The possibility that the periodic features observed in the nearshore region are the result of self-organisational processes is investigated in this work. The behaviour of two numerical models, based on different techniques, has been analysed in order to describe the formation of periodic features in the surf and swash zone respectively. The appearance of periodic patterns in the nearshore region has been traditionally linked to the presence of standing edge waves with the topographic changes passively driven by the flow patterns. A more recent approach indicates the possibility that periodic patterns appear because of feedback processes between beach morphology and flow. In the first model, the coupling between topographic irregularities and wave driven mean water motion in the surf zone is examined. This coupling occurs due to the fact that the topographic perturbations produce excess gradients in the wave radiation stress that cause a steady circulation. To investigate this mechanism, the linearised stability problem in the case of an originally plane sloping beach and normal wave incidence is solved. It is shown that the basic topography can be unstable with respect to two different modes: a giant cusp pattern with shore attached transverse bars that extend across the whole surf zone and a crescentic pattern with alternate shoals and pools at both sides of the breaking line showing a mirroring effect. For the swash zone, the formation of beach cusps has been investigated. The several theories proposed in the past have been analysed and all the field and laboratory measurements available in the literature collected in order to test such theories. It is suggested that, with the available measurements it is not possible to distinguish between the standing edge wave model and the self-organisation approach. A numerical model based on self-organisation has been here developed and tested in order to understand the processes occurring during beach cusp formation and development, to evaluate the sensitivity towards the parameters used and to look at how the model might relate to field observations. Results obtained confirm the validity of the self-organisation approach and its capacity to predict beach cusp spacing with values in fair agreement with the available field measurements and with most of the input parameters primarily affecting the rate of the process rather than the final spacing. However, changes in the random seed and runs for large numbers of swash cycles reveal a dynamical system with significant unpredictable behaviour. A qualitative comparison between the model results and field measurements collected by Masselink et al. (1997) during beach cusp formation and development has also been performed on the basis of a non-linear fractal technique. Results indicate beach locations and time-scales where non-linearities are more important and self-organisation can play a fundamental role.

Bathymetric features such as nearshore sandbars can alter local nearshore hydrodynamic processes such as the production of infragravity energy. These bathymetric features may act to reduce or increase the amount of infragravity energy that reaches the shoreline. To determine the influence of the bathymetric features on infragravity energy, the numerical nearshore processes model XBeach was used to simulate infragravity energy at the shoreline. Numerical simulations were completed for three types of bathymetric scenarios: continuous alongshore bar, bar-rip, and no-bar. The presence of the bar reduces the amount of infragravity energy at the shoreline when compared with the no-bar scenario. This reduction was characterized by modifying an empirical parameterization for significant infragravity swash developed by Stockdon et al. (2006) for barred beaches. Results show that the amount of infragravity energy in the form of swash is dependent on the bar height and depth, in addition to the offshore wave height and wavelength. The bar-rip bathymetry produces significant alongshore variation in infragravity energy. The alongshore variations may be due to refracted wave energy or the production of an edge wave by the rip. The magnitude of infragravity energy in the alongshore direction is found to be correlated with the surf zone width. Finally, erosion for the bar-rip scenario is studied qualitatively. The shape of the shoreline is modified during storm events, and is found to take the shape of the alongshore distribution of infragravity energy. Since infragravity swash influences beach erosion, results of this research may be used as part of an erosion vulnerability scale. Such information on erosion vulnerability is important for the design of coastal protection systems and the protection of coastal communities.

