• 한국농공학회논문집
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• 제55권3호
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• pp.63-73
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• 2013

The objectives of this study were to develop a hydrologic simulation model to estimate surface drainage for irrigation districts consisting of paddy and protected cultivation, and to evaluate the applicability of the developed model. The model consists of three sub-models; agricultural supply, paddy block drainage, and protected cultivation runoff. The model simulates daily total drainage as the sum of paddy field drainage, irrigation canal drainage, and protected cultivation runoff at the outlets of the irrigation districts. The agricultural supply sub-model was formulated considering crop water requirement for growing seasons and agricultural water management loss. Agricultural supply was calculated for use as input data for the paddy block sub-model. The paddy block drainage sub-model simulates paddy field drainage based on water balance, and irrigation canal drainage as a fraction of agricultural supply. Protected cultivation runoff is calculated based on NRCS (Natural Resources Conservation Service) curve number method. The Idong reservoir irrigation district was selected for surface drainage monitoring and model verification. The parameters of model were calibrated using a trial and error technique, and validated with the measured data from the study site. The model can be a useful tool to estimate surface drainage for irrigated districts consisting of paddy and protected cultivation.

• 한국환경복원기술학회지
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• 제14권1호
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• pp.35-42
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• 2011

The current study analyzed appropriateness of abandoned rice paddy wetlands as habitats for the Amphibia by assessing functions and value of abandoned rice paddy wetlands within land development districts as a habitat for living creatures and researching into the Amphibia living in the subject districts. For this purpose, the study designated abandoned rice paddy wetlands within Hwaseong A District and Pangyo B District under land development as subject lands. Those wetlands went through succession after abandonment of farming. Detailed study results are as follows. From classification of wetland types and an analysis of their characteristics, it was found that herbaceous plants such as smartweed communities, horsetail communities and reed communities, and woody plants such as pussy willow communities appeared in both districts. These abandoned rice paddy wetlands shows typical characteristics of palustrine wetlands. As a result of a vegetation structure research, it was observed that succession has been progressed for at least over 2~3 years. In assessment of wetland functions by item, it was found that they are developing into fine wetlands in terms of functions because they are ranked over Moderate Class except separate distance from streams. Also from a research into animals living in the abandoned rice paddy wetlands, it was found that main inhabitants are Rana nigromaculata,Rana dybowskii, Hyla japonica, Bufo bufo gargarizans, etc. It can be confirmed that the abandoned rice paddy wetlands are providing appropriate conditions as habitats to the Amphibia in a view that those species have life cycles of inhabitation (shores and wetlands) - egg-laying (rice paddy, puddles and swampy places) - hibernation (rice field banks and swampy places). From this point of view, it was found that abandoned rice paddy wetlands that developed because of abandonment of farming can be used as means to improve structure and functions of habitats.

• 한국농공학회논문집
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• 제56권2호
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• pp.1-9
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• 2014

A modeling system is constructed by integrating an one-dimensional unsteady flow simulation model and a hydrologic model to simulate flood flows in drainage channel networks of paddy field districts. The modeling system's applicability is validated by simulating flood discharges from a paddy field district, which consists of nine paddy fields and one drainage channel. The simulation results are in good agreement with the observed. Particularly, in the verification stage, the relative errors of peak flows and peak depths between the observed and simulated hydrographs range 8.96 to 10.26 % and -10.26 to 2.97 %, respectively. The modeling system's capability is compared with that of a water balance equation-based model; it is revealed that the modeling system's accuracy is superior to the other model. In addition, the simulations of flood discharges from large-sized paddy fields through drainage channels show that the flood discharge patterns are affected by drainage outlet management for paddy fields and physical characteristics of the drainage channels. Finally, it is concluded that to efficiently design drainage channel networks, it is necessary to analyze the results from simulating flood discharges of the drainage channel networks according to their physical characteristics and connectivities.

• 한국농공학회논문집
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• 제63권6호
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• pp.27-37
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• 2021

Conversion of rice paddy field to upland has been accelerated as the central government incentivizes more profitable upland crop cultivation. The objective of this study was to investigate the current status and conversion trend from paddy to upland for the reservoir irrigation districts. Total 605 of reservoir irrigation districts whose beneficiary area is greater than 200 ha were selected for paddy-to-upland conversion analysis using the land cover maps provided by the EGIS of the Ministry of Environment. The land cover data of 2019 was used to analyze up-to-date upland conversion status and its correlation with city proximity, while land cover change between 2007 and 2019 was used for paddy-to-upland conversion trend analysis. Overall 14.8% of the entire study reservoir irrigation area was converted to upland cultivation including greenhouse and orchard areas. Approximately the portion of paddy area was reduced by 17.8% on average, while upland area was increased by 4.9% over the 12 years from 2007 to 2019. This conversion from paddy to upland cultivation was more pronounced in the Gyoenggi and Gyeongsang regions compared to other the Jeolla and Chungcheong provinces. The increase of upland area was also more notable in proximity of the major city. This study findings may assist to identify some hot reservoir districts of the rapid conversion to upland cultivation and thus plan to transition toward upland irrigation system.

