Coastal Disaster Prevention Research Articles

The Measure Against Restoration of Coastal Disaster Prevention Forests Damaged by the Great East Japan Earthquake

The Measure Against Restoration of Coastal Disaster Prevention Forests Damaged by the Great East Japan Earthquake

Restoration of Coastal Disaster Prevention Forests Damaged by the Great East Japan Earthquake

Restoration of Coastal Disaster Prevention Forests Damaged by the Great East Japan Earthquake

유한요소 폭풍해일 모형을 이용한 직립안벽에 대한 범람모의

연안방재계획 수립을 위한 기초자료 생성의 일환으로 태풍에 의한 해일 범람모의를 수행하였다. 통상적인 침수-노출 처리가 불가한 직립안벽을 갖는 항만역의 특징이 반영되도록 가상의 내부제방 개념을 도입하여 해석하였다. 목포항에 대한 실제해역 적용에 앞서 단순해역에서 다수의 적용성 평가를 통해 내부제방의 폭은 1 m가 적정한 것으로 평가되었다. 해일범람으로 인한 침수면적과 침수심 산정에 민감하게 작용하는 육역의 침수-노출 처리기법에서의 최소침수심은 격자에 의존적이나 10 m 내외의 유한요소 상세격자에서는 0.01 m가 적정한 것으로 판단된다. 기존 태풍경로에 준거한 100년 빈도급 중심기압과 최대풍속을 가지며 비대칭 경도풍과 파랑효과가 고려된 가상태풍의 내습에 따른 목포해역의 침수예상역이 모의되었다. 침수면적은 기존 연구결과와 유사성을 나타내지만 항만권역 일부에서 확대 가능성이 있는 것으로 평가된다. Typhoon induced surge simulations are done to make an establishment of coastal disaster prevention plan. To apply efficient run-up and overtopping on vertical harbor docks, in which prevailing wet-dry scheme cannot be satisfied due to infinite steepness, an imaginary internal barrier concept introduced and analyzed. Before real application on the Mokpo harbor area, feasibility tests are done on an idealized simple geometry and as a result it is found that the moderate width of the barrier might be 1 m. The threshold value of the minimum wet depth <TEX>$H_{min}$</TEX> for land area, which behaves sensitive role in inundation area and depth, depends on grid size. However it is revealed that 0.01 m is adequate value in this fine finite element with 10 m spacing. A hypothetical typhoon of 100 years return period in central pressure and maximum velocity is generated based on historical tracks. Simulation of possible inundation on Mokpo area is performed with asymmetrical vortex of hypothetical typhoon and wave coupling. Model results show general agreement in pattern compared to other's prediction, however possibility of inundation enlargement is expected in harbor area.

정밀수준측량 성과를 이용한 육상 및 해상 수직기준면 변환모델링

현재 우리나라의 국가수직기준체계는 육상과 해상으로 서로 이원화되어 있어 전 국토에 걸쳐 균일하고, 정확한 높이정보를 획득하기 어려운 문제가 있다. 본 연구에서는 국토지리정보원에서 수행한 TBM 및 BM 간 연결 수준측량 성과를 이용하여 육상과 해상으로 이원화된 국가수직기준체계의 문제점을 해결하고자 하였다. 이를 위해 정밀 수준측량으로 결정된 육상과 해상 수직기준면 간 편차를 모델링하여 육상 해상 수직기준면 연계를 위한 변환모델을 개발하였다. 보다 정밀한 수직기준면간 변환모델링 방안을 제시하기 위하여 LSC 및 Spline 방법 등 다양한 보간방법들에 의한 결과를 분석하였으며, 그 결과 비선형의 4-파라미터 경향성 모델과 LSC 방법을 조합하여 개발하는 방안이 가장 적합하였다. 이 방법에 의해 개발된 수직 기준면 변환모델의 정확도는 약 <TEX>${\pm}10.4cm{\sim}14.8cm$</TEX> 수준으로 분석되었으며, 변환모델을 사용하여 다양한 공간정보의 높이정보를 효율적으로 변환할 수 있는 변환 소프트웨어도 함께 개발하였다. 본 연구를 통해 육상 및 해상 국가공간정보의 연계 활용 시에 높이정보 불일치로 인한 혼란을 최소화할 수 있을 것으로 기대되며, 향후 연안지역 개발과 해양방재의 수행에 있어서도 경제적, 시간적 손실을 최소화할 수 있을 것으로 판단되었다. It is difficult to obtain the accurate and homogeneous height information over the whole Korea due to the effect of different vertical datums have been divided into land and sea part. In this study, we tried to unify the different vertical datums using the precise spirit leveling between TBM (tidal bench mark) and BM (bench mark) in order to solve the problems caused by different vertical datums. For this, the vertical datum offsets at observed points which were calculate from leveling results and then transformation model of vertical datum will be modelled using calculated offsets along the coastal line. For suggesting the precise modelling method to vertical datum transformation, we analyzed results from various interpolation methods such as Spline and LSC method. As the results from analysis, the LSC method combined with 4-parameters trend model is more suitable for modelling the offsets between vertical datums. The final transformation model of vertical datum using the combination of LSC and 4-parameter model which provides the transformation accuracies of <TEX>${\pm}10.4cm{\sim}14.8cm$</TEX> level. And, the software for vertical datum transformation that was also developed using the final model in order to convert the height information included in various spatial data effectively. Therefore, the transformation model between vertical datums of land and sea part, which is developed in this study, is expected to minimize the confusion caused by mismatch of height information in the use of spatial data, and it also can be minimize economic and time losses in various application fields such as coastal development project, coastal disaster prevention, etc.

