• Journal of Korean Society of Environmental Engineers
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• v.37 no.10
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• pp.551-557
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• 2015

This study analyzes potentially hazardous sub-watersheds from non-point source pollution areas using an HSPF model. The watershed of the Juam dam reservoir was divided into 29 sub-watersheds, and the flow, BOD, TN and TP concentration for the Juam dam watershed were evaluated from 2009 to 2012 using a watershed model, with a warming period from 2009 to 2010. The results of the watershed model agreed well with the flow and water quality field measurements. The calculated average non-point source loadings were BOD of 8.8 and $9.1kg/day/km^2$ in 2011 and 2012, respectively; TN of 9.7 and $10.1kg/day/km^2$ in 2011 and 2012, respectively; and TP of 0.30 and $0.33kg/day/km^2$ in 2011 and 2012, respectively. The non-point source loading of the Bonghwa stream watershed was calculated, and predominantly assessed upstream of the Boseong river. Additionally, the Miryeok, Jangpyeong, Yuleo, Guam, Seokgyo, Mundeok, Incheon, and Bongnae stream watersheds, with extensive agricultural areas, were assessed to be potentially hazardous areas in terms of non-point source management. In this study, HSPF model was applied in order to aid in the selection of non-point source reduction facilities for the Juam dam watershed, where they were evaluated as to whether they would be applicable for non-point source management.

• Journal of The Korean Society of Agricultural Engineers
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• v.52 no.1
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• pp.79-88
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• 2010

준분포형 모형인 SWAT 모형은 소유역내 수문학적 반응단위 별로 유출, 유사 등의 발생을 평가하는데 이때 Hydrological Response Unit (HRU)의 지형정보가 활용된다. 현재 SWAT 모형의 인터페이스 구조는, 각 소유역의 평균 지형인자 값이 각 소유역내의 모든 HRU의 지형정보로 사용된다. 그러므로 각 소유역내의 HRU에 있는 지형인자를 정확하게 추출하기 위해서는 수계를 자세하게 나누어야 하며, 이를 위해서 더욱 자세한 소유역 수계 인터페이스가 필요하다. 현재 SWAT 모형 인터페이스에서는 수계를 나눌 때 임계값의 최소값은 최대 flow accumulation 값의 0.1 %가 사용된다. 따라서 HRU의 지형인자를 추출하기 위해 아주 자세한 정도로 소유역의 수계를 나눈다는 것은 불가능하다. 본 연구에서는 사용자가 원하는 임계값과 농경지 경계를 근거하여 소유역 경계를 추가로 수계를 나눌 수 있는 Dual Watershed Delineation Module (DWDM) 을 개발하였다. 기존 SWAT의 수계추출 모듈로 유량을 모의한 결과 $27,219\;m^3$/month 가 산정되었고, DWDM 을 적용한 결과 $26,172\;m^3$/month 로 약 3.8 %의 미미한 차이가 생겼다. 하지만 유사의 경우 DWDM을 적용하기 전에는 0.779 ton/month, 적용 후에는 2.688 ton/month 로 약 245 %의 차이를 보였다. 즉 농경지를 추가적으로 수계를 나눌 때 유사의 가장 민감한 요소인 경사장을 실제지형에 맞게 고려함에 따라 좀 더 정확한 유사 산정을 할 수 있었다. 농경지에서의 정확한 수문 및 유사 평가 시 본 연구에서 개발한 모듈이 적용 되어야 한다고 사료된다.

• Journal of the Korean Geosynthetics Society
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• v.17 no.1
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• pp.139-152
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• 2018

This study is an analysis of slope failure examples of cut sedimentary hills during construction road in Kyoungsang Basin, especially Yangsan Fault system (Ilkwang-Dongrae fault). This area involved a lot of hillslope failures compared to other areas during road construction. The exposed failure slopes were first face-mapped, and then back analyzed based on the limit equilibrium method to assess the shear strength parameters of discontinuity (bedding). The results of this analysis indicate that the shear strength parameters of discontinuity (bedding) are significantly smaller than those used in the design stage and presented in the existing works. The filling in the bedding and emerging groundwater may be decreasing strength parameters. Especially, the clay in the bedding plays a key role in the effect of the shear strength. The study also suggests that the bedding angle and the internal friction angle are proportional to each other. Using this relationship and knowing the bedding angle, the friction can easily be estimated.

• Journal of Korea Water Resources Association
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• v.41 no.11
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• pp.1143-1152
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• 2008

Korea is located in a monson area, so that 2/3 of precipitation is fallen down in rainy season and dry season has few rainfall. Also, water quality gets worse during dry season by shortage of water. In this paper, the method, which is a physical way to improve water quality by dilution through over supplied water from big reservoir or dam, is analyzed at Han-river basin. For the sake of the analysis, the basin is divided in 33 catchments and each catchments' natural flow is simulated by SWAT-K and the future water demand is estimated by using statistics data. It is considered that Han-river basin has two big reservoirs(Chung-ju dam, So-yang gang dam) and potential discharge by dam is calculated through case of supply water from each dam and supply water from both dams.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.25 no.1
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• pp.65-72
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• 1992

It is believed that the lower cold water is formed by winter cooling in the north of the East(Japan) Sea. To examine its effect on the general circulation of the East Sea, we performed a two-layer numerical model with realistic bottom topography. First a circulation is generated by imposing only an inflow and an outflow which is then modified by adding the cooling effect in the north. The interface between the two layers rises due to cooling and propagates along the coast as internal Kelvin waves. About 7 months after the cooling starts, all coastal areas of the basin have higher elevation than that in offshore region. This induces baroclinic currents resulting in clockwise(anticlockwise) circulation in upper (lower) layer of the basin. It is concluded that the East Korean Warm Current strengthens as a result of lower cold water formation.

