Ảnh hưởng của xói lở bờ biển và sa bồi luồng lạch tới nuôi thủy sản hội thảo toàn quốc bảo vệ môi trường và nguồn lợi thủy sản hải phòng

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BQ THUY SAN

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N G H I~ P


ABSTRACT

INFLUENCES
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et phai

AND SILTATION

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ON AQUACULTURE

Nguyen Huu Cu, Tran Duc Thanh
Hai PhongZYXWVUTSRQPONMLKJIHGFEDCBA
In s titu te o f O c e a n o g r a p h y

e trong
ii trong
cac vi

EROSION

C o a s ta l

e r o s io n

h e a v ily in flu e n c e d

and

s ilta tio n

b y fis h in g

T hough not recorded

a c tiv itie s ;

a n d d o c u m e n te d

b e lie v e d to b e g r e a t in fo r m
- decrease

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is c o m m o n

in lo c a litie s

in c lu d in g b r a c k is h a q u a c u ltu r e
so

fa r , e c o n o m ic

w h ic h

have been

a n d m a r in e c u ltu r e .

lo s s e s d u e to th e s e p h e n o m e n a

are

o f"

in th e a r e a o f a q u a c u ltu r e ,

_ c h a n g e in th e w a te r q u ~ lity , a n d e v e n le a d in g to d e g r a d a tio n o f s o m e a q u a c u ltu r e p o n d s ,

du

luqng
iuoi, dam
lam kenh

- r e d u c tio n

in th e n a tu r a l s to c k , q u a n tity a n d q u a lity o f a q u a tic p r o d u c ts

- a q u a c u ltu r e
- u n -h a r v e s te d

:lac bi~t la
e 'sinh thai
:hat thai tit

in fr a s tr u c tu r e

d e s tr o y e d

b y e r o s io n ,

p o n d s d u e to e r o s io n - b r o k e n c a u s e w a y s

in s to r m s a n d flo o d s

ANH HUONG CUA XOI LO BO BIEN

v A SA BOI LUONG LACH T61 NUOI THUY SAN
Nguyen Htru Cir, Tran Dire Thanh
P h d n v ie n H d i d u a n g h o c ta i H d i P h o n g

1. MO DAU
.

X6i 16 ba bien va sa boi luong lach la cac dang tai bien moi tnrong

dia chat (tai bien

cl~: chat)_ph6 bien 6 vung be bien Viet Nam, gay hau qua kinh te - xa hoi nang ne bat chap
~h~g no, hrc ?hong
tieuaclavanuacma-n)
~
"

chon~ to Ian nhu hien nay, trong d6 c6 nuoi thuy san (nuoi thuy san
, de0 tal
"d' an h baat t h'uy san
, tong
he
.,
va'a c hiirng rmrc nao

qua su suy giam
m nang nguon lei tv nhien,

b"
. .'
;"
.
X6i 16 Him h d'
dan ve hi
.,1c 0 uan~ a lui dan ve phia luc dia, b01 tu, ngiroc lai, lam cho ba bien Ian
x ,

tuang d~' :

nuc; thu

1
y

bl:?

?

.,

,

•• '.'

lach 6 cac vung cira song va dam pha, va can bang

1a thay the theo mila voi cuong dQ nrong dirong d~u anh huang t6i

hoac ,~6~ lap luong

!~-

bci
XOI
san duO! dang:

(1) - thu hep dien tich nuoi
( 2 ) - thay d,1· d:;'"
'
01
leu hen moi tnron g
(3 ) _

..
nuOl,
suy glam ngu6n gicng tu nhien,
.,

,

.

77


(4) - khong 6n dinh nghe nuoi ca ve khong gian, thai gian (rnua vu) va doi tuqng nUai.

Bai vier nay de cap toi tinh trang xoi 10' be bien, sa boi luong lach va anh huang c'
cluing toi nuoi thuy san thong qua cac phirong thirc khac nhau.
ua
2. TONG QUAN RQPONMLKJIHGFEDCBA
V E XOI LO BO BIEN v A SA BOI LUONG L~CH
2.1. X6i

