肥後における伝統的河川工法「轡塘」について

抄録

In Kumamoto Prefecture, there were many flood protection works called Kutsuwa Domo in the Edo Period. They were commonly employed by Kiyomasa Kato(1562-1611) as a feudal lord in the early Edo era and which entailed the widening a river at the confluence or rushing points to weaken floods. However, most works have not been clarified with actual proofs as to how they play a role in flood protection.

In this paper, Kutsuwa Domo was investigated from a viewpoint of historical river regulation methods. Hydraulic model tests were conducted to a Kutsuwa Domo located at Shimada district in the Hamado river, using a model scale 1/150. In addition, the archives of land use in floodplain effected by Kutsuwa Domo in Midori River basin were investigated to reveal the relationship between flood disasters and land tax. The results showed Kutsuwa Domo was effectively works for floods exceeding the design limit as traditional river works, and the distance from Kutsuwa Domo with overflow type levee in floodplain has a decisive effect on land tax.