Tap chl Khoa hoc Tru'dng Dai hpc Can Thcf website

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Tgp chi Khoa hpc Tru&ng Dgi hgc Cdn Tha Phdn A: Khoa hgc Tu nhien. Cong nghe vd Moi tnr&ng. 30 (2014)- 78-83

Tap chl Khoa hoc Tru'dng Dai hpc Can Thcf website: sj.ctu.edu.vn

THEO DOI SU* THAY DOl DAT NUOI TRONG THUY SAN TINH AN GIANG TU* NAM 2008 DEN NAM 2012 SU* DUNG KY THU.^T V I £ N THAM VA GIS

Nguyin Thi Hong Diep^ Vo Quang Minh', Phan Kilu Dilm' va Pham Quang Quyet' ' Khoa Moi trudng & Tdi nguyin Thien nhiin, Tnrdng Dgi hoc Cdn Tha

Thong tin chung:

Ngdy nhgn: 22/08/2013 Ngdy chdp nhdn: 25/02/2014

Title:

Aquaculture changes detection in An Giang province from 2008 lo 2012 using remote sensing and GIS technique

Tie khda:

dnh LANDSATETM\ hiin . trgng thuy sdn, dy bdo biin dpng, vd tinh An Giang

Keywords:

LANDSATETW imagery, aquaculture, change detection, and An Giang province

ABSTRACT

Aquaculture is one of the most profitable industries in the An Giang province and key economic sectors not only to bring high profit to farmers but also to increase economic efficiency for the province. It is necessary to manage and detect aquaculture area changes to support management and predict timely changing of the province's aquaculture. This study aims to use the LANDSAT ETM* imagery lo develop spatial aquaculture distribution cmd evaluate the changes from 2008 to 2012. The obtained results showed that aquaculture area increased from 1,937 ha in 2008 to 2,173 ha in 2010 and reduced to 2,038 ha in 2012. The image classification was assessed with high reliability from 70% to 83.33%

between 2008 and 2012. Besides, combining between real data and classified data were evaluated the application and image classification for aquaculture spatial distribution mapping in the An Giang province.

Nuoi trong thuy sdn Id mot trong cdc ngdnh mang lgi lgi nhugn cao cho tinh An Giang, di gop phdn qudn ly chgt che han ve diin tich nuoi trong thuy sdn cdn co su qudn ly vd du bdo kip thdi tinh hinh biin dong cho viic nuoi trdng thdy sdn cda tinh. Di tdi thuc hiin nham myc tieu sir dimg chudi dnh LANDSAT ETM^ xdy dimg bdn do hiin trgng nuoi trong thuy sdn cdc ndm tir 2008 den 2012 vd ddnh gid tinh hlnh biin dong trong giai dogn ndy. Kit qud cho thdy da theo doi dugc biin dong hiin trgng nuoi trong thdy sdn vdi diin tich nuoi thiiy sdn gia tdng tii 1.937 ha (2008) din 2.173 ha (2010) vd gidm xuong 2.038 ha (2012). Dg iin cdy phdn logi dnh qua cdc ndm dugc xdc dinh tir 70% din 83.33% lit ndm 2008 den 2012.

Ddng thdi kit hgp vdi sd lieu thuc ti de so sdnh vd ddnli gid khd ndng img

^dung vd phdn logi dnh vien thdm trong viic xdy dung hdn do phdn bd khdng gian hiin trgng nuoi trong thdy sdn cda tinh An Giang

1 G i m THIEU

Nuoi ttlng thiiy san di v i dang ttd thinh nganh nong nghiep kinh te thi manh ve nuoi thuy sin nude nggt eiia cic tinh Dong bang song Cuu Long dung thu 2 sau lua (Ban chi dao Tiy Nam bd va Trung tim Thong tin Sii Gon, 2005), dac bilt An Giang li mdt ttong cic tinh cd kim nggch xuit

khiu thiiy sin nude ngot Idn nhat ci nude chiem 30% ting gia tri xuit khiu (GTZ, 2009). Thuy san xuit khau ehu yeu la ea da tton nhu ca tta va ca basa, da va dang rat duge ua ehugng tten thi trudng ttong nude v i dac biet la thj trudng quoc tl. Diln tich nuoi ttong thiiy sin loai cua c i da tton nay ngay eing tang do gii tti thuang phim cao eiia nd

