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This paper presents field observations of the riprap slope of a dam regarding the slope damage due to adherence of the ice floe to the slope protection when the water level fluctuates. Analysis of field observation data has made it possible to identify the nature of the slope failure, including the scope of failure, as well as the steepness of a slope resistant to ice impact. To repair the slope of the toe rock, which is pervious fill, and the drainage of the dam, a rational solution has been proposed which, on the one hand, does not lead to a rise of the phreatic surface in the body of the dam, and on the other, its entire mass resists fluctuations of the ice floe. The design concept of the slope protection can be used for both rivers and marine structures, because the geometry of the concrete beams that are the basis of the proposed solution can be modified easily, thus adapting them to specific conditions associated with both ice impacts and the geometry of the slopes to be protected.

This paper investigates effect of scour adjacent to the bridge piers with installed riprap as the scour countermeasure. A riprap sloping structure is a conical placement of launchable stones around the bridge pier commonly used as erosion protection. Riprap sloping structure affects the flow in similar manner to groynes, shifting the scour hole downstream of the toe of the structure. Assuming that the installation of the riprap erosion protection deflects the scour hole development downstream of the bridge, experimental model is developed to represent natural environment under different flow scenarios. The 3D model requires calibration of numerical parameters to accurately simulate the prototype conditions – e.g. cell mesh size, turbulence model, and roughness associated with natural riverbed and the riprap sloping structure. Calibration of the Flow-3D numerical model was performed against the flow measurements conducted during field campaign. Flow measurements were collected using Acoustic Doppler current profiler on 20 transects along the river section adjacent to the bridge. Two independent surveys were conducted: for 30 % flow duration and 60 % flow duration (mean flow conditions). After obtaining the results, cross-sectional velocities were analyzed in 3 characteristic transects (upstream, downstream and at the bridge opening). Finally, good agreement was achieved between the model and measured flow field across all transects, enabling numerical setup to be reliable for simulating rare flood events, and associated scour development. Acknowledgments:This work has been supported in part by Croatian Science Foundation under the project R3PEAT (UIP-2019-04-4046).

A detrimental problem of scour downstream of a Bagmari Syphon in the feeder canal off taking from Farakka Barrage on the Ganga River, West Bengal, India has kindled our interest in understanding the scour process downstream of a broad crested drowned weir. A river was syphoned across the Feeder canal at Bagmari, flushing the top of the syphon with canal bed. However, the canal bed degraded over the years and resulted in exposure and protrusion of the syphon barrel above the canal bed and acting as a broad crested drowned weir. Due to the acceleration of flow over the barrel, scour has developed downstream of the barrel. This problem has been formulated and studied in the laboratory to study the scour process and its mitigation measures using boulders. Experiments have been carried out in the Hydraulics Laboratory of IIT Roorkee, India in a flume of 12.5 m length, 0.46 m width, 0.70 m depth for the different protruding height of weir and flow intensity, keeping ratio of shear stress of approach flow to critical shear stress less than unity. Study on factors affecting maximum scour depth and its temporal variation were analyzed graphically. The scour depth increases with an increase in protruding height of weir and flow intensity. It has been found that maximum scour reduces significantly using boulder apron. The maximum reduction in scour depth with boulder apron lies in the 44% - 68% range and the range of shift in maximum scour depth from weir with boulder apron was 1.6-1.8 times from the original location of maximum scour depth without boulder apron.

There are increasing demands from dam safety regulations and guidelines to upgrade the rockfill dams, especially in Norway where over 180 large rockfill dams are present. To protect the hydraulic structure against overtopping events or leakages, it is important to use defence mechanisms such as a protective layer of riprap on the downstream slope. In this article, we display 9 experimental setups of riprap, conducted at the hydraulic laboratory of NTNU (Trondheim) and subjected to overtopping phenomena with increasing water discharge, until the complete failure of the model. These tests were performed on models with dumped and placed riprap, with or without toe support, with or without the downstream rockfill shoulder, and finally on models with a full dam profile. The models with downstream rockfill shoulder as well as with full dam profiles allowed for throughflow. The model behaviour during these experimental tests is described and discussed, according to their respective critical discharge values and associated failure mechanisms. Limitations are also discussed. The results bring to light the benefit of placed riprap compared to dumped riprap structures. As the results show a placed riprap can withstand a significantly higher overtopping discharge than a dumped riprap. Also, the use of toe support enables a significant increase of resistance against overtopping of placed riprap structures. However, toe supports have not proven any significant improvement in stability for dumped riprap structures. This research also puts forward that dumped riprap undergoes a surface erosion process with smaller slides. Placed riprap undergoes a sliding failure mechanism when unsupported at the toe, and a buckling deformation when supported.

This study was conducted to assess scour problems at three selected bridge sites in the Tigray region, northern Ethiopia, namely the Ilala, upper Geba, and Tankwa bridges. Smart-GIS, ArcGIS, Hydrol...

Burullus headland is located in the middle half of the Nile Delta Coast. It extends from Burullus inlet to the east to Kitchener drain outlet to the west. Burullus headland has several types of coastal protection structures, such as seawalls, groins, revetments, jetties, basalt riprap (rock wall), and detached breakwaters; these structures were constructed to mitigate coastal erosion. This study aims to compare rates of shoreline displacement prior to and after the construction of the aforementioned structures and to evaluate their efficiency in protecting Burullus headland from erosion during the period from 1973 to 2018. Multi-temporal satellite images and Digital Shoreline Analysis System software have been used to detect and quantify shoreline changes and to predict the shoreline position at 2030, depending on the resulted rates of shoreline displacement. The analysis showed that Burullus headland coast would be divided into four zones, according to the intensity of the erosion; these are: Zone A with accretion's rate of 0.67 m/year; Zone B, the most affected area by erosion with retreating rate of 4.32 m/year; Zone C, which includes 14 of detached breakwater, showed an accretion rate of 5.62 m/year; and finally, Zone D, which includes 9 groins, was characterized by retreating rate of 2.88 m/year. The results of this study show that some types of protection structures were not effective in mitigating coastal erosion in the case of Burullus headland. The predicted shoreline indicates continuous accretion in zone A and C and continuous erosion in zone B and D.

