Assessment of o loan lagoons water quality for aquaculture sector by mike 21 model under the impacts of climate change

MINISTRY OF EDUCATION
NHA TRANG UNIVERSITY
___________________________

BUI VINH DAI

ASSESSMENT OF O LOAN LAGOON’S WATER QUALITY FOR
AQUACULTURE SECTOR BY MIKE 21 MODEL UNDER THE
IMPACTS OF CLIMATE CHANGE

MASTER THESIS

KHANH HOA – 2017


MINISTRY OF EDUCATION
NHA TRANG UNIVERSITY
___________________________

BUI VINH DAI
ASSESSMENT OF O LOAN LAGOON’S WATER QUALITY FOR
AQUACULTURE SECTOR BY MIKE 21 MODEL UNDER THE
IMPACTS OF CLIMATE CHANGE
MASTER THESIS
Major:
Code:
Topic allocation Decision
Decision on establishing
the Committee:
Defense date:
Supervisor:

Ass.Prof. Ngo Dang Nghia
Chairman of Committee:
Ass.Prof. Pham Quoc Hung
Faculty
Studies:

of

Graduate

KHANH HOA – 2017


DECLARATION
I hereby declare that this thesis titled “Assessment of O Loan lagoon’s water quality
for aquaculture sector by Mike 21 model under the impacts of climate change” is the
result of my own research. It is original and no part of this work has been submitted
for any other degrees or diploma. All the given information is true to best of my
knowledge.
Nha Trang, 25th April 2017

Bui Vinh Dai


TABLE OF CONTENTS
LIST OF FIGURES .........................................................................................................v
LIST OF TABLES ....................................................................................................... vii
ACKNOWLEDGEMENT ........................................................................................... viii
ABSTRACT ...................................................................................................................ix
PREFACE ........................................................................................................................x

CHAPTER 1 ....................................................................................................................1
INTRODUCTION AND LITERATURE REVIEW .......................................................1
1.1. Application of numerical models for assessment of water quality ..........................1
1.1.1. International ...........................................................................................................1
1.1.2. In Vietnam .............................................................................................................3
1.1.3. Numerical model: MIKE 21 ..................................................................................4
1.2. Case study: O Loan lagoon.......................................................................................5
1.2.1. Natural characteristics ...........................................................................................5
1.2.2. Community characteristics ....................................................................................7
1.2.3. Aquaculture sector .................................................................................................8
1.2.4. Environmental problems in O Loan lagoon ..........................................................9
1.3. Research plan ..........................................................................................................11
CHAPTER 2. METHODOLOGY .................................................................................12
2.1. Data collection and Aggregation ............................................................................12
2.2. Data processing ......................................................................................................13
2.3. Assessment of water quality ...................................................................................13
2.4. Modeling method ....................................................................................................14
CHAPTER 3: APPLICATION MODEL, RESULTS AND DISCUSSIONS ..............17
3.1. Model Application ..................................................................................................17
3.1.1. Input data .............................................................................................................17
3.1.2. Creating Mesh .....................................................................................................23
3.2. Mike 21 Ecolab calibration ....................................................................................26
3.3. Model results in 2013 and 2014 .............................................................................30
3.3.1. Hydrodynamic .....................................................................................................30
3.3.2. Simulation results of pollution dispersion in 2013 and 2014 ..............................34
3.4. Model results in 2016 .............................................................................................45

iii

3.4.1. Hydrodynamic .....................................................................................................45
3.4.2. Simulation results of pollution dispersion in 2016 ..............................................49
CHAPTER 4. CONCLUSION AND RECOMENTDATIONS ....................................62
4.1. Conclusion ..............................................................................................................62
4.2. Recommendations ..................................................................................................62
REFERENCES ..............................................................................................................64
APPENDICES

