su* DUNG ANH VIEN THAM VA GIS PHAN TICH TAI BIEN
TRi/grr Ld D A T K H U W C H O T H U Y D I E N S O N L A
NGUYEN VAN DUNG PHAIVI VAN HtJNG, NGUYllN THANH H O A N
Tdm tdt: Trdn ca sd tdng hgp cdc tai li$u hien cd va kdt qua phan tich gjai doan anh vien thdm phdn gidi cao cho phdp xac Idp hien trang phdn b6 vd cdc ydu td tac ddng phdt sinh tai hidn trugt Id ddt Son La.
Trdn Idiu vyc nghi^ cuu dd xdc lap gdn 400 khdi trugt ldn nhd; phan bd tiieo dang tuydn cd phuong Tdy Bdc - Ddng Nam vd d kinh tuydn. Cdc ddi cd phucmg Tay Bdc - Ddng Nam: Phong 1h6 - Tam Ehidng, Q u ^ Nhai - Mudi^ La, Tuin Giao - Thudn Chdu. Cdc ddi cd phuong d kinh tuydn:
Mudng Lay - Mudng Chd, Tan Uyen - Than Uyen, Tua Chiaa - Tudn Gido.
Cdc yeu to tdc dgng phdt sinh trugt Id ddt bao g^m nhdm cdc ydu td dia mgo, dia chdt, kiln tao, khi hgu thuy vdn, Idp phu thuc vdt vd hoat dgng kmh td ciia con ngudi. Trong dd, cdc ydu td dia chdt; kidn tao, ldp phu thuc vat, hi?n trgng sd dung ddt,... dugc xac lap tren co sd tdng hgp cdc kdt qud phdn tich giai dodn dnh vien tham, khdo sat thuc ^ a vd cdc tdi U?u hien cd. Phdn tich hien trang cdc tai bjen theo tung yeu to phat sinh cho phep xay dung cdc bdn dd nguy ca tai bidn thdnh phdn.
USE OF REMOTE SENSING IMAGE AND GIS FOR ANALYSIS IMPACT FACTORS OF COMPLICATIONS ARISING LANDSLIDES IN SON LA HYDROPOWER LAKE AREA Abstract: Based on the review of existing documentation and analysis of remote sensing unage
interpretation of high resolution allows to estabHsh the current status and distribution of impact factors complications arising landslides and debris flows in Son La hydropower lake area.
In the study area was established nearly 400 small. Slack in the form of online distribution NW - SE and Asia meridian. The NW - SE range: Phong Thd - Tam Ehrdng, Quynh Nhai - Mudng I ^ Tudn Giao - Thuan Chdu. The band has the submeridian: Mudng Lay - Muong Cha, Tan Uyen - Than Uyen, Tda Chiia - Tudn Gido.
The imp^t factore arising landslides including geomorphology, geology, tectonics, climate hydrology, vegetation cover and economic activities of the people. In particular, the geological, tectonic, vegetation cover, land use status ... are established on the basis of summing up the results of the analysis of remote sensing image interpretation, field survey and documentation existing.
Situation analysis of complications arising under each element allows the construction of disaster risk nu^ping component
I, 1. M d DAU dd cd nguon ca sd dii Ugu phong phu ve dnh Cac tai bidn trugt Id ddt (TLB) Id mdt trong vien tham, ddc biet la dnh viln thdm phan ^di nhiing tai bidn dia chdt (TBDC) didn hmh, gay cao phuc v\i cho nghien cuu ddnh gid, du bao nguy hidm khd ludng, de dga cudc s6ng cua cu cdc TBDC cd hieu qua. V? tinh VNREDSat-1 la dan cfia phuang. Ung dung phuong phdp phan vg tinh vien thdm ddu tien cua Viet Nam cung ti'ch vien thdm vd h | thdng thdng tin dia Iy cap ngudn dii li$u anh cd do phdn giai cao phuc (GIS) trong nghidn cdu ddnh gid du bdo TLD dd vu cho nghidn cdu dvr bdo TLD va Iu quet, lu dugc de cdp trong cdc cong trinh khoa hgc tren biin dd (LQ-LBD) d nudc ta. Ngodi ra, cac dnh the gjdi, ddc bi$t la d Nga, Phdp, My, Nhdt va SPOT-5, Landsat-8 ciing la nhihig ngudn dii Trung Qudc, dgt dugc nhung thanh tuu khoa li?u quan trgng trong nghien cdu ILD ndi rieng hgc quan trgng [1, 4, 10-13]. Hi?n nay, nudc ta vd tai bien dia chdt ndi ehung.
