H$i Dia ly Viet Nam Dai hpc Thai Nguyen PHAN VUNG MirC DO NGUY CO TRlTOT LCS DAT Cf CAC HUYEN MIEN NUI TiNH QUANG NAM Le Van An' Abstract Landslide hazard zoning in the mountainous districts of Quang Nam Landslide hazard zoning was performed in the study area mainly by means of the map-overlay procedure; particularly we produced landslide-zoning maps based on eight criteria (slope, hydrogeolo fracture, annual precipitation, vegetation, vertical line segment cuts, horizontal line segment cuts, weath crust, and Jive selected sensitivity levels to landslides (very low low, medium, high and very high)) E zoning component maps were overlaid by means of spatial analysis in GIS environment through Ihe integration of component maps with available software to produce landslide-zoning maps As a result, landslide-zoning map was created for the study area with five levels and statistics of landslide risk leve according lo area ratio were also recorded I.MODAU Tinh Quing Nam cd huyen mien nin, bao gom: Bic Tri My, Nam Tra My, Phudc Son, Tien Phudc, Ndng Son, Ddng Giang, Tay Giang, Nam Giang vi Higp Diic Ciing nhu cic dja phuang mien mii khae d Vigt Nam, cic huygn mien mii tinh Quang Nam cd dia hinh chia cit manh liet Igi nam dieu kign hgu mua miia, nen tai biln ty nhien ngogi sinh ndi chung, tmat id dit ndi rieng xay rat biln vi mang tinh thudng nign, gay inh hudng Idn den sy phat trien kinh tl - xa hgi ben viing cua khu vyc Do vgy vigc nghien ciiu phan vung miic nguy ca tmpt Id dat lam ca sd cho vigc quy hogch sin xuat vi phdng trinh giim nhe thien tai tai bien tai cac huyen mien mii tinh Quing Nam dang la van dl c ^ thiet PHAN VUNG MlTC DO NGUY CO TRLTOT L Q D A T TAI CAC HUYEN MIEN NUI TTNH Q U A N G NAM 2.1 Phirong phip phin vung Phan vimg muc dp nguy co tmpt Id dat tai dja ban chu yeu bang phuang phap chong xep bin vdi su phy trg eiia phuong p h ^ thu thgp xu ly tu lieu Phuang phap chong xep ban dd phan vimg nguy ca tmpt Id dat dugc thuc hien nhu sau: 2.1.1 Xdc dinh chitiiu vdphdn cap chitiSuphdn viing - Lya chgn chi tieu phin vimg: Cie chi tieu lya chgn phan vimg miic dp nguy co tmpt Id dat d ^ a ban li cic nhan to ty nhien tic dpng sau sie din qui trinh tmgt Id dat Nhan to duoc chgn lam chi tigu cdn l i nhan to mang tinh dien hinh - nhan to tic dpng manh me &n qui trinh tmgt td dat, cd tinh dgi dien va phin anh dugc sy tic d|ng cua cic nhin to khic Nhan to dugc lua chpn phii li nhan to thugn Igi thu thgp, nhung phii bio dim miic dg chinh xac cao phan vung Til cic yen cau niy, cac chi tigu dugc lya chgn dua vao phin vimg bao gom: hg thong diit gSy, dg doc dia hinh, dja chat thiiy vin, lugng mua trung bmh nam, dp che phii thue vat, dp chia cit sau, dp chia cit ngang, Idp vd phong hda, - Phan cap chi tieu: Vigc phan eip chi tieu dugc tien hinh dya vao su bien thien ciia