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The main objective of the present paper is to achieve the simulation of the long-term (e.g., annual) morphological evolution (bathymetry and shoreline) of a coastal area (Mastichari beach, Greece) due to wind-generated waves in an accurate and cost-effective way. For this purpose, wave climate schematization techniques are adopted in order to reduce the computational effort without losing or distorting the crucial information. Referring to the current practice, the wave chronology is not considered in detail in these acceleration techniques, and therefore, sea bottom and shoreline evolution are not estimated as a function of time. To fill this gap, a novel and easy-to-use chronology-based wave input reduction method is developed to produce representative wave time series of different intensities and durations. The performance of all the applied techniques in the present study is evaluated, and a comparative analysis is conducted. It is shown that the new chronology-based wave input reduction method can achieve a model run-time reduction of about 70%, while at the same time, it provides satisfactorily accurate results. In general, this research could be useful for coastal engineering studies and coastal zone monitoring, and thus, it would be a valuable tool for coastal engineers and marine scientists. [ABSTRACT FROM AUTHOR]

Abstract: A morphodynamic model previously developed to predict the evolution of sedimentary coasts is extended to compare the effects of abrasion and thermal-abrasion processes on Arctic coasts. It is concluded that under the same storm impact, an unfrozen abrasion cliff loses almost the same sediment volume and retreats at almost the same rate as a thermal-abrasion cliff of corresponding effective height. Thermal impact itself presumably does not contribute to the volume of sediment losses significantly and only prepares the frozen material to be removed by waves and currents. Whatever the potential of thermal-abrasion determined by thermal effects, the volume of lost material would be limited mostly by the potential transport capacity of storm wave activity, as in the case of a pure abrasion. The long-term losses of sediments for both types of coast can be determined using an empirical relationship incorporating the effective height of the cliff, hce, taking into account the subsidence of soil after thawing of ice. The proposed model is employed to predict the evolution of thermal-abrasion and accretionary coasts in the central and eastern Russian Arctic where the sea-ice conditions at present are more severe. The recession of the thermal abrasion cliffs is expected to accelerate by 1.4 to 1.5 times in the second half of the 21st century. Evolution of the accretionary coasts may lead to development of natural berms protecting the coast from erosion. [Copyright &y& Elsevier]

Morphodynamic modeling is employed in the present work to predict the long-term evolution (over the next 100 years) of typical sedimentary coasts in the western Russian Arctic. The studied objects are the coasts of Varandey (the Barents Sea), Baydaratskaya Bay and Harasavey (the Kara Sea). The model developed takes into account both the short-term processes (storm events) and long-term factors (for example, changes in sea level, inter-annual variations in gross sediment flux, lack or excess of sediment supply). Predicted and observed morphological changes in coastal profiles are shown to agree well for time scales ranging from weeks to decades. It is revealed that under given environmental conditions, the morphological evolution is strongly influenced by storm surges and associated wind-driven circulation. The water level gradient created by a surge generates a seaward flow at the bed. This outflow is shown to be an important destructive mechanism contributing to the erosion and recession of Arctic coasts. The rate of change is found to depend on both the exposure of the coast (relative to the direction of dominant winds) and its height above the sea. The open coast of Varandey is expected to retreat as much as 300–500 m over 100 years, while recession of the less exposed coasts of Baydaratskaya Bay would not exceed about 100 m/century. If long-term sediment losses are insignificant, the rate of erosion decays with time and the morphodynamic system may tend toward equilibrium. It is concluded that the expected relative sea-level rise (up to 1 m over the nearest 100 years) is non-crucial to the future coastal evolution if an erosion activity is already high enough. [Copyright &y& Elsevier]

This paper presents how major French science-oriented public institutions and Ministry of Higher Education, Research, and Innovation (MESRI) have developed and structured coastal observatories along metropolitan and oversea coastlines in order to better understand the metropolitan and oversea French coastal evolution on a wide range of temporal and spatial scales. Scientific results presented in this special Issue have been obtained in the framework of the resulting DYNALIT / ILICO observatory network. [ABSTRACT FROM AUTHOR]

The damming of the estuaries Brielse Maas, Haringvliet and Grevelingen in the SW Netherlands, distributaries of the rivers Rhine and Meuse, caused large-scale morphodynamic changes in their respective ebb-tidal deltas that continue until today. The strong reduction of the cross-shore tidal flow triggered erosion of the ebb-delta front, the building of a coast-parallel, linear intertidal sand bar at the seaward edge of the delta platform, levelling of bars and infilling of the tidal channels. The stepwise extension of the port of Rotterdam north of the Haringvliet ebb-tidal delta increasingly sheltered this area from the impact of waves and caused a large supply of sand. This finally led to breaching and erosion of the shore-parallel bar. Moreover, large-scale sedimentation reduced the average depth in this area. The Grevelingen ebb-tidal delta has a more exposed position and a smaller sediment supply and has not reached the stage of bar breaching yet. The observed development of the ebb-tidal deltas caused by blocking of the tidal flow in the associated estuary or tidal inlet is summarized in a three-stage conceptual model. This model can help to assess the impact of interventions in estuaries and tidal inlets, for instance to mitigate the impacts of sea-level rise. • Fife decades of data show changes in ebb-tidal deltas caused by damming of inlets. • The ebb-tidal deltas have been strongly reduced in extent and average water depth. • The observed morphodynamic evolution can be summarised in a conceptual model. • This model can assess impact of engineering, e.g. anticipating future sea-level rise. [ABSTRACT FROM AUTHOR]