Tai biến địa chất và vấn đề quy hoạch – quản lý đô thị ven biển huế đà nẵng – hội an

Vi du tai bien ruroc dangRQPONMLKJIHGFEDCBAa thi xa Hoi An lau nay va.n ,duqc hieu la do lU thoat khong kip vl Cira Dai bi boi nong va da co y kien de xuat viec khoi thong Cira Dai, nhu

CUC DIA CHAT VIET NAM TONG CONG TY DAU Kid VIET NAM

H(')I DIA CHAT V~T NAMbaZYXWVUTSRQPONMLKJIHGFEDCBA

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NGlIYEN DINI-I I-IOE*, NG~N CAN" , NGllr'EN CIIU JIO!"", mAN DOC THANH"", NGlJ'r'EN DOC CU", NGtJYEN BOO CU*, TRAN DlNII LAN"WVUTSRQPONMLKJIHGFEDCBA

B A O C A O n O I N G H ! K I I O A u o c D ! A C H A T v t e r N A M L A N T H U / I I , H A N O l , " - 5 / 1 0 / 1 9 9 5 2 7 1IHGFEDCBA

Cac do thi ven bien tir l Iue der IT¢i An da diroc hlnh thanh tir lau: I Ioi An la mot

thanh do thi tl1 each day gan 100 narn Lich su xuai h ic n cac 06 thi nay tu ban dau phu

thuoc nhieu vao cac yeu t6 dia lei ur nhicn, trong s6 d6 nhirng uu the ur nhien ve giao

t h o n g t h u y v a cang b ie n dirng hang d a u ,

Qua trinh do th] h6a hien dai a nhirng trung tam dO thi san c6 nay la sir ke thira va

mo rong Nhicu vung dat khong thuan loi cling diroc sir dung lam khu dan cir moi, mat

d¢ dan cir va cong trinh xay dung ngay cang cao, cac trung tam cong nghicp va dan cir

tao ra mot lirong chat thai ngay cang 1 0 0hau nhir khong qua X U 1 9 va quy hoach quan

1 9 Sir bung n6 dan s6 trong cac do thi dful den viec khaH~c tai nguyen qua mire tl! phuc

hoi cua cac khu vue xung quanh do thi gay suy thoai moi tnrong nghicm trong Trong

b6i canh d6 cac tai bien moi tnrong do cac qua trlnh dia dong lire ur nhicn tao ra hoan

toan c6 kha nang k h u e c h dai tac dong Thier hai do chting gay ra trong cac do thi v6n

hlnh thanh va ph at tritn ur nhien la 1 0 0hem rat nhieu Ian so voi thiet hai xay ra a cac

v u n g n o n g t h o n v a rirng mii

-.

Nhfmg hi~u biet ve tai bien moi tnrong va van dung cluing vao cong tac quy hoach

va quan 1 9d6 thi la van d e moi khong chi voi cac mroc dang phat trien ma rnoi voi toan

.the gioi Thirc te d6 khicn cho chuong trlnh moi tnrong cua Lien hop qu6c (UNEP) phai

xay dung nhfrng van ban huang dful vice Slr dung cac s61i¢u ve danh gia dieu kien rnoi

tnrong vao linh vue quy hoach va quan 1 9 lanh th6 [6, 7 1

N6i rieng cho dai ven bi~n mien trung Viet Nam, cac tai bien dia chat nhir IG, lut,

tnrot 1 0 ' dat, dong dat, nut dat, mroc dang, nhicm mam, sa boi luong lach da gay tac

hai dang k t Tuy da c6 mot s6 cong trlnh khoa h9C de cap den cac InfNT~G TAll3IEN

T A c H B 1 ~ Tnay vc mot s6 khia canh, thuc te chira he c6 chuong trlnh nghien ciiu t6ng

th~ nao xem xct toan dien cac tai hien nhir nhfrng QuA TRINH TAl m(iN, la san pham

tong hop cua nhieu hlnh thai dong Il!Cnr nhien va nhan sinh, ma cac hien urong tai bien

