• Journal of Wetlands Research
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• v.14 no.3
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• pp.399-411
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• 2012

Namgang Dam is located in the upstream of Nam river. Namgang Dam controls flood for the downstream of Namgang Dam using the Namgang spillway and the Sacheonman spillway with planned discharge. However, it had not been evaluated adequately that the effect of the discharge through Sacheonman spillway on the flood reduction of the downstream of Namgang Dam. This study performs runoff simulation considering the discharge from Namgang Dam and Sacheonman spillway. And modeling results are evaluated for the flood reduction effect of Sacheonman spillway on the downstream of Namgang Dam. This study uses a distributed model, GRM(Grid based Rainfall-runoff Model) for runoff analysis. As a result, Sacheonman spillway is assigned more discharge than Namgang Dam, and Sacheonman spillway greatly affects flood reduction in the downstream of Namgang Dam.

• Journal of the Korean Association of Geographic Information Studies
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• v.12 no.3
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• pp.76-87
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• 2009

Most distributed models have been developed for data interchange between model for hydrological analysis and GIS(Geographic Information System). And some interface systems between them have been developed to operate the model conveniently. This study is about developing integrated system between model and GIS not coupled system based on file interchange or interface system. In this study, HyGIS-GRM which is integrated system between GRM(Grid based Rainfall-runoff Model) which is physically based distributed rainfall-runoff model and HyGIS(Hydro Geographic Information System) have been developed. HyGIS-GRM can carry out all the processes from preparing input data to appling them to model in the same system, and this operation environment can improve the efficiency of running the model and analyzing modeling results. HyGIS-GRM can provide objective modeling environment through establishing the process of integrated operation of GIS and distributed model, and we can obtain fundamental technologies for developing integrated system between GIS and water resources model.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.5
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• pp.143-148
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• 2010

In this study, the mixed model of the surface rainfall-runoff analysis using grid data and Illudas model was applied to the urban watershed of Bulgang river. After the surface rainfall-runoff was estimated with GIS data, the runoff hydrograph was calculated using network analysis at Jeungsan bridge, which is the final output of watershed. Estimated runoff hydrograph in this study was compared to the observed runoff hydrograph which is converted from the water stage at Jeungsan bridge. The relative errors of total runoff volume and peak discharge showed the range values of 11.70%~16.30% and 1.10%~6.96%, and then the difference of peak times had the values of less than 1 hour for 4 storms. Therefore, the mixed model in this study could be considered to estimate the runoff hydrograph for the prevention of disasters in urban watershed.

• Magazine of the Korean Society of Agricultural Engineers
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• v.37 no.5
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• pp.35-42
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• 1995

his paper is to develop a GIS application model (GISCELWAB) for the spatial simulation of surface runoff from a small watershed. The model was constituted by three submodels : The input data extraction model (GISINDATA) which prepares cell-based input data automatically for a given watershed, the cell water balance model (CELWAB) which calculates the water balance for a cell and simulates surface runoff of watershed simultaneously by the interaction of cells, and the output data management model (GISOUTDISP) which visualize the results of temporal and spatial variation of surface runoff. The input data extraction model was developed to solve the time-consuming problems for the input-data preparation of distributed hydrologic model. The input data for CELWAB can be obtained by extracting ASCII data from a vector map. The output data management model was developed to convert the storage depth and discharge of cells into grid map. This model enables to visualize the spatial formulation process of watershed storage depth and surface runoff wholly with time increment.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.1D
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• pp.145-151
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• 2009

Recently, the rapid development of GIS technology has made it possible to handle a various data associated with spatially hydrological parameters with their attribute information. Therefore, there has been a shift in focus from lumped runoff models to distributed runoff models, as the latter can consider temporal and spatial variations of discharge. This research is to evaluate the feasibility of GIS based distributed model using radar rainfall which can express temporal and spatial distribution in actual dam watershed during flood runoff period. K-DRUM (K-water hydrologic & hydaulic Distributed flood RUnoff Model) which was developed to calculate flood discharge connected to radar rainfall based on long-term runoff model developed by Kyoto- University DPRI (Disaster Prevention Research Institute), and Yondam-Dam watershed ($930km^2$) was applied as study site. Distributed rainfall according to grid resolution was generated by using preprocess program of radar rainfall, from JIN radar. Also, GIS hydrological parameters were extracted from basic GIS data such as DEM, land cover and soil map, and used as input data of distributed model (K-DRUM). Results of this research can provide a base for building of real-time short-term rainfall runoff forecast system according to flash flood in near future.

