KHAO SAT SV* BIEN D O N G DO CAO MAT BIEN TR&N PHAM VI c u e BQ 6 VIET NAM
H O A N G NGQC QUANG Tnrdng D^i hqc Tai nguySn vd Moi tn/dng Ha Ngi Tom tif:
Ti> nhuTig kit qud kfiao sdt va bing phuwig phdp tinh toan phdn tich xu thi biin dgng myv nu&c bien nhiiu nam, ehung toi da thay rdng: toe dS nuoc bien dang t^i cdc tr^m Hai vdn a Viet Nam dao dgng 1,2 - 4,2 mm/ndm tinh theo s6 li$u mifC nwac trung binh nhiiu ndm. Cdc so ti$u ndy cho thdy s^rphu hap ehung vai so li$u quan trdc cOa ve tinh do cao bi m$t biin cOa Dy dn trie d^e GE02TECHDI-S0NG cua Thai Lan - EU.
Tuy mai cht Id bu^jc dau khi dira vdo s6 lieu quan trie muc nudc vdi cdc chudi so li$u CO do ddi khde nhau va chu^ du dai nhung hy vong cdc kit qua ttnh todn do co the ddng gop phdn ndo vdo kit ludn ehung vi tic d0 nif&c biin ddng phia ba Viet Nam la khd cao va dang co xu the gia tdng a giai doan 10 ndm gan ddy.
1. D^t van de gia tdng nhanh myc niroc biin trong khu De ddnh gid sy ndng hay hg xuing cua '^'= ^ i " * ^ '^^' ^" <=^° '""} ' ^ ^ ' . " ^ " 9
trung binh cua myc nu-dc biin toan cau.
Phia biy Tdy vjnh Thai Lan, bdn ddo Malaysia da co cdc tram quan trac myc luc ^ a th6ng qua sy ddng hay njt myc
nu'oc biin can phai co chudi s i li§u quan
trie myc nu-oc ddi, toi hdng chuc ndm trd _
len. NhLrng do! vol Vi0t Nam dbi hdi dd Id r i t nyd'c: Sattahip, Ko SIchang, Ko Mataphon khd khan, boi thyc te nhOng chuii s i ligu vd m$t s6 tr^m khde sCr dung so lieu do do nhu- vgy thuwng rat hiim. Bk khac phuc,
can cd phu-ong phdp XLP ly thich hp'p nhdm khai thac cac chuoi s i lieu quan trac ngdn, khdng lien tgc khi cd sy kit hp'p s i lieu do cao bang v^ tinh.
cao b i mat biin cOa cac ve tinh Topex, Jason vd Envisat.
Cdc s i li$u do dac va s i lieu ve tinh da cho thay: myc nu'oc biin dang cd xu t h i dang cao tren phgm vi todn vjnh Thai Lan vd Vung vjnh Thdi Lan thong qua dy an hop cung chu'a cd xu t h i ha myc nipoc biin tdc Thdi Lan - Cdng dong Chau Au giai doan dyoc phdt hi$n tai cdc khu vyc nghi§n eO'u.
hai, Cdng ngh§ quan trac trac dja xac djnh (Xem bang 1) cac biin dOng mdi tru'O'ng hu'ong toi bao ve
biin cho cdc t h i hO tipong lai (GE02TECDI - SONG) da dira ra mOt s i kit luan ve sy dang cao nhanh myc nif6c bien lien quan d i n hogt dpng kiin tao vd bien doi khi hau (BDKH) trong khu vyc.
Dy dn hp'p tac Thdi Lan - EU da su- dung
Tuy nhien, s i lieu quan trdc myc HLFOC Id lien tgc cdn s i lieu do dp cao b i mgt biin bang ve tinh chi tien hdnh trong cdc tho'i gian ngan nen da cd nhOng sai so nhat djnh.
