(Luận văn thạc sĩ) coastal erosion in phu cat district binh dinh province in the context of climate change and adaptation measures

v LIST OF ABBREVIATIONS MONRE Ministry of Natural Resources and Environment GSO General Statistics Office GIS Geographic information system DSAS Digital Shoreline Analysis System EPR En

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PLEDGE

I assure that this thesis is my research work and has not been published The results of this thesis are honest, not copied from any source and in any form The references to the source materials used in this thesis have been cited following the regulations

AUTHOR OF THE THESIS

NGUYEN THI THUY DUNG

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ACKNOWLEDGMENTS

Foremost, I would like to express my deep gratitude to Professor Yasuhara Kazuya and Associate Professor Do Minh Duc for wholeheartedly guiding and supporting me conducted this research

I would also like to thank Mr Nguyen Huu Hoa, deputy director of Binh Dinh Department of Science and Technology, for helping me collect the data for the thesis May warm thanks also go to Ms Dinh Thi Quynh for her kind help, academic advice, and support during the study

I also want to express my thanks to the MCCD program for all support and sharing Last but not least, I would like to thank my family for always being my spiritual support and encouragement me to overcome all difficulties to complete this thesis

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CONTENT

LIST OF TABLES i

LIST OF FIGURES ii

LIST OF ABBREVIATIONS v

CHAPTER 1: INTRODUCTION 1

1.1 Rationale of the study 1

1.2 Objectives of the research 2

1.3 Objects and Scope of the research 3

1.4 Research questions and hypotheses 3

1.5 Significance of the research 3

1.6 The novelty of the research 3

1.7 The structure of the thesis 3

1.8 Review related literature and studies 4

1.8.1 Definitions 4

1.8.2 Overview of studies on coastal erosion 6

1.8.3 Overview of adaptation measures 8

1.9 Site descriptions 14

1.9.1 Location and natural conditions 14

1.9.2 Socio-economic condition 18

1.9.3 Climate change in Binh Dinh 21

CHAPTER 2 METHODOLOGY 27

2.1 Approaches 27

2.2 Data collection 28

2.2.1 Primary data 28

2.2.2 Secondary data 30

2.3 Methods 34

2.3.1 Qualitative methods 34

2.3.2 Quantitative methods 35

CHAPTER 3 RESULTS AND DISCUSSION 43

3.1 Results 43

3.1.1 Sediment distribution 43

3.1.2 UAVs photo processing 44

3.1.3 Shoreline change analysis 44

3.1.4 Preliminary assessment of the causes of coastal erosion 60

3.1.5 Shoreline change prediction 63

3.1.6 Adaptation measures 72

3.2 Discussion 85

CHAPTER 4 RECOMMENDATIONS 90

4.1 Recommendation for using research results 90

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4.2 Further research orientations 90

CONCLUSIONS 91

REFERENCES 93

APPENDIX 98

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LIST OF TABLES

Table 1 1: Research objectives, questions and hypotheses 3

Table 1 2: Structural solutions to prevent coastal erosion 9

Table 1 3: Anti-erosion solutions of Cua Dai beach 11

Table 1 4: Average rainfall in years at Phu Cat station 16

Table 1 5: Wave and current characteristics at the De Gi estuary 17

Table 1 6: Population of 5 coastal communes of Phu Cat district 18

Table 1 7: Land use status of 5 coastal communes of Phu Cat district in 2013 19

Table 1 8: List of storms that landed or affected Binh Dinh province (1988-2017) 24

Table 2 1: Landsat 8-9 OLI/TIRS (L2SP) Band Specifications 31

Table 2 2: Landsat 4-5 TM (L2SP) Band Specifications 31

Table 2 3: List of satellite images used in the study 32

Table 2 4: Summary of data used in the research 33

Table 2 5: List of research methods 34

Table 3 1: Shoreline change rate in NE monsoon season (1989-2016) 47

Table 3 2: Shoreline change rate in NE monsoon season (1989-1999) 48

Table 3 3: Shoreline change rate in NE monsoon season (1999-2008) 49

Table 3 4: Shoreline change rate in NE monsoon season (2008-2016) 50

Table 3 5: Shoreline change rate in SW monsoon season (1989-2014) 52

Table 3 6: Shoreline change rate in SW monsoon season (1989-2000) 53

Table 3 7: Shoreline change rate in SW monsoon season (2000-2008) 54

Table 3 8: Shoreline change rate in SW monsoon season (2008-2014) 55

Table 3 9: Shoreline change in 1989 56

Table 3 10: Shoreline change in 1993 57

Table 3 11: Shoreline change in 2008 58

Table 3 12: Shoreline change rate in 2014 59

Table 3 13: Estimation of shoreline retreat due to SLR in Cat Khanh beach 69

Table 3 14: Estimation of shoreline retreat due to SLR in Cat Hai beach 70

Table 3 15: Estimation of shoreline retreat due to SLR in Vinh Hoi beach 71

Table 3 16: Estimation of shoreline retreat due to SLR in Trung Luong beach 71

Table 3 17: The group of non-structural solutions 72

Table 3 18: Features of Phu Cat coastal dunes 74

Table 3 19: Activities of exploiting dunes along Phu Cat coastline 74

Table 3 20: List of policies related to coastal erosion issue in Binh Dinh province 74

