• 한국농공학회논문집
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• 제60권5호
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• pp.41-54
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• 2018

A method to account a detention in a rice paddy field in hydrologic modeling was tested at plot and watershed scales. Hydrologic Simulation Program - Fortran (HSPF) and its one of surface runoff modeling method, i.e Surface-Ftable, were used to simulate a inundated condition in a rice paddy culture for a study plot and basins in Saemangeum watershed. Surface-Ftable in HSPF defines surface runoff ratio with respect to surface water depth in a pervious land segment, which can be implemented to the feature of water management in a rice paddy field. A Surface-Ftable for paddy fields in Saemangeum watershed was developed based on the study paddy field monitoring data from 2013 to 2014, and was applied to Jeonju-chun and Jeongeup-chun basins which comprise 12% and 22% of paddy fields in the basins, respectively. Four gaging stations were used to calibrate and validate the watershed models for the period of 2009 and 2013. Model performed 7.13% and 9.68% in PBIAS, and 0.94 and 0.90 in monthly NSE during model calibrations at Jeonju and Jeongeup stations, respectively, while the models were validated its applicability at Hyoja and Gongpyung stations. The comparison of results with and without considering detention effect of paddy fields confirmed the validity of the Surface-Ftable method in modeling watersheds containing rice paddy fields.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2023년도 학술발표회
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• pp.287-287
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• 2023

Surface water-groundwater interaction (SWGI) is an important hydrological process that influences both the quantity and quality of water resources. However, regional scale SWGI model calibration and uncertainty analysis have been a challenge because integrated models inherently carry a vast number of parameters, modeling assumptions, and inputs, potentially leaving little time and budget to explore questions related to model performance and forecasting. In this study, we have proposed the application of iterative ensemble smoother (IES) for uncertainty analysis and calibration of the widely used integrated surface-subsurface model, SWAT-MODFLOW. SWAT-MODFLOW integrates Soil and Water Assessment Tool (SWAT) and a three-dimensional finite difference model (MODFLOW). The model was calibrated using a parameter estimation tool (PEST). The major advantage of the employed IES is that the number of model runs required for the calibration of an ensemble is independent of the number of adjustable parameters. The pilot point approach was followed to calibrate the aquifer parameters, namely hydraulic conductivity, specific storage, and specific yield. The parameter estimation process for the SWAT model focused primarily on surface-related parameters. The uncertainties both in the streamflow and groundwater level were assessed. The work presented provides valuable insights for future endeavors in coupled surface-subsurface modeling, data collection, model development, and informed decision-making.

• 상하수도학회지
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• 제20권4호
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• pp.585-594
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• 2006

This study focused on the causes of fish kills and its prevention methods in Yudeung Stream, Daejeon, Korea. Intense field data, continuous water quality monitoring system and water quality modeling were applied to analyze the causes. Pollutant can be delivered to urban streams by surface runoff and combined sewer overflows in rainfall events. However, water quality analysis and water quality modeling results indicate that the abrupt fish kills in the Yudeung stream seems to be caused by combined effect of DO depletion, increase in turbidity and other toxic material. Excessive fish population in the study area may harm the aesthetic value of the stream and also has greater potential for massive fish kills. It is suggested to implement methods to reduce delivery of pollutants to the stream not only to prevent fish kills but also to keep balance of ecosystem including human uses. Frequent clean up of the urban surface and CSO, installation of detention basin will be helpful. In the long run, it seems combined sewer system has be replaced with separate sewer system for more effective pollutant removal in the urban area.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.839-846
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• 2004

The objective of this study is the evaluation of the tunneling effect on the groundwater-surface water interaction. The designed tunnel line is laid beneath the Gapo-cheon, which runs throughout study area. And, the pre-evaluation of the tunnel-influence on the Gapo-cheon is urgently needed. However, it is very difficult to find out the similar domestic and/or foreign cases. In this study, we would exclude the numerical modeling technique with insufficient data. Instead of the evaluation of the tunneling effect on the groundwater-surface water interaction with the numerical modeling, we monitored the flow rate of surface water at various point. We measured the flow rate of surface water at 5 points. With the results of surface flow, we can conclude that 39% of flow rate in Gapo-cheon is contributed by the groundwater discharge, as baseflow.

