• Journal of Korea Water Resources Association
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• v.53 no.12
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• pp.1131-1142
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• 2020

This study assessed evapotranspiration (ET) methods applying for estimation of paddy rice water demand based on agricultural water supply. The Modified Penman (MP) method and the Penman-Monteith (PM) method recently suggested by Rural Development Administration (RDA) were considered. The 6 Korea Rural Community Corporation (KRC) command areas located in Honam province were selected in this study. The climate characteristics were also analysed with the average annual and the growing season temperatures and rainfalls. As a result, the annual average and the growing season temperature showed the increased trend while the rainfall tended to decrease during 30 years. The paddy rice water demand found to be directly influenced by these climate trends as ET also affected by them. The higher values of paddy rice water demand were obtained from applying MP method compared to the one applying PM method. The lower differences were also obtained from MP method for the comparisons between the paddy rice water demand estimated by both methods with agricultural water supply. Therefore, these results suggest that the MP method is more desirable to use for estimating paddy rice water demand in order to achieve stability of irrigation designs and plans.

• Journal of the Korean association of regional geographers
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• v.6 no.3
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• pp.37-52
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• 2000

Generally speaking, the metropolitan agricultural regions have some advantages from the high accessibility to markets. But agriculture inevitably rests on the biological process. This study shows what characteristics of the agricultural management are found in these less favored metropolitan areas with bad natural conditions and how farm household live there. From the view point of farm household, the quality of labors they can get is quite low, and insufficient in quantity. The shortage of labor can be made up for the farming on Trust Farming System And the relatively less favored agricultural conditions prevent people from immigrating into these kind of areas, if they don't have any relationship with there. With bad natural conditions, the farm households usually cultivate relatively small areas for the purpose of self-sufficiency, and with smaller cultivating units(Baemi) of the land than in open fields. The scale of the agricultural management is largely affected by the ages of agricultural managers. The more aged the managers are, the smaller scale of the agricultural management. How to use lands is determined in accordance with the natural conditions such as percentage of sunshine and accessibility to drainage facilities -the two major factors- and more. Either owner-run farmlands or leased farmlands doesn't show any difference in each growing crops. Depending on the conditions of the lands, rice paddy is used for growing rice and field is used for growing self sufficient plants including vegetables for the farm household. Although the lack of infrastructure causes the inconvenience of living, and there exist less favored agricultural conditions, this kind of life and agricultural management style -self-sufficiency type- seems to be sustained quite longer. The less favored natural conditions for farming keeps the agricultural management style from being developed to be the level of commercialization. And the poor economic situation of farmers are continuing again and again. With the result of this study, there should be two conditions to be established previously if they want to develop these regions. First, each farm household should get to know of the importance of commercialization and try to spread it. The commercialization. should be attained through the expansion of the environmental friendly agriculture and the improvement of the previously established distribution system of the crops. Secondly, there should be a support from the government. The support will include the expansion of the infrastructures for fanning to improve the fanning conditions and the compensation system directly from the government to the farmers.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.66-66
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• 2020

최근 기후변화로 인한 전 세계적인 기온상승이 야기되고 있으며, 농업에 직접적인 영향을 주는 기상학적 및 수문학적 변화가 급격하게 진행되고 있다. 우리나라의 경우 최근 7년 동안 지역별로 극심한 가뭄이 매년 발생하고 있고, 가뭄의 발생 빈도와 강도가 증가하는 추세이다. 특히 밭의 경우 농업용 저수지 등 수리시설물로부터 관개용수를 공급받는 논 작물과 달리 자연 강우를 통해 필요한 용수량을 공급받는 천수답이 대부분이고 관개시설이 부족하기 때문에, 기후변화에 의한 가뭄의 취약성이 높다. 밭작물은 작물의 생육 시기와 기후 환경, 수자원 환경에 민감하고 토양수분을 흡수함으로써 생육하기 때문에 이러한 밭작물의 소비수량 및 관개용수량은 증발산량 뿐만 아니라 토양내 수분의 이동을 고려하여 수분 부족량을 산정해야 한다. 본 연구에서는 미래 기후변화에 의한 밭가뭄 평가를 위하여 밭 작물별 소비수량 및 관개용수량을 추정하기 위한 밭 토양수분 물수지 모형 (Soil Moisture Model)을 구성하였다. 또한 대표농도경로 (Representative Concentration Pathway, RCP) 시나리오 기반의 제5차 결합기후모델상호비교사업 (Coupled Model Intercomparison Project Phase 5, CMIP5)에서 제공하는 RCP 시나리오를 기반으로 한 전지구 기후모델 (General Circulation Model, GCM)의 기후예측결과를 적용함으로써 미래 밭 가뭄 평가를 수행하였다. 과거 기상자료 및 미래 대표농도경로 시나리오와 작물 기초자료를 수집하여 과거 및 미래 작물증발산량을 산정하였으며, 토양수분 물수지 모형에 적용하여 밭작물의 토양수분 변화를 모의하고 기후변화에 따른 작물별/생육시기별 소비수량 및 관개용수량을 추정하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.2064-2068
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• 2007

