Flood Control by Traditional River Technique in Japan

日本传统河流技术的防洪在熊本县，有许多防洪工程，如导流结构，堤防和丁坝，由加藤清正作为封建领主在江户时代早期建造的石头。然而，大部分工程在防洪方面所发挥的作用，至今仍未有实际的证明。在本文中，Kiyomasa常用的Kutsuwa Domo，这需要扩大河流的汇合处或冲点，以削弱洪水，从历史的河流整治方法的观点进行了研究，通过应用水力模型，位于滨户河岛田区的Kutsuwa Domo。模型比例为1/150。本文的研究结果表明，Kutsuwa Domo最初是由Kiyomasa创建的，与Kasumi银行不同（开放式堤坝）和有效的工程，以应对超过设计极限的洪水。花栗水道以其形状独特的建筑物而闻名，它是1608年加藤清正为了灌溉位于白罗河流域中游的稻田而在中须山建造的。为了掌握花栗水道的实际状况和水力功能，进行了现场调查和模型试验。结果表明，花栗水道有26个壁面，壁面下部有一个半圆形的洞，壁面间的水流具有壁面射流的特征，有足够的牵引力输送阿索火山喷发的火山灰。

Flood Control by Traditional River Technique in JapanIn Kumamoto Prefecture, there were many flood protection works such as diversion structures, levees and groynes made of stones which were constructed by Kiyomasa Kato as a feudal lord in the early Edo era. However, most works have not been clarified with actual proof as to how they play a role in flood protection. In this paper, Kutsuwa Domo commonly employed by Kiyomasa, which entails the widening a river at the confluence or rushing points to weaken floods, was investigated from the viewpoint of historical river regulation methods by applying a hydraulic model to a kutsuwa domo located at Shimada district in the Hamado river. The model scale was 1/150. The results of this paper showed that Kutsuwa domo was originally created by Kiyomasa, different from Kasumi bank (open levee) and effective works for floods exceeding the design limit.The Hanaguri channel is known for mysterious-shaped structures, which was constructed in the Nakasu mountain to irrigate a paddy field lying in the middle reach of the Shira river basin by Kiyomasa Katou in 1608.In this study, a field investigation and a model experiment were carried out to grasp the actual status and hydraulic functions of the Hanaguri channel. The results showed that the Hanaguri channel had 26 walls with a semicircular hole which was dug in the lower part of the wall, and the flow between the walls exhibited the characteristics of wall jet and had enough tractive force to transport volcanic ashes erupted from the Mt Aso.