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For rubble mound breakwaters, incorporating a berm in the seaward slope can be very effective in reducing wave overtopping and mitigating wave loads acting on the breakwater armor elements. This research aims to investigate the effect of horizontal berm on the seismic response of conventional rubble mound breakwaters, considering various amplitudes and frequencies characterizing seismic loads. Finite element models of conventional rubble mound breakwaters, with and without berm, are developed using Plaxis 2D software for this purpose. Additionally, the stability of rubble mound breakwaters with berms is studied through various numerical models, considering different lengths and height levels of the berm. A comparative analysis of the results shows that rubble mound breakwaters incorporating berms exhibit lower deformation characteristics compared to those without berm. The numerical study results suggest that berms can significantly enhance the stability and reduce displacements of rubble mound breakwaters under seismic loading compared to breakwaters without berm. [ABSTRACT FROM AUTHOR]

Copyright of Revue TED: Territoires, Environnement et Développement is the property of Universite Ibn Tofail and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

There are many ways to support the foundation pit, such as earth berm and anchor. However, the combined support structure of earth berm and anchor cable for over-excavation foundation pit is lack of theoretical research. To investigate the interaction between reserved earth berm and anchor cable in large over-excavation foundation pit engineering, the theoretical model of anchor cable internal force under over-excavation considering the earth berm is deduced based on the elastic resistance method and the slip line field theories. Furthermore, combined with practical engineering cases, the influence law of control factors on anchor cable internal force is explored, and the corresponding construction parameter optimization is proposed. The main conclusions can be drawn as follows: (i) stratum unit weight, internal friction angle, and cohesion are all closely related to the moment of anchor cable, and appropriate improvement of active side soil (increasing internal friction angle and cohesion) will significantly reduce anchor cable internal force caused by deep excavation; (ii) anchor cable internal force can be obviously reduced by increasing relaxation coefficient and compactness of earth berm; (iii) when earth berm top width exceeds 7m, it has little effect on anchor cable internal force; when earth berm height reaches about 20m, the anchor cable is no longer needed to provide support; (iv) due to the comprehensive influence of inclination, height and top width of earth berm, there is a critical line of anchor cable internal force; when top width is less than the critical value, anchor cable moment increases with the increase of inclination, which is opposite to that when top width is greater than the critical value; therefore, it is better to increase top width and inclination. [ABSTRACT FROM AUTHOR]

In order to investigate the freezing damage problem of berms of earth-rock dams in cold regions, an earth-rock dam in a cold region was selected as the research object in this study. A finite element model, considering the effect of thermo-hydro-mechanical coupling, has been developed to solve the problem by combining the characteristics of the earth-rock dam. The whole process of freezing damage of berms under the influence of the reservoir level and the water migration of the dam filling was investigated, and the laws in temperature, humidity and displacement of earth-rock dams were analyzed. The calculated displacement field was then compared with the measured frozen deformation data to validate the results of the finite element simulation. The results showed that the freezing influence range of the dam slope was about 2 m, the range of temperature influence on the dam slope mainly depended on the depth of freezing, and the temperature change in the shallow range (0–2 m) of the dam slope was influenced by the outside air temperature. Also, the internal temperature of the dam body was small relative to the shallow dam slope, and there was a certain hysteresis. In addition, the effect of negative temperature was such that the shallow pore water phase of the dam slope turned into ice, manifesting macroscopically as a reduction in unfrozen water content. Water phase change, water migration from the dam filling to the dam slope, and the movement of the ice peak towards the dam body were found to be the main causes of berm freezing and expansion damage. The calculated amount expansion (due to freezing) of the dam slope was found to be in the range of 20–30 cm with a maximum value of 36 cm, which was consistent with the measured results. It was also found that the freezing and expansion damage of the berm is mainly caused by the joint action of freezing and expansion of the soil and rock mixture such as gravel bedding and dam filling, as well as the ice thrust force. It is expected that the results of this research can provide a basis for the design of berms of earth-rock dams in cold regions. • Berm frost heaving damage is caused by soil-rock mixture freezing and ice thrust. • Water migration from inside to slope is a key factor of berm frost heaving damage. • Study berm frost heaving damage by considering thermo-hydro-mechanical coupling. • Analyze the temperature, moisture, and displacement fields of earth-rock dams. • Validate calculation results by comparing them with measured data. [ABSTRACT FROM AUTHOR]