iv


LIST OF FIGURES
Figure 1.1: Map of O Loan lagoon ....................................................................................6
Figure 1.2: Shrimp farming in O Loan lagoon ..................................................................8
Figure 1.3: Total production and aquaculture area in O Loan lagoon in 2014 ................9
Figure 2.1: A flowchart of Mike 21 modules ..................................................................15
Figure 3.1: O Loan lagoon’s bathymetry extracted from Mike 21 FM ...........................18
Figure 3.2: Water level monitoring in O Loan lagoon (October, 2013) ..........................19
Figure 3.3: Water level monitoring in O Loan lagoon (March, 2013) ............................19
Figure 3.4: Tidal water level monitoring in Tan Quy mouth (Octorber, 2013) ..............20
Figure 3.5: Tidal water level monitoring Tan Quy mouth (March, 2014) .....................20
Figure 3.6: Water sampling sites in O Loan lagoon ........................................................23
Figure 3.7: O Loan lagoon mesh extracted from Mike 21 FM ......................................24
Figure 3.8: Domain boundaries in O Loan lagoon extracted from Mike 21 FM ...........25
Figure 3.9: COD calibration, 10/2013 .............................................................................27
Figure 3.10:COD calibration, 3/ 2014 .............................................................................27
Figure 3.11: BOD calibration, 10/2013 ...........................................................................27
Figure 3.12: BOD calibration, 3/2014 .............................................................................27
Figure 3.13: TSS calibration, 10/2013 .............................................................................28
Figure 3.14:TSS calibration, 3/2014 ................................................................................28

Figure 3.15: N-NO3- calibration, 10/2013 .......................................................................28
Figure 3.16: N-NO3- calibration, 3/2014 .........................................................................28
Figure 3.17: PO43- calibration, 10/2013...........................................................................29
Figure 3.18:PO43- calibration, 3/2014..............................................................................29
Figure 3.19: Current flow pattern during high tide (0:00, 11/10/2013) ..........................31
Figure 3.20: Current flow pattern during low tide (8:00 am,10/10/2013)......................32
Figure 3.21: Current flow pattern during high tide (2:00 pm, 24/3/2014) ......................33
Figure 3.22: Current flow pattern during low tide (11:00 pm,24/3/2014) .....................34
Figure 3.23: Distribution of average COD concentration, 10/2013 ................................35
Figure 3.24: Distribution of average COD concentration, 3/2014 ..................................36
Figure 3.25: Distribution of average BOD concentration, 10/2013 ................................37
Figure 3.26: Distribution of average BOD concentration, 3/2014 ..................................38
Figure 3.27: Distribution of average TSS concentration, 10/2013 ..................................39

v


Figure 3.28: Distribution of average TSS concentration, 3/2014 ....................................40
Figure 3.29: Distribution of average N-NO3- concentration, 10/2013 ............................41
Figure 3.30: Distribution of average N-NO3-concentration, 3/2014 ..............................42
Figure 3.31: Distribution of average P-PO43-concentration, 10/2013 .............................43
Figure 3.32: Distribution of average P-PO43 concentration, 3/2014 ................................44
Figure 3.33: Current flow pattern during high tide (5:00 pm, 18/3/2016) ......................45
Figure 3.34: Current flow pattern during low tide (2:00 am, 19/3/2016)........................46
Figure 3.35: Current flow pattern during high tide (11:00 pm, 20/10/2016) ..................47
Figure 3.36: Current flow pattern during low tide (7:00 am, 20/10/2016)......................48
Figure 3.37: Distribution of average COD concentration, 3/2016 ..................................49
Figure 3.38: Distribution of average COD concentration, 10/2016 ................................50
Figure 3.39: Distribution of average BOD concentration, 3/2016 ..................................51
Figure 3.40: Distribution of average BOD concentration, 10/2016 ...............................52

Figure 3.41: Distribution of average TSSconcentration, 3/2016 .....................................53
Figure 3.42: Distribution of average TSS concentration, 10/2016 ..................................54
Figure3.43: Distribution of average N-NO3-concentration, 3/2016 ................................55
Figure3.44: Distribution of average N-NO3- concentration, 10/2016 ...........................56
Figure 3.45: Distribution of average P-PO43-concentration, 3/2016..............................57
Figure 3.46: Distribution of average P-PO43- concentration, 10/2016...........................58

vi


LIST OF TABLES
Table 1.1: Distribution of population in O Loan lagoon, 2014 .....................................8
Table 1.2: Type of shrimp farming in O Loan lagoon in 2014 .....................................9
Table 2.1: Data collection and sources........................................................................12
Table 2.2: Summary of water quality standards relevant to coastal water aquaculture
.....................................................................................................................................13
Table 3.1: Water depth in O Loan lagoon ...................................................................17
Table3.2: Wind speed in O Loan lagoon.....................................................................21
Table 3.3: Pollution loading in O Loan lagoon, 2014 ................................................22
Table 3.4: Initial conditions of Mike 21 Ecolab..........................................................26
Table 3.5: Pollution dipersion coefficients .................................................................29

vii


ACKNOWLEDGEMENT
First of all, I would like to express my sincere gratitude to NOHERD project for giving
me a chance to study in international environment with experts and students from
many countries around the world.
I would like to send my deep appreciation to my supervisors: Ass. Prof. Ngo Dang

