Study of Traditional River Works Technologies in the Upstream Region of the Kiso River in Early Modern Times

Based on Nationally-Mandated Locally-Financed Kiso River Infrastructure Diagrams of 1845

Abstract

In recent years, decrease in the flow capacity of rivers has proceeded due to increased rainfall and forestation. For the environment, maintenance and control must coexist with nature. For this, it is crucial that we know our history of river control and learn from the wisdom of our ancestors. In the upstream region of the Kiso River, nationally-mandated locally-financed river works projects were frequently conducted in early modern times. Even now many of these facilities remain. This study analyzed the characteristics of river channels as well as the design concepts of river works based on the diagrams of these flood control projects. This study shows that the river works mainly employed stone spur dikes on river gravel beds and prevented scouring using sinking frames.