TY - JOUR
T1 - Assessment of flood risk management in lowland Tokyo areas in the seventeenth century by numerical flow simulations
AU - Ishikawa, Tadaharu
AU - Akoh, Ryosuke
N1 - Funding Information:
We would like to thank Emeritus Professor Hideo Kikkawa of the Tokyo Institute of Technology for his valuable suggestions pertaining to this study. We would also like to thank the Arakawa-Karyu River Office and the Tokyo Metropolitan Government Bureau of Construction for providing field survey data for this study. This study was supported by a Grant from the River Foundation (No. 27-1212-006).
Publisher Copyright:
© 2018, Springer Nature B.V.
PY - 2019/10/1
Y1 - 2019/10/1
N2 - Numerical simulations using the shallow water model on an unstructured triangular mesh system were conducted to elucidate the hydraulic functions of the Nihon levee system, which was built in the seventeenth century to protect the city of Edo (present-day Tokyo) against flooding. Because numerical data related to the topography and hydrology of that era do not exist, simulation conditions were inferred from records from the beginning of twentieth century and recent GIS elevation data and flood records. In the simulation results, floodwaters spread over the floodplain surrounded by the levee system, and the inundation areas expanded gradually through a canal to rice paddies in the adjacent river basin. Furthermore, the rise in the water level induced by the levee system produced a steeper water surface slope in the downstream channel, causing a high-rate discharge to Tokyo Bay, where the water level was practically constant. These results suggest that the river engineering of Japan in the seventeenth century was based on a levee design technique with the aim not of restraining floodwaters with levees but of generating water head differences to divert flood flow from urban areas.
AB - Numerical simulations using the shallow water model on an unstructured triangular mesh system were conducted to elucidate the hydraulic functions of the Nihon levee system, which was built in the seventeenth century to protect the city of Edo (present-day Tokyo) against flooding. Because numerical data related to the topography and hydrology of that era do not exist, simulation conditions were inferred from records from the beginning of twentieth century and recent GIS elevation data and flood records. In the simulation results, floodwaters spread over the floodplain surrounded by the levee system, and the inundation areas expanded gradually through a canal to rice paddies in the adjacent river basin. Furthermore, the rise in the water level induced by the levee system produced a steeper water surface slope in the downstream channel, causing a high-rate discharge to Tokyo Bay, where the water level was practically constant. These results suggest that the river engineering of Japan in the seventeenth century was based on a levee design technique with the aim not of restraining floodwaters with levees but of generating water head differences to divert flood flow from urban areas.
KW - Early modern period
KW - Historic flood control strategy
KW - Levee system design
KW - Shallow water model
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U2 - 10.1007/s10652-018-9616-6
DO - 10.1007/s10652-018-9616-6
M3 - Article
AN - SCOPUS:85050369939
SN - 1567-7419
VL - 19
SP - 1295
EP - 1307
JO - Environmental Fluid Mechanics
JF - Environmental Fluid Mechanics
IS - 5
ER -