Abstract

The Sibari Plain, located in northeastern Calabria (southern Italy), represents a large coastal alluvial plain withconsiderable agricultural and tourist development. The plain is crossed by secondary ephemeral rivers and by the CratiRiver, the main regional river. The area is characterized by low rainfall and by the presence of a shallow unconfined andoutcropping aquifer lying on a confined aquifer.A geochemical survey was carried out on 103 selected wells from June to September 2012 in the framework of theproject PON01_ 02818 AMICUS to investigate the chemical and isotopic composition of local groundwaters of the bothaquifers. In situ measurements of electrical conductivity show a mean value of 1.1 mS/cm and a maximum value of 4.2mS/cm close to Crati Delta area. The interpretation of chemical data allows one to recognize 4 hydrochemical facies. TheCa-HCO3 hydrochemical facies (70 samples) has a Total Ionic Salinity (TIS) comprised between 6 and 34 meq/L. It isprobably generated by calcite dissolution, a mineral phase that dissolves very quickly and that is very frequent in thestudy area. The Na-HCO3 waters (13 samples) have TIS of 11 to 46 meq/L partly overlapping or somewhat higher thanthe TIS range of Ca-HCO3 ones. The origin of these groundwaters is probably due to reflow of Ca-HCO3 groundwater inshallow aquifers, previously flooded with seawater and/or brackish water (freshening). The Na-Cl hydrochemical faciese (14 samples) show a wide TIS range, from 22 to 80 meq/L, generally higher than that of Ca-HCO3 water, but still belowthe TIS of 1210 meq/L of mean seawater. These waters are typically found in aquifers located near the coast and in thearea of the Crati Delta. Close to the coastline, the origin of these waters can be related to ingression of seawater and/orbrackish water within the sediments of the alluvial plain. This intrusion of seawater and/or brackish water takes placeeither directly (salt wedge), or through inflow of seawater along the riverbeds and subsequent infiltration into thesurrounding shallow aquifers hosted in the alluvial deposits. This process may be favored by intense pumping from wellslocated near the riverbeds. The presence of Na-Cl waters in the inland area could be related to local upflow of deep brines(recorded in deep exploration boreholes) along tectonic discontinuities. The Ca-Cl type (3 samples) has TIS of 33-49meq/L, exceeding that of the Ca-HCO3 waters. This is a chemical composition generated by ionic exchange consequentto seawater ingression.Furthermore, the average infiltration elevation for the groundwaters of the Sibari Plain was obtained by means of thed18O and d2H values of H2O. The computed average infiltration elevations, supported by the results of the numericalgroundwater modelling, suggest that the Sibari Plain aquifers system receives underground inflows from the surroundingPollino and Sila massifs.

Autore Pugliese

• Polemio Maurizio

Tutti gli autori

• Cianflone G.; Vespasiano G. ; Apollaro C.; Dominici R. ; Marini L.; Romanazzi A.; Polemio M. ; De Rosa R.

Titolo volume/Rivista

Rendiconti online Società Geologica Italiana

Anno di pubblicazione

2016

ISSN

2035-8008

ISBN

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Numero di citazioni Wos

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Numero di citazioni Scopus

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Settori ERC

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Codici ASJC

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