합류식 하수도는 오수와 우수를 동시에 배제하는 하수관거 시스템으로 시공이 쉽고 건설비용이 저렴한 반면에 강우시 차집되지 않고 월류되는 유출량으로 인해 수체에 악영향을 초래한다. 관거에서 유출되는 유출수는 강우 초기에 유역에서 집중적으로 유출되는 비점오염원과 하수 및 관거내 오염물질 등을 동반하여 수질 개선을 어렵게 하고 수질 악화를 가중시킨다. 본 연구에서는 기존 유역에 설치된 합류식 하수관거를 분류식으로 개선하고 강우시 초기 세척에 의해 유입하는 비점오염원을 삭감하기 위한 초기우수 처리시설 설치에 따른 M 저수지 수질개선 효과를 수치모델을 사용하여 모의하였다. 저수지의 수질예측은 횡방향 평균 2차원 저수지 수리 및 수질모델인 CE-QUAL-W2를 사용하였다. 저수지 유입량은 군산기상대에서 관측한 일별 강우량 자료를 이용하여 일별 유출량을 산정하였고, 댐 방류량 자료는 M저수지의 2006년 일별 관측수위를 이용하여 유입량과 수위-체적 곡선으로부터 산정하였다. 모델의 보정은 2005년 5월과 8월에 측정한 수질자료를 이용하여 수행하였으며, 저수지의 관측값과 모의결과는 저수지 중앙부 대표지점에서 이루어졌으며, 모델은 관측값을 잘 반영하였다. 모의 결과 M 저수지의 연평균 BOD농도는 합류식(1.25 mg/L)에 비해 분류식 하수 관거(0.91 mg/L)를 도입할 경우 27.2% 개선되었으며, 초기우수 처리시설(0.84 mg/L)을 추가 할 경우 32.8%까지 개선효과가 상승하였다. 기존 합류식 하수관거의 경우 연간 유출부하량은 7,713 kg/yr이었으며, 분류식으로 전환할 경우 2,256 kg/yr, 초기우수처리시설을 추가할 경우 902 kg/yr로 삭감되는 것으로 예측되었다. 분류식하수관거와 초기우수처리를 모두 이행할 경우, BOD와 COD 기준이 호수 수질 기준 II등급 이내로 유지되며, T-P 농도는 0.02mg/L 이하로 유지되어 6월 이후 여름철에 저수지내 조류성장 억제에 효과가 클 것으로 예측되었다. 하수관거 정비사업을 통해 M 저수지는 기존의 농업용 저수지의 목표수질뿐만 아니라, 친수공간으로써 적합한 II등급 수질을 유지할 수 있을 것으로 판단되었다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.2
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• pp.507-519
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• 2013

This study is to evaluate agricultural water supply capacity in Geum river basin (9,865 $km^2$), one of the 5 big river basin of South Korea using MODSIM-DSS (MODified SIMyld-Decision Support System) model. The model is a generalized river basin decision support system and network flow model developed at Colorado State University designed specifically to meet the growing demands and pressures on river basin management. The model was established by dividing the basin into 14 subbasins and the irrigation facilities viz. agricultural reservoirs, pumping stations, diversions, culverts and groundwater wells were grouped and networked within each subbasin and networked between subbasins including municipal and industrial water supplies. To prepare the inflows to agricultural reservoirs and multipurpose dams, the Soil and Water Assessment Tool (SWAT) was calibrated using 6 years (2005-2010) observed dam inflow and storage data. By MODSIM run for 8 years from 2004 to 2011, the agricultural water shortage had occurred during the drought years of 2006, 2008, and 2009. The agricultural water shortage could be calculated as 282 $10^6m^3$, 286 $10^6m^3$, and 329 $10^6m^3$ respectively.

