• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.605-605
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• 2016

최근 기후변화로 인한 국지적 또는 대규모 극한 가뭄과 홍수가 빈발함에 따라 수자원 관리 여건은 점점 더 어려워지고 있다. 이런 물 관련 재해에 보다 효과적으로 대응하기 위해서는 수자원인자에 대한 시공간적 모니터링이 필수적인데, 이러한 관점에서 시공간적 광역관측이 가능한 위성자료의 활용가치는 매우 높게 평가되고 있으며, 최근에는 국내외적으로 위성자료를 이용하여 수문 인자 산출, 가뭄 홍수 등의 모니터링 기술 등에 대한 연구가 활발히 진행되고 있다. K-water는 위성정보 활용기술력 축적을 통한 보다 효율적인 수자원 관리를 하기 위하여 수자원 분야에 활용 가능한 해외의 주요 위성자료를 실시간 직수신 처리하여 표출하는 K-water 위성영상관리시스템(K-SIMS, K-water Satellite Image Management System)을 2015년에 구축하였다. 현재 K-SIMS를 통해 관리되는 위성은 AQUA, TERRA, NPP, GCOM-W, GPM로서 총 5개이다. AQUA, TERRA, NPP 위성은 각 궤도운영 스케쥴에 따라 한반도 상공을 통과하는 시각에 안테나가 위성의 궤도를 따라가며 수신하고, GCOM-W, GPM 위성자료는 FTP 접속를 통해 준실시간으로 수신하고 있다. 산출물은 AQUA, TERRA, NPP가 각각 23종, GCOM-W 9종, GPM 2종 등 총 80여종으로 위성원시자료 수신즉시 처리 표출까지 실시간 자동 수행되고 있으나 식생지수, 강수, 구름, 대기온도, 수증기 등 대부분 수문기상학적 변수들로 구성되어 있어 수자원 관리 현업 업무에는 직접 사용하기에는 다소 한계가 있다. 따라서, 위성자료의 활용성을 높이기 위하여 수문해석에 중요한 변수인 토양수분에 대해서 AQUA, TERRA의 MODIS LST(Land Surface Temperature)와 식생지수(Vegetation Index)를 이용하여 SMI(Soil Moisture Index)를 산출하고 이를 K-SIMS에 표출하는 체계를 추가로 구축하여 현업 활용도가 높은 자료를 생산하고 있으며, 향후 위성자료를 활용한 가뭄지수를 추가로 산출하여 표출할 계획이다. 이와 함께 K-water는 차세대 중형위성 개발 사업에 따른 수자원 위성 확보에 대비해 수자원 분야 위성활용 중장기 계획을 마련하였다. 향후에 광학위성, SAR위성 등 다양한 위성자료의 융복합적 활용을 통하여 위성산출물 알고리즘을 지속적으로 개발함으로써 홍수, 가뭄, 수질 등 물 재해 대응 및 수자원 관리 전 분야에 위성자료의 활용을 확대해 나갈 계획이다.

• Journal of Korea Water Resources Association
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• v.54 no.9
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• pp.705-718
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• 2021

Climate change has a significant impact on vegetation growth and terrestrial ecosystems. In this study, the possibility of ecological drought was investigated using satellite remote sensing data. First, the Vegetation Health Index was estimated from the Normalized Difference Vegetation Index and Land Surface Temperature provided by MODIS. Then, a joint probability model was constructed to estimate the possibility of vegetation-related drought in various precipitation/evaporation scenarios in forest areas around 60 major ASOS sites of the Meteorological Administration located throughout Korea. The results of this study show the risk pattern of drought related to forest vegetation under conditions of low atmospheric moisture supply or high atmospheric moisture demand. It also identifies the sensitivity of drought risks associated with forest vegetation under various meterological drought conditions. These findings provide insights for decision makers to assess drought risk and develop drought mitigation strategies related to forest vegetation in a warming era.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.365-365
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• 2019

