Tac dng t nhien va nhan sinh dn s ph

MUCL'UC
STT

Ten bal

Trang

1 Uri n6i dau

3

2

5

MQt s6 van de khoa hoc va cong nghe phuc vu phat trien kinh t~

xii hoi trung du va dong bang song Hong
3

GS.ZYXWVUTSRQPONMLKJIHGFEDCBA
D u a n g H ZYXWVUTSRQPONMLKJIHGFEDCBA
lin g D a t : Khoa hoc cong nghe phuc Yl:1 cong
nghiep hoa, hien dai hoa nong nghiep va nong thon vung dong
bang song Hong

13

•4

PGS. PTS. N g o D o lin V in h : MQt s6 van de ve khoa hoc cong
nghe d6i voi phat trien vung trong qua trinh cong nghiep hoa,
hien dai hoa a Viet nam

19

5

KS. N g u y in N g u y e n O d n h : MQt s6 van de chulkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA
ye u ve "Khai
22
thac t6ng hop va su dung hop 19, ben virng tai nguyen dai ven
bien B ik bo"

6 Hien trang moi tnrong mroc cira song ven bien Hai phong

28

7

GS. PTS. T r d n H ie u N h u e : Cong nghiep
nhiem moi tnrong mroc

37

8

PTS. T r d n D u c T h { ln h , PTS. T r d n D in h L d n , PTS. D in h V a n
H u y : Tac dong nr nhien va nhan sinh den sir phat trien cua giai
ven bien chau th6 song Hong

9

PGS. PTS. T o n T h a t C h iiu , PGS. PTS.
dat a trung du va dong bang BAc bo

10

t.e

hoa, do thi hoa va 0

42

Sir dung

52

PTS. P h a m T r u n g L u o n g : Dinh HU<1ng phat tri6n du lich vung

60

Thai B ac:

dong bang song Hong
11

GS. L e B a T h d o : Di tlm mot sir hop tac chat che hon gitra dong
bang song Hong va trung du nharn cung phat trien ben viing

69

12

PTS. N g u y in tu « M a n h , PTS. D u o n g N g ( } c T h i: Kinh t~ nong
nghiep va nong thon. vung dong bang song Hong - Nhirng thach
thirc va giai phap thuc day phat trien vung
.

72

13

PGS. PTS. N g u y in K im V ii: D6i moi cong nghe che bien, bao
quan nong san trong su phat tri6n nong nghiep dong bang song
H6ng

77

14

PTS. H a H o c N g o va cong sir: Phat tri6n mo hlnh nong nghiep
da canh tren vung dat iing triing cua dong bang song Hong

81

15

Ap dung cac h¢ thong canh tac tien bo, nang cao hieu qua str
dung dat vung dong bang va trung du BAc bo

88

16

PTS, N g u y in V a n T u d t: MQt s6 van de bao ve thirc vat a dong.
bang song Hong va noi dung can nghien ctru irng dung trong
thai gian toi

'89

17

PGS', PTS, T r d n K h d c T h i: Phat trien rau qua - mot the' manh
cua trung du va dong bang song Hong

93

139


)

yxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHG

TAc OONG
SINH
. . ~ru. NHIEN vA NHAN
~
OEN su. PHAT TRIEN

~
,?
.2.............
--..
CUA DAI VEN BIEN CHAU THO SONG HONG

PTS.ZYXWVUTSRQPONMLKJIHGFEDCBA
T r d n ZYXWVUTSRQPONMLKJIHGFEDCB
D u e T h r;z n h
PTS. T r d n D in h

Ldn

PTS. D in h v a n H u y
Phan vien Hai dirong h9C tai Hai phong.

M onAU
Chau th6 song Hong (Cl'Sll) 1611 thir hai
& Viet Nam, nam & bo Tay vinh Bac bo mot vinh rong, nira kin. Do Hi mot vung dat
tru phu, noi t~p trung 14 trieu dan voi mat
d¢ dan s6 cao nhat mroc. Do vay, dat boi Ian
ra bien hang nam trc thanh tai nguyen q u y
gia. Gan day, sir phat trien cua dai yen bien
CTSH co nhirng bien d6i 1611 bieu hien &
hinh thai, dac diem boi W, xoi 1& va kern
theo la nhfrng tai bien yen bo nhir ngap lut,
va de, xam nhap man .v.v .. Ngoai nhirng
nguyen nhan tien hoa W nhien, nhirng bien
d6i nay con co nguon g6c tir nhirng bien
dong bat thirong ve khi hau, thuy van va d~c

thirong
biet tir hoat dong nhan tac &
nguon va ha hru.

ca

HINH THAI CUA DAI VEN BIEN CTSH.

v oi

dien tich khoang 17 nghln ha, dong
bang CTSH bao gorn cac hop phan co tu6i
Pleixtoxen,
Holoxen som giira va Holoxen
muon. Trong bai viet nay, dai yen bien
CTSH hay CTSH hien dai diroc hieu la b¢
phan tuoi Holoxen muon diroc thanh tao
. trong khoang 3000 nghln nam qua. No co
dien tich 6000 nghln krn", dinh nam phan
Hung Yen, day trai dai khoang 145 km tir
ban dao D6 Son den.Lach Truong (hinh 1).

