• Journal of Environmental Impact Assessment
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• v.18 no.5
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• pp.293-299
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• 2009

Wintering migratory species of white-fronted geese (Anser albifrons) are common visitor in South Korea, and this study examined the survivorship of white-fronted geese in the Junam Reservoir with the application of Population Viability Analysis (PVA) technique. In Junam PVA analysis was done for the next 50 years using factors of breeding population, sex ratios, survivorship in the VORTEX program. As a result white-fronted geese will reach to carrying capacity within 40 years, and population will reach to carrying capacity later when it becomes smaller. Also with a large initial population white-fronted geese will reach to carrying capacity earlier. In conclusion, for the next 50 years the white-fronted geese are expected to a long-term survival with stable condition with survivorship (0.03) and extinction rate (0.0).

• Journal of The Korean Society of Agricultural Engineers
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• v.63 no.5
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• pp.49-62
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• 2021

The objective of this study was to evaluate the flood control capacity of the agricultural reservoir based on state-of-the-art climate change scenario - SSP (Shared Socioeconomic Pathways). 18 agricultural reservoirs were selected as the study sites, and future rainfall data based on SSP scenario provided by CMIP6 (Coupled Model Intercomparison Project 6) was applied to analyze the impact of climate change. The frequency analysis module, the rainfall-runoff module, the reservoir operation module, and their linkage system were built and applied to simulate probable rainfall, maximum inflow, maximum outflow, and maximum water level of the reservoirs. And the maximum values were compared with the design values, such as design flood of reservoirs, design flood of direct downstream, and top of dam elevation, respectively. According to whether or not the maximum values exceed each design value, cases were divided into eight categories; I-O-H, I-O, I-H, I, O-H, O, H, X. Probable rainfall (200-yr frequency, 12-h duration) for observed data (1973~2020) was a maximum of 445.2 mm and increased to 619.1~1,359.7 mm in the future (2011~2100). For the present, 61.1% of the reservoirs corresponded to I-O, which means the reservoirs have sufficient capacity to discharge large inflow; however, there is a risk of overflowing downstream due to excessive outflow. For the future, six reservoirs (Idong, Baekgok, Yedang, Tapjung, Naju, Jangsung) were changed from I-O to I-O-H, which means inflow increases beyond the discharge capacity due to climate change, and there is a risk of collapse due to dam overflow.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.1 no.1
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• pp.69-76
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• 1981

The predictive equations for reservoir sedimentation rate now in use are extensively reviewed, and the equation of multiple regression type, in which the reservoir sedimentation rate is related with the watershed area and the trap-efficiency, is proposed based on the 113 irrigation reservoir resurvey data. The predictive relation so obtained proved to be a reasonable measure for the estimation of reservoir sedimentation rate. The relationship of sediment yield with the watershed area and with the reservoir trap efficiency is also analyzed. The variations of sedimentation rate and of the annual reservoir capacity loss rate was shown to heavily depend on the trap-efficiency of a reservoir. Besides, the effect of sedimentation on stream channels is confirmed and quantified based on the predictive equation derived in the present study.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2003.10a
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• pp.495-498
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• 2003

In order to analyze water supply capacity in estuary barrage dam, a system was developed in which base model was consisted of daily water balance model and daily inflow model. Agricultural water demand to paddy fields and domestic and industrial water demand were considered in this daily water balance model. Also outflow volume through sluice gate and inside water level at time to start outflow was conditioned initially to simulate reservoir storage. The DAWAST model was selected to simulate daily reservoir inflow in which return flows from agricultural, domestic and industrial water were included to simulate runoff. Using this developed system, water supply capacity in the Keum river estuary reservoir was analyzed.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.1
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• pp.1-6
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• 2017

Total capacity of pumped hydro storage(PHS) in Korean power system reaches 4,700MW, though the share of it is about 4.56% of total capacity The Unit Commitment program, E-terracommit which is used for the operational purpose by KPX, includes the PHS model. But the model has a defect that it does not include the information of water level of upper reservoir. Therefore two types of improved the PHS models are represented in this paper. The first model is a optimized model by connecting the upper reservoir water level to the non-spinning reserve. The other model is to have priority allocate both the PHS and combined cycle generator for non-spinning reserve. The proposed two models and the E-terracommit model is compared and resulting to have improvement in estimating non-spinning reserve when using the proposed models.

• Water for future
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• v.17 no.2
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• pp.107-112
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• 1984

It si presented here that in order to estimate reservoir sedimentation rate through the use of reservoir survey data of 66 irrigation reservoir in 3 major watersheds in this country, the correlation between reservoir sedimentation rate and the following factors; watershed area, trap-efficiency, watershed slope, shape factor of water shed, and reservoir deposition age in two models simple regression model and multiple regression model. Appropriatness of the proposed models have been calibrated from the survey data and as a result, it has been determined that the multiple regression model is much more accurate than the simple regression model. The annual sediment yield is correlated with watershed area and reservoir trap efficiency. It has been found that variation of the annual average sedimentation rate and the annual reservoir capacity loss rate are influenced by the trap efficiency of reservoir.