• Truong Dai hoc T6ng hop l la Noi

•• Vicn Hilidirong hoc IIili Phong

chi la mirebaZYXWVUTSRQPONMLKJIHGFEDCBAd o virot qua nguong cua cac qua trlnh nay Vi du tai bien ruroc dangRQPONMLKJIHGFEDCBAa thi xa Hoi An lau nay va.n ,duqc hieu la do lU thoat khong kip vl Cira Dai bi boi nong va da co

y kien de xuat viec khoi thong Cira Dai, nhu sau day se trlnh bay van de thirc ra con

phirc tap hem: vai tro cua dong bi~n d9C bo, tac dong cua he thong d6 ngan man vung

Cam Thanh, sir hinh thanh cac vom nang kien tao CI;lCbo a vung ha luu cac song Vu

Gia, Thanh Quyt va Vinh Dien, Sl;l' dang cao mire mroc bien, sir sut chlm kien tao vung

cira song da thoat khoi boi tu hang nam., cling gap phan khong nho tao fa tai bien ruroc

dangWVUTSRQPONMLKJIHGFEDCBA a Hoi An

Trong khuon kh6 s6 ieu It oi tfch lily duoc moi day ve cac tai bien dia chat deli yen bien Ilue - Hoi An, cac tac gia hy vong se thu hut duoc su' chii y cua cac nha quan ly

lanh th6 cling nhir cua cac nha khoa h9C ve vai tro cua tai bien moi tnrong trong quan ly

va quy hoach do thi khu vue Hue - Hoi An noi rieng va mien Trung noi chung

1 Tac d(mg cua su dang cao muc mroc bi~n

r Mire mroc bien dang cao khong ngirng trong 100 nam qua (toe dQ 1,0-2,Omm/nam, bien d¢ 0,2m/100 nam), trong thai gian toi toe dQ dang cao rmrc mroc dai dtrong ngay

cang tang Dir bao den nam 2030 mroc bi~n se dang cao them tir 0,2 den O,Sm (co

nhfing tinh toan la l-2m); den 20S0 se dang cao them 0,5-1,Sm /8,9, 11/ Jelgersma

(1986) tfnh toan ding; do su am len toan cau nho hicu irng nha kinh cong img voi viec

trai dat dong thai t ic n vao thai ky khi hau nong lcn, khien cho trong nhirng nam toi,

mroc dai dirong am len va gian nO', cung voi sir tan dan bang ha trcn day Alpes

Greenl'and va Nam Cue ma mire mroc dai dtrong sc phai dang cao kha nhanh; theo ong,

den nam 2100 mire ruroc dai dirong se dang cao 0,S-3,Sm, chi can mire bien dang len

0,3m cling du pha huy het cac bai bien rong 20-60m (luu y ding cac bai bien mien

Trung dcu rat h9P, thirong durri 20m) Su tan cua lap bang Nam cue trong vong 3 den S

the ky nira se lam mire mroc dai dirong dang lcn them 6m nfra [21

Tac dong moi tnrong cua su' dang cao mire mroc bi6n a mien Trung diroc tang cirong

do hicn urong mroc dang nho' bao: ven bien mien Trung khi co bao gap luc tricu cuong

mroc co th~ dang cao 2,2S den 3,23m [1]

Khong phai toan bo dai ven bien mien Trung deuphan irng tnroc hicn urong mroc dang nhir nhau Do cau tnic khoi tang, nen da g6c diroc chia thanh nhicu khoi 1 6 '1 1 nho,

m6i khoi co bi~u hien nang hay sut khac nhau Voi cac khoi nang co t6c d¢ 1 6 '1 1 hem hay

bang t6c d¢ nang cua rmrc mroc bien, throng bo bien sc rat 6n dinh Tuy nhien a cac

khoi sut ha, hien urong bien Ian, xoi lo, nhiem man va ngap lut sc diroc tang cuong a

dai ven bien Hue - Hoi An, cac khoi clang sut ha gom Dam C a u llai, Vung Da Nang va

Cam Thanh a vung C~m Thanh (phfa dong Hoi An), t6c d0 sut ha nrong d6i trong

vong vai ngan nam tro' lai la 0,3mm/nam

Nl10C dang do bao va su dang cao mire mroc bi<in sc tac dong manh me den vung dat thap yen bien Hue - Da Nang, hien tirong ngap lut se xay ra ngay cang thtrong xuyen

