Groundwater freshening following coastal progradation and land reclamation of the Po Plain, Italy

High-resolution electrical resistivity tomography (ERT) with electrode spacing of 1 m proved to be an effective methodology to characterize ephemeral, sparse, and discontinuous freshwater lenses within the almost completely salinized shallow aquifer of the low coastal zone near Ravenna. ERT profiles with a vertical resolution of 0.25–0.5 m, once calibrated with groundwater data (water table depth and electrical conductivity) collected in multi-level sampler systems at the same spatial resolution, are reliable and provide repeatable measurements in time. The ERT methodology allows for fast data acquisition over large areas and it also permits the study of the evolution in time of freshwater availability in coastal zones, which is important for local ecosystems and soil resources. This makes high-resolution ERT a valid tool to aid local stakeholders and decision makers to effectively manage freshwater lenses, and guarantee their preservation or augmentation by means of managed aquifer recharge.

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“…inland. The gradient is inland-oriented, because of the drainage rate controlled by the land reclamation authority [53].…”

Section: Wtdmentioning

confidence: 99%

“…The WTD is controlled by the drainage channel, which crosses the pine forest parallel to the coastline. The drainage channel guarantees a 1-m-deep vadose zone that preserves the coastal forest from water logging and flooding [4,33] but at the same time promotes saltwater seepage from the bottom of the aquifer [49,53].…”

Section: Wtdmentioning

confidence: 99%

High-Resolution Electrical Resistivity Tomography (ERT) to Characterize the Spatial Extension of Freshwater Lenses in a Salinized Coastal Aquifer

Greggio

Giambastiani

Balugani

et al. 2018

Water

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“…Under natural condition, the subsidence is a few millimetres per year, whereas anthropogenic subsidence rate is about 6–21 mm year −1 in the monitored area (Taramelli, Di Matteo, Ciavola, Guadagnano, & Tolomei, ). Because of low topography, high rate of natural and anthropic subsidence and an extensive drainage system (Antonellini, Allen, Mollema, Capo, & Greggio, ), the coastal aquifer is subjected to marine ingression with groundwater that remains brackish to saline. Freshwater lenses are limited in areal extent, thickness, and time and are related to dune heights in coastal systems (Cozzolino et al, ).…”

Section: Introductionmentioning

confidence: 99%

Forest fire effects on groundwater in a coastal aquifer (Ravenna, Italy)

Giambastiani

Greggio

Nobili

et al. 2018

Hydrological Processes

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We examined the fire-induced changes in groundwater recharge rate. This aspect is particularly important in the case of large forested areas growing over a coastal aquifer affected by saltwater intrusion. In the Ravenna coastal area (Italy), pine forests grow on coastal dune belts, overlying a sandy unconfined aquifer, which is strongly affected by marine ingression. Three groundwater profiles across the forest and perpendicular to the coastline were monitored for groundwater level, physical, and chemical parameters. The aims were to define groundwater quality, recharge rate, freshwater volume, and highlight change, which occurred after a forest fire with reference to pre-fire conditions. Analytical solutions based on Darcy Law and the Dupuit Equation were applied to calculate unconfined flow and compare recharge rates among the profiles. The estimated recharge rates increased in the partially and completely burnt areas (219 and 511 mm year −1 , respectively) compared with the pristine pine forest area (73 mm year −1 ). Although pre-fire conditions were similar in all monitored profiles, a post-fire decrease in salinity was observed across the burnt forest, along with an increase in infiltration and freshwater lens thickness. This was attributed to decrease canopy interception and evapotranspiration caused by vegetation absence after the fire. This research provided an example of positive forest fire feedback on the quantity and quality of fresh groundwater resources in a lowland coastal aquifer affected by saltwater intrusion, with limited availability of freshwater resources. The fire provided an opportunity to evaluate a new forest management approach and consider the restoration and promotion of native dune herbaceous vegetation.

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“…A large number of studies have established that the main source of salinity is coming from water-rock interactions [186][187][188][189], and to better establish such relationships in those papers, the researchers largely used stable and radioactive isotopes in groundwater were largely used. Less studies have pointed out paleo-seawaters as the main mechanism of aquifer salinization [190][191][192][193][194][195][196][197][198][199], although in many cases this distinction was possible by using high resolution MLSs. Only a few papers distinguished as the main salinization mechanism the return flow from agricultural lands [200][201][202].…”

Section: Groundwater Salinization Origins and Mechanismsmentioning

confidence: 99%

The Issue of Groundwater Salinization in Coastal Areas of the Mediterranean Region: A Review

Mastrocicco

Colombani

2021

Water

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The Mediterranean area is undergoing intensive demographic, social, cultural, economic, and environmental changes. This generates multiple environmental pressures such as increased demand for water resources, generation of pollution related to wastewater discharge, and land consumption. In the Mediterranean area, recent climate change studies forecast large impacts on the hydrologic cycle. Thus, in the next years, surface and ground-water resources will be gradually more stressed, especially in coastal areas. In this review paper, the historical and geographical distribution of peer-review studies and the main mechanisms that promote aquifer salinization in the Mediterranean area are critically discussed, providing the state of the art on topics such as actual saltwater wedge characterization, paleo-salinities in coastal areas, water-rock interactions, geophysical techniques aimed at delineating the areal and vertical extent of saltwater intrusion, management of groundwater overexploitation using numerical models and GIS mapping techniques for aquifer vulnerability to salinization. Each of the above-mentioned approaches has potential advantages and drawbacks; thus, the best tactic to tackle coastal aquifer management is to employ a combination of approaches. Finally, the number of studies focusing on predictions of climate change effects on coastal aquifers are growing but are still very limited and surely need further research.

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Groundwater freshening following coastal progradation and land reclamation of the Po Plain, Italy

Cited by 29 publications

References 30 publications

High-Resolution Electrical Resistivity Tomography (ERT) to Characterize the Spatial Extension of Freshwater Lenses in a Salinized Coastal Aquifer

High-Resolution Electrical Resistivity Tomography (ERT) to Characterize the Spatial Extension of Freshwater Lenses in a Salinized Coastal Aquifer

Forest fire effects on groundwater in a coastal aquifer (Ravenna, Italy)

The Issue of Groundwater Salinization in Coastal Areas of the Mediterranean Region: A Review

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