Hoi nghi Khoa hoc va Ccmg nghe hien toim qu<'>c inn ihu y
DIEN BIEN VUNG CtlA SONG VEN BIEN IIAI PHONG VA NHUNG VAN DE KHAI THAC TRONG BOI CANH
BIEN DOI KHi HAU VA N U O C BIEN DANG
Pham Quang SoTi, Nguyen Cong Quan, Biii IMiu'o'ng Thao Vicn Dia chdt - Vicn KI ICNVN
Trong 45 num cpcu (1965-2010) vimg cua sdng ven hien Hdi Phcmg dd . ,i nhirng bien ddi diu hinh manh mH do liic diing cua cite yeu td ttr nhien vu h. •. :i de'mg eua con ngircri. Trong do, cdc boat ddng kinh te - ky thudl ngu\ i ••
lung len
Bui hdo gidi thieu mdt so kel epid nghien cuu vi diin bien phdl trien v'"i\^
cira si'ing ven bien Hdi Phdng tren ca sd phdn lich ccic thong tin vicn thdm • /t/
thiri giun vd cdc thdng tin dia ly khdc. nhdm ddnh gid nhirng mat thudn ' >i cimg nhu nhirng khd khun hien nuy cr vung ven bii}n Hdi Phong
llai Phdng Id mdi dmh cpmn trong cuu tum gicic kinh le Hd Ndi - Lldi Phdng - Oucing Nmh vd thdnh phd dang phdt trien manh ru phiu biin Trong bdi cunh dang cd dti}n biin cua bien ddi khi hgu lodn cdu vd mrdc bien ddng. tin vice khui ilu'ic vitng ven bien Hdi Phong cdn chii y den cdc bien phdp phong ngira vu thich ung vdi hodn cdnh mcri ndy.
THE EVOLUTION OF ESTUARY AREAS IN HAI PHONG COASTAL ZONE AND SOMtVlH EXPLOITATION ASPECTS UNDER CLIMATE ClIANGi':
AND SEA LEVEL RISE
Pham Otians Son. Nguyen Cong Quan, Bui Phuong Thao tract;
In 45 years (from 1965 to 2010), the topography of Hai Phong coerskd :"nc and estuary area have been drumaticully chunged due lo natural cause' well as human activiiies in rapid ecoiwmlc and technical development.
This report introduces some findings about the evolulion cf llai Phung coasted zcme and estuary area based on the analysis of multi-temporal renn le sen.sing deUa and other geogruphycal documents, m order to as,-' *^
opportunities and challenges in the area oj Hen Phemg
Lied Phong is an important lop ofthe Hanoi-Haiphong-Quangninh ecmu^'iic triangle and a seaward extending city Under global climate change and sea
Tten bun Diu li Dui c hdi xd Dm vdt ly llien
level rise ciiihlitions. the exploitution of lluiphong's couslul zone needs lo consider uboul prccuuiums und udaptulions lo new situulions
I. MO t).U
I nmg cong code Ddi mdi ciia ddl nunc. 1 lai Phdng Id mdt dmh quan trgng eua lam gidc kinh le Ild \ d i - llai Plidng - Qudng Ninh, nen ihdnh phd cdng cd dieu kicn phat men nii^iiih \:i ihii'c le dang duge ma rgng \e phia bien. llai Phdng la mdt ihdnh pho ldn \cn bien Bdc Bo. nilm kep giua nhung cua sdng ldn ihugc he ihdng Sdng Ildng - sdng Thai Binh. nhu ede cua I acli llu\en. cua N.ini liieu. cua Cam. cua Laeh l r a \ . eua \'an Lc.
cua riidi Binh. Cde cini sdng nd\- deu phdl trien manh \d ludn bien ddng do eac nhdn id tu nhicn \d houl dgng khai thdc. cbinh iri eua con ngirdi, Nhirng bien dong eiia \'ung cua sdng a I lai Phdng Jd ed tae dong \'d dnh hu'o-ng ldn den quy hoaeh \d phdl liien thanh phd cang irong ibdi gian hicn lai \ a Irong urang lai.
Miuiig bicn ddng d viing eua sdng \cn bicn Hai Phdng. dicn hinh la hien lugng xdi lo' bd sdng - bd bien. bdi Idp ludng laeh, ilia\ ddi ddng cba\. nude ddng \ en bien. ngdp hii \ d nliung bicn ddi \ c mdi liudng .sinh ihdi.... Cde bien ddng tren deu ed lde ddng xau ldi ddi sdng cua nhdn tidn. ldi cdc hoat dong san xual \d quy hoach phdl inen ibanb phd LJIIL;
Trong lime id. 1 lai I'hdiig da gap khdng il khd khan do hicn lugng bdi lap cac lu\en ludng vdo eang tlo qud liinh d nhiem nude bien a khu nghi dudng - du lieh Dd San. hay nhung khd khdn liong \iec cung cap nude .saeb cho nhan dan thdnh phd do nhiem man cdc ngudn nude \cn b i e n . . .
