Luận văn thạc sỹ Kỹ thuật và Quản lý vùng ven biển: Research hydrodynamics to serve layout design of beach Nourishment project for the Mui Nai beach, Ha Tien, Kien Giang province

MINISTRY OF EDUCATION MINISTRY OF AGRICULTURE,AND TRAINING AND RURAL DEVELOPMENT ‘THUY LOI UNIVERSITY RESEARCH ON HYDRODYNAMICS TO SERVE LAYOUT DESIGN OF BEACH NOURISHMENT PROJECT FOR TH

MINISTRY OF EDUCATION MINISTRY OF AGRICULTURE

AND TRAINING AND RURAL DEVELOPMENT

THUY LOI UNIVERSITY

PHAM THI HAN

THESIS OF MASTER DEGREE

HA NOI - 2016

MINISTRY OF EDUCATION MINISTRY OF AGRICULTURE,

AND TRAINING AND RURAL DEVELOPMENT

‘THUY LOI UNIVERSITY

RESEARCH ON HYDRODYNAMICS TO SERVE LAYOUT DESIGN OF BEACH NOURISHMENT PROJECT FOR THE MUI

NAIBEACH, HA TIEN, KIEN GIANG PROVINCE

‘Major: Coastal Engineering and ManagementCode: 62-58-02-03

THESIS OF MASTER DEGREE

SUPERVISOR: Assoc.Prof.Dr TRAN THANH TUNG

HA NOT - 2016

T guarantee the work which is being presented in this thesis entitled, “Research onhydrodynamics to serve layout design of beach nourishment project for the Mui Naibeach, Ha Tien, Kien Giang province” in partial complete of the requirement for theaward of Master thesis of Coastal Engineering Management, is an authentic record of

my own work carried out under supervision Assoc Prof.Dr Tran Thanh Tung The

‘matter embodied in this thesis has not been submitted by me for the award of any otherdegree or diploma

Ha Noi, December 16, 2016

Pham Thi Han

I would like to express my sincere gratitude for my advisor Assoc.Prof Dr Tran

‘Thanh Tung was help me complete my master thesis

also want to show deep thanks to Master Nguyen Thanh Luan who is making valuecontributions to success in Master course

1 would like to thank faculty of Marine and Coastal Engineering of Thuy LoiUniversity and Key laboratory of river and coastal engineering for help me to

‘complete thesis on schedule

Finally, I would like to express my special appreciation to my friends and colleaguesfor their support and encourage I would like to express deep gratitude to the members

‘of my family

Ha Noi, December 16, 2016

Pham Thi Han

4 Thesis outline 4CHAPTER 1 OVERVIEW OF BEACH NOURISHMENT AND STUDY AREAS1.1 Introduction of beach nourishment 51.1.1 Beach nourishment, a basic concepts $1.1.2 The beach nourishment in developed countries 81.1.3 Beach nourishment in Vietnam R1.2Brief description of the study area 151.2.1Geographical location and natural conditions 151.2.2 Topography, geomorphology characteristics 11.2.3 Hydro-marine conditions of study area 71.2-4§ocial and economic features 18CHAPTER 2 SETUP HYDRODYNAMIC AND WAVE MODEL FOR STUDY

AREA, 20

2.1Model descriptions 202.1.[Hydrodynamics model (MIKE 21 FM HD module) 202.1.2 Wave model (MIKE21 FM SW module) 22.2Data usage for model setup, calibration and verification 242.2.2 Water levels observation and field measurement 282.2.3 Wave data 282.3 Setup wave and tidal models for large domain 322.3.1 Model setup 322.3.2 Model calibration 352.3.3 Model verification 362.4Setup hydrodynamics model for the M 362.4.1Model setup 36A.2Model calibration 39CHAPTER 3 CRITERIA FOR BEACH NOURISHMENT AND DESIGNBEACH NOURISHMENT FOR MUI NAI BEACH 403.1 Analysis of wave climate and wind regime for the study area 403.2 Criteria for beach nourishment project 4“3.2.1 Technical criteria 4“ 3.2.2 Environmental criteria and landseape 43.2.3 Social eriteria 4

3.2.4 Criteria of the legal framework and implemented project beach nourishments

B

3.2.$ Criteria for planning, protection, exploitation and using of coastal resource 433.3 Design the Mui Nai beach nourishment project “443.3.1Design beach nourishment profile “43.3.2 Volume of sand fill and sand composition 43.4 Computation lifetime for the Mui Nai beach nourishment project 43.4.1 Estimation of annual alongshore sediment transport for study area 43.4.2Computation lifetime of the Mui Nai beach nourishment project STHAPTER 4, DESIGN BEACH NOURISHMENT IN COMBINATION WITH

|UBMERGED GEOTUBE FOR THE MUI NAI BEACH 364.1 Design draft layout for submerged geotube 36 4.1.1 Criteria proposed plan 564.1.2 Technical solutions is proposed 564.1.3 Design layout for submerged geotubes 584.14 The parameters design layout of submerged geo-tube for beach nourishment604.2 Simulation waves pattern with and without submerged geotube a42.1 Simulation scenarios for waves a42.2 Simulation results and analysis 64.2.3 Estimated sediment loss behind submerged geo-tube 74.3 Simulation flow pattern with and without submerged geotube 743.1 Simulation scenarios for tide and wave 744.3.2 Simulation results and analysis 7

44 Propose layout for beach nourishment in combination with submerged

geotube 86

CONCLUSIONS AND RECOMMENDATIONS 87

Conclusions 87 Recommendations 88 REFERENCI 89

‘THE APPENDIX 1

‘on satellite images 26Figure 2 2Points setting automatic equipment to observe water level, WLI, under the

