• Journal of Korea Water Resources Association
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• v.53 no.6
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• pp.417-425
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• 2020

In order to predict and prevent hydrological disasters such as flood, it is necessary to accurately estimate rainfall. In this paper, an areal average rainfall estimation method using multiple elevation observation data of an electromagnetic wave rain gauge is presented. The small electromagnetic rain gauge system is a very small precipitation radar that operates at K-band with dual-polarization technology for very short distance observation. The areal average rainfall estimation method is based on the assumption that the variation in rainfall over the observation range is small because the observation distance and time are very short. The proposed method has been evaluated by comparing with ground instruments such as tipping-bucket rain gauges and a Parsivel. The evaluation results show that the methodology works fairly well for the rainfall events which are shown here.

• Korean Journal of Ecology and Environment
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• v.36 no.3 s.104
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• pp.242-256
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• 2003

This study aimed to determine the relationship between rainfall-discharge patterns and maior aquatic environmental factors in a river-type reservoir. Specifically, daily monitoring was conducted in Paltang Reservoir from January 1999 to December 2001. Observation of the daily changes of the environment factors showed that natural meteorological factors and hydrological factors causing the change of water discharge had a major effect on the aquatic environment. Rainfall was the main source of hydrological changes, with its frequency a possible direct variable governing the range of discharge changes. Rainfall was weak in November${\sim}$May and heavy in June${\sim}$October (heavist in summer). The range of water discharge was greatest during summer (July to September) and lowest during winter (January to February). A principal component analysis (PCA) showed that aquatic environmental factors could be classified into three different types in the pattern of annual variation. First, type I included water temperature, turbidity, water color and organic matter (COD), which increased with increasing water discharge. Second, type ll consisted of DO and pH, which decreased with increasing water discharge. Third, type III included conductivity, alkalinity and chloride ion, which showed middle values with increasing water discharge. Monthly variation of aquatic environments explained by the first two dimensions of the PCA suggests that aquatic environments of Paltang Reservoir may have annual cycle typical of river-type reservoirs depending on hydrological factor such as water discharge.

• Journal of Korean Society of Disaster and Security
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• v.15 no.4
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• pp.87-98
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• 2022

In recent years, frequent localized heavy rainfalls, which have a lot of rainfall in a short period of time, have been increasingly causing flooding damages. To prevent damage caused by localized heavy rainfalls, Hydrological Quantitative Precipitation Forecast (HQPF) was developed using the Local ENsemble prediction System (LENS) provided by the Korea Meteorological Administration (KMA) and Machine Learning and Probability Matching (PM) techniques using Digital forecast data. HQPF is produced as information on the impact of heavy rainfall to prepare for flooding damage caused by localized heavy rainfalls, but there is a tendency to overestimate the low rainfall intensity. In this study, we improved HQPF by expanding the period of machine learning data, analyzing ensemble techniques, and changing the process of Probability Matching (PM) techniques to improve predictive accuracy and over-predictive propensity of HQPF. In order to evaluate the predictive performance of the improved HQPF, we performed the predictive performance verification on heavy rainfall cases caused by the Changma front from August 27, 2021 to September 3, 2021. We found that the improved HQPF showed a significantly improved prediction accuracy for rainfall below 10 mm, as well as the over-prediction tendency, such as predicting the likelihood of occurrence and rainfall area similar to observation.

• Water for future
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• v.26 no.4
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• pp.117-125
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• 1993

A flood -flow management system model of river basin has been developed in this study. The system model consists of the observation and telemetering system, the rainfall forecasting and data-bank system, the flood runoff simulation system, the dam operation simulation system, the flood forecasting simulation system and the flood warning system. The Multivariate model(MV) and Meterological-factor regression model(FR) for rainfall forecasting and the Streamflow synthesis and reservoir regulation(SSARR) model for flood runoff simulation have been adopted for the development of a new system model for flood-flow management. These models are calibrated to determine the optimal parameters on the basis of observed rainfall, streamflow and other hydrological data during the past flood periods. The flood-flow management system model with SSARR model(FFMM-SR,FFMM-SR(FR) and FFMM-SR(MV)), in which the integrated operation of dams and rainfall forecasting in the basin are considered, is then suggested and applied for flood-flow management and forecasting. The results of the simulations done at the base stations are analysed and were found to be more accurate and effective in the FFMM-SR and FFMM0-SR(MV).