cac chi tieu trgn tgi dja phuong vi miic^g tic dpng cua timg cip doi vdi qui trinh tragt Id dit Tren co sd nay, chiing toi^^n^chia moTcKi tieu thinh ckp va danh gii miic tac ddng ciia timg c ^ doi vdi qua trinh tmpt Id dit (bang: 1,2,3,4,5,6,7,8), ~i^i hgc Su pham Hue ' ^yiu Hpi nghi Khoa hgc Dia lp todn qudc ldn thd Hoi Dia Iy Vigt Nam D^i hoc Thii I^ Bang ! Phdn cdp nguy co tntat Id dat ddi vdi dp ddc Bo doc Muc nhay cam cip 20°- 35° Tmng binh >33°-4S» Cao >45° Rit cao Bdng 7: Phdn cdp nguy ea trugt Id ddt ddt vdi ehia cdt ngang Bo chia cSt Cap ngaDg(hm/km^) Muc nh^y cam I 2_ , _ l,5-2.0 >2,0-2,5 >2.5 Rat thip Thip Tnmg binh Cao Rit cao Rattii^ Thap Trung binh Cao Bdng 4: Phdn cdp nguy ca triegt Id ddt ddi vdi lugTig mua TB ndm Bang 3: Phdn cdp nguy ca truat Id ddt ddi v&i dja chdt thuy vdn fiia chat thuy van Cap Muc nhgy cam Giiu nude Rat tiiap Q>mt/s Ngheo nude Thip (co the lay dugc) Rit ngheo nude Tmng binh Giau nude cue bp Cao Q100-150 >150 Rit thap Thap Tnmg bhih Cao Rit cao Bdng 8: Phdn cdp nguy ca truot Id ddt Mi v&i logi vo phong hda Cap Vd phoQg hda Miirc nb^y cim Tram lich bdr roi Rit thip Feralit Thip SiUcit Trung bmh Sialferit Cao Ferosialit Rat cao Kpyiu Hdi nghi Khoa hgc Dia lp todn qudc ldn th Hoi Dia ly Vift Nam Dai hpc Thai Nguyen 2.7.2 Phdn vitng muc dp nguy ca tru0 Id dat ciia tirng ehi tieu Tir eac bin cac chi tieu phan, phan vung nguy ca tmot Id dit cho timg chi tieu theo nam cip chi tieu tren va xay dyng dugc ban dd phan vimg miic dd nguy co tmgt Id dat cua timg phan ZI.3 Phan viing muc dp nguy cff tru0 Id dat cua cdc huyen mien nui tinh Oudng Nam Vigc xay dyng bin nguy co tmgt Id dit cic huyen mien nui tinh Quang Nara dugc tien hanh thdng qua viec chdng xep ban phan vimg nguy co tmgt Id dat phan, bing phuang phap phan tich khdng gian mdi tmdng GIS - su tich hap cac ban dd phan theo cdng thiic [6] LSI - 0,225Bd_Dd + 0,I75Bd_Lm + 0,125Bd_Vph + 0,125Bd_DdI + 0,075Bd Dctv + 0,025Bd_Mdcn + 0,025Bd_Mdcs + 0,025 Bd Dptv (Chii giai cdng thirc tren vi dy Bd-Dd: bin dd dd ddc, BdLm ) Ket qui xir ly tich hgp thu duac la ban gia tri so vdi mdi pixel cd mdt gii trj LSI tuong ling, dd de xay dyng so nguy ca tmgt Id dat can phan chia cac gia tn LSI trgn bin gii tn so thinh cic cip miic dd phii hpp Nguyen tac va phuang phs^ phan chia cac cap miic dp tmgt Id dat tir cic gia tri LSI nhu sau- ngudng 6k, phan c ^ ban tmgt Id cd gii trj so dugc lya chgn sau thyc hign xii Iy thong ke, xiy dyng ducmg cdng tich luy xac suit (bieu thong kg tich luy miic dp tmgt Id dat gii tri so) Ket qua xii Ii thong ke xic djnh dugc cic thdng so sau: Gii tri tdi thieu Xmin = 1,210; tmng bmh Avg= 5,107, toi da Xraax= 8,930; dd leeh tigu chuyin StD= 2,131 Kho^g cich giiia cic c ^ dugc lya chgn theo cdng thiic: Ax = (Xmax - Xmin)/n Trong dd n- so cip cin phan chia (vdi so cip