HOI NGH! KHOA HQC TOAN QUOC V £ SINH THAI VA TAI NGUY£N SINH VAT U N THU BA LI/A CHON PHU''''ONG PHAP NGHEEN ClTU DANH GIA XOI MON DAT PHU HOP C H O HUYEN SON DQNG TINH B A C GIANG HOANG TIEN HA Sa Nong[.]
HOI NGH! KHOA HQC T O A N Q U O C V £ SINH THAI VA TAI NGUY£N SINH VAT U N THU BA LI/A CHON PHU'ONG PHAP NGHEEN ClTU DANH GIA XOI MON DAT PHU HOP C H O H U Y E N SON DQNG - T I N H B A C GIANG HOANG TIEN HA Sa Nong nghiep vd Phdt trien nong thon Bdc Giang Xdi mdn dit Ii qui trinh phi buy lcip thd nhudng (bao gom ci phi buy thinh phin co, Iy, hoa, chit dinh dudng v.v cua dit) dudi tic dgng ciia cic nhin td ty nhien va nhan sinh lam giam phi nhieu ciia dit, giy rabac miu, thoii hoi dit, laterit hoi, tro sdi di v.v , inh hudng fryc tilp tdi sy sdng vi phit friln ciia thim thyc vat rimg, thim ciy khic Cic nha khoa hgc d tren thi gidi ciing nhu d Viet Nam di neu nhilu phuang phap de tinh toin, dinh gia xdi mdn dit Tuy nhien, vifc lya chgn phucmg phip nghien cim, danh gii xdi mdn dit phii hgp cho huyfn Son Dgng - tinh Bic Giang vi vd ciing can thilt Scm Ddng Ii huyfn miln nui vimg cao cua tinh Bic Giang cd difn tich ty nhien la 84.432,4ha, dd difn tich dit lam nghiep Ii 65.528,8ha chilm 77,6% [8] Dia hinh Son Dgng gom ci miln nui va dong bing xen ke, manh miin Die dilm chii ylu cua dja hinh viing niii Ii chia cit manh, phuc tap, chenh Ifch vl dg cao ldn Trong nhirng nim qua, vifcijuin ly va sir dyng bin vtrng dat canh tic, die bift Ii viing dit ddc chua dugc cac cip, cac nganh quan tam diing mirc Hing nim, hang trim hecta rimg ty nhien bi tan phi lim cho_ difn tich dit frong, dong nui trgc cang ting hoic thay vio la nhtmg difn tich rimg kem^chit lugng, ning bao vf dit thip Chinh vi vay, hifn tugng xdi mdn dang xiy manh, mdi nim hang nghin tin dit miu md bi xdi mdn, rira trdi Thyc frang niy dang lim cho dit dai ciia huyfn mit din ning canh tic I M y c DICH VA PHU^ONG PHAP Tren co Sd phin tich dinh gii cic phuomg phip dinh gii xdi mdn dit da dugc thyc hifn vi ngoai nude, lya chgn dugc phuang phip nghien ciiu, dinh gii xdi mdn dit phii bgp cho huyfn Son Dgng - tinh Bic Giang, lim co sd cho cac dl tii nghien cuu sau niy lien quan den xdi mdn dit tren dia bin huyfn Som Dgng ' IL KET QUA NGHIEN CUtl " Cac nhan to anh hud'ng den xdi mdn dat: Cac nhan to chinh inh hudng din qui trinh xdi mdn dit bao gdm: hau, dia hinh, ldp phu thyc vat, dang dit, ngudi 1-1 Anh hudng cua cac nhan to hau den xdi mdn dat: Xdi mdn chu ylu ddng chiy bl mit giy ra, nhung ddng chay lai cic ylu td hiu quan frgng quyet dinh la: Tdng lugng mua va tinh chit ciia mua, thdi gian vi cudng mua Thdi gian mua cang Ion, cudng dg mua cing cao thi qui trmh xdi mdn cing xiy manh me Q Vift Nam ndi chung va d huyfn Son Dgng - tinh Bic Giang ndi rieng, mua phan hda theo miia rd rft Lugng mua cue dai vio cic tiling miia he vi rat it nhung thang mua dong Vi vay vifc bao vf dit chong xdi mdn die bift miia mua