• Journal of Korea Water Resources Association
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• v.39 no.8 s.169
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• pp.703-716
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• 2006

The flow duration curves in the present and the ideal hydrologic cycle were derived using SWAT model. The present situation is the landuse and the groundwater withdrawal in the year of 2000 and the ideal situation is the landuse of 1975 and no groundwater withdrawal. These results were compared with the previous instream flow requirements which are the larger flow between the average drought flow and environmental control flow. As a result, the present and ideal drought flows of Ojeoncheon, Hakuicheon, Samseongcheon, and Sammakcheon, were the same and the drought flows of Samseongcheon and Sammakcheon were even zero since the baseflow is very little due to the small and mountainous watersheds. The previous instream flow requirement for the riverine function is also larger than the low flow of the ideal hydrologic cycle. The present method to set the instream flow requirement is not proper for the small mountainous watershed since it can be usually overestimated and drive the artificial measures to secure the streamflow Therefore, another method should be developed such as the low flow and the average flow between the drought flow and the low flow of the ideal hydrologic cycle using the proper hydrologic simulation model such as SWAT which can consider the landuse.

• Journal of Korea Water Resources Association
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• v.53 no.8
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• pp.605-616
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• 2020

The purpose of this study is to assess the future hydrological and water quality change of Man-gyeong river basin (1,602 ㎢) based on future extreme climate change scenarios and reduction of inter-basin water transfer amount using SWAT (Soil and Water Assessment Tool). The SWAT was calibrated (2012~2014) and validated (2016~2018) at 2 water level observation stations (DC, JJ) and 2 water quality observation stations (SR, GJ) considering inter-basin water transfer amount, stream water withdrawal, and point source data. For the streamflow, the coefficient of determination (R²) was 0.70 and the average Nash-Sutcliffe efficiency (NSE) was 0.51 respectively. For the water quality of SS, T-N, and T-P, the R² was 0.72, 0.80 and 0.72 respectively. The future average streamflow under climate change scenarios increased up to 459 mm/yr, and average SS, T-N and T-P yields also increased up to 19,548 ton/yr, 68,748 kg/yr, and 13,728 kg/yr respectively. When the amount of inter basin water transfer decreased, the streamflow especially decreased in spring and winter periods, and the future water quality yields increased under the influence of precipitation. In order to solve the deterioration of water quality due to decrease in the flow rate and an increase in the load, the amount of inter basin water transfer should be maintained to a certain level.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.1048-1052
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• 2008

본 연구의 목적은 기후변화로부터 예상되는 기온 변화로 인한 유출수문성분의 변동성을 평가하고자 하는 것이다. 이를 위해 52개 기상관측소 자료를 이용하여 연평균 기온의 변동성을 분석한 결과 평균 $0.03^{\circ}C$/year이 증가하는 것으로 나타났다. 수문성분 분석을 위해 SWAT 모형을 4개 댐 상류유역에 적용하여 모형의 적용성을 검정하였다. 기온 $1^{\circ}C$, $3^{\circ}C$, $5^{\circ}C$ 증가를 고려한 가상 시나리오를 구축하여 모형에 적용하였다. 기온 증가에 따라 수문성분 중 지하수 유출량이 가장 민감하게 변하는 것으로 나타났으며 토양내 측방흐름은 변화가 없는 것으로 나타났다. 기온 증가에 따라 지표유출량, 지하수유출량, 실제 증발산량은 30% 이내의 변동성을 보임을 확인하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.219-219
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• 2019

모래저장형댐(sand dam)은 계곡이나 하천을 가로질러 보를 설치하고 확보된 공간을 모래와 같은 공극이 큰 투수성 재료로 채운 후 그 채움재 안에 물을 저장하는 구조물로서 증발량이 큰 건조지역에서 수자원 확보 수단으로 널리 이용되고 있다(Hanson and Nilsson, 1986). 국내에서는 차수 및 저류를 위한 제체를 지하 땅속에 설치한 지하수댐을 운영하거나 사방댐을 소규모 수자원공급시설로 개조하여 활용한 일부 사례가 있으나, 전형적인 모래저장형댐의 설계, 시공, 운영 사례가 전무하다. 본 연구에서는 A지역을 대상으로 모래저장형댐의 저류용량을 설계하고 수자원 확보효과를 분석하기 위해서 유역수문모형 SWAT으로 모의한 장기유출량과 방류구, 위어 등을 고려한 저수지 유출추적을 수행하였다. 모래저장형댐의 형태, 규모, 취수량, 지형조건, 수문학적 조건 등에 따른 댐내 수위, 저류량, 방류량 등의 변화를 분석하여 설치 부지에 대한 적정 설계 인자를 도출하였다. 또한 평시 및 가뭄시 물공급 효과와 유황개선 효과를 정량적으로 분석, 제시하였다.