dugc sir dyng tgi cac huyen miln mii tinh Quang Nara, n=5) va tri gia Ax = 1,55 Tir cic thdng so tren, vdi c ^ miic tmgt Id dit (rit t h ^ , thip, tmng binh, cao vi rat cao) d dja bin nghien ciiu tuang iing vdi cic tri gia: rit t h ^ < 2,76; thap > 2,76 ~ 4,31; tmng binh > 4,31 - 5,86; cao > 5,86 - 7,41 vi rit cao > 7,41 2.1.4 Kit qud Tir quy trinh tren, kit qui Ii da xiy dyng dugc ban phan viing miic nguy ca tmgt Id dat ciia cic huygn mien mii tinh Quang Nam vdi eip (hinh 1) va bin thong ke ti trpng dign tich cic c ^ dp tmgt Id dat (bing 9) Hinh 1: Sadd phdn vitng mac dg nguyea tru0 Id ddt cdc huyin miin nui tinh Qudng Nam ^ySTHpi nghi Khoa hoc Dia lp todn qudc ldn tha Dai hoc Thai Ng ayg Hoi Dia ly Vi£t N a m Bdng 9: Bdng thdng ke dien tieh cdc cdp muc dg nguy ca trugt Id ddt cdc huyen mien niii tinh Qudng Nam Cap nguy cu Dicn tich (ha) Rit thip 355 0,8 Thap 95 330 12,8 Trung binh 408 400 55 Cao 205 200 27,6 Tylg(%) Rit cao 28 500 3,8 Tong 742 785 100 Nhu vgy, qui trinh thyc hign phan viing miic dp nguy ca tmot Id dat tgi dja bin vdi kit qui tren cho thay cic huygn mien mii tinh Quing Nam cd nguy co tmgt Id dat rat cao, cy thi tong dign tich ty nhien toan dja bin la 742 785 thi co tdi 642 100 (chilm 86,4%) cd nguy co tmgt Id dit tir mire tmng binh trd Ien v i cd tdi 32,4% cd nguy co d miic cao va rat cao KET LUAN Phan vimg nguy co tmgt Id dat bing phuong phip chong xep bin da dugc nhilu nha khoa hgc d Vigt Nam vgn dyng d cac dja phuong khic va cd hi|u qua nhat dhih Phuang ph^ chong xip bin phan vung miic nguy co tmgt Id dat la mgt phuang p h ^ bao dam tinh chmh xac cao, vi phuang phiqi da sir dyng rat nhieu chi tigu dugc lya chgn cd nguygn tac cho thong^ • so Mu vio dong thai dugc bo trg bdi cdng nghe hien dgi, Ket qua nghign ciiu tai dia bin cic b u y ^ ^ mien mii tinh Quing Nam cho thiy, dign tich cap miic dg nguy eg tmgt Id cao chiem ti lg Ion n h ^ | Dong thdi eic tic nhan ty nhien ciing tgo nguy co tmgt Id dit tiim nang rit ldn Vi the tgi dja ban niu khdng dim bio giii duac ldp phii thyc vgt dong thoi khdng cd sy dilu chinh cac hogt dpng!'"| lira gia tang nguy eo tmgt Id dat (phi hoai Idp pM, Iam tang dd doc, tang dd rcri rae vat chit,.,) tS^l tai biln tmgt Id dit se xay rit nghiem trgng T A I LIEU THAM K H A O Le Diic An (2008) Mpt sd vdn di vi nghiin cim truat Id ddt vd du bdo chiing - Hpi nghi KHDia lp todn quoc ldn thd i - Ha Ngi Le Tin Cue (2011) Nghiin cdu tai biin truat Id ddt trin cac tuyin giao thong trongyeu tinh Qudng Ngdi - Lugn van ThS Khoa hpc - DH SP Hui f^guyln Vi Dm {2006) Ld ddt vd budc ddu du bdo viing truat Id ddt d Bdc Trung B$ < bdng phuang phdp dia mgo - Hdi Nghi KH Dia lp ldn2-i^ Npi ; Nguyen Tir Dan., (2008) Ddnh gid tdng hap xdi mdn va truat Id ddt tren lim vuc song Dd bdng cdng nghi GIS - Hpi Nghi KH Dia lp ldn - Ha Ngi ,5 l: