Tap chi KHOA HOC BHSP TPHCM Sd 36 ndm 2012
PHAN TICH BIEN DONG SU DUNG DAT B A N G ANH LANDSAT - TRUOfNG HOP TINH DAK LAK
GIAI DOAN 2000-2010
T R A N H A P H U - O N G * . N G U Y E N THANH HIJNG"
TOiVf T A T
Sir Ihay ddi hi('n trgng .sir dung dat cua tinh Dak Ldk giai doan 2000-2010 ductc xdc dinh bdng dnh Landsat. Phuang phdp nghien ciru bdng dnh Landsat duac .sir dung trong hdi vicf ndy cd ihc du(.fc dp dung trong truang h<,rp thieu dir lieu kiem chirng thuc te hoac khdng cd kha ndng kiem ti a hi('n truang luang irng IY// thai gian thu chup dnh.
Tir khda hipn trang sir dyng dat. DSk Lak, Landsat, giai doan anh.
ABSTRACT
Analyzing landuse changes by using Landsat images - case of Dak Lak province from 2000 to 2010
The landuse changes of Dak Lak province were identified using Landsat images from 2000 to 2010. Compared with the land use map in 2000. the results from the Landsat images interpretation is acceptable. Research methods used in this paper, can be used in the absence of actual test data or not able to check out the collection corresponding lo the time of photography
Keywords: land use. Dak Lak, Landsat, image interpretation.
1. Gioi thieu
Tinh Dak Lak nam 6 cao nguyen Nam Trung Bp, co tpa dp dia li tir 11°30' d^n 13°25' vT dp Bac va 107°30" d^n 109°30' kinh dp Dong; phia Bac giap linh Gia Lai; phia Nam gidp tinh Lam Dong va linh Dak Nong; phia Dong giap linh Khanh Hoa va linh Phii Yen: phia ra> giap vuang quoc Cam-pu-chia.
Dak Lak CO dien tich tu nhien 13,085km^, phan Ion dia ban thupc suan Tay Nam day Trucmg Son nen dja hinh niii cao chiem 35 % dien tich ty nhien, tap Irung a phia Nam va Dong Nam tinh vai dp cao Irung binh 1000m - 1200m.
Dia hinh cao ngu>en bang phang nam 6 giira tinh, chiem 53% dien tich tu nhien vai dp cao trung binh 450m. Phan dien tich tu nhien con lai !a vung thap, bao gom nhung binh nguyen a phia Bac tinh va cf phia Nam Ihanh pho Buon Ma Thupl [1]. Vai Igi the dia li. Dak Lak co vj tri chien lupc ve kinh te va an ninh quoc phong.
Hang nam, vao miia mua, Dak Lak thucmg bj lu va sat la dat, gay thiet hai nghiem trpng ve nguai, tai san va anh huong khong nho den san xuat. Co nhieu nguyen nhan dan den hien trang tren, trong do viec sir dung dat va bo tri san xual chua hcfp li la cac nguyen nhan chii
Tap chi KHOA HOC DHSP TPHCM Tran Hd Phuang va Igk
Do do, de ban chS din muc thip vao cdng tac phdng chdng thien tai tren nhat nhung thiet hai neu tren, cdn phai dia ban tinh.
theo ddi bidn ddng hien trpng su dung ddt 2. Tu- lieu va phuong phap nghien trong nhung nam qua, nhim kip thdi dua ciiu
ra nhirng giai phap cin thiSt, gop phjn 2.1. Tu lieu su dung
Hinh 1. Khu vuc nghien ciru
Nguon: Bo Tin nguyen vii Mdt tnrdng. ban dd nen dia hinh tile T50 000 Ban dd nen dia hinh nam 2000, ti le
1:50.000 vdi ludi chidu UTM, Datum Indian 1960, vung 49 (xem hinh 1);
Anh Landsat nam 2000 va nam 2010 cd dp phan giai 30m x 30m duac sii dung de thanh lap ban dd hien trang sii dung dat;
- Ban dd (giay) hien trang sii dung djt tinh Dak LJk nam 2000, ti le 100000 dugc sii dung de lam khoa giai doan anh nam 2000 va kiem chiing ket qua ciia nam 2000;
- SiJ dung khda giai doan neu tren, cd ddi chieu va so sanh vdi cac tu lieu, du lieu vien tham da cd, de giai doan anh nam 2010 va lap ban dd hien trang sir dung dat nam 2010;
Phan mem dugc sii dung trong nghien ciiu bao gdm: Envi va ArcGIS.
2.2. Phuang phdp nghien cuu Quy trinh danh gia bien dgng hien trang sil dung 6k gdm cac budc theo so dd sau day:
113
Tap chi KHOA HQC DHSP TPHCM Sd 36 ndm 2012
BAii Ah 11 rSDD 2000 (girty)
sAlifu living k£ Anh Landsal 2000
- Ti^n xir li
• TAng cirirntt ch^l I iron ^
DO mSu SO bO
C h u y i n sang Vector
Ban d o H T S D D 2 0 0 0
Ban do n^n ndm 2000
Anh Landsat 2010
B$ miu chudn
Chu>in sang Vector
Ban do HTSDD 2010
Bicn dong HTSDD
Sa do quy trinh ddnh gid bien dgng hi^n trgng su dung ddt
Theo sa do quy trinh ddnh gid bien dpng hi$n trgng su dung ddt, dong thai dui vao cac so lieu thu th^p dupc nhu: ban do nen GIS, ban do hi?n trang sii dung dat nan 2000 (ban do giay), anh Landsat 2000 va 2010, cac buac dugc tidn hanh lin lupt nhi sau:
Tien xir li anh Landsat nam 2000, tang cuang chat lugng anh: gian anh, Ipc anh lap anh ti s6, tao kenh chi s6 Ihi^c vat (NDVI),... tao Ihuan Igi cho viec giai doan ban^
mat (xem hinh 3). [2]
T?p chi KHOA HOC DHSP TPHCM Tran Hd Phuang vd Igk
Phan loai anh: Xac dinh cac loai hinh sir dung dSt can phan chia, sau dd chpn cac vung mau tren anh tuang ung vdi sd lugng loai hinh sii dung ddt cdn thanh lap. Viing mau, tuang img vdi timg loai hinh sir dung dSt, dugc chgn cd so lugng pixel du Idn, so vdi sd lugng pixel ciia mgt loai hinh su dung dat chiSm gid (cd ddi chieu va so sanh vdi ban dd (gi^y) hien trang sii dung ddt nam 2000; va cd ddi chieu vdi dit lieu chua xir li cua anh Landsat nam 2010), sao cho cac gia tri trung binh cung nhu ma tran phuong sai - hiep phuang sai tinh cho mdt loai hinh nao do cd gia tri dung vdi thuc te. Ngoai
ra, Vj tri cua viing mau dugc chgn, cd tap hgp cac pixel chiem giii d trung tam, khdng nen bao gdm cac pixel d bien dS cd su ddng nhit vi dac trung phd; ddng thdi vi tri phan bd cua cac pixel dugc chgn lam vung mdu cung can cd su ddng nhat ve dac trung phd ddi vdi cac kenh phd khac khi sir dung de giai doan phan loai.
- Ket hgp cac ySu td giai doan bing mat vdi viec kiSm chimg tren ban do hien trang sir dung dat nam 2000 (xem hinh 4), tiSn hanh thanh lap bg miu nhu bang 1 sau day:
Bdng 1. Bo mdu sir dung cho viec phan loai cd kiem dinh
So
1
2
3
4
Doi tuoTig
Song
Data
Rintg xanli thuang xuyen
Rimg ngheo
H i n h a n h
H rn
Yeu to giai cloiin (to hffp R G B ; kenh 5, 4 , 3 )
Man xanli dam. xanh den, can tnic min
Tim hong, dm, cau true 16m ddm
Mau xanii, can htic thd
Mau xaiili xeii Ian vdi mau dm dam
Toa do X
193665
178710
221505
156360 Y
1375020
1403940
1376700
1480620
115
Tap chi KHOA HOC DHSP TPHCM So 36 nam 2012
5
6
7
8 Lua
Dat lidiig, cd, biu
Dat liiiug cay lan natti
^HIKRI
1
c
Q
Man xanit, xanh la, cau tnic min
Mau hong xen vdi mau trang, cd lorn dom mau xanh
Mau xanh, xanli tham thanlt timg khoi cd ranh gidi llinh hoc rd rang, tiraiig phan tone man cao so vdi ddi ttrcmg xtmg quanh
Cau tiiic tmn, man xanh thucmg bl chia cat rBt sac net
219435
228300
189165
192345
1409985
1488285
1389855
1409820
Hinh 4. Vt tri cdc diem mdu tren ban do hien trang su dung ddt ndm 2000 (Nguon: SdKhoa hoc vd Cdng nghe Dak Ldk, bdn dd hien trang sie dung ddt
nam 2000, tile 100.000)
Tap chi KHOA HOC DHSP TPHCM Trdn Hd Phuang vd Igk
Can cii vao bd mau da lap, tidn hanh phan loai cd kiem dinh vdi phuong phap Maximum likelihood cho anh Landsat 2000.
