Tap chi Khoa hoc TrirmgBai hoc Ch Tha Phm A • Khoa hoc Tv nhien, Cong nghf va U6i ini&ng 26 (2013): 35-43
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Tap chi Khoa hoc Tru'dng Dai hpc Can Thd
website: sj.ctu.edu.vn [,
BANH GIA TINH HINH SAT L 6 , BOX TU KHU VX/C VEN BIEN T I N H CA MAU VA B^C LBEU Ttr 1995-2010 S C D U N G VIEN THAM VA CONG NGHE GIS Phan Kieu Dilm', Vo Quang Minh', Nguyin Thi Hong Diep' va Diep Van Den'
' Bo mon Tai nguyen ddt dai, Khoa Moi truimg vd Tai nguyen Thien nhien, Trudng Dgi hpe Cdn Tlia Thdng tin chung:
Ngdy nhgn: 24/12/2012 Ngay chdp nhdn: 19/06/2013 TUle:
Monitoring the shoreline change in coastal area ofCa Mau and Bac Lieu province from 1995 to 2010 by using remote sensing and GTS TIrklida:
Vien thdm, he thong thong dn dia l}>, boi lu, sat Id, Cd Mau, Bge Lieu
Keywords:
Remote sensing, GIS, shoreline, accretion, erosion, Ca Mau, Bac Lieu
ABSTRACT
Extraction of the coastline is an essential task of environment monitoring and change detection in coastal area. Ca Mau, Bac Lieu the southern most province of Vietnam, is affected by coastal environmental change and tlie coastline has been subjected to specific modifications over many years. The cause is determined by three factors including erosion, stabilily and sedimentation. The pattern of coastline changes ofCa Mau and Bac Lieu was identified using Landsat TM images acquired in 1995, 2000, 2005 andAlos image acquired in 2010. In this study we proposed a semi-automatic technique to extract the coastline.
The results showed that the changing of shoreline is very complex in this area and the shoreline was tended toward erosion more than accretion in this areas in general In period 1995 to 2010. erosion process, occurred highest in Tan Thuan, Tan Tien ward. Dam Doi district while accretion 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 East sea ofCa Mau and Bac Lieu. The information is to support the local government in assessing monitoring and making plan for land use planning in this region.
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 qud ti-inh sal Id va bdi tu diln hiin mot cdch nghiem ti-ong Bi lai da xdy dung duac bdn do 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 nhau Irong timg thdi ky. Khu vuc sal Id nhiiu nhatxay ra 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 nay 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 trong nhmig thong tin huu ich giup cdc ca quan chuc ndng cua chmh quyen dia phuang trong 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
1 DATVANDE
Dirong bcf dugc dinh nghta la dirdng bien giua dit va nude (Alesheikh et at., 2006), no la m6t trong nhiing dac tnmg quan trgng tren bd mat trai ddt Winarso et a/., 2001). Vide kham pha va do ludng sg thay ddi dudng bd la mdt cdng viec quan trgng trong 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 do 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 trong khoang budc sdng hdng ngoai, vung dk va nude tach bidt ro trong khoang budc sdng nay.
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 tuy nhidn hidn nay chung ta cd thd thuc hidn do ve dudng bd bing cac thidt bi hien dai nhu he Bang 1: Thdng tin anh vien tham dS thu thap
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.
2 PHlTONG PHAP NGHIEN ClTU 2.1 Dir lieu anh
Anh vien tham sir dung trong nghidn cuu nay 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 4 kenh:
kenh 1 (0.42 - 0.5 pm), kdnh 2 (0.52 - 0.6 pm), kdnh 3 (0.61 - 0.69 pm) va kdnh 4 (0.76 - 0.89 pm).
Anh Landsat thu dugc sau nam 2003 phan ldn hi soc do Idi he thong (Scan Line Corrector), bg phan didu chinh hudng bay va tang hieu qua quan sat trai dSt.
STT I 2 3 4 5 6 7 8 9 10 11
Thod gian 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
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
-
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
khong cd thdng tin dii lieu. De khac phuc tinh trang nay 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).
Kdnhi 5)/(Kenh 4 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 dugc Iam noi bat thdng qua chi sd NDWI theo nhim dd hidu chinh anh hi sai lech vd toa dp cdng thuc nhu sau:
trong 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 do chu^n. Viing cua ludi chidu ia UTM mui 48, he tpa do 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 khi dat dugc yeu cau (Trin Thi Van, 2008).
