[M-IS11] Mountain Science

[MIS11-P11] Spatial distribution of gravel mass movement on periglacial smooth slope using remote sensing

*KATSURA SAITO¹, Chiyuki Narama², Eri Fukada³ (1.niigata university・Graduate school , 2.niigata university, 3.CERI)

Keywords:periglacial smooth slope, remote sensing, DInSAR, UAV, freeze-thaw action

Periglacial smooth slopes are slopes with slight unevenness that extend along the ridgelines of alpine belts in windswept areas (Koizumi, 1992). In this study, we investigated the spatial distribution of gravel movement on periglacial sand and gravel slopes and evaluated the effect of snow cover on freeze-thaw behavior.
DInSAR and image-matching analyses were conducted on periglacial sand and gravel slopes in the Hakuba mountain range, with the largest periglacial sand and gravel slope area in the northern Japanese Alps. The results show that most of the periglacial sand and gravel slopes of the Hakuba mountain range have undergone extensive land surface changes, but the areas of gravel movement are limited in each slope. The gravel movement was observed on only some of the periglacial sand and gravel slopes but in areas with low snow cover. Lifting of gravels due to diurnal freezing and thawing was confirmed by time-lapse camera images. Gravels moved downslope as the ground temperature decreased during the night. Based on ground temperature observations, freeze-thaw cycles rarely occurred in areas with thick snow cover. In contrast, they occurred frequently in areas with a small snow cover.