• Proceedings of the KSRS Conference
• /
• 2003.11a
• /
• pp.147-149
• /
• 2003

The wetness, a function of precipitation and temperature etc, and the warmth, a function of temperature, are the dominant factor for global vegetation distribution. This paper employs the normalized difference vegetation index (NDVI), warmth index (WAI), and wetness index (WEI), and focuses on an essential climate-vegetation relationship at global scale. The NDVI was acquired from ‘Twenty-year global 4-minute AVHRR NDVI dataset.’ The WEI is defined as the fraction of the precipitation to the potential evaporation. The WAI was calculated by accumulating the monthly mean temperature of the portion exceeded 5$^{\circ}C$ throughout the year. Meteorological data for the WEI and WAI calculation were obtained from the ISLSCP CD-ROM. All analyses were conducted for 1 ${\times}$ 1 degree grid box on the terrestrial area of the Earth, and on annual value basis averaged in 1987 and 1988. The result of analyses demonstrated that there are two regimes in their relations, that is, a regime in which NDVIs vary depending on the WEI, and a regime in which NDVIs vary depending on the WAI. These two regimes appeared to correspond to the wetness dominant and warmth dominant vegetation, respectively. The geographical distributions of two regimes were mapped. Most of the world vegetation is categorized into wetness dominant, while warmth dominant vegetation is seen in the high-latitude area mainly to the north of 60$^{\circ}$N in the Northern Hemisphere and high-altitude areas.

• Journal of Ecology and Environment
• /
• v.42 no.4
• /
• pp.259-264
• /
• 2018

Background: Revegetating landfills can be a challenging task as the reclaimed soils are typically dry and have low nutrient content. Therefore, selecting suitable plant species is important for initial revegetation. The issue with current practices (in Korea) is that alien plant species have been typically selected for revegetation projects. In this context, this study selects and tests a set of native plant species for landfill revegetation, accompanied by the assessment of the landfill soils. Results: The soil of the landfill (landfill location) was in a very poor condition with high bulk density and low organic matter and nutrient contents. Among 10 tested species, only Brassica campestris showed high coverage and a sufficient number of individuals in study quadrats sown with seeds. Results suggest that plant species with heavy seeds are the only ones that can adapt to the environment of a typical landfill due to the site's aridity and low nutrient content. The reason is due to such species' superior wind resistance and the capacity to provide sufficient energy for the initial growth of the plants for survival in such landfill environment. Conclusions: This study recommends selecting plant species (1) with arid-adapted features and (2) whose seed weight is sufficiently heavy for survival at landfills or areas with a similar condition for future revegetation.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2022.05a
• /
• pp.156-156
• /
• 2022

Explicitly spatially distributed and reliable data on industrial water demand is very much important for both policy makers and researchers in order to carry a region-specific analysis of water resources management. However, such type of data remains scarce particularly in underdeveloped and developing countries. Current research is limited in using different spatially available socio-economic, climate data and geographical data from different sources in accordance to predict industrial water demand at finer resolution. This study proposes a random forest regression (RFR) model to predict the industrial water demand at 0.50× 0.50 spatial resolution by combining various features extracted from multiple data sources. The dataset used here include National Polar-orbiting Partnership (NPP)/Visible Infrared Imaging Radiometer Suite (VIIRS) night-time light (NTL), Global Power Plant database, AQUASTAT country-wise industrial water use data, Elevation data, Gross Domestic Product (GDP), Road density, Crop land, Population, Precipitation, Temperature, and Aridity. Compared with traditional regression algorithms, RF shows the advantages of high prediction accuracy, not requiring assumptions of a prior probability distribution, and the capacity to analyses variable importance. The final RF model was fitted using the parameter settings of ntree = 300 and mtry = 2. As a result, determinate coefficients value of 0.547 is achieved. The variable importance of the independent variables e.g. night light data, elevation data, GDP and population data used in the training purpose of RF model plays the major role in predicting the industrial water demand.

• Journal of Korea Water Resources Association
• /
• v.46 no.7
• /
• pp.735-744
• /
• 2013

The effect of climate and landscape characteristics on hydrologic partitioning and vegetation response is analyzed in this study. After quantifying hydrologic partitioning using the Horton index, the relation between regional climate characteristics and the Horton index is investigated. In addition, using the comparison between the predictability of the Horton index with only regional climate characteristics and the predictability of the Horton index with landscape characteristics as well as regional climate characteristics, the relative contribution of landscape characteristics on hydrologic partitioning is analyzed. Finally, investigating the predictability of the aridity index and Horton index on the normalized difference vegetation index, the effect of climate and landscape characteristics on vegetation response is estimated.

