• Korean Journal of Environmental Agriculture
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• v.30 no.2
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• pp.144-152
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• 2011

BACKGROUND: Eutrophication occurs occasionally in flood control reservoirs around Juam lake in summer and early autumn. Lakeside macrophyte which is one of internal pollutants effects on water quality when it is submerged during water surface is rising after rainy season. METHODS AND RESULTS: To improve water the quality of water from water supply source and to establish the management plan of submerged plants in flood control reservoirs around Juam Lake, the removal and release velocities of nutrients by submerged plants in site 1 and 2 were investigated. Removal or release velocity constant (K) of COD by Carex dimorpholepis Steud in column was 0.07~0.18 $day^{-1}$ at 0~4 days after flooding, -0.23~-0.17 $day^{-1}$ at 5~19 days after flooding and -0.28~0.03 $day^{-1}$ at 20~33 days after flooding. Removal or release velocity constant (K) of T-N by Carex dimorpholepis Steud was 0.02 $day^{-1}$ at 0~4(8) days after flooding, -0.13~-0.10 $day^{-1}$ at 5(9)~33 days after flooding in column. Removal or release velocity constant (K) of T-P by Carex dimorpholepis Steud was 0.05~0.06 $day^{-1}$ at 0~4 days after flooding, -0.14~-0.09 $day^{-1}$ at 5~33 days after flooding. Release velocity constant (K) of nutrients by Miscanthus sacchariflorus Benth was lower than that by Carex dimorpholepis Steud. In site 1, the amount of nutrients release by Carex dimorpholepis Steud was 6,719 kg/month/area for COD, 2,397 kg/month/area for T-N and 466 kg/month/area for T-P. The amounts of nutrients release by Carex dimorpholepis Steud were higher than those by Miscanthus sacchariflorus Benth in both sites. CONCLUSION(s): The results of this study suggest that COD, T-N and T-P in water quality of Juam lake were strongly influenced by submerged plants in flood control reservoirs.

• Journal of Korea Water Resources Association
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• v.37 no.8
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• pp.653-662
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• 2004

In this study, the method of Increasing the flood control as well as conservation effects is studied by joint operation of Hwacheon and Peace Dam. After completing the second phase of the construction of the Peace Dam, the dam crest height will be increased from 225m and the storage capacity will also be increased. If storage capacity is increased and gates are installed, it will assist not only flood control but also conservation of the entire Han river basin. Considering the change of conservation levels, the change of the restricted water level of the Hwacheon Dam in flood season, and the inflow change into the Peace Dam through the simulated reservoir operation, the annual average power of Hwacheon Dam with 95% reliability, annual firm power, the volume of water supply is calculated. As a result, when the conservation level of the Peace Dam and the restricted water level of the Hwacheon Dam are increased, the generation capacity will be improved. However, even though the inflow decrease, the generation capacity will not be affected. If the inflow decrease under the same conditions, the water supply capability will be reduced to the range from 35% to 40%. It is necessary to increase conservation level to keep the same water supply capability.

• The Journal of the Korea Contents Association
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• v.7 no.3
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• pp.140-151
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• 2007

In this study, we attempted to develop a watershed runoff index subject to main control points by dividing the Geum River basin into 14 sub-basins. The Yongdam multipurpose dam Daecheong multipurpose dam and Gongju gage station were selected to serve as the main control points of the Geum River basin, and the observed flow of each control point was calculated by the discharge rating curve, whereas the simulated flow was estimated using the Rainfall Runoff Forecasting System (RRFS), user-interfaced software developed by the Korea Water Corporation, based on the Streamflow Synthesis and Reservoir Regulation (SSARR) model developed by the US Army Corps of Engineers. This study consisted of the daily unit observed flow and the simulated flow of the accumulated moving average flow by daily, 5-days, 10-days, monthly, quarterly and annually, and normal monthly/annually flow. We also performed flow duration analysis for each of the accumulated moving average and the normal monthly/annually flows by unit period, and abundant flow, ordinary flow, low flow and drought flow estimated by each flow duration analysis were utilized as watershed runoff index by main control points. Further, as we determined the current flow by unit period and the normal monthly/annually flow through the drought and flood flow analysis subject to each flow we were able to develop the watershed runoff index in a system that can be used to determine the abundance and scarcity of the flow at the corresponding point.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.744-748
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• 2008

