Qudn ly Tdi nguyin riing & Mdi trudng
XitrNGDUNG THU^T TOAN TRICH XUAT DIEM DI THl/OfNG NHI$T W ANH VE TINH MODIS DE PHAT HIEN CHAY R t o C 6 VIET NAM
Le Nggc Hoan^ Tran Quang Bao^
'^Truang Dgi hgc Ldm nghiep T 6 M TAT
Bai bao trinh bily kk qua nghiai ciiu iing dyng ihuat toan ciia Louis Giglio vii cong sg phdt trioi nam 2003 dua tren thuat todn gfic ciia BCaufinan naml993 dl trich xudt dilm di fliuan§ nhiet tii anh v? tinh MODIS nhSra phye vy phat hien chdy rimg a Viet Nam. De danh gid kha nang trich xuat va miic dp phii hgp kit qua nghiai cihi trong dilu ki&i o Vi?t Nam, nhom tdc gia sii dung anh v? tinh MODIS tii nam 2010 - 2015 dl trich xuit dilm di thuong nhiet, d6ng thoi tdng hop vi [Aan tich khd nang phan b6 cdc dilm di thuong nhiet tiieo thin gian va khwig gian. Kit qua phan tidi sy phSn b6 cdc diem di thudng nhi^t theo khaig gian va thoi gjan d&i tuong doi phli hgp dilu ki?n kit qua phan viing trgng diem chay rang va miia chay rung 6 Viet Nam. Ddy la ca so khoa hgc quan trgng trcng vi?c iing dung anh v| tinh MODIS dl phdt hien va canh bao chdy rimg a Viet Nam.
Tii khoa: Chdy riing, dilm dj thiramg nhif t, MODIS, phdt hien chiy rirng.
I. D ^ T VAN Dfe
Chay rung la tham hpa, gay thiet hai Ion doi voi tinh mang va tai sdn ciia eon nguoi, tai nguygn rimg va moi truong s6ng. Anh hucmg eua no khong nhung tac dong den mot quoc gia ma con anh huong den ca khu vuc va toan cau.
Trong thyc tl, chdy rimg thuong chi duge quan sat thdy khi no da lan ra tren mQt dien tich rgng, dan den kho khan trong viec kiem soat va ngan chan va thdm chi la bdt kha thi (Doanh et a l , 2014). Trong nhiing nam gdn day, tnmg bmh moi nam a Viet Nam xay ra khoang 650 vu chdy, thi?t h^i trung binh 4.340 ha rimg, trong do rung trong khodng 3.200 ha va rirng t\f nhien khoang 1.I4D ha. Nam 2002, chdy rung cr U Minh Thugng va U Minh Ha dd thieu buy 5.500 ha rijrng Tram, trong do co 60% la rimg Tram nguyen sinh. Ddu nam 2010, chdy rung tai Vuon Qu6e gia Hodng Lien - Lao Cai, thi?t hai bon 700 ha riing. Nhiing ton thdt do chay rirng gay ra ve kinh te, xa hgi va moi truong la rat Ion vd kho c6 thi tinh dugc (Bao etal., 2017).
Cong tac qudn Iy chdy rimg, phong ehay va chiia chdy rimg a Viet Nam dS duqc phdn cap cu th^ eho cac chii rimg, cdc ca quan quan ly til trung uong den dja phuong. Tuy nhi^n, do miie do dau tu va quan tam chi dao quan ly o cac dia phuong la khae nhau. Trong nhieu tniong hgp, ehay rimg xdy ra, thzLm chi xdy ra
tren di?n rgng moi phat hi?n dugc, va ket qua la gay ra nhilu kho khan trong eong tac chira chdy rimg. De nang cao hieu ciia cdng tac phong ehdy va chua chdy rung, thong tin vl nguy eo chay ho|c thong tm ve ddm chay rimg cdn dugc phat hien mot cdch kip thoi, chinh xac de cac cap qudn ly rimg c6 giai phap phu hgp trong viec phong vd chiia ehay rimg, giam thieu nhiing thi$t hai do chdy rimg gdy ra. Tit ly do tren, nhom nghien cihi da tien hanh ling dyng thuat todn phat hien chdy rimg ciia Louis Gigiio va cgng sy phdt triln nam 2003 dya tren thug-t toan goe eua Kaufinan naml993 (Louis et al, 2003) de trich xuat diSm di thuong nhiet tir anh ve tuih MODIS nhdm phuc vu phat hi?n som chay rimg a Viet Nam.
