Pub Date : 2023-01-30DOI: 10.20481/kscdp.2023.10.1.35
M. N. Adibhusana, I. Hendrawan, Y. Ryu
A numerical study was carried out in Bali Strait, Indonesia. Finite Volume Coastal Ocean Model (FVCOM) was used to simulate the seawater circulation in Bali Strait. The water circulations were forced by the four major tidal components (S2, M2, K1, and O1). Comparisons of the seawater surface elevation obtained from both modeling and observations show a good result. The tide in Bali Strait is a mixed tide type with two different tidal ranges in one day. The seawater circulation moves from the Indian Ocean to the Bali Sea through narrow strait during the flood tide and then rush back during the ebb tide. In the spring tide, an eddy is also observed on the top of the narrow strait. The simulations show that the flows by tides along the sudden change of the cross-sectional width can be modeled by the finite volume method based model.
{"title":"Numerical Study on Tide and Tidal Current along Bali Strait, Indonesia using Finite Volume Coastal Ocean Model (FVCOM)","authors":"M. N. Adibhusana, I. Hendrawan, Y. Ryu","doi":"10.20481/kscdp.2023.10.1.35","DOIUrl":"https://doi.org/10.20481/kscdp.2023.10.1.35","url":null,"abstract":"A numerical study was carried out in Bali Strait, Indonesia. Finite Volume Coastal Ocean Model (FVCOM) was used to simulate the seawater circulation in Bali Strait. The water circulations were forced by the four major tidal components (S2, M2, K1, and O1). Comparisons of the seawater surface elevation obtained from both modeling and observations show a good result. The tide in Bali Strait is a mixed tide type with two different tidal ranges in one day. The seawater circulation moves from the Indian Ocean to the Bali Sea through narrow strait during the flood tide and then rush back during the ebb tide. In the spring tide, an eddy is also observed on the top of the narrow strait. The simulations show that the flows by tides along the sudden change of the cross-sectional width can be modeled by the finite volume method based model.","PeriodicalId":326564,"journal":{"name":"Korea Society of Coastal Disaster Prevention","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128876209","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-10-30DOI: 10.20481/kscdp.2022.9.4.267
Chang S. Kim, Insik Chun, Byungcheol Oh, Ho-hyun Lee, Jieun Choi, Eunhye Mun
The construction of the tidal information database study was conducted through numerical simulations for the southern coast of Korea. Because Korea has a complex coastline, the grid size of the numerical model was set to 0.1min(approx. 200m) to improve the accuracy of tidal prediction. The NAO.99jb, one of the ocean tide models, was employed in the study to increase the accuracy of the database. The numerical model applied to the database construction was calibrated and validated using observation data from the Korea hydrographic and oceanographic agency. To construct a high-resolution tidal information database, we conducted harmonic analysis for each computational grid point using numerical simulation results. In order to evaluate the tide and tidal current prediction performance of the tidal information database, numerical simulation results were used and compared. The results show that the predictive performance of the harmonic constant database is sufficient, so it can be used where rapid tidal prediction is required.