Mgt khac, trong khoang thd'i gian quan trac va do dac dd cung da c6 tdc dgng cua cac . _ ky hogt dpng cua ENSO, tac ddng cua cac cdc nguin so ligu quan trac myc nu'o'c vo'i y i u to thien van. Do do' cdc k i t qua tren day cdc chudi nhiiu nam lidn tuc kit hop vd'i cua Dy an hpp tdc Thdi Lan - EU can dype quan trdc ngdn dp cao b i mat bien, da kiem tra thdng qua s i ligu quan trdc mye nghien CLPU va cho nhOng k i t lugn v i t i c dp nyd'c biin tai cdc trgm ben bo Viet Nam. Be
N g ^ nhm ba: 28/iaCM16, n g ^ chuyen phSn bien: 0&11C016, n g ^ d i ^ rti^ phEH b i ^ ^
TAP CHi KHOA HOC DO DAC VA BAN B6 SO 31-3/2017
kilm tra, chdng t i l da sd' dgng s l lieu cda edc trgm Phu Qulc, T h i Chu, Con Ddo vd Vung T l u vd thiy ring i) nudrc ta, myc nyd'c biln cung ed xu t h i gia tdng ro rft.
Hidn tyofng myc nydc biln ddng vd nit ddng vai tro cyc kj' quan trpng trong nghien cuu myc nyd'c biln noi Chung vd ttnh todn cdc gid tri cue tn mye nydc ndi ridng. Hien tuyng ndy duyc gdy ra boi nguyen nhdn dia chit vd khi hgu.
Cdc nghidn ciJu cOa Hays vd Pitman, 1973 da cho thiy nhO'ng biln d l i ciia ddy
Biing 1: Toe dg ding cao mifc nurac bien t^i cac tr^m bin ba tay va bac vinh Thai Lan (Ngudn Dw in GE02TECDI - SONG)
dai duong Id nguyen nhan Idm eho my(
nydc biln hg xuong tdi 300 m trang khodnj 80 tridu nam g i n ddy. Dd Id qud trlnh dls kiln tgo dang d i n den qud trinh dang, h?
myc nyde tgi cac khu vyc khde nhau.
Nghidn eCru ciJa Boesh, 1982 eung cho thay d bang Loulsana, Hoa Ky, hi$n tuong nyde biln ddng do eo sy ldn cua ddy biln vdo khoang 1 m trong 1 the ky; trong khi dd d Phan Lan lgi xay ra hidn tyyng nydc biln njt do ed sy ndng Idn eua ddy bien (xem hinh 1).
Tr^m quan t r i e
Sattahip Ko Sichang Ko mattaphon KoLak C5c trgm kh^c
Do d^i quan trac 1942-2004 1993-2009 1940-1999 1993-2009 1964-2004 1993-2009
T 6 C d$ ttang MNB 5.0 + -1.3mm/nam 4.8 + - 0.7mm/nam 4.5 + -1.3mm/nam 5.8 + - 0.8 mm/nam 4.4 + - l.lmm/nam 3.2 + - 0.7mm/nam 3.6 + - 0.7mm/nam 3 - 5 5mm/nam
Ghi chu SL quan trie MN.
SL v$ tinh SL quan ^ c MN SL ve tinh SL quan tracMN SL v# tinh SL v§ «nh SL v§ tinh
Hinh 1: Tr^m mi/c nu(tc vi tuyin do dd cao bi mit bien bing ve tinh thuoc difin GE02TECDI - SONG ven bir Thii Lan vi tr^m quan trie muc nuvc biin cua Vl$t Nam
(hinh vuong)
TAP CHi KHOA HOC 0 0 DAC VA B A N B6 SO 31-3/2017
Tuy nhidn, cdc qud trinh dia chat xay ra r i t ch$m trong khi dd xu t h i biin d i i khi h$u hign nay va trong bfong lai la nguyen nhan o/c kjf quan trpng Idm thay doi myc nydc biin. Cdc nghien ciju cua Lisitzin, 1974, Bamet, 1983, Gomitz et al., 1982, 2002 cdn cho thiy trong t h i ky' vCra qua myc nyd'c bien todn c i u dd dang len khoang 10^15 cm.
Cong bo moi day nhit cua Bidoff et al., 2007, Nicholls et al., 2007, cung cho thay trong giai dogn 1993 - 2003 myc nydc bien dang dyoc ddnh gid thdng qua s i lieu ve tinh vdo khodng 3,1 ± 0,7 mm/nam, cao hon rat nhiiu so vdi gid tn mye nydc biin dang tnjng binh, vao khoang 1,7 ± 0,5 mm/nam va cac k i t qua nghien cdu cua Titus, 1984, Titus et al., 1985 cung d i u eho thdy hien typing myc nydc bien dang xay ra khdng dong deu tgi cac khu vye khac nhau tren t h i gidi.
