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Recent developments in process-based coastal area models such as XBeach provide new opportunities to predict coastal responses to primary forcing mechanisms such as storm hydrodynamic by using 2DH grids. However, due to the lack of measured data, there are few application scenarios of the models. Therefore, more measurement and research are needed. In this paper, the Typhoon Lekima that hitting Zhejiang Province during neap tide period was selected to simulate morphodynamic responses of the Huangcheng Beach by assuming encountering with different tide types. Cross shore measurements with eight cross-shore profiles (named S1 ~ S8 from north to south) of the Huangcheng Beach pre- and post- the Typhoon Lekima respectively were presented. Then a 2DH storm surge and wave coupled model was established with Delft3D Flow/Wave. The model was well calibrated with measured water levels and wave data and provided hydrodynamic boundary conditions of different typhoon and tide types coupling situations for a refined model. The refined model was built using XBeach and simulated the morphological responses of the Huangcheng beach with well verifications. On basis of the numerical results, bed level changes at the eight profiles were analyzed, and the character of erosion and deposition under different tide conditions were illustrated. The net sand volume changes were got smaller under the spring tide condition rather than middle tide and neap tide conditions. Further study of the distribution of wave induced current at different stages of collision, inundation and ebb shown that the stronger current under spring tide condition would increase the sediment transport rate and reduce the deposition volume at profiles S3 and S6 ~ S8, and the total amount of sediment involved in transportation had increased for the whole beach, leading to the reduction of net erosion volume at profiles S1, S2, S4 and S5. [ABSTRACT FROM AUTHOR]

Identifying coastal stretches that are likely to erode under high wave conditions is essential to the coastal management community in addressing beach erosion-related issues. The manuscript presents a case study to predict erosion of a selected beach located on the eastern Indian coast during the 2018 southwest (SW) monsoon season. The pre-monsoon beach topography surveyed using DGPS is used as the initial topographic condition in the morphological model. The model simulates subsequent beach erosion during the SW monsoon season, which is forced by forecast waves. Beach erosion advisories that classify the beach as eroding, accreting and no change are disseminated with a lead period of 10 days. During the SW monsoon period, we have monitored the beach using the dumpy level, and the beach topography during the post-monsoon is generated using DGPS surveyed profiles and are used for model validation. The beach area under erosion observed from the model result is homologous with the in-situ observations. The model shows cross-shore sediment transport to dominate during the SW monsoon, particularly in the central and northern sectors of RK beach. The model estimated shoreline position agrees with the DGPS observations, where the central sector has undergone maximum erosion. The comparison shows the model's ability to simulate beach morphodynamics like landward shifting of the berm crest under a high wave setup and oscillating water levels due to tides. The study highlights the importance of numerical modelling systems that decipher the beach response to the high monsoon waves. Research highlights: Beach erosion forecast system for RK Beach, India. Forecast system is developed using a combination of WAVEWATCHIII and Xbeach. Beach erosion advisories during monsoon period. [ABSTRACT FROM AUTHOR]

To evaluate the annual sediment dispersal pattern, a year-long beach profile monitoring and granulometric analysis were adopted along the Kundapura estuarine beaches of coastal Karnataka. The river mouth is bounded by breakwaters and the coast is armoured by seawalls and groins. Beaches adjacent to the breakwater showed progradation as a result of the shadow zone created due to the sheltering effect from incident waves. Evidence also comes from the replacement of coarser mode sediments by finer. Those away from the shadow zone, however, experienced extensive erosion. They are subjected to along-shore drift and minimal replacement from the same. It was also observed that despite being tropical estuarine beaches, sediments did not show any affinity towards a fluvial-derived character. These points towards transport of fine sediments further offshore and retention of coarser fraction in the surf zone that is to be carried shoreward. Breakwaters in turn facilitate this by channelising the river discharge farther in the sea. Evidence towards the same is also provided by the well-sorted to moderately well-sorted nature of the sediments. Breakwaters were thus observed to highly influence the sediment dispersion and distribution along an estuarine coast. This study will provide knowledge on the role of coastal structures in sediment dispersion while framing future coastal protection strategies for the conservation of the coast. Research highlights: Progradation of beaches adjacent to the breakwaters due to sheltering from direct waves whereas erosion of beaches away from the influence of these structures is observed. Extensive engineered coast has resulted in the narrowing of the natural beach width making it reflective with a high-energy environment thus accelerating further erosion. Due to this, the beach has lost its recreational value. The along-shore drift directions derived considering beach morphology, beach volume change and beach sedimentology, along with the mode of transport and environmental affinity of sediments provide a comprehensive understanding of sediment dispersal pattern along the coast. [ABSTRACT FROM AUTHOR]