This study documents the occurrence of several MISS such as laminated microbial mats, biostabilized ripples, gas domes, mat folds, erosional pockets and remnants, microbial cracks, and gypsified mat chips in Salman hypersaline lagoon, north Jeddah city, Saudi Arabia. This study indicates that both microbial and physical processes are reponsible for sediments biostablization and formation of spits, bars and berms. It focuses on the role of waves generated by winds in erosion of the microbially, biostabilized sediments and their deposition on the eastern shore of the semi-closed Salman lagoon. In winter months, the floor of the lagoon shows a rippled surface that mantled with green to black microbial mats. In summer months, gypsum crystals grow on the surface of the mats and develop a gypsified microbial crust. A slight agitation of the lagoonal water in winter months partially erodes the mat layer and impart a black stain to the water column of the lagoon. In summer months, strong agitation of the waves generated by winds in the lagoon leads to erosion of the gypsified micribial crusts and underlying bioclastic and gypsum layers into gravelly mat chips that leave erosion pockets surrounded with erosion remnants. The gravely, eroded sediments are transported by a longshore current and deposited on the eastern shore of the lagoon as berms, spits and bars. The spits and bars enclose small, shallow pools filled with mud sediments. The result of this study provides useful data to elucidate processes of change in coastal landforms due to bio-stabilization by microbial mats and their erosion by waves induced by wind. [ABSTRACT FROM AUTHOR]

It present the stability studies for different coastal structures obtained by physical model studies. It was done at the Laboratorio di Ingeneria Costiera (LabLInc) of the Department of Civil, Architectural and Environmental Engineering (DICEA) of the University of Naples Federico II, It was done a preliminary study using rock to form the armour of the breakwater, as result the failure of the structure was verified. A new design was done for a low crest of breakwaters and berms, using concrete cubes for the armour. The tests results demonstrated that the berms failed for the higher wave heights. For breakwaters the failure is associated with the location at breaking zone, it is recommend to apply an concrete element with more interconnection, and pay attention to the toe protection of the structures. [ABSTRACT FROM AUTHOR]

This paper present other part of the extensive experimental campaign by physical model in order to obtain an effective solution to reduce the wave overtopping in the Malecón traditional. It was determined the wave overtopping rate for the current situation and for two typologies of seawalls and seawalls combined with berms. It presents a comparative study, taking into account the alternative fulfill the admissible rate of 50 L/ms as project restriction. The testes confirm that the combination of the seawall and berm has the best results for the wave and water level studies conditions, and for the technical restrictions. [ABSTRACT FROM AUTHOR]

Berms deployed at the toe of conventional breakwaters may be needed to reduce bottom settlements and to limit scour in front of the structure due to coastal currents. In the mean time, they may be effective in increasing the stability of the armor layer and also in minimizing the wave overtopping discharge compared to straight sloped conventional breakwaters without a berm. This research aims to provide a new design criterion for the armor layer of conventional breakwaters with submerged berms marked by small thickness compared to water depth. Indeed, past researches focused on the influence of relatively high berms on the stability of the armor layer. The design of the berm itself is not tackled herein. The effects of submerged berms on the incident waves transformation have been evaluated by means of a numerical model, validated by using experimental data. Then, a parametric correction factor of the incident significant wave height at the toe of the structure is provided and included in well established design criteria. The experimental comparison confirms the reliability of the proposed method by highlighting the importance to use design criteria within their validity ranges, in order to avoid an unsafe dimensioning of the armor elements. [ABSTRACT FROM AUTHOR]

A pilot scale free water surface (FWS) wetland with provision of additional intermediate berms composed of gravel material was tested for assessing its potential to remediate hydrocarbons present in produced water from a gas field. The average influent BTEX values were as follows: benzene (1.57 mg/L), toluene (0.14 mg/L), ethyl benzene (0.29 mg/L), m and p-xylene (2.01 mg/L) and o-xylene (0.13 mg/L). The FWS wetland removed all monitored hydrocarbons with very good removal efficiencies during the monitoring period: benzene (92.6%), toluene (93.4%), ethyl benzene (98.3%), m and p-xylene (91.3%) and o-xylene (87.4%). Biodegradation was considered to be the main pathway for benzene removal in the studied system. Reaction kinetics were studied and the first-order area based rate coefficient for benzene was 0.13 m/d while for BTEX it was 0.12 m/d. Metagenomic analysis of bacterial community retrieved from the wetland showed majority of sequences were related to phylum proteobacteria . [ABSTRACT FROM AUTHOR]