- Ghep anh: Viing nghien cuu dugc ve tinh Landsat va AIos chup trdn 2 tim anh khac nhau ndn phai tidn hanh ghep hai tam anh lai thanh mot tim trudc khi 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 thanh 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 khi 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 trong thuc te thudng cd gia tri phin tu' inh phan bd trong pham vi hep so vdi kha ning hidn thi ciia inh (ndu inh 8 bit cd kha ning thd hidn d^n 256 gia tri), timg kdnh inh khi 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 sao 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 2 tinh Ca Mau va Bac Lieu sau do chdng lap cic ban do dudng bd cua 2 linh Ca Mau va Bac Lidu qua cac nam 1995. 2000, 2005, 2010 dd budc diu tim ra 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
NDWI = (Kdnh 4 • Kenh 5)
NDWI cho phep taeh bidt hai ddi tugng dit va nude (Claire, 2012). Sau do 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 2 cd budc song 0,52 - 0,6 (^im)
Kdnh 4 cd budc sdng 0,76 - 0,90 (pm) Kenh 5 c6 budc sdng 1,55 -1,75 (pm) Sau khi 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 do phii x i c 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 khi 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 cio dinh gia
3 KET QUA VA T H A O 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 nhau.
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
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).
- 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).
Hinh 1: Khoanh vung khu virc sat Iff, boi tu dign hinh tinh Ca Mau, B?c Lieu ti^ 1995-2010
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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
dan xen nhau cu the nhu sau: giai doan 1995 - 2000 dien tich sat Id la 186 ha va didn tfch boi tu la 128 ha; giai doan 2000-2005 didn tich sat I d i a 31 ha va dien tich bdi tu la 10 ha; giai doan 2005 - 2010 didn tich sat Id l i 49 ha va dien tich b6i tti la 13 ha (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 trong nhdng nguyen nhan gay ra sat Id
la do rdng phdng ho bi tan pha nghiem trong 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 nay dugc chu trong nhung nhin chung mdc do sat Id van cao hon muc do bdi tu (Theo Sd Ndng nghidp & PTNN, 2012)
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 nhau cu thd: Giai doan 1995 - 2000 didn tich sat Id la 278 ha va didn tich bdi ta la 16 ha; Giai doan 2000 - 2005 didn tich sat Id.Ia 77 ha va dien tich bdi tu la 55 ha; Giai doan 2005 - 2010 dien tich sat Id la 85 ha va didn tich bdi tu la 27 ha (Hinh 3).
a. Nam 1995-2000 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 nay td 3 m ddn 7 m. Mot trong nhung nguyen nhan sat Id la do khu vuc niy chju anh hudng tuong ddi it cua gid miia Tay Nam do 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 nay gin cua sdng Bay Hap, cua song nay rdng ndn dugcphii sa boi dap do dd kdt qua pbin tich cho thay khu vurc nay 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 ha va dien tfch bdi tu la 991 ha; Giai doan 2000 -2005 dien tfch sat Id la 112 ha va didn tich bdi tti la 789 ha; Giai doan 2005 - 2010 dien tich sat Id la 139 ha va dien tfch bdi tu la 425 ha (Hinh 4).
Giai doan 1995 - 2000 tai khu vuc nay qui trinh sat Id xen ke vdi bdi tu, sang giai doan 2000 - 2005 mdc dd sat Id va boi tu cda khu vuc nay ddu giam, tuy nhidn sang giai doan 2005 - 2010 xu hudng bdi ty chidm uu thd va tang nhanh. Mpt trong nhung nguydn nhin do khu vuc nay 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 ngay cang tang len (Chi cue Thuy Loi tinh Ca Mau, 2012).
Tap ehi Khoa hgc Tnrang Dgi hoc Cdn Tho Phan A: Khoa hge Ty nhien. Cong nghi vd Moi Inrang: 26 (2013): 35-43
a- N a m 1995-2000 b . X a m 2 0 0 0 - 2 0 0 5 <_. N S m 2 0 0 5 - 2 0 1 0 Hinh 4: Hinh minh h9a qua trinh sat Id va bdi tu khu Rach Cai Huvng tdi cura Bay Hap,
huydn Nam Can 3.2.4 Khu vuc xa Ddt Mui, huyen Ngoc Hien
Ket qua phan tich cho thSy khu vyc xa dat Mui, huydn Nggc Hidn tinh hinh sat Id va bdi ty dien ranhu sau: Giai doan 1995 - 2000 dien
ti'ch sat Id la 15 ha va didn ti'ch bdi tu la 920 ha; Giai doan 2000 - 2005 didn tich sat Id l i 170 ha va didn tich bdi tu la 232 ha; Giai doan 2005 - 2010 didn tich sat Id la 187 ha va didn tich bdi tu la 302 ha (Hinh 5).
