Tap chi Khoa hoc va Cong nghe biin T9 (2009) So 1 Tr 22 33 AP DUNG CHI SO CHAT LlTONG NÛ OC CWQI 6 VUNG BIEN VEN BCK DA NANG HO CONG HOA Tom tat Cdc cdch ddnh gid truyen thdng vi chdt luang nuac thud[.]
Tap chi Khoa hoc va Cong nghe biin T9 (2009) So Tr 22 - 33 AP DUNG CHI SO CHAT LlTONG NU^OC CWQI VUNG BIEN VEN BCK DA NANG HO CONG HOA Tom tat Cdc cdch ddnh gid truyen thdng vi chdt luang nuac thudng tong hgp cdc gid tri ciia limg ihong s6 Irong mgt thiiy vuc ndo vd hinh tln'cc bdo cdo theo cdch nhu vdy chi phuc vu cho cdc chuyen gia am hiiu vi linh vuc ndy Trong cdc nhd qudn ly, nhd hoach dinh chinh sdch vd cong ddng mudn biit ldng thi chdt lugng nudc ciia mgt viing ndo thuang gap rdt nhiiu kho khdn day khong phdi Id ITnh vuc chuyen sau ciia hg [6J Viec xdy dung chi s6 chdt luang la hit sice cdn Ihiil vl no cho phep ddnh gid vd bdo cdo theo mgt hinh thiic phu hgp ddi vdi tdt cd ddi tugng diing tin ndl tren md khong cdn phdi am hieu vi chdt lucmg nudc Do do, Robert M Brown (1970) da xdy dung chi sd chdt luang nudc (WQI), vd sau do, cdc nhd khoa hgc Canada da xdy dung thdnh cong chi s6 chdt lugng (CWQI) vdo ndm 2001 Bdi bdo ndy gidl thieu phuang phdp ddnh gid chdt lugng nudc qua viec dp dung chi so CWQI vd nhiing kit qud budc ddu dp dung a viing bien ven ba Dd Ndng I Md DAU Da NSng la mdt phd ldn nhat Viet Nam, la phd cang ldn nhat mien Trung, each phd Hd Chf Minh 764 km ve phfa Nam va Ha Ngi 964 km ve phfa Bac Da Nang cd quan, huyen, gdm: Hai Chau, Thanh Khe, Lien Chieu, San Tra, Ngu Hanh Son, Hda Vang, Cam Le va huyen dao Hoang Sa Bd bien Da Nang dep va trai dai khoang 92 km, cat qua 17 phudng, xa ven bien, noi cd mat dan sd eao Cd he thdng sdng ehinh chay vao vjnh Da Nang la sdng Han va sdng Cu De Sdng Han thude he thdng sdng Vu Gia - Thu Bdn, cd dien tfch luu vuc khoang 5,180 km^, sdng Cu De ed dien tfeh luu vuc nhd hon - 472 km^ [7] Cac hoat dgng kinh te-xa hgi soi dgng d Da Nang da va dang tao nhieu riii ro cho mdi trudng bien ven bd eiia phd Bdi vay, chat lugng nudc bien viing luon dugc cac ca quan mdi trudng Trung uong va dia phuong theo doi, quan trie V4n dd la d cho can cd each danh gia tdng quat va du tin cay ve chat lugng nudc bidn ven bd d day dd cd the phuc vu dugc eac ddi tugng quan tam, tu nha hoach dinh chfnh sach din cdng ddng dan cu ven bien Ap dung chi sd CWQI chat lugng nudc d vung biin ven bd Da Ning da dap ung mgt phan nhu eau ndi tren 22 II TAI LIEU VA PinrONG PHAP Tai lieu Cac du lieu dung dd tfnh toan dugc thu thap tu Tram quan trie mdi trudng bien mien Trung thudc Trung tam Khao sat, Nghien euu va Tu vin Mdi trudng Bien (CMESRC), tu Tram quan trie mdi trudng dia phuong (Sd Tai nguyen va Mdi trudng Da Ning), tu cac du an quan trae eua Da Nang va eac du an khac Tieu chuin su dung dd tfnh toan va danh gia chit lugng