• Journal of The Korean Society of Agricultural Engineers
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• v.66 no.5
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• pp.67-79
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• 2024

Water balance analysis in heightened reservoirs, which have been raised to ensure a stable supply of irrigation water and secure water against floods and heavy rainfall, is essential for evaluating water supply capacity and reservoir maintenance. The consecutively linked reservoir system, which involves preserving the existing embankment while constructing a new one, affects the water balance between the existing and new reservoirs. This study aims to analyze the linked water balance between reservoirs in a consecutively linked reservoir system using the DIROM (Daily Irrigation Reservoir Operation Model) model. Surveys were conducted to investigate actual water use, and multiple water supply quantities were estimated based on these findings. Methods to supplement missing data and improve the limitations of simulated inflow were proposed and applied, and the performance of the daily storage simulation was evaluated. By supplementing the missing water use data, the NSE (Nash-Sutcliffe Efficiency) of the Sonhang reservoir storage rate simulation improved by approximately 30%. Additionally, result of using inflow coefficients significantly enhanced the simulation performance for the Sonhang2 and Sonhang reservoirs. This study confirms the necessity of incorporating appropriate inflow coefficients in reservoir design to overcome the model's tendency to overestimate inflow, highlighting the critical importance of quality control in observational data. The findings are expected to be useful for the design and analysis of future reservoir systems through embankment heightening.

• Journal of The Korean Society of Agricultural Engineers
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• v.63 no.2
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• pp.1-10
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• 2021

Agricultural reservoirs have a great influence on the water circulation in the watershed. It is necessary to evaluate the impact on water circulation by the agricultural reservoir. Therefore, in this study, we simulated the agricultural watershed through linkage of Hydrological Simulation Program Fortran (HSPF) and Module-based hydrologic Analysis for Agricultural watershed (MASA) and evaluated the contribution of the agricultural reservoir to water circulation by watershed water circulation index. As a result of simulating the Idong reservoir watershed through the HSPF-MASA linkage model, the model performance during the validation period was R2 0.74 upstream, 0.78 downstream, and 0.76 reservoir water level, respectively. To evaluate the contribution of agricultural reservoirs, three scenarios (baseline, present state, and present state without reservoir) were simulated, and the water balance differences for each scenario were analyzed. In the evaluation through the agricultural water circulation rate in the watershed, it was found that the water circulation rate increased by 1.1%, and the direct flow rate decreased by 13.6 mm due to the agricultural reservoir. In the evaluation through the Budyko curve, the evaporation index increased by 0.01. Agricultural reservoirs reduce direct runoff and increase evapotranspiration, which has a positive effect on the water circulation.

• 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.

• Magazine of the Korean Society of Agricultural Engineers
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• v.35 no.2
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• pp.65-72
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• 1993

When a drought occurs in an area irrigated by multi-reservoirs, onerating a single reservoir separately to control the reservoir' storage is not a desirable solution. In order to reduce damages effectively for the areal drought, the storage of the reservoirs within the areal boundary should be managed as a group. Storage management procedures are as follows : 1. Collecting and checking the present storages of all reservoirs 2. Computing the drought frequency and depth; and finally, establishing a suitable storage saving strategy based on the estimated drought depth. For the purpose of this storage management, the RESTOMS(Reservoirs Storage Management System) was developed and the system was composed of the PRIME computer and the ORACLE as a distributed database management system, which was the host computer of Rural Development Corporation and would be on-lined with the regional offices throughout the country. Reservoirs operated by Farm Land Improvment Association were comprised in the DB system. Using the RESTOMS, the drought frequencies and drought depths were calculated with respect to the reservoir storage records(1967 to 1992). It was obvious that the results were closely corresponding to the real drought records.

• Journal of Korean Society of Rural Planning
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• v.7 no.1 s.13
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• pp.89-98
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• 2001

This study was carried out to provide the basic informations for the water quality management in Boryung fresh water reservoir watershed. Four agricultural reservoirs were selected and the water qualify of the reservoirs were investigated from November 1998 to December 2000, periodically. Including storage rate, temporal variation of water quality constituents such as water temperature, pH, EC, total nitrogen, total phosphorus were analysed. The result showed that pH ranged $6.7{\sim}10.4$, EC $56.1{\sim}1079{\mu}S/cm$, COD $0.75{\sim}8.0mg/L$, respectively. And, total-N concentration affected by the livestock wastes and agricultural activity ranged from 0.21 to 4.66mg/L and which was almost over the agricultural water quality standard(1.0mg/L). Total-P ranged from 0.001 to 0.080mg/L as lower than the agricultural water quality standard(0.1mg/L).

• Journal of The Korean Society of Agricultural Engineers
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• v.64 no.5
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• pp.17-26
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• 2022

In this study, in order to establish the criteria for evaluation of importance by the type of facility specialized for agricultural reservoirs, an expert group consisting of a total of 167 members who were in management, or specialized in the fields of design, research, and diagnosis were organized, and the importance for facilities was set with application of the AHP technique. The importance of dam body, spillway, and intake structure composing a reservoir were set at 59%, 24%, and 17%, and the importance of dam crest, upstream slope, and downstream slope constituting a dam body was set at 32%, 31%, and 37%, respectively. In addition, the importance of approach channel, regulated channel, chute channel, and stilling basin consisting a spillway was set at 15%, 44%, 26%, and 15%, and the importance of inclined conduit and outlet conduit consisting an intake structure was set at 35% and 65%, respectively. The safety grade of the reservoirs evaluated by applying the newly presented importance values in this study showed the rearrangement of the grades with a change of 11% compared to the previous grades. In this way, the newly established criteria are expected to be utilized as basic data with strategic importance in reservoir safety management and disaster prevention as well as the operation of systems in the future.

