Remote sensing observations and geoelectrical surveys in a critical coastal area affected by soil salinity

Soil salinization heavily affects soil quality and productivity and is one of the most widespread soil degradation processes on the Earth. At European level, it is listed as one of the main threats of soil deterioration in the EU Soil Thematic Strategy (COM231/2006). Such a threat is particularly relevant along coastal areas, where the strong incidence of human activities mainly linked to agriculture and tourism induces or exacerbates the process. For monitoring soil salinization over large areas, we implemented an integrated approach based on remote sensing and geophysical techniques. In particular, multi-temporal remote sensing images (Landsat-TM/ETM, Spot, Corona) were analyzed to assess vegetation pattern evolution as indirect indicator of soil condition, and to evaluate shoreline changes jointly with field-GPS surveys and aerial laser scanner acquisitions. Critical areas identified at broad scale were investigated in situ by performing geoelectrical resistivity surveys with a multi-electrode acquisition system for characterizing soil salinity content and distribution. Such an integrated approach was adopted for monitoring the Ionian coast of Basilicata Region (Southern Italy) characterized by a narrow shore (10-30 m) of fine sandy formations; the area includes the main rivers (Bradano, Basento, Cavone, Agri, and Sinni) with their mouths, whose surrounding forested areas are Sites of Community Interest (SCI). The integrated analysis of vegetation patch complexity variations, shoreline changes, and geophysical surveys highlighted that areas characterized by soil layers saturated by sea water limiting plant development are located along regression shorelines marked by fragmented patches, whereas the compacted patches are mainly present along progression areas where soil salinization is reduced. The obtained results suggest that the integration of remote sensing peculiarities (synoptic view, multi-temporal availability) as preliminary screening to minimize efforts and costs of field campaigns with those of geophysical techniques (local details, non-invasive soundings) can represent a suitable support tool for monitoring soil salinization processes along coastal areas and at the same time for identifying the most appropriated sites for restoration interventions.