• Journal of Korea Water Resources Association
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• v.53 no.12
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• pp.1173-1181
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• 2020

Recently, as local heavy rains occur frequently in a short period of time, economic and social impacts are increasing beyond the simple primary damage. In advanced meteorologically advanced countries, realistic and reliable impact forecasts are conducted by analyzing socio-economic impacts, not information transmission as simple weather forecasts. In this paper, the degree of flooding was derived using the Spatial Runoff Assessment Tool (S-RAT) and FLO-2D models to calculate the threshold rainfall that can affect human walking, and the threshold rainfall of the concept of Grid to Grid (G2G) was calculated. In addition, although it was used a lot in the medical field in the past, a quantitative accuracy analysis was performed through the ROC analysis technique, which is widely used in natural phenomena such as drought or flood and machine learning. As a result of the analysis, the results of the time period similar to that of the actual and simulated immersion were obtained, and as a result of the ROC (Receiver Operating Characteristic) curve, the adequacy of the fair stage was secured with more than 0.7.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.3
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• pp.1458-1464
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• 2011

This study is on the application of TOPMODEL-topographic based hydrologic model-to the runoff analysis, The test area was the ssang-chi watershed which is mountainous catchment located in the upstream of the sumjin-gang basin and the watershed area is $126.7km^2$. The six's hourly runoff and precipitation data was selected in the 2006 ~ 2009 year. And the model parameters are calibrated using observed runoff data by Pattern Search method. The topographic index of the ssang-chi catchment was produced by digital elevation model(DEM) of 100m grid. As a results of the analysis, the parameters of model, a decay facter(m), transmissivity(T0), and the unsaturated zone delay(TD) are sensible to hydrologic response, and the simulated runoff data are in good agreement with observed runoff data.

• Journal of Environmental Science International
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• v.28 no.2
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• pp.259-266
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• 2019

Two main sources of data, meteorological data and land surface characteristics, are essential to effectively run a distributed rainfall-runoff model. The specification and averaging of the land surface characteristics in a suitable way is crucial to obtaining accurate runoff output. Recent advances in remote sensing techniques are often being used to derive better representations of these land surface characteristics. Due to the mismatch in scale between digital land cover maps and numerical grid sizes, issues related to upscaling or downscaling occur regularly. A specific method is typically selected to average and represent the land surface characteristics. This paper examines the amount of flooding by applying the FLO-2D routing model, where vegetation heterogeneity is manipulated using the Manning's roughness coefficient. Three different upscaling methods, arithmetic, dominant, and aggregation, were tested. To investigate further, the rainfall-runoff model with FLO-2D was facilitated in Yongdam catchment and heavy rainfall events during wet season were selected. The results show aggregation method provides better results, in terms of the amount of peak flow and the relative time taken to achieve it. These rwsults suggest that the aggregation method, which is a reasonably realistic description of area-averaged vegetation nature and characteristics, is more likely to occur in reality.

• Journal of Korea Water Resources Association
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• v.48 no.11
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• pp.925-936
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• 2015

The purpose of this study is to explore the effectiveness of dual-polarization radar rainfall by comapring with the flood inundation record map through KIMSTORM(Grid-based KIneMatic wave STOrm Runoff Model). For Namgang dam ($2,293km^2$) watershed, the Bisl dual-polarization radar data for 3 typhoons (Khanun, Bolaven, Sanba) and 1 heavy rain event in 2012 were prepared. For both 28 ground rainfall data and radar rainfall data, the model was calibrated using observed discharge data at 5 stations with $R^2$, Nash and Sutcliffe Model Efficiency (ME) and Volume Conservation Index (VCI). The calibration results of $R^2$, ME and VCI were 0.85, 0.78 and 1.09 for ground rainfall and 0.85, 0.79, and 1.04 for radar rainfall respectively. The flood inundation record areas (SY and MD/SG district) by typhoon Sanba were compared with the distributed modeling results. The spatial distribution by radar rainfall produced more surface runoff from the watershed and simulated higher stream discharge than the ground rainfall condition in both SY and MD/SG district. In case of MD/SG district, the stream water level by radar rainfall near the flood inundation area showed 0.72 m higher than the water level by ground rainfall.

• Journal of Wetlands Research
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• v.14 no.2
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• pp.243-254
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• 2012

Recently, the use of radar rainfall data that can help tracking of the development and movement of rainfall's spatial distribution is drawing much attention in hydrology. The reliability of existing radar rainfall compared to gauge rainfall data on the ground has not yet been confirmed and so we have difficulties to apply the radar rainfall in hydrology. The radar rainfall for the applications in hydrology are adjusted merging method derived from gage. This study uses the Mean-Field Bias (MFB) and Statistical Objective Analysis (SOA) as correction methods to create adjusted grid-based radar rainfall data which can represent the temporal and spatial distribution of rainfall. This study used a storm event occurred in August 2010 for the adjustment of radar rainfall. In addition, the grid-based distributed rainfall-runoff model (Vflo), which enables more detailed examinations of spatial flux changes in the basin rather than the lumped hydrological models, has been applied to Gamcheon river basin which is a tributary of Nakdong River located in south-eastern part of the Korean peninsular and the basin area is $1005km^2$. The simulated runoff was compared with the observed runoff in an attempt to evaluate the usability of radar rainfall data and the reliability of the correction methods. The error range of peak discharge using each correction method was within 20 percent and the efficiency of the model was between 60 and 80 percent. In particular, the SOA method showed better results than MFB method. Therefore, the SOA method could be used for the adjustment of grid-based radar rainfall and the adjusted radar rainfall can be used as an input data of rainfall-runoff models.