• Journal of the Korean Geographical Society
• /
• v.33 no.3
• /
• pp.377-394
• /
• 1998

The magnetic record of loess deposits may be one of the most detailed and useful records of Quatermary climate change on the continents. Stratigraphic variations of magnetic parameters define alternating zones of high and low concentrations of magnetic minerals. All the concentration-sensitive magnetic parameters show an increase within the interstadial Gilman Canyon Formation and interglacial Brady soil and a systematic decrease within the Wisconsinan Peoria loess. The influence of climate change on magnetic records is confirmed by a high correlation between the magnetic parameters and biological proxies. Rock magnetic data appear to be better correlated with temperature-sensitive biological proxies than does a precipitation-sensitive index such as the aridity index derived from opal phytoliths. Simultaneous, higher resolution sampling of magnetic and biological proxies proved to be a better sampling tactic, and enhanced the feasibility of rock magnetic parameters as independent climate proxies.

• Food Science and Preservation
• /
• v.10 no.2
• /
• pp.136-141
• /
• 2003

This they was conducted to investigate the surface treated effect of Packaged kimchi on the PH, acidity, total microbe, number of lactic acid bacteria, browning and formation of off-flavor during storage at 10$^{\circ}C$. Kimchi was treated with 70% ethanol(1 time spraying) and attachment of polyethylene film(PE) on the surface of packaged kimchi and stored at 10$^{\circ}C$. pH of the control and ethanol treated kimchi stored for 15 days was decreased to 4.0 level but, the pH of PE-treated kimchi maintained over pH 4.0 until 21 days of storage. The aridity was the same tendency as the pH, which showed delaying of fermentation by PE treatment. Total microbe of PE treated kimchi was lower and number of lactic acid bacteria was higher than those of control and ethanol treated products, respectively. Degree of browning and off-flavor of control and ethanol treated kimchi increased from 13 days of storage, but the degrees of the PE-treated kimchi was lower during all storage periods.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2017.05a
• /
• pp.458-458
• /
• 2017

증발산은 지표면으로부터의 증발이나 식물에 의한 증산에 의해 유역으로부터 물이 제거되는 주요 기작으로서, 유역 물수지 관점에서 보았을 때 강수량과 증발산량의 차이로부터 유출이나 함양되는 양을 추정할 수 있다. 제주도의 경우에는 수자원 이용량의 약 84%를 지하수에 의존하고 있으며, 한편으로 제주도의 지질학적 특성으로 인해 일정 규모 이하의 강수량은 지표유출이나 중간유출의 과정없이 대부분 지하로 침투되기 때문에, 증발산량을 정확하게 파악하는 것이 지하수 함양량의 추정과 제주도 전체 수자원 계획에 큰 영향을 주게 된다. 정확한 증발산량 파악을 위해서는 지속적인 관측과 전문적인 계측장비 등에 의한 직접적인 방법이 있으나 광범위한 유역 단위의 관측값을 확보하는 것이 현실적으로 어렵기 때문에, 물수지법, 열수지법, 공기역학적방법 및 조합방법 등의 간접적인 방법이 많이 활용되고 있다. 간접적인 방법으로 많이 활용되고 있는 Penman-Monteith 법은 일 단위 기반의 정확도 높은 증발산량을 추정할 수 있는 장점이 있으나, 작물생육단계 및 토양수분, 기상 등 많은 변수들에 대한 입력을 요구하고 있기 때문에 복잡한 모델링 과정을 수반하게 되는 단점을 내포하고 있다. 반면, Morton (1978)의 CRAE (Complementary Relationship Areal Evapotranspiration)나 Priestly and Taylor (1973)의 AA (Advection-Aridity)와 같이 잠재증발산량과 실제증발산량간의 보완관계를 이용하는 방법은 지역적인 인자 또는 가용 수분에 대한 조건없이 몇 가지 기상자료만으로 유역의 증발산량을 산정할 수 있다는 장점이 있다. 본 연구에서는 제주도 지역의 4개 하천유역(한천, 천미천, 강정천, 외도천)을 대상으로, Penman-Monteith 법을 적용한 SWAT 모델링를 통해 얻어진 유역의 실제증발산량과 잠재증발산량으로부터, 고도에 따른 기상특성을 반영하여 증발산 보완관계를 검토하였다.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2023.05a
• /
• pp.177-177
• /
• 2023

The impacts of dams on transboundary flow are complex and challenging to project and manage, given the potential moderating influence of a broad range of anthropogenic and natural factors. This study presents a global meta-analysis of 168 studies that examines the effect magnitude of dams on downstream seasonal, annual flow, and hydrological extremes risk on 39 hotspot transboundary river basins. The study also evaluates the impact of 13 factors, such as climate, basin characteristics, dams' design and types, level of transboundary cooperation, and socioeconomic indicators, on the heterogeneity of outcomes. The findings reveal that moderators significantly influence the impact of dams on downstream flow, leading to considerable heterogeneity in outcomes. Transboundary cooperation emerges as the key factor that determines the severity of dams' effect on both dry and wet season's flows at a significance level of 0.01 to 0.05, respectively. Specifically, the presence of water-supply and irrigation dams has a significant (0.01) moderating effect on dry-season flow across basins with high transboundary cooperation. In contrast, for wet-season flow, the basin's vulnerability to climate extremes is associated with a large negative effect size. The various moderators have varying degrees of influence on the heterogeneity of outcomes, with the aridity index, population density, GDP, and risk level of hydro-political tension being the most significant factors for dry-season flow, and the risk level of hydro-political tension and basin vulnerability to climate extremes being the most significant for wet-season flow. The results suggest that transboundary cooperation is crucial for managing the impacts of dams on downstream flow, and that various other factors, such as climate, basin characteristics, and socioeconomic indicators, have significant moderating effects on the outcomes. Thus, context-specific approaches are necessary when predicting and managing the impacts of dams on transboundary flow.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2022.05a
• /
• pp.108-108
• /
• 2022