Figure 2 3 The locations of the sediment sampling area Mui Nai - Ha Tien 26Figure 2 4Water level at rear beach of Mui Nai to 18 hours of June 6, 2016 to 18hours of June 9, 2016 28Figure 2 5 Grid and computation domain of wave and tidal models (large domain) 32Figure 2 6 Bed topography of wave and tidal models, 33Figure 2.7 Comparison of measured and calculated water levels of the Phu Quocgauging stations from May 6, 2010 to May 20,2010 35Figure 2 8Comparison of measured and calculated wave height at Mui Nai station,from 18 to 21 of March, 2016 35Figure 29Compaison of measured and calculated water levels, Phu Quoc gaugingstationfrom September 2, 2010 to September 6, 2010 36Figure 2 10Computational domain of the Mui Nai hydrodynamies model 37Figure 2 11 Grid mesh H and domain of hydrodynamies model 37Figure 2, 12 Topography of hydrodynamics model for study area 3Figure 2 13Comparison of measured and calculated water levels at Mui Nai beach, 16th of March to 22 of March, 2016 39Figure 3 IMonthly wind rose average month, the period from 2009 to 2016 years, Phú

‘Quoc gauging station (Source: WindFinder com GmbH & Co KG) 41Figure 3 2Monthly wave rose average month, the period from 2009 to 2016 years,Phu Quoc gauging station (Source: WindFinder.com GmbH & Co.KG) 41Figure 3 3The scope of dry beach: width 50m, elevation +0.5 “Figure 3 4The scope of submerged beach: width 40m, slope of 1/20, bed elevation atseaside -1.5 4

Figure 3 SDefinition of the angle of wave propagation with respect to the coast 46Figure 3 6Schematization of triangular beach fill ayer 31Figure 3 Lifetimes as function of total fill volume 35Figure 4 1 Solution submerged built by geotube to sand pump (Source: Internet) 57Figure 4 2 Plan view of submerged geotube (Source: Google earth) 59Figure 4.3 Frequency line of synthesis level at point 139 (104027 "A, 10025: B) MyDục, Ha Tien town, Kien Giang province (Source: I4TCNI613~ 2012) 60Figure 4 4Layout of submerged geotube for the beach nourishment project “Figure 4 5The boundary conditions in wave model 6Figure 4 6Location of points on section extracted to calculation results for wavemodel Source: Google earth) 65igure 4.7 The grid incase with and without submerged geotube 66Figure 4 EWave height at MCI section, simulation scenarios without geotube 66Figure 4.Wave height at MC2 section, simulation scenarios without geotube 67Figure 4 10Wave pattern in 4 simulations scenario, without submerged geotube 69Figure 4 11 Wave height at MCI section, scenarios with submerged geotube 9Figure 4 12Wave height at section MC2,scenarios with submerged geotube 70Figure 4 13Wave mode the scripts of the case submerged geo-tube 1Figure 4, 14 Cros “shore profiles in central section computed by DELFT3D-model(waves oblique to coast) nFigure 4, 15Shows the time development of the total beach fill volume by time 73Figure 4 16Water levels at Ha Tien station, 2015 and period of highest spring tide in

November 75

Figure 4 17The boundary conditions in hydrodynamies model 75Figure 4 18The location to extraet the hydrodynamics data 16

Figure 4 19Water levels at boundary, from 12" Nov to 20!" Nov 2015 id

Figure 4 20The area outside submeged geotube of ease current status idFigure 4 21The area outside submeged geotube of case with submerged geotube 78Figure 4 22The area outside submeged geotube of case current status 8Figure 4 23The area outside submeged geotube of case submerged geotube 9Figure 4 24The area inside submeged geotube of case current status, T9

Figure 4 side submeged geotube of case with submerged geotube 80

Figure 4 26The area inside submeged geotube of ease current status 80Figure 4 27The area inside submeged geotube of ease with submerged geotube SIFigure 4 28The point between submeved geotubes of ease current status 8Figure 4 29The point between submeged geotubes of ease with submerged geotube 82Figure 4, 30The point between submeged geotubes of case current status sẽFigure 4, 31The point betreen submeged geotubes of case with submerged geotube 83Figure 4 32Current speed at measuring point with wave direction West before andafter the submel 84Figure 4, 33Current speed at measuring point with wave direction southeastbefore andafter the submerged geotube 85igure 4 34Currents speed corresponding to the scripts of the status quo plan 85Figure 4 35Current speed in the scripts of case with submerged geotube 86

LIST OF TABLES

Table 1 IComparison about the number of projects, the frequency and volume of

‘material used for beach nourishment in some countries 7Table 1 2Comparison of common parameters beach nourishment project between anumbers of countries 8Table 2 1Coordinates of stations observing wave and water level 25

‘Table 2 2Description of hydro-dynamics survey +Table 2 3Quantity of taking suspended sediment and bottom sediment 21

‘Table 2 4Water level characteristics at rear beach Mui Nai, Ha Tien town, 28Table 2 SResults of characteristic wave at WV1 station, averaged for each day 29

‘Table 2 6Characteristic of wave at WV station, the real beach resort of Mui Nai 29Table 2 7Analysis of 12 samples suspended sediment in the Mui Nai beach 30Table 2 8The synthesis of mechanical characteristics for 16 samples bed sediment inthe areas Mui Nai beach 31Table 3 1Statisties waves offshore at Phu Quoc Island from 2005 to 2015 (waveNOAA) 40

‘Table 3 2Brief description of the beach nourishment area 4Table 3 3Statistical analysis of data offshore wave Phu Quoc Island in 2005-2015

NOAA station 49

Table 3 4Input data of wave and wave angle 49

‘Table 3 SInput data of sediment and other main parameters 50

‘Table 3.60utput data s0

‘Table 3 7Input data for calculation lifetime 33Table 3 SOutput data for lifetime of project, st

‘Table 4 1Synthesis of the scripts for wave model 6Table 4 2In put data of the scripts for wave model oF

‘Table 4 3Description of extraction points on wave model 65

‘Table 4 4Wave height at Section MCI, MC2, without geotube 68Table 4 5Wave height at Section MCI, MC2 with submerged geotube T0Table 4 6Wave climate of winter season North Sea (180days; October to March) 72Table 4 7Synthesis of the

Table 4 8Input dạ

Table 4 9Current speed according tothe s

ios for hydrodynamics model 4

ta of the scenariosfor hydrodynamics model 75

xipts 84

1 The necessity of study

The coastal eco-tourism zone of Mui Nai (Ha Tien town, Kien Giang province) issituated in the southwest of Vietnam, with special topography and it has an importantrole in the economic - social development, security defense and security of Kien Giang

province in particular and tourism Southwest region in general.

