NGHIEN CU''''U THIEN TAI LU LUT VA D i XUAT MOT SO GIAI PHAP KHAC PHUC HAU QUA VA PHONG C H O N G TREN CAC HE T H 6 N G SONG SU6l TiNH BAC KAN TS Phf Hung Cu''''O''''ng Trudng Dai hpc Khoa hpe Dai hpc Thai Ngu[.]
NGHIEN CU'U THIEN TAI LU LUT VA D i XUAT MOT SO GIAI PHAP KHAC PHUC HAU QUA VA PHONG C H O N G TREN CAC HE T H N G SONG SU6l TiNH BAC KAN TS Phf Hung Cu'O'ng - Trudng Dai hpc Khoa hpe - Dai hpc Thai Nguyen tk m\ m Kghien ciru cac sy cd moi truang a Viet Nam dang la vin di thai su vi tir nhieu ndm qua, ducn manh hwang cua biin ddi hdu todn ciu, cpng vai tdc dpng ngdy cdng gia tdng ciia boat dpng w khai thdc lanh thd, nhit Id a cac luu vuc song, da tao nen sire ep moi trirang ngdy cdng manh, dac biet la cac thung lung song, suoi mien niii Npi dung bai bdo nghien eiru ddc diim ede luu vuc a tinh Bac Kan va buae diu xdy dyng ban phan viing chirc nang canh bdo 10 lijt tinh Bde Kan tren ca sa phdn tich canh quan, di xuit mpt sd dinh huang sir dijng khdng gian cho phdt trin bin vu'ng, cdc gidi phdp qudn ly luu vuc, cac giai phap tdng hgp mdi tnrang va bao ve mdi truang vd phdt triin bin vu'ng tren thugng ngudn luu vyc sdng Ciu Dat van de phong chdng tren cae he thdng sdng sudi tmh Bac Nghien CLPU cac s y c l mdi trudng d Viet Nam Kan de tCp dd cd nhCpng giai phap nham han c h l thiet dang la van d l thdi s y vi tCr nhilu nam qua, dudi hai eua 10 lut la r i t e i n thilt anh hudng cua b i l n doi hau toan c l u , cpng vdi Khai quat dac diem cae lu'u vyc a tinh Bac tac dpng cang gia tang cua hoat ddng khai thac Kan lanh tho, nhit la d eae luu vyc song, da tao nen SCPC ep mdi trudng cang manh, dae biet la cac thung lung sdng, s u l i m i l n nui Mat khac, cae luu vyc sdng thudng la nhO'ng dja ban phan b l dan cu ddng due, canh tac tru phu, thuan Igi v l dja t h i va tai nguyen ddi vdi viec hinh cac trung tam cdng nghiep va dd thj ndng thdn m i l n nui B l c Kan la tinh m i l n nui nam sau ndi dja eua vung Ddng B l c , phia B l c giap Cao Bang, phfa Nam giap Thai Nguyen, phia Ddng giap Lang San va phia Tay giap Tuyen Quang Dien tich ty nhien la 4.857,21 km^, chilm 4,7% dien tich vung Ddng Blc, va 1,45% dien tich ca nude, s l dan 302.786 ngudi (2006), chilm 0,36% dan s l toan qudc Ngay nay, trudc SLPC ep v l dan sd va nhu c l u SLP dung tai nguyen phat trien kinh t l da lam eho dien tich rCpng bj giam sut, cac vyc chCpa nude bj san l i p , d i t dai bj hoang hoa, va vdi nhO'ng biln dpng cua hau, thdi tilt da lam tang mCrc dp sinh thuy va tap trung nude Day la mpt nhCpng nguyen nhan ehu y l u gay nen nhilu sy e l mdi trudng (dae biet la 10 quet, 10 I n g , sat Id dit ) d vung nui Ddng B l c ndi chung va d eae luu vyc sdng thupc tinh B l c Kan ndi rieng Vi vay, nghien CLPU thien tai 10 lut va d l x u l t mpt so giai phap k h i c phuc hau qua' va Dja hinh cua B l c Kan da dang, phCpc tap, chu y l u la ddi nui eao Cac day nui eao phan b l d phia Odng (canh cung Ngan San) va phia Tay (mpt phin canh cung sdng Gam) Ve mat dja hinh, cd the chia Bac Kan khu vyc: 1) Khu vyc phia Ddng bao g i m cae day nui cao, keo dai theo canh cung Ngan San Canh cung chay s u i t tCp Nam Quet (Cao Bing), qua B l c Kan v l tdi Lang Hit (phfa b l c Thai Nguyen) udn hlnh vdng cung rd ret theo hudng B l c - Nam; 2) Khu vyc phfa Tay cOng la nhO'ng khdi nui cao vdi dinh cao nhat 1578 m (Phia Tap chi Khi ttftfng Thuy van * Thang 5/2009 -i?