Hdi nghi Khoci hoc vd Cdng nghe bien loiin cpidc hin ihd y
BIEN DONG BON KIEU CUA SONG VEN BIEN VIET NAM TRONG HOLOCEN-HIEN DAI, DU BAO XU T H E DIEN BIEN
Nguven Dich Dv', Doan Dinh Liim', Vii Viin Vinh", Vu Van Ha', Dang Minh Tuan
'Vien Dja chit, Vien Khoa hoc va Cdng nghe Vict Nam
"Lien doan Bdn dd Dia chat Mifin Nam
Tom tiit:
Doc ven biin Vii'l Num cir trung binh khodng 25kin thi cd nmt cira song mur cW Idn, he khdc nhuu vd mirc ild bien dong cua cdc cira song trong Hohn i',"- bien dui ciing khdc nhau
Bien tien Flandrian ldc ddng mgnh den qud trinh bien diing ciia cdc cua se'mg ven hiin Vtcl Nam trong Llulocen- hien dai Cdc cira sdng thai ky Holocen sdm ilea num o ngodi dirong bd bien hien dui, vdo thdi ky Holutcn som- giua cdc cua sdng ven bien liii ddn ve phiu luc dia, vuot qua du6ir^_ 'no bten hen deu; Trong Holocen muon, cue cua sdng lien ra phia bien vu ndm ir vi tri nine ngdy nuy
Bien ddng cdc ciea sdng ven bien Viet Num Irong giai dogn hien dal chn veu Id ce'ic hien lugng xdi Id-bdi tu, ddi ddng. ldp ddng (cira Bdt Xdc) Cdc qua trinh ndy hinh thdnh cdc bar cat, con cat., tgo nen cdc kieu ciea song loin, phdng, loi hoiic cira song della hinh md chim, ciea song della hinh quat. cira song della hinh chdn chim, ciea sdng estuary
THE CHANGES OF RIVER MOUTH BASIN IN COASTAL AREA OE VIETNAM DURING THE HOLOCENE-RECENT, FORCAST OF THE CHANGING TREND
Nguven Dich Dy, Doan Dinh Lam, Vu Van Vinh, Vu Van Ha, Dang Minh Tuan Abstract:
At an average of 25km along coasted urea, there will be a river moiintl. with ebffrenl sizes und differeni variable levels in Holocene -present.
Dunng the Holocene -present river mouths in coasted area of l''/(.7A'•; ' had been effected and changed strongly by Flandrian Ireinsgesstcm. In •'urly Holocene. river mouths were located out fur from ofthe present shore and
fiiu ban Dtu h. Dia chdl vd Put veil ly Bien
moved toward to the mainland in early- middle Holocene In the late Holocene. the river mouth moved gradually to the sea.
These main variations of river mouth are erosion — deposilon of river bank, change in flow, filling the channels 'These changes resulted in formation of sand bar und sand bank .. that make the different types of river mouth .such as sunken, plane, convex, hird'sbeok. sector, bird's leg, estuary
M O D A L
Viing cira sdng la ddi tugng dia ly tu nhicn dac bict, cd cau triic phire lap, la noi ddng song chay ra bifin; Nai xay ra qua trinh chu>en hda dan tir che dp thiiy van luc dja sang ch^ dp thil) viin biiin, Cung tai ddy xay ra nhii-ng dien bien cd tinh chit ly hda, tinh chit sinh hpe cung nhu qua irinh hinh thanh ehau thd. Nghien eiiu bicn ddng viing cira sdng Viet Nam tiong Holoeen- bien dai va du bao xu the dien bien la mdt hirdng nghien ciiu hien nay cd tinh khoa bgc va thuc tien phuc vu cho su phat trien kinh lc- xa hpi vimg ven bien. Trong edng trinh ndy trinh bay nipt cdch khai quat ve sir bien dpng ciia bon dang cii'a song va dir bdo xu thfi dicn bien viing ven bifin Vict Nam.