Geographical coordinates:

From 104”40°-105"32'40" East longitude;

From 9°23°50"- 10°32°30" North latitude.

‘The study area is located in the west sea, shielded by Mui Nai in the South (Mountain

‘more than 30 km awayLights) about 8 km west ofthe island are some of Cambod

from Phu Quoc island We can say the project area is shielded almost connected withthe sea on both sides, creating a gentle waves mode than in other beach area of

‘Vietnam Besides, here the tidal magnitude reaches a modest value, from 1.1m to1.2m.

“The coastal eco-tourism zone of Mui Nai beach comprises two beaches: front beach

‘and a rear beach The area has gently sloping beaches, charming landscape and verysuitable for bathing needs and tourism organizations However, the recent years, underthe impact of waves and currents large amount of sand on the beach of Mui Nai lost:the other hand due to the effects of sea level rise phenomenon has made the beach areahere are much narrower, sometimes increase tide, the sea level has risen to foot ofdike, no tourists bathing and recreation It had a large impact to the tourismdevelopment strategy of Mui Nai in particular and Kien Giang province in generalBefore the urgent need for improvement and upgrading of beach resort in Mui Naibeach, Ha Tien town, Kien Giang province, there are no reports, recommendations,proposals from planners or scientists to provide reasonable solutions to improve and

Figure 2 Location map of the study area (Source: Google earth)

Being aware of the urgency of these issues, the student has selected study with thetheme: "Research on hydrodynamics to serve layout design of beach nourishmentproject for the Mui Nai beach, Ha Tien, Kien Giang Province" The research aims

to identify an overall picture on hydro-dynamies regime of the research area and tosimulate design plans in term of hydrodynamic for the Mui Nai beach nourishment

project, review the soluti layout design related to beach nourishment incombination with submerged geo-tube Also analyze and evaluate the effectiveness ofthe solutions layout design, choosing the most reasonable design plan that can be

applied in practice for the study area,

Facing this urgency situation, the layout design of beach nourishment project toimprove and upgrade of the beach area for beach nourishment, thereby creating new

4) Solution makes basis sient € to implement layout design of beach nourishment

for improving and upgrading are completed to supplement sand for beachreplenishment, creating space for tourists to beach with entertainment activities

b) It serves

into a major tourist area of Ha Tien in particular and Kien Giang province in general

4 prerequisite for the development of tourism here; turn Mui Nai beach

©) It ensures the safety of the infrastructure inside, under the effect of waves, currentsand sea levels rise

2 Research objectives

The main objective of this thesis is to simulate the hydrodynamics regime for the studyarea using a numerical model (MIKE 21FM), and use simulation results as scientificbasis for improving and upgrading the Mui Nai beach via a beach nourishment project.+ Improved landscape and saety for tourists:

+ Reduced loss of sand after implementing beach nourishment project

+ Maintained natural features ofthe beach area

3 Study method

BL Subject

Research on hydrodynamics regime by numerical models to serve design layout ofbeach nourishment project for the study area

3.2 Methodology of the thesis

~ Data collection and analysis;

- Field investigations and surveys:

~ Numerical modeling (MIKE21 FM, HD module and SW module)

4 Thesis outline

Besides the introduction, conclusion and recommendations, the thesis is consisted of 4chapters as following:

Chapter 1 Overview of beach nourishment and study area

Chapter 2 Setup hydrodynamic and wave model for the study area

Chapter 3 Beach nourishment criteria and design beach nourishment for the Mui Naibeach

Chapter 4 Design beach nourishment in combination with submerged geo-tubes for theMui N: beach

CHAPTER 1, OVERVIEW OF BEACH NOURISHMENT AND STUDY AREA

1.1 Introduction of beach nourishment

1.1.1 Beach nourishment, a basic concepts

Beach nourishment is a soft solution to protect sea shore by using suitable materialsource (known as beach nourishment material) to expand the exist 1g beaches bypouring directly or indirectly materials for this beach area,

‘A coast is considered to be stable when the amount of sediment provides coastal isbalanced with the amount of sediment lost (due to sediment transport alongshore,horizontal, human exploitation ) Therefore, when the supply of sediment smallererode the coastline and vice versa To minimize the coastal erosion, we usually focus

‘on two solutions: the first solution is to reduce the amount of sediment lost bysediment transport alongshore by design hard structure cross-shore to prevent sand anddecrease wave or planting mangroves; the second solution ineludes beach nourishment

‘and sand by ~ pass to increase the amount of sediment supply t the coast area

So in essence the solution generally by pouring the material directly on the beach butcompletely submerged under water, within breaking wave zone, Material for beachnourishment should be put on the shore with low-energy waves and long period Inthis solution, the beach width increased significantly, which increase supply of

cforesediment to the coast is eroded to progress conditions balance of sediment, Th

beach nourishment must be carried out in a certain period time, this period is calledbeach nouri ment period

Nowadays, there are two forms of beach nourishment, which is direct beachnourishment and indirect beach nourishment In beach nourishment the material ispoured directly on beaches, usually using the appropriate motor vehicles (cars,bulldozers, ete) and razed to the material or using ship suck ~ puff to spray until thematerial reaches the expected beach elevation, width and shape

Unlike beach nourishment, shore-face nourishment is the method applied in large

wave energy and erosion speeds greater the beach nourishment methods often tse in

conjunction with other forms of hard structure (embankments, breakwater, etc) in

5

order (o reduce the loss of material due to beach nourishment caused sedimenttransport alongshore and horizontally Therefore, with the beach area with small wavecondition, the solution using direct beach nourishment is more efficient, reducing the

economic costs.