Ii vo cung can thiet Anh hudng cua dja hinh din xdi mdn dit: Dja hinh cung Ii nhan td ty nhien anh hudng Idn din xdi mdn dit NIU xet tren difn rgng, dia hinh cd tac dung lam thay do, sy phan bd nhift vi lugng mua roi xudng Sy thay ddi ve dg cao d Vift Nam keo theo sy tjay 0,2 mm/phiit) T: Thdi gian tuong iing lugng mua xdi mdn A: Hf so the hifn die tinh xdi mdn cua dat, vdi nhdm dat chinh ciia tay bic cd he so la vi Mo hinh USEE USEE (Universal soil loss equation) - Phuong trinh mit dat tdng quit (hay phuang trinh mat dat phd dyng) dugc Wischmeier vi Schmid hoan thifn vio nim 1978 tir ket qui ciia mgt nd lyc thdng ke Icin (dtr lifu tii hon 5000 plot hang nam) Phuong trinh dugc thiet kf ban dau nhu la mdt cdng cy qui hoach de kiem soat van de xdi mdn cho cic cinh ddng d vimg trung tay vi "vinh dai ngd" nude My Phuong trinh mit dit tdng quit cho phep danh gia d ty If tiing cinh ddng lugmg dat mit xdi mdn khe ranh va xdi mdn hen ranh Trong khung cinh ciia phuong trinh mat dat tdng quit, xdi mdn dugc djnh nghTa la tdng lugng dat dugc chuyen tcii chin sudn ddc noi hoic la cic qui trinh ling dgng (deposit) quan trgng bit dau difn hoac cic ddng chiy bit diu dugc tap trung lai Vifc ip dyng cich tifm can md hinh hoi phin tich thdng ke hdi qui da bien de xiy dyng phuong trinh di cho phep phan tich cac nhan td trgng sd cua mgt loat bien dgc lap (mua, dat, dia hinh, ldp phu thyc v^t v i phucmg thurc canh tic) Hon nira, viec sir dung cic tham sd ludng lugng mat dat hang nim cho phep phucmg trinh niy cd the diing dugc dinh gii lugng mat dat trung buih hang nam Phuomg trinh cd dugc tir sd lugng lcin cic thira dat dugc quan sit hiem qua 90m chilu dii v i ddc qui 18% 1316 HQI NGH! KHOA HQC T O A N Q U O C V £ SINH THAI V A TAI N G U Y £ N SINH VAT LAN THU BA Phucmg trinh mat dat tdng quit cd dang nhu sau: A = RKLSCP (Phuong frinh: Wischmeier WH - Smith DD) Trong dd: A: Lugngdit mat tmng binh hang nam chuyin tdi chan sudn (kg/m^nim) R: He sd xdi mdn mua (thang do xdi mdn dugc lap tren co sd EI30) (KJ.mm/m^.h.nim) K: Hf sd khing xdi ciia dit (dugc xic dinh bing lugmg dit mit di cho mgt don vi x(5i mdn ciia mua dilu kifn chuin, nghTa la chilu dii sudn la 22,4m, ddc 9%, trdng ludng theo chieu tir fren xudng sudn ddc) (kg.h/KJ.mm) L: Hf sd chieu dii sudn ddc, ty If dit mit di ciia thira dit so vdi lugng dit mit di ciia thira dat chuan (khdng thir nguyen) S: Hf sd dg ddc (ty If dat mat di cua thira dit so vdi lugng mit dit ciia thua dit chuin) (khdng thu nguyen) C: Hf sd cay trdng hoic lcip phii (khdng thii nguyen) ty If lugng dit mit ciia thira dat so vdi lugng dat mat di ciia thira dit chuin (bd hoi cich nim) P: Hf sd canh tic bio vf dat (khdng thir nguyen) ty If lugng dit mit di cua thua dit • so vdi lugmg dit mat di cua thua dit chuin (trdng ludng theo chieu tir tren xudng sudn doc) Phuang trinh ban diu dugc lap d hf ludng Anh - My nhung da dugc chuyen sang hf SI de tifn cho