Landslide and flash flood event timing from sentinel 1 SAR - western branch of the East African Rift

Activity: Talk or presentationTalk or presentation at a conference

Description

Geomorphic hazards such as landslides and flash floods (hereafter called GH) often result from a combination of complex interacting physical and anthropogenic processes across multiple spatial and temporal scales. In many instances, GH occur very quickly, sometimes in a matter of a few hours occasionally leading to catastrophic impact on human lives. The tropics are environments where GH are under-researched, while GH disproportionately impact these regions. In addition, GH frequency and/or risks in the tropics are expected to increase in the future in response to increasing demographic pressure, climate change and land use/cover changes. To understand the role of climate and landscape in controlling the spatio-temporal distribution of GH in the context of environmental change, establishing a regional-scale inventory of GH events that are localized accurately in space and time is essential. In this study we focus on the accurate detection of GH timing using remote sensing. The tropics are frequently cloud-covered and an accurate characterization of the timing of GH at a regional scale can only be achieved through the use of Synthetic Aperture Radar (SAR) due to its cloud penetrating capabilities. Here we present the methodology and results of our research on the use of SAR to accurately estimate the timing of GH events with a multi-temporal change analysis approach. The method is applied on several larger GH events in the western branch of the East African Rift located in tropical Africa. Copernicus Sentinel 1 (SAR) is the key satellite product used, which next to being open access, offers a very good trade-off between frequency of acquisition and spatial resolution. The results show that SAR can provide valuable information for event timing detection. Estimated event timing from SAR time series ranges from a couple of days to a maximum of 2,5 months difference. This research is one of the first to show the capabilities of SAR to constrain the timing of GH events with an accuracy much higher than what can be obtained from optical imagery in cloud-covered environments. These methodological results have the potential to be implemented in cloud-based computing platforms to help improve GH detection tools at regional scales, and help to establish unprecedented GH inventories in changing environments such as the East African Rift.
Period15 Dec 2021
Event titleAGU Fall Meeting 2021
Event typeConference
LocationNew Orleans, United States, Louisiana
Degree of RecognitionInternational