• Magazine of the Korean Society of Agricultural Engineers
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• v.22 no.4
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• pp.73-81
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• 1980

In the light of these analysis of the recorded rainfall data from the meteorological observatories in Kyungpook area, hydraulic and hydrological data based on the representative watershed area and questionnaire or visiting letters to the 21 Land Reclamation Association in Kyungpook province, the hydrological backgrounds being the question to the irrigation facilities in Kyungpook Province or nation wide were studied partialy and the system of conservation and management of agricultural water sources facilities, prevention countermeasures to the drought and flood disasters, prediction of available surface waterflow and need or needless of new facilities establishment were reviewed in this paper. In the results, Technical and financial management and conservation investments of the already constructed ficalities should urgently and firstly be considered than the newly being established one.

• Journal of Korea Water Resources Association
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• v.37 no.7
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• pp.517-526
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• 2004

Agricultural water plays an important role in the national water management. Irrigation return flow is the amount of irrigated water that returns to the river system. In the water resources development planing and management, an accurate estimation of the irrigation return flow is very important. In this study, a 5.5 ha small size paddy area in Kyungbuk province is selected and the water balance components are measured during the 2003 growing season. The total irrigation return flow ratio was 53.7%, of which 30.2% was rapid return flow and 23.5% was delayed return flow.

• Journal of The Korean Society of Agricultural Engineers
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• v.59 no.1
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• pp.45-55
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• 2017

Climate change causes changes in rainfall patterns, temperature and drought frequency. Climate change impact influences on water management and crop production. It is critical issue in agricultural industry. Rice is a staple cereal crop in South Korea and Korea uses a ponding system for its paddy fields which requires a significant amount of water. In addition, water supply has inter-relationship with crop production which indicates water productivity. Therefore, it is important to assess overall impacts of climate change on water resource and crop production. A water footprint concept is an indicator which shows relationship between water use and crop yield. In addition, it generally composed of three components depending on water resources: green, blue, grey water. This study analyzed the change trend of water footprint of paddy rice under the climate change. The downscaled climate data from HadGEM3-RA based on RCP 8.5 scenario was applied as future periods (2020s, 2050s, 2080s), and historical climate data was set to base line (1990s). Depending on agro-climatic zones, Suwon and Jeonju were selected for study area. A yield of paddy rice was simulated by using FAO-AquaCrop 5.0, which is a water-driven crop model. Model was calibrated by adjusting parameters and was validated by Mann-Whitney U test statistically. The means of water footprint were projected increase by 55 % (2020s), 51 % (2050s) and 48 % (2080s), respectively, from the baseline value of $767m^2/ton$ in Suwon. In case of Jeonju, total water footprint was projected to increase by 46 % (2020s), 45 % (2050s), 12 % (2080s), respectively, from the baseline value of $765m^2/ton$. The results are expected to be useful for paddy water management and operation of water supply system and apply in establishing long-term policies for agricultural water resources.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.44 no.3
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• pp.225-229
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• 1999

Unstable seedling stand establishment of wet direct seeding culture of rice is one of the major elements preventing the extension of its culture area. In order to develop methods of seedling stand improvement in direct seeded rice on flooded surfaces, three field experiments were conducted on silty loam soil using a cultivar 'Donjinbyeo' for three years, mainly focusing on water management after seeding and seed soaking with plant growth regulators (PGRs). Under the condition of shallow flooding after seeding, seedling stand rate increased and floating seedling rate decreased in both early and normal season seeding compared to deep flooding. With earlier draining time after seeding, there was a tendency towards preferential growth of the seminal root, increase of seedling stand and decrease of the floating seedling rate. Therefore the highest seedling numbers per unit area and the lowest floating seedling numbers were found upon drainage at 1 day after seeding (DAS), while a contrary tendency was shown upon conventional drainage at 7 DAS. Seed soaking with PGRs such as Metalaxyl or mixing of Metalaxyl with gibberellic acid (GA$_3$) significantly increased the seedling stand. In addition the effects of PGR treatment on seedling stand and the early growth of plants were greater under flooded conditions than under drained conditions after seeding, although draining of water after seeding improved the seedling establishment rate more when compared with the PGR treatment. These results suggest that draining management after seeding or maintaining of shallow flooding for a week is the most effective method to improve the seedling stand rate in wet direct seeding.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.323-327
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• 2006

During the past decades in South Korea, there have been several projects to reduce water demand and save water for paddy irrigation system by automation. This is called as intensive water management system by telemetering of paddy ponding depth and canal water level and telecontrol of water supply facilities. This study suggests a method of constructing topology-based irrigation network system using GIS tools. For the network modeling, a typical agricultural watershed included reservoirs, irrigation and drainage canals, pumping stations was selected. ArcHydro tools composed of edge, junction, waterbody and watershed were used to construct hydro-network. ArcHydro Model was then designed and the network was successfully built using the HydroID. Visualization using ArcHydro tools could display table property of each object. ArcHydro Model was linked to Agricultural Water Demamd and Supply Estimation System (AWDS) which developed by Korea Rural Community and Agriculture Corporation (KRC) to extract information of the study area. And menu of supply facilities information, demand analysis and supply analysis constructed for information acquisition and visualization of acquired informations.

