THAI NGUYEN UNIVERSITY UNIVERSITY OF AGRICULTURAL AND FORESTRY NGUYEN VU TUAN ANH CHANGE DETECTION AND ANALYSIS OF SHORELINE IN THE NORTHEAST OF TAIWAN USING REMOTELY SENSED DATA BACHELOR THESIS Study Mode : Full - Time Major : Environmental Science and Management Faculty : International Training and Development Center Batch : K44 – AEP THAI NGUYEN - 2016 i Thai Nguyen University of Agriculture and Forestry Degree program Bachelor of Environmental Science and Management Full name NGUYEN VU TUAN ANH Student ID DTN1253180060 Change detection and analysis of shoreline in the northeast of Thesis title Taiwan using remotely sensed data. Tang-Huang Lin and MSc. Nguyen Van Hieu Abstract: This study focuses on the use of remotely sensed data for monitoring coastline changes from seven beaches located at the Yilan County in Taiwan during the 2000 to 2015 period. For the satellite image data processing, in this study we use the Modified Normalized Difference Water Index (MNDWI) as it can efficiently suppress from the water information the noise coming from built-up land, vegetation and soil.
A GIS (Geographic Information System) approach was used for the spatial analysis of coastline change. It was observed that the coastline change in the Yilan County underwent complicated changes during this 15 year period. In this period, the accretion rate in Yilan coastal area was about 1.04 km and the erosion rate was about 0. For the analysis of the changes of the coastlines, multi-temporal Landsat images have been used.
The zones of varying erosion and accretion have important implications for coastal zone management in the Yilan County region. Yilan County, erosion, accretion, MNDWI, remote Keywords sensing, geographic information system Number of pages Date of submission i ACKNOWLEDGEMENT First and foremost, I wish to express my sincere thanks to the boards of Thai Nguyen University of Agriculture and Forestry, Faculty of International Training and Development Center; Advanced Education Program, for giving me this valuable and unforgettable chance studying and working in Taiwan, and more important providing me all necessary facilities, skills and knowledge to complete this bachelor thesis. Furthermore, I want to deeply thanks to Assoc. Tang-Huang Lin (Head of Environmental Remote Sensing Laboratory (ERSL), National Central University, Taiwan) for given permission to accomplish my Bachelor thesis there, and also his contact motivating supervision during my studies in the research group of ERSL, I would like to thank to Ms.
Nicole Wang, who provided me the materials for my research. This study was also supported and instructed by Professor Nguyen Van Hieu (Head of Spatial Research Laboratory, Thai Nguyen University of Agriculture and Forestry, Vietnam). In particular, I place on record my gratitude to him for the multivariate analysis, and the knowledge of some significant change of sandy beaches around the world. Without him, this work cannot be done.
Finally yet importantly, I take this opportunity to record my sense of gratitude to my families and friends who encourage and backing me unceasingly. Thank you very much! Student signature Nguyen Vu Tuan Anh ii TABLE OF CONTENTS LIST OF FIGURES .vi LIST OF TABLES. viii LIST OF ABBREVIATIONS. Shoreline erosion and accretion.
Geographic information system (GIS).1 Collecting and selecting data. Flowchart of methodology. Image pre-processing. Compute Modified Normalize Difference Water Index (MNDWI).
Result of shoreline change detection map. Compute Modified Normalize Difference Water Index (MNDWI). Shoreline change mapping in research area. DISCUSSION AND CONCLUSION.
39 iv LIST OF FIGURES Figure 1. Different types of coasts in Taiwan. Map of study area. Typhoon routes and No.
Relative spectral response (RSR) profiles showing the spectral band difference between Landsat-8 Operational Land Imager (OLI) (solid curve) and Landsat-7 Enhanced Thematic Mapper Plus (ETM+) (short dot curve). The flowchart of analysis procedure. Radiometric correction of Landsat 7. Region of interest.
Dark object subtract. Radiometric correction of Landsat 8. Region of interest. Dark object subtract.
The registration between Landsat image 2000 and 2015. Shoreline change detection map in Yilan county, 2000 - 2015. Shoreline change detection map in Waiao beach and Wushi port, 2000 - 2015. Shoreline change detection map at the south of Toucheng Township, 2000 - 2015.
Shoreline change detection map at the coast of Zhuangwei Township, 2000 - 2015. Shoreline change detection map at the coast of Wujie Township, 2000 - 2015. Shoreline change detection map at the north of Su'ao Township, 2000 - 2015 .37 vii LIST OF TABLES Table 3. Satellite and sensor characteristics .19 viii LIST OF ABBREVIATIONS CPAMI Construction and Planning Agency under the Ministry of the Interior CSRSR Center of Space and Remote Sensing Research DN Digital Number ETM+ Enhanced Thematic Mapper Plus GCP Ground Control Point GIS Geographic information system GPS Global Positioning System MNDWI Compute Modified Normalized Difference Water Index OLI Operational Land Imager RS Remote sensing RSR Relative Spectral Response SWIR Short-wave infrared ix PART I.
Research rationale The total length of Taiwan’s shoreline is approximately 1,100 kilometers including sand, rock, cliff, gravel and reef coasts. Taiwan is frequently attacked by typhoons, particularly serious in the Yilan County of northeastern Taiwan (Figure 1.1), and shoreline erosion is a major concern to local residents. There always exists a panic among residents whenever a typhoon strikes because typhoons inevitably cause a threat to their safety and property. The Yilan County is an alluvial plain surrounded by mountains on three sides, and its east coast borders the Pacific Ocean with a coast length of about 103 km from north to south.
