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1BO CO MI TRNG QUC GIA 2012MI TRNG NC MT

CHNG 1

TNG QUAN V NC MT VIT NAM

3BO CO MI TRNG QUC GIA 2012MI TRNG NC MT

1.1. C IM IU KIN T NHIN CC LU VC SNG NC TA

Nc ta c a hnh i ni chim n 3/4 din tch lnh th, tp trung phn ln vng ng Bc, Ty Bc v min Trung, phn din tch cn li l chu th v ng bng ph sa, ch yu l BSH v BSCL. Vit Nam nm trong khu vc nhit i gi ma, mc d lng ma trung bnh nhiu nm trn ton lnh th vo khong 1.940 mm/nm nhng do nh hng ca a hnh i ni, lng ma phn b khng u trn c nc v bin i mnh theo thi gian v ang tc ng ln n tr lng v phn b ti nguyn nc Vit Nam.

Vit Nam c hn 2.360 con sng c chiu di t 10 km tr ln, trong c 109 sng chnh. Ton quc c 16 LVS vi din tch lu vc ln hn 2.500 km2, 10/16 lu vc c din tch trn 10.000 km2. Tng din tch cc LVS trn c nc ln n trn 1.167.000 km2, trong , phn lu vc nm ngoi din tch lnh th chim n 72%.

CHNG 1


Khung 1.1. Cc LVS chnh ca nc ta

Lu vc vi din tch trn 10.000 km2

Bng Giang - K Cng

Hng - Thi Bnh

M

C

Vu Gia - Thu Bn

Ba

Sr Pk (thuc LVS M Cng)

S San

ng Nai

M Cng

Lu vc vi din tch t 2.500 - 10.000 km2

Thch Hn

Gianh

Hng

Tr Khc

Kn

Nhm cc LVS vng ng Nam B

Ngun: Cc Qun l ti nguyn nc, B TN&MT, 2012


4 5BO CO MI TRNG QUC GIA 2012MI TRNG NC MTBO CO MI TRNG QUC GIA 2012

MI TRNG NC MT

Bn ranh gii cc LVS nc ta

Ngun: D n nh gi ngnh nc, Cc Qun l Ti nguyn nc, 2008



MI TRNG NC MT

Min Bc (Vng Ty Bc, ng Bc, ng bng sng Hng)

a hnh min Bc c chia lm 2 khu vc ni vi hng ni khc nhau. Pha Bc sng Hng: ni c dng cnh cung v nghing theo hng Ty Bc - ng Nam. Vng i ni pha Nam sng Hng: hng ni dng di nhng ko di khng lin tc to thnh mt vng cung ni tip nhau, lng quay ra bin v bao quanh di cao nguyn bazan pha Ty.

Min Bc c kh hu nhit i gi ma vi bn ma xun, h, thu, ng r rt. Ma xun bt u t thng 2 cho n gn ht thng 4; vo ma h (thng 4 n thng 9) th nhit ngy kh cao v c ma nhiu. Thng nng nht thng l thng 6; t thng 5 n thng 8 c ma nhiu nht trong nm. Ma thu (thng 9 v 10), ma ng (thng 11 n thng 2 nm sau) vi kh hu lnh v hanh kh.

Do tc ng ca yu t a hnh nn cc LVS min Bc c b mt thp dn, c hnh nan qut, chy theo hng Ty Bc - ng Nam, c th hin thng qua hng chy ca cc dng sng ln. Bn cnh , ch thy vn cc sng cn chu s chi phi ca yu t kh hu vi ma ma n sm lm cho lng nc trong ma ma kh di do, thi gian l ko di do kh nng thot l chm (do cc sng c hnh nan qut, chy tp trung vo mt s dng chnh dn n nc sng b dn lm nc l ln nhanh, xung chm). Cc LVS min Bc cn c mt c im khc bit so vi cc LVS khc trn c nc, l cc sng min Bc thng c h thng iu hai bn t hu, do vy nc sng trong c ma l v ma kit thng chy tp trung trong mt vng nht nh.

Min Trung (Vng Bc Trung B, Duyn hi min Trung)

a hnh min Trung c xu hng thp dn t Ty sang ng. Min Trung c mt sng sui dy c, phn ct thnh nhiu LVS nh nh: C, Vu Gia - Thu Bn, Ba, ngoi ra, cn c LVS Gianh, Thch Hn, Hng, Tr Khc v Kn.

Sng min Trung thng c lng sng hp, dc ln, din tch lu vc nh. Dng chy ca cc sng thng tp trung nhanh, lu lng ln nn vo ma ma l thng gy ngp lt vng h lu (cc khu vc ng bng thp pha ng) lm thit hi n i sng ca ngi dn khu vc v nh hng n s pht trin KT-XH ca cc a phng.

Ty Nguyn

a hnh ca lu vc kh phc tp vi nhng cao nguyn xen k ni cao v ni trung bnh v hng dc chnh thp dn theo hng ng Bc - Ty Nam pha Bc v hng ng Nam - Ty Bc pha Nam.

Kh hu Ty Nguyn chu s chi phi chung ca kh hu nhit i nng m v cao so vi mc nc bin. Ma ma bt u t thng 5 n thng 10, ma kh bt u t thng 11 n thng 4 nm sau vi lng ma chi chim 10 15% lng ma nm. Phn ln cc dng sng ti khu vc Ty Nguyn chy theo hng ng sang Ty (chy t Vit Nam sang Lo). Theo , phn phi dng chy trong nm mang tnh cht ma, ma l bt u t thng 8 n thng 11 vi tng lng l chim khong 70% tng lng nm, ma cn t thng 1 n thng 7 chim khong 30% tng lng nc nm.

ng Nam B

Khu vc ng Nam B bao gm LVS ng Nai v h thng cc LVS nh khc nm vng ven bin. Dng chy mt ti cc sng trong vng ng Nam B c phn chia thnh 2 ma r rt, vi ma l thng chm hn ma ma t 1 n 2 thng v ma kit trng vi ma kh. Hng nm, ma l ko di 6 thng, bt u t thng 6 v kt thc vo thng 11, tuy nhin, thi gian ny khng u tng vng.

Phn thng lu v trung lu ca lu vc h thng sng ng Nai khng b nh hng bi ch triu, ch dng chy nh hng ln bi vic iu tit ca cc h thng cng trnh h cha ln. Phn h lu chu tc ng ca triu,



MI TRNG NC MT

xm nhp mn (ch triu ca khu vc ca sng vng ng Nam B mang tnh cht bn nht triu khng u vi bin triu vo loi ln ca Vit Nam). Do , ch thu vn h lu chu s chi phi vi cc mc khc nhau ca cc yu t nh ch dng chy t thng lu v; ch triu bin ng v cc hot ng khai thc c lin quan n dng chy v hot ng ca dng sng ngay ti h lu.

