• Journal of Soil and Groundwater Environment
• /
• v.21 no.6
• /
• pp.22-35
• /
• 2016

Global climate change could have an impact on hydrological process of a watershed and result in problems with future water supply by influencing the recharge process into the aquifer. This study aims to assess the change of groundwater recharge rate by climate change and to predict the sustainability of groundwater resource in Pyoseon watershed, Jeju Island. For the prediction, the groundwater recharge rate of the study area was estimated based on two future climate scenarios (RCP 4.5, RCP 8.5) by using the Soil Water Balance (SWB) computer code. The calculated groundwater recharge rate was used for groundwater flow simulation and the change of groundwater level according to the climate change was predicted using a numerical simulation program (FEFLOW 6.1). The average recharge rate from 2020 to 2100 was predicted to decrease by 10~12% compared to the current situation (1990~2015) while the evapotranspiration and the direct runoff rate would increase at both climate scenarios. The decrease in groundwater recharge rate due to the climate change results in the decline of groundwater level. In some monitoring wells, the predicted mean groundwater level at the year of the lowest water level was estimated to be lower by 60~70 m than the current situation. The model also predicted that temporal fluctuation of groundwater recharge, runoff and evapotranspiration would become more severe as a result of climate change, making the sustainable management of water resource more challenging in the future. Our study results demonstrate that the future availability of water resources highly depends on climate change. Thus, intensive studies on climate changes and water resources should be performed based on the sufficient data, advanced climate change scenarios, and improved modeling methodology.

• Journal of Korea Water Resources Association
• /
• v.46 no.6
• /
• pp.683-696
• /
• 2013

Recent inundation damage has frequently occurred due to heavy rainfall in urban area, because rainfall has locally occurred exceeding the capability of a flood control plan by the exiting design rainfall from the data of Seoul weather station. Accordingly the objective of this study is to predict new design rainfall in order to make a future flood control plan considering climate change. In this study, for considering spatial characteristics of rainfall in urban area, data of AWS was used and for retaining insufficient rainfall data, WGR model was estimated the application of target area. The results were compared with the observation data and consequently show reasonable results. In addition, to prepare for climate change, design rainfall was calculated by applying for various climate scenarios and the result would be used in order to establish future flood control plan.

• Journal of Ecology and Environment
• /
• v.43 no.4
• /
• pp.352-363
• /
• 2019

Background: Invasive plant species are considered a major threat to biodiversity, ecosystem functioning, and human wellbeing worldwide. Climatically suitable ranges for invasive plant species are expected to expand due to future climate change. The identification of current invasions and potential range expansion of invasive plant species is required to plan for the management of these species. Here, we predicted climatically suitable habitats for 11 invasive plant species and calculated the potential species richness and their range expansions in different provinces of the Republic of Korea (ROK) under current and future climate change scenarios (RCP 4.5 and RCP 8.5) using the maximum entropy (MaxEnt) modeling approach. Results: Based on the model predictions, areas of climatically suitable habitats for 90.9% of the invasive plant species are expected to retain current ecological niches and expand to include additional climatically suitable areas under future climate change scenarios. Species richness is predicted to be relatively high in the provinces of the western and southern regions (e.g., Jeollanam, Jeollabuk, and Chungcheongnam) under current climatic conditions. However, under future climates, richness in the provinces of the northern, eastern, and southeastern regions (e.g., Seoul, Incheon, Gyeonggi, Gyeongsangnam, Degue, Busan, and Ulsan) is estimated to increase up to 292%, 390.75%, and 468.06% by 2030, 2050, and 2080, respectively, compared with the current richness. Conclusions: Our study revealed that the rates of introduction and dispersion of invasive plant species from the western and southern coasts are relatively high and are expanding across the ROK through different modes of dispersion. The negative impacts on biodiversity, ecosystem dynamics, and economy caused by invasive plant species will be high if preventive and eradication measures are not employed immediately. Thus, this study will be helpful to policymakers for the management of invasive plant species and the conservation of biodiversity.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2016.05a
• /
• pp.572-572
• /
• 2016