Beach nourishment is describes in the figure below:

Figure 1 IBeach nourishment (left) and shore-face nourishment (right)(Source:

Intemet)

Specifically, the review study of H Hanson, et al [10] about “soft construction”solutions showed that there are clear differences in the frequency of beachnourishment and material used to beach nourishment between the nations Table 1.1below provides information on the number of beach nourishment projects, beachnourishment frequency and volume of material used for beach nourishments in 2002.From the data, we see that the Spain and the Netherlands are the two countries thatused the solutions beach nourishment among European countries, However, solutionsbeach nourishment solutions in these two countries were different While beachnourishment in the Netherlands was performed with large-scale projects, there are

‘more number of projects, but with smaller-scale in Spain,

Table 1.1 shows the Quantitative Statistics about number of projects, the frequencyand volume of material beach nourishment in each country since the started beachnourishment as the 2002 However, to see more clearly the difference betweencountries, table 1.2 presents a more detailed comparison of the common parameters ofthe beach nourishment project between some nations,

Table 1 IComparison about the number of projects, the frequency and volume of

‘material used for beach nourishment in some countries

spaincisssy | THƠ | 688 | 400 mà 03 15

England (198) | 20 | 35 | 32 370 06 mPmak99) | at | ae | 13 263 34 s

‘The most obvious diversity between countries in the percentage of coastline wereraised beach (LN) compared to the total length of the coast of soft (suitable with thesolution adopted, sand or gravel beach) can erosion (LS) In the Netherlands, therewere 52.1% of the entire length of the coast are beach nourishment in soft form.Meanwhil in the US the figure is only 0.6% and some other countries in Europe suchfas France and Italy that number is quite small So this shows that, except for theNetherlands, raising beach activities in other countries is relatively small and is not

‘commensurate with the total length of the coast can be beach nourishment

Referring to the volume of material beach nourishment used annually under 1 meterlength of coastline (AVN) we see that: this value in the Netherlands and Spain

approximately the same and at around 40 m’/yeat/m length of beach nourishment This

indicates that, in the Netherlands and Spain, materials used beach nourishment morelost or are these countries more efforts to compensate for the material lost beachnourishment, Consider retum eyele beach nourishment (ARI) we see that: the periodbeach nourishment in countries such as the Netherlands, Spain, France and Denmark isabout 5 years, while in countries such as Italy and Germany is about 25 years onaverage However, in contrary to the Netherlands and Spain, France and Denmark

7

used volume material of beach nourishment project much less is expressed in valueAVP (the average volume of materials using for all projects beach nourishment).

Table I, 2Comparison of common parameters beach nourishment project between a

nourishment is us 's for many different purposes and below will present the usualsituations beach nouri yment is applied.

~ Apply to the narrow coast or erosion coast but width of coast is not enough toprotect the inside area the risk of flooding due to storm waves and sea level rise;

~ Handling, emergency overcoming erosion aused by storms

~ Reduce the erosion speed for beach nourishment area and the areas downstreamprojects beach nourishment;

~ Handling of erosion caused by impact of hard structure on @ large area or handling

‘and overcoming erosion occur in the hard structure:

~ Expanding the beach to serve the play activities, rest a the beach;

Improving the protection of the natural coast dunes to against flooding for inside

‘area when have impact of storms and sea level rise;

~ Maintain position shoreline to serve the purpose of management, exploitation anduse sustainable coasts;

~ Respond to the phenomenon such as

1.1.2.2, The Netherlands

imate change and sea level ris

In the Netherlands, beach nourishment are started applicable since 1970, in this periodabout 200 new projects and old projects about beach nourishment was performed at 35

locations with a total volume of material to beach nourishment used up 10 110 x 10° m’ From 1991 to now, the volume of medium material for beach nourishment around

6 x10°m’/ year.

“The Netherlands has a lot of experience in protecting the coastal from the effects offlooding at the western part of the country have altitude lower than the average sealevel The majority of the Netherland coastline has faced with encroaching seacondition during a long time Inthe past, the erosion was processed and decrease in 4number of positions with the application of hard structures to prevent sedimenttransport alongshore However, downstream of these structures, coastal erosion has

‘occurred The Netherlands has used hard structure in protecting the beach, However,the historic 1953 floods in the southern region has ereated a change in the coastalprotection policy in the Netherlands

Important step of this trend in 1990 was carried when as sing the feasibility of thetechnical and economic results of adopting measures beach nourishment for sand coasterosion This priorities for restoring and enhancing the protection of the natural dunes

to prevent wave overtopping Beach nourishment was considered as the main solution

in the coastal protection in the Netherlands after the policy the protection andconservation of the coast was carried in 1990,

The design layout parameters includes: the volume of material beach nourishment;beach nourishment performance; each nourishment period; cross-section; sourcematerial beach nourishment, et

In the Netherlands, the shoreline position is determined based on the measured volume

of sand (based on annual beach cross-section) Beach nourishment has designed with 4purpose to offset the loss of sediment caused by the natural process coast dynamies incertain period time, Materials of beach nourishment is calculated by taking the

‘volume of sediment average annual has loss (taking the average for the ten years prior)multiplied by the beach nourishment period, Then material of beach nourishment isadded from 10-20 % of the material was calculated (depending on the conditions ofeach beach nourishment position)

Safety conditions against flooding also are checked regularly every year based on themeasurements of the cross-section the beach Elevation of the sand used to beachnourishment is determined based on the actual annual survey, The structure had doneduring 1965 with the cross-section apart from 200 ~ 250 m along the entire Dutch

coast

1.1.2.3 Japan

Japan is an island country with a approximately 30000 km coastline Due to thespecific features of topography, geology and system transport infrastructure andservices, residential at the coastal areas with high security requirements a majority ofstructure coast protection are built from the 90°s and before the use of hard structures.However, in recent years, due (0 the impact of a series of dams built on main riversystems, the source of river sediment supply to the coast reduced dramatically duc to

relained in the reservoir This caused a serious shortage of sediment to the coastal stiparound the estuary and cause serious erosion of coastal areas.

In the beach nourishment design, requirements for beach nourishment: materialsadopted first purpose This beach nourishment solution is applied to the beach havesmall wave and often combined with hard structure is functions keeping the materialfor beach nourishment

Motivation to design beach nourishment: Material beach nourishment and contribute

to stable beach coast beach culture medium positioned acting as sediment supply to thearea is the lack of sand downstream without beach nourishment Generally applicableactivities beach nourishment for small coast and grain size of sediment is muchchanged This method has the advantage of flexible and harmonious with the natural

processes.

‘Technology built beach nourishment in Japan is using cars and bulldozers to pouringdirectly sediment on the coast Measures using vessels suck, puff is only use in some

projects, With some other projects with floodplain, using much laparotomy types ship.

