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Synchronised Collections of SAR and VHR Optical Satellite Imagery Revolutionise Flood Management

As climate change accelerates, the frequency and severity of flooding events are becoming  increasingly alarming. In response, innovative tools like DoubleShot, developed by European Space  Imaging in partnership with Umbra, are transforming flood management strategies. By combining the  power of Very High Resolution (VHR) Synthetic Aperture Radar (SAR) and Optical satellite imagery,  DoubleShot delivers a comprehensive, weather-independent solution for near real-time flood  mapping and monitoring. 

Satellite image © 2024 Maxar Technologies Provided by European Space Imaging

The Rising Tide of Climate Change 

Extreme precipitation, rising sea levels, higher river flow… These are all results of climate change,  leading to an increased risk of flooding across Europe. According to the International Disaster Database,  in 2023 alone, flooding affected 1.6 million people in Europe and caused around 81% of the year’s  economic losses due to weather and climate-related events on the continent. Only a year later, heavy  flooding in September 2024 caused multiple casualties and resulted in 25–65 years loss for insurers in  Czechia, Poland and Austria. With many regions experiencing more frequent and intense flooding  events, it is now more important than ever to invest in flood preparedness and response solutions.

SAR and Optical Satellite Images in Tandem   

The most recent product available is DoubleShot – synchronised collections of 30 cm VHR Optical  imagery and 25 cm SAR imagery. How does it work? The collection team at European Space Imaging  (EUSI) analyses the orbits of Umbra (SAR) and Maxar WorldView (Optical) satellite constellations and  matches collection times so that customers receive both optical and SAR imagery collected over their  target area only a few minutes apart. This solution brings the benefits of both active and passive  sensors, and combines them to provide maximum effectivity.   

While VHR Optical imagery at 15 cm HD or 30–50 cm native resolution shows details like cars, people,  road features or debris next to buildings, it is often obstructed by cloud cover during flood events. The  missing data can be filled in from delivered SAR imagery.    

Unlike passive (optical) sensors, which measure surface reflectance and are therefore dependent on  sunlight and good weather conditions, active sensors used in SAR technology provide their own source  of energy and then record the energy backscattered at the sensor. Thanks to that, SAR can provide  insights regardless of cloud cover. This makes it the perfect complement to optical imagery in the case  of flooding. 

Optical image © 2024 Maxar Technologies Provided by European Space Imaging | SAR image © 2024 Umbra Provided by European Space Imaging
Optical image © 2024 Maxar Technologies Provided by European Space Imaging | SAR image © 2024 Umbra Provided by European Space Imaging

Near Real-Time Monitoring: From Space to Action 

 For emergency situations, Near Real-Time delivery is possible: up to 15 minutes after collection for  optical satellite imagery and up to one hour for SAR. Without losing precious time, relief organisations  can rapidly answer questions such as: 

  • What is the extent of flooding? 
  • How many disaster responders are needed in each area?  
  • Which evacuation routes are currently obstructed?  
  • How many people need to be evacuated?  
  • What is the status of critical infrastructure? 
  • Is there a hazardous material spill that needs to be contained?  
  • Are there any disruptions to water supply systems?  
  • Were power lines damaged?  

And many more.  

Case Study: Floods in Southern Germany 

The combined tasking of very high resolution SAR and Optical imagery has already proven crucial in  several emergency response and persistent monitoring applications. For example in June 2024,  Southern Germany was hit by floods and due to persistent cloud cover following the event, no usable  optical satellite imagery could be collected. EUSI therefore worked closely with the DLR-ZKI (Centre for  Satellite Based Crisis Information at the German Aerospace Centre) to rapidly collect and deliver both  optical and SAR satellite images of the flooding. 

Analysts from the IFAS (Indicator Monitoring for Early Acquisition of Innovative Satellite Sensors in  Natural Disasters) project received the imagery and created maps detailing flooded areas – thanks to  the high resolution of the radar imagery, the flooded areas could be easily distinguished as the water  had distinct reflections compared to surrounding dry land. The results were immediately made  available to authorities and relief organisations such as the Bavarian Red Cross (BRK) and the German  Federal Agency for Technical Relief (THW). 

Map © DLR/ZKI 2024 | SAR image © 2024 Umbra provided by European Space Imaging

Empowering Regions Against Rising Waters 

In the face of escalating climate change impacts, these innovative solutions are crucial for effective  flood management. By merging very high-resolution SAR and Optical satellite imagery, DoubleShot  offers rapid, weather-independent insights into flooding, enabling emergency responders to make  informed decisions that save lives and property. Contact European Space Imaging to discover how  DoubleShot can transform your flood management strategy.