• Korean Journal of Heritage: History & Science
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• v.51 no.3
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• pp.72-87
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• 2018

This study highlights a drainage gate and a ditch, which existed around the whole area of the western shore of Wolji Pond(月池) and focuses on a possible connection between the drainage facility on the western shore and the historical drainage system of Wolji Pond. Specifically, it primarily considered locations and the form of a drainage gate, the relationship between northwestern ditch of Wolji Pond and the drainage gate, and the establishment period and the character of the drainage facility on the western shore. The drainage gate found in excavation in 1975 is determined as the same facility as Surakgu(水落口) recorded on an actual measurement drawing, 1922. Therefore, it is highly probable that there were already the drainage facility in the western shore of Wolji Pond before the 1920s. The drainage gate constructed by processing rectangular stones has four drainage holes for controlling water level. The way of the drainage through the drainage holes is the same as that of the northern shore of Wolji Pond. From a cadastral map drawn in 1913, it is found that the ditch existed in northwest of Wolji Pond. The ditch was proximate to the drainage gate and shared the same axes. Hence, the ditch and the drainage gate are determined as a organic facility connected to the drainage system of Wolji Pond. In particular, the ditch existed in northwest of Wolji Pond is the basis for judging that the drainage facility in the western shore were established before the 1910s. Water flowed in through drainage holes of the drainage gate is drained into the northwest of Wolji Pond, through the ditch. The establishment period and the intention of the drainage facility on the western shore can be interpreted in two aspects. First, they might be 'a agricultural irrigation facility in the Joseon era', given that Wolji Pond was recorded as a agricultural reservoir, and that the whole northwestern area of Wolji Pond was used as farm land areas. Second, they might be 'a drainage facility for controlling the water level in creating Wolji Pond', given that the drainage gate was annexed to the lower shore forming the waterline of Wolji Pond, and that the hight of drainage holes on top of the drainage gate was similar to the full water level of Wolji Pond. Considering the related grounds and circumstance, the latter possibility is high.

• Journal of Environmental Science International
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• v.28 no.9
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• pp.737-749
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• 2019

In this study, the sensitivity analysis of hydraulic conductivity and separation distance (distance between injection well and pumping well) was analyzed by establishing a conceptual model considering the hydrogeologic characteristics of facility agricultural complex in Korea. In the conceptual model, natural characteristics (topography and geology, precipitation, hydraulic conductivity, etc.) and artificial characteristics (separation distance from injection well to pumping well, injection rate and pumping rate, etc.) is entered, and sensitivity analysis was performed 12 scenarios using a combination of hydraulic conductivity ($10^{-1}cm/sec$, $10^{-2}cm/sec$, $10^{-3}cm/sec$, $10^{-4}cm/sec$) and separation distance (10 m, 50 m, 100 m). Groundwater drawdown at the monitoring well was increased as the hydraulic conductivity decreased and the separation distance increased. From the regression analysis of groundwater drawdown as a hydraulic conductivity at the same separation distance, it was found that the groundwater level fluctuation of artificial recharge aquifer was dominantly influenced by hydraulic conductivity. In the condition that the hydraulic conductivity of artificial recharge aquifer was $10^{-2}cm/sec$ or more, the radius of influence of groundwater level was within 20 m, but In the condition that the hydraulic conductivity is $10^{-3}cm/sec$ or less, it is confirmed that the radius of influence of groundwater increases sharply as the separation distance increases.

• Korean Journal of Agricultural Science
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• v.31 no.1
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• pp.53-75
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• 2004

