• Journal of the Korean Association of Geographic Information Studies
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• v.13 no.4
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• pp.157-169
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• 2010

In this study, the applicability of SRTM(The Shuttle Radar Topography Mission) DEM(Digital Elevation Model) which is one of the remotely sensed shuttle's radar digital elevation was tested for use as the input data in a grid-based rainfall-runoff model. The SRTM DEM and digital topographic map derived DEM(TOPO DEM) were building with 500m spatial resolution for the Chungju-Dam watershed which located in the middle east of South Korea, and stream-burning method was applied to delineate the proper flow direction for model application. Similar topographical characteristics were shown as a result of comparing elevation, flow-direction, hydrological slope, number of watershed cell, and profile between SRTM DEM and TOPO DEM. Two DEMs were tested by using a grid-based rainfall-runoff model named KIMSTORM with 6 storm events. The results also showed no significant differences in average values of relative error for both peak runoff(0.91 %) and total runoff volume(0.29 %). The results showed that the SRTM DEM has applicability like TOPO DEM for use in a grid-based rainfall-runoff modeling.

• Spatial Information Research
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• v.17 no.3
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• pp.389-395
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• 2009

In spite of many numerical analysis of debris flow, a little information has been found out. In this paper the watershed is divided to apply rainfall runoff and to estimate debris flow integrating flow and soil article. We use the contour data to extract spatially distributed topographical information like stream channels and networks of sub-basins. A Quasi Digital Elevation Model (Q-DEM) is developed, integrated, and adopted to estimate runoff based on marked one. As a results, it has been found out that the debris flow was close to observed flow hydrograph. Because debris flow is finished in 30 second, it is important that we have to prepare its prior countermeasure to minimize the damage of debris flow. The GIS-linked model will provide effective information to plan river works for debris flow.

• Journal of Korea Water Resources Association
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• v.55 no.12
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• pp.1115-1124
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• 2022

The impact of climate change on water resources was evaluated for Chungju Dam and Soyang-gang Dam basins by constructing an integrated modeling framework consisting of a dam inflow prediction model based on the Variable Infiltration Capacity (VIC) model, a distributed hydrologic model, and an LSTM based dam outflow prediction model. Considering the uncertainty of future climate data, four models of CMIP6 GCM were used as input data of VIC model for future period (2021-2100). As a result of applying future climate data, the average inflow for period increased as the future progressed, and the inflow in the far future (2070-2100) increased by up to 22% compared to that of the observation period (1986-2020). The minimum value of dam discharge lasting 4~50 days was significantly lower than the observed value. This indicates that droughts may occur over a longer period than observed in the past, meaning that citizens of Seoul metropolitan areas may experience severe water shortages due to future droughts. In addition, compared to the near and middle futures, the change in water storage has occurred rapidly in the far future, suggesting that the difficulties of water resource management may increase.

• Journal of the Korean Society of Groundwater Environment
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• v.7 no.3
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• pp.125-132
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• 2000

pH, EC and TDS are basic components in the investigation of groundwater quality, and are very important to the preliminary assessment of groundwater quality. These three chemical components investigated at the Youngsan and Sumjin river basins in 1998 suggest that the groundwater quality is generally good in these basins. Linear regression analysis shows that TDS versus EC has an linear correlation, but EC versus pH, and TDS versus pH have nearly no correlation. The relation of TDS and EC is 1.0 mg/1=1.52 $mu\textrm{S}$/cm, and it is the quality of natural water. In geostatistical analysis. three kinds of data are stationary random functions and they have exponential variograms. According to the isopleth maps of the groundwater quality, the groundwater quality of the Youngsan river basin is more contaminated than that of the Sumjin river basin. The isopleth maps of TDS and EC show very similar patterns because of the strong correlation between TDS and EC. The minimum and maximum values of the groundwater quality data are not reflected on the isopleth maps because kriging produces smooth distributions with minimum estimation variances.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.183-183
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• 2018