Since domestic reservoirs are mainly soil-fill dams, slope protection measures are necessary to prevent erosion, weathering, and wave-induced loss of soil, and riprap is the most common slope protection method. Although design standards for riprap at fill dams are provided in National Design Standard of Korea, they use out-of-date criteria based largely on overseas standards that may not be applicable to the Korean context. This study aimed to identify problems with the current design standards by comparing them with overseas standards, and to suggest directions for improving Korean standards through investigations of existing embankments. The review found that domestic design standards restrict the quality and maximum particle size of stone used for riprap. Much of the design criteria are based on past surveys of the performance record for fill dams conducted by the US Army Corps of Engineers. So this can be unsuitable for changes in modern technology and environmental conditions in Korea. More recent design trends suggest riprap size using an experimental formula, which is numerically different from the data presented in domestic design standards, and this may lead to unstable and uneconomic dams. In addition, various factors such as the shape, weight, and gradation of the riprap can also have a strong influence on riprap stability. The results of the survey show that current condition of the riprap protection is different from the domestic design standard, but it is judged that the stability is satisfied with the overseas design standards. In the field survey, 12 sites were selected in consideration of regional distribution. The results of the survey show that current condition of the riprap protection is different from the domestic design standard, but it is judged that the stability is satisfied with the overseas design standards.

Riprap rocks and large-sized aggregates have been used extensively in geotechnical and hydraulic engineering applications to serve as a key component for erosion/sediment control and scour protection. Toward sustainable and reliable use of riprap rocks, an efficient and accurate method to characterize the size and shape properties is deemed necessary. Current state-of-the-practice methods mostly assess riprap properties with labor-intensive and time-consuming inspection routines that involve manual size and weight measurements. Recent advances in the field of computer vision have been leveraged in this paper to apply deep learning for the development of an innovative image analysis tool for quantitative and efficient riprap characterization. Based on the single-aggregate and stockpile-aggregates studies conducted on this topic, this paper introduces a newly developed computer program, named I-RIPRAP, for the advanced characterization of aggregate size and shape from images of riprap stockpile(s). The essential features and software workflow, as well as the function and mechanism of each module, are described and discussed in detail. In addition to the deep learning methods for segmentation, I-RIPRAP also improves the morphological analyses with a volume/weight estimation module and a riprap category reference module to generate useful results that can facilitate quality assurance/quality control tasks. The I-RIPRAP software is envisioned to serve as an efficient and innovative tool for field and in-place evaluations of riprap and large-sized aggregates.

© 2021 The Author(s). Published by RTU Press.In this study, scour failure risk of the Çatalzeytin Bridge located in the Western Black Sea Basin, Turkey, was assessed for possible future flood events and appropriate scour countermeasures were considered based on economic and constructability considerations. Waterway adequacy in the spans of the bridge and scour criticality around bridge foundations considered for risk calculations in HYRISK were estimated by hydrological and hydraulic analyses of the watershed and stream. Since the watershed of the bridge is ungauged, geomorphological instantaneous unit hydrograph concept was adopted to estimate the peak discharges with various return periods to be used in hydraulic modelling. Monte Carlo simulation results indicated that most of the simulated peak discharges were in the 95% confidence interval. Hydraulic model results from HECRAS indicated that waterway adequacy and scour criticality were critical for discharges with 200 and 500-year return periods. Scour failure risk of the Çatalzeytin Bridge was classified as high and it was proposed to reduce the risk by constructing partially grouted riprap as the most feasible alternative that would consequently increase the expected lifespan of the bridge. Following this methodology, river bridges may be prioritized based on the risk analysis.

A numerically-based approach is used to obtain a size selection formula for the riprap stone part of the apron used to protect wing-wall abutments against erosion. Several series of simulations wit...

Local scouring is one of the key issues at the downstream of ski-jump spillways which may result in failure of the hydraulic structures. Therefore, adopting some measures in order to control and reduce this phenomenon is very crucial. In the present study, the effect of a special shaped element referred to six-legged concrete (SLC) elements along with riprap materials at the downstream of a ski-jump spillway as the scour countermeasure was experimentally evaluated. Experiments were conducted in unprotected (baseline tests) and protected bed (armed with SLC elements of the fixed size and two sizes of riprap with mean diameters of 9 and 20 mm) at five different flow discharges, with Froude numbers ranged from 3.42 to 15.51, and three tail-water depths. The results of baseline tests showed that increasing the flow discharge at different tail-water depths increased the maximum scour depth. Also, at each state, with the increase in the stability number, the maximum scour depth increases. From the results of the protected bed tests, it was concluded that with the application of SLC elements the jet penetrated from the pores between the protected cover and scour was developed, eventually resulting in the collapse of the protected layer. In addition, when the bed was protected by the combination of SLC elements and proper riprap size, the maximum scour depth beneath the protected material was reduced by 56.6%−100%. Using the experimental data, several empirical relations were developed to predict the maximum scour depth for different protection alternatives under different conditions. By defining the bed scour as a criterion for the stability of SLC, a design graph was also proposed to determine the required riprap size.

