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CHE DO THUY THACH DONG LlTC KHU VlTC CU'A SONG, VEN BIEN VUNG DONG BANG S 6 N G C U U LONG
Le Thanh Chvcrng, Tran B& HoSing Vi$n Khoa hpc Thuy led Mien Nam Tom tat: Bdi bdo ndy trinh bay kit qud nghiin dm ddnh gid chi dp thuy, thgch dpng Itfc khu vuc cica sdng. ven biin viing Ddng Bdng Sdng Cuu Long. Cdc mo hinh todn ID (MIKEll) vd 2D (MIKE21 Coupled FM) vai ti le chi tiit khdc nhau dugc su dung di md phdng chi dp thuy dpng luc, van chuyin biin cdt, vd diin biin hinh thdi trong mpt ndm khi hgu (tic 5/2009 - 4/2010) trong diiu ki$n hien tgi. Kit qud nghien cuu cho thdy khu vuc cica song ven biin vimg Ddng Bdng Sdng Cihi Long chiu tdc dpng cda chi dp gidmua do Id thdi ky gid mua Tdy Nam day cUng Id miia la vd gid miia Dong Bdc day cUng chinh la mua kho. Trong thai ky gid miia Tdy Nam vimg cica sdng, ven biin phia biin Ddng xu thi bdi ty Id chu yiu, hi^n tupmg xdi Id it xdy ra. Hi$n tupng xdi la khu vuc ndy bdt ddu vdo thai ky gid miia Ddng Bdc. Dieu ndy thi nguac Igi ddi vai viing cica sdng ven bien phia hien Tdy.
Tie khoa: Chi dp thuy thgch dpng Iffc hpc viing Ddng bdng song Cuu Long, nghiin ciiu ve chi ^ thuy thgch dpng Iicc hpc DBSCL bdng md hinh todn, diin biin hinh thdi viing ven biin BBSCL Summaty: This paper presents the results of hydrodynamics and morphology in the estuary and coastal areas of the Mekong Delta. The ID (MIKEll) and 2D (MIKE21 Coupled FM) models are used to simulate hydrodynamics, sediment transport, and morphological changes in a climate year from May 2009 to April 2010 under current conditions. Analytical results show that the areas are affected by monsoon seasons namely the southwest (from May to October) coinsiding with the rainy season and the northeast (from November to April next year) coinsiding with dry season. During the southwest monsoon, the area of the East Sea experienced dominantly accretion and erosion occured less frequently. The erosion of the area began in the northeast monsoon. This is opposite for the area'of West Sea.
l . M d D A u (DBSCL) CO d§c dilm song ngoi dciy dac, Trong nhihig nam g5n day, vSn d l xoi 16 hb ^ " ^ E ^^ ^f" •'^o dai tfr Dong sang T^y. Do b i k diin biln ngay m^t phtrc t^p, gSy anh ^ ° ' ^'^^ ^'^^J ^inh thai ducmg b6 d khu w c hucmg khong nho din dai s6ng nhan dSn ciing ^ ^ *^»^" ^^^f "^^ Ph'^<= tap gay anh hudng nhu tac dOng din sy phat triln kinh t l xa hoi ^ ° " g ^ ^ *^^^ ^^ s ^ ' ^^"^ "^?"8 <^^ ^ ^ " ^ ciia cac dia phuong ven biln. VSn dl nghiem * ^ ^^ng khu vuc. Da eo nhieu nghien cim trpng n^y hi^n dang thu hiit sv quan tam dac ^ ^ ^ ^ ^^ cl»« ^^ ^^y t*^'^^ <*^ng luc hpc cdc cdp lanh dao cung nhu cdc nhJl khoa hpc ^ ^ ^<= b ? *>;™ DBSCL, dang chu y trong so trong va ngoai nude. ^^ P * ^ ^^ ^^^ ^ , " ^ ^ g ^^t qua nghien ciiu . „ , , , . . . biln dpng cua chi do thiiy thach dong luc Nhu Chung ta biet, Dong bang song Curu Long ^ ^ ^ ^ ^^^ ^^„ ^ ^ y „ ^ j ^ „ g ^ D„