Xm nhp mn l yu t cn quan tm i vi vng h lu sng ng Nai - Si Gn. Mc xm nhp mn chu nh hng ca lu lng dng chy thng lu v, xm nhp mn tng dn vo cui ma l, t tr s cao nht vo cui ma kit. Cc h cha ln nh Tr An, Du Ting, Thc M,... c xy dng v vn hnh gp phn tng lu lng dng chy cho h lu vo cc thng ma kh.

ng bng sng Cu Long

ng bng sng Cu Long l phn cui cng ca chu th sng M Cng, a hnh vng BSCL thp dn theo 2 hng: t Bc xung Nam v t Ty sang ng. Kh hu vng BSCL mang tnh nhit i, nng, m vi nn nhit cao v n nh theo 2 ma: ma ma v ma kh.

Ma ma t thng 5 n thng 10 (hn 90% lng ma tp trung vo ma ma nh cc thng 9, 10), ma kh t thng 11 n thng 4 nm sau. Theo , ma l BSCL thng ko di khong 6 thng (thng 7 n thng 12) vi din bin kh hin ha vi bin ti Tn Chu, Chu c t 3,5 - 4,0 m v ln xung vi cng sut trung bnh 5 - 7 cm/ngy v cao nht cng chi mc 20 - 30 cm/ngy.

Ch thy vn, thy lc BSCL rt phc tp, theo , cht lng mi trng nc cng a dng theo tng khu vc. Ch ngp mn v qu trnh xm nhp mn BSCL chu s chi phi ca ch bn nht triu khng u ca bin ng nh hng n khong 1,4 - 1,5 triu ha t. Qu trnh chuyn dch c cu sang nui tm nc mn cng lm din bin xm nhp mn gia tng nhanh chng khu vc BSCL.

1.2. C IM TI NGUYN NC MT

V tr a l, c im iu kin t nhin c th nn khong 60% lng nc ca c nc tp trung LVS M Cng, 16% tp trung LVS Hng - Thi Bnh, khong 4% LVS ng Nai, cc LVS ln khc, tng lng nc chi chim phn nh cn li (Biu 1.1).

Biu 1.1. T l phn b ti nguyn nc theo cc LVS

Ngun: Bo co Ti nguyn nc, nhng vn v gii php qun l khai thc, s dng nc, B TN&MT, 2009



MI TRNG NC MT

Tng lng nc mt ca nc ta phn b khng u gia cc ma mt phn l do lng ma phn b khng ng u c v thi gian v khng gian, gy nn l lt thng xuyn v kh hn trong thi gian di. Lng ma thay i theo ma v thi im ma ma, ma kh cc vng l khc nhau. min Bc, ma kh bt u vo thng 11 v thng 12, min Trung v min Nam ma kh bt u mun hn, vo thng 1. Ma kh nc ta ko di t 6 n 9 thng v khc nghit, lng nc trong thi gian ny chi bng khong 20 - 30% lng nc ca c nm. Vo thi im ny, khong mt na trong s 15 LVS chnh b thiu nc - bt thng hoc cc b.

Tng lng nc mt ca cc LVS trn lnh th Vit Nam khong 830 - 840 t m3/nm, nhng chi c khong 310 - 315 t m3 (37%) l nc ni sinh, cn 520 - 525 t m3 (63%) l nc chy t cc nc lng ging vo lnh th Vit

Nam. Chng hn, LVS Hng ngun nc ngoi lai chim 50% tng khi lng nc b mt. Cn LVS M Cng c n 90% tng khi lng nc b mt c ngun gc ngoi lai.

Nu chi xem xt tng lng nc c nm s thy ti nguyn nc ca Vit Nam rt di do. Xt trn tng lu vc, theo tiu chun quc t*1, trong ma kh, chi c 4 lu vc c nc l: M Cng, S San, Vu Gia - Thu Bn v Gianh; 2 lu vc khc l LVS Hng v LVS Ba ngng xp xi mc nc; LVS ng Nam B v ng Nai th vic thiu nc c th thng xuyn hn; LVS Ba gn tin n mc ny; Cc LVS cn li c kh nng thiu nc khng thng xuyn

* Theo Chi s v mc cng thng nc ca Falkenmark. theo ngun cung cp nc: Mc trn 1.700m3/ngi/nm c xem l nc; Trong khong 1.700 - 1.000m3/ngui/nm th c kh nng xy ra thiu nc bt thng hoc cc b; Di 1.000m3/nm th xy ra hin tng khan him nc.

Bng 1.1. Mt s c trng c bn ca cc h thng sng chnh Vit Nam

Ngun: H s ti nguyn nc Quc gia, B TN&MT, 2003; Bo co Ti nguyn nc, nhng vn v gii php qun l khai thc, s dng nc, B TN&MT, 2009

TT H thng sngDin tch lu vc (km2) Tng lng dng chy nm (t m3)

Ngoi nc Trong nc Tng Ngoi nc Trong nc Tng

1 Bng Giang

- K Cng

1.980 11.280 13.260 1,7 7,7 9,4

2 Hng - Thi Bnh 86.660 82.340 169.000 51,8 83,2 135

3 M 10.680 17.720 28.400 3,9 14,1 18

4 C 9.470 17.730 27.200 4 19,5 23,5

5 Thu Bn - 10.350 10.350 - 20,1 20,1

6 Ba - 13.900 13.900 - 9,5 9,5

7 S San - - 11.620 - - 12,9

8 Sr Pk - - 18.265 - - 13,5

9 ng Nai 6.700 33.300 40.000 3,5 33,5 37

10 M Cng 756.000 39.000 795.000 400 75 475



MI TRNG NC MT

hoc cc b (Biu 1.2). Nu xt trn c s tng lng nc trung bnh nm, 2 LVS ng Nai v ng Nam B vi s dn hin ti u c nguy c thiu nc khng thng xuyn hoc thiu nc cc b, LVS M v LVS Kn ang gn vi mc ny.

Vi dn s gn 88 triu ngi, Vit Nam c tng lng nc bnh qun u ngi theo nm t khong 9.560 m3/ngi, thp hn chun 10.000 m3/ngi/nm ca quc gia c ti nguyn nc mc trung bnh theo quan im ca Hip hi Nc quc t (IWRA). Tnh theo lng nc ni sinh th Vit Nam hin mi t khong 4.000 m3/ngi/nm, v n nm 2025 c th b gim xung cn 3.100 m3. c bit, trong trng hp cc quc gia thng ngun khng c s chia s cng bng v s dng hp l ngun nc trn cc dng sng lin quc gia, th Vit Nam chc chn s phi i mt vi nguy c khan him nc, c kh nng s xy ra khng hong nc, e da n s pht trin n nh v kinh t, x hi v an ninh lng thc. Mc nc v lu lng trung bnh cao nht v thp nht trn cc con sng trong giai on t nm 2006 n nay c xu hng gim, iu ny cng minh chng r hn cho cc nhn nh trn (Biu 1.4).

