Author(s): Koji Sassa; Hiroshi Cho; Yu Sato
Linked Author(s):
Keywords: Flood prediction; Water level; Radar observation
Abstract: The risk of river floods becomes more and more serious in the world due to global warming. Therefore, water level prediction in river systems is crucial for flood management and evacuation planning. Its conventional prediction uses pointwise data of rain gauges. On the other hand, weather radars can observe the precipitation all over the river basins. The present work aims to propose new prediction method for river water level and to investigate the validity of the method. In this study, the Kosui River in Kochi City in Japan is selected as the test field. Heavy rain events frequently cause floods in this area. We always observe precipitating clouds with our own X-band polarimetric weather radar network. A prediction equation is derived by assuming a linear relationship between the initial water level and the change in the water level due to rain and drain. The change in the water level is estimated from the information of the radar estimated precipitation and the drainage capacity of the river. In practice, the test field is divided into small grids. The radar estimated precipitation is calculated at each small grid and considering the infiltration rate into soils and the traveling time to the water level gauge from each grid. For validation, the method is applied to predict the water level at specified location for three heavy rainstorm events. The results show that our method can almost predict the water level except for the slight delay of peak values.
Year: 2024