Wave Swash Research Articles

The Wave.

Description Working as a nurse is stressful. Two things that help me decompress are the beach and fused glasswork. Both of those items are represented in this piece. I hand-cut glass to represent a wave and then fused it together in a kiln at high temperatures. Waves wash away my stress. Many people find calm in the ocean, and I am one of such people. The glass mirrors the water.

Total water levels along the South Atlantic Bight during three along-shelf propagating tropical cyclones: relative contributions of storm surge and wave runup

Abstract. Total water levels (TWLs), including the contribution of wind waves, associated with tropical cyclones (TCs) are among the most damaging hazards faced by coastal communities. TC-induced economic losses are expected to increase because of stronger TC intensity, sea level rise, and increased populations along the coasts. TC intensity, translation speed, and distance to the coast affect the magnitude and duration of increased TWLs and wind waves. Under climate change, the proportion of high-intensity TCs is projected to increase globally, whereas the variation pattern of TC translation speed also depends on the ocean basin and latitude. There is an urgent need to improve our understanding of the linkages between TC characteristics and TWL components. In the past few years, hurricanes Matthew (2016), Dorian (2019), and Isaias (2020) propagated over the South Atlantic Bight (SAB) with similar paths but resulted in different coastal impacts. We combined in situ observations and numerical simulations with the Coupled Ocean–Atmosphere–Wave–Sediment Transport (COAWST) modeling system to analyze the extreme TWLs under the three TCs. Model verification showed that the TWL components were well reproduced by the present model setup. Our results showed that the peak storm surge and the peak wave runup depended mainly on the TC intensity, the distance to the TC eye, and the TC heading direction. A decrease in TC translation speed primarily led to longer exceedance durations of TWLs, which may result in more severe economic losses. Wave-dependent water level components (i.e., wave setup and wave swash) were found to dominate the peak TWL within the near-TC field. Our results also showed that in specific conditions, the prestorm wave runup associated with the TC-induced swell may lead to TWLs higher than at the peak of the storm. This was the case along the SAB during Hurricane Isaias. Isaias's fast TC translation speed and the fact that its swell was not blocked by any islands were the main factors contributing to these peak TWLs ahead of the storm peak.

Influence of Beach Slope on Morphological Changes and Sediment Transport under Irregular Waves

This paper presents new data from large-scale wave flume experiments. It shows the beach profile evolution and sediment transport for two different bed slopes (1:15 and 1:25), and three irregular high-energy erosive wave conditions and one low-energy accretive wave condition. The bulk cross-shore net sediment transport was investigated for the total active profile and for the surf and swash zone separately. It is shown that the steep slope is morphologically more active than the gentle slope, with faster and more pronounced morphological changes and larger sediment transport rates. For both slopes, the total and surf zone net sediment transport were offshore-directed for erosive waves and onshore-directed for the accretive wave condition. However, the net swash zone transport for the erosive wave conditions was offshore-directed for the steep slope and onshore-directed for the gentle slope. The direction and magnitude of the total and surf zone sediment transport correlate well with the slope-corrected Dean criterion with increasing offshore-directed sediment transport (erosion) observed for increasing wave energy and bed slope. This relation does not hold for the swash zone sediment transport along the gentle slope, suggesting that swash zone sediment transport processes are not well captured when using a simple predictor such as the (modified) Dean number. Differences in sediment transport in the swash for the different slopes are likely influenced by differences in incoming wave energy, wave–swash interactions and the relative importance of long- and short-waves.