Research shows grab sampling is inadequate for evaluating military ranges contaminated with energetics because of their highly heterogeneous distribution. Similar studies assessing the heterogeneous distribution of metals at small-arms ranges (SAR) are lacking. To address this we evaluated whether grab sampling provides appropriate data for performing risk analysis at metal-contaminated SARs characterized with 30-48 grab samples. We evaluated the extractable metal content of Cu, Pb, Sb, and Zn of the field data using a Monte Carlo random resampling with replacement (bootstrapping) simulation approach. Results indicate the 95% confidence interval of the mean for Pb (432 mg/kg) at one site was 200-700 mg/kg with a data range of 5-4500 mg/kg. Considering the U.S. Environmental Protection Agency screening level for lead is 400 mg/kg, the necessity of cleanup at this site is unclear. Resampling based on populations of 7 and 15 samples, a sample size more realistic for the area yielded high false negative rates. [ABSTRACT FROM AUTHOR]

Prediction of overtopping rate plays a key role in the design and safety assessment of breakwater structures. In this study, the mean wave overtopping rate at hardly and partly reshaping berm breakwaters were investigated by means of small-scale physical model tests. The test program was designed to create a database with a wider range of wave steepness, berm width, berm level and crest level for the hardly/partly reshaping conditions with an initial slope of 1:1.50. The new formula was developed covering the comprehensive test conditions (including existing tests and newly-collected ones) using scaling arguments and data mining techniques. Dimensionless governing parameters were used in the development of the formulae, and it was found that the new formula represented the influence of relative water depth on the wave overtopping rate better than the other prediction models. Accuracy metrics such as RMSE and Bias indicated that the developed formula outperformed the existing prediction models within the range of significant overtopping rates. Moreover, the developed formula is simple and gives better insights into the physical significance of the variables in the overtopping process, and thus it is hoped it will be more appealing for engineering applications. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Submerged berms are an increasingly used coastal defense structure for beach nourishment because of their eco-friendly nature. A beach-nourishment project that included sand placement on the beach and in the nearshore area as a submerged berm was carried out in the winter of 2010 on West Beach in Qinhuangdao, China. West Beach is a low-energy beach characterized by small wave heights, a small tidal range, and low tidal-flow velocities. An analysis of the postnourishment beach profile evolution was conducted based on beach profile surveys from 2011 to 2014. The analysis showed that the most active parts of the profiles were the berm and the submerged berm, whereas the remaining parts of the profiles remained relatively stable. The cross-shore profiles of the submerged berm evolved significantly from roughly symmetrical shapes to asymmetrical shapes, which can be explained by applying the concept of equilibrium wave-energy dissipation per unit of water to a low-energy beach with a submerged berm. Empirical orthogonal function analysis was conducted on the beach profile surveys, which confirmed the features of the background-berms pattern gained from the evolution analysis. The first three eigenfunctions corresponded to the mean beach profile, the volume changes of the berm and the submerged berm, and the change in the submerged berm from roughly symmetrical to asymmetrical in shape, respectively. Finally, a new equilibrium beach profile (EBP) form was developed to represent low-energy sandy beaches with submerged berms. The findings in this paper contribute to the understanding of cross-shore beach morphodynamics and can provide a reference for beach nourishment under similar conditions. [ABSTRACT FROM AUTHOR]

Most studies have evaluated the effects of soil redistribution under water erosion or tillage erosion within hill slope landscapes, yet few studies have demonstrated soil particle redistribution from the sloping lands with a hedge berm. In this study, soil particle redistribution and fractal dimension from sloping lands with or without a hedge berm were investigated. The main radius of soil particles being redistributed from the sloping lands ranged between 0.002 and 0.02 mm, whether or not a hedge berm existed. However, there were significant differences between sloping land with a hedge berm and without a hedge berm ( P < 0.05). The values of the bias coefficient ranged from −0.893 to −0.817, and the values of peak convex coefficient ranged from −1.619 to −1.371. And the order of values of the fractal dimension for land with a hedge berm of 10 cm height was as follows: upper slope > middle slope > lower slope, and the sequence of the values of fractal dimension from sloping land without a hedge berm was upper slope >middle slope > lower slope. There was also a significant difference between the upper ( US) and middle slope ( MS) position ( P < 0.05), and results also showed highly significant correlations ( R2=0.9088 without hedge berm, R2 = 0.9048 with hedge berm, respectively). A regression analysis was performed to establish the logarithmic relationship between peak convex coefficient and soil depth ( R2 = 0.9461 without hedge berm, R2 = 0.9780 with hedge berm, respectively). The correlation between fractal dimension and bias coefficient was significant ( P = < 0.05). Our results suggest that fractal dimension, bias coefficient and peak convex coefficient were sensitive indices to evaluate the soil particle redistribution and the farming activities, such as building a hedge berm, could better describe the characters of soil structure and soil particle redistribution from sloping cultivated land. [ABSTRACT FROM AUTHOR]