This study is aimed at identifying the national economic value of the irrigation facilities by reviewing the existing papers on economic values of the irrigation facilities and presenting current status of dual O & M problems of the irrigation facilities. This study suggested the unified O & M system rather than continuing the existing dual O & M system of irrigation facilities based on the surveyed results of the activities of irrigation fraternities in Chungnam Province. The findings and proposals for the successful unified and mono O & M system of the irrigation facilities are as follows: (1) Total number of irrigation facilities in the nation accounts for 67,582, while the total length of irrigation and drainage canals amounted to about 174,259km. On account of the total length of structural canals was estimated at 31%, much losses of water and much O & M costs have been inevitable for the full irrigation rice culture. In spite of the past heavy investment for irrigation facilities, the ratio of rain-fed and partially irrigated paddy fields accounts for 23% in 2003. Both Korea Agricultural and Rural Infrastructure Corporation (KARICO) and the city and Gun Governments have managed the irrigation facilities separately by irrigation fraternities. The KARICO have commanded 59% of irrigation paddy area with 18% of the total irrigation facilities, while the city and Gun governments covered 41% of irrigation paddy area with 82% of the existing number of irrigation facilities representing small and medium scale. (2) The 1999 demand prices of irrigation water per ton expressed in 2000 constant market price was estimated at 388 won, the supply price was amounted to 184 won per ton. Considering the supply and demand curve of the irrigation water, the existing irrigation facilities could not satisfy the demand of irrigation water. (3) In 1999, total present added value of the irrigation facilities during the economic life accounted for 48 trillion won, while total supply cost was 44.7 trillion won. The marginal benefit and cost ratio of irrigation water was 1.08. (4) The total O & M cost per year amounting to 681.1 billion won have been required to maintain and repair the existing irrigation facilities in Korea. For the successful unified O & M of irrigation facilities covering whole irrigated paddy field in Korea, 950 billion won of O & M costs are required to keep up the marginal benefit of irrigation water as 2,800 billion won per year. The total O & M cost as 950 billion won should be allocated 40%, 380 billion won for O & M costs of irrigation facilities and 60%, 570 billion won for improvement of irrigation facilities. (5) The study investigated and reviewed the present O & M status of the irrigation facilities by small and medium irrigation fraternities. Most of the farmers belong to the irrigation fraternities preferred not only unified O & M but also KARICO take-over of the whole O & M activities of the irrigation facilities. The prevailing O & M cost per 10a expended by the Corporation was amounted to 104,890 won, while that of city and Gun governments was only amounted to 4,600 won per 10a. regarding the small amount of O & M cost expended by city and Gun governments, it is evident that the existing irrigation system have been managed ineffectively and deteriorated the facilities comparing that of KARICO. In conclusion, the Government could not satisfied the demand of irrigation water by suppling water with existing irrigation facilities. Therefore new additional investment and financial support for irrigation water development should be made to convert rain-fed and partially irrigated paddy fields into fully irrigated ones. The operation and maintenance cost should be supported to keep the marginal values of rice production of existing irrigation facilities in the national economy and to modernize the obsolete irrigation facilities. By unifying the existing dual O & M systems, all the farmers belong to the irrigated paddy fields have to be equally benefited and could be increased their farm income and be stabilized their rural lives.

• Journal of the Korean Society of International Agriculture
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• v.23 no.5
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• pp.513-519
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• 2011

In recent, the cultivation of maize in the world is being increased as a feed for the animal due to the increase of the large amount of meat consumption. However, reduction of supply for the feeding maize by the natural disaster such as drought, flooding, and demanding materials for bioenergy are attributed to increase the cereal price of the world that caused for the fluctuation of prices. The research has been done to provide useful information to the Korean agricultural investor regarding the current status of maize production and distribution in Cambodia. The maize cultivation of Cambodia in 2009 presented as a second major crop at the area of 6.8% in the total crop production area, and it continuously increased maize production yearly basis for the internal uses as well as for the exportation. The total amount of production showed by amount of 0.92 million tons due to the increased production of unit area. The yield production of unit area in current shows about 4 tones per hectare. About 90% of total production produced during August to September at wet season, and area of Batambang province produced about 70% of the total production. The production of feeding maize cultivated about 70% of the total cultivation area, and the exportation have done around 60% and remains were consumed as a domestic uses. The prospects of maize production in Cambodia will be increased due to the acceleration of livestock industry as 8.7% of annual growth rate.

• Journal of Korean Society of Rural Planning
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• v.26 no.3
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• pp.39-47
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• 2020

While agricultural water has been declared free in Korea to ensure access to these limited resource since the year 2000, farmers have however developed lackadaisical behavior towards water saving leading to its scarcity. To overcome this problem, a variety of experience-oriented education model was developed for farmers to promote the adoption of water conservation, and preventive measure against the drought impacts. In this study, farmers' awareness and their attitudinal behavior of agricultural water savings were investigated. The monitoring of water supply structure and the repair facilities in Pohang and Yeongdeok areas were conducted. The field visits and behavioral surveys showed a high degree of over-use and illegal water withdrawals by the farmers due to poor water-saving and management practices. We found that most of the KRC employees strongly admitted the necessity of water-saving education. On the other hand, the farmers showed good interest in the implementation of water-saving awareness through education. Besides this, most farmers agreed to adopt water-saving practices in the fields. Farmers also acknowledged the recklessness of water use was due to the aging of waterways, poor water management, and illegal water consumption. The majority of the farmers responded against imposing the water-use tariffs. However, there was a low response to paying the water-use charge. Aging agricultural facilities and the lack of institutional penalties or incentives were the major obstacles in achieving efficient water-saving. Considering the current drought frequency, urgent water-saving education of farmers was deemed necessary to prepare the farming community against the water shortages. Based on the results of this study, we have to identify the irrigation practices of farmers and provide water-saving education to enforce more efficient use and management of agricultural water.