35(2), 107-119 Tjp ehl CAC KHOA HOC V£ TRAI B A T
C A N H B A O N G U Y CO TRLTOT LC5 DAT
CTCAC HUYEN MIEN NUI TINH QUANG NGAI
PHAM VAN HUNG', N G U Y £ N VAN DUNG^
E - mail: [email protected] 'Vi^n Bia chat. Vien Hdn Idm Khoa hoc vd CSng ngh^ Viet Nam
^Vi4n Dia ly, Vien Hdn ldm Khoa hgc vd Cong nghi Viet Nam Ngay n h | n bai: 14 - I - 2013
1. M d dau
Tinh Chuang Ngai nam d vimg Duyen hai mien Trung, cd vi the vua tua vdo dai Trudng San hiing vT, viia hudng ra Biln Ddng {hinh l); phia bdc gidp Qudng Nam, phia nam giap Binh Djnh, phia tdy giap Kon Tum va Gia Lai vd phfa ddng la Bien
Ddng. Tinh Quang Ngai nam trdi dai tii 14°32' den 15°25' vy dp Bdc, tir 108°06' din 109''04' kinh dp Ddng, gdm cd thanh phd Quang Ngai va 13 huyen, trong dd cd mdt huyen dao la Ly Son, 6 huyen ddng bang va 6 huyen mien mii (gom Ba Ta, Tra Bdng, Tdy Trd, San Tay, Son Ha va Minh Long),
HInh 1. Bdn d i phdn bd TLD cdc huy$n ml^n niii tinh Qudng NgSi
Dia ban cdc huyen mien mii tinh Qudng Ngdi ndm trong viing cd dilu kien ty nhifin rat phuc tap, hdng ndm phdi hung chju nhitng tSn that khdng nhd do tai bi6n dia chdt gay ra; ddc biet la trupt Id dit (TLD) dang cd xu hudng ngdy mot gia tdng ca vl quy md vd tin suit xuit hi6n, de I^i nhiing hdu qua n§ng ne cho cupc sdng cua ngudi dan. Nhieu doan dudng bj viii lip, thdm chi bj pha buy, Idm tS lipt giao thdng trong nhieu ngdy (dudng Bdng Trudng Son, quoc Id 24, tinh Id 622, 623, 626);
ddi, niii, rupng vudn (Lang Mam, Gd Riia,...), nha ciia cua cu ddn bi phd huy, dd sap (thon Ddng, thdn Tdy, xd Trd San; Trd L?c, Trd Xanh, xa Trd Lam;
Td BI, xd Scm Bua; Trd Ong, Trd Xudng, xa Trd Qudn; Bdc Duong, xa Trd Thp; Tra Cdt, xa Tra Thanh; Tra Linh, xd Trd Lanh; Td Dieu, Td Bau, xd San Thuy, Rudng Gd, Diep Thuang, xd Thanh An;
Ddng Chiia, xa Ba Chua; Sudi Loa, xd Ba Dpng;
Ldng Mam, Ldng Dieu, xa Ba Bich; Va Chdy, Ddng Ldu, xd Ba Le,...); su an toan ciia cac hd dap thiiy dien (ho Nudc Trong, Ddc Pring, Trd Bdng,.,.) cd nguy co bi de dpa, dnh hudng din ddi sdng ciia cu ddn sdng d viing dudi ddp.
Viec nghien ciru phdng trdnh gidm nhe thilt hai do tai biln dja chdt ndi chung, TLD ndi riing gdy nen dd dupc chii trpng trong nhiing ndm gin day [1-4], Tai biln TLD d mdt sd dia phuang trong tinh dd dupc nghien cuu d miic dp khde nhau, d^t dupc nhiing kit qud nhdt djnh phuc vu cho cdng cudc phdng trdnh giam nhe thiet hai va bdo ve mdi trudng d dja phuang. Tuy nhien, cho den nay tren dja bdn cdc huyen mien mii tinh Quang Ngai, cdn chua cd cdng trinh ndo nghiin ciiu danh gid chi tilt hipn trang vd khoanh viing canh bdo nguy ca tai bien TLD, ldm co sd cho quy hoach phdt trien bin viing KT-XH vd bdo ve mdi tnrdng. Do dd, hang ndm, TLD d viing nui cdn diln bien phiic tap, khd kilm sodt va nhiing tdn that vl KT-XH d noi day cdn kha Idn. Trudc ylu ciu bite xiic cua thuc tiln ddi hdi, De tai "Ddnh gid hien trang, khoanh viing canh bdo chi till nguy ca trupt Id ddt d cac huyen mien nui tinh Quang Ngai phuc vy quy hoach phdt trien ben vung" da dupc trien khai va nhiing kit qua budc ddu ddp ung ylu ciu cua thuc tien ddt ra hipn nay.
Cdng trinh ndy trinh bay mot phin kit qud thyc hipn de tdi nlu tren, trong dd thi hien chinh nhiing ket qua vl hipn trang va phan viing cdnh bao nguy CO TLD d cdc huypn mien mii tinh Qudng Ngai.
2. TJii li^u vi phirong ph&p nghiSn cuu Cdc tdi li^u nghign c ^ trong cdng trinh ndy Id tdng hpp cdc tdi lieu phdn tfch gidi dodn anh viln tham, khdo sdt chi tilt ngodi thuc dia ndm 2011- 2012 vd kl thiia tdi lilu trong nhOng ndm qua. Kit qua nghien cuu dupc hinh thdnh trin ca sd tich hpp til nhilu kit qua: nghiin cuu ngodi thyc dja, phdn tich - nghien ciiu trong phdng vd ke thiia cdc kit qua trudc ddy. Dl ddnh gid hipn trang vd phdn viing canh bdo nguy ca TLD, cdc phuong phdp dp dung bao gdm: phan tich dnh vien thdm, khdo sdt thuc dja, phan tich t6ng hpp, phan tfch so sdnh c$p (AHP ciia Saaty) vd phdn tfch khdng gian trong mdi trudng GIS.
Phdn tich anh vien thdm dupc iing dyng dl giai dodn vj trf cdc khdi trupt trin dja bdn nghien cuu.
Phuang phdp khao sdt thuc dja Id chu d^o dupc ling dung dl nghiin cihi ddnh gid hipn trang vd cdc ylu td tdc dpng phdt sinh TLD. Q ngodi thyc dja, tiln hdnh do ve chi tilt, xdc dinh quy md, cdc d$c tnmg ciia khdi truot vd nhitng yeu td tdc dpng phdt sinh TLD. Tir dd, cho ph6p ddnh gid hi^n tr^ng vd diln bien ciia qud trinh trupt Id trong khu vyc nghien ciru, Phucmg phdp phan tich so sdnh cdp [5, 6] dupc ling dyng nhdm xdc djnh vai trd cOa timg yeu td trong tdng hpp cdc yeu td tdc dpng phdt sinh TLD tren ca sd cho diem vd tinh trpng sd. Phuang phdp phdn tich khdng gian trong mdi trudng GIS dupc dp dung de xay dung bdn dd phan viing cdnh bdo nguy ca TLD.