청미천 유역은 다양한 수계로 구성된 대유역에 해당되며 농업 및 공업활동에 따른 오염원을 가진다. 본 연구에서는 오염원 중 비점오염원이 가지는 특성을 기후변화 시나리오에 따라 모의 및 분석한다. 비점오염원의 모의를 위해서는 SWAT 모형이 이용된다. 기후변화 시나리오로는 RCP4.5 및 RCP8.5 시나리오가 적용된다. SWAT 모형은 유역 모의를 위한 모형으로 대규모의 복잡한 유역에서의 장기간 모의를 수행할 수 있으며 다양한 조건의 토양 및 토지이용 상태를 고려할 수 있는 장점을 가진다. 본 연구에서는 강유-유출모형과 수질모형 등을 GIS와 연계한 호환모형을 이용하며 유출에 따른 비점오염원의 거동을 해석하고자 한다. SWAT 모형을 이용한 모의를 위해 필요한 매개변수는 관측소 현황, 강우, 기온, 습도, 일사량, 풍속 등이다. 이중 일사량에 대한 정보를 가정하여 본 연구를 수행하였고 나머지 매개변수는 청미천 유역의 특성치를 조사하여 입력하였다. 청미천 유역의 수질 오염원에 대한 기여도를 분석하기 위해서 시설용량이 일정 크기 이상인 하수처리장을 조사하였고, 이에 대한 정보가 모의시 검토되었다. 청미천 유역 전체 오염원에 대한 점오원의 비율을 검토한 결과 홍수기에 점오염원의 영향이 낮다는 점을 확인할 수 있다. 이는 홍수기에 불특정 지점에서 유출되는 비점오염원의 기여도가 큰 것으로 이해할 수 있다. 하지만 소규모 산업단지의 배출량 등에 대한 자료가 보완될 때 보다 신뢰성 있는 모의 결과를 얻을 수 있을 것으로 판단된다. 총질소와 총인의 경우에도 하계 홍수기에 크게 증가하는 사실을 확인할 수 있으며 부유물질의 경우는 그 변동 폭이 다른 항목에 비해 크게 나타나며 9월에도 증가하는 경향을 나타낸다. 본 연구를 보다 고도화하기 위해서는 다양한 알고리즘을 통해 매개변수를 보정하는 과정이 필요하며 점오염원을 포함하여 다양한 오염원에 대한 정확한 정보가 구축되는 과정 역시 중요하다.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2018.05a
• /
• pp.145-145
• /
• 2018

Small islands rely heavily on groundwater resources in addition to rainwater as the source of freshwater since surface water bodies are often absent. The groundwater resources are vulnerable to sea level rise, coastal flooding, saltwater intrusion, irregular pattern of precipitation resulting in long droughts and flash floods. Increase in population increases the demand for the limited groundwater resources, thus aggravating the problem. In this study, the effects of climate change on Tongatapu Island, Kingdom of Tonga, a small island in Pacific Ocean, are investigated using a sharp interface transient groundwater flow model. Twenty nine downscaled General Circulation Model(GCM) predictions are input to a water balance model to estimate the groundwater recharge. The temporal variation in recharge is predicted over the period of 2010 to 2099. A set of GCM models are selected to represent the ensemble of 29 models based on cumulative recharge at the end of the century. This set of GCM model predictions are then used to simulate a total of six climate scenarios, three each (2010-2039, 2040-2069, and 2070-2099) under RCP 4.5 and RCP 8.5. The impacts of predicted climate change on groundwater resources is evaluated in terms of freshwater volume changes and saltwater ratios in pumping wells compared to present conditions. Though the cumulative recharge at the end of the century indicates a wetter climate compared to the present conditions the large variability in rainfall pattern results in frequent periods of groundwater drought leading to saltwater intrusion in pumping wells. Thus for sustaining the limited groundwater resources in small islands, implementation of timely assessment and management practices are of utmost importance.

