• KCID journal
• /
• v.18 no.1
• /
• pp.68-80
• /
• 2011

To provide a operation rule curve for reservoir with low ratio of watershed area to paddy field area, Duckyong reservoir with watershed area of $15.8km^2$ and paddy field area of 1,071ha was selected, in which 4 meters are being heightened and full water levels will be increased from EL.26.0m to EL.30.0m, total water storages from 365.6M $m^3$ to 708.0M $m^3$. There was no operation rule curve that satisfied over 90% reliability of water supply in reservoir with watershed area of 1.48 times of paddy field area. The differences between observed and simulated reservoir daily water storages were minimized to determine parameters for simulating reservoir inflow in case of paddy field area of 550ha from 1991 to 2010. A operation rule curve was drawn to have a maximum storage with total water storage, which was in paddy field area of 700ha with ratio of 2.3 between watershed area and paddy field area. This case showed that annual irrigation water supply was 668M $m^3$ and instream flow of 57M $m^3$, water supply reliability of 55.6% in normal operation, and annual irrigation water supply was 605M $m^3$ and instream flow of 38M $m^3$, water supply reliability of 95.6% in withdrawal limited operation. Water supply reliabilities showed 35.6% without flood regulation and 17.8% with flood regulation in existing reservoir before heightening.

• Journal of Korea Water Resources Association
• /
• v.37 no.11
• /
• pp.915-927
• /
• 2004

The purpose of this paper is to estimate the instream flow of the South Han River Basin to ensure an adequate supply of suitable quality of water for preservation and enhancement of aquatic ecosystems. Proposed methods is Physical Habitant Simulation System of Instream Flow Incremental Methodology. Accurate estimation on a water depth and a velocity distribution was acquired by applying a two dimensional hydrodynamic model for a simulation of a hydraulic parameter necessary for the habitat evaluation to be used in a physical habitat simulation system. The Habitat Suitability Criteria with the application of univariate curve on zacco platypus as a representative fish was able to be established by conducting a field investigation. The establishment of a hydrological materialistic balance between upper and lower streams was confirmed by conducting a simulation simultaneously together with a mainstream section, which was excluded from the considered sections for the inhabitation evaluation of fish.

• KCID journal
• /
• v.17 no.2
• /
• pp.57-70
• /
• 2010

This study was performed to analyze the affect of water supply capacity followed by allocating flood control volume in heightening reservoir, of which Baekgog reservoir was selected as a case study in here. Baekgog reservoir is located in Jincheon county, Chungbuk province, of which full water level will be heightened from EL. 100. 1m to EL. 102.1m, and total storage from 21.75M $m^3$ to 26.67M $m^3$. Flood inflow with 200year frequency was estimated to 997 $m^3$/s in peak flow and 22.54M $m^3$ in total volume. Reservoir flood routing was conducted to determine flood limited water levels, which was determined to have scenarios such as EL 97-98-99m in periods of 6.21.-7.20., 7.21.-8.20., and 8.21.-9.20., respectively, EL 97-97-97m, EL 98-98-98m in present reservoir, and EL 99-100-101m, EL 99-99-99m, and EL 100-100-100m in heightened reservoir. Reservoir inflow was simulated by DAWAST model. Annual paddy irrigation requirement was estimated to 33.19M $m^3$ to 2,975ha. Instream flow was allocated to 0.14mm/d from October to April. Operation rule curve was drawn using inflow, irrigation and instream flow requirements data. In case of withdrawal limit reservoir operation using operation rule curve, reduction rates of annual irrigation supply before and after flood control by reservoir were 2.0~4.3% in present size and 1.5~3.6% in heightened size. Reliability on water supply was decreased from 77.3% to 63.6~68.2% in present size and from 81.6% to 72.7~79.5% in heightened size. And reduction rates of water storage at the end of year before and after flood control by reservoir were 7.3~16.5% in present size and 7.7~16.9% in heightened size. But water supplies were done without any water deficiency through withdrawal limit reservoir operation in spite of low flood regulating water level.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2006.05a
• /
• pp.467-471
• /
• 2006

At the current of the time, the ecologic stream is the most important concern of all the country. Daejeon metropolitan city performing the plan to secure the Daejeon cheon (stream) instream water as the 1st stage of the ecologic stream development plan for the Daejeon 3 main stream. During the performing the plan to secure the Daejeon cheon (stream) instream water, the water sources are decided to supply from Yudeng cheon and Daecheong Dam by the various water sources evaluation. For the investigation of flow and quality of instream water, I applicate the HEC-RAS and QUAL2EU. Instream water is proposed as the $10{\sim}30cm$ water depth and 2 degree water quality (lower the BOD 2.0 ppm) by the report of city. It is reasonable to the water depth objective, but the water quality objective is not reasonable because of the seasonal quality changes of supplied water. I suggest that the basin management plan include the non-point source elimination must comprised to the Daejeon ecologic stream project.

