• 한국농공학회논문집
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• 제46권5호
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• pp.3-11
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• 2004

The objective of this study is to develop water saving irrigation method using water balance model in order to save rural water. Daily water balance components such as irrigation water, drainage water, effective rainfall, ET, and infiltration were measured in paddy fields. Model simulations were performed for different outlet heights and ponding depths. The outlet heights and the ponding depths are 2 cm, 4 cm, 6 cm, 8 cm, and 10 cm, respectively. Based on the simulation very shallow ponding depth of 2 cm with 10 cm outlet height showed the largest effective rainfall ratio and the smallest irrigation amount. Until the introduction of laser leveling dozer and automatic inlet control devices, it would be desirable to adopt 4cm ponding depth because of difficulty of land leveling and frequency of farmer's field visit. The results of this study will be applied in the paddy farming and can improve water use efficiency.

• 한국농공학회지
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• 제41권2호
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• pp.37-43
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• 1999

This study was conducted to develop the simple and convenient irrigation control model which can maintain the appropriate rates of irrigation and drainage of nutrient solution according to the enviornmental conditions and growth stages in soilless culture of cucumber. In order to obtain fundamental data for development of the model, investigation of the actual state of soilless culture practices was carried out. Most irrigatioin systems of soillness culture were controlled by the time colock. Evapotranspiration of cucumber in soilness culture was investigated and correlations with environmental conditions were analyzed , and its estimating model was developed. In order to develop the irrigation system which can control the amount of nutrient solution applied according to seasons, weather conditions, and growth stages, a irrigation clock control was developed. Applicability of the model was tested by simulation. Drainage rates of nutrient solution controlled by conventional time clock, integrated solar radiation, and the developed model were 61% , 20%, and 32% , respectively in cucumber perlite culture.

• 한국농공학회논문집
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• 제60권4호
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• pp.63-72
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• 2018

The main function of an agricultural reservoir is to supply irrigation water to paddy rice fields in South Korea. Therefore, the operation of a reservoir is significantly affected by the phenology of paddy rice. For example, the early stage of irrigation season, a lot of irrigation water is required for transplanting rice. Therefore, water storage in the reservoir before irrigation season can be a key factor for sustainable irrigation, and it becomes more important under climate change situation. In this study, we analyzed the climate change impacts on reservoir storage rate at the beginning of irrigation period and simulated the reservoir storage, runoff, and irrigation water requirement under RCP scenarios. Frequency analysis was conducted with simulation results to analyze water supply probabilities of reservoirs. Water supply probability was lower in RCP 8.5 scenario than in RCP 4.5 scenario because of low precipitation in the non-irrigation period. Study reservoirs are classified into 5 groups by water supply probability. Reservoirs in group 5 showed more than 85 percentage probabilities to be filled up from half-filled condition during the non-irrigation period, whereas group 1 showed less than 5 percentages. In conclusion, reservoir capacity to catchment area ratio mainly affected water supply probability. If the ratio was high, reservoirs tended to have a low possibility to supply enough irrigation water amount.

• 한국농공학회논문집
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• 제63권2호
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• pp.85-96
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• 2021

Irrigation return flow is defined as the excess of irrigation water that is not evapotranspirated by direct surface drainage, and which returns to an aquifer. It is important to quantitatively estimate the irrigation return flow of the water cycle in an agricultural watershed. However, the previous studies on irrigation return flow rates are limitations in quantifying the return flow rate by region. Therefore, simulating irrigation return flow by accounting for various water loss rates derived from agricultural practices is necessary while the hydrologic and hydraulic modeling of cultivated canal-irrigated watersheds. In this study, the irrigation return flow rate of agricultural water, especially for the entire agricultural watershed, was estimated using the SWMM (Storm Water Management Model) module from 2010 to 2019 for the Madun reservoir located in Anseong, Gyeonggi-do. The results of SWMM simulation and water balance analysis estimated irrigation return flow rate. The estimated average annual irrigation return flow ratio during the period from 2010 to 2019 was approximately 55.3% of the annual irrigation amounts of which 35.9% was rapid return flow and 19.4% was delayed return flow. Based on these results, the hydrologic and hydraulic modeling approach can provide a valuable approach for estimating the irrigation return flow under different hydrological and water management conditions.

• 한국농공학회지
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• 제39권4호
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• pp.64-74
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• 1997

The purpose of this study is to analyze hydraulic characteristics of surface irrigation in a paddy field of direct seeding culture. Field experiment was performed in the paddy field of ridge direct dry seeding. Simulation by a numerical model was also accomplished with the data obtained from the field experiment. The model was developed by one dimensional zero-inertia equation and finite difference method. From the result of the field observation, the furrows of the experimental field were found to have various geometric characteristics. Advance distance and time were measured both in the field and by the model simulation for various furrow lengths and irrigation discharges. Roughness coefficients of each furrow were also estimated by the model.

• 한국농공학회논문집
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• 제59권5호
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• pp.31-40
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• 2017

The aim of this study is to estimate net irrigation requirements for red pepper during growing period using soil moisture model. The soil moisture model based on water balance approach simulates soil moisture contents of 4 soil layers in crop root zone considering soil moisture extraction pattern. The LAMP (Land-Atmosphere Modeling Package) high resolution meteorological data provided from National Center for AgroMeteorology (NCAM) was used to simulate soil moisture as the input weather data. Study area for the LAMP data and soil moisture simulation covers $36.92^{\circ}{\sim}37.40^{\circ}$ in latitude and $127.36^{\circ}{\sim}127.94^{\circ}$ in longitude. Soil moisture was monitored using FDR (Frequency Domain Reflectometry) sensors and the data were used to validate the simulation model from May 24 to October 20 in 2016. The results showed spatially detailed soil moisture pattern under different weather conditions and soil texture. Net irrigation requirements were also different by location reflecting the spatially distributed weather condition. The average of the requirements was 470.7 mm and averages about soil texture were 466.8 mm, 482.4 mm, 456.0 mm, 481.7 mm, and 465.6 mm for clay loam, sandy loam, silty clay loam, clay, and sand respectively. This study showed spatial differences of soil moisture and the irrigation requirements of red pepper about spatially uneven weather condition and soil texture. From the results, it was demonstrated that high resolution meteorological data could provide an opportunity of spatially different crop water requirement estimation during the irrigation management.