Cc h cha (t nhin v nhn to), p dng v cc cng trnh thy li l mt phn khng th thiu ca cc LVS v thc t cho thy, dng chy ca cc con sng trong lu vc ang c kim sot bi cc h cha v p nc. Theo con s tnh ton, tng dung tch hu ch ca cc h cha ca nc ta vo khong 37 t m3 (chim khong 4,5% ca tng lng nc mt trung bnh nm). Trong , trn 45% nm trong LVS Hng - Thi Bnh, 22% LVS ng Nai v 5 - 7% nm LVS C, LVS Ba v S San. Tnh ring cho LVS ng Nai th dung tch hu ch ca cc h cha chim 23% tng lng nc trung bnh nm ca c lu vc. Trn cc LVS khc lng nc tr bng 20% tng lng nc mt hng nm, trong c 12 LVS mc di 10%.

Biu 1.2. Tc ng ca tr nc v chuyn nc lu vc i vi lng nc ma kh

Ngun: D n nh gi ngnh nc, B TN&MT, nm 2008

Biu 1.3. Din bin lu lng nc trn mt s sng chnh

Ngun: TCTK, 2012



MI TRNG NC MT

H cha thu li - thu in Thc B

Khung 1.2. H thng cc h cha, p, cng trnh thy li trn mt s LVS

LVS Hng - Thi Bnh c 29 h thng thy nng, 900 h cha ln v nh, 1.300 p dng, hng nghn trm bm in ln nh, hng vn cng trnh tiu thy nng;

LVS Hng vi 100 h cha cc loi c xy dng vng trung du, min ni v vng ct;

LVS ng Nai vi 911 cng trnh, trong c 406 h cha, 371 p dng v cng, 134 trm bm v h thng thy li;

LVS M Cng vi k hoch pht trin 15 bc thang thy in, pha h lu c 12 cng trnh ang c xut (phn ln cc cng trnh ny nm pha thng lu, khng thuc lnh th Vit Nam).

Ngun: TCMT tng hp

Khung 1.3. H thng cc h ni thnh Th H Ni v knh rch ti Tp. H Ch Minh

Theo S Giao thng vn ti H Ni, cho n thng 8/2012, trn a bn 9 qun ni thnh H Ni hin c 110 h vi tng din tch hn 1.000 ha, trong , ring din tch H Ty l 526 ha. Chi c vi h c ci to, k xung quanh, tch nc thi v nc ma ring nh Hon Kim, Thin Quang, Kim Lin; vi h ang c ci to nh Vn Chng, Linh Quang... Nhng h cha c ci to, cha tch h thng nc thi v nc ma s l ni gnh chu nc thi sinh hot ca dn c xung quanh cng lng nc thi t hot ng sn xut.

H thng knh rch trong khu vc ni thnh Tp. H Ch Minh c tng chiu di khong 76 km vi 5 tiu lu vc chnh bao gm h thng cc knh: Nhiu Lc - Th Ngh, Tn Ha - L Gm, Tu H - Knh i, Kinh T - Bn Ngh, Tham Lung - Bn Ct - Vm Thut. Theo tnh ton, mt knh rch khu vc cc qun ni thnh hin ang mc rt thp v khng c li cho vic thot nc. ng lu , mt s knh do no vt qu su nhng b rng mt ct b thu hp n hn 50%. Theo thng k hin nay c n 60 - 70% chiu di ca cc tuyn knh rch trong ni thnh ang b nhim nng...

Ngun: TCMT tng hp


MI TRNG NC MT


Nhng nm gn y, do nhiu nguyn nhn, h lu hu ht cc LVS, tnh trng suy gim ngun nc dn ti thiu nc, khan him nc khng cung cp cho sinh hot, sn xut ang din ra ngy mt thng xuyn hn, trn phm vi rng ln hn v ngy cng nghim trng, gy tc ng ln n mi trng sinh thi cc dng sng, gia tng nguy c km bn vng ca tng trng kinh t, xa i gim ngho v pht trin x hi.

Thm vo , ti nguyn nc trn cc LVS Vit Nam ang b suy gim v suy thoi nghim trng do nhu cu dng nc tng cao trong sn xut nng nghip, cng nghip, nui trng thy sn, thy in, lng ngh v do kh nng qun l yu km. Cc h sinh thi rng t nhin duy tr ngun sinh thy t thng ngun cc lu vc cng b suy gim trn din rng do nn ph rng, do canh tc nng, nng - nghip, khai khong v xy dng c s h tng.

Bng 1.2. Cc h cha thy li, thy in quan trng (*)

Thy in sng S San (Kon Tum) x l

(*) Theo Quyt nh s 1879/Q-TTg ngy 13/10/2010 ca Th tng Chnh ph v vic ph duyt danh mc cc h thy li, thy in

trn LVS phi xy dng quy trnh vn hnh lin h cha.Ngun: Cc Qun l Ti nguyn nc,

B TN&MT, 2012

STT Lu vc sng S lng h cha Tn h cha

1 Hng 8 Sn La, Ha Bnh, Thc B, Tuyn Quang, Hui Qung, Bn Cht, Nm Na 3 v Lai Chu

2 M 5 Ca t, Ha Na, Trung Sn, Pa Ma v Hui To

3 C 4 Bn V, Khe B, Bn Mng v Ngn Tri

4 Hng 4 Bnh in, Hng in, T Trch v A Li (trn sng A Sp thuc lu vc sng S Kng)

5 Vu Gia - Thu Bn 6

A Vng, k Mi 4, Sng Tranh 2, Sng Bung 2, Sng Bung 4 v k Mi 1)

6 Tr Khc 2 ak rinh v Nc Trong

7 Kn - H Thanh 3 Vnh Sn A - Vnh Sn B, Bnh nh v Ni Mt

8 Ba 5 Sng Ba H, Sng Hinh, Krng Hnng, Ayun H v cm h An Kh - Kanak

9 S San 5 Ply Krng, Ialy, S San 4, Thng Kon Tum v S San 4A

10 Srpk 6 Bun Tua Srah, Bun Kup, Srpk 3, Srpk 4, c Xuyn v Srpk 7

11 ng Nai 13Du Ting, Tr An, Thc M, n Dng, Hm Thun - a Mi - Cu n, i Ninh, ng Nai 2, ng Nai 3, ng Nai 4, Srok Phu Ming v Phc Ha



MI TRNG NC MT

Xt lng nc vo ma kh th nc ta thuc vo vng phi i mt vi thiu nc, mt s khu vc thuc loi khan him nc. Cha bao gi ti nguyn nc li tr nn qu him nh nhng nm gn y, khi nhu cu nc khng ngng tng ln m nhiu dng sng li b suy thoi, nhim, nc sch ngy mt khan him. Hn hn, thiu nc din ra thng xuyn, nghim trng. An ninh v ngun nc cho thy s pht trin bn vng v bo v mi trng ang khng c bo m nhiu ni, nhiu vng nc ta.

1.3. PHT TRIN KINH T - X HI V SC P I VI MI TRNG NC

1.3.1. Pht trin dn s v qu trnh th ho

Thi gian qua, dn s nc ta khng ngng tng nhanh, cho n ht nm 2011, dn s ton quc ln n 87,8 triu ngi, trong , s dn thnh th ln n 27,9 triu ngi (chim khong 31,8% tng s dn c nc).