최근 국지성 호우와 홍수, 그리고 극심한 가뭄과 같은 기후변화로 인한 극치수문현상이 빈번하게 관측되고 있다. 이는 과거와는 다른 양상의 강우사상으로 광화문(2010), 강남역(2010), 청계천(2010), 청주(2017), 부산(2017) 등 주요 도심지역에 내수침수로 인한 막대한 인명, 재산 피해를 발생시켰으며, 피해의 빈도와 강도가 증가되고 있는 추세이다. 특히 기후변화에 따른 강우강도의 증가는 설계홍수량의 변화를 초래하며, 그로 인해 홍수 위험도 증가와 치수안전도 감소 등 수공구조물의 설계기준에 불확실성을 증가시키는 원인이 되고 있다. 최근 국내에서도 기후변화에 따른 수공시설물 설계빈도 상향에 대한 필요성이 대두되고 있으나 기후변화의 불확실성 및 기후시나리오의 한계로 인해 정량적 분석결과가 제시되지 않아 정책 수립에 반영하기 현실적으로 어려운 상황이다. 본 연구에서는 기후변화에 따른 홍수특성에 대한 도시유역의 영향을 평가하기 위하여 서울 효자배수분구를 대상유역으로 선정하고, 과거관측자료 기준 S0 대비 상세화 기법(Downscaling) 및 편의보정(Bias Correlation)으로 생성된 RCP 4.5 기후시나리오 HadGEM3-RA(RCM)모델을 통해 생산된 S1, S2, S3 기간의 확률강우량의 변화를 평가하였다. 이때 확률분포형은 Gumbel, 매개변수 추정은 최우도법(ML)을 사용하였고, 도시유출모형을 이용하여 최대첨두홍수량 및 침수면적 산정하고 기후변화 기간별 변동성을 분석하였다. 평가 결과 대부분의 도시배수시설물의 설계빈도인 10년빈도를 3사분위값을 기준으로 할 때 50년과 70년 이상의 미래를 가정할 경우 각각 약 10%, 20%의 확률 홍수량이 증가가 예상되었다. 이러한 결과 현재 구축되어 있는 배수시스템의 설계빈도를 크게 상회하는 값으로 도시배수시스템에 많은 어려움을 줄 것으로 예상되며, 정량적 평가 결과가 기후변화 적응 대책 신규 시설물 설계시 참고할 수 있는 기초자료로 활용될 것으로 판단된다.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.780-784
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• 2006

본 연구의 목적은 준분포형 장기유출 모형인 SWAT 모형을 활용하여 충주댐 상류유역에 대한 갈수빈도해석을 실시하고, 비유량을 산정하는데 그 목적이 있다. 이를 위해 중분류 토지피복도, 정밀토양도, 수치표고모델 등의 GIS 데이터를 구축하였으며, $1986{\sim}2004$년에 해당하는 강수량, 상대습도, 일사량, 기온, 풍속 등의 기상자료를 수집하였다. 모의결과 전기간에 대해 ME는 0.71, $R^2$는 0.72로 나타났다. 또한 이 결과로부터 19개 소유역에 대한 지속기간별 갈수량 자료를 구축하여 2.33년, 10년에 대한 빈도해석을 수행하였으며 비유량을 산정하였다. 이러한 결과는 향후 하천유지유량 산정 등 수자원관리 분야에 기초자료로 활용될 것으로 판단된다.

• Journal of Korean Society on Water Environment
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• v.33 no.6
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• pp.661-669
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• 2017

A distributed watershed model CAMEL (Chemicals, Agricultural Management and Erosion Losses) was applied to a small rural watershed where intensive livestock farming sites are located to estimate nitrate leaching rates from soil to groundwater. The model was calibrated against the stream flows, and T-N and $NO_3-N$ concentrations were observed at the watershed outlet for three rainfall events in 2014. The simulation results showed good agreement with the observed stream flows ($R^2=0.67{\sim}0.93$), T-N concentrations ($R^2=0.40{\sim}0.58$) and $NO_3-N$ concentrations ($R^2=0.43{\sim}0.65$). The estimated annual nitrate leaching rate of the watershed was 33.0 kg N/ha/yr. The contributing proportions of individual activities to the total nitrate leaching rate of the watershed were estimated for livestock farming, applications of chemical fertilizer, and manure. The simulation results showed that the highest contributor to the nitrate leaching rate of the watershed was chemical fertilizer applications. The simulation period was for one year only, however, and results may vary depending on different conditions. Gathering input data over a longer period of time and monitoring data for calibration is needed. When this has been accomplished, it is expected that this model can be applied to small rural watersheds for evaluating temporal and spatial variations of nitrogen transformations and transport processes.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.10 no.4
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• pp.53-66
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• 1990

