Freeze-thaw processes and periglacial landforms of High Mountain in Taiwan
Date Issued
2007
Date
2007
Author(s)
Chan, Yi-Chin
DOI
zh-TW
Abstract
Frost action is one of the important environmental factors in alpine and periglacial climate. Among them, freeze-thaw process is the most influential geomorphologic process in the area. Freeze-thaw weathering and gelifluction movement shapes the landform in high mountain area of Taiwan. In this study, the air and ground temperature data of 2, 10 and 20 cm depth of Mt. Nanhu was used to model the magnitude, frequency and distribution of freeze-thaw process. Besides, field investigation was also conducted to depict the geomorphological map in Mt. Nanhu area.
According to ground temperature data in Mt. Nanhuta collected from 2001 to 2005, frequency of freeze-thaw processes at depth of 2 , 10 and 20cm was 55, 8.75 and 1.25 times per year respectively. The freeze-thaw process was weak at depth of 20cm. It was most frequent in autumn and spring but not few in winter for freeze and snow cover in that period.
At the depth of 10 cm in the ground, there are about 2 months of frozen period per year in average. The measured and estimated ground temperature data are highly correlated, the R-square value is 0.7875, and the numbers of freeze-thaw from measurement and estimation by the model are identical.
The relationship between elevation and freeze-thaw cycle is in logarithm regression by the estimation of the model. However, the relationship between freeze-thaw cycle and forest line in Mt. Nanhuta is not clear.
According to field investigation, there are some periglacial landforms in the Mt. Nanhuta and Mt. Hehuan, including turf-banked lobes terraces, talus accumulation and talus slopes. Turf-banked lobes terrace are crescent shape terrace developed in Mt. Sheimajuei and the saddle between main peak and east peak of Mt. Nanhuta. Talus accumulation is developed in the saddle between main peak and east peak of Mt. Nanhuta. Talus slope is accumulated a lot of frost-wedging rock which is located at east of upper-cirque. It shows that freeze-thaw processes are active in the Mt. Nanhuta, so there are many periglacial landscapes between 3200-4000m above sea level.
Subjects
南湖大山
凍融作用
冰緣地形
垂直分布帶
Nanhuta Shan
alpine landscapes
freeze-thaw processes
periglacial landforms
vertical distribution
Type
thesis
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