Assessment of Building Damage in Raqqa during the Syrian Civil War Using Time-Series of Radar Satellite Imagery

Abstract

Change detection is one of the key tasks of earth observation. In the humanitarian domain, information about the impacts of natural disasters or military conflicts are of particular interest. This study uses time-series of Sentinel-1 radar imagery to identify changes resulting from armed combats in the city of Raqqa, Syria. The concept of permanent scatterers (PS) was applied to the data for the identification of stable information, which is then used for temporal analysis of pixel amplitudes. In an urban context, this gives insights into both the locations of damage and the exact date of the destruction. Instances of damage manually identified by UNOSAT are used for validation. The study shows that Sentinel-1 data can be a suitable indicator for heavy damage, but limitations arise from the comparably low spatial resolution and in cases of moderate changes which do not affect the structure of buildings. The study demonstrates the potential of radar imagery regarding its spatial and temporal resolution and gives examples of detailed analyses at selected areas of special interest.

Refugee Camp Monitoring and Environmental Change Assessment of Kutupalong, Bangladesh, Based on Radar Imagery of Sentinel-1 and ALOS-2

“…This slight under-estimation was also indicated, but not fully explained by the user's accuracies (92.1%) and kappa value (0.9) of the camp class from February 2018 because in the image used for training (13.02.2018) the classifier was closer to the radar image (01.02.2019) than the one used by Hassan et al (15.12.2017). Nonetheless, the ambiguity in the backscatter intensity of solid and light dwellings can become a problem in studies dealing with humanitarian settings, as already discussed by Braun [125], however, more research is required to understand the differences between their radar signatures [126].…”

Earth observation tools and services to increase the effectiveness of humanitarian assistance

“…Topics addressed in demonstrator products within the EO4HumEn+ project and scenarios to extend the current portfolio of the humanitarian information service (POP = population monitoring, ENV = environmental resources). Moderate or light damages were not detectable by SAR data at this resolution but the general suitability of a persistent scatterer for damage assessment was proved in this study (Braun, 2018).…”

“…The study used a mixed sensor approach of SAR (ERS-2 and Sentinel-1), and optical HR (Landsat TM and Landsat OLI) to cover a time span of 18 years in 7 time slots. An index was calculated to evaluate the environmental impact of land use transformation considering weighted distributions of land cover according to the FAO-LCCS scheme (Di Gregorio & Jansen, 2005) in the respective time slot (Braun, 2018).…”

Explaining intentional cultural destruction in the Syrian Civil War

“…US air support for the Kurdish-led Syrian Democratic Forces resulted in substantial collateral damage, most notably in the campaign to capture the city of Raqqah and its environs Figure 1. Expected ICD incidence and ISIS territorial control (Braun, 2018). Other rebel forces gradually became dominated by Islamist groups, such as Jabhat al-Nusra (later renamed Tahrir al-Sham) and Ahrar al-Sham, with iconoclastic and religiously intolerant tendencies (Anzalone, 2016).…”