• 한국농공학회논문집
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• 제63권3호
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• pp.75-85
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• 2021

This study evaluated variations in the paddy rice water demand based on the continuous changing in rice transplanting period and ponding depth at the four study paddy fields, which represent typical rice producing regions in Korea. Total 7 scenarios on rice transplanting periods were applied while minimum ponding depth of 0 and 20 mm were applied in accordance with maximum ponding depth ranging from 40 mm to 100 mm with 20 mm interval. The weather data from 2013 to 2019 was also considered. The results indicated that the highest rice water demand occurred at high temperature and low rainfall region. Increased rice transplanting periods showed higher rice water demand. The rice water demand for 51 transplanting days closely matched with the actual irrigation water supply. In case of ponding depth, the results showed that the minimum ponding depth had a proportional relationship with rice water demand, while maximum ponding depth showed the contrary results. Minimum ponding depth had a greater impact on rice water demand than the maximum ponding depth. Therefore, these results suggest that increasing the rice transplanting period, which reflects the current practice is desirable for a reliable estimation of rice water demand.

• 한국관개배수논문집
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• 제13권1호
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• pp.82-90
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• 2006

The practical date of rice growing stages and the date for calculating the water demand in paddy field have differences. The causes are rice planting water requirement, nursery bed area and change of average temperature and so on. Some recent papers have shown the same results. So we have investigated the nursery period, rice transplanting period and mid-summer drainage and developed a system for estimating water demand. And we calculated the water demand by using the system. The result showed that calculation by using the new system is more appropriate than the calculation by using the established period. But because water losses in canals and crop coefficient are not determined appropriately, we can calculate the agricultural water demand more accurately by dstablishing canal losses ratio, crop coefficient and so on.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2005년도 학술발표논문집
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• pp.61-67
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• 2005

Agricultural water for rice growing is the important factor of water resources in Korea. so, it is imperative to know the practice of water management in paddy field. The experimental site has been operated in order to investigate water management practice and water supply discharge since 2001. There are 8 irrigation areas which are observed the water supply discharge in this site. We have investigate the water management practice in this site and we know that the practical date of rice growing stages and the date for calculating the water demand in paddy field. So, There is much differences between the calculated water demand and practical water supply. We could reduce the differences by calculating the water demand using the practical date of rice growing stages.

• 한국수자원학회논문집
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• 제53권12호
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• pp.1131-1142
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• 2020

본 연구에서는 농업용수 공급계획 및 수리시설설계에 적용하기 위한 논벼 수요량 추정에 있어서 증발산량 산정 방법을 농업용수 공급량을 기반으로 평가해 보았다. 증발산량 산정 방법은 기존의 논벼 수요량에 적용 되어온 Modifeid-Penman (MP) 방법과 최근에 농촌진흥청에서 작물계수 개발에 적용한 Penman-Monteith (PM) 방법이 고려되었다. 호남지역 한국농어촌공사 관할지구를 선정하여 기상특성을 분석하고, MP 방법과 PM 방법에 의한 논벼 수요량을 산정하여 현장의 용수 공급량과 비교분석하여 증발산량의 적용성을 평가해 보았다. 대상지구의 기상특성은 30년 기간 연평균 및 논벼 생육기간 평균기온은 증가하고 연평균 강우량과 논벼 생육기간 강우량은 감소하는 경향을 보였다. 이러한 기상특성은 증발산량 산정과 논벼 수요량 결과에 직접적인 영향을 미치는 것으로 파악되었다. 두 증발산량 산정방법 적용에 의한 수요량 결과 비교분석에서 MP 방법에 의한 논벼 수요량이 PM 방법 보다 더 높게 산정되는 경향을 보였으며, 농업용수 공급량과의 비교분석에서 MP 방법이 PM 방법 보다 더 적은 격차를 나타내었다. 따라서 현장여건이 반영된 농업용수 공급량 기반 평가에서 논벼 수요량 산정에 MP 방법을 적용하는 것이 농업용수 관리계획 및 용수공급 안정성 확보에 유리할 것으로 사료된다.

• 한국농공학회논문집
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• 제54권2호
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• pp.15-26
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• 2012

For stable and sustainable crop production, understanding the effects of climate changes on agricultural water resources is necessary to minimize the negative effects which might occur due to shifting weather conditions. Although various studies have been carried out in Korea concerning changes in evapotranspiration and irrigation water requirement, the findings are still difficult to utilize fordesigning the demand and unit duty of water, which are the design criteria of irrigation systems. In this study, the impact analysis of climate changes on the paddy water demand and unit duty of water was analyzed based on the high resolution climate change scenarios (specifically under the A1B scenario) provided by the Korea Meteorological Administration. The result of the study indicated that average changes in the paddy water demand in eight irrigation districts were estimated as -2.4 % (2025s), -0.2 % (2055s), and 3.2 % (2085s). The unit duty of water was estimated to increase on an average within 2 % during paddy transplanting season and within 5 % during growing season after transplanting. This result could be utilized for irrigation system design, agricultural water resource development, and rice paddy cultivation policy-making in South Korea.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2020년도 학술발표회
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• pp.119-119
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• 2020

