Estimation of the Relative Uplift Rate by Stream Power Incision Model in the Chiayi Area, Southwestern Taiwan
Date Issued
2008
Date
2008
Author(s)
Huang, Hsiao-Ting
Abstract
Chiayi area revealed by geodetic measurements and background seismicities, in the Southwestern Taiwan has been undergoing active intensive crustal deformation. We used the stream power erosion model of 9 rivers, easy and less time consuming, to characterize the occurrence and morphology of fluvial bedrock channels and to establish their relationships with tectonic activities. Besides, the stream-power erosion model also takes some hydrological factors such as water discharge, precipitation, and sediment export into consideration to quantify the influence of erosion process in the stream power erosion. Most of the selected rivers in our study area showed high values of concavity (0. 42 ≤ m/n ≤ 0.91), comparing to the global mean river concavity (m/n ratio 0.5), implying the high tectonic activity and high erosion rate in Chiayi area. The mean annual precipitation, water discharge and suspended sediment export concentrations (Cs) for a period of eighteen years (1984~2001) were calculated to figure out the reason for such high m/n ratio. The result showed that precipitation might be one of the important factors to result in high river concavity in the south of the study area. DEM resolution plays much less important role than sampling methods. Because both normalized steepness index (ks) and concavity index (θ) indices are related to lithologic variations, sediment flux, orographic precipitation and uplift rate, thus the normalized steepness index (ksn) is used to quantify the “real” uplift only. The result has pointed out that high uplift rate is predicted at southern part of Pachang river while low uplift rate is predicted at the northern part even though the sinuosity of all rivers are displaying the same pattern. Finally, the characteristics of river basin such as the lithology, structure, hydraulic geometry and so on are also been discussed. We conclude that the river concavity and normalized steepness index deduced from stream power erosion model not only could reflect the influence of tectonic activity and the erosion process but also associate with the drainage basin characteristics.
Subjects
Chiayi Area
Tectonic Activities
Geomorphology
Geomorphic Indexes
Stream Power Incision Model
River Concavity (m/n ratio)
Normalized Steepness Index (ksn)
Type
thesis
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