T hank to this dcvelopm cnt, tho brackish pond culturc has im proved rem ark ab ly thc quality of lifc for m any íarm crs in the province, contributing positivcly to the poverty alleviat
Trang 1VNƯ Jo u rn al o f Science, E arth S cicnccs 24 (2008) 66-78
ưsing multi-criteria analysis as a tool to select the íeasible measures for sustainable development of brackish vvater
shrim p culture in Quang Tri Province
N guyen Tien Giang1-*, Tran Anh Phuong1, Tran Ngoe Anh',
Nguyen Thanh Son1, Nguyen Truong Khoa2
1 College o f Science, VNU
2 Department o/N atural Resources and Enviroivncnt of Quang Tri Provincc
R eceived 7 July 2008; rcccivcd in rcviscd fo rm 23 A u g u st 2008
A b stra ct In rc ccn t yoars, b ra ck ish vvator sh rim p c u ltu rc in Q u a n g Tri P ro v in c e h a s d e v e ỉo p c d
ra p id ly T h a n k s to th is d e v o lo p m e n t, lives of m a n y local ía rm e rs h a v e bccn im p ro v e d , co n trib u tin g
co n sid e ra b ly to th c p o v c rty allcv iatio n goal Iỉo w o v o r, to g c th c r w ith th is p o sitiv o im pact, policy-
m ak ers a n d sh rim p fa rm c rs a rc íacin g sev e ral issucs su ch as sp rc a d of s h r im p 's discascs, w atcr
p o llu tio n a n d sa lin ity in tru sio n P or th c p u rp o s e of su stain ab lc d e v e lo p m c n t, it is ncccssnry to
scarch for a n d im p le m e n t th o sc m e a su re s w h ich can so ỉv c cffcctivcly th c sc c m c rg in g problem s.
T his p n p e r p ro sc n ts th c rc su lts on th o ap p lic a tio n of a m u lti-c ritc ria a n a ly sis m c th o d to sclccting
th c m o st íc a sib le m e a s u re s to th c sc p ro b lcm s 'Ih c M C A rcsults su g g e st th c four m o st ícasiblc
m c a su rc s a n d p in p o in t th n t th e ccìm bincd o p tio n : se d in ic n ta tio n rc se rv o ir & re se rv o ir w ith cu ltu rc
plus im p ro v c d íc c d in g a n d w a tc r m a n a g o m c n t a s th c "bcst" o p tio n
Keỵivords: S h rim p c u ltu rc ; M u lti-critcria an alysis; I;ca sib lc m c asu res; S u sta in ab lc d cv c lo p m c n t;
Q u a n g Tri P ro v in cc.
1 In tro d u c tio n
Q u an g Tri Provincc is located in the
C entral V ietnam The p ro v in ce is b o u n d ed on
the north by Q u a n g Binh Province, on the
south by T h u a T hien H u c Provincc, on the
vvest by Laos R epublic a n d on th e east by thc
sca (Fig.l) T h e Province includcs 10
adm inistrative units: tvvo to w n s and 8
districts, in vvhich D ong H a is the provincial
Capital
* Corresponding author Tcl.: 84-4-2173940.
E-mail: giangntộ vnu.vn
As rogards to p o g rap h y , Q u a n g Tri has all types of top o g rap h y : m o u n tain s, hills, plains
a n d Coastal s a n d d u n c vvith tvvo m ain riv c r
systcm s: Thach H an an d Ben Hai Lying in the tropical m onsoon region, the average tcm p eratu re of Q u a n g Tri is ranging from
tem p eratu rc usually h a p p en s on July an d Jan u ary 7 respcctively
Q u a n g Tri has a total annual rainíall of about 2000-2700 m m , b u t the rainíall is rath er unequally d istrib u te d over từ n e and spacc The rainy scason starts in Septem ber, cnds in
6 6
Trang 2N guyên Tieu Giang ct nì / VNU louniaỉ o f Science, Earth Sciences 24 (2008) 66-7H 6 7
January and accounts íor 75% to 85% of the
total yearly rainíall, vvhcrcas tho dry scason
lasts up to 6 m o n th s, from Fobruary to July
and occupies only 15-25% of the total rainíall
F;ig 1 Qunng '1'ri Provincc
Q uang Tri h a s 75 km of Coastal lino and
tw o river m o u th s, nam ely C ua T ung and Cua
Viet In recent ycars, therc has bcen a rapid
developm ent of brackish p o n d aroa in the
provincc As shovvn in Fig 2, thc total area of
brackish w ater s h rim p culturc has increased
approxim ately 4 tim es, from 251 ha in 2000 to
902.5 ha in 2007 A ccording to the provincial
aquaculture d e v e lo p m e n t plan [6], the total
arca in 2010 vvould bc 1,889 ha, vvhich