• Journal of Environmental Science International
• /
• v.16 no.8
• /
• pp.973-983
• /
• 2007

The eco-hydrologic effects of maintenance water supply on Oncheon stream are studied using hydrologic, hydraulic and ecologic models. SWMM (Storm Water Management Model) is used for long-term simulation of runoff quantity and water quality from Oncheon stream watershed. Using the output hydrologic variables from SWMM, HEC-RAS (River Analysis System) is then used to simulate the hydraulics of water flow through Oncheon stream channels. Such hydrologic, hydraulic and water quality output variables from SWMM and HEC-RAS are served as input data to execute PHABSIM (Physical Habitat Simulation) for the purpose of predicting the micro-habitat conditions in rivers as a function of stream flow and the relative suitability of those conditions to aquatic life. It is observed from the PHABSIM results that the weighted usable area for target fishes has the maximum value at $2m^3/s$ of instream flow. However, mid and down stream areas that have concrete river bed and covered region are unsuitable for fish habitat regardless of instream flow increment. The simulation results indicate that the simple maintenance water supply is limited in its effect to improve the ecological environment in Oncheon stream. Therefore, it is imperative to improve water quality and to recover habitat conditions simultaneously.

• Journal of Korean Society of Water and Wastewater
• /
• v.26 no.2
• /
• pp.285-294
• /
• 2012

Current urban stream conditions and their restoration projects were investigated by surveying the urban stream management experts in 29 cities with high population density (more than 1,000person/$km^{2}$). The survey results showed that the ratio of covered urban streams decreased by 1.4% (from 14% to 12.6%) in the last 5 years through steady river restoration projects promoted by governments. Nonetheless, 36.3% of 369 urban streams surveyed still report stream depletion problems; therefore, more efforts to alleviate the problems caused by distorted water circulation of urban streams are still necessary. Water depletion in many local urban streams, unlike national rivers, is accelerated due to negligence in stream management, budget shortage, and other reasons. To prevent stream depletion, the use of reclaimed water is suggested as one of the prevention plans. When available amounts of reused sewage are estimated through actual available nationwide sewage discharges of each watershed and instream flow of stream, annual instream flow supply of 780 million $m^{3}$ is expected; 4.8% reduction in the pollution load of public sewer treatment facilities is expected; and the creation of new value through water reuse service is expected. Thus, it is important for the reviews of feasibility and alternatives of water reuse projects for flow augmentation to consider not only investment budget reductions, but also environmental aspects. Also it is necessary to provide the financial support of unified government with strict water quality management policy.

• Journal of Korean Society of Environmental Engineers
• /
• v.38 no.3
• /
• pp.117-127
• /
• 2016

In this study, analyzed scenarios of the environmental instream flow for water quality improvement in Saemangeum watershed. In order to get an environmental instream flow, Methodology is selected for Retention-Basin, reservoir expansion, new dam construction, Modification of water intake and drainage system, Rearrangement of plan for system which Yongdam and Seomjin river dam have been used water supply. The study composed of diverse scenario of Environmental instream flow increasement and analyzed the effect of improving the water quality by the QUAL2K model and calculation of runoff for saemangeum watershed by SWAT model. The following water quality indicators have been simulated in irrigation and non-irrigation period for BOD and T-P. When scenarios applied to water quality model, Improvement rate in the water quality for Total Maximum Daily loads of Mankyung B unit watershed during irrigation and non-irrigation period is BOD (28.70%), T-P (17.09%) and BOD (28.51%), T-P (28.68%) respectively. Dongjin A unit watershed during irrigation and non-irrigation period is BOD (14.39%), T-P (14.59%) and BOD (15.54%), T-P (19.46%) similary. Simulation results is to quantify the constribution of the improvement in the water quality. In particular, It was demonstrative that improving effect for water quality was evaluated to be great in non-irrigation period.