Experimental study of the solitary wave induced groundwater hydrodynamics

Coastal groundwater hydrodynamics are affected by the swash uprush and backwash processes. In this study, laboratory experiments were carried out to investigate the solitary wave induced groundwater hydrodynamics over a coarse-grained sand beach. Pore water pressures at 27 cross-shore positions (covering both the subaqueous and subaerial areas) along 3 different beach depths were measured, and the synchronized shoreline position as well as the local water surface elevations (WSE) were also recorded. Temporal variation of the total water head (TWH) was found almost hydrostatically controlled by the instantaneous WSE in the subaqueous area. In the capillary truncated zone, the capillary effect contributes to the non-hysteresis phenomenon between the TWH and WSE. In other subaerial area, time-varying features of the TWH and WSE show clear differences in terms of their magnitudes and phases. Regarding the experimental observations, four representative regions could be identified along the cross-shore direction, i.e., Region I corresponding to the initially subaqueous area, Region II in between the still water shoreline and the top of capillary fringe (saturated beach), Region III in between the upper boundary of Region II and the maximum swash run-up, and Region IV landward beyond the Region III. With respect to the cross-shore distribution characteristics of the maximum TWH and the maximum WSE, as well as the time instants when the maximum TWH and the maximum WSE occur, different groundwater hydrodynamics were observed during the swash event in these four regions. In addition, spatiotemporal characteristics of the TWH were scrutinized and discussed. Both the vertical and horizontal TWH gradients in different regions were considered to reveal the sophisticated groundwater hydrodynamics. Finally, the groundwater movement pattern and its percolation circulation under the solitary wave swash were also specified. • Solitary wave induced groundwater hydrodynamics are investigated through detailed laboratory experiments. • Four regions are identified regarding the spatial characteristics of the maximum total water head and its occurrence time. • Hydrostatic effect, capillary effect and the wetting front are significant for the swash groundwater hydrodynamics. • Horizontal groundwater seepage flow is evident, even larger than the vertical one, during the entire swash process. • Two groundwater circulations are observed in the subaqueous and subaerial areas during the swash cycle.

LSPIV analysis of ship-induced wave wash

Ship-induced wave wash affects the hydromorphological and ecological state of rivers through various mechanisms. The direct proximity of the riverbank is usually the most exposed, as the hydrodynamic stresses are the highest in these shallow water areas. Contrary to the steady and almost still, natural flow conditions (i.e., no waves of anthropogenic source), shoaling and breaking of ship waves increase the hydrodynamic stresses by orders of magnitudes, having notable ecological consequences, and resulting in bank erosion as well. Due to the shallow water depths and temporary drying, conventional measurement techniques are no longer applicable in these areas. In this study, large-scale particle image velocimetry (LSPIV) is used to quantify the prevailing flow conditions. In the absence of ground truth data in the wave breaking region, a high-resolution computational fluid dynamics model—verified with field pressure and acoustic Doppler velocimetry data—is used for the cross-validation of the LSPIV results. The results underline the applicability of LSPIV for the hydrodynamic analysis of wave velocities in this special riverine swash zone, which is of key importance from the aspect of ecology and bank erosion as well.Graphical abstract

Effect of hull displacement on hydro- & aerodynamics of a planing trimaran

The tunnel hydrodynamic and aerodynamic forces are the key to improve the overall resistance of planing trimaran. The variation of hull displacement has different effect on the tunnel flow characteristics at diverse sailing states, resulting in various change trend of resistance per displacement (R / △) of trimaran at various hull displacement. Combined with model tests, this paper conducts numerical investigation for the detailed analysis of hull displacement effect on the hydrodynamics and aerodynamics of a planing trimaran in various speed ranges. It is found that tunnel air cushion occurs when this trimaran running at low speed. The critical Froude Number of air cushion appearance is strongly influenced by the wave interaction in tunnel, where it may occur earlier at heavier hull load. At semi-planing speed, the difference of hull trim angle mainly accounts for the obvious discrepancy of R / △ of trimaran with different hull loads. Apart from the dominant effect of main hull, the high-pressure region at front tunnel, caused by bow wave washing, also plays a boosting role on enlarging the difference of bow-up trim angle between various load conditions. The heavier hull load leads to the stronger interaction between bow waves of main hull and tunnel at semi-planing speed. After entering planing speed, the tunnel wave crest moves astern more quickly at light-load where tunnel ventilation thus occurs earlier. The air flows through tunnel more smoothly at light load, which weaken the tunnel ram pressure effect in turn. At planing state, the variations of tunnel aero-lift and hydro-lift dominantly influence the different growth trend of trimaran R / △ at various hull loads. This work is helpful for the design and performance prediction of planing trimaran which designed for multi working conditions.

