• Journal of Korea Water Resources Association
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• v.43 no.3
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• pp.295-308
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• 2010

As an attempt to explore the impact of droughts which may be worse by the climate change, the change in the water balance of the Han-river basin is analyzed. To accomplish it, we suggest a procedure consisting of three successive sub-procedures: daily rainfall generation for 70 years by the RegCM3 RCM ($27{\times}27\;km$) with the A2 scenario, daily discharge simulations by SLURP using the generated daily rainfall data, and monthly water balance analysis by K-WEAP (Korean Water Evaluation and Planning System) based on the SLURP simulation. Since significant uncertainty is involved in forecasting the future water consumption and water yields, we assumed three water consumption scenarios and fifty water yields scenarios. Three water consumption scenarios are, namely, "LOW", "MEDIUM", and "HIGH" according to the expected amount of water consumption. The fifty daily discharges are obtained from the SLURP simulations during the drought period. Finally, water balance analysis is performed by K-WEAP based on 150 combinations from three water consumption scenarios and the fifty daily discharges. Analysis of water scarcity in small basins of the Han River basin showed concentration of water scarcity in some small basins. It was also found that water scarcity would increase in all small basins of the Han River basin.

• Journal of Korean Society of Rural Planning
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• v.9 no.4 s.21
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• pp.1-7
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• 2003

This study was conducted to seek the effective water management method of the irrigation reservoirs. Joongpyong reservoir was selected for the hydrologic monitoring, and investigated from May in 1999 to December in 2001. The water level and amount of outlet discharge were measured, the stage discharge equation as a rating curve was induced, and which were compared to the irrigation water requirements calculated by a daily simulation model. The water balance of Joongpyong reservoir was analyzed, mainly on the reservoir storage ratio during irrigation period. Comparing the observed storage and simulation data, the results of the simulation were well agreed with the measured data.

• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.4
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• pp.65-71
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• 2012

The objective of this study was to estimate surface runoff from rice paddy plots using an artificial neural network (ANN). A field experiment with three treatment levels was conducted in the NICS saemangum experimental field located in Iksan, Korea. The ANN model with the optimal network architectures, named Paddy1901 with 19 input nodes, 1 hidden layer with 16 neurons nodes, and 1 output node, was adopted to predict surface runoff from the plots. The model consisted of 7 parameters of precipitation, irrigation rate, ponding depth, average temperature, relative humidity, wind speed, and solar radiation on the daily basis. Daily runoff, as the target simulation value, was computed using a water balance equation. The field data collected in 2011 were used for training and validation of the model. The model was trained based on the error back propagation algorithm with sigmoid activation function. Simulation results for the independent training and testing data series showed that the model can perform well in simulating surface runoff from the study plots. The developed model has a main advantage that there is no requirement for any prior assumptions regarding the processes involved. ANN model thus can be a good tool to predict surface runoff from rice paddy fields.

• Journal of Korea Water Resources Association
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• v.40 no.2 s.175
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• pp.147-158
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• 2007

This study attempted to determine a suitable hydrologic model for assessing the impact of climate change on water resources, and to assess the accuracy of streamflow scenarios simulated by the selected hydrologic model using the meteorological scenarios of the Seoul National University Regional Climate Model(SNURCM). Comparison of four water balance models and two daily conceptual rainfall-runoff models for the simulation capability of the Daecheong Dam inflow indicated that the abcd model performs the best among the tested water balance models and performs as well as SSARR that is popular as a daily rainfall-runoff model in Korea. Parameters of the abcd model were then estimated for 12 ungauged subbasins of the Geum River by the regionalization method. The model parameters were first calibrated at nine multi-purpose dams and were then regionalized using catchment characteristics for another four multi-purpose dams, which were assumed to be ungauged sites. The model efficiency(ME) coefficients of the simulated inflows for these four dams were at least 87%. The MEs of the hindcasted meteorological rainfall scenarios of the 12 subbasins of the Geum River were more than 60%. Moreover, the ME of the Daecheong Dam inflow simulated by the abcd model using the SNURCM rainfall scenarios was more than 80%. Therefore, this research concluded that the abcd model coupled with the SNU-RCM meteorological scenarios can be used for impact assessment studies of climate change on water resources.