Ín Japan, most beach nourishment project are supported by the government budget orthe coastal provinces directly The management and exploitation have control of state

‘government and local The private enterprise is not direct financial investment for theprotection of the coast, which is only use through a special tax if the businessmanufacturing jobs related directly to coastal protection structures present

1.1.24, laly

Italy has about 7500 km of coastline, more than half of whi h geology is alluvialsediments and are now faced with state of erosion and the area of the coast limitedregion in a serious Coastal protection is an important issue for Italian, a country that isdestination resort with over 90 million beach tourist arrivals in the country and

‘Western Europe,

In Italy, the solution beach nourishment to the coast against erosion is conducted since

1969 During this period, about 50 projects beach nourishment has implemented in 36locations, bringing the total volume of materials used beach nourishment to about 15 x

"

10° m*, Most of the: c projects are of scale 100 - 150 x10" m’ Except for some scale projects such as dunes along Venice Strip:7.6 x10° mỸ, beach nourishment in the river mouth Po: 1.4 x 10° m',

large-Almost all the beach nourishment projects in Italy are making by form of beach

nourishment combined with hard

addr

structure These the projects are purpose atsing some issues the following: Mitigation of coastal erosion in small range;Expanding the tourist beach resorts and small scale; protecting some sections related toinfrastructure in the south of Tay

1.1.3 Beach nourishment in Vietnam

‘The solution beach nourishment “soft structure", with the “flexibility” in preventingerosion, shoreline stabilization has applied successfully in many countri around inthe world However, this solution has not applied in Vietnam

Beach nourishment combined with hard structures measures to improve the efficiency

of beach nourishment, which hard structure had the effect of reducing the loss ofsediment horizontal and alongshore Hard structures: submerged breakwater, artificialreefi, ete

‘The solution against coastal erosion by hard structures measures has been applied quiteoften in our country, so we had some experience in that problem, The traditionalsolution structure have been used mainly in the coastal strip is now the bank protection

by conerete or stone structures with detailed design guidelines newly updated in 2012

However, if the use of shore protection measu ard structure” in the touristactivities (e.g cases protecting coast by use concrete structures at Doi Duong beach,Binh Thuan province) or potential tourism activities will disrupt the natural landseape,reducing the environmental friendly tourism If the design layout structure areincorrect, would quickly destroy by regularly suffered the ditect impact of thesefactors waves, winds in the area,

In recent years, coastal protection solutions using geotextile tubes forming “softstructure” has also been applied in some sections of coastline erosion in Hoa Duan (

‘Thua Thien Hue); Tam Hai (Quang Nam); Doi Duong (Binh Thuan); Loc An (Ba Vung Tau),

Ria-Beach nourishment as erosion prevention solutions, stabilizing the shoreline haveforms “non-structural” or also known as structural measures “soft” has been appliedsuccessfully in many countries with the first marine science and technology advanced

in the world Beach erosion prevention and embellish the coast had not studied applied

in Vietnam although we had many reclamation projects, but mainly built inside the

‘bays and material mostly rocky beaches and have combination with hard structure, InVietnam, in recent years, some beach regeneration project, reclamation in the touristareas, resorts and coastal areas have just started For example, the reclamation project

in Do Son peninsula, Hai Phong, Quang Ninh Tuan Chau island, the reclamationproject Da Phuoe, Da Nang city, the reclamation Can Gio project, Ho Chi Minh City,

ete

Can Gio project was started in 2007 with a design total area of reclamation of 600hectares, in which 200 hectares will be reserved for internal sea and beaches, 400hectares to develop service projects tourism and residential areas

areas in Vietnam has not been focused,

‘The improvement and upgrading of the tour

due to many reasons such as capital investment, scientific and inadequate technicallevel, ete Currently, only some areas such as Bai Chay Beach, Tuan Chau and Bai TuLong Bays (Quang Ninh), Sam Son beach (Thanh Hoa), Nha Trang beach, are beingproperly concerned with the implementation layout design layout to improve andupgrade beach study area

Figure 1 2Dike in Mui Ne, Binh Thuan (Source: Google Earth)

In previous years, Tuan Chau beach, despite being a beautiful beach, with views of the

Ha Long bay, the UNESCO World Heritage, but also somewhat inconvenient due tonarrow and low quality of mud sand on the beaches Thanks to the investments in theimprovement and upgrading of this beach, the Tuan Chau beach now has a newappearance The beach is wider, sprayed with clean white sand; the sand has smoothlyscreened before put into use, Tourists are comfortably frolie on the wide beach withwhite sand In addition, Tuan Chau beach has been expanding services to createsatisfaction for arriving tourists,

Nha Trang beach needs upgrading and improving because the beach area no longermeets the demand for entertainment while ensuring environmental sanitation andurban landscape The improvement and upgrading of the beach must be consistentwith the overall planning of development economic - social, increase efficiency,censure the beauty of landscape and environment for each region and minimizenegative impacts to Nha Trang

In Sam Son, Thanh Hoa there are also plans to improve and upgrade the beach to serve

the tourists in summer 2016, The Provincial Committee has approved the policyned to Joint Stock Company FLC Group to perform spatial planning at the beacharea, Sam Son town, Thanh Hoa province

Measures to improve and upgrade the beach in Vietnam mainly are "hard measures

so there is less experience on “soft measures”, Beach nourishment is “flexible” in

keeping sand, shoreline stability for serves to improve and upgrade of beach tourismregion has been successfully applied in many countries around the world This solutioncombines with structure to promote the advantages of both “hard” and “soft”

‘measures However, tis solution has not been applied extensively in Vietnam

1.2Brief description of the study area

1.2.1Geographical location and natural conditions

Giang province in the Mekong Delta - the Southwest ofthe country: the North by the Kingdom of Cambodia; the South near Ca Mau and Bac Liew province; Easternand Southeastem of province border An Giang, Can Tho City and Hau GiangProvince; West by the Gulf of Thailand

“The province is located from 9" 23 '50" 10” 32' 30" north latitude; from 104” 26 '40"

-105" 32°40 " east longitude;

North of Kien Giang province bordering Cambodia, 56.8 km long border; south of BacLiew and Ca Mau provinces; west by the Gulf of Thailand with a coastline of 208 km;respectively adjacent eastem provinces of An Giang, Can Tho City and Hau GiangProvince

Kien Giang has 15 administrative units districts: Rach Gia city, Ha Tien town, thedistricts of Kien Luong; Giang Thanh, Hon Dat, Tan Hiep commune, Chau Thanh,Giong Rieng, Go Quao, An Bien and An Minh and Vinh Thuan, U Minh Thuong andPhu Quoc, Kien Hai

=

Figure 1, 3Location of Ha Tien town, Kien Giang provinee.

