Abstract
The development process and flood control effects of the open-levee system, which was constructed from the mid-18th to the mid-19th centuries, on the Kurobe Alluvial Fan—a large alluvial fan located on the Japan Sea Coast of Japan’s main island—was evaluated using numerical flow simulation. The topography for the numerical simulation was determined from an old pictorial map in the 18th century and various maps after the 19th century, and the return period of the flood hydrograph was determined to be 10 years judging from the level of civil engineering of those days. The numerical results suggested the followings: The levees at the first stage were made to block the dominant divergent streams to gather the river flows together efficiently; by the completed open-levee system, excess river flow over the main channel capacity was discharged through upstream levee openings to old stream courses which were used as temporary floodways, and after the flood peak, a part of the flooded water returned to the main channel through the downstream levee openings. It is considered that the ideas of civil engineers of those days to control the floods exceeding river channel capacity, embodied in their levee arrangement, will give us hints on how to control the extraordinary floods that we should face in the near future when the scale of storms will increase due to the global climate change.
Highlights
With the recent progress of computers, on the other hand, numerical simulation of flood flows in a wide area has become a powerful tool to clarify the hydraulic effects of those old river works as well as to understand the flood control strategy in the Edo period when the engineers lacked the knowledge of modern hydraulics and advanced techniques for levee construction
The ground surface is classified into landforms plains, old river channel traces, terraces, natural levees, wetlands, and sa hough the old river channel traces are often fragmentary, they possibly co locations of stream paths depicted in Map (a)
With the progress of levee construction technology in the middle of the 18th century, the branch streams were blocked by construction of longer levees to unify the river flow for the full-scale development of the Kurobe Alluvial Fan
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. According to researchers who studied the development process of those works from the viewpoint of engineering history by analyzing old documents and drawings, many of the river improvement works in Edo period were successful, and some of them were in use until quite recently (for example, [1,2,3,4]). With the recent progress of computers, on the other hand, numerical simulation of flood flows in a wide area has become a powerful tool to clarify the hydraulic effects of those old river works as well as to understand the flood control strategy in the Edo period when the engineers lacked the knowledge of modern hydraulics and advanced techniques for levee construction (for example, [7,8,9,10,11]). It is expected that the ideas of civil engineers of those days, embodied in their levee arrangement, might give us hints on how to control the extraordinary floods that we could face in the near future when the scale of storms increases due to global climate change
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