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Tgp chi Khoa hgc Tnrdng Dgi hgc Cdn Tha Phdn A - Khoa hoc Tu- nhien. Cdng nghe vd Mai inc&ng: 30 (2014): 78-83 tuy nhien trong thdi gian gin day dien deh nuoi cd

chieu hudng giim xudng do anh hudng ciia nen kinh tl thi gidi (Sd Cong Thuong An Giang, 2013). Do do, vin de quan ly nuoi ttlng, quy hogeh va phit triin frong tuong lai se ggp nhilu kho khan va ttong tinh frang cip bich cin dupe quan tim. Vile quin ly hien frgng va Uieo doi bien dpng nuoi ttong thiiy san se dupe dgt Iln hang dau nhim theo doi dien biln dien tich nuoi thuy san ttong qui khd, hien tgi va du bao frong tuong lai (Tri Quang, 2010). Ben canh do, su phat ttiln mgnh me cdng n ^ l vien tham da va dang dng dyng rat thanh edng trong viec quan ly, danh gii, theo doi va du bao hien trang moi trudng va tai nguyin thiln nhien (VQ Quang Minh, 2010). Tuy nhien, ung dyng viln tham ttong thuy sin chua dupe quan tam nhieu mac dii lihh vuc thuy sin la mgt ttong cic nginh kinh te miii nhgn ttong nude va nuoi ttdng thiiy sin li mpt ttong eae van dl giy 5 nhiim tryc tilp vio moi trudng nude ma eae nhi quin ly mdi trudng dang bdc xuc vl van dl nay (Nguyen Thi Xuin An, 2011). De tai thuc hien nham mue dieh theo ddi su thay doi hien ttgng va xiy dung bin do phan bd khong gian nuoi ttong thdy sin td 2008 din 2012 dpe theo tuyen sdng H|u thugc tinh An Giang, tu do ho ttg cho cae nhi quan ly thiiy sin va moi tnrdng quan tim diing muc ve thue ttang cung nhu dinh hudng phat triln ciia nginh nghi nay frong hien tgi va tucmg Iai.

2 KHU VV'C NGHIEN CUtJ

An Giang li mdt tinh thugc Dong bang song Cuu Long, vT dd dia 1^ tu 10''I0'30" - 10°37'50" vi Bic va tit 104047"20"'- 105035'10" kinh dp DSng.

An Giang la tinh cd vi tri dia ly dae bilt la tinh diu nguin eua song Mekong chiy vao dja phin Vilt Nam vi chia thinh hai nhinh song ldn la Sdng Tiln vi Sdng Hgu trai dpc theo chilu dai ciia tir^. Ngoai cae song ldn. An Giang con co mgt hi thing rgch tu nhiin rii ric khip dia ban ciia tinh, do cd hi thing song ehinh vi kinh rach ching chit nin tilm ning phat ttiln nganh thiiy sin cua tinh dupe die biet chii frong va phit triln da co tir lau ddi, die biet mdi trudng nude tten 2 nhanh sdng chinh thudc song Tiin vi song Hgu frIn dia ban tinh An Giang rat phu hpp cho vile nuoi thiiy san nude nggt die bi?t la ca da fran nhu ca tra va ca basa. Khu vyc nghien ciiu dpc theo tuyin song Hgu (vimg mau do) tten dia bin tinh An Giang (Hinh 1).

Hinh 1; Khu vuc nghien cuu 3 PHUONG PHAP

3.1 Dii lieu anh

Bk tai thuc Men su dung inh LANDSAT dd phin giii 30x30m cac nam 2008, 2010 va 2012 thupc dia phgn tinh An Giang, moi 2 nim sd dyng mgt inh bao phd khu vue nghien cuu.

