• Economic and Environmental Geology
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• v.55 no.6
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• pp.563-570
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• 2022

This study was objected to show the complexity of groundwater flow system in a site-scale area as a design parameter of the groundwater monitoring network for early detection of pollutant leakage from a potential source of groundwater contamination (e.g., storage tank). Around the tanks, three monitoring wells were installed at about 22~25 m deep and groundwater level and temperature had been monitored for 22 months by 2-minute interval, and then compared with precipitation and temperature data from nearby weather station. Annual variation of groundwater level and its response to precipitation event, variation of groundwater temperature and delayed response to that of atmospheric temperature indicate the complexity of groundwater flow and flow paths even in the relatively small area. Thus, groundwater monitoring network for early detection of contaminant leakage should be designed with full consideration of the complexity of groundwater flow system, identified from the detailed hydrogeological investigation of the site.

• Journal of the Korean earth science society
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• v.43 no.1
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• pp.30-40
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• 2022

Wildfires, which occur sporadically and irregularly worldwide, are distinct natural disturbances in combustible vegetation areas, important parts of the global carbon cycle, and natural disasters that cause severe public emergencies. While many previous studies have investigated the variability and changes in wildfires globally based on fire emissions, burned areas, and fire weather indices, studies on East Asia are still limited. Here, we explore the characteristics of variability and changes in wildfire danger over East Asia by analyzing the fire weather index for the 40 years-1981-2020. The first empirical orthogonal function (EOF) mode of fire weather index variability represents an increasing trend in wildfire danger over most parts of East Asia over the last 40 years, accounting for 29% of the total variance. The major contributor is an increase in the surface temperature in East Asia associated with global warming and multidecadal ocean variations. The effect of temperature was slightly offset by the increase in soil moisture. The second EOF mode exhibits considerable interannual variability associated with the El Nino-Southern Oscillation, accounting for 17% of the total variance. The increase (decrease) in precipitation in East Asia during El Nino (La Nina) increases (decreases) soil moisture, which in turn reduces (increases) wildfire danger. This dominant soil moisture effect was slightly offset by the temperature increase (decrease) during El Nino (La Nina). Improving the understanding of variability and changes in wildfire danger will have important implications for reducing social, economic, and ecological losses associated with wildfire occurrences.

• Korean Journal of Heritage: History & Science
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• v.53 no.1
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• pp.52-63
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• 2020

This study was conducted in order to evaluate the characteristics of air temperature fluctuation inside the Daegeumgul, Ondaldonggul, and Seongnyugul Caves, which are the most representative limestone caves in Korea, and also to assess the effects of air temperature on cave temperature. Temperature was measured hourly at three sites in Daegeumgul, Ondaldonggul, and Seongnyugul Caves from April 13 to June 25, 2019. Additionally, air temperature data for the areas around the caves was provided by the Meteorological Administration. Using this collected data, the basic statistical measure of fluctuation characteristics over time was ascertained, and time series analyses were performed. Wide variation of temperature was exhibited in the order of the cave entrance, the cave water inflow point, and the midpoint. Cave temperature was observed to increase gradually during the study period. There was a vast range in temperature at the Daegeumgul station located approximately 150 m outside the cave, but it remained nearly constant beyond the midpoint. Although the effect of air temperature was not significant due to the influence of visitors, the effect of air temperature on cave temperature gradually decreased from the entrance to the interior. At Ondaldonggul, there was a wide range in temperature recorded at the entrance due to the influence of air temperature, but it stayed almost constant in the interior. However, at the site where cave water flows into the cave, temperature was influenced by the cave water temperature. At Seongnyugul, there was a distinct fluctuation in temperature recorded at the cave entrance, while the middle of the cave remained nearly constant. Temperature fluctuated due to the air temperature at the entrance, while at the middle of the cave, measurements were expected to be affected to a greater extent by the lake water temperature than by the air temperature. However, this pattern was not observed. According to the time series analysis results, in all caves, fluctuations of air temperature affected cave temperature after approximately one hour. Cave size and structure, water presence, the entrance's size and shape, air flow, and visitor patterns can all influence cave temperature. Therefore, consideration of these factors is very important in the pursuit to clearly understand cave temperature characteristics.

