Tap chi Khoa hoc TrirmgBai hoc Ch Tha Phm A • Khoa hoc Tv nhien, Cong nghf va U6i ini&ng 26 (2013) 35 43 * < • Tap chi Khoa hoc Tru''''dng Dai hpc Can Thd website sj ctu edu vn [, BANH GIA TINH HINH SAT[.]
Tap chi Khoa hoc TrirmgBai hoc Ch Tha Phm A • Khoa hoc Tv nhien, Cong nghf va U6i ini&ng 26 (2013): 35 *, boi lu, sat Id, Cd Mau, highest in Tan Thuan, Tan Tien ward Dam Doi district while accretion Bge Lieu process occurred highest from Cai Huong canal, Ngoc Hien district to Bay Hap estuary Nam Can district In the Western ofCa Mau, accretion process is over predominated while erosion is over predominated in the Keywords: East sea ofCa Mau and Bac Lieu The information is to support the local Remote sensing, GIS, government in assessing monitoring and making plan for land use shoreline, accretion, erosion, planning in this region Ca Mau, Bac Lieu TOM TAT Riit tiich duang ba la mfl cong viec cdn thiit cho gidm sdt mdi trudng vd danh gid tha,: doi dudng bd Cd Mau vd Bac Lieu, hai tinh phia nam ciia Viet Nam qudti-inhsal Id va bdi tu diln hiin mot cdch nghiem ti-ong Bi lai da xdy dung duac bdn dudng bd nam 1995, 2000, 2005 vd 2010 Ket qua cho thdy tinh hinh sgi la va bdi lu ven bd biin Cd Mau va Bac Lieuti,nam 1995 den 2010 diin biin vd cioigphuc tap Qua tiinh sat'ld va bm tu luon dan xen vdi Irong timg thdi ky Khu vuc sal Id nhiiu nhatxay ImxS Tdn Thugn Tdn Tien huyen Bdm Dai va khu vuc bdi ti, nhieu nliat dien rati, R^ch Cai Huang huyen Nggc Hiin keo dai ldi cita Bay Hap huyen Nam Cdn Nliin chung cho din giai doan hien ba bien Tay Imh Ca Mau xu hudng bdi tu chiim uu thi han, bd biin Dong cua tinh Cd Mau vaBgc Lieu thi xu hudng sal Id lgi chiim uu thi Bdy a mQl nhmig thong tin huu ich giup cdc ca quan chuc ndng cua chmh quyen dia phuang cdng tdc quy hogch vd qudn lyvimg Tgp ehi Khoa hoc Tnrang Dgi hgc Cdn Tha Phdn A: Khoa hgc Ty nhien, Cong nghe va Moi Iruang: 26 (2013): 35-43 DATVANDE Dirong bcf dugc dinh nghta la dirdng bien giua dit va nude (Alesheikh et at., 2006), no la m6t nhiing dac tnmg quan trgng tren bd mat trai ddt Winarso et a/., 2001) Vide kham pha va ludng sg thay ddi dudng bd la mdt cdng viec quan trgng cong tac quan ly va theo ddi vun^ bd ven bidn (Zhao et al, 2007), bao gdm nhieu vdn dd quan trgng nhu bao vd va md rdng dudng bd, bao vd ngudn tai nguyen bidn hay dg doan mirc tdn thuong (Nayak, 2005) Mac dta dinh nghia don gian nhung dgng luc tu nhidn cua dudng bd ri\ khd dd theo doi, giam sat Tir 1972, anh ve tinh Landsat va cac anh vd tinh khac chyp khoang budc sdng hdng ngoai, vung dk va nude tach bidt ro khoang budc sdng Vidn tham va ky thuat xtr ly anh dem lai giai phap thay thd giup giai quydt cac \in dd