• 한국농공학회논문집
• /
• 제57권5호
• /
• pp.113-122
• /
• 2015

This study aims to evaluate future stream flow by the operation of agricultural reservoir group at the upper stream of the Miho River. Four agricultural reservoirs with storage capacities greater than one million cubic meters within the watershed were selected, and the RCP 8.5 climate change scenario was applied to simulate reservoir water storage and stream flow assuming that there are no changes in greenhouse gas reduction. Reservoir operation scenarios were classified into four types depending on the supply of instream flow, and the water supply reliability of each reservoir in terms of water supply under different reservoir operation scenarios was analyzed. In addition, flow duration at the watershed outlet was evaluated. The results showed that the overall run-off ratio of the upper stream watershed of the Miho River will decrease in the future. The future water supply reliability of the reservoirs decreased even when they did not supply instream flow during their operation. It would also be difficult to supply instream flow during non-irrigation periods or throughout the year (January-December); however, operating the reservoir based on the operating rule curve should improve the water supply reliability. In particular, when instream flow was not supplied, high flow increased, and when it was supplied, abundant flow, ordinary flow, and low flow increased. Drought flow increased when instream flow was supplied throughout the year. Therefore, the operation of the agricultural reservoirs in accordance with the operating rule curve is expected to increase stream flow by controlling the water supply to cope with climate change.

• 농업과학연구
• /
• 제38권2호
• /
• pp.331-341
• /
• 2011

To provide variation of water supply for instream flow from reservoirs with various magnifications of paddy irrigation area to watershed area, 8 reservoirs were selected to draw operation rule curve and to analyze water supplies from reservoirs. Reliability of 90% for supplying irrigation water from reservoir was able to maintain and instream flow water was able to be supplied only in the reservoir with magnification of paddy irrigation area to watershed area above 3. The more magnification of paddy irrigation area to watershed area increased, the more ratio of irrigation water to total water storage decreased, and the more ratio of instream flow water to total water storage increased. From the heightening 113 reservoirs in Korea, annual irrigation water was estimated to 1,146.05 $Mm^3$ in normal operation, 839.57 $Mm^3$ in withdrawal limited operation, and annual instream flow water was estimated to 149.68 $Mm^3$ in normal operation, 283.19 $Mm^3$ in withdrawal limited operation. It was concluded that withdrawal limited operation was followed to have the premise of saving irrigation water, more instream flow water was able to be supplied from reservoirs with high magnification of paddy irrigation area to watershed area.

• 농업과학연구
• /
• 제37권3호
• /
• pp.481-490
• /
• 2010

Baekgog reservoir is located in Jincheon county, Chungbuk province, of which full water levels will be heightened from EL. 100.1 m to EL. 102.1 m, and total storages from 21.75 $Mm^3$ to 26.67 $Mm^3$. The simulation for reservoir inflow was conducted by DAWAST model. The annual average irrigation water was estimated to 33.19 $Mm^3$ supplied to 2,975 ha and the instream flows could be allocated with 0.14 mm/d from October to April with annual average of 2.52 $Mm^3$. The operation rule curve was drawn using inflow, irrigation, and instream flow requirements data. The reservoir water storage was simulated on a daily basis in case of both normal and withdrawal limit operation. In case of normal operation, the annual average irrigation water supply increased from 31.95 $Mm^3$ to 33.32 $Mm^3$, the instream water supply from 2.40 $Mm^3$ to 2.44 $Mm^3$, the water storages from 15.74 $Mm^3$ to 19.88 $Mm^3$, and the water supply reliability from 77.3 % to 81.6 %. In case of operation with withdrawal limit, the amount of instream water supply was 2.52 $Mm^3$ from reservoir regardless of the condition while the water storage increased from 16.77 $Mm^3$ to 20.65 $Mm^3$. The irrigation water supply capacity was appropriate for the case of normal operation with 2 m heightened condition. The present instream water supply capacity was 35,000 $m^3$/d (6.86 $Mm^3$/y) while 42,000 $m^3$/d (8.36 $Mm^3$/y) in 2 m heightened condition in case of withdrawal limit operation.