{"title":"Construction of Tidal Information Database on the Southern Coast of Korea and Prediction of the Tide","authors":"Chang S. Kim, Insik Chun, Byungcheol Oh, Ho-hyun Lee, Jieun Choi, Eunhye Mun","doi":"10.20481/kscdp.2022.9.4.267","DOIUrl":"https://doi.org/10.20481/kscdp.2022.9.4.267","url":null,"abstract":"The construction of the tidal information database study was conducted through numerical simulations for the southern coast of Korea. Because Korea has a complex coastline, the grid size of the numerical model was set to 0.1min(approx. 200m) to improve the accuracy of tidal prediction. The NAO.99jb, one of the ocean tide models, was employed in the study to increase the accuracy of the database. The numerical model applied to the database construction was calibrated and validated using observation data from the Korea hydrographic and oceanographic agency. To construct a high-resolution tidal information database, we conducted harmonic analysis for each computational grid point using numerical simulation results. In order to evaluate the tide and tidal current prediction performance of the tidal information database, numerical simulation results were used and compared. The results show that the predictive performance of the harmonic constant database is sufficient, so it can be used where rapid tidal prediction is required.","PeriodicalId":326564,"journal":{"name":"Korea Society of Coastal Disaster Prevention","volume":"74 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127109288","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-10-30DOI: 10.20481/kscdp.2022.9.4.221
Y. Jeong, Jeong-Huem Lee, Jun-Seok Kim, D. Hur
In this study, hydraulic experiments were performed for three types of cross sections depending on the presence or absence of pipeline of CTSB(Caisson-Type Submerged Breakwater), in which slit-upper-level drainage and lower-level drainage are installed to reduction the water level behind the submerged breakwaters. Additionally, based on the measured hydraulic characteristics, we compared the changes in the wave reflection, transmission and dissipation coefficient around the submerged breakwaters three cases with or without drainage with a solid caisson that has no slit-upper-level and lower-level drainage. Therefore, wave control around the submerged breakwaters is better using the Caisson-Type solid than with the slit-upper-level drainage and lower-level drainage. Moreover, reduction of water level behind the submerged breakwaters is better using the slit-upper-level drainage and lower-level drainage than Caisson-Type solid. its effect is excellent when with TTP are used.
{"title":"Wave and Mean Water Level Control by Caisson-Type Submerged Breakwater","authors":"Y. Jeong, Jeong-Huem Lee, Jun-Seok Kim, D. Hur","doi":"10.20481/kscdp.2022.9.4.221","DOIUrl":"https://doi.org/10.20481/kscdp.2022.9.4.221","url":null,"abstract":"In this study, hydraulic experiments were performed for three types of cross sections depending on the presence or absence of pipeline of CTSB(Caisson-Type Submerged Breakwater), in which slit-upper-level drainage and lower-level drainage are installed to reduction the water level behind the submerged breakwaters. Additionally, based on the measured hydraulic characteristics, we compared the changes in the wave reflection, transmission and dissipation coefficient around the submerged breakwaters three cases with or without drainage with a solid caisson that has no slit-upper-level and lower-level drainage. Therefore, wave control around the submerged breakwaters is better using the Caisson-Type solid than with the slit-upper-level drainage and lower-level drainage. Moreover, reduction of water level behind the submerged breakwaters is better using the slit-upper-level drainage and lower-level drainage than Caisson-Type solid. its effect is excellent when with TTP are used.","PeriodicalId":326564,"journal":{"name":"Korea Society of Coastal Disaster Prevention","volume":"46 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116541353","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-10-30DOI: 10.20481/kscdp.2022.9.4.247
H. Yoo, Ki-Hyun Kim, Jong-Beom Kim, T. Kang
Increased coastal human intervention and climate change are leading to rapid changes in coastal areas and often causing catastrophic damage to resident populations. The ShorelineS model was introduced, which can explain drastic beach changes were simulated. According to the modeling results, the installation of Gungchon Port caused rapid sedimentation in the south of the port. It was reviewed that the erosion and sedimentation tendency of the beach is changed after the installation breakwater in front of the beach, the erosion in the central part of the beach was somewhat suppressed, and the beach was deposited in the shape of tombolo on the back of the beach. The installation of artificial structures dramatically changes the equilibrium state of the beach and increases the erosion of the direct wave near the structure. The ShorelineS model was the advantage of being able to properly reproduce changes in the coastline by inputting relatively simplified environment and beach information and to quickly predict after installation of artificial structures. The reallity, coastline changes due to various causes, so follow-up studies are needed to predict and effectively respond to this through an advanced model that reflects various conditions.