Table 3 21: Preliminary assessment of adaptive capacity for Phu Cat district 75

Table 3 22: Compare the results of the study with related studies 87

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LIST OF FIGURES

Figure 1 1: Phu Cat coast was eroded in 2017 2

Figure 1 2: The coastal zone 4

Figure 1 3: Headland type concrete structures to protect the coastal area from erosion in Ibaraki, Japan 9

Figure 1 4: Embankment in Phan Thiet beach 12

Figure 1 5: T-groynes and break water in Ro hamlet, Phu Yen province 12

Figure 1 6: Tam Quan embankment was broken in 2019 13

Figure 1 7: Casuarina trees along the coast in An Quang Dong village, Cat Khanh commune, was uprooted in 2017 13

Figure 1 8: Location map of the study area 14

Figure 1 9: Topography map of the study area 15

Figure 1 10: Wave rose at the De Gi estuary a) September 2012 and b) June 2013 17

Figure 1 11: Economic structure of Phu Cat district 19

Figure 1 12: Some beautiful beaches in the Phu Cat district 21

Figure 1 13: Temperature trend in Binh Dinh province from 2006 to 2019 22

Figure 1 14: Change of annual rainfall (%) ( 1958-2014) 22

Figure 1 15: The influence of storm Linfa along with heavy rain caused flooding in many areas in Binh Dinh province 23

Figure 1 16: Path of storms that hit the East Sea and Vietnam in the past 70 years 23

Figure 1 17: Average Sea level at Quy Nhon station 26

Figure 2 1: The research framework 28

Figure 2 2: DJI Phantom 4 Advanced 29

Figure 2 3: UAV photos of Phu Cat coastal area, captured by the DJI Phantom 4 Advance+ 29

Figure 2 4: Topographic maps of study area published by U S Army Topographic Command 30

Figure 2 5: UAV photos processing flowchart 35

Figure 2 6: Sand samples after drying (Left) and sampling location (Right) of coastal sand in Phu Cat district 36

Figure 2 7: Particle size classification by manual sieving method 36

Figure 2 8: Illustration of the Bruun Rule, by the Scientific Committee on Ocean Research (1991) 37

Figure 2 9: Parabolic bay-shape model (after Hsu and Evans, 1989) 38

Figure 2 10: The logical framework 42

Figure 3 1: Particle size distribution along Phu Cat coastline 43

Figure 3 2: UAV images interpretation results (overlap on Google Earth background)44 Figure 3 3: Four research segments 45

Figure 3 4: Result of the shoreline extraction 46

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Figure 3 5: Erosion - Accretion classification (EPR) 47

Figure 3 6: Shoreline change map (EPR) in NE monsoon season (1989-2016) 48

Figure 3 7: Shoreline change map (EPR) in NE monsoon season (1989-1999) 49

Figure 3 8: Shoreline change map (EPR) in NE monsoon season (1999-2008) 50

Figure 3 9: Shoreline change map (EPR) in NE monsoon season (2008-2016) 51

Figure 3 10: Shoreline change map (EPR) in SW monsoon season (1989-2014) 52

Figure 3 11: Shoreline change map (EPR) in SW monsoon season (1989-2000) 53

Figure 3 12: Shoreline change map (EPR) in SW monsoon season (2000-2008) 54

Figure 3 13: Shoreline change map (EPR) in SW monsoon season (2008-2014) 55

Figure 3 14: Map of shoreline change (NSM) in 1989 57

Figure 3 15: Map of shoreline change (NSM) in 1993 58

Figure 3 16: Map of shoreline change (NSM) in 2008 59

Figure 3 17: Map of shoreline change (NSM) in 2014 60

Figure 3 18: Aquaculture area along De Gi beach 62

Figure 3 19: Shoreline prediction for the next10 years and 20 years 64

Figure 3 20: Predicted SEP of De Gi beach (1965) 65

Figure 3 21:Predicted SEP of De Gi beach (2019) 65

Figure 3 22: Predicted SEP of the beach near Ong Lop headland (2019) 66

Figure 3 23: Predicted SEP of Cat Hai beach (2019) 67

Figure 3 24: Predicted SEP of Vinh Hoi beach (2019) 67

Figure 3 25: Predicted SEP of Trung Luong beach (2019) 68

Figure 3 26: Four representative cross-sections of Phu Cat shoreline 69

Figure 3 27: Representative cross-section of Cat Khanh beach 69

Figure 3 28: Representative cross-section of Cat Hai beach 70

Figure 3 29: Representative cross-section of Vinh Hoi beach 71

Figure 3 30: Representative cross-section of Trung Luong beach 71

Figure 3 31: De Gi jetty with tetrapod structure 79

Figure 3 32: Dania beach with jetty and groynes 79

Figure 3 33: Dania Beach, Florida, USA (viewed from the North) 80

Figure 3 34: Conservation of natural vegetation combined coastal setbacks in Dania Beach, Florida, USA 80