• Korean Journal of Agricultural Science
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• v.36 no.1
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• pp.87-98
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• 2009

The objective of this study is to evaluate the effect of increasing instream flow at Gapcheon stream of Daejeon city by considering two virtual reservoirs upstream, respectively; Geum-gok reservoir and Koe-gok reservoir upstream, respectively. The paralleled and cascaded reservoir operations were performed including the existing Jang-an and Bang-dong reservoirs. The results are summarized as follows. Firstly, from the Bang-dong and Geum-gok cascaded reservoir's water balance analysis, instream flow of $6.83Mm^3$ was able to be supplied to downstream, and water supply indexes of Geum-gok reservoir were analyzed to have the rate of water supply divided by watershed area of 403.4 mm, the rate of water supply divided by rainfall of 33.0 %, the rate of water supply divided by inflow of 96.4 %, the rate of water supply divided by storage capacity of 81.9 %, and the rate of inflow divided by storage capacity of 112.3 %. Secondly, from the Jang-an and Geum-gok paralleled reservoir's water balance analysis, flow durations at Gapcheon station were analyzed to have Q95 (the 95th high flow) of $4.806m^3/s$, Q185 (the 185th high flow) of $2.217m^3/s$, Q275 (the 275th high flow) of $1.140m^3/s$, and Q355 (the 355th high flow) of $0.887m^3/s$. Thirdly, inflow to Koe-gok reservoir was simulated including the Jang-an and Bang-dong paralleled reservoir's water balance analysis, instream flow of $49.60Mm^3$ was able to be supplied from Koe-gok reservoir to downstream, and water supply indexes of Koe-gok reservoir were analyzed to have the rate of water supply divided by watershed area of 246.5 mm, the rate of water supply divided by rainfall of 19.4 %, the rate of water supply divided by inflow of 40.8 %, the rate of water supply divided by storage capacity of 412.1 %, and the rate of inflow divided by storage capacity of 1,189.8 %. Fourthly, daily streamflows at Gapcheon stream were simulated including outflows from Koe-gok reservoir, flow durations at Gapcheon station were analyzed to have Q95 (the 95th high flow) of $4.501m^3/s$, Q185 (the 185th high flow) of $2.277m^3/s$, Q275 (the 275th high flow) of $1.743m^3/s$, and Q355 (the 355th high flow) of $1.564m^3/s$. The conclusion appeared that the effect of increasing instream flow at Gapcheon stream from Koe-gok reservoir was more higher than that from Geum-gok reservoir.

• Journal of The Korean Society of Agricultural Engineers
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• v.55 no.3
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• pp.13-24
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• 2013

Agriculture is affected directly by climate conditions and changes, and it is necessary to understand the impact of climate change on agricultural reservoirs which are the main water resources for paddy fields in Korea. This study aimed to evaluate the impact of climate change on the anti-drought capacity including water supply capability (WSC) and drought response ability (DRA) of agricultural reservoirs based on RCP (Representative Concentration Pathway) 4.5 and 8.5 scenarios of CanESM2 (The Second Generation Earth System Model) provided by CCCma (Canadian Center for Climate Modeling and Analysis). The WSC and DRA were estimated using frequency analysis and runs theory. The six reservoirs (Yooshin, Nogok, Kumsung, Songgok, Gapyung, Seoma) were selected considering geographical characteristics and design criteria of reservoir capacity. In case of Seoma reservoir, more than 10 year drought return period (DRP), the variation of the WSC was estimated larger than the others. In case of Yooshin reservior (2~5 DRP) DRC was decreased in 2025s under RCP8.5. These results could be utilized for agricultural reservoirs management and future design criteria considering climate change impacts on paddy irrigation.

• Magazine of the Korean Society of Agricultural Engineers
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• v.10 no.2
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• pp.1443-1453
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• 1968

The reservoir is one of the important partsof facilities for development of irrigation water in Korea. Accordingly, construction of the reservoir will be stressed in the field of future development of agricultural water resources. In the meantime, storage capacity is actually is limited to some extent with various conditions. Acreage of benefited area shall be determined according to such conditions as catchment area, precipitation and unit water requirment within benefited area. According to results of the past construction of the reservoir, the ratio of catchment area to benefited area would be 4:1 to 2.5:1 or catchment area is approximately 2.5 times larger and over than benefited area. In order words, it is the ordinary practice in the construction of reservoir that benefited area should be less than 1/2.5 times as large as catchment area. Moreover, limitation of catchment area would prevent largely the vast drought-stricken area from being benefited by irrigation facilites. This has been, in fact, caused by the fact that a good deal of water stored in the reservoir overflows wastefully through spillway of the reservoir at th time of flood season, and that only very little of the overflowed water is available for irrigation. However, if the more wasted water is stored during the flood season, the larger area of farmland can irrigated. That is, catchment area can reduced to less than 2.5 times as large as benefited area. On the other hand, it is afraid that such reduction should bring about the increase of unit storage capacity. And storage capacity being maximized, costs for construction of the reservoir will be raised too highly, thus making the economics feasibility unfavorable. The purpose of this study is to decide the ratio of catchment area to benefited area toward the minimum level as possible in consideration of the hydrological and economic aspects. Kopung Project which is located in Sosan-kun, Chungnam Province is taken as an example for the review and analysis in this study, and as an example for crop, rice is taken. After consideration of this project, we can find out that annual average inflow is 726mm and annual average water requirements is 811mm. And the ratio of catchment area to benefited area is 1.2:1. This means that catchment area can be reduced even to 1.2 times as large as benefited area. In conclusion, this study reveals that the construction of reservoir is feasible in view of economic and technical points provided that catchment area is more than 1.5 times as large as benefited area.

• Water for future
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• v.28 no.6
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• pp.217-228
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• 1995

For optimal reservoir operation during flood period, a general and systematic policy is suggested to make balance of the conflicting purposes between water conservation and flood control. The purpose of this study is to decide the restricted water level of the reservoir during flood period specially to meet water demand in non-flood period. The optimal policy is derived by reallocation of storage capacity through the application of variable restricted water level(VRWL) and minimum required water level(MRWL) for shorter intervals. This study also suggests water level dconditions to secure conservation storage capacity at the end of the flood period estimated by reservoir operation study. This paper illustrates an application of the Daecheong Dam and Chungju Dam respectively during flood and the results are reviewed.