Nghia for his supports and teaching me from beginning to ending this master course,
Prof.Sigurd Stefansson and Prof. Henrik Glenner for giving me useful advices for my
thesis. My study could not be finished without their assistances.
My sincere gratitude goes to Ms. Tran Xuan Hoang – Institute for Environment and
Resources who help me to use Mike 21 model and Ms. Nguyen Thanh Son who allow
me to use data in his project. I also express thanks to The South Central Station for
Hydro - Meteorological and Institute of Nha Trang Oceanography give me data on
hydro-meteorological for running the model.
I would like to thank all my Cohort 1 classmates who have supported me in this
course.
Finally, this thesis is dedicated to my family who have always stood by me and
supported in my life.

viii


ABSTRACT
The economic activities in coastal area have been causing negative impacts on the
environment nowadays. O Loan is a coastal brackish water lagoon in Tuy An district,
Phu Yen province. It is a famous tourist destination and a national-level landscape of
Phu Yen province. However, the quality of water in the lagoon is currently being
polluted by livelihood activities of people living around the lagoon, aquaculture in
particular. In addition, the influences of climate change in recent years have attributed
to deterioration of water environment in area. There have not been any studies using
numerical model to assess its impacts on water quality in O Loan lagoon yet.
The purpose of the research is to create a numerical model to simulate hydrodynamics
and dispersion process of pollutants in dry season and rainy season under the impacts
of climate change aspects from pollution sources in lagoon and assessment water
quality for aquaculture activities. Among many numerical models exit today to
simulate the dispersion process of pollutants, the Mike 21 model developed by DHI

has been used because of many strong features. Mike 21 model is a comprehensive
coastal model to simulate hydrodynamics, sand transport, mud transport and
advection-diffusion of pollutants.
The input data was collected from vary sources and model calibration based on data of
water quality monitoring in O Loan lagoon in 2013 and 2014 by Ms. Nguyen Thanh
Son conducted. Assessment of water quality for aquaculture based on available
standards including: National technical regulation on coastal water quality applying for
aquaculture and aquatic life conservation area ( NTR 10 : 2008/MONRE) approved
by VietNam Ministry of Natural Resources and Environment and ASEAN Marine
Water Quality Criteria .
The model results were found to be in good agreement with surveyed data and shown
hydrodynamics pattern and dispersion process of five pollutants including COD, BOD,
TSS, NO3-, PO43- in dry season and rainy season under vary hydro-meteorological
conditions. In general, the water quality in rainy season is better than in dry season.
The local pollution phenomenon appears in the Southwest and Northwest in O Loan
lagoon for both seasons. Evaluation of climate change impacts shows that it is greatly
effect on simulation results, the quality of water is deteriorating in dry seasonwhile
there was an improvement in rainy season. In conclusion, limitations of the research
and future direction are outlined.

ix


PREFACE
Sited at about 22km away from the city of Tuy Hoa in the North, O Loan lagoon is a
typically coastal lagoon in mainland of Tuy An district, Phu Yen province, stretching
from North to South. O Loan lagoon is a approximately 17.5 km2 area with an average
depth of 1.2 – 1.4 m. This is a famous national landscape attracted tourists visiting Phu
Yen province. Surrounding the lagoon, there are 50.000 people living on five communes,
whose livelihood has been getting from Agriculture, Tourism-service, Aquaculture and