an de bien Vung Tau - Go Cong [5,6,7], Tuy Ngay nh?n bai: 6/7/2017 ^ | „ pjiam vi nghien cilu trong nhOng d6 tai, Ngay thong qua phta bien: 11/9/2017 ^ ^ ^ j . ^ j „ ^h„^ ^ „ g va chi t4p trung Ngay duy^t dSng; 26/9/2017 v j
10 TAP CH( KHOA HQC VA C O N G NGHf T H O Y L(?I S(5 40 - 2017
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KHOA HOCa vimg cua song ven biln, do do chua thi hipn duprc tmh chdt phiic t^tp cua ehl do thuy thgch dpng luc hpc viing DBSCL. Trong nghien cuu nay ph£im vi mo phdng dupe ma rpng voi m\ic dich phan tich ddy du hem chi dp thiiy t h ^ h dpng luc hpc viing DBSCL. Tir do co thi d l xudt dupe giai phap ch6ng xoi la phii hpp vdi viing tu TP. H6 Chi Minh din Kien Giang Bai bao nay trinh bay m0t s6 kit qua nghien cuu
ddnh gia chi dO thuy thach dOng luc vimg cua s6ng, ven bien viing D6ng BSng S6r^ Cuu Long.
2. PHirONG PHAP NGHIEN ClTU Hinh O.I minh hpa each tilp c|n chung trong viee nghien che dp thiiy dpng l\rc vung cua sfing, ven bien vung D6ng BSng Song Cuu Long, trong do cae mo hinh v6i ti 1§ va mure do chi tiet khac nhau duac thilt l|p.
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Hinh 0.1. Cdc md hinh sic dung Mo hinh 1 la m6 hinh thiiy dpng luc vimg cho
toan bp biln Dong va bien Tay. M6 hinh sit dving cho viing nghien cihi nay la MIKE 21 Coupled FM vdi cac module HD (thuy dpng luc), SW (phd sdng). Muc dich ciia mo hinh I la md phdng chi dO ddng chay (thiiy trilu, ddng chay ven bd) va chS dp sdng nhdm cung cdp bien md phia biln cho cac mo hinh vdi pham vi nhd hon (nhdm md hinh 2).
Nhdm mo hinh 2 bao gom cac mo hinh: (i) ID cho he thdng sdng k6nh Mekong va Sai Gdn - Dong Nai, va (ii) 2D cho vimg nghien curu md rpng phia biln tir bien Cambodia den Phan Thiet. Hai logi md hinh nay se thuc hien cac md phdng ddc l^p (MIKE I I , MIKE2I) hoac duac ndi kit vdi nhau (MIKE FLOOD) tuy
theo timg myc dich khac nhau. M6 hinh MIKE FLOOD (MIKE 1I/MIKE2I Coupled vai cac module HD) duac sit dung dh nghien cuu chi dp thuy dpng lire vimg cura song ven biln. Kit qua ciia md hinh nay se dupe su dyng dl trich xuat bien thuy I\rc cho cac md hinh van chuyen biin cat va dien biln hinh thai ID (cho h? thong sdng chfnh phia thuong ngudn) va 2D (cho vimg cua song, ven bien) dpc Igp. Md hinh ID dpc lap duac su: dyng d l cung cdp bien dau vao cho md hinh nghien cijru md rpng 2D, mo hinh se chi gdm cae sdng kSnh chinh.
Md hinh 2D dpc lap dupe dimg d l nghi6n cuu ehe dp thuy thach dpng luc len vimg ciia sdng ven bien tren pham vi rdng trai dai tir Ba Ria - Viing Tau din Campuchia,. Ddi vdi cac md
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hinh ID dpc l|p, cdc module dupe sii dyng se la MIKE 11 HD, AD. D6i vdi md Wnh 2D d$c mp, cdc module sii dyng sS Ik MIKE 21 FM HD,SWvdMT.