가뭄은 전 세계적으로 농업을 비롯한 사회, 경제적으로 큰 피해를 주는 자연 재해이며, 향후 피해 저감을 위해 가뭄의 경향을 파악하고 지역별 가뭄 특성을 파악할 필요가 있다. 위성영상을 활용한 가뭄 판단은 광역적 범위를 대상으로 다양한 밴드를 활용한 데이터를 주기적이고 일정한 수준으로 취득 가능하다는 장점이 있다. 농업 가뭄 분야의 위성영상 활용은 미계측 지역에 대한 정확한 데이터 취득이 어려운 지점데이터의 단점을 보완할 수 있다. 위성영상을 활용한 가뭄 지수로는 Leaf Area Index (LAI), Vegetation Health Index (VHI), Enhanced Vegetation Index (EVI) 등 다양한 지수들이 있으며, 본 연구에서는 단기 가뭄 판단에 활용되고 있는 Evaporative Stress Index (ESI)를 활용하였다. 국내 행정구역 기반의 가뭄 판단을 위해 Moderate Resolution Imaging Spectramadiometer (MODIS)위성의 MOD16A2 영상을 사용하였다. MOD16A2는 land surface temperature (LST)과 LAI의 계산을 통한 실제 증발산량과 FAO-56 Penman-Monteith 공식을 사용한 잠재증발산량을 포함한 다양한 데이터를 8일 주기의 500m 해상도로 제공하고 있다. 2001년부터 2018년까지 500m 해상도의 ESI를 산정하였으며, 국내의 과거 가뭄 경향 분석과 지역별 특성 파악을 위한 표준화를 수행하였다. 그 결과 과거 극심한 가뭄이 있었던 해 (2000-2001년, 2015-2017년 등)에 대한 농업 가뭄 경향 분석이 가능하였으며, 지역별 특성을 파악한 결과 상습가뭄 지역에서 가뭄 경향을 확인하였다. 농업 가뭄 분야에서 ESI의 활용은 가뭄 조기 경보 시스템 개발 및 위성영상 기반 가뭄 모니터링 기술 개발 등에 활용 가능할 것으로 기대된다.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.375-375
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• 2023

본 연구는 농지를 대상으로 토양수분 및 가뭄 현황을 분석하는 데 그 목적이 있다. 토양수분을 파악하기 위해 Terra MODIS(Moderate Resolution Imaging Spectroradiometer) 위성영상기반의 토양수분 산정모형을 개발하였다. 해당 모형은 MODIS LST(Land Surface Temperature) 및 NDVI(Normalized Difference Deficit Index)를 기반으로 SCS-CN(Soil Conservation Service-Curve Number) 방법에서 착안한 수문학적 개념 5일 선행강우 및 무강우일수를 입력자료로 하며, 토양 종류 및 계절에 따른 토양수분의 특성을 고려하였다. 모형의 개발을 위해 MODIS LST 및 NDVI 영상을 2013년부터 2022년까지 각각 일별 및 16일 단위로 구축하였으며, 동 기간에 대해 전국 88개소의 기상청 종관기상관측소의 강수량 및 LST 자료를 수집하였다. MODIS LST는 실측 LST 자료를 활용해 조건부합성기법을 적용하여 상세화하였고, 수집된 강수량자료는 역거리가중법을 활용해 공간 보간을 수행하였다. 토양특성의 구분은 농촌진흥청에서 정밀토양도를 수집하여 활용하였다. 공간 분포된 토양수분에서 농지에 해당하는 토양수분을 추출하기 위해 스마트팜맵을 구축하고, 농지 속성에 해당하는 위치 정보를 조회 후 이를 시군구별로 평균하여 일별 평균 토양수분값을 산정하였다. 토양수분 기반의 가뭄 현황 분석을 위해 구축된 정밀토양도에서 작물 생장과 관련된 영구위조점 및 포장용수량을 활용해 5단계(정상, 관심, 주의, 경계, 심각)의 가뭄 위험도를 산정하였으며, 실제 가뭄 현황과의 비교를 통해 토양수분기반의 가뭄 위험도의 실효성을 검증하고자 한다.

• Journal of Cadastre & Land InformatiX
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• v.47 no.2
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• pp.107-120
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• 2017

There are many wildfire risk indices worldwide, but objective comparisons between such various wildfire risk indices and surface dryness indices have not been conducted for the wildfire cases in Korea. This paper describes a sensitivity analysis on the wildfire risk indices and surface dryness indices for Korea using LDAPS(Local Analysis and Prediction System) meteorological dataset on a 1.5-km grid and MODIS(Moderate-resolution Imaging Spectroradiometer) satellite images on a 1-km grid. We analyzed the meteorology-based wildfire risk indices such as the Australian FFDI(forest fire danger index), the Canadian FFMC(fine fuel moisture code), the American HI(Haines index), and the academically presented MNI(modified Nesterov index). Also we examined the satellite-based surface dryness indices such as NDDI(normalized difference drought index) and TVDI(temperature vegetation dryness index). As a result of the comparisons between the six indices regarding 120 wildfire cases with the area damaged over 1ha during the period between January 2013 and May 2017, we found that the FFDI and FFMC showed a good predictability for most wildfire cases but the MNI and TVDI were not suitable for Korea. The NDDI can be used as a proxy parameter for wildfire risk because its average CDF(cumulative distribution function) scores were stably high irrespective of fire size. The indices tested in this paper should be carefully chosen and used in an integrated way so that they can contribute to wildfire forecasting in Korea.