Dong bang trong de rong 4500 krrr', cao 1 1,5 m so voi rmrc bien trung blnh (MBTB),
voi nhieu de cat W nhien nam xen each
nhau qua cac dai dat triing ( E is m a . D .,
1 9 8 5 , D . V . H u y , 1994). Vung trieu rong
tren 500 krrr', d¢ cao be mat tir mire bien
thap nhat (MBTN) den 1 - 1,2 m/MBTB, be
rong 0,2 - 12 krn (hlnh 2). Bai trieu cao
ro n g 188 krrr', d¢ cao thirong

0,5 - 1
m/MBTB, trong do khoang 70 km2 co thuc
vat ngap man che phu, Bai trieu thap rong
258 km2 phan b6 tir MBTN den MBTB ( T .
D . T h a c h v a n n k , .1996). Cac roi cat tren
vung trieu chiern dien tfch 12 krrr', cao 1 1,5 m/MBTN, rong 500 - 700 m, dai 10 - 15
km chay song song voi duong bo & khoang
giira cac cira song. Cac con cat thirong
churn dau & cac cira song, dien tich 16 km',
thuong cao 2,5 - 3,0 m/MBTN hay 0,5 Im/MBCN (mire bien cao nhat) dai vai ba
km. Cac bai cat bien do song vun tu phan
b6 han che noi song manh, thuong phat
trien tua ke vao than de, dien tich chi 2 krrr'.
Vung ~hau th6 ngam (avant - delta) co dien
tich 1000 krrr', rong 5 - 15 km co ria ngoai
sau 6 - 20 m tuy noi, be mat phu bun bot va
set bot nau hong. Phia ngoai chau th6 ngarn
la d6i tien chau th6 mo rong den d¢ sau 20 30 m, be mat phu bun set nau hong ( N . C.
H 6 i v a n n k , 1 9 9 4 ).

42


1I1NII .: SO 00 lkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA
___
••.
U 1 1 1 0 S U N G II •
"r;;!i:!!= ~ ~ _--~
~I J C"he"·
:~

illlNlI'1lI
tN
.'
_1S~o
ZYXWVUTSRQPONMLKJIHGFEDCBA
= =A::::!r
..
.~ N < }iliON [)~J
~ w --; :-o

43

"


IIlN II 2 : s o

v6

1 I1 N II'm A I V U N O yxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA
TRI'!.lI CIIAlI Tilt, SONG It6 N O 1I1t--NI)~ I

---------

--~ ----.-,...-.-.

1-(:60 dt. 2- II,~'tribt

QQ.

:I· IU i "t\!1I IM p . 4 ! Nl~lIll ~ n !.
~ , I.~ d llri~ u . (,. 1 I1 n 6 iIlllll~tlh.
7 - II" lthi It I ~1.
II. m bi~".
9· OuUoned.~ s,\g 5m. to- 1111:£vSI J\i~

'\~ A f

m~".

.I.

I

Lr
.'

JJ It•." !{, :.'

::\
'

..\

,

,

44

.

ZYXWVUTSRQPONMLK


NHUNG
YEU

D~C

DIEM

CUA DAI VEN

PHAT

TRIEN

CHU

BIEN

CHAU

THO

a

2,5 - 3,5 m/nam
dang bi xoi lo.

SONG HONG.ZYXWVUTSRQPONMLKJIHGFEDCBA B a n g 1: S o s d n h
( m ln d m ) c u a B T C

1 . B o i tu n h a n h ZYXWVUTSRQPONMLKJIHGFEDCBA
n h u n g k h o n g d e 'u r a

p h ia

b ie n , x o i ltY v a e o x u

huang

ta n g

D o a n b if

phia ngoai

b o Van Ly

t6 ( ,: d t) b 6 i tu

va

mo

rong

H IT 0 m o t so d o a n b a .

B d i tr ie u

B d i tr ie u th tip

cao

m anh,

D6 San-

+ 30

+49

cira Thai B1nh
HO'n 50 nam qua, bai trieu cao (BTC)
Cira Thai B1nh
+ 33
+25
m6i nam b6i Ian 386 ha, xoi la 25 ha va can
- Cira Lan
bang boi tu 361 ha ( N . D . O f va n n k , 1 9 9 3 ) .
Ctra Ba Ll;lt
+ 5,7 phfa Bik cira
+48
B6i tu manh a cac cira song 1611nhir Ba Lat,
- 3,5 phia Nam cira
Day tao nen cac cung 16i hoac miii nho ra
3 . S I ! d i e h u y ln d o n g th a i v a e o e h u k y