Dn s thnh th khng ngng tng theo thi gian, mt dn s nc ta phn b khng ng u gia cc vng a l. Dn s sinh sng tp trung ch yu ti cc thnh ph ln, ni c kinh t pht trin, kh nng tm vic lm gia tng thu nhp v iu kin sng cao hn cc vng khc. Mt dn s cao nht t 3.589 ngi/km2 ti Tp. H Ch Minh, tip theo l Th H Ni vi 2.013 ngi/km2, mt dn s cng cao mt s tinh thuc vng KTT Bc B nh Bc Ninh, Hi Dng, Hi Phng,... (Biu 1.4).

Biu 1.4. Mt dn s cc tnh, thnh ph nm 2011

Ngun: TCTK, 2012

Khung 1.4. H thng cc h cha v kh nng phng l

Chi c 3 LVS c h cha c dung tch phng l, l LVS Hng - Thi Bnh, LVS M v LVS Hng (59%).

- LVS Hng dung tch tr l 16,73 t m3 chng l vi tn sut 1% Sn Ty v gi mc nc l H Ni khng vt qu 13,6 m; trong 38% dung tch ny c s dng cho phng l, 93% pht in.

- LVS M c tng dung tch l 1,25 t m3, 24% cho phng l v 69% cho pht in.

- LVS Hng c tng dung tch l 1.258 t m3, 59% cho phng l v 0% cho pht in.

Cc LVS khc c dung tch h cha s dng pht in gm LVS C (57% dung tch hu ch), LVS Thch Hn (49%), LVS Vu Gia - Thu Bn (67%), LVS Ba (90%), LVS ng Nai (84%), LVS S San (89%), v LVS Sr Pk (48%).

Ngun: TCMT tng hp

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Mt dn s trung bnh ton quc



MI TRNG NC MT

Dn s tp trung ti cc vng c kinh t pht trin, ni tp trung nhiu KCN, nh my, x nghip,... dn n thu nhp v mc sng ca ngi dn cc vng ny cng cao hn cc khu vc khc. Thu nhp ca ngi dn vng ng bng sng Hng v vng ng Nam b cao hn nhiu so vi cc vng cn li (Biu 1.6).

Ngi dn thnh th theo thng k cng c thu nhp thc t cao hn nhiu so vi ngi dn sinh sng nng thn. Nm 2010, nu ngi dn thnh th thu nhp bnh qun 2.130 nghn ng/ngi/thng th ngi dn nng thn chi c thu nhp 1.070 nghn ng/ngi/thng. Qu trnh th ha din ra cng nhanh, mnh th phn ha v thu nhp gia thnh th v nng thn cng khng ngng gia tng.

Khng chi tc ng v mt KT-XH, qu trnh th ha cng l nguyn nhn gy bin ng ngun ti nguyn t, theo , cc sng, h trong cc th ngy mt b thu hp dng chy, thm ch b lp hon ton ly t phc v cho qu trnh pht trin KT-XH, xy dng cc cng trnh giao thng, khu dn c, KCN, nh my, x nghip,...

Biu 1.5. Thu nhp bnh qun u ngi mt thng theo gi thc t chia theo vng

Ngun: TCTK, 2012

Biu 1.6. Thu nhp bnh qun u ngi mt thng theo gi thc t chia theo thnh th, nng thn

Ngun: TCTK, 2012



MI TRNG NC MT

Qu trnh th ha v ang tc ng su sc n cc hot ng KT-XH. Do tc ng ca qu trnh ny, cc on sng chy qua cc khu th, khu dn c tp trung v cc c s sn xut kinh doanh vng ngoi thnh thng xuyn nm trong tnh trng bo ng.

1.3.2. Tng trng kinh t v vic s dng nc

Vit Nam ang trong qu trnh CNH-HH t nc. Tuy nhin, vic khai thc, s dng ti nguyn nc cha hp l v thiu bn vng v ang gy suy gim ti nguyn nc, trong khi hiu qu s dng nc cn thp, tnh trng lng ph trong s dng nc cn ph bin trn phm vi c nc.

Theo con s thng k ca D n nh gi ngnh nc nm 2008, tnh trung bnh trn phm vi ton quc, trn 80% lng nc mt c s dng cho nng nghip, 11% cho nui trng thy sn, 5% cho cng nghip v 3% cho cp nc th. C 3 lu vc, lng nc cho ti chim ti trn 90% tng lng nc s dng (LVS Ba l 96%). Lng nc cho cng nghip chim 14% tng lng nc s dng LVS ng Nai v 11% LVS ng Nam B (gm B Ra - Vng Tu). Lng nc s dng cho thy sn chim 16% LVS M Cng v 26% LVS ng Nam B.

Khung 1.5. Bin ng h thng sng h ti H Ni v Tp. H Ch Minh

H Ni

Vo u th k 19, theo thng k, Th H Ni c 602 h ln nh. Tuy nhin, tri qua thi gian, con s ny gim i ng k. n thng 8/2012, trn a bn 9 qun ni thnh H Ni hin cn 110 h vi tng din tch hn 1.000 ha. th ha l nguyn nhn chnh ca qu trnh ny.

Tp. H Ch Minh

Qu trnh th ha trong vng 14 nm tr li y ti Tp. H ch Minh lm bin mt 47 con knh vi tng din tch 16,4 ha. c bit san lp h Bnh Tin rng 7,4 ha - mt trong nhng h cha nc quan trng nht ca thnh ph. Chi trong vng 8 nm t 2002 - 2009, kh nng cha nc ca h thng h, ao, knh, rch v vng ngp nc trong thnh ph gim gn 10 ln.

Trong vng 17 nm (1989 - 2006), din tch b tng ha trn b mt thnh ph tng t hn 6.000 ha ln 24.500 ha. Vic chuyn i din tch b mt t nhin vn c kh nng thm ti khong 50% lng nc ma thnh b mt th vi tnh trng b tng ha cao chi c kh nng thm khong 13% lng nc ma, tt yu gp phn ng k lm gia tng tnh trng ngp nc Tp. H Ch Minh

Ngun: Bo co ti Hi tho quc t v H H Ni

Khu vc kinh t Nm 2007 Nm 2008 Nm 2009 Nm 2010 Nm 2011

Nng, lm nghip v thy sn 20,34 22,21 20,91 20,58 22,02

Cng nghip v xy dng 41,98 40,35 40,79 41,64 40,79

Dch v 37,68 37,44 38,30 37,78 37,19

Bng 1.3. Tnh hnh tng trng v pht trin ca cc ngnh kinh t

Ngun: TCTK, 2012

n v: %



MI TRNG NC MT

Nm 2011, cc ngnh cng nghip v xy dng ca nc ta ng gp 40,79% gi tr GDP quc gia, ang pht trin nhanh chng trong thi gian qua v s tip tc tng trng trong thi gian ti. Tuy nhin, phn ln cc hot ng cng nghip tp trung mt s vng kinh t gy nn cc vn v mi trng cng nh vn qun l. S pht trin ca cc KCN v lng ngh to nn cc im sn xut v nhim mi v phi tp trung.