j-jip chl Nghien ctru Bja If nhan vin, so 1^ • Thing 3/2017
Tren ISnh tha TSy BSc noi rieng, mioc ta noi ehung, vi$c nghien c\lu phong tranh, ph6ng ch6ng tai Uki TLD da dugc ih cap trong mot s5 cdng trmh nhiing nam gin day va dat dupe nhihig k& qua buac diu [1, 4, 5]. Hito nay, trong dieu ki$n khoa hoc vk kj thuat phat trien, cac tai biln nay dS duac diu tu va ilng dvmg cong ngh$ viln th&n va GIS vto nghito ciiu danh gia hito trang va canh bao nguy co. Bai bao ttmh bay nhiing ket qua nghito ciiu buoc dau cua ii tai "Nghien cuu img dung dnh ve tinh VNREDSat-1 vd tmng duang trong diiu tra, du bdo vd ddnh gid cdc tai biin dja chdt cdc cdng trlnh hd thuy dien vd duang giao thdng cdc tinh khu vifc Tdy Bdc" mang ma s6 VTAJD-03/13- 15 va d6 tai ma s6 105.08-2015.31 dugc tai hw boi Quy Phdt hito khoa hpc va cong ngh$
Qu6cgiaCNAF0STED).
Khu vuc Tay BSc la noi co dia hinh hiSm trd, may mu chinh vi v^y quA trinh thu thap anh v?
tinh con nliito bdt c$p.
2. PmrONG PHAP N G H E I N ctTu vA CO s d TAI LIEU yt TAI BliN TRLTCfT Ld
2.1. Phuomg phap nghito cihi
6 nuoc ta, trong thcri gian qua da co nhito c6ng ttinh nghito curu TLD & nhiJng miic do khac nhau. Vjin dung kSt qua nghito ciiu ciia cac nudc tito tien, vai kinh nghidm nghito cilu nhieu nam ttong lihh vuc nay, GS Nguyen Trpng Yem va cac cpng su (2006) da tong ket, dua ra h? phucmg phap nghito cvm tai biln ket hprp tt^iyto thdng va hito dai, phii hpp vcri dito kien hito tai d nudc ta [5]. Trong do phai k£
den cac phucmg phap khao sat thuc dia, phan tich anh vien tham, phan tich dia mao, dia chat, kito tao va phto tich danh gia tai biln. Dac biet ia cdng ngh? vien tham da dupe ap dung va mang Iai nliito hito quii rd r$t trong danh gia hito tt?ng va phto tich nguyto nhto phat sinh TLD. Phto tich toh vien thtoi VNREDSat-I, SPOT-5 (phto giai 2,5-10 m) va Landsat-8 (phto giai 15-30 m) ket hpp vdi thuc dia kiem chiing cho phep xac lap hifn tt^g phto bd cac khdi trupt va ddng Iu biin da mdt each diy du va chi tiet. Mat khac, cac ylu td dia chit thach hpc, cto tnic Icito t£lo, lineamen - dilt gay, lop
phii th\ic vSt, hito trjng sil d\mg dit, m?ng ludi thily vto, giao thdng,... ciing dupe xac Ijp tten ca so tdng hpp tai li^u, phto tich toh viln tham kit hop khto sat th\rc dia. Cdng nghe GIS d!
dupe khai thac kha tridt dd trong xay dimg cSc bto do hi$n trpig va nguy co tai biln TLD. Vdi cdch tilp can moi, cac tai biln nay la qua trinh dia chit ddng luc, hinh thtoh va phdt ttiln ttong tdc dpng cda nhdm cdc ylu td n§i smh, ngoai sinh vd nhto sinh. Day la each tiep can * da ldm ca sd dl Itra chpn hp phuong phdp phd hpp, giilp cho vide phto tich cac yeu td nguySn nhto true tilp va tilm in ttong phat sinh tai biln diy du va toto dito hem. Ap dyng phuong phap phto tich so sdnh c|p, cho diem, tinh ttpng sd va phto tich khdng gian ttong moi trudng GIS cho phep xay dung bto dd canh bdo nguy ca tai bito d khu v\rc ngliito cilu.