(H.1) Neu cac vung dat thap nay lai diroc quy hoach cho cong nghiep hoac dinh Cl1, cac

chat thai se Ian toa trong nhirng k y ngap ung gay 6 nhiem moi tnrong, tieu diet cac he

sin~ thai ven bien den rmrc rat kho khoi phuc

2 7 3wvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA

2 Hoat dong dirt gay hien dai va cac tai bien lien quan

Thach quyen khu vue Hue - Hoi An co lich sir dia chat lau dai, bi nhieu he thong dUt

gayWVUTSRQPONMLKJIHGFEDCBA ( d i g ) 1 6 '1 1 nho chia cat Cac he thong d i g chu yeu dang heat dong gorn h¢ d i g IIue,

song HGu Trach va mot s6 khac (H.1) G9i la he d i g VI thuc ra rn6i he gom mot chum

dUt gay chay gan song song voi nhau tao thanh mot doi pha huy co chung lich sir, xu6ng

sau trong vo trai dat cac dUt gay trong cung h¢ nhap lai thanh rn¢t dUt gay duy nhal

Cac he d i g c h u y e u trong khu vue d e u la cac d6'i xung yeu, tai h o a t d o n g n h ie u IAn

va la nhtrng doi co tiem nang g a y tai bien.RQPONMLKJIHGFEDCBA

Khoa h9C hien dai da chimg rninh rang trong cac kh6i luc dia cimg ran, da phan

dong dA't sinh ra do str dich tnrot d9C theo cac drit gay

(jkhu vue yen bien Hue - Hoi An, tai lieu dong dA't cling xac nhan quy luat nay Cac

chan tieu ghi diroc lien quan voi cac he dig Hue, he dig Pho Trach va he dig song Cu

De Mac du nang hrong chan ticu khong 1 6 '1 1 (Mrnax <5) nhirng d¢ sau chan tieu nong

(h<20km) nen rA't co kha nang g a y ra cac dong dA't co chan c a p (1°) 1 6 '1 1 Mat khac, vung

dA't thap yen bien co nhieu dien tfch la cac lagoon c6 hien da bi vui IA'p diroi mat dA't

chimg 2-3rn (vung Thuy Thanh - Thuy C h a u a Hue, vung d9C cac song Vinh Dicn va

song De Vong, vung tay bac Hoa Khanh a Da Nang) (I-1.1) Cac tram tich cat bot hat

min bao hoa mroc trong cac lagoon c6 nay co kha nang hoa long khi chan dong, lam

khuech dai bien do va thoi gian dao dong c u a song d o n g dA'tlcn nhieu fan Nhir Ie thirong,

cac vung co tiem nang hoa long bao gia cling la doi co kha nang tai bien cao [2]

Dong dA't can co kha nang kfch dong tnrot la , cac vung nhay earn tnrot 1 a a Hue

-Da Nang lai kha ph6 bien

2 2 H O ( } 1 d o n g I n , ( ( 1 1 L a

/

Cac dUt gay hoat dong a khu vue dia hlnh cao cua Hue - Da Nang tao ra cac siren d6

la trong luc Co the t h a y rA'tfa cac siren dUt gay a vung dco Hai Van, ban dao Son Tra,

doc song Cu De, phfa tay Boa Vang, d9C cac song Ta - HGu Trach a Hue (H.1) Goc

6n dinh cua cac siron da g6c la 32-35°, hoat dong dUt gay da tao ra trong khu virc nhieu

siren dang tuyen d6c den 50-60°, do la cac dai eo tiem nang tnrot 1 a nguy hiem Hoat

dong cua con ngiroi nhir larn dirong 6 to, khai thac da, bat chan sucn dung cot dicn cao

the gop phan tang cuong tfnh khong 6n dinh cua cac siron nay M9i dich tnrot du la

rA't nho d9C theo cac siren dUt gay den dfu1 den tnrot la Cac tnrot dA'ta phfa dong mii

Phiroc Tuong va 0 0 D a u (Da Nang) deu x u a t hien trong b6i canh nhir vay

NUt dA't hien dai diroc phat hien nhicu noi a Thira Thien - Hue (Bang Lang, Hirong

H6, Thuy Chau, Phu Thuong, Thanh N¢i, dau ph6 Ilung Vuong, mii Tuy Van) va Da

Nang (Dien Ban) Mire do mit dA't thuoc cap VII-VIII (gay hir hai nang den mire tai

i, IHGFEDCBA ' I ( : : : : : : : R IF ( -,wvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA il'6· 40~

I Vung cf6i rnii da goc, hoat dong boc mon, nra troi, xarn thirc t6ng hop;

2 BOng bang h6i tu song bi~n gi6

~ Vung nhay earn dong d a t

5 l3()i tu manh

6 DUt gay hoat dong:RQPONMLKJIHGFEDCBA a l Xac dinh tren da cimg

b/ Gia dinh dum la p phu tram tfch vun 00.