{"title":"A Study on the Shoreline Movement of Won-pyeong Beach using ShorelineS Model","authors":"H. Yoo, Ki-Hyun Kim, Jong-Beom Kim, T. Kang","doi":"10.20481/kscdp.2022.9.4.247","DOIUrl":"https://doi.org/10.20481/kscdp.2022.9.4.247","url":null,"abstract":"Increased coastal human intervention and climate change are leading to rapid changes in coastal areas and often causing catastrophic damage to resident populations. The ShorelineS model was introduced, which can explain drastic beach changes were simulated. According to the modeling results, the installation of Gungchon Port caused rapid sedimentation in the south of the port. It was reviewed that the erosion and sedimentation tendency of the beach is changed after the installation breakwater in front of the beach, the erosion in the central part of the beach was somewhat suppressed, and the beach was deposited in the shape of tombolo on the back of the beach. The installation of artificial structures dramatically changes the equilibrium state of the beach and increases the erosion of the direct wave near the structure. The ShorelineS model was the advantage of being able to properly reproduce changes in the coastline by inputting relatively simplified environment and beach information and to quickly predict after installation of artificial structures. The reallity, coastline changes due to various causes, so follow-up studies are needed to predict and effectively respond to this through an advanced model that reflects various conditions.","PeriodicalId":326564,"journal":{"name":"Korea Society of Coastal Disaster Prevention","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130333843","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-10-30DOI: 10.20481/kscdp.2022.9.4.231
Seung-Hyun Lee, Byoung-il Kim, Man-Soo Lee
In order to investigate trustability of prescribed slope inclinations in design criteria, slope stability analyses were performed on the assumed two embankment sections. Factors of safety against dry condition for the section of 10m high and slope inclination of 1:2 and for the other section of 5m high and slope inclination of 1:1.5 were 1.93 and 2.24 respectively and those values were greater than the design criterion value of 1.50. Factors of safety which were computed through seepage analyses for steady state condition were 1.59 for the section of 10m high and 1.93 for the other section and those values were greater than design criterion value of 1.30. Non-steady state analyses under the same rainfall intensity for the steady state condition were also performed to compare with steady state analyses and it can be seen that factor of safety for the non-steady state condition was converged to the value for the steady state condition as time elapsed. Stability analyses of using piezometric line which were located on the top line of the sections were performed and computed values of factor of safety were 1.20 for the section of 10m high and 1.59 for the other section respectively and it could be seen that the factor of safety for the section of 10m is less than the criterion value of 1.30. According to the results of this study, it can be seen that the slope inclination of 1:1.5 for the slope heights less than 5m and the slope inclination of 1:2.0 for the slope heights between 5m to 10m were safe enough under dry condition and rainfall condition. Nevertheless it can be concluded that slope stability analysis should be performed for the slope over 10m high and with ground water table near the surface of the slope because the factor of safety for that situation was less than the design criterion value.
{"title":"An Analytical Study on Trustability of Prescribed Slope Inclinations in Design Criteria","authors":"Seung-Hyun Lee, Byoung-il Kim, Man-Soo Lee","doi":"10.20481/kscdp.2022.9.4.231","DOIUrl":"https://doi.org/10.20481/kscdp.2022.9.4.231","url":null,"abstract":"In order to investigate trustability of prescribed slope inclinations in design criteria, slope stability analyses were performed on the assumed two embankment sections. Factors of safety against dry condition for the section of 10m high and slope inclination of 1:2 and for the other section of 5m high and slope inclination of 1:1.5 were 1.93 and 2.24 respectively and those values were greater than the design criterion value of 1.50. Factors of safety which were computed through seepage analyses for steady state condition were 1.59 for the section of 10m high and 1.93 for the other section and those values were greater than design criterion value of 1.30. Non-steady state analyses under the same rainfall intensity for the steady state condition were also performed to