• 농업과학연구
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• 제28권2호
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• pp.132-146
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• 2001

Rice cultivation is not only the main resource of farm income and staple food but also the root of cultural life of Korean people. Korean government has carried out irrigation water development with heavy investment to cope with water shortage in rice fanning as a link of the five years economic development plans. In spite of the continuous accomplishment of irrigation water development, the marginal benefits-costs of irrigation water has not been studied. Owing to the government full support for the operation and maintenance of irrigation facilities, price of irrigation water as a membership fee could not be formed as the municipal and industrial water prices. Accordingly this study is aimed at identifying firstly the marginal benefits-cost of irrigation water, secondly deriving the macro-econometrics models as supply and demand functions of irrigation water and thirdly examining the marginal benefits-cost ratio. The trends of supply and demand prices of irrigation water were estimated annually. Considering the marginal benefits-cost ratio as 1.3, it was identified that additional irrigation water development projects still have an economic feasibility under the present economic situation in Korea.

• 한국농공학회논문집
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• 제65권5호
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• pp.81-91
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• 2023

As abnormal weather conditions escalate, water disasters such as droughts and floods occur more frequently. These natural disasters are fatal to agricultural reservoirs, where the operation techniques vary greatly depending on the season and weather conditions, and response through intake works is limited. In response, governments like the Korea Rural Community Corporation have researched efficient water supply methods through irrigation channels. Therefore, previous studies analyzed the irrigation process using numerical models to determine an efficient irrigation system. However, SWMM and EPANET used in previous studies are limited in quantitative agricultural irrigation process analysis. Therefore, this study developed AIRISS to simulate and analyze agricultural irrigation. Specifically, we simulated the irrigation process in the Ssangbong area of South Korea and simulated the irrigation process to verify the performance of the numerical model. AIRISS, developed in this study, is specialized in simulating the agricultural irrigation process. It can check the supply to each paddy and the condition of each paddy.

• 한국농공학회논문집
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• 제62권2호
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• pp.53-62
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• 2020

The purpose of this study is to estimate the channel water loss of agricultural water supply in the command areas belong to Yechon irrigation channel of Gyeongcheon reservoir located Mungyeong-si, which area experienced a severe drought in 2015. The channel water loss was estimated by comparison of the irrigation water requirements (IWR) and agricultural water supply of the field data from 2012 to 2015. Further analysis was conducted to define the conveyance loss estimated based on the leakage holes and illegal pumping spots investigated through the field survey, and the distribution loss obtained by subtracting conveyance loss from the channel water loss. The annual rainfall decreased gradually, but the contribution of effective rainfall, available rain water to crop, increased to IWR during the study period. These phenomena resulted in the increase of agricultural water supply, and hence made greater the channel water loss simultaneously. The average channel water losses estimated as 36.8 % with 7.1 % of the conveyance loss and 29.7 % of distribution loss respectively. The distribution loss seems to be related to total number of rainy days, and irrigation schedules, while the conveyance loss was caused by irrigation channel aging conditions and illegal intake problems. In order to achieve sustainable agricultural water resources, the channel water loss needs to be reduced through the restoration of aged irrigation facilities and effective water managements in the fields.

• 한국농공학회:학술대회논문집
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• 한국농공학회 1998년도 학술발표회 발표논문집
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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.

• 한국농공학회논문집
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• 제57권2호
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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.

• 한국농공학회논문집
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• 제63권5호
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• pp.95-105
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• 2021

Drought is a disaster that causes prolonged and wide scale damage. Recently, the severity and frequency of drought occurrences, and drought damage have been increased significantly due to climate change. As a result, a quantitative study of drought factors is needed to better understand and prevent future droughts. In the case of agricultural drought, several existing studies examine the economic damage caused by droughts and their causes, but these studies are not well suited to estimating crop-oriented agricultural drought damage and the factors that absolutely affect agricultural drought. This study determines which factors most affect agricultural drought. It examines meteorological factors and those related to agricultural water supplied by irrigation facilities. Rice paddy production per unit area is lower than the average from the last two years where agricultural drought occurred. We compare the relative frequency of agricultural drought impacts with irrigation facilities, effective reservoir storage, the number of water supply facilities, and the meteorological drought index such as Standardized Precipitation Index (SPI). To identify factors that affect agricultural drought, we correlate rice paddy production anomalies with irrigation water supply for the past two years. There was a high positive correlation between rice paddy production and irrigation water usage, and there was a low or moderate negative correlation between rice paddy production anomalies compared to the average of the past two years and SPI. As a result, agricultural water supply by irrigation facilities was judged to be more influential than meteorological factors in rice paddy production. This study is expected to help local governments establish policies related to agricultural drought response.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2023년도 학술발표회
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• pp.185-185
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• 2023

Agricultural water demand is considered as the major sector of water withdrawal due to irrigation. The majority part of the global agricultural field depends on various irrigation techniques. Therefore, a timely and sufficient supply of water is the most important requirement for agriculture. Irrigation is implemented in different ways in various land surface models, it can be modeled empirically based on observed irrigation rates or by calculating water supply and demand. Certain models can also calculate the irrigation demand as per the soil water deficit. In these implementations, irrigation is typically applied uniformly over the irrigated land regardless of crop types or irrigation techniques. Whereas, the latest version of Community Land Model (CLM) in the Community Terrestrial Systems Model (CTSM) uses a global distribution map of irrigation with 64 crop functional types (CFTs) to simulate the irrigation water demand. It can estimate irrigation water withdrawal from different sources and the amount or the areas irrigated with different irrigation techniques. Hence, we set up the model for the simulation period of 16 years from 2000 to 2015 to analyze the global irrigation demand at a spatial resolution of 1.9° × 2.5°. The simulated irrigation water demand is evaluated with the available observation data from FAO AQUASTAT database at the country scale. With the evaluated model, this study aims to suggest new sustainable scenarios for the ratios of irrigation water withdrawal, high depending on the withdrawal sources e.g. surface water and groundwater. With such scenarios, the CFT maps are considered as the determining factor for selecting the areas where the crop pattern can be altered for a sustainable irrigation water management depending on the available withdrawal sources. Overall, our study demonstrate that the scenarios for the future sustainable water resources management in terms of irrigation water withdrawal from the both the surface water and groundwater sources may overcome the excessive stress on exploiting the groundwater in major river basins globally.

• 농업과학연구
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• 제38권2호
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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 Biosystems Engineering
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• 제30권2호
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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.

• 한국농공학회논문집
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• 제56권4호
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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.