SALINITY INTRUSION AND
ADAPTATION SOLUTIONS
Assessing the transformation from rice to shrimp
as an approach to cope with salinity intrusion in
Salinity intrusion and adaptation solutions:
Assessing the transformation from rice paddies to shrimp farming to adapt to increasing saline
intrusion in the Vietnamese Ben Tre province
Name: Pham Dang Manh Hong Luan
Student ID: 851022651180
Department: Environmental System Analysis Group
Wageningen University and Research
Thesis supervisors:
dr. AR (Andre) van Amstel
Environmental System Analysis Group
Department of Environmental Science
Wageningen University and Research
dr. Ngo Thi Phuong Lan
Department of Anthropology
University of Social Science and Humanities
Environmental System Analysis
MSc Environmental Sciences
Wageningen University and Research
a
Table of contents
List of tables............................................................................................................................................ i
List of figures ......................................................................................................................................... ii
Acknowledgement ................................................................................................................................iii
Summary............................................................................................................................................... iv
I PROBLEM FORMULATION..................................................................................................... 1
1.1
Introduction on study area ................................................................................................... 1
1.1.1
Natural characteristics of Ben Tre province .............................................................. 1
1.1.2
Socio-economic characteristics of Ben Tre province ................................................. 2
1.2
Problem statement ................................................................................................................ 4
1.2.1
Salinity intrusion in Ben Tre province ........................................................................ 4
1.2.2
Rice farming – a precarious livelihood........................................................................ 5
1.3
Research objectives ............................................................................................................... 7
1.4
Conceptual framework ......................................................................................................... 7
1.5
Research questions ................................................................................................................ 8
1.6
Outline of the report ............................................................................................................. 8
II METHODOLOGY ..................................................................................................................... 10
2.2
Multi-criteria analysis (MCA) ........................................................................................... 10
2.3
Literature study .................................................................................................................. 12
2.4
Data collection and field survey ......................................................................................... 12
2.5
GIS ........................................................................................................................................ 14
III HISTORY OF RICE INTENSIFICATION AND SHRIMP FARMING IN BEN TRE
PROVINCE ......................................................................................................................................... 17
3.2
Rice expansion period from 1975 to 1990 ......................................................................... 17
3.2
Rice intensification from 1990 to 2000 .............................................................................. 17
3.3
Period 2000-2010 ................................................................................................................. 17
3.4
Planning for rice and shrimp farming from 2010 to 2020 ............................................... 18
IV SHRIMP FARMING .................................................................................................................. 22
4.1
Type of shrimp farming ...................................................................................................... 22
4.2
Mono-shrimp cultivation .................................................................................................... 24
4.3
Rice-shrimp rotation system .............................................................................................. 26
V RESULTS .................................................................................................................................... 28
5.1
Level of salinity intrusion in Ben Tre province ................................................................ 28
5.1.1
Selection of scenarios .................................................................................................. 30
5.1.2
Extent of salinity intrusion ......................................................................................... 30
5.2
Areas for rice-to-shrimp transformation .......................................................................... 32
5.3
Impact assessment of the rice-to-shrimp transformation ................................................ 34
5.3.1
Food security ............................................................................................................... 34
5.3.2
Economic development ............................................................................................... 35
5.3.3
Environmental sustainability ..................................................................................... 36
5.4
Optimal solution for the area ............................................................................................. 42
VI DISCUSSION .............................................................................................................................. 46
6.1
The extent of salinity intrusion in Ben Tre province ....................................................... 46
6.2
Area for rice-shrimp transformation ................................................................................ 46
6.3
Impacts implied in the rice-shrimp transformation ........................................................ 46
6.4
Optimal solution for the area ............................................................................................. 47