vifc tinh-toin vdi cac dtr lifu thu thip dugc ciing nhu dinh gii so sanh USLE vdi cic md hinh xdi mdn khic Phuang trinh mat dit tdng quit cd the dugc coi la cong cu dy bio cd the "dinh gii tdt nhat" vi chinh xic dudi cac dieu kifn ve hiu, dit, dia hinh da dugc Wischmieier vi Smith chi rd Ciing cd the nhan thay ring vifc su dyng phuang trinh de tinh toin hoic dy doan cho cic hifn tugng xdi mdn xiy thdi gian ngan hon se khong chinh xic vi ip dyng phuong trinh eho cic ty If khic (qui md ve khdng gian) cung can het sire than trgng Tuy nhien, vifc phin tich qui trinh xdi mdn cic bien dgc lap cung mang lai nang to lcin tinh toan dy doin xdi mdn vi tu niy, cung nhu ban thin phuang trinh USLE cd thi dugc sira doi dl thich hgp vdi nhirng hoan cinh cy the ve ty If khdng gian, dilu kifn hiu ciing nhu cic dieu kifn dia - vit Iy khic bing cich thay ddi cic hf sd ciia phucmg trinh Vi Iy tren, phuang trinh USLE da dugc thay ddi cho phii hgp vdi cic dieu kifojchic nhau, vi dy: - USLE cho dit canh tie ndng nghifp (chinh Ii phuang trinh gdc ciia Wischmeier va Smith) - USLE cho dit xay dyng (Wischmeier, Jonson va Cross, 1971) - USLE cho dit rimg (Dissmeier va Foster, 1981) - USLE dilu kifn bao (Onstad v i Foster, 1974) - USLE cho danh gii lugng trim tich ciia luu vyc (Williams, 1975) Mo hinh SEIM Dk dinh gii dugc mirc dg xdi mdn tren linh tiid Icm (toin bg Dai Loan), cic tic gii di sir dyng md hinh chi sd xdi mdn dit (Soil Erosion Index Model - SEIM) Md hinh niy nghien cuu sy inh hudng cua cic chi so khic tdi lugng dit xdi_ mdn ma khdng nhim tinh cy the lugng dit xdi mdn hing nim Vdi sy cd mat ciia Ci (chi sd ldp phu) vi Ui (chi so su dung dit), mo hinh mang tdi birc franh rd rft ban vl tmh trang xdi mdn so vdi md hinh xdi mdn tilm ning tir phuong trinh USLE (loai bd hf sd C vi P) Md hinh chi sd xdi mdn dit cd dang: Ai = Ki + Ri + Ti -f Ci + Ui Trong dd: Ki: chi sd xdi mdn cua dit Ri: Chi sd xdi mdn cua mua Ti: Chi sd xdi mdn ciia sudn (slope) Ci: Chi sd xoi mdn ciia Icip phii Ui: Chi sd xdi mdn ciia sir dyng dati 1317 HOI NGHI KHOA HQC T O A N Q U O C Vfe SINH THAI VA TAI N G U Y £ N SINH VAT L^N THU' BA Va sy lien quan giiia lugng dit xdi mdn va chi so tdng AI dugc bieu dien: SE = d.lC'Al''^ vdi Ai < 50 (1) SE = 0.233AI'" vdi Ai >50 (2) Hf so tuong quan R^ cua cac phuong truih quan hf tren dat 0.88 (ptl) va 0.94 (pt2) D I cd thi thiy ro hon vai frd ciia cac chi sd tdi tiem ning xdi mdn, cac tic gia da phan tich dya tren co sd chia loai chi sd tren ITnh vyc: cac chi sd dieu kien ty nhien vi cac chi sd nhin tao (artificial index) gdm Ci vi Ui, tir dd cd dugc ket luan vl nhirng noi mi ngudi cin cd tic dgng de giim thieu xdi mdn 2.3.2 Mo hinh nhan thirc: Khic vdi md hinh kinh nghiem, cac md hmh nhan thiic dugc phit triln dya vio hieu biet ve cac qui luat van ddng va co che vat Iy cua qui trinh xdi mdn, nghTa Ii dya vio cac hieu biet da dugc Iy thuylt hoi dudi dang cic dinh luat