• Journal of The Geomorphological Association of Korea
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• v.25 no.4
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• pp.1-19
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• 2018

This study tries to identify distributional characteristics of stream incision rates at 23 points in the northern part of the Taebaek Mountains. Soyang-gang, Naerin-cheon, Odae-cheon, Dong-gang and upper reaches of Okdong-cheon Rivers closed to the Range show higher incision rates and the rates clearly decrease with distance from the Range. Therefore, the incision process in the northern part of the Range has been greatly influenced by uplift around the Range, and the Sobaek Mountain Range seem to play a role in the incision process. Limestone areas show lower incision rates due to degradation of terrace surface by dissolution. This study suggests that local hydrological, geological and geomorphological conditions can be regarded as an important factor in stream incision rates, although stream incision rates are greatly influenced by regional uplift.

• Journal of the Korean Geographical Society
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• v.49 no.1
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• pp.1-17
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• 2014

This study estimates geomorphological processes of fluvial terraces by uplifts and bedrock features, by the analyses of topography, distribution, formation age and incision rate of fluvial terraces using Gwang-cheon River in Uljin, Namdae-cheon River in Pyeonghae and Osip-cheon River in Yeongdeok located in the southern Taebaek Mountain Range. The tectonic and climatic terraces I in the upper reaches of Gwang-cheon River with an altitude from riverbed of 9~12m indicate the formation age of MIS 2 with a incision rate of 0.40m/ka. However, the tectonic and climatic terraces I in the upper reaches of Osip-cheon River with an altitude from riverbed of 7~10m show the formation age of MIS 3 with an incision rate of 0.10m/ka. These results suggest that the uplift rate in the Gwang-cheon River basin is likely to be higher than that in the Osip-cheon River basin. Unlike the lower reaches of Osip-cheon River, the thalassostatic terraces are not found in the lower reaches of Gwang-cheon River, because the basin has low maintainable ability of landforms in river valley due to high uplift rate and bedrock properties resistant to weathering and erosion. On the other hand, the lowest tectonic and climatic terraces in the study areas indicate different formative ages and the terraces during the cooling stage in interglacial as well as during interstadial are also found. Therefore, this study suggests that chronological method for fluvial terrace by the previous developmental model of climatic terrace should be reconsidered.

• Journal of the Korean Geographical Society
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• v.44 no.4
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• pp.447-462
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• 2009

Kohyun River basin is located at southern parts of Taebaek Mountains and most of river basins consists of sedimentary rock. The aims of this study are to investigate the distribution characteristics and processes of fluvial terraces at Kohyun River, using scientific methods such as classification of fluvial landforms, analysis of geomorphological deposits, XRD and OSL age dating. In Kohyun River basin are three levels terraces from T1 to T3. Fluvial terraces are assumed to be erosional terraces according to deposited situation of alurium and existences of bedrock riverbed. From the result of OSL age dating, formation age of fluvial terrace 1(T1) is calculated about 37,000 yr.B.P.(MIS 3), and fluvial terrace 2(T2) is calculated about 113,000 yr.B.P.(MIS 5). Therefore, fluvial terraces at Kohyun River are assumed to be formed at warmer period in the glacial stages or cooler period in the interglacial stages. The incision rate of fluvial terrace 1 at Kohyun River is calculated to be 0.054m/ka, and the incision rate of fluvial terrace 2 is calculated to be 0.115m/ka. This results suggest to lower incision rate than other rivers in Korea because of low uplift rates and little discharge.

