Nc mt l nc trong sng, h hoc nc ngt trong vng t ngp nc. Nc mt c b
sung mt cch t nhin bi ging thy v chng mt i khi chy vo i dng, bc hi
v thm xung t.
Ging thy l hin tng nc thot ra khi nhng m my di cc dng lng (ma) v
dng rn (ma tuyt, ma , tuyt), nhm phn bit vi cc hin tng nc tch ra t
khng kh (sng, sng mc, sng bng). N l cch chnh nc kh quyn quay tr li
Tri t. Phn ln lng ging thu l ma.
Phn ln lng nc c ngng t trong cc m my khng ri xung thnh ging thu.
V ging thu xy ra, trc tin nhng git nc nh phi c ngng t. Nhng phn t
nc c th kt hp vi nhau thnh nhng git nc ln hn v nng ri thnh ma. Cn
ti hng triu ht my hnh thnh ch mt ht ma nh.
Lng ging thy ny c thu hi bi cc lu vc, tng lng nc trong h thng ny
ti mt thi im cng ty thuc vo mt s yu t khc. Cc yu t ny nh kh nng cha
ca cc h, vng t ngp nc v cc h cha nhn to, thm ca t bn di cc th cha
nc ny, cc c im ca dng chy mt trong lu vc, thi lng ging thy v tc bc
hi a phng. Tt c cc yu t ny u nh hng n t l mt nc.
2 ti nguyn nc mt ca nc ta tng i phong ph, chim khong 2% tng lng
dng chy ca cc sng trn th gii, trong khi din tch t lin nc ta ch chim
khong 1,35% ca th gii. Tuy nhin, mt c im quan trng ca ti nguyn nc
mt l nhng bin i mnh m theo thi gian (dao ng gia cc nm v phn phi
khng u trong nm) v cn phn b rt khng u gia cc h thng sng v cc
vng.
Ti nguyn nc mt (dng chy sng ngi) ca mt vng lnh th hay mt quc gia
l tng ca lng dng chy sng ngi t ngoi vng chy vo v lng dng chy c sinh
ra trong vng (dng chy ni a).Tng lng dng chy sng ngi trung bnh hng
nm ca nc ta bng khong 847 km3, trong tng lng ngoi vng chy vo l 507
km3 chim 60% v dng chy ni a l 340 km3, chim 40%.Tng lng dng chy nm
ca sng M Kng bng khong 500 km3, chim ti 59% tng lng dng chy nm ca
cc sng trong c nc, sau n h thng sng Hng 126,5 km3 (14,9%), h thng
sng ng Nai 36,3 km3 (4,3%), sng M, C, Thu Bn c tng lng dng chy xp x
nhau, khong trn di 20 km3 (2,3 - 2,6%), cc h thng sng K Cng, Thi
Bnh v sng Ba cng xp x nhau, khong 9 km3 (1%), cc sng cn li l 94,5
km3 (11,1%).Mt c im quan trng na ca ti nguyn nc sng ca nc ta l phn
ln nc sng (khong 60%) li c hnh thnh trn phn lu vc nm nc ngoi, trong
h thng sng M Kng chim nhiu nht (447 km3, 88%). Nu ch xt thnh phn
lng nc sng c hnh thnh trong lnh th nc ta, th h thng sng Hng c tng
lng dng chy ln nht (81,3 km3) chim 23,9%, sau n h thng sng M Kng
(53 km3, 15,6%), h thng sng ng Nai (32,8 km3, 9,6%).l cha xt n kh
nng mt phn ng k lng nc c hnh thnh nc ngoi s b s dng v tiu hao ng k
trong phn lnh th .Hn na, ngun nc sng t nhin trong ma cn li kh nh ch
chim khong 10 - 40% tng lng nc ton nm, thm ch b cn kit v nhim, nn
mc bo m nc trong ma cn nh hn nhiu so vi mc bo m nc trung bnh ton
nm.
