Flood Disaster in the Yura River in 2004 and 2013

Abstract

The Yura River in northern Kyoto Prefecture has long caused flood problems in its drainage basin. Specifically, areas downstream from Ayabe, where the river comes down from mountainous regions to a basin, frequently suffered from inundations, e.g., the Disaster Relief Law was applied eight times in the 60 years from 1953 to 2013. Against those background, river development projects, including levee construction and channel dredging, have been well underway since the late 1950s. The Ohno dam upstream on the main river was completed in 1961. However, the degree of flood safety remained low at that time. In 2004, the heaviest flood in the 50 years since 1953 occurred, followed in 2013 by a massive flood recording the highest water level since observations began at Fukuchiyama. The 2013 flood occurred in the midst of urgent levee construction and land raising based on a river infrastructure development project begun in response to a 2004 flood. This paper outlines damage from floods in 2004 and 2013 and shows the effects of these floods on the inundation depth of levees under development and the effects of the difference in rainfall characteristics in 2004 and 2013 on flood and fine sediment runoff. The effectiveness of the Ohno dam and misunderstandings by residents of the dam are also described. Important points in promoting river development from hard and soft measure are presented for making use of experiences the two disaster in the future.