II. PHlTONG PHAP NGHIEN CUtJ Phuong phap nghien ciki ling dung thuat todn de trieh xudt diem d\ thuong tit anh ve tmh MODIS dugc khai qudt trong hmh 01.
2.1. Vat lieu nghien ciru
Tu lieu dnh viln thdm dugc su dyng de nghiSn cuu trong phdn mem ndy Id anh MODIS Lever 1B. Anh Modis eo 36 kgnh ph6, trong do sii dung ede kenh tir dnh sang nhm thay den can hong ngoai de phat hien cdc khu vye CO ehdy. Anh MODIS dugc khai thac hue tigp tir website eua Co quan hdng khong va vu trvi Hoa Ky - NASA (www.earthdata.nasa.gov;
www. ladsweb.nascom.nasa.gov).
94 T ^ P CHI KHOA HOC VA CONG N G H | LAM NGHIEP SO 1-2018
Qudn ly Tdi nguyin rirng & Moi trwdng ANH V ? TINH MODIS
(Dirge cung cap boi co quan Hang khong va Khdng gjan Hoa Ky_NASA)
Xdc dinh ldp phu be mat mdy vd nude
THUAT TOAN TRICH XUAT DIEM DI THlTOfNG NHI$T Xdc
dinh diem ndng chay dang hogt dpng
Ngit&ng Idem tra
tuy ft dm Bgc tinh nen
Idem tra ngif canh
Phdt diemdj thudng nhiet
Hf thong
A
Sem£
thudng nhiet thupc
lanh tho PlelNam
Xdc dinh phdn bd diem ^ thudng theo thdi g (thdng)
Phdn bo diem dj thudng theo khdng gian (tinh, TP/Viing)
So sdnh xac dinh miic 3^
phu vdi mua chiiyrihtg/
phan bo iSai lich rung d Vi^Nian
Hinh 01. Sff do phircmg phap nghien ciru trich xuat diem di tbuwng nhi£t tir anh ve tinh MODIS
2.2. Thu^t toan trich xuat diem d| thuimg nhiet Thuat todn phdt hien diem nong chay dugc thyc hi$n sii dung theo thudt toan thac sy phat ra manh biic xa ciia kenh hdng ngoai trung (Louis Giglio et al., 2003). Cdc budc boat dgng cua thuat toan nhu sau:
(1) Xdc dinh Idp phu bi mat mdy vd nude: Nhirng diem ban ngdy dugc coi la bi may ehe khudt neu thoa man dieu kien:
(Po 65 + Po ^^ O-S) II (T,2< 265K) || (p„ , , + p „ , 5 > 0 . 7 & T , j < 2 8 5 K )
Nhung diem ban dem dugc xac dinh la mdy nSu thoa man dieu ki?n duy nhdt T,2< 265K.
Ti6u chf CO bdn nay eo the xac dinh dugc
nhiing ddm may \an vd lanh hon, nhung co the bo mit nhiing dam may nho vd ede ria ciia ddm may. Tuy nhien, nhiing diem nong ehay khong quan sat dugc khong bj nham lln Id dam may (Christopher Justice vd cgng su, 2006; Louis Giglio vd cgng sy, 2003).
(2) Xdc dfnh nhihtg diem nong chdy dang hopt dpng: Mgt diem anh ban ngay dugc xde dinh Id mot diem chay tiem nang n6u thoa man dieu kien:
T 4 > 3 I 0 K , A T > I 0 K & P ( , g g < 0 . 3 v a i A T
= T , . T „ .
Voi nhung diem ban dem neu thoa man dieu kiSn:
T ^ CHI KHOA HOC VA CONG NGHE LAM NGHIEP SO 1-2018 95
Qudn ly Tai nguyen nhtg & Moi trudng T 4 > 3 0 5 K , A T > 1 0 K & p „ j 5 < 0 . 3 v a i A T
= T , . T „ .
Nhung diem khong thoa man thii nghidm so bg ndy c6 the phan loai ngay thdnh nhiing diem kh6ng ehay.
Co hai huong de qua do cdc dilm nong chay CO the duge xdc dinh. Huorng ddu tien la sii dung mgt kiem tra nguot^ tuySt doi, eo dinh don gian. Ngu5ng nay phdi dugc thi6t l^p dii cao de no chi dugc kich boat khi cac diera nong chay la rat ro rdng va rdt it ca hgi tao ra nhutig cdnh bao sai. Huong thu hai la chua dyng m^t ehuoi nhirng kiem tra nguong ngii eanh dvttjc thiet kS sin de xac dinh dugc phan Ion nhiing didm nong chdy dang hogt dgng nhung kem ro rang,
(3) Ngudng kiem tra tuyet doi: Tieu chf ve ngudng kiSm tra tuyet d6i la van gidng vdi vi?c Iam trong thu^t toan g6e ndm 1998 (Louis Giglio et al., 2003).
T4 > 360 K (320 K v6 dem) (I) Tuy rSng nguong ki6m tra ban ngdy eao nhung dugc su dung de loai bd nhiing tia sdng mat troi, neu khong nhung tia sang dii manh lde len eiia mat trdi ed the gdy ra canh bao sai.
(4) Bpc iinh nen cua ddm chdy: Nhirng di8m ldn c^n xung quanh ciia digm ndng ehdy dugc Sii dyng de udc tinh mgt gid tri n6n ciia dam chay (khung ciia so). Nen ciia nhiing diSm nong chdy dugc xdc dinh la co T4 > 325K vd AT > 20K d tnidng hgp quan sdt ban ngay;
hoac T4 > 310K vd AT > lOK d truong hgp quan sat ve dem.
Ciia so bat ddu nhu mot diem hinh vudng 3x3 pixel bao xung quanh diem ndng chdy tiem nang. Su bao ximg quanh cd thi ldn len din toi da la 21 x 21 pixel neu cdn thiet, den khi ft nhat 25% nhung di6m dnh trong khung ciia sd dugc cho Id hgp le va so lugng nhiing dilm dnh hgp le it nhdt la 8 diem (Louis Giglio et al., 2003).
(5) Ngudng kiim tra ngO- cdnh: N8u cac
d|ic tfnh nen ed ket qua, mgt loat cae ki6m tra theo ngu5ng ngir eanh dugc thye hi^n dk phai "
hien cac diem chay lien quan. Sy tim kilm cho ddu hi6u d^c tnmg ciia mdt diem chay hoat dgng trong ed kenh nhi$t sdng 4 (tm (T4) va d?
l?ch (AT) giiia kenh nhi^t sang 4 pm vd 11 ^tn tir mgt nin khdng ehdy. Nguang tuong d5i dugc dieu chinh dua trSn nhirng thay ddi tu nhidn cua nen. Sy kiem tra dd la (Louis Giglio et al., 2003):
AT>AT + 3.5 8iT (2) A T > A T + 6 K (3) T4>T4 + 3S4 (4) T n > T n + 5 n - 4 K (5) 6'4>5K (6) Dau tien 3 diem chdy dugc tach ra tir nin khong chdy. He sd 3.5 xudt hien trong kiem tra (2) ldn hon hd sd 3 trong kiem tra (4) dd giup dieu chinh tuong quan giiia kenh quan sat 4 (im vd 11 \im. Didu kien (5) gidi ban cho nhung didm ban ngay, duge sii dung chii yeu de loai bd cac didm dnh nhd eua may co thi xuat hien am len d kdnh 4 pm (phu thupc vao sy phat xa cua tia sang mat trdi) nhung vln mdt trong kenh II pm. Nd ed thd giup giam bdt cac canh bdo sai midn ven bidn thinh thoang vdn xay ra khi nhiing didm anh nude mat hon v6 tinh co trong khung ndn ciia so.
Tuy nhien bdt ky su kiem tra nao trdn Sj,, nhiing nii ro loai bd nhiing diem ndng chay la rat ldn vi chiing lam tang ddng ke ndn cua kenh 11 pm. Vf dy: Tren mgt bd mat ddt pho bien 8j, ~ IK trong khi do nhiing didm dnh tren viing ddt noi vdi mgt viing ehdy rimg ldn 811 se thudng xuyen vugt ngudng 20K. Vi ly do ndy, kiem tra (6) se lam vd hidu kidm tra (5) khi ma khung ndn xuat hidn chiia dyng nhihig dam chdy ldn (Christopher Justice va cgng si;, 2006; Louis Giglio va cgng sy, 2003).
