Agricultural drought is a natural phenomenon that is not easy to observe and predict and is difficult to quantify. In South Korea, the amount of agricultural water used is large and the types of use are varied, so even if an agricultural drought occurs due to insufficient precipitation, the drought actually felt in the irrigated area is it can be temporally and spatially different. In order to interpret the general drought in the past, drought disasters were evaluated using single indicators such as drought damage area, precipitation shortage status, and drought index, and a comprehensive drought management system is needed through drought diagnosis survey. Therefore, we intend to conduct research on agricultural drought assessment and diagnosis using re-evaluation of agricultural facilities and irrigation water supply network due to changes in various conditions such as climate change, irrigation canal network, and evaluation of water supply capacity of agricultural facilities. In this study, agricultural drought diagnosis was conducted on two agricultural reservoirs located in Sangju, Gyeongsangbuk-do, with structural or non-structural evaluations to increase spatiotemporal water supply and efficiency in terms of water shortages. The results of the agricultural drought diagnosis evaluation can be used to identify irrigated areas and canal network vulnerable to drought and to prioritize drought response.
Analysis of the Fertilizing Effects of Hydroponic Waste Solution on Lettuce (Lactuca sativa var. captitata) Cultivation - Based on Inorganic Nitrogen Content -
윤성욱 Yun Sung-wook , 임주미 Lim Ju-Mi , 문종필 Moon Jongpil , 장재경 Jang Jaekyoung , 박민정 Park Minjung , 손진관 Son Jinkwan , 이현호 Lee Hyun-ho , 서효민 Seo Hyomin , 최덕규 Choi Duk-Kyu
Analysis of the Fertilizing Effects of Hydroponic Waste Solution on Lettuce (Lactuca sativa var. captitata) Cultivation - Based on Inorganic Nitrogen Content -
윤성욱 Yun Sung-wook , 임주미 Lim Ju-Mi , 문종필 Moon Jongpil , 장재경 Jang Jaekyoung , 박민정 Park Minjung , 손진관 Son Jinkwan , 이현호 Lee Hyun-ho , 서효민 Seo Hyomin , 최덕규 Choi Duk-Kyu
The feasibility of HWS for agricultural use was analyzed through a crop cultivation test to utilize the hydroponic waste solution (HWS) generated from the nutriculture greenhouse. The fertilizing effect of HWS was assessed on the basis of the inorganic nitrogen (N) mostly existed in HWSs, and nitrogen (urea) fertilizer. Lettuce was selected as the target crop influenced by the soil treatment and also for the crop cultivation test. Thus, the change in growth characteristics of lettuce and that in chemical characteristics of the soil were investigated. In terms of the growth of lettuce, the C control group with 70% nitrogen (urea) fertilizer and 30% HWS and the D control group with 50% nitrogen (urea) fertilizer and 50% HWS were more effective than the practice control group (B) with 100% nitrogen (urea) fertilizer. The results of this study confirmed the combined applicability of the chemical fertilizer and HWS for crop cultivation. Because NO3-N present in HWS has a high possibility of leaching into the soil, its applicability as a fertilizer has been considered to be relatively low in Korea. However, if an appropriate mixing ratio of urea fertilizer and HWS could be applied, the problems associated with leaching of nitrate nitrogen could be reduced with beneficial effects on crop cultivation. Thus, future studies are required on the treatment effect of HWS with repeated cultivation, impact assessment on the surrounding environment, and appropriate fertilization methods using nitrogen (urea) fertilizer and HWS. These studies would facilitate the sustainable recycling of HWS.
Development of Extraction Technique for Irrigated Area and Canal Network Using High Resolution Images
윤동현 Yoon Dong-hyun , 남원호 Nam Won-ho , 이희진 Lee Hee-jin , 전민기 Jeon Min-gi , 이상일 Lee Sang-il , 김한중 Kim Han-joong
For agricultural water management, it is essential to establish the digital infrastructure data such as agricultural watershed, irrigated area and canal network in rural areas. Approximately 70,000 irrigation facilities in agricultural watershed, including reservoirs, pumping and draining stations, weirs, and tube wells have been installed in South Korea to enable the efficient management of agricultural water. The total length of irrigation and drainage canal network, important components of agricultural water supply, is 184,000 km. Major problem faced by irrigation facilities management is that these facilities are spread over an irrigated area at a low density and are difficult to access. In addition, the management of irrigation facilities suffers from missing or errors of spatial information and acquisition of limited range of data through direct survey. Therefore, it is necessary to establish and redefine accurate identification of irrigated areas and canal network using up-to-date high resolution images. In this study, previous existing data such as RIMS (Rural Infrastructure Management System), smart farm map, and land cover map were used to redefine irrigated area and canal network based on appropriate image data using satellite imagery, aerial imagery, and drone imagery. The results of the building the digital infrastructure in rural areas are expected to be utilized for efficient water allocation and planning, such as identifying areas of water shortage and monitoring spatiotemporal distribution of water supply by irrigated areas and irrigation canal network.
