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09.20.2019

In the Wake of Dorian: Maxar’s GeoHIVE Damage Assessment and the State of the Bahamas

By: Jillian Jarrett, GeoHIVE Software Developer and Jenny Roberts, GeoHIVE Crowd Coordinator, Maxar Technologies


Read Time: 6 minutes

Hurricane Dorian made landfall on September 1, 2019, in the Bahamas as a Category five storm, with wind speeds up to 185 mph and extremely slow tracking speeds as low as one mph. It was the strongest storm to strike the Bahamas in recorded history. As the devastating cyclone crawled across the country, the world watched and waited with bated breath to see the extent of the damage.

GeoHIVE (Geospatial Human Imagery Verification Effort), Maxar’s crowdsourcing platform that allows users to discover and verify features of interest in Maxar’s high-resolution satellite imagery to provide insight on even the most complex questions, is primed to provide rapid-response damage assessments during natural disasters, as soon as new satellite imagery is available. It utilizes the collective intelligence of a verified crowd and a team of developers and geospatial analysts to provide fast and accurate assessments of areas affected by such tragedies. When Dorian was first classified as a tropical storm, the GeoHIVE team monitored its progression toward the Bahamas and its estimated area of landfall.

Dorian’s Destruction

Pre-event satellite imagery comes from Maxar’s Vivid imagery mosaic and post-event satellite imagery is sourced from Maxar’s GeoEye-1 satellite. To test out the damage assessment slider-bar feature of GeoHIVE, please visit our demo.

Before the storm reached the Bahamas, GeoHIVE collected pre-event imagery from Maxar’s Vivid imagery mosaic and overlaid OpenStreetMap (OSM) building footprints in preparation of a damage assessment campaign. As soon as the storm cleared and Maxar high-resolution satellite imagery of the islands was available, the team finalized the campaign and sent it to the crowd. In one hour and 12 minutes, 36 GeoHIVE users assessed 3,009 buildings in Abaco’s Marsh Harbor and on Green Turtle Cay. Members compared pre-event imagery and post-event imagery utilizing GeoHIVE’s slider-bar feature to determine accurately the level of damage within each OSM building footprint —each building was viewed by six unique users to ensure accurate assessments. Of the buildings assessed, only 15% had no visible damage while 47% were visibly damaged and 38% were visibly destroyed. This damage assessment data is available for open, non-commercial use through Maxar’s Open Data Program and has informed responses on-the-ground by groups like the United Nations.

Damage assessment of Abaco and Green Turtle Cay. Building footprints provided by OSM, Maxar satellite imagery.

Analyzing the Destruction

As of September 16, 2019, the Bahamian government reported the death toll in the Bahamas was at 50 and rising, while 1,300 were still missing as rescue crews continue to search through the debris and eroded landscape for survivors. Of those who survived and are accounted for, 70,000 are now homeless and in need of assistance. The situation is increasingly dire as the potential for other storms to strike the Bahamas looms with the 2019 hurricane season in full force.

To understand the true nature of the desolation left by Dorian, there are several factors to consider. First, Dorian itself was catastrophic due to its speed and strength. With its exceedingly low tracking speed, the storm only traveled 25 miles in 24 hours, which was the shortest distance traveled by a hurricane in a 24-hour period in 54 years. The duration and strong winds led to a more sustained violent atmosphere that pummeled Bahamian infrastructure and landscape for hours on end, causing significant damage, destruction and erosion.

Second, a significant portion of the Bahamas’ low-income population lives in shantytowns, especially migrants from Haiti. The residential buildings in these shantytowns are often poorly constructed and lack adequate resources, such as water lines, plumbing and electricity. Many of these homes are powered by generators and are unhygienic due to poor sanitation and waste management, putting them at higher risk of fire and structural damage. In 2018, the Bahamian Ministry of Labor identified 915 shantytown residential structures on Abaco, with a majority of residents located in The Mudd and Peas shantytowns in Marsh Harbour. Human rights groups criticized the shantytowns, which led the Bahamian government to distribute eviction notices in 2018. However, due to higher living costs in Abaco, many of the shantytown residents were unable to move locations, forcing them to stay in homes that provided inadequate shelter against Dorian’s wrath.

Pre-event imagery from Maxar’s GeoEye-1 satellite (left image) of The Mudd and Peas shantytowns, where 70% of Abaco’s shantytown residents live. The graphic on the right calls out destroyed buildings (red), partially damaged buildings (orange) and intact buildings (green).

Finally, due to logging operations that lasted throughout a majority of the 20th century, there was a significant reduction of the Bahamian Pine population. These trees are important due to their ability to form windbreaks and prevent erosion during major storms. While wide-scale logging efforts ended in the 1970s and laws were established to protect them, the trees are still at risk. Many shantytowns have economies that rely on charcoal production and the Bahamian government has reported on the illegal harvesting of the Bahamian Pines for production, although it is in direct violation of the Forestry Act. With the continued thinning of these trees, the Bahamas lacked a natural defense against Hurricane Dorian.

These three factors—the storm, poor infrastructure in lower income areas and clearing of critical pine trees—contributed to the damage left in the wake of Dorian. If the infrastructure and deforestation are not addressed, the Bahamas risk the same fate in future storms.

A Facebook post from Hope Town Volunteer Fire & Rescue in Abaco, Bahamas described what it was like to ride out the storm.


Moving Forward

While the Bahamas work to recover from the destruction that Hurricane Dorian caused, Maxar is working to help in any way we can in accordance with our purpose, For a Better World. It is our goal to help those affected by this tragedy and future tragedies in any way we can, including GeoHIVE campaigns, releasing open geospatial data through the Maxar Open Data Program and internal fundraisers for our Purpose partner, Team Rubicon. Our goal is to make this world a better place and that starts with helping our neighbors.

If you want to learn more about GeoHIVE and help in future campaigns, please visit https://geohive.digitalglobe.comfor more information.

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