Tap chi KHOA HOC OHSP TPHCM Trinh Phi Hoanh vd tgk
TINH BAT THirgNG TRONG SlT BIEN DONG Bd SONG TIEN DOAN CHAY QUA TINH DONG THAP
TRjNH PHI H O A N H ' , L t VAN AN"
T 6 M TAT
Bien ddng ba sdng Tiin Men nay so vdi su biin ddng phd biin trudc ddy cd su khdc biet Idn: qua trinh xdi Id bd sdng dang ngdy cdng uu thi, phd biin vdi cudng do manh, gia tang nhanh. phuc tgp vd xdy ra nhieu vao miia kiet. Nguyen nhdn Id do su biin ddi khi hdu dia cdu hien nay ket hap cdc hoat dong cua con ngudi lam gia tdng ddng luc ddng chdy hai miia. thay ddi Idng ddn vd dudng bd. De han chi sir biin ddng bdt thudng dudng bd song Tien, gidm nhe thiet hai theo chiing tdi cdn thuc thi nhdm gidi phdp diiu chinh vd nhdm gidi phdp thich ung.
Tir khoa: bien dpng bat thudng. xdi Id bd song, song Tiln tinh Ddng Thdp.
ABSTRACT
Abnormality of changing Ihe banks of Tien river in Dong Thap province There is the big difference in changing the banks of Tien river at present compared with the popular one in the past: The riverbank erosion process has occurred increasingly, with strong intensity, in the complex way, and even more in the dry season. The causes of this event are due to the interaction between climate change and activities of human that increase forces of stream flows in the two seasons, change the river bed and banks. In order to reduce these abnormal changes of the banks of Tien river and mitigate the damage, we propose some solutions for adjustments and adaptations.
Keywords: abnormal changing, riverbank erosion, Tien river in Dong Thap province.
1. Djt van de trung binh 10 - 15 m) [5]. Tinh bit Cung nhu cdc ddng sdng khac, thudng trong bien dgng bd hien nay dang trong qud trinh phdt triln sdng Cim Long gay khd khan Idn ddi vdi du bdo cung noi chung vd sdng Tiln ndi rieng, bd nhu xdc dinh vd thyc thi gidi phap phdng song ludn biln ddng khdng ngimg theo chdng dung ddn, kip thdi nen hdu qua do thoi gian. Nhung trong nhimg nam gin biln ddng bd ddi vdi cdc dia phuong cd day, su biln dgng bd sdng Tiln, nhit Id ddng sdng chay qua rat Idn.
doan chay qua tinh Ddng Thap dang diln Nghien cim su bit thudng bien ra rit bit thudng (song Tiin dogn chdy ddng bd, xdc dinh nguyen nhan vd de ra qua tinh Ddng Thdp ddi 129km: chiiu cdc gidi phdp han chi su bien dpng va rpng biin ddi nhiiu ldn, hep nhdt a An biln ddng bit thudng bd sdng Tien dang Long (Tam Nong) 450m, rang nhdt la vin dl dat ra rit cap thilt.
2200m d ddu cii lao Long Khanh: do sdu 2. N^i dung ^ -; 2.1 Tinh bit thudng trong su bien
ThS, Trudng 0?! hoc Dong Thdp g^f,g (,(/ song Tiin tinh Ding Thdp TS, Trudng Oai hpc Su pham - 0ai hpc Hu^
Tu" li§u tham khao sS 36 nam 2012 •
Theo Tir dien tiing Vi?t, bat thudng dupc hieu Id khdng theo le thirdng, dgc biet vd dc thay doi (Hodng Phe chii bien, Nxb. Tir dien Bach khoa, 2011). Cdn theo quan ni?m ciia chung tdi, sir bdt thuang ciia bien dpng bd song Id su bien diing co su sai biet ldn so vdi bien dqng phd bien chung ciia song ngdi vd bien dong ba phd bien dd timg vav ra a sdng Tien tinh Dong Thdp. TCr quan niem n:i\. su bien dpng bat thuimg bd sdng Tien lai tinh Dong 1 hap the hi?n:
2 1.1. Xdi la ba sdng dang ngdy cdng chiem tru the. phd bien vdi cudng dq mgnh. gia tdng nhanh
Xdi Id bd sdng Tiln tinh Ddng Thdp dien ra rit phd bien, hiu hit cac huyen cua linh cd sdng Tien chay qua deu xay ra hi?n tupng xdi Id. Qua dieu tra, khdo sdt kit hgp vdi ket qud nghien ciru cua ede tac gid [I], [3], [4], [5], [6], [7], [8] cho thay, rieng doan bd sdng Tiln chdy qua lanh thd linh Ddng Thap da cd hon 53 diem xdi Id. Trong do, cd nhung khu vuc xdi Id vdi tdc dp ldn, dien ra pham vi rpng nhu: khu vuc xdi Id Thudng Phudc Thudng Thdi Tiln (huyen Hdng Ngy) chilu dai xdi Id 6 km, chilu rgng sdu nhat vdp bd 1492 m, tdc dp xdi Id 34,7 m/ndm (1966 - 2009); khu vyc xdi Id sdng Tiln thj xd Sa Dee Chdu Thdnh keo ddi tren 10 km, tdc dp xdi Id trung binh 33,3 m/ndm, chilu rpng an sau ldn nhdt vao bd la 1433 m (1966 - 2002). Ngoai ra, xdi Id bd sdng Tiln khu vyc thj xa Hdng Ngu dang de dga cuoc sdng ngudi ddn sdng ven sdng eac xa An Binh B, An Lac; xdi Id d xa An Phong,
Tan Thanh (Thanh Binh) de dga pha huy Quoc Ig 30 trong thdi gian tdi.
