The Pisa plain, encompassing the Arno and Serchio river estuaries, had been home for human settlements since early Neolithic. During the last two centuries, urban and industrial growth increased the water demand, while industrialization and intensive agriculture caused significant and invasive water pollution, reducing the availability of freshwater. Mechanical reclamation of coastal wetlands and uncontrolled pumping of wells near the coastline have in addition produced Seawater intrusion to the unconfined aquifer. Knowledge and government of water resource should certainly be a public main task: the present work is part of a Pisa Municipality wider project to preserve the unconfined coastal aquifer from Seawater intrusion and other degradations. 3D finite-differences numerical models were applied to the coastal unconfined aquifer, also zooming to the tourist villages of Marina di Pisa and Tirrenia. A numerical flow model of the area between the Arno River to the North, Navicelli Canal to the East, Scolmatore Canal to the South and Ligurian Sea to the West, was implemented and calibrated (Wide Area Model - WAM) to provide boundary condition for the two local models of Marina di Pisa and Tirrenia. Hydrostratigraphy, rainfall pattern, thermometry, water table trend, salinity and hydraulic parameters, head of surface water bodies of the unconfined aquifer are needed for numerical model implementation. Monthly water table and salinity surveys (from October 2007 to December 2009) together with acquisition, systematization and processing of bibliographic and new on-site data were carried out to improve a conceptual model, then translated into a constant density, large-scale numerical model of the WAM. On the contrary, Marina di Pisa and Tirrenia areas were implemented as variable-density models. All three models were calibrated and sensitivity parameters identified. The local models outputs show a modest degree of direct marine intrusion near the shoreline. In the dune area to the West of Marina di Pisa, the Seawater intrusion is reduced to a thin lamina below a thick freshwater saturated layer. Near Tirrenia, the unconfined aquifer is completely salty, showing high to very high salinity in the retrodune lagoons areas to the West. This work is an exportable methodological example of numerical technique of Seawater intrusion study suited for a quantitative anticipatory evaluation of the possible counteractions.
|Autori:||AMBROSIO M; CURCIO C; FAGIOLI MT; GIANNECCHINI R|
|Titolo:||L’acquifero freatico costiero della Pianura di Pisa tra Fiume Arno e Canale Scolmatore: implementazione e calibrazione del modello numerico|
|Anno del prodotto:||2011|
|Appare nelle tipologie:||1.1 Articolo in rivista|