2.2. Cff SOT tai li|u
Trto dja bto Tdy Bdc nuoc ta, m§t khii lupng Idn cdc tai lieu ve lich sil, hien tt^g vd ylu td phdt sinh TLD da dupe dl cap d cdc cdng trinh nghien cilu ttitdc day. Tuy nhien, vi$c c|p nhat cac tai lieu mdi nhit vl vto de nay lam ca sd cho nghito curu d\r bdo TLD Id nhipm yv lit quan ttpng hipn nay. Trong dd phdi ke den ngudn tai lieu ldn dupe phto tich, chiet xuat tir cdc do lito anh viln tham. Trto co sd phto tich toh vien thdm phto gidi cao va khao sdt thuc dia cho phep xdc lap hito trang phto bd va mpt so ylu td phdt sinh TLD a hd thiiy didn Som La.
a) Phdn tich gidl dodn hifn trgng tai bien dfa chat
Cac thdng tin chilt xuit tir dnh vp tmh, thdng qua cdc dto liito anh; dau hito true tiep (pho anh, hoa vto, td hpp mdu...), gito tiep Id nhihig yto to Idp phd, dia hinh, dia mao vd thanh phin vdt chat tten be mdt... cho phep xdc lap, nhto dang cac khdi ttupt va xay dung bto dd hito trjng phto bo TLD. Cdc dnh v$ tmh VNREDSat-1, SPOT-5 cd dp phto giai 2,5-10 m vd Landsat-8 cd dp phan gidi 15-30 m cho phep nhto dang nhiSng khdi trupt cd kich thudc >10 m. (Hmh 1-5). Nhihig kit qua phto tich gidi doto tren anh vien tham duac kilm chiing bdng khdo sdt thuc dja kilm tta vaddisdnh[l,2,5,6,7].
34
NguySn Vin Dung, Ph§m Van Hiing, Nguyen Thanh Hoan • SO' dyng inh vien thim...
Hinh 1. Khdi tnrfft (a) tren anh SPOTS vd chfip mgt ddt tgi phia nam Miedng Lay.
Hinh 1. Khoi trir0 (a) trin dnh SPOTS vd chup mat dat tgi phia nam Mirdrng Lay.
Hinh 3. Khdi tru0 va IH bdn da Igi Tg Khoa tren anh VNREDSat-I vd chup mat tk.
TfP chi Nghien ctru Bja ly nhin vin, so Im, • Thing Thing 3/2m\
b) Phan tich gidi dodn cdc yiu iSphdt sinh tai biin truft li
Cia bto do ylu td phdt sinh TLD da dupe xdy d\mg ttdn ca sd phto tich tdng hpp cdc tdi lidu hi$n cd, cac tai Ii$u khdo sdt vd cdc tdi lieu phto tich gidi doto dnh vp tinh phdn gidi cao. Trong do, cdc bto ih yeu to d^^ ddc dia Wnh, d§ die ldng sdng, m jt dO chia c5t ngang, mdt dp chia cdt sau dia hinh va cdc bto do chilu dai ddng, cip luu vvrc dupe xay dung ttto ca sd phto tich trdc lupng hinh thdi dja hinh. Cdc bto dS ylu td dia chit thjch hpc, lineamen-dHt gay, ciu trdc tto kien tao, dp che phu thirc vat, hito trang sil dyng dit khu virc ho thuy dito Son La dupe xdy d^mg ttto CO sd phto tich tong hgrp cdc tai lito hipn cd, tdi lito khdo sdt thuc dia vd phto tich gidi doto dnh v$ tinh phto giai cao. Bto do dia chit thjch hpc khu v\rc ho thuy dito Son La the liito ^ nhdm dd khde nhau: ttam tich bd rdi, tram tich gto ket, bito chat, magma acid, magma bazo vd carbonat. Bto dd Idp phu thuc
vat (hojc hipn ttjng sil dung dat) the hi^n cac loji dit sil dyng khde nhau: dat d khu dto cu, dit ttdng ddi mli trpc, dit ndng nghidp, dit rimg ttdng vd dit rimg t\r nhien. Do vdy, mile do che phii rimg cimg khde nhau. Bto do lineamen-dilt gay thi hi^n cac Imeamen bieu hipn ro ttto dnh, ctmg ddng thdi thi hito ro ttto dia hinh (Id cdc vdch die, thung ltog thing, tdp hprp cac h^, ttraig dang tuyln ...).
3. BAG DiftM HIEN TRANG VA NGUYEN NHAN PHAT SINH TAI BrtN TRirpTLdDAT
3.1. Hifn trang tai bien trvpt Id dit Tren cdc dii lidu dnh ve tinh, dau vlt ciia kh6i trupt, ndn phdng vdt thd Men khd ro net btog cdc ddm mdu cd xdm d$ vd hoa vto rd n^t va phto bipt hdn so voi xung quanh. Cdc khdi trupt id mdi xdy ra ctog the hito rd net hon vl xdm do, miu stog hem. Kit qud phto tich dnh viln thdm phto gidi cao ket hpp vdi dilu tta khdo sdt TLD d khu vtrc nghito ciiu da xac Ijp gin 400 khdi mrpt Idn nhd (Hmh 4).
mail 4. Bdn as hign trgng trugt Id dot khu virc ho thuy dign San La.