Emission Characteristics of Greenhouse Gases (CH4, N2O) in Mechanically Ventilated Swine Farm during Winter Season
박준용 Park Junyong , 정민웅 Jung Minwoong , 조광곤 Jo Gwanggon , 장유나 Jang Yu-Na
The emission characteristics and emission factors were determined by measuring the concentration of methane (CH4) and nitrous oxide (N2O), the amount of ventilation, etc. in the two fattening rooms which have the same environment in winter. As a result of monitoring, the average concentration of CH4 and N2O was 20.7-26.7 ppm and 1.4-1.6 ppm. The average temperature inside the room was measured at 20.0-21.4℃, and the average ventilation was 1345.4-1567.3 ㎥/h. The daily emission of CH4 for the first 30 days showed a constant emission of 3.6-8.2 g/d/㎡/pig, but thereafter, the emission increased rapidly. The daily emission of N2O was 0.7-1.3 g/d/㎡/pig, showing stable emission during the test period, and relatively insignificant emission compared to the emission of CH4. After repeated test, it was confirmed that there was no significant difference between the two rooms. As a result, the CH4 6 . 21 g /d/㎡/pig and N2O 1.02 g/d/㎡/pig average emission for each room was derived.
Analysis of the Influence of Factors Affecting the Relationship Continuity of Rural Experience Tour - Focusing on the Comparison between Men and Women -
정상숙 Jeong Sang Sook , 윤성수 Yoon Seong Soo , 송창섭 Song Chang Seob , 맹승진 Maeng Seung Jin
Analysis of the Influence of Factors Affecting the Relationship Continuity of Rural Experience Tour - Focusing on the Comparison between Men and Women -
정상숙 Jeong Sang Sook , 윤성수 Yoon Seong Soo , 송창섭 Song Chang Seob , 맹승진 Maeng Seung Jin
The purpose of this study is to analyze the factor influencing in order to increase the intention to revisit rural experience tourism. 181 men and women who had experienced rural experience tourism were surveyed in a Self-Assessment Questionnaire. Some farming experience, life experience, cultural experience, and leisure experience were set as independent variables as representative programs of rural experience tourism, satisfaction and trust as mediated variables, and relationships as dependent variables. Here, the relationship is regarded as a variable representing the intention to revisit. When performing multi-group path analysis by separating men and women, both men and women had a statistically significant positive (+) effect in the Leisure experience→Satisfaction path and the Trust→Relation path. In addition, the paths that were statistically significant for women were not statistically significant, but were statistically significant only for men were Farm experience→Satisfaction path, Farm experience→Relation path, and Leisure experience→Relation path. In addition, the paths that were not statistically significant for men, but statistically significant for women were Culture experience→Satisfaction and Trust→Satisfaction. According to this study, in order to increase the intention to revisit, both men and women should consider leisure experience. And men should emphasize farming experience, while women should emphasize cultural experience. It is considered that there is a need to further subdivide leisure experience, farming experience and cultural experience for the region. This study has a limitation of only 181 people. More large-scale research will be possible in the future.
Water Budget Assessment for Soybean Grown in Paddy Fields Converted to Uplands Using APEX Model
최순군 Choi Soon-kun , 정재학 Jeong Jaehak , 엽소진 Yeob So-jin , 김명현 Kim Myung-hyun , 김민경 Kim Min-kyeong
The expansion of upland crop cultivation in rice paddy fields is recommended by the Korean government to solve the problem of falling rice price and reduction of rice farmer’s income due to oversupply of rice. However, water use efficiency is significantly influenced by the land use change from paddy field to upland. Therefore, this study aimed to evaluate the water budget of soybean grown in using APEX (Agricultural Policy and Environmental eXtender) model. The amount of runoff was measured in a test bed located in Iksan, Jeollabu-do and used to calibrate and validate the simulated runoff by APEX model. From 2019 to 2020, the water budget of soybean grown in uplands were estimated and compared with the one grown in paddy fields. The calibration result of APEX model for runoff showed that R2 (Coefficient of determination) and NSE (Nash-Sutcliffe efficiency) were 0.90 and 0.89, respectively. In addition, the validated results of R2 and NSE were 0.81 and 0.62, respectively. The comparative study of each component in water budget showed that the amounts of evapotranspiration and percolation estimated by APEX model were 549.1 mm and 375.8mm, respectively. The direct runoff amount from upland was 390.1 mm, which was less than that from paddy fields. The average amount of irrigation water was 28.7 mm, which was very small compared to the one from paddy fields.