(6) Phdt hi^n diim nong chdy: Vdi nhiing diem chdy vao ban ngay, 3 budc sau dugc sir dyng dd giup loai bo nhiing cdnh bao sai bcri 96 TAP CHi KHOA HOC VA CONG NGH|: LAM NGHIEP SO 1-2018
Qudn ly Tdi nguyin rung & Mdi trudng nhiing tia sdr^ mdt trdi, bl mat sa mac ndng
hay eac bd bien hoac cdc tuydn ven bd bien (Louis Giglio, at all 2003).
- Diem chdy ban ngay neu:
{(2)true)\\
{(2) (4) tme && [(5) \ \ (6) true]).
Con lai se Id khong chdy.
- Diem chay ban dem neu;
{(l)true)\\
((2)-(4) true}.
Con lai se Id khong chdy.
Ddi vdi nhiing diem ban ngdy vd cd ban ddm khi md dae tfnh ndn khdng thda man, sd lugng nhiing didm dnh hgp Id dugc xac dinh khdng dli, ehi duy nhat kiem tra (1) duge dp dyng d day. Neu diem anh khdng thda man, nd se dugc phdn loai Id "chua bidt", thuat toan khdng thd dua ra dugc kdt luan ro rdng.
Kdt qud ddu ra eiia thudt todn la dii lieu san pham didm di thudng nhiet dang Text, chiia thdng tm ca bdn (bang 01).
Ten tnrcmg Kieu dfr lieu
Bang 01. Bang cau triic dir lieu cac diem di thuong nbi|t Motd gid
latitude ongitude brightness
scan track acq_date acq_time satellite confidence
geom bright T31
frp
serial real real real real real date integer
Char integer geometry
real real
Khoa chinh (m§)
VT d$ ciia didm chay trong gdc thap phan (WGS-84) Kinh dd cua dilm chdy trong g6c thdp phan WGS-84) Nhiet dp kenh sang 21/22 dugc tmh theo thang do K.
Kich thudc diem quet Kich thudc diem theo d5i Ngay ve tinh thu nhpi dft heu diem chay
Thdi gian ciia diem chay (UTC).
Yd tinh thu thdp dii li6u: 'A' Id Aqua, 'T' la Terra Cung cap miic do tin cay (0-100%)
Vi tri ciia diem chay
Nhilt dp kenh sang 31 dugc tinh theo thang dp K Nang lugng phat xa
2.3. Xac d|nb phan b6 diem di thvdng nbi|t theo thoi gian va khdng gian
- Xac dinh dilm di thudng nhiet thudc lanh thd Viet Nam: U'ng dung phdn mem ArcGis 10.4 (Tran Quang Bdo vd cgng sy, 2013) dd chdng ghep len ranh gidi hdnh ehinh ciia Viet Nam xdc dinh cac dilm di thudng nhiet nam tren lanh thd Viet Nam. Kdt qud Id danh mye cdc didm d} thudng nhigt ehiia dyng cdc thdng tin v l xa, huydn, tinh eiia Viet Nam.
- Xac dinh diem di thudng nhiet phan bd theo thdi gian va khdng gian: Tren ca sd ket qua ciia budc tren se xac dinh dugc phdn bd dilm dj thudng nhidt phan bd theo thdi gian vd khdng gian bdng phan mem iing dyng Microsoft Excel.
- So sdnh muc dd phii hgp ciia diem di thudng nhidt vdi phan miia ehdy rimg d Vi|t Nam tir nhiing kit qua nghien'ciiu da cdng bd.
IH. K ^ T QUA VA THAO L U ^ 3.1. Ket qua tricb xuat diem dj thvong nhift til'dnh v^tinb MODIS
Tir so dd phuong phdp nghidn cuu d hinh 01 va kit qua Iua ehgn tu hdu dnh vg tmh thich hgp, nhdm tdc gia tien hanh download dnh vd tinh modis tii website eua NASA, ddng thdi ling dung thudt toan ciia Louis Giglio va cgng sy phdt trien nam 2003 dya trdn thu|lt toan gdc eiia Kaufinan nam 1998 (Louis Giglio et al., 2003) tu ddng xii iy dii lieu kdnh 20, 22 vd 31 eung vdi anh mdt na may dd t^o ra du lieu chay dudi dang anh va danh mye cac didm dl thudng nhiet.