VII CONCLUSION ........................................................................................................................... 49
References ............................................................................................................................................ 50
Appendices ........................................................................................................................................... 54
b
List of tables
Table I.1: Gross output (billions VND) of cultivation at current prices (2015) by crop groups............ 3
Table I.2: Gross output (billion VND) of aquaculture at current price (year 2015) .............................. 4
Table II.1: Goals, criteria and indicators for criteria applied in the research ...................................... 10
Table II.2: List of scenarios of development and its weight to goals .................................................. 11
Table II.3: Source of data for scoring in MCA .................................................................................... 12
Table II.4: Primary data to be collected............................................................................................... 14
Table III.1: Area (ha) for rice farming landuse and cumulative area of rice crop in 3 seasons paddy
by district in 2010 (Ben Tre SO, 2015) ................................................................................................. 20
Table IV.1: Shrimp species nurtured in the studied area and their favorable range of salinity level . 23
Table V.1: Scenarios in the study on salinity intrusion (Toan, 2014) .................................................. 29
Table V.2: Salinity levels of water and their suitable use .................................................................... 30
Table V.3: Original scores of criteria and their normalized values...................................................... 40
i
List of figures
Figure I.1: Map of Ben Tre province ..................................................................................................... 1
Figure I.2: Gross output (billion VND) at current price by economic sectors from 2010 to 2015 ........ 3
Figure I.3: Monthly consumption of rice and meat of an individual in Vietnam from 2002 to 2012 ... 5
Figure I.4: Seasonal calendar in the Mekong Delta and the periods of saline- intrusion- related events
................................................................................................................................................................ 6
Figure I.5: Conceptual framework ......................................................................................................... 7
Figure II.1: Map of survey area ........................................................................................................... 13
Figure II.2: Flowchart describing GIS application in the research...................................................... 15
Figure III.1: Map of rice farming activity in 2010 .............................................................................. 19
Figure III.2: Landuse map of Ben Tre province in 2010..................................................................... 19
Figure III.3: Map of landuse planning of Ben Tre province to 2020 .................................................. 21
Figure IV.1: Shrimp production (tons) by district from 2010 to 2015 ................................................ 22
Figure IV.2: Extensive shrimp pond in Ben Tre province ................................................................... 25
Figure IV.3: Intensive mono-shrimp culture in Ben Tre province ...................................................... 26
Figure IV.4: Rice-shrimp field in Ben Tre .......................................................................................... 27
Figure V.1: Average salinity level in dry seasons in condition 2005 .................................................. 31
Figure V.2: Area (ha) by district under different duration (days) of impact by salinity level 4ppt ..... 32
Figure V.3: Map of duration (days) of salinity level 4ppt in the condition 2005 ................................ 32
Figure V.4: Map of duration of salinity level 4ppt affecting rice crops .............................................. 33
Figure V.5: Map of rice-shrimp transformation in 2020 ..................................................................... 34
Figure V.6: Food security scores of three options of land-use ............................................................ 43
Figure V.7: Economic development scores of the three options of land-use....................................... 43
Figure V.8: Environmental sustainability scores of the three options of land-use .............................. 44
Figure V.9: Graphs illustrating scores of mono rice farming with respect to three criteria (on the left)
and the its final scores in each scenario of development (on the right) ................................................ 45
Figure V.10: Graphs illustrating scores of intensive shrimp farming with respect to three criteria (on
the left) and the its final scores in each scenario of development (on the right) ................................... 45
Figure V.11: Graphs illustrating scores of rice-shrimp farming with respect to three criteria (on the
left) and the its final scores in each scenario of development (on the right)......................................... 45
ii
Acknowledgement
The idea for this thesis came from my experience of more than two years working as a researcher in
Center of Water Management and Climate Change (WACC) whose duty mainly focuses on natural
changes and social dynamics in the Mekong Delta. It was also inspired by my special love for the
Mekong Delta, the land of prosperity but can still preserve its idyll.
I would like to express my gratitude to Wageningen University and Environmental System Analysis
group for creating opportunity for me to do this research. I also want to send my gratitude to Dr.
Andre van Amstel of Wageningen University and Dr. Ngo Thi Phuong Lan of University of Social
Science and Humanities for supervising me in this research.
I would like to thank Sub-Institute of Hydrometeorology and Climate Change (SIHYMECC),
especially Mr. Tran Tuan Hoang, head of Hydrological department and Mr. Truong Hoai Thanh,
expert of Meteorological department for allowing me to work part-time in the office, supporting me in
modelling job, and sharing precious data and information. I also would like to thank Dr. To Quang
Toan, expert of Southern Institute of Water Resources Research (SIWRR) for sharing the result of his
research on salinity intrusion in the Mekong Delta.