• Korean Journal of Remote Sensing
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• v.39 no.5_3
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• pp.1031-1042
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• 2023

In this study, a deep learning model was developed to predict the yield of cabbage and radish, one of the five major supply and demand management vegetables, using satellite images of Landsat 8. To predict the yield of cabbage and radish in Gangwon-do from 2015 to 2020, satellite images from June to September, the growing period of cabbage and radish, were used. Normalized difference vegetation index, enhanced vegetation index, lead area index, and land surface temperature were employed in this study as input data for the yield model. Crop yields can be effectively predicted using satellite images because satellites collect continuous spatiotemporal data on the global environment. Based on the model developed previous study, a model designed for input data was proposed in this study. Using time series satellite images, convolutional neural network, a deep learning model, was used to predict crop yield. Landsat 8 provides images every 16 days, but it is difficult to acquire images especially in summer due to the influence of weather such as clouds. As a result, yield prediction was conducted by splitting June to July into one part and August to September into two. Yield prediction was performed using a machine learning approach and reference models , and modeling performance was compared. The model's performance and early predictability were assessed using year-by-year cross-validation and early prediction. The findings of this study could be applied as basic studies to predict the yield of field crops in Korea.

• Journal of the Korean Geographical Society
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• v.40
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• pp.1-13
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• 1989

The brightness temperature from NOAA AVHRR CH 4 images was examined for the metropolitan Seoul area, the capital city of Korea, to detect the characteristics of the urban heat island for this study. Surface data from 21 meteorological stations were compared with the brightness temperatures Through computer enhancement techniques, more than 20 heat islands could be recognized in South Korea, with 1 km spatii resolution at a scale of 1: 200, 00O(Fig. 3, 4 and 6). The result of the analysis of AVHRR CH 4 images over the metropolitan Seoul area can be summerized as follows (1) The pattern of brightness temperature distribution in the metropolitan Seoul area shows a relatively strong temperature contrast between urban and rural areas. There is some indication of the warm brightness temperature zone characterrizing built-up area including CBD, densely populated residential district and industrial zone. The cool brightness temperature is asociaed with the major hills such as Bukhan-san, Nam-san and Kwanak-san or with the major water bodies such as Han-gang, and reservoirs. Although the influence of the river and reservoirs is obvious in the brightness temperauture, that of small-scaled land use features such as parks in the cities is not features such as parks in the cities is not apperent. (2) One can find a linerar relationshop between the brightenss temperature and air temperature for 10 major cities, where the difference between two variables is larger in big cities. Though the coefficient value is 0.82, one can estimate that factors of the heat islands can not be explained only by the size of the cities. The magnitude of the horizontal brightness temperature differences between urban and rural area is found to be greater than that of horizontal air temperature difference in Korea. (3) Also one can find the high heat island intensity in some smaller cities such as Changwon(won(Tu-r=9.0$^{\circ}$C) and Po-hang(Tu-r==7.1$^{\circ}$~)T. he industrial location quotient of Chang-won is the second in the country and Po-hang the third. (4) A comparision of the enhanced thermal infrared imageries in 1986 and 1989, with the map at a scale of 1:200, 000 for the meotropolitan Seoul area showes the extent of possible urbanization changes. In the last three years, the heat islands have been extended in area. zone characterrizing built-up area including (5) Although the overall data base is small, the data in Fig. 3 suggest that brightness tempeautre could ge utilized for the study on the heat island characteristics. Satellite observations are required to study and monitor the impact of urban heat island on the climate and environment on global scale. This type of remote sensing provides a meams of monitoring the growth of urban and suburban aeas and its impact on the environment.