Cac md hinh trSn da dugc thiet I§p, hi$u chinh v i kilm dinh trong cdc nghifin ciiu trudc ciing nhu trong khudn kh6 d l tai cdp bp "Nghien cihi gidi phdp cdng ngh$ chdng xdi Id bd biin, cua sdng phii hpp vung tic Tp.
Hd Chi Minh din Kien Giang " do Vi?n Khoa hpc Thdy Ipi miln Nam thyc hifn. Bdi bao nay chi trinh bdy cdc ket qud chinh trong vi^c ling dyng cdc md hinh trSn de ddnh gid che dp thuy dpng luc vimg ciia sdng, ven biln khu vuc DBSCL.
3. l d : T QUA v A T H A O L U ^ 3.1. Ket q u i hifu chinh k i i m d|nh md hinh Kit qua h i ^ chinh kiem dinh cdc yeu td myc nude, lim lupng, sdng dupe trinh bay rdt chi tilt trong cdc bai bdo truoc day ve nhOng nghien ciiu v l ehe dO thiiy dpng lyc hpc viing DBSCL md nhdm nghien eiiu da tiiyc h i ^ [2,3,4]. Trong nghien c6u ndy chiit^ tdi chi trinh bdy nhftng kit qud hipu chinh Idem ^ n h so li^u ndr^ d$
bim cat la liing tai mpt sd trgm quan trdc d cua sdng ven biln von dupic thyc hifn trong khodi^
thdi gian ngdn, vi$c hi^u chinh md hinh cdn dupe tiiye hi^n bdng vi^c so sanh kit qud tinh todn md hinh ve phSn b6 bim cat ven biln Nam Bp vdi kit qud phdn tich tir dnh vp tmh
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00.D0 09-29 Hinh 0.1. So sdnh nong dp biin cdt mo phdng vdi tdi li^u thicc do ndm 2009
tgi cdc vi tri cica song Cicu Long.
12 TAP CH( KHOA HOC VA C O N G N G H £ T H O Y L O I S 6 40 - 2017
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Hinh 0.2. So sdnh ndng dp biin cdt md phdng vdi tdi lieu thuc do ndm 2012 tgi cdc vi tri cica sdng Cuu Long vd Sdi Gdn-Ddng Nai.
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Hinh 0.3. So sdnh ndng dp bim cdt mo phdng vdi tdi lieu thifc do nam 2012 tgi cdc vi tri ven bien.
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Hinh 0.4.Phdn bd biin cdt tgi thdi diim lOh 26/7/2009 (mua gid Tdy Nam) theo phdn tich dnh ve tinh (trai) vd kit qud md phdng (phdi).
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Hinh 0.5. Phdn bd bun cdt tgi thdi diem lOh 06/12/2009 (miia gid Dong Bdc) theo phdn tich dnh ve tinh (trai) vd kit qud md phdng (phdi).
Hinh 0.6. Phdn bd bim cdt tgi thdi diem 1 Oh 24/02/2010 (mua gid Ddng Bdc) theo phdn tich dnh ve tinh (trai) vd kit qud md phdng (phdi).