bien. Toe d¢ b6i tu ngang trung binh cua
e
u
a
c a c n h n n n s o n g v e 'p h ia D o n g B a e v a
BTC 27 m/nam, cue dai 100 m/nam a Ba
TdyN am .
Lat, 120 m/nam a cira Day. Tuy nhien, mot
phan nr chieu dai bolkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA
c rS H bi xoi la voi toc
Day la diem dac bier cua sir phat trien
d¢ trung blnh 6 m/nam. Dac biet, bo Van
dai ven bien diroc th~ hien ro a cira Ba Lat
Ly, Giao Hai bi xoi la tren chieu dai 30 km,
(hinh 3). Trong the ky qua, nhanh chinh cira
tee d¢ cue dai 30 m/nam,
Ba Lat d6i hirong 3 l~n voi chu ky khoang
30 - 40 nam.
Bai trieu thap (BIT) co hlnh thai kern 6n

dinh hon. Chung b6i tu 258 ha, xoi la 61 ha
va can bang boi tu 169 ha m6i nam, Toe d¢
b6i tu ngang BIT 13,5 m/nam, circ dai 60
m/nam a cira Thai Binh.

Cira Ba Lat chuyen ve huong Tay Nam
khoang tnroc nam 1938, ve huong Dong
Bttc trong khoang 1938 - 1971 va ve huong
Tay Nam tir 1971 den nay. Tram tich duoc
boi tu manh hon voi co hat rnin hon a ph fa

cira hirong ve va boi tu cham hon, tham chi
bi xoi la a phia doi dien, Su hinh thanh,
phat trien va tan lui cua cac c6n cat can cira
song co lien quan den huong di chuyen cua
cac nhanh song. Noi chung, cac c6n cat rnoi
thanh tao hoac dang phat tri~n nam
phia
cira song dang lnrong toi. Sau mot th a i gian
nhat dinh, sir phat tri~n cua c6n cat can Ian
dong song dich ve cung huong va ngap lut

Toe d¢ boi tu thang dirng thay d6i theo
rmrc d¢ n6i cao cua M mat bai trieu, khoang
1 - 4 cm/narn khi con thap hon MBTB; 5 20 cm/nam khi cao do tu MBTB den mire
trieu cao mroc kern, .sau do giam xuong
duoi 3 cm/nam khi cao do bai virot rmrc
trieu cao mroc kern.
.
.

a

m o-

2 . B o 'i tu
r o n g b tii tr ie u e a o v a b tii
t r ie u th ti'p k h o n g d e 'u .

a

ven b a se thirong xuyen hon.
mot thai
diem thich hop, thuong \frung voi Iii 1611,
dong chay rat manh se xuyen thung, c6n cat
bi xoi la a phia doi dien va mo ra mot
nhanh song moi con nhanh cti se bi tan lui
hoac dong kin. Mot thai ky phat trien moi
cua cira song lai bttt dau.

Nhu da neu a tren, BTC b6i tu mo rong

a

nhanh gap 1,8 Ian BIT.
nhieu trac dien
ngang, co sir khac biet 1611gifta toe d¢ m a
rong BTC va BIT. Khi BTC mo rong nhanh,
BIT mo rong cham hoac tham chf bi xoi la
va nguoc lai. Tuy nhien, lai nhan thay tfnh
d6ng nhat ve boi tu va xoi la gifra BIT va
vung chau th6 ngam. Duong do sau 5m di
chuyen ve phfa bien 10 - 30 m/nam va chi

45


JllNII3:

so 00 lliNII

TnAI £X)NO L{,t; cui\ BA LI;\T

-------_._lkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA
.. '--'----" - - - - - - - - - - - ,
... ~-

.•

~ ~)l..~.,

:::ri..,1
~ '-? :.i2

•

I

\

x~

~~.~-p~

\

\

l>

J.

:!

·1

\
\
I

/

ZYXWVUTSRQ

I
t

J
I

r

~ ~ ~ ~ '@ 5
9

I

HI

[ .~ -..I
I.'

a

I I to

11

0

I

h

,
,
I

~-::J:'II"
' -'.1-'· 'L:J
16

',:1'

J

:
,
I

I

01.11,'
I

1
I

J

/

,
,,
,
,

I

I

"

I

;
;

I
/

I
I
I

I
I

I

I
r
I
\

------ ------ ~--..•....

.•.

...•..

.~... .-"

/

.

,'- .- •......,,"

•..----.