compare with steady state analyses and it can be seen that factor of safety for the non-steady state condition was converged to the value for the steady state condition as time elapsed. Stability analyses of using piezometric line which were located on the top line of the sections were performed and computed values of factor of safety were 1.20 for the section of 10m high and 1.59 for the other section respectively and it could be seen that the factor of safety for the section of 10m is less than the criterion value of 1.30. According to the results of this study, it can be seen that the slope inclination of 1:1.5 for the slope heights less than 5m and the slope inclination of 1:2.0 for the slope heights between 5m to 10m were safe enough under dry condition and rainfall condition. Nevertheless it can be concluded that slope stability analysis should be performed for the slope over 10m high and with ground water table near the surface of the slope because the factor of safety for that situation was less than the design criterion value.","PeriodicalId":326564,"journal":{"name":"Korea Society of Coastal Disaster Prevention","volume":"63 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114394183","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-10-30DOI: 10.20481/kscdp.2022.9.4.257
Dong Hyun Kim, H. Yoo, Young Jun Bang, Seung Oh Lee
Flooding damage is increasing due to abnormal climates. In particular, in the case of coastal cities, it is necessary to simultaneously consider inundation caused by marine disasters such as storm surge and tsunami as well as inundation due to urbanization. In order to respond to disasters in coastal cities, flood prediction must be preceded. In Korea, the intensity of disasters has been classified by frequency, and flood hazard maps have been produced accordingly. The map is generally derived through numerical simulation, which is based on a scenario, so there is a lot of uncertainty, and it is difficult to predict a disaster for which a scenario has not been established. Because the target range of the coast is wide, the calculation speed of numerical simulation is slow, and a considerable amount of time is required for inundation prediction. It is practically difficult to predict a disaster such as torrential rain in a short period of time. Therefore, in this paper, by using the SIND model, a scientific interpolation model proposed by Kim et al. (2018), the ability to predict the inundation of coastal cities was reviewed and the method of using the model was presented. The SIND model is a short-term prediction model of urban inundation for a desired scenario within the range by using a pre-established inundation forecast map, and can be used for short-term inundation prediction such as torrential rain. To examine the applicability, the accuracy of the flood hazard map derived from the SIND model for coastal cities was analyzed. As a result, it was confirmed that the shape similarity suggested by Kim et al. (2019) was about 0.7 or higher, and it was judged to be appropriate in terms of shape similarity. If the shape similarity technique used for model validation is improved to suit the urban flooding characteristics, the use of the SIND model is expected to increase.
由于气候异常，洪涝灾害正在增加。特别是在沿海城市，需要同时考虑风暴潮、海啸等海洋灾害造成的淹没和城市化造成的淹没。为了应对沿海城市的灾害，必须先行进行洪水预测。在韩国，灾害的强度根据发生的频率进行了分类，并制作了相应的洪水灾害地图。地图一般是通过数值模拟得出的，而数值模拟是基于场景的，因此存在很多不确定性，在没有建立场景的情况下很难预测灾难。由于海岸的目标范围较宽，数值模拟的计算速度较慢，洪水预测需要相当长的时间。在短时间内预测像暴雨这样的灾难实际上是困难的。因此，本文利用Kim et al.(2018)提出的科学插值模型SIND模型，对沿海城市洪水的预测能力进行了综述，并介绍了该模型的使用方法。SIND模型是利用预先建立的洪水预报图，在一定范围内对期望情景的城市洪水进行短期预测的模型，可用于暴雨等短期洪水预测。为验证该模型的适用性，对SIND模型绘制的沿海城市洪涝灾害图进行了精度分析。因此，确认Kim et al.(2019)提出的形状相似度约为0.7或更高，并在形状相似度方面判断为合适。如果用于模型验证的形状相似技术得到改进，以适应城市洪水特征，预计SIND模型的使用将会增加。
{"title":"Application of SIND model for the Prediction of Flooding in Coastal Cities","authors":"Dong Hyun Kim, H. Yoo, Young Jun Bang, Seung Oh Lee","doi":"10.20481/kscdp.2022.9.4.257","DOIUrl":"https://doi.org/10.20481/kscdp.2022.9.4.257","url":null,"abstract":"Flooding damage is increasing due to abnormal climates. In particular, in the case of coastal cities, it is necessary to simultaneously consider inundation caused by marine disasters such as storm surge and tsunami as well as inundation due to urbanization. In order to respond to disasters in coastal cities, flood prediction must be preceded. In Korea, the intensity of disasters has been classified by frequency, and flood hazard maps have been produced accordingly. The map is generally derived through numerical simulation, which is based on a scenario, so there is a lot of uncertainty, and it is difficult to predict a disaster for which a scenario