B GIO DC & O TO B NNG NGHIP & PTNT
VIN KHOA HC THY LI VIT NAM
VIN KHOA HC THY LI MIN NAM
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NGUYN NH VNG
C TNH THY NG LC V MI TRNG
VNG TRIU NG DNG CHO H THNG
NUI TRNG THY SN VEN BIN
Chuyn ngnh : K thut ti nguyn nc
M s : 62 58 02 12
TM TT LUN N TIN S K THUT
TP. H CH MINH, NM 2017
Cng trnh c hon thnh ti:
VIN KHOA HC THY LI MIN NAM
Ngi hng dn Khoa hc:
1. GS.TS. Tng c Thng
2. GS.TS. L Sm
Phn bin 1: GS.TS. Nguyn Th Hng
Phn bin 2: PGS.TS. L Vn Ngh
Phn bin 3: PGS.TS. L Th Kim Cc
Lun n s c bo v trc Hi ng chm lun n cp Vin
hp ti:
Vin Khoa hc Thy li min Nam
658 V Vn Kit, Phng 1, Qun 5, Tp. H Ch Minh
Vo hi . gi . pht, ngy thng nm 2017
C th tm c lun n ti:
- Th vin Quc gia Vit Nam
- Th vin Vin Khoa hc Thy li Vit Nam
- Th vin Vin Khoa hc Thy li min Nam
- 1 -
M U
1./ TNH CP THIT CA TI LUN N
ng bng sng Cu Long (BSCL) c xem l va tm
nc mn l vng triu ln nht ca c nc, vi din tch nui
khong 600.000 ha ven bin,[39]. Th nhng nhiu nm qua, vng
nui tm trng im ny vn phi i u vi nn nhim ngun nc
do h thng thy li phc v cho NTTS khng ng b. Hu ht cc
cng trnh thy li phc v cho NTTS vng ny hin nay ch yu l
ca cc vng sn xut nng nghip trc y li. iu ny dn n
mt s bt cp gy kh khn trong vic pht trin tm nui hin nay.
Trn thc t, thng th mt ng mng, mt con knh phi m
nhn cng lc 2 chc nng l va cp nc ao nui v va thot nc
nhim. y cng l mt trong nhng nguyn nhn chnh dn n tnh
trng tm nui trong nhiu nm qua cht hng lot trn din rng,
nhim dch bnh ly lan.
Xut pht t cc vn cp thit ca thc tin, trong khi quy trnh
cng ngh nui nh yu cu v k thut nui, ging v thc n,....
c nghin cu v ph bin tng i rng ri, th hu nh cha c
nhiu cc nghin cu v c tnh ngun nc trong h thng NTTS.
Hn na, quy m ca cc cng trnh thy li vng NTTS ph thuc rt
nhiu vo ch nc h thng, in hnh l ch thy triu v kh
nng cp thot nc ch ng. Trong iu kin nh vy cn thit phi
nghin cu cc c tnh thy ng lc v mi trng ngun nc trong
h thng knh dn vng triu, lm c s khoa hc cho vic thit k v
qun l vn hnh cc h thng thy li phc v NTTS vng ven bin.
2./ MC CH CA LUN N
Mc ch chung ca lun n l nghin cu c tnh thy ng lc
v mi trng trong cc h thng knh dn vng triu ng dng cho h
- 2 -
thng NTTS ven bin. Cc mc ch c th ca lun n l : (i) Xc
nh c c ch lan truyn cc ngun nc, quy lut trit gim ngun
nc trong h thng knh dn vng nh hng triu; (ii) Xc nh
c cc c tnh thy ng lc mi trng vng triu cho mt s s
mu h knh in hnh lm cn c cho vic thit k h thng thy
li hp l phc v NTTS ven bin.
3./ PHNG PHP NGHIN CU
(i) Trn c s iu tra kho st thc t cc h thng NTTS ven
bin, lun n kho cu l thuyt cc s mu c bn in hnh
cho cc h knh dn vng triu tm nguyn l, xc nh quy lut
thy ng lc ngun nc ng dng trong cc h thng NTTS ven
bin; (ii) Lun n s dng phng php m hnh ton p dng l
thuyt lan truyn cc thnh phn ngun nc kt hp vi phn mm
thy lc 1 chiu (MIKE 11) tnh ton phn tch c tnh v quy lut
thy ng lc mi trng ngun nc cc h thng NTTS ven bin.
