Case Study: Laos

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Space technology that aids in rapid flood assessment

On July 23, 2018 the Xe Namnoy Xe Pian Dam in the Attapeu province of Laos (Lao People’s Democratic Republic) collapsed, flooding nearby villages, leaving thousands of people homeless and affecting public and private infrastructure, such as buildings and roads. In response to this disaster, a coordinated inter-governmental agency effort produced timely disaster aid by imaging the extent of the flooding.

This effort utilized state-of-the-art space assets—the Synthetic Aperture Radar (SAR) sensors that were used on board ESA’s Sentinel-1A and JAXA’s ALOS-2 missions. Leveraging the unique capabilities of space technology, SAR sensors provided clear imagery of the aftermath by penetrating clouds and providing an improved assessment.

Perry Oddo, a researcher affiliated with the Earth from Space Institute performed a rapid impact analysis to assess the possible socio-economic impacts of the flooding.  In coordination with NASA colleagues - estimates of flood inundation depths were overlaid onto local land cover, population density, and infrastructure data to produce provisional estimates of persons affected and flood damages (see image below).

Disaster response materials, including flood maps and early impact assessments, were delivered to the Laos Department of Labor and Social Welfare through regional partner, Asian Disaster Preparedness Center (ADPC).

The methodology used during this event has the potential to improve emergency response operations in the hours immediately following a disaster. The resulting ‘heatmap’ of potential impacts can be used to identify areas that may be hardest hit, and can inform flood responders about how to prioritize additional relief. Work is currently underway to expand this analysis to other parts of the globe to ensure it can be deployed operationally whenever disaster strikes.

Rapid Impact Assessment performed for the July 2018 dam collapse

The left insets show flood extent, inundation depth estimates, and infrastructure inputs that were used in the rapid impact assessment. The right shows a ‘heat map’ of provisional damages representing areas that may be most highly impacted from the event.

References & Resources

Oddo, P. C., Ahamed, A., & Bolten, J. D. (2018). Socioeconomic Impact Evaluation for Near Real-Time Flood Detection in the Lower Mekong River Basin. Hydrology, 5(2), 23.