Coarse-grained beaches, such as pure gravel (PG), mixed sand-gravel (MSG) and composite (CSG) beaches, can be considered as one of the most resilient non-cohesive morpho-sedimentary coastal environments to energetic wave forcing (e.g., storms). The hydraulically-rough and permeable nature of gravel (D50 > 2 mm), together with the steep (reflective) beach face, provide efficient mechanisms of wave energy dissipation in the swash zone and provide a natural means of coastal defence. Despite their potential for shore protection very little is known about the response of these environments during high energetic wave conditions. Field measurements of sediment transport and hydrodynamics on coarse-grained beaches are difficult, because there are few instruments capable of taking direct measurements in an energetic swash zone in which large clasts are moving, and significant morphological changes occur within a short period of time. Remote sensing methods emerge in this context as the most appropriate solution for these types of field measurement. A new remote sensing method, based around a mid-range (~ 50 m) 2D laser-scanner was developed, which allows the collection of swash zone hydrodynamics (e.g., vertical and horizontal runup position, swash depth and velocity) and bed changes on wave-by-wave time scale. This instrument allowed the complete coverage of the swash zone on several coarse-grained beaches with a vertical accuracy of approximately 0.015 m and an average horizontal resolution of 0.07 m. The measurements performed with this new methodology are within the accuracy of traditional field techniques (e.g. video cameras, ultrasonic bed-level sensors or dGPS). Seven field experiments were performed between March 2012 and January 2014 on six different coarse-grained beaches (Loe Bar, Chesil, Slapton, Hayling Island, Westward Ho! and Seascale), with each deployment comprising the 2D laser-scanner together with complementary in-situ instrumentation (e.g., pressure transducer, ADV current meter). These datasets were used to explore the hydrodynamics and morphological response of the swash zone of these different environments under different energetic hydrodynamic regimes, ranging from positive, to zero, to negative freeboard regimes. With reference to the swash zone dynamics under storms with positive freeboard regimes (when runup was confined to the foreshore) it was found that extreme runup has an inverse relationship with the surf scaling parameter (=2Hs /gTptan2). The highest vertical runup excursions were found on the steepest beaches (PG beaches) and under long-period swell, while lower vertical runup excursions where linked to short-period waves and beaches with intermediate and dissipative surf zones, thus demonstrating that the contrasting degree of wave dissipation observed in the different types of surf zones is a key factor that control the extreme runup on coarse-grained beaches. Contrasting morphological responses were observed on the different coarse-grained beaches as a result of the distinct swash\surf zone hydrodynamics. PG beaches with narrow surf zone presented an asymmetric morphological response during the tide cycle (accretion during the rising and erosion during the falling tide) as a result of beach step adjustments to the prevailing hydrodynamics. On dissipative MSG and CSG beaches the morphological response was limited due to the very dissipative surf zone, while on an intermediate CSG beach significant erosion of the beach face and berm was observed during the entire tide cycle as a result of the absence of moderate surf zone wave dissipation and beach step dynamics. Fundamental processes related to the link between the beach step dynamics and the asymmetrical morphological response during the tidal cycle were for the first time measured under energetic wave conditions. During the rising tide the onshore shift of the breaking point triggers the onshore translation of the step and favors accretion (step deposit development), while during the falling tide the offshore translation of the wave breaking point triggers retreat of the step and favours backwash sediment transport (erosion of the step deposit). Under zero and negative freeboard storm regimes (when runup exceeds the crest of the barrier or foredune), field measurements complimented by numerical modelling (Xbeach-G) provide clear evidence that the presence of a bimodal wave spectrum enhances the vertical runup and can increase the likelihood of the occurrence of overtopping and overwash events over a gravel barrier. Most runup equations (e.g., Stockdon et al., 2006) used to predict the thresholds for storm impact regime (e.g., swash, overtopping and overwash) on barriers lack adequate characterisation of the full wave spectra; therefore, they may miss important aspects of the incident wave field, such as wave bimodality. XBeach-G allows a full characterization of the incident wave field and is capable of predicting the effect of wave spectra bimodality on the runup, thus demonstrating that is a more appropriate tool for predicting the storm impact regimes on gravel barriers. Regarding the definition of storm impact regimes on gravel barriers, it was found that wave period and wave spectra bimodality are key parameters that can affect significantly the definition of the thresholds for these different regimes. While short-period waves dissipate most of their energy before reaching the swash zone (due to breaking) and produce short runup excursions, long-period waves arrive at the swash zone with enhanced heights (due to shoaling) and break at the edge of the swash, thus promoting large runup excursions. When offshore wave spectrum presents a bimodal shape, the wave transformation on shallow waters favours the long period peak (even if the short-period peak is the most energetic offshore) and large runup excursions occur. XBeach-G simulations show that the morphological response of fine gravel barriers is distinct from coarse gravel barriers under similar overtopping conditions. While on coarser barriers overtopping regimes are expected to increase the crest elevation and narrow the barrier, on fine barriers sedimentation occurs on the back of the barrier and in the lower beach face. Such different sedimentation patterns are attributed to the different hydraulic conductivity of the different sediment sizes which control the amount of flow dissipation (due to infiltration) and, therefore, the capacity of the flow to transport sediment across and over the barrier crest. The present findings have significantly improved our conceptual understanding of the response of coarse-grained beaches during storms. A new field technique to measure swash dynamics in the field was developed during this thesis and has great potential to become widely used in a variety of coastal applications.