• 한국농공학회논문집
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• 제61권4호
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• pp.87-96
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• 2019

The objective of this study was to develop a general inundation modeling technique considering the effect of drainage delay in the paddy field districts. In most studies, farmland inundation simulations have been conducted using previously developed watershed models. However, the water cycle in the paddy fields has a different structure from that of the general watershed, and the effect of the drainage delay should be considered. In this study, the drainage delay algorithm was developed using water balance equation, and the inundation modeling was performed for inundation-prone paddy fields located near Doowol stream. As a result, the depth of inundation was 43.1 cm and 45.2 cm, respectively, due to the 100-year and 200-year frequency rainfall. With the operation of drainage pump ($0.1m^3/s$), inundation depths decreased by 5.8 cm and 6.0 cm, respectively, and inundation time reduced by 20 hours and 21 hours, respectively for the 100-year and 200-year frequency rainfall. The result showed that the general inundation modeling technique developed in this study could reflect the effect of drainage delay due to the rise of external water level and the flooding reduction effect by operation of drainage pump. The results of this study are expected to be useful to establish measures for damage caused by farmland inundation.

• 한국농공학회논문집
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• 제46권3호
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• pp.17-30
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• 2004

This study aimed to develop an agricultural drought assessment methodology for irrigated paddy field districts from a single reservoir. Agricultural drought was defined as the reservoir storage shortage state that cannot satisfy water requirement from the paddy fields. The suggested model, SRADEMP (a Single Reservoir Agricultural Drought Evaluation Model for Paddy), was composed of 4 submodels: PWBM (Paddy Water Balance Model), RWBM (Reservoir Water Balance Model), FA (Frequency and probability Analysis model), and DCI (Drought Classification and Indexing model). Two indices, PDF (Paddy Drought Frequency) and PDI (Paddy Drought Index) were also introduced to classify agricultural drought severity Both values were divided into 4 steps, i.e. normal, moderate drought, severe drought, and extreme drought. Each step of PDI was ranged from +4.2 to -1.39, from -1.39 to -3.33, from -3.33 to -4.0 and less than -4.0, respectively. SRADEMP was applied to Jangheung reservoir irrigation district, and the results showed good relationships between simulated results and the observed data including historical drought records showing that SRADEMP explains better the drought conditions in irrigated paddy districts than PDSI.

• 농촌계획
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• 제26권2호
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• pp.51-59
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• 2020

In this study, we analyzed the characteristics of 511 agricultural districts through statistical data, and classify these districts as the vulnerable area to drought through correlation and cluster analysis. The criteria for classification was related to ground-water recharge, irrigation water demand, and water supply. As a result, 8 types of agricultural districts were extracted. For example, the type 1 indicated the high priority area for ground-water development, thus the districts which were classified as type 1 showed ground-water use was less than 80 % of maximum capacity, and irrigation water supply was only 37.5 % and 76.5 % of irrigation water demand in upland and paddy field, respectively. As a result, 44 of 511 districts were classified as type 1.36 districts (types 5-8) were areas where groundwater development is limited. The results of this study are expected to provide useful information for establishing the direction of the rural area development project in connection with the revitalization of policy of people return to rural area.

• 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.

• 한국토양비료학회지
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• 제44권3호
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• pp.347-352
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• 2011

친환경농업은 합성농약, 화학비료 등 화학 투입제의 사용을 최대한 줄이고 자원의 재활용을 가능케 하여 지역자원과 환경을 보전하면서 장기적으로 일정한 생산성과 수익성을 확보하고 안전한 식품을 생산하는 것이다. 본 연구는 호남지역 친환경 농업지구 논 토양의 환경특성을 조사하여 토양관리 기준을 설정코자 2007년도에 충남, 전북, 전남지역에서 쌀겨농법 2지구, 쌀겨+왕우렁이농법 8지구, 왕우렁이농법 5지구, 오리농법 3지구로 총 18지구를 선정하여 친환경 농법별 토양화학성을 분석하고 농가설문 및 토양물리성을 조사하였다. 친환경농업지구의 토양물리성중 토양경도는 관행농법보다 낮았으며 특히 쌀겨를 시용한 농법의 토양경도가 다른 친환경농법 보다 약간 낮았다. 또한 친환경농업지구의 토양화학성 중 유효인산과 유효규산 함량은 적정수준보다 약간 낮았으며 친환경농법 중 쌀겨를 시용한 농법의 유효인산과 유효규산 함량은 다른 친환경농법 보다 약간 낮았다. 작물별 시비처방 기준에 따라 토양 양분 부족분에 대한 시비량 ($N-P_2O_5-K_2O$)을 계산한 결과 쌀겨농법에서는 $83-49-30kg\;ha^{-1}$, 쌀겨+왕우렁이 농법 $77-48-30kg\;ha^{-1}$, 왕우렁이농법 $84-42-33kg\;ha^{-1}$, 오리농법 $86-36-34kg\;ha^{-1}$로 나타났다.

• 한국응용곤충학회지
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• 제30권1호
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• pp.58-64
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• 1991

수도포장과 휴반에서 발생하는 노린재종의 분포와 반점미 발생 관계를 조사한 결과를 휴반에서 총 21종의 노린재가 채집, 분류되었으며, 그중 우점종은 가시점둥글노린재, 긴날개쐐기노린제였고, 수도포장에서는 11종이 동정되었으며 우점종은 긴날개쐐기노린재, 설상무늬장님 노린재, 가시점동글노린재이었다. 노린재 종별 반점미 발생율은 가시점둥글노린재가 가장 심하여 34.7%였고 그 다음은 붉은잡초노린재로 2.7%였다. 노린재가 주로 벼의 유숙기를 중심으로 출수기에서 황숙기에 피해를 주었을 때 반점미 발생이 많았고, 품종별로는 극조생 또는 조생종 품봉인 태백벼, 소백벼, 삼강벼 등에서 심하였다. 지역별 반점미 발생은 조생종 품종이 재배되는 포천등 내장산간지에서 많았다.