I. HILN DONG UON DANG CIJA SONG VEN BIEN VIET NAM TUONG H O L O C E N - H I E N DAI
1. Nhung nliiln to tac dong
Cac tae nhan gay nen bicn ddng vimg cira song ndi rieng va bd bien ndi chung cd mdi lien quan hiru ca vdi nhau, tuang tac qua lai lan nhau trong he thdng nhat tuan theo quy luat lu nhien va ehiu su chi phoi eiia con ngudi nham thiet lap nen su can bang dgng giua chiing. Cac tac nhan dd bao gdm: Nhan td ndi sinh, ngoai sinh, nlian sinh hay la hoat ddng ciia con ngudi.
- Cac nhan td npi sinh bao gdm nban td nhu' eac thanh tao tram ticb, eau true dja chat, dia mao \'d boat ddng tan kicn lao va dia dpng luc hien dai
_ -Nhiin Id ngoai sinh gdm. cac qud trinh hoat dpng ciia song, ddng chay sdng, dong sa ooi ven bd vimg eira sdng, ddng chay sdng-bifin, ddng biin cat; gid (bao, gid miia va cac dang thdi ticl dac bict); muc nude, tbiiy tneu va tinh chat eo ly eua eae thanh tao viing cira song.
- Nhan id nhan sinh la cac boat ddng ciia con ngudi bao gdm cae cdng trinh Ihiiy loi.
dan sinh. kmh lc, khai thac khoang san. \'at lifiu xay dung; trdng \d pha rirng ngap man d VLing cira sdng,
2. Quii trinh hien dpng
2.1. Khdi quid bien dgng cita song Viet Nam trong thiri ky Holocen
Nghifin ciru bifin ddng hinh thai viing cii'a sdng ven bifin dugc lien hanh phan lieh, giai uoan anh mii\' bay, anh ve linb nhicu tbdi ky ccing vdi ket qua thu dugc qua vice khao .sat tigoai Ihuc lfi lai cdc vimg eira sdng cV Vicl Nam. Bifin ddng dja hinh viing cira sdng ven
Hot nghi Khua hoc vd Cdng nghe hidn loim gnd, /.hi ihir y
bifin la kfit qua tuong tae eua cac qua trinh ndi sinh, ngoai sinh va nhan sinh. I ifiii chifiu dai gin 3.254kni bd bifin tinh trung binh cir khoang 25km lai cd nic)t eiia sdnc lire c6 khodng 130 cira sdng. nhung sd cira sdng co tfin. cd gia tri khai thac thi vao kho.'mg 89 cira, phiin bd theo cac viing. mien nhu trong bang 1.
Bdng 1: Bang thdng ki phdn bd cdc cua sdng theo cdc vimg. mien J 'ii. '' uu;
Viing mien
1 Bac bd
"frung bp Nam Be) Cli nu'O'c
Cac cira sdng Ch
Vict Nam
cu dai b(V bicn Chicu llai btf bicn So cii-a siinji chinh (km) t r i n lOOOkm' do ra liitn
515 [ 4,4 : l.v • 1827 ' I3.(! 4'i 912 12.5 2'' "
3254 i 9,9 1 H'i (Lirong Phmrng Hdi. '.'I05}(4]
)lian bo d Bac Bo va Nam Bg deu co 2 he Ihong suii,_ lian nhu ddi xii'ng lu nhifin:
- He thong sdng dang estuary dd vao cac \'inh niia kin: C) Bac Bd dd la he mong sdng dd ra sdng Baeh Dang (cira Nam Trieu), 0 Nam Bd dd la he thdng dd \'ao vinh "^diih Rai (cira sdng Nga Bay)
-1 Ifi thdng sdng dang della tao ra cac chau thd ldn: C) Bac Bp dd la he thong Song Hdng. O Nam Bp dd la he thdng sdng Ciru Long.
_ Hai he thdng sdng nay dfiu dd ra vimg bien ed thuy trifiu cao, chenh leeh \ap xi 4ni, a Bac Bd die dp nhat trieu, d Nam Bp cd chfi do ban nhat iricu [8].
