Automatization of InSAR mass processing using CSL InSAR Suite (CIS) software for Multidimensional Small Baseline Subset (MSBAS) analysis: example combining Sentinel-1 and Cosmo-SkyMed SAR data for landslides monitoring in South Kivu, DR Congo

DERAUW, DOMINIQUE; DILLE, ANTOINE; ELISE MONSIEURS; LIBERT, LUDIVINE; OLIVIER DEWITTE; FRANÇOIS KERVYN; D'OREYE, NICOLAS; SAMSONOV, SERGEY; ADRIANO NOBILE

Milano

Simposio; Living Planet Symposium; 2019

European Space Agency

Several SAR sensors are today orbiting the Earth and acquiring data with various wavelength and resolution. This offers new opportunities in many Earth Sciences domains but it also calls for new tools to process the massive amount of data and to benefit from the diversity of sensors.We present here an automated mass processing InSAR tool based on- an InSAR processor developed at the Centre Spatial de Liège (CSL), namely the CSL InSAR Suite (CIS; see Derauw et al. this session),- a collection of shell scripts,- the Multidimensional Small Baseline Subset (MSBAS) software (see Samsonov et al., this session)This fully automated mass processing tool aims at performing optimized and self-evaluating mass processing of a large amount of radar interferometric pairs, from any kind of SAR sensor (ERS, ENVISAT, RADARSAT 1 & 2, TanDEM-X, TerraSAR-X, ALOS, CosmoSkyMed, Kompsat-5 and Sentinel-1 A&B) and with any orbital geometry, polarization, wavelength and ground based resolution.The obtained geocoded deformation maps (which can be optionally interpolated to fill small gaps and/or detrended to remove residual phase plane) are automatically fed into the MSBAS software to obtain vertical and horizontal time series of ground deformation.The shell scripts perform optimized sequences of processing for large amount of data, e.g. by sharing intermediate results between compatible processes etc. It does not parallelize the computations but split the number of InSAR processes in a number of parallel sessions chosen by the user. These sessions can be run on separate hard disks in order to minimize the performance loss due to large amount of simultaneous read and write operations on a given hard drive.The processing also self-evaluates the quality of some steps such as the coregistration: if it is not satisfying, it will automatically change the coherence threshold and re-run the coregistration of that specific pair.For Sentinel-1 data, when the precise orbit of an image already used in some interferometric pairs is made available, the processing tool will update all the required products and results.The processing is also incremental, that is, each time (a) new SAR image(s) is (are) received, only the new InSAR compatible pairs satisfying chosen temporal and spatial baselines criteria are automatically processed. These new deformation maps are then added to the database ingested by the MSBAS processing, which only takes a few minutes to hours to be re-run depending on the amount of data.Moreover, additional scripts tools are designed:- to assist the quality check, the result integrity check, to quick look the data at several steps of the processing if required etc.- to plot any kind of maps (amplitude, deformation, coherence etc?), or time series of deformation at single pixels or for double difference between selected pixels,- to create sequence of amplitude images (incl. gif animation),- to create coherence and/or water bodies masks- to launch multiple run of MSBAS to assess the best regularization order etc.In this poster, we illustrate the capabilities of the processing tools with the measure of the ground surface deformations affecting the city of Bukavu, DR Congo. Bukavu is a city of 800.000 inhabitants located south of Lake Kivu in the East African Rift, at the border of Rwanda and Congo. The region is characterized by steep topography affected by heavy precipitations which makes it prone to landslides. Urbanization is very dense and rapidly growing, often without appropriate planning.We simultaneously use 109 Sentinel-1 and 234 Cosmo-Skymed SAR images acquired in ascending and descending orbits between March 2014 and October 2017 to analyze vertical and horizontal ground deformations in the city of Bukavu. The 343 SAR images allow to compute 1063 interferograms with temporal and perpendicular baselines of less than 70 days and 200-350 meters respectively.The analysis of the time series allows the monitoring of a 1.5 km2 landslide which is identified and studied by field observations in Funu (a slum neighborhood in the city of Bukavu). The results are consistent with ground-based measurements performed during dGPS campaigns and with results from classical InSAR time series analysis (Nobile et al, 2018) performed with StaMPS (Hooper, 2008), that is a method which computes time series of ground deformation, though only expressed in the satellite line of sight and only for a given satellite in a given geometry at a time.MSBAS also allows to identify several other landslides in the region. The method can also be used to detect and analyze any kind of ground deformation, from natural or anthropogenic origin (volcano monitoring, post mining or fluid related ground deformation such as from CO2 storage, water pumping, sediment compaction, monitoring of manmade structures such as bridges, warehouses, dams, highways, railways? ).All the component are running on Linux or Mac. They can be obtained from the authors:- CSL InSAR Suite can be obtained on request from the CSL Signal Processing Laboratory (contact : aorban@uliege.be)- Shell scripts suite can be obtained on request from Nicolas d?Oreye (ndo@ecgs.lu)- msbas can be downloaded from http://insar.ca/.