우리나라 조위관측소의 장기간 해수면 변화 분석

Long period sea level changes were investigated at 17 tidal stations which are located around Korea peninsula with more than 25 years tide-gauge data. Regression analysis was applied to get general rising trend for long-term change(1960~2010) in mean sea level(MSL) at each station. The results showed that rising trends of MSL around Korea is higher than that of global MSL. The linear rising trend of MSL was relatively small along the western coast(on average 1.3mm/year), large along the southern and eastern coasts(on average 3.2 and 2.0 mm/year), and very large at around Jeju Island(on average 5.6 mm/year). The rising rate of around Jeju Island is about 3 times higher compared to the world ocean. According to recently IPCC report, the rate of sea level rising can be accelerating after 21st century. The interannual variation of sea level rising around Korea showed regional difference. This property of sea level rising should be considered to design the coastal structure in terms of coastal disaster prevention.

エチゼンクラゲ類(&lt;I&gt;Nemopilema&lt;/I&gt; spp.)を活用した海岸防災林の造成

エチゼンクラゲやミズクラゲ等を活用した土壌改良材を海岸林の造成に活用するために，山形県の庄内砂丘地に植栽された海岸植生であるクロマツを用いて生育実験を行った。その結果，1 年目と 2 年目の樹高および根元直径成長量は，施用区と無施用区との間に，1 ％から 10 ％レベルで有意な差が認められ，その有効性が現地実験で確認された。3 年目の樹高および根元直径成長量は，施用区と無施用区との間に，有意な差は認められなかった。しかし，4 年目の樹高および根元直径成長量は，施用区と無施用区との間に，5 ％から 10 ％レベルで有意な差が認められた。このことから，土壌改良材の施用効果は，継続しているものと判断された。

Ensemble Empirical Mode Decomposition on Storm Surge Separation from Sea Level Data

This paper concerns the storm surge calculation based on the algorithm of ensemble empirical mode decomposition (EEMD). An accurate storm surge result is key information for coastal disaster warning and prevention. Separation of storm surge magnitude from sea level data has typically been done by specifying tidal input from main tidal harmonics. Obtaining accurate storm surge magnitude with harmonic analysis (HA) requires at least one month. This study discusses possible storm surge separation from short-term sea level time series using EEMD. The current work reveals that EEMD is predominant for short-term sea level data analysis shorter than thirty-five days. Due to different residues obtained from EEMD, this work proposes a method to determine most ideal residue for representing the storm surge.

WAVE CLIMATE CHANGE PROJECTION AT THE END OF 21ST CENTURY

The influence of global climate change due to green house effects will require impact assessment and adaptation strategies for future our society. The sea level rise is a static side issue of climate change and is important for human activity near the coastal zone. On the other hand, waves and storm surge are dynamic side of climate change and will be necessary to take into the consideration for coastal disaster prevention and reduction, if extreme weather events will become stronger than those in the present climate. This study estimate the future ocean wave climate in comparison with those in present climate based on the global atmospheric climate model and global wave model.

Adaptive Coastal Preservation Measures with Consideration of Fluctuation of Climate Change

A way of thinking about the adaptive measures to the coastal protection which considered“a fluctuation” of the climate change, was proposed. Definition of“fluctuation” in this paper is a change in climate caused by the volcanic eruption, El Nino Southern Oscillation (ENSO), 11 years of the solar activity together with anthropogenic changing trend and several decadal oscillation of ocean. Considering such“fluctuation”, discussions were made how we should design coastal structures, manage shore environment and establish the coastal disaster prevention measures in the near future of several decades.

特別セッション「沿岸防災―沿岸防災施設のアセットマネジメント―」のまとめ

This paper summarizes the special session “Coastal Disaster Prevention-Asset Management for Coastal Disaster Prevention Facility-” This session has been planned on the basis of the discussion of the last year special session (Fukute et al., 2007). Presentations include (1) risk curve formulation and utilization on the life cycle cost, (2) an approach for asset management of decrepit social infrastructures and there perspective for the future, (3) development of evaluation system for asset management of port facilities, (4) research direction about changes in tropical cyclones associated with global warming, and (5) development of shore protection facilities database using GIS. After presentations, the subjects for applying the asset management to coastal disaster prevention facilities have been discussed. Throughout the presentations and discussions, many important matters have been pointed out.

沿岸防災―沿岸防災施設のアセットマネジメント―

This paper summarizes the special session “Coastal Disaster Prevention -Asset Management for Coastal Disaster Prevention Facility-. ”This session has been planned to understand the asset management and to contribute an application of the asset management for coastal disaster prevention facilities. Presentations include (1) asset management for infrastructure, (2) asset management for road infrastructure, (3) superannuation and destruction of shore protection facilities and (4) a current state and engineering subjects on investigation, measurement, diagnosis and deterioration forecast of port & harbor structure. After presentations, the subjects for applying the asset management to coastal disaster prevention facilities have been discussed. Throughout the presentations and discussions, many important matters have been pointed out.

Functions of coastal disaster prevention forest and points of the control for the future

Functions of coastal disaster prevention forest and points of the control for the future