Lastly, I would like to send great gratitude to Mr. Dinh Quang Toan, lecturer of the University Thu
Dau Mot, Binh Duong and Mr. Pham Van Luan, lecturer and head of Ben Tre Young Creative Group
of Ben Tre University for giving enormous support in my field trip in Ben Tre province. Without their
great help in making contact with local government, the field trip could have never been done.
iii
Summary
Ben Tre is a coastal province in the Mekong Delta of Vietnam. As a coastal province, it is frequently
under the impact of saline intrusion, especially in the dry season. The impacts of saline intrusion
cause severe problems to freshwater livelihoods in the area. Rice farming; in specific, is the most
vulnerable freshwater livelihood in the condition of saline intrusion due to its heavy reliance on the
availability of freshwater. Rice farming in the Mekong Delta is also notorious for its low profit,
trapping rice farmers in poverty. Therefore, the research aims to assess the transformation from rice to
shrimp cultivation to cope with increased saline intrusion in Ben Tre province and find the optimal
solution. Output from model of saline intrusion taken from previous study was applied to analyze the
extent of salinity intrusion in Ben Tre province. The model outputs were then overlaid with a land-use
map planning to 2020 and rice-crop calendar to identify areas where rice was feasibly transformed to
shrimp. Impacts of the rice-shrimp transformation were then assessed. In this research, the impacts on
food security, economic development and the environment were considered. Groups of criteria for
these three dimensions and their indicators were identified using literature review. Data for the impact
assessment came from the field survey and partly from available literature. Lastly, a multi-criteria
analysis (MCA) was then applied to compare different land-use options such as 3-season mono-rice
fields, 3-season industrial shrimp farming and the rice-shrimp rotation farming. The application of
MCA is to find the optimal option between the three options. Results pointed out that any adopted
land-use option implies substantial trade-offs between food-security target, economic development
and the environment. The research also showed that the rice-shrimp rotation model is the optimal
option for the region thanks to its capability of reconciling the conflicting interests on food security,
better income and environmental sustainability.
iv
I
PROBLEM FORMULATION
1.1
Introduction on study area
1.1.1
Natural characteristics of Ben Tre province
Figure I.1 shows the map of the Vietnamese Ben Tre province. It is is one of thirteen provinces of the
Mekong Delta and locates in the coastal area of this delta. Its northern side borders the Tien Giang
province and the western and southern side borders the Vinh Long province. Its eastern side borders
the South China sea (or the East Sea in Vietnam’s naming system) through three estuaries Dai, Ham
Luong and Co Chien. The whole province is subdivided into nine administrative units including one
city and eight districts. Ben Tre city is the administrative, economic and cultural center of the Ben Tre
province. Seven other districts include Chau Thanh, Binh Dai, Giong Trom, Cho Lach, Thanh Phu,
Mo Cay Bac, Mo Cay Nam and Ba Tri.
The Mekong river after entering Vietnam’s territory, separates into two main branches including Tien
and Hau river. Geographically, Ben Tre province is the most downstream area of Tien river. Tien
river is then divided into four main tributaries including Tien, Ba Lai, Ham Luong and Co Chien
river. These tributaries help form the shape of Ben Tre province which is similar to an alluvial fan.
With the existence of these main rivers running through the whole province, geomorphologically, Ben
Tre is separated into three peninsulas including An Hoa, Bao and Minh.
The geographic coordinates of the whole Ben Tre province are 9048’ to 11020’ North and 105057’ to
106048’ East.
Figure I.1: Map of Ben Tre province
(www.bentretourist.vn)
1
About topography, Ben Tre province has characteristics of flat topography of the river delta formed
by deposition of sediments of the Mekong river. The whole province can be topographically divided
into three zones (MONRE, 2010) including:
•
Zone of low elevation: elevation is lower than 1m. This area includes newly formed
peninsulas, tidal areas and mangrove areas. It is usually flooded by tide;
•
Zone of average elevation: elevation ranges from 1 to 2m. This is the dominant topography in
Ben Tre province which occupies up to 90% area of the whole province; and
•
Zone of high elevation: this zone includes coastal sand dunes and high areas along main rivers
in the North West side of the province.
About hydrology, Ben Tre province’s hydrological system is characterized by dense channel network
with overall length of up to 6000 km. Besides 4 main rivers including Tien, Co Chien, Ham Luong
and Ba Lai, there are about 60 other small rivers and channels (MONRE, 2010). The flow of this
dense channel network is driven mainly by flow from Tien river and tidal regime of the South China
sea (ibid). In addition, the tidal regime in coastal area of the province follows semi-diurnal pattern
with two high tides and two low tides each day. Water level in high tide is normally 2.5-3m higher
than in ebb tide in days with high tides, and the difference is approximately 1m in days with low tides
(MONRE, 2011).