Kdt qua xu Iy dnh vd tinh MODIS bang thuat toan (sau khi dd loc nhimg diem di thudng nhiet khong thupc lanh tho Viet Nam) cho ket qud: 123.558 diim di thudng nhiet. Vd ban chdt, thudt todn phdn tich dii lieu tir dnh vd tinh MODIS bdng each su dyng cdc kdnh can TAP CHI KHOA HOC VA CONG NGHE LAM NGHIEP SO 1-2018 97
Qudn ly Tdi nguyin rirng & Mdi trudng hdng ngoai vd qua dd cd the phdt hien ra sy xuat hidn eiia cac diem di thudng nhiet. Tiiy thugc vdo su chdy dang dm i hoac chay rye, hoac do hidu ling nhd kfnh... de cd lugng nhidt nhdt dinh, d nhiet dg nay co m$t phat x^ rat manh trong vung edn hdng ngoai. Phat xai bdi mgt ddm chdy tuong phdn msinh vdi mgt ndn khdng ehdy. Mpt diem chay dugc xdc dinh trong mdt diem dnh khi md sy tuang phdn giua cac diem anh vd mdi trudng xung quanh nd dii eao.
Do vay, nhiing dilm di thudng nhidt dugc thudt trich xudt tii thudt todn d ddy la nhiing didm ehdy rimg dang dien ra ho^c cac la diem chay rirng tilm nang, co thd la ddt nuang dly, tir vimg dat trdng trgc, cac khu cong nghiep hoac sy ndng len cua khu dd thi trong miia he...
De danh gia miic dO phii hgp eiia cdc di^m di thudng nhidt do thudt todn trieh xudt tii tu li?u dnh vd tinh MODIS trong didu ki?n ciia Vidt Nam, die bidt la xem xet dudi goc (1$
phdn miia chay rimg theo vung dia ly d Viet Nam, tac gia tien hanh phdn tfch va danh gia s|r phdn bd cdc diem di thudng nhidt theo khong gian vd thdi gian.
3.2. Ket quS phan b^ cac diem di thirong nhidt theo khdng gian
Tir ket qud trich xudt diem di thudng nhiet, tdc gid tien hanh tdng hgp va md ta su phan b6 cac diem di thudng nhiet theo khdng gian tu nam 2010 ddn nam 2015 dd xdc djnh miic dg phii hgp ciia ede didm di thudng nhidt vdi miia ehdy rimg tai cdc vimg dia ly (hinh 02, bang 02).
PHAN BO DIEM Dl THU'ONG NHIETTHEO KHONG GIAN
D Jem_di_thu on g_n tuet IRGXVN WGS1S84
Hinh 02. PhSn b6 dilm d| thufrng nhiet theo khdng gian giai doatn 2010 - 2015 T ^ CHI KHOA HOC VA CONG NGHE LAM NGHIEP SO 1-2018
Qudn ly Tdi nguyin rung & Mdi trudng Bang 02. Phan bo cac diem di thuihig nhiet theo viing d|a ly
Vimg dia ly Phin bl dilm di thirong nhi|t theo khdng gian 2013 2014 2015 Dong b4ng S6ng Hong
Dong B3c BQ My Bac B8 Bac Trung Bg Nam Tnmg Ba Tay Nguyen Dong Nam Bp MyNamBa
199 2123 7548 2310 1771 7073 2041 2180
278 801 2446 1627 1671 6962 1539 876
228 1255 6230 1539 1783 6029 1177 1436
211 196 303 1254 1480 1700 3606 6314 4208 1793 2190 2744 2199 3105 3718 5214 5766 5502 1171 1419 1607 1850 2056 2830 Kdt qua trdn eho thay: Phan bd cac diem di
thudng nhidt d nude ta tii ndm 2010 - 2015 tap trung tli 15 den 25 nghin diem, tuy dieu kidn khf hdu timg nam khdc nhau se xudt hidn ede didm di thudng nhidt khdc nhau. Xet vd khdng gian cdc didm di thudng nhidt ehu ydu phdn bd tai ede tinh thudc viing Tay Bde: 46.519 diem (tap trung tai tinh Didn Bidn: 19.714 diem; Son La: 16.256 didm vd tinh Lai Chdu: 9.740 dilm); viing Tdy Nguyen: 52.221 diem (tap trung tai tinh Kon Turn: 14.238 diem; Gia Lai:
12.918 diem va tinh Dak l i e : 11.057 dilm);
vung Trung Bd: 38.217 diem (tap trung cao tai tinh Nghd An: 8.086 didm va tinh Quang Nam:
1
947 diem); sau do la ddn cdc viing Tay Nam Bang 03. Tong h^p pbSn bd dilmBd: 15.689 dilm, vimg Ddng Bde Bg: 13.809 didm, vung Ddng Nam Bg: 13.000 didm vd cudi Cling la viing Dong bdng Sdng Hdng:
2177 dilm. Nhin chung cdc diem di thudng nhiet d nhiing tinh cd nhieu didn tfch rimg vd ddt rimg.