우리의 삶의 터전이 도시화됨에 따라 수문현상에도 많은 변화가 생겼다. 이로 인해 기존의 수문해석을 위한 방법을 대신해 도시화된 유역의 새로운 수문해석 방법의 개발이 불가피하게 되었다. 이에 따라 본 연구에서는 도시유출 모형인 SWMM의 대표적 프로그램인 XP-SWMM을 이용하여 도시유역의 유출모의를 하였다. 대상유역으로 선정한 곳은가양천배수분구로 전형적인 도시 하천 유역모습을 하고 있다. 이 유역의 특성치와 확률강우량 산정 후 XP-SWMM 모형에 적용시켜 재현기간별 첨두홍수량을 구하고, 동일 유역을 HEC-HMS로 모의하여 그 차이를 분석하였다. 도시화가 진행되면서 대규모 시설 등이 들어서면서 도로와 인도가 포장되므로 침투는 감소하고, 따라서 유역내 조도계수가 감소되며, 수로망 정비 등에 의해 유입시간이 빨라져 첨두홍수량이 증가하게 되었다. 이와 같은 변화로 인해 기존 홍수량을 구하기 위한 방법의 변화는 필수 불가결하게 되었다. 따라서 본 연구의 중점과제인 저류지에 의한 홍수조절능력에 대한 분석은 대상 유역내에 일정한 크기의 저류지를 상 중 하류위치에 따라 지점선정 후 그에 따른 홍수량과 침수량의 변화를 비교..분석하여 저류지 위치별 홍수조절능력에 대한 평가를 실시하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.433-433
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• 2017

본 연구에서는 노후된 소규모 농업용저수지의 홍수에 대한 안전성이 부족하여 최근들어 노후된 소규모 농업용 저수지를 재설계하여 치수능력을 보강하고 있다. 이러한 노후 소규모 농업용 저수지의 홍수량을 재산정하기 위해 강우량을 수집하여 확률강우량을 재산정하고 빈도별 홍수량을 산정하였다. 산정된 빈도별 확률홍수량을 이용하여 현재의 치수적 안정성을 검토하고 현재기준에 적합한 저수지의 치수적 안정성을 갖추기 위해 댐을 증고하는 방안에 대해 검토하였다. 본 연구에서 저수지의 안정성을 검토한 결과 심천저수지의 홍수위는 200년 빈도에서 EL. 124.38m, 300년 빈도에서 EL. 124.43m 500년 빈도에서 EL. 124.48m로 현재 댐마루고 EL. 125.60m와 비교시 월류는 하지 않으나 댐설계기준(2011,국토해양부)에서 제시된 식에 따른 여유고와 비교한 결과 현재 상태에서는 여유고가 부족하여 증고가 필요한 것으로 분석되었다. 따라서 심천저수지의 현재 홍수량에 대한 검토를 위해 100년, 80년, 50년 빈도의 저수지 홍수추적결과 심천저수지의 여유고는 100년 빈도에서 0.028m부족, 80년 빈도에서 0.007m부족, 50년 빈도에서 기준여유고를 0.046m 만족하여 현재 상태에서는 50년 빈도에서 안정한 것으로 검토되었다.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.2
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• pp.271-277
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• 2011

To improve the quality of water from water supply source and to establish the management plan of dead plants in flood control reservoir around Juam Lake, the effect of water quality by dead plant in column with passing time was investigated. In column test, the amounts of release by Carex dimorpholepis were $7,893-7,917mg\;m^{-2}\;month^{-1}$ COD, $2,711-2,816mg\;m^{-2}\;month^{-1}$ T-N and $342-547mg\;m^{-2}\;month^{-1}$ T-P. The amounts of release by Miscanthus sacchariflorus were $6,487-6,507mg\;m^{-2}$ COD, $1,813-1,868mg\;m^{-2}$ T-N and $226-405mg\;m^{-2}\;month^{-1}$ T-P in column. Therefore, the release of COD, T-N and T-P by Carex dimorpholepis were more than those by Miscanthus sacchariflorus Benth in column.