-.~ ::--------"

-"----

_ .._._-_

- __

1_ COli clt ndi uen tin[\: bi~" cao nhal: a- T/ln Iyi; b- Ph~llri~lI. 2- oSn d.l trong {'hll JlI~1 ITiel! bj
II£~P khi 'ri~u cqong. 3- c6tt cat trollS I'h;1khiii d~u b] ng~r n.we 'ri~1I \;tm . 4- Ulii l~y su vt;l "<11$£1
ph~t lriin 00 d¢tlg 'lfe t;l()'lg.'ri~ vA $1l vet. 5- ll;l.i Iri~u cOO bdi hI nh/) dQng It,tc sMg v~ tri~u: ~
TrtlaulCch dil bQ«~b. T~I!1 !Cd1~l f;/!I. 7. Nl,,,nh S<'Ing I~o do eM y!u x~nlhl!C c:l1n dOllg eMy sOng.
8- cse I~I dm IhlfC Iri~u. 9- Vlid. v~ Ih~lIIl111\.i iliOn ph,1t lrien if b<)cll. 10- 1)1)"f. bdi rfch eung c6p
Ill'!;()ng. * 1- DUng M i Hell dc,x:mr; II- V~ mil:! gi6 00c1{: Uie; b- V~ mil"ll)i6 Tl\y I'Imll. 12<1- Tr:\m
tleh <;1111&
dp llr d l'y ~12b- Tr~lI1fdl rh!ln t~lIlCa IXI. 13- l>bllg bdi cfc::h Idllg ht!P dQC hI). 14· lloollg di
chuyin ln1m lrch kilt IritlJ 1:11(11I&.1SZYXWVUTSRQPONMLKJIHGFEDCBA
- Dt bien qu6c Jin. 16- o.w ..g dAIII\:t.'\u 211I ~ !till.
1 \ . NMllh (:1,(1111
eim sOlI&Inrd>: '!Jl!1; 11. Nhdnh c:hlllh d ill s6ng Wo 1938-1971~ C. Nh~nh ctsrnl1 citn

sOng v~ 197J-1973; l). NMnh chCnh d.ra .slIlIg lit 1973 d~n

46

nAV_

-

"

Dang giap k~ phia Dong B.1c cua CTSH
hien dai bi chuyen hoa tir che d¢ chau th6
sang vimg cira song hinh pheu trong khoang
700 narn qua do bi thieu hut boi tich tren
nen rmrc mroc bien dang cao ( T . D . T h a n h .

Khong chi cira Ba Lat, hien nrong nay
cling dil diroc ghi nhan 0 cac cira khac nhu
Day.v.v ...
tu

4. B6i

ven

b o keo

d a i v e ' p h ia

Tay

va

N am .

n n k , 1 9 9 1 ).

cac nhanh song 100 luon chuyen

5.ZYXWVUTSRQPONMLKJIHGFEDCBA
T r a m . ZYXWVUTSRQPONMLKJIHGFEDCBA
tic h v u n g t r ie u e o x u h u a n g
v~ phia T<1y Nam va Dong B~c,
m in h o n s o v o i q u a k h u .
c6 xu hirong I<1udai dich chuyen
Tram tich lang dong 0 vung trieu chu
Dy
~m
~fu
yeu
tir set toi cat min. N6i chung, chting
va n n k , 1996) do
( E is n z a D .1 9 8 5 .T .D .T h c ; n h
min dan theo cac lap tir diroi len tren mat
dong boi tich tong hop doc bo v6 hirong nay
c.it
bili trieu. Tren mat trac dien ngang,
va do tac dong cua lire Criolit. Do d6, phanlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA
chiing
th o n h a r 0 rmrc MBTN - MBTB, sau
b o phia T<1y Nam cua CTSH, vi du khu virc
d6 min dan theo ca hai phia ra bien va vao
Kim Son ( h in h 4) boi tu nhanh dan' theo th~i
luc
. dia.
. Theo trac dien
.. doc bo chau th6 ,
gian ( T . D . T h r ; n h , 1 9 9 5 ) :
cluing min dan v~ phia T<1yNam.

gan cira
Nam 1970 - 1982: 44m/nam;
song, cluing min hon 0 phia cira song dang
1932 - 1982: 100m/nam;
dich chuyen v~ ( T . D . T h a n h va n n k , 1 9 9 5 ) .
1958 - 1982: 108m/nam;
1982 - 1989: 60m/nam,
C\!Cdai: 120m/nam.
Mac du
d6i huong
c~ung van
~

o

Trong

khi d6, khu
Bdne

V\!C cira song

2·. P h d n

b o 'd o

Bach
h a t c u a tr a m tic h b d i tr ie u ( M d

- m nz)

DO~NBO
Tien LangD6ngBac CTSH

Ba Ll;ltgifra
CTSH

Kim San - Tay
NamCTSH

Tren (tren MBTB)

0,009 - 0,007

0,004 - 0,009

0,0021 - 0,0034

Duai (duoi MBTB)

0,051 - 0,072

0,067 - 0,072

0,035 - 0,059

Tren (dum MBTB)

0,066 - 0,098

0,056 - 0,110

0,046 - 0,068

LOP

V~TRi

B1ii trieu
cao

B1ii trieu
th a p

~

Tram tfch vung trieu c6 xu hirong min
hon qua khir. Th\!C te, tram tfch cat r<1'tph6
bi~n tr~n cac con ~at c6 nam phia trong
dong bang chau tho. Trong khi do, cluing
phan b6 han che 0 cac con cat va bili hien
dai 0 vung trieu.hien
nay. Mot khoi lU<;>TIg
100 tram tfch cat d~ boi tu 0 day va bai boi
yen cac con song c6 de bao 0 mien gitra
ch~u th6 d1i lam thu hep dong chay, gop
phan tang cuong cac tran lil ngap. C6 th~,
mire mroc bien dang cao 0 yen bo la mot
trong nhirng nguyen nhan cua hien nrong
nay.