• 농업과학연구
• /
• 제38권1호
• /
• pp.163-172
• /
• 2011

To provide the operation rule curve for suppling instream flow to urban stream from reservoir, the Soho reservoir with watershed area of 7.4 $km^2$ and total water storage of 2.58 $Mm^3$ was planned at the headwaters of the Daejeoncheon. Daily streamflow was simulated and using the simulated streamflow and desired instream flow, the operation rule curve by Senga method was drawn and evaluated through reservoir operation. Senga method is derived by accumulating the differences between streamflow and desired instream flow adversely. Water storages were simulated on a daily basis to supply urban instream flow from Soho reservoir, but the amount of supplying instream flow to urban stream was not nearly increased comparing with that of normal operation that does not used the rule curve. Thereafter the new simulation-based operation rule curve was derived and applied to supply instream flow from Soho reservoir. In normal operation, the amount of instream flow was shown to 15,000 $m^3$/d, but it was increased to 27,700 $m^3$/d in withdrawal limited operation using the new derived rule curve, in which the applicability of this rule curve was proved. Also comparing with the flow duration curves at station just before urban Daejeoncheon stream without and with upstream Soho reservoir, the 95th flow was decreased from 1.64 mm/d to 1.51 mm/d, and the 355th flow was increased from 0.17 mm/d to 0.30 mm/d. Monthly streamflows during October to March were increased from 10.6~24.1 mm to 24.1~34.0 mm with the increasing rate of 141~227%.

• 한국농공학회:학술대회논문집
• /
• 한국농공학회 2003년도 학술발표논문집
• /
• pp.471-474
• /
• 2003

An attempt was made to evaluate on water supply capability of river management flow of four agricultural dam at the Yongsan River which is required instream flow because of water pollution. As a result, supply capability of agricultural use was sufficient, but supply capability of river management flow was insufficient.

• 한국농공학회논문집
• /
• 제57권4호
• /
• pp.73-84
• /
• 2015

An embankment raising project on 113 agricultural reservoirs in Korea was implemented in 2009 to increase water supply capacity for agricultural water and instream uses. This study evaluated the future water supply capacity of the Imgo reservoir at which the agricultural reservoir embankment raising project was completed, considering climate change scenarios. The height of the embankment of the reservoir was increased by 4.5 m, thereby increasing its total storage from 1,657.0 thousand to 3,179.5 thousand cubic meters. To simulate the reservoir water storage with respect to climate changes, two climate change scenarios, namely, RCP 4.5 and RCP 8.5 (in which greenhouse gas reduction policy was executed and not executed, respectively) were applied with bias correction for reflecting the climate characteristics of the target basin. The analysis result of the agricultural water supply capacity in the future, after the agricultural reservoir embankment raising project is implemented, revealed that the water supply reliability and the agricultural water supply increased, regardless of the climate change scenarios. By simulating the reservoir water storage considering the instream flow post completion of the embankment raising project, it was found that water shortage in the reservoir in the future is not likely to occur when it is supplied with an appropriate instream flow. The range of instream flow tends to decrease over time under RCP 8.5, in which the greenhouse gas reduction policy was not executed, and the restoration of reservoir storage was lower in this scenario than in RCP 4.5, in which greenhouse gas reduction policy was executed.

• 한국환경과학회지
• /
• 제16권5호
• /
• pp.649-655
• /
• 2007

This study was focused on estimating instream flow, and its optimal alternative for securing the required total amount of instream flow was also researched in order to restore ecosystems and riverine aesthetics of the Mugeo Stream. the first tributary of the Taewha River flowing through the center of Ulsan. In this study the hydraulic and hydrologic conditions and water quality were investigated at specific channel reaches and representative stations of the Mugeo Stream to determine a proper estimate of instream flow. And riverine functions, such as the minimum flow, water duality conservation, fish habitat, and recreation, were considered to restore the environmental functions of the stream, As a result, the total amount of $11,500m^3/day$ was set as the target instream flow for the Mugeo Stream. It was chosen as the optimal alternative for securing the total external supply of $10,000m^3/day$ which have to be transfered from the riverbed flow diverted through the Taewha Main river at upstream of Samho bridge. The water duality throughout the Mugeo Stream channels will be improved considerably to 3-4 mg/l of BOD standard if the target instream flow is supplied and sewage is intercepted by the sanitary sewage system.

• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2005년도 학술발표회 논문집
• /
• pp.52-59
• /
• 2005

The goal of this project is to estimate the instream flow of the Han River Basin to ensure the adequate supply of suitable quality water for preservation and enhancement of aquatic ecosystems. A applied model is Physical Habitant Simulation System(PHABSIM) of Instream Flow Incremental Methodology(IFIM). The parameters which are needed to simulation by PHABSIM such as flow depth, velocity distribution and channel cover with cross section data are obtained by field survey. The Habitat Suitability Criteria with the application of univariate curve on Zacco platypus as a target species was able to be established by conducting the field investigation. The estimated results of ecological recommended instream flow by this study has important meanings that the future river management have to seriously take into account for the natural environment and functions of river system.

