• Journal of Korea Water Resources Association
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• v.51 no.spc
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• pp.1161-1169
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• 2018

In this study, a new methodology was proposed to evaluate the flood vulnerability of river levee and to investigate the effect on the levee where the water level changes according to climate change. The stability of levee against seepage was evaluated using SEEP/W model which is two-dimensional groundwater infiltration model. In addition to the infiltration behavior, it is necessary to analyze the vulnerability of the embankment considering the environmental conditions of the river due to climate change. In this study, the levee flood vulnerability index (LFVI) was newly developed by deriving the factors necessary for the analysis of the levee vulnerability. The size of river levee was investigated by selecting the target area. The selected levees were classified into upstream part, midstream part and downstream part at the nearside of Seoul in the Han river, and the safety factor of the levee was analyzed by applying the design flood level of the levee. The safety ratio of the levee was analyzed by applying the design flood level considering the current flood level and the scenario of climate change RCP8.5. The degree of change resulting from climate change was identified for each factor that forms the levee flood vulnerability index. By using the levee flood vulnerability index value utilizing these factors comprehensively, it was finally possible to estimate the vulnerability of levee due to climate change.

• Journal of Korean Society on Water Environment
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• v.38 no.1
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• pp.19-30
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• 2022

Climate change has increased the average air temperature. Rising air temperature are absorbed by water bodies, leading to increasing water temperature. Increased water temperature will cause eutrophication and excess algal growth, which will reduce water quality. In this study, long-term trends of air and water temperatures in the Han-river basin over the period of 1997-2020 were discussed to assess the impacts of climate change. Future (~2100s) levels of air temperature were predicted based on the climate change scenarios (Representative concentration pathway (RCP) 2.6, 4.5, 6.0, and 8.5). The results showed that air and water temperatures rose at an average rate of 0.027℃ year^-1 and 0.038℃ year^-1 respectively, over the past 24 years (1997 to 2020). Future air temperatures under RCP 2.6, 4.5, 6.0, and 8.5 increased up to 0.32℃ 1.18℃, 2.14℃, and 3.51℃, respectively. An increasing water temperature could dissolve more minerals from the surrounding rock and will therefore have a higher electrical conductivity. It is the opposite when considering a gas, such as oxygen, dissolved in the water. Water temperature also governs the kinds of organisms that can live in rivers and lakes. Fish, insects, zooplankton, phytoplankton, and other aquatic species all have a preferred temperature range. As temperatures get too far above or below this preferred range, the number of individuals of the species decreases until finally there are none. Therefore, changes of water temperature that are induced by climate change have important implications on water supplies, water quality, and aquatic ecosystems of a watershed.

• Korean Journal of Agricultural and Forest Meteorology
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• v.24 no.4
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• pp.275-284
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• 2022

Changes in air temperature, CO₂ concentration and precipitation due to climate change are expected to have a significant impact on soybean productivity. This study was conducted to evaluate the climate change impact on growth and development of determinate soybean cultivar in the southern parts of Korea. The high temperature during vegetative period, which does not accompany the increase of CO₂ concentration, increased the canopy photosynthetic rate in soybean, but after flowering, the high temperature above the optimal ranges interrupts the photosynthetic metabolism. In yield and yield components, high temperature reduced both the pod and seed number and single seed weight, resulting in a reduction of total seed yield. On the other hand, the increase in CO₂ concentration dramatically increased the canopy photosynthetic rate over the whole growth period. In addition, high CO₂ concentration increased the number of pods and seeds, which had a positive effect on total seed yield. Under concurrent elevation of air temperature and CO₂ concentration, canopy photosynthesis increased significantly, but enhanced canopy photosynthesis did not lead to an increase in soybean seed yield. The increase in biomass and branch by enhanced canopy photosynthesis seems to be attributed to an increase in the total number of pods and seeds per plant, which compensates for the negative effects of high temperature on pod development. However, Single seed weight tended to decrease rapidly by high temperature, regardless of CO₂ concentration level. Elevated CO₂ concentration did not compensate for the poor distribution of assimilations from source to sink caused by high temperature. These results show that the damage of future soybean yield and quality is closely related to high temperature stress during seed filling period.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.3
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• pp.333-342
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• 2022

