Notice on the Termination of GFAS Operations

The Global Flood Alert System (GFAS) was developed to provide early and easy-to-understand flood warning information, even in developing countries with insufficient hydrological observation infrastructure. The system utilizes satellite-based rainfall data to assess rainfall probability on a global grid of approximately 10 km², with results visualized on maps using a five-level color-coded scale.

Since its launch in 2003, GFAS has undergone several enhancements, including the release of a public website in 2006, a major system upgrade to “GFAS II” in 2015, and a further refinement with “GFAS II ver2.2” in 2020. These continuous improvements have been carried out for more than 20 years.

However, despite these efforts, GFAS has not yet achieved a level of accuracy sufficient for practical use as an early warning system, and prospects for reaching such a level remain uncertain. Meanwhile, technologies for rainfall observation using satellites and weather radar have advanced significantly, leading to the practical implementation and partial adoption of early warning systems that combine such data with runoff analysis models.

In light of these developments, we have decided to terminate the operation of GFAS as of July 2025.

We would like to express our sincere gratitude to all those who have used and supported GFAS over the years, and we kindly ask for your understanding regarding the termination of its operation.

About GFAS

Global Flood Alert System Ver.2.2 (GFAS-II) produced by IDI-Japan made it possible to display the area of observed rainfall and the *1) probable maximum precipitation (PMP) at designated time with an interval of one hour in visually intelligible form, classifying the data by 5 ranked different probabilities in a 10km Mesh Global Atmospheric Model, using GSMaP rainfall data provided by JAXA.

Thereby, GFAS-II is capable of displaying the probable maximum precipitation as flood risk index by using near real-time rainfall data obtained within as little as 1 hour. The display range of those data covers most of all countries and regions in the world.

In the revised version of GFASⅡ released in June, 2020, area coverage partially expanded in the areas of Europe, Africa and America by the expansion of GSMaP coverage. Furthermore, it became possible to display the past precipitation and probable maximum precipitation data with ranked categories, going back to a certain day within one-year.

*1) The theoretically greatest depth of precipitation for a given duration that is physically possible over a particular drainage area at a certain time of year; in practice, this is derived over flat terrain by storm transposition and moisture adjustment to observed storm patterns. Source:“https://encyclopedia2.thefreedictionary.com/probable+maximum+precipitation”

URL for GFASⅡ Revised Version（ver.2.2） is shown below（since June, 2020）
　http://gfas.internationalfloodnetwork.org/n-gfas-web/pc/　 (for PC)
　http://gfas.internationalfloodnetwork.org/n-gfas-web/sp/　 (for Smartphone)

Inquiries

If you have any questions, please send an e-mail to the following address:

Infrastructure Development Institute（IDI-Japan）
e-mail: info@internationalfloodnetwork.org

Links