In this paper, a two-phase coastal liquid-sediment system and a wave breaker were numerically simulated using a particle-based smooth particle hydrodynamics (SPH). To verify the accuracy of SPH numerical scheme and model, a simplified liquid-sediment test case was constructed for validation using particle image velocimetry (PIV) experiment. Quantitatively, the discrepancies of the probed velocities are less than 9.32%. Moreover, both the sediment and flow profiles obtained numerically and experimentally are qualitatively comparable. Through SPH simulation, the exact mechanism of beach profile erosion was visualized. Thus, the veracity of the developed SPH numerical model was affirmed and justified. Using similar numerical approach, the variation effects of wave frequency on the characteristics of breaking wave were investigated. Five liquid-sediment cases of sinusoidal waves of varying frequencies from 0.2 to 1.0 Hz were studied. The characteristics of breaking waves were determined as surging or collapsing, plunging and spilling in the ascending order of wave frequency. Subsequently, the correlation between Iribarren number and Froude number was analyzed to observe the effect of wave breaker types on the beach erosion profile. Furthermore, two statistically correlated equations were formulated to relate wave frequency to Iribarren number and wave height. Finally, generalized plot of Iribarren number against Froude number was developed to determine the characteristics of the breaker wave at different slope angles. Overall, the presented SPH numerical scheme was found viable in simulating coastal problems, for instance, sediment transport and breaking wave impact on erosion. [ABSTRACT FROM AUTHOR]

The mutual feedback between the swash zone and the surf zone is known to affect large-scale morphodynamic processes such as breaker bar migration on sandy beaches. To fully resolve this feedback in a process-based manner, the morphodynamics in the swash zone and due to swash-swash interactions must be explicitly solved, e.g., by means of a wave-resolving numerical model. Currently, few existing models are able to fully resolve the complex morphodynamics in the swash zone, and none is practically applicable for engineering purposes. This work aims at improving the numerical modelling of the intra-wave sediment transport on sandy beaches in an open-source wave-resolving hydro-morphodynamic framework (e.g., non-hydrostatic XBeach). A transport equation for the intra-wave suspended sediment concentration, including an erosion and a deposition rate, is newly implemented in the model. Two laboratory experiments involving isolated waves and wave trains are simulated to analyse the performance of the model. Numerical results show overall better performance in simulating single waves rather than wave trains. For the latter, the modelling of the morphodynamic response improves in the swash zone compared with the existing sediment transport modelling approach within non-hydrostatic XBeach, while the need of including additional physical processes to better capture sediment transport and bed evolution in the surf zone is highlighted in the paper. [ABSTRACT FROM AUTHOR]

A model is developed to simulate the morphodynamics of a barred shore profile on the scale of a storm cycle, comprising the phases of high and low wave activity. In the CROSS-PB model, the main mechanisms governing sediment transport in wave shoaling and surf zones are taken into consideration, in particular, skewness and asymmetry of the wave orbital velocities, undertow, and infragravity oscillations associated with wave groups. By comparing calculations with observed data, it is concluded that the model correctly reproduces seaward displacement of bars during a storm and shoreward under moderate or weak wave conditions. The first process is shown to be provided by balance of transport mechanisms when the peak offshore transport is located at the front slope of bar. The second process is conditioned by dominant shoreward transport and its sharp decay over the bar crest. Testing of the model yields estimates for the calibration coefficients, and it is concluded that shoreward sediment flux is mainly controlled by wave asymmetry. [ABSTRACT FROM AUTHOR]