Bdn dd nguy ca TLD dupc xay dyng dya trin sy hilu bilt ve cdc chuyin ddng phuc t^p tren sudn vd vl cdc yeu td gay ra trupt Id [5, 6]. Vifc khoanh vg cdc khu vyc hiln thdi chua bj tdc ddng cua TLD dupc dya tren gid djnh rdng, qud trinh trupt Id trong tuang lai se dien ra trong ciing mpt dilu kien vdi cdc vu TLD quan sdt dupc dd xdy ra trudc do. Vi^c vgch ranh gidi cua cdc vung nguy co trupt id xuit phdt tir xac suat xay ra hien tupng, tir sy tuong ddng ciia cdc ylu td tdc ddng phdt sinh TLD nhu: dp ddc, mat dp chia cdt sau, mdt dd chia cdt ngang, ddc dilm vd phong hod, ddc tinh dja chit cdng trlnh cua dit dd, ddc dilm dia chat thiiy vdn, lupng mira trung binh ndm, boat ddng phd huy ciia diit gdy hoat dpng (mdt dp dlit giy vd ddi dnh hudng dpng lyc dirt gdy), dp che phii thyc vdt vd cdc hoat dptig kinh tl - xd hdi cua con ngudi (mdt dd giao thdng). M$t khde, vi^
djnh lupng cip dd nguy ca TLD Id kit qud cua sy tich luy cdc ylu td tdc ddng phdt sinh trupt Id dupc tinh theo cdng thutc sau [5,6]:
108
H(LSI)
Trong dd: H (LSI) - Id chi s6 nhay cdm vdi tnrpt Id, Wj - Id trpng s6 cia ylu t6 tiiii j , Xij - id gid trj ciia ldp thti i trong ylu td gdy tnrpt j .
Vi|c tfch hpp thdng tin trong mdi trudng GIS vdi phuong phdp phdn tfch da biln dd cho ph6p xdy dyng bdn di cdnh bdo nguy co TLD tr€n dja bdn vimg niii tinh Qudng Ngdi.
Nhu v|iy, phucmg phdp khdo sdt thyc dia kit hpp vdi phdn tfch cdc dit lifu viln thdm Id quan trpng, bdi IS cd xdc ldp chi tilt hiln trang tai biln TLD mdt cdeh day du, chfnh xdc thi mdi cho kit qud phdn vimg cdnh bdo nguy co TLD dat dp chinh
xdc cao vd cd y nghia thuc tiln. ung dung phuong phdp phan tfch so sdnh cdp vd phdn tich khdng gian trong mdi trudng GIS dl phdn vimg canh bdo nguy CO TLD se ddp ung dupc nhu cau thuc tien ddt ra, ldm CO sd khoa hpc cho phdn vimg quy hoach phdt triln ben vung kinh te - xd hpi cdc huyen mien nui ndi riing, tinh Qudng Ngdi ndi chimg.
3. Ket qud nghiin ciru
3.1. Hi4n trgng trugV I& dat & cdc huy^n miin nUi tinh Qudng Ngai
Tren co sd tdng hpp cdc kit qua khdo sdt chi tilt ngodi thyc dja vd kl thira tdi lieu trong nhihig ndm vira qua da cho phep xac lap 809 khdi trupt Idn nhd, phdn bd tren dien tich 3245 km^ ciia 6 huyen mien niii tinh Quang Ngai {hinh 1, 2).
14*30'45*-1608195
Hinh 2. Bdn dd mdt dd TLD cdc huy$n mi^n nui tinh Qudng Ngdi
- Cac khdi tnrpt phdn bd vdi mat dp trung binh Id 10-12 khdi trupt/lOkml M^t do TLD Idn, dat gid tri >14 kh6i/10km^ phdn bd d cac xd Trd Son, Trd Ldm vd Tra Thiiy, huyen Trd Bdng; Trd Qudn, Trd Ldnh, Tra Thp, huyen Tay Trd; San Bao, Son Thuy, Son Ky, huyen Son Ha; San Bua, Son Miia, San Mau va San Tdn, huyen San Tay; Long Son, Thanh An va Long Mdn, huyen Minh Long; Ba Dpng, Ba Cung, Ba Chiia, huyen Ba To. Mat dd TLD <8 khdi/lOkm^ phdn bd rai rdc d San Tdy, Son Hd, Minh Long vd Ba Ta, Mat dd TLD thip nhdt, <4 khdi/lOkm^ phdn bd d cdc xa Ba Xa, Ba Trang, Ba Khdm, huyin Ba To, Long Mai, Long Hiep, huyen Minh Long, Son Bua, San Liln, Son Lap, huyen San Tay, Trd Biii, Tra Tan, Trd Binh, huyen Tra Bdng. Trupt Id dat phan bd chu yeu thdnh nhiing dai cd mat dp Idn, chay dai theo cdc phuong a vy tuyen, a kinh tuyen va DB-TN, Trong dd ndi lin cdc dai: Trd Thanh - Trd Hipp - Trd Thiiy - Tra Giang, Trd Ldm - Trd San - Trd Phii;
Son Bua - Son Miia, San Tan - San Mdu, Son Bao - Di Ldng - Son Thiiy - San Ky, Ba Vinh - Ba To - Ba Bich - Ba Li vd Ba Dpng - Ba Cung - Ba Chiia - Ba Vi.
- Hau het cac huyen mien niii linh Qudng Ngdi deu dien ra trupt Id, phd huy nhilu doan dudng giao thdng, rudng nuang, hoa mdu, cdng trinh kinh le dan sinh, anh hudng tryc tilp din hdng trdm hp dan dja phuang. Q huyen Tra Bdng, TLD tap trung thanh ddi keo ddi theo phuang d vy tuyen: Trd Hiep - Tra Thiiy - Trd Giang, Tra Lam - Tra Son - Trd Phil. 0 Tra Thiiy, trupt Id pho bien xay ra d dp cao 200 - 250m, dp ddc >35°. Khdi trupt d Trd Thiiy dien ra tren sudn ddc >35°, cd chieu rdng 40m, dai 120m, sau 5 m trong vd phong hod ddy I5m {dnh /). Trupt Id ddt xay ra d Trd Ldm, trong vd phong hda vdi chieu ddy 15-20m, khdi trupt rdng 50-70m, dai 80-IOOm, keo dai dpc theo sudn niii, pha hiiy doan dudng TL622 {dnh 2). 0 thdn Trd Xanh, xa Tra Lam, vet nirt tren niii Xo dai 50m, rdng 0,8m va sau 0,3m da lam cho 21 hd ddn vdi 90 nhan khau sinh sdng dudi chan niii phai di ddi di noi d mdi. Tai huyen Tay Trd, TLD phdt hinh thanh dai cd phuang d vJ tuyin Trd Khi - Trd Quan, d kinh tuyen Tra Lanh - Trd Thp - Trd Trung. Tai thdn Tra Ich thupc xd Tra Lanh, TLD phd hiiy TL626, anh hudng tryc tiep den 45 hp ddn sdng d chdn niii, TLD phd huy taluy duang vd k6 chdng trupt TL626 {dnh 3). Tai thdn Bdc Duang, xd Trd Thp, TLD phd hiiy doan ducmg TL626 ddi khoang 1,5 km {dnh 4) Ngodi ra, tai thdn Trd Reo,
Trd Nilu vd 06 Rd thupc xa Trd Phong, TLD Iam dnh hudng tryc tilp din gin 70 hd ddn sdng d gin dd. Tai khu vyc niii Khi, cao 1.000m d thdn Bdng va thdn Tdy, xd Trd Son, vdo ndm 1999 da xuit hiln bdn vit nut ddi 200 - 300m, hinh thdnh khdi trupt rdt Idn, de dpa tinh mang vd tdi san ciia 33 hp ddn sdng dudi chan mii va budc hp phdi di ddi. O huyen Son Tay, TLD hinh thdnh ddi cd phuong a kinh tuyin Son Bua - San Miia - Son Tdn - Son Mdu. Nirt dit klm theo trupt Id xdy ra d niii Md Rdi, xa San Tdn, d thdn Td Bl, xd San Bua dd anh hudng din 20 hd ddn sinh sdng d dudi chdn mii. 6 huyen- Son Hd, TLD tdp trung thdnh ddi klo ddi theo phuang d kinh tuyin: Son Bao - Di Ldng - Son Thuy - Son Ky, Son Ha - Son Giang - Son Cao. Khdi trupt d xa San Bao cd quy md Idn, chiiu rpng 70m, ddi 100m vd cao 20 m {dnh 5).