la bb' bi~n

2.2. ~
TJ
nang (
C 1 chal
130 h,
tritn v
Tu

- VungZYXWVUTSRQPONMLKJIHGFEDCBA
b i r bien B a c B 9
Vung bo bien B~c B¢ tir Mong O E (Quang Ninh) toi Lach Tnrong (bac Thanh H 6 a )
gorn 2 doan bo: Mong O E - Do San, Do San - Lach Truong. M6i doan ba nay co hinh thai
cau true moi tnrong dia chat khac nhau, co mat cac dia he khac nhau va tat yeu tiern nan~
nuoi thuy san khac nhau.
Doan ba Mong Cai - Do San dac tnrng boi vGng - vinh va vung cira song hinh pheu, noi
co tiern nang nuoi thuy san 1< ;1 - man trong darn va nuoi hili san (mariculture) bang long be.
Dean be Do San. - Lach Truong la ba chau th6 song Hong, noi co tiern nang nuoi thuy san
ruroc 1< ;1 - nhat nhung kern 6n dinh do boi nhanh.

pheu, (
hlnh It

luong I

o

va dam

bitn nh
nguon 1
la xoi 1,·.
bien Hi
dang va

Trong thai gian 1990 - 2000, co 30 diem xoi 10' bai trieu tir Mong Cai toi Cira Luc tren
chieu dai 44 565m vci toe d¢ trung blnh 3,1 m/nam. Chieu dai cac doan bo bi xoi 10trong
khoang 420 - 4 OOOmva toe do xoi 10' trong khoang 1,4 - 8,0 rn/nam. Tren dean ba Cira Luc
- Do San co 15 di~m xoi 10' voi tong chieu dai 43 920m va toe d¢ xoi 10' trung blnh 4,4
rn/nam. Chieu dai cac doan xoi 10' trong khoang 800 - 6 400m va toe d¢ xoi 10' trong khoang
1,2 - 12,9 m/nam. Trong diem xoi 10' tren dean bo nay a cat Hai voi chieu dai 6 400Il} va
toe d¢ 12,9 m/nam, a Phu Long (Duong Gianh) dai 3 OOOmvoi toe do 9,6 m/nam va 0 Dlnh
VG dai 3 OOOmvoi tee d¢ 8,6 m/nam. Doan be Do San - cira Ba Lat co 3 diem xoi 10tren
t6ng chieu dai 2 700m voi toe d¢ trung blnh 9 m/nam. Dean bo cira Ba Lat - Lach Truong
co 3 diem xoi 16 tren tong chieu dai 17 200m voi tee d¢ 14,5 m/narn. Co the theo d6i dien
bien xoi 10' cua cac doan bo bien ttr C U < l: Luc toi Lach Truong trong thai gian 19,30 - 2000
va dien tich mat di hang nam qua tirng thai ky tren bang 1.
- V u n g b o b iln T r u n g B 9

m ot

Oc
Tinh) h i

cira non
delta tri,
ap dao (
pha, tha:
d o khi c
luong - (
Can]

dirng dal
chi can n
bao heat
trieu rrr' )

o cat
b6i Ian d..

Vung be bien Trung bo (tinh tir Thanh Hoa toi Ninh Thuan) co 275 diem xoi 10 tren
chieu dai 328,16 km voi toe d¢ xoi 10' trung binh 11,9 m/narn va dien tich mat di 389,9 _

tinh rien;

ha/nam (Pham Huy Tien va nnk, 2000). Dac bier trong thai gian 1999 - 2000, nhieu diem

vung cat,

xoi 16 day lui dirong bo tai 40 - 60m va tharn
- V u n g b ir b iln n a m T r u n g B 9

va

chi

toi 150 - 250m.
3.

N am B9

Vung bo bien nam Trung B¢ (Binh Thuan) va Nam B¢ (toi Kien Giang) co 71 di~m x6i
16 tren chieu dai 478,12 km voi toe d¢ trung binh 2,5 m/nam (Bui Hong Long va nnk,
2000), trong do co 12,8% chieu dai be bi xoi 10' voi toe d¢ 2,5 - 5 m/nam, nrong U n g ,
43,7% - 5 - 10 m/nam va 43,5% tren 10 m/narn.
78

ANH

I

THin
Thon!
thuy trieu
b6i lu6ng


ng nUaL

Sa boi luong lach
ua trinh phat trien chau th6 (delta), dirong ba tien dan ve phia bien do bai boi
TrO~gbi mat va me rong nhanh, dat toe d¢ trung blnh 27 m/narn (Ian nhat 120 m/nam)
~Anga~ath6song Hong, 50 - 80 m/narn (Ian nhat 150 m/nam) 0 chai: th6 song Mekong va

2.2.
.uOngRQPONMLKJIHGFEDCBA
CUa

~3~ ha/nam 0 rieng ban dao Ca Mau.