Figure 3 35: An example of native vegetation conservation on the coastal sand dunes in India 81

Figure 3 36: Proposal on the process of integrating coastal erosion into construction planning 82

Figure 3 37: Orientation for construction planning in Phu Cat district (browsed) 83

Figure 3 38: Mainstreaming anti-erosion measures into planning 84

Figure 3 39: Parabolic model for T-groins (tentative) at the beach of An Quang village (Cat Khanh commune) 85

Figure 3 40: Comparison of erosion rate (EPR index) in NEMS and SWMS 86

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LIST OF ABBREVIATIONS

MONRE Ministry of Natural Resources and Environment

GSO General Statistics Office

GIS Geographic information system

DSAS Digital Shoreline Analysis System

EPR End Point Rate

LR Linear Regression

IPCC Intergovernmental Panel on Climate Change

USGS United States Geological Survey

UNFCCC United Nations Framework Convention on Climate Change

IWRM Integrated Water Resources Management

CZM Coastal Zone Management

FAO Food and Agriculture Organization

EC The European Commission

ICAM Integrated Coastal Area Management

ICZM Integrated Coastal Zone Management

PBSE Parabolic Bay Shape Equation

HBB Headland-bay beaches

NEMS North-east monsoon season

SWMS South-west monsoon season

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CHAPTER 1: INTRODUCTION

1.1 Rationale of the study

Climate change is becoming the biggest challenge facing humanity on a global scale According to the Global Climate Risk Index 2021 (CRI) report, Vietnam ranked

13 out of 180 countries [1] Recognizing the dangers of climate change, on April 22 at the United Nations headquarters in New York (USA), Vietnam and about 180 countries signed the Paris Agreement, officially step into the fight against global climate change [2]

In Vietnam, in the past 50 years, the average temperature has increased by 0.5÷0.7oC, the sea level has risen about 20cm Extreme weather events, especially storms, floods, and droughts, are becoming increasingly severe According to the climate change and sea-level rise scenarios released in 2016 by MONRE, the average temperature in Vietnam could rise to 4oC, and sea level could rise 1 m by 2100 [3] Vulnerable areas include coastal areas (especially areas often affected by storms, storm surges, floods); mountainous areas, especially places where flash floods and landslides often occur

With a coastline of 3,260 km, Vietnam's marine economy is developing strongly However, climate change and sea-level rise would increase the risk of inundation, erosion, and salinity, affect the economy, people's livelihoods, threaten or destroy the coastal technical infrastructure system

At present, coastal erosion has become common all over the coast of Vietnam, from the North to the South According to research by Pham Huy Tien et al (2002), the total number of eroded banks is 397, with a total length of 920.21km The average erosion rate is about 5-10m/year, but could reach 50-100m/year, even 200-250m/year

in short intervals [3]

Binh Dinh is a coastal province located in Central Vietnam, borders the East Sea with a coastline of 134 km Binh Dinh has significant advantages by nature and great potential for the development of the marine economy

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According to the Chairman of Binh Dinh Provincial People's Committee, the most erosion hot spot is Phu My district with four communes My Duc, My Thang, My An and My Thanh; including the total length of the landslide is 3,900m; affecting the life and production of 2,520 households In Phu Cat district, coastal erosion occurred in An Quang village, Cat Khanh commune, with over 520m, affecting 550 families In 2015 and 2017, coastal erosion uprooted many casuarina trees, and waves intruded inland in some places over 70m In Cat Tien commune, the sea firmly invaded Trung Luong village over 500m, affecting 495 households [4] (Please see Figure 1.1)

(Source: Internet)

Figure 1 1: Phu Cat coast was eroded in 2017

Realizing the potential risk caused by the impacts of climate change, in June 2020, Department of Science and Technology of Binh Dinh province proposed to order an independent national science and technology mission: "Research on integrated technology solutions to strengthen resilience and ability to proactively respond to erosion and accretion disaster of coastal villages and communes of Binh Dinh province

in the context of urbanization and climate change"

From the above practice, the topic "Coastal erosion in Phu Cat district, Binh Dinh province in the context of climate change and adaptation measures" was selected for research to analyze coastal erosion under the impacts of climate change; and propose adaptation solutions in accordance with the local adaptive capacity

1.2 Objectives of the research

This study has three main objectives: to analyze shoreline changes, to forecast shoreline changes in the context of climate change, and to propose adaptation measures

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1.3 Objects and Scope of the research

- Research object: shoreline changes (focus on coastal erosion)

- Research scope: the entire coastal strip in Cat Khanh, Cat Thanh, Cat Hai, Cat Tien and Cat Chanh

1.4 Research questions and hypotheses

Table 1 1: Research objectives, questions and hypotheses

[O1]: Analyze shoreline

[O2]: Predict shoreline

change

[Q2]: How would shoreline change?

[H2]: Shoreline would continue to recede under CC

[O3]: Propose

anti-erosion measures

countermeasures could respond to coastal erosion?