7 TAm dong etat

8 TAm mrt dat va phuong uu t h e cua he khe nUt

9. 6nhicrn phong xa t l ! nhicn

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bien) Dicu dang chiibaZYXWVUTSRQPONMLKJIHGFEDCBAy la cac trung tam mrt da'tWVUTSRQPONMLKJIHGFEDCBA a Thira Thien - Hue dcu nam trung v6i cac tuyen d u t gay duoc phat hien tren anh ve tinh Nghicn ctru chi tiel cac khc mit cho

khe mrt (thuat ngif d ia chat goi fa hai canh), phu hop voi qui luat diroc: xac dinh nho phan tfch tnrong lire kien tao hien dai dang tac dong tren lanh thO Hue - Da Nang [3]

Truong khe mrtRQPONMLKJIHGFEDCBAa Dien Ban xuat hien a tam mot vom nang hien dai dang hoat dong manh

Tai lieu khoa h9C cho t h a y rang cac diit gay dich chuyen co th~ kern theo dong dat hoac khong, tnrong hop khong kern theo dong dat diroc goi la sir tnrot em, co th~ gay mrt dat Ket qua tinh toan cho thay bien d¢ dich chuyen ngang d9C theo he d i g song Cu

De la c a 700-800m va song Thu B6n la khoang 1500m trong su6t ky D¢ tu [1]

Tai bien mrt dat tuy khong on tao nhimg cue ky nguy hiem; cluing co kha nang cat

va he thong 6ng dful ruroc, dan dau, dful chat thai, cat pha h¢ thong day cap thong tin ngam: lam mat mroc trong cac ho chira, suy thoai de dap, tang cuong xoi lo, gay dO nha cira, lam giam gia tri dat dai va cac bat dong san, Ian toa 6 nhiern Cac khe mit a Hue cat pha vao KyDai, Ng9 M6n va cac di tlch lich sir can gay t6n that nhieu hon ntra,

3 V~n dong nang Cl,IC bl) dang vorn cat qua dong song

Nghien CUu dia dong hrc khu vue flue - Da Nang trong su6t lich sl'r Holocen da xac nhan su' xuat hicn va 16'11dan cua cac khoi nang cue bo cat ngang mot s6 dong song trong vung

- Yom nang Hai Thanh cat ngang song 0 Lau, song 0 Lau a ch6 do bi that lai, khong du sire thoat IG khien cho mot hrong mroc dang k€ cua song lam lay hoa vung con cat Quang Dien

- Cac vom nang An Hoa, Plui Yang, Thuy Thanh gay cai bien manh me he thong thuy van khu virc thanh pho Hue, ricng vom Thuy Thanh cat ngang song c6 Dai Giang, hai mra song hien nay chay ve hai phfa, ngiroi ta phai dao kenh Phii (tam d€ dful mroc song Hirong ve darn C a u HaL Svxuat hien va tang tnrong cua vom Thiry Thanh da tap trung nang luong dong chay song Hirong vao vung cira song Hirong, gop phan tao ra lut

a ha hru song Hirong ciing nhir viec tr6 cira Thuan An thay cho cira Tu Bin

- a dong bang Quang Nam - Da Nang, vom nang Yen Ne xuat hien gan cho hop luu cua song Yen va song Tuy Loan; vom Nhon Th9 cat ngang song Bau Xau lam hai mra, mua kho moi mra chay ve mot phia, chi co mua mi.ra rnroc moi chay diroc ve phfa song Han: vom Dien Ban cat doi dong song cO Cam Na - ha luu Vinh Dien khien cho m6i mra chay ve mot phia khac nhau (tnroc day v6n la mot dong song duy nhai d6 ve song Ban) Narn 1822Minh MC;iOgcho dao song Vmh Dien de thoat IG cho II¢i An Cira song Vinh Dien gan day co nguy CC/bi boi lap

