Verification of the Scale of “The Yokota-Gire Flood” From the Viewpoint of Characteristics of Rainfall of Historical Floods in the Shinano River Basin

Abstract

This study is conducted as part of the study on estimation of the peak discharge of "the Yokota-Gire Flood" in July 1896, one of the historical floods in the Shinano River Basin. This study analyses relationship between rainfalls and discharges of relatively large floods since 1956 with well recorded rainfalls and flood discharges, and particularly compares the Yokota-Gire Flood with the flood in September 1982, in which the similar amount of rainfall was recorded despite the difference of the number of precipitation stations exists. Making clear the characteristics of hourly and spatial distribution of the rainfalls which caused large floods in the Shinano River Basin, not only helped to improve the accuracy of the peak discharge estimation of the Yokota-Gire Flood and to verify its validity, but also clarified the statistical positioning of the Yokota-Gire Flood through rainfall characteristics. Key Word: historic flood, rainfall and discharge, hourly and spatial distribution of rainfall, estimation of peak discharge