[H3]: For the long-term preventing coastal erosion and responding to climate change, a combination of hard and soft measures is needed

1.5 Significance of the research

Scientific significance: This study contributes to enriching research series on

coastal erosion for coastal provinces and cities of Vietnam in the context of climate

change

Practical significance: The study provides some analysis of shoreline change

(focus on coastal erosion) in the Phu Cat district and some anti-erosion countermeasures based on existing local conditions

1.6 The novelty of the research

This study is the first study on the erosion phenomenon in Phu Cat district This is also the first study to integrate coastal erosion issues into spatial planning and propose anti- erosion solutions based on local adaptive capacity

1.7 The structure of the thesis

The thesis, apart from the Conclusions, consists of four chapters as below:

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(Source: Pearson Prentice Hall, Inc, 2009)

Figure 1 2: The coastal zone

In the Ramsar handbooks for the use of wetlands, 4th edition, the coastal zone is

an area with a relatively narrow interface between land and sea, where ecological and functional processes are complex and intensive, depending on the interaction between land and sea The coastal zone contains terrestrial and aquatic ecosystems closely linked to the socio-economic system, forming complex functional units [6]

In the book " Vietnam coastal zone - structure and natural resources", the author

Le Duc An claimed that the coastal zone consists of two ribbon spaces embracing the shoreline, the coastal strip and the shallow coastal strip edge The inner boundary of the coastal strip is the administrative boundary of the coastal districts and cities, and

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* Coastline:

The coastline is the contact line dividing the land from the coastal water bodies [6] In general, the coastline is the boundary between land and sea This boundary is also not stationary but always moves under waves, tides, currents, etc

The coastline is the highest boundary of waves during interaction with the mainland This boundary is usually cliffs, dunes or terrestrial vegetation [9]

1.8.2 Overview of studies on coastal erosion

1.8.2.1 Overview of coastal erosion studies in the world

Long times ago, people gathered in the coastal plains to take benefits from coastal resources As a result, coastal erosion took place and the history of human development based on the sea

According to the IPCC report, the average reverse speed of the shoreline of Louisiana, USA, was from 0.61 m / year in the period 1855-2002 to 0.94 m / year since 1988 [13] In China, coastal erosion also accounts for nearly 50% of the coastline For example, the Yellow Sea eroded 49%, the East China Sea eroded 44%, the coast of Guangdong province and Hainan Island erodes 21% [13]

Traces of anti-erosion structures such as ports and breakwaters constructed at the Nile river-mouth around 2500 BC and today's anti-erosion protection works show that studies of coastal erosion had a long time of implementation Interaction between land and sea The coastal zone contains terrestrial and aquatic ecosystems closely linked to the socio-economic system, forming complex functional units in ecology

a) Research on coastal erosion based on geological, geomorphological, and hydrodynamic viewpoints

Strahler (1952) and Hack (1960) studied topographical evolution, analyzed the

processes of erosion and accretion based on morphological dynamics [14] [15]

Zencovich (1962) examined the evolution of the coast concerning the factors that form and change the coastal topography and the role of climate and coastal vegetation in geomorphologic development [16] Other authors such as Eliot and Clark (1982), Thom and Hall (1991), McLean and Shen (2006) studied coastal erosion based on beach profiles [17] [18] [16]

b) Research on coastal erosion concerning climate change

Bruun (1962) gave a view (known as the Bruun Rule) on the impact of sea-level rise on the coast, claiming that the beach's horizontal profile had reached a dynamic equilibrium when the sea level is stable Meanwhile, Zhang et al (2004) believed that

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The era since 1990 is the period of a combination of traditional geomorphological research, geomorphic technology, and modelling in coastal erosion analysis For example, Kay (1990) assessed coastal erosion under SLR and GHE effects [21]; Corwell (1991) analyzes the trend of shoreline changes and analyzes the uncertainty of volatility assessment techniques [22] Cambers (1998) studied coastal retreat for coastal planning investigative methods associated with satellite image interpretation [23]; Woodrrofe (2002) evaluated the evolution of coastal topography, sediment changes by traditional investigative methods related to satellite image interpretation [24]

The Coastal Vulnerability Index (CVI) trend has become popular since the beginning of the twenty-first century Authors represented this approach include Gornitz et al (1994) [25], Thieler and Hammar (1999) [26], Dwarakish et al (2009) [27], Özyurt and Ergin (2009) [28], etc

Currently, studies of coastal evolution have come a long way by combining many different methods such as satellite image interpretation, statistics, mathematical

modelling, hydrodynamic modelling, etc

1.8.2.2 Overview of coastal erosion studies in Vietnam

In Vietnam, research on coastal erosion has only been popular since the 90s of the

20th century until now Studies on coastal erosion in central Vietnam are also of interest to domestic scientists

The foundation research on coastal evolution in Vietnam is a State-level research project of author Nguyen Thanh Nga, with code KT-03-14, which assessed the current