3.3. K i t qua ph^n hh cac dilm di thucnig nhiet tbeo thdi gian
Tir so lieu cdc didm di thudng nhi^t tir nam 2010 - 2016 trong pham vi cd nude, tac gid da tdng hgp dd xde dinh sy phdn bd diem di thudng nhidt theo thdi gian, eu the Id su phdn bd theo cdc thdng trong nam. Kit qud dugc tdng hgp theo bdng 03 vd hmh 03.
di thirong nhi^t theo thoi gian
TT Thoi gian So diem di thudng nhift Ghi chii
1 2 3 4 5 6 7 8 9 10 11 12
Thang 1 Thdng2 Things Thang 4 Thang 5 Thang 6 Thang 7 Thang 8 Thang 9 Thang 10 Thang 11 Thang 12
13608 29867 55116 35995 15728 8342 4457 4577 3130 2591 2814 5407
2010-2016 2010-2016 2010-2016 2010-2016 2010-2016 2010-2016 2010-2016 2010-2016 2010-2016 2010-2016 2010-2016 2010-2016
TAP CHi KHOA HQC VA C 6 N G NGHE LAM NGHIEP SO 1-2018
Qudn ly Tdi nguyin rumg & Moi trudng 60000 bU g 50000
^ 40000 . t l , t > 30000
"^ ^ 20000
•^i 10000
.1
w/ A \
/ X_
1 2 J 4 5 6 7 Thdng
8
»
IU 11 12Hinh 03. Bilu dl phdn bo dilm d| thirorng nhiet theo thM gian trong to^n quic Kdt qua cho thay cdc diem di thudng nhiet
xuat hien chii ylu tit thang 11 nam trudc den thdng 6 nam sau, tham chi ddn thang 7 va tdp trung chii ydu thang 1 den thdng 5, d|c bi?t la cac tinh khu vyc phia Bde, sau khi hidn tugng mua phim giam (thudng la thang 2) hidn tugng xuat hi?n nhidu dilm di thudng nhiet la thdng 3 vd thang 4. Sd di co sy xudt hien nhidu diem di thudng nhidt nhu vdy Id thdi ky miia kho ban keo ddi ndn hien tugng kho hanh cgng vdi nhiet lugng tii mat trdi da lam tang nhidt do be
Bang 04. Phdn bl dilm di thirdng nhiet theo thoi gian tai cac viing dia ly m^t dan sy phat xa nhidt tu bd mat dat, va hen thyc t l thdi diem nay thudng xay ra chay riing d ede viing midn trong ca nude. Tuy nhidn, tiiy theo tung dia phuang hoac vimg dia 1;^ khac nhau cd thd xudt hidn nhieu hay it hoac keo dai thdi gian xuat hidn dilm di thudng nhidt khac nhau. Dd tim hieu sau vd ro ban ve vdn dd nay, tdc gid tdng hgp va phan tich dac diem phSn M cac didm di thudng nhidt theo thdi gian tai cac vimg dia ly trong pham vi ca nude theo bang 04 vd hinh 04.