nudc bien la TCVN-95 ddi vdi nude bidn ven bd cho muc dfch nudi trdng thuy san, bai tam va muc dfch khac Trudng hgp tieu chuan Viet Nam chua cd, da su dung tieu chuan de xuat cua Du an KT03.07d6 tham khao Chi sd chat lugng nirdc Chi sd chat lugng nudc (WQI - Water Quality Index) dugc tdng hgp tu' cac sd lieu ve chat lugng nudc nham don gian hda mdt sd, qua dd cd cai nhin tdng the ve chat lugng nudc (vf du: tdt, trung binh, d nhiem, ), giup di dang dua len ban dd hoac thdng bao cho cac nha quan ly, nha hoach djnh chfnh sach, edng ddng hieu dugc ma khdng cin cd kidn thiic ehuyen mdn sau Tren ca sd danh trgng sd cua thdng sd: dxy hoa tan (DO), khuan gay benh (fecal califorrm), pH, BOD, bidn ddi nhiet do, tdng phdt (TP), Nitarat (NO3), due va tdng chit rin la lung (TSS), Robert M Brown (1970) da tien hanh xay dung va tinh chi sd WQI theo cdng thuc C2.1 WQI = £wj.qi, i=i (C2.1) Jw>=l Trong Wj la trgng sd thdng sd i; qi la chi sd chat lugng thdng sd i, dugc tinh toan bing each liy ket qua quan trac ddi chieu vdi gia tri q cho san (vf du d hinh 1); n la sd thdng sd Trgng sd ciia cac thdng sd dugc eho theo bang Bang 1: Trgng sd cua cac thdng sd [theo 8] Thong so DO Fecal Coliform pH BOD Trong so 0,17 0,16 0,11 0,11 Bien doi nhiet 0,10 TP N03 Do due TSS 0,10 0,10 0,08 0,07 23 Chi so chdt hcovg ciia TSS ; Chi so chdt luang cua pH ! i ^ " " " • • ^ OO O CIO £50 30O 1I C •! t X l SO »x Chu y: Neu nhu gid tri TSS lan hom 500 ppm, thi q = 20 S T H « 10 -11 1' Chii y: Neu nhu gid tri pH thdp han 2.0 hodc ldn han 12.0 thi q= Hinh 1: Cac yeu td chat lugng nude Kdt qua tfnh toan WQI eho gia trj tu ddn 100, dugc chia cip chat lugng nudc (bang 2) Bang 2: Gia tri WQI va chat lugng nude [theo 8] Tinh trang chat lu-ffng nuo'c T6t (Excellent) WQI 90-100 nhiem (Bad) nhiem nang (Good) Trung binh (Medium) 70-90 50-70 25-50 0-25 Kha (Very bad) Chi sd chat lucmg nude CWQI Mac du su dung ehi sd WQI cua Brown cd the chi dugc tdng thd chat lugng nudc, nhung sd lugng cac thdng sd su dung de tfnh toan rat han chd va kdt qua tfnh toan khdng chi cho ddi tugng su dung eu the, nhu: nudi trdng thuy san, vui chai giai trf, Dd khac phuc, eac nha khoa hgc cua Canada (1995) da nghien cuu va xay dung mgt chi sd chit lugng nudc, dd tit ca thdng sd dugc dua vao tfnh toan bing each so sanh vdi cac tieu chuan ve chat lugng nudc cho mgi muc dfch su dung Ddn nam 2001 chi sd chit lugng nudc CCME WQI (Canadian Council of Ministers of Environement Water Quality Index, viet tat la CWQI) dugc Bg Mdi trudng Canada eho phep su dung nhung du an nghien cuu, cac bao cao hien trang mdi trudng Vd mat toan hgc, chi sd CWQI la mdt ham gdm bidn Fl, F2,F3 (hinh 3), dd: Fl (pham vi - bao nhieu): phan tram thdng sd vugt tieu chuin cho phep: ^,= 24 Sd thdng sd vuot tieu chuan xlOO Tdng sd thdng sd danh gia (C2.2) F2 (tan suat - bao nhieu lin): phin tram sd miu vugt tieu chuan cho phep: „ f So mau vuot tieu chuan I ,„„ /r-i ix Fj = xlOO (C2.3) V Tong so mau ^ F3 (do lech - bao nhieu): ldn muc vugt tieu chuan cho phep (cd gia trj tu 0-100) dugc tfnh toan bing cdng thue C2.4 use (C2.4) F3 = 0.0\nse + 0.0\^ nse - lech ehuan tuang ddi trung binh so vdi tieu chuan va dugc tfnh nhu sau: n ^ddlech (C2.5) use =—; —^ Tong sd mau lechj- lech cua thdng sd i so vdi tieu chuan eho phep, dugc tfnh nhu sau: Neu tieu chan tren thi a Fl lechi ^c.-c^ \ ^o (C2.6) J Neu tieu ehuan dudi thi lechi = ^c.-e ^ V C/ (C2.7) F2 J Hinh 2: Md hinh khai niem ve chi sd CWQI [8] Trong dd: Co la gia tri tieu chuan cho phep; c; la gia trj thdng sd i; neu Co = thi gia tri lechi - ci Gia tri ciia CWQI tfnh theo cdng thue: CWQI = 100- r r—;—— 7\ ^F ;-+F,'+F} 1.732 (C2.6) Chi sd CWQI cd gia tri tu' -100, mdi gia tri ludn the hien dugc chat lugng nudc tai khu vuc nghien ciiu, bang chia diem va phan loai chat lugng nudc dugc the hien d bang 25 Bang 3: Xdp loai chit lugng nuoc theo chi sd CWQI [8] CWQI Dieu kien chat luong nuoc ciia he sinh thai Xip loai 95-100 Tot (excellent): chat luong nuoc dugc bao ve, khong hi de doa hay bj tdn thuong; hien trang chat iuong nuoc rat gan vai he tu' nhien hay cac muc mong rauon (muc dfch su diang) Gia tri dat dugc toan bg cac mau dac, phan tich gin nhu dSu nim giai han cho phep toan bg thai gian A 80-94 Kha (good): chit lugng nuac dugc bao ve voi muc de doa va bi ton thuang khong lan; hien trang chit lugng nuac hiem vugt khoi he tu nhien hay cac muc mong muon B 65-79 Trung binh (fair): chat lugng nuac dugc bao ve nhung doi hi de doa hay bi ton thuang a mii'c thap; hien trang chat lugng nuac doi vugt khoi he tij' nhien hay cac mii'c mong muon C 45-64 Bieu hien nhiem (marginal): chat lugng nuac thuang xuyen bi de doa hay bi ton thuang; hien trang chat lugng nuoc thuang vugt khoi he tu nhien hay cac muc mong muon D 0-44 O nhiem (poor): phan Ion tat ca chat lugng nuac luon bi de doa hay bj ton thuang; hien trang chat lugng nuac thuang xuyen vugt khoi he tu nhien hay cac muc mong muon E III K E T QUA TINH TOAN Sd lieu chit lugng nudc tu 11 tram quan trie dugc thu thap, phan tfch va tinh toan, bao gdm 22 thdng sd: nhiet do, DO, pH, due, NO2-N, NO3-N, NH3-N, PO4-P, SiOz, COD, BOD, T.Coliform, diu, CN', Cu, Zn, Hg, Cd, Pb, As, Fe va tdng hda chit bao ve thuc vat Vj trf cac tram quan trac va phan tfch dugc the hien qua hinh \ ^ ^^ ^M ' Hinh 3: Tram quan trie va phan tich chit lugng nudc 26 Tinh toan vi du cho tram Thanh Binh Vai muc tieu nuoi trdng thiiy sdn: Bang cho thay, ket qua quan trac va phan tich tai tram Thanh Binh, gin cdng thai ciia phd Da Ning nam 2000 Mau the hien gia tri tdng Coliform vugt tieu chuin cho muc dfch nudi trdng thiiy san hon 25 