About climate, Ben Tre can be distinctively separated into 2 seasons. The rainy season lasts from May
to November, the dry season, on the other hand, lasts from December to April next year. The yearly
average precipitation in the province is from 1,200 to 1,600 mm (MONRE, 2011). Precipitation in
rainy season takes up to 90-95% of the yearly rainfall in the province. On the contrary, in dry season,
especially in January, February and March, there are only 1 or 2 rainy days and the rainfall in dry
season only takes 1.5 to 6% of the total yearly rainfall (ibid).
1.1.2
Socio-economic characteristics of Ben Tre province
Ben Tre province has many geographic advantages for socio-economic development. Being located at
the most downstream area of the Mekong Delta with dense river network and only 86km away from
Ho Chi Minh city, the socio-economic center of the South, Ben Tre can easily integrate its economy
with other regions in the Mekong Delta and the South Eastern part of Vietnam (Ben Tre DONRE,
2008).
According to Ben Tre SO (2015); in 2010, agriculture, forestry and aquaculture continues to be the
main economic sector in the province with the largest contribution to the economy’s GDP. In specific,
these sectors account for nearly 45% of the province’s gross output in 2010 (ibid). In recent years;
however, industrial and service sector have been developing sharply as shown in Figure I.2 to replace
agriculture, forestry and fishing in the contribution to the province’s gross output.
2
90,000
80,000
Billions VND
70,000
60,000
50,000
40,000
30,000
20,000
10,000
0
2010
2011
2012
Agriculture, Forestry and fishing
2013
2014
Industry and construction
Prel. 2015
Service
Figure I.2: Gross output (billion VND) at current price by economic sectors from 2010 to 2015
(Ben Tre SO, 2015)
Table I.1 shows the contribution of each type of crops to agricultural sector. Cereal crops (mostly
rice) are the most important annual crops contributing 1,501billions VND to gross product in 2015
(Ben Tre SO, 2015).
Table I.1: Gross output (billions VND) of cultivation at current prices (2015) by crop groups
(Ben Tre SO, 2015)
Annual crops
Year
Total
Total
Cereal
Perennial crops
Vegetable,
Annual
bean and
industrial
flowers
crop
Total
Fruit
Perennial
crop
industrial
crop
2010
6,343
2,545
1,551
537
367
3,798
2,310
1,411
2011
9,696
3,372
1,993
819
412
6,324
3,159
3,012
2012
7,494
3,359
1,747
1,070
319
4,135
2,998
1,124
2013
7,375
2,815
1,343
1,029
240
4,560
2,983
1,562
2014
9,261
3,668
1,677
1,490
230
5,593
2,849
2,736
Prel.
9.198
3,548
1,501
1,618
138
5,650
3,036
2,606
2015
3
Aquaculture is another main economic activity in Ben Tre province. Aquaculture activities involving
farming rapidly expanded in the period 2001-2005 due to brackish-water shrimp farming program
(Ben Tre DARD, 2010). As being shown in Table I.5; in 2010, the gross output of aquaculture is
6,717 billions VND and the number kept increasing to 7,383 billion VND in 2015 (Ben Tre SO,
2015).
Table I.2: Gross output (billion VND) of aquaculture at current price (year 2015)
(Ben Tre SO, 2015)
Year
Gross
output
2010
2011
2012
2013
2014
Prel. 2015
6,717
9,147
8,629
9,818
11,547
9,491
1.2
Problem statement
1.2.1
Salinity intrusion in Ben Tre province
Similar to other downstream provinces in the Mekong Delta of Vietnam, salinity level in Ben Tre
province is a function of many variables including the flow from the upstream part of the Mekong
Delta, the effects of tidal regime of the East Sea, water storage in Tonle Sap (Cambodia) and in river
or canal system and the hydrological structures in the area (Nhan et al., 2007). With its low elevation
compared to average sea level and being under the strong impacts of tidal regime of the East sea,
salinity intrusion is very severe, especially in dry season (MONRE, 2011).
The salinity level in Ben Tre province is always tightly connected with tidal regime of the East Sea.
Salinity normally fluctuates accordingly with the tidal pattern of the East Sea. Salinity is also greatly
influenced by flow from the upstream of the Mekong Delta. In flooded season, salinity boundary is
pushed seawards. However, in coastal areas, salinity level is never lower than 2ppt. The highest
salinity level usually occurs in April, the last month of dry season when there is least freshwater from
Tien river (MONRE, 2011; My et al., 2006). The occurrence of ‘Chuong’ wind which pushes tidal
flows further inlands in the dry season exacerbates the salinity intrusion in the province (MONRE,
2011).