O Mien Trung \di eae sdng ngan tir vimg nui eao dd xudng vimg bicn. cd [• icu thap, quanli nam sdng ldn [8].
Cae cira song \en bien d Viet Nam trong thdi ky Holoeen dfiu chiu anh hudng bicn dpng cua dgt bien tifin Frandrian bat dau tir 18.000 nam cho dfin nay tren pham vi loan ciu Vao thdi dicm hau het cua sdng ven bifin bien nay dfiu dfi lai cac diu in d - •.mg ihcm lue dia (Holocen sdm- II .70p nam - 8000 nam BP); Vao khoang 8000 nam di-r. -lOOO nam BP eac cira sdng ven bien lien dan vao Iuc dja vdi bicn tifin cue dai 1 lolocen giiia Dau an ciia do! bien lien nay cd the lim thiy trong cac thanh tao trim tieh nguon gde >^;. n d Moc Hda (Long An), Cdng Chanb (Hai Duong).., 'frong Holocen nhiing bifin dbn\: la. da dang nhu dia hinh. \di Id bdi lu. bifin ddi Idng sdng. .
L2.2. Bien dentg cdc cfra sdng thoi ky hien dcd
Trong so 130 cira sdng cd ten va khdng cd tfin trong khudn khd bai bao na^ khong the trinh hd\' hei cae kieu cira sdng ven bien cung nhu su bifin dgng ciia chiing o nude la. Do dd lap the taenia da lua chgn 4 dang cira sdng la: Cira sdng hinh pheu- Cir.' ^am Trieu (sdng Bach Ddng); cira sdng delta- Cira Ba Lat^Sdng Hong); Cira song cha\ qua dim pha ra bien- Cua fhuan An (song Huong); Cira sdng luang tinh- Cira Dinh An'(.sd>.;_' Hau). 0
\ fieu bun Dm Iv^Diu c lie'ii vd Dut vui ly Bien
• day Is"*' '^^'•*^ ^' '^'^' trmh bd\ sir bifin dc)ng cua sdng Dinh An trong llidi k\ I loloeen- 1 lien
\ dai. sir bifin di)iig dd nam irong phdng ehung eua 9 cua sdng chau llid sdng Cuu Long.
rira song hinh nlicu - Cuu Nam rrieu (N»nu Hach Dang) nam trong vjnh bifin nua kin trong \ inh I lai Phdng. ikly la cua sdng kifiu estuary. Bifin de)ng eua Nam "frieu eiing nhu cde cua sdng irong vmh bifin nua kin ndy cd hifin tucrng phd bifin la bdi lap da\ ludng va xdi la bd. dao sau clu mang tinh cue be), khdng dn dmh \ a thay ddi \j iri bai bdi cira song. Cir^i ^I'^iiJ^ ^^'11 bifin Nam frieu co xu the ndng ddn, qud irinh bdi lap ngay mdt lang.
Cac doi edl o hai bfin cira sdng Nam 'frifiu phdl Iricn ca chieu ngang veil ehifiu dai iheo hudng ddng nam. Cua Nam I rieu bifin ddi hinh thdi ngodi hicu img udn khiic cdn cd hifiu ling tdch dong.
Ciia sdnu delta - Cua Ba Lat (Sun''; Hiinii) la eua delta difin hinh o nire'rc la, bifin ddng cira sdiie lu nam 1939 dfin na> qua 4 giai doan Ddng chinh Sdng Ildng dd ra bifin iheo liircing ld> biic ddng nam. Cua sdng duefc keo dai do su phdl infiii cua bai bdi cV hai bfin.