a. Nam 1995-2000 b. Nam 2000-2005 c. Nam 2005-2010
Hinh 5: Hinh minb hoa qua trinh s^t Id va bdi tu khu virc sa 0Sf Miii, NgQC Hidn Day la khu vyc cd qua trinh sat Id va bdi tu
khi phdc tap, giai doan 1995 - 2000 day la giai doan sat Id manh, giai doan 2000 - 2005 vua bdi tu xen lan sat Id, giai doan 2005 - 2010 nhin chung cd xu hudng bdi tu. Kdt qui khao sat thyc dia cho thay khu vyc phia Nam Mui Ca Mau cd diu hidu sat Id tu giua nam 2006 cho ddn nay va tdc dd sat Id tang nhanh qua tung nam. Theo Chi cue Thdy Lgi tinh Ca Mau, 2012, mdt frong nhung nguydn nhan chu yeu la do anh hudng td gid mua Tay Nam v i gid mOa Dong B i c boat dpng lidn tuc, khu vuc nay chua cd ke chan sdng thdm vao do tic dgng sdng bidn, tridu cudng, ddng chiy, va thi cdng dao bdi bd kdnh khdng ddng quy trinh k j thuat.
3.2.5 Khu vuc xa Tdn Thudn, xa Tdn Tien Kdt qui chdng lip bin dd khu vuc x i Tan Thuan va Tan Tidn, huyen Dam Doi (Hinh 6) cho thay tinh hinh sat Id va bdi tu didn ra nhu sau: Giai doan 1995 - 2000 didn tich sat Id la 126 ha va didn tfch bdi tu la 15 ha; Giai doan 2000 - 2005 didn tfch sat Id la 182 ha va dien tich bdi tu la 0 ha; Giai doan 2005 - 2010 didn tfch sat Id la 167 ha va dien tfch bdi tu la 2 ha.
Qua cac giai doan nghien cdu 1995 - 2000, 2000 - 2005, 2005 - 2010 tai khu vuc nay hidn trang sat Id la chu yeu. Ket qua di thuc dia cho thay mdc do sat Id tai khu vyc nay trung binh mdi nam td 5 m ddn 10 m.
Tgp chi Khoa hoc Tnrang Dgi hoc Cdn Th • y nhien. Cong nghi iw Moi Irudng: 26 (2013): 35-43
\
a. X 3 m 1995-2000 N a m 2 0 0 0 - 2 0 0 5 c . N S m 2 0 0 5 - 2 0 1 0 HiDh 6: Hinh mint] h^a qua frinh s^t liVva bdi tu khu v i ^ xS Tan ThuSn, xa Tan Tiin 3.2.6 Khu vuc ctra Ganh Hdo, huyen Gid Rai
Qua ket qua phan tich anh cho thay khu vuc cira Ganh Hao, huyen Gia Rai (Hinh 7) qua cac giai doan tinh hinh sat Id va b6i tu diln ra nhu sau; Giai doan 1995 - 2000 dien tich sat 16 la 27 ha va dien tich b6i tu la 12 ha; Giai doan 2000 - 2005 dien tich sat Id la 46 ha va dien
tich b6i tu la 2 ha; Giai doan 2005 - 2010 dien tich sat 16 la 43 ha va dien tich boi tu la 11 ha.
Giai doan tir 1995 - 2000 khu vuc nay sat la nhanh, sang giai doan tir 2000 - 2005 tmh hinh sat la giam dang k€, tuy nhien giai doan 2005 - 2010 mirc dp sat Icr tang nhanh.
a. N a m 1995-2000 b . N a m 2000-2005 c. N a m 2 0 0 5 - 2 0 1 0 Hinh 7: Hinh minh hpa qua trinh sat Iff va b6i tu khu virc G4nh HSo hnyfn Gii Kai 3.2.7 Khu vuc cira Biin Nha Mdt din Vmh tich b6i tu la 0 ha; Giai doan 2005-2010 dien
Trach Dong tich sat lo la 72 ha va dien tich b6i tu la 45 ha.