Fishing sector. Aquaculture sector plays an important role and affects directly the day-today living of thousands of people. However, in recent years, the dramatic increase in area
of aquaculture without reasonable planning strategy and the discharge of wastewater
directly into lagoon have led to deterioration of water quality, affecting economic
activities of people lived around.
The untreated wastewater from aquaculture has been discharged directly into the O
Loan lagoon. The dynamic process (flow, wind, tidal pattern, disturbance...) causes
diffusion process and brings pollutants in wastewater distributing over places of
lagoon followed flow in local tidal pattern. Moreover, in recent year, this area has
witnessed increasing impacts of climate change. The extreme weather phenomena
such as: droughts and floods, thunderstorms, cyclones…have occurred frequently in
dry and rainy seasons, affecting the lives of the people here.
One of the approaches in studying impacts of wastewater sources is using
mathematical models to calculate and simulate physical and biochemical process in
interested area. The results from model integrated actual data survey can continually
simulate the dynamics and material transport process occurring in lagoon.
A number of studies have been carried out in O Loan lagoon such as Survey of bottom
sediment of Phu Khanh coastal area (Institute of HDH, 1997); Research on fisheries
resources in O Loan lagoon (Nguyen Van Chung and Huynh Quang Nang, 1980); Study
of geomorphology and surface sediments (Pham Van Thom et al, 1981); Environmental
quality in O Loan lagoon, Phu Yen province (Le Thi Vinh et al, 2009); Application of
remote sensing and GIS in the study fluctuations shoreline at O Loan lagoon area from
1965 to 2011 (Tran Van Binh et al, 2011); Study of erosion - accretion processes and inlet
opening/closing phenomenon in O Loan lagoon, Phu Yen province (Tran Van Binh and

x


Le Dinh Mau, 2012); Assessing the environment status and the risk of environmental
catastrophe in O Loan lagoon, Tuy An district, Phu Yen province (Nguyen Thanh Son et
al, 2016). These studies provided quite adequate evaluation of aquatic resources, water

and sediment quality, geomorphology and data on the socio-economic situation
surrounding O Loan Lagoon. However, no present studies has been conducted in the O
Loan lagoon to assess the hydrodynamic regime and the dispersion of pollutants as well as
those from pollution sources discharged into the lagoon under the influence of climate
change, which is one of the most challenges facing us in early years of the 21st century.
Realizing the environmental problems occurring in O Loan lagoon, the trainee Bui
Vinh Dai has decided to conduct a research title: "Assessment of O Loan lagoon’s
water quality for the Aquaculture sector by Mike 21 model under the impacts of
climate change" in order to simulate the pollutants dispersion that can affect
aquaculture sector in O Loan lagoon, Phu Yen province. To assess the impacts of
water pollution on aquaculture activities, the author selected recognized environmental
parameters including: Nutrient Pollution Index (NPI) NO3-, PO43-, Organic Pollutant
Index (OPI) COD, BOD, TSS. The data is get from the provincial research project:
“Assessing the environment status and the risk of environmental catastrophe in O
Loan lagoon, Tuy An district, Phu Yen province" chaired by Nguyen Thanh Son and
The South Central Station for Hydro - Meteorological and Institute of Nha Trang
Oceanography. Trainee uses the Mike 21 modeling suite to simulate the pollutant
dispersion that can be causing the water pollution for aquaculture in two seasons: the
rainy season of 2013 and dry seasons of 2014 and assess impacts of climate change on
this process in 2016 in O Loan lagoon.
The results of the thesis provide additional scientific information on the impact of
environment parameters for the aquaculture sector under different dynamics conditions
in O Loan lagoon. This work also contribute to helping managers give more flexible
responses, suitable planning policies for aquaculture activities in order to protect
environment and improves the quality of people’s life in lagoon.

xi


CHAPTER 1

INTRODUCTION AND LITERATURE REVIEW
1.1. Application of numerical models for assessment of water quality
1.1.1. International
Numerical modeling is frequently used to assess water quality in coastal water area,
estuary and sea over the world. The application of numerical models can vary
depending on the objectives and purposes of each research. There are a number of
models that are normally used to assess the water environmental quality, which are:
The WASP7 model (Water Quality Analysis Simulation Program 7) is an
enhancement of the original WASP is used to describe and predict the water quality to
assist the managers in making decisions and taking measures to deal with
environmental pollution problems. This model allows users to spatially apply one, two
and three-dimensional space with diversity of the composition of pollutants. The
WASP model can also be linked to hydrodynamic and sediment transport models to
obtain flow regime, temperature, salinity and sediment loading. The WASP model was
used to simulate the anaerobic process in Tampa Bay; Phosphorus supply for
Okeechobee Lake. Anaerobic process at Neuse River; Pollution of biodegradable
organic materials in the Delaware river, Heavy metal pollution in Deep River, North
Carolina (Di Toro et al., 1983; Connolly and Winfield, 1984; Ambrose, R.B. et al., 1988).
The AQUATOX model simulates the aquatic ecosystem. The model can forecast the
decline process attributed to various types of environmental pollutants such as
nutrients, organic chemicals and assess influences of process on entire ecosystem
including fish, invertebrates and aquatic plants. The AQUATOX model is an effective
tool for the environmentalists, biologist and others who are interested in risk
assessment and declining process of aquatic ecosystems (Robert A. Pastorok et al.,
2013).
The QUAL2K model (River and Stream Water Quality Model) was upgraded from the
previous model (QUAL2E or Q2E). This one-dimensional model simulates the water
quality in the streams and rivers involving the water disturbances process. A flexible

