• Journal of The Korean Society of Agricultural Engineers
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• v.56 no.5
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• pp.77-87
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• 2014

The impacts of climate change on upland crops is great significance for water resource planning, estimating crop water demand and irrigation scheduling. The objective of this study is to predict upland crop evapotranspiration, effective rainfall and net irrigation requirement for upland under climate change, and changes in the temporal trends in South Korea. The changes in consumptive use and net irrigation requirement in the six upland crops, such as Soybeans, Maize, Potatoes, Red Peppers, Chinese Cabbage (spring and fall) were determined based on the soil moisture model using historical meteorological data and climate change data from the representative concentration pathway (RCP) scenarios. The results of this study showed that the average annual upland crop evapotranspiration and net irrigation requirement during the growing period for upland crops would increase persistently in the future, and were projected to increase more in RCP 8.5 than those in RCP 4.5 scenario, while effective rainfall decreased. This study is significant, as it provides baseline information on future plan of water resources management for upland crops related to climate variability and change.

• KCID journal
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• v.2 no.2
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• pp.54-58
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• 1995

• Journal of The Korean Society of Agricultural Engineers
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• v.56 no.4
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• pp.1-8
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• 2014

Appropriate amount of water supply to paddy fields in proper time is important to achieve efficient agricultural water management. The purpose of this study is to evaluate the irrigation water supply adequacy for paddy fields using water level data in irrigation canals. For the evaluation, the real-time water level data were collected from main canals in the Dongjin irrigation district for 2 years. Using the water level data, delivered irrigation water amounts at the distribution points of each canal were calculated. The water balance model for paddy field was designed considering intermittent irrigation and the irrigation water requirement was estimated. Irrigation water supply adequacy was analyzed from main canals to the irrigation blocks based on the comparison between estimated requirement and delivered irrigation water amounts. From the adequacy analysis, irrigation water supply showed poor management condition in 2012 with low efficiency except the Daepyong canal section, and the adequacy in 2013 was good or fair except the Yongsung canal section. When irrigation water for paddy fields was insufficient, water supply adequacy was affected by irrigation area, but when irrigation water was enough to supply, adequacy was affected by distance from main canal to distribution points. These results of the spatial and temporal dimensions of the irrigation adequacy could be utilized for efficient irrigation water management to improve the temporal uniformity and equity in the water distribution for paddy fields.

• Water Engineering Research
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• v.5 no.3
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• pp.123-131
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• 2004

This paper describes the use of spatial interpolation for estimating seasonal crop potential evapotranspiration (PET) and irrigation water requirement in unmeasured evaporation gage stations within Edwards Aquifer, Texas using GIS. The Edwards Aquifer area has insufficient data with short observed records and rare gage stations, then, the investigation of data for determining of irrigation water requirement is difficult. This research shows that spatial interpolation techniques can be used for creating more accurate PET data in unmeasured region, because PET data are important parameter to estimate irrigation water requirement. Recently, many researchers are investigating intensively these techniques based upon mathematical and statistical theories. Especially, three techniques have well been used: Inverse Distance Weighting (IDW), spline, and kriging (simple, ordinary and universal). In conclusion, the result of this study (Table 1) shows the kriging interpolation technique is found to be the best method for prediction of unmeasured PET in Edwards aquifer, Texas.

• Journal of The Korean Society of Agricultural Engineers
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• v.63 no.1
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• pp.27-35
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• 2021

KRC (Korea Rural Community Corporation) is in charge of about 3,400 agricultural reservoirs out of 17,240 agricultural reservoirs, and automatic water level gauges in reservoirs and canals were installed to collect reservoir and canal water level data from 2010. In this study, 10-minute water level data of 173 reservoir irrigation canals from 2016 to 2018 are collected, and discharge during irrigation season was calculated using rating curves. For estimation of water supply, irrigation water requirement was calculated with HOMWRS (Hydrological Operation Model for Water Resources System), and the summation of reservoir water storage decrease was calculated with daily reservoir storage data from RAWRIS (Rural Agricultural Water Resource Information System). From the results, the total yearly amount of irrigation water supply showed less than 10% difference than the irrigation water requirement. The regional analysis revealed that reservoirs in Jeollanam-do and Chungcheongnam-do supply greater irrigation water than average. On the contrary, reservoirs in Gyeongsangnam-do and Chungcheongbuk-do supply less than others. This study was conducted with a limited number of reservoirs compared to total agricultural reservoirs. Nevertheless, it can indicate irrigation water supply from agricultural reservoirs to provide information about agricultural water use for irrigation.

• Journal of the Korean Association of Geographic Information Studies
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• v.23 no.4
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• pp.120-139
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• 2020

This study is to assess the future agricultural land use and climate change impacts on irrigation water requirement using CLUE-s(Conversion of Land Use and its Effects at Small regional extent) and RCP(Representative Concentration Pathway) 4.5 and 8.5 HadGEM3-RA(Hadley Centre Global Environmental Model version 3 Regional Atmosphere) scenario. For Nonsan city(55,517.9ha), the rice paddy, upland crop, and greenhouse cultivation were considered for agricultural land uses and DIROM(Daily Irrigation Reservoir Operation Model) was applied to benefited areas of Tapjeong reservoir (5,713.3ha) for Irrigation Water Requirement(IWR) estimation. For future land use change simulation, the CLUE-s used land uses of 2007, 2013, and 2019 from Ministry of Environment(MOE) and 6 classes(water, urban, rice paddy, upland crop, forest, and greenhouse cultivation). In 2100, the rice paddy and upland crop areas decreased 5.0% and 7.6%, and greenhouse cultivation area increased 24.7% compared to 2013. For the future climate change scenario considering agricultural land use change, the RCP 4.5 and RCP 8.5 2090s(2090~2099) IWR decreased 2.1% and 1.0% for rice paddy and upland crops, and increased 11.4% for greenhouse cultivation compared to pure application of future climate change scenario.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.5
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• pp.683-689
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• 2012

