Effects of saltwater intrusion on pinewood vegetation using satellite ASTER data: the case study of Ravenna (Italy)

Abstract

The San Vitale pinewood (Ravenna, Italy) is part of the remaining wooded areas within the southeastern Po Valley. Several studies demonstrated a widespread saltwater intrusion in the phreatic aquifer caused by natural and human factors in this area as the whole complex coastal system. Groundwater salinization affects soils and vegetation, which takes up water from the shallow aquifer. Changes in groundwater salinity induce variations of the leaf properties and vegetation cover, recognizable by satellite sensors as a response to different spectral bands. A procedure to identify stressed areas from satellite remote sensing data, reducing the expensive and time-consuming ground monitoring campaign, was developed. Multispectral Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data, acquired between May 2005 and August 2005, were used to calculate Normalized Difference Vegetation Index (NDVI). Within the same vegetation type (thermophilic deciduous forest), the areas with the higher vegetation index were taken as reference to identify the most stressed areas using a statistical approach. To confirm the findings, a comparison was conducted using contemporary groundwater salinity data. The results were coherent in the areas with highest and lowest average NDVI values. Instead, to better understand the behavior of the intermediate areas, other parameters influencing vegetation (meteorological data, water table depth, and tree density) were added for the interpretation of the results.

Correlation between geochemical, mineralogical and physical characters of sediments and salinization phenomena in a pilot area in the ionian plain (Southern Italy)

“…Salt accumulation is generally more accentuated at the soil surface, when salt deposition from marine spray or water evaporation from brackish pool and ponds occur. The excessive exploitation of groundwater at ground level or close by and the indiscriminate use of fertilizers and/or land irrigation using brackish or saline waters can also contribute and exacerbate the salinization processes with very serious consequences on crops and plants (Barbarella et al 2015;Gkiougkis et al 2015;Argamasilla et al 2017;Imbrenda et al 2018). Crop salinity tolerance depends on the crop species, however, the growth of most agronomic crops is inhibited or greatly hindered when effective electrical conductivity is greater than 4 dS/m (Soil Salinity Staff 1954; Andrews et al 2004;Karlen et al 2008;Aldabaa et al 2015).…”

ASTER and Worldview-2 satellite data comparison for identification of groundwater salinization effects on the Classe pine forest vegetation (Ravenna, Italy)

“…Before comparing the ASTER (VNIR sensor only, spatial resolution of 15m) and the WV-2 data (spatial resolution of 2m), the procedure developed on the nearby San Vitale Pinewood (Barbarella et al, 2015) was applied to each satellite data. Since the two images were acquired respectively on 05/18/2011 and on 05/29/2011, the atmospheric correction to retrieve surface reflectance was required (Yuan andNiu 2008, Abuzar et al, 2014).…”

“…The presented analysis is based on ASTER and Worldview-2 (below WV-2) images, acquired in May 2011. In order to study the possible advantages of high spatial resolution in face of the medium resolution, the same procedure to identify portions of pinewood affected by groundwater salinization (Barbarella et al, 2015) was applied to each satellite data and the results were statistically compared (Pu and Landry, 2012). Given that, within the Classe pinewood, the same stressed areas were recognized, this study can suggest the use of the medium resolution in continuity with high resolution dataset.…”

Studies on water resources salinization along the Italian coast: 30 years of work

“…1E). Barbarella et al (2015) used satellite ASTER data to assess the effects of SWI on coastal pinewood vegetation, while airborne electromagnetics methods (AEM) were employed to identify SW-GW exchange in the Venice Lagoon (Viezzoli et al 2010). On the other hand, few studies were performed in laboratory conditions to understand specific mechanism influencing saltwater distribution in the field, like the complex biogeochemical processes that occur between buried peaty lenses and the flowing through GW (Colombani et al 2016a).…”