'Irong nghien cuu nay, chung ldi de cap den nhimg bien dgng khdng gian d vung cua song \cn bien phia Bac ban dao Dd San lliudc ihdnh phd Hdi Phdng, nhflng vdn de dal ra chn ihanh phd cang khi qii}' hoaeh phdl trien trong dieu kicn dang dien ra qud trinh bicn ddl khi hdu lodn edu \d nude bicn ddng, Nhung ddnh gid irong bdo cdo. dua Iren Iren ca so phdn lieh tai lieu vien iham da thdi gian. cdc lai lieu khdo sdl thue dia vd eac ibdng tin khde CO lien quan tdi khu vue nghien cuu
II. n i l ' O N C ; PII.U* NGIIILN C I U VA NGl'ON TAI LILU SU DUNG Cdc ldi lieu su dung irong nghien cuu dien bien \ung cua sdng \cn bien thdnh phd llai Plum^ bao udm cdc^u lieu dnh ve linh Radarsal-I SAR (1995. 1996). Spot 1.2.4.5 {I9S8, 1991. 1995. 2004); Ikoiio/ (2002); Landsat MSS (1975). '1 M (1989). LTM (1999, 2001. 2005. 2008. 2010): ban dd dia hinh UTM (1965). Gauss (1995-1996); Alias dien lu (1998). ldi lieu khdo sdl thuc dia vdo cdc nam 1984-1986, 1995-1996. 2009-2011 trong kluidn khd mdt sd dd lai khoa hoe - cdng nghe eae edp va cdc tai lieu khdc cd lien quan.
Phuong phdp thue hien chinh trong nghien euu ndy la gidi dodn thdng tin tren cde anh
\'c linh. bdn do dja hinh ed su dung cde phan mem khde nhau nhu PCI, Arc/view.
Map'Info... vdi he iga dd ehuan VN-2000 va cdc tai lieu bd trg khde ed lien quan de phan tich. ddnh gid linh hinh dien bicn cdc eua sdng \'en bicn I Iai Phdng
Hat n^ln Khua hae va Cang n^hc bien toait qtuit I6n thu V
III. DIEN BIEN \ LNG CU.A SONG VEN BIEN HAI PHONG (1965-2010) Bteit dotig dta hinh ccic cira sottg vert hien Ihanh pho Hdi Phong ducrc danh giii ihong qua quti Ifinh boi tti va xoi la qua 7 giai doan ngdn: 1965-1975. 1975-1989. 1989-1995^
1995-2001, 2001-2005, 2005-2008 va 2008-2010 ti hon khu vtfc nho, gtim:
- Khu vtxc ddo Cat Hdi ttam giira cua Lach Huyen viH cua Natn Trieu, - Khu vtrc ddo Binh Vii ndm giira cira Nam Ttieu vd cua Cdtn (cU), - Khu vtfc cira Cam - ctra Lgch Tfay, vd
- Khu vtrc cira Lgch Ttttt - bdc Do Sent.
1. Khu virc dao Cat Hai
Qua trinh xoi la ba bicn dien ra trong hang chuc nam qua, tren chieu dai lion 6km tli BSn Got toi Hoang Chau.
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(a) (b)
Hinh }-. Dien bien khu virc cira song ven bien tp. Hai Phong a/-Giai doan 1965-1975; b/-Giai doan 1975-1989 / . / . Ciai doan nam 1965-1975 (hinh la)
Bor bien dao Cat Hai bi xoi Id manh tren chiSu dai 6,6km tit BSn Got (nSm phia BonP
^ ^ ' P l ^ * ' ' ' * "^ ^ ° * " ^ '^*'^" " P'''^ ^*y '"^™ ''^ ^ ^ ' ^ ' " " Trieu). Doan bii bi xoi Id manh nhat thuoc dia phan cac xa Van Phong, Hoang Chau co chiSu dai 3,1km, chiSu long trung bmh 160m va rong nhat tai 21 Om, tuang duong toe do xoi Id trung binh 16m/iiam va Ion nhat ten 21 m/nam. Doan bo biSn thuoc thi tr§n Cat Hai co cuang do xoi la Ihdp hon;
bo XOT lo CO chieu dai 2,2km, rgng trung binh 35m va rpng nhat la 60m, tuang dirong toe dp XOI lo trung binh 3,5m/nam va lon nhfit 6iTi/nam, Ciic doan ba dao Cat Hal 6 phia Dong (cira Lach Huyen) va phia Tay (cua Nam TriSu) dien ra hiSn tuong xoi - boi xen ke iren cac doan ngan co chieu dai tir 0,8 - 1,6km voi cuong do xoi icr va b6i tu nhe.
Tieu ban Dialy^iiacliai vci Dia vdi lv Btin
1.2. Giai dogn 1975-1989 (hinh lb)
Bd bien tiep tuc bi xdi Id tren chidu dai 6,4km tir B^n Gdt ldi Hoang Chdu. Tai thi trdn Cat Hai, vung bd xoi cd chieu rdng hj 20-45m, rgng nhdt tdi 70m, tuong duong toe do xoi tir 1,4 - 3,2m/nam va ldn nhdt 5m/nam. Tren doan bd bidn thi trdn Cat Hdi tu Ddn Luong den Gia Ldc tdc do xdi Id da han chd do cd ke da bao ve. Tren doan bd bidn phia Tay TT.
Cat Hdi (doan Gia Lge - Hodng Chdu) bd bidn tidp tue bj xdi Id manh tren chidu dai 2,7km, rgng trung binh 130m. rgng nhdt tdi 350m. luong duong tdc do xdi Id trung binh 9,3m/nam va idn nhat 25m/nam.
Bd dao thudc eua Nam Trieu va cua Lach Huyen bi xdi lo tren cae doan ngdn, co chidu dai tir 1,7 - 2,3km. Doan bd ddo Cat Hdi thudc cua Nam Trieu bi xdi manh, mgt phdn do ddng chay sdng Cam (Kinh Thay) chuydn hodn loan sang cua Nam Trieu khi ddp dap Dinh Vu (nam 1978) cd hudng chdy xien gdc vdi bd ddo Cdt Hai, gay xdi Id doan bd nay.