Viing dia 1<
T l E>6ng bing y.^
Sdng Hdng
DongBicB? 1504 T a y B i c B ? 2401 Bac Trung Bp 592 Nam Trung Bo 283 Tay Nguyen 6266 Dong Nam Bp 1775 Tay Nam Bp 750
30000
f
f 20000
1
.a g 10000 13
T2 17 2506 9897 1144 795 11734 2121 1653
1 T3 30 ' 2911 17864 2145 2737 20058 2824 6547
2 3
PhSn b6 diSm d| thirong nhiet theo thM gian T4
191 2186 11240 3694 3874 9819 1994 2997
4 T5 311 1986 1914 3704 3997 1766 1037 1013
T6 277 648 93 3295 2256 493 677 603
5 6 7 Thang
T7 T8 T9 334 459 396 233 142 163 14 27 72 1001 607 647 1804 2257 1272 224 125 87 429 406 278 418 554 215 TIG
72 264 419 483 618 66 470 199
• Viing Dong bang Song Hong
—•—VCing D6ng Bac Bg
—•—ViingTly Bac Bg
—•— Viing Bac Tmng B$
—•—VCing Nam Trung Bg
—•—Vung Tay Nguy&n
—•—ViingDong Nam B$
8 9 10 11 12 T i l
20 331 1388 355 131 170 271 148
TO 33 935 1190 43S 91 1413 718 592
Hinh 04. Bieu do phSn bo dilm di thirovg nhiet or viing dia ly theo thoi gian T ^ P CHI KHOA HOC VA CONG NGHE LAM NGHIEP SO 1-2018
Qudn ly Tdi nguyin rung & Mdi trudng
Tit kdt qua cho thdy: Cdc viing trgng diem va ed sy thay ddi ro v l sy phan bd cac didm di thudng nhiet Id viing Tdy Nguyen, Tdy Bde Bd va Tay Nam Bd, cac dilm di thudng nhidt thudng xudt hidn tap trung tix thang 2 den thdng 4 vd dinh dilm thang 3 hang nam. Tuy nhidn, miic dg xuit hidn cdc diem di thudng nhiet tai khu vuc Tnmg B$ lai co xu hudng tang din tii thang 3, thang 4, thang 5 va thdng 6, miic cao nhdt la thang 4 va thang 5. Vdo eac thdng 8, thang 9 va thang 10 hdu nhu cac viing
trong ca nude it xuat hien diem di thuang nhi?t.
Mat khac, trong nghidn cuu 'Thuong phap dy bao nguy co chay rirng theo didu kien khi hiiu d Viet Nam" ciia Ld Sy Doanh va Vuong Van Quynh (2014) dd xdc dinh duge cdng thiic tinh ehi sd khi hau phdn dnh nguy co chay rung Qi qua eae ehi sd khf hdu co bdn la nhiet dg va lugng mua, ddng thdi kit qua nghien cuu nay cung da khang dinh nguy ca chay rung cao d Vidt Nam thudng xuat hien chu yeu tir thang 11 ddn thdng 4 nam sau (Doanh et al., 2014).
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Thang Hinb 05. Dien bien nguy ZG chay
trong nhirng thoi Tir kit qua tdng hgp miic do phdn bd cac dilm di thudng nhiet theo thdi gian va khdng gian ciia nghidn cuu nay cho thdy, tucmg doi phii hgp vdi cae ket qua nghien cuu ve phdn viing trgng didm chdy rirng va phan miia chdy rimg toan qudc trudc ddy (Doanh et al, 2014).
Didu ndy da chung td rdng vide sir dung thudt toan cua Louis Giglio va cdng sy phat trien nam 2003 dya trdn thu^t todn goc ciia Kaufinan nam 1993 (Louis et a l , 2003) ty dgng xii ly dfi lieu kdnh 20, 22 va 31 cua anh vd tinh MODIS ciing vdi anh mat na may dd trich xudt ra du lieu chay dudi dang dnh vd danh muc cdc diem chay d l phat hi?n vd cdnh bdo chdy rimg d Vi^t Nam Id hodn toan phu hgp va cd ca sd.
rumg trung binh tren ca nirdc 1^ khac nhau
IV. KET LUAN
Anh vd tinh MODIS la tu heu thich hgp sii dung trong phdt hien sdm chay rimg d Viet Nam. Anh ve tinh MODIS dugc thu nhdn tir hai he thdng vg tinh ehhih TERRA MODIS va AQUA MODIS ed mye dich cimg cap dfl lieu ve ddt lidn, biln vd khi quyen mgt each ding thdi va dugc cung cdp midn phi. Anh chyp tu vd tinh MODIS cung clp dii lieu dnh todn edu 4 dnh trong 1 ngay, 2 anh ban ngay va 2 anh ban dem. Anh MODIS cd 2 kenh phd 4 pm sd 21 va 22 dugc thilt k l dac bidt vd huu ieh eho vide phat hidn dam chay.