• Explosives and Blasting
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• v.21 no.3
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• pp.23-35
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• 2003

An analytical diffusion model for flood routing with backwater effects and lateral flows is developed. The basic diffusion equation is linearized about an average depth of (H + h), and is solved using the boundary conditons which take into account the effects of backwater and lateral flows. Scouring phenomenon around pier which affects on the support function of pier and the stabilization if river bed is a complex problem depending on flow properties and river bed state as well as pier geometry. therefore, there is no uniting theory at present which would enable the designer to estimate, with confidence, the depth of scour at bridge piers. The various methods used in erosion control are collectively called upstream engineering, HEC-RAS Model, underwater blasting. They consist of reforestation, check-dam construction, planting of burned-over areas, contour plowing and regulation of crop and grazing practices. Also included are measures for proper treatment of high embankments and cuts and stabilization of streambanks by planting or by revetment construction. One phase of reforestation that may be applied near a reservoir is planting of vegetation screens. Such screens, planted on the flats adjacent to the normal stream channel at the head of a reservoir, reduce the velocity of silt-laden storm inflows that inundate these areas. This stilling action causes extensive deposition to occur before the silt reaches the main cavity of the reservoir.

• Journal of Korea Water Resources Association
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• v.46 no.7
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• pp.719-733
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• 2013

In this study, a watershed-based surface-water and groundwater integrated model, SWAT-MODFLOW was used to evaluate streamflow depletion induced by groundwater withdrawals and irrigation reservoirs for the Juksan-cheon watershed in South Korea. The streamflow responses to groundwater pumping and irrigation reservoirs were simulated under several different scenarios. The scenarios were (1) current pumping well withdrawals with reservoirs; (2) current pumping well withdrawals without reservoirs; (3) no pumping well withdrawals with reservoirs; (4) no pumping well withdrawals without reservoirs (natural condition). The simulated results indicated that the effects of groundwater pumping on streamflow depletion are a little more significant than those of irrigation reservoirs. Particularly, the groundwater withdrawals with irrigation reservoirs at current status (scenario 1) has induced the decrease of more than 20% in drought flow against the natural condition (scenario 4) at the outlet of the watershed. The specific drought flows through the main stream of Juksan-cheon watershed were simulated in order to assess the irrigation effects on downstream flows. It was found out that the specific drought flows are increasing as the distance from the reservoir increases due to the accumulation of the return flows to stream.

• Journal of Korea Water Resources Association
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• v.49 no.4
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• pp.327-333
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• 2016

Due to climate changes accelerated by global warming, South Korea has experienced regional climate variations as well as increasing severities and frequencies of extreme weather. The precipitation in South Korea during the summer season in 2013 was concentrated mainly in the central region; the maximum number of rainy days were recorded in the central region while the southern region had the minimum number of rainy days. As a result, much attention has been paid to the importance of flood control due to damage caused by spatiotemporal intensive rainfalls. In this study, forecast rainfall data was used for rapid responses to prevent disasters during flood seasons. For this purpose, the applicability of numerical weather forecast data was analyzed using the ground observation rainfall and inflow rate. Correlation coefficient, maximum rainfall intensity percent error and total rainfall percent error were used for the quantitative comparison of ground observation rainfall data. In addition, correlation coefficient, Nash-Sutcliffe efficiency coefficient, and standardized RMSE were used for the quantitative comparison of inflow rate. As a result of the simulation, the correlation coefficient up to six hours was 0.7 or higher, indicating a high correlation. Furthermore, the Nash-Sutcliffe efficiency coefficient was positive until six hours, confirming the applicability of forecast rainfall.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.3
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• pp.155-165
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• 2010

In low-lying districts of urban areas, pump stations were built to protect flooding by the heavy rain. Particularly, the automatic pump operation system was installed for efficiency in the pump stations of Seoul. However, the effective pump operation is difficult under existing operating system because the system only performs operation by reservoir depth. This study would like to improve the real time operating system suggested by Jun et al.(2007) and to apply the system Gasan 1 pump station in Seoul. For various design rainfall events, maximum water levels simulated by the suggested system were 10~70cm lower than results by the existing system. And overflow volume at upstream manholes were 50% reduced. We converted the flood control effects by establishment of the suggested system to economic indicators. To obtain the same effect, approximately 4.9 billion won needs to expand pump capacities or 3.2~6.9 hundreds million won needs to construct storm water detention on upstream area. The suggested system could improve the flood control stability by efficient operation of the existing pump station.