Tinh hinh sat la va bai tu khu vuc cua Biln Kk qua di thuc dia cho thiy khu vuc cila Nha Mat (Hinh 8) qua cac giai doan diln ra biln Nha Mat, tinh Bac Lieu bi sat I* r&manh nhu sau: Giai doan 1995 - 2000 dien tich sat Icr 6 giai doan 2000 - 2005, din giai doan 2005 - la 3 ha va dien tich boi tu la 184 ha; Giai doan 2010 xu huang sat la giam djn do khu vuc nay 2000 - 2005 di?n tich sat Id la 220 ha va dien da triln khai xay ke chin song. Miic dd' sat Id
trung binh moi nam tit 0.5 m din 5 m.
a Nan, 1995.2000 b. N am 2000-2005 c. N a m 2005-2010 ' Hinh 8: Hinh minh hpa qui trinh sat 1* va b6i t j tir Nhi Mit den Vinh Trjch Bong
41
Tgp chi Khoa hgc Tnrang Dgi hgc Cdn Tha Phdn A: Khoa hgc Ty nhiin. <e va Moi Inrang: 26 (2013): 35-43 3.3 Danh gia chung
Nhm chimg cho ca khu vuc nghidn cuu thi xu huong sat Id ven bidn tang d§n giai doan
Bang 2: Dida ti'ch sat Id va boi tn qua tiing giai doan tv 1995-2010
2000-2005 va giam din giai doan 2005 - 2010;
xu hudng bdi tu giam din qua tiing giai doan, cu thd trinh bay qua Bing 2 ben dudi:
Cac qua tiinJi Dieit tich sat td (ha) T6ng sd Tnmg binh nam Dien tich boi ta (ha) Tdng s6 Trung binh nam
1995-2010 6.208
1241 3.495 699
1995.2000 2.274
455 3.032
606 ThM sian
2000-2005 2.739
547 1.168 234
2005-2010 2.430
486 1.029
206 - Giai doan tir 1995-2000 muc do sat Id
cda vijng nghien cuu la 2.274 ha, den giai doan 2000 - 2005 muc do sat Id tang len 2.739 ha, den giai doan 2005 - 2010 muc do sat Id giam chi cdn 2.430 ha.
Giai doan t u 1995-2000 muc do bdi m cua ca viang nghien cdu la 3.032 ha, ddn giai doan 2000 - 2005 mdc do bdi tu cd xu hudng giam cdn 1.168 ha, den giai doan 2005 - 2010 thl xu huong bdi tu tidp tuc giam vdi dien ti'ch boi t u l a 1.029 ha.
Giai d o ^ 1995 - 2000 do cdng tac quan \y riing phdng hg cdn qua Idng Ido nen mdt so ngudi dan p h i rimg xay dung nha cda, nudi trdng thuy san, ben canh do cac cdng trinh xay dyng bd ke chira dugc quan tam thuc hien.
Ddn giai doan 2000 - 2005 cac ca quan chdc nang quan Iy rdng phdng hg chat che ban,
tridn khai cdng tac frdng rung phyc hdi riing phdng hd, nhieu cong frinh dugc tridn khai:
xay dung dd bao, ke chan sdng, ndn muc do sat Id giim rd ret va xu hudng bdi tu tang len. Giai doan 2005-2010 mdt sd khu vuc sat Id nghidm trgng frd thinh didm ndng.
Mgt sd nguyen nhin chu ydu dan den qua trinh sat Id va bdi tu cd thd la do inh hudng cua cac ydu td tu nhidn va tac ddng cua con ngudi:
Yeu td tu nhidn: Tic ddng cua sdng, tac dgng do gid, anh hudng cda thdy fridu.
Tic dgng cda con ngudi: cd the do nbuTig hoat ddng cda con ngudi lam inh hudng tdi riing ngap man nhu nan chat phi rdng dd nudi frdng thuy san, xiy dung nha trai phep.
Sat Id xa Khanh Lam Bd ke xa Tan Thuan Sat Id mai dd I OOm-Bac Lidu Hinh 9: Hinb anh thuc dia dnh hinh s^t Id tai rndt sd diem khu vue nghien cdu 4 K i T LUAN VA DE XUAT
Tinh hinh sat Id va bdi tu ven bd bidn Ca Mau va Bac Lidu giai doan 1995 - 2010 didn bidn phdc tap. Qua trinh sat Id va boi tu ludn dan xen vdi nhau trong timg thdi ky. Trong dd.
Khu vuc sat Id nhidu nhat tai xa Tan Thuan va Tan Tien, huyen Dira Doi.