Due to climate change, increased heavy rainfalls result in flood damage every year. To investigate the storm-runoff reduction effects of Low Impact Development (LID), this study performed runoff analyses using the U.S. Environmental Protection Agency (EPA) Storm Water Management Model (SWMM) for past and future representative storm events of the Yongdu Rainwater Pumping Station basin. As a result, the infiltration loss for representative future rainfalls increased by 3.17 %, and the surface runoff and peak runoff rate increased significantly by 32.50 %, and 128.77 %, respectively. To reduce the increased surface runoff and peak runoff rates, this study investigated the applicability of LID approaches, including a permeable pavement, green roof, and rain garden, by adjusting the LID parameters and the ratio of installation area. We identified the ranges of LID parameters that decreased peak runoff rate and surface runoff, and increased infiltration. In addition, when the application ratio of permeable pavement, green roof, and rain garden was 2:1:3, best performance was attained, leading to a reduction of peak runoff of 26.85 %, infiltration loss 12.01 %, surface runoff 15.11 %, and storage 509.47 %. Based on analyzing the effect of storm runoff reductions for various return periods, it was found that as the return period increased, the proportion of peak runoff and surface runoff increased and the proportion of infiltration loss and storage decreased.

• Journal of Korea Water Resources Association
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• v.56 no.6
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• pp.393-402
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• 2023

Drought, which has been increasing in frequency and magnitude due to recent abnormal weather events, poses severe challenges in various sectors. To address this issue, it is important to develop technologies for drought monitoring, forecasting, and response in order to implement effective measures and safeguard the ecological health of aquatic systems during water scarcity caused by drought. This study aimed to predict water quality fluctuations during drought periods by integrating the watershed model HSPF and the water quality model QUAL-MEV. The researchers examined the SPI and RCP 4.5 scenarios, and analyzed water quality changes based on flow rates by simulating them using the HSPF and QUAL-MEV models. The study found a strong correlation between water flow and water quality during the low flow. However, the relationship between precipitation and water quality was deemed insignificant. Moreover, the flow rate and SPI6 exhibited different trends. It was observed that the relationship with the mid- to long-term drought index was not significant when predicting changes in water quality influenced by drought. Therefore, to accurately assess the impact of drought on water quality, it is necessary to employ a short-term drought index and develop an evaluation method that considers fluctuations in flow.

• Journal of Korean Society of Rural Planning
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• v.22 no.4
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• pp.71-80
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• 2016

Meanwhile, reference evapotranspiration(ET0) is important information for agricultural management including irrigation planning and drought assessment, the database of reference evapotranspiration for future periods was rarely constructed especially at districts unit over the country. The Coupled Model Intercomparison Project Phase 5 (CMIP5) provides several meteorological data such as precipitation, average temperature, humidity, wind speed, and radiation for long-term future period at daily time-scale. This study aimed to build a database for reference evapotranspiration using the climate forecasts at high resolution (the outputs of HadGEM3-RA provided by Korea Meteorological Administration (KMA)). To estimate reference evapotranspiration, we implemented four different models such as FAO Modified Penman, FAO Penman-Monteith, FAO Blaney-Criddle, and Thornthwaite. The suggested database system has an open architecture so that user could add other models into the database. The database contains 5,050 regions' data for each four models and four Representative Concentration Pathways (RCP) climate change scenarios. The developed database system provides selecting features by which the database users could extract specific region and period data.