1

feature of this model is that it isable to run in the Visual Basic Operating System and
Excel software. The characteristics of this model can be calculated on each segment of
the river and its tributaries, the nitrogen cycle, based on nitrogen process to present
carbon compounds and the ability of oxygen and nutrient exchange between sediment
and water (Brown and Barnwell 7, 1987).
The DELFT 3D model (designed by Netherland Hydraulic Institute) allows
combination of three-dimensional hydrodynamic model and water quality model. The
advantage of this model is the combination of complex modules to provide simulating
results for multi-substances and processes involved (Anton J. Schleiss, Giovanni De
Cesare, 2014).
The SMS model (designed by Center for research and technical development of United
States military) allows combination of one and two-dimensional hydraulic model with
water quality model, in which, the RMA4 module is the numerical model of water
quality elements uniformly distributed with depth. It can be calculated in onedimensional mesh or two- dimensional mesh (Militello and Zundel, 1999).
The ECOHAM model (version 1 and 2) is a 3D numerical model combining hydraulic
module and ecological module that was developed by the research team of the
Hamburg University (Germany). This model calculated based on cycles of nitrogen
and phosphorus components. It also can be calculated for both plants and zooplankton
in the seawater (Moll, 1997, 1998).
The BASINS model (Designed by EPA- United States Environmental Protection
Agency) assists the assessment of environmental information system, environmental
analysis system and analyzing of management measures. One of the advantages of this
model is already included in the new approach based on river basin incorporating
spatial data through GIS geographic information system. The Basins model can be
used for the following purposes: Simulating the conditions of the basin and assessing
the status of water quality, scenarios of pollution source, the impact of land use
changing related to water balance, development of basins management measures. The
parameters of the model include nutrient compounds of nitrogen and phosphorus, DO,

BOD, pesticides, sediment (Grady Hanrahan, 2010).

2


The MIKE 21 model is an engineering software developed by Danish Hydraulic
Institute (DHI) and be commercialized. It is used to simulate the hydraulic regime,
water quality and sediment transportation in coastal, estuary area and the sea. There
are many modules integrated in the model Mike 21 suite and depending on research
objectives these modules will be used. The Mike 21 modeling suite has been used
popularly in coastal engineering and application in many countries around the world
(Sébastien Erpicum et al., 2016).
1.1.2. In Vietnam
In Viet Nam, application of the numerical modeling in environmental studies in
coastal and estuary received attention in recent years. Numerical models have been
used to calculate water pollution in coastal area in many studies such as: Institute of
Natural Resources and Marine Environment - Institute of Science and Technology of
Vietnam under supported of the Japanese Government (Program JICA, 1995 - 1998)
was initially used the Flux and Budget methods running on dedicated software
CABARET of LOICZ (USA) to evaluate the accumulation and diffusion of pollutants
in Ha Long Bay. Then, this research method was used to calculate the nutritional level
of the Tam Giang - Cau Hai lagoon (Hue province, Viet Nam). However, a
disadvantage of this method is that it does not calculate the process of material
diffusion in space and confined in a number of certain points (Truong Van Tuyen et
al., 2006).
In Ministry of Fishery project, Tran Luu Khanh studied the carrying and selfpurification capacity in fishing cages area in Phat Co (Quang Ninh province) and Tung
Gau (Hai Phong province). The study based on the nutrient and organic metabolism
process integrated the hydrodynamic processes in area (Tran Luu Khanh, 2004)
Phan Minh Thu, Nguyen Huu Huan (1999) were used the method of modelling
biological processes to study the self- purification process in Nha Trang bay under

impact of domestic wastewater. However, this study did not calculate the influence of
coastal hydrodynamic (transportation, diffusion) under the tidal pattern.
Thai Ngoc Chien, Nguyen Tac An, Bui Hong Long (Institute of Nha Trang
Oceanographic) were used the 3-dimensional ECOHAM model to calculate nutrient