Ngoai ra. tren dao cdn cd hien tugng xdi la nhdn tao do viec xay dung kenh Cdi Trap-1 (nam 1985) ndi lien eua Nam Trieu vd cua Lach Huyen, phuc vu giao thdng thuy ndi dia bi Hai Phdng ra ddo Cdt Ba vd vimg than Qudng Ninh. Kenh Cai Trap-l cd chidu dai 3,3km va rdng trung binh 200m. Ngodi viee dao kenh, dap ddp, thi cac boat ddng nhan tao khae nhu nao vet duy tu ludng tau vao cang Hdi Phdng, tac ddng eiia sdng re dudi tau.
ddng chay do tau bien qua Iai ddu cd anh huong It nhicu tdi klid nang bdi tu - xoi Id ven bien dao Cat Hai
• . v \ ~ ' - - ' -
(a) (b)
Hinh 2: Diln bien khu vuc cua sdng ven bien tp. Hai Phong a/- Giai doan 1989-1995; b/- Giat doan 1995-2001 1.3. Giai dogn 1989-1995 (hinh 2a)
ViJng bd phat trien theo phuong thuc xdi - boi xen ke tren nhiing doan bd ngan. Doan bd phia Bdc (kenh Cai Trap-l) dicn ra xdi Id nhe tren sudt chieu dai 3,1km dge theo ldng kenh. Bd phia Ddng (kd cua Lach Huyen) diln ra xdi - bdi tren cdc doan ngan cd chieu ddi rtr 0,7 ' 1,2km Doan bd bien phia Nam T.T Cat Hai diln ra xdi Id nhe, do cd ldp ke dd bao
Hch nghi Khou hoc vit Cimg nghe hicn loc'in ifun, tan llu'r V
ve \a han chd qua irinh xdi Id bd. Doan bd bien phia Tay T.T Cat Hai (tren dja phan cde xa Van Phong - Hoang Chdu) dien ra bdi tu - xdi Id xen ke nhau tren eac doiin ngdn cd chidu ddi lir 0,5 - 0,8km. Doan bd phia Tdy, gdm cac doan tir cua kenh Cai Trap tdi xa Hodng Chdu diln ra qua trinh xdi Id nhe tren chieu dai 2.8kiTi, rgng trung binh 40m va rgng nhdt la 90m, tuong duong tdc do xdi trung binh 6,5m/nam va ldn nhat Id ! '^w ii:tni 1.4. Giai dogn 1995-2001 (hinh 2b)
Viing bd phat trien tuong ddi dn djnh, trong do cac doan bd phia Bde (kenh t di Trap), phia Ddng (ben cira Lach Huyen) va phia Tay (ben cira Nam Trieu) dugc bdi (u nhe Dogn bd bidn phia Nam tir Ben Gdt tdi Hoang Chdu it cd bien ddng Idn, nhd cdc dnnn kc xay du'ng bang dd vd be long, da han ehe dugc tdc ddng eua sdng bicn.
Tren doan bd phia Tdy xual hien vung bd xdi Id ngan thugc dja pban \d I iu.uig Chau, day la doan bd xoi la cue bd nhung nam sdt vdi khu dan cu. Viing bd xdi ed rhieu ddi khoang 0,6km, rgng trung binh 45m va rdng nhai Id 130m, tuang duong tdc \6i Id lii' 7.5m/nam den 21,6m/nam. Doan bd phia Ddng T.T Cdt llai dugc bdi tu do vici- quai dc lan dat vd xay dung cae d nudi thuy sdn ven cii'a Lach Huyen.
1.5. Gitn dogn 2001-2005 (hinh 3a)
Tai khu vuc phia Bac dao Cat Hai, bien ddng dia hinh ldn do vide ddo kdnh Cai rrap-2 (kenh Ha Nam) dai 3,9kni va rdng 350m, co true gdn triing phuang ddng - liiy, la luyen ludng tdu bicn mdi di vdo cang Hai Phdng thdng qua cii'a Lach Huydn. Trong thdi gian nay ddi bd dao phat trien theo phuong thii'c xdi - bdi xen ke tren cdc doan ngan, cd LIH^U dai tii' 0,7 - 1,8km. Tde do xdi Id vdbdi tu khdng manh, nhin chung bddao tuong ddi dn dinh.
Ben canh dao Cat Hdi, cae vimg dat ngdp nude thude dao Ha Nam, bai Nhii Mae, dao Qua Xodi, dao Qua Mudm.vv... deu cd bien dgng manh do viee khai thae vimg dat ihdpdc xay dung cde d nudi thuy sdn. Qua trinh xay dimg cac viing nudi thuy san dien ra nhanh chdng trong nhirng nam qua d ven bien Hai Phdng ndi neng va cac tinh ven bicn Bae Bd ndi chung.
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Hitth 3. Dicn biSn khu vuc cua siing ven bicn Ip. Hai Phimg a/- Giai doan 2001-2005; b/- Giai doan 2005-2008
Ttiu hem Dia ly. Diu chut vu Dia vdi lv Bien
1.6. Giai docui 2005-2008 (hinh 3b)
Cae doan bd phia Bdc va phia Nam ddo d uang ihdi boi lu nhe. diln bien dgc theo bd kenh Cdi lrdp-2 vdi eudng do boi nhe. Doan bd bicn tir Ben Got ddn Hodng Chdu duoc bdi \y nhe tren clneu ddi 5,9km. Cdc doan bir phia Ddng va phia Tay eiia dao dien ra xdi Id va bdi lu xen ke nhau tren ede doan ngdn, ed ehidu ddi tir 0.3-0,8km.