This research was carried out to investigate the effect of installation spacing of subsurface drip irrigation pipe on the mineral content, nutrient uptake, yield of lettuce, water requirement for irrigation, and soil chemical properties in greenhouse cultivation. Semi-forcing and retarding culture were implemented in this experiment, with four treatments containing overhead spray irrigation and three subsurface irrigation lateral spacing intervals of 30, 40, 50 cm at a depth of 30 cm from soil surface, respectively. Each mineral content of lettuce grown under subirrigation system did not show significant difference between treatments, however the uptake of nutrients was lower at 50 cm-distance. The yield was largest in 30 cm-subirrigation (SI), followed by 40 cm-SI, overhead spray, and 50 cm-treatment. Water requirement for irrigation was highest in overhead spray, and it was in reverse proportion to the distance of irrigation pipes. $NO_3$-N content in the soil, at a depth of 10 cm, showed a higher value in 50 cm-SI, followed by 40 cm-SI, overhead spray and 30 cm-SI. Exchangeable K content was highest in 50 cm-SI, Mg was highest in 40 cm-SI, and Ca was lowest in 30 cm-SI. In conclusion, the lettuce yield was not different between 30 and 40 cm-SI, but water requirement for irrigation was lower as the distance of irrigation pipes was further. And it seems to be needed more precise research on this theme, because crop yield and the dynamics of soil minerals in subsurface irrigation can vary with the depth and distance of irrigation pipes, dripper, water flow depending on the soil texture, and plant response to soil minerals.

• Journal of The Korean Society of Agricultural Engineers
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• v.53 no.4
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• pp.39-47
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• 2011

The aim of the study is to predict potential evapotranspiration and crop water requirement using meteorological data from MIROC3.2 with A1B scenario. Increase of evapotranspiration due to temperature rise can be observed out of the analysis, while effective rainfall decreased. The evapotranspiration elevation results in large amount of crop water requirement in the paddy farming. It can be seen that rainfall intensification at non-irrigation period brings effective rainfall decrease, while contributes to higher demand of crop water at irrigation period. It is necessary to secure additional water resources to adapt the climate change. It is expected that estimation on potentialevapotranspiration in this study can be used for formulation of master plan of water resources.

• Journal of The Korean Society of Agricultural Engineers
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• v.61 no.2
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• pp.97-104
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• 2019

The purpose of this study was to establish the estimation method of irrigation water amount for sewage treated water reuse for agricultural purpose. To calculate the irrigation water amount, we adopted Penman-Monteith for potential evapotranspiration estimation and applied crop coefficient and irrigation efficiency factor. We developed the irrigation water amount calculation program using C language in Xcode environment. The target district for calculation is having 259 ha of agricultural land located near the Jinyeong Clear Water Circulation Center in Hanrim-myeon, Gimhae city. The meteorological data of the study area were obtained from Changwon weather station from 1986 to 2017. Calculated average and maximum of annual mean potential evapotranspiration were 2.72 mm/day and 6.22 mm/day, respectively. We used K-S (Kolmogorov-Smirnov) for goodness-of-fit test to find optimal probability distribution of annual mean and maximum evapotranspiration. As a result, the normal distribution was selected for the appropriate distribution. The annual mean and maximum potential evapotranspiration for 10-year return period by applying normal distribution were 2.88 mm/day and 6.76 mm/day, respectively. Assuming that the irrigation efficiency is 80%, the irrigation water requirement was calculated as $36.05m^3/day/ha$ and $84.45m^3/day/ha$, respectively, when annual mean and maximum potential evapotranspiration were applied. The actual irrigation water amount can be calculated by applying the crop coefficient and cropping days for the study area based on the developed irrigation water amount estimation program in this study.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.46 no.1
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• pp.6-11
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• 2001

In this lysimeter experiment, temporal changes of water percolation rate, irrigation requirement and ${No}_3$－-N leaching were investigated under different cultural practices that were no-till direct seeding on flooded paddy (NTDSF), till direct seeding on flooded paddy (TDSF), and transplanting. The highest water percolation rate of 3,001 l/$m^2$ was measured in NTDSF. Others were 2,551 l/$m^2$ and 2,210 l/$m^2$ in TDSF and transplanting. Water percolation rate in NTDSF and TDSF was increased by 36% and 15% compared to transplanting. Water percolation rates in all cultural practices were increased remarkably from the reproductive growth stage and relatively large amount of water loss through percolation was measured even after the reproductive growth stage. A total irrigation requirement was 3,469 l/$m^2$ in NTDSF and 2,898 l/$m^2$ in TDSF. That was equivalent to 45% and 21 % of increase compared to 2,389 l/$m^2$ in transplanting. The largest ${No}_3$－-N leaching through the entire rice growing period was 701 mg/$m^2$ in NTDSF and was followed by 494 mg/$m^2$ in TDSF and 465 mg/$m^2$ in transplanting. The ratios to the total amount of ${No}_3$－-N leaching at the vegetative growth stage, reproductive growth stage and ripening stage were 31 %, 41 % and 28% in NTDSF; 21 %, 48% and 31 % in TDSF; and 18%, 48% and 35 % in transplanting.