Coastal Dynamics of the Danube Delta

Large parts of the Danube Delta coast suffered severe erosion during last decades due to both natural trends and human interventions. To investigate and quantify the processes controlling the Danube Delta coast evolution a systematic approach was employed. First, a hindcast of the wave climate was simulated using the numerical model SWAN and wind data recorded locally during 11 consecutive years. Second, the sediment transport was calculated using the simulated wave climate, field data and an one line numerical model (UNIBEST CL+). A sediment budget and predictions for the future evolution of the study zone were derived further on. Third, the process based numerical model Delft-3D was used to investigate the episodic water level changes which produce locally large shoreline retreats. Fourth, an ideal spit was design and modelled with Delft-3D to understand the relationship between the two sediment transport components: cross and along shore. The results, along with historical data, were used to study the dynamics of the Sahalin spit, a particular geomorphologic feature formed at southernmost distributary mouth. Based on this particular case a conceptual model for formation and evolution of a spit at a river mouth was proposed. The thesis concludes with recommendations to mitigate the coastal erosion in a sustainable way by artificially supplying the retreating beach sectors.

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