Data di Pubblicazione:
2015
Citazione:
Groundwater flow in Venice-Porto Marghera and the impact of containment works / J. Terrenghi, G.P. Beretta, S. Fassina, M. Cattelan, L. Penzo, L. Zanella, C. Novello. ((Intervento presentato al 42. convegno AQUA tenutosi a Roma nel 2015.
Abstract:
Some environmental remediation works in the Site of National Interest (SIN) of Venezia-Porto Marghera provide numerous geological and hydrogeological investigation data: over 5000 boreholes and piezometric data from a remote monitoring system (55 piezometers) were used to support the numerical groundwater model made up to assess the effectiveness of ongoing actions.
The groundwater flow in the first 30 m depth occurs in sandy aquifers with hydraulic conductivity of about 10-4÷10-5 m/s; the groundwater has a high degree of contamination by inorganic elements and organic compounds originating from the old productions of the industrial area. The water table depth is very low and some territories are under the sea level; these areas are subject of hydraulic drainage works from centuries.
The remediation plan provides a P&T system in a hydraulic isolated area and tens of several km of physical barriers (partially completed) are planned to prevent the influx in the Venice lagoon of contaminated groundwater.
The modeled area (336.49 km2) was discretized with a grid of 100x100 m and 13 layer, in two different periods, respectively with absence and a high recharge rate.
Draining pumps and rivers are the main elements that influence the groundwater flow, determining a flux from upgradient and inducing an infiltration from the seawater downgradient. The studied period shows a consistent recharge occurred during a period of heavy rains.
The physical barriers along the Lagoon determine a rising of the piezometric level in the urban area upgradient the SIN and a lowering of the level in the industrial zone. The realization of a possible barrier between the residential and the industrial areas intercepts a small flow rate, but can determine, in the absence of additional mitigation works, a raising of the water table that can be extended even for a 1.5 km upgradient, also affecting the urban surrounding area.
Looking at the environmental importance of the site and the high costs of the works, further studies can be carried out modeling in more detail, integrating data regarding the relationship between surface water and groundwater, the rate of withdrawals and the increase of the monitoring piezometric network in the upgradient zones.
Tipologia IRIS:
14 - Intervento a convegno non pubblicato
Keywords:
Groundwater modeling; Venezia-Porto Marghera; Site Remediation
Elenco autori:
J. Terrenghi, G.P. Beretta, S. Fassina, M. Cattelan, L. Penzo, L. Zanella, C. Novello
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