has not been established. Because the target range of the coast is wide, the calculation speed of numerical simulation is slow, and a considerable amount of time is required for inundation prediction. It is practically difficult to predict a disaster such as torrential rain in a short period of time. Therefore, in this paper, by using the SIND model, a scientific interpolation model proposed by Kim et al. (2018), the ability to predict the inundation of coastal cities was reviewed and the method of using the model was presented. The SIND model is a short-term prediction model of urban inundation for a desired scenario within the range by using a pre-established inundation forecast map, and can be used for short-term inundation prediction such as torrential rain. To examine the applicability, the accuracy of the flood hazard map derived from the SIND model for coastal cities was analyzed. As a result, it was confirmed that the shape similarity suggested by Kim et al. (2019) was about 0.7 or higher, and it was judged to be appropriate in terms of shape similarity. If the shape similarity technique used for model validation is improved to suit the urban flooding characteristics, the use of the SIND model is expected to increase.","PeriodicalId":326564,"journal":{"name":"Korea Society of Coastal Disaster Prevention","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127896639","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-10-30DOI: 10.20481/kscdp.2022.9.4.237
In-ki Min, Insik Chun, Jaeseol Shim, D. Ha
Detecting the displacement of a structure by external forces in advance is very important in monitoring the health of the structure. In this study, a kind of sensor fusion technique that combines low-cost GNSS and IMU for structural displacement measurement was established. In addition, a data acquisition program that can secure the synchronous measurement between sensors was created. In order to evaluate the performance of this measurement module, a model experiment gauging the true value by the laser displacement meter was performed, and the results of GNSS single positioning, VRS positioning, precision single positioning (PPP), and sensor merging positioning were compared and analyzed. As a result, it was found that the PPP positioning did not capture the vibration of the structure at all regardless of the waiting time within the excitation condition of the model structure. On the other hand, GNSS single positioning was able to obtain similar results to true values and VRS positioning by pre-processing with an appropriate high-pass filter and the sensor fusion technique.
{"title":"Configuration and Performance Test of GNSS-IMU Sensor Fusion Module for Structural Displacement Measurement","authors":"In-ki Min, Insik Chun, Jaeseol Shim, D. Ha","doi":"10.20481/kscdp.2022.9.4.237","DOIUrl":"https://doi.org/10.20481/kscdp.2022.9.4.237","url":null,"abstract":"Detecting the displacement of a structure by external forces in advance is very important in monitoring the health of the structure. In this study, a kind of sensor fusion technique that combines low-cost GNSS and IMU for structural displacement measurement was established. In addition, a data acquisition program that can secure the synchronous measurement between sensors was created. In order to evaluate the performance of this measurement module, a model experiment gauging the true value by the laser displacement meter was performed, and the results of GNSS single positioning, VRS positioning, precision single positioning (PPP), and sensor merging positioning were compared and analyzed. As a result, it was found that the PPP positioning did not capture the vibration of the structure at all regardless of the waiting time within the excitation condition of the model structure. On the other hand, GNSS single positioning was able to obtain similar results to true values and VRS positioning by pre-processing with an appropriate high-pass filter and the sensor fusion technique.","PeriodicalId":326564,"journal":{"name":"Korea Society of Coastal Disaster Prevention","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130628812","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-07-30DOI: 10.20481/kscdp.2022.9.3.189
Y. Cho