Sy xdi Id bd d sdng Tien tinh Ddng Thdp trong thdi gian qua khdng nhung phd biln, manh mS ma cdn dang ngdy cdng cd xu hudng gia tang nhanh theo thdi gian. Trong nhimg ndm qua, xdi Id bd sdng d Ddng bang sdng Ciiu Long (DBSCL) ndi chung \a tren sdng Tien tinh Ddng Thap ndi rieng cd xu hudng gia tdng cd ve quy md va tdc dp. Trudc d;i\. xdi Id chi \a> ra mgt sd khu vuc nhu Hdng Ngy, Sa Dec thi den nay hau het cdc huyen ciia tinh Ddng Thap deu xay ra hi?n tupng xdi Id bd sdng. Trong dd manh nhdt dien ra tren sdng Tien d xd An Hi?p (Chdu Thdnh); xa Tdn Thuan Ddng (thanh phd Cao Lanh); cac xa Tan Binh, An Phong, Tdn Thanh (Thanh Binh): cdc xa thudc cii lao Long Khanh (huyen Hdng Ngy).
Bang 1 eho thdy, phan ldn cac hd xdi diu bi \di sau them tir 0,53 - 10,45 m trong giai do^n 1991 - 2003 da phdn dnh dupc hi^n tugng xdi Id vin dang gia tang theo thdi gian. Hien nay, miic dp xdi sdu vdo bd vd dao sau Idng vdn dang tiep diln. Trudc ndm 2000, cd 16 dilm xdi Id dupc xdc dinh d sdng Tien tinh Ddng Thdp thi din nay (2011) da xdc djnh dupc 53 dilm xdi Id Idn nhd [5].
Trudc ddy, xdi Id thudng xay ra tit til, muc dp mdi dpt xdi Id nhd nhung nhiing ndm gin ddy xdi Id bd sdng Tiln xdy ra nhanh, khdi lugng dit sat Id ldn.
Cu thi, dpt xdi Id ngay 16-8-2011 tai Td 19, Ap 1 (Thudng Phudc 1, Hong Ngu) xdy ra dpt sat Id nghiem trpng, keo ddi tren 100 m, sdu 20 m, lam syp dd 3 cdn
T?p chi KHOA HOC BHSP TPHCM Trmh Phi Hoanh vd tgk
10.000 m ddt, de dpa cupc sdng gin 70 hd ddn sdng ven sdng...
nha xudng sdng. Dem 22 rang sang 23/9/2011 d dp An Thuan (An Hiep, Chau Thdnh) xdy ra xdi Id eudn trdi gdn
Bdng 1. Quy lugt dien bien cdc hd xdi a sdng Tiin tinh Ddng Thdp giai dogn 1991-2003
Vj In ho .xdi Hdng Ngu Binh Thanh SaDec My Thuan
£)p sdu ldn nhal (m) 1991
35,78 21,12 31,36 45,21
2003 36,31 31.57 32,85 48,94
a 0,53 10,45 1,49 3,73
*
362,3 430,0 613,8 500,0
c 30,19 35,83 51,15 41,67
i 138,2 70,50 520,0 95,50 Ngudn: [6]. Ghi chu: a - Chenh lech do sdu (m); b - Khodng cdch dich chuyin vi hg km (m), c - Tdc do dich chuyen xudng hg Imi (m/ndm), d - Khodng cdch dich chuyen
\ao bd (m).