• Journal of The Geomorphological Association of Korea
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• v.28 no.3
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• pp.27-35
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• 2021

This study tried to reveal incision rate and its change by formation of lava plateau in the Cheorwon-Jeongok area. Incision rates of 0.421 m/ka and 0.101 m/ka in the upper and lower reaches of Hantan-gang, respectively, were calculated from sites before formation of lava plateau. These incision rates indicate that the upper and lower reaches of Hantan-gang have much higher and slightly lower incision rates than streams with similar distances from the Taebaek Mountains. However, sites after formation of lava plateau mostly showed incision rates ranging from 0.5 m/ka to 0.9 m/ka. Streams flowed on the lava plateau revealed 2-3 times higher incision rates than unrelated-streams or paleo-streams to formation of lava plateau did. These results suggest that incision rate in the study area was greatly influenced by formation of lava plateau and resultant geomorphic avulsion with rearrangements of stream.

• Journal of The Geomorphological Association of Korea
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• v.28 no.2
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• pp.15-30
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• 2021

This study tried to reveal distribution of incision rate and the factors from fluvial terrace deposits on the western and eastern slopes in the Middle Sobaek Mountain Range, using OSL age dating and topographical analysis. An average incision rate of 0.220 m/ka was estimated in the western slope streams, while the streams on the eastern slope showed a lower average incision rate of 0.121 m/ka. These results seem to indicate that the study area experienced an asymmetric uplift. Patterns of incision rate in the study area were different from those in the Northern Sobaek Mountain Range, probably suggesting that the Sobaek Mountain Range experienced spatially different uplift patterns. Among the factors, which were considered to influence on distribution of incision rate in the study area (e.g., altitude of sampling point, distance from divide, distance from axis, channel width, and bedrock type), distance from axis showed the strongest relationship with incision rate. Therefore, uplift is thought to be the most significant factor in distribution of incision rate in the Middle Sobaek Mountain Range.

• Journal of the Korean Geographical Society
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• v.44 no.3
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• pp.224-239
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• 2009

This study analyzes the properties of fluvial landforms in the upper and lower reaches and investigates the evolutions of stream and fluvial terrace in the Odae river basin. The lower basin of the river that consist of sedimentary rocks resistant to weathering and erosion processes shows higher altitude, relief and slope than the upper basin that consist of granite less resistant to weathering and erosion processes. The average width of river valley at the lower reaches is one-third to the upper reaches and the average width of river channel at the lower reaches is narrower than at the upper reaches. Based on the OSL age dating, the fluvial terrace T1 formed at the temperature-rising period during the late MIS 2 and T2 formed at the middle MIS 3, interstadial period during the last glacial period. Based on the these results, the average incision rates of Odae river are calculated as 0.205m/ka and 0.269m/ka at the upper granite area and lower sedimentary rocks area, respectively.

• Journal of The Geomorphological Association of Korea
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• v.27 no.3
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• pp.41-51
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• 2020

This study tried to reveal incision rate distribution of streams on the northern part of the Sobaek Mountain Range with OSL age dating and geomorphic analysis, and factors influencing on the distribution were also discussed. With results from the previous studies, a total of 10 sites from 7 streams in the study area showed the rates ranging from 0.220 m/ka to 0.297 m/ka. Namhan-gang and Geum-cheon indicated the highest and lowest rates, respectively. Both sides in the northern section in the study area showed similar rates, while the western side in the middle section and the eastern side in the southern section showed higher rates than the other sides. Higher rates were also found from the eastern and northern sides where the Range runs N-S and E-W directions, respectively. Certain relationships with altitude and distance from the divide can be recognized from the rates and may be attributed to active incision with altitude and location of the uplift axis near the present divide. The rates on granite and sedimentary rock were higher than those on metamorphic rock, indicating that bedrock type is one of the important factors influencing on stream incision. Tectonic movement seemed to play some roles in the rates, because areas with lineaments showed lower rates. This study suggests that incision rate distribution of streams on the northern part of the Sobaek Mountain Range reflects various local geomorphic and geologic conditions.