3.2 Xdl^ dir lilu Budc 1: Xoa sge tten anh

Do anh LANDSAT til' nim 2003 bi 16i khi chup inh, xuit hien nhung spe den ttIn anh Iam giim thong tinttin inh gay kho khan cho qua ttinh xd 1^' inh vi the trude khi phan loai cin tiln hinh xda soc de bo sung thdng tin tren mdi inh cin phan loai. Sir dyng phan mim Gapfilling ^k hi trg bl sung thdng tin phan bj spe tten inh.

Budc 2: Ghep inh va eit anh

Ghep dnh- ghep cic inh cd cimg thdi dilm chup anh dl cd dugc 1 tim inh bao phii toin bg khu vuc tinh An Giang.

Cat dnh: cit khu vyc nudi thuy san tip trung chu yeu d hai bin bd song Hiu vi ttIn cac cin dgc song Hiu de ting dp chinh xac cho qua trinh phin loai sau niy.

Budc 3: Phan tich thanh phin dpe lap (ICA:

Independent Component Analysis) va tao anh chi so thinh phin doe lip (IC)

Phan tich thinh phin dpc lap ICA (Independent Component Analysis) la mdt ky thuat tinh toan va

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Tap chi Khoa hgc Tnrang Dgi hgc Cdn Tha Phdn .4: Khoa hgc Tir nhien, Cong nghe vd Mdi tnr&ng- 30 (2014): 78-83 thong ke de phit hien nhiJng thua s l tilm an tin tai

ngiu nhien dudi nhimg t^p hgp biln hay phep do hay tm hieu. Phuong phip ICA la phuang phap taeh nguon mii BSS (Blind Source Separation),

"i^uon" d day cd nghia li tin hieu ban diu nhu mpt thinh phan d^c lap, "mii"' cd nghia la biet rat it hoac khong bilt ^ vl ma ttin ttgn. lan. ICA la mot phuong phap dugc sd dung rpng rSi nhat eho viec tich ngudn mii.

Khi xet hai biln ngau nhien sl va s2, vi co bin eac bien sl va s2 li d^c lap thing kl niu thong tin vl gia tri eiia sl khdng dua ra bat ky thong tin ve gia tri eua s2 va nguge Igi.

sl va s2 dugc coi li doe lgp khi va chi khi p (sl,s2) = pl(Sl)p2(s2).

Gia tti ciia ICA dugc biiu thj bdi p (sl, s2) ham mat dp xac suit ehung eiia sl vi s2. Him mat dp xac suat ehung eua sl va s2 dugc bieu thi bdi pl(Sl) la him mgt dp xac suit eua Sl, vap2(s2) la him mat dd xac suit cua s2.

Budc 4: Phin logi ddi tugng

Trong phin loai khong kiem dinh, de tai su dyng phuang phip ghep nhom khong phin cip (ISODATA) la m$t fron^ nhiing thuit toin lap tii iru CO bin tilu bilu nhit. Phuong phap nay vira mang die tinh ciia phan logi phi kiem dinh vira mang die tinh eua phin logi kilm dinh. Trong ghep nhdm khdng phin cap, cic nhom ddi tupng dua tten quy lugt phin bd va tan sd xuit hien cua cic gia tti dilm inh, dau tien sd nhdm dugc in dinh tam tiidi, sau do eac diem inh (pixel) dupe ghep sao cho khi ning phin cich giiia cac nhdm li cao nhit, tinh toan ttgng tim cae nhdm vi dilu chinh sl lugng eac nhom. Qua ttinh nay dugc lap vdng eho din khi s l lupng eac nhdm frd nen on dinh.

3.3 Dinh gii d$ tin c$y

Xic dinh dO chinh xac phin logi dua tten thu^t

toan ma ttan sai so de tinh toin dg chinh xac toan eye va mdc do phan loai nham doi vdi timg loai hiin trang (ty le % sai sd thyc hiin vi bd sdt). Dp chinh xie toin cue eda thuit toan phin loai (T) dugc tinh theo % nhu sau:

Trong do: Oij la gii fri thi hiin su phu hgp d hang i va egt j cua ma frin K*K

n pixel duge phan thanh K logi

Chi so Kappa (K) dupe xac djnh de kiem tta khi hai bp dii" lieu eo dp tin cay khae nhau vl thong ke va djmh gia su phii hgp giiia nhiing nguin dir lieu khae nhau hogc khi ip dung cic thuat toin khic nhau. Cich xic dinh cht so Kappa (K) nhu sau:

.(T-E)

K =

( l - £ )

Trong do: T: do chinh xac toan cyc cho bdi ma ttan sai sd.

