• 대한원격탐사학회지
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• 제36권1호
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• pp.29-39
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• 2020

Forest fire is a critical disaster that causes massive destruction of forest ecosystem and economic loss. Hence, accurate estimation of the burned area is important for evaluation of the degree of damage and for preparing baseline data for recovery. Since most of the area size damaged by wildfires in Korea is less than 1 ha, it is necessary to use satellite or drone images with a resolution of less than 10m for detecting the damage area. This paper aims to detect wildfire-damaged area from a Kompsat-3 image using the indices such as NDVI (normalized difference vegetation index) and FBI (fire burn index) and to examine the classification characteristics according to the methods such as Otsu thresholding and ISODATA(iterative self-organizing data analysis technique). To mitigate the salt-and-pepper phenomenon of the pixel-based classification, a gaussian filter was applied to the images of NDVI and FBI. Otsu thresholding and ISODATA could distinguish the burned forest from normal forest appropriately, and the salt-and-pepper phenomenon at the boundaries of burned forest was reduced by the gaussian filter. The result from ISODATA with gaussian filter using NDVI was closest to the official record of damage area (56.9 ha) published by the Korea Forest Service. Unlike Otsu thresholding for binary classification,since the ISODATA categorizes the images into multiple classes such as(1)severely burned area, (2) moderately burned area, (3) mixture of burned and unburned areas, and (4) unburned area, the characteristics of the boundaries consisting of burned and normal forests can be better expressed. It is expected that our approach can be utilized for the high-resolution images obtained from other satellites and drones.

• 한국환경과학회지
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• 제31권9호
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• pp.735-741
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• 2022

Global warming affects forests and their ecology. Diversity in the forest is a buffer that reduces the damage due to global warming. Mixed forests are ecologically more valuable as versatile habitats and are effective in preventing landslides. In Korea, most forests were created by simple afforestation with trees of evergreen species. Typically, evergreen trees are shallow-rooted, and deciduous trees are deep-rooted. Mixed forest tree roots grip the soil effectively, which reduces the occurrence of landslides. Therefore, improving the distribution of tree types is essential to reduce damage due to global warming. For this improvement, the investigation of tree types of the forest is needed. However, determining the tree type distribution of forests that are spread over wide areas is labor-intensive and time-consuming. This study suggests effective methods for determining the distribution of tree types in a forest that is spread across a relatively wide area. Using normalized difference vegetation index and RGB images from unmanned aerial vehicles, each evergreen and deciduous tree, and grassland area can be distinguished. The distinguished image determines the distribution of tree type. This method is effective compared to directly determining the tree type distribution in the forest by the use of manpower. The data from these methods could be applied to plan a mixed forest or to prepare for future damage due to global warming.

• 한국산림과학회지
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• 제94권3호통권160호
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• pp.197-204
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• 2005

동해에서 발생한 쓰나미가 우리나라에 미치는 영향을 파악하고, 해안림이 쓰나미의 속도와 에너지를 저감시키는 기능 및 비구조물 대책에 대하여 일본의 사례를 중심으로 분석하였다. 자료를 분석한 결과, 1983년과 1993년에 동해에서 발생한 쓰나미는 우리나라 동해안에 1시간 50분만에 도달하였으며, 이로 인해 인명, 재산 및 침수피해가 발생하였다. 또한 쓰나미에 대비하여 해안림을 폭 60m로 조성하면 속도는 30%, 에너지는 10%로 각각 저감되므로 60m 정도의 폭을 확보하도록 하고, 해안림의 임분구조는 혼효림의 복층림으로 하며, 방조시설을 함께 시공하여야 한다. 이와 함께 쓰나미에 대한 대응법과 주의점 등에 대한 적극적인 홍보와 같은 비구조물 대책을 마련하여야 할 것이다.

• Journal of Ecology and Environment
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• 제38권2호
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• pp.175-183
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• 2015

Extremely strong winds and heavy rainfall caused canopy gaps in a mixed Abies holophylla broadleaf forest and a Quercus mongolica-dominated forest in Odaesan National Park, Korea in October 2006. The impact of the combination of strong winds and torrential rain on the development of forest gaps and canopy structures were investigated. The mean size of newly created gaps were $205m^2$ in the mixed forest and $86m^2$ in the Quercus forest, and were created by 2.8 and 1.4 gapmaker trees, respectively. Among the 73 trees lost in the mixed forest, 59% succumbed because of direct wind damage while 41% were struck by neighboring trees that fell into them. Most of these trees downed by wind were uprooted (74%), while the trees downed by neighboring tree falls snapped (78%). 21 trees in the Quercus forest died from direct wind damage, and 57% of them were uprooted. Although the relative density of Abies nephrolepis and A. holophylla represented only 0.2% and 6.4%, respectively, of all species in the intact mixed forest, they accounted for 27% and 15%, respectively, of all trees affected by wind on that site. In fact, 85% of the total A. nephrolepis and 91% of the total A. holophylla in the mixed forest fell directly due to strong wind. By contrast, only one Abies species, A. nephrolepis, was found in the Quercusdominated forest, and it accounted for 7.3% of the species composition. These findings suggest that A. nephrolepis and A. holophylla are particularly susceptible to high winds because of their great heights and shallow root systems.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2007년도 Proceedings of ISRS 2007
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• pp.533-536
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• 2007