doubles the present's- value T hank to this
dcvelopm cnt, tho brackish pond culturc has
im proved rem ark ab ly thc quality of lifc for
m any íarm crs in the province, contributing
positivcly to the poverty alleviation Hovvever,
during tho d e v elo p m e n t process, the local
íarm crs and a u th o rities havo bcen íacing
som e problcm s s u c h as vvater pollution, saiinity
intrusion an d th c sp re a d of sh rim p 's diseases
This lead s to tho d o m a n d for seeking and
ừ n p lcm o n tin g m easuros to solve the conílicts betvveen econom ic goal an d its negative
im pacts, especially in tho íu tu re, vvhen the province has tho plan to develop the aquaculture
to be th e key sector of local econom ics [6Ị
2000
2000 2001 2002 2003 2004 2005 2006 2007 2010
Y««r
Fig 2 The devclopmcnt of brackish pond area in
Quang Tri Province
In order to have íeasiblc scts of measuros
for thc abo v e-statcd p ro b lem , a M ulti-C riteria
A nalysis (MCA) m e th o d w as uscd and its results aro p rc se n te d in tho next scctions
T his p a p e r is d iv id e d into 5 scctions Section 1 is involvcd vvith the problem statcm en t Scction 2 is d ev o ted to the overvievv of thc MCA m eth o d s Section 3
d escribcs stcp by step tho ap p lication of the
M CA m e th o d u sin g pair-vvise com parison and its rcsu lts to tho p ro b le m of brackish
w ate r s h rừ n p cu ltu re in Q u an g Tri Provữice
S ubsequentỉy, scctions 4 an d 5 p resen t som e discussions, conclusions on the results and the rcscarch outlook
2 M e th o d o lo g y
2.7 Fraincworkfor muỉti-critcria analysis
A n y dccision p ro b lem can be stru c tu re d into th re e m ajor phases: intoliigence w hich exarrdnes the existence of a p ro b lem or the
o p p o rtu n ity for change; design vvhich
Trang 368 Nguyeiĩ Tiett Giang ct nỉ / VNU Ịủuntal o f Sciaice, Earth Scicìĩccs 24 (2008) 66-78
determ ines the alternativos; and choice w hich
decides the best alternative 110] MCA is an
eííective tool u sed in a decision process The
m ajor elcm ents involved in decision m aking
proccss using a MCA m eth o d can bc view ed
systcm atically in a ừam evvork (Fig 3)
P roblcm D cíỉn itio n
E v alu atio n C ritcria 4
D ecision M atrix <
C onst raints
A ltcrnativcs
I
Pairvvise c o m p a riso n Dccision M akci^s
_ *
C ritcrion W cights
ĩ
Select íeasiblc
m e a su re s Fig 3 F ram ew o rk for m u lti-c riteria analysis.
2.2 Problem dcfinition
A decision p roblem is the diííerence
betvveen thc dosired an d existing State of the
rcal vvorld It is a gap ro co g n i/ed by the
stakeholdcrs (dccision makors, sdontísts and/or
íarmers) A ny dccision m aking process
begins w ith th e recognition an d tho deíinition
of the problcm This stagc is in thc intolligcncc
phaso of docision m aking and it involves in
scarching thc decision env iro n m en t for
conditions, obtaining, Processing and examining
the raw data to identiíy the problem s
2.3 Constraints
After the problem has been deíined,
constraints (or b o u n d ary conditions) of this
problem h ave to bc dctcrm in ed for the
íollovving tvvo rcasons:
- Tho stu d icd p ro b lem s are usually com plicate, they are rclating to m an y aspects and scctors T hereíore, it is im possiblo to take into account all thcso effects in practice
- O n the o th cr h a n d , for solving a problcm , m any m easurcs w ould bo suggestod The responsibility of the scientists is to screen
a m o n g these a ltc rn ativ es th e íeasib lc m c a s u re s
bascd on applicability and suitability for tho
local conditions.
2.4 Evaluatioiì critcria
Aítor tho p roblem and its constraints h av c beon detorm ined, the set of ev aluation critcria should be dcsig n ated Ị2Ị This stagc involves spcciíying a co m p reh en siv c sct of obịectives that rcAects all concem s relevant to the decision problem a n d m oasurcs for achieving
íhosc objoctivcs.
