InSAR Monitoring of Landslide Activity in Dominica

Abstract

Dominica is a geologically young, volcanic island in the eastern Caribbean. Due to its rugged terrain, substantial rainfall, and distinct soil characteristics, it is highly vulnerable to landslides. The dominant triggers of these landslides are hurricanes, tropical storms, and heavy prolonged rainfall events. These events frequently lead to loss of life and the need for a growing portion of the island’s annual budget to cover the considerable cost of reconstruction and recovery. For disaster risk mitigation and landslide risk assessment, landslide inventory and susceptibility maps are essential. Landslide inventory maps record existing landslides and include details on their type, location, spatial extent, and time of occurrence. These data are integrated (when possible) with the landslide trigger and pre-failure slope conditions to generate or validate a susceptibility map. The susceptibility map is used to identify the level of potential landslide risk (low, moderate, or high). In Dominica, these maps are produced using optical satellite and aerial images, digital elevation models, and historic landslide inventory data. This study illustrates the benefits of using satellite Interferometric Synthetic Aperture Radar (InSAR) to refine these maps. Our study shows that when using continuous high-resolution InSAR data, active slopes can be identified and monitored. This information can be used to highlight areas most at risk (for use in validating and updating the susceptibility map), and can constrain the time of occurrence of when the landslide was initiated (for use in landslide inventory mapping). Our study shows that InSAR can be used to assist in the investigation of pre-failure slope conditions. For instance, our initial findings suggest there is more land motion prior to failure on clay soils with gentler slopes than on those with steeper slopes. A greater understanding of pre-failure slope conditions will support the generation of a more dependable susceptibility map. Our study also discusses the integration of InSAR deformation-rate maps and time-series analysis with rainfall data in support of the development of rainfall thresholds for different terrains. The information provided by InSAR can enhance inventory and susceptibility mapping, which will better assist with the island’s current disaster mitigation and resiliency efforts.

Hurricanes alter 10Be concentrations in tropical river sediment but do not change regional erosion rate estimates

“…Wind gusts peaked at 77 m s À1 and total satellite-estimated precipitation reached 700 mm over 30 h (TRMM, 2011); although, given the coarse (0.25 ) resolution of the dataset (Smith et al, 2009(Smith et al, , 2012, actual rainfall may have been higher on the wetter, eastern side of the island and in the mountains. These are slightly higher rainfall amounts over a longer period of time than the total recorded for Erika of 500 mm in 10 h (Fobert et al, 2021).…”

“…Wind gusts peaked at 77 m s −1 and total satellite‐estimated precipitation reached 700 mm over 30 h (TRMM, 2011); although, given the coarse (0.25°) resolution of the dataset (Smith et al, 2009, 2012), actual rainfall may have been higher on the wetter, eastern side of the island and in the mountains. These are slightly higher rainfall amounts over a longer period of time than the total recorded for Erika of 500 mm in 10 h (Fobert et al, 2021). The effects of the storm included vegetation loss (Hu & Smith, 2018) (Figures 2g and h), flooding (Heidarzadeh et al, 2018), channel bank erosion, and mass movements on ~1.3% of the island (van Westen et al, 2018).…”

“…Mass movements are primarily associated with high rainfall rates and thus are strongly correlated with tropical cyclones (van Westen, 2016). Mass movements are concentrated in clay-rich soils and are relatively stable during the dry season and reactivate in the wet season each year (Fobert et al, 2021).…”

Geomorphological transformations and future deformation estimations of a large potential landslide in the high-order position area of Diexi, China

“…InSAR technology can also approximate the time at which landslides began. 41 . In particular, it can detect surface changes at the millimeter scale 42 , and therefor compute surface deformation prior to landslides according to previous records.…”

Unified landslide hazard assessment using hurdle models: a case study in the Island of Dominica

“…In this paper, we focus on the aftermath of hurricane Maria, which originated from a wave leaving the west coast of Africa on 12th September 2017. The wave moved westward across the Atlantic, creating deep convection, and consolidated into a tropical depression 580 nautical miles east of Barbados on the 16th September (Pasch et al 2018;Fobert et al 2021). By the evening of the 18th, Maria had intensified and hit the Island of Dominica twelve hours later as a category five hurricane (Pasch et al 2018), causing a total of 9960 landslides on the island, 8,576 of which were classified as debris slides (Van Westen and Zhang 2018).…”