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  • 1
    Publication Date: 2017-04-04
    Description: The catchment south of the Venice Lagoon is threatened by shallow aquifer salinization and land subsidence. Although the area is not experiencing everywhere saline contamination and high sinking rates, a very serious situation has been brought to light in a large portion of the coastal farmland. The salt water contamination, recently investigated within a series of research projects, i.e. ISES, BRENTA, Co.Ri.La. 3.10-3.16, extends up to 20 km inland from the coast (Carbognin and Tosi, 2003; Rizzetto et al., 2003; Carbognin et al., 2005, 2005b). The depth of the fresh/salt-water interface varies from 1 to 30 m below the ground level and exhibits a significant, mainly seasonal, time variation. The dynamics of the soil salinization process is especially sensitive to changes in river (Brenta, Bacchiglione, Adige, Gorzone) discharges, in groundwater and channel levels regulated by a number of pumping stations of the reclamation network, and in weather conditions. At the same time an ongoing land subsidence with rates varying from few mm/yr to cm/yr affects the southern lagoon margin and the nearby watershed (Tosi et al., 2000; Teatini et al., 2007). The settlement of these territories is mainly due to natural consolidation (Teatini et al., 2005) and geochemical subsidence, i.e. peat oxidation promoted by farming activities (Gambolati et al., 2005). Salt water intrusion and land subsidence combined with significant dry seasons expose this area to the potential soil desertification. The combined effect of both processes is producing an alarming social and environmental impact on the south Venice coastland, also in relation to the expected global climate change.
    Description: Published
    Description: Rimini, Italy
    Description: 6A. Monitoraggio ambientale, sicurezza e territorio
    Description: open
    Keywords: saltwater intrusion ; land subsidence ; soil desertification ; Venice lagoon ; Bacchiglione-Brenta river mouth ; 05. General::05.08. Risk::05.08.02. Hydrogeological risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Abstract
    Location Call Number Limitation Availability
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  • 2
    Publication Date: 2021-08-16
    Description: In permafrost areas, seasonal freeze-thaw cycles result in upward and downward movements of the ground. For some permafrost areas, long-term downward movements were reported during the last decade. We measured seasonal and multi-year ground movements in a yedoma region of the Lena River Delta, Siberia, in 2013–2017, using reference rods installed deep in the permafrost. The seasonal subsidence was 1.7 +- 1.5 cm in the cold summer of 2013 and 4.8 +- 2 cm in the warm summer of 2014. Furthermore, we measured a pronounced multi-year net subsidence of 9.3 +- 5.7 cm from spring 2013 to the end of summer 2017. Importantly, we observed a high spatial variability of subsidence of up to 6 cm across a sub-meter horizontal scale. In summer 2013, we accompanied our field measurements with Differential Synthetic Aperture Radar Interferometry (DInSAR) on repeat-pass TerraSAR-X (TSX) data from the summer of 2013 to detect summer thaw subsidence over the same study area. Interferometry was strongly affected by a fast phase coherence loss, atmospheric artifacts, and possibly the choice of reference point. A cumulative ground movement map, built from a continuous interferogram stack, did not reveal a subsidence on the upland but showed a distinct subsidence of up to 2 cm in most of the thermokarst basins. There, the spatial pattern of DInSAR-measured subsidence corresponded well with relative surface wetness identified with the near infra-red band of a high-resolution optical image. Our study suggests that (i) although X-band SAR has serious limitations for ground movement monitoring in permafrost landscapes, it can provide valuable information for specific environments like thermokarst basins, and (ii) due to the high sub-pixel spatial variability of ground movements, a validation scheme needs to be developed and implemented for future DInSAR studies in permafrost environments.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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