Evolution Of Coastal Environments Research Articles

Evolution of Coastal Environments under Inundation Scenarios Using an Oceanographic Model and Remote Sensing Data

A new methodology to map Italian coastal areas at risk of flooding is presented. This approach relies on detailed projections of the future sea level from a high-resolution, three-dimensional model of the Mediterranean Sea circulation, on the best available digital terrain model of the Italian coasts, and on the most advanced satellite-derived data of ground motion, provided by the European Ground Motion Service of Copernicus. To obtain a reliable understanding of coastal evolution, future sea level projections and estimates of the future vertical ground motion based on the currently available data were combined and spread over the digital terrain model, using a GIS-based approach specifically developed for this work. The coastal plains of Piombino-Follonica and Marina di Campo (Tuscany Region), Alghero-Fertilia (Sardinia), and Rome and Latina-Sabaudia (Lazio Region) were selected as test cases for the new approach. These coastal stretches are important for the ecosystems and the economic activities they host and are relatively stable areas from a geological point of view. Flood maps were constructed for these areas, for the reference periods 2010–2040, 2040–2070, and 2040–2099. Where possible, the new maps were compared with previous results, highlighting differences that are mainly due to the more refined and resolved sea-level projection and to the detailed Copernicus ground motion data. Coastal flooding was simulated by using the “bathtub” approach without considering the morphodynamic processes induced by waves and currents during the inundation process. The inundation zone was represented by the water level raised on a coastal DTM, selecting all vulnerable areas that were below the predicted new water level. Consequent risk was related to the exposed asset.

The role of rapid glacier retreat and landscape transformation in controlling the post‐Little Ice Age evolution of paraglacial coasts in central Spitsbergen (Billefjorden, Svalbard)

AbstractIn Svalbard, the rapid glacier retreat observed since the end of the Little Ice Age (LIA) has transformed the geomorphology and sediment budgets of glacial forelands, river valleys, and slope systems. To date, relatively little information exists regarding the impact of such a profound glacial landscape degradation on the evolution of coastal environment. This paper addresses this deficiency by detailing the post‐LIA sediment fluxes to the coastal zone in Billefjorden, central Spitsbergen (Svalbard). We analysed the response of the gravel‐dominated barrier coast to the decay of Ferdinandbreen, one of the fastest retreating glaciers in the region. Glacier retreat resulted in the development of paraglacial sediment cascade where eroded and reworked glacigenic sediments progressed through alluvial fans to the coast, thus feeding gravel‐dominated spit systems in Petuniabukta. We demonstrated that the coastal systems in central Spitsbergen responded abruptly to post‐LIA climatic changes. The acceleration of coastal erosion and associated spit development was coincident with rapid climate warming that dates from the 1980s and has been associated with longer ice‐free periods and activation of multiple sediment supply sources from the deglaciated landscape. In colder phases of post‐LIA period, coastal zone development was subdued and strongly dependent on the efficiency of sediment transport via in a longshore drift. Finally, we discuss the differences in the post‐LIA coastal responses between central Spitsbergen and western Spitsbergen highlighting the efficiency of paraglacial sediment delivery from land to the coast controlled by the state of glacial systems, bedrock topography, and development of river channels.

Sedimentary Patterns and Evolution of Coastal Environments during the Holocene in Central Belize, Central America

ABSTRACT Adomat, F. and Gischler, E., 2015. Sedimentary patterns and evolution of coastal environments during the Holocene in central Belize, Central America. Coastal lagoons, marshes, and swamps cover large areas of the Belize coast. Twenty-six sediment cores collected along five transects along the central Belize coast and 58 radiocarbon dates from these cores reveal stratigraphic details of coastal sediment deposition. Marine inundation of the mainland and coastal lagoon formation started between 7980 calendar years before present (cal BP) and >5547 cal BP. As a response to sea-level rise during the Holocene transgression, facies retrograded toward the coast, as seen in marginal marine overlying brackish mollusk faunas. Evidence for late Holocene progradation of facies due to sea-level stagnation is largely lacking. The occurrence of landward thinning sand beds, hiatuses, and marine fauna in lagoonal successions are indications of event (overwash) sedimentation. Sediments recovered are largely of Holoc...

Numerical Modeling of Suspended Sediment Concentration and Its Validation for the Hooghly Estuary, India

Suspended sediment transport plays an important role in the evolution of coastal environment. Hence, observation and modeling of suspended sediment concentration (SSC) is of immense interest to coastal oceanographers, engineers and coastal zone management authorities. The variation of SSC in an estuary is expected both in space and time scales governed by factors such as freshwater influx, tidal variation and basin geometry. The present study reports on development of SSC model for the tidal dominated Hooghly basin, a tributary of the Ganges River having its discharge in the Bay of Bengal, India. The Hooghly estuary experiences high rates of sedimentation related problems requiring periodic maintenance dredging at various locations in the basin. Being a tidal dominated estuary, varying loads of suspended sediments is distributed along various channels in the estuarine zone. The existing SSC models developed earlier for this region had inherent limitations that tend to over-predict computed SSC. These issues critically investigated in the present study thereby developing an upgraded SSC model. It includes better physical parametrizations compared to existing SSC models developed for this region. Efficacy and robustness of the developed SSC model substantiated with measurements conducted in the Hooghly basin. Validation of model computed SSC performed with all available data that comprises of 15 location specific observations of SSC. The validation results signify that upgraded SSC model performs reasonably well compared to field measurements.