I-shape and U-shape structures have been studied in a horizontal channel. In the second series of experiments, riverbed slopes of 1%, 2.5% and 5% were tested. For each type of structure, three heights in different hydraulic conditions including densimetric Froude numbers and drop heights were tested. Results show, that the ratio between the length of the structure and the channel width is one of the most important non-dimensional parameter to classify the scour. New analytical functions have been derived from dimensional analysis to predict the maximum scour depth, the maximum length of the scour, location of the maximum scour depth and the maximum development of the scour width. All the experiments were conducted in clear water conditions. Based on dimensional analysis and using all collected data new equations have been obtained. Scour morphology downstream of Cross-Vane structure was classified in different scour patterns based on different flow hydraulic conditions, structures geometries and the ratio between the maximum length of the scour and the channel width.