6

cac chau thd Ian nay, he thong lach trieu kern phat

trien va chong tan.
he
tanh R6a)
hlnh th"ai,
tiern nang

Tuy nhien, xoi 10 va bci tu lien quan chat che voi nhau. 6 cac vung cira song hlnh
ch~ng han vung cira song hlnh pheu Bach Dang va Dong Nai, qua trlnh san bang dia

~m:'luon xay ra theo ph~an,~ th"uc ~M ~uy bili .trieu ca~: n:o r?n~.bil~ ;rie~ th~p v~ bdi lap
juong Iach. tao de cat chan Iui dan ve phia luc dia gay boi lap ca bai tneu lay va luong lach.

o mot so noi nhu Duong
va d~m nuoi thuy san.

pheu, noi
g long be.
,i thuy san

6

Gianh (Phu Long), de cat chan lui dan dil vui lap rirng ngap man
vung cira song chau thd, xu the chung la bdi tu IAn tien ve phfa

bien nhirng van dan xen C\1Cbo ( t h a i gian, khong gian) cac diem xoi 10 do phan bo boi tich
nguon luc dia qua bat doi ximg giira chu hru va cac ph an hru, Dien hinh cua tnrong hop ~ay
la xoi 10 ba bien Hai Hau lien quan toi viec chan d~p song So. Luong vat chat do xoi lo'ba
bien Hili H~u dll tham gia vao dong boi tfch doc be di chuyen ve phia tay nam gay bien
dang va bdi lap ludng vao cang Hai Thinh.
'

o

a Luc tren
cac vung cira song liman, dien hinh la cira Lach Ghep (Thanh Hoa), Cira Khau (Ha
5i 10 trong ZYXWVUTSRQPONMLKJIHGFEDCBA
Tinh) hay cira song Cu De (Da Nang), V.V.,boi tu co xu the dong kin cira va boi lap luong
a Cira Luc
cira nong dan ve mua kho do dong boi tich cat d9C be tao roi cat phat trien tir mot phia va
g blnh 4,4
delta trieu len. v e mua mira, chinh cac thanh t<:10n ay bi pha huy do dong chay song manh
ng khoang
) 400m va
va o Dinh
xoi 10 tren
ch Tnrong
:0 d6i dien
no - 2000

xoi 10 tren

it di 389,9
ihieu diem

1 diem x6i
19 va rink,
uang ung,

ap dao dong trieu, dac biet khi co lti Ian. Tuong tv voi hien tuong nay la bdi lap cira dam
pha, tharn c h i dong Iil pha de cat chan t<:10
them cira moi ve mua mua hoac cira thay the gan
d6 khi cira Cll bi boi lap ve mua kho ma con nguoi loi dung gia co thay VI nao vet thong
luong - dien hinh la cac cira cua he dam pha Tam Giang - Cau Hai (Thira Thien - Hue),
Cang Hai Phong dll tirng la cang Ian nhat bac Viet Nam mot t h a i roi dan mat di vi tri
dirng dau nay do bdi lap luong lach. Vao dau the ky tnroc (trong nhtrng nam 1920 - 1930),
chi can nao vet hang nam chirng 1 trieu rrr' bun cat la du duy tri luong 0 d¢ sau 6 - 7m dam
baa hoat dong cho tau tren V<:1n
tan hoat dong. Nhung hien nay, lirong nao vet len t a i 3 - 5
trieu rrr' m&i nam mci duy tri duoc d¢ sau 3,5 - 4m.

o cac vung cat ven bien mien Trung, cat di dong tro thanh tai bien nghiern trong, gay
bdi Ian dat canh tac va th6 cu, boi lap va vo hieu hoa cong trlnh thuy lei va giao thong. Chi
tinh rieng 2 huyen Quang Ninh va L~ Thiry (Quang Blnh) , noi co khoang 30 000 ha dat
vung cat, toe d¢ boi Ian do cat khoang 176 ha moi nam trong khoang t h a i gian 1993 - 1995.
3.

ANH HUONG
THUYSAN

CUA

XOI LO

BO BIEN V A SA BOI LUONG LACH TOI NUOI

.