기후변화는 전 지구 수문순환과 수자원 분포에 커다란 영향을 준다. 하지만 지금까지 관측되어온 지구상의 건조도 변화에 있어서 기후의 자연변동성의 영향과 인간활동에 의한 온난화의 영향을 명시적으로 밝힌 연구는 존재하지 않는다. 본 연구에서는 데이터 구동형 모델과 물리 모델을 이용해 관측 기반의 전구 수자원 분포를 1902년부터 2014년까지 재구축함으로써 지구의 평균온도가 약 1도 상승해온 지난 세기에 걸쳐 건기의 수자원 분포가 어떻게 변해왔는지 보인다. 재구축된 전구 변화 패턴은 인간활동에 의한 온실가스 증가등을 고려한 기후 모델 시뮬레이션과 흡사함을 알 수 있었으며 기후의 자연변동성만을 고려한 기후 모델 시뮬레이션에서는 발견되지 않았다. 주로 북아시아, 북미, 유럽 등 중위도 온대지방에서 더욱더 건조한 건기가 뚜렷하게 나타났으며 이는 강수량의 감소보다는 증발산의 증가에 기인하는 것으로 나타난다. 이와 같은 건조도의 변화는 미래 있어서 또한 인류에 대한 커다란 위협으로 자리한다. 미래 기후에서의 가뭄의 변화에 대해 다양한 연구들이 존재하지만 대부분 높은 수준의 온난화 (예를들어 RCP-SSP 585)에서의 영향에 국한된다. 다시 말해 인류가 21세기 중반에 달성을 목표로 하는 탄소중립이 가뭄의 측면에서 어떤 영향을 주게 될지에 대한 연구는 아직 충분하지 않다고 할 수 있다. 본 연구에서는 약한 혹은 중간 수준의 기후변화 시나리오를 이용해 파리협약에서 목표로 하는 1.5℃와 2℃ 상승에 따라 전 지구의 건조도 분포가 어떻게 변하고 그 변화에 있어서 어떠한 수문기후학적 메커니즘이 작용하는지 밝힌다. 지중해 연안 지역에서는 건조도의 가속이 +1.5℃와 +2℃사이에 존재하였으나 동아시아에서는 +1.5℃와 +2℃ 모두에서 습윤해짐을 알 수 있었으며 이러한 지역적 불균일성은 기후변화 대응 노력에 있어서 과거 온실가스 배출에 대한 책임뿐만 아니라 다양한 부문에 걸친 미래의 잠재 적응 노력 또한 고려해야만 함을 시사한다. 본 연구는 제6차 Coupled Model Intercomparison Project의 Land Surface, Snow, Soil-moisture Model Intercomparison Project (CMIP6/LS3MIP)와 Half a degree Additional warming, Prognosis and Projected Impacts (HAPPI)의 다중 모델 앙상블 시뮬레이션 결과를 이용했다.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.3 no.1
• /
• pp.44-54
• /
• 2001

This study was conducted to estimate microclimate of natural deciduous forest in national forest of Pyungchang, Kangwon province and to investigate the effects of the microclimatic conditions on the periodic annual increment of diameter by site types. In this study, site was first classified by nine types considering both elevation (higher than 1,000 m, 700∼1,000 m, and lower than 700 m) and topographical conditions (ridge, slope and valley). For each of site types, diameter growth was measured by using increment borer and periodic annual increment of diameter was then analyzed. A topoclimatological technique, for estimating microclimatic conditions, which make use of empirical relationships between the topographical factor and the climatic normals in the study area was applied to produce monthly mean, maximum and minimum temperatures, relative humidity, precipitation and hours of sunshine. From these monthly estimtes, 17 weather variables such as warmth index, coldness index, index of aridity etc. which affect the diameter growth were computed for each of site types. The periodic annual increment of diameter was then correlated with and regressed on the 17 weather variables to examine effects of microclimatic conditions on the diameter growth by site types. From the correlation analysis, it was found that the diameter growth by site types was positively correlated with all of 17 weather variables except the warmth index. Especially, the conditions such as high relative humidity and large amount of sunshine hours provide favorable environment for the growth of diameter. On the other hand, it was also found that diameter growth was negatively iufluenced by warmth index. According to the regression analysis, the periodic annual increment of diameter could be well predicted by index of aridity and mean relative humidity for the growing season.