hay phuong trinh vat Iy Cac qui trinh vat ly cua xdi mdn cd the dugc ke gdm: qua trinh bdc tich hat dat (do ning lugng cua hat mua roi hoac mgt dang nang lucTng khic); qua trinh chuyen tai (vdi cac djnh luat ve ddng chay ma qui trinh niy man thu) vi qui trinh sa ling cua cac hat dit Vi till, co sd ly thuyet cua md hinh nhan thiic Ii ly thuyet co hgc chat ran, chat ldng vi phan tich md hinh kinh nghiem * Mo hinh nhan thirc don gian: Bin chit ciia cac md hinh nhan thiic dom gian Ii qui trinh xdi mdn dugc chia lam hai budc, budc dat bj bdc tach vi budc dat dugc chuyen tai tdi ciia Lugng dit bi bdc tich thudng dugc tinh theo phuomg trinh mat dat tdng quit USLE, qui trinh chuyen tii dugc tinh toin qua cic ham dien toin thinh phin chuyen tai Cic md hinh thugc loai niy cd the ke Ii Md hinh dien toan bim cit theo Muskingum, Sign vi Qufroga, 1986; Ket hgp md hinh md phdng mua, ddng chiy v i bim cit, Franchini vi Schipa, 1993 Md hinh nhan thirc don gian cd cac uu diem va nhugc diem sau: - Uu diem: + Md ti va tinh toin kha chi tiet qui trinh chuyen tai hat dat tren sudn doc thdng qua vifc phan chia luu vyc + Khdng bat budc phy thugc vio hinh dang xac dinh - Nhugc diem: Khdng hoin toan dya vao qui trinh vat Iy cua hifn tugng xdi mdn ma mdi chi de cap den lugng dit tdn that hing nim Vi vay, cin nghien ciru hoan thifn ciu tnic ciia md hinh de cd the cho phep md phdng lugng dat mit vdi thdi gian tinh toin nhd hon mdt nim * Md hinh nhan thirc phiic tap: Cic md hinh loai niy dugc xay dyng dya vio bin chat vat ly ciia hifn tugng xdi mdn luu vyc Qua trinh xdi mdn luu vyc dugc md t i qua ba qui trinh chinh: qui frinh bdc tich cic hat dat ning lugng cua hat mua; qui trinh chuyen tii hat dit ddng chay mat gay nen v i qui trinh bdi ling kha nfing chuyen tai ciia be mat lim vyc nho hon ndng tap trung cic hat Mdi qua trinh dfu tuan thu nhirng djnh luat vat ly nhat djnh va cd the md phdng dugc Toan bg ba qua trinh tren Ii lien tyc va tao nen ddng lyc cua qui trinh xoi mdn tren be mat luu vyc Cd the ke d day Ii cic md hinh phd bien sau: Dy bio xdi mdn nude (WEPP), Lane va Nearing, 1989; Md hinh xdi mdn Chau Au, Morgan, 1992; Chuang trinh dy bio xdi mdn tiieo qui trinh, Schramm, 1994: - Uu diem quan trgng nhat cin phai ke tdi ciia md hinh nhan thuc phirc tap la nd da khic phuc nhieu nhugc diem ciia hai loai md hinh fren Cich md phdng sat vdi qua trinh xdi mdn tren be mat luu wc, vi the, cho phep xem xet phan img cua hf thdng thuy vin mudn thay ddi mdt bd phan hay toin bd cau tnic ciia he - Nhugc diem de thay cua md hinh nhan thiic phiic tap la ddi hdi lugng thdng tin dau 1318 HOI NGH! KHOA HQC T O A N Q U O C Vg SINH THAI VA TAI N G U Y £ N SINH VAT LAN THU" BA Viet Nam tmdc day, mdt sd tic gia da nghien cim xdi mdn dit d ddng bic, tiy bic bing cic phucmg phap don gian va tryc quan nhu ddng cgc, dimg day dgi hoic md ti, danh gia djnh tinh qua trmh xdi mdn nam (1961-1964) Sau dd, chiln