14 TAP CH( KHOA HOC VA C O N G N G H £ THCIY LOI S 6 40 - 2017
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3.2. Kit qua tfnh toan chi d$ thdy d$ng lyv:
a) Che dp muc nude
Muc nude khu vye viing ven biln Ddng khu vuc DBSCL cd chi dd trilu dupe phan logi la bdn nhat trilu khdng ddu. Bien dd trilu trong viing nghien ciiu kha Ion: tir 3.0 - 4,0 m trong thdi ky trieu cudng va tir 1.5 -^ 2.0 m trong thdi ky trieu kem. Muc nude cd xu thi ddng cao ddn tir cvta Tieu ve phia Bac Li£u trong khi bien dp trieu giam dan. Ve fdiia biln Tiy muc nude cd che dp trieu dupe phan loai la trilu hdn hpp thiSn v l nhdt trilu khdng deu. Thdi
gian nude len va nude xudng rat khdng deu nhau trong tung ngay. BiSn d0 trilu nhd, tdi da chi dat I.I m ± O.I m
b) Ddng chay tdng hap
Hinh 0.7 trinh bdy k i t qud md phdng trudng ddng chdy tdng hpp tai thdi dilm trilu nit va tri6u len . Phia dudi cae hinh tren trinh bay dudng qud trinh luu tdc tdng hpp tai cac vi tri PI (phia bien Tdy) va P2 (ben ngoai ciia sdng H^u phia bien Ddng), trong dd cd bieu thi thdi dilm trich xudt trudng vdn tdc tuong ling phia tren.
(a) (b) Hinh 0.7. Kit qud mo phdng phdn bo ddng chdy tong hap thdi diem trieu rut
(a) vd thdi diem trieu len (b) c) Ddng du do gid
Trong thanh phdn cua dong chay tdng hpp khu vuc cira sdng ven bien, thanh phdn ddng ven bd do gid khdng chilm nhilu ti le. Tuy nhien
chiing lai cd vai trd quan trpng anh hudng den xu thi van chuyin biin cat d khu vuc nay.
Hinh 0.8 trinh bay phan bd ddng du trung binh trong thdi ky gid miia Tay Nam va Ddng Bac
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trSn khdng gian viing nghien ciiu md rdng trong khi Hinh 0.9 trinh bdy bilu dd phan bd ddng du trung binh thdng 8/2009 va 1/2010 Idn lupt tr6n m^t cdt ngang bd bien t ^ U Mmh (biln Tdy) va Tra Vinh (biln Ddng). Ddng du dupe tinh todn Id hiSu ciia kit qua md phdng ddng chay cd bao gdm tdc dpng ciia ma sat gid va thiiy trilu va md phdng chi xet den yeu to thiiy trilu. Phia biln Ddng, trong thdi k^^ gid miia Tdy Nam ddng du cd hudng Tdy Nam -
Ddng Bdc va nguoc lai trong thdi ky gid miia
£)dng Bdc. Do gid mua Ddng Bdc cd cudng dO mgnh, tdn sudt xudt hi$n ciing nhilu hon nSn cudng dO ddr^ du trong tiidi ky nay ciing Ion hem nhilu so vdi thoi k j gid mua Tdy Nam. Phia biln Tdy, ddng du do gid cd huang Bdc Nam trong miia gid Tdy Nam va ngupe tgi trong thdi k>' gid miia £)di^ Bdc, tuy n h i ^ cudng dp ddng du yeu han nhi6u so vdi phia bien E)dng, ngay cd trong thdi ky gid mua Tay Nam.
Hinh 0.8. Ket qua mo phdng phdn bd ddng du trung binh (a) thdi ky gid miia Tdy Nam vd (b) thdi ky gid miia Ddng Bac.
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M a t cat ngang U M i n h Dangdudo^TBi(2oio^
60000 80000 Khoang each bj bo (m)
M a t cat ngang Tra Vinh Oongdui)QglaTB«2009^] - Deng du do gloTB 10010 ftntt] •
40000 60000 Khoaig each tu bo (m)
Hinh 0.9. Phdn bd cudng ddng du trung binh thdng 8/2009 vd 1/2010 tren cdc mat cdt ngang bd biin tgi U Minh vd Trd Vinh
TAP CHf KHOA HOC VA C O N G N G H E THlllY LOl S 6 40 - 2017
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3.3. K i t quS tinh toan sdng
Sdng la san phdm ndi sinh trong qud trinh tuong tdc giiia gid, cu thi hem la qua trinh luu chuyin tdng khi quyln be mdt dai duang vd nude biln.
Hinh O.IO the hien trudng sdng dgc trung eho eac thdi k j gid m ^ Tay Nam vd Ddng Bdc.