Do v§y, vigc nghien cdu myc nydc biin can phdi dype cdc nhd khoa hpc no lyc nghien cdu, ndng cao dp tin cgy cua cdc k i t qud ddnh gia vd dy bdo dyoc xu t h i biin d i i cua myc nydc biin trong tyong lai.
2. Phiro'ng phdp tinh todn vd phan tich xu the
Toe dp bien thien theo thdi gian (dang len hoge hg xuong) cua myc nydc dygc xdc ^ n h theo phyong phap phan tich xu t h i (phdn tich trend).
Theo phyong phap ndy, ngydi ta xdc djnh moi lien hg giya myc nyde vd thdi gian dydi dgng mpt phyong trinh hoi quy tuyin tinh :
y = ax + b (1)
CT.
trong do: a=—^r, b^m^-am^,{2)
Z^'
Z-?=v^
(3)Zy> 23".' ^ (4)
2^,r.
(5)
Trong phyong trinh tren h§ s i cd y nghTa la toe dp bien thi^n cua mye nydc trong mot don vj thdi gian. Neu chuii phan tich Id gid tn myc nyde nam, hg s i la toe dp dang len (hay ha xuing) eua myc nydc trong mdt nam. N i u phdn tich myc nydc thdng, he so Id t i e dd ddng len (hay hg xuing) cua myc nydc trong mpt thdng.
Phyong phap phan tich ndy dyoc dp dung d i i vdi cac chuoi myc nydc gid, ngay, thang hoge nam. Doi khi, ngydi ta quan tam tdi xu t h i tdng len hay gidm di eua cae myc nydc cyc tiiu vd cyc dai ndm va phyong phdp ndy eung ed t h i dp dgng de phan tich.
3. Co> sd do lieu m i ^ niFdc phia b a Ddng va l a y Nam Bp Viet Nam
Myc nydc dype do lien tuc bdng cdc logi mdy t y ghi nhy: Stevens A71 (My), SYM (Nga), triiu ky Sutron, triiu ky dp lyc, triiu ky sidu dm; tai cdc tram khdng cd mdy ty ghi dyoc dpc tdng gid mOt thdng qua hg thing thOy chi vd coc... Cdc trgm do 4 lan (obs) m$t ngdy bang mdt thdng qua hg thing thuy chf. Mye nydc biin quan trdc tgi cdc trgm hai van dyoc so vdi so "0" hdi do tgi khu vyc tram; tgi cde tram thijy vdn da dygc quy doi ve cao dp Quic gia (xem bang 2).
4. Ket qua nghien cdu xu t h i dang len cua myc niro'c bien vung bd Dong vd Tdy Nam Bo
Bang 3 la k i t qua tfnh xu t h i ddng len cua mye nydc bien (mm/nam) theo s i lieu
TAP CHi KHOA HOC DO DAC VA BAN B6 SO 31-3/2017
Nghien dhi
Bing 2: Danh sich dc tr^m thu thip so mu mi/c nudc thifc rfo timg gi& vung ba Tiy vi Dong Nam Bo
Tentr^m Vung Tdu Nam can Cdn D^o*
Cd Mau Sdng Doc R9ch Gia Phu Quoc*
T f a d ^ Klnh d9
1 0 7 W 105"01' 106"36' 104"45' 104"49' 105TO' 103"58'
vra9 10'20' 8'45' 8'41' 8'39' SKZ 1 0 W 10"13'
S6 nam quan trac 40 15 37 15 15 40 40
Ghi chu Quan trac tCmg gidr Quan trSc tCrng gi£r Quan trac 4 obs/ngay Quan trac tirng gid"
Quan tr^c tirng gicr Quan trac tirng gi£r Quan trac tirng gicr GW chu: • Mirc nuoc so vdi V hai do; cac tram con lai so ven'0' Quoc gia Bing 3: Tdc dt biin doi (mm/nSm) cue mifc nudc biSn doc bd Ddng va Tiy Nam Bg tinh theo
nguhn so Ii0u din 2008 (Ngudn Hoang Tmng Thinh)
Tram Vung Tau Ptiu Qu6c Rach Gia Nam can Con Dao
Toa do 10"20'N > 107"04'E 10"13'N >103"58'E lO'OO'N .lOS-OS'N 8"46'N >105"01'E 8'4rN .106"36'E
Sd nam quan trac 31 28 31 29 - o
Tinh theo so iifu Trung binh
TBnam 3,0 2,0 3,7 2.3 0.3
Tdi thap min nam -0,8
•0,7 5,7 4,3 -7,3
Tdicao max nam
4,4 5,1 0,1 5,7 6.2 Bdng 4: Toe 6Q bien ddi (mm/nSm) cua muv nu6c bien doc ba Dong va Tdy Nam Bo
theo chudi s6 li§u 2002 - 2012
Vung Tau Phil Quoc Rach Gia Nam can Cdn Dao
T9a do 10"20'N > 107'04'E KyiS'N > 103"58'E 10"00'N >105"05'N
8'46'N .lOS-Ot'E 8"41'N >106'36'E
Nam quan trac 2002 - 2012 2002 - 2012 2002 - 2012 2002 - 2012 2002-2012
Tinh theo so lidu TB nam
3,6 3,2 4,2 3,0 1,2
lUax thang 4,8 5,6 0.1 6,2 6,8 mtrc nu'o'c trung binh nam, muc nudc toi
thap nam va toi cao nam d6i voi cac tram co thoi gian quan trie l<hoang hon 20 nam tro len (xem bing 3).