«i Nghien cufu & Trao ddi Bide) tren lanh tho B l c Kan; 3) Khu vyc trung tam Dan so luu vyc he thong cae sdng cua B l c dpc thung lOng sdng C l u cd dja hinh t h i p han Kan thupc loai t h i p nhit so vdi ca nude, dd nhilu Day la mpt n i p Idm dugc eau tao chu y l u bdi dong bao dan tdc it ngudi chilm d i n 78% (ehu y l u da phien, da vdi, da set vdi cd tuoi rat co Pho biln la cac cdng d i n g Tay, Nung, Dao ) Mat dp dan sd la cac day doi cao d i n 200m, mpt vai nui thap (400- 60 ngudi/km^, nen cOng la mpt nhO'ng tinh ed 500m) cd nhO'ng thung lOng md rpng, ddi trd mat dp dan sd t h i p n h i t ea nude, ty le d i t ndng nhO'ng canh dong giO'a nui Vdi e l u true dja nghiep tren dau ngudi rat thap, cd d i n > hinh nhu vay, cdng vdi dja hinh nui ehilm uu t h i 85% dan s l sdng bang n g h i ndng Chinh vi vay tinh nen dien tich d i t doe tren 150 d B l c Kan chilm tdi trang canh tac nuang r i y cdn kha biln, d i n d i n 66% (319.124 ha).dien tich toan tinh, them vao dd la tinh trang xam canh vao quy d i t rCpng, lam eho dien nhO'ng dien tich d i t cd dp doc nhd, nhung lai nam tich rCpng bj thu hep nhanh chdng, va lam suy thoai tren eae vung sudn va dinh nui vdi 106.000 lam mdi trudng sinh thai tren luu vyc cho dien tfch dat doe ft cd kha nang sCr dung ca gidi hoa chilm d i n 88% dien tich ty nhien toan tinh, dien Ket qua bu'O'C dau xay dirng ban phong tich n l u khdng dugc che phu tot se la mpt b i n chd'ng thien tai lu lut tmh Bae Kan thu nude Idn tgp trung d l d i n nhanh nude xuing vung thung lOng Tren dja ban tinh B l c Kan da xay dyng dugc nhieu ban d l bp phan nhu ban d l v l hau, dja Canh quan hinh thai dja hlnh Bac Kan r i t da hinh, tho nhuang, thuy van, trac lugng hinh thai dang, chung ed vai trd quan trpng viec luu trCp Tuy nhien, ehi la eae ban d l dan tinh khdng the va phan phdi nude, dae biet la nude dudi dat d l ndi len dugc d i y du cac thdng tin v l nguyen nhan d i l u hda can can nude Trudc day rCrng che phu gay tai biln, khu vyc tai biln, khu vyc cd the phat tren dja ban B l c Kan kha t i t , ty le che phu dat 75%, triln kinh t l xa hpi dugc Bang cac p h i n m i m song nhO'ng nam g i n day, viec khai thac rCrng thilu chuyen dung va SLP dung he thdng tin dja ly (GIS), , quy hoach da b i l n nhilu khu ru'ng gia, nhilu khu tac gia da xay dyng dugc ban d l phan vung chCpc ', ru'ng ed c h i t lugng cao trd ddi trpc, nang canh bao 10 lut tren pham vi toan tinh, ban d l rCrng thu* sinh cay bui, d i l u da lam tang xdi mdn cho phep nhin nhan mpt each tong hgp v l dit, tang sy x u l t hien eua cac tran lu, giam lugng