The LiDAR data structure has the potential for modeling in three dimensions because the LiDAR data can represent voxels with z value under certain defined conditions. Therefore, it is possible to classify the physical damaged degree of vegetation by forest fire as using the LiDAR data because the physical loss of canopy height and width by forest fire can be relative to an amount of points reached to the ground through the canopy of damaged forest. On the other hand, biological damage of vegetation by forest fire can be explained using the NDVI (Normalized Difference Vegetation Index) which show vegetation vitality. In this study, we graded the damaged degree of vegetation by forest fire in Yangyang-Gun of South Korea using the LiDAR data for physical grading and digital aerial photograph including Red, Green, Blue and Near Infra-Red bands for biological grading. The LiDAR data was classified into 2 classes, of which one was Serious Physical Damaged (SPD) and the other was Light Physical Damaged (LPD) area. The NDVI was also classified into 2 classes which are Serious Biological Damaged (SBD) and Light Biological Damaged (LBD) area respectively. With each 2 classes ofthe LiDAR data and NDVI, the damaged area by forest fire was graded into 4 degrees like damaged class 1,2,3 and 4 grade. As a result of this study, 1 graded area was the broadest and next was the 3 grade. With this result, we could know that the burned area by forest fire in Yangyang-Gun was damaged rather biologically because the NDVI in 1 and 3 grade appeared low value whereas the LiDAR data in 1 and 3 grade included light physical damage like the LPD.

• Journal of Forest and Environmental Science
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• 제34권6호
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• pp.481-489
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• 2018

In this study, the succession and stand dimension attributes related to the disaster prevention function of Pinus thunbergii coastal forests were examined after damage from Diplodia tip blight. In 2015, 101 years after the Taisho eruption, field investigations were performed on the vegetation, soil thickness, and pH of surface soil of P. thunbergii coastal forests in western Sakurajima (Hakamagoshi plot) and Taisho lava flows in southeastern Sakurajima (Seto plot). The Hakamagoshi plot had more woody plant species with larger basal areas than that in the Seto plot. The mean age and height, maximal age and height of plant species, and H/D ratio were all larger in the Hakamagoshi plot than in the Seto plot. These results may be explained by the relatively smaller effect of volcanic ash and gas on forests in the Hakamagoshi plot compared to the Seto plot, resulting in a more suitable environment for many plant species. Although P. thunbergii coastal forests in Sakurajima are currently recovering from damages owing to Diplodia tip blight, there has not yet been a sufficient recovery compared to the results from a 1997 study. Furthermore, the results of assessment based on the H/D ratio and abundance of trees in P. thunbergii forests indicate that both regions are not yet effective in disaster prevention. Thus, it is necessary to establish Pinus trees, which can adjust to harsh environments like coastal areas and are resistant to volcanic ash and gas, to enhance the disaster prevention function of P. thunbergii coastal forests in volcanic regions. It may also be helpful to establish coastal forests with ectotrophic mycorrhizal fungi and organic matter coverage. Additionally, it is necessary to ensure the continuous maintenance of stand density and soil quality, and further develop efforts to prevent Diplodia tip blight and promote forest recovery.

• 현장농수산연구지
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• 제24권3호
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• pp.33-43
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• 2022

This study was conducted to monitor the vegetation recovery in the areas damaged by the forest fires on the east coast that occurred in April 2000. The study site was a forest fire-damaged area in Samcheok-si, Gangwon-do, and 21 monitoring areas (12 natural restoration sites, 9 artificial restoration sites) were selected to analyze the vegetation recovery trend since 1998. The vegetation recovery trend was compared by calculating the values according to the year using the difference Normalized Burn Ratio (dNBR) and Normalized Difference Vegetation Index (NDVI) based on satellite images (Landsat TM/ETM+ and Sentinel-2A). As the result of this study, all 21 sites, vegetation was recovered, and both groups showed the greatest recovery in summer. In the case of the dNBR, the artificial restored sites showed higher values than the natural restored sites, and in the case of the NDVI, the natural restored sites were higher than the artificially restored sites in summer and autumn. However, the difference between the two groups of natural and artificial restoration sites was not significant. Therefore, the direction of forest restoration after forest fire damage can be effectively restored if properly implemented for the purpose of restoration of the target site.