• Journal of Korean Society of Rural Planning
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• v.26 no.1
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• pp.1-12
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• 2020

다수의 국가에서 농촌이 쇠퇴하는 현상을 확인할 수 있으며, 특히 경작 포기지의 비율이 빠른 속도로 향상되고 있다. 일본에서 경작 포기지의 증가는 농작물의 국내 자급률 감소, 농지의 중요한 기능 중 하나인 자연재해 방지 기능의 상실, 그리고 농촌 지역사회가 계승해 오던 다양한 형태의 무형적 자산의 소실 등을 야기하였다. 농지와 농촌 지역사회 활동의 보존은 지속가능한 개발을 위해 필수적인 요소이다. 생태계 서비스는 농지가 보유한 기능 중 하나이며, 일본의 중산간 지역 직불제는 농지의 보전과 농촌 지역사회 활동을 지원하여 생태계 서비스 보존 및 유지에 일조하기에 생태계 서비스에 대한 지불(PES)이라 볼 수 있다. 본 연구의 목표는 중산간지역 직접지불제도의 혜택을 받는 지역과 RCP8.5 시나리오 하에서의 자연재해 피해액 간의 관계를 파악하여 직불제의 효율성을 간접적으로 검증하는 것이다. 본 연구의 대상지는 일본 홋카이도의 농지 전체이며, 2005년, 2010년, 2015년의 강우량 예측 패널 데이터와 농업 센서스 패널 데이터를 이용하여 한계효과를 구하여 분석하였다. 분석 결과, 중산간지역 직불제 해당지역이면서 농촌 지역사회 활동이 활발할수록 자연재해 피해액이 적었다. 따라서 특히 중산간지역 직불제 해당지역일수록 재해피해 감소를 위해 농촌 지역사회 활동이 필수적으로 요구된다. 본 연구의 의의는 중산간지역 직불제의 효율성을 자연재해 피해액을 통해 검증한 데 있으며, 향후 직불제의 효율성에 대한 논의에 기초자료로 활용될 수 있다.

• Journal of The Korean Society of Agricultural Engineers
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• v.60 no.5
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• pp.149-162
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• 2018

It is necessary to select the appropriate global climate model (GCM) to take into account the impacts of climate change on integrated water management. The objective of this study was to develop the selection technique of representative GCMs for uncertainty in climate change scenario. The selection technique which set priorities of GCMs consisted of two steps. First step was evaluating original GCMs by comparing with grid-based observational data for the past period. Second step was evaluating whether the statistical downscaled data reflect characteristics for the historical period. Spatial Disaggregation Quantile Delta Mapping (SDQDM), one of the statistical downscaling methods, was used for the downscaled data. The way of evaluating was using explanatory power, the stepwise ratio of the entire GCMs by Expert Team on Climate Change Detection and Indices (ETCCDI) basis. We used 26 GCMs based on CMIP5 data. The Representative Concentration Pathways (RCP) 4.5 and 8.5 scenarios were selected for this study. The period for evaluating reproducibility of historical period was 30 years from 1976 to 2005. Precipitation, maximum temperature, and minimum temperature were used as collected climate variables. As a result, we suggested representative 13 GCMs among 26 GCMs by using the selection technique developed in this research. Furthermore, this result can be utilized as a basic data for integrated water management.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.43-43
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• 2018

