Joel Rhine’s breakthrough solution for national-scale flood analysis with Sentinel-1 data

When faced with technical constraints in data processing, Joel Rhine, a former World Bank consultant, created an innovative solution that has been able to optimise flood risk analysis on a national scale. Joel’s application, which he has named the DE Africa Mosaic Builder, overcomes the space limitations of Digital Earth Africa’s (DEA) sandbox environment.  The DEA Mosaic Builder which harnesses Sentinel-1 data to conduct large-scale flood mapping efficiently has streamlined the analysis process and significantly reduced processing times. 

The Challenge: Overcoming technical constraints 
Joel’s initial work began in the DEA Sandbox environment, which offers a valuable and accessible platform for Earth observation analysis. However, for his national-scale flood risk mapping in Chad and Niger, the size of the datasets eventually exceeded the sandbox’s default processing capacity. To accommodate these larger requirements, he explored additional approaches that could complement the sandbox and support more intensive analysis. 

Leveraging Google Drive API for data scalability 
As a work around, Joel experimented in Google Drive to manage the large requisite datasets. By improving the existing Google Drive upload code, he bypassed the 15GB service account limit. This solution allowed for analysis across multiple countries and ensured the project’s scalability. Joel says, “The key was using Google Drive’s Desktop App API, which facilitated potentially unlimited storage for flood risk mapping analysis. This method proved to be faster and more efficient, reducing processing times from 10 days (depending on area of interest) to just a few hours.” 

Flood risk mapping 
The software developed by Joel’s team was used to analyse flood expanse in Chad and Niger, using Sentinel-1 satellite data to compare pre- and post-flood conditions.  This analysis provided valuable insights into infrastructure damage and economic losses caused by floods, supporting efforts in disaster risk management and planning. The tool demonstrated its potential not only in analysing flood risk but also in creating reproducible, scalable workflows for large-scale analysis. 

Scaling the solution  
Joel’s application has far-reaching implications. By combining cloud storage with flexible data handling capabilities, the Mosaic Builder adds a complimentary layer to Digital Earth Africa’s datasets, bypassing the computational limitations of the sandbox environment to affect less time-intensive national-scale analyses. This development aligns with the broader goal of making flood risk data accessible for a wide range of stakeholders, from governments to researchers. With detailed documentation, Joel has ensured that others can replicate and expand on his work, helping to foster a collaborative and user-driven approach to flood risk mapping. 

A model for future innovation 
Joel’s work with the DEA Mosaic Builder showcases how users can extend the value of Digital Earth Africa’s datasets beyond the sandbox environment. While the sandbox is a powerful and accessible entry point for many users, Joel’s approach demonstrates how external tools and platforms can be leveraged to scale analysis for national-level applications. His innovation not only addresses specific technical challenges but also opens doors for applying DEA data across sectors like agriculture, urban planning, and disaster management  

By streamlining the use of Sentinel-1 data, Joel has paved the way for a new era of accessible, user-driven satellite data solutions that push the boundaries of what’s possible.