|Theme||Visible||Selectable||Appearance||Zoom Range (now: 0)|
ABSTRACT This paper analyzes the distribution of landslides in southern Taiwan due to typhoon or rainstorm from 2009 to 2011. The genetic adaptive neural network (GANN) integrated with texture analysis and geographic information system (GIS) is applied to capture disaster records and surface information for interpretation and classification of satellite images, and then analysis of land use change. The multivariate hazards evaluation method (MHEH) is employed to quantify the weight of the disaster factors, and then build the landslide potential model. Furthermore, this paper also explores the correlation of rainfall events on slope land development, scale and regional characteristics. The results of this study will provide a reference for the development of subsequent slope development strategies and the evaluation of landslide. INTRODUCTION Taiwan is located in the area of typhoon and heavy rainfall. Coupled with mountainous terrain and bad geological conditions, landslides and debris flows occurred often due to concentrated rainfall caused by typhoons or storms. Furthermore, extreme rainfall events resulted in drastic changes in the natural environment of the catchment area, such as mass landslides, river siltation and river bank dike. The unexpected rainfall due to Typhoon Morakot in 2009 resulted in severe landslides, debris flows, and flooding in the southern, central and eastern Taiwan. The frequent landslide disasters affected people's lives and properties and endangered major public works. The overall industrial economic development and transport routes are threatened by the disaster. Therefore, it is necessary to study the prevention and control of the landslide disaster. In this research, the study area is in the watershed area of Laonong River in Kaohsiung City, southern Taiwan. Artificial neural network (ANN) integrated with texture analysis was employed to classify landslide disaster and land use change using satellite images. Genetic algorithm (GA) was used to automatically evolve and train the neural network to obtain the optimal framework of the network, then to acquire disaster records and surface data. The MHEM was used to obtain the weights of the disaster factors, such as natural environment and slope development, and to estimate the landslide potential of the study area. Through the correlation analysis between the landslide history and the regional environmental characteristics in the study area, the interaction between the scale of the landslide and location was also explored. All of these can provide reference for the prevention and countermeasures of landslide disaster.
Abstract With the rapid development of harbor construction in China and in other developing countries, environmental protection and ecological harmony have become decisive factors in harbor planning, design and construction management. Green harbor concept and ecological strategies are important means used to guide the building processes and operation procedures of harbors to save the coastal environment and nature reserve and to make best use of various resources like water, power, land and sea areas. Based on theoretical analysis and practices, this paper summarizes nine evaluation principles and twelve available strategies which help build and manage ecological green harbors and coastal areas during the processes of planning, design, construction and operation management, puts forward the concept and method of dealing with harbor planning as with that of ecological communities, and the ecological theories of diversity and dominance of species can be referenced in planning considerations. Introduction Ecological Green harbor is both an objective and a sustainable means to obtain a good balance between the economic development of the harbor and the society as well as the ecological environment. Due to their large space occupation and big traffic and pollutants convergence, harbors have great impacts on both coastal environments and the adjacent communities. In early stages of harbor building of developed countries, they also met the big challenges of environmental influences and societal impacts when the harbors scales expanded, so they developed the concept of "Green Harbors" in order to control these influences and impacts. According to Chang & Wang, (2012), Driscoll, etc., (2002), Ju, etc. (2010), Wu, (2009), "Green harbors" are those which can be of least impacts on natural and living environment, the implementation of which has brought success in harbors of Long Beach, New York/New Jersey, Vancouver, Sydney, Kaohsiung, etc. Ecological green harbors are those which consider harbors as parts of bigger environmental and ecological systems and make harmony between harbor development and environment quality improvement while raising income of enterprises and the society by means of ecological theories and methods of planning, design and management. Such harbors can be called ecological green harbors.