Ce travail de thèse s’inscrit dans le contexte général de l’étude de la dynamique de la frangelittorale. Le but de ce travail de thèse était l’étude des couplages entre les ondes de surface (vagues, ondeslongues dont les ondes infra-gravitaires), les variations du niveau marin et les courants ainsi que les variationsà haute-fréquence du niveau d’eau sur la plage et les déplacements de la nappe phréatique au sein de la plagesableuse. L’approche retenue est essentiellement expérimentale in-situ.La campagne de mesure ROUSTY201412 a permis de récolter un jeu de données hydro- morphodynamiquesconsidérable, qui viendra alimenter l’étude des plages sableuses dans de nombreux domaines. Elle permeten particulier de décrire l’ensemble d’une saison hivernale sur un même site soumis à une grande variété declimats de houles et de vents, ce qui en fait un jeu de données unique dans le contexte méditerranéen.Dans cette thèse nous nous intéressons à trois domaines d’étude : la dynamique de la surface libre avecl’analyse des relations existantes entre les différentes échelles (vagues, variations du niveau marin, ondeslongues, wave-setup, ...), la structure et l’évolution du courant ainsi que le lien avec la dynamique de surface,et la circulation souterraine dans la nappe de plage et en particulier sous la zone de swash. / This PhD work is part of the general context of littoral dynamic study. The purpose of this workwas to study couplings between surface waves (waves and long waves including infra-gravity waves), sea waterlevel variations and currents, as well as high-frequence water level variations on shoreline and groundwatermovements within sandy beaches. The approach is mostly experimental in-situ.The field campaign ROUSTY201412 allowed the collection of a substantial hydro- morphodynamic dataset,supplying sandy beaches studies in several fields. In particular, it will allow, on a same site, the descriptionof a full winter season under various waves and winds climates, making it a unique dataset in Mediterraneancontext.In this PhD, we are interested in three fields : free surface dynamics, including multi scale relations analysis(waves, water level variations, long waves, wave-setup, ...), currents structure and evolution linked withsurface dynamics, and groundwater circulation within the coastal aquifer and particularly under the swashzone.

L'objectif de ce mémoire est de comprendre le fonctionnement hydro-sédimentaire des embouchures tidales dominées par la marée et la construction d'une flèche sableuse à crochets perpendiculaires. Deux sites voisins ont été choisis : les embouchures de l'Orne et de la Dives sur la côte du Calvados (Normandie). L'utilisation de données d'agitation et topographiques, acquises selon plusieurs échelles spatio-temporelles, permet d'étudier la morphodynamique de ces deux embouchures.L'embouchure de l'Orne possède une évolution soumise à une forte pression anthropique causée par de nombreuses infrastructures portuaires. Elle est comparée à celle de l'embouchure de la Dives, où l'impact anthropique est plus limité. Il apparaît que ces deux embouchures partagent les mêmes mécanismes de transports sédimentaires, avec une composante transversale importante. Ce transport vers la côte est assuré par la migration de barres de swash sur les parties aval-dérive des deltas de jusant. Ces barres de swash possèdent des volumes et des vitesses de migration similaires, comprises entre 3.5 et 8.0 m/mois.Contrairement à la Dives, les côtes en amont et en aval-dérive de l'embouchure de l'Orne sont en accrétion. Si en amont, cette accrétion suit les nombreuses phases de construction du port de Caen-Ouistreham, en aval se développe depuis un peu plus d'un siècle une flèche sableuse à la morphologie atypique. En effet, cette flèche possède plusieurs crochons emboités, dont les extrémités - les crochets - sont perpendiculaires au corps à la flèche. Il est démontré que l'attachement des barres de swash à la côte est responsable de la formation d'un nouveau crochon. La diffraction des vagues au niveau de l'extrémité des barres de swash et des crochons, ainsi que les directions locales de l'agitation, expliquent la formation des crochets perpendiculaires à l'extrémité des crochons. / The aim of this thesis is to understand the mechanisms of sediment bypassing at tidal inlets in a macrotidal environment and the formation of a sandspit with perpendicular hooks. Two closed areas are studied, the Orne and Dives inlets on the coast of Normandy (France). Wave and topographic data, at several space-time scales, are used to study the inlet morphodynamics.The Orne inlet is affected by strong human impacts due to several port facilities whereas the Dives inlet knows a limited anthropogenic impact. The study of the two inlets allows to deduce the impact of the human activities in the sediment transport patterns. The Orne and Dives inlets share the same mechanisms of sediment transport. Both show a major cross-shore component of the transport, underlines by the swash bars migration over the ebb-tidal deltas. All swash bars have similar volumes and migration rates, between 3.5 and 8.0 m/month.The Orne inlet shows deposition on both sides. The accretion on the updrift coast follows the building stages of the harbour of Caen-Ouistreham. On the downdrift coast, the deposition creates the Merville spit, which has several interlocked ridges. A perpendicular hook is present on the distal part of each ridge. This work shows that the swash bar attachment at the shoreline shapes a new ridge. Wave diffraction around the distal part of the swash bars and ridges, and the local wave directions, explain the formation of perpendicular hooks.