Hin nay, khng c s liu thng k v lng nc s dng cho cng nghip ni chung, ngoi tr c th c s liu ca cc nh my ln. Do thiu s liu nn sn lng nc s dng cho cng nghip c tnh da trn tiu chun nc yu cu cho mt n v sn lng cng nghip. Tiu chun cp nc cho hot ng sn xut cng nghip l t 40 - 45 m3/ha/ngy ti 70 m3/ha/ngy (JICA, 2002) v ty theo loi hnh sn xut. V khng c thng tin, s liu nn nh gi da trn din tch t s dng cho sn xut cng nghip v bnh qun lng nc s dng cho tng vng cng nghip tng lu vc sng. Da trn cc nh gi ny, tng sn lng nc s dng cho cng nghip c khong 3.770 triu m3/nm, trong LVS Hng - Thi Bnh chim gn 50% tng lng nc s dng cho ngnh cng nghip c nc; LVS ng Nai s dng 25% lng nc cho sn xut cng nghip; nhm sng ng Nam b l 7% v LVS M Cng l 10%. c bit, t l s dng nc di t cho cng nghip rt ln, ring Tp. H Ch Minh c n 57% doanh nghip s dng nc di t. D bo n nm 2015, khi lng nc s dng trong cng nghip s tng gp i so vi nm 2006, mc tng s ch yu din ra cc LVS vn l ni tp trung cc hot ng sn xut cng nghip l LVS Hng - Thi Bnh, ng Nai, nhm sng ng Nam b, M Cng v Vu Gia - Thu Bn.

Nm 2012, ngnh nng nghip tuy chi ng gp 22,02 % gi tr GDP nhng l ngnh s dng nc ln nht nc ta. Mc d ng gp ca ngnh nng nghip cho GDP quc gia gim so vi ngnh cng nghip nhng vn tip tc tng trng v to ra ngun vic lm ln.

Theo nh gi, nc mt s dng cho ti tiu ln n hn 66.000 triu m3/nm, chim trn 82% tng lng nc s dng c tnh Vit Nam. LVS M Cng v LVS Hng - Thi Bnh chim khong 75% tng s dng nc ti Vit Nam vi mc tng ng ln lt l trn 27% v 45%. LVS M Cng c chi s s dng nc ti trn u ngi nng thn ln nht (trn 2.000 m3/ngi/nm) trong khi hu ht cc lu vc cn li u c con s di 1.000 m3/ngi/nm. hu ht cc lu vc, ngoi tr LVS ng Nai v ng Nam b, s dng nc ti chim ti t nht l 80% tng s dng nc ca lu vc. Tuy vy, din tch thc ti thp hn nhiu so vi din tch thit k (chi t 68% tng din tch c ti), chng t hiu qu s dng nc cho nng nghip cha cao. Vic khai thc cc h cha thy li cng ang gy ra nhiu vn v iu tit nc trn lu vc, cp nc v duy tr dng chy mi trng h lu, v cc cng trnh ny hu ht khng c nhim v thit k x nc xung h lu trong ma cn.

Ngnh dch v v ang tip tc gp vai tr quan trng trong nn kinh t quc dn. Nm 2012, ngnh dch v ng gp 37,17% gi tr GDP quc gia. Tuy nhin, t l ny gim so vi nm 2010 v cc nm trc.

1.3.3. Suy gim cht lng rng

Rng c vai tr quan trng trong vic iu tit ngun nc cho lu vc. Nhng nm gn y, tng din tch rng tng ln, nhng phn ln din tch tng them l rng trng. che ph rng lin tc tng ln, t 27,8% (nm 1990) n 39,5% (nm 2010) (Biu 1.7). Tuy nhin, din tch rng nguyn sinh, rng nhiu tng u b gim st. Hu ht cc vng rng t nhin ang b suy gim nghim trng do nn khai thc rng tri php.

Din tch rng trng - rng mt tng tng cao vi tc gia tng trung bnh t nm 1990 n 2010 cao hn 13 ln tc gia tng ca rng t nhin. Nm 2011, din tch rng trng mi tp trung t 214,7 nghn ha, bng 85,2% so



MI TRNG NC MT

vi cng k nm trc; trong , din tch trng mi rng phng h, c dng t 20,5 nghn ha, bng 33% so vi cng k nm trc; trng mi rng sn xut t 194,3 nghn ha, tng 2,2% so vi cng k nm trc.

Bn cnh vic khai thc thu hoch rng trng theo chu k v mt rng do chy rng cng nh nn ph rng tri php, hng nm, Chnh ph vn cp giy php cho khai thc khong 150.000 m3 g t rng t nhin, cho php chuyn i mc ch s dng rng ngho sang rng trng cao su, trng keo, pht trin thy in... Trc s gim st trm trng v din tch v cht lng rng, cn r sot xem xt li mc thch hp ca vic qun l, bo v v khai thc rng hin nay.

1.3.4. Pht trin thy in

Thy in ng vai tr quan trng trong vic cung cp in cho h thng in quc gia, ng gp cho h thng in quc gia 48,26% cng sut v 43,9% in lng, gp phn khng nh m bo cho cc hot ng sn xut v phc v i sng x hi.

Tnh n ht nm 2012, trn c nc c tng s 1.110 cng trnh v d n thy in c quy hoch, trong c 239 cng trnh vn hnh (chim 21,5% tng s d n, 51,6% tng cng sut cc d n c quy hoch); 217 cng trnh ang thi cng xy dng (chim 19,5% tng s d n, 27,4% tng cng sut); 294 d n ang nghin cu u t v 360 d n cha c ch trng u t hoc cha c nh u t (chim 59% tng s d n, 21% tng cng sut) (B Cng thng, 2012).

Vi h thng sng ngi dy c, nc ta c tim nng thy in kh ln vi tng cng sut khong 35.000 MW v in lng khong 300 t kWh/nm, trong min Bc chim khong 60%, min Trung chim khong 27% v min Nam chim khong 13%. Tuy nhin, tnh ton v mc kh thi, th thc t chi c th khai thc c khong 26.000 MW (khong 100 t kWh/nm), phn b theo cc h thng sng gm: sng 33%, sng ng Nai 13,8%, sng S San

Biu 1.7. Tng din tch rng v che ph rng

hng nm

Ngun: TCTK, 2012

Biu 1.8. Din tch rng b mt do chuyn i s dng v b ph hoi qua cc nm

Ngun: TCTK, 2012

nghn ha



MI TRNG NC MT

10%, sng Vu Gia - Thu Bn 5,2%, sng Srpk 4%, sng L - Gm - Chy 3,8% v cc sng khc 30,2%*1.