Trupt Id hdn hpp trong ddi dap v& vd vd phong hod day tdi 25-30m. Khdi trupt tai xd Son Ky dien ra d sudn mii cao 200-300 m, ddc 35-45°. Khdi trupt cd quy md Idn, chilu rpng 300m, ddi 80m vd cao 30m {dnh (5). Trupt Id hdn hpp trong ddi dap vd, vd phong hod day tdi 15-20m. Ngodi ra, d xdm Td Dieu, thdn Td Biu, xd Son Thiiy dd xuit hipn nhiiu vit nirt vao ndm 2004, dai hang trdm mit, klm theo Id nui rit nguy hilm cho cu ddn sdng dudi chdn niii. Cdc diem xdy ra nirt Id mil manh nhu d thdn Td Cdn, xd Son Hdi, Idng Bd Riy, x3 Son KJf, ndi Md O, xa Son Ba, lang Bd, thj trdn Di Ldng. d huyen Minh Long, TLD tdp trung thdnh ddi d kinh tuyen Long San -Long Mai vd phuang DB-TN Thanh An - Long Mdn. Trin dja bdn cdc x3 Long Son, Long Mdn vd Thanh An, TLD diln ra gay nguy hiem cho gan 200 hp dan dmh cu d chdn niii liln kl. Trin ddi Nudc Dep, thdn Dipp Thupng vd ddi Met thdn Nudc Nhieu, xd Thanh An, mit ddt kem theo trupt Id Idn da dnh hudng tryc tiep den gan 70 hd ddn. Tai xd Long Son, nirt nui kfim theo Id niii xay ra d Gd Chanh, Gd Nay, Gd Ddi, Lac Son vd Difp San dd anh hudng tryc tiep den 150 hd dan sdng d dudi chan mii, bupc phai di chuyin.
Nut dat k^m theo trupt Id d sdng Liln, tai cdc xdm Ddng Vdn, Kala vd Gd Pdc da anh hudng tryc tilp den 22 hp dan bupc hp phai di ddi. Tren dja phdn huyen Ba To, TLD hinh thdnh ddi cd phuong d kinh tuyin Ba Vinh - Ba To - Ba Bich - Ba Le, ddng bic - tdy nam Ba Dpng - Ba Cung - Ba VI.
Cdc dilm nirt ddt kem theo TLD gdy nguy hilm cho cu ddn dja phuang tdp trung dpc theo thung lung sdng Re vd sdng Trd Nd. Khdi trupt d xd Ba Chua cd quy md Idn, ddi 70m, rpng 100m, sau 15m
110
(dnh 7) da tdc ddng tryc tilp din nhd ddn d dudi chdn sudn niii. T?i xd Ba Vinh, nut dit kfem theo Id niii diln ra d cdc xdm Pha Cun, Gd D§p, Chin Cdng, da dnh hudng tryc tiep den gin 200 hd ddn s6ng lien kl (dnh 8). Tai thdn Sudi Loa, xa Ba Ddng da xuit hiln vit mit mii ddi 200-300ni, ch^iy ddi tiieo phuang DB-TN, klm theo syt bac chenh cao din S-7m, dd dnh hudng din 50 hd ddn sdng d dudi chdn nfii. T^ii thdn Va Chdy vd Ddng Lau thudc xa Ba LI, ntit dat kem theo Id nQi phdt triln theo phuang DB-TN vd d kinh tuyin, tuy nhign chi dnh hudng din 8 hd dan sdng liln ki.
- Da sd cdc diem trupt Id diu phdn bd trin sudn nui cd dp cao tii 200 din 500m din gin 1000m, dd ddc 25-35°. Vdt lifu trupt chu yeu Id sdn phim phong hod cua cdc dd biln chit: goneis, phien kit tmh vd trim tich bd rdi hon hpp aluvi, proluvi vd deluvi. Tnrpt Id ddt diln ra trong cdc kilu vd
phong hod ferosialit, sialferit vd trim tich bd rdi;
nai cd dd che phu nhd <20% vd ho^t ddng kinh tl phdt triln, giao thdng dupc xdy dung, md mang nhu: d cdc huyen Tdy Trd, Trd Bdng, Son Tdy vd Son Hd. Trupt Id ^ t diln ra vd phat triin khd m^nh ml dpc cdc ddi diit gdy hoat ddng Sdng Trd Bing, Sdng Re, Ba Dpng - Ba Vl, dit dd bj cd ndt, xilt Ip, v6 vun vd cd dd dfnh kit yiu. Dd chinh la nhihig ddi anh hudng dpng lyc ciia cdc ddi dirt gdy ho^t ddng vdi mdt dd khe mit, diit gdy Idn
> 1 km/km . Phin Idn cdc dilm trupt Id diu diln ra trong thdi gian miia mua (tir thdng 8 din thdng 11) vd d nhiing ncri cd lupng mua trung binh ndm Idn
>3000mm/ndm. Trong thdi gian nay, trupt Id dien ra manh me khdng chi vl quy md khdng gian, kich thudc khdi trupt ma cd tan sudt xuit hifn. Mdt khde, trupt Id klm theo cd lu quit - lu biin dd dd gdy nin hdu qua Idn cho ddi sdng cita cu ddn dia phuang.