Rainfall is a phenomenon that shows a high variability both in space and time, Hy drologists are usually interested in the description of spatial distribution of rainfall over watershed. The theory of Kriging, generalized covariance technique using nonstationary mean in the regions under orographic effect, was chosen to construct random surface of total storm depth. For the constructed random surface, the double Fourier analysis of the total storm depths was performed, and the principal harmonics of storm were determined. The local component, or storm residuals was obtained by subtracting the periodic component of the storm from total storm depths. It is assumed that the residuals are a sample function of a homogeneous random field. This random field can be characterized by an isotropic one dimensional autocorrelation function or its corresponding spectral density function. Under this assumption, this study proposed a theorectical model for spectral density function adapted to two watersheds.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.88-88
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• 2011

수자원에서 일강수량 모의기법은 다양한 목적으로 활용되고 있으며 기본적으로 수공구조물 설계 및 수자원계획을 수립하기 위한 입력 자료로서 이용된다. 수자원계획은 장기적인 목적을 가지고 수행되는 것이 일반적이며 우리가 목표로 하는 장기간의 일강수량자료의 획득이 어렵기 때문에 단기간의 일강수량자료를 장기 모의하여 이용하게 된다. 일강수량을 모의하는데 있어서 강수계열의 단기간의 기억(memory)을 활용한 Markov Chain 모형이 가장 일반적이며, 기존 Markov Chain 모형을 통한 일강수량 모의에서 발생하는 가장 큰 문제점은 극치강수량을 재현하기 어렵다는 점이다. 이러한 문제점으로 인해 수자원 계획을 수립하는데 있어서 불확실성을 가중시키고 있다. 특히 일강수량 모의기법을 통해서 추정되는 빈도강수량의 과소추정으로 인해 수공구조물 설계 시에 신뢰성을 확보하는 데 문제점이 있다. 이러한 점에서 본 연구에서는 기존 Markov Chain 모형에서 일강수량에 평균적인 특성과 극치특성을 동시에 재현할 수 있도록 불연속 Kernel-Pareto Distribution 기반에 일강수량모의기법을 개발하였다. 한강유역의 3개 강수지점에 대해서 기존 Markov Chain 모형과 본 연구에서 제안한 방법을 적용한 결과 여름의 일강수량 모의 시 1차모멘트인 평균과 2-3차 모멘트 모두 효과적으로 재현하지 못하는 문제점이 나타났다. 그러나 본 연구에서 제안한 불연속 Kernel-Pareto 분포형 기반 Markov Chain 모형은 여름의 일강수량 모의 시 강수계열의 평균적인 특성뿐만 아니라 표준편차 및 왜곡도의 경우에도 관측치의 통계특성을 매우 효과적으로 재현하는 것으로 나타났다. 본 연구에서 제시한 방법론은 전체적으로 기존 Markov Chain 모형에 비해 극치강수량을 재현하는데 유리한 기법으로 판단되며, 또한 극치강수량을 일반강수량으로부터 분리하여 모의함으로서 평균 및 중간값 등 낮은 차수에 모멘트 등 일강수량에 전체적인 분포특성을 더욱 효과적으로 모의할 수 장점을 확인하였다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.5
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• pp.1039-1049
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• 2015

The inflow estimation at large multipurpose dam reservoir is carried out by considering the water balance among the discharge, the storage change during unit time interval obtained from the observed water level near dam structure and area-volume curve. This method can be ideal for level pool reservoir but include potential errors when the inflow is influenced by the water level slope due to backwater effects from upstream flood inflows and strong wind induced by typhoon. In addition, the other uncertainties arisen from the storage reduction due to sedimentation after the dam construction and water level noise due to mechanical vibration transmitted from the electric power generator. These uncertainties impedes the accurate hydraulic inflow measurement requiring exquisite hydrometric data arrangement for reservoir waterbody. In this study, the distributed hydrologic model using UBC-3P boundary setting was applied and its feasibility was evaluated. Finally, the modeling performance has been verified since the calculated determination coefficient has been in between 0.96 to 0.99 after comparing with observed peak inflow and total inflow at Namgang dam reservoir.