When mound breakwaters are placed on steep sea bottoms in combination with very shallow waters, the design of the toe berm becomes a relevant issue. Toe berms built close to the water surface on a steep sea bottom must withstand such high wave loads that their design may not be feasible with available quarrystones. In this study, a new design method was developed to reduce the rock size by increasing the toe berm width. The analysis involved specific 2D small-scale tests with toe berms of different rock sizes and widths, placed on a m = 1/10 bottom slope with the water surface close to the toe berm crest. Two new concepts were introduced to better characterize damage to wide toe berms: (1) the most shoreward toe berm area which effectively supports the armor layer, in this study referred to as the primary or “nominal” toe berm and (2) the most seaward toe berm area which serves to protect the nominal toe berm, in this study called the secondary or the “sacrificial” toe berm. Damage to the nominal toe berm was used to describe hydraulic stability of wider toe berms. Given a standard toe berm of three rocks wide (nominal toe berm), an equivalent toe berm with damage similar to the nominal toe berm was defined by increasing the berm width and decreasing the rock size. The reduction in rock size showed an inverse 0.4-power relation with the relative berm width. [ABSTRACT FROM AUTHOR]

Copyright of Scientific Papers of Silesian University of Technology. Organization & Management / Zeszyty Naukowe Politechniki Slaskiej. Seria Organizacji i Zarzadzanie is the property of Silesian Technical University, Organisation & Management Faculty and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

An analytical method is proposed in this paper to calculate the maximum embedded depth of a dragged Hall anchor when passing through rock berm and to thus define a minimum buried depth of pipelines in rock berm to prevent pipelines from being damaged by dragging anchors. The movement of a Hall anchor in rock berm is interpreted based on the equilibrium conditions for resisting and driving moments acting on the anchor. To verify the accuracy of the proposed analytical method, model tests were carried out by using three scaled Hall anchor models and dragging them through rock berm. The comparisons between the two studies show that the average value of their differences for the stable embedded depth of a Hall anchor in sand and in rock berm are only 1.7% and 2.7%, respectively. The good agreements indicate that the proposed method is accurate enough to calculate the minimum buried depth of pipeline in rock berm during pipeline design. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A procedure for obtaining the dynamic characteristics of rock berms in the event of an anchor collision is developed, a safety analysis is performed, and associated recommendations are made. The drag coefficients of five target anchors were obtained through finite element flow analysis, and their terminal velocities calculated to maximise colliding kinetic energy. The dynamic behaviours of the rock berms were modelled by smoothed particle hydrodynamics (SPH). Six parameters were considered in the collision analysis: anchor type, collision velocity, SPH particle size, ground state, rock berm size, and collision point. The results were verified by an existing field test and a safety analysis was carried out with respect to parameter variation; the associated recommendations are discussed. It was found that rock berm height is the most critical factor in ensuring the safety of power cables. Rock size and installation depth are important to satisfy the safety criteria established in this study. [ABSTRACT FROM AUTHOR]

The toe berm is a relevant design element when rubble mound breakwaters are built on steep sea bottoms in breaking conditions. Different design formulas can be found in the literature to predict the damage caused to submerged toe berms placed on gentle bottom slopes. However, these formulas are not valid for very shallow waters in combination with steep sea bottoms where toe berms receive the full force of breaking waves. To guarantee breakwater stability in these conditions, new design formulas are needed for toe berms. To this end, physical model tests were carried out and data were analyzed to characterize rock toe berm stability in very shallow water and with a bottom slope m = 1/10. Based on test results, a new formula was developed with three parameters to estimate the nominal diameter ( D n 50 ) of the toe berm rocks: water depth at the toe ( h s ), deep water significant wave height ( H s0 ), and deep water wave length ( L 0p ). [ABSTRACT FROM AUTHOR]