• Journal of the Korean Association of Geographic Information Studies
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• v.19 no.4
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• pp.199-217
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• 2016

Influences of seasonal warming and cooling rates on the annual temperature patterns were analyzed based on the meteorological data from 13 weather stations in Busan Metropolitan Area(BMA), Korea during 1997~2014. BMA daily temperature time-series was generalized by Fourier analysis, which mathematically summarizes complex, regularly sampled periodic records, such as air temperature, into a limited number of major wave components. Local monthly warming and cooling rates of BMA were strongly governed by the ocean effect within the city. March($1.121^{\circ}C/month$) and November(-$1.564^{\circ}C/month$) were the two months, when the most rapid warming and cooling rates were observed, respectively during the study period. Geographically, spring warming rates of inland increased more rapidly compared to coastal areas due to weaker ocean effect. As a result, the annual maximum temperature was reached earlier in a location, where the annual temperature range was larger, and therefore its July mean temperature and continentality were higher. Interannual analyses based on average temperature data of all weather stations also showed that the annual maximum temperature tended to occur earlier as the city's July mean temperature increased. Percent area of impervious surfaces, an indicator of urbanization, was another contributor to temperature change rates of the city. Annual mean temperature was positively correlated with percent area of impervious surfaces, and the variations of monthly warming and cooling rates also increased with percent area of impervious surfaces.

• Korean Journal of Agricultural and Forest Meteorology
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• v.11 no.4
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• pp.185-191
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• 2009

Few studies have attempted to analyze variations of daily maximum temperature in the summer whereas many studies have analyzed warming trends in other seasons with respect to greenhouse gases or urban heat islands. We analyzed daily maximum temperature data for the summer season (June to August) at 18 locations in South Korea from 1983 to 2007. Compared to the climatic normal (from 1971 to 2000), an average increase of $0.1^{\circ}C$ was found for the summer daily maximum temperature along with an increase of $0.61MJ\;m^{-2}$ in daily solar radiation. Approximately 65% of the annual variations of the summer daily maximum temperature could be explained by the solar radiance alone. Higher atmospheric transmittance due to lower aerosol concentration (especially of sulfur dioxide) is believed to have caused the recent increase in solar irradiance. Daily maximum temperature of the summer is expected to keep rising if the clean air activities are maintained in the future.

• Journal of Wetlands Research
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• v.23 no.4
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• pp.296-306
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• 2021

Elasticity is a statistical technique that interprets the changing pattern of another variable according to a change in one variable as a quantitative numerical value and provides more information than correlation analysis and is widely used in climate change research. In this study the elasticity was calculated and sensitivity analysis was performed using air temperature and water quality data of the major tributaries of the Nakdong River. In addition the confidence interval for the elasticity was calculated using the T-Test and the validity of the elasticity was examined. The strength of elasticity shows high strength in the order of summer>fall>spring>winter and the direction shows regional characteristics with both negative and positive elasticity. After performing hierarchical cluster analysis on monthly observation data they were classified into 5 clusters and the characteristics of each cluster were visually analyzed using a parallel coordinate graph. The direction and intensity of the air temperature elasticity show regional characteristics due to the relatively high population density and complex influencing factors such as sewage treatment plants, small-scale livestock houses and agricultural activities. In the case of TP it shows great regional variability according to the circulation of nutrients in the ecosystem caused by algae growth and death according to temperature changes. Since the air temperature elasticity of the major tributaries of the Nakdong River is over weak and is valid at the significance level of 5%, it was analyzed that there is a change in water quality according to the air temperature change.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.434-434
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• 2017

우리나라의 기후가 아열대 몬순기후로 변화가 이루어지고 있는 현재에 있어 과거의 강수패턴과 현재의 강수패턴은 많은 변화가 나타나고 있다. 우리가 일상생활에서 많이 사용되고 있는 계절의 변화를 나타내는 24절기의 경우 과거와 달리 기온이나 강수 등의 변화로 인해 절기의 구분이 상이한 경우가 많이 발생하고 있으며, 특히 농업에 있어 24절기를 기준으로 작물의 생육을 관리하는 인식이 기후변화로 인한 기온, 강수의 패턴이 과거와는 많은 차이가 발생하고 있다. 이러한 절기별 강수량의 변화는 농업용수의 계획에 있어 많은 영향을 미칠 것으로 판단된다. 본 연구에서는 우리나라의 관측소에서 관측된 기온, 강수를 24절기로 구분하여 과거와 현재의 변화정도를 분석하였다. 24절기의 강수량의 이동평균법을 이용하여 변동성을 분석한 결과에서는 서울, 대구, 부산의 경우 증가하였으며, 가장 많이 증가한 절기는 망종으로 서울의 경우 245%정도 증가된 것으로 분석되었으며, 전반적으로 120%이상 증가된 것으로 나타났다. 20년 이동평균 분석결과에서는 망종과 백로에서 120%이상 증가되는 것으로 나타났다.