Climate Resilience Assessment of Agricultural Water System Using System Dynamics Model
This study aims at testing a hypothesis that the resilience of agricultural water systems is characterized by trade-offs and synergies of effects from climate and socioeconomic change. To achieve this, an Agricultural Water System Climate Resilience Assessment (ACRA) framework is established to evaluate comprehensive resilience of an agricultural water system to the combined impacts of the climate and socioeconomic changes with a case study in South Korea. Understanding dynamic behaviors of the agricultural water systems under climate and socioeconomic drivers is not straightforward because the system structure includes complex interactions with multiple feedbacks across components in water and agriculture sectors and climate and socioeconomic factors, which has not been well addressed in the existing decision support models. No consideration of the complex interactions with feedbacks in a decision making process may lead to counterintuitive and untoward evaluation of the coupled impacts of the climate and socioeconomic changes on the system performance. In this regard, the ACRA framework employs a System Dynamics (SD) approach that has been widely used to understand dynamics of the complex systems with the feedback interactions. In the ACRA framework applied to the case study in South Korea, the SD model works along with HOMWRS simulation. The ACRA framework will help to explore resilience-based strategies with infrastructure investment and management options for agricultural water systems.
Evaluation of Parameter Estimation Method for Design Rainfall Estimation
김귀훈 Kim Kwihoon , 전상민 Jun Sang-min , 장정렬 Jang Jeongyeol , 송인홍 Song Inhong , 강문성 Kang Moon-seong , 최진용 Choi Jin-yong
Determining design rainfall is the first step to plan an agricultural drainage facility. The objective of this study is to evaluate whether the current method for parameter estimation is reasonable for computing the design rainfall. The current Gumbel-Kendall (G-K) method was compared with two other methods which are Gumbel-Chow (G-C) method and Probability weighted moment (PWM). Hourly rainfall data were acquired from the 60 ASOS (Automated Synoptic Observing System) stations across the nation. For the goodness-of-fit test, this study used chi-squared (χ2) and K olmogorov- Smirnov (K-S) test. When using G-K method, χ2 statistics of 18 stations exceeded the critical value (X2a=0.02,df=4=9.4877) and 10, 3 stations for G-C method, PWM method respectively. For K-S test, none of the stations exceeded the critical value (Da=0.05n=0.19838). However, G-K method showed the worst performances in both tests compared to other methods. Subsequently, this study computed design rainfall of 48-hour duration in 60 ASOS stations. G-K method showed 5.6 and 6.4% higher average design rainfall and 15.2 and 24.6% higher variance compared to G-C and PWM methods. In short, G-K showed the worst performance in goodness-of-fit tests and showed higher design rainfall with the least robustness. Likewise, considering the basic assumptions of the design rainfall estimation, G-K is not an appropriate method for the practical use. This study can be referenced and helpful when revising the agricultural drainage standards.
Evaluation of Agricultural Reservoirs Operation Guideline Using K-HAS and Ratio Correction Factor during Flood Season
Despite the practical limitations of calculating the amount of inflow and supply related to the operation of agricultural reservoirs, the role of agricultural reservoirs is gradually being emphasized. In particular, as interest in disaster safety has increased, the demand for preliminary measures to prepare for disasters has been rising, for instance, pre-discharging agricultural reservoirs for flood control. The aim of this study is to analyze the plans for the flood season reservoir operation considering pre-discharge period and water level limit. Accordingly, we optimized the simulation of daily storage using the ratio correction factor (RCFs) and analyzed the amount of inflow and supply using K-HAS. In addition we developed the drought determination coefficient (k) as a indicator of water availability and applied it for supplementing the risk level criteria in the Drought Crisis Response Manual. The results showed that it would be difficult to set the water level limit during the flood period in the situation of little water supply for flood control in agricultural reservoirs. Therefore, it is necessary to operate the reservoir management regulations after measures such as securing additional storage water are established in the future.