2.5 Critcrion wcights
C riteria vveighting is ono of the m ost
im p o rtan t step s in th e decision m ak in g process A w oight can be do íin ed as a value assigned to an cvaluation critcrion vvhich indicates iís im p o rtan ce rolative to othor criteria u n d c r considcration A ssigning
w cights of im portanco to evalualion critcria accounts for: (i) tho changos in tho range of variation for each cvaluation critorion and (ii) the diííeront d eg rccs of im portanco bcing attachcd to those ranges of variation [3Ị Bascd on this general dircction, a n u m b er of
m cth o d s have bocn d ev elo p cd and applied Each of them has its ovvn ad v an tag cs an d disadvantages T ablc 1 su m m a ri/e s som c thcse m cthods an d thcir íoaturcs
In com parison w ith thc ranking an d
ra tin g m c th o d s , pairvviso co m p ariso n a n d
tradc-off analysis m eth o d s both h av c m o rc precise and objective u n d c rly in g thcory
Trang 4N guyên T im Giang ct al / VNU ỉounml oỊScim ce, Earth Sciences 24 (2008) 66-78
T able 1 M eth o d s for d e te rm in in g criterio n vveights [8, 9]
69
M cth o d s/H ca tu res R an k in g R ating P a irw ise c o m p ariso n T ra d e -o íí analysis
U n d c rly in g th c o ry N o n c N onc S ta tistica l/ heuristic A x io m atic/ d cd u c tiv e
P recỉsion A p p ro x im a tio n s N o t prccisc Q u itc prccisc Q u ite procise
S(.)ftwarc a v a ila b ility S p rcn d sh e cts S p rcad sh eets E x p ert C hoicc Logical Dccision
Hovvever, vvhon it comos to the ease of
usc, pairvvisc c o m p ariso n is m u ch bettcr than
the trade-off analysis For thoso reasons,
pairvvise co m p ariso n m cth o d w as applicd in
this study T h e íollovving p arag rap h s
introduce this m othod
Tho mothod involvcs pairw ise comparisons
to create a ratio m atrix It takos pairw isc
com parisons as in p u t a n d p ro d u ccd rclativo
vveights as o u tp u t Tho pairvvise com parison
m ethod involves tw o m ain stcps:
- D evclopm ent of a p airw isc com parison
m atrix: tho m eth o d uses a scale w ith valucs
range from 1 to 9 The possible valuos arc
presentod in T able 2
T able 2 Scale fo r p a irw ise c o m p ariso n [12]
Intcnsity of D e íin itio n
im portancc
1 lỉq u al im p o rta n c c
2 Lỉqual to m o d e ra to ly im p o rtan cc
3 M oderatG im p o rta n c e
4 M o d e ra te to stro n g im p o rtan ce
5 S tro n g im p o rta n c c
6 S tro n g to v ery s tro n g im p o rta n c e
7 V ery s tro n g im p o rta n c c
8 V cry to c xtrom cly stro n g im portancc
9 K xtrem e im p o rta n c e
- C o m p u ta tio n of the w eights: the
com putation of th e w cig h ts involves three
steps The first One is su m m atio n of the
valucs in cach m atrix colum n Ncxt, cach
elem ent in the m atrix should be dividcd by
its colum n total (thc rcsulting m atrix is reícrred to as tho norm alized pairw isc com parison m atrix) In tho third step, com putation of the averagc of the olcm ents in each rovv of tho norm alized m atrix should bo
m ade vvhich includos d ividing tho sum of
n o rm a li/e d scorcs for each rovv by the
n u m b cr of critcria T hcse avoragos provide an estim ate of thc relativc w cights of thc criteria being com parod
T he ad v an tag e of this m ethod is that only
tw o critoria have to be considered at a tim e, it can b e im plem ented in a spreadsheet cnv iro n m en t [3] O ne of the disadvantagcs is that th e relative Lmportance of evaluation criteria is detcrm in ed vvithout considoring the scales o n vvhich the criteria are m easured
A nothcr d isad v a n ta g e is th e large am ount of pairvvise com parisons if m any criteria cxist
2.6 Dctermination o f alternativcs
Based on the constraints and objectives of the p roblem and the relating sectors, the
m easures or com binations of m easures to solve th e p ro b lem is to be suggested Thcsc
