Abstract
The present paper reports that the landslide in the snowmelt period in Niigata prefecture (1950-1974) depends mainly on the snowmelt, as follows :
(1) The longest period in every year in which snowmelt water covers the ground surface, ND, is denoted approximately by the uninterrupted number of decreasing days of snowcover depth at Nagaoka city, Niigata prefecture. In defining ND, the small suspension of decreasing in snow depth (less than two days) is of little significance to water saturation underground, therefore, it is omitted.
(2) The frequency of landslides in the maximum snowmelt period (usually in March and April, and in some cases continuing into May) NS, by using the above mentioned ND, is given as NS=10.2+0.91ND, where the largest observed values where NS=52 times and ND=45 days. The correlation coefficient between NS and ND is obtained as 0.70.