Variations in shoreline trend was examined for 21 stations between Manuvai (in the west) and Vijayapathi (in the east), along the southern tip of India. Multispectral satellite data of Landsat MSS (9th Feb, 1973), Landsat TM 5 (4th Sep 2001) and Landsat ETM+ (21st Jan 2006) were used to assess the temporal dynamics of shoreline trend present in the region. The images were pretreated by radiometric calibration in order to avoid the temporal deviation of spatial and spectral information. The exact shorelines were estimated by two steps of image processing techniques: Normalized Difference Water Index (NDWI) is used to classify the land and sea water by and Sobal edge detection techniques are used to extract boundary line between land and water body. The rate of changes between the period 1973 and 2006 has shown that, the average shoreline rate is accelerated in the study area at 1.78 m/year. However, unusual shoreline changes ranging from 3.60 m/year to 15.60 m/year has been observed between the period 2001 and 2006 due to the impact of Tsunami. The station-wise shoreline data endorsed that Chinna muttom to Visvanarayanapuram and Lipuram are under continuous depositional process whereas other stations are under erosional process. This result shows that littoral sediment movement, with respect to the wave climate and anthropogenic activities are the predominant factors that affect the shoreline trend and sediment drift prevailing in the coast. [ABSTRACT FROM AUTHOR]

Coastal roads are lifelines for bringing emergency personnel and equipment into affected areas after tsunamis, thus careful thought should be given to how to make roadways safer from tsunamis. Scouring at roadways is the primary damage caused by tsunamis; however, tsunami-induced scouring and beach erosion are less understood compared to tsunami runup and tsunami inundation. A set of laboratory experiments are reported in this study on tsunami-induced scour at a road model situated on a sandy beach. Our experiments showed that the distance between the shoreline and a roadway, which varies with tides, was a key factor affecting the scour depth at the road. Having the coastal road at about half of the inundation distance is not the most ideal location. The depth of road embedment did not affect the scour depth in our experiments. It was also found that for typical tsunamis, the scour depth is unlikely to reach its equilibrium stage. The information reported in this study is useful for local authorities to assess potential tsunami damage of roads and to have a better plan for tsunami disaster relief. [ABSTRACT FROM AUTHOR]

The study aims to calibrate/validate and apply the dune-erosion model, XBeach, in order to predict morphological response to storm events along a meso-tidal, steeply sloping beach. More than 10,000 XBeach calibration runs, including different model parameters and erosion events, were compared with measurements of beach-profile response to storm conditions. Off-shore wave and tidal measurements were used as input for a SWAN wave model, which was used to provide wave conditions to XBeach. The results indicate that using XBeach to predict beach-profile morphodynamic response during storm events on steeply sloping intermediate-to- reflective beaches may be more demanding than for dissipative beaches and that the default model setup can overestimate dune/beach-face erosion. The performance of the model after calibration was satisfactory, with Brier Skill Scores from 0.2 to 0.72. XBeach was found to be more sensitive to input parameters such as the beach-face slope and the surf similarity parameter ξ (especially for values ξ > 0.6). The calibrated XBeach setup was used for simulations of storm scenarios with different return periods (5, 25, and 50 years), and the simulations highlighted the fragility of the dune field and the potential for storm-induced dune retreat, lowering, and overwash in the study area. Finally, the nested SWAN/XBeach models were forced by an existing operational wave-forecast WAVEWATCH-III/SWAN model, operated by the Portuguese Hydrographic Institute to generate daily forecasts of storm impact and serve as a prototype-case for an early warning system for storm hazard mitigation. [ABSTRACT FROM AUTHOR]

This work presents the results of a beach-monitoring program carried out in the Bay of Cadiz (SW Spain), which consists of urban, natural and nourished beaches. In the present study, 24 topographic profiles have been monthly monitored during the 1996–1998 period, in order to draw the morphodynamic behavior of this coast and the general characterization of short-term coastal trends. This way, total volumetric budgets have been calculated for each beach profile in order to group beaches in different erosive/accreting sectors. Studied beaches recorded both erosion and accretion: the greatest accretionary trends have been observed at Aguadulce, La Costilla and Rota beaches, with values ranging from 30 to 70 m3/m. The largest erosion episodes have been recorded in the southernmost end of Valdelagrana spit, with values over 50 m3/m, and in Rota and Vistahermosa, after nourishment works. Main erosion and accretion pathways have been related to the existence of natural and human structures, which blocked the longshore drift suggesting the existence of littoral cells. [ABSTRACT FROM AUTHOR]