Nghien cufu & Trao doi DANH GIA KHA NANG Tl^ LAM SACH CAC SONG CHINH HUYEN CAN GlCf DlTCfl ANH H I / O N G CUA NlTCfC THAI NUOI TOM TS Nguyin Ky Phiing Dai hoc Khoa hoc Tff Nhien Tp HCM TS Nguyin Thi[.]
Nghien cufu & Trao doi DANH GIA KHA NANG Tl^ LAM SACH CAC SONG CHINH HUYEN CAN GlCf DlTCfl ANH H I / O N G CUA NlTCfC THAI NUOI TOM TS Nguyin Ky Phiing - Dai hoc Khoa hoc Tff Nhien Tp HCM TS Nguyin Thi Bay - Dai hoc Bach Khoa Tp HCM Ung dung md hinh lan truyen chd't mot chieu tinh todn qud trinh lan truyen cdc chd't DO, B0D5 tit nUdc thdi nudi tdm cdc sdng chinh dng vdi cdc kich bdn khdc Tii dd ddnh gid khd ndng tif Idm sgch cua cdc sdng chinh Gidi thieu chung Kha nang tiep nhan chat thai ciia mot ddng sdng dffdc hieu la tai Iffdng chat thai cd the dffa vao ddng sdng cho ddng sdng vIn cdn kha nang tff lam sach de dat yeu cau sff dung, nghTa la dat tieu chuan chat Iffdng qui dinh cho muc dich sff dung Kha nang tff lam sach (KNTLS) ciia sdng la kha nang loai bd, giam thieu cac chat d nhilm thdng qua cac qua trinh bie'n ddi vat ly, hda hoc, sinh hoc xay ddng chay Kha nang tff lam sach ciia sdng phu thuoc vao: - Lffu Iffdng nffdc sdng - Van td'c ddng chay - Do sau - Do dd'c - Do ud'n khiic ciia sdng - Thanh phan hda hoc cua nffdc - Nhiet nffdc - Thffc vat nffdc (Aquatic macrophyte): rong reu, beo, cay co v.v -Sif thdng - Thdi gian Kha nang tff lam sach ciia sdng gdm giai doan: (1) Qua trinh xao trdn (hay pha loang) thuan tiiy ly hoc giffa nffdc thai va nffdc sdng (2) Qua trinh Idioang hda cac chat hffu cd chffa nffdc sdng (qua trinh hda ly, sinh hda, sinh hoc) Sif pha loang ndng chat d nhilm thuan ly hoc gdm qua trinh cd ban sau: (i) Chuyen tai: sff van chuyen cac chat ddng chay cua nffdc, (ii) Khuye'ch tan: sff phan tan hay van chuyen cac chat sff xao tron nffdc Hai qua trinh lam cho chat d nhilm dffdc van chuyen xa ngudn thai va lam ndng chat d nhilm giam di Song song vdi sif pha loang ndng do, cac chat d nhilm cd kha nang bi phan hiiy sau vung tie'p nhan nffdc thai bi hap thu, thiiy phan, hoac phan sinh hoc Vi du sd Iffdng vi sinh tff nffdc thai sinh hoat dffa vao ddng sdng se bi giam dieu kien mdi trffdng khdng phii hdp (thay ddi nhiet do, ) Mot sdtac nhan hda hoc (cac chat hiJli cd khdng ben vffng, ammoni, ) tff nffdc thai cung cd the bi chuyen hda cac phan ffng hda hoc Noi dung va phfftfng phap nghien cffu a Ngi dung nghien cdu Ngffdi phan bien: TS Nguyin Kien Dung 40 Tap chi Khi tiTc^ng Thuy van * Thang 5/2008 A' Nghien cihi & Trao doi - Xay dffng md hinh toan tren mang sdng tinh toan lan truyen chat - Ap dung tinh toan lan truyen DO, B0D5 tren mang sdng Can Gid vdi nhieu kich ban khac nhau, tff dd danh gia kha nang tff lam sach cua he thd'ng sd'ng b PhUdngphdp nghien cdu Viec nghien cffu kha nang tie'p nhan tai Iffdng d nhilm va kha nang tff lam sach dang dffdc quan tam nghien cffu chii ye'u dffa vao cac mo hinh toan Cac bffdc chu ye'u tinh toan kha nang tie^p nhan ngudn thai bao gdm: - Xac dinh trffdng van tdc ddng chay (lffu Iffdng ddng chay) bang phffdng phap dac thffc dia hoac qua md hinh tinh toan thiiy life - Xac dinh cac ngudn thai (vi tri, thai Iffdng, ndng thai, ) - Tinh toan phan bd' ndng