• Journal of Wetlands Research
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• v.12 no.1
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• pp.51-61
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• 2010

Changes in climate have largely increased concentrated heavy rainfall, which in turn is causing enormous damages to humans and properties. Therefore, it is important to understand the spatial-temporal features of rainfall. In this study, RADAR rainfall was used to calculate gridded areal rainfall which reflects the spatial-temporal variability. In addition, Kalman-filter method, a stochastical technique, was used to combine ground rainfall network with RADAR rainfall network to calculate areal rainfall. Thiessen polygon method, Inverse distance weighting method, and Kriging method were used for calculating areal rainfall, and the calculated data was compared with adjusted areal RADAR rainfall measured using the Kalman-filter method. The result showed that RADAR rainfall adjusted with Kalman-filter method well-reproduced the distribution of raw RADAR rainfall which has a similar spatial distribution as the actual rainfall distribution. The adjusted RADAR rainfall also showed a similar rainfall volume as the volume shown in rain gauge data. Anseong-Cheon basin was used as a study area and the RADAR rainfall adjusted with Kalman-filter method was applied in $Vflo^{TM}$ model, a physical-based distributed model, and ModClark model, a semi-distributed model. As a result, $Vflo^{TM}$ model simulated peak time and peak value similar to that of observed hydrograph. ModClark model showed good results for total runoff volume. However, for verifying the parameter, $Vflo^{TM}$ model showed better reproduction of observed hydrograph than ModClark model. These results confirmed that flood runoff simulation is applicable in domestic settings(in South Korea) if highly accurate areal rainfall is calculated by combining gauge rainfall and RADAR rainfall data and the simulation is performed in link to the distributed hydrological model.

• Journal of Wetlands Research
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• v.14 no.3
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• pp.385-397
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• 2012

A grid based physically distributed model analyzes rainfall-runoff using physical parameters and grid-typed spatial and hydrological data. This study have developed a real time runoff modelling system using GRM RT(Grid based Rainfall-runoff Model Real Time) which is a real time flow analysis module in GRM, a grid based physically distributed rainfall-runoff model. Weather radar data received in real time are calibrated by using real time AWS from Korea Meteorological Administration(KMA), and they are applied to real time runoff modeling. And the runoff model is calibrated by using observed discharges from a water level gauge in real time. This study have designed and implemented the databases necessary to construct the real time runoff modelling system, and established the process of a real time runoff modelling. And the performances of the developed system have been evaluated. The system have been applied to Nerinheon watershed located in the upstream of Soyanggang Dam and the application results are evaluated.

• Proceedings of the Korean Society of Disaster Information Conference
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• 2016.11a
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• pp.226-228
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• 2016

유출해석을 하기 위한 수문 모형은 크게 분포형 모형과 집중형 모형으로 구분할 수 있다. $Vflo^{TM}$와 같은 분포형 모형은 격자 기반의 유역 특성 및 강우자료로부터 초기 매개변수 값을 추정하기 때문에 모형보정시 민감하게 반응할 수 있다. 따라서 모형 내 구성된 매개변수들의 특성과 민감도를 파악하여 유출해석을 하는 것이 중요하다. 본 연구에서는 물리적 기반의 완전분포 모형인 $Vflo^{TM}$모형을 이용하여 감천유역의 유출해석을 실시하였다. 그 후, 지표면 유출과 하도 추적에서 주요 매개변수가 미치는 영향을 분석하여 매개변수별 민감도를 평가하였다. 이 결과, 수리전도도는 유역전체 유출고에 관여하였고, 불투수율은 첨두유량에 영향을 미치는 것으로 나타났다. 본 연구결과를 통해 유출고 및 유출량에 영향을 미치는 매개변수와 이에 따른 민감도를 확인할 수 있었다.

• Journal of Korea Water Resources Association
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• v.48 no.11
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• pp.937-944
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• 2015

This study proposed a novel technique, namely the Radar Polygon Method (RPM), for areal rainfall estimation based on radar precipitation data. The RPM algorithm has the following steps: 1. Determine a map of the similar rainfall occurrence of which each grid cell contains the binary information on whether the grid cell rainfall is similar to that of the observation gage; 2. Determine the similar rainfall probability map for each gage of which each grid cell contains the probability of having the rainfall similar to that of the observation gage; 3. Determine the governing territory of each gage by comparing the probability maps of the gages. RPM method was applied to the Anseong stream basin. Radar Polygons and Thiessen Polygons of the study area were similar to each other with the difference between the two being greater for the rain gage highly influenced by the orography. However, the weight factor between the two were similar with each other. The significance of this study is to pioneer a new application field of radar rainfall data that has been limited due to short observation period and low accuracy.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.197-201
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• 2018

인공위성 기반의 원격탐사자료는 홍수, 가뭄 등 자연재해에 대한 모니터링 및 예측에 활용되어 왔으며, 특히 인공위성을 이용한 광역적 강수량 추정 자료는 지형적 제약을 받는 지상관측자료와 비교하여 시공간적으로 연속적이고 균질한 강수량 자료 취득이 가능하다는 장점이 있다. 우리나라의 경우 상대적으로 조밀한 지상관측망이 구축되어 있어 공간적으로 상세한 강수량 정보를 생산할 수 있는 여건을 갖추고 있지만, 북한 지역의 경우 기상, 수문, 통계자료에 관한 자료의 접근 및 품질의 제한성으로 인해 미계측 지역에 대한 강수량의 추정에 한계가 있다. CHIRPS (Climate Hazards Group InfraRed Precipitation with Stations) 데이터는 1999년부터 미국국제개발처 (U.S. Agency for International Development, USAID), 미국항공우주국 (National Aeronautics and Space Administration, NASA), 미국해양대기청 (National Oceanic and Atmospheric Administration, NOAA)의 지원으로 개발된 전지구 강우데이터 자료이다. CHIRPS는 1981년부터 현재까지 전지구 강우자료를 0.05도 격자 해상도로 제공하고 있으며, 강수량의 추세 분석 및 가뭄 모니터링을 위해 활용되고 있다. 본 연구에서는 CHG (Climate Hazards Group)에서 제공하고 있는 인공위성을 이용한 광역적 강수량 추정 자료인 CHIRPS와 남한 및 북한의 지상관측 강수량 자료와의 비교를 통해 위성으로부터 유도된 격자 강수량자료의 정확도 및 지역적인 강수추정의 불확실성을 평가하고, 수자원 및 재해 분야 이용 가능성을 검토하고자 한다.