Trong thdi ky gid miia Tdy Nam, khu vyc ven biSn phia Ddng nam troi^ viing khuat ciia hudr^ gid nen sdi^ nhd. Chilu cao sdng d vj tri P2 ven bien Tra Vinh trong thdi k^ nay chi khoang 0.2 - 1.5 m. Hudi^ sdng troi^ thdi ky nay thudng la Nam va Ddng Nam d ngoai khoi, Ddng Nam d viing gdn bd. Trong thdi k^ gid miia Ddng Bdc, chilu cao sdng tai vj tri P2 Id khoai^ 0.5 - 3.5 m, tdn sudt xuat hipn ciia sdng trong thdi ky gid mua Ddng Bdc cung Idn hon so vai thdi ky gio mua Tdy Nam. Chi dp sdng theo miia d vi tri PI ven biln U Minh tren biln Tdy thi ngupe lai vdi vi tri P2 ven biln Ddng, chilu cao sdng trong thdi ky gid miia Tdy Nam Id khodng 0.5 - 2.0 m, Idn hon nhieu so vdi chieu cao sdng trong thdi ky gid mua Ddng Bdc khi
chi6u cao sdng chi Idiodng 0.2 - 1.0 m. Dilu nay Id hodn toan phii hpp Idii s6 U6u gid dupe trich xudt tir kit qud tir md hinh khi tupng todn edu CFSR ciia NCAA (National Oceanic and Atmospheric Administration) tit ndm 2010 2014 tgi hai vj tri biln Ddng, biln Tay xem tEnh 0.11, v l phia bien Ddng, gid miia Ddng Bdc thudng bdt ddu tir thdng 11 din thdng 3 ndm sau.
Phia bien Ddng, ngodi biln gid ed hudi^ ehmh la hudng Ddng Bac, van t6c gid trung bmh khodng 9 - 1 1 m/s, Idn nhdt dat tren 20 m/s. CJ viing ven bd, gid thudng thdi ttieo hudng: Ddng Bdc, E)6ng va Ddng Nam, trong do diil ylu Id hudng Dong va E)di^ Bac. Vdn ^ gid trung binh dgt khodng 8-10 m/s, cao nhdt Id tii 12- 14 m/s. Ngupe lai, d phia bi&i ngoai khoi biln Tay hudng gid chinh trong mua gjd Tdy Nam Id hudng Tdy vd Tay Tay Nam, chi ylu la hudng Tay, vdn tdc gid Idn nhdt khodng 16-18 m/s. d vimg ven bd, hudng gid chinh mua Tdy Nam Id Tdy, Tay Tay Nam, vd Tdy Nam, trong do chu ylu la Tdy Tdy Nam, van toe gid Idn nhdt Idiodng 14-16 m/s.
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Hinh 0.10. Phdn bd trudng sdng vung nghien cicu md rdng ddc trung cho (a) mua gid Tdy Nam vd (b) mua gid Ddng Bdc (phia dudi lan lupt la cdc bieu do chieu cao sdng
cd nghia tgi cdc vi tri PI vd P2 cd the Men thdi diem trich xudt trudng sdng tuang icng d tren).
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Hinh 0.11. Hoa gid tgi vr tri ven bien Ben Tre cdch bd khodng 10 km (phdi) vd vi tri (104.73°, 9.^) ven bien UMinh cdch bd khodng 10 km (phdi), sd lieu ^d gid
trich tic kit qud md hinh todn cdu CFSR giai doan 2010-2014
phia cifa sdng ven biSn vdi dieu ki^n Idii hau, chi dp thuy van thuong ngudn (ddng chay va bun
^ , cat), va che do thiiy ddng luc phia bien (sdng, ung Hinh 0.12 the hifn tuong quan dien bien bim cat s^dt tilp day) vdi chu'ky mot nam khi hau.