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state and the causes of coastal erosion in Vietnam and proposed technical solutions Following that, the studies of Cu et al (2001, 2003, 2005) [29], Nguyen Manh Hung (2010) [30], Pham Huy Tien et al (2005) [31], Mimura (2008) [32], Le Phuoc Trinh et

al (2011) [33], gave more views on the trend of coastal erosion and accretion in Vietnam In which, some research proposed the application of remote sensing to create sensitive coastal maps Most studies have evaluated the current state of the volatility (erosion and accretion) of Vietnam's coastline and the future trend of the increase related to global climate change (sea-level rise, storm surge)

In terms of research methods: Until now, Vietnamese scientists mainly used geomorphology research methods such as morpho-dynamic, hydrodynamic, and analysis methods based on topographic maps, aerial photography, remote sensing images, etc The above studies all use at least one of these research methods to analyze shoreline changes

For Binh Dinh province, up to now, in addition to the studies on coastal erosion in the Central region mentioned above, most studies have focused on the analysis of the accretion phenomenon of some estuaries such as the Tam Quan estuary, De Gi estuary such as Do Minh Duc et al (2017) [34], Dinh Thi Quynh (2017) [35]

There was one study conducted by Vo Ngoc Duong et al (2019) published in the proceedings of the 10th International Conference on the coasts of Asia and the Pacific (APAC 2019) [37] This study aimed to identify shoreline fluctuations in Binh Dinh province from 1975 to 2017 used Remote sensing technology and DSAS application

1.8.3 Overview of adaptation measures

1.8.3.1 Adaption measures in the world

The world has had many works to solve the problem of the estuary and coastal erosion Countries with advanced marine science and technology have long built estuary and coastal protection works Those solutions are mainly around two main types: construction and non-structural Materials used are diverse, from reinforced concrete, steel piles to geo-bags, geo-tubes, etc For example, the coastal protection method used in India is the construction of the Rubble mound Seawall Furthermore,

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groynes and detached seawall have been used in some areas In addition, artificial beach nourishment is also adequate

More flexible solutions such as

using beach nourishment or

underground breakwaters have also

been effective in tourist and resort

areas worldwide

Currently, the combination of

hard and soft options has become more

popular recently for optimum results

because they have weaknesses when

used separately

(Source: [36])

Figure 1 3: Headland type concrete structures to protect the coastal area from

erosion in Ibaraki, Japan

1.8.3.2 Adaption measures in Vietnam

Over the years, under climate change and sea-level rise, river erosion and coastal erosion have become more complicated As a result, with an increasing trend in both scope and intensity, threatening people's livelihood, infrastructure, and coastal areas, negatively affecting socio-economic development

Many prestigious Vietnamese research institutions such as the Institute of Geography, the Institute of Science and Technology of Irrigation, the Institute of Oceanography, Nha Trang have been studying coastal erosion prevention following independent state-level projects or research projects of each locality [37]

According to the state-level project KT.03.14 (N.T.Nga et al., 1995), many structural solutions to prevent coastal erosion have been proposed (Please see Table 1.2)

Table 1 2: Structural solutions to prevent coastal erosion

(Source: KT.03.14)

1 Hai Phong Groins+ beach nourishment Hai Phong Oceanography

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The experience of preventing coastal erosion and accretion in countries worldwide and Vietnam have shown that avoiding coastal erosion and accretion is highly complicated, requiring synchronous and comprehensive solutions Solutions from macro to micro scale, using structural and non-structural solutions for each specific period

The solutions at the macro level lie in the content of regional management and the master plan for socio-economic development; The structural solutions should be studied based on the integrated and interdisciplinary forecast of coastal erosion in 20,

30, or 50 years under the impact of climate change

1.8.3.3 Adaption measures in Central Vietnam

The Central Coast region, due to its topographical characteristics, is a place subject to many natural disasters such as storms, floods, droughts, riverbank erosion, coastal erosion, etc Especially, coastal erosion in recent times is complicated, causing much damage Moreover, upstream exploitation of river basins also contributes to the problem Therefore, the protection and prevention of coastal erosion here are becoming an urgent requirement in Vietnam promoting socio-economic development

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in the coastal strip Erosion still occurs in the central coastal zone of Viet Nam and preventive measures such as sea dykes, revetments, and tree plantations have been implemented in many coastal areas

According to scientific reports on coastal erosion, the Central Coast of Vietnam has 397 eroded sections with a total length of over 920 km, of which erosion occurs in

233 areas with a total distance of up to 492 km Particularly, Quang Nam province has

20 erosion sections of nearly 19 km; Quang Ngai province has 27 sections over 35 km; Binh Dinh has 33 sections of almost 34 km; and Phu Yen province has 25 areas 21 km

of erosion [37] As a result, localities heavily affected by erosion have been rushing to find solutions to this problem

Take Cua Dai as an example; a decade has passed since the first appearance of coastal erosion in Cua Dai beach Until now, Cua Dai beach has eroded about 160 meters inland The erosion rate from 2014 slowed down, but the situation has not improved much, although the capital from the budget alone has poured into "rescuing" the coast of more than 250 billion VND Many efforts and synchronous solutions have been deployed but have not been effective (Please see Table 1.3); the beach is still necrotic and disappearing day by day