Ce travail porte sur l’étude des processus hydrodynamiques consécutifs à l’interaction entre deux ressauts hydrauliques propagatifs, particulièrement lorsqu’elle intervient sur une plage faiblement inclinée, ou à proximité. L’étude est menée dans un dispositif expérimental original constitué d’un canal de faible longueur, fermé à ses extrémités, et par deux vannes séparant le canal en trois parties de longueurs variables, remplies à des niveaux différents, qui définissent deux réservoirs et une "zone de large". A l’autre extrémité du canal est disposé un plan incliné, imperméable, qui modélise la plage. Les ouvertures des vannes, rapides et décalées d’un intervalle de temps contrôlé (rupture de barrage), génèrent deux vagues successives qui interagissent avant ou sur la plage, ou après que l’une d’entre-elles se soit préalablement réfléchie dessus. Un dispositif de métrologie optique – "ombroscopie" – permet la mesure à haute fréquence de la position de l’interface libre au cours du temps. Lors de la caractérisation du dispositif expérimental, nous avons mis en évidence que la célérité du front consécutif à une rupture de barrage suit un modèle théorique basé sur une méthode des caractéristiques pour les équations de Saint-Venant, obtenues dans l’approximation d’eau peu profonde ("shallow water"), et proposé par Stoker (1957), malgré quelques effets qui perturbent cette dynamique comme la taille finie des réservoirs par exemple. Nous observons en particulier que cette célérité dépend principalement de la nonlinéarité et faiblement de la dispersion, en accord avec l’approximation d’eau peu profonde. Lors de la génération de deux ressauts hydrauliques successifs, nous proposons deux modélisations simples pour décrire la dynamique initiale du déplacement du deuxième front, avant qu’il n’interagisse avec le premier. Ces modèles simples encadrent la solution réelle, mais se heurtent également aux effets de taille finie des réservoirs. Les interactions des deux ressauts "similaires" sur la plage, ou à proximité, et la dynamique de la lame d’eau sur la plage, sont analysées en fonction du décalage temporel, et de l’angle de pente de la plage, en considérant la nature "fusion" ou "collision" de l’interaction. Pour un angle de plage donné, le "run-up "maximum est obtenu, dans notre étude, pour un déphasage entre les fronts qui entraîne une interaction de "fusion" au début de la plage. L’angle de plage optimum, dans ce cadre, semble correspondre à un type de plage intermédiaire entre une plage très réflective et uneplage dissipative / This study investigates the hydrodynamic processes resulting fromthe interaction between two bores, particularly when these happen on a beach with a gradual slope or nearby. The research was conducted with a new experimental device. The latter was designed with a short channel, closed at both ends, with two gates separating the channel in three parts of varying lengths and filled to different levels, defining respectively two reservoirs and a “nearshore zone”. At the other end of the channel lies an inclined, impermeable plane, which represents the beach. The rapid openings of the gates, with a controlled lag time, generate two successive waves that interact either before or on the beach, or after one of them swashes on the beach. A classical shadowgraphy method enables high frequency measurement of the free interface position over time. During the characterisation of the experimental device, we demonstrated that the velocity of the front originating from the dam break follows a theoretical model based on the characteristics evolution of the hyperbolic Saint-Venant equations obtained in the shallow water approximation, and proposed by Stoker (1957) fairly well. This occurs despite some effects that disrupt this dynamic, as for instance the finite size of the thanks. In particular, we observe that the front velocity depends mostly on non-linearity and not on dispersive effects, accordingly to shallow water approximation. During the generation of two successive bores, we propose two simple modelizations to describe the initial dynamics of the displacement of the second front, before it interacts with the first one. These simple models frame the actual solution, but also collide with the finite size effects of the reservoirs. The interactions of the two "similar" bores on the beach, or nearby, and the dynamics of the water lens swashing on the beach are analysed according to the time shift, and the angle of slope, considering the nature "fusion" or "collision" of the interaction. For a given beach angle, our study obtained the maximum run-up with a time shift that generates a merging of the fronts at the beginning of the shore. It appears that the optimum angle in this settingmatches that of a type of intermediate beach between a very reflective and a dissipativebeach

No description available.

