Các tác động môi trường của dự án nạo vét duy tu tuyến luồng tàu định an cần thơ (khu vực tỉnh trà vinh)

Hgi nghi Khoa hgc vd Cdng ngh^ bien loan qudc Idn th CAC TAC DONG MOI TRlTcyNG CUA DlT AN NAO VET DUY TU TUYEN LUONG TAU DINH AN - CAN THO (KHU v y c TiNH TRA VINH) Bui Trong Vinh'\ Huynh Trung Tin'' Nguyen Xi£m Bang^', Td Quoc Huy^* 1) Khoa Ky thuat Dja chit va Ddu khi, Dai hpc Bach Khoa Tp.HCM 2) Cdng ty T>JHH Dia chit vd Mdi trudng Ddt Viet, Tra Vinh Email: btvinh(a).hcmut.edu.vti hogc biiilronevinh^gmail.com Trong nhimg ndm gdn day viec ngo vet tu luong tdu vd khai thdc tdi nguyen viing cira sdng ven bien diin rdt mgnh Hit Tuy nhien, cdng tdc diiu tra vd ddnh gid tdc dgng moi tricdng cua cdc hogt dong ndy cho den vdn chica dic(xc thuc hien nghiim tiic Tuyen luong tdu Dinh An - Cdn Tha (khu vice cira sdng ven biin tinh Trd Vinh) hdng ndm bf bdi Idng trdm tich tic song Hdu dd gdy kho khdn rdt lan cho cdc tdu van tdi luu thong qua khu v(fc ndy Du dn ngo vet tu tuyen luong tdu Binh An - Cdn Tha dugrc thuc hi$n hdng ndm vdi muc dich khai thdng luong, tgo diiu ki^n thugn Igi cho cdc tdu cd tdi trgng lan cd the luu thdng vdo di ddng hon Trong bdi bdo ndy tdc gid dd su dung cdc phuang phdp ddnh gid tdc ddng mdi trudng tic cdc hogt dgng ngo vet vd di cdc chuong trinh qudn ly hgp ly mdi trudng khu vice Bin cgnh phuong phdp md hinh sd dugc sic dung di ddnh gid tdc dgng ciia sdng vd ddng chdy tdi moi trudng khu vice sau ngo vet Kit qud cho thdy, sau ngo vet ludng tdu, chdt luong mdi trudng cUng nhu he sinh thdi se bi thay ddi nhung khdng ddng ke ENVIRONMENTAL IMPACTS OF THE PROJECT OF DREDGING AND MAINTAINING DINH AN - CAN THO SHIPPING CHANNEL (TRA VINH AREA) In recent years, the dredging of navigational channel and resource exploitation in coastal areas have been carried out increasingly However, the investigation and the environmental impact assessment of these activities have not been done yet Early Dinh An - Can Tho navigational channel (the section of Dinh An river, Ben Tre province) has been deposited severely by sediments from Hau River, caused an obstacle of navigation operating The project to dredging Dinh An - Can Tho navigational channel has been carried out helping heavy ship to travel through easily Tieu ban Sinh thdi, Mdi trudng vd qudn ly Bien Disposal can bury all ecosystems at disposal site and a new ecosystem will be replaced In this paper, the authors i4se the environmental impact assessment methods in implementing the project and proposing the environmental monitoring program Numerical modeling method has been also used to evaluate the current change due to dredging The results showed that after dredging navigational channel, the environment and ecosystem have been changed not much Gidi thi^u Ludng tdu biSn Dinh An - Can Tho Id mgt tuyln ludng quan hrpng ddi vdi giao thdng thiiy va phdt trien kinh te ciia ddng bdng sdng Cim