• The Journal of Engineering Geology
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• v.10 no.3
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• pp.263-272
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• 2000

The main objective of this study is to simulate the rainfall-runoff relationship of the Ohwon rivet basin. For the this study, we used GIS technique and HMS(Hydrological Modeling System). In this study, watershed itself and geometric factors of watershed are extracted from DEM by using a GIS technique. The scanned data of topographical map with scale of 1:50,000 in the Ohwon river basin is used to this study and it is converted to DEM data. The parameters of Hydrological Modeling System as watershed area(A), river length, SCS Curve Number(CN) etc. are extracted by using the GIS technique in the Ohwon Basin. Extracted parameters are applied to the Hydrological Model System, then the paramenters optimized by the observed data and rainfall data. Then, the optimized parameters and Hydrological Modeling System are applied to the study area for the simulation of rainfall-runoff relationship. With the resultn of this study, GIS technique is useful to the extraction of watershed characteristics factors and Hydrological Modeling System is successful to the simulation of rainfall-runoff relationship.

• Journal of the Korean Association of Geographic Information Studies
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• v.7 no.2
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• pp.87-96
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• 2004

When watershed spatial database is constructed from DEM, hydrological geographic characteristics of watershed can be easily extracted. And the characteristics can be assigned and managed as the attribute of spatial database. In this study the scheme of constructing framework spatial database which is basic information for managing watershed information is examined. We established framework spatial data and defined the relationship of the data. And framework spatial database of test site was constructed. In this study, HyGIS(Hydrological Geographic Information System) which is developed by domestic technology for making hydrological spatial data and developing water resources system is used. Hydrological geographic characteristics and spatial data is extracted by HyGIS. And the data from HyGIS is used for constructing framework spatial database of test site. Finally, this study suggests the strategy of constructing framework spatial database for developing watershed management system based on river network.

• Journal of Korea Water Resources Association
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• v.54 no.9
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• pp.681-692
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• 2021

Vegetation processes have a significant impact on rainfall runoff processes through evapotranspiration control, but are rarely considered in the conceptual lumped hydrological model. This study evaluated the model performance of the Hapcheon Dam watershed by integrating the ecological module expressing the leaf area index data sensed remotely from the satellite into the hydrological partition module. The proposed eco-hydrological model has three main features to better represent the eco-hydrological process in humid regions. 1) The growth rate of vegetation is constrained by water shortage stress in the watershed. 2) The maximum growth of vegetation is limited by the energy of the watershed climate. 3) The interaction of vegetation and aquifers is reflected. The proposed model simultaneously simulates hydrologic components and vegetation dynamics of watershed scale. The following findings were found from the validation results using the model parameters estimated by the SCEM algorithm. 1) Estimating the parameters of the eco-hydrological model using the leaf area index and streamflow data can predict the streamflow with similar accuracy and robustness to the hydrological model without the ecological module. 2) Using the remotely sensed leaf area index without filtering as input data is not helpful in estimating streamflow. 3) The integrated eco-hydrological model can provide an excellent estimate of the seasonal variability of the leaf area index.

• Journal of the Korean Association of Geographic Information Studies
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• v.9 no.2
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• pp.144-159
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• 2006

Hydrological models are tools intended to realistically represent the basin's complex system in which hydrological characteristics result from a number of physical, vegetative, climatic, and anthropomorphic factors. Spatially distributed hydrological models were first developed in the 1960s, Remote sensing(RS) data and Geographical Information System(GIS) play a rapidly increasing role in the field of hydrology and water resources development. Although very few remotely sensed data can applied in hydrology, such information is of great. One of the greatest advantage of using RS data for hydrological modeling and monitoring is its ability to generate information in spatial and temporal domain, which is very crucial for successful model analysis, prediction and validation. In this paper, SLURP model is selected as semi-distributed hydrological model and MODIS Leaf Area Index(LAI), Normalized Difference Vegetation Index(NDVI) as Remote sensing input data to hydrological modeling of Kyung An-chen basin. The outlet of the Kyung An stage site was simulated, We evaluated two RS data, based on ability of SLURP model to simulate daily streamflows, and How the two RS data influence the sensitivity of simulated Evapotranspiration.

• Journal of Korean Society on Water Environment
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• v.27 no.6
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• pp.794-803
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• 2011

Self Organizing Map (SOM) was applied for pattern classification of hydrological and water quality data measured at Jangseong Reservoir on a monthly basis. The primary objective of the present study is to understand better data characteristics and relationship between the data. For the purpose, two SOMs were configured by a methodologically systematic approach with appropriate methods for data transformation, determination of map size and side lengths of the map. The SOMs constructed at the respective measurement stations for water quality data (JSD1 and JSD2) commonly classified the respective datasets into five clusters by Davies-Bouldin Index (DBI). The trained SOMs were fine-tuned by Ward's method of a hierarchical cluster analysis. On the one hand, the patterns with high values of standardized reference vectors for hydrological variables revealed the high possibility of eutrophication by TN or TP in the reservoir, in general. On the other hand, the clusters with low values of standardized reference vectors for hydrological variables showed the patterns with high COD concentration. In particular, Clsuter1 at JSD1 and Cluster5 at JSD2 represented the worst condition of water quality with high reference vectors for rainfall and storage in the reservoir. Consequently, SOM is applicable to identify the patterns of potential eutrophication in reservoirs according to the better understanding of data characteristics and their relationship.