• Water for future
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• v.28 no.3
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• pp.159-173
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• 1995

This study is to develop the suitable hydrologic models for determination of the size and location of detention storage facilities to restrain stormwater runoff in urban areas. Fictitious areas of two levels are considered to seize the hydrologic response characteristics. A one-square-kilometer area is selected for the catchment level, and a 10-square-kilometer area consisting of 10 catchments is adapted at the watershed level as representative of urban drainage area. In this analysis, different rainfall frequencies, land uses, drainage patterns, basin shapes and detention storage policies are considered. Flow reduction effect of detention storage facilities is deduced from storage ratio and detention basin factor. A substantial saving in detention storage volumes is achieved when the detention storage is planned at the watershed level than the catchment level. For the application of real watersheds, two watersheds in Seoul metropolitan area-Jamshil 2, Seongnae 1-are selected on the basis of hydrologic response characteristics. Through the regression analysis between dimensionless detention storage volume, dimensionless upstream area ratio and reduction rate of storage ratio, the regression equations to determine the size and location of detention storage facilities are presented.

• Journal of Korean Society for Geospatial Information Science
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• v.15 no.2 s.40
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• pp.25-31
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• 2007

The recent frequent heavy rainfall has caused an increased in soil erosion and the soil drain which drained soil has caused decreased in channel radius and environmental problems by turbidity. In this study, the optimum size of the sediment basin was tested with soil erosion estimated from the Universal Soil Loss Equation (USLE) in the basin using by GIS data. The results show that the estimated soil erosion and the designed soil deposit are $72.1\;m^3$ and $85.0\;m^3$ respectively and the size of sediment basin is proper. In this study the water depth was calculated from the Hec-Ras model to test the stability of the bank and to prove submersion of the inside fields from stream overflow.

• Journal of Soil and Groundwater Environment
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• v.10 no.2
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• pp.20-27
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• 2005

The seasonal variation of water quality was studied in the Hwabongcheon. It runs though a small catchment where shallow groundwater was contaminated with $NO_3-N$ by intensive livestock facilities. A direct inflow of animal waste and incoming of contaminated groundwater affected its water quality. In the dry season, an important factor of water quality in the Hwabongcheon was direct inflow of animal waste. In the wet season, concentrations of $NO_3-N$ in the Hwabongcheon were elevated in spite of being diluted by precipitation. It could be explained by the effect of increased incoming of contaminated groundwater and showed by oxygen and hydrogen isotope values. $NO_3-N$ concentration in the Cheongmicheon was lower than that in the Hwabongcheon, so it increased next a junction. This effect was intense in wet season because $NO_3-N$ concentration in the Hwabongcheon was high.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.4 no.2
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• pp.93-100
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• 1999

Analyzing the tide data taken at Kunsan inner and Outer ports, non-tidal and mean sea level and harmonic constants of major constituents are investigated to examine the effects of the dyke gate operation on the sea level change in Keum River estuary. Non-tidal and annual mean sea levels decrease at Kunsan Inner and Outer ports after the dyke gate operation, especially showing an abrupt drop of non-tidal sea level at Kunsan Inner port. This non-tidal sea level drop results in the mean sea level gradient change between the inner and outer port, which can be mainly explained in terms of the decrease of river discharge from the dyke. Amplitudes of the $M_2$ and $S_2$ tides at the Inner port increase after the dyke gate operation, showing an abrupt jump, and phases of both tides slightly decrease. Amplitude and phase of the $K_1$ and $O_1$ tides show slight changes after the dyke gate operation. This significant change of semi diurnal tide amplitude is believed as a result of superposition of incident tidal wave and reflected tidal wave from the dyke.

• Journal of Korea Water Resources Association
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• v.36 no.1
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• pp.117-128
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• 2003

The objectives of this study are to develop the total maximum daily loads simulation system, TOLOS that is capable of estimating annual nonpoint source pollution from small watersheds, to monitor the hydrology and water quality of the Balkan HP#6 watershed, and to validate TOLOS with the field data. TOLOS consists of three subsystems: the input data processor based on a geographic information system, the models, and the post processor. Land use pattern at the tested watershed was classified from the Landsat TM data using the artificial neutral network model that adopts an error back propagation algorithm. Paddy field components were added to SWAT model to simulate water balance at irrigated paddy blocks. SWAT model parameters were obtained from the GIS data base, and additional parameters calibrated with field data. TOLOS was then tested with ungauged conditions. The simulated runoff was reasonably good as compared with the observed data. And simulated water quality parameters appear to be reasonably comparable to the field data.