36
Nguyin Van Dung, Ph?m VSn Hiing, Nguy$n Thanh Hoan • Sir dyng inh viin thim..
Trdn ho thuy di^n Son La, cac ldi6i trugt Id phdn bd theo cdc ddi: Phong Th6 - Than Uydn;
Tua Chiia - TTiudn Chau. Ngoai ra, trugt Id cdn tgp trung vdi mgt dO Idn d mdt so khu vyc nhu:
Mudng Lay, Quynh Nhai, thdnh ph6 Son La, Mudng La. Dgc qudc Id 6, phdn b6 trdn 50 khdi trugt, tgp tnmg d mgt so dogn: Km 113+50, Km 85+300. Km 471+200, Km 482+600, Km 421+700). Tren qu6c Ig 12 phan bo hdng trdm khdi trugt d 80 dogn khde nhau.
d khu v\rc Mudng Lay cd I km phdn b6 5 - 6 khdi trugt Tgi Kml2 trugt Id keo ddi 2 km vdi cac khdi trugt ldn. Trugt Id xdy ra pho bidn tren dogn td Km 177+500 d^n Km 112+400.
Td ndm 1994 trd lgi day, trdn tuyen td Than Uyen - Tam Dudng - Phong Thd trugt Id xay ra rdt phdc tgp. Hang trdm kh6i trugt phdn bd tren cac sudn dh\ theo phuang a kinh tuydn td Tam Dudng den Than Uyen. Trdn tuydn Than Uydn - Khau Co phan bd nhidu di^m trugt Id ldn tai chdn deo phia Mudng Than.
Dai s^t trugt nay tgo nen nhieu diem trugt dai hang tram met (13 diem trugt ldn tren qudng dudng 2 km khdi lugng ddt dd phdi xd ly tdi 15000 m^). Tren tuyen Than Uyen - Tan Uyen phan bd nhieu £em trugt Id rat manh. Cdc diem trugt Id phat triln chu yeu tren ddi ddi thdp nhung cdc khdi trugt deu rat ldn. Dgc theo tuyln Tdn Uydn - Binh Lu (Tam Dudng) trugt Id mgnh dd xudt hign tai Mudng Khoa, ddo Bdn Bo, nam Binh Lu. Tat ca cac diem trugt Id nay deu hinh thanh tren sudn ddi thap, thoai vd dd keo dai qua nhieu ndm, Td Binh Lu den thdnh phd Lai Chau trugt tu nhidn phan bd thanh mgt ddi tren sudn ndi phia ddng bdc, chidu dai khoang 20 km.
Tai Idiu v ^ Sin H^ trugt Id xuat hi?n hau nhu trdn todn bd luu v\rc sudi Ngm Mg va tren sudn day Phu Sam C|p. Ddi phia ddng bdc dgc theo sudn phia tdy nam ddy Phu Sam C|.p. d day chu ylu xudt lii$n cac kh6i trugt tu nhien Ai ldn. Dien hinh nhdt Id khu vuc xd Phin Hd.
Toan bd sudn nui d ddy, tu dudng chia nudc ddy Phu Sam Cdp din day thung liing vlt tich cac khdi trugt phdt triln ddy d?ic chdng gdi len nhau kilu mai ngdi. Mgt vet trugt trong sd do kdo ddi td tram giao thdng xudng din lung
chimg nui, chieu dai iheo sudn d6c hem 200 m.
Cdc khoi trugt ldn hon cd dgng nhdng khii sut phan b6 thdp ddn xuong tan suoi. Td N ^ Tdm vl phia ddng nam, trugt Id t$p trung nhilu nhdt Id khu vvrc di ddn xd Nam Tam. Ddi phia tay keo dai dgc theo sudn ddng bdc cua cao nguyen Sin Hd. Cac khdi trugt d ddy phdn bd rai rdc chu ylu d khu vuc Ma Quai, Can Ho ya mgt it d khu v\rc Nam Tdm, Nam Mg. , , Tren tuyen Phong Thi - Mudng Lay trip^J^
rdt mgnh d khu v^rc Nam Pgy vd m$t ddi ^{^
Tan din Mudng Lay, d|c bi^t la dogn ^ ^ Nua - Mudng Lay. Td Pa T ^ di vl phia, Q^^
Nua Idiodng han 10 km xuat lii$n mgt khu vuc trugt ty: nhidn kha Idn. Dai trugt nay keo ddi hon 600 m, rgng khoang hon 100 m tgo thanh mOt bl mdt sudn rdt thodi trdn do la cdc mdnh rudng bdc thang. Phia trong la vdch nui rit ddc hinh dgng cua cung trugt sgt rat rd. Ria ngodi dai trugt tao thdnh mdt cung Idi vl phia sudi.