Table 1 3: Anti-erosion solutions of Cua Dai beach

Evaluation Effective Ineffective Effective Ineffective

(Source: Internet)

In Binh Thuan, the province has invested in many coastal protection works such as rock-fill embankment (Phu Hai coastal area), sandbag embankment (I or T shape) in Ham Tien‟s tourist area, etc The construction works have brought many practical effects, such as preventing erosion and ensuring a beautiful landscape

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(Source: Internet, Google Earth)

Figure 1 4: Embankment in Phan Thiet beach

In Phu Yen province, anti-erosion works have proved effective From figure 1.5,

in March 2015, the distance from point 1 to the edge of the shoreline was about 45.8m

In 2016, Phu Yen provincial government began to build the first T-groins Distance from point 1 to point 2 in March 2016 was 78.3m After four years, in 2020, the coast has been filled with sand, at a speed of about 32m/5yrs From that success, in 2019, more T-groins and breakwaters continue to be built for other areas

(Source: Google Earth)

Figure 1 5: T-groins and break water in Ro hamlet, Phu Yen province

1.8.3.4 Adaption measures in Binh Dinh province

The whole province of Binh Dinh has about 134 km of coastline Along the coast

of Binh Dinh exist estuaries such as: Tam Quan estuary, An Du estuary, Ha Ra estuary, De Gi estuary and Quy Nhon estuary

Regarding structural constructions, currently, Binh Dinh has four sea dike systems: Tam Quan (6 km), De Gi (16.9 km), Hoai Huong - Hoai My (4.5 km), and East (47 km) However, the existing dyke system could withstand storms class 7÷8 when there is no high tide [38] Therefore, when extreme weather events occur, especially massive storms, these structures are not strong enough to withstand

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(Source: Internet)

Figure 1 6: Tam Quan embankment was broken in 2019

According to Binh Dinh Department of

Agriculture and Rural Development, from

November to January 2017, due to the

influence of the Northeast monsoon

combined with high tides, the coast of De

Gi (An Quang Dong village) eroded As a

result, the sea invaded about 30-70m

inland, extending from the base of the De

Gi welding torch to the South about 500m;

then, from February to April, the accretion

returned [38]

(Source: Internet)

Figure 1 7: Casuarina trees along the coast in An Quang Dong village, Cat Khanh commune, was uprooted in 2017

To ensure the stability of the coast, the construction of embankment protection requires a large amount of money Therefore, the solution of planting casuarinas with denser density to prevent erosion is implemented instead

Regarding non-structural solutions, Binh Dinh Department of Natural Resources and Environment (DONRE) in 2018 issued a draft list of areas that must establish a coastal protection corridor in Binh Dinh province The De Gi shoreline segment (near

De Gi fishing port) is considered the most severe erosion risk in the Phu Cat coastal area

On January 25, 2019, Binh Dinh Provincial People's Committee issued Decision

No 296/QD-UBND approving the list of areas where the coastal protection corridor of Binh Dinh province must be established [39] According to this decision, the total

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length of the protected area is 100,817 m, with 43 sections in 28 communes and wards

in the districts of Hoai Nhon, Phu My, Phu Cat, Tuy Phuoc, and Quy Nhon city

Shortly after, Binh Dinh province issued Decision No 4383/QD-UBND dated November 2019 on approving the width and boundaries of the coastal protection corridor of Binh Dinh province [40], to detailed Decision No 296/QD-UBND above

1.9 Site descriptions

1.9.1 Location and natural conditions

1.9.1.1 Geographical location

According to the website of Phu Cat district [41], Phu Cat is a coastal plain district

of Binh Dinh province, located on 13o54'N- 14o32'N and 108o55'E- 109o05'E

- The North and the Northwest border Phu My district and Hoai An district

- The South borders An Nhon town

- The West and the Southwest border the districts of Vinh Thanh and Tay Son

- The East borders the East Sea with a length of 35 km

- The Southeast borders Tuy Phuoc district and Quy Nhon city

Figure 1 8: Location map of the study area

The Phu Cat coastal strip is about 30 kilometres in length, stretches through 5 communes Cat Khanh, Cat Thanh, Cat Hai, Cat Tien and Cat Chanh

Phu Cat district has a pretty favourable position for economic development associated with benefits from the sea

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1.9.1.2 Topography - geomorphology

Phu Cat's topography is diverse, including deltas, low mountainous areas, and coastal lagoons in Cat Minh, Cat Khanh, and Cat Thanh Cat Chanh commune and Cat Tien commune located in the south of Ba mountain

Hills and mountains in this area account for more than half, but most are bare hills

South of De Gi estuary, the coastline is shaped, concave to the West The intertidal topography in the study area is quite steep, with

arc-an average width of 30 - 50 m

With a total length of more than 20km, the beaches of Phu Cat district have much potential for tourism development but not yet fully exploited

1.9.1.3 General climate

Located in the tropical monsoon climate area, the climate of Phu Cat characterized

by hot, humid, and rainy There are two distinct seasons in the year, the dry season and the rainy season The dry season is from December to August, the rainy season from September to November The dry and hot southwest wind operates from March to August From September to February of the following year, it is influenced by the northeast wind, accompanied by drizzling and cold rain