m casures can be the oncs that have bcen being ap p lied clsew h ere having ícatures or new technologies that arc íirstly considered Thon, scores for thesc m casures vvith rcspect
to diffcrcnt critcria will be assessod aíter expert consultation
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2.7 Selcction o f thc/casiblc measurcs
The íinal sta g e in tho decision m aking
process is to e stim ate th c scores for each of
m easures for th e objectivcs and conditions of
the study Tvvo íactors used to dcterm inc
thcse scores are scores for thc m casurcs w ith
rcspcct to d ifferen t critoria and vvoights of thc
criteria The m oasures w ith highest scores
will be selccted to solve the problom
3 Application o í MCA to sclecting ícasible
measures for sustainable development of
brackish water shrimp culture in Quang Tri
Province
3.7 Currcnt and/iiturc problcm
D uring the last couple of yoars, tho spread
of sh rim p discasos occurrcd ừ equently in the
stu d y arca T h esc discascs arc spread by
brackish vvater, w hich is takcn in and out
vvithout propcr pretreatm cnt and post trcatment
by the sh rim p íarm ers T he river vvater has a
tendency to bc pollutcd duo to the vvastewater
from thc s h rim p íarm s and from other scctors
such as in d u stry and agriculturc
A nother p ro b lc m for the sh rim p íarm ers
is to kecp a d ccen t salinity rato for grovving
black tigor sh rim p s (Pcnacus monodon) This
salinity rate ch an g cs considcrably ovcr tim c
because of th e tidal rcgim c Only at certain
periods w atcr vvith thc ap p ro p riate salinity
rate can bo tak en in by the íarm crs
3.2 Boundary conditions
Thcre are several boư ndary conditions that
need to be m entioncd relatod to thc problem s
and possiblc solutions of the w astew ater
problem s near sh rim p ponds These are:
(i) Spatial boundarics: the location of the
sh rim p íarm s has to stay ncarby thc rivcr cstuarics; T h e availablc space for a prod uction p o n d rem ains 0.5-1 ha
(ii) Social boundarics: the S tandard ()f
living for the íarm ers should not be lovvered (iii) Ecological boundaries: the w ater quality in th e p o n d s should be im p ro v cd to the nccdcd sta n d a rd s for black tigcr sh rim p s;
W atcr quality in the river and in the estu arics should bo im proved; No m easures m ay havo negative effects on thc en v ừ o n m en t
M casures suggested should m eet thcse boundarics, o th erw ise thoy vvill be rcm o v cd
3.3 Obịcctivcs
S hrim p íarm crs vvant to m ak e thcir living; thcy neod to m ain tain thoir íam ilies Also becausc of thc rclative largc initial investm ent costs thcy are in dcbt and havo to rcpay tho b an k s in short term s
T he local g o v crn m en t vvants a g ro w in g econom y in Q u a n g Tri, and shrim p íarm ing is
a grcat o p p o rtu n ity for the people living in the lovver p arts of tho provincc b ccausc of its
u n iq u e hrackish en vironm cnt
A ítcr all req u irem en ts of all íactors aro takcn into account, thc study com es to conclude th at the m ajor objcctivo for MCA is
to achievc a m ore stablc econom ic
cn v iro n m en t In trying to achievc this goal, sub-goals can bo reached like:
+ Bcttor w atcr quality in thc rivcrs an d estuaries;
+ Bcttcr vvater quality m thc shrừnp ponds;
+ Bcttcr w cll being of íarm ers and thcir íam ilies / the com m unities;
+ Better íunctioning of all tho land uses in
thc su rro u n d in g s
Trang 6N guyên IÌCÌ 1 Giang ct aỉ Ị VN U Ịourìĩal ởỷScience, Earth Sciences 24 (2008) 66-78 71
3.4 Evaỉuation criteria
To choose critcria th at are u se íu l for the
m ulti-criteria analysis, several aspects arc
kept in m ind First of all, thc relatin g aspects
can iníluence thc vvatcr quality in the river,
estuaries and sh rim p ponds Secondly, the
relatcd actors, cvery actor has his m ain
interests, w hich arc im p o rtan t to find a
m easure, or a com bination of m o asu res that is
suitable for all tho actors T hirdly, all of the