수생태계는 다른 여러 생태계 중에서 가장 위험에 처해있으며, 기후변화로 인한 수온, 수문 수질의 변화는 수생태계와 담수 생물다양성에 가장 큰 영향을 미치는 요인 중 하나이다. 본 연구에서는 생물 생태학적으로 변화하는 세계적인 물 관리 패러다임에 따라 한강유역에서의 미래 수생태계 평가를 수행하였다. 본 연구의 목적은 수생태 건강성 관측자료와 수질자료, SWAT 모형을 이용하여 미래 기후변화에 따른 한강유역의 수생태를 평가하는 것이다. 본 연구에서 선정한 수생태계 건강성 조사자료로 국립환경과학원에서 8년간(2008년~2015년) 봄과 가을 2차례에 걸쳐 모니터링 한 부착돌말류(TDI), 저서형 대형무척추동물(BMI), 어류(FAI)에 대한 수생태 등급자료 및 해당 지점에 대한 수온 및 수질자료를 이용하였다. 수집한 결과를 DB(T-N, $NH_4N$, $NO_3N$, T-P, PO4P)에 대한 수생태 등급의 상관성을 분석하고 수온 수질인자에 따른 수생태 등급을 나타내어 미래 기후변화에 따른 수생태 건강성 평가 및 예측을 실시하고자 하였다. Soil and Water Assessment Tool (SWAT) 모형은 유역의 신뢰성 있는 유역 수문, 수질 모의 및 기후변화 영향평가를 위하여 활용되었다. SWAT 모형을 이용하여 한강유역의 다목적댐(3개), 발전용댐(1개), 다기능보(3개) 운영을 고려하였고, 237개의 표준유역으로 분할한 뒤 수문 및 수질 모의를 수행하였다. 모형의 적용성 평가를 위해 댐 및 보의 유입량, 증발산량, 토양수분, 지하수위, SS, T-N, T-P에 대하여 보정(2005~2009) 및 검증(2010~2015)을 수행하였다. 기후변화에 따른 수문, 수질 및 수생태 평가를 위해 기상청의 HadGEM3-RA RCP 4.5와 8.5 시나리오를 적용하였으며, 기준년(1975-2005)년에 대해 2020s(2010-2039), 2050s(2040-2069), 2080s(2070-2099)의 수생태를 평가하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.521-521
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• 2017

본 연구는 기후변화가 만경강에 서식하는 어류 서식처에 미치는 영향을 분석하고자 하였다. 기후변화 영향에 따른 수문자료는 RCP 8.5 기후변화시나리오 결과에 기반하여 SLURP 분포형 모델을 이용하여 일 유출량을 도출하였다. 기후변화 전후의 일 유출량 자료는 수문변화지표(indicator of Hydrologic Alteration, IHA) 통계분석모형을 이용하여 유출량의 규모, 빈도, 시기, 기간, 변화율 등 유황특성을 반영한 5가지의 환경흐름요소(Environmental Flow Components, EFC)로 나타냈다. 환경흐름요소는 수문기간 동안의 유황을 극히 낮은 흐름(Extreme low flow), 낮은 흐름(Low flow), 높은 흐름 펄스(High flow pulse), 작은 홍수(Small floods), 커다란 홍수(Large floods) 등 5가지의 스펙트럼 형태로 나타낼 수 있다. 어류의 물리서식처 모의를 위한 대상어종은 환경부 멸종위기 야생동식물 1급으로 지정 및 보호되고 있고 과거 만경강 봉동 일대에서 출현하였던 감돌고기를 선정하였다. 감돌고기의 서식처 적합도(HSI)는 과거 모니터링 결과 및 문헌자료 근거로 생애주기별(산란기, 성장기, 성어기)로 구분하여 나타내었고, River2D 모형에 적용하였다. 분석결과 생애주기별로는 기후변화 영향 후 산란기의 감돌고기의 서식처가중가용면적은 24.1% 증가, 성장기와 성어기의 가중가용면적은 각각 3.3%, 7.3%로 감소하는 것으로 예측되었다. 극한조건에서 서식처가중가용면적의 크기는 높은 흐름 펄스, 작은 홍수, 커다란 홍수, 극히 낮은 흐름 순으로 나타났다. 기후변화 영향으로 인한 가중가용면적의 변화는 작은 홍수를 제외하고 미래에는 감소하는 것으로 나타났으며, 특히 극히 낮은 흐름, 커다란 홍수의 경우 빈도와 기간을 고려할 때 실질적인 가중가용면적은 더욱 악화될 것으로 예측되었다. 이러한 결과를 바탕으로 기후변화 영향으로 인한 만경강 유역의 미래서식처 요건은 악화될 것으로 예상되며 멸종위기종인 감돌고기의 서식처 확보방안의 제시가 필요할 것으로 판단된다.