• Journal of the Korean Geographical Society
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• v.42 no.3 s.120
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• pp.405-420
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• 2007

This study is intended to analyze and evaluate the effects of Seomjingang Dam and Soyanggang Dam Catchment on water circulation in order to examine water balance change of watershed by climate change. Obviously, air temperature and precipitation showed a gradually increasing trend for the past 30 years; evapotranspiration vary in areas and increasing annual average air temperature is not always proportional to increasing evapotranspiration. Based on Penman-FAO24, climatic water balance methods and measured values are shown to be significantly related with each other and to be available in Korea. It is certainly recognized that increasing annual rainfall volume leads to increasing annual runoff depth; for fluctuation in annual runoff rates, there are some difference in changes in measured values and calculated values. It is presumably early to determine that climate changes has a significant effect on runoff characteristic at dam catchment. It is widely known that climate changes are expected to cause many difficulties in water resources and disaster management. To take appropriate measures, deeper understanding is necessary for climatological conditions and variability of hydrology and to have more careful prospection and to accumulate highly reliable knowledge would be prerequisites for hydrometric network.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.39-39
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• 2016

기후 변화의 수자원 영향 평가에서 전지구모형이 갖는 불확실성이나 이산화탄소 배출 등의 시나리오별 불확실성에 대해서는 많은 연구가 진행되어져 왔으나, 외부의 변화가 아닌 지구 시스템상의 내부 변화에 대한 자연적인 변동성에 대해서는 상대적으로 연구가 미흡한 상태이다. 대표적인 내적 변동성의 예시로 엘리뇨 또는 라니뇨 현상을 들 수 있으며, 일정 영역 해수의 온도 변화에 따른 순환정도가 전세계적으로 큰 영향 (태풍, 가뭄, 홍수 등)을 주는 것을 확인할 수 있었다. 유역에서의 침식 및 퇴적 현상에서도 기후변화에서와 비슷한 내적변동성의 영향이 관찰되어지나, 과거의 대부분의 연구는 외적변동성의 영향에만 집중되어 왔다. 가장 빈번하게 발생하는 예로, 토양 표면의 미묘한 변화 (aggregation, dispersion, shielding, crusting 등)때문에 같은 양의 강우 또는 유출이 발생하는 경우라도 같은 양의 침식량이 발생하지 않는 현상을 들 수 있다. 여기에서 다루어지는 침식량의 '다름'은 같은 지역에서라도 적게는 수십배에서 크게는 수백배까지 예측량이 다를 수 있음을 뜻한다. 이러한 다름이 그동안 수자원/지질학을 연구하는 학자 및 실무자로 하여금 수치모델을 적용하고 예측하는 것을 어렵게 했던 원인이 되었다. 본 연구에서는 기후 변화가 가져올 수자원의 영향 평가를 수행할 것이다. 관심있는 기후변화 변수로서 기온 및 강수량을 시간단위로 상세화할 것이며, 변화한 기후의 영향을 평가할 수자원의 현상으로는 증발산, 토양수분량, 유출량, 하천에서의 수심 및 첨두량, 침식량 등을 고려할 것이다. 물리현상을 모의하기 위해, 유역기반의 수리, 수문, 침식 및 퇴적 현상을 동시에 계산할 수 있는 통합모델을 개발하였고 적용하였다. 여기에서 얻은 결과로부터 내적 변동성이 수자원 현상에 미치는 불확실성을 확률통계적인 기법을 이용하여 정량화할 수 있을 것이다.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.1067-1071
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• 2008

장기적인 수자원정책을 수립하기 위해서는 강수, 증발산, 유출 등의 물수지의 변동성을 평가하는 것이 중요하다. 특히 기후변화로 인한 기온 증가는 증발산량에 영향을 미칠 것이다. 따라서 기후변화에 따른 수자원의 영향을 신뢰성 있게 평가하기 위해서는 증발산량의 산정방법에 대한 불확실성을 평가하는 것이 필요하다. 본 연구에서는 다섯 가지의 증발산량 산정방법에 대해 기온 및 강수변화에 따라 증발산량 계산과 유출량산정에 미치는 영향을 평가하였다. 안동댐 유역에 대해 준분포형 수문모형인 SLURP를 이용하여 기온과 강수변화에 따른 5가지 증발산량 산정방법의 민감도를 분석하였다. SLURP 모형에서는 Penman-Monteith method, Morton CRAE method, Spittlehouse/Black method, Granger method, Linacre method의 다섯 가지방법을 제시하고 있고, 관측 자료에 대해 검 보정을 수행한 결과 5개의 증발산량 산정법 모두 안동댐 유역에 대해 잘 모의하는 것으로 나타났다. 기온과 온도를 변화시킨 합성시나리오에서 Linacre 방법이 다른 방법들과 비교하여 높은 민감도를 나타내었는데 증발산량 산정법별 구조적 차이가 원인 것으로 판단되어 추가적인 연구가 진행 중이다. 결과적으로 각 증발산량 산정방법에 따른 민감도 차이는 기후변화 영향평가 결과의 불확실성을 제시하는 척도가 될 것이다.