Tnh theo khu vc, c th thy rng, khu vc min Bc l ni tp trung kh nhiu cc cng trnh thy in ln nh trn cc LVS. Trong , tnh n nm 2012, cc cng trnh thy in ln nh Sn La, Ha Bnh, Tuyn Quang c tng cng sut t gn 50% cng sut in ton quc theo quy hoch n nm 2020. Khu vc min Trung v Ty nguyn l ni tp trung nhiu cc cng trnh thy in ln nh vi mt cc cng trnh tnh trn chiu di cc con sng l ln nht c nc. Ti khu vc min Nam, cc cng trnh thy in tp trung ch yu trn lu vc h thng sng ng Nai. Cc nh my v d n thy in gn nh lp y 3 dng chnh ca lu vc h thng l sng ng Nai, sng B v sng La Ng.

Biu 1.9. T trng pht trin thy in trong c cu ngnh in giai on 2006 - 2020

Ngun: Bo co ca ngnh in v Tng s in VII, TCMT tng hp, 2012

Nhiu cng trnh thu in trn LVS ng Nai c xy dng

*. Bo co tnh hnh thc hin cc d n thy in trong Quy hoch pht trin in lc quc gia giai on 2011 - 2020 lin quan n vic chuyn i mc ch s dng t rng c dng, rng phng h, Vn quc gia v cng tc qun l, vn hnh khai thc cc h cha thy li, thy in. B Cng thng, 2012.



MI TRNG NC MT

Vic hnh thnh cc h cha ca cc cng trnh thy in trn cc LVS phc v tt cho hot ng nui trng thy sn, ti tiu nng nghip, h tr iu tit nc cho khu vc h lu... Mt s cng trnh thy in c h cha ln bc u pht huy tc dng ct gim l vng h lu nh: thy in i Ninh (sng a Nhim), ng Nai 3, ng Nai 4 (sng ng Nai) phng, chng, ct gim l cho vng h lu ca huyn Ct Tin, Th.

Bn cnh nhng tc ng tch cc, nhng nh hng tiu cc ca cc cng trnh thy in ti hot ng pht trin kinh t - x hi v mi trng t nhin l khng nh.

Tng din tch t c quy hoch v giao cho hn 1.000 d n thy in va v nh l khong 109.569 ha, trong din tch t rng chim khong 32.373 ha. Trong giai on t nm 2006 - 2012, c nc c 160 d n thuc 29 tinh, thnh ph trc thuc trung ng thc hin vic chuyn i mc ch s dng rng sang xy dng thy in vi din tch 19.792 ha. Khu vc chuyn i din tch nhiu nht l Ty Nguyn (41,2% c nc), tip n l vng Bc Trung b (22,9% c nc). Mc d, cc a phng trin khai vic trng mi b sung thay th nhng t l din tch rng trng mi chi t 3,7% tng din tch rng b chuyn i mc ch s dng. Cc a phng c din tch rng b chuyn i ln (trn 1.000 ha) gm c: k Nng, Lai Chu, Lm ng, Gia Lai, Kon Tum, Qung Nam v Ngh An*2. y chnh l mt trong nhng nguyn nhn gy suy thoi a dng sinh hc v cc h sinh thi t nhin.

Vic chuyn dng ca mt s cng trnh thy in sang lu vc khc thiu s xem xt y tc ng mi trng ln lu vc, lm thay i n ch thy vn, gy ra nhng tc ng ln n cc h sinh thi v hot ng pht trin kinh t - x hi trn cc LVS. in hnh c th k n cng trnh chuyn nc t LVS ng Nai sang nhm sng ng Nam b gy ra tnh trng thiu nc cho hot ng pht trin cng nghip v cc nhu cu cp nc th khu vc h lu, c bit l vo ma kh.

Khung 1.6. Tc ng ca cc cng trnh thy in trn LVS Ba v LVS Kn ti

mi trng nc mt

Trn phn thng ngun ca LVS Ba (Gia Lai) c cng trnh thy in Vnh Sn v thy in An Kh - Ka Nak. Cc h cha ca cc cng trnh ny tch nc ca sng Ba v chuyn nc qua cc ng hm, knh dn sang LVS Kn nhm to ct nc ln tng kh nng pht in.

Vic chuyn nc ca cc cng trnh thy in nu trn, nht l sau khi thy in An Kh - Ka Nak tch nc, vn hnh pht sinh mt s vn nh x nc gy l t ngt, bt thng hoc tch nc pht in; c thi im khng x nc xung h du (u nm 2011) gy cn kit dng chy, thiu nc, nhim ngun nc do khng kh nng pha long,... lm nh hng khng nh n i sng, sn xut ca nhiu h dn khu vc ven sng.

Nguyn nhn chnh l do vic chuyn nc ca cng trnh thy in An Kh - Ka Nak cha nh gi y , ton din cc tc ng, nh hng ca vic chuyn nc ra khi lu vc. ng thi, vic tch nc, x nc, vn hnh pht in khng hp l, thiu s phi hp cht ch vi chnh quyn a phng; cha bo m yu cu khai thc, s dng tng hp, a mc tiu ngun nc ca h cha theo quy nh. Ngoi ra, hot ng sn xut, x nc thi cha x l ca mt s doanh nghip ng trn a bn khu vc h du cng trnh lm tng thm tnh trng thiu nc v nhim ngun nc sng Ba on i qua a bn th x An Kh, tinh Gia Lai.

Ngun: Cc Qun l Ti nguyn nc, 2012

*. Bo co chuyn i mc ch s dng rng sang xy dng thy in giai on 2006 - 2012, B NN&PTNT, 2012.



MI TRNG NC MT

Trm thy nng huyn Vnh in, tnh Qung Nam b nhim mn phi ngng hot ng

Ngun: i An

Cng vi , do nhng bt cp trong cng tc qun l xy dng v vn hnh cc cng trnh thy in khin cho hn 90% cng trnh thy in trn c nc cha th m nhn nhim v iu tit l (ct l) vo ma ma v iu tit nc cho vng h lu vo ma kh hn. c bit, vic thiu cc quy nh c th trong xy dng v vn hnh cc h cha thy in v ang gy ra nhng tc ng tiu cc n mi trng nh: lm thay i ch thy vn ca cc sng ngi, lm gim lng nc trong ma kit, lm gia tng tnh trng nhim ti h lu cc con sng, thm ch gy ra nhng nguy c v a chn ng t kch thch...

Bn cnh , vic thay i quy hoch cc bc thang thy in cha xem xt n hiu qu tng th v cp nc, phng l, y mn gy ra nhng nh hng nghim trng n vic khai thc tng hp ngun nc, in hnh nh cc bc thang thy in ng Nai 2 v ng Nai 6. Tnh trng xm nhp mn pha h ngun sng ng Nai ang din bin theo chiu hng xu. Vo nhng thng cao im ma kh, xm nhp mn xm thc su vo t lin, gy nh hng ln ti hot ng cp nc ca mt s nh

my nc t ti Tp. Bin Ha (ng Nai) v nh my nc Th c (Tp. H Ch Minh). Nguyn nhn chnh l do ngun nc pha thng ngun b chn bi cc cng trnh thy in, khng nc cp cho khu vc h lu y ngun mn ra xa khi khu vc.

