• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.4
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• pp.633-641
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• 2018

The risk of disasters, such as floods and drought, has increased. Reliable hydrological data is important for analyzing the water resource and designing hydraulic structure to manage these risks. The Yongdam Guryang river catchment located in the central of Korea is the research catchment of K-water and UNESCO IHP, and the hydrological data, such as rainfall, runoff, evapotranspiration, etc. has been observed at the catchment. The aim of this study was to assess the runoff characteristics of the small mountainous catchment of Korea based on the observed hydrological data, and the Probability Distributed Model was applied as the Rainfall-Runoff Model at the Yongdam Guryang river catchment. The hydrological data was divided into the wet period from June to September and dry period from October to May according to data analysis. The runoff ratio was 0.27~0.41 in the wet period and 0.30~0.45 in the dry period. The calibration result by the Probability Distributed Model showed a difference in the calibrated model parameters according to the periods. In addition, the model simulated the runoff accurately except for the dry period of 2015, and the result revealed the applicability of the PDM. This study showed the runoff characteristics of the small mountainous catchment by dividing the hydrological data into dry and wet periods.

• Journal of The Korean Society of Agricultural Engineers
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• v.47 no.6
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• pp.3-14
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• 2005

Accurate estimation of the spatial distribution of rainfall is critical to the successful modeling of hydrologic processes. The objective of this study is to evaluate the applicability of spatially distributed rainfall data. Spatially distributed rainfall was calculated using Kriging method and Thiessen method. The application of spatially distributed rainfall was appreciated to the runoff response from the watershed. The results showed that for each method the coefficient of determination for observed hydrograph was $0.92\~0.95$ and root mean square error was $9.78\~10.89$ CMS. Ordinary Kriging method showed more exact results than Simple Kriging, Universal Kriging and Thiessen method, based on comparison of observed and simulated hydrograph. The coefncient of determination for the observed peak flow was 0.9991 and runoff volume was 0.9982. The accuracy of rainfall-runoff prediction depends on the extent of spatial rainfall variability.

• Journal of Korea Water Resources Association
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• v.42 no.9
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• pp.703-713
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• 2009

Dam has very important roles in both water use and flood control. Dam release and runoff from rainfall affect directly to the flood control at the downstream of dam during heavy storm especially. This study evaluates the applicability of a distributed model by applying the GRM (Grid based Rainfall-runoff Model) based on HyGIS (Hydro Geographic Information System) environment to runoff modeling at the downstream of dam where the discharge from dam and rainfall affect simultaneously. In order to do this, Yeoju watershed in Han River basin is selected. Rainfall data and discharge from Chungju regulation dam and Hoengseong dam are applied to runoff simulation. The modeling results are verified with Yeoju water level station, and they show good agreement with observed hydrographs. And this study shows that GRM is able to simulate appropriately the effect of dam discharge and rainfall on watershed runoff.

• Journal of Korea Water Resources Association
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• v.42 no.3
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• pp.259-270
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• 2009

The applicability of the developed distributed rainfall runoff model using a multi-directional flow allocation algorithm and a real-time updating algorithm was evaluated. The rainfall runoff processes were simulated for the events of the Andong dam basin and the Namgang dam basin using raingauge network data and weather radar rainfall data, respectively. Model parameters of the basins were estimated using previous storm event then those parameters were applied to a current storm event. The physical propriety of the multi-directional flow allocation algorithm for flow routing was validated by presenting the result of flow grouping for the Andong dam basin. Results demonstrated that the developed model has efficiency of simulation time with maintaining accuracy by applying the multi-directional flow allocation algorithm and it can obtain more accurate results by applying the real-time updating algorithm. In this study, we demonstrated the applicability of a distributed rainfall runoff model for the advanced basin-wide flood management.