suggestcd criteria have to m eet thc d em an d
of b o u n d ary conditions Based on these
rcquirem ents, th e íollovving critcria vvcrc
takcn into account in o rd cr to cv alu ate the
cíícctivenoss of alternativcs:
- C osts of im plem entation: this critcrion is
quite logical, as it is im p o rtan t for thc íarm ers
and th e local g o v ern m cn t that a m e asu re vvill
bo affordablo
- T im e of im plem entation: this is very
im p o rtan t for thc íarm ers M any íarm crs novv
are already in d eb t because of the loans thcy
took for thcir initial ỉnvcstm cnt costs For the
local go v crn m cn t it is also im p o rtan t to havc
a quick solution for the issucs at the íarm s as
the sh rim p íarm in g ind u stry itselí has great
potcntial for developm cnt
- M anagcability by íarm crs: it is im portant
that the m casurcs are not diííicult to implemcnt,
m aintain an d operate
- Economic beneíits: if m easu res arc
successíully im p lem en ted they could rcally
contribute to a m ore stablc econom ic
cn vironm cnt for both local ía rm c rs and
governm ent
- Effcct on p roduction: thc su rv iv al ratc of
shrim ps vvill increase differently p er m easure
or in som o cases an o th cr type of cu ltu re can
be a d d c d to the pro d u ctio n
- Effcct on discascs: if pollutod substances
in the w ater are re d u ced to th e n eed ed or
d esừ ed vvater quality sta n d a rđ s, the
occurrcnce of diseases will decrease
- E nvironm ental im pact: m easuros can bc taken at the intakc or outlet of the sh rim p íarm s In this w ay the im pact can bc different per m easure
- N eeded policics: d cp o n d in g on each
m easurc the governm ent nccds to apply policies to the arca aííoctcđ by the m easure This requires tim e-consum ing and costly
effortSt
- Large scalo effectiveness: It is im portant
to scc how large the inAucncc of a m casuro can bo, m ostly for the íu tu re p la n n in g of
aq u acu ltu re in Q u an g Tri Provincc
3.5 Dctermination o f critcrion ĩccights
VVhen the critcria have bccn selected, tho next step is to d eterm in e w cights for these critcria based on the im portance of each critcrion Bccause thc m ain objective of the stu d y is to create a m ore stablc econom ic
e n v iro n m en t for the íarm crs and g o v e rn m e n t thc tvvo critcria, w hich arc econom ic proíit and environm cntal im pact, will bo assigned the highest w eight O th cr objectives arc cost and timo of im plcm ontation, effect on discases Pinaily, the iinpact an d area of
im pact arc im portant for the aquaculturc, agriculture, ind u stries and o th er land uscrs Bascd on these criteria an d thc p reíercnce order, th e follow ing p arag ra p h discusses how
to d eterm in e thcse w eights by thc pairw ise com parison m ethod:
Establishment of painvisc comparison matrix:
Each p air of criteria vvas takcn from tho set of the criteria and com pare w ith each othcr Experts' consultation w as used for the rclative im p o rtan t level of one criterion betvvecn a pair of criteria based on iníorm ation ừi Tablc 2 The exercise vvas rep catcd for ail the pairs of criteria an d the result is p resen tcd in Table 3
Trang 772 Nguyeiì T im Giang ct al / VNU Ịoumal o f Science, Larth Scim ces 24 (2008) 66-7H
T ablc 3 T he p a in v isc c o m p ariso n m atrix
A: Econom ic b cn cíits 1.00 2.00 3.00 1.00 4.00 5.00 5.00 6.00 7.00
13: C osts o f im p le m e n tatio n 0.50 1.00 2.00 0.50 3.00 4.00 4.00 5.00 6.00
C: T ứnc o f im p le m e n tatio n 0.33 0.50 l.()0 0.33 2.00 3.00 3.00 4.00 5.00
D: lin v iro n n ic n tal im p act 1.00 2.00 3.00 1.00 4.00 5.00 5.00 6.00 7.00
E: Effect on diseases 0.25 0.33 0.50 0.25 1.00 2.00 2.00 3.00 4.00
F; M an ag eab ility by ía rm e rs 0.20 0.25 0.33 0.20 0.50 1.00 1.00 2.00 3.00
G: L arge scale effcctiveness 0.20 0.25 0.33 0.20 0.50 1.00 1.00 2.00 3.00
I I: Effect o n p ro d u c tio n 0.17 0.20 0.25 0.17 0.33 0.50 0.50 1.00 2.00