Chien, Lien-Kwei (National Taiwan Ocean University) | Tseng, Wen-Chien (National Taiwan Ocean University) | Chiu, Shu-Yi (National Taiwan Ocean University) | Chang, Chih-Hsin (National Science and Technology Center for Disaster Reduction)
Abstract With climate change in recent years caused the occurred frequency increasing of extremely waves. Due to sea level rise and the typhoon disasters, it could be caused the pore pressure of seabed may be sustained a build-up state below the coastal structures, and occurring and increasing the risk of the seabed liquefaction. Most of the past related researches followed the earthquake relevant theory to evaluate the dynamic characteristic of cyclic wave loading, including wave induced the single external stress or internal stress, number of cycles in seabed, and pore pressure generation model for earthquake mechanism. Therefore, this study used experimental mechanics and theoretical model to simulate liquefaction behavior under typhoon wave loading with case study of "Zone A" of Kaohsiung Harbor Intercontinental Container Center at second stage project. From the related cyclic triaxial test results, this study proposed an pore pressure generation model for seabed under long-term wave loading by the hyperbolic sine function, and suggest a testing parameter to predict the curve of pore pressure under different test conditions as Tp=0.005, 0.05 and 0.5. The model can be applied in assessment of typhoon wave induced seabed liquefaction potential. The maximum possible liquefied depth is about 6.6m when Tc =1200s in this study area, and provide the well marine geotechnical practical application for seabed stability.
Abstract In 2009, Typhoon Morakot brought heavy rainfall and severely damaged the mountainous area in Taiwan. The Hsien-du-shan rock avalanche occurred at ChiaHsien Township, Kaohsiung County, Taiwan, destroyed the Hsiaolin Village and killed more than 400 local residents. The case highlighted the great importance to identify the location and precursors of a possible rock avalanche. In this study, the initiation of the Hsien-du-shan rock avalanche is simulated by a discrete numerical analysis method, called Discontinuous Deformation Analysis (DDA). The simulation indicates that two slope failures occurred at the Hsien-du-shan rock avalanche due to the geometry of the sliding surface. The sliding rocks and soils can be briefly divided into two groups. The computational results fit well to the local information, which two giant bursts were heart during the slope failure. However, the time interval of the two slope failures in DDA was very short. Therefore, the slope failure can be also considered as a massive one.
Chien, Lien-Kwei (National Taiwan Ocean University) | Tseng, Wen-Chien (National Taiwan Ocean University) | Chen, Bao-Ching (National Taiwan Ocean University) | Hsu, Chao-Min (Taiwan Ocean Research Institute)
ABSTRACT This study discuss the liquefaction potential for seabed soil subjected to earthquake loading and wave action separately on the Kaohsiung Harbor Intercontinental Container Center. The testing sample was obtained by drilling from -1m to -3m beneath surface of seabed at water depth 23.5m. This study simulates two testing conditions. One of which is the torsional shear stress combination of axial stress test during the wave period of 12 seconds. Another is the axial stress test during the earthquake period of 1 second. This study proposes earthquake loading induced the threshold of liquefaction resistance is about 0.19 when Nc=100 times; and wave action induced the threshold of liquefaction resistance is about 0.20 when time of cycles is 1200 seconds. Both thresholds are applicable to seabed soils in Kaohsiung nearshore area. Finally, a method of liquefaction potential assessment for seabed sediment is established. It can obtain the maximum possible liquefied depth by diagram of wave-induced liquefaction analysis for seabed in study area, which is 4.57m beneath the surface of seabed.