Anh 1 Tru'ol lij dai d xa Tra lliuv '•..•••••i (anh Pham Van Hung, nam j'JO'j
2 Truot 16 dai Iren taluy du'ong TL622 tai xa Tra Lam huyen Tra Bong (anh Pham Van Hung nam 2009)
Anh 3. Tiupl 16 dai t^i xa Tia Lanli. huy^n Tay Tra (dnh Ph^m Vdn Hung, ndm 2012)
moi io dai dnh ig a26, xd iid iiiv. iiuye (anh. Pham Van Hung, nam 2012)
Anh 7 Truot Id 6ht, it xa Ba Chiia, huyen Ba To (dnh Pham Van HCing, nam 2012)
Anh 6. Jrwat Id dlit a xa Ba Vmh, huyen Ba To (anh Pham Van Hiing, nam 2012) 3.2. Cdc yiu tS ldc dgng phdt sinh TLB & cdc
huy4n miin nui tinh Qudng Ngai
Trupt Id Id qud Irinh di chuyen xudi ddc ciia v$t lieu dat dd, Qud trinh trupt Id dupc bat dau khi the can bing ddng ciia sudn ddc bi phd va do ldc ddng ciia cdc yeu td ty nhien vd xd hpi. Cdc cdng trinh nghiin ciiu vl TLD trin thi gidi, ciing nhu d nudc ta trong thdi gian qua dd khing dmh, hipn tupng TLD hinh thdnh vd phdt triln do tdc ddng ciia nhieu yeu td khde nhau [ 1, 4-6], trong dd, yeu td dd ddc sudn Id quan trong nhdt, kl lilp la ylu td lupng mua trung binh ndm vd cdc ylu td khac tiep theo cd vai trd thti yeu. Kit qud nghiin ciiu cua cdng trinh ndy, d viing miln niii tinh Quang Ngdi, TLD hinh thdnh vd phdt triln dudi tdc ddng ciia 11 ylu td thupc cdc nhdm yeu td: dja mao, khf h$u thiiy vdn, dja chat, kien tao vd nhdm yeu td che phu thyc vat vd ho^it dpng kinh te ciia con ngudi. Trong do,
dd ddc sudn ddng vai trd rdt quan trpng, cd quan hi tryc tiep din sy thay ddi hp sd dn djnh sudn ddc, rdi tilp din cdc yeu td khde nhu: lupng mua trung binh ndm, kilu vd phong hod, ddc dilm dja chat cdng trinh, dja chit thuy vdn, ddi anh hudng dpng lyc dlit gdy ho^t dpng, m§t dd diit gdy, dd che phu thyc vdt, mdt dp chia cdt ngang, m$t dd chia cdt sau va m$t dd giao thdng. Cdn cii vdo mdi quan hi giiia miic dp trupt Id vdi d^c diim timg ylu tl trong tdng thi cdc ylu td, di tii dd cho diim timg yeu td tdc ddng phdt sinh TLD d viing niii tinh Qudng Ngdi.
Nhdm yeu to dja m^o:
Ylu td dp ddc sudn Id quan trpng nhit trong phdt sinh TLD, do dd cho 9 diem. Kit qua nghiin ciiu cho thiy {bang 1), tren b|c dd ddc 35°-45*', TLD diln ra Idn nhit. Tilp theo, miic dp TLD ft 112
hon chu yiu diln ra » b j c dO d6c 25°-35° v» 15"- 25°. RiSng b j c d J d6c >45°, TLD diln ra rft it v i qu^ trlnh dia chit dfng l^c ph6 biln l i d6 IA [4, S].
C i c bjc df d6c 35-t5°, 25-35°, 15-25°, <15° v i
>45° c6 dilm tuong iing l i 9 , 7 , 5 , 3 v i 1.
B i n g 1 . T h i n g M t r u ^ t Id* v i d i 4 m s 6 theo c i p d o ddc aia h i n h tr c i c h u y f n m l ^ n nOi Onh Q u i n g Ngat BO dAc
<15 0
15-25 25-35 35-45
>45 SAUiAfii truot Ifr 295 324 122 33 2
OlOntfch (km^
1355,5S 1217,74 535.50 118.88 12.G0
M^dObVTtier (khfii/IOcW)
22 27 23 2B 17
Di^msd 3 7 5 S 1 Y I U t6 phdn cdt^sau cd vai trd trong phdt sinh vd phdt triln trupt lo. Miic dd trupt Id Idn nhit tap trung d viing cd mdt dp chia cdt sau trung binh; tilp theo Id mdt dp chia cdt sdu Idn hem {bdng 2). Do dd, vai trd ciia y l u td ndy vdi TLD d miic dp nhit dinh vd cho 1 diim. Diim ciia cdc bdc dp chia cdt sdu 25 - 50m/km^ 50 - 100m/km^ 100 - I50m/km^ <25 m/km^ vd >150m/km^ tuang irng Id 9, 7, 5, 3 vd 1.
Bdng 2. T h 6 n g M t r i n / t Id- v d d i ^ m s 6 theo m^t d d chia c i t sdu 6" cdc huyfin m i ^ n n i i i t i n h Qudng Ngdi M3t d$ chia cA\
s3u (m/hm'l
<100 100-190 ig0-2B0 280-370
>370
sT rtSir
trvutlfr 296 ee 26B 108 35
Di^n ticn (km') 381,33 851,43 1028,21 555,20 245,S0
Mat dl) tn/ol 1*
[kh6i/100km') 0,17 0,34 0,26 0,19 0,13
niim s6 3 9 7 5 1 - Vlu t6 phdn cdt ngang cd vai trd thii ylu trong phdt sinh trupt Id {bdng 3). Mire dd trupt Id Idn nhit phdn b l d viing cd mdt dp chia cdt ngang Idn
>2000m/km^ tilp theo Id Wing cd m$t dd chia cdt ngang 500 - I000m/km^ 1000 - I500m/km^ 1500- 200m/km^. Do v$y, diim ciia cdc c i p dp mdt dp chia cdt ngang >2000m/km^ 500-I000^l/km^
1000 - I500m/km^ 1500 - 200m/km' vd <500 m/km^ tuang img Id 9, 7, 5, 3 vd I.
Bdng 3. T h d n g kA t n i ^ I d v d d i i m s i theo m | t d $ chia c i t n g a n g fr cdc h u y ^ n mi4n nui t i n h Qudng Ngdi
•^^fn « l l " MStaetrugHd Difim triKTt ,^„3, (kh6i/l00km'} s6 Mat ai chia
cit ngang
(m/km') (km')
<500 207 1134.55 500-1000 161 583.01 1000-1500 171 629.82 1500-2000 108 471,56
>2000 129 425,76
Nhdm ySu id khi h^u thuy vdn:
v l u t6 lupng mua, cy thi d khu vyc ndy Id xem x^t vai trd ciia y l u t l lupng mua trung binh ndm
(bang 4). Ddy Id yeu td quan trpng thii 2 sau yeu td dd ddc- Do vdy, diem cho vai trd cua yeu td lupng mua tnmg binh ndm la 7. Phdn tfch hiln trang TLD trdn dja ban vimg mii tinh Qudng Ngdi cho thdy, khu vyc cd lupng mua trung binh ndm >3500 mm cd miic dp trupt Id manh nhat; tilp theo Id khu vyc cd lupng mua tnmg binh nam 3000 - 3500 mm va 2500 - 3000 mm. 0 nhirng noi cd lupng mua trung binh ndm <2500 mm thi trupt Id xdy ra it nhat. Do dd, cdc bdc lupng mua trung binh ndm >3S00 mm, 3000 - 3500nmi/ndm, 2500 - 3000 mm/nam vd
<2500 nun cd diim tuang iing Id 9, 7, 5 vd 3.