Ce travail porte sur l’étude de l’évolution morphologique dans la zone de swash à haute résolution spatiale et temporelle afin de pouvoir analyser l’influence de la houle. Cette étude s’appuie sur deux campagnes de mesures menées dans le grand canal à houle CIEM (Barcelone), l’une avec application d’un forçage aléatoire érosif de type JONSWAP et l’autre avec application d’une série de forçages bichromatiques. L’originalité de l’étude proposée ici consiste en l’analyse, par une méthode de stéréoscopie optique, de l’évolution du fond avec une excellente précision tout en quantifiant précisément l’évolution des fronts d’eau sur une surface continue, la majorité des techniques de mesure ne donnant en général accès qu’à des relevés ponctuels dans cette zone. La position du lit de sable est estimée avec une précision de quelques centaines de μm. Sur des temps longs, le forçage JONSWAP érosif engendre un recul global et quasi-homogène dans la zone de swash. Cependant, cette évolution ne semble pas influencer la réponse hydrodynamique qui reste similaire dans la zone de swash lorsque l’on répète la série. Ceci a été confirmé dans le cas des forçages bichromatiques, répétés sur des fonds différents. Au sein d’une série d’un forçage aléatoire, différentes échelles de temps sont observées : l’échelle gravitaire (période caractéristique du signal) et les ondes infragravitaires (large gamme d’événements plus longs). Cette coexistence de plusieurs échelles de temps a pu être associée à la forte variabilité du profil de plage, notamment dans la direction cross-shore. Le cas bichromatique montre quant à lui une convergence du profil de plage vers un état qui ne dépendrait que du forçage en entrée. L’interaction d’une seule onde infragravitaire avec l’onde gravitaire ne peut donc pas être responsable de la variabilité du fond observée avec le forçage aléatoire. En revanche, cette étude semble confirmer la présence d’événements particuliers à l’origine d’une forte modification du fond sableux. Le lien entre ces événements et l’interaction entre des événements hydrodynamiques spécifiques et la forme du fond n’est pas encore complètement établi. Enfin, pour le forçage aléatoire la variabilité transverse induite par les ondes courtes est forte alors qu’elle semble plus faible à l’échelle de l’onde longue. Pour le forçage bichromatique, cette variabilité transverse a également pu être observée mais son lien avec le forçage reste encore à élucider. / This study investigates the morphological evolution in the swash zone at high spatial and temporal resolution to be able to analyze the swell influence. The study is here based on two measurement campaigns in the large CIEM wave flume (Barcelona), using both a random erosive JONSWAP and bichromatics forcing. The originality of the proposed study lies on analysis, by an optical stereoscopic method, of bottom evolution with a very good precision while getting an accurate quantification of water fronts evolution on a continuous area, most of the measurement techniques generally allowing only to obtain punctual measurements in this area. The sand bed position is estimated with an accuracy of a few hundred μm. Over long periods, erosive JONSWAP forcing generates an overall and almost homogeneous backward movement in the swash area. However, this trend does not appear to influence the hydrodynamics response that remains similar in the swash area when the series is repeated. This was confirmed in the bichromatic forcings case, repeated on different bottoms. During a random forcing series, different time scales are observed : the gravity scale (characteristic period of the signal) and infragravity waves (wide range of longer events). This coexistence of several time scales could be associated with the observation of a strong variability of the beach profile, especially in the cross-shore direction. The bichromatic case shows meanwhile convergence of beach profile to a state that would depend only on forcing conditions. The interaction of a single infragravity wave with the gravitational wave can therefore not be responsible for the observed bottom variability with the random forcing. In contrast, the present study seems to confirm the presence of specific events responsible of a strong change in the sandy bottom. The link between these events and the hydrodynamic interaction between specific events and the bottom shape is not yet completely established. Finally, for the random forcing the transverse variability induced by short wave is strong as it seems weak at long wave time scale. For bichromatic forcing, the transverse variability has also been observed but its link with the forcing still remains to be elucidated.