I: N c c d c d policics 0.14 0.17 0.20 0.14 0.25 0.33 0.33 0.50 1.00
T ablc 4 T he s ta n d a rd iz c đ pairw isc c o m p a riso n m atrix
A: Econom ic boneíits 0.26 0.30 0.28 0.26 0.26 0.23 0.23 0.20 0.18 0.25
B: C osts of im p lc m e n tatio n 0.13 0.15 0.19 0.13 0.19 0.18 0.18 0.17 0.16 0.17
C: Tim e of ỉm p le m e n tatỉo n 0.09 0.07 0.09 0.09 0.13 0.14 0.14 0.14 0.13 0.11
D: ỉỉnvironm ontal im pact 0.26 0.30 0.28 0.26 0.26 0.23 0.23 0.20 0.18 0.25
E: Effect on diseascs 0.07 0.05 0.05 0.07 0.06 0.09 0.09 0.10 0.11 0.08
F: M anagcability by ía rm c rs 0.05 0.04 0.03 0.05 0.03 0.05 0.05 0.07 0.08 0.05
G: Large scalc cffcctivcncss 0.05 0.04 0.03 0.05 0.03 0.05 0.05 0.07 0.08 0.05
ỉ ỉ: Effect o n p ro d u c tio n 0.04 0.03 0.02 0.04 0.02 0.02 0.02 0.03 0.05 0.03
l: N cedcd policics 0.04 0.02 0.02 0.04 0.02 0.02 0.02 0.02 0.03 0.02
Establishnicnt o f standardizcd comparison
matrix: This m atrix can bc estim atcd by
dividing cach elem cnt in thc pairw ise
com parison m atrix by its colum n total The
result is p rescn tcd in Table 4
Computation of criterion ĩvcights: VVeights
of each of th e criteria w ere d eterm in ed by
com puting the average of th e elem ents in
cach row of th e n o rm a li/e d m atrix The result
is shovvn in th e last colum n of Table 4
3.6 Mcasurcs fo r Quang Tri's brackish water
shrimp culture
To solve th e problem s relating to Q uang
Tri's brackish vvater sh rim p culture, thc study
considcrs those m casurcs that are being uscd
in tho targct areas as wcll as íorcign countries, such as Indonesia, C hina, B angladesh,
G erm any, Mexico, Colom bia, USA Somc of thcm arc in tro d u ccd as íollovvs
3.6.2 Structural mcasurcs
A ì: Poỉyculturc
In the sh rim p farm, the first crop vvill rem ain the sam e as bcíorc, but tho second crop Guly to O ctober) vvill be used to pro d u ce not only sh rim p but also other culture, likc oysters, crabs, m ussels, fish, etc In doing so, there vviU be tw o proíits: the n utricnts in the
w ater stcm m ừig írom the first crop will be
re u se d in tho second crop, and tho íarm ers
Trang 8Nguyeiì lien Giang ct ai / VNU Ịounml o f Science, Earth Sciences 24 (2008) 66-78 73
vvill have m ore cconom ic certainty, bccausc
thcy can bct on tvvo diííercn t horscs Some of
the sem i-intensive sh rim p íarm s have already
used the polyculturo m cthod, w ith fish and
ricc
A2: Bio-fìltcr
- A2.Ĩ: Mangrovc fĩltcr This m easure has
been alrcady co n d u ctcd by com bining the
sh rim p íarm ing in d u stry vvith the placing of
m angroves in Colom bia Ịl] T he cost of the
m easu re is around 100,000 USD (1995 price)
for 120 ha of m an g ro v es an d 200 ha of
p roduction pond arca [1] C onstruction of the
m casurc cost ab o u t 100,000 USD, vvhich is
very chcap in com parison vvith the cost of a
constructcd vvetland as proposed by
Schvvart/ and Boyd [ 1 ] T he m ost signiíicant
bencfit of thc system , followod by G auticr, is
the BOD and TSS rem oval from pond
cfflucnt A nothcr potcntiai íinancial bcncfit
C)f thc recirculation system is tho possiblc
prevention ()f bluo-groen algac bloom in thc
estuary, w hich m ay cause an off-flavor to
dcvclop in shrim p
- A2.2: VVctlainỉ A vvetland also can bo a
solution to Q u an g Tri Provincc Tho w etland
is locatcd near thc sh rim p po n d s and consists
of soil w ith a ccrtain slope and obstaclcs ừi it,
so that w atcr will flovv th ro u g h in a ccrtain
direction In this w ay the vvater gets cleaned
bcíorc it rcachcs th e discharge channcl [11]
The costs of a constructed vvetland d cp en d
on the size of the w ctlan d noodcd, w hich on
itselí d cp en d s on the am o u n t of flowing
vvastcwater T h e ad v an tag es of thc
constructcd w ctlan d s are that they can bc
very effective in im p ro v in g vvatcr quality in
the dow nstrcam w aters They also are
effectivo Ũ1 rem o v in g or stabilizừig
sedim ents, hcavy m etals and organic
contaminants.