Bang 4. Thdng ke tnpnt Mr vk Sikm s& theo c i p lu>o>ng m m trung binh n i m 6' CcIc huyen m i i n nui tinh Quang Ngai Uwngmira g ^ ^ D J ^ Mata5tn.<«l* „ . „ . .
;;^;^g^^;g m M i * ,;;^, oThdi/iookm'} ^"^"'^
<2500 2500-3000 3000-3500
>3500
434,15 931,37 1344,12 537,12 N h d m y e u t o dia c h i t
Yeu td vd phong hoa (kieu vd phong hod) vd trim tich De Tii Id ylu td cd vai trd thir tilp theo trong phdt sinh trupt Id dat {bang 5). Bdi le, vd phong hod va trim tich bd rdi D? Tir cung cdp ngudn vdt lipu cho qud trinh trupt Id d vung niii tinh Qudng Ngdi. Phdn tich tdng hpp mdi quan h | giiia mire dp trupt Id vdi cdc kieu phong hod vd trim lich D^ Tir cho thay, yeu td ndy cd vai trd nhdt djnh vd cho 5 dilm. Trim tich D? tit bd rdi hdn hop (aluvi, proluvi, deluvi) d khu vuc ndy thudng cd chieu day Idn (tir 15 den 20m) rat thu^n lpi cho trupt Id phal trien, do dd, nd cd miic dd trupt Id Idn nhit; tiep den la kilu vd phong hod sialferit (thudng cd chilu day ni 15 den 20m) cd mire dp trupt Id thap hon. Tilp din kilu vd phong hod ferosialit (chieu ddy thudng dat tir lOden 15m) vd saproit (chieu day thudng lii 5 din 10m) cd mire dd trupt Id thap ban. Do vay, diem ciia cac kilu vd phong hod vd tram tich De Tir tuang irng nhu sau:
trdm lich De tu hdn hpp bd rdi - 9, sialferit - 7, ferosialit - 5, saproit - 3, alferit - I,
Bang 5. T h 6 n g ke t r u v t Icr vd diem s 6 theo k i i u v d p h o n g hod v d t r i m t i c h De TLF dr cdc huyen m i £ n niii
t i n h Quang Ngai
Kieu ¥0 So diem Dien tfch Mat iIo lnn?t Icr n i™ =*
phong hoa tnwytlcr (Itm'} (kh6</100km') " ' ^ " ' ^ Alferit 6 65.83 10 1 Trdm lich b *
Tin 167 461,71 36 S Ferosialit 387 1785,56 22 5 Saproit 115 612,64 19 3 Sialfent 101 315.94 32 7
Ylu td dja chit th^ich hpc cdng hrnih cd vai trd thii tilp theo, thi hi^n d dd ciing, dd bin chdc cua cdc nhdm dit dd trong phdt sinh TLD {bang 6).
Phdn tfch ddnh gid vai trd ciia yiu td ndy trong phdt sinh trupt Id cho thiy, yeu td nay d vai trd nhat djnh vd cho 3 diem. Tren cdc tram tich bd rdi hSn hpp (apd), TLD xdy ra manh nhit. Trupt Id dit xdy ra ylu han trin cdc thdnh t^o biin chit ttr dd magma, roi din dd biln chit trim tich. Do dd, dilm ciia cdc nhdm da trim tich De Tii hdn hpp bd rdi, dfnh kit rit yiu (apd), biln chit magma, biln chit trim tich, granit, basalt tuang ung Id 9,7, 5,3 vd 1.
Bdng 6. Thdng k6 t n r p t \b vd diem s 6 theo y£u td dja c h i t th^ch hpc cdng trlnh (theo nhdm d i t dd)
6 cdc huy^n m i l n niii tinh Quang Ngai S6
dilm truytld-
Dien tich M|t dg tnnrt Mr Oiim P(m^) {kh6i/l00km') s6 edt>asatt-
rdtci>ng o a bidn c h ^ trim tich - cCmg Da granit - niia c<>ng Trim tich bff rffi oa bi6n chat magma - nu'a ci^ng
609,59 466,89
Vai trd ciia ylu td dia chdt thiiy vdn trong phdt sinh TLD thi hipn d miic dd chiia nudc {bang 7).
Tuy nhiln, ddi vdi qud trinh TLD d khu vuc miln niii tinh Qudng Ngdi cho thdy, mdi quan he giiia miic dd trugrt Id vdi miic dp chiia nudc ngam d miic dd nhit djnh. Mire dp trupt Id Idn nhdt ndm trong ddi gidu nudc; tilp theo Id ddi rit n ^ l o nudc, tham chi khdng chira nuoc. Do vay, ddnh gid mdi quan hf giita miic dp trupt Id vdi miic dp chiia nudc cho ylu td nay 3 diim. Dilm cua cdc cdp dp chira nudc ngdm gidu nudc, rit ngheo nudc, khdng chiia nudc, chiia nudc trung binh vd ngheo nudc tuong img Id 9, 7, 5, 3 vd I.
Bdng 7. Thdng kS b v p l I d vd d i l m s6 theo mOc dd chira mrin n g i m cua d i t dd d cdc huyen m i l n niii
tinh Qudng Ngai
GO chi>a nu'd'c didm Di$n tich Bi&m sd Gidu nu'd'c {qh)
Chira nu/dc tnjng binh (qp) Ngh^o nu'd'c (bz) Rdt nghto nird^(bc}
Khdng chi>a ntfircjioi)
Nhdm y l u t6 kiln t^o:
Ylu t6 m$t d$ dlit gdy cd vai trd nhit djnh trong phdt sinh TLD {bang 8). Phan tfch ddnh gid theo miic dd trupt Id cho thiy, ylu t6 ndy cd vai trd nhit djnh vd cho S dilm. Viing cd m^t dd diit gdy tit >0,576km/km^ cd miic dd trupt id Idn nhit, tilp theo Id vimg c6 m§t dd 0,144 - 0,288kni/km^ 0,288 0,432km/km^,... Viing cd m$t dd diit gdy
<0,144km/km^ cd miic dp trupt Id thip nhit. Dilm cua cdc bgc m^t dp dut gdy >0,576kni/km^0,144- 0,288km/km^ 0,288 - 0,432km/km^ 0,432 - 0,576km/km^ vd <0,144km/km^ tuang feig Id 9, 7, 5,3 vdl.
Bdng 8. Thdng kd t n r p t Id* vd diem s d theo c i p in$t d$
dirt gay if cdc huyen m i l n niii tinh Qudng Ngdi M3t<l$di>t
gSy (km/km*)
<0.144 0,144-0,288 0,288-0,432 0,432-0,576
>0,576 dilm t n w t 6 23 347 183 217
Dien tich (km')
178,61 54,48 1436,08 1083,25 493,78
Mat<l9 truvtlff {khoi/IOOk^
3 42 24 17 44
sA 1 7 5 3 9
YIU td ddi dnh hudng ddng lyc dlit gdy hogt ddng cd vai trd nhai djnh trong phdt sinh TLD {bang 9). Phdn tich mdi quan h | ndy cho thiy, yiu td ddi dnh hudng dpng lyc diit gay hoat ddng cd vai trd nhit dinh vd cho 3 dilm. Miic dp trupt Id Idn nhit tap trung d cdc ddi dpng luc diit gdy hoat dpng b$c 1 d khu vyc nghien cixu, tilp theo Id cdc ddi dlit gdy b$c 2, bdc 4, bdc 3 vd cao han. Dilm ciia cdc bdc ddi dnh hudng ddng luc dirt gdy tuong imgld9,7,5,3vdl.