lan; mau vang la gia tri vugt tieu chuin 10 den 25 lan, va mau nau la vugt tieu chuan dudi 25 lan Bang Chit lugng nude tai Thanh Binh cho muc dfch nudi trdng thuy san nam 2000 DO SS NO2 NO3 NH3 PO4 COD BOD Tong coliform DSu Hg Pb mg/l mg/l mg/l mg/l mg/l mg/l mg/l MNP/100ml mg/l mg/l mg/l M• 0,5 M 30 10 1000 0,005 0,05 pH Don vi mg/l TC 5,00 6,5-8,5 50 0,02 T.3 6,6 8,1 9,0 - 0,12 0,16 0,05 12 20000 - - - T.6 6,6 7,7 5,0 0,23 0,12 0,47 0,17 - 40000 0,04 0,0002 0,01 T.9 5,1 8,0 25,0 0,014 0,21 1,05 0,26 3000 0,06 0,0002 0,01 Tu bang cho thay, thdng sd vugt tieu chuan (F|) cho phep ddi vdi muc dfch nudi trdng thuy san tii nam 1994 den 2004 nam khoang 22,2 - 60,00 %, trung binh cd 39,86 % thdng sd vugt tieu chuan Khoang 13,60 - 50,00% sd mau vugt tieu chuan (F2), trung binh la 26,35 % Miic vugt tieu chuan cho phep (F3) nam khoang 31,60 90,30 diem, trung binh la 68,69 diem, gia tri F3 rat eao vi day gan edng thai ciia phd Da Nang vinh Da Nang Bang 4: Ket qua tfnh toan cac thdng sd Fi, F2, F3 tai Thanh Binh Muc dich Khac Nuoi thiiy san Bai tam sir dung Nam Fl F2 F3 Fl F2 F3 Fl F2 F3 1994 60,00 33,30 29,30 60,00 50,00 31,60 60,00 33,30 49,70 1995 33,30 18,20 46,60 22,20 13,60 45,80 22,20 13,60 51,60 1996 50,00 23,90 85,00 54,50 21,40 85,60 36,40 16,70 85,60 1997 52,90 28,20 63,30 43,80 17,50 52,70 43,80 14,30 48,90 1998 53,80 28,60 55,80 58,30 25,00 47,70 33,30 11,10 46,50 40,00 14,70 84,90 20,00 5,90 84,10 1999 45,50 21,10 83,70 2000 42,90 35,10 72,70 38,50 26,50 68,50 23,10 14,70 67,80 2001 35,70 35,70 81,40 46,20 46,20 79,20 23,10 23,10 78,60 2002 25,00 25,00 89,30 25,00 25,00 89,30 25,00 25,00 89,30 2003 25,00 25,00 90,80 25,00 25,00 90,30 25,00 25,00 90,30 2004 25,00 25,00 82,40 25,00 25,00 80,00 25,00 25,00 80,00 27 Hinh gidi thieu kdt qua tfnh toan chi sd chit lugng nuac tai Thanh Binh tix 1994 den 2004 ddi vdi muc dfch su dung khac va chi ring chit lugng nudc nhin chung ed bidu hien d nhidm, ddi liic d nhiem va dang cd chiSu huang giam din, nhien tu nam 2002 den 2004 da cd dau hieu dn djnh va bat diu khdi sic d nam 2004 Gia tri CWQI eho muc dfch nudi trdng thiiy san nam khoang 40,12-69,58 di6m, trung binh 50,04 didm; cho muc dfch bai tam la 41,41-65,30, trung binh 48,88 didm; va cho muc dfch su dung khac, gia tri chat lugng d miie 44,01-66,63 diem, trung binh la 53,40 didm no 100 Excglleiil 90 80 Fair 70 60 SO ra- 40 Poor 20 CWQI _Beaches -m- 10 1994 •V- 199S - 1996 - - 1997 : CWQ!