• Journal of Korean Society on Water Environment
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• v.23 no.4
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• pp.527-534
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• 2007

To operate scientifical and integrated management of water resources, it needs to identify clearly the quantitative variation and moving pathway of water resources in a basin. Moreover, it needs to also estimate more precisely the amount of runoff generating from the precipitation. Thus, in this study, to carry out more reliable hydrologic analyses, the runoff characteristics according to detailed runoff components and water balance in a basin are analyzed. As a result of yearly water balance analyses, during the period of drought year, the loss is bigger than that of 6-year mean loss and the return flow of groundwater is the most dominant component of runoff. During the period of flood year, the loss is smaller about 4% than that of 6-year mean loss and the subsurface water is the most dominant component of runoff. The loss due to the interception and evapotranspiration for 6-year mean loss is about 53% of the total rainfall, the mean runoff ratio is about 27% and the baseflow is about 22%.

• Journal of Wetlands Research
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• v.11 no.3
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• pp.161-169
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• 2009

Rainfall-runoff procedures of urban area are more complicated than agricultural procedures. Extension and development of town leads to shift of the basin characteristics and it makes more difficult to use runoff models. In this study, the changes of hydrologic circumstances and the shape of hydrograph due to the urbanization in Cho-kyung river basin has been assessed which is the representative urban stream in Jeonju city. The urbanization can be classified as four typical year. The natural basin period(1924) that is before the urban development, the period of construction of Chonbuk National University campus (1963), the period of construction of residential area(1986), and urbanization process has been finally completed in 1995. The rainfall-runoff analysis has been carried out by Storm Water Management Model(SWMM) under condition of the basin characteristics and impervious area of each period. It was found that hydrologic characteristics such as river length, roughness coefficient, and coefficient of surface storage has been decreased. According to the land use change, the pervious area was decreased from 97.7% to 42%, while the impervious area was increased from 0.6% to 34%. The time of concentration was shorten from 90 minutes to 37 minutes. Along with decreasing the time of concentration, the peak discharge was increased from $4.37m^3/s$ to $111.13m^3/s$, and the runoff rate was also increased from 0.8% to 68%.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.1450-1454
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• 2006

Empirical mode decomposition (EMD) is applied to analyze time series characterized with nonlinearity and nonstationarity. This decomposition could be utilized to construct finite and small number intrinsic mode functions (IMF) that describe complicated time series, while admitting the Hilbert transformation properties. EMD has the capability of being adaptive, capture local characteristics, and applicable to nonlinear and nonstationary processes. Unlike discrete wavelet transform (DWT), IMF eliminates spurious harmonics and retains meaningful instantaneous frequencies. Examples based on data representing natural phenomena are given to demonstrate highlight the power of this method in contrast and comparison of other ones. A presentation of the energy-frequency-time distribution of these signals found to be more informative and intuitive when based on Hilbert transformation.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.1830-1834
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• 2006

본 연구에서는 강우의 수문학적 특성을 고려하여 도시지역에서의 시간분포를 분석하고, Huff의 무차원 누가곡선 및 Yen과 Chow의 무차원 특성변수를 제시하였으며, 강우의 수문학적 특성은 지속기간, 강우의 발생원인(장마, 태풍, 집중호우, 전선형 강우), 강우강도 등으로 분류하였다. 본 연구의 수행으로 인해 얻어진 결과를 요약하면 다음과 같다. 첫째, 국내 도시지역의 단시간 강우의 최대강우강도는 전방위구간에서 발생할 확률이 가장 높게 나타났으며, 둘째, 강우발생원인별 분류에서도 전반적으로 전방위구간에서, 태풍의 경우에는 후방위구간에서 최대강우강도가 발생하였다. 셋째, 평균강우강도이하의 경호우와 평균강우강도이상의 중 호우에서는 전방위구간에서 최대강우강도가 발생하였다. 넷째, 전기간 강우자료를 이용한 기존 연구들의 무차원 누가곡선 및 특성변수와의 비교를 실시하여, 수문학적 특성에 따라 무차원 누가곡선의 위치 및 특성변수의 값에서 차이가 발생한다는 것을 알 수 있었다.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2002.10a
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• pp.217-220
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• 2002

This study was carried out to investigate the characteristics of the field-saturated hydraulic conductivity$(K_{fs})$ and matric flux potential$({\Phi}_m)$ measured by the Guelph Permeameter at the Backokpo watershed in the Han river and at the Bangdong watershed in the Keum river. And the Alpha $({\alpha})$ value which is the ratio of $K_{fs}$ to ${\Phi}_m$ were determined and the ${\alpha}$ values along with the defined soil series could be utilized to classify the soil in the Korean watershed into the SCS hydrologic soil groups.