• 대한원격탐사학회지
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• 제35권6_2호
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• pp.1107-1115
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• 2019

산불 피해와 관련하여 위성영상을 활용한 분석은 넓은 면적을 빠르게 분석하는 장점이 있다. 본 연구에서는 2019년 4월 4일 속초에서 발생한 산불 피해에 따른 산림의 변화 탐지를 위해 7장의 Sentinel-2A영상을 활용하였다. 산불피해지역 분류 과정은 NBR(normalized burn ratio) 값의 전후 시기 차이를 나타낸 dNBR(difference normalized burn ratio)을 통해 산불피해 정도를 7가지 단계로 분류하였다. 분류과정에서 본 연구는 식생의 재성장지수가 높은 3지역을 선정하여 해당 지역에 대한 세밀한 공간 분석을 실시하였다. dNBR 분석 결과는 활엽수림보다 침엽수림의 식생 재성장 분류가 큰 폭으로 나타났으나, NDVI를 통한 결과에서 가장 낮은 평균값을 보여주었다. 이는 침엽수림의 dNBR 오차범위로 나타난다. 시계열 결과로는 4월 20일과 5월 3일 사이를 기준으로 산불피해 면적이 큰 폭으로 감소하였다. 이는 경과한 시기의 활엽수림에서 하층 식생의 발달 및 식생 증가에 따른 피해 완화로 예를 들 수 있다. 본 연구 결과는 발생하는 산불 피해에 대하여 산림 분류 별 면적 변화를 통해 변화 탐지를 실시하였으며, NDVI와 dNBR 비교를 통해 침엽수림이 가장 높은 분류 오차가 발생한다는 결론을 도출하였다. 따라서 dNBR을 통한 영상분류과정에서 현장조사를 동반한 정밀한 국내 산불피해 등급표를 개선해야 할 필요성을 제시하였다.

• 한국재난정보학회 논문집
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• 제9권3호
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• pp.347-357
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• 2013

본 연구는 산지토사재해의 인문사회적 피해강도 기준을 개발하기 위하여 산지토사재해로 피해를 입은 지역주민들의 산사태 방재사업에 대한 인식을 조사하고, 분석하는 것을 목적으로 한다. 우리나라는 전 국토의 약 64%가 산림지역이며 인구밀도가 매우 높아 산지개발을 통해 도시가 발전한 대표적인 산지-도시생활형 국가이다. 최근들어 우리나라는 산지토사재해로 인한 인명피해가 침수로 인한 인명피해를 넘어서는 등 산사태의 발생이 대형화되고 있다. 그 결과 2011년에는 서울시 우면산, 춘천시 등에서 예상하지 못한 산사태로 총 43명의 사망자가 발생하였고, 복구사업으로 막대한 비용이 소요되었다. 본 연구는 2011년의 주요 피해지역인 서울 우면산, 춘천시, 부산시, 동두천시를 대상으로 산사태의 피해현황과 피해요인에 대한 시설물 현장답사와 주민 설문조사를 수행하였다.

• 한국대기환경학회지
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• 제23권1호
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• pp.29-38
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• 2007

Recently, the tropospheric ozone has gained a global attention for its adverse effect on vegetation as well as its contribution to the global warming. Although a number of studies have been carried out for the urban ozone, the effect of ozone on vegetation is still largely unknown in Korea. The present work aimed at performing the first evaluation of forest damage by ozone using the national air monitoring data from the year 2000 to the year 2005. Moreover, it also explored the relevance of adverse effect of ozone to the recent events on leaf chlorosis of black locust, Robinia pseudo-acacia, leading to early foliage widely observed in Korea since 2001. In the nineties, forest damages caused by ozone such as leaf chlorosis occurred in Europe and North America and led to invoke comprehensive field and laboratory studies. As a result, AOT40, implying the accumulated dose over a threshold 40 ppb, was developed to assess the forest damage by ozone. 19 air monitoring stations were selected across Korea to calculate AOT40 from the year 2000 to the year 2005. The calculated AOT40 generally increased during April and May and reached the maximum after May. The increase of AOT40 diminished substantially from the mid-June as the rainy season started. The calculated AOT40 in the nine rural sites from the year 2002 to th ε year 2005 ranged from 6.8 to 29.4 ppm-hr. And all the AOT40 at th ε year 2005 exceeded the critical value of 10 ppm-hr for forest damage. Morevoer the calculated AOT40 of Korea appeared higher than the AOT40 of Europe in the year 2004/2005 and comparable to the AOT40 of China in the year 2000. Despite the high levels of the calculated AOT40 since the year 2001 and the consistency of time of seasons between high AOT40 values and occurrence of chlorosis of black locust, further studies are required to conclude that the chlorosis of black locust occurred from the year 2001 to the year 2005 were resulted from a damage by ozone.