Ket qua sau phan loai bang phuong phap xir li anh sd la mgt birc tranh nhidu mau sac ve cac ddi tugng, sir phan bd cua
cac ddi tirgng khdng hgp li so vdi phan bd thuc te, kich thudc cua cac ddi tugng nay qua nhd, chi cd I hoac 2 pbSn tir nlm rieng le va phan bd rai rac xen ke vdi cac ddi tugng khac..., gay khd khan cho ngudi sir dung. Vi thj, phai xir li sau phan loai (xem hinh 5).
(Tniilc kh loc) (Sou khi lpc) Hinh 5. Trudc vd sau khi cdc phdn tir dnh rdi rac (chiem khdng nhieu) duac loc bd
Ket qua sau phan loai dugc chuyen sang ArcGIS de bieu chinh, bien tap lai va ket hgp vdi ban dd nen de thanh lap ban do anh sd hien trang su dung dat nam 2000.
Kiem chiing ket qua giai doan anh Landsat nam 2000 vdi ban dd bien trang su dung dat nam 2000 (giay), sd lieu
^^MWiMsinxS^
thdng ke thay rang ket qua cd su tucmg dong.
Tir nam 2003, khi bg cam bien cua Landsat hi Idi thi cac anh Landsat hi mat dir lieu. De cd the sir dung dugc cac anh nay, can phai xir li lai dir lieu. Chuong trinh dugc sir dung de hieu chinh du lieu nay la OapFill ciia NASA. [4]
(Trudc khi xic li) (Sau khi Hinh 6. Anh Landsat ndm 2010 bi iSi duoc xit li lai.
- Sau khi anh Landsat nam 2010 dugc khdi phuc lai, thi tien hanh nan chinh hinh hgc anh, tang cudng chit lugng anh: gian anh, Igc anh, lap anh ti
(NguSn [5]) sd, tao kenh chi sd thirc vat (NDVI)...
nhu cac cdng doan neu tren.
Dua vao bd anh Landsat nam 2000, 2010 va bg miu chuan da dugc xay dung, tiln hanh phan loai cho anh Landsat nam 117
Tap chi KHOA HOC DHSP TPHCM Sd 36 nam 2012
2010. De tranh sai so Idn thi cic viing mau dugc chgn lam khda giai do4n khdng nam trong phin 16i cua anh Landsat 2010. (lic cdng d o ^ tiep theo dc lap ban dd hien trang sir dyng dat nSm 2010 dugc thi,rc hi?n tuang tu nhu cdc cong doan ciia vice giai doan anh Landsat nam 2000.
Tren ca so 2 ban do hign trang sir dung dat nam 2000 va nam 2010, tien hanh danh gid bijn dgng hi$n trang sir dung dat tir thdi diem nam 2000 den nam 2010.
3. Ket qua
3.1. Hien Irang sd dung dai ndm 2000 Cd 8 loai hinh sii dung dat dugc xac dinh, vdi tdng dien tich la 1.300.716 ha.
Trong do, dit rimg chidm 63,12% vdi 505.984 ha dat rimg dugc phu xanh. [3]
Qua kidm chung giu-a sd lieu thdng ke tren ban do hien trang su dung dit va cac so lieu thong ke cua tinh, thi ket qua giai doan anh Landsat nam 2000 la cd the tin cay.
Tuy nhien, ket qua giai doan anh Landsat nam 2000 thi khdng chi tiet nhu ban dd hien trang sir dung ddt. Su khac nhau nay the hien bang 2 dual day:
Bdng 2. Dien tich cdc loai hinh sir dung ddt giua bdn do hien trang sir dung ddt nam 2000 vd dnh Landsat ndm 2010
STT 1 2 3 4 5 6 7 8 9 10
Ban do HTSDD nam 2000 Loai
Lua 1, 2 vu Mau Mia Caphe Cao su Data Ao, bd Dat trong, cd Rimg xanh thucmg xuyen Rimg ngheo
Dien tieh (ha) 27 100 97 106 410- 65 385 14 005 42 756 47 056 186 788 505 110 315 020
Anh Landsat nam 2000 Loai
Lua 1, 2 vu cay hang nam Cay lau nam Data Ao, ho Dat trdng, cd Rimg xanh thudng xuyen Rimg ngheo
Dien tich (ha) 27 065 97 524 79 379 42 929 47 000 185 742 505 984 315 093 Bang 2 cho thiy, kit qua giai doan
anh Landsat nam 2000 chi phan loai dit trdng cay hang nam va cay lau nSm, ma khdng the chia ra timg loai dat trdng cao su, ca phe, hoac dat mau vdi dat trdng mia nhu d ban dd HTSDD (hien trang sir
tai mgt sd pixel bi lan khdng phan biet dugc, nhimg day van la ket qua cd the chap nhan dugc. [3]
3.2. Hi^n IrQng sir dung ddi ndm 2010 Trong nam 2010, cd 8 loai hinh sit dung dit dugc giai doan, thd hien d bieu
Tap chi KHOA HOC OHSP TPHCM Trdn Hd Phuang va Igk
Bieu do dien tich cdc loai hinh su dung ddt nam 2010
% woooo
-
_o IT" n -
- -
-
nLm C t f M n g C i y l i u CUtli Rung H„ng Ojl tFdng Ao. M
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Dua vao bang 2 va bieu dd dien tich cac loai hinh su dung dat nam 2010, ta thiy dit trdng ca\ lau nam chiim dien tich Ion (174.740 ha), tang cao so vdi nam 2000.