Chang, Yin (Tainan Hydraulics Laboratory, National Cheng Kung University) | Li, Hong-Chun (Tainan Hydraulics Laboratory, National Cheng Kung University) | Yang, Ray-Yeng (Tainan Hydraulics Laboratory, National Cheng Kung University)
ABSTRACT: Oysters have strong pollution tolerance; it can survive well in polluted waters. When oyster grows in polluted water, its meat can accumulate heavy metals, which has considerable potential for water clarification. Besides, oyster has very thick calcium carbonate shells, during shell growth; it can absorb and fix CO2, which is also known as an important portion of greenhouse gases; so the oyster culture is able to provide benefits of CO2 reduction. In view of this, we attempted to carry out a pilot oyster culture experiment in the Er-Ren estuary, where located in Southwest of Taiwan. The main purposes of this experiment are to assess the efficiency of water clarification and CO2 reduction by cultured oyster. Preliminary result reveals: the Er-Ren estuary cultured oysters have very high efficiency in Cu and Zn absorption, the Cu concentration in mature oyster meat could reach 34,496 times higher than it in the water of Er-Ren estuary; and Zn concentration could reach 83,500 times. On the aspects of CO2 absorption, after measured oyster shell growth rate, we roughly estimated the CO2 fixing rate is 0.78 kg/m2/day in the Er-Ren estuary oyster culture experiment. INTRODUCTION The history of oyster culture in Taiwan has been more than 300 years, where already has well development oyster culture techniques and industry. One of the most marked examples is the green oyster incident in Er-Ren estuary (Hung et al. 1989; Han and Hung 1990; Han et al. 1993). The estuary of Er-Ren estuary, where locate in the border of Tainan and Kaohsiung county in Taiwan, was once an important oyster farming area. But during 1980s, the Er-Ren estuary water was polluted by neighboring scrap metal recycling industry, and their heavy metal pollutant caused cultured oyster turned green, this is the famous green oyster incident.
Hsiao, D.H. (Department of Civil Engineering, National Kaohsiung University of Applied Sciences) | Hsieh, C.S. (Department of Civil Engineering, National Kaohsiung University of Applied Sciences) | Chang, J.J. (Department of Civil Engineering, National Kaohsiung University of Applied Sciences)
ABSTRACT: The techniques of in-situ investigation, close-range photogrammetry, laboratory tests, stereographic projection and slope stability analysis were used to investigate debris flow at Hsia-Hsinkai Tribe in Liugui town, Kaohsiung on August 8, 2009. Because test results show that 50–80% of the soil aggrades are larger than 2 mm (#10 size), the study area can be considered as gravel debris according to the Taiwan specification. The internal friction angle of the aggrading soil materials ranges from 33.1° to 40.9° using direct shear tests. The outcrops found on site are analyzed with a stereographic projection method. Finally, an analysis of slope stability on the upslope reveals that the deposited geomaterials and rock slope on both sides of the valley are unstable when they are gradually saturated. The heavy precipitation is the primary factor that triggered the occurrence of the debris flow. Topographical variations before and after the 2009 Morakot Typhoon disaster were provided by a three-dimensional digital topography model created by a close-range photogrammetry technique. The elevation variation after the disaster is calculated using a digital elevation model (DEM) and can validate the relation between the source area and the depositional area. In Taiwan, the principal areas of debris flow can usually be divided into three sub-areas: a source area, a flow area and a depositional area. To investigate deposit length and mass flow volume, some independent zones in the study area are divided to verify zones locations after a disaster. It was found that the length of the depositional area is shorter than expected. Hence, the excess pore water pressure between the debris flow and the bedrock could be a significant factor to cause the debris flow. In this paper, we present an explanation of the debris flow based on Newtonian slide theory.
Hsiao, Yu-Hung (Department of Systems and Naval Mechatronic Engineering, National Cheng Kung University Tainan, TAIWAN, China) | Chen, Hsueh-Tzu (Department of Systems and Naval Mechatronic Engineering, National Cheng Kung University Tainan, TAIWAN, China) | Chuang, Shun-Chin (Department of Systems and Naval Mechatronic Engineering, National Cheng Kung University Tainan, TAIWAN, China) | Huang, Min-Chih (Department of Systems and Naval Mechatronic Engineering, National Cheng Kung University Tainan, TAIWAN, China)
The purpose of this study is to develop an image analysis system for coastal observation based on a pan/tilt controlled camera. The system substitutes for multi-directional camera system in large-scale coastal observation. Each image in different pan/tilt angle is considered an independent camera image for subsequent image processing techniques. The system is based on the Direct Linear Transformation algorithm (DLT) to calibrate the intrinsic and extrinsic camera model. In terms of the geometrical relationships relating image and world coordinates, images pixels are transformed to the world coordinates. All of images are integrated in the same coordinates to obtain a composite coastal view. A generalized gradient vector flow active contours model (GGVF snake) is then used to track the coastlines. The database of coastal images obtained can be used to analyze intertidal bathymetry and foreshore topography in short-term and long-term variations. A coastal observation system is installed atop a building roof overlooking the whole bay area of Hsi-tzu-wan in order to study the nearshore morphology variation after a beach restoration program was conducted since April 2008. During the period of observation, several typhoons raid on the bay and scour the beach drastically. In summary, this paper provides new application of a pan/tilt controlled camera setup to replace multi-camera system of coastal observation. The combination of existing techniques, direct linear transformation algorithm and the active contour model, enables us to estimate the nearshore morphology variation during and after the coastal works. INTRODUCTION Hsi-tzu-wan is located near Kaohsiung city at the southwestern coast of Taiwan. It is adjacent to Kaohsiung First Harbor and is a popular scenic spot in Taiwan. The morphology of nearshore zone of Hsi-tzuwan varies drastically during typhoon season in the summer, which is demonstrated by quick change of eroding shorelines and submerged sandbars. The process of accreting shorelines and sandbars is more slowly during the swell seasons.