Long Qua trinh b^i lang ciia phu sa sdng Hdu mang lai nhiSu Igi ich nhung cung gay can trd iuu thdng thdng qua tuyln ludng De dam bdo cho vi?c luu thdng cua tau thuyen, viec nao vet tuyln ludng da dugc thyc hipn Tuy nhien, tac d§ng tii viec ngo vet ludng tdu ddi vdi mdi trudng la tuong ddi Idn Do vay, can cd nhiing nghien ciiu ddnh gid tac ddng mdi trudng de cd the cd nhiing bien phdp gidm thieu hieu qua Hhih I Id so dd vi tri lay mau vd va mdt sd hinh anh khu vyc nghien cim P^^ -1 '^^H f H ^ L o n o VTnn L * (in D* I fi,r\ Tnsnn ' n Thanh U j •i ^ IB skf l ^ 'f j ^ ^ t »B,,M, Cua Tranh D* iBInh' • n hsx I'IStai ( ApConC Bl, M l 1 60011 Goo^ - Terms ot Use Hinh 1: Sa vi tri lay mdu vd hinh dnh khu vuc nghien ciru BI: Bun day khu vuc ngo vet B2: Bim ddy khu vyc bun Mj: Mau nude mat khu vyc ngo vet M2: Mdu nude mdt khu vyc dd bun Hgi nghi KIwa hgc vd Cdng ngh? bien loan qudc Idn th Phuong phap nghien ciiu 2.1 Phuang phdp phdn tich vd thirc dja D I thuc hien cdng tac ddnh gid dnh hudng ciia du an nao vet tu ludng tau Dinh An cin Tho (khu vyc cira biin Tra Vinh), nhdm tdc gia da thuc hien chuyin dac thyc dia tai khu vyc du an Moi dgt thyc dia, cac mdu khdng khi, trim tich, nude biln(6 miu) dupe lay theo tieu chudn Viet Nam va chuyin vl phdng thi nghiem phan tich cdc chi tieu chdt lugng mdi trudng Quy chuin Viet Nam dugc sir dung de danh gid chit lugng khdng vd chat lugng nude khu vuc dy an [9] VChit lugng tram tich dugc phan tich vd so sanh vdi tieu chuan chit lugng tram tich ven bd Canada [5] 2.2 Phuong phdp md hinh so D I ddnh gia cac tac dpng ciia sdng, ddng trieu gay nen cac qud trinh sat Id va dien bien moi trudng dien d khu vuc sdng va viing cira sdng ven bien, md hinh sd da duoc thilt lap dl du bao su phan bd cua ciia sdng, ddng chay, thuy trilu va sy tuang tac giiia chiing [1,4]: i^"^" ^n)}^•-^{vih^n, dt (ss„ ss„\ p(h+n) [cK '* BU a dx av {•U dl dy , 1 dy • p(h+n)\ v'-L dx (2) Sy as„'\ p{h+n) a„ dy p(h+n) ' (3) (4) Trong do, TI la dp dao dpng be mat; U va V - van toe cue dai theo chilu ngang va chieu dpc cua nude tinh; E - mat dp nang lupng song va duac tinh theo phuong trinh (8); C - v|n t6e pha song; Cg - van t6c t6ng hop; - huong song; D, - t6n that nang lupng; S^x, Sx„ va Syy - ling suat tan xa song dupe tinh bang cac phuong trinh (5) — (7); Xx va Ty - ung suat c3t trung binh theo phuang x va phuong y; h - d6 sau nuac; g - gia t6c trpng truong; p - ty trpng cua nuoc; L' - he so roi ngang: = f{> (^-)) S =S C =£—E-cosSsine (5) (7) Tieu ban Sinh thdi Mdi trudng va qudn ly Bien E= ^ (8) Bien dp cua ung suat e4t dupe tinh tpan dua vao phuong tritrh (9) (Johnspn, 1963): 2" = pf.V'^ (9) Trong do, Ur la van toe ket hpp giGa song va dong chay ciia nuac a ducri day tinh theo phuong trinh (10) (Sawararagi et al , 1995) va f„ la he s6 ma sat duoc tinh theo phuang trinh (14) (Swart, 1974) [4]: U:=}-w:- +—W.W +U' (10) ?i W,= ''-H 7'sinh*(/n-i7) »'