• Journal of Korea Water Resources Association
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• v.52 no.11
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• pp.887-894
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• 2019

We proposed a GPU (Grapic Processing Unit) accelerated kinematic wave model for rainfall runoff simulation and tested the accuracy and speed up performance of the proposed model. The governing equations are the kinematic wave equation for surface flow and the Green-Ampt model for infiltration. The kinematic wave equations were discretized using a finite volume method and CUDA fortran was used to implement the rainfall runoff model. Several numerical tests were conducted. The computed results of the GPU accelerated kinematic wave model were compared with several measured and other numerical results and reasonable agreements were observed from the comparisons. The speed up performance of the GPU accelerated model increased as the number of grids increased, achieving a maximum speed up of approximately 450 times compared to a CPU (Central Processing Unit) version, at least for the tested computing resources.

• Journal of Korean Society on Water Environment
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• v.27 no.5
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• pp.587-596
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• 2011

The interest in hydrological modeling has increased significantly recently due to the necessity of watershed management, specifically in regards to lumped models, which are being prosperously utilized because of their relatively uncomplicated algorithms which require less simulation time. However, lumped models require empirical coefficients for hydrological analyses, which do not take into consideration the heterogeneity of site-specific characteristics. To overcome such obstacles, a distributed model was offered as an alternative and the number of researches related to watershed management and distributed models has been steadily increasing in the recent years. Thus, in this study, the feasibility of a grid-based rainfall-runoff model was reviewed using the flood runoff process in the Han River basin, including the ChungjuDam, HoengseongDam and SoyangDam watersheds. Hydrological parameters based on GIS/RS were extracted from basic GIS data such as DEM, land cover, soil map and rainfall depth. The accuracy of the runoff analysis for the model application was evaluated using EFF, NRMSE and QER. The calculation results showed that there was a good agreement with the observed data. Besides the ungauged spatial characteristics in the SoyangDam watershed, EFF showed a good result of 0.859.

• Journal of the Korean Association of Geographic Information Studies
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• v.16 no.3
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• pp.193-210
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• 2013

This study aims to assess the slope stability variation of Jeollabuk-do drainage areas by RCM model outputs based on A1B climate change scenario and infinite slope stability model based on the specific catchment area concept. For this objective, we downscaled RCM data in time and space: from watershed scale to rain gauge scale in space and from monthly data to daily data in time and also developed the GIS-based infinite slope stability model based on the concept of specific catchment area to calculate spatially-distributed wetness index. For model parameterization, topographic, geologic, forestry digital map were used and model parameters were set up in format of grid cells($90m{\times}90m$). Finally, we applied the future daily rainfall data to the infinite slope stability model and then assess slope stability variation under the climate change scenario. This research consists of two papers: the first paper focuses on the methodologies of climate change scenario preparation and infinite slope stability model development.

• Korean Journal of Remote Sensing
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• v.34 no.6_1
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• pp.997-1007
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• 2018

Drought monitoring is the important system for disasters by climate change. To perform this, it is necessary to measure the precipitation based on satellite rainfall estimation. The data developed in this study provides two kinds of satellite data (raw satellite data and bias-corrected satellite data). The spatial resolution of satellite data is 10 km and the temporal resolution is 1 day. South Korea was selected as the target area, and the original satellite data was constructed, and the bias-correction method was validated. The raw satellite data was constructed using TRMM TMPA and GPM IMERG products. The GRA-IDW was selected for bias-correction method. The correlation coefficient of 0.775 between 1998 and 2017 is relatively high, and TRMM TMPA and GPM IMERG 10 km daily rainfall correlation coefficients are 0.776 and 0.753, respectively. The BIAS values were found to overestimate the raw satellite data over observed data. By using the technique developed in this study, it is possible to provide reliable drought monitoring to Korean peninsula watershed. It is also a basic data for overseas projects including the un-gaged regions. It is expected that reliable gridded data for end users of drought management.

• Journal of Korean Society for Geospatial Information Science
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• v.17 no.2
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• pp.71-79
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• 2009

In this study, a distributed rainfall-runoff model, K-DRUM, based on physical kinematic wave was developed to simulate temporal and spatial distribution of flood discharge considering grid rainfall and grid based GIS hydrological parameters. The developed model can simulate temporal and spatial distribution of surface flow and sub-surface flow during flood period, and input parameters of ASCII format as pre-process can be extracted using ArcView. Output results of ASCII format as post-process can be created to express distribution of discharge in the watershed using GIS and express discharge as animation using TecPlot. an auto calibration method for initial soil moisture conditions that have an effect on discharge in the physics based K-DRUM was additionally developed. The baseflow for Namgang Dam Watershed was analysed to review the applicability of the developed auto calibration method. The accuracy of discharge analysis for application of the method was evaluated using RMSE and NRMSE. Problems in running time and inaccuracy setting using the existing trial and error method were solved by applying an auto calibration method in setting initial soil moisture conditions of K-DRUM.