Salinity level also varies in different rivers in Ben Tre. Salinity intrusion in Ba Lai is the most severe,
(i.e salinity goes furthest inland). It is because the upstream flow is too little to push back salinity.
Ham Luong is the river with the least impacts of salinity intrusion in Ben Tre mostly because of its
flow which is the highest among four main rivers in the province. Salinity is also higher in channels
compared to in river because there is no upstream flow entering channels to dilute the salinity in water
(MONRE, 2011).
4
B Tre provvince will bee more severre under the impact of climate
c
changge
Salinity intrusion in Ben
E, 2011). Morre specific, itt was estimatted that in 20050, when thee sea level rises 30 cm, thhe
(MONRE
salinity bo
oundary of 4 ppt will mov
ve 40km inlaand and the current
c
salinitty boundary of
o 4 ppt would
shift to 8-10
8
ppt (ibid
d). The salinity intrusion can even geet over the capacity of cu
urrent salinityycontrollinng structures. For instances, it was foreecasted that salinity
s
can m
move deeply inland througgh
Dai estuarry and increaase the salinity
y level in Chhau Thanh disstrict despite tthe operation of sludge gaate
Ba Lai in Ba Lai river (ibid).
R farming – a precariou
Rice
us livelihood
d
1.2.2
a) Low prrofitability of
o rice farmin
ng
Tran et al.
a (2013) obbserved that food
f
securityy issue in Viietnam is noo longer the main concerrn.
Accordingg to their reseearch; since 2000,
2
rice connsumption haas decreased in Vietnam. The
T downwarrd
trend of riice consumpttion as shownn in Figure I.33 is considereed as a result of higher inccome, enablinng
people to diversify theeir diet towarrds other sourrces of nutrieents includingg meat, fruit, egg and millk.
This trend
d is also preddicted to offsset the shrinkking of rice production
p
duue to the impaacts of climaate
change annd land, wateer scarcity, poointing to thee fact that Vietnam
V
can still
s
meet the target of foood
security inn the future (ibid). Food security is thherefore, not a serious prooblem and foocus should be
b
shifted to profits generrated from rice farming (ibid).
14
4
12
2
12
12
11.4
11
kg
10
0
9.7
9
9.6
1.8
1
1.8
201
10
20
012
8
6
4
2
1.3
1.4
1.5
4
1.4
2002
2004
2006
6
2008
8
0
Ricce
Meat
meat of an ind
dividual in Viietnam from 2002
2
to 2012
Figure I.3: Monthly consumptionn of rice and m
(Vietnam
m GSO, 2012))
Neverthelless, unlike the
t optimisticc picture it bbrings to of food securitty, the contriibution of ricce
cultivation
n to income of
o farmers rem
mains at the loow level in th
he Mekong D
Delta (Tran et al., 2013). Thhe
share of income
i
is esppecially low in groups of farmers with
h small-size and
a fragmented farms. Thhis
share of income is higgher in case of
o farmers with large farm
m in that rice farming in grroups of largefarm farm
mers, rice farm
ming still acccounts approxximately 64%
% of total incoome in 2006.. However, thhe
number drropped downn to 50% in 20
010 (ibid). Foor groups of small-farm farrmers, up to 80%
8
of farmeers
5
with farms smaller than 0.5 hectares have only 20% of their incomes coming from rice farming.
While the low income in small-size farmer can be explained by small area for rice paddies, the
decreasing income in groups of large farms is due to the fact that rice farming is a low profit
agriculture activity (ibid).
In the Mekong Delta, even though there are few researches that directly explore the linkage between
rice farming and poverty, there are many expert opinions recently about this issue. According to Vo
Tong Xuan, leading expert in agriculture, using rough estimations, with the price of rice today of
about 4,300 VND/kg, individual farmers with small-size farms only benefit about 300-400 VND/kg
because they have to pay a higher cost of production compared to those in collectives or with largesize farms (Phan Chu, 2016).
b) Rice farming susceptible to salinity intrusion
Rice farming, especially in the coastal area, is always under the risk of negative impacts by salinity
intrusion. In the coastal Mekong Delta, areas with three seasons of rice are vulnerable the most
because there will be one season in the dry period, when the areas are heavily affected by high salinity
level.