- A2.3: Scdinicntation rcscrvoir + rcscrvoir
ĩoith culture (oỵsters, crabs) This system
includcs tw o basins: a sedim entation basin to settle tho su sp en d ed substanccs in the watcr; and a basin w ith bactoria, or other cultures likc oysters, m usscls or crabs, to rem ovc ccrtain n u trie n ts (Fig 4) Tho cost of this
m easuro is about 900 USD for 0.5 ha of reservoir
L » o « n d :
1 - S h rlm p P o n d *
2 - M*in Rlv«r
3 ■ I nta h* C h a n n a l
4 - D l»ch«ry« C h i n n t l
83SS3" Seđlm«nt«tlon Reaarvoir
R «»«rvolr Mltlì Cultur*
■■■■■ ‘ - Ịr»t«K* pip«Wchanntl«
R ac trcu lá lm o p ip * « lc h « n n * u
Fig 4 A h y p o th ctical cxn m p lc of p ro d u c tio n p o n d s
w ith se d im c n ta tio n a n d c u ltu rc re serv o irs [4].
3.6.2 Non-structural mcasures Bĩ: htiprovcd /ccding managcmcnt (appropriate/ceding, less antibiotics)
The m ajor p roblem s vvith N utrients,
P hosphates and BOD are m aừily causcd by íeeding the shrim ps m ore than they can eat and giving them too m an y antibiotics The excess of these substanccs will rem ain in the
w atcr a n d will also get in the sludge on the bottom of the sh rim p ponds By rcducing the íeeding an d thc antibiotics, less substanccs vvill get into tho w astew ater
B2: Bcttcr ĩvatcr managcmcnt Reducing the
number of timcs that watcr is taken in should
have a positive effect on thc am o u n t of pollu ted w ater taken in by farm s T hough not
Trang 974 Nguyei: T im Giang et nl / VNU Ịounml o f Science, ĩ.arth Scienccs 24 (200S) 66-78
changing the w ator oíten en ough m ay have
negative effects on tho chanccs of discascs [5]
In order to conduct effectively this m easure,
the tim ing of th c fri?shwator intake should be
changcd togethcr w ith thc o u tp u t of
vvastevvater, no t only from sh rim p farm s but
also thc vvastevvater o u tp u t of industries and
agriculture VVhcn thoso tvvo events occur too
closc to each othcr, sh rim p farm s vvill takc in
polluted vvater The p u m p in g in and out of
saline and vvastevvater should íollovv the tidal
regim e scientifically
In practice, in ordor to h ave m ore
effective m easures, a num ber of altcm atives
(especially tho non-structural) are usually
ừnplem entod sim ultaneously Based on the
Q uang Tri's local conditions and the ícasibility
of altcrnativcs, 10 com binations bclow vvere
takon into account in thc MCA process:
AI + A2.3: Polyculture + Sedimcnt reservoir
Sĩ rcscrvoir vvith culturc
AI + BI: Polyculture + Im provod íccding
m anagem ent
AI + B2: Polyculture + Botter w ator
m anagem ent
AI + BI + B2: Polyculture + Improved íeeding
m anagem ent + BcUer vvater m anagem cnt
A2.1 + A23: Mangrovc filtor + Sodimcntation
reservoir & rcsorvoir w ith culture
A2.1 + Bl: M angrove íilter + Im proved
íeeding m anagcm cnt
A2.2 + A2.3: VVetland + Sodim entation
reservoir & reserv o ữ vvith culturc
A2.2 + Bl: W ctland + Im proved íccxiing
m anagem ent
A2.3 + B l: Sedim entation reservoir &
reservoir vvith culture + Im proved íceding
m anagem ent
A2.3 + BI + B2: S edim entation reservoir &
reservoir vvith culture + Im provcd íeeding
m anagem cnt + Bottcr w ater m anagem ent
In order to score for each of the m casures
vvith the critcria, the m ean in g of tho im pact
levels of m easu res on the critcria should be
dcíincd The m can in g lovols are as íoUovvs:
Costs o f impỉcmcntation: Tho lovver the
scorc tho better
Time o f implcincntation: The lovver the
am o u n t tho better
Managcability b\j /armcrs: The easier thc
better
Economic bcncfits: The higher thc better Effcct on production: Tho higher thc effect
the botter
Effcct on diseascs: The highor the cffect the
bettcr
Environmcntal impact: The highor the better Ncedcd policies: The less tho am o u n t of
policies necded (or guidanco by the government) the bctter