• 한국농공학회논문집
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• 제56권5호
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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.

• 한국습지학회지
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• 제25권4호
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• pp.297-305
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• 2023

순환관개는 농업유역내 하천수를 상류의 농경지로 재투입시켜 관개용수로써 활용하고 기 사용된 용수는 직접유출 또는 기저유출의 형태로 하천으로 회귀되는 관개방식이다. 순환관개는 용수 및 양분 확보 측면에서 장점이 크지만 순환관개 후 발생하는 회귀수는 과투입된 양분을 함유하고 있어 하천 수질에 악영향을 미칠 것으로 예상된다. 따라서 순환관개에 따른 하천 수질변화에 대한 정량적 분석은 효율적인 농업용수 공급과 수질관리대책 수립을 위해 반드시 필요하다. 유역내 수문 및 오염물질의 순환, 그리고 하천수질에 대한 정량적 영향을 통합적으로 분석하기 위하여 유역모델이 주로 활용되고 있으나 대부분의 유역모델들은 순환관개에 의한 수질 영향을 모의할 수 있는 기능을 제공하고 있지 않다. 이에 본 연구에서는 HSPF(Hydrological Simulation Program-Fortran) 유역모델과 다중 저류지 모델(Multi-reservoir model)을 연계하여 순환관개 시스템 운영에 따른 하천수질 영향을 분석하고자 하였다. 연구 대상 지역은 경상남도 창녕군 계성천 유역내 순환관개를 시행하고 있는 관곡천 소유역으로 농업활동에 의한 오염물질 배출이 주된 지역이다. 먼저 계성천 및 관곡천을 대상으로 구축된 HSPF모델을 활용하여 관개지역에서의 배출수(직접유출 및 기저유출) 및 하천수에 대한 연간 유량 및 수질 변화 시계열 자료를 생성하고 이를 토대로 자체 구축한 다중저류조 모델을 보정한 후 순환관개 모의에 사용하였다. 다중 저류지 모델에서 관곡천 유역을 관개지역과 관곡천 등 두 개의 하위시스템으로 구성하고 순환관개에 따른 하위시스템내 반응(식물흡수, 흡탈착, 및 소멸) 및 하위시스템 간 물 및 물질(질소 및 인)전달 관계를 모의할 수 있도록 하였다. 최종적으로 순환관개 운영 유무에 따라 총 3개의 시나리오를 구성하여 연간 순환관개용수량 변화에 따른 관곡천 수질영향을 분석하였다.

• 한국농공학회논문집
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• 제48권2호
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• pp.77-87
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• 2006

The reuse of wastewater for agricultural irrigation may cause human health risk as a result of exposure to pathogens. This study conducted the quantitative microbial risk assessment in paddy field irrigated with treated wastewater. Six treatments were used to irrigate the paddy field from Year 2003 to Year 2005: biofilter-effluent, UV-disinfected water (6, 16, 40, 68 $mW s cm^{-2}$), pond-treated water, wetland-treated water, conventional irrigation water and tap water. Total coliforms, fecal coliforms and E. coli were monitored during rice growing period. Beta - Poisson model was employed to calculate the microbial risk of pathogens ingestion that may occur to farmers and neighbor children. Uncertainty of risk was estimated using Monte Carlo simulation. In this study, the microbial risk was higher during initial cultivation (end of May$\sim$June), and it decreased with time. Biofilter effluent (secondary effluent) irrigation showed higher risk values than others (>$10^{-4}$) and irrigation with UV-disinfected water has the lowest risk range ($10^{-6}{\sim}10^{-5}$). The risk value estimated in 2005 was lower than risk value in 2003 and 2004, it is likely due to clean tap water irrigation in initial transplanting stage. It is suggested that irrigation with UV-disinfected water and pond-treated water would reduce the microbial risk associated with wastewater irrigation in paddy field. In addition, the first irrigation water quality significantly affected the subsequent microbial risk.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2005년도 학술발표논문집
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• pp.661-666
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• 2005

Wastewater reuse are exposed public health risk by pathogens. Therefore, this study was examined for microbial risk assessment after irrigation as treated wastewater in paddy rice plots. Five treatments were used: biofilter effluent, UV disinfected water, pond treatment, wetland treatment and conventional irrigation water. Risk assessment was calculated based on the beta-Poisson model by concentration of E. coli from 2003 to 2005. Monte-Carlo simulation (n=10,000) was used to estimate the risk characterization of uncertainty. The risk range was from $10^{-5}$ to $10^{-8}$ except biofilter effluent was $10^{-4}$ in June. The USEPA(1992) has recommended that risk of < $10^{-4}$ is acceptable level of safety for potable waters. In 2005, risk value was lower than 2003, 2004 because of the first irrigation for plowing water is lower E. coli concentration used tap water. It is shown that the first irrigation water quality was important for wastewater irrigation in paddy. UV disinfection and natural treatment used pond and wetland were thought to be an effective for wastewater reuse.