• 한국환경과학회지
• /
• 제26권9호
• /
• pp.1031-1043
• /
• 2017

Recently severe drought caused the water shortage around the western parts of Chungcheongnamdo province, South Korea. A Diversion tunnel from the Geum river to the Boryong dam, which is the water supply dam for these areas has been proposed to solve this problem. This study examined hydraulic impacts on the Geum river associated with the diversion plan assuming the severe drought condition of 2015 would persist for the simulation period of 2016. The hydraulic simulation model was verified using hydrologic and hydraulic data including hourly discharges of the Geum river and its 8 tributaries, fluctuation of tidal level at the mouth of the river, withdrawals and return flows and operation records of the Geum river barrage since Feb. 1, 2015 through May 31, 2015. For the upstream boundary condition of the Geum river predicted inflow series using the nonlinear regression equation for 2015 discharge data was used. In order to estimate the effects of uncertainty in inflow prediction to the results total four inflow series consisting of upper limit flow, expected flow, lower limit flow and instream flow were used to examine hydraulic impacts of the diversion plan. The simulation showed that in cases of upper limit and expected flows there would be no problem in taking water from the Geum river mouth with a minimum water surface level of EL(+) 1.44 m. Meanwhile, the simulation also showed that in cases of lower limit flow and instream flow there would be some problems not only in taking water for water supply from the mouth of the Geum river but also operating the diversion facility itself with minimum water surface levels of EL(+) 0.94, 0.72, 0.43, and 0.14 m for the lower limit flow without/with diversion and the instream flow without/with diversion, respectively.

• 농업과학연구
• /
• 제36권1호
• /
• pp.87-98
• /
• 2009

대전 3대 하천의 하나인 갑천의 유등천 합류전 지점의 하천유지유량 확보를 위해 상류 유역에 금곡지와 괴곡지를 각각 설치하는 경우 각각 장안지, 방동지의 기존 저수지를 포함하여 직렬, 병렬 연계 운영을 반영하여 목표 지점의 유량을 1966년부터 2007년까지 모의하여 효과를 분석한 결과 다음과 같다. 첫째, 방동지-금곡지 직렬 연계에 의해 금곡지로부터 용수공급능력을 분석한 결과 연평균하여 하천유지유량 공급량은 6.83백만 $m^3$, 용수공급량/유역면적은 403.4 mm, 단위유역 용수공급량/강우량 비율은 33.0 %, 용수공급량/유입량 비율은 96.4 %, 용수공급량/저수량 비율은 81.9 %, 유입량/저수량 비율은 112.3 %였다. 둘째, 장안지-금곡지 병렬 연계를 고려한 갑천지점의 유량을 분석한 결과 유황은 연평균하여 풍수량 $4.806m^3/s$, 평수량 $2.217m^3/s$, 저수량 $1.140m^3/s$, 갈수량 $0.887m^3/s$로 분석되었으며, 평균갈수량은 목표유량 $1.486m^3/s$보다 $0.599m^3/s$ 적게 나타났다. 셋째, 장안지-방동지 병렬 연계에 의해 괴곡지 유입량을 모의하였고, 괴곡지로부터 용수공급능력을 분석한 결과 연평균하여 하천유지유량 공급량은 49.60백만 $m^3$, 용수공급량/유역면적은 246.5 mm, 단위유역 용수공급량/강우량 비율은 19.4 %, 용수공급량/유입량 비율은 40.8 %, 용수공급량/저수량 비율은 412.1 %, 유입량/저수량 비율은 1,189.8 %였다. 넷째, 괴곡지 방류를 고려한 갑천 지점의 유량을 분석한 결과 유황은 연평균하여 풍수량 $4.501m^3/s$, 평수량 $2.277m^3/s$, 저수량 $1.743m^3/s$, 갈수량 $1.564m^3/s$로 분석되었으며, 평균갈수량은 목표유량 $1.486m^3/s$보다 $0.078m^3/s$ 높게 나타났다. 요약하면 괴곡지를 설치하는 것이 금곡지를 설치하는 것보다 갑천 지점의 하천유지유량을 확보하는데 효율성이 높은 것으로 분석되었다.