Globally, the demand for food and water resources are increasing rapidly with the growing concerns of meeting the projected population upsurge, specifically by 2050. The global population is projected to hit 9.8 billion in 2050 while the food demand is expected to increase by 77% from the 2007 base year. Moreover, the already scarce water resources, especially in the food-producing regions, expected to be significantly affected as food production already accounts for over 70% of the global water resources. However, the estimated food demand encapsulated the actual demand for both human consumption and animal feed in addition to the exuberant food waste at the consumption stage of the supply chain, notably in the developed countries. Managing the food consumption demand and food waste can have across-the-board benefits on water resources and other associated food production impacts. This study assessed the water-saving potentials through food waste in Korean households using the food waste data obtained from the direct weighing analysis. The household food waste collection and characterization were carried out during the summer (July), fall (September), and winter (December) seasons of 2019. The water footprint related to the food waste within Korean households was based on the water footprint concept, i.e. indirect water use. The results of our estimation showed that an average Korean household wasted 6.15 ± 4.36 kg daily, amounting to 12.53 ± 11.10 m3 of water resources associated with the waste. On the per capita basis, an average of 0.024 ± 0.017 kg/capita/day of food was wasted resulting to 0.049 ± 0.044 m3/capital/day of water resources wasted. The food waste types that accounted for the principal share in the water footprint were beef, soybean, rice and pork with values 30.7, 10.1, 9.6, and 7.5%, respectively. Considering that the production of meat and meat products are water intensive and the agricultural water use in Korea is largely for rice production, addressing the food waste of these two important agricultural products can be a hotspot for water saving potential in the country. This study therefore provides an insight to addressing the water scarcity in the country through reducing household food waste.

• 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.

• 한국농공학회지
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• 제43권1호
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• pp.53-65
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• 2001

To estimate agricultural water demand, many factors such as weather, crops, soil, cultivation method, crop coefficient and cultivation area, etc. must be considered. But it is not easy to estimate water demand in consideration of these factors, which are variable according to growth stage and regional environment. This study provides estimation system for agricultural water demand(ESAD) in order to estimate water demand easily and accurately, and arranges all factors needed for water demand estimation. This study identifies the application of estimation system for agricultural water demand with the data observed in the other studies, and analyzes nationwide agricultural water demand. The results are as follows. 1) The practice of different rice cultivation in the paddy field resulted in different water demands. Water depth and infiltration ratio in paddy are the most important factors to estimate water demand. The water depths in paddy simulated by ESAD is very similar to the observed ones. 2) Water demand of upland crops varies with the crops, soil, etc.. Effective rainfall estimated by daily routing of soil moisture varies according to the crops, soil, and effective soil zone(root depth). As crop root become grown, effective rainfall and an amount of irrigation water has been increased. 3) The current unit water demand of upland crops applied as 500mm or 550mm to estimate water demand does not reflect the differences caused by the crops, regional surrounding, weather condition, etc. Results from ESAD for the estimation of water demand of upland crops show that ESAD can simulate the actual field conditions reasonably because it simulates the actual irrigation practices with the daily routing of soil moisture.

• Agricultural and Biosystems Engineering
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• 제5권2호
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• pp.60-63
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• 2004

Demand for development of processing systems for pre-washed rice and propagation of the systems has recently been on the rise, because rice-cooking requires watering 15 times the rice quantity to cook, as in case of the regular rice currently being circulated in Korean market, in addition to paying the trouble of washing it for cooking, and besides the milky turbid water coming from the rice-washing contributes to water contamination. In this study, therefore, a processing system for pre-washed rice was designed and built with rice surface polishing devices that adopted abrading and airing methods, an electrostatic method and a method using a fine watering, to conduct its performance test. The result showed that turbidity of the wash water, which is the base to determine the pre-washed rice standard, turned out 47.33 ppm and 48.00 ppm respectively for 800 kg/hr and 1,000 kg/hr supplies, which meets the standard for the processing system free from rice-washing for cooking. The quantity of watering at this experiment was only 0.43 times the rice, thus resulting in curtailment of process-watering by approximately $69\%$ compared with the existing wet-type pre-washed rice processing system popular in Korean market.

• 한국농공학회논문집
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• 제63권6호
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• pp.1-16
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• 2021

Global warming due to climate change is expected to significantly affect the hydrological cycle of agriculture. Therefore, in order to predict the magnitude of climate impact on agricultural water resources in the future, it is necessary to estimate the water demand for irrigation as the climate change. This study aimed at evaluating the future changes in water demand for irrigation under two Shared Socioeconomic Pathways (SSPs) (SSP2-4.5 and SSP5-8.5) scenarios for paddy rice in Gimje, South Korea. The APEX-Paddy model developed for the simulation of paddy environment was used. The model was calibrated and validated using the H₂O flux observation data by the eddy covariance system installed at the field. Sixteen General Circulation Models (GCMs) collected from the Climate Model Intercomparison Project phase 6 (CMIP6) and downscaled using Simple Quantile Mapping (SQM) were used. The future climate data obtained were subjected to APEX-Paddy model simulation to evaluate the future water demand for irrigation at the paddy field. Changes in water demand for irrigation were evaluated for Near-future-NF (2011-2040), Mid-future-MF (2041-2070), and Far-future-FF (2071-2100) by comparing with historical data (1981-2010). The result revealed that, water demand for irrigation would increase by 2.3%, 4.8%, and 7.5% for NF, MF and FF respectively under SSP2-4.5 as compared to the historical demand. Under SSP5-8.5, the water demand for irrigation will worsen by 1.6%, 5.7%, 9.7%, for NF, MF and FF respectively. The increasing water demand for irrigating paddy field into the future is due to increasing evapotranspiration resulting from rising daily mean temperatures and solar radiation under the changing climate.