_Aquaculture • & 1998 1999 2000 , 2001 CWQl_Other 2002 „.,., 2003 2004 _y Hinh 4: Chi sd chit lugng nude CWQI tai Thanh Binh Tinh toan chat luong nirdc cho cac vung khac Ciia sdng Han: Hinh gidi thieu kdt qua tfnh toan d vung biSn ciia sdng Han tu 1994 ddn 2004 vdi mgi muc dfch su dung, va cho thiy chiing bidn ddi kha rdng, tu nguong bien gidi d nhiem d6n miic trung binh Ndi each khac, chiing cd thi xiy sir cd su dung mat nudc cho muc dfch nudi trdng thiiy san, bai tim va eac muc dfch khac, mac dii ddi liic chit lugng nudc duge bao ve, nhien phin ldn thdi gian chit lugng nudc d day didu kien bien gidi d nhiim, ddi liic bj de dga va tdn thuong Didu cung phu hgp vdi didu kien thuc td, khu vuc ed su hien dien ciia cang Da Ning, cang ca Thuan Phude va dac biet hai eiia thai ldn cua Da Ning la Thanh Binh va Phii Lde 28 no 100 90 80 70 60 so 40 30 20 •CWQI_Beaches - a - CWQ!_Aquacuiture 10 -fe • CWQI_Other 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 Hinh 5: Chi sd CWQI tai viing eiia sdng Han Viing cira sdng Cu De: Hinh cho ket qua tfnh toan chat lugng nudc tai vung ciia sdng Cu De lu 1994 den 2004 vdi mgi muc dfch sir dung, va chi chat lugng nude phan ldn nam d dieu kien trung binh, nhung tdt hon vdng cua sdng Han Nhu vay, neu su dung mat nudc d day cho cac muc dfch sii' dung la tuong ddi tdt, vi chat lugng nudc ludn duge bao dam, nhung nen than trgng, vi ddi bi tdn thuong Nai day mat dan sd, cac hoat ddng san xuat tai thdi diem phan tich la khdng ldn so vdi luu vuc ciia ciia sdng Han Mac dii vay, nhiing nam gan day, nhieu nha may, eac khu cdng nghiep duge xay dung d day nhu (khu cdng nghiep Lien Chieu, Hda Khanh, ), nen chat lugng nudc cd chieu hudng suy giam r:no 100 Excollcrit 90 80 70 60 50 40 9oo': 30 20 •CWQi_Beaches - • - CWQI_Aquaculture 10 A • CWQI_Other 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 Hinh 6: Chi sd CWQI tai vimg ciia sdng Cu De 29 Viing cua vinh Da Nang Chit lugng nudc tai vimg ciia vjnh Da NSng dugc gioi thieu d hinh 7, tinh toan chit lugng nudc tii- 1997 den 2004 cho cac muc dfch su dung', va nhan thiy chit lugng nudc thdi gian quan trac deu d dieu kien kha, cho mgi muc dich su dung Do vay, neu su dung mat nudc cho nudi trdng thiiy san va tam bien thi kha tdt, bai vi nudc d day ludn dugc bao dam mii'c de dga rat thap; dieu kien chat lugng nuoc hi6m vugt khdi dieu kien tu nhien hoac cac miic mong mudn 110 " "•—*••"*• , „ ^ ™ , » .„- 100 .^ / TO / ™^ ~ ™ ™ » , ^ _—*^'-.«« m- —z::^r-=?- ,>B——-~ so -\ „™ ,.^_„™ ^ E;xciiiit, ' " 'Af' '-~^=:i^ 70 60 50 40 Pool 30 20 ^ CWQI_Beaches 10 ~ iIr CWQI_Aquaculture / CWQLOther 1094 1995 1996 1907 1998 1999 ?000 2001 2002 2003 2004 Hinh 7: Chi sd CWQI tai cua vinh Da Ning Vung bien phia Ddng Theo ket qua tfnh toan dugc gidi thieu tren hinh thi chat lugng nudc tu 1994 den 2004 cho mgi muc dfch su dung ludn khdng dn dinh, bien dgng pham vi rdng, tu bien gidi d nhiem den kha, ddi liic tdt cho muc sii dung khac^ TCr nam 1994 den 2000, chat lugng nudc nhin ehung bidn ddng tii' bien gidi d nhiSm ddn trung binh, va tu 2001 den 2004 chat lugng ed bieu hien tdt len, van khdng dn dinh d miic trung binh va kha^ Thuc te Da Ning da