• Ocean and Polar Research
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• v.38 no.4
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• pp.331-338
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• 2016

Many studies using tracers have been conducted to understand a physical process in a system. Rain-on-snow could accelerate snowmelt processes, which influences the hydrological process in both temperate and polar regions. Hydrological and ecological conditions will be affected by the amount and timing of discharge reaching the bottom of a snowpack. The discharge consists of the rain-on-snow, pore water penetrating into the snowpack and natural meltwater. In this study, after a rain-on-snow experiment, we conducted an isotopic hydrograph separation to distinguish rainwater and pore water from meltwater. Using the isotopic data of snow and meltwater from Lee et al. (2010), two components were separated based on the assumption that rainwater and pore water are new water and natural meltwater is old water. After the second rain-on-snow experiment, the maximum contributions of rainwater and pore water reached up to 69% of the discharge and then decreased. During the study period, the measured total discharge was 4153 L and 40% (based on hydrogen isotope) of rainwater and pore water was calculated in the discharge, which is not consistent with what Lee et al. (2016) calculated using chemical separation (63%). This inconsistency can be explained by how an end-member was defined in both approaches. The contributions of artificial rainonsnow and pore water to melwater discharge range between the two methods. This study will suggest a mixing calculation from isotopic compositions of the Southern Ocean.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.1558-1562
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• 2007

우리나라 지형은 전체의 70%가 산지로 이루어져 있다. 특히 강원도 지역과 같이 산지가 대부분인 지역에서는 경사도에 따라 강우에 의한 유출특성이 크게 달라질 수 있으므로 지형의 경사가 고려된 유출량 산정방식이 필요하다. 현재 유출량 산정 방식에 많이 이용되고 있는 SCS의 CN값은 미국의 중서부 지역과 같이 경사도 5%미만인 지역에서의 유출량 산정에 적합한 유출곡선지수이다. 경사도 5%에서 유출량 산정에 적합한 CN값을 우리나라의 강원도 지형과 같이 복잡하고 경사도가 심한 지역에 적용하기에는 부적합하다. 따라서 본 연구에서는 연구대상지역인 도암댐 유역의 평균 25.8% 경사도를 고려한 직접유출량을 산정하여 기존 평균 경사도 5%일 때의 직접유출량과 비교분석하였다. 본 연구의 비교분석에 있어서 직접유출의 모의가 가능한 Long-Term Hydrologic Impact Assessment (L-THIA) ArcView GIS 모델을 사용하였고 모델의 적용성 평가를 위해 수문분석에 사용되고 있는 WHAT 모듈을 이용하여 분리된 직접유출과 비교하였다. 그 결과 유출량 산정을 위해 CN값 산정시 강원도 지형과 같이 지형이 복잡하고 경사가 심한 지형에 있어서는 유역의 경사도를 고려하여 유출을 모의해야 한다는 것을 알 수 있다.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.827-831
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• 2010

홍수범람 또는 피해에 의해 발생한 인명피해 및 재산손실과 이를 치유하기 위해 구호 복구에 들어가는 노력 등 수해가 가져오는 여러 가지 사회경제적 역기능은 홍수의 특성을 정확하게 이해하고 이를 예방하기 위한 적절한 계획수립 및 시행을 포함하는 과학적인 홍수분석시스템을 도입해서 홍수를 사전에 예방하거나 경감할 수 있는 수방대책을 수립하는 것이 방안이 될 수 있다. 우리나라의 하천에 대한 홍수재해특성은 체계적인 하천정비의 미비, 하천제방, 호안시설의 붕괴 및 유실 등이 있을수 있으며, 또한 저수지 소류지 보 등의 파제가 홍수시 잦은 발생을 초래하고 있다. 하천부속시설물(수문, 갑문, 방수구 등)의 기능 및 제방과의 접속부실은 최근에 많이 발생하는 하천의 피해양상이 된다. 하천유역관리 및 방제의 비구조물적인 요인으로는 하천유역의 개발에 의한 유출요인의 증대가 있으며, 하천연안 저지대의 난개발로 인한 상습침수 지역조장 등이 요인이 될 수 있다. 또한 소하천, 지방하천 및 국가하천의 분리관리로 인한 일관성있는 하천관리가 미비한 점도 있다. 항상 피해가 발생한 후 원상복구에 치중하는 복구계획과 환경단체 및 방제조직 그리고 제도 및 법규의 미비도 홍수재해의 원인이 될 수 있다. 우리나라는 지역특성 및 강우특성에 따라 많은 차이를 나타내기 때문에 그 특성에 적합한 홍수재해대응시스템을 구축해야 하는 것도 충분히 고려해야 한다.