Due to many advantages, swash plate pumps are wide spread in hydraulic systems. The main advantages are the through drive capability, the adjustability and most of all, the high power density. Their application range is limited, historically, to 450bar including medium and higher volume sizes. In higher pressure range, constant pumps such as wobbling disks or radial piston pumps are normally used. This is because the higher stressed parts can be dimensioned much bigger. Pumps with lower power such as constant displacement gear pumps are generally used in low price applications. In order to enlarge the application range of swash plate pumps, their advantages have to be further improved and strengthened. This paper shows by example how the pressure of the basic series A4VSO was increased up to a nominal pressure of 630bar and the historical pressure mark of 450bar could be exceeded. This increase in pressure level enables for example steel treatment manufacturers to reduce their component sizes without the need of a pressure transducer. Furthermore the power density of the redesigned HA4VSO was increased by 36%, compared to the standard A4VSO, by significantly increasing the self-priming speed. On the other side of the application range, in lower power mobile applications such as small tractors, forklift and skid steer loader, there is an increasing demand for less exhaust emissions and better fuel economy. The energy saving potential by changing from a hydraulic system with constant hydraulic pumps to variable hydraulic pumps is already proven on high power applications. By developing the variable axial piston pump A1VO to the requirements of lower horse power application, it is now also possible to realize such savings in lower horse power applications. Furthermore efficiency of the pump itself can be improved. An example of this is shown by way of the new A4 series 33.

This thesis examines the processes of longshore sediment transport in the swash zone of a mixed sand and gravel shoreline, Lake Coleridge, New Zealand. It focuses on the interactions between waves and currents in the swash zone and the resulting sediment transport. No previous study has attempted to concurrently measure wave and current data and longshore sediment transport rates on a mixed sand and gravel lakeshore beach in New Zealand. Many of these beaches, in both the oceanic and lacustrine environments, are in net long-term erosion. It is recognised that longshore sediment transport is a part of this process, but very little knowledge has existed regarding rates of sediment movement and the relationships between waves, currents and swash activity in the foreshore of these beach types. A field programme was designed to measure a comprehensive range of wind, wave, current and morphological variables concurrently with longshore transport. Four electronic instruments were used to measure both waves and currents simultaneously in the offshore, nearshore and swash zone. In the offshore area, an InterOcean S4ADW wave and current meter was installed to record wave height, period, direction and velocity. A WG-30 capacitance wave gauge measured the total water surface variation. A pair of Marsh-McBirney electromagnetic current meters, measuring current directions and velocities were installed in the nearshore and swash zone. Data were sampled for 18 minutes every hour with a Campbell Scientific CR23x data-logger. The wave gauge data was sampled at a rate of 10 Hz (0.1 s) and the two current meters at a rate of 2 Hz (0.5 s). Longshore sediment transport rates were investigated with the use of two traps placed in the nearshore and swash zone to collect sediment transported under wave and swash action. This occurred concurrently with the wave measurements and together yielded over 500 individual hours of high quality time series data. Important new insights were made into lake wave processes in New Zealand's alpine lakes. Measured wave heights averaged 0.20-0.35 m and ranged up to 0.85 m. Wave height was found to be strongly linked to the wind and grew rapidly to increasing wind strength in an exponential fashion. Wave period responded more slowly and required time and distance for the wave length to develop. Overall, there was a narrow band of wave periods with means ranging from 1.43 to 2.33 s. The wave spectrum was found to be more mixed and complicated than had previously been assumed for lake environments. Spectral band width parameters were large, with 95% of the values between 0.75 and 0.90. The wave regime attained the characteristics of a storm wave spectrum. The waves were characteristically steep and capable of obtaining far greater steepness than oceanic wind-waves. Values ranged from 0.010 to 0.074, with an average of 0.051. Waves were able to progress very close to shore without modification and broke in water less than 0.5 m deep. Wave refraction from deep to shallow water only caused wave angles to be altered in the order of 10%. The two main breaker types were spilling and plunging. However, rapid increases in beach slope near the shoreline often caused the waves to