tranh (1965-1976), vin dl xdi mon it dugc quan tam nghien cim: Sau nam 1960, cic cdng trinh nghien ciru ciia Nguyin Nggc Binh (1962), Nguyen Quy Khai (1962), Cao Vin Binh (1962) da nghien ciiu vl inh hudng cua doc den xdi mdn dit, gdp phin dua cic tieu chi bio vf dit, sir dyng vi khai thac dit doc Cac tac gia Tdn Gia Huyen, Chu Dinh Hoing, Nguyin Xuin Ky, Nguyin Quy Khii, Biii Nganh (1963) v.v da tap trung nghien ciru d tay bic, Bic Thii (cu), Phu Thg (cu), Son La vi Lao Cai vl xdi mdn khu vyc va bifn phap, cdng trinh trdng cay xanh che phii dat chong xdi mdn Cdng trinh ciia Pham Nggc Diing (1991) ve iimg dyng phucmg trinh mat dat phd quit vao dy bao tilm nang xdi mdn dat md trien vgng cho vifc img dung phuang trinh Wischmeier W.HSmith D.D vio dy bio xdi mdn dit dieu kifn nude ta hifn "Nim 1996, Nguyen Nggc Lung vi Vd Dai Hii da cdng bd cdng trinh nghien cim vdi tya de "Nghien ciru tic dung phdng hg ngudn nude cua mgt sd thim thyc vit chinh vi cic nguyen tic xiy dyng rimg phdng hg ngudn nude" Ve mat Iy luan cic tic gii da dinh gii dugc ning lyc phdng hd ciia mdt sd dang ciu triic thim thyc vit rimg ve mat chdng xdi mdn Hf thong thdng tin dja li (GIS) va nhirng iing dung tinh toan xoi mdn dat 3.1 Hf thong thdng tin dja ly (GIS): Thuomg GIS hay dugc ghep vdi ban dd Tuy nhien ban dd chi li mdt each de lam vifc vdi cic du lifu dia ly GIS vi chi Ii mgt loai sin pham dugc GIS tao Vift Nam, GIS dugc thdng nhit hieu chung: He thdng tin dja Iy la mgt hf thdng kit hgp giua ngudi vi hf thdng miy tinh ciing cic thiet bj ngoai vi de luu trti', xir ly, phan tich vi hiln thj cac thdng tin dia ly dl phyc vy mgt muc dich nghien ciiu nhat djnh DiKii tra tiiyc tii Du lietu lj;a.j;im.JEr]k nFCtnthj " Hmh Qui trinh GIS co ban Mgt hf thdng tin dia ly cd cic chiic ning co bin sau: - Nhap dir lifu - Thao tic dir lifu - Quin Iy dir lifu - Tmy van vi phan tich - Hiln thj va kit xuit dtir lifu Qui trinh boat dgng ciia GIS dugc mieu ta hinh 1319 HOI NGHI KHOA HOC T O A N Q U O C V £ SINH THAI V A TAI N G U Y £ N SINH VAT LAN THU' BA 3.2 Lfng dyng GIS mo hinh hda danh gia xdi mdn dat 3.2.1 LTng dung GIS tryc tiep xay dyng ban xdi mdn: Nhu trmh bay d frfn cho thiy GIS li cdng cy manh cd kha ning tryc tiep iing dung de danh gia xdi mdn dit Sir dyng tryc tilp GIS danh gii xay dyng ban dd xdi mdn dat dugc thyc hifn qua budc sau: Budc 1: Xay dyng cic ban dd don tinh, can it nhat loai ban sau: Ban thd nhudng, ban dd lugng mua, bin dia hinh, bin dd tham thyc vat Budc 2: Sii dyng GIS tinh toin dl dugc bin dd xdi mdn dit - U'u dilm cua phuong phap nay: Nhanh, tdn it cdng - Nhugc dilm: Dg tin cay khdng cao, t^o ban qua khdng cd co sd de phan cap xdi mdn 3.2.2 LTng dung GIS va md hinh hoa tinh toan xoi mdn dat: Vdi vifc cic md hinh tinh toin xdi mdn phong phii, da dang nhu da trinh biy d tren, viec lya chgn mdt md hinh de sir dung cin dugc quan tam can nhic dya tren nhieu yeu td: - Tinh kha