Subsoil architecture and morphological setting shaping the saltwater
intrusion in the coastal plain south of the Venice lagoon, Italy
L. Tosi, C. Da Lio, S. Donnici, E. Fornaro
Institute of Marine Sciences, CNR, Venezia, Italy
E. Carol, E. Kruse
Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad Nacional
de La Plata, Argentina
V. Bassan, A. Mazzuccato
Provincia di Venezia - Servizio Geologico, Difesa del Suolo e Tutela del Territorio,
Mestre-Venezia, Italy
P. Teatini
Dept. of Civil, Environmental and Architectural Engineering, University of Padova, Padova,
Italy
ABSTRACT
The southern catchment of the Venice watershed (Italy) is threatened by shallow aquifer and soil
salinization. The saltwater may extend inland up to 20 km from the Adriatic coastline and deepen
down to some tens of meters. Here, saltwater contamination is driven by other forcing factors than
excessive pumping, such as ground elevation, buried geological structures, tide encroachment
along watercourses, climate and tide conditions, and drainage practices implemented in reclaimed
areas. This work aims to outline a conceptual model of the saltwater contamination highlighting the
mechanisms driving the saltwater-freshwater exchanges. Results show that the fresh/salt-water
interface depth varies from 1 to 30 m below the ground level and exhibits a significant, mainly
seasonal, time variation. The dynamics of the soil salinization process is especially sensitive to
changes in river (Brenta, Bacchiglione, Adige, Gorzone) discharges, groundwater and channel
levels, which are regulated by a number of pumping stations, and climate conditions. Relict
geomorphological features, filled with high permeability sediments, act as preferred pathways for
groundwater flow and solute transport. In fact they provide a hydraulic connection between
freshwater aquifers and sea, possibly facilitating saltwater intrusion landward or, conversely, acting
as reservoir of freshwater provided by precipitation, irrigation, percolation through channel beds.