• Proceedings of the Korea Contents Association Conference
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• 2008.05a
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• pp.788-791
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• 2008

On this study, following works have been carried out : division of Han River Basin into 24 sub basins, use of rainfall data of 151 stations to make spatial distribution of rainfall, selection of control points such as Soyanggang Dam, Chungju Dam, Chungju Release Control Dam, Heongseong Dam, Hwachun Dam, Chuncheon Dam, Uiam Dam, Cheongpyung Dam and Paldang Dam, selection of SSARR (Streamflow Synthesis and Reservoir Regulation) model as a hydrologic model, preparation of input data of SSARR model, sensitivity analysis of parameter using hydrologic data of 2002. The sensitivity analysis showed that soil moisture index versus runoff percent (SMI-ROP), baseflow infiltration index versus baseflow percent (BII-BFP) and surface-subsurface separation (S-SS) parameters are higher sensitive parameters to the simulation result.

• Journal of Soil and Groundwater Environment
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• v.27 no.1
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• pp.50-59
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• 2022

There are several methods for separating the baseflow from the hydrograph, and graphical methods (GM) have mostly been used. GMs are those that separate the baseflow from the direct flow simply by connecting rising point with inflection point or points related to some duration from a hydrograph. Environmental tracer method (ETM) is another tool researched and developed under several conditions to estimate the groundwater recharge. The goal of this study is to separate the baseflow component from a storm hydrograph by applying various GMs and ETM, and to compare their results. The baseflow component estimated by ETM was different from the results by GMs in terms of their shapes of fluctuation and flow rates. Another important feature is that the form of the baseflow to which ETM is applied is similar to that of a storm hydrograph. This similarity is presumed to be due to the selection of tracer that respond quickly to rainfall.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.253-253
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• 2020

최근 전 세계는 급격한 기후변화와 도시화의 집중 등으로 인해 예상치 못한 수문학적인 문제, 특히 도시 내 홍수 피해 규모와 빈도가 매년 증가하고 있다. 기존의 도시 개발은 그레이 인프라(Gray Infrastructure)형을 중심으로 불투수 포장면의 증가를 가져왔다. 그 결과로 자연적 투수층이 감소하여 첨두유량 증가, 침투량 감소와 같은 도시물 순환의 문제점이 부각되기 시작했다. 이에 많은 국가들이 그린 인프라(Green Infrastructure)의 중요성과 필요성을 인지하고 그와 관련된 정책 마련에 나서고 있다. 그린 인프라는 모든 개발사업의 계획 이전에 고려되느냐 기타 기반 시설의 계획 후 입지를 결정하느냐에 따라 입지 선정 기준을 크게 두 가지로 구축할 수 있는데, 본 연구는 도시 내 물 순환을 관리하여 유출수를 지표로 침투시켜 도시의 회복력을 평가하는 것이기 때문에 후자에 해당된다. 자연과 분리되거나 별도로 적용하지 않으면서 기후변화에 대응할 수 있는 지속가능한 도시를 만들 수 있으며 소규모로도 물 순환을 가능하게 해 도시의 큰 구조적 변화 없이 적용 가능하다. 본 연구에서는 서울 신월지구에 선행 된 시험 관측 결과를 토대로 도시 내 그린 인프라의 설치에 따른 도시 회복력에 대한 정의를 내려보았다.