Coastal flood risk from coincident high tides and energetic waves is concentrated around low-lying urban areas. Municipalities construct temporary sand berms (also known as sacrificial dunes) to manage potential flooding, however the relationships between berm geometry (e.g., height, width and length) and performance are not understood. Concomitant pressures of sea level rise and urbanization will increase active beach berming. Effective future coastal flood risk management will depend upon optimizing berm efficacy relative to geometry, placement, and water levels. Here, 34 individual berms at seven southern California locations are characterized using 18 LiDAR datasets spanning nearly a decade. Three berm classifications emerged based on deployment duration: event, seasonal and persistent. Event berms, deployed to manage specific storms or high water events, are triangular in cross-section, relatively low volume (∼4 m 3 /m) and low crest elevation (∼5 m NAVD88). Seasonal berms are larger, volumes vary from 6 to 28 m 3 /m, and average crest elevations are between 5.3 and 6.4 m. A persistent berm, captured in all LiDAR data for that area, is the largest (48 m 3 /m), longest (1.2 km), and highest mean crest elevation (7 m NAVD88) of all study berms. Total water levels, estimated using observed tides and a regional wave model coupled with an empirical runup formula, suggest that overtopping is rare. Currently, event berms are vulnerable to wave attack only a few hours per year. However, even with modest sea level rise (∼25 cm) or El Niño conditions, exposure increases significantly, and substantial nourishments may be required to maintain current flood protection levels. [ABSTRACT FROM AUTHOR]

Taiwan is located in the circum-Pacific seismic belt. Berms served as protections of riverbanks were all designed without taking seismic bearing capacity into account in the past. Therefore failures of berms occurred frequently even the magnitude of an earthquake was not large enough. For the long term stability of berms, an equation of seismic bearing capacity is presented in this paper. Such an equation has been proved to be able to capture seismic bearing capacity failure of berms in Taiwan. [ABSTRACT FROM AUTHOR]

Morang, A.; Waters, J.P., and Stauble, D.K., 2014. Performance of submerged prefabricated structures to improve sand retention at beach nourishment projects. Submerged breakwaters were examined to evaluate their performance in maintaining the natural beach and retaining beach fill. These included sites where prefabricated concrete reefs, sills, and ball-like reef structures had been deployed. Most of these innovative structures have not performed well in exposed, open-coast, settings unless they were mounted on hard bottom. The Cape May Point, New Jersey, Section 227 demonstration site was used to develop a conceptual analysis model. The project monitored the functional, structural, and economic performance of two innovative prefabricated concrete structures placed at the seaward end of a groin compartment to form an enclosed sill. The project was conducted in conjunction with an ecosystem restoration beach fill to assess if a Beachsaver Reef™ and a Double-T sill could help to hold fill sediment in place at the entrance to Delaware Bay, which is influenced by high wave energy and strong tidal currents. The Beachsaver Reef™ units appear to be retaining the fill sand, while the Double-T sill settled completely into the bed and is no longer functioning as intended. Settlement and scour of these prefabricated units present the most problems in project performance. Wave attenuation performance is poor when the units settle, and they are better suited to act as a sill to hold sediment on a beach. Guidance is provided from the conceptual model at Cape May Point on the components that are needed to monitor a successful project. Criteria are given on how to evaluate project performance. [ABSTRACT FROM AUTHOR]

Measuring infiltration at the plot scale is difficult, especially for high hydraulic conductivity soils. At the plot scale, the infiltration rate is usually calculated by comparing surface runoff to rainfall. Direct measurement of infiltration beyond the point scale is typically limited to locations where land forming (e.g., infiltration pond) has been performed or fields with basin irrigation systems. The standard method for field measurement of point-scale infiltration is the double ring infiltrometer, which is limited in size (typically 30 cm diameter). In this research, a new method is proposed that uses a temporary berm constructed of a water-filled 15-cm diameter vinyl hose with the edges sealed to the soil using bentonite. The berm is capable of confining infiltration plot areas of various sizes (e.g., and areas in this research). Water tanks with 0.8 and capacity were used to supply water to the plots by gravity flow. A constant head could be maintained within the plot using either an automatic float valve for lower infiltration rates or a manually operated gate valve for higher infiltration rates. Observation wells were installed outside the plots to monitor for water table rise and tracers that leached into the groundwater. Guidelines are provided for tank size and refilling frequency for conducting field experiments. The procedure was tested on soils ranging from silt loam to coarse gravel using 12 and plots at three alluvial floodplain sites. Measured infiltration rates ranged over two orders of magnitude () and were typically greater than the estimated permeability of the limiting layer reported in soil surveys, suggesting the need for larger scale field measurements of infiltration rates. [ABSTRACT FROM AUTHOR]