СЕЗОННЫЕ ИЗМЕНЕНИЯ СОДЕРЖАНИЯ ЧАСТИЦ МИКРОПЛАСТИКА В ПЕСКАХ ПРИБОЙНОЙ ЗОНЫ ПЛЯЖА

The paper considers the seasonal dynamics of the content of microplastic particles with a size from 0.5 to 5 mm in the sands of the surf zone of the Vistula Spit (the Baltic Sea). Microplastic particles are classified by size and color. The results are compared with the data for the Curonian Spit. It is concluded that the level of contamination with small microplastics (0.5–2 mm) of the sands of the swash zone can be used as a "background" value for the entire region and during all seasons of the year. The current level of sand contamination in the wave swash zone in the South-Eastern Baltic by small microplastic particles (0.5–2 mm) is 30–60 pieces per kg of dry weight throughout the year, while more than 90% are fibers.

Ecological causes of fluctuating natural selection on habitat choice in an amphibian.

We estimated natural selection targeting three traits related to habitat choice in a frog (Pseudacris maculata) breeding in pools on the rocky shores of Isle Royale, Michigan, over 16 years. Our aim was to identify the form and ecological causes of annual variation in directional and correlational selection as expressed in the survival and growth of tadpoles. We found directional selection favoring early breeding, but pool choice was under weak stabilizing selection. However, the form of stabilizing selection and the position of the optimum trait value shifted among years with the severity of disturbance and the intensity of biotic interactions. In years when wave wash and pool desiccation were severe, selection shifted to favor tadpoles in habitats where these risks were less pronounced. If predatory dragonfly larvae were abundant, selection favored tadpoles in small pools where dragonflies did not occur. When intraspecific competition was strong, selection favored early broods within a broader range of pool types. The agents of selection in this study—biotic interactions and disturbance—are common to many ecological systems and frequently exhibit temporal variation; this suggests that fluctuating selection may be widespread in natural populations.

Geomorphology of the Coastal Plain of the Asir Region, Using Remote Sensing and GIS Techniques, Saudi Arabia

Coastal Plain in Asir Region under investigation stretches in the southwest of Saudi Arabia. The geo-morphologic features, shoreline configuration, sediment characteristics and dynamics have been established for understanding the processes that influence the coastal environments. The shoreline of the studied area is not linear and smooth; instead, it is complicated by arcuate beaches, sharms, inlets, lagoons, barriers and rocky hills. The width of the coastal plain varies widely; it is wide and featureless towards the south of the study area while being narrow and bounded by resistant sea cliffs towards the north of the study area. Asir coastal landforms include a marsh system, inlet and swamps, wave swash, dunes, shoreline processes, beach bars, a spit system, wadi systems and sabkha systems. Conditions on such beaches change rapidly. It is a unique environment, being characterized by some of the major geological environments (e.g. coastal reefs, mangrove stands, marshes, sabkhas, alluvial fans, sea cliffs, recent sediments, sand dunes, sabkhas, sand beaches, lagoons, nebkas, wadis, coral reefs, organic matter, and vegetation areas). The aim of this paper is to follow and assess the environment and characteristics of landforms. The previous procedures happen through measuring biodiversity, landforms and geo-morphological processes on the coastline. The study uses several methods such as field study, collection of samples from different geo-morphic environments of the coastal area,comparing the geo-morphological and environmental changes from maps and also using remote sensing and GIS techniques.

Groundwater–surface water exchange in the intertidal zone detected by hydrologic and coastal oceanographic measurements

Animation S1. Subsurface saturation dynamics due to the movement of wave swash, tides, and the surface saturation boundary over a tidal cycle. Animation S2. Formation of the recharge lens in the unsaturated zone at the swash time scale during a rising tide. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

DNA mtCOI Barcodes for Maritime Biosecurity: A Proof of Concept in French Polynesia Ports

DNA barcodes have been proposed for diverse applications as markers for species identification. One application is not fully explored yet is their use for assessing the species biodiversity and presence of invasive alien species in maritime biosecurity. The phylogeographical signals of mtCOI gene have been sometimes used for inferring the number of introduction hits and the origin of biological invasions. Here we employed mtCOI barcodes of mollusks and acorn barnacles (N=751) from ports of the Windward Island of French Polynesia to infer the effect of port size, maritime traffic and degree of openness in the risk of biological invasions. With 17.2% of non-indigenous species recorded here, significant differences in diversity were found among docks, and between long-time docked ships and their closest piers. A higher proportion of non-indigenous species (NIS) was found from sheltered compared to open ports, regardless their size and traffic. Less frequent wave washing, lower effect of currents and partial isolation in sheltered ports could explain the difference. The results suggest that port biota surveys should focus first on ports sheltered from open sea and emphasize the value of mtCOI barcodes for early detection of potential invasive species, for prioritizing surveillance efforts.