• Journal of Korea Water Resources Association
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• v.36 no.6
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• pp.901-910
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• 2003

The hydrologic behavior of paddy field depends largely on the irrigation and levee height management by farmers. The storage and drainage amount of paddy for storm events certainly influences the stream discharge. To understand the paddy storage effect during storm periods, a daily paddy water balance model embedding farmer's water management was developed by using 4 years (1996, 1997, 2001, 2002) field experimental data at 2 locations (Suwon and Yeoju) From the modeling, it was possible to simulate the daily ponding depth of paddy by treating paddy levee height and threshold pending depth indicating irrigation time as 10 days average parameters of the model. The storage amount(306.9 mm to 343.6 mm) showed little deviation to rainfall amount(425.1 mm to 850.8 mm).

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.74-83
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• 2007

The goal of this study is to establish an integrated watershed hydrologic model for the whole Nakdong River basin whose area is an approximately 24,000 km2. Including a number of watershed elements such as rainfall, runoff, water use, and so on, the proposed model is based on SWAT model, and is used to improve the flow duration curve estimation of ungauged watersheds for Korean Total Maximum Daily Load (TMDL). The model is also used to recognize quantitatively the river flow variation due to water use elements and large dam effluents in the whole watershed. The established combined watershed hydrologic model, SWAT-Nakdong, is used to evaluate the quantified influences of artificial water balance elements, such as a dam and water use in the watershed. We apply two water balance scenarios in this study: the dam scenario considering effluent conditions of 4 large multi-purpose dams, Andong dam, Imha dam, Namgang dam, and Habcheon dam, and the water use scenario considering a water use for stream line and the effluent from a treatment plant. The two scenarios are used to investigate the impacts on TMDL design flow and flow duration of particular locations in Nakdong River main stream. The results from this study will provide the basic guideline for the natural flow restoration in Nakdong River.

• Journal of Korean Society of Rural Planning
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• v.8 no.1 s.15
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• pp.60-68
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• 2002

A Modified CREAMS model, CREAMS-PADDY was developed to simulate the hydrology and nutrient transport at an irrigated rice paddy. The hydrology at a paddy was simulated by a daily water balance routine which reflects daily inflow, outflow, and water level changes. The soil erosion was simulated using modified USLE. The nutrient transport for total nitrogen and phosphorus were depicted for various phases of each constitute such as extraction, percolation, mineralization, and plant uptakes. Field monitoring was conducted to investigate the water quality changes at a paddy field at three times a week during the growing season of 1996. The proposed model simulates the water quality of the paddy reasonably well, and is found to be applicable to field conditions.

• Magazine of the Korean Society of Agricultural Engineers
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• v.42
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• pp.1-8
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• 2000

To examine the irrigation water uses in Sunjin river basin, existing status and operation records of headworks facilities including reservoirs, pumping stations, tube wells, and diversion dams were surveyed and analyzed for the period of 1994∼1998. Daily irrigation demand and water use were estimated for the irrigated paddy field using penman equation, Thank model, reservoir water balance model and daily pumping rate of pumping stations. Irrigation water use from multi-purpose dams in the basin was not included in this study.

• Magazine of the Korean Society of Agricultural Engineers
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• v.43 no.2
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• pp.78-84
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• 2001

The daily streamflow in the Yaluhe watershed located in the north-eastern part of China was simulated by DAWAST model and the water balance parameters of the model were calibrated by simplex method. Model verification tests were carried out. The range of root mean square error was 0.34∼1.50mm, that of percent error in volume was -16.9∼-62.0% and that of correlation coefficient was 0.727∼0.920. DAWAST model was revised to consider the phreatic evaporation from the ground water in the frozen soil by adjusting soil moisture content in the unsaturated layer at the end of the melting season. The results of estimation of the daily streamflow by the revised model were statistically improved, that is, the range of root mean square error was 0.31∼1.49mm, that of percent error in volume was -11.7∼-12.1%, and that of correlation coefficient was 0.810∼0.932. The accuracy of DAWAST model was improved and the applicability of DAWAST model was expanded to the frozen region.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2003.10a
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• pp.499-502
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• 2003

Using the daily water balance model of the Keum River Barrage Dam, water supply capacity was analyzed. The scenario of reservoir inflow was selected to case with Daechung dam, case with no dam, case with Yongdam dams. Runoffs in 12 sub watersheds were simulated by the DAWAST model considered return flows.