• Journal of The Korean Society of Agricultural Engineers
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• v.62 no.4
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• pp.1-12
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• 2020

The extreme 2017 spring drought affected a large portion of South Korea in the Southern Gyeonggi-do and Chungcheongnam-do districts. This drought event was one of the climatologically driest spring seasons over the 1961-2016 period of record. It was characterized by exceptionally low reservoir water levels, with the average water level being 36% lower over most of western South Korea. In this study, we consider drought response methods to alleviate the shortage of agricultural water in times of drought. It could be to store water from a stream into a reservoir. There is a cyclical method for reusing water supplied from a reservoir into streams through drainage. We intended to present a decision-making plan for water supply based on the calculation of the quantity of water supply and leakage. We compared the rainfall-runoff equation with the TANK model, which is a long-term run-off model. Estimations of reservoir inflow during non-irrigation seasons applied to the Madun, Daesa, and Pungjeon reservoirs. We applied the run-off flow to the last 30 years of rainfall data to estimate reservoir storage. We calculated the available water in the river during the non-irrigation season. The daily average inflow from 2003 to 2018 was calculated from October to April. Simulation results show that an average of 67,000 tons of water is obtained during the non-irrigation season. The report shows that about 53,000 tons of water are available except during the winter season from December to February. The Madun Reservoir began in early October with a 10 percent storage rate. In the starting ratio, a simulated rate of 4 K, 6 K, and 8 K tons is predicted to be 44%, 50%, and 60%. We can estimate the amount of water needed and the timing of water pump operations during the non-irrigation season that focuses on fresh water reservoirs and improve decision making for efficient water supplies.

• Journal of Soil and Groundwater Environment
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• v.27 no.2
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• pp.24-35
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• 2022

This study was conducted to estimate groundwater demand and supply for agricultural activities in a frequent-drought area that requires implementation of optimal distribution plan utilizing the well-network system (WNS). The WNS has been considered as a viable strategic way of supplying groundwater to farmlands by connecting groundwater wells physically or virtually. The study area heavily relied on groundwater resources for irrigation up to 53% due to a lack of surface water resources. Two kinds of methods, HOMWRS software and FAO approach, were used for estimating irrigation water requirements for paddy and upland fields, respectively. During the latest 10 years (2010~2019), the water requirements was estimated to be 1,106 m³/day. The requirements notably increased to 1,121~4,004 m³/day during active farming season (May to September), which exceeded the total yield capacity of pre-existing groundwater wells (2,356 m³/day) in the area. Detailed and definite determination for groundwater demand and supply helped to determine optimal scale parameters of WNS. The WNS has achieved more balanced distribution of groundwater resources for irrigation over the study area.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2002.10a
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• pp.37-40
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• 2002

It is to show the problems of the existing techniques to estimate agricultural water demand and to suggest the new methods considering the water demand for non-irrigated area and decrease of water loss in canal. It is to suggest the methods to improve the techniques for estimating agricultural water demand and to analyze the water demand and supply according to the facilities capacity. Until now, the concept of per the unit used to estimate agriculture water demand is useful to estimate demand, but is insufficient to cope with the variations of conditions in future. And the paddy area of government is not realistic against a trend of decrease. Water demand decrease is caused by constructions of irrigation facilities as constructing of irrigation canal, but application loss ratio is fixed. Increase of the water demand owing to the increase of the yield per the unit area is also the actual condition which is not considered. The guide-line must contain these contents for a demand estimate.

• Journal of The Korean Society of Agricultural Engineers
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• v.47 no.3
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• pp.15-25
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• 2005

Ninety tow percent of over 1,800 gate controlled dams in Korea are classified as small dams. The primary purpose of these small dams is to supply irrigation water. Therefore, while large dams can store as much as 80 percent of precipitation and thus are efficient to control flood, small dams are often lack of flood control function resulting in increased susceptibility drought and flood events. The purpose of this study is to develope a storage management model for irrigation dams occupying the largest portion of small dams. The proposed Storage Management Model (STMM) can be applied to the Seongju dam for efficient management. Besides, the operation standard is capable of analyzing additional available water, considering water demand and supply conditions of watershed realistically. And the model can improve the flood control capacity and water utilization efficiency by the flexible operation of storage space. Consequently, if the small dams are managed by the proposed Storage management model, it is possible to maximize water resources securance and minimize drought and flood damages.

• Environmental Engineering Research
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• v.20 no.3
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• pp.290-297
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• 2015

This paper presents the evaluation of the impact of climate change on water resources and yield capacity of Asa and Kampe reservoirs. Trend analysis of mean temperature, runoff, rainfall and evapotranspiration was carried out using Mann Kendall and Sen's slope, while runoff was modeled as a function of temperature, rainfall and evapotranspiration using Artificial Neural Networks (ANN). Rainfall and runoff exhibited positive trends at the two dam sites and their upstream while forecasted ten-year runoff displayed increasing positive trend which indicates high reservoir inflow. The reservoir yield capacity estimated with the ANN forecasted runoff was higher by about 38% and 17% compared to that obtained with historical runoff at Asa and Kampe respectively. This is an indication that there is tendency for water resources of the reservoir to increase and thus more water will be available for water supply and irrigation to ensure food security.

• Water for future
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• v.11 no.2
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• pp.43-53
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• 1978

Synopsis: This study has systemized the results of construction and classification with 656 large dams in Korea which were defined in ICOLD provision. Especially, checking up the drainage capability of large capacity outlets and its of spillway, this paper suggests the planning of outflow discharge with large capacity outlets and spillway in future. The results of this study are following as; 1. The classification by purposes in Korea shows that irrigation dams are 94% in rate(607 dams), jydropower and multipurpose dams are 2% (14 dams), municipal and industrial water supply dams are 4% (26 dams). 2. In design of proposed outflow discharge, spillways of irrigation dams were selected outflow discharge on 100 years return period, those of municipal and industrial water supply dmas 200 years and those of hydropower and multipurpose dams 500 years or 1000 years. 3. Emergency spillway should be considered in the fields of disaster prevention engineering and the rank of return periods for the emergency proposed out flow discharge was suggested. 4. Some of problems are suggested for this subject in future.

