HISTORICAL TRANSITION OF RIVER TRAINING WORKS AND INUNDATION CHARACTERISTICS IN SAPPORO

Abstract

The urbanization in Sapporo was started about only 140 years ago. Before the urbanization, the topography of most part of Sapporo was wetland and not suitable for living and cultivation. Intensive river training works have changed this area dramatically for relatively short period, and made Sapporo as one of the biggest cities in Japan with a population of 1.9 million. In this study, the history of river training works and the transition of inundation characteristics in Sapporo are investigated through old literatures and numerical simulations. First, the historical process of river training constructions was clarified by inspecting old documents and found out some key works. Then numerical simulations of flood were performed in three cases, namely, original topography, after construction of Toyohira-River- Bank and after construction of new Toyohira River Channel. The comparison of simulation results elucidated the relation between river training works and change of inundation behavior.