trudc day (Winarsoet et al, 2001) Ngay nay, vdi su tich hgp cua cdng nghd vidn tham va GIS, viec theo ddi \k tinh toan cac bien dgng dtrdng bd dugc thuc hien kha nhanh chdng va hieu qua Trudc dSy, vide danh gia dirdng bd dugc thuc hien bang phuoTtg ph^p thyc dia thdng qua vide si!r dung cac cdng cy va thidt bi truydn thdng nhidn hidn chung ta cd thd thuc hidn ve dudng bd bing cac thidt bi hien dai nhu he thdng dinh vi loan cau hoac he thdng may quay va ngudn thdng tin tir anh ve tinh Ngudn du lieu tu anh vd tinh se dugc dua vao he thdng thdng tin dia ly (GIS) dd xu ly, phan tfch va danh gia didn bien dudng bd mgt each ban tu ddng (Claire, 2012) Nghien cuu xac dinh quy md, xu hudng bidn ddng dudng bd nham cung cap thdng tin huu fch phyc vu cong tac dinh hudng quy hoach, khai thac hgp Iy cac vung cua sdng, ven bidn, day la mdt nhiem vu cd y nghTa ca ve khoa hgc ciing nhu thuc tidn PHlTONG PHAP NGHIEN ClTU 2.1 Dir lieu anh Anh vien tham sir dung nghidn cuu gom anh Landsat va AIos Anh Landsat dugc cung cap bdi U.S Geological Survey (USGS) tai mien phi tai website www.global.usgs.gov ciia trung ^m NASA (Hoa Ky) Anh AIos dugc cung cap bdi Jaxa Earth Observation Research Center Anh vd tinh AIos (bd cam AVNIR-2) chup d kenh: kenh (0.42 - 0.5 pm), kdnh (0.52 - 0.6 pm), kdnh (0.61 - 0.69 pm) va kdnh (0.76 0.89 pm) Anh Landsat thu dugc sau nam 2003 phan ldn hi soc Idi he thong (Scan Line Corrector), bg phan didu chinh hudng bay va tang hieu qua quan sat trai dSt Bang 1: Thdng tin anh vien tham dS thu thap STT Thod gian I 10 11 07/01/1995 13/05/1995 04/03/2000 03/05/2000 05/04/2004 01/07/2005 I2/11/2005 09/01/2006 19/03/2010 06/01/2011 06/06/2011 Lo^i do- li£u Anh Landsat TM Anh Landsat TM Anh Landsat ETM Anh Landsat ETM Anh Landsat ETM Anh Landsat ETM AnhLyidsatETM Anh Landsat ETM Anh AIos Anh AIos Anh AIos 2.2 Cac birdc thu-c hien - Sira loi anh Landsat bi sgc: Do anh Landsat thu vao nam 2005, 2006 hi sgc nen qua trinh so hda dudng bd cd nhidu doan Binh dang Raster Raster Raster Raster Raster Raster Raster Raster Raster Raster Raster Bo phan giai 30m X 30m 30m X 30m 30m X 30m 30m X 30m 30m X 30m 30m X 30m 30m X 30m 30m X 30m lOmxIOm 10m X 10m lOmxIOm Bispc (Co/Khdng) Soc Soc Soc - khong cd thdng tin dii lieu De khac phuc tinh trang dk tai sd dyng cdng cu didn sgc (Gapfill) chay trdn ndn phSn mdm ArcGIS de cd dugc mgt tam anh cd day du thong tin (Tran Thi Van, 2008) Tap ehi Khoa hoc TruangDgi hoc Cdn Tha Phdn A Khoa hoc Tu nhien Cong nghe vaMSi inmng: 26 (2013): 35-43 ' Dang ky anh: Thao tac dang ky anh nhim dd hidu chinh anh hi sai lech vd toa dp qua trinh chup Anh Landsat 1990, 2000, 2005 va AIos 2010 dugc dang ky dua vao toa dp c^c didm