3


dynamics in Van Phong Bay (Khanh Hoa province) and given out the seasonal
fluctuations of nitrogen and phosphorus concentration in the Bay (Bui Hong Long et
al., 2006)
A project chaired by Vietnam Academy of Science anh Technology has been carried
out to study the carrying capacity of Cam Ranh Bay by the ECOSMO model. Project
used model to calculate the pollutants dispersion, biochemical processes in order to
assess self-purification capacity in Bay (Phan Thanh Bac, 2012).
Nguyen Chi Cong – Ha Noi university of Natural Science, 2012 was used Mike 21
model to calculate pollutants dispersion in Nha Trang bay from Cai river and Tac
river. Simulation results from model give an overview of sea water quality in Nha
Trang’s beaches which are affected by untreated domestic wastewater from city
discharging into the Bay in recent years (Nguyen Chi Cong, 2012).
In O Loan lagoon, there are a number of studies undertaken but their focus on
assessment of environmental situation, fishery resources, socioeconomic status. There
is no study using numerical models to simulate the process of pollution dispersion
under impacts of dynamics process and climate change. Application of Mike 21 model
to calculate water quality for economic activities, aquaculture sector in particular is an
approach trainee chose.
1.1.3. Numerical model: MIKE 21
The MIKE 21 model is dedicated software is developed by Danish Hydraulic Institute
(DHI) used to simulate the hydraulic regime, water quality and sediment transportation
in the river estuary, coastal and the sea. There are many modules in MIKE 21

modeling suite with vary features such as:
 Hydrodynamics module (MIKE 21/3 HD)
 Spectral Wave module (MIKE 21 SW)
 Littoral Processes and Coastline Kinetics ( LITPACK)
 Flood Forcasting ( MIKE 21 FF)
 Sand Transport module (MIKE 21/3 ST, MT)
 Oil Spill module (MIKE 21 OS)

4


 Ecological module (MIKE 21 ECOLAB)
 Advection Dispersion (MIKE 21 AD)
Among MIKE 21 modules, the module MIKE 21 FM is the core of the MIKE 21
modeling suite. It calculates hydrodynamic regime to build up the foundation for other
modules.
The strong features of Mike 21 model compared to other models: application for
variant water bodies in river basin, estuary, coastal and the sea. Because of it utilisable
and friendly interface, Integrated Geographic Information System (GIS) is used to
extract data exactly and visual, time setup quickly, provision of flexible mesh which
enables more accurate representation of the actual area. On the other hand, the
disadvantages of this model is some calculation results is incorrect with actual data
survey, the running speed is still limited, especially MIKE 21 FM module.
In this thesis, the module FM and module ECOLAB of MIKE 21 modeling suite were
used to simulate hydrodynamics regime, process of pollutants dispersion entire lagoon
in dry season and rainy season in 2013-2014 and 2016.
1.2. Case study: O Loan lagoon
1.2.1. Natural characteristics
a) Geographical location
O Loan lagoon is located in the south of Tuy An district, next to Quan Cau Pass and

adjacent to to An Cu, An Hoa, An Hai, An Hiep and An Ninh Dong commune. Lagoon
has geographic coordinates 13013'50" to 13019'00" north latitude and 109014'30" to
109017'30" east longitude.
It is a brackish water and almost belonged to mainland with about 17.5 km2, stretching
from North to South, the widest point of 2.5 km, longest point of 8 km, 1.2 km2 of the
surface area and 1.2m -1.4m of average depth. The mouth of lagoon is namely Tan
Quy with about 100m of width.

5


Figure 1.1: Map of O Loan lagoon ( />b) Topographic
Topography around lagoon is complex, hills intervened by small valley. The Eastern of
lagoon was formed by many low sand dunes. The average elevation of hills is lower
than 200m and formed from granite, basalt layers. The lagoon is surrounded by Dong
Chay mountain, Cam mountain and peninsulas of An Ninh Dong, An Hai, An Hoa.
c) Hydro - Meteorological
 Wind
Trade wind and monsoon wind is prominent in Phu Yen province. Wind direction was
recorded from North, Northeast, East with average speed of 2.2m/s in coastal and of
1.7 m/s in mountain respectively. In addition, the plain climate is harmonized partly
by phenomenon of "seabreeze" in coastal area.

6


 Temperature
The absolute maximual temperature was 300C with the average annual of 60-90 days
that caused hot weather in area. The absolute maximum temperature was 15-16 0C in
the coastal plain (Source: Characteristics of Phu Yen hydro-meteorology).

 Precipitation
Precipitation in Phu Yen province is mostly concentrated in rainy season from August
to December every year and tends to be higher year to year. In December of 2016, the
highest precipitation was over 200mm per day in Tuy An district.