Shoreline hardening affects ecological processes in nearshore intertidal ecosystems and upland habitats. Invasive species establishment and spread is one consequence of shoreline alterations. Invasive Phragmites australis has spread throughout the U.S., including in subestuaries with hardened shorelines. It is unclear, though, by what mechanisms shoreline hardening facilitates P. australis establishment. We tested the hypothesis that shoreline structures are associated with seedling recruitment, resulting in higher levels of within stand genetic diversity. We used microsatellite analysis to examine the genetic diversity of P. australis stands associated with two types of shoreline structures (riprap, bulkhead revetments) compared to unaltered shorelines. Because P. australis seed viability depends on cross-pollination, higher levels of genetic diversity in stands associated with hardened shorelines are more likely to contribute to the spread of invasive P. australis. We conclude that the extent of shoreline modifications in the Chesapeake Bay has contributed to the spread of P. australis by seeds. The results have implications for the management of P. australis associated with the establishment of shoreline structures.

A model of propagation of thermal fields in permafrost from various engineering objects operating in Arctic regions is considered. The proposed model includes the most significant technical and climatic parameters affecting the formation of thermal fields in the surface layer of the soil. The main objective of the study is a long-term forecasting of changes in the dynamics of permafrost boundaries during operation of cluster sites of northern oil and gas fields. Such a forecast is obtained by simulation of complex system consisting of heat or cold sources and frozen soil, thawing of which can lead to the loss of the bearing capacity and possible technogenic and environmental accidents. For example, the sources of heat can be production wells, and the sources of cold can be seasonal cooling devices that are used to stabilize the soil. To minimize the impact of heat sources on permafrost, various options for thermal insulation are used, and to preserve the original temperature regime of the top layer of soil, riprap materials consisting of sand, concrete, foam concrete, or other heat insulating material are used. The developed set of programs was used in the design of 12 northern oil and gas fields. To solve the described problem in a complex three-dimensional area, substantial computational resources are required. The computing time of one variant can often exceed 10–20 hours of machine time on a supercomputer. To speed up the numerical calculations, multi-core processors are used. Numerical calculations illustrate the possibility of a developed set of programs for making long-term forecasts for determining changes in the boundaries of the permafrost zones, and show that on multi-core processors it is possible to achieve acceleration close to the theoretical one.

Riprap stones are frequently applied to protect rivers and channels against erosion processes. Many empirical equations have been proposed in the past to estimate the unit discharge at the failure circumstance of riprap layers. However, these equations lack general impact due to the limited range of experimental variables. To overcome these shortcomings, support vector machine (SVM), multivariate adaptive regression splines (MARS), and random forest (RF) techniques have been applied in this study to estimate the approach densimetric Froude number at the incipient motion of riprap stones. Riprap stone size, streambank slope, uniformity coefficient of riprap layer stone, specific density of stones, and thickness of riprap layer have been considered as controlling variables. Quantitative performances of the artificial intelligence (AI) models have been assessed by many statistical measures including: coefficient of correlation (R), root mean square error (RMSE), mean absolute error (MAE), and scatter index (SI). Statistical performance of AI models indicated that SVM model with radial basis function (RBF) kernel had better performance (SI = 0.37) than MARS (SI = 0.75) and RF (SI = 0.63) techniques. The proposed AI models performed better than existing empirical equations. From a parametric study the results demonstrated that the erosion-critical stone-referred Froude number (Fs,c) is mainly controlled by the streambank slope.

Stable riprap size and optimized extension of the riprap layer around double and triple piers along the flow direction are studied experimentally. Results showed that the critical riprap failure area and stable riprap size around the first pier remain unchanged with increasing pier spacing. In addition, the largest stable riprap should always be placed in front of the first pier in comparison with the remaining downstream piers. However, by increasing the pier spacing, stable riprap size around the second and third pier increased and approached that around the first pier. A relationship was developed for designing stable riprap size in pier groups. Based on this relationship, different riprap sizes are suggested for different zones around the pier group. Experiments showed that the critical zone around the piers includes only a small area and the rest of the riprap extent area can be protected with smaller riprap stones.

The paper briefly describes the mechanics of local scour process around bridge pier and gives an in-depth review of the various techniques employed for local scour control and protection. The most ...

A novel approach quantitatively describing two-dimensional displacements of placed riprap stones exposed to overtopping flows is developed and validated, coupling experimental data with Euler’s buc...

Monitoring system is essential for improving the understanding of scour processes next to structures built in the riverine environment. State-of-the-art review shows a lack of field scour measurements due to expensive specialized equipment, time-consuming surveys, and difficulties in data acquirement during floods. However, the development of remote sensing over the last 40 years has led to availability of high- quality geospatial data that can be used to obtain accurate 3D physical characteristics data in riverine environment. In bridge construction, it is common practice to place riprap erosion protection above the natural riverbed. Recent studies show that such riprap protection significantly alters flow conditions compared to natural conditions and consequently deflects the scour hole downstream of the bridge. Therefore, the placement of monitoring instruments must be relocated downstream, eliminating solutions that are fixed on the bridge pier. This paper outlines the ScourBuoy innovative prototype for real-time scour monitoring, developed as a part of the R3PEAT project “Remote Real-time Riprap Protection Erosion AssessmenT on large rivers”, which investigates scour processes next to riprap protection. ScourBuoy is an adaptable floating system that can be anchored above the scour hole. It is equipped with an echo sounder, low-cost multi-GNSS dual- frequency device, compass, and motion sensor which collect depth, temperature, pitch and roll data, as well as absolute 3D positioned orientation, integrated into a buoy using a stainless-steel tube and waterproof housing. For the reasons above, Scour Buoy provides a real-time scour monitoring alternative for measurements and research at the specific locations affected by scour.