Dien tich rimg khdng ddi. tuy nhien dugc phu xanh nhieu hem. Dit d tang 16.253 ha.
dien tich chua sii dung cdn ldn 154.304 ha.
3.3. Bien dpng hien Irang su dung ddi nam 2000 vd ndm 2010
Sir bien dgng hien trang sir dung dit nam 2000 va 2010 thd hien d bang 3 sau Bang 3. Bien dong hien Irang su dung ddt tu ndm 2000 din nam 2010
Loai Lua Cay hang nam Cay lau nam Dato RiJng ngheo
Rimg xanh thuang xuyen Dat trong, co
Ao, h6 T6ng
Nam 2000 Dien tich
(ha) 27 065 97 524 79 379 42 929 315 093 505 984 185 742 47 000 1 300 716
%
2.08 7,50 6,10 3.30 24,22 38.90 14,28 3,61 100
Nam 2010 Dien tieh
(ha) 32 264 96 383 174 740 59 182 173 755 562 967 154 304 47 121 1 300 716
%
2,48 7,41 13,43 4,55 13,36 43,28 11,86 3,62 100
Bien dong
( % ) •
19,21 -1,17 120,13 37,86 -44,8 11,26 -16,92 0,25 Bang 3 cho thay, cac sd lieu cua
nam 2000 va 2010 cd sir thay ddi, dien tich cay lau nam bidn ddng nhilu nhat (tang 120,13%), dien tich trdng lua tang 19,21%; dit rimg ngheo giam (18,38%), chuyen sang dit rimg xanh thutmg tuyen; dit trdng giam (16,92%), chuyin
sang cac muc dich khac. Nhu vay, cd the nhan thiy viec thuc hien chucmg trinh phu xanh dit trdng, ddi trgc, chuong trinh dam bao an toan luong thuc da dugc thirc hien va dat kit qua kha quan.
119
Tap chi KHOA HOC DHSP TPHCM Sd 36 ndm 2012
han d^ kel qua giai doan anh co the chi liet va chinh xac hon.
Khi dieu kien thuc te khong ihuan lai. thi vi?c sir dung phuang phap nghien cuu bang anh Landsal irong vipc phan lich danh gia bi^n dpng sii dung ddt la Ihuan Ipi v^ hi?u qua, dac biel trong Irucrng hgp lap ban do ti le nho (vi du:
1/100.000- 1/250.000).
4. Ket luan
Tinh hinh sir dyng dai ciia linh Dak I-i'ik CO nhieu bicn d()ng, chu yeu la dat Irong cay lau nam \a dfil a. Dal chua su dyng (dai irong) co sy giam nhanh ve dien lich phan anh dugc loc dp chuyen doi tiem nSng dat dai v^o cac niyc dich phai trien kinh ic xa hpi.
Su dyng anh vien tham dc d^nh gia bien dpng hi(;n irgng sii dyng dat la mgt phuang phdp khoa hpc, hi?n dai. Tuy nhien. cac anh can co dp phan giai cao
TAI Lli.li THAM KHAO
1. Le van Nhat (2008), Kinh te linh Dak Ldk: The manh vd dinh huang phdt trien ben vung thdi ki den ndm 2010, Tuyen tap cac bao cao khoa hpc, Hgi nghi Khoa hpc Dia li toan quoc lan thu 3 ngay 16-12-2008. Nxb Khoa hpc vaKT thuat. Ha Npi.
2. Le Van Trung. Lam Dao Nguyen, Pham Bach Viet (2006), Thuc hdnh vien thdm, Nxb Dai hpc Quoc gia, TPHCM.
3. So Khoa hpc va Cong nghe tinh Dak Lak (2000), Bdn do (gidy) hien trang su dung ddt tinh Ddk Ldk ndm 2000. ti le 1:100.000.
4. Irish Richard (2009), Frame and Fill program, Ver I.O (05-26-09). NASA Goddard Space Flight Center.
5. htlp//glovis usgsgov/
(Ngay Toa soan nh^n duxyc b^i. 22-6-2011. ng^y chSp nh$n dSng 24-4-2012)