Cac vom nang Yen Ne, Nhon Th9 va Dicn Ban chi la nhirng trung tam nang xuat hicn trong vung nang hien dai giira song Thu B6n va song Han, khien cho mroc song Thu B6n vao mira lG chi co mot bo phan nho chay thoat vao song Ban, dong luc mroc

va boi tich cua cii he thong song Thu Bon tap trung vao cira song Thu B'L>ngay bienbaZYXWVUTSRQPONMLKJIHGFEDCBA

Lich sir dia chat vung song Thu Bon cho t h a y tir dau cong nguyen cho den t~ the' ky

XVII, song Cira D~ (phan ha hru song Thu 136n) vfuI la mot cira song hlnh pheu mroc

sau [8]; cac song nho phan luu tir song Thu B'L>nsang song Han (song Yen, song Thanh

Quyt, song BAuS a u , song Cfun Nam - ha hru Vinh Dien) da co thai la nhirng dong song

Thu B'L>nva song Han da dfuI d6n sir boi xoi bat thirong vung cira song Thu Bon, gop

phan dang ki vao tien trlnh suy thoai cang Hoi An va do thj II¢i An, dong thai tang

cuong t6c d¢ do thi hoa Da Nang

* Qua trlnh hlnh thanh cac vom nang dia phuong v6n tir cluing khong phai hien

urong tai bien, VI cluing xay ra cham chap; tuy nhien cling nhir bgt err qua trlnh dong lire

noi sinh oM, cluing la qua trlnh khong th~ dao ngiroc diroc, la cac qua trlnh khong che

xu th€ phat trien cua Ianh th6 va quy dinh S,! tac dong cua cac qua trlnh khac Chung tro

thanh hien nrong tai bien chi khi con ngiroi tac dong ngiroc chieu do chira nhan dien

diroc cluing hoac c6 y khong danh gia dung vai tro cua chung

4 D o n g b i~ n doc b o va t a i b ie n sa b o i luong lach

Mot vai tro quan trong cua bai bi~n la triet ticu nang lirong song, bao ve doi bo' khoi

hoat dong xoi mono D~ dat diroc vai tro do, bai bien phai thoai va du rong

Bai bi~n mien Trung noi chung va Hue - Hoi An noi rieng hep va d o c , S6ng biin

thirong xuyen 1 6 '1 1 (cap III - cao O,9m: mua gio tay nam; cap VIII cao 3,5-4m: mua gio

dong bac), tac dong xuyen goc v6i bo ca trong hai mua gio Dicu do khien cho phan 1 6 '1 1

nang luong song chuycn thanh dong yen boo

Dong yen bo Da Nang - Hoi An co toe d¢ vao mua gio tay nam la O,5-1m/s, rnua gio

dong bac: O,3-0,4m/s, 1 6 '1 1 hon t6c d¢ dong yen bo vinh Bac B¢ 5 I'A n vao mua gio r a y

nam va 2,5-3,5 Ian vao mua gio dong b a c , C h jn h VI t h e b o bi~n mien Trung thirong phat

tri~n cac con cat d9C bo, kco dai n6i dao, bien nhieu thuy vue yen bo va cira song thanh

darn pha

Mot tac dung cua dong d9C bo la lam xuat hicn cac doi cat, lam thu h9P cira song,

bien cac cira song mien Trung thanh dang "khuyet ao"; ur than qua trlnh nay chira phai

la tai bien, nhimg chinh no da lam t6c d¢ thoat lU cua song cham him lai; gop phan gay

ung lut vung cira song mien Trung, cac doi cat khep cira song lai hay thay d6i theo mua,

khien cho Iuong lach cling lien tuc thay d6i theo Mot s6 dao n6i gan cira song Thu Bon

bi xoi la voi t6c.d¢ d6n l Jm/nam nhir dao Cam Nam, bo nam Cira Dai bi xoi mon voi

t6c d¢ 6-8m/nam Nhieu bai boi moi diroc thanh tao

Cling chfnh cac doi cat do dong d9C bo da nhieu ph en 19p kin cira Ttr Hien va boi

nong cang Da Nang Vat lieu boi nong cang Da Nang chinh la boi tfch cua song Cu De

do dong d9C bo mua dong till xu6ng, cac ke luong da cuu diroc cang Da Nang, nhimg

dong thai lai gop phan boi nong vung bi~n bcn ngoai kc; d¢ sau cua vung bi~n Ian can

cang Tien Sa chi co I-2m, nhieu ch6 0,3-0,5m, co ch6 O,lm; khai niem ve mot cang Da