A comprehensive assessment of the tree growth/climate relationship was undertaken to better understand the potential impacts of climate change on the growth dynamics of four widespread and common boreal tree species, namely jack pine (Pinus banksiana) , black spruce (Picea mariana) , eastern larch (Larix laricina) , and trembling aspen (Populus tremuloides), located at the southern limits of the Canadian boreal forest. Over intra-annual time scales, results show that precipitation is likely the main driver of stem radius change (∆R), with jack pine radius exhibiting the most consistent positive relationship. Precipitation had a stronger relationship with stem radius variation in black spruce and eastern larch during periods when volumetric water content (VWC) in the root zone was below average, pointing to the likelihood that certain species rely more heavily on available moisture in the uppermost layers of the soil column to replenish stem water, especially during extended dry periods. Warm air temperatures had an immediate negative impact on stem water content due to transpiration. This was most marked during periods of reduced moisture availability in the root zone, when trees are more susceptible to net water volume loss. During periods when moisture was not limiting, a positive relationship between lagged air temperature and ∆R was detected. Warm air temperatures may therefore play an important role in stimulating radial growth when moisture requirements are met. At annual temporal resolution, the growth/climate relationship changed over the lifetime of our study species. Over the last several decades, the relationship between precipitation and annual radial tree growth has weakened, while positive relationships between spring and summer air temperature and annual radial tree growth have emerged, likely signaling a decrease in moisture limitations, and a positive response to spring warming. Our findings reveal that boreal forest tree species may benefit from spring and summer warming over the near term, providing there is sufficient moisture to support growth. Over the long term, rates of evapotranspiration are expected to overshadow gains in moisture related to an increase in precipitation. Under these circumstances, we are likely to see reduced growth rates and an increasingly negative response of boreal tree species growth to warm air temperatures. [ABSTRACT FROM AUTHOR]

Abstract: A new stability formula is proposed for the toe protection of rubble mound structures. The new approach is based on a critical stability number that refers to the initial movement of armour stones on the toe berm. Damage progression is subsequently described by the ratio of actual and critical stability numbers. The ratio of toe berm submergence and incoming wave height has been identified as the governing parameter for the toe stability. Other parameters including sea bed gradient, wave steepness and toe berm geometry were found to be of minor importance. The new toe stability formula has been validated against model test results and has been compared with the widely used formula of van der Meer (1998). The new approach appears more accurate and more physically meaningful. The practical application of the new formula for toe berm design is briefly described. [Copyright &y& Elsevier]

Abstract: The formation of berms and their transformation into beach ridges in a micro-tidal environment is coupled to wave run-up and overtopping during extreme sea levels. A straight-forward comparison between extreme sea levels due to storm-surges and active berm levels is impossible in the semi-enclosed bays along the Baltic Sea. Quite often, the maximum water levels do not coincide with the maximum intensity of the wave driven processes because of seiches in the Baltic. In this paper, we look into the joined distribution of extreme water levels and high-energetic wave conditions at Feddet, a sandy prograding spit on the south-eastern Baltic shores of Zealand, Denmark. The modern, sandy beach at this location consists of a beachface with a shallow incipient berm, a mature berm, and a dune-covered beach ridge. It borders a beach-ridge plain to the west, where more than 20N–S oriented beach ridges and swales are present. Measured water-level data from 1991 to 2012 and topographical observations, carried out during fair weather period and during a storm event, provided the basis for a conceptual model exhibiting berm formation and transformation into the local beach-ridge system. The character of extreme sea level events is identified using thirty-three well described extreme events throughout a period of 15years. Analysis of the meteorological conditions during these events revealed that berm formation only occurred during 20% of all extreme events when onshore winds, high-energy wave action and elevated water coincided. These berm-forming events had a mean return period of once every three years. The average age between successive beach ridges on the beach-ridge plain was about 180years, which means that the transformation of a berm into a single beach ridge is the result of a large number of storm episodes with high-energy waves and extreme water levels. [Copyright &y& Elsevier]