VAI TRO CUA

cA c YEU T6 TTJ NHIEN

47

,

.

~

.

DOl VOl STJ PHAT TRIEN CUA DAI VEN
BO CHAu THO SONG HONG.
1 . C a c y iu

t6 ' n e n

Dai yen b o CTSH bi..ha chlm 004
- 0 , 15
,
mm/nam trong tan kien tao va 0,04 - 0,1
mm/nam trong thai gian ky D~ Ttr ( N . C a n ,
1989). Mire d¢ ha chlm
ph at trien chau th6 c6 sir
Tuy nhien, ha chlm c6 th~
me xoi 10 neu duoc cong
cao mire bi~n chan tinh

thieu hut boi tich,

nay phu hop voi
den bir tram tich.
tang cuong manh
huang voi nang
trong dieu kien


1I1N1l4: m~N P
.

500

KllU Vt"C

1/

KtM SON (193~-l9g9)

1000n.

,

,

E=IlillllU1lli~":>:x~
~ '':";----I'::-'--'-]
lkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA

'.<>;::: •• _
--..-'. ~'$")('-.!'
._..!~ ~ ...'., "':.~'"
--

I

.

•

.:

.• .

_..!.!...ta

s

_ .!._ ~

•

1- IIIMp. 4- f)u<)lIg nll.R:" "i~n hung hlllh "h 111:11'
nh:!'. v1\o n?tlll 1989.5- VuOllg. lillie biCll (lung blnh •••11.
th:!" uh~ vl\o II!I". 19~1I. Co· DC hie" v~ n !ln l x~y
/

48


bao dat toi toe d¢ 45-50 m/s va mang theo
Luong mira 1.500 mm/nam tren toan hru
a dai yen bien. hau het cac con bao rei vao ky trieu kern.
vue va 1600-2000 mm/nam ZYXWVUTSRQPONMLKJIHGFEDCBA
Mot s6 It con bao trung ky trieu cirong ket
NhietlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA
d o trung blnh nam 23,5°C thich h9P
. h?p voi mroc dang tao nen sir tan pha nang
ch? phat trien thirc vat ngap man tren b'ai
ne.
trieu cao va thuc vat can tren cac con cat.
Vao mila gio Dong Bilc tir thang 10 den
LUll vue h¢ thong song Hong co dien tfch
thang 4 nam sau, gio co t6c d¢ trung blnh 3155 ngan km", trong do 55% dien tich tren
4 tn ls , huang Dong Bac va huang Bilc gan
lanh th6 Trung Qu6c ( L . B . H u y n h , 1 9 9 7 ) .
song song voi bo, voi. tan xuat 70-80%
Tai hrong hang nam cua cluing khoang 114
trong khoang thang 12 va thang 1. Vao mila
krrr' mroc va 114 trieu tffn bdi tfch ( N . V .
g~~ Tay Nam tir thang 5 den thang 9, t6c d¢
P h 6 , 1984). Voi dac di~m phan b6 boi tich
g~o trung blnh 4-5 m/s voi cac huong thinh
10' lirng, bdi tu a yen b a Cl'Sl-l thuan 100ihon
hanh Dong Nam, Nam va Dong. Hang nam,
nhieu a dong bang song Oro Long' (bang 3).
b a chiu anh huang cua 2-5 con bao

deli yenZYXWVUTSRQPONMLKJIHGFEDCBA
xay ra trong khoang thang 6-9. GilS· trb'ng
Bang

3: S o

Song

s d n h . p h d n b ( ) ' tr d m

Tal luong boi tich

1 0 ' lu n g c u a s o n g H o n g

tic k

va

s o n g C ic u L o n g

Ham hrong
bOi tich

Chieu dal bb'
chau the)

Mue de) phan tan
boi tich xa bo

Song H6ng

114 trieu tan/nam

1 kg/rrr'

145 km

12 - 20 km

Song Ciru Long

98 trieu tan/nam

0,2 kg/rrr'

320km

20 - 30 km

Sonneratia caseolaris ph6 bien nhat va chu
yeu phan b6 tren MBTB. Khi bai trieu con
thap diroi MBTB, vai tro tien phong cho bdi
tu thuoc ve cac loai co bien dac biet la co
ng(;1n ( C y p e r u s
~p)
va 'coi
iC y p e r u s