1.7. Gild dogn 2008-2010 (hinh 4ii)
Bd bien ddo tuong ddi dn dinb, dicn ra qud trinb xdi Id vd bdi tu nhe iren ede doan ngan. Bien ddng ehinh la linh irang xdi Id nhe dge kenh Cai Trdp-2, do hoai dong eua ede phuang lien ^•an tai ihiiy eo Idn qua lai. Hien lugng xdi Id nhe edn dien la tren doan bd phia Tdy TT. Cdi Hdi. thudc dia phan xa Hoang Chdu. Hicn tuang xoi Id bd dien ra tren cdc doan ngan cd ehieu ddi tu 0.8 - 1,2km.
2. Khu \ ue ddo Dinh \'u
Trong 45 nam qua, ven bidn ddo Dinh Vu cd nhung bien ddng manb, dien bien xen ke giua bdi lu \'d xdi Id khd phire lap tren ehicu ddi ban 5km lir ddng sang ldy vd iren cdc doan bd khdc xung quanh dao.
2.1. Giai dogti niiin 1965-1975 (binh la)
Bd bien phia Nam bj xdi Id manh tren chieu ddi 4,8km. rdng trung binh 130m va rgng nhai ldi 300m. luong duang ldc do xdi Id irung binh 13m/nam \ a Idn nhdl dal idi 30ni/nam. Xdi Id cdn xual hien tren doan nam ke ben kdnh Dinh Vu (kenh ndi eua Cdm va cira Nam Tneu) va doan bd thudc cira sdng Cdm \ di ehieu ddi 2.8km. rdng trung binh 50iii vd rdng nhdt tdi 190m. tuong duong ldc dg xdi trung binh 5m/nam vd Idn nhdl id 19m/nam. Doan bd phia Ddng ddo Dinh Vu (nam ke eira Nam Trieu) phdl irien ihicii ve trang ihdi bdi tu; doan bd ddo phia Tay Nam (kc cua Cdm) phat Iricn theo phuong ihire xdi - bdi xen ke tren cdc doan ngan co ehicu ddi tir 0,4 den 0,8km.
2.2. Gicddocin 1975-1989 (hinb lb)
Doan bd xdi Id nam d phia Bdc ddo (ke ben kenh Dinh Vu) va phia Ddng nam eiia ddo vdi dien tieh khdng ldn, chirng td tde do xdi Id da gidm ddng kc so vdi giai doan Irudc. Bd kenh Dinb Vu xdi la do sau khi dap dap Dinh Vu (1978) lodn bd nude va ddng biin cat lir sdng Cdm (Kinh Thay) chuyen sang phia cira Nam Trieu qua kenh dao ndy. Doan bd phia Ddng nam bi xdi Id, bdi boat ddng manh ciia cdc hirdng sdng gid ehinh irong miia he, do dudng bd ldi nang Iugng sdng hdi tu manh
Doan bd phia Tdy dao Dinh Vu dugc bdi lu manh, bdi cira sdng Cdm da bi e'ldn lap (nam 1978) tren ehidu dai 6,1km, ehicu rdng irung binh 200m va rdng nhdt tdi 400m.
tuong duong tdc do bdi irung binh 14,3m/ndm va ldn nhdt 28,5m/nam. Doan bd phia Ddng ddo Dinh Vu dugc bdi lu nhe.
2.3. Cdc gitd dogn 1989-2001 (hinh 2a, 2b)
Bd dao d Irang thai thicn ve bdi lu vdi lde do trung binh 33m/nam va ldn nhat tdi 65m/nam d phia Tdy; sau 1995 xuat hidn vimg bdi tu Idn vdi dicn tich tdi 258 ha d phia
//<;; ii^hi Khaa hag I'ti Cong rtg/u' hitjii liiait tta:,.
Tay Nam vol t6c dp b6i tu trung binh 41,5m/nam va ion nhat toi I33ni/nam. Viiiir n bjj tu dupe khai thac phat IriSn cac 6 thiiy san va trong rirng ngap man dS bao \ c hii 2.4. Cdc giai dogn 2001-2010 (hinh 3a,3h.4a)
Trang thai viing bir tuong ddi on dinh. Ciic doan bcr phia Dong, phia Tay va rt Nam dugc bSi tu nhe Mpt s6 doan ngan ci niiii diio Dinh Vu co hien tupng xcii la cv , voi quy mo khong lon. Tir 2005, dao Dinh Vu duac phat tnen nhanh hon vS co so \tv • -iig va CO so cong nghiep, cang. B6i tu nhan tao dicn ra do mo rpng xay dung khu ci n iiii-p, cang vii cac cong trinh ky thuat khac tren dao.
(a) (b)
Hinb 4-. Dien bien khu vuc cua sdng ven bien tp. Hai Phdng a/- Giai doan 2008-2010; hi- Phdn bd viing bidn ddng trong thdi ky 1965-2010
3. Khu vuc ven bien cii-a Cam - cua Lach Tray
Qua trinh bdi tu phdt tnen manh theo kieu bdi "lap gdc vjnh". Vimg bdi Lu duac trdng rii'ng ngap man nham giii dat vd bao ve eac d nudi tbiiy san phia ven bd Irong 45 nam qua khu vuc nay cd dien bien tuong ddi phire tap bdi tac dgng ciia lu nhicn vd con ngudi.