nguyen nhan xay tai biln, dua nhO'ng khu vyc eung d p nude cho cac t i n g nude n g l m La mpt cd nguy ca xay tai b i l n va tCp dd d l x u l t phuang tinh nam khu vyc Ddng B l c Bac Bp nen an phdng ching phuc vu cho cdng tac quy hoach hau Blc Kan mang nhO'ng net dac trung cua hau khu vyc eho phat trien kinh te nhiet ddi gid mua nen c h l dp mua bj chi phdi chu Tren ban d l phan vung ehCpc nang canh bao 10 y l u bdi gid mua he D i l u lam cho lugng nude lut phan chia duge 12 vung ehCpc nang canh tap trung vao mua mua, tang kha nang sinh lu tren quan, dd la: Vung chCre nang canh quan ddng cae triln sdng B l c Kan bang day cae thung lOng giCi'a nui e l u tao bdi cae Ldp phu tho nhuang tren dja ban luu vyc cac sdng thudc B l c Kan thudng ed t i n g day khdng qua 2m, tren cac sudn d i e manh va tren da g l c la diep thach thi t i n g day d i t khdng qua 50 cm, t i n g phong hda ben dudi cd dp day tCp - 3m, ddi chd < m tren eae da ran it bj phong hoa Ham lugng cac p h i n tCp thd (< 2mm) trung binh tu' d i n 10% Day la mpt y l u t l anh hudng d i n dp t h i m nude va kha nang giu' nude eua tho bi, lien quan d i n mCpc dp tap trung nude tren cac luu vuc vat lieu t r i m tich bd rdi aluvi, proluvi, deluvi vdi b l mat kha bang phang, nghieng thoai; Vung chCpc nang canh quan d i n g bang day cac canh dong eacxta (thung lOng cacxta) eae khu vyc bj cacxta manh, tren b l mat p h i n Idn cd nhO'ng doi da vdi sdt, ddi eho kha b i n g phang; Vung chCre nang canh quan dong bang cacxta (ven ria thung lOng cacxta) cae khu vyc bj cacxta manh, tren b l mat phin Idn ed nhO'ng d i i da vdi sdt, ddi cho kha " bang phang; 4.Vung chCre nang canh quan doi eao, sudn 111 hay sudn thang, dinh klia bang, hinh dang Tap chi Khi ttfcfng Thuy van * Thang 5/2009 ; ^ N g h i d n Cii'u & Trao d ^ i ^ binh khdng d i u dan, phan bo cac b i n dja giu'a nui; 5.Vung ehCpc nang canh quan nui t h i p c l u tao bdi da vdi qua trinh phong hoa cacxta dien manh; Vung chCrc nang canh quan nui t h i p e l u tao bdi da t r i m tich xen da vdi, sudn ed dp d i e tu" t h i p d i n trung binh, b l mat dinh m i m mai It Id da goc, tang phong hoa ed ehilu day 0,5 I m ; Vung chCpc nang canh quan nui t h i p c l u tao bdi da t r i m tfch xen da vdi, sudn kha d i e gdm cac vat sudn tich (deluvi) va proluvi chilm phan Idn trie dien, phin dinh thudng Id da g l c Idm chdm (gim da vdi chLPa nhilu da lan tuoi D va O -S), t i n g d i t - Vung so 10 ed dien tfch r i t rpng, nhung lai cd dp chia e i t r i t Idn, cd nguy ca xam thye bdc mdn manh, e i n cd nhO'ng bien phap bao ve ching xam thye khe ranh Day la vung thu nude, se cd anh hudng d i n cac vCing va - Cac vung so 6, 8, la nhu'ng vung d i t die, ed nhilu kha nang xay chay trugt, bdc mdn b l mat neu canh tac khdng hgp ly, khdng mang tinh b i n vCpng Djnh hu'O'ng su' dung khong gian eho phat triin b i n vu-ng thudng mdng; Vung chCre nang canh quan nui NhO'ng canh bao da duge phan tfch d muc tren t h i p c l u tao bdi da philn (trim tfch biln chit) vdi cho phep dua nhO'ng djnh hudng SLP dung nhu cac sudn dai, b l mat dinh kha m i m mai, dp chia c i t sau: khdng cao, t i n g d i t kha day; Vung chCpc nang canh quan nui trung binh e l u tao bdi da philn (da biln chit), sudn nui dai, b l mat dinh kha m i m mai, dp chia c i t ngang khdng eao, tang d i t kha day; 10 Vung chLPc nang canh quan nui t h i p c l u tao bdi da t r i m tfch va da biln c h i t vdi cac sudn ngan, b l mat - D i i vdi eae vung ehCrc nang canh quan s l (cd dien tich kha rpng) va 12 (dien tich hep), e i n dugc bao ve nghiem ngat vdi phuang hudng phat then mang tinh bao t i n cao, dd hinh cac khu rCrng dac dung va phat triln cay lam nghiep cay dai dja hinh bj chia cat manh, dp chia cat ngang Idn; 11 tren d i t d i e , vi day thye t l la nhO'ng vung d i u Vung chLPC nang canh quan nui thap c l u tao bdi da ngudn sdng s u l i nhu vung thu nude thudc h i Ba Be baza va sieu baza (gabro), sudn dai, t h i n g , d i e , (nam dja phan VQG Ba B l , huyen Ba Be), dja chia c i t ngang y l u , t i n g d i t day mau dd sam, ban cac nguin s u l i hCpu ngan sdng Nang, vung dudng net m i m mai; 12 Vung chCpc nang canh Phuc Lpc, Ha Hieu (huyen Pac Nam), vung thugng quan nui thip, c l u tao bdi da xam nhap axit (granit), nguin sdng Ngan San d VO Loan, Luang thugng, sudn dai, d i e loi, b l mat dinh rpng, m i m mai, dat cd Lang San (thudc khu bao t i n thien nhien Kim Hy, t i n g day dang ke mau dd vang huyen Na Ri), vung nui Khuoi Deng Tan San (huyen Tren ca sd cac vung chCpc nang canh bao 10 lut duge phan chia tren dja ban tinh Bae Kan, ed the dua nhO'ng canh bao sau: Chg Mdi), v.v Hudng SLP dung la phat then cay lam nghiep va bao ve tham ru'ng - Tai lanh t h i cac vung chCpc nang s l va s l 2, - Cac vung chCpc nang sd va so 12 la nhCrng cd nhCrng nguy ca t i l m an v l ngap lut va thye t l vung nui thip, cd sudn d i e , sudn nui cd chilu dai da tu'ng xay ngap lut thudng xuyen tai nhO'ng dang ke, vd phong hoa kha day hoac la nhO'ng vat vung dpc theo cac thung lOng sdng sudi mua sudn tich Idn, vat lieu mang tinh hon hgp, day la Idn va tap trung, mat khac, day la nhO'ng vung tap nhO'ng vung cd nguy ea t i l m an cao v l trugt Id, lu trung cac dien tfch canh tac va nhu'ng vung dan cu quet, vi vay e i n ed nhO'ng bien phap phdng tranh ddng due, vi vay, e i n thilt phai cd nhu'ng cdng trinh hO'u hieu thoat nude, d i l u hoa ddng chay, cpng vdi viec xay Cac vung chu'c nang s l va s l la nhO'ng vung dyng n i n ndng nghiep sinh thai, tranh gieo tring va day thung lung, n i m dpc theo eae thung lOng sdng thu hoach trung vdi cac thdi diem ed kha nang ung hay cac canh ddng cacxta vdi dac trung la nhO'ng ngap; tim nhO'ng tap doan cay tring cd kha nang vung tu thuy, la nhCrng vung cd nhO'ng nguy ca tiem ehju ngap cao, phat triln dugc d i l u kien ung an v l ngap lut thudng xuyen ngap, v.v Tap chi Khi ixidng Thuy van * Thang 5/2009 Nghien ciiu & Trao doi ' VBIIK HIIU- aaiqt faMli*|ii:iflil»^ bAi^ ibiv