C104

Numerical Modeling of Flood Disaster in Kyoto's Cultural Heritage
Considering Architectural Form Characteristics〇Xi CHEN, Kenji KAWAIKE, Kazuki YAMANOI, Takahiro KOSHIBA

1. Introduction

heritage disaster prevention particularly significant in

The number of disasters occurring globally has been

this area. This research focuses on the Katsura Rikyū,

steadily increasing (UNISDR, 2009). Traditional

internationally renowned for its Japanese garden design

research on natural disasters has focused on hazards

and representation of Japanese aesthetics, holding

mechanisms and their impacts on societal infrastructure,

substantial historical value. Situated adjacent to thehuman lives and properties. However, the consideration

Katsuragawa, the Katsura Rikyū has faced multipleof cultural heritage has often been overlooked.

instances of flooding over its centuries-long existence,

Meanwhile, cultural heritage managers and decision-

with the flood in 1721 leaving imprints on the interiormakers tend to concentrate on heritage preservation,walls of the Shōkin-tei pavilion within the garden (桂restoration, fire prevention, and aging mitigation, but

宮 日 記 ). Additionally, the Katsuragawa has

not the impact of natural disaster on heritage. Current

experienced numerous floods, and although there arelimited research predominantly centers on large-scale

no official records of heritage damage, it is speculated

risk assessments, neglecting in-depth studies on thethat the Katsura Rikyū may be susceptible to flooding

specific characteristics of individual hazards. There(Kawasaki, 2013).

remains a notable gap in interdisciplinary research on
cultural heritage disaster prevention.

The author has collected data from the Geospatial
Information Authority of Japan (GSI) maps andThis study is grounded in the interdisciplinary field

relevant literature, comparing and refining the overallof cultural heritage and flood disaster research, aiming

map to accurately depict the architectural layout andto address the inadequacies in the current research ofdetailed dimensions of the Katsura Rikyū forcultural heritage for flood disasters. The research seeks

subsequent numerical simulations.

to elucidate the anticipated external forces and scales ofThis study employs 2D inundation model (Kawaike,flood faced by cultural heritage. Recognizing the2002) to investigate flood scenarios. This modelsignificant

providesdifferences

betweenhistoricalandcomprehensive

representations

ofthecontemporary buildings, the study strives to reasonably

temporal evolution of floods in urban areas. The

incorporate architectural features influencing flood

distinguishing features of historical buildings, indistribution into the numerical model. In this paper,

contrast to modern structures, include overhanging

cultural heritage primarily refers to immovable cultural

eaves, high floor structure, and surrounding walls.

assets, such as structures, gardens, monuments, and so

These three architectural features directly influence theon.

distribution of floodwaters (Fig.1). In this research,

2. Materials and Methods

these characteristics are integrated into the numerical

Kyoto City has a rich historical heritage andabundant resources, making the study of culturalmodel to accurately simulate their impact on flood
distribution.

Regarding walls, the representation involved gaps
between solid walls. Calculations were carried out withdifferent gap ratios, and the DEM was elevated by 3meters. The results indicate that regardless of frequency,
if there are gaps in the walls, the final state of flood
distribution is generally the same. However, in the earlystages of flooding (Fig. 5), the flood spreading area andFig. 1 Research Diagram of Three Characteristics

3. Results and Discussions

speed vary. Examining the flooding situation at 600
seconds, it can be observed that the lower the gap ratios,

The study begins with a comprehensive diagram tovalidate the research methodology for three features. It

the lower the average water depth within the walls
during the initial stages of flooding.

is assumed that the area under investigation includes
roads, buildings, and walls (Fig. 2).

Fig.5 Flood at 600s with ratio of 2:1, 8:1, 26:1

Quantifying these three features for the simulation of
the Katsura Rikyū, assuming a closed boundary andspecifying breach points, yields two-dimensional
Left Fig. 2 Assumed Study Subject

numerical simulation results at the architectural level

Right Fig. 3 Comparison of Water Depth(Fig.6). These results contain inundation depth, extent,

Concerning eaves, calculations were did using roof

flow velocity, direction at different time intervals.

outline and exterior wall outline. Graph is representedby light and dark blue lines separately (Fig.3). The
results indicate that areas with deeper water depths are
more extensive when using roof outline.
Regarding high floor structure, the method ofincreasing DEM values was used. Calculations wereconducted for both non-elevated buildings andFig. 8: Flood distribution of Katsura Rikyūbuildings elevated by 1 meter (Fig.4). The results

References:indicate that the simulation with elevated buildings

1) 川池, 健司. 都市における氾濫解析法とその耐demonstrates a noticeable effect, effectively capturing

水性評価への応用に関する研究. 京都大学, 2002,the characteristic.

博士(工学)
2) 川崎一朗, 岡田篤正, 諏訪浩, 等. 桂離宮とその 周 辺 の 水 害 リ ス ク [J]. 京 都 歴 史 災 害 研 究 ,2013(14): 53-62.
3) 桂宮日記.宮内庁書陵部蔵4) 二川, et al. 天上の庭: 京都御所・仙洞御所・修学院離宮・桂離宮.

Fig.4 Left Original DEM

Right Higher DEM (1m)5) 渡辺祐蔵. 京の離宮: 桂離宮・修学院離宮.1983