2.1.2. Xdi la ba song dien ra phirc tgp Ngoai tinh quy luat (xoi la xay manh a bo phai. dau cac cu lao, doan phan nhap luu; xoi 16 chu yeu dien ra trong mua lu o nhung doan song chiu anh huong chinh ciia dong chay thugng nguon), xoi la ba song Tien tinh Dong Thap con dien bien rat phirc tap.
Tinh phuc tap cua xoi 16 ba song o day the hien cac diem xoi 16 xay ra ca 6 ba trai (Hong Ngu, Tam Nong, Thanh Binh - hinh I) lln ba phai (Sa Dec, Chau
Thanh); ca ba loi (Hong Ngu) va bo I5m (Sa Dec); xoi 16 xay ra 6 dau cac cii lao (cii lao Long Khanh, cii lao Tay, cii lao Chai - hinh 2) va ca duoi cac cii lao; vira CO xoi 16 thanh bo va vira co xoi 16 mai b6; xoi 16 xay ra suot ca thoi gian trong nam (xoi 16 xay ra trong miia lu lan miia kiet) va vkx da dang ve loai hinh xoi 16 (xoi 16 mai bo song; xoi 16 vira c6 tinh chat mat can bang ve sue tai cat; viia c6 CO tinh chat m4t can bang ve mat ca hoc;
vira CO xoi ngam ca hgc...)-
Hinh 1 \oi lo bo song Tien \ny fa a ba trdi thupc huyen Thanh Binh
Hinh 2. Xoi la ddu cii tao Chdi thdnh phd Cao Lanh
Tir lieu tham khao So 36 ndm 2012
2.1.3. Xoi la ba sdng Tien ngdy cdng gia tdng trong mua kiet
Trong nhimg nSm 90 ciia the ki -XX. tinh trang xdi Id bd sdng chu yeu xay ra trong miia ID nhung hi?n nay, xdi Id dien ra cd trong miia lu lan miia kiet va ed xu hudng tdng trong miia kiet.
Nam 1994, sau miia lu xuat hign them 4 diem xdi Id mdi, cdn trong miia ki?l chi cd I dilm xdi Id mdi. Ndm 2000 - nam lii lich sir d DBSCL, sau mua lu xudt hien 7 diem xdi Id, miia kiet cd 2 diem xdi Id mdi thi din ndm 2009 trong miia lu cd 6 diem xdi Id vd mua ki?t cd 4 dilm xdi Id mdi va miia kiel ndm 2009 - 2010 cd them 4 diem xdi Id nhd.
2.2. Nguyen nhan gay nen linh bat thudng Irong bien dong bd song Tiin linh Bdng Thdp hien nay
Sir biln dpng bat thudng hien nay cua sdng Tien tai Ddng Thdp true tiep Id do su gia tdng ddng luc ddng chdy hai miia vd sy thay ddi Idng ddn ciia sdng.
Nhung sy gia tang ddng lyc ddng chdy hai miia vd su thay ddi Idng dan cua sdng lai do tdc ddng tdng the cua nhieu nguyen nhdn sau xa (cd the ggi la tdc nhdn) sau:
2.2.1. Nhdm nguyen nhdn tir nhien Nguyen nhan ty nhien gay bien dgng bit thudng dudng bd sdng Tiln tai Ddng Thap hien nay ddng vai trd quylt djnh nhdt Id sy biln ddi khi hau dja ciu.
Chinh do su ndng Ien ciia khi hau Trai Ddt dang lam cho myc nude bien dang, lam gia tdng ddng chdy trilu (nhdt Id trong miia kiet, dong chdy nguqc dual tdc dong ciia thuy trieu xudt hien tren todn bo ddng song Tien dogn chdy qua
tinh Ddng Thdp) ddng thdi lam gia tang Iu ve mgi phuang dien (trong miia Id).
Theo nhieu cdng trinh nghien cim trong nude vd the gidi cho thdy, Viet Nam dupe dy bdo se Id mgt trong nhung nude chiu dnh hudng ndng ne nhdt eua bien ddi khi hau md DBSCL Iai la noi hirng chiu nhilu thift hai nhit d nude ta.
Mpt trpng nhung bieu hien rd net nhdt eiia bicn ddi khi hdu dd Id lugng mua d luu vuc sdng Me Kdng ndi chung vd lai tinh Ddng Thap ndi rieng. Lupng mua cd su bicn dpng Idn giira miia mua - khd (ndm 2010, luang mua a linh Ddng Thdp tdng mgnh 23S7.8 mm/ndm nhung Irong thdng 2, 3 hdu nhu khdng co mua) Id nguyen nhan chinh dan den lupng nude d h? thdng sdng Me Kdng cung phdn hda sau sdc theo miia. Miia mua lugng nude Idn, tap trung trong thdi gian ngdn nen lupng nude dd vao sdng nhilu, van tdc cao gay ID lyt Idn nhu nam 2000, 2001, 2011 (Thai Lan, Campuchia, DBSCL... ) va xdi Id bd sdng diln ra manh.