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Scour is one of the main causes of hydraulic structural failures. The present experimental study examines the use of riprap, submerged vanes, and a combination of these for scour reduction around vertical walls and spill-through abutments under clear-water conditions. Specifically, the influence of placing riprap stones with different apron shapes (geometry) and/or a group of submerged vanes of constant height and length on abutment scour was examined. The main aim is to propose the optimum apron geometry and placement of submerged vanes to (1) reduce edge failure at vertical walls and spill-through abutments; and (2) prevent shear failure at the spill-through abutment (no shear failure is observed around the vertical wall abutment). The results show that using ripraps for scour protection is more effective than submerged vanes. However, the highest reduction in scour depth was achieved when a combination of riprap and submerged vanes was used together. This arrangement can reduce the maximum clear-water scour depth by up to 54% and 39% with vertical walls and spill-through abutments, respectively. Furthermore, selecting appropriate apron scale ratios reduces the required riprap volume by up to 46% and 31% for the vertical wall and spill-through abutment, respectively. In addition, the installation of vanes increased the riprap stability and reduced edge failure in both abutments tested. Finally, using riprap aprons with proper scales ratios at the downstream side of the spill-through abutment also prevents shear failure in this zone.

Local scour is a complex phenomenon consisting of three-dimensional flow structures that often develop around piers and abutments founded in movable river beds. Major damage occurs to bridges during flood, mainly because of scour at bridge foundation, particularly the piers and abutments. In Vietnam, every year there are many serious damages to bridges caused involving local scour. In this article some modern countermeasures against local scour at bridge piers from National Cooperative Highway Research Program (NCHRP) Project were considered, including riprap, articulating concrete blocks, gabion mattresses, rigid and flexible grout filled mattresses. The applicability of each method to bridge structures in Vietnamese conditions was also presented in detail. The results of analyzing the advantages and disadvantages of the four methods of erosion control above show that the riprap method is quite suitable in the conditions of Vietnam.

A numerically based investigation is carried out to determine the minimum median diameter of the riprap stone needed to avoid shear failure inside the riprap apron used to protect spill-tro...

Placing riprap is considered as a permanent layer and common countermeasure against local scour around the bridge pier. However, the typical design of the riprap layer by using empirical equations ...

Hurricanes and tropical storms are among the most frequent and costly natural disasters in the United States, and their impacts are expected to intensify in the future. Understanding the best predictors of hurricane damage in coastal areas is of paramount importance for reducing recovery costs and protecting coastal infrastructure and human lives. This project used surveys of 295 homeowners in coastal North Carolina to evaluate damage to estuarine shorelines and homes caused by Hurricane Matthew in 2016. Specifically, we were interested in the following questions: 1) did homes with hardened shorelines (e.g. bulkheads and riprap revetments) experience more or less damage than homes with natural shorelines during the storm; and, 2) what were the strongest predictors of hurricane damage to shorelines and homes. Overall, we found that past hurricane damage to shorelines was the strongest predictor of shoreline damage during Hurricane Matthew and that flood zone and past hurricane damage to homes were the strongest predictors of home damage. However, homes with bulkheads also sustained more hurricane damage than homes with natural shorelines, perhaps because homes with bulkheads were on average 2 times closer to the shoreline than homes with natural shorelines. Our results show patterns of repeated shoreline and home damage during hurricanes and indicate that environmental context and vulnerability can outweigh individual residents’ shoreline management decisions.

River bank stabilization is a common practise and can be observed on most rivers around the world, often using hard-engineering riprap. Increasingly, bioengineered approaches using vegetation-based constructive materials is promoted to alleviate some of the negative ecological stresses of bank stabilization. Because these stabilization projects use a variety of techniques to create a site-specific design, they can have unexpected morphological implications and variable ecological benefits which can be anticipated using numerical modelling. Bioengineered bank stabilization creates roughness elements on both micro and macro scales, where only macro-roughness can be captured by bathymetric adjustments. The definition of micro- and macro-roughness depends on the spatial resolution of the model domain, and may be considered analogous to skin and form friction when characterizing natural alluvial bed environments. The objectives of this research are to assess the hydrodynamic impact of the added micro- and macro-roughness associated with a bioengineering pilot project planned in Quebec, Canada and to use this case study to propose new techniques for integrating increased roughness due to bank stabilization into numerical models. The roughness of the stabilization project is assessed by adjusting bathymetry to simulate macro-roughness features, and roughness coefficients to simulate micro-roughness features. Results show a significant dampening interaction term that reduced the cumulative effect on resistance to flow when both roughness types were applied.

