It is likely that this channel was one of the Brenta river mouths cited signaling pathway by Comel (1968) and by Bondesan and Meneghel (2004) closed by the Venetians in 1191 in order to slow down the filling process of the lagoon. Before this diversion the Brenta river flowed to the city of Venice through the ancient “Canal de Botenigo” into the Giudecca Channel (Fig. 3) through the island of Tronchetto. This

hypothesis is confirmed by the presence of a similar channel deposition in the transect B–B′ between Santa Marta and the Canal Grande shown on page 20 in Zezza (2008). This palaeochannel is further described in Zezza (2010), where it is observed that in the city area “the lithostratigraphic model of the subsoil reveals that alluvial processes lasted until the verge of the Holocene Period and, furthermore, that the Flandrian transgression determined first all the widening and successively the partial find more filling of the alluvial channel, incised into the caranto and evolved into a tide channel during the Holocene”. Finally in the southern part of profile 4 (Fig. 2d) one can see the chaotic and structureless filling of a recent superficial palaeochannel (CL3). This kind of acoustic signal probably corresponds to a sandy filling of the channel. The absence

of stratified reflectors implies a highly energetic environment and a fast channel filling. The palaeochannel CL3 corresponds to the “Coa de Botenigo” (Fig. 4b). The map of the areal extension of all palaeochannels reconstructed in the study area is shown in Fig. 4 for five different times: Fig. 4a represents the palaeochannels that were dated between 2000 BC and 0 AD, active during the Bronze, Iron Age and Roman Times reconstructed using as a basis the acoustic survey and the geological data. This corresponds

to a natural environment immediately before the first stable human settlements. Instead, the map of 1691, which is one of the first detailed cartographic representation of the area, refers to a time when some of the main river and channel paths were already modified by the Venetians. Fig. 4b–d depicts not only the reconstructed palaeochannels but also channel paths (and when available the land extension), digitized from the historical maps of Inositol monophosphatase 1 1691, 1810, 1901, respectively. The present situation is shown in Fig. 4e. Many palaeochannels were reconstructed in the area, adding more information to the historical maps. In general they flow almost parallel in the west-east direction, with a slightly sinuous path. This orientation can be explained by the fact that this hydrographic system probably belonged to the Brenta megafan (Bondesan and Meneghel, 2004 and Fontana et al., 2008). A few palaeochannels have a north–south direction. This orientation may be related to the natural development of tidal networks. We show the patterns of the palaeochannels that existed before or that formed immediately after the lagoon expansion in the area (Fig. 4a).