Figure I.4: Seasonal calendar in the Mekong Delta and the periods of saline- intrusion- related events
(Nhan, et al., 2011)
The Winter-Spring season of rice in the Mekong Delta is normally started from the end of November
to Febuary in the irrigated area, e.g. area without threat of salinity intrusion thanks to irrigational
system. In the coastal zone, shift of crop calendar had to be conducted to avoid rice cultivation in dry
season normally lasting from the end of November till April. However, climate change along with
higher sea level can induce salinity stress on the agriculture activity (Wassmann et al., 2009). Climate
change also cause abnormality in rainfall pattern, which in turn can cause drought, making it easier
for saline water to intrude deeper inland (Nhan et al., 2011). It was estimated by Nhan. et al. (2012)
that during the peak of dry season, salinity level of 5ppt can go up to 40-50km inland through main
rivers.
6
In their study on the impact of salinity level on crop yields using statistical data on rice crop
production in Ben Tre, Tra Vinh, Soc Trang and Bac Lieu provinces of Mekong Delta from 2003 to
2005, Kotera et al. (2008) found there was an inverse correlation between rice yield in Winter-Spring
season (dry season) and salinity level in that rice production in Winter-Spring season decreased when
salinity increased. One of the reason for this drop in crop yield was because of abnormally early rise
of salinity level, many rice fields were dead before farmers could harvest.
The latest drought event in 2016 clearly showed the immense impacts of salinity intrusion on rice
production in the Mekong Delta. In this historic drought-salinity intrusion, by mid-April, it was
estimated that in the Mekong Delta, there were up to 224,552 ha of rice field affected by salinity
intrusion (CGIAR, 2016). In Ben Tre alone, 8,668 out of 11,200 ha of cultivated rice field was
affected by salinity. This accounted up to 77.4% of total area of rice fields. Giong Trom district with
2,600 ha of sow rice field also suffered heavy loss in this incident with up to 1,000 ha (approximately
38%) lost completely (Giang Son, 2016). The damage reflected by rice yield was estimated from 50%
to complete loss (CIGAR,2016).
1.3
Research objectives
The current salinity condition in Ben Tre province and its expected trend in the future necessitate an
urgent solution. There are many options available for the area. Among of those, changing of land-use
patterns from freshwater-dependent land-use types to other types that favor saline environment is a
promising adaptation solution. The transformation from rice to shrimp farming; in specific, is the
most desired possibility in the area. This transformation, however, is considered debatable because it
meets some opposition from the government for jeopardizing the possibility of national food security,
which was proposed to maintain the productivity of rice cultivation. The transformation also implies
many environmental as well as socio-economic impacts, demanding a thorough understanding before
being brought into practice. Therefore, the research aims to assess the possible impacts of this
transformation from rice to shrimp and find the optimal solution.
1.4
Conceptual framework
Figure I.5: Conceptual framework
Figure I.5 visualizes the conceptual framework for the research. Under the pressure of salinity
intrusion, the transformation from rice to shrimp farming is a promising adaptive approach. This
7
transformation; however, implies within it the trade-off between three aspects including food security,
economic development and environmental sustainability. In specific, there would be great loss to food
security due to the transformation of rice paddies to shrimp farms as an exchange for better economic
condition of farmers. This transformation; however, also means huge environmental impacts because
of the environment cost of shrimp farming.
1.5
Research questions
The research will target four main research questions:
1. How is the level of salinity intrusion in Ben Tre province ?
a. What is the spatial extent of salinity intrusion in Ben Tre province ?
b. What is the temporal extent of salinity intrusion in Ben Tre province ?
2. What is the area suitable for the rice-to-shrimp transformation ?
3. What are the possible impacts of changing from rice to shrimp ?
a. What are the impacts of the transformation from rice to shrimp on food security
situation in Ben Tre province ?
b. What are the economic impacts of rice-shrimp transformation ?
c. What are the environmental cost of this transformation ?
4. What solution is optimal for the area ?
1.6
Outline of the report
The report includes seven chapters. The first chapter is the introduction part describing the studied
area, the problem statement explaining explicitly the problems the area is facing, the research
objectives, the conceptual framework for this study, and lastly the research questions.
The second chapter is about the methodology used to address research questions in the first chapter.
The chapter describes in detail the techniques as well as tools and input data utilized in each method.
Four research methods including Multi-criteria analysis, literature study, data collection and field
survey and geographic information system approach are discussed explicitly four separate sections.