3.4. Ket qua tfnh toan diin bien hinh thai a) Phia bien Ddng
Hinh 0.12. Tuang quan bien dong biin cat phia cica song ven biin vai cac miia khi hau, thuy van thuong nguon (ddng chay, biin cat), thuy dong luc phia biin
(ddng du ven ba, song, ung suit tiip ddy) vdi chu kynam khi hau
18 TAP CHl KHOA HOC VA CONG NGH6 T H C I V LOI S(3 4 0 - 2 0 1 7
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Hinh 0.13. Phdn bd biin cdt tren viing nghien cuu md rdng tai cdc thdi diim thdng 8 (a), thdng 10 (b), thdng 11 (c), thdng 1 (d), thdng 4, vd thdng 6 (c).
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• • " - r /fin/i 0. i-^. Phdn bo xdi bdi viing ven bien tgi cdc thdi diem
(a) audi thdng 7, (b) thdng 10, (c) thdng 11, vd (d) cudi thdng 4 Thdi k^' gid miia Tdy Nam ciing la mua mua
lu, la miia cd ngudn phii sa tOc cdc sdng ddi dao nhat trong nam, trong dd thdi ky miia lu tir thdng 7-10 dupe coi la thdi kj' cung cap bim cdt chu yeu eho vimg ven bien. Ddng thdi hudng gid mua ndy ngupe vdi huang md cua dudng bd vung ven bien Ddng nen vai trd cua sdng trong cac qud trinh ven bd miia nay la yeu nhu trinh bay trong myc 4.2. Dilu nay dupe minh hpa kha rd net ti^n bilu dd phan bo sdng va ung suat tiep day tdng hop gay ra bdi ddng chay vd sdng tren Hmh 0.12. Trong thdi ky nay, bim eat tir eac ciia sdng ra da hmh thanh cdc ludng bim cdt (sedunent flume) tren khu vyc them ndng. Trong thdi ky tir thdng 6 cho din giiia thdng 10, ddng du do gid cd hudng Tdy Nam-Ddng Bdc nen hudng vgn
chuyin bim cdt chinh ciing theo hudng nay, cho tdi cudi thdng 10 thi hudng van chuyin bdt ddu chuyen hudng ngugc Igi do tdc dpng ciia ddng ven bd do gid miia Ddng Bdc. Kit qud mo phdng ve phdn bd biin cat va diin biln hhih thai (Hmh 0.13 ^ Hinh 0.14) cho thdy tirong Uidi ky nay qua trinh bdi ty biin cdt chilm uu the, cac hien tuang xdi Id it khi xdy ra.
Trong thdi ky gid miia Ddng Bdc, gid thudng thdi theo hudng: Ddng Bdc, Ddng Ddng Bdc va Ddng, trong dd chu yeu Id hudng Ddng Bdc va Ddng Ddng Bdc. Vdi tdn sudt xudt hi?n vupt trpi, tdc dp gid ciing la Idn hon nhieu so vdi eac hudng khdc, hudng gid gdn nhu tryc dipn vai dudng bd biln md phia bien Ddng, nen ed thi xac dinh gid mua Ddng Bdc la hudng gid chi phdi chinh din qud trinh xdi Id
20 T^P CHl KHOA H p C VA CONG N G H C T H O Y LOI S(5 40 - 2017
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cua bd bien trong khu vuc nay. tTng suat tiep day trong thdi ky ndy Idn han nhieu so vdi thdi ky gid miia Tdy Nam. Chinh vi 1^ do ndy ma mge du la thdi ky miia kipt, ddng chdy va ngudn bim cdt tii cac sdng dd ra Id thdp nhat nhung ham lupng bim cat la limg ven biln thi vdn rdt cao (Hinh 0.13). Ben canh dd, ddng du (hodn luu) trong thdi ky nay cd hudng Ddng Bac - Tay Nam ciing cd cudng dp manh hon nhieu so vdi thdi ky gid miia Tay Nam. Ddy Id nhung minh chiing cho nhan dinh la sdng gay ra bdi gid mua Ddng Bac dao xdi va lam tai la limg phdn Idn bim cdt dugc bdi ty trong mua gid Tay Nam, tao ra dong chay ven bd, cimg vdi ddng trieu va ddng hai luu van chuyen bim cdt v& phia Nam. Day chinh la hudng di chuyen bim cat thuc tren dai ven biln tir Tp.