Tuyln Ngd ba Chdn Nua di Sin Hd phan bd hang logt khdi trugt Idn nhd. Td Chan Nua vl Mudng Lay phan bd hang trdm khoi trugt ldn nhd. Cdch ddu ciiu Lai Ha vd phia bdc hon 2 km mgt diem trugt rat ldn da xdy ra vdo khodng thdng 7 ndm 2010. Chidu dai cua vet trugt khoang hon 100 m nhung chieu cao 50 - 60 m lam sat toan bg mgt mdng ldn sudn nui xuIng sudi Nam Na keo theo todn bg dogn dudng nhua mdi lam d day xuIng long hd. Sy:
cd ndy gdy dch ^ c hodn todn giao thdng trong vdng 2 thdng.
Dgc tuyln Mudng Lay - Mudng Cha, keo ddi theo thung liing Nam Lay, Na Pheo va Ngm Mdc, hi^n tugng trugt tf nhien tap trung vdi mat dg ldn (25 diem trugt Id ldn d khu v\rc Mudng Lay), Dien hinh Id khdi trugt d ehan deo Ma Ty Ho tgi Km 111-133 vdi khdi lugng ti-en 5000 m^ vd khii Ougt Id rdt ldn cdch thj xa Lai Chdu khodng 9 km, tai Km 112+400. Cd the coi day la nhiing diem trugt didn hinh thudc xa Hudi Leng. Tgi day hang ndm ddu xdy ra trugt Id, cd nam sau hien tugng trugt lgi dien ra mgnh hon ndm trudc, gdy ach tdc giao thdng, phd huy mdt dudng. Dilm trugt Id keo dai lien tyc 350 m, cao 150 m vdi cung trugt nhilu bgc, bgc sau nhdt din 20 m vao ndi.
Tftp chl Nghiin cOv Bja If nhin vin, s6 Inn - Thing 3/2017
3.2. Nguyto nhSn phat sinh tai biin tnrft Idd^t
Cdc tai biln TLD phat smh do hai nhdm nguyto nhto chinh: tiem an vd tr\rc tiep.
NgMto ciiu nhitng nguyen nhto trye tidp cho phSp gidi quyet cac hjlu qua ciing nhu de ra nhimg gidi phdp cdng nghp thich hpp de han chl vd gidm thidu tai biln. Nghito cilu nguyto nhto tilm in (cdc ylu t6 ho ttp, hoje tdc dpng phdt smh tai biln TLD) cd y nghla quan ttijng trong du bdo tai bien, phye vu quy hoach phat ttiln bin vfing vd dl xuit gidi phap phdng trdnh. Do v^y, dl du bdo nguy co TLD, nhiem vy quan trpng la xdc I^p vai ttd ciia cdc ylu td tdc ddng phdt smh cac tai biln nto tten. Cac tai biln nay hinh thdnh vd phdt trito do tac dpng cda cdc ylu to npi, ngoai va nhto sinh. Trong dd phai ke din edc ylu th dia mao, dia ehdt.
Bang 1. Thong ke t n r ^ Idrvd
kiln tjo, khi h|u thuy vdn, Idrp phd thuc v|t vd ho?t dpng kinh tl cua con ngudi [5, 6, 8, 10- 13]. Cac ylu td dia mao bao g6m: dp ddc sudn, dp ddc Idng, m|t dd chia cat ngang, mat dp chia cdt sau, hinh thdi vd dito tich luu vyrc sdng... Ttong dd, cdc ylu td dp ddc sudn, mjt dp chia cit sau, m$t dd chia cit ngang ddng vai ttd quan ttpng ttong phdt sinh TLD. Trdn co sd phto tich hito trang TLD, ddi vdi timg yto td phdt sinh tai biln cho phdp xay drag cdc bto dd nguy ca tai biln thanh phin ttong nhdm cac ylu td dia mao. Phto tich hito trang TLD theo ylu td dp doc d khu virc h6 thdy dito Son La cho thiy, TLD xdy ra Idn nhat d bdc dp ddc 35- 45°. Miic dp TLD ctog gidm khi bdc dd ddc nhd din. B$c d0 ddc >45° hdu nhu khdng xdy ra TLD, do d dp ddc ndy, qua trinh dd Id phat triln (Bang 1).