M}t khdc, trong miia kiet lugng nude nhd ket hgp vdi dja hinh thip vd bdng phdng dd tao dilu kien cho thuy trilu xam nhap sau vao dit liln (do gidi han truyen Irieu tren song Me Kong vdo miia kiel Id khodng 350 km, con mita IH khodng 150 - 200 km tir cira biin len phia thuqng nguon, vol chi do bdn nhdt trieu Bien Ddng, Idc do truyin triiu Iren song Tiin miia kiel Irung binh 25 km/h [II]). Tai My Thuan, tdc dp ddng chay ngugc trung binh 0,5 - 0,8 m/s, ldn nhit cd thi d?t 1,12 m/s (24/4/1978). 6 Tdn Chau, tdc do ddng chay ngugc trung binh
Tap chi KHOA HOC DHSP TPHCM Trinh Phi Hoanh vd Igk
0,2 - 0,3 m/s, Idn nhdt cd thi dat 0,395 ni/s(I2/4/I987)[9].
Xet ca trong miia Iu Idn mua kiet.
van tdc ciia ddng chdy (xudl) tren sdng Tien deu Idn hon miic cho phep khdng xdi cua Idp dit bd sdng (bdng 2). Trong do, miia lu thudng gay xdi Id ldn do miia lu d DBSCL thudng keo dai 2 - 3 thang vd luu lugng khd Idn (lini lirang miia lii trung binh nhieu ndm khodng 20.000 26.000 m\ lan nhdt dat 30.000 m'is.
van tdc miia lii tir 2.4-2.7 m/s). Mua kiel Bdng 2. Van tdc ddng chdy song Tien vc
van toe ddng chdy sdng Tiln cung ldn hon 2,0 - 2,5 lin van tdc cho phep khdng xdi trung binh cua Idp dit bd sdng. Mat khdc, lai chju su chi phdi manh me vd Idm phirc lap bdi thuy trilu nen xuit hien nhtmg ddng chay ngupc vdi van toe Idn (ldn nhdt khi gid Chuong xudt hien kit hap vdi trieu cudng), lien tuc Ihay ddi chieu (nhdt Id cdc khu vuc ha nguon sdng Tien ciia tinh Ddng Thdp nhir doan My Thugn - Sa Dec...).
van tdc cho phep khdng xdi ciia bd sdng (Dan vi: m/s)
Vj tri bo"
Tan Chau SaDec My Thuan
Miia lu Van tdc trung
binh ddng chdy sdng 2,70 2,40 2,45
Van tdc trung binh cho phep
khdng xdi ba sdng tuang
img 0,58 0,58 0,55
MCia kift Van tdc trung
binh dong chdy sdng
1,10 1,20
Van toe trung binh cho phep
khdng xdi ba sdng tuang
img 0,58 0,55
Mat khdc, theo Kjch ban Bien ddi khi hdu va nude bien ddng cho Viet Nam [2] neu myc nude bien ddng cao 65 cm vdo cudi thi ki XXI thi dien tich dit viing DBSCL bj ngap Id 5133 km^ (12,8% tdng dien tieh), muc nude bien dang 75 cm thi dien tich ngap Id 7580 km^ (19%), muc nude biln dang 100 cm thi dien tieh ngap Id I5.II6 kra^ (37,8%). Trong giai doan hien nay, mue nude bien cua Viet Nam tang trung binh I - 2 cm/nam, trong vdng 50 ndm qua muc nude biln tai tram Hdn Diu dang len khoang 20 cm. Cdn d BBSCL, muc nude biln trung binh cung
Nguon: xir li lir [6], [7].
dang eao (giai dogn 1988 2008, muc nude bien trung binh tdng 1,8 mm/ndm a
Viing Tau: 11,6 mm/nam a Binh Dai:
14,5 mm/ndm a My Thanh [W]). Dieu nay se 1dm gia lang xdi Id bd sdng Tien ndi rieng va he thdng sdng khu vuc DBSCL ndi chung.