Largc scaỉc ẹffèctivcness: The hig h cr thc scale the b etter
Based on these m caning, thc im pact levels and scores of tho suggcstod m casu rcs for cach of the criteria should be asscsscd
T he cost of im plcm ontation critorion:
am ong m easures, tho m oasurc vvith tho highest and low est cost vvill gct the scorc of 0 and 1, respectivoly T he othcrs vvill bo in terpolatcd from the lovvest and highcst cost
T he tim e of im plom ontation critcrion: if thc im plem en tin g tim e of a m easure is longer
th an 4 m o n th s, equal to 2-3 m o n th s an d shorter th an 2 m onths, its score is 0, 0.5, and
1, rcspcctivcly
O th er criteria: this stu d y evaluates im pact
of tho m casu res in 3 lcvels: h a rd /m c d iu m / easy or h ig h /m cd iu m /lo w vvith 3 respective sta n d a rd i/o d scorc of 0, 0.5, and 1
Tho s ta n d a rd i/c d scorcs for diffcrent criteria arc sh o w n in Tablc 5
Based on thc standardi/.ation scorirtg card, the stu d y has consulted experts in thc som c of rolated sectors, local authoritios an d resid en ts about the im pact lcvel of m oasuros
on each of the critcria T hese evaluation results are sh o w n in Table 6
Trang 10N $ U \/C ỈĨ iiciĩ Giang c t aỉ / VNU Ịourĩiaỉ o f Sâence, L a r t h Scieĩĩces 24 (ĨOOS) 66-78
T ablc 5 S ta n d ard iz atio n sco rin g card
75
C o sts of im p le m e n ta tio n h ig h /m cd i u m /lo w 0/0.5/1
T im e of im p lc m c n ta tio n 4/2-3/1 0/0.5/1
M an ag o ab ỉlity by ía rm c rs h a rd /m e d i u m /c a sy 0/0.5/1
E conom ic b en c íits h ig h /m c d iu m /lo w 1/0.5/0 F.ffcct on p ro d u c tio n h ig h /m e d iu m /lo w 0/0.5/1 F.ffect o n d iseascs h ig h /m c d iu n i/lo w 1/0.5/0 r.n v iro n m c n ta ỉ im p act hig h /m cd iu n V lo w 1/0.5/0
N c c d c d policics high/m odium /lo^v 0/0.5/1
I arg e scaỉc cííccti v cncss h i g h /m ed i u n ì/lo w 1/0.5/0
T able 6 S co rin g card of com bination of m casu rcs
C o m b in a tio n o f M casu rcs
C o sts o f im p le m e n ta tio n est: 335 cst: 220 est: 220 cst: 240 est: 737
T im e o f im p le m c n ta tio n 2-3 2-3 2-3 2-3 >4
M an a g e a b ility by ín rm crs m c d iu m m cd iu m m e d iu m m c d iu m m ed iu m
F.ffect on p ro d u c tiơ n high high h ig h high m cd iu m
Rffcct on đ iseaso s m c d iu m m cdiurn m e d iu m m c d iu m m ed iu m
[{nvironm cntal im pact m c d iu m m cd iu m n ic d iu m m c d iu m high
N c c d c d poỉicics m c d iu m m cd iu m m e d iu m m e d iu m low
C o m b in a tio n of M casures
C o sts o f im p lc m c n tatio n est: 622 cst: 8351 cst: 8236 cst: 155 est:175
T im e o f im p le m c n ta tio n >4 >4 >4 1-2 1-2
M a n a g c a b ility by íarm c rs m e d iu m m ed iu m m e d iu m m c d iu m m c d iu m
F xonom ic b c n c íits m e d iu m m e d iu m m c d iu m m c d iu m high
E ííect o n p ro d u c tio n m c d iu m high hig h m e d iu m high
Effcct o n d iseasc s n ie d iu m high h ig h m c d iu m m c d iu m
E n v iro n m e n ta l im pact hig h high h ig h low m c d iu m
N c c d e d policies m e d iu m m c d iu m m c d iu m high low
L arge scalc cffcctiv cn ess h ig h m cd iu m n ic d iu m lovv lovv
Next, thc s ta n d n rd i/e d score for tho cost
of im plem cntation sh o u ld bo estim ated so
that the overall cvalu atio n can be done Fừst
of all, tho cost of im p lem en tatio n a n d applicd
areas of so m e projccts in o th er locations are
collocted [1, 11] Tho research assumcs that
the cost to establish thcse m oasurcs in Q uang
Tri Provincc is cqual to tho cost in other
regions Those values, then, arc dividcd by thc sh rim p p o n d area to gct tho standardized cost (USD/ha) The results are presented in Table 8 As a rule, the altcrnativo A2.3 + BI
w ith low cst cost (155 USD) will be assigned a
score of 1 and the combination A2.2 + A2.3
vvith h ighest cost (8,351 USD) vvill be assigned a score of 0 The others are