In this study, an active overtopping control system [AWOC] that could effectively supress the flooding caused by storm surge was presented, and numerical simulations to verify the overtopping control effect of AWOC were also carried out using OlaFlow, an OpenFoam-based toolbox. In the AWOC, the floating structure that works as the overtopping controller is submerged in a mild sea, and when exposed to a storm, it rises when the sea level are getting increased due to a storm surge, and as a result, would effectively supress the wave-induced overtopping. Due to these characteristics, the AWOC has the advantage of controlling overtopping at the minimum opportunity cost to preserve the beautiful beach landscape. In the numerical simulation, the motion of a floating structure that rises or descends coupled with the sea level during a storm surge or harsh waves was described by solving the structure motion equation using the water pressure acting on it as an external force. In doing so, Dynamic Mesh was used for the sake of more accurate numerical simulation, in which the computational mesh is updated whenever floating structure moves. Numerical result shows that even though overtopping flow becomes more energetic compared to that in the rubble-mound breaker due to the emhanced reflection after the deployment of AWOC, AWOC could effectively control the enhanced overtopping. It is also shown that an obliquely descending flow from the first quadrant to the third quadrant is formed in the front of AWOC due to the offshore-directed flow commencing from the floating structure of AWOC.
{"title":"Development of Active Wave-induced Overtopping Control System [AWOC] using a Self-adaptive Floating Structure","authors":"Y. Cho","doi":"10.20481/kscdp.2022.9.3.189","DOIUrl":"https://doi.org/10.20481/kscdp.2022.9.3.189","url":null,"abstract":"In this study, an active overtopping control system [AWOC] that could effectively supress the flooding caused by storm surge was presented, and numerical simulations to verify the overtopping control effect of AWOC were also carried out using OlaFlow, an OpenFoam-based toolbox. In the AWOC, the floating structure that works as the overtopping controller is submerged in a mild sea, and when exposed to a storm, it rises when the sea level are getting increased due to a storm surge, and as a result, would effectively supress the wave-induced overtopping. Due to these characteristics, the AWOC has the advantage of controlling overtopping at the minimum opportunity cost to preserve the beautiful beach landscape. In the numerical simulation, the motion of a floating structure that rises or descends coupled with the sea level during a storm surge or harsh waves was described by solving the structure motion equation using the water pressure acting on it as an external force. In doing so, Dynamic Mesh was used for the sake of more accurate numerical simulation, in which the computational mesh is updated whenever floating structure moves. Numerical result shows that even though overtopping flow becomes more energetic compared to that in the rubble-mound breaker due to the emhanced reflection after the deployment of AWOC, AWOC could effectively control the enhanced overtopping. It is also shown that an obliquely descending flow from the first quadrant to the third quadrant is formed in the front of AWOC due to the offshore-directed flow commencing from the floating structure of AWOC.","PeriodicalId":326564,"journal":{"name":"Korea Society of Coastal Disaster Prevention","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127594655","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-07-30DOI: 10.20481/kscdp.2022.9.3.179
Su-Hyun Yang, Tae-Young An, Kyu-Nam Hwang
In this study, the temporal and spatial changes of sea level in Korean coastal zone were analyzed. First, the error value of 1 hour tide data provided by the Korea Hydrographic and Oceanographic Agency was excluded through preprocessing, the analysis of sea level change was performed by considering long period components through low-pass filtering. Using low-pass filtering data, the monthly mean sea level was calculated and the temporal changes of sea level were verified by data fitting using linear fit and multidimensional smoothing spline. The results of linear fit show that the tide tends to rise at most stations. And the results of multidimensional smoothing spline fit show that the increase and decrease of sea level is repeated every year. Although the amounts of change vary every year, sea levels have been repeated seasonally, with sea levels rising in summer and falling in winter. Also, Hovmöller diagram was prepared for the change of sea level in each east, west, and south coast, and the temporal and spatial changes of sea level were analyzed. Compared to the past, recent sea level changes increased in all points. Especially, in the west coast, the sea level increased more in the south (Mokpo) area than in the north (Yeongjong Bridge), and the south (Mokpo) area of the west coast could be a vulnerable area due to the rise in sea level.