Abstract: Breakwaters with a berm can significantly reduce overtopping and reduce the required rock size compared to straight slopes without a berm. Here, the stability of rock slopes with a horizontal berm has been studied by means of physical model tests to provide information on the required rock size. The tests and analysis are focussed on the slope above the berm as well as the slope below the berm. Also the stability of the rock at the berm is addressed. The influence of the slope angle (1:2 and 1:4), the width of the berm, the level of the berm, and the wave steepness has been investigated. Based on the test results prediction formulae have been derived to quantify the required rock size for rubble mound breakwaters with a berm. Especially for the slope above the berm, the rock size can be reduced significantly compared to straight slopes. [Copyright &y& Elsevier]

Abstract: The short communication presents application of the conventional Van der Meer stability formula for low-crested breakwaters for the prediction of front slope erosion of statically stable berm breakwaters with relatively high berms. The method is verified (Burcharth, 2008) by comparison with the reshaping of a large Norwegian breakwater exposed to the North Sea waves. As a motivation for applying the Van der Meer formula a discussion of design parameters related to berm breakwater stability formulae is given. Comparisons of front erosion predicted by the use of the Van der Meer formula with model test results including tests presented in Sigurdarson and Van der Meer (2011) are discussed. A proposal is presented for performance of new model tests with the purpose of developing more accurate formulae for the prediction of front slope erosion as a function of front slope, relative berm height, relative berm width, method of armour stone placement, and hydraulic parameters. The formulae should cover the structure range from statically stable berm breakwaters to conventional double layer armoured breakwaters. [Copyright &y& Elsevier]

Schmidt-hammer exposure-age dating ( SHD) was applied to three flood berms in upper Vetlestølsdalen, southern Norway, using a local, high-precision calibration curve that takes account of the colluvial origin of fluvial boulders in the youngest berm, which was deposited during the August 1979 flood. Precision of SHD dating for this berm was estimated as ±210 years, whereas predicted ages of the two older berms were 3195 ± 435 and 3405 ± 340 years, and subsections of the oldest berm yielded age ranges of ∼900 years. The results demonstrate the feasibility of high-precision SHD in the context of boulder landforms deposited by high-magnitude floods, the requirement of a large sample of R values in the face of high natural variability, the necessity of an appropriate calibration curve to ensure accuracy, the usefulness of floods of known age for testing and improving calibration curves, and the potential effects of boulders of colluvial origin on R values (especially the susceptibility of young surfaces to roughness variations). The dated berms indicate a return period of ∼1000-1500 years for floods of the magnitude of the 1979 flood event in the upper catchment. Thus, the long-term persistence of flood boulder berms in the landscape has potential for reconstructing Holocene flood history and palaeohydrology from the geomorphic legacy of the most extreme Holocene floods. [ABSTRACT FROM AUTHOR]

New England has an extensive history in restricting salt marsh tidal flooding to promote agricultural, industrial, and environmental endeavors. While previous research has focused on the physical and biological impacts of large-scale tidal restrictions, such as dikes and undersized culverts, the effect of smaller historic earthen barriers (average height = 0.71 m ± 0.12 SE; average length = 166 m ± 41 SE), or berms, is less understood. Here, we investigate how salt marsh plant communities respond to berms located in the interior of the marsh and oriented parallel to tidal rivers or creeks. Based on the observations from a descriptive study, the landward side of the berm consistently shows a distinct plant species assemblage from the reference areas (ANOSIM: R = 0.541, p = 0.001), which is most likely a result of landward pool development. A follow-up manipulative transplant experiment considers how the landward pools affect the governing factors (e.g., physical stress, competition, etc.) controlling the distribution and abundance of Schoenoplectus maritimus and Spartina patens in the landward and seaward zones. The experimental results show that while physical stress seems to prevent robust S. patens growth in the landward zone (ANOVA: F = 24.697; p < 0.001), herbivory seems to be the main driving factor behind the low S. maritimus cover found in the seaward zone (Mann-Whitney: U = 56, p = 0.015). The combined results from the two studies show that berm-associated pools have the potential to impact biological interactions within and across trophic levels in salt marshes. [ABSTRACT FROM AUTHOR]