cd du an xay dung he thdng thu gom va xu ly nudc thai thi, ngan khdng cho chay true tiep cac bai bien, cho nen nhung nam gan day, chit lugng nudc dang cd chieu hudng tdt len / Day Id diem quan Irac Qudc gia, cd sd lieu day dii vai tdn sudi Idn/nam, vd nhiiu thong sd nlidl Cdn liru y Id, phdn ton cdc diem quan trdc dieu td diem tdc ddng, nen tap trung vdo nhung nai duac cho Id cd khd ndng dnh hudng nhdt, nen dnh hudng it nhieu den ddnh gid long the Tuy dd sodt vd sic dung cdc phuang phdp Igc sd lieu, tdc gid vdn chua tim duac nguyen nhan tai nam 1997 chi sd chdt lugng nudc tai viing bien phia Dong thdp han trung binh cdc ndm khdc, hy vong se tim dugc nguyen nhdn cdc nghien cTni khdc 30 no 100 ^Exccllcnl 90 so 70 60 50 40 30 20 10 —-9—CWQI_Beaches - • - CWQI_Aquaculture •••-!* CWQI_Other 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 Hinh 8: Chi sd chat lugng CWQI tai vung bien phfa Ddng Da Ning Ket qua tdng hgp gia tri ciia chi sd chat lugng nudc CQWI trung binh tai vung dugc gidi thieu tai hinh no oiiem 100 90 80 70 60 50 40 30 20 10 I Mffi-1: - V" tJ*, r :• Han virvcr i-noi.ith Cu Oe river mouth m CWQi _Beaches Eost ^eo • CWQ!_Aquaculture 8ay mouth CWQI Other Hinh 9: Gia h:i trung binh CWQI tai vung IV KET LUAN Chi sd da kdt hgp dugc nhieu yeu td nhu phan tram sd mau vugt tieu chuan, phan tram thdng sd vugt tieu chuan, mirc vugt tieu chuan, ciing nhu cd the sii dung cac tieu ehuan khac (cac ddi tugng sii dung, eac tieu chuan Qudc gia va vung lanh thd khac nhau) de so sanh va danh gia Til' cac ket qua tinh toan tren ta thay chi sd CWQI da phan anh dugc mdt gia trj tu sd lieu quan trac vdi nhieu thdng sd cd don vi khac nhau, vdi miic d nhiem khac nhau, qua dd chi cho nha quan ly, nha hoach dinh chfnh sach va cdng ddng (nhung ddi tugng 31 khdng ddi hdi phai cd mdt chuyen mdn sau) cung co thg hiiu dugc, cung nhu cd thd khuydn nghj viec su dung mat nude cho cac muc dfch khach Chi sd cung cho phep len ban d nhilm cho mgi thiiy vuc mgt each de dang Tuy nhien, chi sd khdng thd thay the cae bao cao thdng thudng, vi cac thdng sd da bj in diu va a muc nao dd khdng phan anh duge dac diem cung nhu khdng phuc vu dugc cho muc dfch nghien euu sau Tac gia ciing da chia vung de de dang nhan dang ban chit vin dd, chi sd CWQI da chi dugc tinh trang chat lugng nudc tai viing ciia sdng Han la xiu nhit, d bien gidi d nhiem, nai ma nd tiep nhan cac ngudn d nhiem chfnh tii': sdng Han chay ra, cang ca Thuan Phude, cdng thai Thanh Binh va Phii Ldc Chat lugng nude vung bien phfa Ddng tdt hon vung ciia sdng Cu De nhung khdng bang vung ciia vinh Da Nang Dieu la hoan toan phu hgp vdi thuc te TAI LIEU THAM KHAO Hd Cdng Hda, 2005 Danh gia chat lugng nudc vung bien ven bd Da Nang Luan van thac sy, Trudng Dai hgc Khoa hgc tu nhien, Ha Ndi Pham Van Ninh va nnk, 1997, 