4./ CC NI DUNG NGHIN CU CA LUN N
(1) Tng quan h thng thy li phc v NTTS, nh gi cc
cng trnh khoa hc c lin quan n ngun nc v mi trng
vng NTTS ven bin v xc nh vn cn nghin cu ca lun n;
(2) Nghin cu c tnh thy ng lc mi trng trong cc h
thng knh dn vng triu in hnh cho cc h thng NTTS (h knh
n c bn, h knh dng cnh cy gm knh chnh v knh nhnh cc
cp, h knh c nhiu vng kn, h knh c cng iu khin);
(3) ng dng l thuyt lan truyn cc thnh phn ngun nc kt
hp vi m hnh ton phn mm thy lc MIKE 11 nghin cu c
tnh thy ng lc mi trng ngun nc (chng hn ngun nc
mang mm bnh thy sn,...) cho 2 h thng thc t NTTS ven bin
BSCL (vng nh hng triu bin ng v triu bin Ty).
- 3 -
5./ I TNG V PHM VI NGHIN CU
i tng nghin cu ca lun n l vn thy ng lc mi
trng trong h thng knh dn cc vng NTTS nh hng triu.
Phm vi gii hn nghin cu ca lun n l cc h thng sng
knh, h thng cng trnh thy li phc v NTTS vng ven bin nh
hng triu bin ng v triu bin Ty BSCL.
6./ NGHA KHOA HC V THC TIN CA LUN N
a) ngha khoa hc
Lun n phn tch lm r c ch thy ng lc lan truyn cc
ngun nc trong h thng knh dn vng NTTS nh hng triu
(ngun nc nhim bn, ngun nc mang mm bnh thy sn, ngun
nc mn, ngun nc ngt sch cp cho cc vng nui,...);
nghin cu c tnh thy ng lc mi trng vng triu cho
mt s s mu h knh in hnh t cc h thng NTTS thc t ven
bin. Gii quyt c v mt khoa hc mt s bi ton v cht lng
nc v mi trng trong cc h thng NTTS m l thuyt truyn
thng thc hin cn rt hn ch hoc cha gii quyt c.
b) ngha thc tin
Kt qu nghin cu ca lun n c th ng dng vo thc t sn
xut, lm c s thit k h thng thy li phc v NTTS vng ven
bin BSCL v cc vng khc c iu kin tng t;
Mt s gii php b tr h thng cng trnh mang tnh nh hng
nhng cng c th coi l cc hng dn s b cho cc c quan qun l
ngnh v a phng khi thit k quy hoch cc h thng thy li phc
v NTTS ven bin BSCL.
7./ NHNG NG GP MI CA LUN N
(1). Lun n a ra khi nim mi (c tnh quy c), vi tn gi l
ngun nc quan tm hay TPNquan-tm, nh vic nghin
- 4 -
cu lan truyn cc ngun nc trong h thng NTTS c tin
hnh theo th thc lan truyn tng TPNquan-tm in hnh,
lm cho bi ton h thng NTTS chu cc ngun nc tc ng
tr nn n gin hn rt nhiu. Cch gii bi ton y thay v
tnh nng ngun nc ta s tnh t l )(, tp itmquan ca ngun
nc quan tm, biu th theo %. Kt qu kho cu ng thi cc
TPNquan-tm trong h thng NTTS gp phn lm r c ch lan
truyn, quy lut vn ng, qu trnh trit gim ca cc ngun ny,
t nh gi c tc ng ca tng loi ngun v phng
php khoa hc qun l chng;
(2). Lun n pht trin phng php lun ng dng l thuyt lan
truyn cc thnh phn ngun nc kt hp vi phn mm thy
ng lc mt chiu h sng knh (chng hn MIKE 11) lm r c
ch lan truyn TPNquan-tm gia knh chnh v knh nhnh trong
h thng NTTS theo cc pha triu. Vi cc knh nhnh, pha u
knh tip nhn nhanh ngun nc t sng /knh chnh nn d b
nhim nc bn, nc nhim, nc mang mm bnh thy sn t
cc vng khc trong h thng. Trong khi cui knh th tip
nhn ngun nc kh khn hn v cng chm hn nn kh b
nhim nc bn, nc mang mm bnh. Tuy nhin khi gp s c
mi trng, vic thau ra phn cui knh (nht l knh ct) kh
khn hn rt nhiu so vi u knh;
(3). Kt qu nghin cu ca lun n v c tnh thy ng lc cc
TPNquan-tm (nc mn, ngt, nc bn, nc mang mm bnh
thy sn,) trong cc h thng NTTS c th m ra hng pht
trin cng c d bo c ngun nc (cht v lng) cho cc
vng nui trng khc nhau trong h thng, t c c k
hoch thch hp cho vic ly nc (cp mn, ngt), x thi, thau
ra h thng NTTS v qun l dch bnh thy sn vng nui;
- 5 -
(4). Kt qu lun n ch ra rng cc h thng NTTS cn phi cn
c vo h c tnh vn ng (lan truyn) cc ngun nc thit
k v vn hnh, trong cn ch : (a) Hn ch ti a b tr knh
ct; (b) V tr v quy m knh chnh, knh nhnh cc cp c vai
tr quan trng trong vic phn b t l cc ngun nc trong h
thng, cn c nghin cu k khi thit k theo quan im to
c ngun nc tt, trnh lu cu, hn ch lan rng cc ngun
nc c cht lng km v x l s c mi trng nhanh.