diim so theo cap d$ doc dia hinh S $ d 6 c O
<15 15-25 25-35 35-45
>45
So diem trirgt Id 71 106 125 81 9
Dito tich (km^) 2190 3255 3703 1737 293
Hf s6 triigt lor 0.0324 0.0326 0.0338 0.0466 0.0307
Biem so 3 5 7 9 1 Nhdm yeu td dia chdt bao gdm: dia chdt
thach hgc, vd phong hda vd dia chdt thuy vdn.
Phdn tich quan h$ gitta hi^n trgng vdi timg yeu to phdt sinh tai biln cho phep xay d\m^
ban do nguy ca thdnh phdn. Vi dy: vdi ylu td dia chat thgch hgc cho thay, ylu to ndy cd vai trd trong ^hat smh TLD, thi hign d d$ cdng, dO ben chdc cua cdc nhdm ddt da vd cung thi hi?n d mdc dg phong hda ddt dd. Qua trinh phong hda ddt dd, tgo vd phong hod va qud trinh tich ty cdc tram tfch bd rdi Id ylu t l cd
vai trd ddng thdi vdi ddc dilm dia chdt thgch hgc trong phdt sinh tai biln. Bdi le, vd phong hod va trim tich bd rdi cung cdp ngudn vgt ligu cho qud trinh TLD. Nhdm da cd ddc dilm bin chdc khde nhau ddi vdi qud trinh phong hda, ciing thi hign vai trd khde nhau trong qua trinh phat sinh TLD. Nhdm da biln chdt, gdn kit yeu thdc ddy TLD d mdc cao nhat, tiep den la nhdm da magma acit, magma bazo va trdm tich gdn kit rdn chdc bi phong hda {Bang 2).
Bing 2.Thing ke truwt lor v i dilm so theo yen th dja chit thach h9C Nh6m dit di
Biln chdt Magma ach
Magma baza ^ Tram tich gto ket Ddvdi Trim tich bd rdi
So diem t m ^ lor 108
61 11 204 0 8
Dito tt'ch (km') 1717 2017 448 2273 1461 3219
H j s i truQt lor 0.062 0.030 0.024 0.089 0 0.002
Siem so 7 5 3 9 1 1
38
Nguyin Vin Dung, Ph^m Vin Hiing, Nguyin Thanh Hoan • Si> dyng inh viin tham.
Hinh 5. Bdn dS nguy cff tru0 W ddt theo yeu to ^ chat th^h hgc khu vuc ho thiiy difn Sffn La Nhdm yeu td kien tgo tac dgng phdt smh
TUD bao gdm: ylu t l cdu trdc tan ki&i tgo, mgt d$ ddt gdy vd ddi dtit gdy hogt dgng. Ddi d\A gdy tan kiln tgo tac d$ng phdt sinh TLD vol vai trd phd hu^ ddt da, hinh thanh khe ndt kien tgo vdi m$t d$ Idn, Idm cho ddt da kem bin viing; d ^ bigt Id khi cd mua, nudc mua thdm thau qua khe ntJt vao trong dat dd; dd dinh kit cua (m dd k^m, thdc ddy TLD phat trien. Mat dO ddt gdy vd ddi ddng l\rc ddt ^dy hoat dgng la ylu to chu dgo trong nhdm yeu td kien tgo phdt sinh TLD. Tren ca sd phdn tfch quan h$
giiia hi$n trgng vdi tung ylu td phat sinh tai bien cho phe^ xay dung bdn do nguy co tai biln thdnh phdn trong nhdm yeu td nay. Vi dy ddi vdi yeu to m|t dO ddt gdy cho thdy, ylu \h nay cd vai trd nhdt <!^nh trong phdt sinh TLD.
Viing cd m$t dd ddt gdy cang Idn, mdc dg TLD cdng Idn. Ydu t l ddi d$ng l^c dut gdy hogt dgng thi hign d cap do khac nhau, cd vai trd trong phdt sinh TLD khac nhau. Cap ddi ddng l\rc cang cao, qua trinh TLD xdy ra vdi mdc dg cang nhd; ddc bigt la vdng ngogi vi cdc ddi dgng lvrc ddt gdy, TLD xdy ra rdt ft (Bdng 3).