• Journal of Climate Change Research
• /
• v.9 no.2
• /
• pp.143-156
• /
• 2018

Evapotranspiration is a key element in designing and operating agricultural hydraulic structures. The profound effect of climate change to local agro-hydrological systems makes it inevitable to study the potential variability in evapotranspiration rate in order to develop policies on future agricultural water management as well as to evaluate changes in agricultural environment. The APEX-Paddy model was used to simulate local evapotranspiration responses to climate change scenarios. Nine Global Climate Models(GCMs) downscaled using a non-parametric quantile mapping method and a Multi?Model Ensemble method(MME) were used for an uncertainty analysis in the climate scenarios. Results indicate that APEX-Paddy and the downscaled 9 GCMs reproduce evapotranspiration accurately for historical period(1976~2005). For future periods, simulated evapotranspiration rate under the RCP 4.5 scenario showed increasing trends by -1.31%, 2.21% and 4.32% for 2025s(2011~2040), 2055s(2041~2070) and 2085s(2071~2100), respectively, compared with historical(441.6 mm). Similar trends were found under the RCP 8.5 scenario with the rates of increase by 0.00%, 4.67%, and 7.41% for the near?term, mid?term, and long?term periods. Monthly evapotranspiration was predicted to be the highest in August, July was the month having a strong upward trend while. September and October were the months showing downward trends in evapotranspiration are mainly resulted from the shortening of the growth period of paddy rice due to temperature increase and stomatal closer as ambient $CO_2$ concentration increases in the future.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2023.05a
• /
• pp.314-314
• /
• 2023

Extreme climate events can have a large impact on human life by hampering social, environmental, and economic development. Global circulation models (GCMs) are the widely used numerical models to understand the anticipated future climate change. However, different GCMs can project different future climates due to structural differences, varying initial boundary conditions and assumptions about the physical phenomena. The multi-model ensemble (MME) approach can improve the uncertainties associated with the different GCM outcomes. In this study, a comprehensive rating metric was used to select the best-performing GCMs out of 11 CMIP5 and 13 CMIP6 GCMs, according to their skills in terms of four temporal and five spatial performance indices, in replicating the 21 extreme climate indices during the baseline (1975-2017) in South Korea. The MME data were derived by averaging the simulations from all selected GCMs and three top-ranked GCMs. The random forest (RF) algorithm was also used to derive the MME data from the three top-ranked GCMs. The RF-derived MME data of the three top-ranked GCMs showed the highest performance in simulating the baseline extreme climate which was subsequently used to project the future extreme climate indices under both the representative concentration pathway (RCP) and the socioeconomic concentration pathway scenarios (SSP). The extreme cold and warming indices had declining and increasing trends, respectively, and most extreme precipitation indices had increasing trends over the period 2031-2100. Compared to all scenarios, RCP8.5 showed drastic changes in future extreme climate indices. The coasts in the east, south and west had stronger warming than the rest of the country, while mountain areas in the north experienced more extreme cold. While extreme cold climatology gradually declined from north to south, extreme warming climatology continuously grew from coastal to inland and northern mountainous regions. The results showed that the socially, environmentally and agriculturally important regions of South Korea were at increased risk of facing the detrimental impacts of extreme climatology.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2021.06a
• /
• pp.143-143
• /
• 2021

Climate change indicators, mainly frequent drought which has happened since the drought of 1994, 1995, and 2012 causing the devastating effect to the agricultural sector, and could be more disruptive given the context of climate change indicators by increasing the temperature and more variable and extreme precipitation. Changes in frequency, duration, and severity of droughts will have enormous impacts on agriculture production and water management. Since both the possibility of drought manifestation and substantial yield losses, we are propositioning an integrated method for evaluating past and future agriculture drought hazards that depend on models' simulations in the Hung-up watershed. to discuss the question of how climate change might influence the impact of extreme agriculture drought by assessing the potential changes in temporal trends of agriculture drought. we will calculate the temporal trends of future drought through drought indices Standardized Precipitation Evapotranspiration Index, Standardized Precipitation Index, and Palmer drought severity index by using observed data of (1991-2020) from Wonju meteorological station and projected climate change scenarios (2021-2100) of the Representative Concentration Pathways models (RCPs). expected results confirmed the frequency of extreme agricultural drought in the future projected to increase under all studied RCPs. at present 100 years drought is anticipated to happen since the result showing under RCP2.6 will occur every 24 years, RCP4.5 every 17 years, and RCPs8.5 every 7 years, and it would be double in the largest warming scenarios. On another side, the result shows unsupportable water management, could cause devastating consequences in both food production and water supply in extreme events. Because significant increases in the drought magnitude and severity like to be initiate at different time scales for each drought indicator. Based on the expected result that the evaluating the impacts of extreme agricultural droughts and recession could be used for the development of proactive drought risk management, policies for future water balance, prioritize sustainable strengthening and mitigation strategies.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2022.05a
• /
• pp.299-299
• /
• 2022