One of the main causes of damage to bridges, especially during flood event is the scour around the bridge. Determination of the depth of scour around the bridge piers plays a very important role in designing the bridges against this destructive factor. The complexity of the bridge scour and the effects of different parameters on its estimation more clearly reveal the necessity of using a nonlinear and comprehensive model in this field. In this present study, decision tree models, as nonparametric models, are used to estimate the scour depth. Furthermore, the statistics of different bridges and four tree methods are used. The data used to train and test decision trees including flow the velocity of upstream, the median grain size, flow depth, and the pier width, the skew of the pier to approach flow, the length of the pier, the grain size of bed material for which 84 percent is finer, a multiplying factor, input variables, and the depth of scour as output in the model. 75% of the available data is used for model training and the remaining 25% for testing. The results show that among the four models (CART, C5, QUEST, CHAID) examined, C5 model, considering the comparison of the root mean square error parameters and the coefficient of determination, is more accurate in computing the scour depth of the bridge, the amount coefficients of determination in this model is in training and testing steps are 0.92 and 0.76, as well as the mean square error values of the error is 0.56 and 0.72 respectively. Furthermore, the results reveal the QUEST model does not have a proper accuracy in scour depth estimation. Furthermore, the analysis of the models shows flow depth, the flow velocity in the upstream have the greatest effect on the scour depth. Keywords: Scouring; sensitivity analysis; tree models References: Arneson, L. A., Zevenbergen, L. W., Lagasse, P. F., & Clopper, P. E. (2012). Evaluating scour at bridges. Breiman, L., Friedman, J. H., Olshen, R. A., & Stone, C. J. (1984). Classification and regression trees. Wadsworth & Brooks. Cole Statistics/Probability Series. Chattamvelli, R. (2011). Data mining algorithms. Alpha Science International, Ltd. Furnkranz, J., Gamberger, D., & Lavrac, N. (2012). Foundations of rule learning. Springer Science & Business Media. Guan, X., Liang, J., Qian, Y., & Pang, J. (2017). A multi-view OVA model based on decision tree for multi-classification tasks. Knowledge-Based Systems, 138, 208-219. Hamedani, T. (2012). Decision tree algorithms" Mashhad Ferdowsi University, Iran. Hossieni, H., Dalir, A., Farsadizadeh, D., Aronaghi, H., & Ghorbani, M. (2011). Application of submerged plates to control the scouring around the base of a rectangular bridge with a rounded nose. Civil Engineering and Surveying Journal, 9(10), 58-67. Jabari, A., & Samadi, M. (2013). Application of M5 algorithm and prediction of scour depth in downstream overflows. Iran Water Resources Management Co. Karimi, N., Heidarnejad, M., & Masjedi, A. (2017). Scour depth at inclined bridge piers along a straight path: A laboratory study. Engineering Science and Technology, An International Journal, 20(4), 1302-1307. Lim, S. Y., & Cheng, N. S. (1998). Prediction of live-bed scour at bridge abutments. Journal of Hydraulic Engineering, 124(6), 635-638. Lim, T. S., Loh, W. Y., & Shih, Y. S. (2000). A comparison of prediction accuracy, complexity, and training time of thirty-three old and new classification algorithms. Machine Learning, 40(3), 203-228. Tubaldi, E., Macorini, L., Izzuddin, B. A., Manes, C., & Laio, F. (2017). A framework for probabilistic assessment of clear-water scour around bridge piers. Structural Safety, 69, 11-22. Melville, B. W., & Sutherland, A. J. (1988). Design method for local scour at bridge piers. Journal of Hydraulic Engineering, 114(10), 1210-1226. Mia, M. F., & Nago, H. (2003). Design method of time-dependent local scour at circular bridge pier. Journal of Hydraulic Engineering, 129(6), 420-427. Mueller, D. S., & Wagner, C. R. (2005). Field observations and evaluations of streambed scour at bridges (No. FHWA-RD-03-052). Sharyati, H., khodashenas, R., Esmaili, K. (2009). Investigate the operation of the coupling geometry in local scouring at the bridge base. Hydraulic Scientific Journal, 11(5), 14-27. Soleimanpour, S. M., Mesbah, S. H., & Hedayati, B. (2018). Application of CART decision tree data mining to determine the most effective drinking water quality factors (case study: Kazeroon plain, Fars province). Iranian Journal of Health and Environment, 11(1), 1-14. Zahiri, J. (2015). Riprap Design for Bridge Piers Using Nonparametric Models. Zaid, M., Yazdanfar, Z., Chowdhury, H., & Alam, F. (2019). A review on the methods used to reduce the scouring effect of bridge pier. Energy Procedia, 160, 45-50. Zhao, Y., Li, Y., Zhang, L., & Wang, Q. (2016). Groundwater level prediction of landslide based on classification and regression tree. Geodesy and Geodynamics, 7(5), 348-355.

Riprap rock and large-sized aggregates have been used extensively in geotechnical and hydraulic engineering. They essentially provide erosion control, sediment control, and scour protection. The sustainable and reliable use of riprap materials demands efficient and accurate evaluation of their large particle sizes, shapes, and gradation information at both quarry production lines and construction sites. Traditional methods for assessing riprap geometric properties involve subjective visual inspection and time-consuming hand measurements. As such, achieving the comprehensive in-situ characterization of riprap materials still remains challenging for practitioners and engineers. This paper presents an innovative approach for characterizing the volumetric properties of riprap by establishing a field imaging system associated with newly developed color image segmentation and three-dimensional (3-D) reconstruction algorithms. The field imaging system described in this paper with its algorithms and field application examples is designed to be portable, deployable, and affordable for efficient image acquisition. The robustness and accuracy of the image segmentation and 3-D reconstruction algorithms are validated against ground truth measurements collected in stone quarry sites and compared with state-of-the-practice inspection methods. The imaging-based results show good agreement with the ground truth and provide improved volumetric estimation when compared with currently adopted inspection methods. Based on the findings of this study, the innovative imaging-based system is envisioned for full development to provide convenient, reliable, and sustainable solutions for the onsite Quality Assurance/Quality Control tasks relating to riprap rock and large-sized aggregates.