khdng chd thu thap tir ban chu^n Viing cua ludi chidu ia UTM mui 48, he tpa WGS84 Sai sd toan cue cua anh da dang ky phai nhd hon mot mdi dugc chpn, ndu sai so ldn hon mot se tien hanh chpn lai cac didm khong chd ddn dat dugc yeu cau (Trin Thi Van, 2008) - Ghep anh: Viing nghien cuu dugc ve tinh Landsat va AIos chup trdn tim anh khac ndn phai tidn hanh ghep hai tam anh lai mot tim trudc tien hanh cac thao tac xir 1;^ dinh Anh dugc ghep dua vao cong cu ghep (Mosaic) trdn phin mem Envi (Nguyen Nggc Thach, 1997) Tang cirdng chat lugng anh: Tang cudng anh la bidn ddi anh gdc anh mdi nham the hien anh ro rang ban hay t^o didm n h ^ ddi vdi cac doi tugng can quan tam Anh sau tSng cudng se giup cho cong tac giii doan bang mat hoac xii Iy bang may hidu qui va chinh xic hon Cac kdnh anh vd tinh thu dugc thuc te thudng cd gia tri phin tu' inh phan bd pham vi hep so vdi kha ning hidn thi ciia inh (ndu inh bit cd kha ning thd hidn d^n 256 gia tri), timg kdnh inh hien thi co xu hudng tuong ddi t6i hoac tuong ddi sang Do dd, tang dp tuong phin cho anh dugc thyc hidn bing each keo gian gia tri cda inh (Nguydn Nggc Thach, 1997) - TSng cudng dd tuong phan la mgt thao tic lam ndi bit hinh anh cho ngudi giai doan de dgc, dd nhan bidt ngi dung trdn anh hon so vdi anh goc Tiiy theo timg dng dung cu the, tirng loai anh vd tinh, dac di^m timg kdnh anh ma ngudi giii doan didu chinh dp sang va mdc dp tuang phan cho thich hgp - So hda: Tien hanh sd hda dudng bd cua tinh Ca Mau va Bac Lieu sau chdng lap cic ban dudng bd cua linh Ca Mau va Bac Lidu qua cac nam 1995 2000, 2005, 2010 dd budc diu tim khu vuc bdi tu hay sat Id ven bidn viing nghidn cuu De qui trinh s6 hda dugc chfnh xic de tai da thuc hidn phuong phap ban ty ddng (Claire, 2012), dudng bd dugc Iam noi bat thdng qua chi sd NDWI theo cdng thuc nhu sau: NDWI = (Kdnh • Kdnhi 5)/(Kenh Kenh 5) NDWI cho phep taeh bidt hai ddi tugng dit va nude (Claire, 2012) Sau sir dung phuong phap chia anh t^ so dugc sd dung dd lam ndi bat dudng bd theo cong thdc sau: Dudng bd = ((Kdnh 2/Kdrih 4) x (Kenh • 2/Kenh 5)) + NDWI Trong do: Kenh cd budc song 0,52 0,6 (^im) Kdnh cd budc sdng 0,76 - 0,90 (pm) Kenh c6 budc sdng 1,55 -1,75 (pm) Sau thyc hien cac phuang phip lam ndi bit dudng bd, dii lieu dugc chuydn sang phan mdm ARCGIS dh sd hda ban ty ddng v i hoin chinh ban dd dudng bd - Cdng tac di thuc dia: + Chuin bi phidu didu tra va phong vin ngudi dan, can bp tai khu vuc khao sat vd tinh hinh sat Id va bdi tu + Chuin bi ban dd lam tu lieu di thyc dia, tren ban phii xic dinh trudc khu vyc sat Id va bdi tu ven bidn hai tinh Ca Mau v i Bac Lieu Khoanh vung nhdng noi dien hinh cd van de ve sat Id va bdi tu ciia hai tinh