E: dai lugng thi hien sy ky vpng trong phin logi cd thi du doin trudc.

4 KET QUA THV"C H I | : N 4.1 Ghep va cat anh

Toin bp tinh An Giang dupe bao phu tten 3 tim inh. Vile ghep inh dugc tien hanh tu 3 tam inh nay lgi vdi nhau dl cd dugc 1 tim inh che phu toin idiu vuc nghiin cuu. (Hinh 2a). Khu vuc nudi thuy sin phan bo chu yeu dpe theo song Hiu eua tinh An Giang do do inh dugc cit dgc cac viing dpe theo sdng Hiu dl tich riing khu vue nuoi thuy sin (Hinh 2b) de khi phan loai se khong hi anh hudng den cic doi tugng khic phin bl ttIn khu vue tinh An Giang.

a. Khu vuc tinh An Giang b. Anh eat khu vuc phin bl nudi thuy sin Hlnh 2: a) Phin b i tinh An Giang tren anh LANDSAT, b) Viing phan bo nuoi thiiy san

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Tap chi Khoa hgc Tnr&ng Dgi hoc Cdn Tlia 4.2 T90 anh chi sl IC

Phan tich thanh phin dgc lap (ICA) li su phan tich cac thinh phin mang tinh doe lip, trong nghien edu niy ehi phan tich dpc lip eie doi tupng lien quan din nude tten inh- eae ddi tupng nay se dupe taeh rieng thanh cic nhdm thupc tinh rieng bi?t nhu nude, nudi thuy san hay eac ddi tupng khic, viec phin tieh niy nhim mye dich lim noi rd thupc tinh eac dii Wgng ed lien quan den nude nhim thuin tien hon eho qua ttinh phin logi.

^^^

': Khoa hgc Ttr nhien. Cdng ngl^ vd Mdi tnrdng: 30 (2014): 78-83 Qua trinh phin tieh thinh phin dOc lap dupe thue hien ttIn tung bing inh, kit qui dat dugc li bg inh chi sl IC vdi su tieh bilt v l thugc tinh ^tta , cie nhom dii tugng. Ddi vdi di tii tien hinh phia loai ttIn 6 bing anh LANDSAT (ttd bSng hong ngoai nhiet) dk xay dimg 6 bing IC. Sau do Iyc ehgn cae bang IC nio chda nhilu thong tin ttIn anh, dii vdi nghiin cdu nay 3 bang IC gom ICI, IC2, IC3 dugc chpn va sd dung phin logi vi eae bang nay chiia nhieu thdng tin frIn inh (Hinh 3).

4.3 Phan lo^i khong kiem dinh (ISODATA) Anh sau khi tgo ehi s l IC, tiln hanh phin logi inh theo phuong phip ISODATA dugc chia thinh 13 cip do (Hinh 4a). Sau do t l hpp thinh 3 nhom dii tugng gim: dii tugng thdy sin, sdng va cac doi tuong khic (gim lua, hoa mau, ciy an ttai, nha d...) tir nam 2008 din nim 2012 (Hinh 4b). Kit qui inh sau khi ghep hiin thi 1 dii tugng duy nhit la thuy sin (Hinh 4c).