• Water Engineering Research
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• v.6 no.4
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• pp.179-187
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• 2005

This paper introduces the Cheonggye-cheon restoration project. The restoration project aims to revive the 600-year-old city of Seoul by recovering the historical heritage, guaranteeing safety from the deteriorated covering structures, creating the environment-friendly space, and revitalizing the neglected city centers. In order to understand the current hydrological cycle of the Chenggye-cheon watershed, the annual water balance of the region was calculated using the observed data including precipitation, runoff, water supply and sewage, and the changes in the groundwater level. The $2001{\sim}2002$ data were used to calibrate the WEP, and the $2003{\sim}2004$ data were used to verify the WEP. The calibration and validation results for the flood hydrograph how a reasonable value (at Majanggyo station, the R2 for the calibration period was 0.9, and that for the validation period was 0.7). According to the annual water balance of the Cheonggye-cheon watershed for 2004, the amount of surface runoff, infiltration, and evapotranspiration was 1,097mm, 216mm and 382mm, respectively, for an annual precipitation of 1,499mm. The application results from WEP, a distributed hydrological model, provide more detailed information of the watershed, and the model will be useful for improving the hydrological cycle in urban watershed.

• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.2
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• pp.15-26
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• 2015

The purpose of this paper is to develop a software tool, PGA-CC (Projection of hydrology via Grid-based Assessment for Climate Change) to evaluate the present hydrologic cycle and the future watershed hydrology by climate change. PGA-CC is composed of grid-based input data pre-processing module, hydrologic cycle calculation module, output analysis module, and output data post-processing module. The grid-based hydrological model was coded by Fortran and compiled using Compaq Fortran 6.6c, and the Graphic User Interface was developed by using Visual C#. Other most elements viz. Table and Graph, and GIS functions were implemented by MapWindow. The applicability of PGA-CC was tested by assessing the future hydrology of South Korea by HadCM3 SRES B1 and A2 climate change scenarios. For the whole country, the tool successfully assessed the future hydrological components including input data and evapotranspiration, soil moisture, surface runoff, lateral flow, base flow etc. From the spatial outputs, we could understand the hydrological changes both seasonally and regionally.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.4-4
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• 2020

Three wildfires severely damaged local towns and forests in Gangwon-do, South Korea in 2019 April 4-5. Local hydrological regime could be greatly altered by the wildfires, therefore it is important to assess its damage (e.g. area and severity) and also resultant changes in hydrological fluxes. We retrieved the Normalized-Burned Ratio (NBR) index using remote-sensing data (Moderate Resolution Imaging Spectroradiometer (MODIS) 500-m 8-day surface reflectance data), and delineated the damaged-area based on the difference in the NBR (dNBR) before and after the wildfires. We then estimated changes in the annual evapotranspiration (AET) in 2019 using the MODIS evapotranspiration data (500-m 8-day). It was found that the damaged-area of the three wildfires was 29.50 km^2 in total, which take up 1.00-6.19% area of five catchments. It was estimated that the AET would be decreased as 0.05-1.56% over those five catchments, as compared to the pre-fire AET (2004-2018). The impact of the wildfires on the catchment AET was less severe than expected (i.e. up to 1.56%) mostly because two big wildfires were distributed across two catchments respectively (i.e. four catchments for the two wildfires) and the other wildfire was small and not severe. This study highlights the importance of assessing the area and severity of a wildfire when estimating its impact on the local hydrological cycle.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.179-179
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• 2015

Citarum River is one of the important river in West Java, Indonesia. During the rainy season, flood happens almost every year in Upper Citarum Watershed, hence, it is necessary to establish the countermeasure in order to prevent and mitigate flood damages. Since the lack of hydrological data for the modelling is common problem in this area, it is difficult to prepare the countermeasures. Therefore, we used Rainfall-Runoff-Inundation (RRI) Model developed by Sayama et al. (2010) as the hydrological and inundation modelling for evaluating the inundation case happened in Upper Citarum Watershed, West Java, Indonesia and the satellite based information such as rainfall (GSMaP), landuse and so on instead of the limited hydrological data. In addition, 3 arc-second HydroSHEDS Digital Elevation Model (DEM) is used. To verify the model, the observed data of Nanjung water stage gauging station and the daily observation data are used. Simulated inundation areas are compared with the flood extent figure from Upper Citarum Basin Flood Management Project (UCBFM).

• Journal of Korea Water Resources Association
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• v.54 no.11
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• pp.891-901
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• 2021

In this study, a hydrological cycle soundness evaluation method was developed using monthly meteorological observation data. The Gyeongan stream watershed was divided into five sub-basins and eight criteria were established for hydrological cycle evaluation: the number of non-rainfall day, the number of non-rainfall day fluctuation, over 30 mm per day, over 30 mm per day fluctuation, average river level, average river level fluctuation, average groundwater level and average groundwater level fluctuation. Observation data were normalized and weights for evaluation by each sub-basin were calculated using the entropy method. The hydrological cycle soundness evaluation indices were calculated using TOPSIS applying the calculated weight value. As a result of the study, it was found that the hydrological cycle soundness was unstable in the Gyeongan-upstream from November to January, the Gyeongan-suwipyo from February to April, Gonjiam stream from April to May, and the Gyeongan-downstream from November to February. In this study, the developed technique is expected to serve as a quantitative basis for policy decision to recover hydrological cycle soundness.