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Air temperature in the region is lowest in winter (November to March) and highest

in summer (May to August) The average temperature in many years is about 24.3oC The difference in temperature during the day is from 7 to 10oC

Average relative humidity for many years ranges from 85 to 90% Average evaporation for many years is in the range of 1,200 -1,300mm

Rainfall in Binh Dinh year is very irregular The average annual precipitation measured in the place with the most rainfall and the least amount of rain has a big difference Observation results for many years showed that the rainfall recorded in

October and November is the largest

Table 1 4: Average rainfall in years at Phu Cat station

According to [35], from November of last year to April of next year, the wave has

a Northeast direction on the continental shelf of Binh Dinh May is the period of changing seasons; the waves are unstable and weak From June to September, the southwest wave prevails Other directional waves have minor, insignificant frequencies The maximum observed wave height is 12m In summer, the average wave height is 1.2 - 1.7m In winter, the average height of waves is 1m, of rogue waves is 2.2m; In summer, the average wave height is 0.5 m; rogue waves are 2.3 m Measuring waves is quite complicated According to the research by Duc et al (2013) [42], the wave characteristics measured with an AWAC system Table 1.5 and Figure 1.10 showed that the Northeast-wave was dominant in September 2012, and the East-wave dominated in June 2013

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Table 1 5: Wave and current characteristics at the De Gi estuary

Dominant wave direction 61.7° (NE) 111.2° (SE)

During the rainy and stormy season, the surface flow through Binh Dinh is mainly

in the East and Southeast directions, the West flow accounts for a tiny proportion

c) Tide

According to [43], the tides of Binh Dinh are mainly irregular diurnal tides; the number of diurnal days in a month ranges from 18 to 26 days Thi Nai lagoon and river mouth have the same tidal regime as Quy Nhon coastal area; however, tidal amplitude

in the lagoon area is smaller than tidal amplitude in the coastal region

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The tidal amplitude in the lagoon is from 1.3m to 1.4m, while the tidal amplitude

in the sea at the same period is 1.5m to 2.0m The tidal peaks in the lagoon and at Quy Nhon station did not change significantly

1.9.2 Socio-economic condition

1.9.2.1 Population and Labor

According to Binh Dinh Statistical Office, the total area of Phu Cat district is 680.49 km2, with an average population of 193,262 people Phu Cat has 18 commune-level administrative units, including 17 communes of Cat Son, Cat Lam, Cat Hiep, Cat Hanh, Cat Tai, Cat Minh, Cat Khanh, Cat Thanh, Cat Hai, Cat Tien, Cat Chanh, and Cat Thang, Cat Hung, Cat Nhon, Cat Tuong, Cat Trinh, Cat Tan, and 01 towns is Ngo May Town

The study area includes five communes: Cat Khanh, Cat Thanh, Cat Hai, Cat Tien,

and Cat Chanh, with the population shown in table 1.5

Table 1 6: Population of 5 coastal communes of Phu Cat district

1.9.2.2 Economy

According to the Phu Cat district socio-economic report, the total value of production fields increased compared with previous years The proportion of sectors in the economic structure is Agriculture - Forestry - Fishery accounts for 25.32%;

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Cat Chanh

2.5 River, stream land and

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Khanh

Cat Thanh Cat Hai Cat Tien

Cat Chanh

(Source: Binh Dinh Department of Statistic) From table 1.6, it can be clearly seen that unused land still accounts for a large proportion

The coastal area of Phu Cat district extends from Cat Khanh commune to Cat Chanh commune In general, this place brings together beautiful and unspoiled beaches, almost unaffected by human activities Therefore, the Phu Cat district converges many conditions for economic development in association with the sea Potentials of Phu Cat district include developing diversified agricultural production from cultivation, husbandry, fisheries, afforestation, tourism and services with beautiful landscape and convenient transportation systems (Phu Cat International Airport, 1A National highway), developing human resources, etc

With De Gi lagoon - one of the significant lagoons of our country, the coastal area

of Phu Cat district plays an essential role in the economic development process The current aquaculture area is 391 ha Total production of fishery and aquaculture in 2012 reached 35,000 tons In which the exploiting output accounts for 94%, the farming output accounts for 6%

In addition to the advantages of the beach, the infrastructure of Phu Cat District also has many potentials For example, according to the airport system planning, by

2030, Phu Cat airport would become an international airport, promising to benefit tourism and commerce It will also be an opportunity for Phu Cat district to develop economy and tourism and move closer to building an aviation logistics centre

According to the Regional Construction Planning of Binh Dinh Province, by 2035, Cat Tien commune would become a grade IV city and act as a satellite city of Quy Nhon city, taking on the functions of services tourism and development of Nhon Hoi Economic Zone

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Besides, De Gi fishing port could accommodate 150 ships with a capacity of 400CV a day; ship mooring area with a total of up to 2000 ships with a power of over 300CV would play an essential role in marine economic development Moreover, this

is a place to anchor boats and avoid storms of fishers in Phu Cat district and Phu My and other provinces in the Central fishing grounds

