A Multidisciplinary Approach for Paleoenviromental Reconstruction in Ultra-Shallow Water through Acoustics and Core Sampling

The lagoon of Venice represents a very peculiar environment resulting from combined natural and anthropic action. It began to form during the last marine transgression about 5500 years ago. Since then, its morphological aspect has drastically changed. The changes are due, on one hand, to natural causes like tributary river sediment supply, eustatic variations and natural subsidence. On the other hand, the anthropic action had a strong impact on the lagoon evolution. The first anthropic settlements go back in time to the roman age, but the big engineering and dredging works started about the 14th century AD and are still ongoing. All these interventions contributed to radical changes in the lagoon hydrodynamics. The consequent change in the lagoon morphology can be established by studying the content of the lagoonal sediments. For this purpose, a multidisciplinary research project has been carried out over a large area (about 50 km 2) of the lagoon. An extensive high space resolution acoustic survey in ultra-shallow water (up to a depth 0.5 m) together with geological analysis from 60 cores extracted in the explored area revealed the Holocene sedi- ment architecture. In particular a complex network of buried palaeochannels was reconstructed thanks to the acoustic techniques that allowed a detailed mapping of the buried lagoonal morphologies.