Bang 3. Thong kS tnr^t Id vd dilm so theo cdp mdt dp ddt gdy M | t d9 Sin giy (km/km')
<0,144 0,144-0,288 0,288-0,432 0,432-0,576
>0,576
So diem tror^rt lor 15 92 199 65 21
Dito tich (km') 1008 3482 3938 2006 744
Hf so tnrgt lor 0.01488 0.02642 0.05053 0.03240 0.02822
Diem so 1 3 9 7 5
r?p chl Nghien ctru Bja tf nhin vin, s6 Ig^ • Thing 3/2017
Hinh 6. Bdn do nguy cff tnrgt id ddi theo yeu td mgt dg ditt gdy khu vwc hd thdy dipt Sffn La
Nhdm yeu t l ldp phu thyc v$t vd ho?it ddng kinh tl cda con ngudi cd vai ttd nhit dinh ttong phdt sinh TLD. DO che phii th\rc vdt, hodc hipn trimg sil dyng dit cd vai trd quan ttpng phat sinh TLD. Viing cd d? che phi kdm (<20%) - phin ldm id viing dit d khu dto cu vd dit ttong d^i nui trpc, cdc qud trinh ndy xdy ra manh mS nhit. Vdng cd d§ che phd tot (>90%) - phin ldn la vung dit rimg tu nhito, TLD diln ra ylu nhit. NhiSng viing cd
d0 che phd 20-45% - phin Idn Id vtog dit sdn xuit ndng nghi$p, mile dO TLD diln ra d miic cao. Ngodi ra, hoat dpng kinh tl cda con ngudi tdc d^ng phdt sinh cdc tai biln ndy cdn the hipn d xay dyng m ^ g ludi giao thdng.
Khi xdy dyng dudng giao thdng, con ngudi tdc dpng trye tilp, ldm thay ddi ttang thdi mdi trudng, trong dd, vipc thay ddi dp die sudn, Idp phu thyc v|it dd ldm cho qud trinh TLD phdt ttiln (Btog 4).
40
JjStj^n^nDung, Ph^m Van Hung, Nguyen Thanh Hoan • Sir dyng inh vien tham...
Bang 4. Thing ke trirgt Id va diem sl theo yla t l dg che phfi thuc v^t B$ che Dhn thfc vat (%)
<20 20-45 45-75 75-90
>90
So diem tnrgrt Id 72 86 18 72 144
Di|n tich (km') 1717 2017 448 2273 4650
Hlsotnqrtlor 0.0419 0.0426 0.0401 0.0316 0.0309
Diem so 7 9 5 3 1
TRUNG QUOC ,/j
Hinh 7. Ban dS nguy cff tnrgt td ddt theo yiu ti dg che phu thgc vgt khu vgc hi thuy dien San La Tdm lai, trdn ca sd tong hpp cdc tai lito hien La. Ngodi mpt sd ylu td dupe xdy drag ttdn ca cd, phto tich giai doto dnh v$ tinh va khto sdt sd phto tich tedc lupng hhih thai dia hmh, mdt thuc dia dd cho phep xay dyng bto dd hito sd ylu td tdc dpng phdt smh TLD cung duac oang phto bd TLD khu vyc hd thdy dito Son xac lap tten ca sd phto tich dnh viln thdm kit
Tfip chi NghlSn ctru Bja If nhin vin, s61i,„ • Thing 3/2017
hpp khdo sat thirc dja va tdng hprp cdc tai lito hien cd nhu: dia chil th^ch hpc, vd phong hda, mdt dp Imeamen-ddt gdy, ldp pjiithyc vdt vd hipn trang sil dmg dit.
4 . l r f ; T L U ^
Ting hpp cic tdi lipu hito cd va kit qud phto tich gidi doto dnh vien thdm phto gidi cao (VNREDSat-1, SPOT-5 vd Landsat-8) da cho phep xdc ldp hi?n tt^g phto b6 va cdc ylu to tac dpng phdt sinh tai bien ttttpt Id dit d khu vyc h& thdy dito San La.
Cdc khdi trupt dd the hi^n rd vd nhto d ^ g tit ttto cdc dnh vp tinh phto gidi cao. Trto khu vyc ndy da xac lap gin 400 khoi truprt Idn nhd. TLD phto bo thdnh cdc ddi cd phuong Tdjr Bic - Ddng Nam va d kinh tuyln. Tai bien TLD dien ra m?nh mS, phto bo tap trung d dia bto tinh Lai Chau, Som La. DJc bi$t, chtog t5p himg ttdn dja bto cdc huyto Phong Thd, Mudng Chd, Mudng Lay, Than Uyto, Quynh Nhai.