Toe dp bien doi muc nuoc trung binh tai cac trgm trong i<hu vuc nay rat l<hac nhau ca ve dau. Nguyen nhSn ciJa sur phCrc tap nay CO le 6 chat lugrng so lieu quan trio. Ngoai
ra, l<hong loai tru' kha nang do oao so I<h6ng quy chieu cua thyoc do nu'oc bj thay doi dan do n^n day nang ha t u nhien trong vai chuc nam qua.
Khu vuc ven bien Nam Bo bao gflm ca phia dong nam va tay nam, mi/c nudc bien trung binh co t6c dp d§ng len v^o khoang tCr 0,3 den 3,7 mm/nam giai doan 1980 - 2007
TAP CHl KHOA HOC DO BAC VA B A N O 6 SO 31-3/2017
Nghien aht theo chuii so lieu mye nydc trung binh va tfnh theo gia trj cyc dgi gid tri ndy len tdi 6,2 mm/nam (xem bang 4).
Khu vyc ven bien Nam Bp bao g i m ca phia ddng nam va tay nam tfnh theo bp so lieu myc nydc biin trung binh cd toe dp dang dao dpng trong khoang ti> 1,2 d i n 4,2 mm/nam giai doan 2002 - 2012. T i c dp dang myc nydc bien tinh theo bp s6 lieu cyc dai thang trong nhilu nam gia tri nay len tdi 6,8 mm/ nam. So sanh vdi ket qua tinh toan cua Hoang Trung Thanh vdi chuii s6 lieu td 2007 trd v i trydc cac kit qua tfnh toan dype da oho thiy gia tri t i c dp dang cao myc nydc bien Idn hon theo ca 2 ngudn so lieu dua vao tfnh toan.
Xu the' bie'n thien myc nydc bien dype nhan biet do la do cac k i t qua phan tich myc nydc thyc do thudn tuy. Tuy nhien, xu the' tang hay giam myc nydc con phu thuoc vao nhiiu nguyen nhan trong do co nguyen
nhan dja chd't. Hien nay ehu'ng ta chya co nghien cdu nao v i sy thang giang nen day eua khu vyc ven bd bien Viet Nam. Day la mpt van d i cdn thiet ddi hoi cac nha khoa hpc quan tam nghien cyu tiep theo.
T i e dp dang myc nydc bien rd rang la ngay mpt cao hon the hien qua cac chuoi s i lieu trong 2 giai doan nhy k i t qua phdn tich d tren. Neu chi xet theo cac gia tri myc nydc trung binh nam tai cac tram nhy trong Bang 5 va 6 dydi day ta cung se nhan ra sy gia tang myc nydc bien trong vong 10 nam g i n day (xem bang 5, bang 6).
5. Kit luan
Cac kit qua tfnh toan t i c dp dang myc nydc bien theo cac chudi s i lieu trung binh va cyc dai thang cua hai thdi ky s i lieu 1999-2007 va 2002 - 2012 cho thiy vung bien bd Ddng va Tay Nam Bp co t i c do dang myc nydc bien kha cao. Theo chuoi
Bang 5: Mi/c mrac biSn trung binh (cm) thai ky 1999 - 2007
T r a m
V u n g Tau C a M a u C o n D a o Phu Q u o c T h o C h u
Giai d o a n 1999 - 2 0 0 7 1999
269 33
119 2 0 0 0
270 31
94 2001
270 29
90 2002
267 25
91 2 0 0 3
263 28
93 2 0 0 4
263 25
91 2005 259 24
87 2 0 0 6
264 30
90 2007
264 32
88 TB 265 29 228 93 60
? 6: Mi/c nutyc bien trung binh (cm) thai ky 2008 - 2072
Ti„,..
V u n g Tau C a M a u C o n D a o Phu Q u o c T h o C h u
2008 265 33
91 2009
269 32 248 93 83
Qiai 2 0 1 0
270 33 250 97 84
d o a n 2008 - 2011 269 34 254 99 90
2012 2012
269 33 253 95 88
TB 269
33 251 95 86
Ghi chu*
4 4 23 2 26
Ghi chu ' Gia tn chenh lech mwc nuxyc bien trung binh cua 2 th&i ky 2008 - 2012 va 1999 - 2007
TAP CHi KHOA HOC DO DAC VA BAN DO SO 31-3/2017
Nghiln ctht s6 li^u ddi hgn, cac ket qua tmh todn cOa Hodng Trung Thanh da cho mijc tdng la 3,7mm/n3m doi voi chu6i so li$u trung binh thdng vd 6,2 mm/nam d6i vo'i chuoi s6 li§u cyc dai thdng. Cdc k i t qud tinh todn theo chuoi s6 li$u 2002 - 2012 cOa chOng t6i thi t6c dp dang myc nu6c bien len tdi 4,2 mm/
nam vd'i chuoi so llpu trung binh thdng va 6,8 mm/nam voi chuoi so lieu cyc dai thdng.
Ket qud nghien cu'u dd da chO'ng td rang:
toe dp nydc bien dang ngay cdng cao va cung khd phu hop vdl so lieu tinh todn d phfa bd Thdi Lan nhu cdng bo cua dy an GE02TECDI - SONG: tO- 4,4 -5,0 mm/nam theo s6 li^u myc nudc vd 3,2 - 5,8 mm/nam theo s6 li$u vp tinh. Cd hai ket qua tinh todn cua chiing toi va cOa dy dn GE02TECDI - SONG Id khd phCi hp'p vdi cung mpt ket luan: myc nydc biSn ddng khu vyc vjnh Thai Lan gia tang vdl t6c dp cao.
Cdc ket qud tfnh todn ciia dy dn
GE02TECDI - SONG cung da dyp'C ket hpfp so li$u ve tinh va s6 lipu ve ho?t dpng kiin tao dja ch^t khu vyc. Cac k i t qua tfnh todn t6c dp dang myc nydc bien tai cdc tram quan trac myc nydc cua Viet Nam can dyp'C kilm nghipm vd hipu chinh do dd cao v$ tinh thupc khu vyc bd Viet Nam vd cac k i t qud biln dpng cau true dja chat lien quan d i n qua trlnh ndng - ha cOa khu vg'c ven bd Ddng vd Tdy Nam nydc ta.O
Tai lipu tham khdo
[1]. GE02TECDI - SONG Concept Note, Chulalongkon, 2012.
[2]. Hoang Trung Thdnh (2010), Nghien cyu dpc diem myc nydc biln ven bd Vi^t Nam dya trdn ca sd so lieu thyc do, Lu$n an Tiln sy, Vien Khoa hpc Khf typ'ng Thiiy van vd Mdi trydng.O
Summary
A survey on changes of sea surface height over local area of Viet Nam Hoang Ngoc Quang, University of Mining and Geology
The GE02TECDI - SONG project in cooperation with Thailand and EU about marine surveying concluded that speed of sea level rise (SLR) in Thailand Gulf fluctuated betvieen 3,2-5,8 mm/year which was higher than the speed of mean SLR in the Worid. This paper that initially calculates and analyses the trend of fluctuation in sea level in long time reaches a conclusion that the speed of SLR in which was measured at Vietnam stations fluctuated between 1,2 - 4,2 mm/year based on calculation from mean sea level data This data IS believed to be suitable for data surveying from satellite altimetry in GE02TECDI - SONG project
The result of identification SLR that was measured at Vietnam stations was based initially on short-different surveyed water level. However, this paper contributes to general conclusion about the speed of SLR In Coastal Vietnam that has been high and increased for last 10 years.O
TAP CHl KHOA HOC DO DAC VA B A N 0 6 S6 31-3/2017