Many natural coastal habitats around the world are being replaced by hard coastal defense structures as a result of rising sea levels and increasing intensity of storms. To examine the potential effects of riprap on gobies in the nearshore zone of the southern Caspian Sea, we used angling to compare their abundance and diversity in 13 riprap and natural habitats (sandy and gravel shores) from April 2012 through April 2013. In total, 819 gobies of three species, Caspian sand goby Neogobius pallasi (N = 433), round goby Neogobius melanostomus (N = 206), and Caspian goby Neogobius caspius (N = 180) were collected. No round gobies were caught from sandy shores and only two Caspian gobies were caught from gravel habitats, while all three species were abundant in riprap shores. A significant difference was observed in CPUE of all three goby species among shore types, with riprap sites having the highest abundance. PERMANOVA and nMDS demonstrated differences in goby assemblages among all three habitats. There were significant differences in round goby and Caspian goby sizes among riprap and natural habitats, while there were no significant differences in Caspian sand goby size among habitat types. In general deployment of riprap, especially in an area characterized as having natural shores with low structural complexity, could enhance the abundance and coexistence of nearshore gobies and act as a dispersal vector.

Riprap rocks and large-sized aggregates are being used extensively in geotechnical and hydraulic engineering applications. Knowing the particle size and morphological/shape properties ensures the reliable and sustainable use of aggregate materials at both quarry production lines and construction sites. Traditional methods for assessing aggregates geometric properties involve subjective visual inspection and time-consuming hand measurements, while the use of computer vision analysis techniques is restricted primarily due to the unwieldiness of large-sized aggregates. This paper presents the use of a computer vision system for in-place size and shape evaluation of large aggregates in a stockpile using images of stockpiles conveniently collected using smartphone cameras. The automated image analysis software is comprised of an image segmentation kernel and a morphological analysis module. Comprehensive analyses are conducted on a sample stockpile with multiple view inspections. Based on the findings of this study, the stockpile aggregate image analysis program has great potential as an efficient and innovative application for field-scale and in-place evaluations of aggregate materials.

The objective of this study was to evaluate the input of suspended sediment from the slope toe in the São Francisco River channel, in Northeast Brazil, under different soil bioengineering techniques. Sediments were collected in the years of 2013, 2014 and 2015, in five transects crossing the river channel. Sediment input in the sampling points was higher in the year of 2013, i.e., the year of the highest river discharge. Sediment supply to the river channel for a period of 3 years (2013, 2014 and 2015), was evaluated at 20, 40 and 60% depth, along five different transects (P1= riverbank, P2= beginning of the thalweg, P3= middle of the thalweg, P4= end of the thalweg, and P5 = margin of the side sandybar), oriented by the presence or absence of erosion control techniques (treatments) such as: 1-Natural Vegetated Slope; 2-Vegetated Riprap; 3-Eroded Slope; 4-Live Cribwall and 5-Vetiver grass Contour Line. Sediments input was different in all evaluated transects, and the one identified as Eroded Slope at 20% depth presented the lowest amount of suspended sediment load. There was a decrease in the total amount of suspended sediment in the evaluated periods, probably due to the progressive decrease in the river discharge, and the protection provided by the soil bioengineering techniques.

Scour at bridge abutments usually consists of local and contraction scour that correlate because of the flow field that develops both scours. Flume experiments were conducted using simulate...

Grado en Ingeniería Civil

This technical note briefly reviews existing empirical riprap sizing equations for overtopping flow conditions. It then proposes new riprap sizing relationships that focus on the dominant p...

Shoreline erosion in lakes is a pressing issue for many landowners, yet common erosion mitigation practices that involve armoring can alter littoral habitat and potentially diminish near-shore biodiversity. We studied the effects of two armoring methods (i.e., riprap, retaining walls) on habitat, taxonomic richness, relative abundance, and total abundance of fishes and benthic macroinvertebrates at shorelines on Big Rideau Lake in eastern Ontario, Canada. Snorkel surveys were conducted to assess aquatic habitat characteristics and fish diversity, and benthic infauna were sampled using kick-nets. Submergent and emergent macrophytes were more abundant at natural rocky shorelines compared to shorelines modified with riprap or retaining walls. Coarse woody debris was also more abundant at natural shorelines compared to riprap and retaining wall shorelines. Relative abundances of some fish species varied between shoreline types, but overall species richness and total abundance did not. Largemouth Bass (Micropterus salmoides) were more abundant at natural sites than armored sites. Conversely, Rock Bass (Ambloplites rupestris), Pumpkinseed (Lepomis gibbosus), Bluegill (Lepomis macrochirus), Yellow Perch (Perca flavescens), and baitfish from the family Cyprinidae were more abundant at both types of armored sites compared to natural sites. Taxonomic richness of benthic macroinvertebrates did not vary among shoreline types, however abundance of Amphipoda, Isopoda, Ephemeroptera, and Cladocera was greater at armored shorelines. These results suggest that human modification of shorelines is altering littoral ecosystems and potentially leading to shifts in the community structure of littoral nekton. More study is needed to fully understand the community level effects of shoreline erosion mitigation involving armoring in freshwater lakes and determine the effectiveness of alternative mitigation strategies that preserve natural habitat features.