- Khu vyc bdi ty nhidu nhat tu Rach Cii Huong, huyen Nggc Hidn keo dai tdi cda Bay Hap, huydn Nam Can.
Tap chi Khoa hoc Trudng Dgi hgc Cdn Tho Phdn .4 Khoa hoc Ty nhien, Cong nghi vd Moi n-uang: 26 (2013). 35-43 Nhin chung cho den giai doan hien nay, bd
bidn Tay tinh Ca Mau xu hudng bdi tu chidm uu thd ban, bd bidn Ddng cua tinh C i Mau va Bac Lidu thi xu hudng sat !d lai chidm uu the.
Vide sd dung anh Landsat va ky thuat GIS bing phuong phip Iam ndi bat dudng bd trong nghien cdu tinh hmh sat Id va bdi tu ven bien cho ra kdt qua l i dang tin ciy dugc khi ddi chidu vdi kdt qui di thuc dia.
Anh Landsat sau nam 2003 bi sgc sau khi xd ly Iugng thong tin huu ich tren anh con Iai khoang 70 - 80% ndn cd thd dap ung dugc cho vide ip dung frong ITnh vuc nghien cdu niy.
Tiep tuc ung dung vidn tham frong giii doin va nghidn cdu sat Id va bdi ty cho c i khu vyc ddng bing song Cdu Long dd cd bien phap quan Iy v i sd dyng hgp ly ngu6n tai nguydn dat dai cua cac tinh va loan Qudc gia.
TAI LU^U THAM KHAO 1. Alesheikh, Ghorbanali and Nouri, 2007.
Coastline change detection using remote sensing, International Jumal of Environment Science and Technolo^, 4(1) 61 - 66.
2. Claire Casse, Pham Bach Viet, Pham Thi Ngoc Nhung, Hoang Phi Phung and Lam Dao Nguyen, 2012. Remote Sensing Application For coastline Detection In Ca Mau, Mekong Delta. Proceeding of Intemational Conferance on Geometics for spatial Infrastructure development in Earth and Allied Science-GIS IDEAS 2012. Ho Chi Minh city 16- 20/October/2012. JVGC (Japan - Vietnam Geolnfomiatic Consortium) Technique Document No 2. Pp \ 99-204.
3. D§ng van To, 2006. Beach Erosion in Doi Duong-Phan Thiet Tourist Resort and Its Proposed Measure, Vietnam-Japan Estuary Workshop, Vietnam: 151-156
4. Dang Van to and Pham Thi Phuong Thao, 2008. A Shoreline Analysis using DSAS in Nam Dinh Coastal Areas, hitemational Joumai of Geoinformatics, 4 (1): 37-42.
5. Dang Van To va Pham Thi Phuong Thao, 2008. Xic dinh dudng muc nude tii anh s6, Tuyen tap Bio cio Khoa hpc Hgi nghi Khoa hgc "Bidn D6ng-2007", Vidn Hai duong hoc Nha Trang: 591-600.
6. Nayak, 2005. Role of remote sensing to integrated coastal zone mjmagement.
Intemational Society for photogranimetry and remote sensing.
7. Nguydn Td Din, Nguydn Thd Ti^p, 2003. Xu the bien dpng cua cic cua song chinh d dai ven bidn ddng bang song Hong. Tap chi Khoa hgc va Cong nghd biln, T3, S6 1: 25-35 8. Nguyin Ngpc Th£ich, 1997. Vidn tham trong
nghien cuu tai nguyen mdi tnrdng. NXB khoa hgc kj tfiuit Ha Npi.
9. Tanaka, H, 2006. Monitoring of Short-term Morpholep Change at A River MouA,
" Vietnam-Japan Estuary Workshop, Vietnam:
1-6.
10. Thieler. E. R, Marline, D and Ergul, A, 2003.
The digital shoreline analysis system, version 2 Shoreline Change Measurement Software Extention for AcView, USGS. Open-File' Report 03-076.
11. Tran Thi Van, Trinh Thi Binh, 2008. Shoreline Change Detection to Serve Sustainable Management of Coastal Zone in Cuu Long Estuary, Intemational Sysposium on Geoinformatics for Spatial Infrastructure Development in Earth and Allied Sciences:
351-356.
12. Zhao, Gou, Yan, Wang and Li, 2007. A Simple Waterline Approach for tidelands Using raunli-temporal Setellite Images: A case study in the Zangtze Delta, Estuarine, Coastal and Shelf Science, 77,134 -142.
