JpGU-AGU Joint Meeting 2017

Presentation information

[JJ] Poster

A (Atmospheric and Hydrospheric Sciences) » A-OS Ocean Sciences & Ocean Environment

[A-OS21] [JJ] The dynamics of freshwater discharge - rivers, estuaries, and along coasts

Mon. May 22, 2017 3:30 PM - 5:00 PM Poster Hall (International Exhibition Hall HALL7)

convener:Shinichiro Kida(Research Institute for Applied Mechanics, Kyushu University), Dai Yamazaki(JAMSTEC - Japan Agency for Marine-Earth Science and Technology), Yoshimasa Matsumura(Atmosphere and Ocean Research Institute, University of Tokyo), Yosuke Yamashiki(Global Water Resources Assessment Laboratory - Yamashiki Laboratory Graduate School of Advanced Integrated Studies in Human Survivability Kyoto University)

[AOS21-P01] Incorporation of sea level variation into a global river routing model and its impact assessment

★Invited papers

Hiroaki Ikeuchi1, Yukiko Hirabayashi1, *Dai Yamazaki2 (1.Graduate Schoolf of Engineering, the Universiy of Tokyo, 2.Japan Agency for Marine-Earth Science and Technology)

Keywords:Fluvial flooding, Storm surge, Global river routing model, Global reanalysis of tide and surge

Global river routing models have been applied to river flood risk assessment such as in regions with poor data of topography observation, and global mapping of flood inundated areas and its interregional comparisons. In these years they have been developed in various research institutions around the world. However, since previous studies mainly focused on flood risk assessment in land areas, sea level variations have not been taken into consideration, and fluvial flood simulations in areas vulnerable to tides and storm surges have been underestimated.
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.