Ha Tien is a small town located in the nomthwest of the provinee of Kien Giang(formerly located in the province of Ha Tien district and then Rach Gia province)North bordering Cambodia with 13.7 km long border, the eastern and southern bordersKien Luong district, the West by the Gulf of Thailand with a coastline of 22 km, HaTien is a narrow coastal strip of land with a rich terrain as bays, plains, mountains,rivers, caves and islands, ete

Mai Nai is located in the southwest of the country and south-west of the MekongDelta, Eastern and south-eastern borders of the provinces of An Giang, Can Tho, thesouth by the Ca Mau and Bac Lieu, the west by the Gulf of Thailand, north bordering

‘Cambodia, with length borders 56.8 km.

Ha Tien is where the distances to the ASEAN countries are relatively short; thesecountries are having economic growth rate highest in the world Ability of developwith Cambodia through the gate and create a relationship with Thailand through road

Mai beach of Ha Tien town is one of three “rare” area of the Mekong River DeltaFrom more than 300 years ago, Mui Nai was called Loc Tri and renowned as one often beauty of Ha Tien town, For many years, this area has become a major tourdestination attracting many tourists to visit beach and resort On an area of 17 hectares,Mai Nai beach have 11 business tourism operators.

1.2.2 Topography, geomorphology characteristics

4 Topography characteristics

‘The study area is mountainous terrain on the coastal plain

Coastal areas in Kien Giang province has relatively flat topography and low altitude in

‘common areas from 0.3 to 0.5 m Particularly through Ha Tien town high topography,

int sspersed with hilly, altitude in the region of 0.8 to 1.2 m Seabed terrain is flat andgentle slope Accretion takes place strongly in Rach Gia Bay area and many otherareas such as tourist resorts of Mui Nai

Topography and geomorphology of the study area will be the basis for the researchdesign of the project layout, offering suitable technical solutions to serve the beachnourishment project

b, Geomorphology characteristics

‘Among study area, there are 16 stratigraphic units, which the presence of intrusiverocks, eruptive, sediment Young Holocene sediments (Q12) are distributed in anarrow area, but very diverse in origin: rivers, marshes, bays, oceans

‘The region is full of mountainous terrain types, hills, plains, beaches, islands andarchipelagos Ha Tien - Kien Luong characterized by the landscape of the massif,rocks erupting cone, like the coast of Mui Nai, and geomorphology karst landscapewith towering limestone blocks, distribution pyramid isolated on Freeze Cave systemdistributed in different heights, with many stalagmites, stone columns, stalactites withinteresting shapes Hollow strip worn by the sea meets the typical average have 4.5meters high - the traces of climate change in the past engraved on limestone cliffs1.2.3 Hydro-marine conditions of study area

1.2.3.1, Hydrological conditions

Tidal waters of Ha Tien and Mui Nai general in particular influenced by semi-diurnalEast Sea; also influenced by the diurnal tide from the Gulf of Thailand Tidal of HaTien sea area prone to mixed diurnal During the day there are two peaks, 2 feet, butthe catastrophe completely dominate and neither diurnal Means two peaks differsignificantly but each approximately 2 feet Only small tidal amplitude ranges from 0.7

to L0 m This timetable form time to maintaining low water levels create favorablerained spending In January, the highest level on day care to high expectations (15lunar), down on the day the upper and lower amplitude mystical about 02 to 0.5 m

‘The lowest water level is no clear cycle oscillations for two boundaries

‘The wave regime of the region is affected by two distinct seasons, with NE, SWmonsoon In which the wave direction SW is most active from May to September, the

‘wave height may reach Š meters and in the summer (June and July) The average sea

temperature reached 29.2 °C, often never to below 24 °C.

‘The flow in Ha Tien coastal area is formed the combination of by the tidal current,Wind and river flow stream, The average flow speed is quite large, from 30 (0 50 emis,1.2.3.2 Climatic ~ meteorological conditions

‘The climate, hydrology resort in Mui Nai characterized hydrology climate is tropical

monsoon, hot and humid throughout the year, (he average temperature from 27.5 °C

Celsius to 27.7 hours of sunshine in the years around 2400 hours, average humidity81-82 4% The year is divided into two distinet seasons including rainy season and dryseason The rainy season from May to November, the dry season from December toApril next year The average rainfall is over 2100 mm/year, The area has two mainWind directions northeast and the southwest monsoon,

1.3-4Social and economic features

«a, Economic conditions

Ha Tien town is located in Long Xuyen quadrangle, has borders with Cambodia, both

‘on land and at sea, from Cambodia's Kampot province about 60 km and 20 km of thecity of Kep, which is very convenient in economic development with Cambodia

through border gate, creating a relationship with Thailand through waterway and

For the development of tourism, Ha Tien and hinterland are popular destinations ofVietnam travelers in general, However, very few international visitors have been tothis place Thus solution is needed to enhance regional economic development through

tourism activ 's development this areas,

Research about infrastructure in poor areas, greatly hinders socio-economicdevelopment in the region In the future, along with the renovation and synchronousinfrastructure of the industrial centers and economic zones, coastal cities need to spendadequate funds to invest in developing infrastructure systems for the deep-lying,remote and island areas

By 2020, construction of Ha Tien town into a tourist center of servies development ofurban type Ill, is the closest connection points along the Phu Quoc island district;renovation and expansion of the port in Kien Luong, Hon Chuong and Binh Thị; urbandevelopment, such as Hon Dat, Chau Thanh, Song Doe, Nam Can, Ghenh Hao form

