• Korean Journal of Agricultural Science
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• v.38 no.2
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• pp.331-341
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• 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.

• Journal of The Korean Society of Agricultural Engineers
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• v.56 no.4
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• pp.59-68
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• 2014

Climate change influences multiple environmental aspects, certain of which are specifically related to agricultural water resources such as water supply, water management, droughts and floods. Understanding the impact of climate change on reservoirs in relation to the passage of time is an important component of water resource management for stable water supply maintenance. Changes on rainfall and hydrologic patterns due to climate change can increases the occurrence of reservoir water shortage and affect the future availability of agricultural water resources. It is a main concern for sustainable development in agricultural water resources management to evaluate adaptation capability of water supply under the future climate conditions. The purpose of this study is to predict the sustainability of agricultural water demand and supply under future climate change by applying an irrigation vulnerability assessment model to investigate evidence of climate change occurrences at a local scale with respect to potential water supply capacity and irrigation water requirement. Thus, it is a recommended practice in the development of water supply management strategies on reservoir operation under climate change.

• Journal of The Korean Society of Agricultural Engineers
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• v.55 no.3
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• pp.63-73
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• 2013

The objectives of this study were to develop a hydrologic simulation model to estimate surface drainage for irrigation districts consisting of paddy and protected cultivation, and to evaluate the applicability of the developed model. The model consists of three sub-models; agricultural supply, paddy block drainage, and protected cultivation runoff. The model simulates daily total drainage as the sum of paddy field drainage, irrigation canal drainage, and protected cultivation runoff at the outlets of the irrigation districts. The agricultural supply sub-model was formulated considering crop water requirement for growing seasons and agricultural water management loss. Agricultural supply was calculated for use as input data for the paddy block sub-model. The paddy block drainage sub-model simulates paddy field drainage based on water balance, and irrigation canal drainage as a fraction of agricultural supply. Protected cultivation runoff is calculated based on NRCS (Natural Resources Conservation Service) curve number method. The Idong reservoir irrigation district was selected for surface drainage monitoring and model verification. The parameters of model were calibrated using a trial and error technique, and validated with the measured data from the study site. The model can be a useful tool to estimate surface drainage for irrigated districts consisting of paddy and protected cultivation.

• KCID journal
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• v.19 no.1
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• pp.77-86
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• 2012

The aim of this study was to analyze the operation plan for heightened agricultural reservoir, in terms of water supply to downstream paddy fields and instreams. Operation of agricultural reservoir before the heightened reservoir project is easy to manage because of its single purpose, which is irrigation water supply. However, after proceeding the heightened project, there is needed to be set the operation rule because of its multiple purpose, which is water for irrigation and supply to the stream. In this paper, propose the method of design the criteria of supply to the stream and operation rule curve for the heightened reservoir. According to simulation results by proposed operating rule for the Gumsa reservoir, the yearly amount of water supply to the stream can be 2,588 thousand $m^3$, 3 times of the heightened space (2,588 thousand $m^3$).

• Journal of The Korean Society of Agricultural Engineers
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• v.60 no.2
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• pp.121-132
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• 2018

Along with climate change, it is reported that the extreme climate events such as severe drought could cause difficulties of agricultural water supply. To minimize such damages, it is necessary to secure the agricultural water resources by using or saving the amount of irrigation water efficiently. The objectives of this study were to develop paddy water management scenarios and to evaluate their effectiveness on water saving. Three water management scenarios (a) deep irrigation with ponding depth of 20~80 mm (control, CT), (b) no/intermittent irrigation until paddy cracks (water management A, WM-A), and (c) intermittent irrigation with ponding depth under 20 mm (water management B, WM-B) were developed. Water saving effects were analyzed using monitored data from experimental paddy fields, and agricultural water supply was analyzed on a reservoir-scale using MASA model. The observed irrigation amounts were reduced by 21 % and 17 % for WM-A and WM-B compared to CT, respectively, and mainly occurred by the increase of effective rainfall. The simulation results showed that water management scenarios could reduce irrigation by 21~51 % and total inflow by 10~24 % compared to CT. The long-term simulated water level change of agricultural reservoir resulted in the decrease of dead level occurrence for WM-A and WM-B. The study results showed that WT-A and WT-B have more benefit than CT in the aspect of agricultural reservoir water supply.

• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.2
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• pp.93-101
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• 2015

The purpose of this study is to evaluate the paddy irrigation efficiency using real-time water level monitoring data and intermittent irrigation model in Gimjae, Dong-Jin irrigation district. For this study, the real-time water level data in Gimjae main canal and other secondary canals were collected from 2012 to 2014 and converted to daily discharge using rating curve in each canal. From intermittent irrigation model in paddy, irrigation water requirement was estimated and irrigation efficiency was calculated. The average amount of irrigation water supply per unit irrigation area was 1,011 mm in Gimjae main canal for 12,749 ha irrigation area, 1,011 mm in the secondary canal of upper region and 1,470 mm in the secondary canal of lower region. The median irrigation loss was 43 % in Gimjae main canal, 25 % in secondary canal of upper region and 35 % in the secondary canal of lower region. The larger irrigation area is, the irrigation loss rates tend to decrease in secondary canals. Monthly median irrigation losses in upper region were 10 (June) - 40 % (September) and those in lower region were 25 (May) to 40 % (April, June, August, and September). The results of canal management loss can be available as the basic data for irrigation water management and estimating guideline of optimal irrigation water supply to improve agricultural water use efficiencies.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2005.10a
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• pp.318-323
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• 2005

This research evaluates agricultural water supply capabilities for water computing demand and supply for water of the whole water system of Ansung stream by carrying out basin water balance classified by irrigation facility of water system of Ansung stream.

• Korean Journal of Agricultural Science
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• v.47 no.1
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• pp.19-28
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• 2020

This study proposed a simple estimation method for irrigation return flow from paddy fields using the water balance model. The merit of this method is applicability to other paddy fields irrigated from agricultural reservoirs due to the simplicity compared with the previous monitoring based estimation method. It was assumed that the unused amount of irrigation water was the return flow which included the quick and delayed return flows. The amount of irrigation supply from a reservoir was estimated from the reservoir water balance with the storage rate and runoff model. It was also assumed that the infiltration was the main source of the delayed return flow and that the other delayed return flow was neglected. In this study, the amount of reservoir inflow and water demand from paddy field are calculated on a daily basis, and irrigation supply was calculated on 10-day basis, taking into account the uncertainty of the model and the reliability of the data. The regression rate was calculated on a yearly basis, and yearly data was computed by accumulating daily and 10-day data, considering that the recirculating water circulation cycle was relatively long. The proposed method was applied to the paddy blocks of the Jamhong and Seosan agricultural reservoirs and the results were acceptable.

• Journal of Biosystems Engineering
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• v.30 no.2 s.109
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• pp.102-109
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• 2005

Water consumption at the farm is up to 48 percent of water resource of South Korea while manufacturing industry's is only $9.6\%$. The area of arable land is 2,077,067 ha and 27 percent of it is used for growing fruits and vegetables using furrow or surface irrigation at the greenhouse. Surface irrigation at the greenhouse for fruits and vegetables has problems such as over watering and insufficient supply of water to the fine roots of the plant. However, the research on the new method of irrigation to save water usage is few. The characteristics of soil wetting was measured for using surface irrigation and underground trickle irrigation method where water was supplied at 10, 15, 20, and 25 cm beneath the surface ground. Followings are summary of this study. 1. The efficiency of underground trickle irrigation was expected to be as high as twice of surface irrigation such as drip watering or sprinkling. 2. This improvement could be possible by using less than $50\%$ of irrigation water than surface irrigation to supply similar amount of water near fine roots. 3. Surface irrigation causes soil compaction as deep as 20 cm below the surface ground which reduces soil porosity and root respiration ending up developing less fine roots. 4. Underground trickle irrigation can prevent overdamping in the greenhouse since it does not over wet the surface soil. At winter, the amount of agricultural chemical usage could be reduced since this irrigation method does not develop blight or crop disease from condensation of water vapor.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1998.10a
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• pp.81-86
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• 1998

It is difficult to know how to restrict the amount of water supply in the drought season, because there is no objective standard rules. The purpose of the study is to present management rules to overcome the drought in the irrigation reservoir by forecasting the water level and restricting water supply according to the operation rule curve and the pattern of rotation-irrigation system. From the operation rule curve drawn up by analyzing the observed water level of reservoir, the water supply rules and rotation-irrigation patterns using WWW and GIS are suggested.