• Journal of The Korean Society of Agricultural Engineers
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• v.60 no.4
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• pp.63-72
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• 2018

The main function of an agricultural reservoir is to supply irrigation water to paddy rice fields in South Korea. Therefore, the operation of a reservoir is significantly affected by the phenology of paddy rice. For example, the early stage of irrigation season, a lot of irrigation water is required for transplanting rice. Therefore, water storage in the reservoir before irrigation season can be a key factor for sustainable irrigation, and it becomes more important under climate change situation. In this study, we analyzed the climate change impacts on reservoir storage rate at the beginning of irrigation period and simulated the reservoir storage, runoff, and irrigation water requirement under RCP scenarios. Frequency analysis was conducted with simulation results to analyze water supply probabilities of reservoirs. Water supply probability was lower in RCP 8.5 scenario than in RCP 4.5 scenario because of low precipitation in the non-irrigation period. Study reservoirs are classified into 5 groups by water supply probability. Reservoirs in group 5 showed more than 85 percentage probabilities to be filled up from half-filled condition during the non-irrigation period, whereas group 1 showed less than 5 percentages. In conclusion, reservoir capacity to catchment area ratio mainly affected water supply probability. If the ratio was high, reservoirs tended to have a low possibility to supply enough irrigation water amount.

• KCID journal
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• v.7 no.2
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• pp.117-122
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• 2000

• Magazine of the Korean Society of Agricultural Engineers
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• v.37 no.E
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• pp.72-78
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• 1995

To support some knowledge in planning irrigation system, short or long-term irrigation scheduling or determining irrigation reservoir capacity, it is necessary to estimate peak irrigation requirements and seasonal distribution of water demands for various return periods. In this paper Dry Day Index and Probable Evapotranspiration were evaluated to decide seasonal consumptive use of paddy rice for a design year using several decades' daily rainfall data and 5 years'('82~'86) actual evapotranspiration data, respectively. To obtain Dry Day Index that is defined as the number of probable dry days for a given period, Slade unsymmetrical distribution function was adopted. Dry Day Index was analysed for 5 and 10-day intervals. Each of them was evaluated with return periods of 1, 3, 5, 10 and 20 year. Their singnificance was tested by X$^2$ method. Based on these values, the Probable Evaportanspiration, that is the average daily ET both in dry days and rainy days during a given period, was estimated. Crop coefficient was also determined by the modified Penman equation proposed by Doorenbos & Pruitt.

• Journal of The Korean Society of Agricultural Engineers
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• v.46 no.7
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• pp.71-80
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• 2004

A system for estimating daily paddy irrigation water requirements was developed to simulate daily stream flows that reflect various upstream and downstream return flows from river basin. Evapotranspiration in paddy fields was estimated using the modified Penman equation. Daily irrigation water requirements of paddy fields were calculated by multiplying the paddy area and the daily decrease in ponding depth. The system was constructed almost completely using images, grids, etc. in Visual Basic 6.0. The developed model was verified in the Damyang dam, and was used to estimate daily paddy irrigation water requirements at 12 small watersheds in Geum river basin for 20 years, from 1983 to 2002, covering paddy field areas of $3,332\~26,422$ ha. The results on the runoff analysis on the inflow to the Daecheong multi-purpose dam with various return flows were satisfactory. They were reasonable compared to the scenario where return flows were not considered.

• Korean Journal of Agricultural Science
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• v.37 no.3
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• pp.481-490
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• 2010

Baekgog reservoir is located in Jincheon county, Chungbuk province, of which full water levels will be heightened from EL. 100.1 m to EL. 102.1 m, and total storages from 21.75 $Mm^3$ to 26.67 $Mm^3$. The simulation for reservoir inflow was conducted by DAWAST model. The annual average irrigation water was estimated to 33.19 $Mm^3$ supplied to 2,975 ha and the instream flows could be allocated with 0.14 mm/d from October to April with annual average of 2.52 $Mm^3$. The operation rule curve was drawn using inflow, irrigation, and instream flow requirements data. The reservoir water storage was simulated on a daily basis in case of both normal and withdrawal limit operation. In case of normal operation, the annual average irrigation water supply increased from 31.95 $Mm^3$ to 33.32 $Mm^3$, the instream water supply from 2.40 $Mm^3$ to 2.44 $Mm^3$, the water storages from 15.74 $Mm^3$ to 19.88 $Mm^3$, and the water supply reliability from 77.3 % to 81.6 %. In case of operation with withdrawal limit, the amount of instream water supply was 2.52 $Mm^3$ from reservoir regardless of the condition while the water storage increased from 16.77 $Mm^3$ to 20.65 $Mm^3$. The irrigation water supply capacity was appropriate for the case of normal operation with 2 m heightened condition. The present instream water supply capacity was 35,000 $m^3$/d (6.86 $Mm^3$/y) while 42,000 $m^3$/d (8.36 $Mm^3$/y) in 2 m heightened condition in case of withdrawal limit operation.