‘an urban system along the coast; urban construction, the town on the island as of DuongDong, An Thoi and Kien Hai create a strong base for development combined withsecurity and defense, firmly safeguard the waters south west of the country

CHAPTER 2 SETUP HYDRODYNAMIC AND WAVE MODEL FOR STUDY AREA

2.1Model descriptions

MIKE 21 is a modeling system developed by DHI Water & Environment, The

‘objective of this section is to provide the user with a detailed description of the flowand transport model equations, numerical discretization and solution methods andmodel validation

MIKE 21 is based on a flexible mesh approach and it has been developed forapplications within oceanographic, coastal and estuarine environments The modelingsystem may also be applied for studies of overland flooding,

‘The system is based on the numerical solution of the two/three dimensionalincompressible Reynolds averaged Navier - Stokes equations invoking theassumptions of Boussinesq and of hydrostatic pressure Thus, the model consists ofcontinuity, momentum, temperature, salinity and density equations and itis closed by

a turbulent closure scheme

entered

‘The spatial discretization of the primitive equations is performed using a cell

finite volume method The spatial domain is discretized by subdivision of thecontinuum into non-overlapping elements/cells In the horizontal plane an unstructured{rfid is used while inthe vertical domain in the 3D model a structured mesh is used In

s.In the model 3Dthe model 2D the elements can be triangles or quadrilateral elemen

the elements can be prisms or bricks whose horizontal faces are triangles and

‘quadrilateral elements, respectively

2.1 [Hydrodynamics model (MIKE 21 EM HD module)

-2,1.1.1 The theoretical basis of the hydrodynamics modet

MIKE 21 Flow Model FM is a new modeling system based on a flexible meshapproach The modeling system has been developed for applications within

‘oceanographic, coastal and estuarine environments,

MIKE 21 FM is composed of following modules:

Hydrodynamic Module

‘Transport Module

ECO Lab Module

Particle Tracking Module

¥- Sand Transport Module

‘The Hydrodynamic Module is the basie computational component of the entire MIKE

21 Flow Model FM modeling system providing the hydrodynamic basis for the

‘Transport Module, ECO Lab Module, Mud Transport Module, Particle Tracking

‘Module and Sand Transport Module

‘The Hydrodynamic Module is based on the numerical solution of the 2D shallowwater equations - the depth-integrated incompressible Reynolds averaged NavierStokes equations Thus, the model cons \s of continuity, momentum, temperature,

salinity and density equations In the horizontal domain both Cartesian and spherical

‘coordinates can be used,

‘The spatial discretization of the primitive equations is performed using a cellcenteredfinite volume method The spatial domain is discretized by subdivision of thecontinuum into non-overlapping elemenUcells In the horizontal plane an unstructuredgridis used comprising of triangles or quadrilateral element An approximate Riemannsolver is used for computation of the convective fluxes, which makes it possible (0handle discontinuous solutions

‘Where £ is the time; x, y and z are the Cartesian co-ordinates; is the surface elevation;

is the still water depth; h + đ is the total water depth; u, v and w are the velocitycomponents in the x, y and direction; f = 20sing is the Coriolis parameter; g is thegravitational acceleration; p is the density of water; vis the turbulent (or eddy)viscosity; p, is the atmospheric pressure; p, is the reference density of water S is themagnitude of the discharge due t0 point sources and (u,.¥), is the velocity by whiehthe water is discharged into the ambient water

2.1.1.3 Application areas

“The application areas are generally problems where flow and transport phenomena areimportant with emphasis on coastal and marine applications, where the flexibilityinherited in the unstructured meshes can be utilized

2.1.2 Wave model (MIKE21 FM SW module)

2.1.2.1 The theoretical basis of the wave model

Mike 21SW is a state of the art third generation spectral wind -wave model developed

by DHI The model simulates the growth, decay and transformation of wind =

‘generated waves and swells in offshore and coastal areas,

Mike 21SW includes two different formulations:

Fall spectral formulation;

¥_ Directional decoupled parametric formulation

The fully spectral formulation is based on the wave action conservation equation,Komen et al (1994) and Young (1999) The directional decoupled parametricformulation is based on the parameterization of the wave action conservation equation,

‘The parameter tion is made in the frequency domain by introducing the zero andfirst moment of the wave action spectrum The basic conservation equations areformulated in either Cartesian co-ordinates for small-scale applications and polarspherical co — ordinates for large-scale applications

The discretisation of the governing equation in geographical and spectral space isperformed using cell- centred finite volume method In the geographical domain, an

‘unstructured mesh technique is used The time integration is performed using afractional step approach where a multi-sequence explicit method is applied for the

propagation of wave aetion

2.1.2.2 Model equations

Mike 21SW includes two different formulations

Fall spectral formulation;

¥ Directional decoupled parametric formulation

‘The directionally decoupled parametric formulation is based on a parameterization ofthe wave action conservation equation Following Holthuijsen et al (1989), theparameterization is made in the frequency domain by introducing the zero and firstmoment of the wave action spectrum as dependent variables Mike 21 SW it is notnecessary to set up a number of different orientated bathymetries to cover varyingwind and wave directions

‘The governing equation in Mike 21 SW is the wave action balance equationformulated in either Cartesian or spherical co-ordinates In horizontal Cartesian orspherical co-ordinates, the conservation equation for wave action reads:

ex

Where N(x.0,0,His the action density; t is the Hme;Z = (x,y) và y = (đ,Ä)is the

Caresian coordinates; TT (2®?! < the propagation velocity ofa wave group

in the four- dimensional phase space ", ơ và Ú; va S is the source term for energy

balance equation V is the four- dimensional differential operator `, 6 và 0

2.1.2.3 Application areas

Mike 21SW is used for the assessment of wave climates in offshore and coastal areas

in hind cast and forecast mode

A major application area is the design of offshore, coastal and port structure whereaccurate assessment of wave loads is of utmost importance to the safe and economicdesign of these structures,

‘Mike 218W is also used for the calculation of the sediment transport, which for a large

part determined by wave conditions and associated wave induced currents The

‘wave - induced currents is generated by the gradients in radiation stresses that occur inthe surf zone,

Mike 218W can be used to calculate the wave conditions and associated radiationstresses The long-shore currents and sediment transport are using the flow andsediment transport models available in the MIKE 21 package For such type ofapplications, the directional decoupled parametric formulation of MIKE 21 SW is anexcellent compromise between the computational effort and a suraey.