, Th?,ng qua dong hrc moi tnrong dia chat vung be bien, trong do co vai tro cua song,
~~~ytr;eu, song, dong chay va tac dong cua con ngtroi, anh htrong cua xoi 10 bo bien va sa
oi luang lach tci heat dong thuy san noi chung hay nuoi thuy san noi rieng theo c,ae
79


,

phuong

thirc khac nhau:

anh huong tnrc tiep, gian tiep (dan suat), anh huong tru6e

..

mih '

lau dai (tiern nang) duoi cac dang khac nhau (4 dang) nhu vita gioi thieu 6 phan ZYXWVUTSRQPONMLKJIHGFEDCBA
m a dii v~
U Va
gici thieu khai quat.RQPONMLKJIHGFEDCBA
Mac du chira c6 so lieu thong ke va danh gia cu the, nhung t6n that kinh te thuy ,
san

chac han khong nho khi nhin nhan tir nhfrng khia canh khac nhau:

5.

6.

(1) phi, t6n hang nam cho cong tac tu b6 de darn, gia co cong, ke va duy tu luong dan

7.

mroc,

(2) thu hep quy dat nuoi tiem nang, thu hep va thoai h6a darn nuoi dang diroc Slr d\lng,
(3) giam sari hrong va chat Iirong thuong pharn thong
tnrong, nguon giong va nguon loi tu nhien,
(4 )

ton that tnrc tiep doi nrong nuoi do x6i
mua mira bao va Hi.

qua suy giarn chat luqng mOi

8.

1 6 p h a h u y b o , do sa b o i gay n g a p

iing trang
9.

NH~NXftTvAKHUYtNNGHl

X6i 1 6 be bien hay sa boi luong lach la cac dang tai bien moi tnrong

dia chat gay hau

bar

qua kinh te - xa hoi nang n6, trong d6 c6 thuy san, va con tiep tuc dien bien phirc tap
no hrc phong

chap nhirng

to Ian nhir hien nay. Anh huang

chong

cua chung toi cac hoat

11

dong thuy san, dac biet la nuoi thuy san mroc lc, la anh huang toan dien ca true tiep va gi.in
tiep (dan suat), ca tnroc mat valau
tich nuoi va quy
luong

thirong

dai (tiem tang) va gay hau qua diroi dang: thu hep di¢n

dat nuoi, thay d6i dieu kien moi tnrong nuoi, suy giarn san hrong va chat

pharn, nguon

giong va nguon

lei tu nhien, khong

6n dinh nghe nuoi 0 tat

ca

cac loai hinh thuy vue ven bb noi c6 tiern nang nuoi thuy san.
Dieu d6 doi hoi quy hoach nuoi thuy san ben vfrng gan lien voi quy hoach bao v~ moi
tnrong

truce

tac dong cua cac hanh dong phat trien kinh te - xa hoi cling nhu tac dong cila

thien tai, trong

d6 c6 tai bien moi tnrong

dia chat vung bo bien nhir x6i 1 6 b o ' bien, sa boi

luong lach, cat bay, cat chay, v.v.

TAl LI~U THAM KHAo
1.

Dinh Van Huy, 1996. Dac diem hinh thai dong hrc khu b o bien hien dai Hai

Phong. Luan an PTS. Khoa hoc Dia ly - Dia chat. Ha Noi 1 - 127 trang.

2.

Dinh

HGu Cir va nnk, 1999. D f i c d i l m d i a d o n g luc b i t chdu
Hong, Bao cao M tai cap co so nam 1999. Liru trir tai Phan vien Hiii

Van Huy, Nguyen

th d s o n g

dtrong hoc tai Hai Phong,
3.

Le Xuan Hong,

1

1997. N g u y e n

cong tinh nghien ctru Dia chat
KH & KT Ha Nqi.

4.

Nguyen

Bieu,

Proceedings

1998.

of the 5

Oct. 1998, Hanoi,

80

n h d n x 6 i lc j

va

Asean Science

Vietnam,

b iln

V i¢ t N a m

cae

d o c o n n g l 1 O 'i .

Dia Vat ly bien, tap III, trang 291 - 295. NXB

G e o -h a za rd s

th

ba

in M a r in e

and

and Technology

p. 12 - 19.

C o a s ta l

Zone

o f V ie tn a m .

Week Conference,

12 -14


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21
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DIEU TRA NGHIEN COO KY SINH TRUNG VA BENH VI KHUAN TREN OC
HUONG ( B A B Y L O N I A A R E O L A T A ) V A so HUYET ( A N A D A R A G R A N O S A )

112

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