Nang mroc sau tren thuc te da khong can dung nira

5 Cac nguon 6 nhlem phong xa tlJ nhien

Cac con cat co tuoi Holocen gitra - muon (chirng 5000-2000 nam tnroc) trai dill theoWVUTSRQPONMLKJIHGFEDCBA

b a blen tir Quang Tri den Hoi An chira nhieu than sa khoang nang, trang thanh phan sa

khoang ngoai ilmenit (quang titan), zircon can co monazit la loai khoang vat chira

nguyen t6 phong xa nhir thori, urani Viec tham do danh giacac than sa khoang nay can

dang diroc tien hanh Hien da biet nhimg tich tu dat ham hrong cong nghiep a V!I1hMy,

Tir Hien, Vinh Phong (Thira Thien - Hue) va Cira Dai, Mire d¢ phong xa cua cac than sa

khoang vung Tu Hien, Vinh Phong th~t dang ngai: cirong d¢ phong xa co ch6 dat den

1400~R/h (cirong do 300~R/h tra len la cuong d¢ gay hai cho ngiroi), Bao cao cua

Doan dia ch~t 207 (1993) viet: "Trang qua trlnh nghien CUu a dai yen bien Phii Loc

cluing toi thay nhieu nguo;baZYXWVUTSRQPONMLKJIHGFEDCBA1 6 '1 1 va tre em b] d] t~t nhir earn, dice, slit moi, than kinh ,

chung toi cho rang sir s6ng bi anh huang cua moi tnrong Cl nhiem phong xa den rmrc

kinh khung"

Hien chira co s6 lieu dieu tra ve Cl nhiern xa tren toan bo dai cat nay, nhimg dieu

.chilc chan yen bien Phti Loc khong phai la noi duy nh~t co bidu hicn o nhiem phong xa,

Nuoc con cat gan nhir la n g u o n mroc duy nhai c u a dan cir s6ng tren do That dang ngai

la tnroc khi xuat 1¢ trang cac gieng, mroc ngam da phai di qua cac tfch tu phong xa,RQPONMLKJIHGFEDCBAa

Vinh Phong, den mroc thai sinh hoat cling bi nhiern xa

•

Cac tai bien moi tnrong noi chung va tai bien dia ch~t noi rieng thoat nhln co th~

gi6ng nhau nhimg thtrong co nguon g6c phirc tap khong m a y khi nhu nhau Nham giarn

bot thiet hai do tai b ie n gay ra can hieu r6 co che' cac qua trlnh tai bien de chon phirong

phap tac dong vao qua trlnh do, khong d~ cho no phat trien dat d~n ngirong moi tnrong

Hue - Hoi An la mot vi du biroc dau lam r6 them co che' mot s6 qua trlnh va hien

nrong tai bien diroi goc d¢ Dia c h a t Moi tnrong D~ hi6u r6 hon cac tai bien rnoi tnrong

dai yen bien mien Trung, tao co s a cho cong tac quy hoach va quan 19 do thi, can co

cang som cang t6t mot chuang trlnh dieu tra nghien ciru t6ng th~ ve tai bien thien nhien

trang do co tai bien dia c h a t Ket qua can co cua chuang trlnh n g h ie n ciru nay la cac ban

do chi r6 cac vung nhay earn tai bien, it thuan loi cho phat tri~n va phirong hirong quy

hoach cac vung do

Hay can qua sorn neu coi nhimg van de neu tren la du d6 hi~u r6 cac tai bien moi

tnrong a Hue - Hoi An, va cling can qua som d~ tir mot vai s6 lieu rnong manh do d~ De

xuat mot each voi va cac ke hoach quan 19 lanh th6 Tuy nhicn cling co th6 nhan xct

rang d6i voi vung nghien cuu, dai d~t thap cira song -ven bi6n va cac he dUt gay heat

dong la nhirng vung mang nhieu tai bien kho lirong Lich su da d~ lai nhirng khu dan cir

toa lac ngay trcn chinh nhtrng vung tai bien nay, lich su cling cho t h a y su suy tan cua do

thi c6 Hoi An, s\!'phat trien day kho khan cua Hue va thanh ph6 Da Nang mac du nhieu

277

mo hoi lao dong da d6 xu6ng manh dtft nay, mac du khong the phu nhan dtroc cac "tiem nang" va loi the cho sir ph at tri~nWVUTSRQPONMLKJIHGFEDCBA a day