Thuy trieu nhat deu, do 100 cue dai 3 5 4 m ( N g u y ln N g r c T h lf Y , '1984). 'So ~ai ;hai
gian trieu len, thai gian trieu xu6ng dai hon

chut it a ria Dong Bac va gap doi ian a ria
Nam
C6 nghia la, a ria Tay
b6i W thuan loi hon. Dong chay
N.a,m
trieu t6c d¢ trung blnh 20 - 30 cm/s, circ dai
60 cm/s voi trieu xu6ng va 50 cm/s v6i triu
Ie? Dong chay yen b a 25 - 30 cm/s huong
ve phfa Tay Nam ve mila kho va 15 - 20
cm/s hirong ve phfa Dong Bilc vao mila
rmra. Do do, dong boi tfch t6ng h9P d9C bo
h~OOg ve phia Tay Nam. Song huong Dong
Bac thinh hanh vao mila Dong va htrong
Dong Nam thinh hanh vao mila he. Do cao
song trung binh 0,88 m, circ dai 2 m vao
mila ~io Dong Bilc va S m . trong bao
( N g u y e n M a n h llu n g , 1992). Tuy nhien, khi
vao sat b a d¢ cao song chi 0,4 - 0,8 m va
cue dai 2 m.

Tay

crsH

crsn.

Trong s6 116 loai dong vat
day duoc kiern ke, cac loai than mem nhir
dat ( A lo id is la e v is ) , ngao ( M e r e tr ix ) , mong
tay ( S o le n g o u d i) , ngo ( C y c lin a s in e n s is )

.v.v ... co y nghia quan trong cung cap v~t
lieu boi tich. Chung tu t~p voi mat d¢ cao
640 - 2190 ca th~ voi 90 - 220 g sinh khoi
tren moi met vuong. Nhieu noi vo cua
chung chong chat thanh lap, d6ng tren cac
con, bai.
m a la c c e n s is ) .

2 . C a c y lu

d o 'i

va

u ic d lJ n g .

Gan day, c6 nhfrng bien dong bfft thirong
cua mot s6 yeu t6 ur nhien tac dong sau silc
tci phat trien bo cua CTSH.

Thirc vat ngap man va co bien co vai tro
rfft quan trong d6i voi phat trien bo CTSH.
Nho cluing, bai trieu boi tu nhanh hon va bo
6n dinh nhanh hon dum tac dung cua song.
Trong s6 12 loai thuc vat ngap man,
Kandelia candel, Aegiceras comiculatum
va

4· KYHN

t f f b ie n

Cac tran lut da tao nen dong chay rfft
manh lam thay d6i he thong nhanh song va
phan b6 b6i tich 10' hrng a dai yen bien. Cac
tran lut rat 100 xay ra theo chu ky 25 - 30
narn nhu vao cac nam 1945, 1971 va 1996

49


nhirng dot khai hoang IOn nhat co the noi
(L . B . ZYXWVUTSRQPONMLKJIHGFEDCBA
H I/S III/i, lkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA
1 9 9 7 ), n h u n g ca c tra n yxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA
I~Jt co
cac nam 1957 - 1962 va 1968 - 1971
voi quy mo hang ngan ha. Gan day, khai
huang nong nghiep giam di, nhirng quan he
dam nuoi tr6ng thLIYsan lai tang len co tinh
dot bien, vi du khoang 4800 ha trong thai
gian c h i 10 narn (1983 - 1993). Thong ke
cho rhay moi nam co 985 ha BTC, g6m ca
cac biii lay su vet duoc dap de khai hoang
nong nghiep va nuoi trong thuy san, trong
khi chi boi tu 361 ha (1958 - 1994).

Ion tang dang k~. Tai Phil. Lai, so sanh 2
thai ky 1905 - 1960 va 1961 - 1990, cric
tran IIl I ut bao dong cap III tang len tir 7,2

% len 46,6%. S~ gia tang cac tran mua Ion
tap trung vao mot so it ngay ciing la ly do
quan trong gay 1G lut.

V~IO

Dai ven bien Cf'Sl-I chiu anh huang Ion
cua cac can bao di vao vung bo tay vinh mk
BQ, co so luong 2,77 con/nam vao 1911 1965 tang thanh 4,28' con/narn vao thai ky
1954 - 1989. Theo tinh roan, khu vue nay ctr
2 can biio co mot Ian mroc dang trong bao
dat l m, 5 can mot.Itin dat 2 m va cue dai
3 m ( P . V . N iu h \· u III/k , 1 9 9 2 ). Khi mroc
dang trong b a o trung ky trie u cu o n g , m u c
m roc bien co the dang cao 5 - 6 m, tao da
song manh p h a h u y de ke va bien dang b e
sau sac. Su trung hop gifra mroc dang bao va
rrie u cuong co xu h u o n g tang r6 re t, tnroc
day 20 narn, nay khoang 5-10 nam mot Ian.

