Conference Agenda

The upper-Jinsha River region has steep terrain and broken structures, causing landslide disasters frequently. Thus, it is important to monitor the surface deformation and analyze the stability in this area. Here we use the distributed scatterer interferometric SAR (DS-InSAR) method is used to monitor and analyze the Woda landslide area. Employing the hypothesis test of confidence interval (HTCI) algorithm we select the statistically homogeneous pixel (SHP) and using adaptive spatial nonlocal filtering method based on the identified SHP for phase optimization to select DS points. The obvious advantage is that DS points are used together with persistent scatterer (PS) points to increase the density of monitoring points in the study area. By the DS-InSAR method, we derive the deformation of the Woda landslide area from 106 Sentinel-1A ascending images acquired in 2014/11/05~2019/09/04 and 102 Sentinel-1A descending images acquired in 2014/10/31~2019/09/11. The two-dimensional deformation of the landslide area shows that the maximum surface deformation rate in the normal direction is -80.3 mm/yr, and in the east-west direction is 117.7 mm/yr. In addition, according to the rescaled range (R/S) analysis, the Hurst index of the deformation trends are all greater than 0.5, which means the deformation trend will continue for some time. Our monitoring results can be used for landslide disaster prevention in mountainous areas.

The area around Ostia and Portus, in the hinterland of Rome (Italy), is well-known for being inhabited and occupied for millennia, with the first traces dating to the Eneolithic, although most archaeological remains and monuments date to the Roman period. Furthermore, it offers a wealth of natural features related to both the Tiber river and the prograding Tyrrhenian coast. As such, it has been selected as an ideal case to investigate the visibility of archaeological cropmarks in temperate environments based on satellite Synthetic Aperture Radar (SAR) data and their suitability for archaeological mapping following the common practice exploited by field archaeologists.

A comprehensive revision of previous research on the hinterlands of Ostia and Portus was first undertaken. Previous studies ranged from remote sensing observations, extensive geophysics, and targeted and random archaeological investigations. These legacy data have been integrated by systematically analysing all historical aerial photos and optical satellite images freely available online such as Google Earth (2002-2022), ESRI basemaps (2011-2021) and Bing (2020). This wide collection of both anthropogenic and natural features, arranged and catalogued in a GIS database with metadata and reference to the information sources, provides the basis for assessing the effectiveness of SAR-based archaeological prospection in this temperate environment.

The few publications exploiting X-band SAR data in this area have shown how multi-temporal averaging of a series of images with similar acquisition parameters helps reduce speckle and improve the readability of archaeological features. However, in Ostia and Portus the fields' state could change abruptly due to harvesting, ploughing and/or farming-related burning. Thus, to understand how these sudden land use / land cover changes affect the multi-temporal averages, we are analysing 10 m resolution Sentinel-2 and 3 m resolution PlanetScope multispectral images to evaluate any significant modification that has occurred in the most recent years. Specifically, the assessment is made for fields where crop marks are visible, by highlighting any changes through True and False Color visualisations and the Normalized Difference Vegetation Index (NDVI) index.

The dynamics of local land use / land cover changes are then used to support the analysis of very high resolution SAR images that are being collected by the Italian Space Agency (ASI) via a tailored monitoring campaign with COSMO-SkyMed constellation in SpotLight mode (1 m resolution) since August 2021. Various filters used in the literature, including the Lee Sigma and Adaptive filters, are tested to improve the readability of the archaeological cropmarks and to identify the most suitable filtering parameters enabling an archaeologist to discern buried structures.

In addition, to keep monitoring the fields of archaeological relevance, a targeted SkySat multispectral image collection at 50 cm resolution has been tasked since July 2022 via the ESA Cat-1/EO Data User Project GEOARCHAMMI. Repeated on-site verifications are carried out on the occasion of the SkySat image collection for ground-truthing.

The intended goal is to achieve a spatial mapping of archaeological features visible from satellite data that, in combination with those known from the literature, can be used by an archaeologist to improve the understanding of settlement patterns and the environmental evolution of this cultural landscape.