Bdng 9. Thdng kS tru-pl Id* vd d i l m s6 theo c i p ddi dnhhi/drng ddng \\JK 0<»t gdy it cdc h u y f n m i l n nui tinh Qudng Ngai ( n h i m Idn giOa 2 cot dien tich vd sd
d i l m t r u ^ id*) Cdpil$
hifd'ng d^ng li/c diJtgay Baccao Baci Bac 2 Bac 3 Bac 4
s i dilm tnwtid' 195 138 198 217 28
Dign tfch (km^
1461,37 171,83 647,87 915,92 98,5
Mdt ad triKjl Id- (kh6i/100^
13 80 31 24 28
Bilmsl 1 9 7 3 5 Nhdm yeu to che phu thi^c v | t va hogt dpng kinh t i cua con ngirdi:
Ylu td ldp phu thyc v^t (cy thi Id dp che phu diyc v§t) cd vai trd nhit djnh trong phdt sinh TLD
d khu vyc ndy {bang 10). Tren thyc t l d vimg mii tmh Qudng Ngdi, viing cd dp che phii k l m (<20%) - vimg dit d khu dan cu vd cdng trinh kinh t l ddn sinh, qud trinh TLD diln ra manh m l nhdt. Vimg cd dp che phii tdt (>90%) - viing d i t riing ty nhien, TLD dien ra ylu nhit (bang 10). Nhihig viing cd dd che phu trung binh (20-45%) - viing ddt sdn xuit ndng nghiep vd ho^t ddng xdy dyng, phdt trien giao thdng, thiiy dipn, thuy Ipi, mire dd TLD dien ra ciing khd m ^ . Do dd, phdn tfch mdi quan h | ciia ylu td ndy vdi qud trlnh trupt Id cho thdy, vai trd cua y l u td ndy d miic thip vd cho I diim.
Dilm cua cdc c i p che phu thyc v$t: <20%, 20- 45%, 45-70%, 70-90% vd >90% tuong img Id: 9, 7, 5, 3 v d l .
Bang 10. T h i n g k i tnrat Of vi diem s l theo y l u t l do che phii th^rc vat d* cac huy^n m l i n nui tinh Quang Ngai Bg che phu
thi/cv5il(%)
<20 20-45 45-75 75-90
>90
Sddi^m truvtld' 119 505 91 29 32
Dien tich (km')
316,50 1825,81 483.70 152,32 461,70
Mai do Inrcrl \a (khii/lOO^)
37 28 19 18 7
Oilmsd 9 7 5 3 1 v l u t l ho9t ddng kinh t l cua con ngudi tdc ddng tryc tiip vdo phdt sinh TLD Id hoat ddng xay dyng m^ng ludi giao thdng. Khi xdy dyng giao thdng, con ngudi tdc ddng true tilp, Idm thay ddi tr^ng thdi mdi trudng {bang 11). Trong dd, viec thay ddi dd d i e sudn, Idp phii thyc vdt,... dd ldm cho qud trlnh sudn cd dieu kien phdt triln, trong dd cd TLD. Do dd, mat dp giao thdng cd vai trd nhit djnh trong phdt sinh TLD d cdc huyen mien niii tinh Qudng Ngdi, Phdn tfch ddnh gid hien trang
TLD vdi ylu td mdt dp giao thdng cho thiy, d nhiing noi cd mat dp giao thdng Idn, TLD cung xdy ra vdi mdt dp rdt Idn. Do dd, phdn tich mdi quan he ndy cho thdy, vai trd ciia yiu td mat dp giao thdng cd miic dp nhdt djnh vd cho 3 dilm. Dilm cua cdc cip mdt dd giao thdng >7,054kni/km^ 5,075 - 7,054km/km^ 3,096 - 5,075knVkm^ 1,117 - 3,096 km/km^ < 1,117 km/km ^ tuong ling Id 9,7,5,3 vd 1.
Bang 11. T h i n g k e t r v g U v v a diem s l theo y l u t l mat dd giao thdng 6- cAc huyen m i l n niii tinh Q u i n g Ngai Mat dd giao S i d i i m Di^n tich
thdng (km/km') tnrcfi Id (km^) Maide tnrpi Id" Diem si (khoc/IQO') 5.075-7,054
<1.117 1.117-3,096 3,096-5,075
>7,054
163 140 155 227 91
576,52 812,83 779,07 875,05 202,59
0,28 0,17 0,20 0,26 0,45
7 1 3 5 9 Nhu vdy, d vting niii tinh Qudng Ngai, TLD hinh thdnh vd phdt trien bdi tdc dpng ciia 11 yeu td thanh phan. Trin co sd dilm cQa 11 ylu td nlu tren, cho phip xdc djnh trpng sd ciia mdi yeu td bdng phuang phdp phdn tich so sdnh cdp ciia Saaty (Saaty's Analytical Hierarchy Process- AHP), Kit qua tinh todn cho thay {bdng 12), trpng sd ciia ylu td dp ddc Id 0,209; lupng mua Id 0,163; vd phong hod, dja chit cdng trinh vd mat dp dirt gdy diu Id 0,116; dja chdt thuy vdn, ddi dpng lyc dirt gay, mat dp giao thdng diu la 0,070; mat dp chia cdt ngang, mat dp chia cdt sau vd dp che phu thyc vat deu Id 0,023. Bdn dd nguy co TLD thdnh phdn duoc xay dung trin co sd phdn lich theo timg yeu td tdc ddng ndi trin.
Bdng 12. Trpng s l ciia yeu t l tdc d^ng phat sinh trtryt Id* 6* cic huyen miln nui tinh Qudng Ngai VlutI
Trpng sd EM 0) 0,209
Lm (7) 0,163
vph (5) 0,116
Mddg (5) 0,116
Occt (5) 0,116
OOv (3) 0,070
Ddi (3) 0,070
Mdcs (1) 0,023 (1)
0,023 Dcplv
(1) 0,023
Mdgt (3) 0,070 Chij thich. Dd- D$ d i e , Lm- Lu'png mua trung binh nam, Vph- Vd phong hoa, Ddi- Ddi dpng lyc dut gSy, Mddg- Mgt d0 d u l gdy, Occt- Dja chdt cdng trinh, Dctv- Dia chat thuy vdn, Mdcn- Mdt d$ chia c i t ngang, Mdcs- Mat dp chia cdt sau, Dcptv- D ( che phij thpc vdt. Mdgt- M^t d$ giao thong.
3.3. Phdn viing nguy ca trugft l& dh cdc huy$n miin nUi llnh Qudng Ngdi
Bdn dd phdn vimg cdnh bdo nguy co TLD uen dja bdn cdc huyfn miln nui tinh Qudng Ngdi dupc xdy dyng bdng phuang phdp phdn tich khdng gian trong mdi trudng GIS. Dd Id sy tich hpp 11 ban dd thdnh phin theo cdng thuc sau:
LSI (H) - 0,209 Bd_Dd + 0,163 x Bd_Lm + 0,116 X Bd_Dcct + 0, H 6 >^ Bd_Vph + 0,116 " Bd_Mddg + 0,070 " Bd_Ddl + 0,070 x Bd_Dctv + 0,023 x Bd_Mdcn + 0,023 x Bd_Mdcs -i- 0,023 Bd_Dcptv + 0,070 Bd_Mdgt.