The shoreline of the Yilan County can be divided into three coastal types: Jiaosi fault; Lanyang alluvial; and Suhua fault. The topographical change of the Jiaosi and Suhua faults is little because the geological structures of both faults compose of sea rocks and coastal cliffs. Therefore, this study focuses mainly on the 33-km sandy beach along the coast between Toucheng and Suao (Figure 1.1: Different types of coasts in Taiwan Figure 1.2: Map of study area 1 The 73-km Lanyang River originates from the northern part of the Nanhu Mountain at 3740 m above sea level and winds through the Yilan County from west to east. Its upstream is very steep with rapid flow coupled with a great deal of sand grains.
Torrential rains as well as earthquakes make the river more susceptible to collapse and erosion at the rock base, and thus create an alluvial fan in the midstream region. In the downstream region, the flowing speed of the river turns slow gradually and gravels in various sizes are deposited in the river bed. The river carries mass eroded materials such as mud, sand and gravels, which is one of the main sources that form sandy beaches. Besides, sands drifting with tides result in shoreline changes.
The estuary sand source is determined by the river sediment transport capacity and sand source supply amount (Sun, 2003). Beach stabilization along the Yilan Coast must rely on the sand source from the Lanyang River (Lee et al. Beach erosion makes direct impacts on the tourism economy of the Yilan County because the tourism economy depends highly on beautiful sandy beaches. Monitoring coastal erosion and accretion using remote sensing data is a good solution to overcome the challenges which traditional methods face to in coastal environment.
In assessment of coastal change, in a given period of time, the integration of remote sensing data with other geodata into Geographical Information Systems (GIS) is a powerful tool for quantitative spatial data analysis. The development of Remote Sensing (RS) and Geographical Information systems (GIS) technology can supports mapping and detecting useful information that always updated periodically. Beside some types of satellite imagery with medium 2 resolution, such as Landsat images that downloaded freely from website of USGS (http://earthexplorer.gov)appropriate with the research of erosion or deposition in large area like Yilan county. To gain a better understanding of this vulnerable area and make a good plan for the sustainability, it is crucial to observe and provide the erosional and depositional areas, as well as to study the coastline changes from past to present time.2 Research objectives The objective of this study is to detect the coastline change of Yilan county using multiple space-born remote sensing resources.
The following tasks will be carried out to accomplish the aim of this research: - Detection the shoreline position and identifying of the coastline change in the sandy beaches since 2000 using different approaches; - Investigation and analysis of the reasons of coastline change; - Evaluation of the practically of satellite remotely sensed data in the detection of coastline change, and the assessment of digital image processing and GIS techniques for the quantificative of variation in coastline over study area.3 The requirement - To classify and process spatial data - To know the rate of erosion and accretion in the research area - To be familiarized in GIS software in mapping and analyzing data 3 1. Limitations In this study, the tidal level data is not available, therefore, the shorelines determined by visual and manual techniques are appropriately considered for the reference in validating the final results from satellite imagery. The significance Shoreline erosion is a worldwide problem that causes a major concern to the socio-economic developments in coastal cities for many countries (Chen and Zong, 1998; Genz et al. Bird (1985) indicated that about 70% of the world’s sandy beaches retreated at a rate of 0.
The increasingly intensive human activities in river basins and/or along coasts enlarge coastal erosion areas and aggravate erosion processes, and thus cause land losses: moreover the global climate change in the past decades results in rising sea levels (IPCC, 2007; Church et al., 2008) and accelerates the sand losses of beaches (Bruun, 1962; Davidson-Arnott, 2005). Such threat is particularly severe in Taiwan, an island bearing intense shoreline changes. Recent surveys indicate that more than 80% of the island’s sandy beaches have undergone erosion over the past three decades and coastal erosion has occurred along most of sandy shores at an alarming rate, which becomes an island-wide problem in Taiwan (Hsu et al. Therefore, the environmental protection against beach loss, disaster warning systems for coastal zones and appropriate land management along the coasts are critical issues that need to be carefully studied and adequately developed.
Shoreline erosion and accretion Shorelines are known to be unstable and vary over time. Short-term changes occur over decadal time scales, more or less, and are related to daily, monthly and seasonal variations in tides, currents, wave climate, episodic events and anthropogenic factors. Shoreline movement is a complex phenomenon (signal) from short-term changes (noise). Analysis of shoreline variability and erosion-accretion trend is elementally important to coastal scientists, engineers and managers (Douglas and Crowell, 2000).
Both coastal management and engineering design requires information of the past, current and future shoreline positions. Successful coastal management requires long-term shoreline erosion rates to be determined and forecasts made of future shorelines positions along with the estimates of their uncertainty (Douglas and Crowell, 2000). Shoreline erosion is the wearing away and breaking up of rock along the coast. Destructive waves erode the coastline in a number of ways: Hydraulic action: air may become trapped in joints and cracks on a cliff face.
When a wave breaks, the trapped air is compressed which weakens the cliff and causes erosion; Abrasion: bits of rock and sand in waves grind down cliff surfaces like sandpaper; Attrition: waves smash rocks pebbles on the shore in each other, and they break and become smoother; Solution: acids contained in sea water will dissolve some types of rock such as chalk or limestone. 5 Shoreline accretion is the process of coastal sediment returning to the visible portion of a beach or foreshore following a submersion event. A sustainable beach or foreshore often goes through a cycle of submersion during rough weather then accretion during calmer periods.