Author(s): Tetsuaki Mikami; Shoji Fukuoka; Akihide Watanabe
Linked Author(s): Shoji Fukuoka
Keywords: Water surface profiles; Water level prediction; Propagation characteristics of flood flow; Assimilation analysis; Adjoint method
Abstract: Providing accurate water level forecasts is important to ensure the timely evacuation of residents put at risk by a levee overflow or breach. The purpose of this study is to clarify the propagation characteristics of flood flow in Japan’s Tone River and to predict several hours ahead the water level downstream. To this end, we developed a real-time assimilation model with two-dimensional planar flow analysis to determine the temporal change in the water level observed over a long section of the river. Based on the hydraulic quantities obtained from the assimilation analysis, the continuity equation is analyzed using the characteristic curve method, and the propagation time of the flood flow to the downstream prediction section is produced. Results show that the water level propagation time is 3 to 5 hours during the rising phase and 2.5 hours at peak. Water levels are then predicted based on the lead time (i.e., propagation time). The predicted water levels are shown to closely approximate the levels, demonstrating the utility of the method for water level prediction.
Year: 2020