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As a part of a larger study designed to develop compost filter berms i.e., an unsupported mound of compost that intercepts surface runoff from a site, suitable for removing nutrients and sediment from agricultural operations, we evaluated the hydraulic behavior of compost buffers with different masses and particle size distributions subjected to varying water flow rates using flume experiments. For each berm combination, the maximum flow rate the compost berm could sustain before a structural failure occurs was determined for different compost particle sizes. These data were used to develop models to predict headloss through a compost berm as a function of the flow rate per unit width, the median particle size of the compost media, and the buffer dimensions. The developed models perform well with R values ranging from 0.64 to 0.97 with the majority of values greater than 0.9. The effect of presence of sediments in the flow was also quantified. The results show that headloss increased by 1-2 cm as a result of sediment removal, ranging from 5 to 35%, taking up pore space in the compost berm. [ABSTRACT FROM AUTHOR]

This case study on the Mississippi River Gulf Outlet earthen berm/spoil bank (EBSB) illustrates a method to quantitatively analyze wave-induced lateral erosion and breaching through the flood side of coastal flood protection levees with grass armor prior to overtopping. Lateral wave-induced erosion was evaluated based on a three-step process: (1) velocity profiles were generated using a general purpose transient dynamic finite element program; (2) resistance to wave-induced erosion as a result of grass cover (turf) on the flood face of the EBSB was estimated and no wave-induced erosion was applied until the grass cover protection failed; and (3) estimated soil erodibility characteristics were used, in combination with the estimated wave-induced flood face velocities, to estimate the magnitude of lateral erosion. This case study identified that soil erodibility characteristics directly impact coastal flood protection levee performance, grass/turf armoring provides erosion protection for a limited duration, and identification and evaluation of pre-overtopping wave-induced erosion is an important failure mode to be considered in order to ensure reliable coastal flood protection. [ABSTRACT FROM AUTHOR]

The scope of this paper is to develop a new three-part wedge method to analyze translational failure when using an engineered berm to increase landfill space. The possible failure face may pass over the back slope of the berm or pass under the bottom of the berm. This depends on the geometric dimensions of the berm which in turn influences the amount of airspace gained. Each possible failure condition must be checked to make sure both the waste mass and berm remain stable. If the waste boundary is kept to be unchanged, FSover will increase and FSunder will decrease with increase of the back slope of the berm. The critical failure condition may be changed from passing over to passing under the berm by changing the back slope of the berm. If the location of the front toe of the berm is fixed, both FSover and FSunder increase with increased height of the berm, however, the critical failure condition will change from passing under the berm to passing over the berm. [ABSTRACT FROM AUTHOR]

The prediction of berm and dune erosion during a storm is essential for storm damage assessment. Simple and transparent formulas for the cross-shore and longshore transport rates of suspended sediment and bed load on beaches are proposed and incorporated into a combined wave and current model to predict the berm and dune erosion under normally and obliquely incident irregular waves. Two small-scale experiments for two different berm profiles were conducted for the calibration of the developed numerical model. The calibrated numerical model is shown to predict the measured berm and dune erosion in these experiments as well as dune erosion measured in three large-scale tests with errors less than a factor of two. The numerical model is used to examine the effects of the wave period and incident wave angle on the berm and dune erosion. These effects are computed to be within a factor of two. [ABSTRACT FROM AUTHOR]

The present work involves the investigation of the influence of wave height, wave period, water depth, and sea-ward slope on the stability, wave runup, and wave rundown of statically stable rubble-mound berm breakwater. The weight of armor stones used in the present study is 20% lighter than the weight that is required for a conventional breakwater, designed using Hudson formula for a wave height of 0.1 m in the model. In the present work models with a berm width of 0.6 m, at constant depth of 0.32 m from the seabed were tested. The damage to the breakwater model with the berm was compared with the results on a model without the berm using different armor weights. The variation of relative runup and rundown was found for different values of wave steepness and water depths in front of the structure. The damage to the breakwater, wave runup, and rundown for the structure with seaward slope 1:2 and 1:1.5 were compared. The investigation was carried out in the Marine Structures Laboratory, Department of Applied Mechanics and Hydraulics, National Institute of Technology Karnataka, Surathkal. [ABSTRACT FROM AUTHOR]

The finite element method was used to assess the influence of berms on the stability of slopes resting on rigid foundations for three different slope angles. Both purely cohesive soils and soils exhibiting cohesive and frictional strength properties were considered. The results of the analyses are presented in non-dimensional graphical and tabular form for design purposes and show that, for each case considered, there is a unique (berm width) : (slope height) ratio after which further increases in the berm width produce no further increases in stability. Example design calculations are presented and validated using Bishop's simplified method. [ABSTRACT FROM AUTHOR]