2.2.2. Nhdm nguyen nhdn do con nguai Su tac dgng cua con ngudi tao nen su biln ddng bit thudng bd sdng Tiln chinh Id cdc hoat ddng Idm gia tdng dgng luc ddng chdy, tinh eye doan ciia chi do ddng chdy hai miia, Idm thay ddi long sdng ndi chung vd true Idng dan ndi
Tu" li^u tham khao S6 36 ndm 2012
rieng. Nhttng lac dgng lieu cy:c ciia con nguai bao gom:
*l* Phd rimg ddu ngudn
Tham ihi^c vgt rimg co vai tro rat quan trgng trong dieu tiet nu6c song, lani ban che su phan hoa ihco miia ciia dong cha\. Truac dii), Iren loan luu \Lrc song Me Rong dien lich phii rimg rai Ion va chii )cu la rirng nhiet doi. co kha nang dieu licl nuac rai cao. Hi?n nay. dien lich va chat lugng rimg suy thoai nghiem trgng. Tren loan luu vuc. nhal la khu vyc dau nguon dien lich rimg ngay cang giam sut, do che phii rimg chi con 30 - 40%, so rimg con lai chii yeu la tai sinh. kha nang dieu tiet nuac giam. Chi tinh rieng tai Dong Thap, dien tich rimg dang giam ro ret. nam 2008, dien tich rimg la 8975 ha, 2009 la 8378 ha dan nam 2010 con lai 7593 ha. [4]
Thuc trang suy thoai rirng hien nay dang gop phan lam cho che do nuac phan hoa theo miia mang tinh cue doan (phdn van toe ddng chdy da chung minh) va qua do tang dgng lyc dong chay hai miia, ga\
xam thuc - x6i 16 ba song.
•t* Tinh bdt hg'p li ciia cdc cdng trinh kinh te - ddn sinh tren va ven sdng
Hien nay, do nhu cau phat trien kinh te - x5 hgi (KT-XH), tren va ven song Me Kong co rat nhieu cong trinh ra dai. Trong cac cong trinh xay ven va tren he thong song, cong trinh c6 anh huang lan nhat den bien dgng ba phai ke den cac cong trinh thiiy dien, thiiy Igi. Theo thong ke hien nay co tai 12 cong trinh thiiy dien da, dang va du kiln xay dung tren he thong song Me Kong. Xet ve muc tieu, cac cong trinh nay la khai thac dien
nang va di§u liCn nuoc. Nhung vai Ihuc trang chung hi^n nay, cac cong trinh thiiy dign, thiiy Igi chii yiu coi trgng khai thac dien nSng va bao dam Igi ich kinh te cho cac nha dau tu nen cac cong trinh chua dam bao yeu cau kT thuat, \ iec dieu tiet nuac thuang mau thuan vai muc tieu (mua lii xd nirac, miia kho tich nuac).
Tinh bat hgp !i ciia cac cong trinh nhu vay dang la mgt trong nhihig tac nhan lam tang linh phan hoa cue doan hai miia va eye bg timg thai diem cua dong chay qua do lam tang them qua trinh xam thuc - xoi 16 ba.
• Khai thdc cdt sgn
Khai thac cat san phyc vu xay dung la hoat dgng tat yeu va la nganh nghe co tir lau dai. Nhung hien na\. do nhu cau vat lieu xay dyng rat lan va gia tang rat nhanh, nham phyc vy cho hien dai boa nen kinh te nen boat dgng khai thac eat san tren cac song noi chung va he thong song Me Kong noi rieng phat trien 6 at, thieu tinh khoa hgc.
Theo thong ke [1]. [5] cho thay, 6 Campuchia, mdi ngay co khoang 50 - 60 tan cat khai thac tren he thong song Me Kong de xuat khau sang Singapore. Con 6 Dong Thap, theo So Tai nguyen va Moi truong chi tinh rieng cac dcm vi dugc cip phep thi hien nay tinh D6ng Thap udc tinh san lugng cat san khai thac trung binh 8 trieu mVnam vai hang tram ghe thuyin khai thac cat san Iren song.
Voi kh6i lugng vat chit khai thac 6 long song, nhat la doan chay qua ha luu nhu song Tiln tinh D6ng Thap mgt mat lam tang t6c do dong chay miia lu (do su tucmg phdn dp ^dc giira thucmg va hg
Tap chi KHOA HOC DHSP TPHCM Trinh Phi Hodnh vd tgk
Imi) va dong chay ngugc ciia trieu (do thay doi do doc tu nhien ciia sdng). Mat khac, sy khai thac cat con lam thay doi trie dien (trdc dien dgc, trdc dien ngang) tu nhien long song, nhat la thay doi duong tu thiiy tao nen sy bat thuang ciia dong chay, gay xoi 16 ba nhanh va bat quy luat.