plunge immediately landward of the swash zone, leading to a greater proportion of plunging waves. Wave energy attenuation was found to be severe. Measured velocities were some 10 times less at two thirds the water depth beneath the wave. Mean orbital velocities were 0.30 m s⁻¹ in deep water and 0.15 m s⁻¹ in shallow water. The ratio difference between the measured deep water orbital velocities and the nearshore orbital velocities was just under one half (us/uo = 0.58), almost identical to the predicted phase velocity difference by Linear wave theory. In general Linear wave theory was found to provide good approximations of the wave conditions in a small lake environment. The swash zone is an important area of wave dissipation and it defines the limits of sediment transport. The width of the swash zone was found to be controlled by the wave height, which in turn determined the quantity of sediment transported through the swash zone. It ranged in width from 0.05 m to 6.0 m and widened landward in response to increased wave height and lakeward in response the wave length. Slope was found to be an important secondary control on swash zone width. In low energy conditions, swash zone slopes were typically steep. At the onset of wave activity the swash zone becomes scoured by swash activity and the beach slope grades down. An equation was developed, using the wave height and beach slope that provides close estimates of the swash zone width under a wide range of conditions. Run-up heights were calculated using the swash zone width and slope angle. Run-up elevations ranged from 0.01 m to 0.73 m and were strongly related to the wave height and the beach slope. On average, run-up exceeds the deep water wave height by a factor of 1.16H. The highest run-up elevations were found to occur at intermediate slope angles of between 6-8°. Above 8°, the run-up declined in response to beach porosity and lower wave energy conditions. A generalised run-up equation for lake environments has been developed, that takes into account the negative relationship between beach slope and run-up. Swash velocities averaged 0.30 m s⁻¹ but maximum velocities averaged 0.98 m s⁻¹. After wave breaking, swash velocities quickly reduced through dissipation by approximately one half. Swash velocity was strongly linked to wave height and beach slope. Maximum velocities occurred at beach slopes of 5°, where incident swash dominated. At slopes between 6° and 10°, swash velocities were hindered by turbulence, but the relative differences between the swash and backswash flows were negligible. At slope angles above 10° there was a slight asymmetry to the swash/backswash flow velocities due to beach porosity absorbing water at the limits of the swash zone. Three equations were developed for estimating the mean and maximum swash velocity flows. From an analysis of these interactions, a process-response model was developed that formalises the morphodynamic response of the swash zone to wave activity. Longshore sediment transport occurred exclusively in the swash zone, landward of the breaking wave in bedload. The sediments collected in transit were a heterogeneous mix of coarse sands and fine-large gravels. Hourly trapped rates ranged from 0.02 to 214.88 kg hr⁻¹. Numerical methods were developed to convert trapped mass rates in to volumetric rates that use the density and porosity of the sediment. A sediment transport flux curve was developed from measuring the distribution of longshore sediment transport across the swash zone. Using numerical integration, the area under this curve was calculated and an equation written to accurately estimate the total integrated transport rates in the swash zone. The total transport rates ranged from a minimum of 1.10 x 10-5 m³ hr⁻¹ to a maximum of 1.15 m³ hr⁻¹. The mean rate was 7.36 x 10⁻² m³ hr⁻¹. Sediment transport was found to be most strongly controlled by the wave height, period, wave steepness and mean swash velocity. Transport is initiated when waves break at an oblique angle to the shoreline. No relationships could be found between the grain size and transport rates. Instead, the critical threshold velocities of the sediment sizes were almost always exceed in the turbulent conditions under the breaking wave. The highest transport rates were associated with the lowest beach slopes. It was found that this was linked to swash high velocities and wave heights associated with foreshore scouring. An expression was developed to estimate the longshore sediment transport, termed the LEXSED formula, that divides the cube of the wave height and the wave length and multiplies this by the mean swash velocity and the wave approach angle. The expression performs well across a wide range of conditions and the estimates show very good correlations to the empirical data. LEXSED was used to calculate an accurate annual sediment transport budget for the fieldsite beaches. LEXSED was compared to 16 other longshore sediment transport formulas and performed best overall. The underlying principles of the model make its application to other mixed sand and gravel beaches promising.