The third chapter provides information the history of rice farming and shrimp farming in the studied
region. The purpose of this chapter is to briefly describe the success of rice farming in the Mekong
region, turning Vietnam not only into a highly food-secured country but also one of the top riceexporters of the world. This success; however, implicitly put constraints on any innovative attempt to
help agricultural sector in Vietnam cope with growing pressures from the environment such as salinity
intrusion. The chapter also shortly introduces about arrival of shrimp farming in the Mekong Delta
and its equally important role to rice farming in Ben Tre province as reflected in the current land-use
map 2010 and the land-use map planning to 2020. Lastly, the chapter provides information on landuse allocation planning to 2020 in the area, which later serves as input to the analysis of the
possibilities and impacts of the transformation from rice to shrimp to cope with salinity intrusion.
The fourth chapter of the report provides insights into shrimp farming in the Mekong Delta region.
The chapter specifically discuss two distinctive types of shrimp farming including the intensive
8
shrimp farming and the rice-shrimp rotation farming with the aim to introduce about two brackishwater-dependent livelihoods which can be good substitutes to rice farming in the condition of salinity
intrusion.
The fifth chapter presents the results of the research. This chapter includes four sections presenting
the answers to the four research questions. The first section of the chapter will discuss the extent of
salinity intrusion in Ben Tre province using available outputs from modelling. The second section will
present the finding of areas where there should be transformation from rice to shrimp. The third
section will present the possible impacts of this transformation and lastly, the fourth section will
discuss the optimal option of land-use for the area.
The sixth chapter discusses the results of the research in the order of research questions. Critical
assessment on the result will be conducted. The last chapter is the conclusion which summarizes the
objectives that the research addresses.
9
II
METHODOLOGY
2.2
Multi-criteria analysis (MCA)
MCA is applied to address research question fourth. The application of MCA is to assess alternatives
of land-use under different perspectives. The advantage of MCA over other assessment tools is that it
allows the assimilation of different criteria whether they are qualitative or quantitative. Another
advantage of MCA is that it allows the assignment of importance level or hierarchy to criteria
(Mendoza et al., 2006).
The study applies the set of criteria in previous studies on assessing scenarios of land-use allocation.
In their study on optimizing land-use allocation for the Mekong delta area, Trung et al. (2006)
suggested that economic development, social security and environmental sustainability should be used
in assessing scenarios of land-use allocation. In this study, food security is used in place of social
security as a criteria because the food security is still a main focus in any policies targeting land-use
allocation in Vietnam. Table II.1 shows list of criteria and their indicators used in this study.
Table II.1: Goals, criteria and indicators for criteria applied in the research
Goal
Criteria
Indicator
Food security
Production of rice
Rice yield (tons/year)
Profitability when crop wins
Benefit to cost ratio in case of crop
succeeds
Economic development
Profitability when crop fails
Benefit to cost ratio in case of crop
fails
Job opportunity
Labor days (labor days/year)
Salinization cost (VND/year)
Sedimentation by frequency of pond
dredging (times/year)
Sedimentation
Environmental sustainability
Environmental impact
by
amount
of
industrial feed (kg/year)
Fertilizer
application
(kg/ha/
season)
Pesticide application (kg /ha/ year)
Area irreversibly adjusted (hectares)
Freshwater demand (m3/ha/year)
The food security criteria is measured by the production of rice. It is an important criteria for any land
use allocation decision in the Mekong Delta because it has a long history of being the top concern by
the government.
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Socio-economic criteria include the benefit to cost ratio of rice and shrimp farming and their job
opportunities. Besides the possible profit that can be generated from options of land-use, the risk
adhered to them will also be considered. In the research, risk will be evaluated using the the ratio of
benefit and cost in case of crop loss.
Environmental criteria reflect the level of impact that rice and shrimp farming activities can induce on
the environment. The criteria will be evaluated by the volume of agro-chemical applied in each type
of farming. Three other indicators of environmental impacts are also considered including salinization
cost, terrain adjustment and freshwater usage.
Table II.2: List of scenarios of development and its weight to goals
Criteria
Goal
Food security
Economic
Environmental
development
sustainability
Balance scenario
0.33
0.33
0.33
Food security first
0.7
0.15
0.15
Less food security
0.5
0.25
0.25
Economic development first
0.15
0.7
0.15
Less economic development
0.25
0.5
0.25
Environmental sustainability first
0.15
0.15
0.7
Less environmental sustainability
0.25
0.25
0.5
Economy – Environment balance
0.15
0.425
0.425
0
0.5
0.5
No food security
Table II.2 includes weights assigned to criteria in this study. The weights are assigned differently in
each goal or scenario of development. The values of weights are taken from the study by Trung et al.
