仁淀川流域の豪雨出水の統計的特性

Abstract

There exist several low lands in danger of flooding in the down-stream reaches of the Niyodoriver. Flood disasters there are not independent of flood flows in the Niyodo river, but the floodflows are not simple because the Niyodo river basin is large as 1460 km2 in area in the upstreamof Ino which is the key water gauge station for river plannings.In this paper, the statistical characteristics of heavy rainfalls are examined for the flood flowsover 3000 m3/s at Ino, by applying the principal component analysis. On the basis of the results, the correlation between average rainfall over a sub-basin and flood peak discharge at Ino isexamined to show that the flood peak is mainly governed by the rainfall in the middle zone of thebasin.