Qui trinh thuc dia tham khao y kidn cua cac cin bp phu trich, quin I^ van de sat Id va bdi tu tai cac viing ven bidn tinh C i Mau va Bac Lidu thupc chi cue thuy Igi tinh Ca Mau va Bac Lieu + Sau thyc dia, tidn hanh so sanh ket qua giai doin, tidn hinh chgn khu vyc didn hinh cho vin de sat Id va bdi tu cua tirng tinh, di thyc Id liy tpa dd diem, ph6ng van, chup anh va ghi nhan I^i hidn trang sat Id v i bdi tu tai cac khu vyc didn hinh dugc chpn Hoan chmh ket qui, vidt bao dinh gia cio KET QUA VA THAO LUAN 3.1 Tong quan tinh hinh sgt Id v^ hhi tg Dudng bd bidn Dong va bidn Tay hai tinh Ca Mau v i Bac Lidu dai khoing 300 km, cd Tap chi Khoa hoc Tnrdng Dgi hoc Can Tha Phdn A: Khoa hgc Tu nhien Cong nghe vd Moi Iruang: 26 (2013): 35-13 hinh dang gi6ng cha V (Hinh 1), rieng tinh Ca Mau CO hai mat tilp giap biln Trong qua trinh chong lap ban d6 cho thiy diln biln duong bo xSy ta ba qua trinh: b6i tu, sat Id va sat lo/boi ty xen ke cua Nha IVIat, phuang Nha Mat din Vinh Tiach Dong (Hinh 1) - Hai khu vuc sat la xen ke vol bfii tu: khu vuc xa Nguyen Viet Khai (huyen Phii Tan); khu vuc Mui Ca Mau (huyen Ngoc Hiln) (Hinh 1) Kbu virc sat lit diln hinh la: khu vuc ciJa S6ng D6c (huyen Ttln Van Thai); khu virc xa Tan Thuan, Tan Tiln (huyen Dim Doi); khu virc cira Ganh Hao (huyen Gia Rai); khu vuc - Khu vyc b6i ty dien hinh: khu vyc tir cira Bay Hap (huyen Nam Can) keo dai tai Rach cai Huang (huyen Ngpc Hiln) (Hinh 1) Ba n d o h i ^ i i r a n g sat l o va b m EU ven bi^n tinh Ca Ixla.y.^ Bac Lieu n a m 1995-2(>l!D /fe^Vai'Hiiiin r|~t:-teah- Hinh 1: Khoanh vung khu virc sat Iff, boi tu dign hinh tinh Ca Mau, B?c Lieu ti^ 1995-2010 -^ niAi [ -' •- _ „ " t ^ LA.MAL^ ^At'ViaJian '•- > _r EhnTfa J^-jlft xC/^ • \^ -' ^ J J- '•Tboij^ib { V* y X ' Dam Doi' J -y' > f ' ^ " ^ ''y^'^ ^ i " *iB^^i»ff^|[^/ i'^t^^^ j^5i=^-'''''^ | ., , 3.2 Dien bi^n tinh hinh sat Id va bdi tu qua tirng giai doan 3.2.1 Khu vuc cua Song Boc, xd Khdnh Hdi, huyin Trdn Van Thai Khu vyc cua Sdng Ddc, xa Khinh Hii, huyen Tran Van Thdi tinh hinh sat Id va bdi tu ^ ^HoaBmh ^ -» - "T ^ ^8 ) VnbLcn ' ' S ^ ^ i j p ^ J-" B AC L I E L , , ' ' ' ' ' ^ ^/ : i '» ' -k^' ^oopBj "^ ^ > " a 4r — TIU Sd L'K^Dha}-^ Tty SO UBND Tnh Du^dg gBO dtfing ^"Satlo ^BSiiv CZi Khu-niclRJiEii \ 'li L Khu -vvc ^ i la dan xen cu the nhu sau: giai doan 1995 2000 dien tich sat Id la 186 va didn tfch boi tu la 128 ha; giai doan 2000-2005 didn tich sat I d i a 31 va dien tich bdi tu la 10 ha; giai doan 2005 - 2010 didn tich sat Id li 49 va dien tich b6i tti la 13 (Hinh 2) Hinh 2: Hinh minh hpa qua trinh s?t Id v^ bdi tu khu virc ven biln cira Song Ddc, xa Khdnh Hai, huydn Tran Van Thdi Tgp ehi Khoa hoe Truong