• Water Engineering Research
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• v.5 no.2
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• pp.81-99
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• 2004

Long term streamflow regime under virtual climate change scenario was examined. Rainfall forecast simulation of the Canadian Global Coupled Model (CGCM2) of the Canadian Climate Center for modeling and analysis for the IPCC SRES B2 scenario was used for analysis. The B2 scenario envisions slower population growth (10.4 billion by 2010) with a more rapidly evolving economy and more emphasis on environmental protection. The relatively large scale of GCM hinders the accurate computation of the important streamflow characteristics such as the peak flow rate and lag time, etc. The GCM rainfall with more than 100km scale was downscaled to 2km-scale using the space-time stochastic random cascade model. The HEC-HMS was used for distributed hydrologic model which can take the grid rainfall as input data. The result illustrates that the annual variation of the total runoff and the peak flow can be much greater than rainfall variation, which means actual impact of rainfall variation for the available water resources can be much greater than the extent of the rainfall variation.

• Journal of the Korean Society of Safety
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• v.26 no.2
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• pp.83-88
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• 2011

Annually, many parts of the Korea have been damaged from the localized heavy rain and/or typhoons which peak between June and September, which result in extensive financial and human loss. Especially, because the most area of Gangwon province is composed of the steep slope mountains, the damages by the debris flow or land-sliding are more frequent and the frequency has been increased. To analyze the characteristics and causes of these debris flow disasters, lots of study are recently being conducted through database of weather, hydrologic, soil etc using a GIS or remote sensing. In this study, we applied GIS method to analyze the risk of the debris flow area. With the statistical analysis and infinite slope stability model(SINMAP), the debris flow risk level of the mountain slope was generated. As a result, the GIS statistical analysis showed high correlation that former model of SINMAP in determining the debris flow risk area.

• Korean Journal of Hydrosciences
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• v.8
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• pp.125-136
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• 1997

The simulation techniques of hydrologic data series have develped for the purposes of the design of water resources system, the optimization of reservoir operation, and the design of flood control of reservoir, etc. While the stochastic models are usually used in most analysis of water resources fields for the generation of data sequences, the indexed sequential modeling (ISM) method based on generation of a series of overlapping short-term flow sequences directly from the historical record has been used for the data generation in the western USA since the early of 1980s. It was reported that the reliable results by ISM were obtained in practical applications. In this study, we generate annual inflow series at a location of Hong Cheon Dam site by using ISM method and autoregressive, order-1 model (AR(1)), and estimate the drought characteristics for the comparison aim between ISM and AR(1).

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.1008-1013
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• 2007

The objectives of the paper were to identify appropriate best management practices (BMPs) for reducing nonpoint source (NPS) pollutant loadings and to simulate the effects of the application of the several BMP scenarios on the study watershed using Agricultural Nonpoint Source (AGNPS) model. AGNPS model was calibrated and validated for runoff, sediment yield, and nutrient components using the observed hydrologic and water quality data. The simulated runoff, sediment, and nutrient components were well agreed with observed data. The validated AGNPS was applied to estimate the NPS pollution removal efficiency for BMP scenarios which were selected considering the pollutant characteristics of the study watershed.

• Water for future
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• v.23 no.1
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• pp.79-87
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• 1990

In this study, a regression model, which relates annual flood peak flows collected at stramflow gaging stations in the Han river and Nakdong river basin to both basin characteristics and precipitation data, is developed by using the generalized least squares method which can provide reasonable and unbiased estimator of error variance by separating error variance of the regression model into that due to model error and due to sampling error. This model may be used as a mechanism for transferring hydrologic information from the gaged sites to ungaged sites.