(2006). In their study on analyzing land-use planning approaches in the coastal Mekong Delta, Trung
et al. (2006) applied FAO-MCE method to generate land-use scenarios. The step involved decision
makers into the process of identifying indicators and their level of importance. The result from this
step is a list of scenarios or goals for land-use planning; in each scenario, weights for criteria were
defined as level of priority.
In this study, nine scenarios or goals of development will be analyzed including one scenario of
balance in which all goals have the same weight, two scenarios of food security in which weights for
the goal food security are 0.7 and 0.5, two scenarios of economic development in which weights for
the goal economic development are 0.7 and 0.5, two scenarios of environmental sustainability in
which weights for the goal environmental sustainability are 0.7 and 0.5 and lastly two scenarios with
equal priority levels on economic development and environmental sustainability and less or no
concern about food security. The values of weights are picked up on referencing to the work by Trung
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et al. (2006). More than one weight for each goal are chosen to analyze the sensitivity of the result to
different weights.
2.3
Literature study
Literature study is applied to address the research question one and three. About the first research
question on level of salinity intrusion, the research refers to the study by Toan (2014) on possible
impacts of upstream development on hydrological regime and salinity intrusion in the Mekong Delta
using modelling approach. Two indicators of salinity intrusion including spatial distribution of salinity
level and duration of salinity level 4ppt are extracted from the study to analyze the spatial and
temporal extent of salinity intrusion in the region.
The study also refers to the work by Trung et al. (2006) on developing land-use approaches in the
Mekong Delta. Information taken from the research includes set of criteria, their indicators and their
weights to compare different scenarios of land-use allocation.
Lastly, literature study is to find out relevant information on the practice of rice and shrimp farming in
the area. Google scholar searching engine is utilized to find scientific papers with necessary
information. The search is applied with keywords ‘shrimp farming’, ‘rice farming’ and ‘Mekong
Delta’. Available reports on environmental and social impact assessment of each type of rice, shrimp
and rice-shrimp farming are the main target of this search. These information is used to fill in the
values of criteria in MCA which data gathered from field survey cannot cover. In specific, criteria that
will be scored using data from available reports and articles are production of rice, job opportunity,
salinization impact, pesticide and fertilizer application and freshwater demand. Sources for these
Criteria
Indicator
Source
Food security
Rice yield
Ben Tre DARD, 2010
Economic development
Labor days
Vu et al., 2014
Environmental sustainability
Salinization cost
Be et al., 1999
Pesticide application
Berg, 2002
Fertilizer application
Huan et al., 2005
Freshwater demand
To, 2015
criteria are mentioned in Table II.
Table II.3: Source of data for scoring in MCA
2.4
Data collection and field survey
Data collection and field survey are applied to address research questions one, two and three. In this
study, a wide range of data will be collected including data from doing interviews in field survey and
data from available sources. Data from doing interviews in field survey or primary data is collected
using questionnaire instrument. The field survey will focus on shrimp farming activity in the research
area. Two specific types of shrimp farming are to be considered including the mono intensive shrimp
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farming and the rice-shrimp rotation models. Stratified sampling technique using local knowledge of
studied area is used to identify sampling area. Figure II.1 depicts the sampling area. In this study, two
wards My An and An Thanh of Thanh Phu province are chosen to do the field survey because in these
two wards, shrimp farming is the dominant activities and there is a mix of intensive shrimp farming
and rice-shrimp rotation model. These two wards are also areas where there used to be a
transformation from rice farming to shrimp farming. Random sampling technique is then applied in
the field trip to find participants for interviews. Total sampling size is thirty two in which there are
sixteen interviews with intensive shrimp farmers and sixteen interviews with farmers doing riceshrimp rotation models. Because the survey targets two distinctive groups of farmers, two
questionnaires with different formats are needed. Interviews are in form of semi-structure interview
with questionnaires including open-ended questions. Questions mainly focused on capital investment,
farming practice and lastly productivity of two types of shrimp farming in the condition of crop win
and crop loss. The two version of questionnaires are included in Appendices two and three.
Information taken from the field survey is listed in Table II.4.
Figure II.1: Map of survey area
Secondary data collected are maps of current land-use and land-use planning in the province to 2020
and other layers of maps including administrative and hydrological maps.
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