Abstract
Recentry, slope failures caused by heavy rainfall occured at Noboribetsu City.
During August 28 to 31, 1980, the total precipitation reached 576mm and maximum rainfall intensity attained 60mm/h at 6: 00 a.m. on August 31, recorded at Horobetsu town along the coastal area. This rainfall pattern was the coast rain. Most of the slope failuers were concentrated in the area from Horobetsu to Tomiura, where the precipitation of 40 to 60mm/h associated with previous rainfall 200mm, was documented.
In September 24 to 25, 1983, the total precipitation reached 508mm and rainfall intensity attained 126 mm/h at 4: 00 a.m. on September 25 at Satsunai. This rainfall pattern was the hill rain. The numerous slope failures, debris flows and erosion of river bottoms occured in the area from Mt. Kamuinupuri and Satsunai hill to Lake Kuttara, where the precipitation of 250 to 300mm without previous rainfall.