• Korean Journal of Ecology and Environment
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• v.54 no.1
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• pp.49-60
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• 2021

We examined the flow characteristics by direct runoff and base flow in a headwater stream during observed 59 rainfall events of flood season (June~September) from 2017 to 2020 yrs. Total precipitation ranged from 5.0 to 400.8 mm, total runoff ranged from 0.1 to 176.5 mm, and runoff ratio ranged from 0.1 to 242.9% during the rainfall events. From hydrograph separation, flow duration in base flow (139.3 days) was tended to be longer than direct runoff (78.3 days), while the contribution of direct runoff in total runoff (54.2%) was greater than base flow (45.8%). The total amount and peak flow of direct runoff and base flow had the highest correlation (p<0.05) with total precipitation and duration of rain among rainfall and soil moisture conditions. Dominant rainfall events for the total amount and peak flow of base flow were generated under 5.0~200.4 and 10.5~110.5 mm in total precipitation. However, when direct runoff occurred as dominant rainfall events, total amount and peak flow were increased by 267.4~400.8 and 169.0~400.8 mm in total precipitation. Therefore, the unique aspects of our study design permitted us to draw inferences about flow characteristic analysis with the contribution of base flow and/or direct runoff in the total runoff in a headwater stream. Furthermore, it will be useful for the long-term strategy of effective water management for integrated surface-groundwater in the forested headwater stream.

• Journal of Korea Water Resources Association
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• v.38 no.12 s.161
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• pp.985-994
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• 2005

We examined problems of the principal component analysis(PCA), which is able to analyze at the low dimensionality as a methodologv to assess hydrologic time series, and introduced the theory and characteristics of independent component analysis(ICA) that can supplement problems of principal component analysis. We also applied the global sea surface temperature(SST) of the Nino region and assessed the correlation between El $\tilde{n}ino$-Southern Oscillation(ENSO) and SST. The results of examining separation-ability of principal components using mixed signals indicate that the independent component analysis is statistically superior compared to that of the principal component analysis. Finally, we assessed correlation between ENSO and global anomaly SST. The independent component analysis was applied to the $5^{\circ}{\times}5^{\circ}$(latitude and longitude) global anomaly SST in the Nino+3.4 region that is the El $\tilde{n}ino$ observation section. We assessed the correlation with the ENSO years. These results of the analysis show that only one independent component($86\%$) was able to represent the entire behavior and was consistent with the main ENSO years. Finally, we carried out independent component analysis for summer seasonal rainfalls at nine stations and could extract ICs to reflect geographical characteristics. The increasing trend has been shown at IC-1 and IC-2 since 1970s.

• Journal of Korea Water Resources Association
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• v.37 no.1
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• pp.21-29
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• 2004

The growth of water resources engineering associated with stable supply, management, development is essential to overcome the coming water deficit of our country. Large scale remote sensing and the analysis of sub-pixel variability of soil moisture fields are necessary in order to understand water cycle and to develop appropriate hydrologic model. The target resolution of coming Global monitoring of soil moisture field is about 10km which is not appropriate for the regional scale hydrologic model. Therefore, we need a downscaling scheme to generate hydrologic variables which are suitable for the regional hydrologic model. The results of the analysis of sub-pixel soil moisture variability show that the relationship between ancillary data and soil moisture fields shows there is very weak linear relationship. A downscaling scheme was developed using physically-based classification scheme and Neural Networks which are able to link the nonlinear relationship between ancillary data and soil moisture fields. The model is demonstrated by downscaling soil moisture fields from 4km to 0.2km resolution using remotely-sensed data from the Washita'92 experiment.

• Journal of Soil and Groundwater Environment
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• v.11 no.5
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• pp.9-19
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• 2006

The accurate estimation of groundwater recharge is important for the proper management of groundwater systems. The widely used techniques of groundwater recharge estimation include water table fluctuation method, baseflow separation method, and annual water balance method. However, these methods can not represent the temporal-spatial variability of recharge resulting from climatic condition, land use, soil storage and hydrogeological heterogeneity because the methods are all based on the lumped concept and local scale problems. Therefore, the objective of this paper is to present an effective method for estimating groundwater recharge with spatial-temporal variability using the SWAT model which can represent the heterogeneity of the watershed. The SWAT model can simulate daily surface runoff, evapotranspiration, soil storage, recharge, and groundwater flow within the watershed. The model was applied to the Musimcheon watershed located in the upstream of Mihocheon watershed. Hydrological components were determined during the period from 2001 to 2004, and the validity of the results was tested by comparing the estimated runoff with the observed runoff at the outlet of the catchment. The results of temporal and spatial variations of groundwater recharge were presented here. This study suggests that variations in recharge can be significantly affected by subbasin slope as well as land use.