cac chat d nhilm doc theo sdng va thay ddi theo thdi gian Tren the' gidi cd kha nhieu md hinh tinh toan thiiy life va lan truyen d nhilm tren sdng nhff Qual2E, WASP, dffdc sff dung rat rong rai O Viet Nam cung da cd so' md hinh thiiy life va lan truyen chat dffdc xay dffng nhff HydroGIS, VSAP, De danh gia kha nang giam thieu d nhilm, cai thien mdi trffdng cac bien phap tren, chiing tdi nghien cffu ap dung cac md hinh thuy life va md hinh chat Iffdng nffdc tien tie'n Ke't qua nghien cffu se gdp phan xay dffng cd sd khoa hoc cdng nghe de cai tao mdi trffdng nffdc lffu vffc 1) Md hinh nghien cUu Md hinh gdm module chinh: module thiiy life va module lan truyen chat d nhilm - Module thiiy life: dffdc xay dffng tren cd sd he phffdng trinh Saint -venant, sai phan theo sd dd Upwind trung tam - Module lan truyen chat: sff dung phffdng trinh bao toan vat chat (cac ye'u to'sau: chuyen tai, khuye'ch tan, phan hiiy, lang, ) cho cac cbi tieu mdi trffdng nffdc nhff: DO, BOD, nhiet do, man, cohform, chat ran Id Iffng, 2) Ifng dung tinh todn tren mgng sdng thUc te Phan mem dffdc ffng dung tinh cho mang kenh, sdng huyen Can Gid Trong dd cd tdng so'545 mat cat ngang tren 53 nhanh vdi 59 hdp lffu, va 16 diem thai Khoang each Idn nha't giffa mat cat la 2433 m va nhd nha't la 20 m, bffdc thdi gian tinh (t = 5s) Dieu kien ban dau va dieu kien bien Dieu kien ban dau va dieu kien bien thuy life O thdi diem ban dau (t=0), cho mffc nffdc tTnh z=0 va Q=0 tai tat ca cac mat cat tren mang sdng - Dieu kien bien: Mang song dffdc tinh vdi dau bien Trong dd cd bien tren (trong sdng) d phia Bac va bien dffdi (cffa bien) d phia Nam Dieu Iden ban dau va dieu kien bien truyen chat (J thdi diem ban dau (t=0), gia sff ndng cac ye'u to'can tinh (do man, BOD, DO, ) - Dieu kien bien: Bang Gid tri nong dg tgi cdc diem bien So" hieu nhanh 36 38 39 53 49 51 BiSn BOD (mg/l) 6 13,3 2 2 DO (mg/l) 5,1 5,1 8 - Dieu ki$n tgi diem thai: Cac thdng sd bao gdm vi tri cac diem Tap chi Khi ttf(?ng Thuy van * Thang 5/2008 41 Nghien ciJu & Trao doi thai, thdi gian thai, lffu Iffdng thai va ndng thai Trong bai bao cac ngudn thai chinh la nffdc thai nudi tdm tap trung tai cac Idiu vffc chinh la Binh Khanh, Tam Thdn Hiep, Ly Nhdn, An Thdi Ddng cho ca cac loai hinh nudi: ruong Ilia, ban cdng nghiep, cdng nghiep Khi tang dien tich nudi tdm len 7000ha thi Iffdng nffdc thai tff cac vudng tdm sdng se tang len ã2ãô , 40 ' a ? — *2 "**^ 5fl 48^- 54 49 ^^.>i-^>^n>W^ 169 337 505 673 841 1009 1177 1345 1513 3'" Hinh BOD tgi sdng Long Tau + Nhdn xet ve DO: - Khu vffc Ly Nhdn: Ddi vdi Oxy hda tan (DO) cung cho ta ke't qua tffdng tff ve kha nang pha loang ciia nffdc sdng Rd net nha't la d khu vffc Ly Nhdn (hinh 5,6) Nffdc thai tff cac viing nuoi tdm cd ndng DO tha'p, sau thai song se dffdc pha loang va be mat trao ddi Idn, ndng 44 DO tang len Vdi phffdng an 5000ha, sff thay ddi DO sdngffngvdi moi lan xa thai tffdng tif vdi phffdng an hien trang Va phffdng an 7000 bie'n ddi ndng DO d cac khu vffc nudi tdm tffdng tff vdi phffdng an 5000 ha, khdng cd gi bie'n ddi nhieu Tap chi Khi tifi^ng Thuy van * Thang 5/2008 Nghien ciJu & Trao doi DO tai mat cat nhanh 39 D Otai mat cat 14 