Using a calibrated upper living position of marine biota to calculate coseismic uplift: a case study of the 2016 Kaikōura earthquake, New Zealand

Abstract. The 2016 Mw=7.8 Kaikōura earthquake (South Island, New Zealand) caused widespread complex ground deformation, including significant coastal uplift of rocky shorelines. This coastal deformation is used here to develop a new methodology, in which the upper living limits of intertidal marine biota have been calibrated against tide-gauge records to quantitatively constrain pre-deformation biota living position relative to sea level. This living position is then applied to measure coseismic uplift at three other locations along the Kaikōura coast. We then assess how coseismic uplift derived using this calibrated biological method compares to that measured using other methods, such as light detection and ranging (lidar) and strong-motion data, as well as non-calibrated biological methods at the same localities. The results show that where biological data are collected by a real-time kinematic (RTK) global navigation satellite system (GNSS) in sheltered locations, this new tide-gauge calibration method estimates tectonic uplift with an accuracy of ±≤0.07 m in the vicinity of the tide gauge and an overall mean accuracy of ±0.10 m or 10 % compared to differential lidar methods for all locations. Sites exposed to high wave wash, or data collected by tape measure, are more likely to show higher uplift results. Tectonic uplift estimates derived using predictive tidal charts produce overall higher uplift estimates in comparison to tide-gauge-calibrated and instrumental methods, with mean uplift results 0.21 m or 20 % higher than lidar results. This low-tech methodology can, however, produce uplift results that are broadly consistent with instrumental methodologies and may be applied with confidence in remote locations where lidar or local tide-gauge measurements are not available.

Intertidal sedimentary dynamics in Mont-Saint-Michel bay, a study of its natural evolution and man-made modifications

Due to its exceptional tidal range and the immensity of its intertidal zones, Mont-Saint-Michel is a favored model for research on coastal hydro-sedimentary processes, present-day sedimentary dynamics and the reconstruction of coastal paleo-environments. The purpose of this article is to analyze the erosion/sedimentation processes which govern the sedimentary dynamics and the recent evolution of the characteristic sedimentary environments of the bay. The western bay head is made up of tidal sand and silt deposits, where the extent of the surface sediment reworking is less than 10 cm and linked to the nature of the substrate and the wind direction. Added to these tidal dynamics are the dynamics of the swell, which set coarse bioclastic sands in motion as the waves wash away the shore. These sands migrate on the tidal flat at rates of several dozen m/year and accumulate on the upper tidal flat, forming a relatively stable non-continuous coastal barrier of large shell banks. The eastern part of the bay is an estuarine zone, where the morpho-dynamics of the sandy tidal flat are constrained by shifting channels. Studies of the interaction between vegetation and sedimentation around Mont-Saint-Michel show sedimentary accretion rates varying from 0.2 to 10 cm/year, depending on the morpho-dynamic context of the salt marsh front. The volume of sediment deposited by the tide leads to cyclical deposition of calcareous muds followed by the steady advance of salt marshes at a rate of about 17 ha/year between La Chapelle Sainte-Anne and the Roche Torin point. The bay has filled for thousands of years to the rhythm of sea level oscillations, leading to the gradual infilling of the Dol marsh and the advance of the shoreline. In addition to this natural evolution, human activities have developed in the bay, both on the western tidal flat (fixed fisheries and shellfish farming) and on the eastern estuarine side (polder formation, construction of dikes and a dam) and have altered the landscapes, the historical evolution of which was reconstructed from old documents.

Below-ground biomass of plants, with a key contribution of buried shoots, increases foredune resistance to wave swash.