• Journal of Bio-Environment Control
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• v.24 no.1
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• pp.1-7
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• 2015

Irrigation control plays an important role in improving productivity of paprika which is very sensitive to moisture condition. Among environmental factors, light intensity and distribution are not easily controlled and showed a big difference depending on season and region. For adequate irrigation control, therefore, transpiration and irrigation amounts considering light environmental data should be estimated. In current study, modified transpiration model was used for more precise estimation of transpiration. Seasonal transpiration and irrigation amounts at different regions were compared by using light environmental data provided from Korea Meteorological Administration. The transpiration amount in summer was rather smaller than those in spring and autumn seasons in Korea due to large deviations in light intensity as well as rainy period in summer. Irrigation system capacities at various regions could be recommended by using the transpiration amount in the spring having the longest photoperiod in the year. These results will be useful to the design of irrigation system and optimization of input energy in greenhouse.

• Magazine of the Korean Society of Agricultural Engineers
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• v.30 no.3
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• pp.95-105
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• 1988

This study refers to the development of a hydrologic model simulating daily inflow and release rates for irrigation reservoirs. A daily - based model is needed for adequate operation of an irrigation reservoir sufficing the water demand for paddy fields which is closely related to meteorological conditions. And the objective or this study is to develop a Daily Irrigation Reservoir Operation Model(DIROM) combining the inflow and the release models which depicts the daily water level fluctuations of an irrigation reservoir, and to evaluate the applicability of the model. DIROM was applied to four reservoirs and daily water levels were simulated and compared to the observed data. The model behaviour was also compared with that of a ten - day based model, Reservoir Operation Study(ROS) which has been applied for determining the design capacity of reservoirs. Various combinations of measured and simulated inflow and release rates for tested reservoirs were used to define the daily water level fluctuations. Simulated release rates and measured inflow data resulted in larger errors, and simulated inflow and release rates produced the smallest errors in water level comparison. Two resevoir operation models, DIROM and ROS were applied to the same reservoir and the simulation results compared. The computational errors of DIROM ware smaller than those of ROS, and DIROM was more sensitive to meteorological conditions. DIROM demonstrated its potenial applicability in water management and operation.

• Journal of The Korean Society of Agricultural Engineers
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• v.59 no.4
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• pp.17-26
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• 2017

In this study, EPANET model which is using on the pipe network analysis was applied to Haenam irrigation district has provided irrigation water by pipeline system about 1,125ha and then have built pipe network to study area and supply performance evaluation of existing structure was analyzed by SPA (Single Period Analysis) in EPANET. As model results of simulation average ratio of maximum supply quantity/irrigation water requirements(base demand) was analyzed by 2.63. It means also that was analyzed as being capable of ensuring the water supply capacity. It was provided the necessary information for the maintenance facility through analyzed hydraulic behaviors in the pipeline inside such as flow velocities, pressures and hydraulic grade lines. It was satisfied with the allowable design criteria that was compared analyzed results with presented allowable design standards at agricultural production infra improvement project planning and design (Pipeline design standard). In order to analyze efficiency promotions of irrigation water, using Extended Period Simulation it was compared supply quantity with irrigation water requirements while pumps set operating pattern in 24 hours, then efficiency promotions of irrigation water was determined through analyzed oversupply water quantity and occurrence time by branch lines. According to results for oversupply quantity in Haenam district by time and end of branch lines efficiency promotions of irrigation water was suggested from 0.33 % to 37.59 %. To draw reasonable operating rules for water use and through this research, it is expected to be helpful for efficient water use and operational management of agricultural pipeline system to the current agricultural irrigation.

• Journal of The Korean Society of Agricultural Engineers
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• v.48 no.2
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• pp.27-35
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• 2006

Large dams are managed with operation standard and flood forecasting systems, while small dams do not have management method generally. Shortage of water resources and natural disasters due to drought and flood raised public concerns for management of small dams. Most of small dams are irrigation dams, which need diversified water uses. However, the lack of systematic management of small dams have caused serious water wastage and increased natural disasters. Storage management method and system were developed to solve these problems in small dams. The system was applied to Seongju dam for effective management. The storage management method was established considering hydrology simulation and statistical analysis using the system. This method can bring additional available water, even in the same conditions of the water demand and the supply conditions of watershed. It can improve the flood control capacity and water utilization efficiency by' the flexible operation of storage space.

• KCID journal
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• v.6 no.1
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• pp.74-80
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• 1999