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.776-780
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• 2005

한국건설기술연구원에서 운영하고 있는 설마천 시험유역을 대상으로 관측자료를 이용하여 물순환 해석을 수행하고자 기초자료로 강우량, 유출량, 지하수이용량, 지하수위 변화에 의한 유역 저류량 등의 관측자료를 수집하여 2004년의 연간 물수지 분석을 수행하였다. 설마천 시험유역의 유역의 물순환 구조는 자연계의 유입과 유출이 지배적이며, 이들의 수문성분을 규명하기 위해서는 각각의 수문성분들의 관측 및 해석이 필요하며, 각 수문성분들의 물수지 분석을 통하여 정량적인 합의 결과를 가시적으로 확보함이 매우 중요하다. 신뢰도와 정확성에 근거한 관측자료를 이용한 물순환 해석결과는 수문성분들의 총체적 표현이라 할 수 있는 모형(model)의 중요 입력자료이며, 모형의 분석결과를 검증할 수 있는 중요한 기준이 된다 설마천 시험유역에 기 설치된 수문모니터링 자료로 물순환 해석을 수행하는 데는 부족함이 있다. 따라서, 추가적인 수문관측 및 모니터링이 필요하며, 지속적인 수문모니터링이 이루어진다면 보다 구체적인 물순환 관계를 규명할 수 있을 것으로 기대된다.

• Water Engineering Research
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• v.1 no.3
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• pp.233-242
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• 2000

A system for regularly appraising the reliability of streamflow data, KORSAS (KOwaco's Regular Streamflow Appraising System) was developed on PC based Windows for hydrological specialists and engineers working in the Korea Water Resources Corporation (KOWACO). The reliability of streamflow rates can be evaluated with KORSAS in various as pects according to the evaluation duration and method. The former being selected as short term (event based) or long term(continus based), and the latter being classified into comparison methods of flow measurement, other stations results, and simulation. Rainfall-runoff models can be used together with KORSAS in order to evaluate the reliability of observed flow data by comparing with simulated flow data. The objective of this study is to develop a systematic methodology in various aspects to evaluate the reliability of streamflow data regularly.

• Magazine of the Korean Society of Agricultural Engineers
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• v.37 no.3_4
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• pp.48-60
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• 1995

A flood - flow forecasting system model of river basins has been developed in this study. The system model consists of the data management system(the observation and telemetering system, the rainfall forecasting and data-bank system), the flood runoff simulation system, the reservoir operation simulation system, the flood forecasting simulation system, the flood warning system and the user's menu system. The Multivariate Rainfall Forecasting model, Meteorological factor regression model and Zone expected rainfall model for rainfall forecasting and the Streamflow synthesis and reservoir regulation(SSARR) model for flood runoff simulation have been adopted for the development of a new system model for flood - flow forecasting. These models are calibrated to determine the optimal parameters on the basis of observed rainfall, 7 streamfiow and other hydrological data during the past flood periods.

• Journal of Environmental Science International
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• v.23 no.4
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• pp.533-541
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• 2014

The streams in Jeju Island have very distinctive hydrological and geological properties and there are a lot of limits in applying the general flood estimation method. This study presented parameters dominant in the Hancheon stream of Jeju Island by analyzing the sensitivity of parameters of HEC-HMS model regarding rainfall events in the target basin, and extracted the optimal parameter(Time of Concentration of Clark Unit Hydrograph: Kraven II method, Storage Coefficient: Sabol method) by analyzing and comparing it with the flood runoff data observed in the site and Jeju Island's observation data.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.413-413
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• 2023

Wetlands are a critical component of the global carbon cycle and are essential in mitigating climate change. Accurately quantifying wetland carbon emissions is crucial for understanding and predicting the impact of wetlands on the global carbon budget. The uncertainty quantifying carbon in wetlands may comes from the ecosystem's hydrological, biochemical, and microbiological variability. The Community Land Model is a sophisticated and flexible land surface model that offers several configuration options such as energy and water fluxes, vegetation dynamics, and biogeochemical cycling, necessitating careful consideration for the alternative configurations before model implementation to develop a practical model framework. We conducted a systematic literature review, analyzing the alternatives, focusing on the carbon stock pools configurations and the parameters with significant sensitivity for carbon quantification in wetlands. In addition, we evaluated the feasibility and availability of in situ observation data necessary for validating the different alternatives. This analysis identified the most suitable option for our study site, the Binbong Wetland, in Korea.

• Journal of Korea Water Resources Association
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• v.50 no.5
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• pp.335-346
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• 2017

This study generated the radar-based forecasted rainfall using spatial-scale decomposition method (SCDM) and evaluated the hydrological applicability with forecasted rainfall by KMA (MAPLE, KONOS) in terms of urban flood forecasting. SCDM is to separate the small-scale field (convective cell) and large-scale field (straitform cell) from radar rainfield. And each separated field is forecasted by translation model and storm tracker nowcasting model for improvement of QPF accuracy. As the evaluated results of various QPF for three rainfall events in Seoul and Metropolitan area, proposed method showed better prediction accuracy than MAPLE and KONOS considering the simplicity of the methodology. In addition, this study assessed the urban hydrological applicability for Gangnam basin. As the results, KONOS simulated the peak of water depth more accurately than MAPLE and SCDM, however cannot simulated the timeseries pattern of water depth. In the case of SCDM, the quantitative error was larger than observed water depth, but the simulated pattern was similar to observation. The SCDM will be useful information for flood forecasting if quantitative accuracy is improved through the adjustment technique and blending with NWP.