3.1. Giai dogn ndm 1965-1975 (hinh la)
Doan bd ben phai eira Cam duge bdi tu manh vdi chieu dai 4,4km, rgni; i r n g binh 200m va rdng nhat tdi 400m, tuong duong tdc do boi trung binh 20m/nam \a idn nhat tdi 40m/nam. Doan bd bien nam giira cira Cam vd cira Lach Tray phat tridn theo phii''ng I'TJ'^
xdi - bdi xen ke vdi cudng do nhe, dien ra tren cac doan ngdn cd ehieu ddi (u 1.4 den 1,5km. Doan bd phia trong cua sdng Laeh Tray duge bdi tu nhe vdi chidu rgng \nwg binh 40m vd Idn nhdl la 100m, tuang duong ldc do bdi lu trung binh 4m/nain va ldn nhat la
lOm/nam.
Tteu hull Dtu ly.Djci cheil vu Dtu vdi l\ litei
3.2. G'teddocin 1975-1989 (hinh lb)
_ Trong cii'a sdng Cdm bd phai bi xdi Id Iren chidu ddi 2.6km Doan bd bien lir cii'a C am den eua Laeh Tray duoe bdi lu manh vdi ehidu ddi 4.7km, rdng trung binb 420m va rdng nhdl ldi 600m. luong duang tdc dd boi Ui luing binh 30m/ndm vd Idn nhdt 43m/nam. Vimg bdhdi lu duge irdng rirng ngdp man dd bao ve cdc d nudi Ihuy sdn phia trong. Kbu vue nay dirge bdi lu manh sau khi cd dap Dinh Vu chan ddng cira Cdm, dd bidn ed doan bd bien lu Dinh VQ - Dd Son ihanh mdt vinh nude ndng nua khep kin. Nha ed \ i iri thudn lgi.
tranh dirge ldc ddng trge tiep cua eae hirdng sdng bicn. nen qua irinh bdi lu dien ra nhanh chong theo kieu bdi "lap gde vinh"
3.3. Ccic gicd dogn 1989-2001 (htnh 2ci,2b)
Ven bd khu vue nay ticp luc duge bdi lu vdi ldc do trung binh 16.5m/nain vd ldn nhdl ldi 65m/iiam. Vimg bdi tu ticp luc phat tnen nhd viec md rgng dicn lich rimg ngap man ven bien Sau nam 1995, lde do bdi lu ldng len dal irung binh t40m/ndm va ldn nhai bvi 200m/nam
Qud irinh phdl irien bdi lu manh d khu vuc giua eira Cdm - cira Laeh 1 ray eung nhu dicn I a bdi tu d doan bcr nain ke can phia Nam ddo Dinh Vu dugc gidi Ihich Id ehiing phdl trien ibeo nguj'cn lac bdi "lap gdc vmh". Bdi lu dicn ra vdi ldc do nhanh Irong didu kien il chiu ldc ddng ciia sdng bien. mai khdc cdn do lac ddng lich cue eiia viee md rgng dicn lieh rii'iig ngap mdn dd gop phdn ldm lang tde dd bdi lu vd khd nang giiJ- ddl mdi bdi Irirde lac ddng eua ddng chav. ihiiy iricu va sdng bien.
3.4. Cite gicd demn 2001-2010 (hinh 3a,3b,4ct)
Doan bd bien ciia Cdm - eira Laeh Tray nam irong linb trang xdi Id nhe tren chidu ddi 4.2km. rdng Irung binh 25ni va rdng nhdt Id 90m, tuang duong tdc do xdi irung binh 5m/ndm vd Idn nhat la 18m/nam. Tir 2005 - 2008. xu the bdi tu lai Idn al. viing bdi cd dien tieh kboang 285ha. chicu dai gan 4.2kni. rdng trung binh 700m va rdng nhdl ldi 1.600m.
dugc khai ihdc dc nudi irong thuy .san va trdng rung ngap man ven bien, Giai doan 2008- 2010 vimg bd tuong ddi dn duih.
4. Khu vue phia Nam ciia Lach Tray - bac Dd Son
Trong 45 nam qua, viing ven bien ndy phdt trien thidn ve trang thai bdi tu, luy nhien qud Irinh dicn ra khdc nhau trong mdi giai doan ngan.
4.1. Giai dogn nam 1965-1975 (Itinh let)
Bd bidn phia Nam cira Lach Tray phdt trien iheo phuang thiic bdi lu - xc- Id xen ke vdi cirdng do nhe, ndm xen kc tren cac doan cd ehicu dai lir 0,5 - 1,1km Vdo ddu nhung nam 1970. tai khu vuc bd bidn Tan 'Ihdnh dd dicn ra vice khai hoang lan bien, vdi dicn licb khoang 590ba. Viing ldn bidn cd chieu dai 4.4km, rgng irung binh 1.600m va rgng nhai la 2,300m. Day ciing Id noi diln ra qua trinh khai hoang idn bicn Idn nhat cua I ldi Phong trong nhung nam 1960-1980.
Iloi nghi Khoa hoc va Cehig nghe bien loan qiiot lim
4.2. Gicddocin 1975-1989 (htnh lb)
Bd bidn phdl tridn theo phuang thirc xdi - bdi xen kc vd thicn ve trang thdixdi In Vims, bd xdi Id ehinh ndm ke tuydn de bien thudc dia phdn phudng Nggc Xu>en (Dd Son). \ img bd xoi loco chidu rdng irung binh 90m va Idn nhat Id 180m, tuong duang ldc do xdi uung binh 6.4ni/ndm vd km nhdt 13m/nam Hicn lugng xdi Id bd dicn ra do lae ddny .-u i cac hirdng sdng Ddng va Ddng Nam vd do bai bicn ed do dde luong ddi ldn. khdiiLj i M umg ngdp man ehe chdn ben ngodi.