Dai cai ngdm a cua lifip luc phdt trifin Ihdnh edn. nhd Ifin khdi muc nuirc trifiu kifit. ddng thdi cac cdn cai hai phia tifip Uie kin la, ddng chinh bj thu bep. Bai ngdm ehan cua nhd len khoi mat nude irifiu irung binb. ddng chinh Sdng Hdng chu\eii luicing: Qua cac eon lii 1971. 1973 dd nnv re)ng lach cai dfi ddng chinh Sdng Hdng cha; ra bifin nlur eii mcr diu mpt thdi k\' phdl lilcn nieil |7f
Cu'ii .soniz ch;iv quii dam pha - Cti'ii Thuiin .An (.scing Hunng) la nic)l cua sdng difin hinh cho loai cua sdiig mien frung o nude ta. Id cua co lue>i cat hinh edng eua. cua sdng chay qua ddm pha Irireic khi dd ra bifin, Cira nam tiong \ ung bifin cd chfi dc) trifiu dac bicl.
Ciifi dp tneu ban nbdt deu. bifin dp trifiu rat be. Cua Ihuan An nam trong vimg cd nhicu bao dd be), gid miia ddng bac \'a lay nam hoai dcing kha manh. Lich sir bifin ddng cira sdng da chinig kicn nliifiu trdn lu quel kinh hodng. gan ddy nhat la cern ICi thdng 11 nam 1999.
Nam 1404. ei khu \'iie 'fhuan An. cira bien duerc mo Ian dau tien lai ldng Hda Dudn gpi Id cira Hda Dudn (ciia Eo. eua Nbu\cn). Lich sir bifin ddng cac cira 'fhuan An \ a cira I kia Duan' Cira Hda Duan ldn lai irong vdng 5 the ky (1404-1904); cira fhuan An Id cira duy nhat lu nam 1904 cho dfin nay. Thdng 11/1999 cua Hda Duan dugc mei. khi dd ldn tai hai ctra bifin. nam 2000 ticn bdnh lap eiia Ilda Duan. cd thfi ndi rang bifin di)ng eua sdng Thudn ,'\n hay 1 Ida Duan ldm djch ehuj'en tuyfin ludng chinb nam trong hinh cang cua. cdc hudng. (uyen. ludng theo hucing ddng bac thucmg xuat hifin vao nhung nam cd lu hoac bao ldn I u\'fiii ludng iheo hudng lay bac thudng xudt hifin vao nhung nam nuoc thdp. 'Irong con lu Ihdng 11/1999 dan dfin bifin ddng hinh thai vimg cira 'fhuan An va lan can nhu trpc thiing doi edl vd md thfim eira mdi ra bien (cua I Ida Dudn) ldm bien ddi eira Thudn An nhu viec phan bd bdi xdi. dicu chinh lai duimg bd bien.
C ira sdnu linintz linh - (Tia Dinh An (sonu llati) la mdi trong 3 cira sdng ven bien kin nhdi lluieic sdng Ildu. ddy la cira ludng linh co nghTa la ed yeu id estuary va delta, Bifiii dpng cua sdng Djnh An duerc nghifin ciru nidi each chi lifil dudi cac gdc do: bdi tu xdi lo od. difin the eira sdng. bien ddng cira sdng. vimg \'en bicn cira sdng \'a thiiy thach dc)iig lire viing cu-a sdng |5f
HOI nghi Khaa luic m Cong nglie hien IMn rmj. lij„,i,^y
-'-•iECrE.i
Hinh I: Ban do litang da - cd dia ly thai ky ddu Holocen .s&m [3]
Qua hinh 1, cac cua song trong do co ciia Djnh An thoi ky Holocen som dSu nSra 6 ngoai diroTig bo bien hien dai, co the niim d phJn chau th6 ngim.
,Jja» f ^ '""!! ""X^""^' ''""• ^^ ' ^ '''^" ' ' ' " S '"^'^ ''»"8 ^ i s6"g d'cn hinh o Viet Nan.
trong Holocen- hien dai qua tien trinh bien tien Holocen va cac biSn dong hicn dai. Duii day lay thi du, trmh bay su bien dong cua cfa Djnh An thong qua cac ban di. mong da co
Tiiu ban Dia li', Dia chdt vd Dig val ly Bien
^ia ly de minh churng bien ddng ciia eua song ven bien vung chau thd song Cuu Long theo cac then ky Holocen sdm; Holocen giiia-mugn va Holocen mugn (hinh 1; hinh 2; hinh 3).