Hinb 3: Anh t^o chi so IC

••%'

(a) Sau ph3n loai ISODATA (b) Gom nhom sau phan loai (c) Phan bo hien trang thuy sin Hinh 4: Anh sau phin loai kbdng kiem dinh vi phan bo hifn trang thiiy san khu vuc nghiin cuu 4.4 0$ chinh xac phan loai

DO chinh xac phin loai dugc tinh toin dya tten 30 diem khio sit thyc tl dugc phin bl ngau nhien ttIn khu vyc nudi thuy san (Hinh 5) dl xic djnh dg tin ciy ttong phin logi bing cich do ludng dO chinh xic gida mpt di^ lieu chuan ngoii thye tl vdi dti lieu anh dugc phin logi. Kit qua tinh toin dp ehinh \ac toin eye phan loai hien trgng vao nim 2008 li 70%, nain 2010 li 83.33% va nim 2012 li 76,67% vdi he sd Kappa thi hien sai so trong qua frinh phin logi lan lugt la 0.4, 0.7 vi 0.53. Kit qua tinh loan dp chinh xic phin logi va dp tin egy cho thiy kil qua phan logi vao nim 2010 vi nim 2012

cao hem so voi nam 2008. Hinh 5: Vi tri phan b6 cac dilm lihao sit 81

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Tgp chi Khoa hgc Tnr&ng Dai hgc Cdn Tha 4.5 Hoan chinh ban do hien trang nuoi trong thuy san

Ban do hiin ttang nudi ttlng thiiy san dugc thue hiin va hoan chinh ttIn Mapinfo bao gdm cac ldp ban do nhu ranh gidi song, ranh gidi huyen, ranh gidi tmh va ten cac don vi hinh chinh cip huyen. Bin d l hien ttang duge thinh lip vdi ti 11 ban d l la 1: 100.000. Nam 2008 diln tt'ch nudi ttong thuy san phin bo chu yeu d vung thupng lim song Hiu, chu ylu thupc 2 huyin la Chiu Phu va

Phdn A- Khoa hoc Tu nhien. Cong nghe vd Moi tnr&ng 30(2014): 78-83 An Phii, dong thdi phan bo rai rac dgc theo tuyin song thugc eae huyen Chau Thanh va Chg Mdi (Hinh 6a). Nam 2010, dien tich thiiy sin tang so vdi nam 2008, dien tieh nudi tang khu vuc ha nguon thupc 2 huyen Chau Thanh va Chg Mdi (Hinh 6b). Den nam 2012, diln tich nuoi thuy san giim so vdi nam 2010, hien ttang nuoi thay doi it va giam d khu vue 2 huyen Chau Thanh vi Chg mdi vdi mat dp nuoi thua hon nam 2010 CHinh 6c).

(a) Hien trang thuy san nam (b) Hien trang thuy san nam (c) Hien trang thuy san nam

2008 2010 2012 Hinh 6: Ban do phan bo hiin trang thuy san khu vuc nghiin ciru nam 2008, 2010 va 2012

4.6 So sanh dien tich phan loai va diln tich thurc te

So lieu dien tich nuoi thiiy sin timg nam tu 2008 den 2012 ttinh biy ttIn Hinh 6 va so lieu dien tich thuc t l (dua ttIn cic bao eao thong ke thuy sin thudng nien ciia tinh An Giang tu nim 2008 den 2012). Dien tich nudi thiiy sin tang tir nam 2008 din 2010 td 1.936,86 ha din 2.172,78 ha din nam 2012 thi dien tich thuy sin bat dau giam 2.038,32 ha (Hinh 7). Lgi nhugn mang lgi tir nghi nuoi thiiy sin ddi vdi tinh An Giang li rit ldn nen dien tieh ting tu 2008 din 2010; tuy nhien, din nam 2012 diln tich nuoi lgi giim do su anh hudng ciia vu kiln chdng ban phi gia ca fra, ci basa tu 2001 den 2003 (Minh Hiin, 2013) vi ap tiiul nhap khiu tu 36,84% - 63,88% eho sin phin ea tta, ea basa vio thi ttudng My tu nam 2003 (Dl Tuyet Khanh, 2004). Theo Tap ehi Thuy Sin (2013), trong vong 8 nam tir 2000 - 2008, kim ngach xuit khiu ca tra cua Viet Nam ting 460 lan, sin lupng ting 830 Ian vi frong han 10 nam qua, gia xuat khau binh quan liln tyc giam, gia xuat khiu trung binh cua mot ky

ea d nam 2010 chi con 70% so nam 2003 va 60%

so nam 2000.