Thudt toan iing dyng d l trich xuat cac diem di thudng nhigt d l phat hien chay rung Id thudt toan ciia Louis Giglio va cdng su phat tridn Ti^P CHi KHOA HQC VA CONG NGHE LAM NGHIEP SO 1-2018 lOI
Qudn ly Tdi nguyen rimg & Mdi trudng nam 2003 dua trdn thuat toan gdc cua Kaufarm nam 1993. Thuat toan sii dung cac kdnh hong ngoai nhiet ciia anh ve tinh MODIS dd phat hien diem di thudng nhiet tren mdi diem dnh CO ban, thuat toan ty ddng xu ly dii lieu kenh 20, 22 va 31 cimg vdi dnh mat n^ may dd tao ra du lidu chdy dudi dang anh vd danh mue cac diem di thudng nhiet.
Kdt qud thir nghiem thudt toan de trich xuat diem di thucrng nhiet da khdng dinh sy phii hgp vdi miia chay rimg theo thdi gian cimg nhu theo khdng gian d Viet Nam.
TAX LIEU THAM KHAO
I. Trka Quang Bao, Chu Ngpc Thuan, Nguyin Huy Hoang (2013). GISvaviin thdm. Giao trinh Tnrdng
Dai hpc Lam nghiep, Nha xuit ban Nmg nghiep. Ha N(iL 2. Tran Quang Bao (2017). Nghien cuu sd difng cong nghg khdng gian dia l^ (RS. GIS GPS) trong phat hien chdy rimg vd gidm sdt tdi nguyen rimg. Qk t^
nghien cmi khoa hpc cap Bp, Hfl N6i.
3. Christopher Justice, Louis Gi^io, Luigi Boschetti, David Roy, Ivan Csiszar, Jeffrey Morisette and Yoram Kaufinan (2006). Modis fire products.
Version 2.3, 1 OctobCT 2006, Algorithm Technical Background Document
4. IA Sy Doanh, Virong Van Quynh (2014)., Phuong phip d\r bao nguy co chay riing theo di6u ki^i khi hau 6 Viet Nam. Tgp chi Khoa hgc Cong ngh$ ldm nghiep, S6 1/2014.
5. Louis Giglio, Jacques Descloitres, ChristO[Aef O. Justice, Yoram J. Kauhnan (2003). An Enhanced Contextual Fire Detection Algorithm for MODIS Remote Sensing of Environment 87,273-282.
A P P L I C A T I O N O F A L G O R I T H M T O E X T R A C T F I R E H O T S P O T F R O M M O D I S S A T E L L I T E I M A G E S F O R F O R E S T F I R E DETECTION
I N V I E T N A M
L e N g o c H o a n ^ T r a n Quang Bao^
''^Vietnam National University of Forestry S U M M A R Y
This article presents the results of applying the algorithmic of Louis Giglio developed in 2003 based on Kauiarm's original algorithm in 1993 to extract the thermal anomalies from the MODIS satellite imagery to detect forest fires in Vietnam. To assess the possibili^ of extraction and relevance of results in Vietnam, ttie authors used MODIS imagery from 2010 to 2015 to extract heat anomalies, synthesize and analyze the distribution of thermal anomalies over time and spatial. The analysis of fire hotspots distributicHi by time and spatial are quite suitable with previous resuhs of forest fire region and season in Vietnam. This is an impMtant scientific basis for applying MODIS satellite imagery to detect and alert forest fires in Vietnam, Keywords; Fire hotspot, forest fire, forest fire detection, MODIS.
Ngay nhSn bai Ngay phan bien Ngay quyet dinh dang
28/12/2017 25/01/2018 05/02/2018
102 T ^ CHI KHOA HOC VA CONG NGHE LAM NGHIEP SO 1-2018