Trong dd: LSI - bdn dd nguy ca trupt Id dit, Bd-Dd: ban dd dp ddc, Bd_Lm: bdn dd lupng mua
trung binh ndm, Bd_Dcct: ban dd dia chit cdng trinh, Bd_Vph: bdn dd vd phong hod vd trim tfch D^ tii, Bd_ Mddg: bdn dd m$t dd diit gdy, Bd_Ddl:
bdn dd ddi ddng lyc diit gdy, Bd_Dctv: bdn db dja chit thiiy vdn, BdMdcn: bdn dd m^t dd chia cdt ngang, Bd_Mdcs: bdn dd mat dp chia cdt sau, Bd_Dcptv: bdn dd dp che phii thyc v^t vd Bd_Mdgt - ban dd mdt dp giao thdng.
Bdn do cdnh bdo nguy ca TLD dupc tich hpp tir 11 ban dd thdnh phin thi hien bdng gid trj sd vdi moi pixel cd rapt gid trj nguy co trupt Id tuong img. Do dd, de xdy dung bdn dd phan viing cdnh bdo nguy co TLD, cdn phdn chia cac gia trj nguy CO trupt Id tren bdn dd gid trj sd thanh cdc cip nguy CO phil hpp. Nguyen tdc vd phuong phdp phdn chia cdc cap nguy co tir cac gia trj nguy ca trupt Id nhu sau: ngudng dl phan cdp ban dd trupt Id gid trj sd dupc lya chpn sau khi thuc hien phdn tich xii ly thdng ke, xay dyng dudng cong tich luj xdc sudt (bilu dd thdng kl tich luy nguy co TLD gid trj sd). Kel qua xii ly thdng kl cho cdc thdng sd sau: gid trj tdi thieu Xmm^ 2,8680, trung binh Avg - 5,4559, tdi da X^^^= 8,7660, dp lech tieu chuin StD = \,2617 {hinh 3, bdng 13).
1400- 1200- 1000-
•S 5. 800- J 600-
400- 200-
1 ilil l U
4 S Gl tn 8 9
Vipc phdn chia s6 lupng cip nguy co TLD dugrc iya chpn theo cdng thiic:
Ax = (X„^- X,nm>'n; ttong dd: n- s6 cip cin phdn chia.
Theo nguyin tdc neu trdn, d cdc huyen miln niii tinh Qudng Ngdi, cho phip lya chpn, phdn chia 5 cip nguy co (n = 5, Ax = 1,1796): rit thip, thip, trung binh, cad vd rit cao. Cdc trj sd tuong dug ciia cdc cip nguy ca: rit thip: <4,0476, thip: 4,0476- 5,2272, trung binh: 5,2272-6,4068, cao: 6,4068-"' 7,5864 vd rit cao: >7,5864. Cip nguy ca rit thip thi hiln d viing dd rit it xay ra trupt Id, hodc cd xdy ra vdi khdi lupng rit nhd. Cdp nguy co trupt Id thip phdn dnh d viing dd trupt Id cd thi xdy ra ft, ho$c xdy ra vdi khdi luong, quy md nhd. Cip nguy CO trupt Id trung binh Id viing cd thi xay ra trupt Id vdi quy md vd khdi lupng vira. Cip nguy ca trupt Id cao la viing cd the xdy ra trupt Id nhilu, quy md vd khdi lupng Idn. Cap nguy co trupt Id rat cao Id viing cd thi xay ra trupt Id rit nhiiu, quy md vd khdi lupng rdt Idn.
Bdn dd phdn viing cdnh bdo nguy ca TLD viing mii tinh Quang Ngdi tj-le 1:25,000 thi hien d 5 cdp nguy ca khde nhau {bang 14, 15, hinh 4, 5).
Bang 14. T h i n g ke dien tich theo cdc d p nguy c o TLD trfen dja bdn viing nui tinh Quang Ngai
Hinh 3 B i l u d l t h i n g ke phan bo nguy CCT TLD b cac huyen m i l n niii tinh Quang Ngai Bdng 13. T h i n g kS phdn bd gid trj nguy c c TLO b cdc
huy^n m i l n nui tinh Quang Nggi Ndi dung
Mm Max Tmng binh Od l|ch chuSn
Gidtn 2,868
8.76 5,4559 1,2677
Cdp d? nguy co' Rdt thdp Thdp Trung binh Cao Rdt cao
Bdng 15. T h i n g ke Di#n tfch (ha)
149251 213899 428861 256480 6086 cac c i p dd nguy
Phdn tram (%) 14,15 20,28 40,67 24,32 0,58 c a TLD Uieo dif n tich (ha) tirng h u y i n d* viing niii tinh Qudng Ngdi
Huyen BaTff Mmh Long ScrnHd So'n Tay Tr^ Bing ray Tra
Rdt thdp 8352 2584 2897 8807 1027 2187
Thdp 44245 11750 29133 25232 13428 11597
Trung binh 47065
6093 32178 3732 12721 16415
Cao 11818
792 11115 156 12635 2745
Rdt cao 73 0 11 0 S71 1
Tren dja Mn c^c huy^n miln nai tinh Qu^ng Ngai ph6 bifin lion ca 1^ viing c6 nguy ca TLD dr cip do trung blnli. Vung c6 nguy co tnicrt 14 trung binh chigm 40,67% difn tich t\r nhiln Idiu v\rc nghien cuu, phSn b6 chii yiu a c4c xa Ba Tifiu, Ba Vi, Ba T6, Ba Dinh, Ba Trang {huy?n Ba To), Son Thuqmg, Son Trung, Son Cao, Son Linh (huyjn Son Hi) va Tri Xinh, Tri Khe, Tri Nham (huyta TayTrJ).
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Hinh 5. Bi6u 66 cip ai> nguy co- TLO it cic huy^n mien niii tinh Quing Ngdi
Viing c6 nguy ca TLD a cip d$ cao chiim 24,32% di^n tich tu nhien khu vuc nghign ciiu, phan bo chii ySu a cic xa Ba Dong, Ba Cung, Ba Vinh, Ba Chiia, Ba Bich, Ba l i (huySn Ba Ta), Son Ha, Scm Giang, Di LSng, Sofn Bao, Son Thiiy, Son KJ (huy?n Son Hk) vi Tr^ Thiiy, Tri Son, Tri Hiep, Tr^ Lam (huy?n Tri B6ng).
Ving c6 nguy ca TLD d cip dO thip chi6m 20,28% di?n tich t\r nhign Idiu vuc nghien ciiu, phin b6 a c^c xa Ba Nam, Ba l i , Ba Xa, Ba Lien, Ba Diln (huygn Ba To), Son Nham, San Linh, Son Cao (huyen Son HEI) vi San LiSn, San L§p, Son Tinh (huyfn Son Tdy), m^t phan a cic huygn Tiy Tri, Minh Long vi Tri Bong.