Hd Chi Minh den Ca Mau. Trong thdi ky nay, mpt phan bim cat theo ddng trieu ngugc vao cac cua sdng vd gay ra bdi Idng tgi cac cira sdng (Hinh 0.14).
b) Phia biin Tdy
Khdc vdi vimg ven bien phia bien Ddng, viing ven biln Tay it chiu dnh hudng tryc tiep bdi che dp ddng chdy vd biin cat vdo ra cac sdng Mekong vd Ddng Nai. Hai ylu to chi phdi chinh tdi chi dp thuy ddng lye, van chuyen biin cat vd diin biln hinh thdi d khu vye nay la ddng thuy trilu, tdc ddng do sdng vd ddng ven bd do gid.
Trong thdi ky* gid mua Tdy Nam, hudng gid va hudng sdng gdn nhu true dien vdi dudng bd.
Ndng lugng cua sdng da dao xdi va lam lo limg hoa bim cat bai, bd biln, la nguyen nhdn tinic tilp gay ra xdi Id bd biln. Nhu dugc mmh hpa ti-en Hinh 0.13a, ham lugng biin cat vimg ven biln tit Hdn Ddt din mi5i Ca Mau trong thdi ky thudng Id rdt cao, bao gdm ca vimg vinh ndng Rach Gid. Ddng chdy ven bd do gid trong khu vyc cd hudng Nam Bdc, tuy nhifin do cudng dd nhd nen chi cd mpt pihdn nhd bun cat van chuyin v l phia miii Ca Mau ve phia bien Ddng.
Phdn Idn bim cdt bi dao xdi ven bd bj ddng
trieu van chuyen va bdi ty phia ben ngoai, mdt phdn dugc vln chuyen vd bdi ty phia tiong he thdng kenh rgch npi ddng ven biln.
Trong thdi ky gid miia Ddng Bde, vimg ven bd bien Tdy la vimg khudt so vdi hudng gid nen boat ddng ciia sdng yeu, ham lupng bun cat thap, xdi Id bdu nhu khdng xay ra.
4. KET LUAN
Nghien cihi ve che dp thuy ddng luc vd dien bien hinh thdi vimg cita sdng, ven bien khu vyc Dong bdng sdng ciru long trong dilu kien muc nude biln hien tgi, cdc kit ludn ca ban sau da dugc nit ra:
(i) Che dp muc nude khu vuc ven bi6n Ddng viing DBSCL cd che dp trieu la bdn nhdt trieu khdng diu vdi biSn dp trilu khd Idn tu 3.0 -4.0 m trong thdi ky trilu cudng va tir 1.5 ^ 2.0 m trong thdi ky trilu kem. Muc nude cd xu the dang cao ddn tir cua Tieu ve phia Bac Li8u trong khi bien dp trieu gidm ddn. Trong khi dd khu vuc ven bien Tdy cd che dd tri6u hdn hgp thien v l nhat trieu khdng deu. Hinh dang trieu d day gdn nhu ngugc Igi vdi trieu bien Ddng.
Bien dd trieu nhd, tdi da chi dat 1.1 m ± 0.1 m;
(ii) Sdng khu vyc nghien ciiu chiu tac d^ng chS dp gid mua. Phia biln Ddng sdng cao tap trung vao thdi kjf gid miia Ddng Bdc, cdn vao thdi ky gid miia Tdy Nam thi sdng nhd hon. Dieu ndy thi ngugc lai che dp sdng viing bien Tdy.