Con ngiroibaZYXWVUTSRQPONMLKJIHGFEDCBAv a thanh p h o khong th~ tr6n chay t h ic n tai m a can thfch img voi cluing Tren cac dai dUt gay dang hoat dong va vung dtft thap cira song - ven bien, dill tranh xay dung cac cong trlnh tao ra nhieu chat thai nguy hiem nhir cong nghiep loc dau, hoa

can thira va co kien tnic phu hop: cac dirong 6ng va cap ngam cling can co m~t dQ va k€t cau hop ly a cac vung dtft thap ven bien, heat dong quai de, dap dam nuoi lam cat giam nguon cung cap boi tfch co the lam gia tang hieu img iing lut va nhiem man, do do can khai thac a ty l¢ phu hop

Tranh xay dung nha cira va khai thac v~t lieu xay dung a chan cac siren drit gay co nguy co tnrot lc r

Nhirng cong trlnh kien tnic quy da toa lac ngay tren d a i tai bien can c6 k6 hoach va kinh phi gia c6 hoac tharn chi di chuycn Co the thiet lap cac quy bao hi6m de chia mong thiet hai cua vung c6 thien tai len mot cong dong Ian hon, lam cho nhfrng ngiroi dinh cir trong vung tai bien khong hoang mang hoang 10';\ncling nhir c6 dieu kicn nhanh chong 6n dinh cuoc s6ng va phuc hoi san x u a t

Cling can c6 nhimg quy dinh ro ve vice cung cap thong tin d a y du cho nhimg ngiroi

1)6 ket luan co the nhan manh them mot dicu la chi co con ngiroi de quen tai bien VI cluing thinh thoang rnoi xay ra: nhieu khi hang the he diroc s6ng trong thanh blnh khong co thien tai dang k6; nhirng tai bien moi tnrong khong bao gio lang quen con ngiroi Theo su phat trien cua qua trlnh do thi hoa, tai bien moi twang dirong nhir ngay cang tram trong, khong phai VI ur than chiing tra ncn manh lict hon ma chinh su thieu hop ly trong k6 hoach phat tri~n cua xa hoi da Jam cac tai bien tro ncn tram trong

VANIHGFEDCBA L l l t U

1 0 0 D1Nr1 KHOI, 1993 Ngap iing c rdong bang ven bien mien Trung Khf urong thuy van 8(392): 27-32

2 JELGERSMA, s., 1986 A future sea-level rise: its impact on coastal lowlands In

"Atlas of Urban geology" ESCAP, vol 1: 61-81

3 NGuvEN CAN NGUYENDINII HOE, 1994 Recent faulting in coastal zone of Vietnam and its relation to seismic activities Proc Inter Symp on seismotectonics and seismic hazards in Southeast Asia, Hanoi, P 137-138

4 NGUYENCllU JIOI TRAN m:t: TH~H, NGlNEN m:t: cu 1991 l)ieu kien nr nhicn va sinh thai h~ darn pha Tam Giang - C a u Hai va dam Lang C6 Thong tin KH va CN Thira Thien Hu€, 1/1991: 32-39

,

5 NGUYENNGQCTJ-Jl)Y, 1990 KhI hau toan cau n6ng lcn va mire mroc bien dang cao Khi nrong thuy van, 10 (358): 13-16

6.baZYXWVUTSRQPONMLKJIHGFEDCBAU N E P , 1987 Environment Guidelines for Settlements planning and Management, Narobi, Kenya, v II-III

7 U N E ~ a , 1992 Coastal Systems Studies and Sustainable Development Proc of the COMAR Interreg Sci Conf Paris

8 YO vAN Pl-iAI, f)~G vAN BAa, 1991 Dac di~m dia mao khu vue Hoi An va Ian can, trong "1)6 thi c6 H¢i An", NXB KHXH, HaN¢i, tr 87-100.IHGFEDCBA

S U M M A R Y

Geological hazards and urban planning management in Hue Danang

In coastal region from Hue to lToi An - Central Vietnam - many types of natural and man - made hazards such as earthquakes, earth fissures, landslides, floods, storm surges, deposition, radioactive contamination etc have been recorded for years These hazards are commonly concentrated in coastal lowland and along active fault systems Hazardous data should be evaluated in urban management and planning.

I •