• Journal of The Korean Society of Agricultural Engineers
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• v.60 no.6
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• pp.1-12
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• 2018

The objectives of this study were to develop a system linking hydrologic and water quality models considering the mechanisms of agricultural reservoir and paddy cultivation and to evaluate whether the developed system simulates hydrologic and water quality processes better than a hydrologic model that do not consider the mechanisms. The system consisted of Hydrological Simulation Program-Fortran (HSPF) as a watershed model, Module-based hydrologic Analysis System for Agricultural watersheds (MASA) as reservoir water balance model, and Chemical, Runoff and Erosion from Agricultural Management System-Paddy (CREAMS-PADDY) as a hydrologic and water quality model for paddy fields. This study carried out on the Seolseong-Cheon watershed in Icheon, and the water level and water quality had been monitored for two years at the outlet of the watershed. According to the results of this study, the performance of the simulation using HSPF-MASA-CREAMS-PADDY system was better than others, but they did not show a statistically significant difference. This seemed to be due to the uncertainty of the farming data and the water quality data of the reservoir. Therefore, if accurate input data for the system is obtained, HSPF-MASA-CREAMS-PADDY system could be used to model an agricultural watershed to obtain more realistic results. The results of this study could be utilized to the modeling of agricultural watersheds in Korea where paddy rice cultivation is dominant.

• Journal of Korean Society of Rural Planning
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• v.11 no.4 s.29
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• pp.99-108
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• 2005

In this study, thirteen villages in Chonnam province were selected as case study sites and the spatial distribution of the facilities in the villages was examined to provide basic information fur the establishment of rural plans. According to the questionnaire survey, various problem such as environmental pollution, position, scene, management etc. was brought owing to cattle shed, and dissension was more or less seen by scale of facilities, management of facilities and waste, regional factor(stock farming management condition, life style and attitude of inhabitants) and topographical factor (height, position physical aspect of a mountain, distance with water resources etc.) etc.. The facilities could be classified into 6 types based on the their spatial locations: 1) Type 1, facilities located at the waterside; 2) Type 2, facilities located at the entrance of village; 3) Type 3 facilities, scattered in the residential area: 4) Type 4 facilities, collectivized in village; 5) Type 5 facilities, adjoining village; and 6) Type 6 facilities, scattered irregularly inside and outside of village. Based on the classification, possible implementations for the reduction of environmental impacts were suggested. The results of this study could be used as an example of study on the distribution, classification, and rearrangement of environment-impacting facilities in rural areas for improvement of their roles in providing amenity resources.

• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.1
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• pp.37-45
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• 2015

Recent droughts in South Korea have had large economic and environmental impacts across the country. Changes in rainfall and hydrologic patterns due to climate change can potentially increase the occurrence of extreme droughts and affect the future availability of water resources. Therefore, it is necessary to evaluate drought vulnerability for water resources planning and management, and identify the appropriate mitigation actions to conduct a drought risk analysis in the context of climate change. The objective of this study is changes in the temporal trends of drought characteristics in South Korea to examine drought impacts under climate change. First, the changes of drought occurrence were analyzed by applying the Standardized Precipitation Evapotranspiration Index (SPEI) for meteorological data on 54 meteorological stations, and were analyzed for the past 30 years (1981-2010), and Representative Concentration Pathways (RCP) climate change scenarios (2011-2100). Second, the changes on the temporal trends of drought characteristics were performed using run theory, which was used to compare drought duration, severity, and magnitude to allow for quantitative evaluations under past and future climate conditions. These results show the high influence of climate change on drought phenomenon, and will contribute to water resources management and drought countermeasures to climate change.

• Journal of The Korean Society of Agricultural Engineers
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• v.56 no.5
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• pp.1-9
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• 2014

The DIROM (Daily Irrigation Reservoir Operation Model) was modified to estimate amounts of water release from reservoirs, considering customary irrigation water management practices, such as water supply for puddling and transplanting paddy rice from seeding beds and mid-season drainage. The applicability of the modified model was investigated by simulating amounts of water release from three study reservoirs: Hwamae, Ogi, and Doya Reservoirs. In terms of annual amounts of water release, the relative errors between the observed and simulated values in 2012 and 2013 ranged -26.20 % to 10.28 % and 4.90 % to 30.06 %, respectively; in case of reservoir water levels, the RMSE values ranged 0.45 m to 1.34 m and 0.40 m to 1.27 m, respectively. Also, it was revealed that the model provided better simulation results for monthly water releases than the original model. In addition, the model presented better performance in simulating 10-day amounts of water release from April to June. However, the model had still significant errors in the simulation results from July to September because the reservoirs were practically operated to adapt to water management circumstances. Finally, it is concluded that the modified DIROM can estimate the amounts of water release from reservoirs, reflecting irrigation water management customs in paddy-field districts. To achieve higher prediction accuracy of the model, it is necessary to incorporate practical reservoir operation rules into the model.

• Journal of The Korean Society of Agricultural Engineers
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• v.65 no.5
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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.