• Journal of Korea Water Resources Association
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• v.46 no.6
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• pp.569-583
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• 2013

This study is to evaluate the future climate change impact on hydrological components in the Seolmacheon ($8.54km^2$) mixed forest catchment located in the northwest of South Korea using SWAT (Soil and Water Assessment Tool) model. To reduce the uncertainty, the model was spatially calibrated (2007~2008) and validated (2009~2010) using daily observed streamflow, evapotranspiration, and soil moisture data. Hydrological predicted values matched well with the observed values by showing coefficient of determination ($R^2$) from 0.74 to 0.91 for streamflow, from 0.56 to 0.71 for evapotranspiration, and from 0.45 to 0.71 for soil moisture. The HadGEM3-RA future weather data of Representative Concentration pathway (RCP) 4.5 and 8.5 scenarios of the IPCC (Intergovernmental Panel on Climate Change) AR5 (Assessment Report 5) were adopted for future assessment after bias correction of ground measured data. The future changes in annual temperature and precipitation showed an upward tendency from $0.9^{\circ}C$ to $4.2^{\circ}C$ and from 7.9% to 20.4% respectively. The future streamflow showed an increase from 0.6% to 15.7%, but runoff ratio showed a decrease from 3.8% to 5.4%. The future predicted evapotranspiration about precipitation increased from 4.1% to 6.8%, and the future soil moisture decreased from 4.3% to 5.5%.

• Journal of Korea Water Resources Association
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• v.49 no.6
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• pp.509-518
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• 2016

This study assessed drought of Cheongmicheon watershed from 1985 to 2015 according to duration. In order to quantify drought, we used meteorological and hydrological drought index. Standardized Precipitation Index(SPI) based on precipitation and Standardized Precipitation Evapotranspiration Index(SPEI) based on precipitation and evapotranspiration were applied as meteorological drought index. Palmer Drought Severity Index(PDSI) and Stream Drought Index(SDI) based on simulation of Soil and Water Assessment Tool(SWAT) model were applied as agricultural and hydrological drought index. As a result, in case average of extreme and averaged drought, 2014 and 2015 have the most vulnerable in all drought indices. Variation of drought showed different trend with regard to analysis of frequency. Also, the extreme and averaged drought have high correlation between drought indices excluding between PDSIs. However, each drought index showed different occurrence year and severity of drought Therefore, drought indices with various characteristics were used to analysis drought.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.273-277
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• 2011

오늘날 기후변화는 기후 시스템을 구성하는 대기, 해양, 생물, 빙하, 육지 등의 다양한 구성요소에 작용하여 자연 생태계와 인간의 사회 및 경제 시스템에 커다란 영향을 미친다. 특히 최근 인간의 활동에 의해 야기된 기후변화는 극치적인 기후 현상의 빈도와 강도에 영향을 미칠 뿐만 아니라, 기후변화 현상은 수환경 시스템, 하천 생태계와 유역관리 등의 다양한 분야에 걸쳐 심각한 문제를 발생시킨다. 이에 따른 수자원의 효율적인 관리와 안정적인 물공급에 어려움을 증대시킬 것으로 전망되며, 현재 이것은 각 분야별로 해결해야 할 범지구적 문제로 인식되고 있다. 기후변화를 탐지하고 예측하기 위해서는 SRES 배출시나리오를 이용한 미래의 기후변화 장기시나리오가 필요한데, 이를 위한 기본적인 도구로 전지구기후모형(Global Climate Models, GCMs)이 있다. 기후변화에 따른 지역적 차원의 수자원에의 영향 분석을 위해서는 GCMs의 결과를 바탕으로 지역 규모에서의 기후 자료로 변환하는 규모내림(downscaling) 기법을 이용한다. 본 연구는 기후변화 분석의 가장 기본이라 할 수 있는 국내에 적합한 GCM의 선정 및 우리나라의 시공간적 기상패턴의 정밀한 구현을 위한 규모내림기법의 적용을 통하여 실시하였다. 현재 뿐 아니라 미래 90년간 (2011년 ~ 2100년)의 기상 자료를 생산하고 이를 SWAT 모형에 적용하였다. 이러한 GCMs-규모내림-SWAT 모형으로 이어지는 시나리오 기반의 기후변화에 대한 낙동강 유역의 유출 분석은 기후변화 연구에 기술적 방법론의 제시와 함께 앞으로 타 유역에의 적용을 통하여 보다 정량적이고 신뢰성 있는 전국 단위의 기후변화에 따른 유출 분석연구의 기초가 될 수 있을 것이라 기대한다.