ABSTRACT The Chi-Chin coastal park, located near Kaohsiung harbor, was built from 1993 to 1997 in southern area of Taiwan. Due to the heavy wave induced settlement inside the park from beach to Art Square during June 1997, the continued soil loss not only endangered the park area, but also resulted in some ground settlement around the front of the Office and Travel Center within the park zone. In order to promptly prevent more ground soil loss, a group of retaining piles was constructed between the beach and Park Office. Until 2003, over almost 6 years, the damage has been not happen in the Chi-Chin coastal park due to the piles installation. From the case, the retaining wall or embedded pile will provide a successful experience for offshore slope subject to wave loadings. Meantime the model derived by minimum energy theory can explain the observed settlement profile in the field. Eventually the full length of pile, even reaches to 14 meter, will provide a good way to mitigate the soil loss of beach while heavy waves attack. INTRODUCTION The Chi-Chin coastal park, located near Kaohsiung harbor, was built from 1993 to 1997 in southern area of Taiwan. Since the heavy wave loadings induced settlement inside the park from beach to Art Square during June 1997, the continued soil loss not only endangered the park area, but also resulted in some ground settlement around the front of the Office and Travel Center within the park zone. In the past study Hsiao and Huang (2000a) stated that the failure mechanism were discussed and analyzed by using the model fluid-liquefaction. It is found that some areas should be liquefied apparently under given parametric conditions. Furthermore, Hsiao and Huang (2000a) found that liquefaction caused from wave loading leads to reduction of passive soil pressure and causing slope slide instability.
Large scale slope movement occurred at communities on hill slope in Kaohsiung areas have been recognized as a serious public concern by the resident at Kaohsiung city in southwestern Taiwan. The administration of Kaohsiung metropolitan containing the area of 2645.60 km includes both Kaohsiung city and county governments. However, Most of hill slope areas are located at Kaohsiung County with 1970.62 km2 which were occupied more than 70% of total Kaohsiung areas. Weak geological structure, uneven distributions of rainfall intensity, steep geomorphology and intensive development were identified as the predominated factors contributing to the slope failures at community on Kaohsiung slope land. Natural disasters damaging properties, infrastructure and human life can be serious all over Kaohsiung metropolitan area. To identify large scale soil mass movement, debris flow and surface runoff erosion by using satellite image processing system and aerial photography implementation on the surface of earth should be required in this project. Applications of GIS integrated with GPS and RS technology would also be necessary and critical for this research. This project was proposed as a three year study to establish a risk assessment model of environmental disasters and set up geo-hazard database systems for the communities on hill slope in Kaohsiung metropolitan. All results can give a fundamental guideline of sediment related disaster prevention. Hopefully, this guideline can help Kaohsiung city and county governments set up their own disaster prevention and mitigation systems to keep urban safe and well development in the future. It is expected that the establishment of this risk model and disaster database system can be used to help a well development of community on urban planning, designing and controlling the hazard mitigation of Kaohsiung area in southwestern Taiwan. INTRODUCTION The problem of slope failure occurred at the community on hill slope is strong related to human activities such as deforestations, land use development and surface mining operation.