[AOS21-P01] Incorporation of sea level variation into a global river routing model and its impact assessment
Keywords:Fluvial flooding, Storm surge, Global river routing model, Global reanalysis of tide and surge
The objective of this study is to elucidate the influence of sea level variation on fluvial flooding by employing a global river ruoting model capable of appropriately expressing the backwater effect, and a global reanalysis of tide and surge that was developed in recent years. First, we modified the river routing model to express sea level variation. Next, we developed a scheme for delivering sea level data from a global reanalysis of tide and surge to the global river routing model, conducted coupled simulation, and evaluated the influence.
Coupled simulation on the global scale revealed that river water levels increased by 0.5 m or more in comparison with the case without considering sea level variation. We found that the sea level fluctuation significantly affected fluvial flood simualtions. Time series of river water levels was analysed for large rivers with catchment areas larger than 160,000 km2 in the Asian region. As a result, peak water levels increased by 1 m or more in some rivers, and the seasonal variation of river water levels were enhanced in others. In sum, it was clarified that sea level variation had a meaningful impact on fluvial flood simulations.