1.3.5. Khai thc khong sn

Vit Nam c nh gi l quc gia c nhiu tim nng v khong sn vi khong 60 loi, trong nhiu loi c tr lng ln nh b xt, titan, t him vi gi tr kinh t ln, ng gp ca ngnh cng nghip khai khong vo GDP ang ngy cng tng. Theo s liu iu tra, hin nay nc ta c trn 5.000 m v im khai thc khong sn. Mc d h thng php lut v qun l v khai thc khong sn tng i y , tuy nhin vn cn khong cch ln gia quy nh lut php v thc t, v vy hiu qu kinh t ngnh khai thc khong sn cha cao, vn ch yu khai thc, ch bin v xut khu sn phm th, s ch. hu ht cc m khai thc khong sn, cng ngh v k thut khai thc cha c quan tm ng mc, phn ln l khai thc l thin, s dng k thut khai thc c in... Chnh



MI TRNG NC MT

v vy, hot ng khai thc khong sn v ang li nhiu hu qu ln v kh khc phc v mt mi trng, x hi.

Biu hin r nt nht l vic s dng thiu hiu qu cc ngun khong sn t nhin gy tc ng n cnh quan v hnh thi mi trng; tch t hoc pht tn cht thi; lm nh hng n s dng nc, nhim nc, tim n nguy c v dng thi axit m... Nhng hot ng ny ang ph v cn bng iu kin sinh thi.

Ti khu vc min Bc, hot ng khai thc than pht trin mnh. Trong nhng nm gn y, sn lng than gia tng nhanh chng. Nhng km theo , vn t thi v nc thi ti cc m than cng ang l nhng im nng v mi trng. Theo tnh ton, vic sn xut 1 tn than s thi ra t 1-3 m3 nc thi m. Nh vy, vi sn lng khai thc nm 2012 ca ngnh than l hn 42 triu tn th lng nc thi m thi ra mi trng trung bnh khong hn 70 triu m3. y chnh l nguyn nhn khin cho nhiu khu vc ti Mo Kh, Ung B, Cm Ph (Qung Ninh), Na Dng (Lng Sn)... mi trng nc mt b nhim n mc bo ng.

Cng nghip khai khong cng l th mnh ca khu vc min Trung v Ty Nguyn, c bit l khai khong vng gc, vng sa khong v cc loi qung khc. Cc hot ng khai khong khu vc ny ch yu quy m nh. Nguyn nhn do vn u t ca cc doanh nghip ny hn ch, khai thc bng phng php th cng, bn c gii, cng ngh lc hu. Thm vo , thc chp hnh lut php cha cao nn cc ch c s t quan tm n cng tc bo v mi trng, an ton lao ng, bo v ti nguyn khong sn, li nhiu hu qu xu n mi trng. a s cc m ang hot ng hin nay hot ng khng tun th d n, thit k v bo co nh gi tc ng mi trng, hoc bn cam kt c duyt. Chnh v vy, y cng l mt ngun gy nhim mi trng nc mt ti cc vng ln cn.

Mt trong nhng loi vt liu xy dng c khai thc t cc lng sng l ct. Hot ng ny

Khung 1.7. nhim do khai thc ti m than Na Dng (trn sng K Cng) v trn sng Hin,

sng Bng ti Cao Bng

Khu vc khai trng than l thin ca m than Na Dng (Lng Sn) rng hn hng chc nghn m2; trong , lng moong thp hn mt nc bin hng trm mt v lun c lng nc trong moong t 300 - 400 nghn m3. Vo ma ma, bnh qun mi ngy, m phi bm hn 2.800m3 nc t lng moong ra ngoi t nhin. Nc thi m than Na Dng c nng axt cao, c kh nng gy nhim trm trng mi trng nc.

Sng Hin, sng Bng l ngun cung cp nc sinh hot, sn xut cho th x Cao Bng v mt s huyn. Tnh t thi im u nm 2000 n ht thng 3/2012, trn a bn cc huyn: Thch An, Ho An, Nguyn Bnh (Cao Bng) v huyn Ngn Sn (Bc Kn), bnh qun mi ngy c hn 100 my xc, gin tuyn v cc thit b khc, cng vi hng nghn ngi khai thc khong sn c php v khng php.

Ngun: TCMT tng hp, 2012

Khung 1.8. Hot ng khai khong ti khu vc min Trung v Ty Nguyn

Gia Lai

Nh my tuyn qung st Kbang: Kt qu phn

tch mu nc thi (x ln ra mi trng) ngy

04/7/2011 cho thy: c 3/7 chi tiu vt QCCP, c

th: chi tiu mu vt 18 ln, COD vt 3,6 ln

v Cht rn l lng vt 39 ln.

Kon Tum

Dc sng P K thuc a bn x Kroong,

thnh ph Kon Tum, tinh Kon Tum mi ngy cng c

hng trm lt ngi dn x i o i vng tri

php. Dc b sng P K di chng hn 10 km

din ra hot ng khai thc khong sn tri php.

Ngun: Chi cc Bo v mi trng cc tnh Gia Lai, Kon Tum, 2012



MI TRNG NC MT

din ra trn ton b h thng sng sui nc ta tuy nhin, tp trung nhiu nht l cc tinh pha Nam. Ti min Nam c ti 120 khu vc c UBND cc tinh cp php khai thc ct xy dng, khi lng ct khai thc t nhng con sng ln nh ng Nai - Nh B, Si Gn, Vm C ng, sng Tin v sng Hu... k t nm 1990 n nay ln ti 100 triu m3. Hu qu mi trng m cc tinh ny ang phi gnh chu l lm c nc sng, cn tr thuyn b qua li v c bit l gy st l nghim trng cc b sng, nht l sng ng Nai v sng Si Gn v ang st l nghim trng.

Khung 1.9. Cc m, im khai thc khong sn Cao Bng, Bc Kn, Tuyn Quang, H Giang

Cao Bng xc nh c 142 m v im qung vi 22 loi khong sn khc nhau. Nhng m quy m ln vi tr lng v cht lng tt tp trung nhiu cc huyn Tr Lnh, Trng Khnh, H Lang. Trong , qung st c tr lng 50-60 triu tn, mangan 6-7 triu tn, bauxit khong 200 triu tn, ngoi ra cn c vng v thic.

Bc Kn c 165 m v im qung. Cc loi khong sn c tr lng ln bao gm ch, km vi 70 m v im m, tr lng khong 4 triu tn; st c 13 m v im m, tr lng khong 22 triu tn; vng c 17 m v im qung, tr lng khong 39 tn; vi, xi mng 150 triu m3; trng, thch anh khong 460 triu m3; st xi mng trn 10 triu m3; ngoi ra cn c cc khong sn khc nh antimon, titan, kaolin, silic.

Tuyn Quang c khong 200 m v im m, 86 im khong sn thuc 31 loi khong sn c xp thnh 5 nhm, bao gm: khong sn nhin liu (than , than nu), kim loi (st, mangan, ch-km, thic, antimon), khong cht cng nghip (barit, caolanh-fenspat, dolomit), vt liu xy dng ( vi, ct cui si, st gch ngi) v nc nng, nc khong.