(iii) Ket qud tinh todn cho thdy thdi ky gid miia Tdy Nam ciing la mua mua lu, la miia ed ham lugng phu sa tic cdc sdng dd ra biln ddi dao nhdt trong nam. Trong dd, thdi ky miia Iii tir thdng 7- 10 la thdi ky chu yeu md bim cdt dugc mang tir thugng ngudn sdng Mekong ra vung ven bien. Trong thdi ky nay (thdng 7-10) qua trinh bdi tu bim cat chiem uu the, cdc hien tugng xdi Id it khi xay ra d khu vuc ciia sdng ven bien phia Dong. Ngugc lai, phia biln Tay qua trinh xdi Id chu yeu dien ra vao thdi ky gid mua Tdy Nam, thdi ky gid mua Ddng Bdc ham lugng bCm cdt nhd vd hdu nhu khdng cd xdi Id
TAP CHl mOA H p c VA C O N G N G H C T H O Y L p l S<5 40 - 2017 21
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[I] L6 Manh Hung, Nguyen Duy Khang, va cdng sy, 2011. Bao cao tdng kit de tai cap Bp
"Nghiin cicu xdc djnh nguyen nhdn gdy sat Id vd de xudt gidi phdp bdo vi khu vuc bd biin tie cica Tiiu din cua Sodi Rap tinh Tiin Giang". ViSn Khoa hpc thiiy Igi miln Nam.
[2] Nguyen Duy Khang, Trdn Bd Hodng, va cpng sy, 2012. Bdo cdo chuyen dh "Hi§u chinh va kilm dinh md hinh tdng thi todn vimg biln Ddng". D I tdi ddc lap cdp nhd nude DTDL.20I I-G/39 "Nghien cicu biin dpng cua chi dp thuy thgch ddng luc viing cua sdng ven biin chiu tdc dpng ciia d{c dn di biin Viing Tau - Gd Cdng". Vien Khoa hpc Thiiy Ipi miln Nam.
[3] Nguyin Duy Khang, Trdn Bd Hodng, vd cdng sy, 2013a. Bao cdo chuyen de "Hieu chinh vd kilm dinh md hinh md rpng". De tai d^c lap cap nhd nude DTDL.20I I-G/39 "Nghien cuu bien dpng cua che dp thuy thgch dpng l^cc viing cica song ven biin chfu tdc dpng cua du dn de bien Vung Tau - Gd Cong". Vi6n Khoa hpc Thuy Igi miSn Nam.
[4] Nguyin Duy Khang, Tran Bd Hodng, va cdng su, 2013b. Bao cao chuyen d l "HiSu chmh vd kilm dinh md hinh chi tiet". De tdi d0c lap cap nha nude DTDL.201 I-G/39 "Nghien cuu biin dpng ciia chi dp thuy thgch dpng luc viing cua song ven biin chfu tdc dpng cua du dn de biin Viing Tau - Gd Cong". Vien Khoa hpc Thiiy Igi miln Nam.
[5] Tran Bd Hodng, Nguyin Duy Khang, 2012. Tdc d^ng ciia tuyin dS biln Viing Tdu - Gd Cdng len che dp thiiy thgch dpng luc cdc khu vyc Idn cgn. Tgp chi Khoa hpc va Cdng nghe 7%«y/OT,sd 12/2012, tr. 5-17
[6] Nguyen Duy Khang, Trdn Ba Hodng, 2015. Che dp van chuyen bim cat vimg ven bien ngodi cdc cua sdng Mekong va Ddng Nai. Tgp chi Khoa hpc vd Cdng nghi Thiiy Ipi, so 25/2015, tr. 86-99
[7] Tran Ba Hoang, Nguyen Duy Khang, 2015. Tdc dpng cua tuyIn de biln Viing Tdu - 06 Cdng len che dp thuy thach dpng luc khu vuc cira sdng, ven bien Idn cgn. Tgp chi Khoa hpc va Cdng nghe Thiiy Ipi, sd 25/2015, ti". 13-25
22 T^P CHI KHOA HQC VA C O N G N G H $ T H O Y LOI S(5 40 - 2017