2.2Data usage for model setup, calibration and verification

2.2.1 Observation periods and location

Construction Engineering Institute has conducted the task of observation of

‘oceanographic factors including waves, currents, water levels and sediment at thebeach of resort Mui Nai, Ha Tien Town, Kien Giang Province Data is recorded inJune 2016 when the southwest monsoon is dominant Basically, the factors aresimultaneously observed

Tide was continuously observed for three days in June 2016

‘Wave was continuously observed for 6 hours per day and for three days in June 2016,2.2.1.1 Location of observation station and taking samples

‘The observation factors includes: waves, water levels, sediment bottom and suspendedsediments Therefore, there are basically three monitoring stations and I group ofsediment sampling locations Specifically, wave station WVI and current station FLfre arranged close to each other, located on the cross-section in the middle ofthebeach, about 300 meters from shore The station observing water level WLI islocated at the toe of marina in front of Ta Pang motel Location and coordinates ofstation WVI /ELI and WLI are given in Figure 3.1 and Table 3.1

Table 2 1Coordinates of stations observing wave and water level

Coordinates Station WV1/ FLI Station WLI

longitude 104°26°35,53 10426/45,0

North latitude 10°23°12,69" 1023144

According to the research proposal, wave characteristics are observed at a fixed point

in the surfzone and continuous measuring in 3 days However, based on the actualconditions of equipment transportation and hiring boats, the observation process isadjusted, Due to difficulties in transporting automatic equipment continuously andaccessories, the survey team can only carry equipment to measure wave height

‘Therefore, wave was observed about 6 to 8 hours per day (in 3 days),

“The location for setting equipment to observe water level at the tourist port Thisposition is satisfied in term of stability, easy observation and protection as well astheleast impact to the activities of visitors Moreover, this positon is always flooded even

if the water level down to the lowest Figure 2.1 illustrates position of installing the

equipment

Group of sediment sampling locations included fifteen points, distributed over fourcross-sections with regular intervals along the beach from North to South, as shown inFigure 2.3

25

Figure 2 | Location of points observing waves WV 1, currents FLI and water level

WLI on satellite image

Figure 2.2 Points setting automatic equipment to observe water level, WLI, under the

‘wharf in front of Ta Pang motel

2.2.1.2 Factors of the survey

‘Three oceanographic factors are observed that include wave characteristies, the current(sp

at the

ed and direction) and the water level Wave height and wave period are measured

ea atthe water depth of 3 m.

Near the location, a boat was arranged to measure speed and observing currentdirection, Tidal fluctuation was observed by self-recording machines; results are based

‘on national elevation datum The number of oceanographic surveys is summarized inTable 2.2

Table 2,2 Description of hydro-dynamics surveyContents | Stations | Pe id of survey Deseri

The device is st by 4 Hy mode,

W 1 rom 7109 Fun, | eee ase sdnes

Table 2 3 Quantity of taking suspended sediment and bottom sediment

Contents Locations Description

Bottom Sampling usin

Bottom sediment 15 3 days pines

mm

2.2.2 Water levels observation and field measurement

Results of measurement tide water level

‘The water level observations at foot of the bridge of beach Mui Nai in 3 days timemeasure are summarized and illustrated in Figure 24.

Waerled(em)

ii

Figure 2 4 Water level at rear beach of Mui Nai to 18 hours of June 6, 2016 to 18

hours of June 9, 2016Reviews tide water level measurement results: Overall, water level at the Mui Naibeach is quite similar to Ha Tien town, but with different amplitude,

‘Table 2 4 Water level characteristics at rear beach Mui Nai, Ha Tien town

Characteristies ‘Water level (em)

Maximum water level “

Minimum water level 2

Average water level 32

2.2.3 Wave data

Results calculated wave characteristics by spectrum method change depend on how

popular the parameter selected Results processed by the method of spectrum analysis

is for reference only, The annex table provides specific details for each hour waveanalysis of each probe in all three days

Table 2, 5 Results of characteristic wave at WVI station, averaged for each day

Days | Wave height H, (m) | Wave period Ty (s)June 7 029 3.10

June 8 028 2.86June 9 029 285

Results showed that treatment probe 2 value greater bias probe 1, both in terms ofdepth (more than 0.66 m), the wave height (0,02 m) and period (longer than 0.5 3).Results of wave characteristics are equal to the arithmetic mean value from the twoprobes To sum up, we will use statistical values and average hourly from two probesfor each day as shown in Table 2.5

‘Table 2 6 Characteristic of wave at WV1 station, the real beach resort of Mui NaiCharacteristics | H, Time Huy Time

Maximum | 225 Tune 7 156 June 7

Minimum — | 034 Tune 8 034 June 8

From the measurements carried out calculations of waves includes: the maximum

‘wave height and minimum wave height and medium wave height as shown in Table26

‘Through the data collected, we can see the frequency 4 Hz ensures the meter isrequired Matlab code of Verhagen (2013) was use for statistical characteristics of theWave; calculation results relatively reasonable

Using measured water level data to calibrate is recommended instead of curve fitting ifthe water level monitoring data fully In addition, the values Hyg T„ , Tạ and Tyoshould be calculated by means of wave spectrum with some parameters specified,2.24 Suspended sediment

Analysis results of samples suspended sediment in the Mui Nai beach area at 4sections long shore, as shown in Table 2.7 below

”

Table 2, TAnalysis of 12 samples suspended sediment in the Mui Nai beach

Numbers ‘The concentration of ‘Sampling locations ‘Suspended sediment (mg/l)

1 lo7at 12

? ma lạ

3 401.89 2-2 4090 23

2.2.5 Bed sediment sampling

Analysis result of bed sediment samples Dyso in the area Mui Nai in 4 sections alongshore, is presents in Table 2.5 below,

‘The average value calculated from the average diameter Dạ, of 8 samples is 161 jm

‘So, material to beach nourishment should have Dạ, about 180 to 200 ym,