The coastal environment is the most densely populated location on the planet, as well as one of the most complex because of the presence of both marine and terrestrial forcings. In particular, the small-scale landforms are usually rapidly changing as a result of the modification of the forcings such as waves, tides, the sea level rise (SLR), fluvial solid discharge and anthropic activities. An analysis of the geomorphological aspects, sediment budgets, and their evolution over time is a basic requirement for coastal management. In this work, we analysed a nearshore depositional system made up of active and relict sand banks characterized by the presence of a fluvial sediment source, a wave bimodality made up of long southern and short north-eastern waves, and divergent landforms, intrinsically related to the delicate balance of hydrodynamic conditions and grain-size characteristics of the sediments. The objective of the PhD project is to clarify the complex morphodynamics of this area combining data of different source, such as bathymetric, aerial photogrammetric and sediment data, in a multidisciplinary approach in order to furnish a basis for future accurate planning and re-evaluation of coastal management choices to balance environmental protection and tourist use. By combining all the data together, processed both with standard methodologies and with algorithms developed during the PhD, it was possible to derive the complex evolutionary pattern of the area, in which the subcoastal dynamics linked to the transport of sediments along the longshore transport pathway in a westward direction combines with the deep dynamics linked to the relict sedimentary body, made up of landforms with opposite vergence compared to the littoral drift. In this context, the bimodality of waves has proven to be the most important morphodynamic agent although the presence of the sedimentary source is of fundamental importance for the constant recharge of sediments and the evolution of ongoing processes.
L’ambiente costiero è il luogo più densamente popolato del pianeta, nonché uno dei più complessi a causa della presenza di forzanti sia marine che terrestri. In particolare, le morfologie a piccola scala stanno solitamente cambiando rapidamente a seguito della modificazione delle forzanti quali le onde, le maree, l'innalzamento del livello del mare (SLR), la portata solida fluviale e le attività antropiche. L'analisi degli aspetti geomorfologici, dei bilanci sedimentari e della loro evoluzione nel tempo è un requisito fondamentale per la gestione costiera. In questo lavoro, abbiamo analizzato un sistema deposizionale sottocostiero costituito da banchi sabbiosi attivi e relitti caratterizzati dalla presenza di una sorgente sedimentaria fluviale, da una bimodalità del moto ondoso composta da onde lunghe meridionali e onde corte nord-orientali, e morfologie divergenti, intrinsecamente correlate a il delicato equilibrio tra condizioni idrodinamiche e caratteristiche granulometriche dei sedimenti. L'obiettivo del progetto di dottorato è chiarire la complessa morfodinamica di quest'area combinando dati provenienti da diverse fonti, come dati batimetrici, aerofotogrammetrici e sedimentari, in un approccio multidisciplinare al fine di fornire una base per una futura pianificazione e rivalutazione accurata delle scelte di gestione costiera per bilanciare tutela ambientale e fruizione turistica. Combinando insieme tutti i dati, elaborati sia con metodologie standard che con algoritmi sviluppati nel corso del dottorato, è stato possibile ricavare il complesso modello evolutivo dell'area, in cui le dinamiche sottocostiere legate al trasporto di sedimenti lungo il corridoio di trasporto longshore in direzione ovest si coniuga con le dinamiche profonde legate al corpo sedimentario relitto, costituito da morfologie a vergenza opposta rispetto alla deriva litoranea. In questo contesto la bimodalità del moto ondoso si è rivelata l'agente morfodinamico più importante sebbene la presenza della sorgente sedimentaria sia di fondamentale importanza per la costante ricarica dei sedimenti e l'evoluzione dei processi in corso.
ANALISI DI UN'ANOMALIA MORFODINAMICA LEGATA A SISTEMI DI FORME DI FONDO DIVERGENTI: IL BANCO SABBIOSO SOTTOCOSTIERO DELLA MULA DI MUGGIA, MAR ADRIATICO SETTENTRIONALE, ITALIA
FRACAROS, SAVERIO
2024
Abstract
The coastal environment is the most densely populated location on the planet, as well as one of the most complex because of the presence of both marine and terrestrial forcings. In particular, the small-scale landforms are usually rapidly changing as a result of the modification of the forcings such as waves, tides, the sea level rise (SLR), fluvial solid discharge and anthropic activities. An analysis of the geomorphological aspects, sediment budgets, and their evolution over time is a basic requirement for coastal management. In this work, we analysed a nearshore depositional system made up of active and relict sand banks characterized by the presence of a fluvial sediment source, a wave bimodality made up of long southern and short north-eastern waves, and divergent landforms, intrinsically related to the delicate balance of hydrodynamic conditions and grain-size characteristics of the sediments. The objective of the PhD project is to clarify the complex morphodynamics of this area combining data of different source, such as bathymetric, aerial photogrammetric and sediment data, in a multidisciplinary approach in order to furnish a basis for future accurate planning and re-evaluation of coastal management choices to balance environmental protection and tourist use. By combining all the data together, processed both with standard methodologies and with algorithms developed during the PhD, it was possible to derive the complex evolutionary pattern of the area, in which the subcoastal dynamics linked to the transport of sediments along the longshore transport pathway in a westward direction combines with the deep dynamics linked to the relict sedimentary body, made up of landforms with opposite vergence compared to the littoral drift. In this context, the bimodality of waves has proven to be the most important morphodynamic agent although the presence of the sedimentary source is of fundamental importance for the constant recharge of sediments and the evolution of ongoing processes.File | Dimensione | Formato | |
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https://hdl.handle.net/20.500.14242/164563
URN:NBN:IT:UNITS-164563