To address the needs of the Haitian community in the south-west of the country involved in recovery and rehabilitation after the impact of Hurricane Matthew in October 2016, the Committee on Earth Observation Satellites (CEOS) triggered the 4 year-long Recovery Observatory (RO) pilot project, led by the National Center for Geo-spatial Information (CNIGS) with technical support from the French National Centre for Space Studies (CNES) [www.recovery-observatory.org].
During the RO pilot, the Italian Space Agency (ASI) contributed with scientific research aiming to develop – jointly with the RO management and technical team from CNES and CNIGS – a workflow which encompassed: (i) tasking of satellite high resolution Synthetic Aperture Radar (SAR) data for regular observations of the priority areas defined by the Haitian users; (ii) image processing, also testing computing and algorithm resources that could ensure future sustainability; (iii) generation of value-added geohazard products providing information on terrain motion and change detection; and (iv) in-situ validation. In addition, a basic SAR image course was given to the URGEO master in Université d’État d’Haiti (UEH). The motivation to focus on SAR data (to complement more consolidated techniques based on optical satellite imagery) was provided by the Haitian partners’ expressed need to approach the domain of SAR remote sensing and interferometry (InSAR) that, on one side, bring well-known advantages for land applications and disaster risk reduction in tropical regions but, on the other, require computing facilities, training and capacity building to be feasibly used as sources of geospatial information.
The RO pilot was successfully completed at the beginning of 2021. A final workshop was held by involving all the space agencies, national champions and users who collaborated to demonstrate the benefits of better integrating information from satellite imagery and their derived products into the post-Matthew reconstruction and recovery process. That event provided the opportunity to reflect collectively on the lessons learnt and the legacy of the RO pilot experience.
The present paper aims to contribute to the key objectives of ESA Living Planet Symposium session D1.05 “International Collaboration to better understand risks using satellite EO (GEO, CEOS, etc.)”, by:
- sharing the technical achievements and challenges in the use of repeated SAR data from high revisit sensors (e.g. Sentinel-1) and on-demand acquisitions from high resolution sensors (e.g. COSMO-SkyMed) for terrain motion and land surface change applications;
- highlighting the role that the collaboration with users and stakeholders can play to add value to SAR-based scientific products.
For the purposes of a wide-area regional analysis, Sentinel-1 data were processed and interferometric products were generated using ESA’s Geohazards Exploitation Platform (GEP) [Cigna et al. 2020]. In particular, we will showcase the value of accessing such infrastructure and its hosted processing routines, discuss the impact of possible external constraints that may limit the exploitation by users (e.g. skill gap, limited internet connectivity), and outline possible actions towards an effective use of this resource (e.g. dedicated training).
In parallel, a bespoke campaign to monitor three priority areas defined by the Haitian users – i.e. Jérémie, Camp Perrin and Carrière Arniquet – was undertaken with ASI’s COSMO-SkyMed constellation using the Enhanced SpotLight mode, at 1-m spatial resolution, 16 days site revisit, in both ascending and descending modes, from December 2017 to December 2020 until the RO completion. These data were used to generate maps that allowed the identification of different categories of surface changes including:
(a) environmental, located along the estuarine section of the Grand’Anse River south of Jérémie and mixed with anthropogenic activities mostly related to quarrying and unregulated waste disposal [De Giorgi et al., 2021];
(b) geological, along the rock cliffs north-west of Jérémie where susceptibility of local lithologies to fracturing, toppling and lateral spreading may be worsened by the impact of hurricanes and storms, thus causing potential risks to small villages and isolated dwellings.
(c) urban, within the outskirts of Jérémie due to reconstruction, as well as new constructions, in areas where the Sentinel-1 InSAR analyses highlighted ground motions;
(d) rural, due to landslides to be distinguished by similar signals associated with agricultural practices along the slopes in the Camp Perrin.
Each of the above categories was validated based on ground-truth data collected during a technical mission that was jointly carried out by ASI, CNIGS, CNES, ICube-SERTIT and Bureau des Mines et de l'Energie d'Haïti (BME). Lessons learnt will be discussed in detail, in order to outline some recommendations on how to effectively integrate a range of SAR observations and products and pave the way for their embedding into the decision making process for recovery and resilience building.
In this regard, the discussion will also encompass the analysis of the feedback received by Haitian stakeholders (e.g. the Civil Protection, mayors of the municipalities affected by the hurricane Matthew, the Comité Interministériel d'Aménagement du Territoire) during the dedicated workshops that were held in Jérémie and Port-au-Prince to present these SAR and InSAR derived products, as well as from the group discussion at the final workshop. Among the feedback:
- the integration between the Sentinel-1 InSAR ground motion products and the COSMO-SkyMed-based urbanization map was positively assessed for purposes of urban planning, as a satellite evidence-base to highlight areas where cascading hazards may be triggered and thus new urbanization is not recommended;
- in light of the proven benefits of InSAR and SAR change detection techniques, there is the need for capacity building not only to transfer knowledge, but also to create a technical capability (also through the involvement of the local university) to exploit the RO pilot technical legacy after the project completion.
- Cigna, F.; Tapete, D.; Danzeglocke, J.; Bally, P.; Cuccu, R.; Papadopoulou, T.; Caumont, H.; Collet, A.; de Boissezon, H.; Eddy, A.; Piard, B.E. Supporting Recovery after 2016 Hurricane Matthew in Haiti With Big SAR Data Processing in the Geohazards Exploitation Platform (GEP). Proceedings of 2020 IEEE International Geoscience and Remote Sensing Symposium (IGARSS), Waikoloa, HI, USA, 26 September–2 October 2020; pp. 6867–6870. https://doi.org/10.1109/IGARSS39084.2020.9323231
- De Giorgi, A.; Solarna, D.; Moser, G.; Tapete, D.; Cigna, F.; Boni, G.; Rudari, R.; Serpico, S.B.; Pisani, A.R.; Montuori, A.; Zoffoli, S. Monitoring the Recovery after 2016 Hurricane Matthew in Haiti via Markovian Multitemporal Region-Based Modeling. Remote Sensing 2021, 13 (17), 3509. https://doi.org/10.3390/rs13173509