Dgi hoc Cdn Tha Phdn A: Khoa hgc Ty nhien, Cong ngh$ ^>a Moi Iruang: 26 (2013): 35-43 * I Mdt nhdng nguyen nhan gay sat Id la rdng phdng ho bi tan pha nghiem cung vdi tac ddng sdng bidn, ddng chay, thi cong dao bdi bd kdnh khdng dung quy Irinh ky thuat, cac phuang tien giao tbdng thuy cMy vdi cong suit ldn Mac dii gim doan tu 2005 den 2010 cdng tic bio ve, trdng va lam ke tam rimg tai khu vyc dugc chu nhung nhin chung mdc sat Id van cao hon muc bdi tu (Theo Sd Ndng nghidp & PTNN, 2012) a Nam 1995-2000 3.2.2 Khu vuc xd Nguyin Viet Khdi huyen Phii Tdn Khu vuc ven bidn xS Nguyin Viet Khai, huyen Phu Tan tinh hinh sat Id va bdi tu dan xen cu thd: Giai doan 1995 - 2000 didn tich sat Id la 278 va didn tich bdi ta la 16 ha; Giai doan 2000 - 2005 didn tich sat Id.Ia 77 va dien tich bdi tu la 55 ha; Giai doan 2005 - 2010 dien tich sat Id la 85 va didn tich bdi tu la 27 (Hinh 3) Nam 2005-2010 Hinb 3: Hinh minh boa qud trinb s^t Id va bdi tu khu vyc ven bidn xa Nguyen Vift Khii, huyen Phii Tan Qui trinh sat Id va boi tu xen ke vdi nhau, giai doan 1995 - 2000 qua trinh sat Id la chu y^u, giai doan 2000 - 2005 qua trinh sat Id xen ke vdi boi ty, giai doan 2005 - 2010 qua trinh sat Id chiem uu thd Muc dp sat id trung binh moi nam tai khu vuc td m ddn m Mot nhung nguyen nhan sat Id la khu vuc niy chju anh hudng tuong ddi it cua gid miia Tay Nam cd dia hinh dan trai theo hudng gid va dudng bd dai ndn ban che dugc tie beii cua sdng va gid Bdn canh dd khu vuc gin cua sdng Bay Hap, cua song rdng ndn dugcphii sa boi dap dd kdt qua pbin tich cho thay khu vurc cd xu hudng bdi tu (Chi cyc Thuy Lgi tinh Ca Mau, 2012) 3.2.3 Khu vuc tir Rgch Cdi Hirang, huyin Ngoc Hiin keo dai tai cua Bdy Hdp, huyin Ndm Cdn Khu vuc tu Rach Cai Huong, huyen Ngpc Hidn keo dai tdi cua Biy Hap, huydn Nam Can tinh hinh b6i tu chidm uu the cu thh nhu sau: Giai doan 1995 - 2000 didn ti'cli sat Id la 320 va dien tfch bdi tu la 991 ha; Giai doan 2000 -2005 dien tfch sat Id la 112 va didn tich bdi tti la 789 ha; Giai doan 2005 - 2010 dien tich sat Id la 139 va dien tfch bdi tu la 425 (Hinh 4) Giai doan 1995 - 2000 tai khu vuc qui trinh sat Id xen ke vdi bdi tu, sang giai doan 2000 - 2005 mdc dd sat Id va boi tu cda khu vuc ddu giam, nhidn sang giai doan 2005 - 2010 xu hudng bdi ty chidm uu thd va tang nhanh Mpt nhung nguydn nhin khu vuc cd nhidu cua sdng Idn Iugng phu sa bdi d^p Idn, them vao dd khu vuc s^t Id Miii Ca Mau theo hudng gid mda Tay Nam dan chuydn vao Iam cho didn tich bdi tu cang tang len (Chi cue Thuy Loi tinh Ca Mau, 2012) Tap ehi Khoa hgc Tnrang Dgi hoc Cdn Tho a- N a m 1995-2000 Phan A: Khoa hge Ty nhien Cong nghi vd Moi Inrang: 26 (2013): 35-43 b X a m 2000-2005