With the aim of accurately predicting river water levels a few hours ahead in the event of a flood, we created a river water level prediction model consisting of a runoff model, a channel model, and data assimilation technique. We also developed a cascade assimilation method that allows us to calculate assimilations of water levels observed at multiple points using particle filters in real-time. As a result of applying the river water level prediction model to Arakawa Basin using the assimilation technique, it was confirmed that reproductive simulations that produce results very similar to the observed results could be achieved, and that we would be able to predict river water levels less affected by the predicted amount of rainfall.

1. [1] “IPCC 4th Assessment Report,” Working Group 2, 2007.
2. [2] Ministry of Land, Infrastructure, Transport and Tourism, http://www.mlit.go.jp/river/shinngikai_blog/shaseishin/kasenbunkakai/shouiinkai/daikibohanran/index.html (in Japanese) [accessed December 11, 2015]
3. [3] Cross-ministerial Strategic Innovation Promotion Program, “Enhancement of Societal Resiliency against Natural Disasters,” Prediction System of Local Heavy rain and Tornado, https://www8.cao.go.jp/cstp/gaiyo/sip/index.html (in Japanese) [accessed May 23, 2014]
4. [4] R. Tsubaki, K. Kobayashi, M. Naito, and S. Taniguchi, “On the Flood Prediction, Present State and Matters to Resolve,” Advanced in River Engineering, Vol.19, pp. 1-6, 2013 (in Japanese).
5. [5] S. Tsuchiya and M. Kawasaki, “Development of Technology for Longitudinal Water-level Estimation and Prediction for Flood Risk Visualization,” Civil Engineering J., Vol.59, No.12, pp. 14-17, 2017 (in Japanese).
6. [6] S. Tsuchiya, M. Kawasaki, K. Fukami, S. Nemoto, M. Naito, and H. Godo, “Trends of Progress and Application of Radar Rainfall Information for the Advancement of Rainfall and Flood Forecasting Technology,” Advanced in River Engineering, Vol.20, pp. 343-348, 2014 (in Japanese).
7. [7] Y. Tachikawa, J. Sudo, M. Shiiba, K. Yorozu, and S. Kim, “Development of A Real-Time River Stage Forecasting Method Using a Particle Filter,” J. of Japan Society of Civil Engineers, Ser.B1, Vol.67, No.4, pp. I_511-I_516, 2011.