Sand dunes reduce the impact of storms on shorelines and human infrastructure. The ability of these ecosystems to provide sustained coastal protection under persistent wave attack depends on their resistance to erosion. Although flume experiments show that roots of perennial plants contribute to foredune stabilization, the role of other plant organs, and of annual species, remains poorly studied. Furthermore, it remains unknown if restored foredunes provide the same level of erosion resistance as natural foredunes. We investigated the capacity of three widespread pioneer foredune species (the perennial Ammophila arenaria and the annuals Cakile maritima and Salsola kali) to resist dune erosion, and compared the erosion resistance of Ammophila at natural and restored sites. Cores collected in the field were tested in a flume that simulated a wave swash. A multi-model inference approach was used to disentangle the contributions of different below-ground compartments (i.e. roots, rhizomes, buried shoots) to erosion resistance. All three species reduced erosion, with Ammophila having the strongest effect (36 % erosion reduction versus unvegetated cores). Total below-ground biomass (roots, rhizomes and shoots), rather than any single compartment, most parsimoniously explained erosion resistance. Further analysis revealed that buried shoots had the clearest individual contribution. Despite similar levels of total below-ground biomass, coarser sediment reduced erosion resistance of Ammophila cores from the restored site relative to the natural site. The total below-ground biomass of both annual and perennial plants, including roots, rhizomes and buried shoots, reduced dune erosion under a swash regime. Notably, we show that (1) annual pioneer species offer erosion protection, (2) buried shoots are an important plant component in driving sediment stabilization, and (3) management must consider both biological (plants and their traits) and physical (grain size) factors when integrating dunes into schemes for coastal protection.

Beyond tides: surge-dominated submersion regimes on rocky shores of central Chile

By definition, intertidal organisms are exposed to fluctuations between submersion and exposure to air due to the variation in the sea level caused, primarily, by tides and waves. Such submersion regimes have great consequences on the evolution, physiology, behavior, and ecology of intertidal marine organisms, but, paradoxically, our quantitative knowledge about submersion regimes is extremely limited, especially in wave-exposed shores. We here quantify submersion regimes during summer (February 2012) in a wave-exposed rocky shore of central Chile (Las Cruces, 33°30′S, 71°38′W) using a remote sensing method that permits high-frequency measurements. We provide metrics of submersion for the high (barnacle), mid (mussel) and low (upper kelp) intertidal zones and developed statistical models to hindcast submersion regimes from tide and wave data. Results revealed that the submersion consists solely of numerous but brief submersion events produced by waves. The three intertidal zones therefore experience intermittent submersion most of the time, and submersion events are so brief that, in these three zones, emersion predominates over submersion. In this region, submersion cannot be determined from tidal charts, because most of the intertidal zone lies above the highest tidal level, but still the tidal cycle strongly modulates submersion regimes, by altering wave swash into the shore. Combined statistical models including tides and waves are necessary to reproduce the most biologically relevant aspects of submersion. We discuss the consequences of these findings for our understanding of adaptation to intertidal life, and the design of studies on responses to current environmental variability and future climate change.

Predicting Wave Wash Overs for Sea Turtle Nests

To better protect coastal species, researchers developed a model that predicts harmful wash overs with 83% accuracy.

The role of beach and sand dune vegetation in mediating wave run up erosion

Coastal dunes are often the first and only line of physical defense for communities subjected to damaging storms and waves. Planting vegetation on them has been proposed as one way to increase their protective capacity, but it is unknown how dune plant architecture reduces erosion. We conducted wave flume and field experiments to address this question and found that dune plants primarily reduced erosion by attenuating wave swash and run up bores with their stems and leaves, while their roots initially enhanced erosion through uprooting. After excavation, the roots also attenuated waves and reduced erosion. We then sampled the biophysical attributes of a broad distribution of plants, and found that herbaceous non-Graminoid (non-grass) species that inhabited the lowest latitudes and most seaward zones had the most efficient structures for erosion reduction. Our results suggest that there is a fundamental tradeoff in the ability of dune plant species to respond to hydrodynamic versus Aeolian processes, based on the relative allocation of aboveground versus belowground biomass. Through the combination of flume experiments, field survey, and meta-analysis, our findings show that vegetation provides on average ∼1.6 factor of safety over bare sand across a wide range of latitudes in the northern hemisphere - translating into a reduction of wave run up erosion by approximately 40% for dunes.