• Sir dung nuac ngot mdu thuan vai ngudn nuac tu nhien ciia sdng
Nam trong dieu kien khi hau mua miia sau sac, tren loan luu vyc song Me Kong noi chung va song Tien noi rieng von dl da CO mau thuan giira nhu cau nirac va nguon nuac hai miia ciia song (miia khd can nhu cdu dimg nuac cdng nhieu). Hien nay, voi su phat trien KT- XH, nhu cau sii dung nu6c nhat la trong miia kho rat lan. Viec khai thac nguon nuac mang tinh mau thuan nguon nu6c cung cap (chu yeu la tir sdng) dang lam cho muc nuac song vao miia kiel cang ha thap va dong trieu di chuyen cang manh, xam nhap cang sau, gay bien dgng ba.
Ngoai ra, sy bien dgng bat thuang con do nhilu boat dgng KT-XH khac nhu hoat dpng nuoi trong thuy san tren song Tien bat hgp Ii (lam thay ddi ddng chdy tir nhien); xay dyng he thong tuoi tieu bat hgp li (vira lam suy can muc nuac miia khd, lam thay ddi dong chdy... ) ; sy gia tang phuang tien giao thong duang thiiy ca so lugng va tai trgng (gdy song vd mgnh vdo ba); khai thac dSt 6 ba song, nhat la khu vyc bj x6i 16 hoac eo nguy co xoi 16 cao...
2J. Be xuat gidi phdp han che bien
^dng bdt thudng b& song Tiin vd giam fihf thi^t hat
De giai quylt mgt each hgp li, co hieu qua vin.de xoi 16 cin phai thuc thi nh6m giai phap ban che nguy co (nhom giai phap dilu chinh tac nhan) gay xoi lo bat thuang va nhom giai phap thich irng;
2.3.1. Nhom gidi phdp diiu chinh Nhom giai phap dieu chinh can dugc thuc thi ca ve mat ty nhien va hoat dgng ciia con nguai. Nhung xet vl kha nang va goc do vi mo, chung toi chi de cap den giai phap dieu chinh boat dgng ciia con nguoi. dong chay tai dia phuang.
Nhom giai phap nay nham myc lieu dilu chinh boat dgng ciia con nguoi theo huong lam giam nguy co gay xoi 16 den mirc toi da va dugc cu the hoa nhu sau:
Trong va bao ve rirng, nhat la 6 nhiing khu vyc ngap nu6c chua phen, dau nguon song. Ben canh do, nhiing khu vuc xoi 16 nho, dan cu tap trung it nhu cac khu vyc xoi 16 6 dau cii lao Long Khanh, huyen Cao Lanh, huyen Lap V6, xa An Nhan {Chau Thanh)... tang cu6ng trdng tham thyc vat nhu beo, du6c, dira nu6c...
- Tiln hanh quy hoach cac tuyen lulng chay tau, khong gia tai qua muc len mep song. Dac biet, 6 nhiing khu vyc xoi 16 hoac co nguy co xoi 16 cao (cac khu vyc dau cii lao Long Khanh, cii lao Tay, cii lao Chai, xa An Hiep) can kien quylt khong cho nguai dan xay dyng trai phep cac cong trinh KT-XH...
Hoan thien he thong phap luat dl ban chi tinh trang khai thac cat san qua mirc, khai thac dat ba song noi xoi 16, nuoi trdng thiiy san thiiu quy hoach tren song Tiln, su dung ngudn nu6c sdng lang phi va qua mirc, r\hk la trong miia kiet...
Tu" li$u tham khao Sd 36 ndm 2012
Tang cuang hgp tac (giu-a cac dia phuang trong khu vyc, giOa cac qudc gia cd chung luu vyc sdng) trong khai thac va su dyng sdng Me Kdng ndi chung va sdng lien noi rieng theo hudng dam bao Igi ich hai hoa va phdt trien bin vCrng cung nhu Irong nghien cuu, xir li, canh bao xoi 16 bd sdng (giu'a chinh quyen dia phuong. nhan dan va giOa cac nha khoa hgc).
Su dyng phao huang ddng de lai dong chay. ngan ddng chay co luu tdc Idti lac dgng tryc liep vao khu vyc bd bj xdi 16. Phao huang ddng la mgt loai cdng nghe moi co nhieu uxi diem (su dyng hieu qua trong dieu kien chinh tri ddng chay theo hai chieu, co kha nSng su dyng nhieu lan, 6 nhieu vj tri va eo kha nang thao lap de dang). Phao huang ddng cd the sir dyng 6 cac khu vyc bi xdi 16 hoac nguy ca xdi 16 cao nhu 6 xa An Phong (Tan Binh), xa Tan Thuan Ddng (thanh phd Cao Lanh)... de ban che xoi 16 xay ra.
