Some characteristics of heavy rainfalls in the Yamato River Basin found by the principal component and cluster analyses

In this paper, characteristics of spatial distribution of heavy rainfalls causing floods in the Yamato River basin located in the Kinki district are examined by applying the techniques of both principal component and cluster analyses. The result of the principal component analysis shows that rain gauge stations in this basin can be arranged into eight groups from the common characteristics of rain storms. On the other hand, the result of cluster analysis differs slightly from the former, but supports it in the practical sense. Finally, the correlations of flood peak discharges at Kashiwara with 12-, 24-, and 48-hour maximum rainfalls averaged over a basin are examined. The result shows that the flood peak discharges have strong correlation with areal 12-hour rainfalls, especially with those in new urbanized areas along the main channel. (Authors)