Nhdm cdc ylu to dia m^io, dia chit, kiln t ^ , khi hau thdy vdn, ldp phii thuc vat vd hojt dpng kinh tl cda con ngudi tdc dpng phdt smh TLD d khu vyc h& thdy dipn San La. Cdc ylu tl dp d6c, mdt dp chia cit ngang, mat dp chia cit sdu dia hinh, chilu ddi ddng cip 1, dO ddc ldng cip 2 vd 3, hinh thai va dito tich luu vuc dupe xdy dyng ttdn co sd phto tt'ch trdc lupng hinh thdi dia hinh; cdc ylu t6 dia chit thach hpc, mat dp Imeamen-dul gSy, ldp phu thyc vJt, hi^n tt^g sd dyng dit dupe xdy dyng ttto co sd phto tich t6ng hpp tai li^u hipn cd, phto tt'ch gidi doto dnh vp tinh vd khdo sdt thyc dja.
Cac bto ih nguy ca tai bidn thdnh phan dupe xdy dyng ttdn ca sd phto tich hipn trang vdi timg ylu td. Ap dyng phuomg phdp phto tich so sdnh cfip, cho dilm va tinh trpng so, cho phep xdy dyng bto do nguy ca tai biln d khu vuc nghien ciiu./.
TAI L i e u THAM K H A O
1. Trdn Trung HuS v i nnk (2000), Nghiin ctiu ainh gii hiin taong tnigt li khu vac mip nu<K hd Hoi Binh, liiin nghj m^ s6 spii phip phdng trinh, Bdo cio d6 tii cip Vien Hin lim KH&CN Vj$t Nam.
2. Phgm Quang San (2001), Sd- dvng thing Un viin thim vi cing nghi GIS trong nghiin ciiu, theo d6i si/ c6 xdi id - tmvtldbdsdng, Trang "BSo vS nguin ddt vd nif*ccQa chiing ta (MLWR)", Ir. 155-160. Hd N6i.
3. VQ Anh Tudn. Ngfl DOc Anh (2012). DSnh gii biin tfjng rtmg tinh Son La, Hda Binh bing inh v$ trnh iJJ phin ^ii cao. Tuyln tdp bdo cdo: H$i thdo khoa hoc vd cflng ngh$ phgc vu phdt IrlSn kinh id - xd h$l khu v^c Tdy Bdc, Ygn Bdi, ngdy 12 thing 4 ndm 2012. Trang 184-187.
4. Trdn Anh Tudn. Nguydn Tir Ddn (2012), Nghiin cdu nh^y cim vi phin vitng nguy ca tnivt • Id dit Iftiu vac hi thdy diin Son La theo phuong phip phin tich cip bic Saaty, TC Cdc khoa hoc v l Trdi ddt. 3 Cr34). Hd N$i, tr. 223 -232.
5. NguySn Trgng Ydm vd nnk (2006), Nghiin cdu thinh tip bin d6 tai biin thiin nhiin trin tinh thS Viit Nam ty 1$ 1:
500.000, Bdo cdo ting kit d i tdi, Viin Bia chdt, Hd Nii.
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8. Landslides and Mudllows, 1998. Vol HZ: UNEP, UNESCO, Mockva.
9. Saaty. Tbomas L, 1994. Fundamentals of decision making and priority theory with analytic hierarchy process.
Pittsburgh; fW/S publications, 527 p.
lO.OnacHbieoKsoreHKbienpoueccbt. rEOC, M, 1999.
11. npMpoAHbie onacHOCTH PoccHK. T l . npHpOAHbie onacHOCm H oSiuecTBO. KPVK, M. 2001.
12. npHpoAHbre onacHocm POCCHH. T2. SicsoreHHbie reono™4ecKMe onacHoc™. KPVK. M, 2002.
13. FlpupoAHbie onacHOCTH POCCKH. T 5 . rMflpoMeTeoponwecKHe onacHocm. KPVK, M, 2002.
Thflng On tic gil:
Nguyin Van DQng.Vi$n Dia ly, 18 Hodng Quic Vi$t Hd Nil Email: [email protected]
Pham van HCtng, V[$n Dia chdt. 64 ChUa Ldng. Hi Nii Nguyin Thanh Hodn. Vi$n Dja ly, 18 Hodng Quic Vidt, Hd Nfli
Nhjt ky tfla sodn Ngdy nhin bdi: 211/2/2017 Biin tip: 2/2017
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