thi, bao gom c i vifc kha thi vl dtr lif u va phuong phap - Tinh phu hgp vl thdng tin Cic thdng tin ma md hinh cd the dem lai (nghTa li ket qui tinh toin) phii diy du, phii hgp vdi yeu ciu dat - Tinh chinh xic Md hinh dugc chgn phii cd dg chinh xic phii hgp vcii yeu cau Nhtrng phan tich tren diy cho thiy USLE li mgt nhtrng md hinh phii hgp df dinh gii, tinh toin xdi mdn Sir dyng md hinh USLE frong dinh gii xdi mdn di li de tii nghien curu cua nhieu tic gii khic vi cho thay md hinh USLE cd the ip dyng thinh cdng cho tinh toan xdi mdn d cap dg khu vyc hoac mgt huyfn (nhu nghien ciiu cua de tii) Mgt dieu die bift thuan Igi nua ciia md hinh USLE li de cap den cic nhan td anh hudng tdi xdi mdn mdt cich rieng bift mdt mdi tuomg quan chit che Dilu niy cho phep tich rieng timg ylu to de phan tich anh hudng ciia chiing den xdi mdn va tim bifn phip tic dgng phii hgp nhat Vcii each tifm can van dl theo timg thdng sd anh hudng den xdi mdn, USLE cd the dugc tinh toan bing GIS Trinh ty cac budc co ban dugc thyc hifn nhu sau: Budc I: Xay dyng cac bin don tinh: - Ban dd thd nhudng - Ban dd lugng mua - Ban dd dia hinh - Ban dd tham thyc vat - Bin canh tic sir dyng dat v.v Budc 2: Tir cic ban don tinh, irng dyng GIS xay dyng cic bin he sd xdi mdn ciia phuong trinh USLE Budc 3: Tir cac ban dd hf so xdi mdn, iing dyng GIS xay dyng ban dd tiem ning xdi mdn va xdi mdn hifn tai cua khu vyc nghien ciiu Cac budc thyc hifn dugc md phdng theo hinh dudi day Hinh mieu ta vifc sii dyng md hinh USLE tinh toin xdi mdn bing hf thdng thdng tin dia Iy Cic thdng sd ciia md hinh (cic he sd) dugc tinh toin fren GIS tir cac du lifu diu vio (cic ban dd) Cudi ciing, dya tren ban dd cic hf sd nay, ban dd xdi mdn v i ban dd xdi mdn tiem ning dugc tinh toan 1320 HOI NGH! KHOA HQC T O A N QUOC V £ SINH THAI VA TAI NGUYEN SINH VAT LAN THU" BA - Uu diem: Phuong phap cho dg tin cay cao, de phan cip xdi mdn - Nhugc diem: Can hieu ro vl GIS dl thyc hifn tdt cic budc cdng vifc Tuy nhien, can die bift luu y ddi vdi vifc ung dung GIS tinh toan xdi mdn dit la so lifu diu vio phai chinh xac thi GIS mdi cho kit qua tin cay Do dd, quan tim din viec xay dyng mdt co sd dtr lifu dii tin cay li yeu ciu hang diu vifc ihig dyng GIS ndi chung va img dung GIS dinh gii xdi mdn dit ndi rieng PP khac + GIS Ban lirgng mira trung GIS ,^^^ GIS f H | se R binh nam , TS H^ so K Ban tho nhir&ng Hf so C Ban lop phii thyc v$t ^ ^ ^ He so P I ^ , - , , , A ^ • i Ca sa air li^u aau VCtO Ban phdn '^ \Bdn dS kei qua GIS ; ' !