H Giang xc nh c 175 m, im m vi 28 loi khong sn. Trong , 4 nhm qung c tr lng ln l ch - km, st, mangan v antimon. Cho n nay, pht hin 7 m, im m cha qung antimon; 19 m, im m st; 15 m, im m ch - km. Trong cc nhm khong sn chnh, c 2 m st thuc qun l ca Chnh ph l Tng B (huyn V Xuyn), Sng Thn (huyn Bc M); 4 m ch - km, 3 m mangan c UBND tinh cho php thu thp thng tin, kho st, nh gi tr lng phc v cng tc cp php khai thc trong tng lai.

Ngun: TCMT tng hp, 2012



MI TRNG NC MT

1.4. BIN I KH HU V TC NG N MI TRNG NC

Bin i kh hu v ang din ra v gy nhng bin ng mnh m thng qua cc hin tng thi tit cc oan, d thng nh nhit tng, bo mnh, ma ln, l lt, hn hn v nc bin dng... Cc biu hin ca bin i kh hu nh tng nhit , gia tng mc nc bin, cng v s t khng kh lnh, bo v cc hin tng thi tit cc oan din ra ngy cng thng xuyn v tr nn ph bin hn.

Suy gim ngun nc cng chu nh hng ca xu th suy thoi do tc ng ca bin i kh hu ton cu. Nhit khng kh c xu th ngy mt tng ln v kch bn c th chp nhn l n nm 2070, nhit cc vng ven bin c kh nng tng thm +1,50C, vng ni a tng +2,00C. Vic ny ko theo lng hi nc bc ln tng khong 7,7% - 8,4%, nhu cu ti tng ln, lng dng chy nc mt s gim i tng ng khi lng ma khng i v thm ch gim. Cn hin tng El-Nino mi khi xut hin cng gn lin vi vic gy hn hn rt nng n nc ta.

Lng ma trung bnh nm c xu hng gim cc vng kh hu pha Bc v tng cc vng kh hu pha Nam. Tnh trung bnh trong c nc, lng ma nm trong 50 nm qua (1958 - 2007) gim khong 2%. Tuy nhin, bin i lng ma c xu hng cc oan: tng trong ma ma v gim trong ma kh. Thm vo , lng ma phn b rt khng u theo thi gian: ma kh v ma ma - ma kh th hn hn, ma ma th ngp ng, theo khng gian - trong mt thi im c vng ang chu l lt li c vng ang thiu nc trm trng thm ch kh hn.

S liu thng k cho thy mc nc mt h du cc cng trnh h cha thy in, thy li trn nhng LVS chnh nc ta, nh sng Hng, ng Nai - Si Gn, Ba, Vu Gia - Thu Bn... ph bin thp hn trung bnh hng nm, c ni thp hn kh nhiu. Ti h lu sng , Thao, L v Hng - Thi Bnh, ngun nc trong 5 nm 2003

- 2007 thp hn trung bnh nhiu nm t 9 - 20% (ti H Ni, thp hn ti 22%, c nm thp hn ti 30%); trong ma kit, ngun nc cn thp hn trung bnh cng k n 50 - 60%. Trn cc LVS khc, ngun nc mt ph bin mc thp hn trung bnh nhiu nm t 15 - 40%, ring cc sng Nam Trung b nh tinh Bnh nh, Bnh Thun, lng dng chy thp hn trung bnh nhiu nm ti 55 - 80%.

Tnh trng suy gim, khan him nc h lu cc dng sng xy ra thng xuyn. S liu iu tra c bn 5 nm gn y 40 trm quan trc cho thy ngun nc ma trung bnh lnh th nc ta khong 585 t m3 (xp xi trung bnh nhiu nm l 592 t m3) v thng tp trung vo mt vi thng ma ma. Tuy nhin, do cc nh hng ca bin i kh hu, trong giai on gn y, ma ma thng kt thc sm hn bnh thng, ma kh thng ko di hn vi hng thng khng ma hoc ma nh khng ng k.

Trong ma kit nhng nm qua, suy gim ngun nc mt din ra kh ph bin cc LVS Hng, Vu Gia - Thu Bn, Tr Khc, Kn, Ba, ng Nai - Si Gn, S San, Srpk... thm ch suy gim ngun nc nghim trng din ra cc h cha thy in Ha Bnh, Thc B, Tuyn Quang, dn ti suy gim mc nc lin tc h lu sng Hng. Hin tng ny lm cho nhiu sng vn kh phong ph ngun nc nay mt dng chy hoc cn n mc cn kit, din ra lin tc trong nhng nm gn y. Sng Hng, sng Thao c nhng thi k di tr y do mc nc gim qu thp, cn kit trong nhiu thng lin tc vo ma kh ca 6 - 7 nm gn y (ti H Ni, mc nc thp nht nm lin tc xung thp, nm sau thp hn nm trc, lp nhng k lc cn kit cha tng thy trong chui s liu quan trc trong gn 110 nm qua). y l hin tng khng bnh thng v v nguyn tc, cc cng trnh h cha u c nhim v b sung ngun nc vo ma kit.

Theo nh gi, hin tng suy gim ngun nc xy ra h lu cc LVS mt phn l do cng


22 PBBO CO MI TRNG QUC GIA 2012MI TRNG NC MTBO CO MI TRNG QUC GIA 2012

MI TRNG NC MT

tc iu tit, vn hnh cc cng trnh thy in, cc p, h cha nc cha m bo. Khan him nc do ngun nc h lu cc sng suy gim cng tc ng mnh ca nc thi khng qua x l gy nhim v qu trnh xm nhp mn gy nh hng ln n vic cp nc sinh hot, cp nc cho sn xut. Theo s liu iu tra, tnh trng suy gim ngun nc dn ti thiu nc, hn hn , ang xy ra trn khng chi mt vi LVS m nhiu nm cn bao trm c vng, min hoc khp c nc.

Kh nng t lm sch ngun nc ph thuc vo nhiu nhn t: quan trng nht l lu lng ca ngun nc, mt thong ngun nc, su ca ngun nc, nhit ,... Mi dng sng, mi on sng c mt kh nng t lm sch khi nhng cht nhim thi vo n. Tuy nhin, do

xy dng cc cng trnh phc v mc tiu pht trin KT-XH (cc h cha, cc cng trnh thy li, thy in,...), vi s iu tit v vn hnh cha hp l, nng lc hot ng ca cng trnh hn ch, cng vi nhu cu dng nc gia tng v tc ng ca bin i kh hu ton cu,... dn n suy gim ngun nc mt. Vn ny cng vi nc thi sinh hot, nc thi ca cc c s sn xut kinh doanh,... khng qua x l x thng ra mi trng l nguyn nhn gy suy thoi v nhim ngun nc cc LVS c bit l cc on sng c cc hot ng KT-XH pht trin nhanh, mnh v h lu cc con sng. Hin trng cht lng nc cc con sng v cc tc ng ca nhim mi trng nc mt, cc bin php , ang v s c s dng gim thiu nhim ngun nc s c phn tch v lm r trong phn sau.

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