{"title":"Analysis of the Temporal and Spatial Changes of Sea Level in Korean Coastal Zone","authors":"Su-Hyun Yang, Tae-Young An, Kyu-Nam Hwang","doi":"10.20481/kscdp.2022.9.3.179","DOIUrl":"https://doi.org/10.20481/kscdp.2022.9.3.179","url":null,"abstract":"In this study, the temporal and spatial changes of sea level in Korean coastal zone were analyzed. First, the error value of 1 hour tide data provided by the Korea Hydrographic and Oceanographic Agency was excluded through preprocessing, the analysis of sea level change was performed by considering long period components through low-pass filtering. Using low-pass filtering data, the monthly mean sea level was calculated and the temporal changes of sea level were verified by data fitting using linear fit and multidimensional smoothing spline. The results of linear fit show that the tide tends to rise at most stations. And the results of multidimensional smoothing spline fit show that the increase and decrease of sea level is repeated every year. Although the amounts of change vary every year, sea levels have been repeated seasonally, with sea levels rising in summer and falling in winter. Also, Hovmöller diagram was prepared for the change of sea level in each east, west, and south coast, and the temporal and spatial changes of sea level were analyzed. Compared to the past, recent sea level changes increased in all points. Especially, in the west coast, the sea level increased more in the south (Mokpo) area than in the north (Yeongjong Bridge), and the south (Mokpo) area of the west coast could be a vulnerable area due to the rise in sea level.","PeriodicalId":326564,"journal":{"name":"Korea Society of Coastal Disaster Prevention","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127515890","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-07-30DOI: 10.20481/kscdp.2022.9.3.207
Joon‐Soo Lee, Ji-Yeong Song, Myung-Hee Park, M. Kwon, I. Han, R. Jung
In this study, a forecast system for the occurrence of cold waters in the eastern coast of Korea was developed by combining the ROMS ocean model and the WRF regional atmospheric model. The 1-day hindcast and 3.5-day forecasts from April 1 to August 31, 2021, successfully reproduced and forecasted the temporal and spatial changes of coastal cold waters. Three case studies with different surface boundary conditions in the ROMS model confirmed that the wind is a primary driver for the occurrence of cold waters in the region. The performance of the ROMS was improved by high-resolution WRF outputs, and through error correction using the water temperature data from the real-time stations, the average RMSE of 9 stations for Forecast Day-3 was 0.73℃, indicating a prossibility of high-precision forecast.
{"title":"Development of Forecast System for the Upwelled Coastal Cold Waters in the Eastern Coast of Korea","authors":"Joon‐Soo Lee, Ji-Yeong Song, Myung-Hee Park, M. Kwon, I. Han, R. Jung","doi":"10.20481/kscdp.2022.9.3.207","DOIUrl":"https://doi.org/10.20481/kscdp.2022.9.3.207","url":null,"abstract":"In this study, a forecast system for the occurrence of cold waters in the eastern coast of Korea was developed by combining the ROMS ocean model and the WRF regional atmospheric model. The 1-day hindcast and 3.5-day forecasts from April 1 to August 31, 2021, successfully reproduced and forecasted the temporal and spatial changes of coastal cold waters. Three case studies with different surface boundary conditions in the ROMS model confirmed that the wind is a primary driver for the occurrence of cold waters in the region. The performance of the ROMS was improved by high-resolution WRF outputs, and through error correction using the water temperature data from the real-time stations, the average RMSE of 9 stations for Forecast Day-3 was 0.73℃, indicating a prossibility of high-precision forecast.","PeriodicalId":326564,"journal":{"name":"Korea Society of Coastal Disaster Prevention","volume":"83 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114813470","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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