• Korean Journal of Agricultural Science
• /
• v.36 no.1
• /
• pp.99-109
• /
• 2009

This study was performed to evaluate the effect of increasing instream flow at Nonsancheon stream of Nonsan city by securing water storages in upstream reservoirs; Ge-ryong, Gyoung-cheon, Dae-dun, and Tab-jeong. The paralleled and cascaded upstream reservoir operations for 8 storage securing scenarios were considered to simulate daily streamflows at Nonsan station. Using Tab-jeong reservoir water storage, the DAWAST model's parameters were determined, and the verified result showed Nash-Schcliffe's coefficient of 0.666. Instream flows were analyzed to supply maximum $59.85Mm^3$ on an annually average from upstream reservoir storage securing scenarios. The storage securing set of 2 m heightened Ge-ryong, 5 m Dae-dun, and 1 m Tab-jeong showed that the additional secured water storages were $17.132Mm^3$ and instream flow at Nonsan station was increased to $2.183m^3/s$, 2 times of present condition.

• Korean Journal of Agricultural Science
• /
• v.35 no.2
• /
• pp.225-235
• /
• 2008

The objective of this study is to evaluate the hydrological feasibility of heightening the Dae-ah reservoir in order to save instream flow at the Bong-dong station situated in the Mankyoung river. The results are summarized as follows. Firstly, from the Dong-sang and Dae-ah cascaded reservoir's water balance analysis, water supply indexes of the Dae-ah reservoir were analyzed to have the rate of water supply divided by watershed area of 1207.4 mm, the rate of water supply divided by rainfall of 95.8%, the rate of water supply divided by inflow of 153.1%, the rate of water supply divided by storage capacity of 236.1%, and the rate of inflow divided by storage capacity of 200.6%. Secondly, from the Dae-ah and Kyoung-cheon paralleled reservoir's water balance analysis, flow durations at the Bong-dong station were analyzed to have the Q95 (the 95th high flow) of $28.95m^3/s$, the Q185 (the 185th high flow) of $2.00m^3/s$, the Q275 (the 275th high flow) of $2.00m^3/s$, and the Q355 (the 355th high flow) of $0.82m^3/s$. Thirdly, in case of heightening the full water level of the Dae-ah reservoir of 10m, from the Dong-sang and Dae-ah cascaded reservoir's water balance analysis, water supply indexes of the Dae-ah reservoir were analyzed to have the rate of water supply divided by watershed area of 1220.7 mm, the rate of water supply divided by rainfall of 96.8%, the rate of water supply divided by inflow of 154.6%, the rate of water supply divided by storage capacity of 160.0%, and the rate of inflow divided by storage capacity of 137.0%. Fourthly, in case of heightening the full water level of the Dae-ah reservoir of 10m, from the Dae-ah and Kyoung-cheon paralleled reservoir's water balance analysis, flow durations at the Bong-dong station were analyzed to have the Q95 of $28.09m^3/s$, the Q185 of $1.79m^3/s$, the Q275 of $1.79m^3/s$, and the Q355 of $0.82m^3/s$. The conclusion appeared not to have the hydrological feasibility of heightening the Dae-ah reservoir from the reason that increased storage capacity does not increase water supply amount any more because of the high rate of the water supply divided by inflow.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.8 no.6
• /
• pp.121-128
• /
• 2008

Instream flows are defined as the stream flows needed to protect and preserve instream resources and values. They are supplied by the essential discharge for maintaining the channel. However, due to the lack of precipitation during the dry season, which is usually between the months of January and April, natural flows are not enough for the instream flows, thus leaving the dams at a shortage. In this paper, the method which will be discussed will show a physical way to improve water quality by the dilution of water that is supplied from a reservoir or dam, and how it is analyzed at the Han River basin. For the sake of this analysis, the basin has been divided into 33 catchments. Each catchment's natural flow has been simulated by SWAT-K, and the future water demand has been estimated using statistical data. It has also been assumed that the Han River basin has two large reservoirs(Chung-ju dam, and So-yang dam). The supply of potential discharge has been calculated using a case of water separately from each dam, as well as supply water from both dams.