Chng 1: TNG QUAN
1.1. TNG QUAN V HTTL PHC V NTTS VEN BIN
1.1.1. c im cc h thng thy li phc v NTTS
c im chung v HTTL phc v NTTS ven bin: (i) H thng
lun chu nhiu ngun nc tc ng, do h thng chu nh hng trc
tip ca thy triu nn thun li trong vic cp mn nui tm; (ii)
Cc h thng trc y phc v cho nng nghip, do ch cn h s cp,
thot nh nn quy m khng ln. Khi chuyn sang NTTS, ngoi yu
cu cp thot cc loi ngun nc cn c yu cu thau ra, trao i
nc rt ln; (iii) Kh nng tiu thot, thau ra ca h thng knh cn
cha cao, mt s vng b tr knh cha hp l, c bit c vng li b
tr nhiu knh ct. Nc lu cu lu di trong h thng, d sinh ra cht
lng km; (iv) Nhiu h thng kim sot ch nc cn thp, rt
hn ch trong vic to ra ngun nc c cht lng thch hp cho thy
sn; (v) H thng knh rch an xen v thng ni thng sut vi
nhau, nhiu vng khng c cng iu tit, kim sot nn rt kh khn
trong vic ngn chn dch bnh lan truyn theo ng nc, nht l
trong cc h thng c knh cp v thot chung.
1.1.2. Nhng tn ti v hn ch ca HTTL phc v NTTS
H thng cng trnh thu li xy dng trc y vi mc ch
ch yu l phc v SXNN, nay chuyn sang phc v NTTS mc d
- 6 -
trong thi gian qua h thng thy li bc u pht huy hiu qu
cho NTTS, nhng ng trc i hi ca thi k mi, thy li cha
p ng c yu cu ca NTTS, vn cn tn ti cc vn chnh nh
sau : (i) Cc h thng trc y ch thit k cho nng nghip (trng
la) nay chuyn sang phc v NTTS khng cn ph hp na, c quy
m v cu trc, b tr cng trnh; (ii) Phn ln b tr khng hp l, nht
l knh cp v knh thot (cha phn bit vng no dng chung, vng
no cp thot tch ri); (iii) Chnh cch b tr cha hp l nh vy dn
n ngun nc trong nhiu vng ca h thng b nhim. Khi gp
cc s c mi trng khng x l c, hoc l x l hiu qu thp;
(iv) Ch yu ly h thng thy li cho nng nghip trc y phc v
NTTS do vy quy m c cng v knh u cn nh dn n kh nng
trao i nc km, kh nng vn hnh cng trnh ly mn rt hn ch.
Hnh 1-6: Hin trng HTTL vng trng la nay phc v NTTS Tr Vinh
Cng tc thy li phc v NTTS vn cn cha tng xng vi
nhng li ch do NTTS mang li v cn thp xa so vi yu cu pht
trin NTTS hiu qu cao hn theo hng thm canh. Tm li HTTL
phc v NTTS ven bin cha ng nhiu vn phc tp, trong s
nhiu vn cn tn ti, cn c gii quyt th vic n