• 한국물환경학회지
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• 제36권6호
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• pp.592-610
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• 2020

In South Korea, the concept of water environment was expanded to include aquatic ecosystems with the Integrated Water Management implementation. Watershed-scale modeling is typically performed for hydrologic component analysis, however, there is a need to expand to include ecosystem variability such that the modeling corresponds to the social and political issues around the water environment. For this to be viable, the modeling must account for several distinct features in South Korean watersheds. The modeling must provide reasonable estimations for peak flow rate and apply to paddy areas as they represent 11% of land use area and greatly influence groundwater levels during irrigation. These facts indicate that the modeling time intervals should be sub-daily and the hydrologic model must have sufficient power to process surface flow, subsurface flow, and baseflow. Thus, the features required for watershed-scale modeling are suggested in this study by way of review of frequently used hydrologic models including: Agricultural Policy/Environmental eXtender(APEX), Catchment hydrologic cycle analysis tool(CAT), Hydrological Simulation Program-FORTRAN(HSPF), Spatio-Temporal River-basin Ecohydrology Analysis Model(STREAM), and Soil and Water Assessment Tool(SWAT).

• 한국물환경학회지
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• 제32권3호
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• pp.243-252
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• 2016

In cases of water pollution accidents, accurate prediction for arrival time and concentration of contaminants in a river is essential to take proper measures and minimize their impact on downstream water intake facilities. It is critical to fully understand the behavior characteristics of contaminants on river surface, especially in case of oil spill accidents. Therefore, in this study, the effects of main parameters of advection and diffusion of contaminants were analyzed and validated by comparing the results of Lagrangian particle tracking (LPT) simulation of Environmental Fluid Dynamic Code (EFDC) model with those of Global Position System (GPS)-equipped drifter experiment. Prevention scenario modeling was accomplished by taking cases of movable weir operation into account. The simulated water level and flow velocity fluctuations agreed well with observations. There was no significant difference in the speed of surface particle movement between 5 and 10 layer modeling. Therefore, 5 layer modeling could be chosen to reduce computational time. It was found that full three dimensional modeling simulated wind effects on surface particle movements more sensitively than depth-averaged two dimensional modeling. The diffusion range of particles was linearly proportional to horizontal diffusivity by sensitivity analysis. Horizontal diffusivity estimated from the results of GPS-equipped drifter experiment was 0.096 m²/sec, which was considered to be valid for applying the LPT module in this area. Finally, the scenario analysis results showed that particle movements could be stagnant when discharge from the upstream weir was reduced, implying the possibility of securing time for mitigation actions such as oil boom installation and wiping oil contaminants. The outcomes of this study can help improve the prediction accuracy of particle tracking simulation to establish the most suitable mitigation plan considering the combination of movable weir operation.

• 지질공학
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• 제27권3호
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• pp.313-322
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• 2017

본 연구의 목적은 지표수-지하수 통합 모델을 통해 모델 영역과 시설농업단지(밀양들)의 지표수/지하수 유동을 모의하고 모델 영역의 물수지 분석을 통해 지하수 함양량을 산정하는 것이다. 지표수 유동 모델 결과에서는 밀양강 상류(북동쪽)에서 하류(남동쪽)로 약 1~5 m의 수심으로 지표수가 유동하고 있으며, 모델지역 상류의 M01 지점에서는 지표수 유량 관측값과 모델값이 일치하고, 모델지역 하류의 M02 지점에서의 지표수 유량은 1% 정도의 차이를 보인다. 지하수 유동 모델에서는 지하수 심도가 하천에서는 표고와 유사하며 산림 지역으로 갈수록 높아지고, 지하수 양수를 고려한 지하수 심도는 모델값이 관측값보다 1.5 m이내의 범위로 높게 나타난다. 지표수-지하수 통합모델에서는 지하수의 함양 면적이 모델 면적의 90% 정도이고, 지하수 함양량은 $1.92{\times}10^5m^3/day$인 것으로 나타난다. 연평균 물수지 분석에서는 단위 면적당 지하수 함양량이 503.9 mm/year로서 연평균 강우량의 39% 정도로 추정된다.