1998, 1999, 2000, 2001, 2002, 2003 Bao eao kdt qua quan trac nude bien ven bd mien Trung Luu tru tai Cue Bao ve Mdi trudng, Ha Ndi Pham Van Ninh, Nguyen Vu Tuong, Ho Cong Hoa, Pham Thi Minh Hanh, 2000 Data report from marine water quality monitoring in Central Vietnam In Collection of Marine Research Works, 2002, XII spoorted to proceedings of SCOPE Workshop on Land-Ocean Nutrient Fluxes: The Silica Cycle, Nha Trang Vietnam National Standard, 2002 Coastal Water Quality Standard-TCVN 59431995, Ha Noi The Bay Institute Ecological Scorecard, 2003 San Francisco Bay water quality index San Francisco Canadian Council of Ministers of the Environment, 2001 Canadian Environmental Quality Guidelines CCME Water Quality Index 1.0 Technical Report http://www.danangcoastalink.org.vn/ http://www.nsf.org/consumer/just_for_ldds/wqi.asp http://www.water-research.net/watrquallndex/index.htm 10 http://www.ccme.ca Cdc tram quan trdc plidn ldn dugc lua chon d, diim dugc col id cd tliin ndng d nhiim cao, cho nen kit ludn chua phdn dnh dugc chdt lugng nudc a cdc diem du lich, cdc bdt tdm 32 APPLYING CWQI IN COASTAL WATERS OF DA NANG CITY, VIETNAM HO CONG HOA Summary: by-variable, Traditional reports on water quality typically consist of complex and water body-by-water body statistical summaries of value to water quality experts, but may not be meaningful variable- This type of Information is to people who want to know about the state of their local water bodies and for managers and policy makers who require concise information about those water bodies [6] Developing necessary, it gives us an evaluation a water quality Index Is very method allows water quality data to be compiled reported In a consistent manner throughout people jurisdictions and Therefore, In 1970, Brown developed a water quality Index (WQI), and the Canadian scientists developed the Canada water quality index (CWQI) in 2001 This report introduces the evaluation method of water quality by using the CWQI and some Initial results of the CWQI application In coastal water quality of Da Nang Ngdy nhan bdi: 10 - - 2008 Ngudi nhan xet: PGS TS Nguyen Chu Hdi Bia chi: Vien Khoa hgc va Cdng nghe Vi?t Nam 33 ... Excollcrit 90 80 70 60 50 40 9oo'': 30 20 ? ?CWQi_ Beaches - • - CWQI_ Aquaculture 10 A • CWQI_ Other 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 Hinh 6: Chi sd CWQI tai vimg ciia sdng Cu De 29 Viing... so 70 60 50 40 30 20 10 —-9? ?CWQI_ Beaches - • - CWQI_ Aquaculture •••-!* CWQI_ Other 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 Hinh 8: Chi sd chat lugng CWQI tai vung bien phfa Ddng... khai niem ve chi sd CWQI [8] Trong dd: Co la gia tri tieu chuan cho phep; c; la gia trj thdng sd i; neu Co = thi gia tri lechi - ci Gia tri ciia CWQI tfnh theo cdng thue: CWQI = 100- r r—;——