Hinb 2: Bdn do luang dd - cd dia ly thai ky cuoi Holocen .sdm - ddu Holocen giUa f3]
Theo hinh 2, cac ciia song trong dd cd cira Dinh An ven bien vao thdi ky dd lui dan ve phia luc dja vugt qua dudng bd bien hien dai.
Ildl light Khou hen vu Cdng nghe hidn loan qiiJK hh, ihu y
Hinh 3: Bdn do tuang da - cd dia ly thai ky Holocen mudn f3]
Hinh 3, cac ctra sdng ven bien ke ca cira Djnh An trong Holoeen mudn ddi. dan lui ra khoi luc dja, lien tdi dudng bd bien hien dai.
II. DU BAO XL T H E DIEN BIEN B O N D . \ \ C ; ( IJ A S 6 N ( ; \ EN BIEN V H T NAM Co sd khoa hge cho \icc du bao xu the dicn bicn eac cira sdng vcn bicn -' ^ ^ ^ phan tich cac tac nhan gay nen bdi tu, xdi Id nhu ngi sinh, ngoai sinh va nhan ^mb, ^an"
gia hicn trang va xu the dien bien: Tim hicu nguyen nhan bdi tu va xdi lo. t ac -hdn to not
fiiu ban Diu lv. Dig chdl vu Dia vdt ly Bten
sinh it b'£" dpng trong khoang thdi gian qua ngan so vdi thdi gian dja chat. Cac nhan td ngoai sinh bicn dcing manh khdng chi d viing cira sdng ma cdn d phan thugng ngudn.
I>jhan to eon ngirdi boat dgng tren eae luu vuc song, khu bd bifin nhu dap dap, nudi trdng tjiuy san. Mat khac, muc nude bicn dang do bicn ddi khi hau. Ddi lugng cua du bao la vung eac cira sdng lifin quan tdi duimg bd bien, qua trinh bdi tu va xdi Id lien quan tdi bien d6ng muc nude bien. 'finh chat ciia du bao: vice du bao theo chu ky hay khdng theo chu ky, du bao ngan hoac dai. Cae phuang phap du bao: du bao theo kieh bdn, du bao theo anh vien tham.
Du bao xu the difin bien theo kjch ban nude bicn dang trong tuong lai: Cac kjch ban nude dang d Viet nam dugc tinh loan theo kich ban phai thai thap nhat (Bl), kieh ban phdt thai trung binh (B2) va kieh ban pbat thai cao nhat (AlFI). Theo do, dfin cudi thfi ky 21 muc nude dang them 75 dfin lOOcni so vdi thdi ky 1980-1999. (bang 2).
Bdng 2- Muc nuirc bii^n ddng (cm) so vdi thai ky 19H0 -1999
Kjch biin
Tiiap(Bi) Trung binh (B2) Cao (AlFI)
Cac moc thoi gian ciia the ky 21 2020
II 12 12
2030 17 17 17
20-10 23
T ^
24 2050
28 30 33
2060 35 37 44
2070 42 46 57
2080 50 54 71
2090 57 64 86
2100 65 75 100 Nguon. kich bdn bien ddi khi lulu, mrae bien ddng cho Viet Nam. Bd TNMT, 6/2009 f Ket qua tinh loan:
+ Mue nude dang 65cni, thi dicn tich ngap la 5.133km (chiem 12,8% dien tieh loan DBSCL).
+ Muc nude dang 75em, dien tieh ngap 7.580 km^ (chifim 19% dien tich DBSCL).
+ Muc nude bien dang 100cm. dicn tich ngap 15.116 km^ (chimin 37,8% dicn tich DBSCL)
Theo tinh toan nay, khi mirc nude bien dang lOOem. thi -2/3 dicn tich dien tich duyen n3i tir Sdc Trang den 'fien Giang ngap dudi nude.