>; ' , Hinh 2: Sir dyng mo hinh USLE tinh toin x6i ni6n bang GIS IIL KET LUAN Tir nhtrng ket qua tdng hgp, phan tich neu fren cd the di den nhumg ket luan sau: - Hifn cd nhieu phuong phip nghien ciru, dinh gii xdi mdn dit dugc cic nhi khoa hgc va ngoii nude sir dyng Cic phuong phip my khic nhung deu cho nhtrng ket qui nghien ciru cd gii trj - Phuomg trinh mit dit phd qui cua Wischmeier W.H and Smith D.D da ddi tir rat liu nhung van dang dugc nhieu nha khoa hgc coi la cdng cu hiru hifu dinh gii xdi mdn dit - Vdi vifc phat triln manh ciia cdng nghf thdng tin, vifc nghien cim, dinh gii xdi mdn dit tren difn rgng trd nen de ding va thuan lgi - Ciing Iiic kit hgp phuong trinh USLE ciia Wischmeier W.H and Smith D.D vi hf thdng tin dia Iy (GIS) frong nghien cim, danh gii xdi mdn dit vira dam bio nhanh chdng, chinh xic ma van bdc tich dugc tung ylu td dl nghien cim rieng bift va cd nhimg khuyen cao, tic dgng hgp Iy cho khu vyc nghien ciiu Do vay, diy la lya chgn phii hgp cho nghien cuu, dinh gii xdi mdn dit ndi chung vi tren dja bin huyfn Son Dgng - tinh Bic Giang ndi rieng 1321 HOI NGH! KHOA HOC T O A N Q U O C Vg SINH THAI V A TAI N G U Y £ N SINH VAT LAN THU" BA TAI LIfU THAM KHAO Lai Vinh Cam, 2000: "Soil erosion smdy in NorthWest region of Viet Nam by intergrating watersheed analysis and universal soil loss equation (USLE)" Tap chi khoa hgc Dai hgc Qiioc gia H i Ndi, sd XI Nguyen The Dang, Dao Chau Thu, Dang Van Minh, 2003: Dat doi nui Vift Nam, N'XB Ndng nghifp Ha Ngi Hgi Khoa hgc dat Vift Nam, 2000: Dit Vift Nam, NXB Ndng nghifp Ha Ngi Phdng Thong ke huyfn Son Dgng, 2007: Nien giim thong ke nam 2007, Scm Dgng, Bac Giang Tran Vinh Phudc, 2001: GIS - Mgt so vin dl chgn Igc, NXB Giao dye Ha Ngi Nguyen Quang My, 2005: Xdi mdn dit hifn dai va cic bifn phip chdng xdi mdn, NXB Dai hgc Qudc gia Ha Ndi Tran Van Y, Nguyen Quang My, Nguyen Van Nhung, 1999: "Sir dyng Hf Thdng tin dia Iy xay dyng bin dd xdi mdn tiem ning Vift Nam ty If 1:1000.000", Ung dyng Vien thim vi Hf thdng tin dja Iy quy hoach mdi trudng, H i Ngi » UBNT) tinh Bac Giang, 2007: Kit qua theo ddi dien bien tai nguyen rimg tinh Bac Giang nam 2007 Wischmeier W.H and Smith D.D, 1962: Rainfall erosion, advance in Agronomy S E L E C T I N G AN A P P R O P R I A T E M E T H O D F O R ASSESSMENT O F SOIL EROSION O F SON D O N G D I S T R I C T - BAC G I A N G P R O V I N C E HOANG TIEN HA SUMMARY This paper presents a review on methods of assessment of soil erosion in order to choose an appropriate method for assessment of soil erosion of Son Dong District - Bac Giang Province As the result, the USLE with application of GIS has been selected for assessment of soil erosion of Son Dong District - Bac Giang Province 1322 ... trinh USLE da dugc thay ddi cho phii hgp vdi cic dieu kifojchic nhau, vi dy: - USLE cho dit canh tie ndng nghifp (chinh Ii phuang trinh gdc ciia Wischmeier va Smith) - USLE cho dit xay dyng (Wischmeier,... khuyen cao, tic dgng hgp Iy cho khu vyc nghien ciiu Do vay, diy la lya chgn phii hgp cho nghien cuu, dinh gii xdi mdn dit ndi chung vi tren dja bin huyfn Son Dgng - tinh Bic Giang ndi rieng 1321 HOI... tiem ning xdi mdn cho cic khu vyc khic Do Hung Thinh da cii bien cdng thirc tren: Y =A.I°•''^L''''•^x••^T Y: Lugmg dit nia trdi fren mgt don vi difn tich 1: Do ddc sudn tinh binh quan cho mdi d vudng