• Korean Journal of Agricultural and Forest Meteorology
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• v.18 no.4
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• pp.327-336
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• 2016

The Bagan, the central part of Myanmar, is dry zone where the mean annual precipitation is less than 600 mm for the last ten years. Forest in this region has been degraded due to biotic and abiotic disturbances. While there have been various efforts to rehabilitate the degraded area, the information on growth and physiological characteristics of planting species and the impacts of planting trees in the region still lacks. Therefore, this study was conducted to determine the growth and physiological water use efficiency characteristics of five species (Azadirachta indica A. Juss., Acacia catechu Willd., Eucalyptus camaldulensis Dehn., Acacia leucophloea (Roxb.) Willd. and Albizia lebbek (L.) Willd.) which are utilized as rehabilitation species in the dry zone and to identify the impacts of tree planting on microclimate change in dry zone. The growth and the foliar carbon isotope composition of seedlings and the above mentioned five species planted in 2005 were measured. And from February 2015 to January 2016, microclimatic factors air temperature and relative humidity at 60 cm and 2 m above soil, soil temperature, soil water contents and precipitation were measured at every 30-minute interval from the two weather stations installed in the plantation located in Ngalinpoke Mt. Range. One was established in the center of A. indica plantation, and the other was in the barren land fully exposed to the sunlight. Among the five species, A. indica and A. lebbek which showed higher water use efficiency could be recommended as rehabilitation species in dry zone. Planting trees in the dry area was shown to affect the change of microclimate with shading effects, declining temperature of the land surface and aridity of the air, and to contribute to conserving more water in soil by preventing direct evaporation and containing more water with fine roots of trees.

• Journal of the Korean Institute of Landscape Architecture
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• v.52 no.2
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• pp.79-95
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• 2024

The purpose of this study was to find the changes in the habitat of wild birds caused by climate change in urban rivers and protected areas that greatly require ecological functions. In the future, this study can be used as a management index to protect the urban river ecosystem and maintain the health of sustainable urban rivers, thereby ensuring biodiversity. The Tancheon Ecological and Landscape Conservation Area, selected as a target site, has been affected by climate change. The four seasons of Korea have a distinct temperate climate, but the average annual temperature in Seoul has risen by 2.4-2.8℃ over the last 40 years. Winter temperatures tended to gradually increase. Precipitation, which was concentrated from June to August, is now changing into localized torrential rain and a uniform precipitation pattern of several months. Climate change causes irregular and unforeseen features. Climate change has been shown to have various effects on urban river ecosystems. The decrease in the area of water surface and sedimentary land impacted river shape change and has led to large-scale terrestrialization. Plants showed disturbance, and the vegetation was simplified. The emergence of national climate change indicator species, the development of foreign herbaceous plants, the change of dry land native herbaceous species, and wet intelligence vegetation were developed. Wild birds appeared in the territory of winter-summer migratory. In addition, species change and the populations of migratory birds also occurred. It was judged that fluctuations in temperature and precipitation and non-predictive characteristics affect the hydrological environment, plant ecology, and wild birds connecting with the river ecosystem. The results of this study were to analyze how climate change affects the habitat of wild birds and to develop a management index for river ecological and landscape conservation areas where environmental and ecological functions in cities operate. This study can serve as a basic study at the level of ecosystem services to improve the health of urban rivers and create a foundation for biodiversity.

• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.4
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• pp.334-344
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• 2013

In order to understand the characteristics of oceanic environment in the coastal aquaculture waters of the East Sea, the observation of the CTD (temperature and salinity), dissolved oxygen, chlorophyll a and N/P (DIN ($NO_2$-N, $NO_3$-N, $NH_4$-N) : DIP($PO_4$-P)) ratio was carried out at Sokcho, Jukbyon and Gampo in February, April, June, August, October, December 2013. Based on T(temperature)-S(salinity) diagram analysis, the water masses in the study area were divided into 3 groups; Tsushima Surface Water (TSW: $20-28.3^{\circ}C$ temperatures and 31.04-33.75 salinities), Tsushima Middle Water (TMW: $8.1-16.3^{\circ}C$ and 33.00-34.49), and North Korean Cold Water (NKCW: $1.8-9.4^{\circ}C$ and 33.78-34.42). In winter, DO concentrations in the northern part were higher than those in southern part. In spring and fall, they were low in the surface layer, and increased in summer. Chl-a concentrations < $0.4{\mu}g/L$ dominated in February, April, October and December. Chl-a concentrations were higher in June and August. In particular, the highest Chl-a concentration > $2{\mu}g/L$ was observed in the middle layer of Gampo in August. In February, April, June and December, the N/P ratio in the most of the water masses was less than the Redfield ratio (16), indicating that nitrate did act as a limiting factor in phytoplankton growth. On the contrary, in August and October, the N/P ratio in surface and sub-surface layer was greater than the Redfield ratio, suggesting that phosphate was a limiting factor.