T6m lai: Viec du bao xu the dicn bien bdn dang eira sdng ven bicn Viet Nam ndi rieng va cac ciia sdng ven bicn Vict Nam ndi chung lioan toan phu thupc vao su bien ddi khi hau
^ va hien tuong nude bien dang. He luv eiia vice bien ddi khi hau va nude bien dang dan tdi f '"limg thiet hai d cac viing eiia sdng \en bien va nipt phan dien ticb thudc cac ddng bang -Ven bifin ddc biet d ddng bang ehau ihd Sdng Hdng va sdng Ciru Long. Nha nude ta eiing VOl cac qudc gia tren the gid. se cung chung tay de eo the giam thieu nhirng tdn that vfi igiroi va cua
Hot nghi Khoa hgc vd Cong nghe bten loim qude lim lhu C
KET LDAN
Vcn bifin Vifit Nam cir khoang 25km tlii cd mgt cira sdng muc do jdn, be: khac nhau, mirc dp bifin ddng hong Holocen- hien dai khac nliau, eho phep rut ra eae kfit luan dudi dix
- Cdc cira sdng ven bifin Viet Nam ndi chung va bdn dang eira sdng ndi rifing trong Holocen- hien dai, kfi tir 11.700 nam BP da bicn ddng tuan Ihii theo tien trinh phdt irifin ciia biSn tifin Flandrian. Cae cira sdng thdi ky Holoeen sdm deu ndm d ngoai dudng bo bifin hifin dai. vao thdi ky flolocen sdm- giira cae cii'a sdng ven bifin liii dan xc phii, luc dja vugt qua dudng bd bifin hien dai; Cdc cira sdng vcn bien trong Holocen mudn thi ddn ddn liii ra khdi phdn luc dia tifin ldi dudng bd bien hien dai.
Bicn ddng cac ciia sdng ven bicn Viet Nam ndi ehung va bdn dang cua '--dng noi rieng bifin dai cbii yfiu la eac hien tupng xdi Id-bdi lu, ddi ddng, lap ddng (cira H.it Xdc), hinh ihanh eae bar, cdn cat... tao nen cac kifiu cira sdng lom, phang, ldi hoac i ua sdng delta hinh md chim, cira sdng delta hinh quat, cira sdng delta hinh ehan chim ':iia song estuarv
TAI LIKU TIIAM KIIAO
1. Baidin S S, 1971. Cdc giai doan phat trien viing cira sdng. Matskva (ban tifing -^ga).
2. Nguyfin Van Cu va nnk, 1988. Kcl qua budc dau nghien ciru ddng luc cac vimg cira sdng thudc he thdng Sdng Hdng. sdng Thai Binh. Bao eao Khoa hpc tai bdi nghj dia ly loan qudc. Ha Npi.
3. Nguyfin Djeh Dy va nnk, 2010. Nghien cii'u bifin ddng cii'a sdng va mdi truciiiy iram tich flolocen- hifin dai viing ven bifin chau thd sdng Cii'u Long, phue vu pbat trifin hfin virng.
Chuong trinh Khoa hgc Cdng nghe cap Nha nude, KC09.06/06-10. Ha Ndi 4. Lirong Phuong Hau, 2005. Ddng lire hge va edng trinh eira sdng. Nha xual ban Xay
dung, Ha Npi,
5. I loa Manh I Iimg. 2003. Danh gia tinh hinh bifin dpng vimg cua sdng vcn bifin Djnh An qua cdc tu lieu vicn tham, HaNpi,
6. Vii Van Pbai. 1988. Hinh thai eae cii'a sdng ven bifin ddng bang BSe Bp. Tap ehi khoa hpe dja ly. Trudng Dai hgc Tdng hgp Ha Ngi.
7. N'guyfin Ba Quy. 1994. Mdt sd vdn dfi dien bifin viing cira song dudi anh liudng cua trifiu va lu Luan an 'fien sy Dai hgc "fhuy Lgi. Ha Npi
8. Nguyen Nggc Thuy \'d nnk, 1998. 'fhiiy trifiu trong cac cua sdng viing vcn bien Viet Nam. fla Ndi.