• Journal of Wetlands Research
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• v.20 no.3
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• pp.210-218
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• 2018

It is very important to analyze water balance in the mountain wetland for the sustainable management of the wetland. In this study, the SWAT model was used to analyze the water balance of Janggun wetland located in Geumjeong mountain of Gyungnam province, Korea. The data such as rainfall and water level measured in Janggun wetland were used for water balance analysis and from the analysis we have known that the rainfall of 10mm within 8 days is required for maintaining an appropriate water level in Janggun wetland. Also, water balance analysis in the wetland for the period of 2009 to 2017 was performed by using hydro-meteorological data obtained from Yangsan weather station which is located around Janggun wetland. From the analysis results, we have known that the amount of rainfall was relatively small in 2010, 2012 and 2015 and water shortage was occurred in the wetland. Especially, water shortage was occurred during the summer that we had intensive rainfall for very short time and faster removal of the runoff from the wetland. Therefore, we may need extend water courses from a wetland watershed to the wetland for preventing land-forming of the wetland and also store water by banking up the wetland for preventing the decrease of water level in the wetland.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.295-295
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• 2021

수자원 관리 및 계획 수립에 있어 강우 유출 분석은 가장 중요하며, 기본적인 분석이다. 기존의 강우 유출 분석은 일반적으로 수문 모형을 이용한다. 강우 유출 분석은 강수와 증발산 과정, 즉 물순환에 있어 복잡한 상호 작용을 고려해야한다. 본 연구에서는 기존의 수문 모형과 데이터간의 관계를 포착할 수 있는 딥러닝 기법을 이용한 강우 유출분석 수행하였다. 우리나라의 유역 중, 비교적 풍부한 수문데이터를 보유하고 있는 IHP (International Hydrological Program)의 청미천 유역을 연구대상지역으로 연구를 수행하였다. 수문 모형으로는 SWAT (Soil and Water Assessment Tool)을 이용하였으며, 딥러닝 기법은 시계열 분석에 있어 주로 사용되는 RNN(Recurrent Neural Network) 중 LSTM (Long Short-Term Memory) 네트워크를 이용하였다. 분석결과 수문 모형의 성능 지표인 상관계수와 NSE (Nash-Sutcliffe Efficiency)는 LSTM 네트워크에서 더 높은 성능을 확인 할 수 있었다. 일반적으로 LSTM 네트워크는 보정 기간이 길수록 더욱 좋은 성능을 나타낸다. 즉, 과거 수문데이터가 충분히 확보된 유역에서 LSTM 네트워크와 같은 데이터 기반 모델은 다양한 지형 및 기상데이터를 필요하는 수문 모델보다 유용할 것이라 사료된다.

• Journal of Korea Water Resources Association
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• v.50 no.10
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• pp.703-714
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• 2017

This paper analyzes the impact of two climate change scenarios on flow rate and water quality of the Yongdam Dam and its basin using CE-QUAL-W2 and SWAT, respectively. Under RCP 4.5 and RCP 8.5 scenarios by IPCC, simulations were performed for 2016~2095, and the results were rearranged into three separate periods; 2016~2035, 2036~2065 and 2066~2095. Also, the result of each year was divided as dry season (May~Oct) and wet season (Nov~Apr) to account for rainfall effect. For total simulation period, arithmetic average of flow rate and TSS (Total Suspended Solid) and TP (Total Phosphorus) were greater for RCP 4.5 than those of RCP 8.5, whereas TN (Total Nitrogen) showed contrary results. However, when averaged within three periods and rainfall conditions the tendencies were different from each other. As the scenarios went on, the number of rainfall days has decreased and the rainfall intensities have increased. These resulted in waste load discharge from the basin being decreased during the dry period and it being increased in the wet period. The results of SWAT model were used as boundary conditions of CE-QUAL-W2 model to predict water level and water quality changes in the Yongdam Dam. TSS and TP tend to increase during summer periods when rainfalls are higher, while TN shows the opposite pattern due to its weak absorption to particulate materials. Therefore, the climate change impact must be carefully analyzed when temporal and spatial conditions of study area are considered, and water quantity and water quality management alternatives must be case specific.