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Nghien Citu & Trao doi NGHIEN CU''''U XAY DU''''NG BAN DO PHAN VUNG NGUY CO LO QUET PHUC Vy CONG TAC PHONG TRANH LU QUET CHO TINH YEN BAI TS La Thanh Ha Trung tam Nghien cuu Thuy van va Tai nguyen nude Vien[.]
Nghien Citu & Trao doi NGHIEN CU'U XAY DU'NG BAN DO PHAN VUNG NGUY CO LO QUET PHUC Vy CONG TAC PHONG TRANH LU QUET CHO TINH YEN BAI TS La Thanh Ha Trung tam Nghien cuu Thuy van va Tai nguyen nude - Vien Khoa hpc Khf tugng Thuy van va Mdi trudng Y rSn Bdi Id mdt cdc tinh ehju nhiiu anh hudng cua thien tai, dae biet Id lu quet Do diiu kien dja hlnh ndm d sudn ddn gid ddng nam cua ddy Hodng Lien Son nen cd lugng mua Idn, die luu vuc cdc sdng Ngdi Thia, Ngdi Lao Idn da tao nguy ea lu quet cao Tran lu quet kinh hodng xay cung thdi gian vdo euii thang ndm 1995 tai Vdn Chin, Thj xa Nghia Ld, Mil Cang Chdi gay thiet hai Idn vi ngudi va tdi san Trong bai bdo trinh bdy phuang phdp vd gidi thieu kit qua lap bdn dd phdn viing-nguy ca lu quet cho tinh Yen Bai vdi hy vgng su dung duge cdng tdc canh bdo lu quet mua mua ID sap din Giai thieu t i n g quan khu virc nghien cii'u trinh nhd Tong thiet hai v l kinh t l khoang 29,6 ty ding a Dieu kien tiv nhien Yen Bai n i m d vung nui phia Bac, cd dae diem dja hinh cao dan tCp Ddng Nam len Tay B l c va duge kiln tao bdi day nui Idn d i u cd hudng Tay B l c - - Tran lu quet tCp 30/6/2001 -13/8/2001 tai Cat Thjnh, Tu Le, Nam Bung, San A, D i n g Khe, San Luang, lam 15 ngudi chit, 506 lua, 261 hoa mau bj ngap lut Ddng Nam: phia Tay cd day Hoang Lien San - Pu Ludng nam kep giua song H i n g va sdng Da, t i l p - Tran lu quet ljch su vao 18-19/9/2005: Xay d i n CO day nui Con Voi n i m kep giua s6ng Hing va tae d6ng cua hai can bao sd va lien tilp s6ng Chay, phfa Dong la day nui da v6i nam kep gay tran lu quet kinh hoang tren pham vi cae giua s6ng Chay va s6ng L6 Dja hinh kha phuc tap huyen Van C h i n , TX NghTa Lp, Mu Cang Chai, nhung cd t h i chia vung Idn: vung cao va nghiem trpng n h i t tai xa Cat Thjnh, huyen Van vung thip.Vung cao cd d6 cao trung binh 600 m trd C h i n , lam 76 ngudi c h i t va m i t tfch, ngap ung len, ehilm 67,6 % dien tich toan tinh Vung dan 2370 lua, dd 1109 m i t tring eu thua thdt, cd t i l m nang v l d i t dai, lam san, c Tong quan cac nguyen nhan gay lu quet khoang san, cd kha nang huy ddng vao phat triln kinh t l - xa hpi Vung t h i p cd d6 eao dudi 600 m, chu y l u la d i i nui thip, thung lung b i n dia, chilm Cd t h i tong quat mpt s i nguyen nhan chfnh gay lu quet va sat Id dat d tinh Yen Bai nhu sau: - Do mua r i t to, cudng dp Idn (lugng mua gid tdi 40 mm hoac cao han) 32,4 % dien tich toan tinh - Do dja hinh d i e , k i t d u kem, d i sat Id cd b Hien trang lu quet tinh mua to Theo thing ke, tCp nam 1977 den 2008, tren dja - RCpng d i u ngudn bj tan pha nhieu khai thac ban tinh Yen Bai da xay 60 tran lu quet Idn, nhd bua bai, d i t nuang lam r i y v.v nen mdi cd d h i u khip cac huyen tinh M6t s i tran lu quet mua Idn nude tap trung r i t nhanh d i l n hinh: - Ddng chay d cac khe s u l i thudng t i e - Tran lu quet 23-24/7/1996, tai xa NghTa lgi, P Cau Thia, P Pu Trang- thj xa NghTa Lo, P bj lan chilm de xay dyng cac vat kiln true, cay, viec xay dyng cau, d n g d mpt s i nai khong du O i n g Tam, P Minh Tan, xa Minh Bao lam 10 ngudi khIu thoat lu v.v chit, thiet hai 3144 lua, 2008 hoa mau, hu Lya chon y l u t6 phan vung nguy co- lu quet hdng 104 cdng trinh thuy Igi, ehu y l u la cac cdng Lu quet la mot dang thien tai nhung su hinh Phan bien: PGS TS Ngo Trong Thuan Tap chi Khi tu'tfng Thoy van Thang 2/2009 11 Nghien cufu & Trao doi eua nd cung ehju tac ddng eua nhan t l eon pham phong hoa da Macmaxit, da eat cd phin ngudi, dd, nguyen nhan gay ID quet bao g i m ea gidi chu y l u la thjt nhe, d u true kem, ham lugng dieu kien ty nhien va nhan t l eon ngudi Qua phan mun thip, chu y l u phan b l tren vung cd dp d i e ldn tich so lieu cac tran lu quet da xay tren pham vi nen nguy ea xdi mdn eao nhit; toan quic va tinh Yen Bai da chpn yeu t l chfnh anh hudng d i n sy hinh lu quet sau: a Lwang mwa l&n nhit wng v&i tin Nhdm II (G2): D i t hinh tren phu sa c l hoac tren da maema axit, bj thoai hoa manh, phin suit ca gidi tCp eat pha d i n thjt nhe, d i t m i t d u true, ngheo mun, tinh deo, tfnh dinh d i u kem, thudng 50% Can cu s i lieu mua thye eua cac tram mien nui phia Bie da lap ban d l dang trj mua Idn nhit ling vdi t i n s u i t 50% va phan d p (Bang 1, Hinh 1) phan b l d ria ddng b i n g , dp d i e thap nen nguy ca xdi mdn t h i p han cac loai d i t nhdm Nhdm 111 (G3): La nhCrng d i t hinh tren san p h i m phong hoa da set, da biln c h i t va phu sa eo Nhdm IV (G4): La nhung loai d i t hinh tren b Nguy caxoi mon dit Cac loai d i t d i i nui cua vung Trung du miln nui phia B i e dugc phan chia d p theo nguy ea xdi mdn nhu sau (Bang 1): san pham phong hoa da bazan, da vdi va eae d i t vang da dugc cai tao Nhdm V (G5): Cac loai d i t edn lai Nhdm I (GI): La nhCrng d i t hinh tren san Bang Phan cip Iwang mwa l&n nhit (XI max) wng v&i tin suit 50% va nguy caxoi mon CSp/TiSuchf XI max (mm) Ky higu JMiicdO >600 X, 450-600 X2 300-450 X3 150-300 X4