4.3. Ccic gild dogn 1989-2001 (hinh 2a, 2b)
Bd bien phdl Incn Iheo phuong thire xdi - bdi xen ke. Viing bd bdi tu dugc ma idng nhd viec Udng rirng ngdp man ven bd. nhdm ban che tac ddng eiia song va ddng cliLi-i. lain ldng kha nang bdi lu \d bdo \ e lu>'en dd bicn sung yeu d doan bd da dugc quai tie Ifm hien trong nhung ndm 1960-1980. Ben canh vimg bd bdi tu la cdc doan xdi Id nhe Vmi;' hu xdi Id CO ehicu ddi lir 1,2 - 1,8km. rdng irung binh 40m vd rdng nhdt 70m, tuong dudiir idc do xdi lo Irung binh 6.5m/nam va ldn nhdl Id 11.7ni/nam, Sau 1995, vimg bd bicn iiraiii; Jdi dn dinh.
4.4. Ciic gicd dogn 2001-2010 (hinh 3a,3b,4a)
Trong ihdi gian ndv. bd bien pbia Nam cua Lach I'ray tuang ddi dn dnih. bdi lu nhe Iren cde doan ngan vdi ehieu ddi lir 1,8 - 3kiii Dgc bd bicn dugc trdng ihem dien lich rirng ngdp mdn nhdm giir ddl bdi vd bdo ve luyen de bicn. Tir 2005-2008, vimg bdi tu manh nhdl nam ke eua Laeh Tra\ vdi didn lieh khodng I46ha. Vimg bdi ndy cd chieu ddi 2,5kni. rgng Irung binh 560m dugc khai thac trdng rii'ng ngdp man va nudi trdng thuy sdn. bd bien doc tuven de dn dinh, Tu 2008-2010, vimg bdi lu ed chieu dai lir 1,3 - den 2,lkm. Cic viing bdi lu diroc khai thac nudi ihiiy san vd trdng rirng ngdp man.
I\ . OANH GIA TINH M I N H PHAT TRIEN VUNG CU'A SONG VEN BH.tN TP.
HAI P1I()NG VA N H C N G VAN DE DAT RA TRONG BOI CANH M()l Tdng hgp va cdc ddnh gia chung vd qua irinh phdt trien d moi khu vire trong thdi gian 45 ndm qua (1965-2010) tren bang 1 nhu sau:
1. Khu VU'C ven bien dao Cat llai da cd nhu'ng bidn dgng Idn dugc ghi nban do cdc yeu to tu nhien vd boat dgng khai thac, chinh tn eiia eon ngudi. Bidn ddng Idn nhdl ghi nhdn duoc Id hien luong xdi Id bd bicn phia Nam ddo Cat Hai. Nhd vice xay dung luyen ke bang dd hoc va be long dge bd bidn T.T Cat Hdi vd cdc tuydn ke tren de bidn Van I'hong - I lodng Chau. nen da han ehe dugc qua trinh xoi Id bd va bidn Idn vao ddo.
Cac bidn dgng khac trdn ddo Cat Hdi do boat dgng khai thac, chinh tri nim vice xay dung kenh Cdi Trap-l (1985) va kenh Cdi Trdp-2 (2004) dd ldm thay ddi ddng kr dien mao Ircn dao. Cdc hgat ddng khae nhu xdy dung eac ddm nudi thiiy san, chuydn ddi sir dung dat ndng nghiep - diem ngbicp, ndng nghiep - thuy san, xay dung cac cdng trinh gum thdng - thiiy Igi.vv. . da gdp phdn Ibay ddi cdnh quan vd mdi trudng tren dao Cat Hdi.
TKuJtanDiaJy., Dtu chih vit Dia ritt lv Btin
Bdng I. Tong hop dicn biSn khu vuc ctra song ven biSntp.Hai Phong, thai ky 1965-2010 Ghi chit. (I) linh trang hi>i lu: (-) linh Irgng xt'ii ia, (+/-} linh tntng biti - x(')i xen ke
Giai duan
1965-1975
1975-1989
1989-1995
1995-2001
2001-2005
2005-2008
2008-2010
Nhan xet
Khu vuc diio Cat llai
(-) (-)
(+/-)
(+/-)
(-/+)
(+/-)
(-/+)
Bd xoi la,
it on dinh
Khu VU'C nghien cu'u Khu vuc
dao Dinh VQ
(-)
(+/-)
(+/•)
(+)
(+/-)
(+)
(+/-)
Bdi tu, chua dn dinh
Khu vuc eua Cdm - C.LachTrav
(+/-)
(+/-)
(+)
(+)
(-/+)
{+)
(+/-)
Bflitu manh.
chua on dinh
Khu vuc phia Nam c LachTray
(-^)
(+/-)
(+/-)
(+/-)
(+/-)
(+)
(+)
Bdi tu, chua dn djnh
Danh gia tinh tran}>
vung ven bien tp. Hai Phimg Bd bien xdi Id manh, cdc cira sdng il dn dinh Bd bicn va cua sdng
il dn dinh Bd biC'n it dn dinh, cdc ciia sdng bdi lu Bd bicn luong ddi dn dinb,
cdc cira song bdi tu manh Bd bien vd eac cira sdng
il dn dmh
Bd bien tuang ddi dn djnh, cdc eua sdng bdi lu manh
Bd bien va cde cua sdng il dn dinb
2. Kliu >'uc ^e^ bien dao Dinh Vu da cd nhu'ng bicn ddi sdu sac, bicn ddi ldn nhat gbi nhan dugc sau khi ddp dap Dinh VQ, ehan ddng cira Cdm (1978) lien quan chat che den qud Irinh bdi lu d phia Tdy ddo, cua Cdm thu hep ddn va tao ra khdng gian bdi tu manh, noi iicn ddo Dinb Vu vdi phdn ddt lidn thude quan Hdi An. Cae bien ddng khac edn do xay dung CO sd ba tang giao thdng, khu cdng nghiep va cdng container Ircn ddo Dinh Vu
Hidn lugng xdi Id bd bicn phia Ddng nam ddo Dinh Vu da dicn ra trong mdt thai gian kha ddi do ldc dgng ciia thiiy trieu vd sdng bicn. Hien nay dao Dinh Vu dang dugc md
UOI iighiKlwu Iwc va Cong nghe hien loan L/U/K l,i,i ihi-f y
rdng nhd qua trinh bdi tu va ldn bidn dd xdy dung cac cdng trinh cdng nghiep. Trong bdi cdnh hicn nay ed nhirng didu kien bdt lgi do bicn ddi khi hdu va nude bicn dang ihi cdc nha ddu tu \ a quy hoach cdn pbai chii y den nhurng dae didm ndy.
3. Khu vu-c ven blC-n giua ciia Cdm - cu-a Lach Tray ed nhtrng bidn dgng rdt dang chu y lir sail dap dap Dinh Vu. Tai khu vgc giua hai cira sdng ndy, vung bd bicn phdt tridn bdi (u dn dinh trong nhilu nam qua, cd tdc dd bdi lu nhanh - ddy cung la khu virc bdi lu nhanh nhdt o viing nghidn cdu theo kicu bdi ''lap gde vinh", nhd cd ngudn bdi lich ddi ddo vd ddng luc sdng gid phd buy ihdp; mat khae cdn ed vai trd tich cue ciia eae Iham linig ngdp man do nhdn dan trdng dc giQ- dat, cdi tao mdi trudng va bao ve ede d nudi thiiy sdn 4. Khu \iie vtn bicn phia Nam ciia Lach Tray, lir nhung nam 1960 cdng cudi ddp dc, khai hoang ldn biln dien ra rat manh; da cd ban lOOOha dat bai trieu da duge khai hoang.
trd thanh ddl canh tae ven bicn. hinh thdnh len xa Tdn Thanh (quan Duong Kinh) pbuimg Ngoc Xuyen (qudn Dd S o n ) . Tu\ nhicn, hicn lugng xdi Id cue bg ven chan de bicn dicn ra trong nhicu ndm sau khi dap de ldn bicn. Sau nam 1989 bd bien trd ndn dn djnh ban, do nam trong vimg it ehiu ldc ddng cua sdng bien nhd dirge trdng rimg ngap man klui ddy. Vc long the bd bien dugc bdi lu manh theo kieu bdi "lap gde vinh" niia kin, tuong lu doan bd bien phia Nam ddng bang Sdng Hdng thude dia phdn cdc huyen Kim Son - Nga Son (Ninh Binh-Thanh Hod).
Mdt diem dang luu y. vung ven bien Hai Phong eo dia hinh khd thdp, ludn ehiu ldc dgng manh bdi ede yeu id ddng luc sdng - bicn. Trong dd yeu Id bien dien hinh Id dao ddng muc nude do thuy trieu ed bien do thude loai cao nhat d Viet Nam. Thuy tneu bicn do ldn tao ra ddng chav dang - rdt rat manh trong cdc ludng lach d cira sdng Mai Phdng.
Hien lugng ddng chav \ a biin cat tir he ihdng Sdng Hdng phdn chia ve phia Ddng Bdc ehdu thd ngay cang ldng len, gdp phan ldm thay ddi dicn mao vimg ven bidn 1 Idi Phdng.
Trong ban 45 nam qua, tai khu vue ven Hai Phdng da ghi nhdn nhtrng bicn dgng manh do tdc ddng eua tu nhien va eon ngudi. Trong qua khir, viing ven bien Hai Phdng da phai hung ehiu nhieu Iran bao ldn; nhu Iran bao thang 8/1955, gay vd dc bidn va lam thiel hai ndng nc ve ngudi va val ehat cho cu ddn sdng d ven bien.
Hicn nay. trong bdi canh dang dien ra nhu'ng bien ddi eua khi bau va hien lugng nude bicn dang, llai Phdng sc Id mdt trong nhQ'ng dia phuang dung ddu d nude ta ehiu ldc dgng manh eua lae nhdn tu nhicn nay. Vi vdy, vice sdm cd kd hoach chu ddng thich irng vdi nhirng dicu kien mdi cdn duge dal ra. Dae bicl hicn nay khi thdnh phd cdng dang cd nh&ng du an kinh le - xa hdi Idn de dua thanh phd vuon xa ra phia bidn. se xay dirng them nhicu edng trinh kinh le - ky thudt quan trgng d cac viing ddt mdi bdi va chua dn dinh. can duge can nhac ddn eac phuang an ddi phd vdi nhQ'ng bdt Igi ciia thidn nhicn.
V. Y KIEN TRAO DO! VA KET LUAN
Trong thdi gian 45 nam qua (1965-2010) viing cira sdng ven bidn Hai Pbi>iig da co nhu'iig bicn dgng to Idn do cac tac ddng cua thicn nhicn va hoat dgng kinh t l - ky tbnal ciia con ngudi. Trong dd, cac boat ddng nhan lao ngay cang tang manh, do nhu cau phdl trien kinh le - xd hdi kbi Hai Phdng ird thanh mgt dinh quan trgng trong tam giac kinli le Ha Ngi -1 lai Phong - Qudng Ninh.
Tteu han Dig If. p,,, chiil rd Dia vdt li- Bten
Khn vuc cira song a ven bicn lliii Phong vii viing lan can se con bicn dong manh, do tiic dpng cua cac nhiin to lu nhien, hoat dpng khai Ihac cac vimg dal Ihip ill chinh In soilg- bien. Viing bicn dpng co pham \ i anh hucrng rpng, do do khi quy hoach khai Ihac sir dung khong gian \cn bicn, can tinh den nhtrng ySu 16 bdt loi do lai bicn thicn nhien gay ra; nhai la trong dicu kicn hicn nay khi dang co nhung tac dpng xdu va bdi thudng do hicn lupng bicn doi khi liiiu va xu huong nuoc bien si; diing cao Irong nhirng thiip ky ldi
Viing ven biC-n 1 lai Phong co dia hinh Ihdp, si; chiu lac diing m,iiili boi qua trinli nuirc bicn diing va xam nhap man viio siiu trong he lh6ng song ngoi, linh trang ngap lut si: gia tang do d|a hinh ciic khu dan cu diap ... Ucn canh nhung mat lieu cue do hicn lupng lu nhicn nay giiy ra. chiing ta can hicu bijt da chii dpng phong tranh. hpc each s6ng vii ihich nghi voi chiing. Ngoai nhung mat lieu cue. bdi lpi con co nhirng mai lich cue khac cdn dupe khai thiic sil dung. Nhung nial tich cue khi muc nuac bidn diing Icn la didu kien cho phill Iricn nghe nuoi Irong Ihiiy siin ven bicn. phai tridn loai hinh giao song Ibiiy vai eiic phuang ticn chinh la cac loai lim. IhuySn pha song - bien; chiing co sire viin lai khong liVn nhung sc dc dang iuu ihong iren cac he thdng song ngoi 6 ven bidn 1 lai I'liong noi rieng l a
\en Iiicn Biic lip noi chunii ./.
TAI LIEU Til \ M KHAO
TRINH VIFT AN (chil bien). 2000. Danh gia hien Irang. xu Ihd dien bidn \ii kli.i niing Ihoal lu eua eae eiia cac cira song lliupe he Ihdng Song H6ng - song Thiii Binh. Dinh hudng gi.ii phap chinh tri long the. Vii:n Khoa hoc Thity loi. I la Noi
NGUYHN VAN CU. PHAM QUANG SON vii nnk, 1986. Nghien ciru bidn ldn dao Cai I lai (1 lai Phdng) va budc dan de xuiil cac giai phap phdng chdng B/c de lin nghien eiru giira Vicn Khoa hpc \ c Trai Dal va Sd KHCN-MT lp. Hai Phdng.
NGUYliN VAN CU', PIIAM QUANG SON \a nnk, 1990 Dong luc vimg ven bidn ciia sdng Viet Nam. Phiin nghiSn ciru cua sdng. B/c dc lai 48B-02-01. Vien KHVN, Hii Ndi. 355 lr.
NGUYHN VIET PHO, VU VAN TUAN, TRAN THANH XUAN, 2003. Tai ngujen nude Vicl Nam. NXB Ndng nghiep I Iii Ndi 392 lr.
I'l 1AM QUANG SON, 2002. Su dung Ihdng tin vicn tham va cong nghe GIS trong nghien ciru, Iheo ddi l a canh bao su cd xdi Id, Irual Id bd sdng. 1 ldi lliao qudc le "Biio l e ngudn ddl va nude ciia chiing la" (MLWR). Ha Ndi. 20-22/10/2001. Tr 155-160.
PHAM QUANG SON. 2006. Dicn bicn cac vimg cira sdng d ven bien ddng bang Song Hdng Irong nhung nam dau van hiinh edng trinh Ihiiy dien Hda Binh Tap chi Dia chdl. loal A. sd 295/7-8/2006. Tr. 125-137.
I>II.\M QUANG SON vii nnk, 2007. Dicn bidn viing ven bidn cac linh Nam Dinh.
Ninh Binh Irudc va sau khi co cong trinh lliiiy dien Hda Binh qua phiin tich thdng Un vicn Iham va GIS. I'ap chi Cac Khoa hpc vd Triii Ddl. Sd 3 (T.29)/2007 Tr. 267-276.
TRAN DUC THANH, 2008. Tac dpng ciia sdng, biio ddi vdi cac cong trinh bd bien Bdc Bd vii giai phap phdng Iranh. Tap chi Cae Khoa hpc vc Triii Diil. Sd 4 (T.30)/2O08. IliiNpi Tr 555-565.
Ildl nghi Khoa hi;/c va Cong nghe hien loan cjiiQc lim il„-^ y
9. PHAM HUY TIEN (chu bicn), 2004, Du bdo hidn tugng xdi Id, bdi iii bd bidn eira sdng va gidi phdp phdng chdng. Bao cdo ldng kdt dd tdi KC.09.05. T.T KHTNvCNQCi HdNdi.
10. TRAN THANH XUAN, 2007. Dac didm thuy van va ngudn nude sdng Vidi Xam Nhd xudt bdn Ndng nghiep. Ha Ngi, 427 lr.
11 CNBS (Centre Nalionale d'Bludcs Spatialcs - France) From Opiics lo Radar. Spoi and
| ; R S Applications Cepaducs Editions, Toulouse, France 1993. 573pp.
12. i;SCAP/UNDP. 1989. Remote Sensing Applications to Coastal Zone Siudics and I'jivironmenlal Monitoring. Regional Remote Sensing program. Hanoi.