 Water flow
Water flow in lagoon influenced by four factors: monsoon wind system, wind,
bathymetry, tidal regime. However, the water is exchanged daily between lagoon and
the sea by only a Tan Quy mouth, the depth and width of lagoon were small, the top of
the lagoon is narrow (200m - 500m). Thus, the water flow is completely affected by
tidal current.

 Salinity
Salinity in O Loan lagoon is not different to that of coastal lagoons in Viet Nam. The
highest salinity is 3.6 %, the lowest is 2.15% and the average one is2.78% (Source:
Characteristics of Phu Yen hydro-meteorology).
 Tidal pattern
The tidal in Phu Yen coastal is similar to tidal pattern of South Central coastal of Viet
Nam with mixed tidal. O Loan lagoon's mixed tidal pattern may have characteristics of
both diurnal and semidiurnal tides with amplitude of tidal increases from North to South.
1.2.2. Community characteristics
The total population of five communes in O Loan lagoon was estimated 47,963 people
in 2014, according to Statistical Yearbook of Tuy An 2014. Table 1.1 provides
detailed information about community in O Loan lagoon.

7


Table 1.1: Distribution of population in O Loan lagoon, 2014

Commune

Area (km2) Population (P) Density (P/km2)

Village

An Ninh Đông

26,5

12.945

488

4

An Hai

14,7

3.505

238

6

An Cu

22,6

11.116

492

5

An Hoa

23,2

12.418

535

8

An Hiep

47,7

8.429

178

6

(Source: Statistical Yearbook of Tuy An 2014)

There are many economic sectors that create employment and livelihoods for
community in O Loan including fishery, agriculture, tourism services. The aquaculture

sector plays an important role to create the livelihoods for 3,900 people.
1.2.3. Aquaculture sector
The total aquaculture area of five communes in O Loan lagoon in 2014 was 544
hectares, in which 97 hectares was used for fish and bivalves farming (17.8%) and 477
hectares was used for shrimp farming (82.2%).

Figure 1.2: Shrimp farming in O Loan lagoon
Total aquaculture production in O Loan lagoon in 2014 was 1549 tons, in which
shrimp production reached 1524 tons (98.4%). Figure 1.2 shows total production and
aquaculture area in five communes in O Loan lagoon 2014.

8


160

600

140

500

120
400

100
80

300

60

Aquaculture
area (ha)

200

40
100

20
0

0
An Hai

An Hiep

An Cu

An Ninh Dong

Aquaculture
production
(tons)

An Hoa

Figure 1.3: Total production and aquaculture area in O Loan lagoon in 2014
(Source: Statistical Yearbook of Tuy An 2014)

The white shrimp and black tiger shrimp are main species cultured in O Loan lagoon.
Not many of fish and bivalve species were farmed in An Hai and An Cu commune.
Intensive farming and extensive farming are types of aquaculture in lagoon. Intensive
shrimp farming in high tidal area has become a main form of aquaculture in most of
communes surrounding the O Loan lagoon.Table 1.2 presents the percentage of
aquaculture type in five communes in 2014.
Table 1.2: Type of shrimp farming in O Loan lagoon in 2014
An Ninh
Type

Dong

An Hai

An Cu

An Hiep

An Hoa

Intensive (%)

85

60

45

75

100

Semi-intensive (%)

15

40

55

25

0

(Source: Statistical Yearbook of Tuy An 2014)

1.2.4. Environmental problems in O Loan lagoon
Recent environmental studies have shown that, the deterioration of water quality is due
to livelihood activities around the lagoon, especially aquaculture activities. The
increase in aquaculture area without reasonable planning led brought negative impacts
on water environment. It can influence back to aquaculture and other area.This is the
main problem that needs to be tackled by local managers because O Loan lagoon is not

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only a famous scenic destination but also a livelihood source for thousands of people
living around.
The erosion - accretion phenomenon in O Loan coastal is seasonally occurring with

strong in intensity and complicated in manner under impacts of human being and
natural.