Trong khi d6, vung nguy co truot Id rit cao chi chilm 0,58% dign tich tu nhien khu vuc nghiin ciiu vi phan b6 chii ygu 6 cic xS Tri Thiiy, Tra Lim, Tri Hi^p, Tri Son (huygn Tri B6ng) vi mot it ij Ba To, San Hi. Viing co nguy co trugt la rat thap chiem 14,15% dien tich tu nhien cua viing mii tinh Quing Ngai, ph&a bd tren dia bin cic huyen San Tay, Ba To vi rai r4c a cac huygn San Hi, Tay Tri vi Minh Long.
4. Kit lu^n
Cic huygn mien mii tinh Quang Ngai li nai dien ra trupt la dtt manh, hign da xic lip dugc 809 khoi trugt, chiing tao thinh nhung dai ch^y theo phuong i vy tuyen, i kinh tuyen vi DB-TN voi mat d§ kh6i truot dat 10-12 kh6i trugt/lOkml
Trugt 16 dat dien ra do 11 yeu t6 tic dpng phit sinh, trong d6 yeu to dp doc suon vi lugng mua trung binh nSm dong vai tro chii dao; tigp theo la cac yeu to vo phong hoi, dia chat cong trlnh, doi anh huong dong lire dut gay, dia chat thiiy vin, mat dd dlit giy.m^t dd chia cit siu, mat dg chia cit ngang, dg che phii thuc v$t vi mit do giao thong.
Bin do phan vimg canh bao nguy co TLD cac huygn mien mii tinh Quang Ngai dugc xay dung tren ca sd tich hgp 11 bin d6 nguy co TLD thinh phin bing phan tich khong gian trong moi tnidng GiS.
Trgn dja bin cic huyen mien niii tinh Quing Ngii, viing CO nguy co trugt Id trung binh chigm 40,67% dign tich tu nhign khu vuc nghien ciiu, phan bo d cic huygn Ba To, San Ha \k Tay Tra.
Viing c6 nguy co TLD d cip dO cao chiSm 24,32%
di?n tich t\f nhien khu v\rc nghign ciiu, phan b6 chii yeu a cic huygn Ba Ta, San HS vi Trk B6ng.
Ving c6 nguy ca TLD d cip dO thip chigm 20,28% dign tfch t^r nhifin khu vuc nghign ciiu, phan b6 d cic huygn: Ba Ta, Son Hi vi Son TSy, mOt phin d cic huygn TSy Tri, Mmh Long vi Tri B6ng. Vimg cd nguy ca trugt Id rit cao chi chilm 0,58% di^n tich tu nhign khu vuc nghign ciiu \k phan b6 chii ygu d huy^n TrS Bdng vi rii rSc d Ba Ta, Son UL Vimg c6 nguy ca trugt Id rit thip chigm 14,15% dign tich t^ nhign khu vvrc nghign cim, phan bd d cic huy^n San Tay, Ba To vi rai ric d cSc huygn Son Hi, TSy Tra vS Minh Long.
Vi^c phdng tranh tai biln TLD phSi dirge xic djnh li nhigm vu ciia timg ngudi, timg h0 vi mpi cip quin I^ xa hOi. Cin diu tu tang cudng m^ng ludi d^ bio trugt Id; dau tu nang cap trang thilt bi, he thdng xii IJ thdng tin; thiet ISp cSc hg thdng cinh bSo tign tign, cung nhu xay dvng cic phuong in ciiu hp ciiu nan nhim giam thieu thigt h^i do tai bign giy ra d nhihig viing cd nguy co cao. Trgn pham vi cac khu vvc dan cu, cdng trinh kinh tl - xa hdi quan trpng di xiy ra tai bien ho^c dang bi tai biln de dga nhit thilt phai co bien phip phdng trinh c^ thg.
TAILI$UDAN
[1] Le Muc Dich, 2001: Kinh nghidm phdng trinh vi kigm soit tai bien dja chSt, Nxb. Xay Dimg, Hi Npi. (Dich tu tilng Trung Qudc).
[2] Pham Vdn Hiing. 2011: Dinh gii hi0n tr?ng vi khoanh viing canh bio nguy ca trugt Id dit tinh Quang Nam, Tap chi Cic Khoa hgc vg Trii Dit, T.33, 3DB, tr. 518-525, Hi Ngi.
[3] Phgm Vdn Hiing, 2012: Diit giy ho^t dpng vi nguy co nut sut dit viing mii tinh Quang Ngai.
Tap chi Cac Khoa hpc vl Trai Dit, T.34, 3, tr.233- 242, Hi Ndi.
[4] Ngo Cdnh Tiing, Nguyen HOu Ndm. Nghiem HOv Hgnh, 2010: Thign tai trugt Id dit d Quang Nam, Quing Ngai vi m^t sd phuang phSp du bio.
Tap chf Dja ky thuit, sd 3, tr.46-53. Hi N^i.
[5] Guzzetti, F., A. Carrara, M. Cardinali, P.
Reichenback, 1999: Landslide hazard evaluation:
a review of current techniques and their application in a multi-scale study. Central Italy.
Geomorphoiogy, vol. 31, no.1-4, p.181-216.
[6] Saaty, Thomas L, 1994: Fundamentals of decision making and priority theory with analytic hierarchy process. Pittsburg: RWS publications, 527p.
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SUMMARY
Risk w a r n i n g landsiide In the m o u n t a i n o u s d i s t r i c t s of Q u a n g Ngai p r o v i n c e
On the basis of studies to assess the status and impact factors arising landslides, partitioning allows warned the risk of landslides in the mountainous districts of Quang Ngai province.
- On the mountainous province of Quang Ngai distnbuted sliding block 809, they fomi bands njnning under the sublatitude, sublongtitude and the NE-SW with sliding mass density reached 10-12 block/1 Okm^,
• Landslides occur due to 11 impact factors arising, including slope and slope factor mean annual rainfall plays a key role: followed by the crust of factors, geology, tropical impact fracture dynamics, hydrogeology, fracture density, the density of deep separation, horizontal separation density, cover plant phue and traffic density. Zoning map warning the risk of landslides in mountainous districts of Quang Ngai province was built on the basis of the integrated 11 Landslide hazard maps in spatial analysis component in a GIS environment.
- On Ihe mountainous districts of Quang Ngai province, the average risk of landslides accounted for 40.67% of the research natural area, distributed in the districts of Ba To, Son Ha, Tay Tra. Areas at risk of landslides in high level accounting for 24.32% of the natural areas of the study area, mainly distnbuted in the districts of Ba To, Son Ha and Tra Bong. Areas at risk of landslides in low-level accounting for 20.28% of the area of research natural areas, distributed in the district Ba To, Son Ha and Son Tay, partly In Tay Tra district, Minh Long and Tra Bong Areas with high risk of landslides accounted for only 0 5 8 % of the natural area and research area is mainly distributed in Tra Bong district and scattered in Ba To, Son Ha. Areas with very low risk of landslides accounted for 14 15% of the research natural area, distnbuted m the distncts of Shon Tay, Ba To and scattered in the districts of Son Ha, Tay Tra and Mmh Long