수문학적 가뭄 발생의 직접적 영향은 강수부족량이나, 다양한 사회경제적 인자들은 수문학적 가뭄에 간접적으로 영향을 미치고 있다. 물관리 선진기관에서는 인간의 활동 및 물관리 방식에 따라 수문학적 가뭄을 심화시키거나 완화시킬 수 있음을 인지하고, 인간의 물사용이 가뭄에 미치는 영향을 평가하기 위한 다양한 연구가 이루어지고 있다. 본 연구에서는 강수량 및 미래의 인구변화에 따른 수문학적 가뭄의 영향의 정도를 판단함으로써, 인간의 활동이 가뭄에 미치는 영향을 정량적으로 제시하고자 한다. 충정북도 시군지역을 대상지역으로 선정하였으며, 시군 장래인구 추정값을 미래 인구자료로, 미래 유출량이 산정되어 제공되는 RCP 4.5와 RCP 8.5시나리오를 활용하여 미래 가뭄상황 예측하였다. 강수량 및 인구변화가 수문학적 가뭄에 미치는 영향 평가를 위하여 코플라함수 기반의 베이지안 네트워크 모형이 활용하였다. 베이지안 네트워크는 강수량, 인구밀도, 수문학적 가뭄사이의 관계 도출을 위하여 활용되었으며, 베이지안 네트워크 내의 결합확률의 산정을 위하여 코플라 함수가 활용되었다. 미래의 강수량 및 인구밀도의 변화에 따른 수문학적 가뭄의 영향 관계를 분석한 결과는 다음과 같다. 강수량이 인구밀도보다 수문학적 가뭄의 발생에 영향을 미치며, 약 0.2~0.3 정도 발생확률이 크게 산정되었다. 두 인자를 동시에 고려할 경우, 강수량이 적고, 인구밀도가 높아지는 조건(F(강수량)=0.1, F(인구밀도)=0.9)에서는 조건부 CDF 변화율이 크게 나타나, 곧 수문학적 가뭄의 위험성이 높음을 확인할 수 있었다. 인구밀도는 수문학적 가뭄의 발생 위험성을 높이 알려져 있으나, 정량적으로 그 값을 제시한 연구 사례는 찾기 어렵다. 이에 따라 본 연구에서는 가뭄의 영향정도를 정량적으로 표현하였으며, 한 인자만의 영향이 아닌 두 개 이상의 인자들의 복합적인 영향 정도를 제시함으로써 수치적인 비교가 가능하게 하였다. 미래 추정 인자가 인구자료가 한정적이라 인구 자료만을 활용하여 수문학적 가뭄에 미치는 영향을 분석하였으나, 다른 사회경제적 지표를 활용하여 미래 변화에 따른 미래 수문학적 가뭄의 영향 정도의 비교 및 분석 결과를 바탕으로 가뭄 대응 우선순위 선정을 위한 연구자료로 활용 가능할 것으로 사료된다.

• Journal of Environmental Impact Assessment
• /
• v.26 no.5
• /
• pp.291-302
• /
• 2017

The research was carried out in order to find climate factors which determine the distribution of Eurya japonica, and the potential habitats (PHs) under the current climate and climate change scenario by using species distribution models (SDMs). Four climate factors; the warmth index (WI), the minimum temperature of the coldest month (TMC), summer precipitation (PRS), and winter precipitaion (PRW) : were used as independent variables for the model. Seventeen general circulation models under RCP (Representative concentration pathway) 8.5 scenarios were used as future climate scenarios for the 2050s (2040~2069) and 2080s (2070~2099). Highly accurate SDMs were obtained for E. japonica. The model of distribution for E. japonica constructed by SDMs showed that minimum temperature of the coldest month (TMC) is a major climate factor in determining the distribution of E. japonica. The area above the $-5.7^{\circ}C$ of TMC revealed high occurrence probability of the E. japonica. Future PHs for E. japonica were projected to increase respectively by 2.5 times, 3.4 times of current PHs under 2050s and 2080s. It is expected that the potential of E. japonica habitats is expanded gradually. E. japonica is applicable as indicator species for monitoring in the Korean Peninsula. E. japonica is necessary to be monitored of potential habitats.