Proposal of Digital Twin Technology for Visualizing Flood Inundation in Cities with Underground Spaces

Abstract

This research aims to create content that visualizes the inundation status of cities with underground spaces using digital twin technology, based on hydrologically objective flood calculations, in order to promote the personalization of flood risks and encourage voluntary early evacuation. In Japan, flood disasters are intensifying due to climate change, and the inundation of underground spaces—which are particularly vulnerable to flooding—can lead to human casualties and the paralysis of urban functions. This study focused on the left bank of the middle reaches of the Toyohira River, which flows through the urban area of Sapporo, Hokkaido, where underground spaces are located. A digital twin was developed by integrating flood simulations with a 3D virtual space constructed using Fundamental Geospatial Data and PLATEAU. For the flood calculations, iRIC Nays2DFlood was utilized to estimate surface inundation depths in Sapporo, assuming a levee breach based on the maximum discharge for the present climate derived from d4PDF. Furthermore, the resulting inflow volume into underground spaces was estimated and visualized using generative AI.