Sd lieu dien tfch phin logi vi s6 lilu diln tich thuc tl cd su khae biet c6 the la do sd dung anh LANDSAT dp phan giai anh 30 m, de danh gia muc do chinh xac khi phin logi v i so lieu thuc tl CO the su dung' inh co do phan giai cao hon de so sanh dien tich phan loai.

B Dien lie

Hinh 7: Bieu d l so sanh diln fr'ch phan loai va dien tich nudi thiiy san thuc te

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Tap chi Khoa hgc Tnr&ng Dgi hgc Cdn Tha 5 KET LUAN

Phdn A: Klioa hoc Tir nhien. Cong nghe vd Mdi trudng- 30 (2014): 78-83

Be tat dng dung ky diuit vien tham di xiy dyng cic bin do hien trang nuoi ttdng thiiy san tu nam 2008 den 2012 va theo doi tinh hinh biln dpng diln tich nudi thiiy sin theo thdi gian va khong gian. Kit qui dat dugc cho thiy tinh ung dung cao cua viln thim ttong quan ly nudi ttlng thuy sin nhim ho ttg cic nhi quin l;f theo ddi dugc tinh hinh biln dgng nuoi thuy san qua cic nam. Tuy nhiin, cd the sd dung cic loai inh vien tham khie CO dp phin giii cao hem de so sanh do tin cay va dinh gii dg ehinh xac khi phin loai hien frgng nuoi thuy san vdi sl lieu thuc te.

TAI LI?U THAM KHAO

1. Ban Chi dgo Tay Nam Bp va Trung tam diong tin Sai Gon. 2005. Tiy Nam Bd tiln vio the ky 21, NXB. Chinh trj Quic gia, HaNgi.

2. Do Tuylt Khanh. 2004. Tim hiiu luit vi chinh sach chong bin phi gia (anti- dumping) ciia MJ [I]. Thdi dgi mdi. Tap ehi Nghiin ciiu & Thao luin. Sl 1 - thing 3/2004.

3. GTZ. 2009. Chuoi gii tti ca tta tai An Giang. GTZ-MPI Small and Medium Enterprise Development Program in Vietnam.

4. Ll van Tmng. 2005. Viln thim. NXB dgi hge Quie Gia, TP Hi Chi Mmh.

5. Minh Hien. 2013 An Giang: Hudng di nio cho nghi nuoi vi xuit khiu ci tta. Tgp chi Thiiy sin 25/07/2013.

http ://thuy sanvietnam.com .vn/an-giang- huong-di-nao-cho-nghe-nuoi-va-xuat-khau- c a-tta-articIe-53 75 .tsvn.

6. Nguyin Ngpc Thgeh. 2005. Giao ttinh co sd viln thim. Dgi hpc Qude gia Ha Ngi.

7. Nguyin Ngpc Thach. 1997. Bai giaig gidi thilu cie kien thdc co sd ve vien thim, Khoa Dia chat, Trudng Dgi hpc Khoa hpe Tu nhien. Hi Npi.

8. NguylnThiXuin An. 2011. Nuoi trlng, khai thic thuy hii sin. Viln Kinh te va Quy hogeh Thuy sin, 12/12/2011.

http://www.peworld.com.vn/artieIes/quan-

!y/ehuyen-mue/2004/01/1185714/gis-va- quy-hoach-nuoi-frong-thuy-san/

9. Phgm Vpng Thinh. 2000. Trie dia inh.

NXB Giao thong vin tii, Ha Npi.

10. Tri Quang. 2010. Ci fra xuat khiu - cin c6 cii nhin tong quan dl phit friln. Cing thong tin di?n tu Bp Nong nghiep & PTNT.

http://www.agroviet.gov.vn/Pages/newsdeta il. aspx?NewsId=10831&Page=4.

11. Sd Cdng Thuang An Giang. 2013. Bio cio kim ngach xuit khiu dinh ki quy 1 nam 2013 12. Vd Quang Mmh. 2010. Giao frinh ky thugt

viln thim. Tnrdng Dai hgc c i n Tha.