In recent years, due to impacts of climate change, the process erosion-

accretion in O Loan lagoon has been intensively taken place, posing threats for human
life and geological environment.
Climate change has begun to show its impacts in O Loan lagoon in recent years. The
extreme weather phenomena have increased in frequency and intensity. According to
National Centre for Hydro - Meteorological Forecasting, the South Central region has
suffered the El Nino phenomenon over past 3 years (2014-2016). The effects of El
Nino led to high temperature, a shortage of precipitation, saltwater intrusion in South
Central provinces. In Tuy An district, prolonged drought appeared more frequent in
dry season resulting in prolonged shortages in water supply, saltwater intrusion recent
years. In 2014, the satlwater intrusion was detected in upstream about 2km far from
Hai Yen estuary that has not been recorded before.
On other hand, under impact of La Nina phenomenon, the mechanism of storms and
flood was unpredictable especially intensity, speed, direction of movement and heavy
rain, thunderstorms related. The storm frequency did occur in Phu Yen many years
before and in December of 2016, Phu Yen province was recorded a historic flood after
decades which caused serious damages people and heavy economic losses in community.
Overally, the quality of the environment is being threatened by the economic activities
surrounding and the initial impacts of climate change aspects. It is a key challenge for
local authorities to develop strategy of sustainable development in O Loan lagoon in
the near future.

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1.3. Research plan

A brief overview of research plan is shown in below flowchart

Reading references and Building research methodology

Data collection

Running Mike 21 model (Mike 21 FM and Mike 21 ECOLAB)
- Calibration and running model with data in 2013 and
2014
- Using hydro-meteorological data in 2016 based on
calibrated model of 2013, 2014

Assessment of water quality for aquaculture sector based on
Natural technical regulation on coastal water quality (NTR 10
: 2008/MONRE) and ASEAN standard

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CHAPTER 2. METHODOLOGY
2.1. Data collection and Aggregation
In this study, collecting and aggregating data including documents/data on
environment, hydro-meteorological and socio-economic in O Loan lagoon, Tuy Hoa
district, Phu Yen province for modelling is very important to run the model. These
were obtained by:
-

Inheriting, analysis and synthesis of materials, data sources that related to Loan
lagoon.

-

Collecting, assessing and analyzing the existing data sources according to the
traditional analytical methods.

-

An overview of domestic and international documentsrelated to field of study,
conferences, seminars... seek to build research methodology.

The table 2.1 shows the number of data and sources that will be used in running
MIKE 21 model.
Table 2.1: Data collection and sources
No.
1

Data
Bathymetry

Periods

Sources

2013, 2014

Project: “Assessing the environment status
and the risk of environmental catastrophe
in O Loan lagoon, Tuy An district, Phu
Yen province” (2013-2016)

O Loan lagoon’s water
2

level
Tidal

2013, 2014, 2016 The South Central Station for Hydro Meteorological and Institute of Nha Trang
Oceanography

Wind
3

Wave

2013, 2014, 2016 Global wave model (Wave – Watch III)
2013, 2014, 2016 Project: “Assessing the environment status

4

and the risk of environmental catastrophe

Pollution loading

in O Loan lagoon, Tuy An district, Phu
Yen province” (2013-2016)
2013, 2014

5

Project: “Assessing the environment status

and the risk of environmental catastrophe

Water quality monitoring

in O Loan lagoon, Tuy An district, Phu
Yen province” (2013-2016)

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2.2. Data processing
In this study, Excel software was used to aggregate input data, assess calibration
results of module ECOLAB, drawing graphs, charts to simulate. This is a program
package of Microsoft office software that is widely used in the world. The Excel
software can do many complex calculations and show through charts, graphs in a
flexible in manner.
2.3. Assessment of water quality
To assess the impacts of water pollution on aquaculture, the author selected recognized
environmental parameters including: Nutrient Pollution Index (NPI) NO3-, PO43-,
Organic Pollutant Index (OPI) COD, BOD, TSS. The water quality assessments were
based on available standards for coastal aquaculture including: National technical
regulation on coastal water quality applying for aquaculture and aquatic life
conservation area (NTR 10 : 2008/MONRE) approved by VietNam Ministry of
Natural Resources and Environment) and ASEAN Marine Water Quality Criteria.For
BOD criteria, the National technical regulation on surface water quality (NTR
08:2015/MORNE) applying for aquatic life conservation will be used to evaluate. The
maximum allowable concentration of criteria was shown in Table 2.2.
Table 2.2: Summary of water quality standards relevant to coastal water
aquaculture
Unit

Standards and Parameters
NTR
10:2008/MONRE

ASEAN Standard

NTR
08:2015/MONRE

COD

TSS

N-NO3-

P-PO43-

BOD

3

50

0.06

0.015

4

Concentration
(mg/l)

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