Author(s): Monique M. Villatoro
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Keywords: Tidal inlet; Morphology; Ebb-tidal delta; Coastal lagoon; Anthropogenic influence
Abstract: This paper studies the geomorphology of Chioggia inlet and its surroundings in the light of long term morphological changes in southern Venice lagoon. Bathymetry surveys extending over two weeks of September 2005 and 2006 provided enough data to identify an ebb tidal delta protruding southeast of the inlet mouth. Comparison of the 2005-2006 mapped sea bed of outer Chioggia with a 1990 data set shows a growth trend of 280, 000 m3 of sand/yr. According to historical charts (Bondesan and Menghel, 2004) the ebb delta is a new feature of the shore face (about 70 years old) and is the product of the construction of jetties in the early 20th century. Comparative bathymetry for the years of 1990 to 2000 shows that, with the exception of a small gain between 1970 and 1990, southern Venice Lagoon has eroded at a rate of 155, 000 m3/yr. This sediment is likely to be contributing to the evolution of the ebb-tidal delta. However, another possible source was identified, a sub-aqueous ebb tidal spit, protruding from the Sottomarina beach south of the inlet towards the delta. This spit is fed by northwards alongshore transport, and although there is a clear separation between the spit and the ebb tidal delta, some of the sand might be reaching the delta. This study will the provide foundation for further understanding of the processes governing dispersal of sand in the area, and for a quantitative analysis, as described by Amos et al., (2007) and Amos et al., (2006).
Year: 2007