• Journal of The Korean Society of Agricultural Engineers
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• v.65 no.2
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• pp.21-33
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• 2023

While the main purpose of irrigation reservoirs is to supply agricultural water, the needs of environmental flow and flood control has been expanded. The agricultural reservoirs have been operated in the form of carry-over system until now. Therefore, the supply of agricultural water is difficult when the storage rate is not sufficiently secured after large volume of irrigation. In addition, there are regulation of the upper storage rate for some large reservoirs during the flood season, but lower storage rate is not regulated. Accordingly, this study aims to evaluate the capacity of agricultural water and environmental flow supply by setting the management lower storage rate of reservoir. The changes in the supply of agricultural and environmental flow was simulated according to the three different regulating lower storage rate scenarios. As a result, it was judged effective in terms of water supply managing the lower storage rate up to 30% when the initial storage rate of farming period is above annual average for the Naju reservoir considering existing water management practice. If the lower storage rate would have been controlled above 30%, the supply of agricultural water might be increased and non-effective discharge amount would be decreased compared to other scenarios during dry period of 2016-2018.

• Korean Journal of Agricultural Science
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• v.48 no.1
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• pp.103-117
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• 2021

The severe effects of climate change, such as global warming and the El Niño phenomenon, have become more prevalent. In recent years, natural disasters such as drought, heavy rain, and typhoons have taken place, resulting in noticeable damage. Korea is affected by droughts that cause damage to rice fields and crops. Societal interest in droughts is growing, and measures are urgently needed to address their impacts. As the demand for high-quality agricultural products expands, farmers have become more interested in water management, and the demand for field irrigation is increasing. Therefore, we investigated water demand in the irrigation of drought-vulnerable crops. Specifically, we determined the water requirements for crops including cabbage, red pepper, apple, and bean in four regions by calculating the consumptive water use (evapotranspiration), effective rainfall, and irrigation capacity. The total consumptive water use (crop evapotranspiration) estimates for Dangjin-si (cabbage), Yesan-gun (apple), Cheongyang-gun (pepper) in Chungnam, and Goesan-gun (bean) in Chungbuk were 33.5, 206.4, 86.1, and 204.5 mm, respectively. The volumes of groundwater available in the four regions were determined to be the following: Dangjin-si, 4,968,000 m³; Yesan-gun, 4,300,000 m³; Cheongyang-gun, 1,114,000 m³, and Goesan-gun, 3,794,000 m³. The annual amounts available for the representative crops, compared to the amount of evapotranspiration, were 313.9% in Dangjin-si, 29.5% in Yesan-gun, 56.1% in Cheongyang-gun, and 20.1% in Goesan-gun.

• Magazine of the Korean Society of Agricultural Engineers
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• v.21 no.1
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• pp.53-62
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• 1979

Since the first installation of irrigation Systems in Korea , a large number of small and medium sized reservoirs have been constructed as the main water sources Some 412, 000 ha are at present irrigated from these sources of supply. Many of the reservoirs were designed in accordance with old low standards and have in addition suffered a loss in capacity through sedimentation. At the same time, water demand has increased with the in troduction of high yielding varieties of rice. The combination has resulted in severe water deficits. To study the problem, 16 sample reservoirs have been surveyed and analysed. The results of the study are summarized be low: 1. Average decrease in reservoir capacity from the installation to present-8% 2. Average soil erosion loss (m$^3$/km$^2$/year) is 536 m$^3$/km$^2$/year and average erosion depth of soil is 0. 5mm per year. 3. No relationship, between reservoir capacity per unit of watershed (m$^3$/km$^2$) and soil erosion loss was found. 4. Increases are required in reservoir capacity: 15.8% due to the introduction of HYV's; 16.6% due to the change of system losses from 10%to 25% The conclusion to be drawn from the above results is that existing reservoir capacity should be increased by an average of 32%. The unit storage capacity to be adopted should be 661 mm

• Journal of Korean Society of Rural Planning
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• v.23 no.1
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• pp.85-96
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• 2017

Existing agricultural reservoirs are considered as alternative source for the water welfare of rural area. In this study, domestic water supply potential of 476 reservoirs, which has storage capacity more than one million cubic meter, out of 3,377 agricultural reservoirs managed by Korean Rural Community Corporation (KRC) were investigated. Among them water quality of 136 reservoirs met the criteria of domestic water source which show less than COD 3 ppm. Available amount for domestic water of reservoirs, which meet the water quality, for ten year return period of drought was analyzed with reservoir water balance model. The results showed that 116 reservoirs has potential for supplementary domestic water supply while satisfying irrigation water supply. Finally, economic analysis using Net Present Value (NPV), Benefit-Cost (B/C) ratio, Internal Rate of Return (IRR), and Profitability Index (PI) methods was also conducted. The analysis showed that 19 reservoirs satisfied economic feasibility when water is provided from reservoir outlet but only 9 reservoirs meet the economic feasibility if water delivered from a reservoir to treatment plant by newly built conveyance canal. In order to supply the domestic water through the agricultural reservoirs managed by KRC, it is necessary to flexibly interpret and operate the 'Rearrangement of Agricultural and Fishing village Act'. Also, it is reasonable to participate in the water service business when there is a supply request from other Ministries. In addition, the KRC requires further effort to change the crop system for saving water and improve efficiency of irrigation systems.