• 한국물환경학회지
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• 제36권6호
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• pp.636-650
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• 2020

A modeling system that can consider the overall water environment and be used to integrate hydrology, water quality, and aquatic ecosystem on a watershed scale is essential to support decision-making in integrated water resources management (IWRM). In adapting imported models for evaluating the unique water environment in Korea, a platform perspective is becoming increasingly important. In this study, a modeling platform is defined as an ecosystem that continuously grows and provides sustainable values through voluntary participation- and interaction-of all stakeholders- not only experts related to model development, but also model users and decision-makers. We assessed the conceptual values provided by the IWRM modeling platform in terms of openness, transparency, scalability, and sustainability. I We also reviewed the technical aspects of functional and spatial integrations in terms of socio-economic factors and user-centered multi-scale climate-forecast information. Based on those conceptual and technical aspects, we evaluated potential modeling platforms such as Source, FREEWAT, Object Modeling System (OMS), OpenMI, Community Surface-Dynamics Modeling System (CSDMS), and HydroShare. Among them, CSDMS most closely approached the values suggested in model development and offered a basic standard for easy integration of existing models using different program languages. HydroShare showed potential for sharing modeling results with the transparency expected by model user-s. Therefore, we believe that can be used as a reference in development of a modeling platform appropriate for managing the unique integrated water environment in Korea.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2006년도 학술발표회 논문집
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• pp.2-11
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• 2006

In the processes of hydrological cycle, when precipitation reaches the ground surface, water may become surface runoff or infiltrate into soil and then possibly further percolate into groundwater aquifer. A part of the water is returned to the atmosphere through evaporation and transpiration. Soil moisture dynamics driven climate fluctuations plays a key role in the simulation of water transfer among ground surface, unsaturated zone and aquifer. In this study, a one-layer canopy and a four-layer soil representation is used for a coupled soil-vegetation modeling scheme. A non-zero hydraulic diffusivity between the deepest soil layer modeled and groundwater table is used to couple the numerical equations of soil moisture and groundwater dynamics. Simulation of runoff generation is based on the mechanism of both infiltration excess overland flow and saturation overland flow nested in a numerical model of soil moisture dynamics. Thus, a comprehensive hydrological model integrating canopy, soil zone and aquifer has been developed to evaluate water resources in the plain region of Huaihe River basin in East China and simulate water transfer among precipitation, surface water, soil moisture and groundwater. The newly developed model is capable of calculating hydrological components of surface runoff, evapotranpiration from soil and aquifer, and groundwater recharge from precipitation and discharge into rivers. Regional parameterization is made by using two approaches. One is to determine most parameters representing specific physical values on the basis of characterization of soil properties in unsaturated zone and aquifer, and vegetations. The other is to calibrate the remaining few parameters on the basis of comparison between measured and simulated streamflow and groundwater tables. The integrated modeling system was successfully used in the Linhuanji catchment of Huaihe plain region. Study results demonstrate that (1) on the average 14.2% of precipitation becomes surface runoff and baseflow during a ten-year period from 1986 to 1995 and this figure fluctuates between only 3.0% in drought years of 1986, 1988, 1993 and 1994 to 24.0% in wet year of 1991; (2) groundwater directly deriving from precipitation recharge is about 15.0% t of the precipitation amount, and (3) about half of the groundwater recharge flows into rivers and loses through evaporation.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2001년도 학술발표회 발표논문집
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• pp.412-416
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• 2001

Among water quality models, WASP5 was applied to Boryeong freshwater lake, as a part of Water Quality Management System. The WASP modeling system is a generalized modeling framework for contaminant fate and transport in surface waters. The simulated result was compaired with actual measurement. So, before and after making freshwater lake were compaired. After this research, the lake may have eutrophication and water quality would be worse after making the lake as freshwater lake. Therefore, to make the freshwater lake better, more appropriate plan is necessary.