• Journal of Korea Water Resources Association
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• v.37 no.11
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• pp.969-978
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• 2004

According to the report of hydrologic modeling study, from a quantitative point of view, a lumped model is more efficient than a distributed model. A distributed model has to simplify geospatial characteristics for the shake of restricted application on computer calculation and field observation. In this reason, a distributed model can not help having some errors of water quantity modelling. However, considering a distribution of rainfall-runoff reflected spatial characteristics, a distributed model is more efficient to simulate a flow of surface water, The purpose of this study is modeling of spatial rainfall-runoff of surface water using grid based distributed model, which is consisted of storage function model and essential basin-channel parameters( slope, flow direction & accumulation), and that procedure is able to be executed at a personal computer. The prototype of this model is developed in Heongseong Multipunose Dam basin and adapted in Hapchon Multipurpose Dam basin, which is larger than the former about five times. The efficiency coefficients in result of two dam basin simulations are more than about 0.9, but ones at the upstream water level gauge station meet with bad result owing to overestimated rating curves in high water level. As a result of this study, it is easily implemented that spatially distributed rainfall-runoff model using GIS, and geophysical characteristics of the catchment, hereafter it is anticipated that this model is easily able to apply rainfall data by real time.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.6B
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• pp.613-622
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• 2006

In this study, a fully distributed physical-based rainfall-runoff model called Vflo$^{TM}$ is applied to Junglang-cheon basin for simulating runoff. Geo-spatial data are used to parameterize the model to account for the characteristics of soils, landuse/cover, and topograph. 300m resolution DEM is used to compute slope and drainage network connectivity. Spatially distributed rainfall data is interpolated by ordinary kriging method. In this study, hydrograph from HEC-HMS and Vflo$^{TM}$ without/with calibration of parameters was compared to evaluate the accuracy of rainfall-runoff model From the results, a fully distributed physical-based rainfall-runoff model reproduce the peak time and shape of hydrograph much better than HEC-HMS.

• 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 Environmental Science International
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• v.19 no.12
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• pp.1375-1384
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• 2010

The purpose of this research is to understand the change of runoff characteristics by estimated spatial rainfall. Therefore, this paper largely composed of two parts. First, we compared the simulated result according to estimation method, ID(Inverse Distance Method, ID2(Inverse Square Distance Method), and Kr(General Covariance Kriging Method), after letting miss rainfall data to the observed data. Second, we reviewed the runoff characteristics of the distributed runoff model according to the estimated spatial rainfall. On the basis of Yuseong water level station, we select the target basin as Gabchun watershed. We assumed 1 point or 2 point of the 6 rainfall gauge stations in watershed were missed. We applied the spatial rainfall distributed by Kr to Hy-GIS GRM, distributed runoff model. When 1 point rainfall data is missed, Kr is superior to others in point rainfall estimation and runoff estimation of Hy-GIS GRM. However, in case rainfall data of 2 points is missed, all of three methods did not give suitable result for them. In conclusion, Kr showed better applicability than other estimated methods if rainfall's data less than 2 points is missed.

• Journal of the Korean Association of Geographic Information Studies
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• v.9 no.3
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• pp.171-182
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• 2006

In this study, rainfall-runoff analysis was performed for Yongdam watershed($930km^2$) using KOWACO flood analysis model based on Storage Function Method as lumped hydrologic model and Vflo which was developed for real-time flood prediction by University of Oklahoma. The results shows that, the hydrographs of lumped and distributed model with uncalibrated parameters which estimated from physical or experimental relationship show significant biases from observed hydrographs. However, the hydrograph at Cheoncheon site from the distributed model follows the actual hydrograph to an extent that no more calibration is necessary. It encourages that distributed model can have advantages for application in real-time flood forecasting as physically based distributed hydrologic model which can construct event-independent basin parameter group.

• Journal of the Korean Association of Geographic Information Studies
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• v.11 no.3
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• pp.52-67
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• 2008

Recently, frequent occurrence of flash floods caused by climactic change has necessitated prompt and quantitative prediction of precipitation. In particular, the usability of rainfall radar that can carry out real-time observation and prediction of precipitation behavior has increased. Moreover, the use of distributed hydrological model that enables grid level analysis has increased for an efficient use of rainfall radar that provides grid data at 1km resolution. The use of distributed hydrologic model necessitates grid-type spatial data about target basins; to enhance reliability of flood runoff simulation, the use of visible and precise data is necessary. In this paper, physically based $Vflo^{TM}$ model and ModClark, a quasi-distributed hydrological model, were used to carry out flood runoff simulation and comparison of simulation results with data from Imjin River Basin, two-third of which is ungauged. The spatial scope of this study was divided into the whole Imjin River basin area, which includes ungauged area, and Imjin River basin area in South Korea for which relatively accurate and visible data are available. Peak flow and lag time outputs from the two simulations of each region were compared to analyze the impact of uncertainty in topographical parameters and soil parameters on flood runoff simulation and to propose effective methods for flood runoff simulation in ungauged regions.