nhanh29 ""3" I Hjgnfrang SOOOha — mg/l 7000ha| Hientang ZK^ '^ :C — I — 169 I — I — 337 505 I — 673 I — I — I — I — I —I — 841 1009 1177 1345 1513 gio Hinh DO tgi sdng Soai Rgp Vdi phffdng an hien trang thi DO cQng thay ddi tffdng tff nhff khu vffc Ly Nhdn nhffng khdng rd net bang Nhffng vdi phffdng an 5000ha thi sif thay ddi DO d khu vffc la dang ke sau mdi lan xa thai, nd lam ndng DO giam xud'ng den gan SiBOte 1 r- mg/l sau moi lan nffdc thai tff vudng tdm thai sdng, va sau dd tang len lai xap xi 5mg/l (hinh 7) Va vdi phffdng an 7000 thi mdi lan xa thai DO cd the xudng rat tha'p gan 2mg/l va sau dd tang len lai xap xi 5mg/l DO' fail «i # t e ^ t nh^fi'hi 3'1 DOt^ii m t c a t nhiainih Hifnitr^ng —I 16S 337 505 673 841 1009 1177 1345 1513 gia Hinh DO tgi sdng Soai Rgp - Khu vffc Binh Khanh: mg/l' 7Crj0ha -Pffi?^ -r^ SOOOha TiOilEi! h s - H fSni frgng SOQSHs 7000 hs S T /"'W!i^)»ff)»y^»»i«l^^ _211jk 1S9 337 505 813 841 n03 T177 1345 1513 giio Hinh DO tgi sdng Long Tau - Khu vffc An Thdi Ddng: Vdi phffdng an hien trang thi DO ciing thay ddi tffdng tff nhff khu vffc Ly Nhdn nhffng khdng rd net bang Va cac phffdng an khac thi sff bie'n ddi DO Ididng dang ke Danh gia chung: Bang ket qua tinh toan vdi cac phffdng an khac nhau, bao cao da cho tha'y sff thay ddi ndng nffdc sdng lffu vffc Can Gid sudt vu mua nudi tdm Day la bai toan 169 337 505 673 341 1009 1177 1345 1513 Hinh DO tgi sdng Long Tau md phdng dau tien tff trffdc de'n vdi thdi gian dai nhff vay Qua ket qua tinh toan cho tha'y ndng BOD, DO sdng tai cac khu vffc tiep nhan nffdc thai tff cac vudng nudi tdm thay ddi Idia nhieu sau moi ddt tie^p nhan nffdc thai, sau dd ndng BOD giam dan va DO tang dan pha loang vdi nffdc song va anh hffdng ddng chay Qua cac kich ban nhan tha'y rang kha nang tff lam sach d khu vffc cdn rat Idnffngvdi cac qui hoach SOOOha, 7000ha Tap chi Khi tifgfng Thuy van * Thang 5/2008 45 Nghien ciJu & Trao doi Tai li$u tham khao Bui Lai (Vien Sinh Hoc Nhiet Ddi), Nguyen Thi Kim Lan (Phdn Vien KM Tugng Thuy Vdn Vd Mdi Trudng Phia Nam), Le Thi Quynh Hd (Vien Ca Hoc lfng Dung), "Nghien cdu qud trinh d nhiem hUu cd ao nudi tdm su cdng nghiep" Huynh Thi Minh Hang (2005), Bdo cdo De tdi: "Xdy difng chuang trinh vd tien hdnh quan trac mdi trudnng lUu vifc sdng Sdi Gdn - Dong Nai", Vien Tdi nguyen vd Mdi trUdng Le Thi Sieng vd CTV (2003), Bdo cdo tdm tat: "Nghien cdu dien bien mdi trUdng nUdc hogt ddng nudi tdm tgi cdc tinh Bgc Lieu, Cd Mau dnh hudng tdi mdi trUdng vd de xuat cdc bien phdp khdc phuc ", Vien Khoa Hoc Thuy Lgi Mien Nam Nguyen Vdn Luc (1999), tap bdi gidng "Gidm sdt chd't lugng mdi trudng vd mdt so phuang phdp gidm thieu tdc ddng xa'u hogt ddng nudi tdm", Vien Hdi DUdng Hoc Nha Trang UBND Huyen Can Gid (2005), "Mdt so ddc diem chinh ve dieu kien tU nhien, thuy sinh vdt, ngudn lgi thuy sdn vd phdn vung nudi thuy sdn cua huyen Can Gid" UBND Huyen Cdn Gid (2005), bdo cdo: "Tdng ket ndm ddu tU thdy lgi phuc vu nudi tdm ndm 2000 - 2004 vd ke hogch ndm 2005 -2010" J.A.Cung, F.M.Holly, A.Verway (1980), Practical aspects of computational river hydraulics Pitman Advanced Publishing Program 46 Tap chi Khi tiTtfng Thuy van * Thang 5/2008