Mapping impact of urbanization in Shahat-Cyrene (Libya) using a big SAR data approach of change detection with COSMO-SkyMed time series

Abstract

Uncontrolled and unregulated urbanization around the modern town of Shahat, Libya, has been reported by several studies as a pressing issue for the conservation of archaeological heritage in the cultural landscape south of Cyrene UNESCO World Heritage Site (WHS). In this paper, we implemented a big Synthetic Aperture Radar (SAR) data analysis approach on a selection of more than 180 StripMap images that the Italian Space Agency (ASI)’s COSMO-SkyMed constellation has consistently collected at 3-m resolution over Cyrene since 2011, as part of its background acquisition scenario. We prove the accuracy of the method to map the spatial and temporal spread of new building and road blocks using COSMO-SkyMed SAR data, and its complementarity with the mapping based on the full archive of cloud-free Copernicus Sentinel-2 multi-spectral imagery at 10-m resolution (2015-2017). Owing to the higher spatial resolution and half-month frequency of observation of COSMO-SkyMed, we better delineated the new urban features and estimated more precisely when these were developed across the landscape.