Vessel-induced waves affect the morphology and ecology of banks and shorelines around the world. In rivers used as waterways, ship passages contribute to the erosion of unprotected banks, but their short- and long-term impacts remain unclear. This work investigates the effects of navigation on bank erosion along a reach of the regulated Meuse River with recently renaturalized banks. We apply UAV-SfM photogrammetry, RTK-GPS, acoustic Doppler velocimetry, aerial and terrestrial photography, soil tests, and multibeam echosounding to analyze the progression of bank retreat after riprap removal. After having analyzed the effects of ship-generated waves and currents, floods, and vegetation dynamics, a process-based model is proposed to estimate the long-term bank retreat. The results show that a terrace evolves in length and depth across the bank according to local lithology, which we clustered in three types. Floods contribute to upper-bank erosion-inducing mass failures, while near-bank flow appears increasingly ineffective to remove the failed material due to terrace elongation. Vegetation growth at the upper-bank toe reduces bank failure and delays erosion, but its permanence is limited by terrace stability and efficiency to dissipate waves. The results also indicate that long-term bank retreat is controlled by deep primary waves acting like bores over the terrace. Understanding the underlying drivers of bank evolution can support process-based management to optimize the benefits of structural and functional diversity in navigable rivers.

This study aimed to determine the current geological and engineering features of granite blocks used as riprap material in the construction of Gelingullu Dam which is in use for nearly 20 years. The riprap layer is divided into four zones (A, B, C and D) from the lowest lake water level to dam crest by noting the durations underwater. Samples taken from the zones were investigated for petrographic, physical, chemical and mechanical characteristics. Schmidt hardness hammer experiments were completed on site for blocks in the zones. The shape features of the blocks were determined with the fractal dimension method. Physical weathering developed on sections close to the surface of blocks in zones A, B and C which were in contact with water. Compared to blocks in zone D, blocks in zones A, B and C had higher porosity, water absorption and Los Angeles abrasion loss values, with lower density, uniaxial compressive strength, Schmidt hardness rebound values and Vp values. The increased porosity of blocks from zones A, B and C was caused by greater effects of physical factors like wetting–drying and freeze–thaw affecting the blocks in these zones in contact with lake water. This increased the speed of fragmentation and weakening of the blocks. According to the results obtained in the study, it is understood that over nearly twenty years, the weathering processes affecting the riprap layer have caused changes to the physical and mechanical features of the rock blocks.

All engineering projects consist of several steps, and one of the main tasks is to identify and characterize the most important features of rock types that will be excavated, crushed, or mined for any particular usage purpose, from a single residential building to major works of infrastructure. Laboratory investigation on engineering geology is thus conducted in order to determine the most relevant rock properties when designing structures such as mining shafts, tunnels, buildings, or reservoir dams to be built in sites associated with rocks. A wide range of laboratory tests is available, making the correct choice of test methods greatly relevant to determine the key property for the planned use of the rock. This paper is an illustrative case of laboratory testing of basaltic rocks to be used as riprap in a reservoir dam. It shows the important role of the petrographic study carried out to analyze the distribution pattern of smectite clay minerals. Test results are explained for the assessment of rock alterability, an essential aspect for the selection of the most suitable basalt variety for the envisaged conditions of use. Keywords: Rock properties, Laboratory testing, Test methods, Petrographic analysis, Smectite clay minerals, Basaltic rocks, Accelerated weathering tests, Alterability

INTRODUCTION Tho rolled earth fill dam, the design of which forms the subject of this thesis, is a homogeneous bank of a material which may be described, generally, as a sandy-silty clay. It is not a large dam, its principal dimensions being – maximum height above natural surface, 60 feet; length, 1250 feet; and maximum width at base, 400 feet. The total quantity of fill is approximately 250,000 cu. yd., including riprap and other rock fill. The structure has, however, been considered of sufficient importance to warrant the application to its design and construction of the most recent information on soil mechanics which was available to its designers and builders, and this for three reasons – 1. It is a functionally important structure in its own right. 2. Site conditions, being on the whole unfavourable, presented problems which necessitated as precise a knowledge of material properties - and of their effects on design and construction- as could be obtained with available resources. And 3. The Saddle Bank was regarded partly as a training ground for the main earth banks (later changed to rock- fill) of Koombooloomba Dam, which is the first dam of its type to be undertaken by the Co-ordinator- General's Department and will probably be the forerunner of many more earth or rock-fill dams to be constructed in Queensland in the future. …………

Research and engineering efforts are establishing a vast number of stream restoration planning approaches, design testing frameworks, construction techniques, and performance evaluation methods. A primary question arises as to the lifespan of stream restoration features. This study develops a framework to identify relevant parameters, design criteria and survival thresholds for ten multidisciplinary restoration techniques: • Parameterize relevant features, notably, (1) bar and floodplain grading; (2) berm setback; (3) vegetation plantings; (4) riprap placement; (5) sediment replenishment; (6) side cavities; (7) side channel and anabranches; (8) streambed reshaping; (9) structure removal; and (10) placement of wood in the shape of engineered logjams and rootstocks. • Identify survival thresholds for parameters, where the feature life ends when the threshold value is exceeded. • Compare parameter thresholds with spatial data of topographic change and hydrodynamic forces as a result of hydrodynamic modelling of multiple discharges.The discharge or topographic change rate that is related to the lowest (flood) return period spatially determines the feature’s lifespan in years. Method name: Lifespan map creation, Keywords: Eco-morphology, Habitat enhancement, River management, Stream restoration, Sustainability, Feature lifetime

A series of laboratory flume experiments were done in a large-scale 180° bend with non- cohesive sediment to find optimal or effective protection works at a bend. Detailed study of the scour and flow field dynamics with and without protection works was done. Spatially dense, high frequency velocity data were collected and analyzed to describe the pattern and magnitude of three-dimensional (3D) velocity throughout the bend. Characterizing the role of flow field dynamics on the pattern of deposition and erosion through experimental measurements provided valuable data about how such flow features contribute to scour and about the performance of the protection works. From the experimental results, it is revealed that for a perennial river it is not possible to protect from scour either with riprap or with submerged vanes alone. Protection from scour at a bend can be achieved with proper combination of these two works. First, submerged vanes can protect the toe, and, second, riprap can protect the upper part of the slope if it is not damaged through toe erosion. The experiments convincingly demonstrate the efficiency of this bank protection technique.