2.3.2. Nhdm gidi phdp thich img Nhdm giai phap nay nham muc lieu tang thich nghi, khang ve ciia cdng ddng ddi voi xoi la. Vol myc lieu nay, nhdm giai phap thich ung bao gdm hai bi?n phap: cdng trinh va phi cdng trinh:
*X* Bi^n phdp phi cong trinh: Cac bien phap phi cong trinh nham myc dich phdng ngCra va ne tranh khu vyc xoi 16, thuang bao gdm cac bien phap sau:
Giao due nang cao nh^n thirc eiia chinh quyen dia phuang va cgng ddng dan cu sdng ven sdng Tien ve nguyen nhan, muc do thi?t hai va each phong tranh, phuang phap xir li khi xay ra xdi 16 ba sdng. Dac biet, khi c6 dau hieu (niit
dat, 16 dat ven sdng) cin kip thoi bao cao cac cap chinh quyen de c6 phuang an giai quyet.
Dy bdo hanh lang, canh bao nguy ca xdi 16 va di dai nguoi dan ra khdi khu vyc cd nguy ca xoi 16. H? thdng canh bao phai dam bao chuc nang giam sat, theo ddi va chuan bi dy bao canh bao. Pham vi an loan dugc nhieu tac gia xac djnh nhu sau: pham vi an toan > 20 m ddi vai sdng sau h < 10 m va h? sd mai ddc > 2; pham vi an loan > 25 m ddi vai sdng sau 10 m >
h < 15 m va he sd mai doc > 2; pham vi an toan Ion > 30 m ddi voi sdng sau > 15 m va he sd mai ddc > 2. Vi the, tinh Ddng Thap can ed ke hoach dl doi nguai dan a khu vyc cac xa dau cii lao huyen Hdng Ngy (Long Thuan, Long Khanh); xa Tan Quai, An Phong (Thanh Binh); dp An Thuan, An Thanh x§ An Hiep (Chau Thanh) ra khdi khu vyc cd nguy ca xdi 16 cao.
• Bien phdp cong trinh
Bien phap cdng trinh thuc thi tryc tiep tai cac vimg xdi 16 hoac cd nguy ca xdi 16 cao va bao gom cac bien phap sau:
Gia cd ba. Gia cd ba cd the su dung cac bien phap tham thyc vat (cay dira, cay mam, duoc, ban, cac loai beo, tham lyc binh... rat phii hgp vai tinh Ddng Thap 6 nhirng khu vyc huyen Tam Ndng, Thanh Binh, Cao Lanh); ke lat mai (ke lat mai, ke da xay, ke rg da); tucmg chSn (cgc ke thuang bang be tdng hoSc cay go nhu tram, tre ket hgp vol tham thyc vat) nham tang cuang kha nang cd kit cua ba, giam sire chiu tai cua mep ba. Cac phuang phap nay dugc sir dung kha phd bidn va cd hieu qua cho ba sdng tinh Ddng Thap trong dd bo ke la giai phap
Tap chi KHOA HOC DHSP TPHCM Trinh Phi Hoanh va tgk
hieu qua nhit nhung khd khan la ngudn kinh phi lan va su dn dinh lau dai cua cong trinh.
Kenh, rach phan ddng. Nd cd tac dung phan bat ddng chay vao kenh, ddng chay qua khu vyc xoi Id giam. Kenh thucmg dugc dao 6 phia bd loi, cua vao song Ihuan ddng 6 phia thugng luu khu vyc xoi 16 bd. Thi cdng kenh chi can dao ranh nhd, khai sau ddng, sau dd ddng chay ty md rdng mat clt. Kenh phan dong c6 the su dung 6 doan sdng Tien thuoc huyen Hdng Ngy.
Su dung ke md han. Md han la loai cong trinh dugc su dyng rdng rai nhat trong chinh tri sdng. Bao gdm hai loai la mo han dai va md ban ngan. Md ban dai CO tac dyng thu hep Idng sdng, lam thay ddi vi tri eiia true ddng lyc, cdn md ban ngan chi de ddn da chu luu, bao ve bd bai. Vat lieu lam md ban thdng dung nhat la da dd, bao tai cat ciing Idp.rg da de bao ve hay hang cgc be tdng. Md han cd the sir dung de chinh tri sdng Tiln khu vyc thi xa Hdng Ngy, Sa Dec...
