• Journal of the Korean earth science society
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• v.45 no.4
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• pp.363-376
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• 2024

Alluvial beds are intimately associated with electrical properties related to soil types, including clay mineral content, porosity, and water content. The hydraulic property governs water movement and storage in alluvial beds. This study revealed electrical resistivity and hydraulic properties in space and time in relation to the hydrogeological data, groundwater pumping, and rainfall infiltration into the alluvial bed located in Daesan-myeon, Changwon City. An electrical resistivity survey with electrode spacings of 2 and 4m using a dipole-dipole array indicates that electrical resistivity changes in the alluvial bed depend on groundwater pumping and rainfall events. Additionally, rainfall infiltration varies with hydraulic conductivity in the shallow zone of the alluvial bed. The 2 m electrode spacing survey confirms that electrical resistivity values decrease at shallow depths, corresponding with rainfall and increased water content in the soil, indicating rainfall infiltration approximately 1-2 m below the land surface. The 4m electrode spacing survey reveals that hydraulic conductivity (K) values and electrical resistivity (ρ) values display an inverse relationship from the surface to the water table (approximately 9 m) and at deeper levels than the water table. Notably, ρ values are impacted by pumping around the depth of the water table at 9 m. This study suggests that time-lapsed electrical resistivity surveys in space and time could be effective tools for detecting the impact of rainfall and pumping, as well as hydraulic conductivity in shallow alluvial beds.

• Water for future
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• v.24 no.1
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• pp.99-107
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• 1991

This study is for simulating to the model which analyzes flow characteristics and transverse bed slopes in a coarse-streambed of the meandering alluvial channels. Using the equations for conservation of mass, momentum, and for lateral stability of the streambed, a linear differential equation of transverse bed slope is derived from the flow characteristics in curved channels. Its solutions are solved by the Sine-generated curve method(SCM) and compared with results of field measurements. Lag distances by the maximum transverse bed slope and velocity profiles will predict risk sections of concave bank under floods.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.4
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• pp.111-121
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• 1993

Changes in bed forms and subsequent changes in channel roughness by changes in water discharge are discussed with the field data collected from some alluvial rivers in Korea. This study is limited to the following condition of river flow: (1) Medium size alluvial rivers with their widths of 100 m more or less, (2) Straight and prismatic river reach with no additional causes for energy loss but bed friction, (3) Lower-flow regime with Froude number less than 0.5. Major conclusions obtained from this study can be summarized as follows: (1) For the channels considered in this study, the bed roughness expressed by Manning's n increases from 0.02 for the plane beds with no sediment motion to 0.05 for the dune beds, (2) The roughness coefficient for alluvial channels should not be estimated from Strickler-type equations developed for the fixed beds, (3) The method for determining the channel roughness suggested in the present guideline for river works, River Structure Standard, appears to be lack of generality. More research based on the field data collected in Korea is needed in order to improve the existing methods.

• Journal of the Korean earth science society
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• v.27 no.7
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• pp.757-767
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• 2006

Alluvial-plain deposits in the southeastern part of the Eumsung Basin (Cretaceous) are characterized by coarse-grained channel fills encased in purple siltstone beds. It represents distinct channel geometry, infill organization, and variations in facies distribution. The directions of paleocurrent, sedimentary facies changes, and channel-fill geometry can be used to reconstruct a channel network in the alluvial system developed along the southeastern margin of the basin. The channel-fill facies represent downstream changes: 1) down-sizing and well-sorting in clast and martix of channel fills and 2) internal organization of scour fill or gravel lag and overlying cross-stratified, planar-stratified beds. These findings suggest multiple stages of channel-filling processes according to flooding and subsequent stream flows. In the small-scale pull-apart Eumsung Basin (${\sim}7{\times}33km^2$ in area), vertical-stacked alluvial architecture of the coarse-grained channel fills encased in purple siltstone is expected to result from episodic channel shifting under a rapidly subsiding setting.

• Proceedings of the Korea Water Resources Association Conference
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• 1995.05a
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• pp.9-14
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• 1995

• KSCE Journal of Civil and Environmental Engineering Research
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• v.4 no.1
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• pp.49-58
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• 1984

This paper is to exhibit the numerical analysis of sediment transport in the slowly varing flow and the sediment transport relation between the steady and the unsteady flow in the alluvial stream. The gradually varied flow of alluvial stream and the sediment transport are very complicated physical phenomen. Therefore the mathematical modeling is needed to be established. Linear implicit means of modified indirect method are applied to sediment transport by numerical analysis instead of the conception of steady flow in order to decrease errors. Further more, this study has purpose on reasonable prediction of the river-bed variation by way of this numerical method.