Providing the most effective solution for protection of the bed downstream of hydraulic structures constitutes an important field of research. In addition, for safe and cost-effective designs, it is important to be able to predict the maximum scour depth downstream of hydraulic structures. The study reported in this paper examined the effectiveness of two types of countermeasures – a bed sill and riprap – to reduce the maximum scour depth adjacent to horizontal rigid aprons. For tests with the bed sill located downstream of the apron, two distinct scour holes were formed upstream and downstream of the sill, with respective maximum scour depths of ds1 and ds2. The results show that a bed sill can reduce ds1 and ds2 by up to 23% and 47%, respectively, compared with the maximum scour depth for the no-sill condition. However, when the erodible bed between the apron and the bed sill was replaced by riprap, ds1 and ds2 decreased by up to 53% and 90% respectively. Variations of the other characteristic scour hole lengths, including the maximum extension of the scour hole and the maximum height of the mound, were also studied and an attempt was made to examine any geometrical similarities in the scour hole profiles under different conditions.

Four southern California beaches were nourished with offshore sand placed as subaerial pads several meters thick, ∼ 50 m wide, and spanning between 500 and 1500 m alongshore. Three nourishments constructed with coarser than native sand, placed in 2012 at Imperial, Cardiff and Solana Beaches, elevated subaerial sand volumes for several years even when exposed to the energetic winter waves of the 2015-16 El Nino, followed by a stormy 2016-17 winter. As these relatively resilient pads were overwashed, landward tilted subaerial profiles (accretionary crowns) formed at the eroding front face of the originally flat-topped pads and pooling occurred in the backbeach. At Imperial Beach, nourishment sand helped prevent waves from directly impacting riprap fronting houses, while groundwater flooding behind the pad was observed at a location where the pad was elevated ∼ 1.6 m above the street. As the nourishments retreated, alongshore oriented spits grew downdrift from the eroding face. The alongshore displacement of the subaerial center of mass of the 2012 nourishments is positively correlated with the seasonally varying S x y (the alongshore radiation stress component). After four years, the net southward drift of the Imperial Beach nourishment contributed to the winter 2016 closure of the Tijuana River mouth and the associated hyper-polluted and anoxic estuary conditions. Nourishment impacts on sand levels on rocky reefs were not unambiguously detectable in the background of natural variability. Over several years, gains or losses in the total sand volume (integrated from the back beach to 8 m depth, over the few km alongshore survey spans) are sometimes comparable to nourishment volumes, suggesting relatively large interannual sediment fluxes across the control volume boundaries. The clearest trend in total volume is at Torrey Pines; during 16 years since the 2001 nourishment, about 300,000 m3 of sand has been lost. If the trend continues, the thinning veneer of sand will be removed more often from the subaerial winter beach, exposing rocks and cobbles.

As the Buenos Aires Province coastline is dominated by a longshore transport from south to north, obstructions performed at the beginning of the 20th century originated the width reduction of some beaches. Fields of groins were constructed without a master plan; therefore, more obstructions caused a dramatic decrease in the longshore sand supply. These defense alternatives were only applied in the counties of the southeast of the province (General Pueyrredon, General Alvarado, Mar Chiquita), close to the quarries, and with resistant abrasion platforms. Northern beaches (Villa Gesell, Pinamar and Partido de la Costa), on the other hand, are natural with a dissipative morphodynamics. Where the coastal route is close to active cliffs, riprap structures were constructed parallel to the coastline. Today, the southeastern coast remains with the higher erosion rates of the Buenos Aires coastline. With the aim of aerial and satellite photographs, and images, erosion rates were calculated. In order to analyze the success of coastal defenses, comparisons were established according to two intervals: 1960–1980, and 1980–2008. Defense structures have contributed to the decrease in the erosion rates in some areas; in other areas, the rates have increased due to the drift obstruction. In some critic areas, and considering present erosion rates, future positions of the coastline were simulated for the next 20–30 years. At the same time, there are new unexpected problems derived from a project to construct detached breakwaters that were not completed, and considering jetties that were constructed without a previous impact-assessment analysis. Fil: Isla, Federico Ignacio. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Geología de Costas y del Cuaternario. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto de Geología de Costas y del Cuaternario; Argentina Fil: Cortizo, Luis. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Geología de Costas y del Cuaternario. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto de Geología de Costas y del Cuaternario; Argentina Fil: Merlotto, Alejandra. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Geología de Costas y del Cuaternario. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto de Geología de Costas y del Cuaternario; Argentina Fil: Bertola, German Ricardo. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Geología de Costas y del Cuaternario. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto de Geología de Costas y del Cuaternario; Argentina Fil: Pontrelli Albisetti, Melisa. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Geología de Costas y del Cuaternario. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto de Geología de Costas y del Cuaternario; Argentina Fil: Finocchietti, Cecilia. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Geología de Costas y del Cuaternario. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto de Geología de Costas y del Cuaternario; Argentina

Rock riprap is commonly used to protect levees, embankment dam, steep channels, and other structures being vulnerable to deteriorative erosion caused by overtopping flow. A review of the literature...