Do bi he thong de song va de bien bao
dap, dong bang rong Ion phia trong de
khong duoc boi tu tiep tuc va bi bien thanh
cac 0 dat tning, ngay cang thap hon cac
vung dat moi boi ben ngoai. Do y ~ y , dong
bang trong de de bi ngap iing va kho tieu
thoat mroc. Cac con de con ngan dong cac
nhanh song nho gay thieu hut boi tich va
xo i 1 0 b o bien. B o Van Ly - Giao H a i la m o t
vi du, Tren suet chieu dai bo 3Q km dang bi

xoi lo , de ngan da k h o n g cho mot nh.inh
song nao d6 ra. Mat khac, tram tfeh lo lung
lai tap trung a cac cira song Ion, noi boi tu
rat nhanh tao ra nhirng mo phun boi tfch V~IO
vung bien xa. Do vay, tram tfch bi thieu hut
rhirong a ph an giira cua hai cira song 16n.
Tram tich khong duoc cung cap cho dong
bang trong de se tap trung a vung trieu V~I
tao nen toe dQ boi tu nhanh tai day. Them
vao do, he thong de di chuyen c o hoc nhanh
v~ phia bien lam tang nhanh b6i tu Ian bien
oven b o ch a u th6. Ciing do qua trlnh nay
ma BTC b6i tu nhanh h(JJ1h~n BIT dfln den
lam ngan di trac dien bo va tang cirong xoi
1 0 khi n g u o n cung cap b6i tu suy giam. Do
la dieu khac bier .co ban g ifra c rS H co de va
chau th6 song Ciru Long khong de.

Sir dang cao mire nuoc bien lien quan vo i
am len to an cau da duoc ghi nhan a nhieu
noi tren the gioi. Tai tram Hon Dau, MBTB
da nang cao 2,24 m/nam trong thai gian
khoang 30 nam qua ( N . N . T h l.'Y V U III//.;,
1 9 9 6 ). T o e dQ nay co the cao h o n a p h a n
giira bo chau tho, noi hoar dong sut ha kien
t~IO tich cue hon. Co Ie xo i 1 0 mo' ro n g va
manh hon, boi tu cat tfeh cUC a bai boi va
IOI~g song mien gifra chau th6, ngap lut va
nhiern man deu chiu tac dong cua dang cao
mire mroc bien.

HOAT

DONG

NHAN

VA

S IN H

TAc

DONG.

Nhirng hoat d o n g nhan sinh chu ye u tac
dong r6 rang den su phat trien cua dai ven
bien Cl'Sl-l duoc gQP thanh 3 nhom.

2 . X a y d ljp

va dao kenh,

Nhieu con dap da d u o c xay d u n g trong
1. D ap

d e k iw i

hoang

nong

n g h ie p

vue Cl'Sl-l de lam cac ho chira phuc vu
nroi tieu, nuoc sinh hoat va thuy dien. Dap
thuy dien Hoa Binh hien Ion nhat trong h ru
vue, rong 208 krrr', lirong chira 9,45 krrr' va
duoc van hanh tir 1987. Trang nrong lai, dap
San La con IOn h(JJ1, voi dien tich 440 km2
nam a phia thirong luu d~p Hoa Blnh. Cac
ho dap nho ph6 bien a ha h ru , Mac dLI mar
do song ngoi chau th6 1 - 1,5 km/km2 thu9c
10<;licao, mQt so song, kenh dlrQ'c t<;lo nen

va

]UlI

n u o i tr o n g tlllly s d n .

Khoang mot nghln nam qua, de bien lien
tuc duoc quai dap nham ph at trien khai
hoang nong nghiep ( N . K . D W Il, 1 9 6 2 ) .
Theo tai lieu lich sir, nhirng dot khai hoang
Ion diroc tien hanh vao cac narn 1226 ( N h «

1471 va 1773
1835, 1856 ( N / iu

T r U 'lI) ,

(N h a

L e ),

N g lly e ll) .

1827 - 1832,
Tuy

nhien,

50


nho dao hO~ICnao vet cac nhanh da tan d~
Doi voi dao song, song M6i a Hai Phong I~l
phuc vu giao thong hoac nroi tieu,lkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA
n lu r cac
mot VI du. Song nay diroc kh o i dao narn
song Nam Dinh, Duong, song M6i .v.v ....
1934 d~ tao duong giao thong thuy noi song
V[lI1 Dc voi song LUQc va n h o do tau thuyen
Viec dap dap, dao song da g o p phan lam
co th~ tir do ngiroc vao thu do Ha NQi. Sat!
a cac khi dao song, co nhirng bien d6i sau sac v~
thay d6i luu luong mroc va boi tichZYXWVUTSRQPONMLKJIHGFEDCBA
nhanh song cling nhir phan bo b d i tich a yen
cau true he thong chi h ru yen bo khu vue.
bo. Thirc te, tac dong cua cac dap 16n