• Korean Journal of Hydrosciences
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• v.1
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• pp.61-71
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• 1990

The characteristics of radial thickness of ice jam at the center part of channel bends were analyzed briefly in this paper. Jam thickness in channel bends increases both toward the inner bank, and dowmstream. For this study, slope at the jam's underside was assumed to be liner with similarity of radial slope of bed in alluvial bends. Radial slope at the jam's underside in floating ice elements was estimated using the force equilibrium theory in the radial direction. The eqution which can be estimated the radial slope of ice jam was suggested using Falcon and Kennedy's bed layer theory. Experimental data, which were measured at the center part of cross-section in a single 180-degree bend, were compared to the calculated values using the suggested equtions. The result shows that the calcultated values were smaller than the measured ones. Ot is considered that the estimated value of shear stress in the radial direction may be smaller than the actual and two-layer model may be not suibable for alluvial bend flow.

• Journal of the Korean Geographical Society
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• v.39 no.1
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• pp.56-69
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• 2004

We investigated the distribution and geomorphic development of alluvial fan in Gyeongju City including Cheonbuk area. According to a relative height to a river bed, alluvial fans of this area are divided into Higher surface, Middle surface, and Lower surface. As alluvial fans of Bulguk temple∼Ulsan bay area, the confluent fans in Cheonbuk and Gyeongju areas were formed by the Quaternary climatic change alternating glacial and interglacial stages, and the development of N-S and NW-SE fault lines. The Gyeongju alluvial fan, the largest in Korea, has been provided as the significant space for human activity since the prehistoric age. Bukcheon river formed the Gyeongju alluvial fan had not flowed over during the prehistoric and the ancient times. In contrast with general geomorphic characteristics, many springs in the Gyeongju alluvial fan are located in the middle part of the fan because ground water reaches to the surface. It is supposed that sedimental materials were not sufficiently piled up at lower reach of Bukcheon river due to the large deposits at upper and middle reach of the basin.

• Magazine of the Korean Society of Agricultural Engineers
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• v.11 no.4
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• pp.1827-1831
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• 1969

Resulties of research on the capacity of ground water of 994 concrete-pipe-wells and 97 infiltration-gallerys in ground-water-developement-works region executed from March to Julyin 1969, in Choong Chung Nam Do, and research on the quality of ground water for 88 wells for home-use around of River Geum Area, are as fellows: (1) Thickness of aquifer is no more than 2.85m averagely even at river-overflowed plain, alluvial plain and valley plain area that are estimated to contain ground water mostly. And so, it is guessed that ground water capacity is not much especially. (2) Soil of aquifer of the above area is sand or gravel and it is estimated to be good for ground water developement and its mean permeability coefficient is bout $2.5{\times}10^{-3}$(m/sec), and its porosity is about 33.9%. (3) The quality of ground water is good for irrigation water exception of delta plain area. Warm water plan is to need for irrigation water when water temperature is less than 19 degrees below zero. (4) Prospect of ground water developement, judging from quality and quantity, expects to lay infiltration gallery under the ground at river bed in order to utilize under-flow-water of river bed, river-overflowed plain, alluvial plain and valley plain that ground level is less than 50m. (5) Collectable water volume of under-flow-water of river bed is about 450 to $750m^3/day$ to be able to irrigate 3ha to 5ha of the cultivated land in case that infiltration gallery length is 50m and its depth is about 5m. (6) Collectable water volume at river-overflowed plain, alluvial plain and valley plain area, is estimated $150m^3/day$ to be able to irrigated 1ha of the cultivated land.

• Korean Journal of Hydrosciences
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• v.1
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• pp.49-60
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• 1990

Manning's roughness factor to flow in sand-bed channels may be divided into the grain roughness factor nd the form roughness factor. The grain roughness factor may be dedermined by using Keulegan's formula. By using available experimental data, it was found there is a unique relationship between the form roughness and the hydraulic radius to sediment particle size ratio for a given value of the Froude number. The form roughness and the bed form may be determined by using this unique relationship. The technique for engineering applications of the results appears to be quite simple.