Figure 1 12: Some beautiful beaches in the Phu Cat district

Much planning for service and tourism areas is being developed in this area, threatening ecological imbalance due to economic and environmental benefits Therefore, research on this coastal area's erosion would guide marine economic development plans towards sustainable development, biodiversity conservation, and increased resilience for the ecosystem and coastal communities

1.9.3 Climate change in Binh Dinh

1.9.3.1 Temperature change

According to the temperature monitoring data from 2006 to 2019 by GSO, the temperature in Binh Dinh tends to increase (Please see Figure 1.13)

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Research [45] showed that temperature in Binh Dinh province increased every decade For example, the average annual temperature had the lowest value in the decade 1981-1990, raised in the decade 1991-2000 and the period 2001-2008 about 0.1÷0.2oC compared to the average of the period 1981-2008 The average annual temperature in Binh Dinh has increased by 0.7oC over the past 50 years

(Source: GSO)

Figure 1 13: Temperature trend in Binh Dinh province from 2006 to 2019 1.9.3.2 Precipitation change

According to the Climate Change and Sea

Level Rise Scenario of MONRE (2016) [46], in

1958-2014, South-Central Vietnam had the most

significant increase in rainfall (19.8% /57 years)

According to research [29], rainfall in Phu

Cat tends to increase gradually over time The

average annual rainfall in Phu Cat district in the

period 1980-2018 was about 1900÷2000mm;

Rainfall in the rainy season is three times higher

than in the dry season

According to the project "Building a plan to

respond to climate change in Binh Dinh province",

(Source: MONRE, 2016)

Figure 1 14: Change of annual rainfall (%) ( 1958-2014)

y = 0.0514x + 26.957 R² = 0.4081

26 26.5

27 27.5

28 28.5

2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019

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Figure 1 15: The influence of storm Linfa along with heavy rain caused flooding in

many areas in Binh Dinh province 1.9.3.3 Storm

NOAA recorded the data of storms and tropical depressions that hit the mainland

of Vietnam A research team from P-GIS analyzed 459 storms that made landfall in Vietnam over the past 70 years These data are extracted from the Asia-Pacific storm track database with more than 227 thousand storms in the same period

(Source: P-GIS)

Figure 1 16: Path of storms that hit the East Sea and Vietnam in the past 70 years

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Statistics of storms hitting Vietnam were collected from the website and statistical data of GSO and the website named EM-DAT (https://public.emdat.be/), a global database on natural and technological disasters that contains essential core data on the occurrence and effects of more than 17,000 disasters in the world from 1900 to present

The list of storms that hit or landed Binh Dinh was shown in Table 1.8

Table 1 8: List of storms that landed or affected Binh Dinh province (1988-2017)

(Source: GSO, EM-DAT, [34]) Event

Name

Start Day

Start Month

Start Year

Event Name

Start Day

Start Month

Start Year

1.9.3.4 Sea level rise

According to statistics of the Hydrometeorology Station of the South-Central region, from 2000 to 2019, the sea level observed at Quy Nhon station increased

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rapidly and tended to increase Figure 1.17 shows that during the period from 2000 to

2019, the sea level rose 3cm on average (Please see Figure 1.17)

In 2014, the Ministry of Natural Resources and Environment announced the storm zoning report, identified the risk of storms and storm surge for the coastal strip of Vietnam and updated it in 2016 Although in the area from Da Nang to Binh Dinh, the highest storm surge that has happened is 180 cm, in the future, it may reach over 230

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26

(Source: GSO)

Figure 1 17: Average Sea level at Quy Nhon station

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To date, to ensure the sustainable management, exploitation and use of marine resources, as well as minimize coastal erosion, the Government, the MONRE and local departments have promulgated and implemented laws and policies on requirements, orientations and solutions for natural disaster prevention and control, response to climate change and sea-level rise in coastal areas

The traditional approach to assessing the impacts of climate change on the coastal area is a “top-down” approach This approach considers the causes of shoreline change (endogenous, exogenous and human causes), uses climate scenarios, coastal models, etc., to forecast future shoreline change However, it involves many uncertainties due

to the cumulative uncertainties associated with datasets, models, and scenarios Therefore, if any, the solutions are almost theoretical, not based on the internal capacity of that locality On the other hand, the “bottom-up” approach is based on one area's past and present conditions to understand future adaptation Combining these two approaches will help urban planners have a more multi-dimensional view of coastal management The shoreline change research framework based on these approaches is presented in Figure 2.1

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The images used in the study, taken from a

device called the DJI Phantom 4 Advance+, provided

by the MCCD program, with an image resolution of

up to 20 megapixels The Phantom 4 Advance+ is a

multi-rotor UAV with a weight of 1,380g, a diagonal

size of 350mm, and a flight time of up to nearly 30

a total length of about 12km The drone‟s route was set up downwind, and the photos were taken at Equal Distance

Figure 2 3: UAV photos of Phu Cat coastal area, captured by the DJI Phantom 4