Song Thai Binh da tirng la song 16n thCr hai
tlurong nguon den dai yen bi~n crSH chua
a Cl Sl-l da bi boi tu lam suy tan bien thanh
duoc danh gia chi tiet va h~ thong. Tuy
mot song nho va hang nghin ha hia thuoc
nhien, co th~ nhan th a y rang, sau khi van
dia phan Tien Lang nam trong khu vue bi de
hanh dap thuy dien Hoa Binh chiern 53% tai
c10~ nhiem man do anh huang cua rnroc
lu o n g ruroc c u a h e thong song Hong, xo i la
rrieu man Ian doc song vao luc dia.
tang len a cira Ba Lat. MQt kh o i hrong Ion
bdi tfch da duoc giii lai a long ho. Bo Bang
3 . P lu i r u n g v a t r 6 n g r u n g .
La (Hai Phon g) bi xoi la 3 5 m/nam
Ca mroc ta co dien tich dat dai 33, 1 trieu
trang 30 narn qua co lien quan den dap song
ha, neu nhu nam 1943 rung chu yeu la tv
Da DQ d~ IflY ruroc uroi tieu va sinh hoat.
nghiern v~ Iinh vue nay. Cac du an trong
rung n o i chung d e u yeu v~ can clr khoa h9C,
chua lam r6 duoc ba van d~ HI trong cay g"i ?
a dau ? va vao Itic nao ?

nhien co dien tich 14,3 trieu ha voi dQ phu
43,2% thi chi can 33,7% va o 1976, 22,7%
vao 1990 va 28, I % va o 1995. Trong do, luu

thirong n g u o n h~ thong song Hong rirng
co dQ phu chi 20% dien tfch. Trong so 8,3

trieu ha rung (1995) rirng trdng chiern 1,05
rrieu ha. Mac du dien tich rung trong tang
nhien thuan le i, Cl'Sll
Nho dieu kien
hang nam nhung can th a p xa so voi dien
16n thtr hai a Viet Nam, hang nam bdi Ian ra
tich nrng dau nguon bi phaZYXWVUTSRQPONMLKJIHGFEDCBA
( N g u y e ll
M a u lt
bien kha nhanh, cue dai toi 120 rn/nam. Tuy
vu e

tv

o dai

yen b o Cl'Sl+, trong so
7000 ha rirng n g a p man, co 4200 ha rirng

Cuoug,

tro n g

/9 9 7 ).

(P .

N.

H O llg

I'd

H.

P.

S U II,

/9 9 3 ).

tv

nhien bi suy giam dien
Rirng ngap man
tich nang ne do khai hoang nong nghiep,
dap dam nuoi, chat cay lay cui .v.v ... Gan
day, co sir can bang giua rung ngap man bi
khai thac va trong moi. Do pha rirng, xoi
man dat thirong nguon tang len va tai h ro n g
phu sa ra bi~n cling tang a mot so nhanh
song ( T . D . T h « lI h . 1 9 9 5 ). Tuy nhien, tac
dong tieu cue 16n n h a t van la van d~ lU lut
tang ca v~ tan xu a t lfin cirong dQ ke t h9P
lam bien d6i bat thirong dia hinh bo, can
bang boi xoi cac cira song.
Rirng ngap man co vai tro cue ky quan
trong doi vci phat trien b a Cl'Sl-l thong qua
bao v~ bo va tang cuong boi tu ( T . D . T h a n h
I'd I I l1 k . /984). Nhirng thiet h<;tiv~ kinh te va

sinh thai do pha rung ng(lp m~n rat 16n. V"i
the, nha nu6c rat quan tam trong ri:rng ng~p
m~n. Tuy nhien, hi~u qua trong rlrng ng~p
m~n can thap do thieu hi~u biet va kinh

51

nhien, thirc chat cua van d~ boi nhanh can
do ca sir di chuyen nhanh cua he thong de ra
phia bien be lai nhirng 0 triing ngay ding
thap phia trang. Gan day, phat trien cua dai
yen bien Cl'Sl-I her sire plurc tap voi nhfrng
bien d6i bat thuong, dot rigor v~ hinh dang
bo va boi tu, xoi lo. Dac biet, xoi la b a tang
ca quy mo va toe dQ. nhirng bien d6i nay la
hau qua ke t hop cua tac dong tv nhien va
nhan sinh. Su gia tang cua bao, nuoc dang
trong bao, mira Ion t~p trung va dang cao
rmrc bien diroc coi la cac yeu to nen tang
cua nhirng bien d6i yen bo. Trang khi do,
tac dong nhan sinh bao gorn quai de, xay
dap dao song, pha rung va trong rirng dJ
dong gop cho nhirng bien d6i sau sac dci
voi phat tri~n bo. Hau her nhirng bien d6i
nay lam phat sinh V~ltang cuong cac tai bien
yen bo, gay thiet hai 16n cho kinh te dan
sinh va lam dao IQn tlnh b~n viing cua cac
chien Iuqc ph<:it tri~n. V i the, chung can
duqc xem xet chi tiet trong cac d V an ph<:it
tri~n va quy ho~ch slr dl,!ng hqp 19 tai

nguyen, bao v~ moi truang yen b a crSH.