Progress of developing flood forecasting system by Today’s Earth (TE)

A flood forecasting system (FFS) is widely recognized as essential to protect people’s lives and prosperities. Developing an FFS with high accuracy, longer lead time, and high resolution is the ideal goal, but there are lots of obstacles to achieving this challenge. Here, we would like to introduce our progress in the development of 5-km resolution FFS system in Japan by Today’s Earth (TE) system (Ma et al., 2021). TE was developed by the collaboration between JAXA and The University of Tokyo and is routinely run at https://www.eorc.jaxa.jp/water/index.html. Among various events, we focus on a case study for forecasting Typhoon Hagibis by assessing its forecasting performance. The results showed that this method was accurate in predicting floods at 130 locations, approximately 91.6% of the total of 142 flooded locations, with a lead time of approximately 32.75 h. In terms of precision, these successfully predicted locations accounted for 24.0% of the total of 542 locations under a flood warning. On average, the predicted flood time was approximately 8.53 h earlier than a given dike-break time. Further, we would like to present our current work for developing an FFS with much higher resolution (1 km), with a probabilistic approach by the ensemble method using NEXRA (NICAM-LETKF JAXA Research Analysis, Kotsuki et al. 2017, https://www.eorc.jaxa.jp/theme/NEXRA/) data, and other developing versions of Today’s Earth system of Global scale (https://www.eorc.jaxa.jp/water/).

 

Ma, W., Ishitsuka, Y., Takeshima, A. et al. (2021). Applicability of a nationwide flood forecasting system for Typhoon Hagibis 2019. Sci Rep 11, 10213. https://doi.org/10.1038/s41598-021-89522-8.

Kotsuki S, Miyoshi T, Terasaki K. Lien GY, Kalnay E (2017) Assimilating the global satellite mapping of precipitation data with the Nonhydrostatic Icosahedral Atmospheric Model (NICAM), J. Geophys. Res. Atmos., 122, 631–650. doi: 10.1002/2016JD025355.