WAVE INDUCED CURRENT MONITORING USING UAV-BASED PHOTOGRAMMETRY

In recent years, due to the development of hardware and video image processing technology, image analysis technique using a wide coastal coastline, it made it possible to analyze the wave runup and swash, current and so on. However, in order to obtain the image information of a large area requires a high-resolution imaging at a high position, however, to the recording technique used in the past, there is a limit of height and resolution. Thus, recently, on the basis of remote sensing techniques, or build spatial information technology using UAV (Unmanned Aerial Vehicle) system, and the research and utilization in various fields it increased. Small UAV platforms is becoming low-cost, miniaturized hyperspectral imaging technology. The direct measurement of wave induce current is tested using image analysis techniques using sea dye maker and UAV. Specially, rip currents are approximately shore normal seaward flows which are strong, localized and rather narrow. In this method, UAV at a region with frequent wave induced current occurrence, and images are continuously obtained in real time. This research investigates the development of wave induced currents using images in East coast of Korea.

The influence of wave groups and wave-swash interactions on sediment transport and bed evolution in the swash zone

Large scale laboratory measurements of sediment dynamics in the swash zone are presented. Two bichromatic wave group conditions were generated, having the same energy content but different wave group period (Tg=15.0 s and 27.7 s). For the shortest wave group, due to bore focusing, the shoreline fluctuates predominantly at the Tg time scale, showing a large runup and the presence of wave–swash interactions with strong momentum exchange. In contrast, for the longer wave groups, the swash excursion is dominated by the individual waves. The uprush generally promotes onshore sediment advection with consequent erosion at the rundown location but accretion close to the runup. On the contrary, the backwash promotes seaward sediment advection and accretion at the rundown location. The presence of repeated wave–swash interactions modifies these patterns slightly. A wave overrunning a previous uprush promotes a reduction in onshore sediment advection while weak wave–backwash interactions reduce seaward advection. Consequently, the measured sediment dynamics shows stronger intra–swash cross–shore sediment advection for the swash events produced by the short wave groups. Measurements of the sheet flow layer near the shoreline show that for the shortest wave groups the vertical structure of the concentration is influenced by horizontal advection, leading to large sheet-flow layer thickness. However, for the longer wave groups, the local vertical exchange of sediment in the sheet–flow layer is dominant, with the presence of a pick–up and mirroring upper layer similar to oscillatory sheet–flow measurements. These results reaffirm the important effects of the wave group structure and the wave–swash interactions on the swash zone sediment dynamics and beach face evolution.

Storm-wave development of shore-normal grooves (gutters) on a steep sandstone beach face

Shore-normal grooves (gutters) cut into the seabed have been reported widely from the marine geological record. Grooves commonly are spaced regularly across plane, consolidated surfaces in the littoral and sub-littoral zones and may be deeply incised. Despite their common occurrence in the rock record, there are few detailed descriptions of examples from modern environments. Previously reported examples have been ascribed to erosion by wave-induced currents, especially storm-driven near-shore flows. In particular, examples from beach faces have been related to either wave swash or backwash. However, no conceptual model exists to explain the presence of grooves, their morphology or their spacing alongshore.Herein, quasi-regularly spaced grooves on a soft sandstone beach face are described and interpreted to have formed due to wave breaking and swash zone processes consequent upon exceptional storms at sea. The groove morphologies are quantified using terrestrial laser scanning. Numerical modelling of the translation from offshore waves to nearshore breaking waves provides estimates of the swash zone parameters. A consideration of swash zone processes provides an explanation for formation of the grooves. In particular, the swash zone shear stress distribution and consequent bed erosion is a dome-shaped function of distance across the beach face, and this controls the cross-shore variability in groove depths. High-speed sheet flows, such as swash and backwash, develop periodic, shore normal, high and low speed streaks alongshore. Consequent streaky erosion produces the quasi-regular alongshore groove spacings. However, on any given beach face the specific spacing of grooves is likely a property, not only of the local sheet flow attributes, but also of larger-scale morphological forcing. This outcome suggests that spacing is an emergent property of the coupled sheet flow and larger-scale forcing, and thus specific spacings on any beach face remain unpredictable.