• Journal of The Geomorphological Association of Korea
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• v.18 no.4
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• pp.17-33
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• 2011

This study summarizes the research history of fluvial terraces in Korea and examines the geomorphic properties of fluvial terraces in Korea based on the previous works. The research history of fluvial terraces in Korea can be divided into the three periods. The theories of fluvial terraces were spread by the early geomorphologists during the period of Japanese colonial era to mid-1980s. The dissertations on the fluvial terraces were intensively published during the late 1980s to 1990s and their discussions were the center of geomorphology researches in Korea. Since 2000s, the discussions have become more mature and researches have been quantitatively increased as the various methodologies have been developed. The fluvial terraces in Korea are mostly developed in the western and eastern parts of the Taebaek Mountains, upper and middle reaches of Han and Nakdong River, and in the western slopes of Sobaek Mountains, middle reaches of Namhan River, upper and middle reaches of Geum and Seomjin River. Along these rivers in actively uplifted areas, fluvial terraces with much higher altitude from riverbed are observable and incision rates are relatively high. In the sense of the formation ages, they have developed in not regular patterns by the climatic changes during the Quaternary, but in more complicated aspects by the environmental conditions such as climate, hydrology, geology and geomorphology in the specific drainage basins.

• Journal of The Geomorphological Association of Korea
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• v.24 no.2
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• pp.27-40
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• 2017

This study tries to analyze topographic distribution and characteristics of as well as formative age and incision rate of fluvial terraces in Danyang River on western side and Geum River on eastern side of the northern Sobaek Mountains and to estimate geomorphic development during the late Quaternary in the mountains regarded as one of the uplift axes in the Korean Peninsula. OSL age dating shows that the fluvial terrace I with an altitude above riverbed of approximately 7~13 m in Danyang River has a formative age of approximately 18 ka (MIS 2) and incision rate in the river is approximately 0.156~0.194 m/ka based on the age. Altitudes above riverbed of the fluvial terrace I in Geum River range from approximately 7 to 14 m and the terrace is thought to be older than 70 ka based on age result from aeolian sediments above the terrace deposits, suggestive of an incision rate less than approximately 0.10 m/ka. These results indicate lower uplift rate in the northern Sobaek Mountains than in the Taebaek Mountains. Moreover, it can be suggested that the northern Sobaek Mountains has experienced asymmetric uplift during the late Quaternary, because the river on western side of the northern Sobaek Mountains shows greater uplift rate than the eastern side river does. Low incision rate in Geum River can be attributed to low altitude of the river basin with little difference in altitude from the base level as well as to gentle river slope due to influence of Nakdong River.

• Economic and Environmental Geology
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• v.44 no.5
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• pp.399-412
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• 2011

A DEM (digital elevation model) is produced using a digital topographic map and is now a commonly used tool in geologic surveys. This study aimed to clarify the relationship between knickpoints and faults in the Namdae stream by analyzing a DEM of the area. The Namdae drainage basin was divided into three subbasins (S1, S2 and S3) and their knickpoints developed for the middle to mid-upper regions were extracted from the DEM. The relative steepness Ks and concavity depending on the incision rate was higher in S1 than in S2 and S3 regions. We assumed that the incision rate caused by active erosion resulted from several faults crossing the basins rather than differences in rock types. There are 77 knickpoints in the Namdae drainage area, including the low-ranking branch, and 24 of thses are on the main river system (S1, S2, S3). Of these 77 knickpoints, 27 (38%) are matched by faults, and from the three basins, 13 (54%) correspond with faults, indicating that the knickpoints are connected closely with the faults. For example the average Ks (relative steepness), was 38.8, but in the overlapping area of the Samdang and Doocheon faults the Ks value was 42.99~43.39. We suggest that the faults resulted in geomorphic deformation such as the high-Ksn knickpoints. There was little evdence of relationship between the knickpoints and rock boundaries, with 54% of the knickpoints distributed on the S1, S2, and S3 subbasins. We concluded that the drainage basin knickpoints are the result of fault movement and are a type of geomorphologic deformation that could be useful for surveying Quaternary faults or fault extension.