Water Stage Prediction Using the Coupled Hydraulic and Hydrologic Model and Data Assimilation (PAP014392)

Código

PAP014392

Autores

Yeonsu Kim, Yasuto Tachikawa, Sunmin Kim, Michiharu Shiiba, Seong Jin Noh

Tema

Flood forecasting and early warning systems

Resumo

It is essential to identify the uncertainty in two factors, model parameters and observation data, for a successful flood forecasting. They affect to other various factors during flood forecasting, which are generally utilizing a hydrologic and a hydraulic model. In many cases, deterministic parameter set and deterministically observed data are utilized in the forecasting models, and the uncertainties of those factors are not considered carefully. Careful combination of model and parameters as well as adopting a sophisticated data assimilation scheme should be consider to avoid unidentified uncertainty in the flood forecasting and improve the accuracy of it. Therefore, we are proposing a comprehensive forecasting system with a coupled hydraulic and hydrologic model with the particle filtering scheme. For the sakes of the connection between a hydrologic and hydraulic model, observation uncertainties included in a rating curve are considered, when the curve is adopted for the hydrologic model calibration and the boundary setting for a hydraulic model. It was evaluated in our previous study to establish a rating curve using a 2D dynamic wave model and particle filters. Based on the analysis of uncertainties of the rating curve, the uncertainties of hydrologic parameters are improved by the sequential update of the water stage at the gauging stations. Moreover, the ensemble discharge predicted by a hydrologic model considering the uncertainties of parameters serve as boundary conditions of a hydraulic model for the water stage prediction. In comparison with an existing method for flood forecasting, the proposed method is able to provide the sequentially updated information about flood stage and to consider the uncertainties included in the rating curve by the coupled system. The proposed method is applied to the areas prone to floods within the Katsura River located in Kyoto, Japan.