VERBI VEnice Research BIbliography
VERBI VEnice Research BIbliography |
|
 |
 |
|
Amos, C. L., Umgiesser, G., Reed, P., Munford, G., & Lea, J. (2004). The residual tidal circulation of water. sediment and organics in northern venice lagoon, italy. Scientific Research and Safeguarding of Venice, Corila Research Program 2002 Results, II, 189–202.
Added by: Dott. Alessandro Meggiato (28/05/2014 16:19:41) |
| Tipo di Risorsa: Articolo di Rivista Chiave di citazione BibTeX: Amos2004 Invia la risorsa per email ad un amico View all bibliographic details  |
Categorie: General Keywords: extend abstract corila, Idrodinamica e Morfologia, processi ambientali - Environmental Processes Creatori: Amos, Lea, Munford, Reed, Umgiesser Collezione: Scientific Research and Safeguarding of Venice, Corila Research Program 2002 Results |
Visualizzazioni: 4/757
Indice di Visite: 50% Indice di Downloads: 8% Indice di Popolarità: 18.5% |
Allegati
 [1/187]
|
| Abstract |
|
This paper is a description of a series of studies undertaken along the Treporti-Burano canal and its tributaries within the CORILA project 3.2 (Hydrodynamics and Morphology of Venice Lagoon). Three main activities are described: (1) frontal development at canal triple-junctions and the impact on scouring; (2) turbid plumes and the impact on residual sediment movement; and (3) the nature and effectiveness of submerged beaches on marsh protection. The over-arching purpose of the study was to measure the mass transport and residual motion of water, inorganic suspended particulate matter, and organic carbon within what is considered to be a key region of northern Venice Lagoon from the perspective of numerical simulation. The region is unique because tidal marshes on Palude della Rosa are accreting at 1.54 cm/a whereas, elsewhere in the Lagoon, erosion prevails. It is proposed that understanding the mechanisms at play in the northern Lagoon is vital to remediation or reversal of habitat destruction in the central and southern parts. Three important conclusions have been reached within the framework of this study: (1) enhanced shearing, peak flows, and vorticity are the mechanisms for scouring deep holes at triple-junctions, and evidence for significant resuspension at peak flows have been found; (2) strong residual flows were found, which enhance the export of material through Scanello and Palude Burano canals; and (3) submerged beaches formed of shelly sand appear widespread, and provide an effective barrier to wave erosion.
Schubel and Kennedy (1984) recognised that tidal estuaries, such as Venice Lagoon, behave as filters to material entering at the head or the mouth. That is, material may be trapped within the estuary as it passes through it: this does not appear to be the case for Venice Lagoon. The efficiency of lagoonal filtering is strongly dependent on the non-tidal residual circulation, turbulent activity, and degree of stratification (Bowden, 1984). The residual currents vary in magnitude and direction within Venice Lagoon (Umgiesser, 2000) and hence the filtering efficiency may be expected to vary. The manifestation of this appears evident in the differing evolutionary trends of paludi north and south of Venice. To the north, Cappucci (2002) detected a mean upward growth of Palude della Rosa. This is in contrast to widespread erosion that is taking place on the adjacent Palude Burano: Yet both are within the catchment area of the Treporti-Burano canal system. Given the general trends of erosion within Venice Lagoon, the question is asked: what factors lead to the accretion of Palude della Rosa, and equally important, why is Palude Burano not also undergoing accretion? Possible controls on the patterns of growth are: high local sediment supply from rivers, high sediment supply from the erosion of adjacent tidal flats, biological effects, local changes in wave exposure, changes in residual flows in the adjacent canals which favour import of sediment over export, or some combination of these mechanisms. The main objectives of this study were thus to: (1) determine the residual flows within the Treporti-Burano canal and two of its tributaries: Scanello canal which drains Palude della Rosa, and Palude Burano canal, which drains Palude Burano; (2) determine the mass balance of suspended particulate matter through the canals and (3) suggest sources and sinks of the suspended particulate matter. Other factors, unique to the region, have also been investigated. Specifically, to examine the role of canal triple junctions to enhance bed scour through frontal development and enhanced shear, and finally, to examine the serendipitous discovery of submerged beaches on the preservation of paludi through wave attenuance. Added by: Dott. Alessandro Meggiato |