3. Ket luan
Xoi 16 ba sdng Tien doan chay qua linh Ddng Thap dang diln ra manh me, diln bien phirc tap va cd xu huang gia tang vao miia kiel. Nguyen nhan ciia sy bien ddng bat thudng trong xdi 16 bd sdng la sy thay ddi ciia he thdng ty nhien dia cau (chii yeu la bien ddi khi hau va nude biln dang) va hoat dgng KT - XH chua hgp li tren loan bd luu vyc sdng Me Kdng.
Xdi 16 bd sdng Tien doan chay qua tinh Ddng Thap tieu bieu cho xdi Id viing sdng ha chau thd, chiu anh hudng chii yeu ciia ddng chay thugng ngudn nhung van bi chi phdi bdi ddng chay thiiy trieu.
Dk qua trinh bien dgng bd sdng Tien ndi chung va sdng Tien doan chay qua tinh Dong Thap ndi rieng diln ra binh thuang, mang tinh quy luat cin phai cd cac giai phap dieu chinh boat ddng cua eon ngudi Iheo hudtig giam nguy ca gay biln dgng ddng thoi phai cd cac giai phap thich ung, giam nhe thiet hai ddi vai thyc trang biln ddng bd hien nay.
TAI LIEU THAM KHAO
Le Van An, Tnnh Phi Hoanh (2011), "Xdi Id bd sdng Tiln doan chay qua tinh Dong Thap. Thyc trang, nguyen nhan va giai phap", Tgp chi Khoa hoc & Gido due, Truang Dai hoc Suphgm - Dgi hgc Hui. 04(20), tr. 56-66.
Bo Tai nguyen va Mdi truang (2009), "Kich ban biln ddi khi hau va nude bien dang cho Viet Nam", www.imh.ac.vn, 21/11/2009.
Ha Quang Hai (2010), "Tai biln xdi 16 - bdi ty long song doan Tan Chau - Hdng Ngy til gdc nhin ciia dia mao hgc", www.idm.gov.vn, 21/11/2010.
Trinh Phi Hoanh (2011), "Cac nhan id tac dgng xdi 16 ba sdng Tien doan chay qua lanh tinh thd Ddng Thap"', Thdng bdo Khoa hgc, Trudng Dgi hgc Bdng Thdp, (01), tr. 74-79.
Trinh Phi Hoanh (2011), Nghien cuu xdi Id bd sdng tinh Dong Thdp Luan van thac sT Dia li tu nhien, Truong Dai hpc Su pham - D?i hgc Hue, Hue.
Tu' lieu tham khao Sd 36 nam 2012
6 Le Manh 1 liing (2008), Xdi hiii he thdng si'mg rach viing DBSCL. Nxb Ndng nghi$p, TPHCM
7. Nguyen Quang My, Vii Vdn Vinh, Dinh Bdo Hoa (2003), t'lr sd li ludn vd thuc te .Ndc dinh \ im dl nghien ciru du bdo sal Id sdng Tien", Hqi thao Nghien ciru ca hdn trong linh vuc cdc khoa hoc vi Trdi Dat phlic vu phdt trien ben vimg KT-XH khu virc KuniBd. hup ''www.diacliatvn.com.
8. Lam Dao Nguyen, Nguyen Thanh Minh, Pham Thi Mai Thy, Hoang Thi Phung, Hoang Van Huan (2010), "Analysis of changes in river bank of Mekong river, Vietnam by using multi-temporal remote sensing data", hup www isprs.org.
29/03/2011.
9. Ngd Trgng Thuan (2007), "Ddng chay miia can d DBSCL". Tuyen tap bdo cdo Hgi thdo khoa hgc ldn thir 10. Vien Khoa hoc khi tuang thuy van vd Mdi trudng.
TPHCM.
10. Tran Thuc, Hoang Minh Tuyen, Huynh Thj Lan Hucmg, Dinh Xuan Trudng (2007),
"Danh gid anh hudng cua cac phuang an sir dyng nude cua cdc qudc gia thugng ngudn den ddng chay DBSCL", Tuyen tap hao cdo Hdi thdo khoa hoc ldn thir 10.
Vien Khoa hoc khi tirang thiiy vdn vd Mdi trudng. TPHCM.
11. Nguyen Nggc Tran (2010), "Ddng bang sdng Ciru Long ddi mat vdi thach thire kep ciia bien ddi khf hau", http://vncold.vn (download 21/11/2010).
(Ngiy T6a soan ntt$n duuc bii 26-12-2011, ngay chip nhin aSng 24-4-2012}