• Journal of The Korean Society of Agricultural Engineers
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• v.62 no.2
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• pp.83-95
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• 2020

The water circulation in agricultural watersheds changes with the operation of agricultural reservoirs, it is necessary to classify and evaluate them into upstream, agricultural reservoirs, irrigation districts, and downstream. Therefore, in this study, we developed the agricultural water circulation rate (AWCR) considering an agricultural reservoir and irrigation district by improving the water circulation rate of the Water environmental conservation Act. we applied it to Jinwi watershed using the module-based hydrologic analysis system to simulate the water circulation for agricultural reservoirs and irrigation areas. The model performance during the validation period was NSE of 0.762 for the downstream stream and 0.682 for the reservoir level. And the hydrograph separation model was applied to separate the direct and baseflow. As a result of this study, The AWCR of Jinwi watershed was 71.8% on average, which was higher than the water circulation rate estimated by the downstream hydrograph separation.

• Journal of The Korean Society of Agricultural Engineers
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• v.62 no.2
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• pp.111-120
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• 2020

This study assessed the reliability of the agricultural water supply based on future climate change scenarios, and suggested plans to improve the reliability in order to promote the adaptability of irrigation water in agricultural reservoirs to climate change. The assessment of agricultural water supply reliability was performed on reservoirs which had a lower water quantity than their design basis and which had recently been subject to drought. In other words, from the irrigation districts of main intake works among the reservoirs managed by the Korea Rural Community Corporation, 1~2 districts in each province-that is, a total of 13 districts -that were recently designated as a district for securing agricultural water (drought prevention district) were selected. Climate change scenarios were applied to the selected districts to analyze their future water supply reliability compared to the current level. All districts selected showed a drought frequency of 4 years or shorter, which demonstrated the need to establish climate change response plans. As plans for responding to climate change, a plan that utilizes supplemental intake works to reduce the area of the irrigation districts of main intake works, and another one that increases the capacity of main intake works were adopted to reanalyze their water supply reliability. When the area of the irrigation districts of main intake works was reduced by about 30~40%, the drought frequency dropped to more than 10 years, securing the reliability of water supply. To secure the reliability by increasing the capacity of main intake works, it was calculated that about 19,000~2,400,000 tons need to be added to each reservoir. In addition, climate change response plans were suggested to improve the reliability of the water supply in each district based on the results of economic analysis.

• Journal of Korean Society of Rural Planning
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• v.23 no.3
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• pp.163-174
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• 2017

This study developed the prototype of the system and implemented its main functions, which is the intelligent integrated agricultural water management information system and service (IaWAMISS). The developed system was designed to be able to collect, process and analyze the agricultural water information of spatially dispersed reservoirs in whole country and spatial geographic information distributed in various systems of other organizations. The system, IaWAMISS, is also possible to provide the reproduced information services in each reservoir and space units, such as agricultural water demand and supply analysis and drought prediction, to the people, experts, and policy makers. This study defined the 6 step modules to develop the system, which are to design the components of intelligent integrated information system, to derive the utilization contents of existing systems, to design the new development elements for IaWAMISS, to design the reservoir information system can be used by managers of city and county, to designate the monitoring reservoirs managed by city and county, and finally to prepare the sharing system between organizations with the existing information systems. In order to implement the prototype of the system, this study shows the results for three important functions of the system: spatial integration of reservoirs' information, data link integration between the existing systems, and intelligent analysis program development to assist decision support for agricultural water management. For the spatial integration with the reservoir water information of the Korea Rural Community Corporation, this study get IaWAMISS to receive the real-time reservoir storage information from the measurement facility installed in the municipal management reservoir. The data link integration connecting databases of the existing systems, was implemented by integrating the meteorological information of the Korea Meteorological Administration with IaWAMISS, so that the rainfall forecast data could be derived and used. For the implementation of the intelligent analysis program, this study also showed the results of analysis and prediction of agricultural water demand and supply amount, estimation of Palmer drought index, analysis of flood risk area in typhoon course region, and analysis of the storage status of reservoirs related to each storm. This study confirmed the possibility and efficiency of an useful system development through the prototype design and implementation of IaWAMISS. By solving the preliminary 6 step modules presented in this study, it is possible not only to efficiently manage water by spatial unit, but also to provide the service of information and to enhance the relevant policy and national understanding to the people.

• Journal of Korea Water Resources Association
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• v.54 no.2
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• pp.93-104
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• 2021

Due to climate change the sustainable water resources management of agricultural reservoirs, the largest number of reservoirs in Korea, has become important. However, the DIROM, rainfall-runoff model for calculating agricultural reservoir inflow, has used regression equation developed in the 1980s. This study has optimized the parameters of the DIROM using the genetic algorithm (GA) based on historical inflow data for some agricultural reservoirs that recently begun to observe inflow data. The result showed that the error between the historical inflow and simulated inflow using the optimal parameters was decreased by about 80% compared with the annual inflow with the existing parameters. The correlation coefficient and root mean square error with the historical inflow increased to 0.64 and decreased to 28.2 × 103 ㎥, respectively. As a result, if the DIROM uses the optimal parameters based on the historical inflow of agricultural reservoirs, it will be possible to calculate the long-term reservoir inflow with high accuracy. This study will contribute to future research using the historical inflow of agricultural reservoirs and improvement of the rainfall-runoff model parameters. Furthermore, the reliable long-term inflow data will support for sustainable reservoir management and agricultural water supply.