63% tng ti nguyn nc mt ca chng ta l ngun nc ngoi lai, tc bt ngun
t cc quc gia khc. Chng hn, lu vc sng Hng ngun nc ngoi lai chim 50%
tng khi lng nc b mt. Cn lu vc sng Cu Long 90% tng khi lng nc b mt c
ngun gc ngoi lai.Ngun nc ni a ch t mc trung bnh km ca th gii 3.600
m3/ngi/nm, t hn mc bnh qun ton cu 4.000 m3 /ngi/nm v thuc din quc
gia thiu nc.
Nc cn cn cho cc hot ng khc ca con ngi nh sn xut cng nghip, nng
nghip v hot ng dch v. Lng nc dng cho trng trt, chn nui rt ln: trung
bnh 1 ha mu cn 0,12 - 0,29 l/s; 1 ha trng la nc cn 1,5 -7 l/s; mi u
vt nui nh nga, tru b tiu tn 20 - 80 lt nc mt ngy, ln: 15 - 60, g,
vt, ngan, ngng: 1 - 1,25 lt. Nhu cu nc cho sn xut cng nghip cng vy:
sn xut 1 tn thp hay 1 tn giy phi dng 44.000 lt nc; lc mt lt du cn
10 lt; sn xut mt lt bia phi c 15 lt nc sch; lng nc dng lm mt my cng
khng nh (ng c t trong: 10 lt /gi, ng c du: 25 - 50 lt/gi...)Nhu cu
dng nc tng ln mnh mCng vi s pht trin kinh t x hi v s gia tng dn s,
nhu cu dng nc cho sinh hot, sn xut cng nng nghip s tng ln mnh m
trong tt c cc vng. Theo kt qu nh gi nm 1999, tng lng nc cn dng ca c
nc chim khong 8,8% tng lng dng chy nm tng ng vi tn sut 75%, tng ln
ti 12,5% vo nm 2000 v 16,5% vo khong nm 2010. Tng lng nc dng ti cho
cy trng kh ln, t 41 km3 (chim 89,8%) nm 1985, tng ln 46,9 km3 (nm
1990) v 60 km3 nm 2000 (chim 85%). Lng nc cn dng trong ma cn rt ln,
nht l lng nc dng cho nng nghip. Tng lng nc cn dng trong ma cn nm
2000 t ti 70,7 km3, chim khong 42,4% tng lng nc c kh nng cung cp
trong ma cn (bao gm nc sng, nc di t v nc do cc h cha iu tit), hay
51% tng lng dng chy ma cn tng ng vi tn sut 75%. Vo khong nm 2010,
tng lng nc cn dng trong ma cn c th ti 90 km3, chim khong 54% tng
lng nc c th cung cp hay 65% tng lng dng chy trong ma cn tng ng vi
tn sut 75%. c bit, khng t vng v lu vc sng, lng nc cn dng c th gp vi
ln tng lng nc c th cung cp, tc l chng nhng vt qu xa ngng lng nc cn
c duy tr sinh thi m cn khng c ngun nc ti ch cung cp cho sinh hot v
sn xut.
Trn phm vi c nc, lng nc cn dng nm 2000 khong 92,116 t m3, vo nm
2010 tng ln khong 121,521 t m3. Lng nc cn dng cho ti, chn nui, thy
sn tng nhanh. Nm 2000, tng lng nc dng cho ti l 76,6x109 m3, chim
84% tng nhu cu dng nc, d bo n nm 2010 s tng ln khong 88,8x109 m3.
Nc s dng trong sinh hot chim t l rt nh, khong 2% tng nhu cu. Lng nc
tiu dng cho sinh hot vo nm 2010 c th tng ln 3,088 t m3.
Vit Nam nm trong vng kh hu nhit i vi b bin di hn 3000km, c nhiu
sng,
rch, ao, h, m, ph v din tch mt nc ni thy rng ln l nhng iu kin
thun
li pht trin ngnh kinh t thy sn. Thc hin chng trnh pht trin nui
trng
thy sn thi k 1999 2010 vi mc tiu m bo an ton thc phm, to vic lm
v
hng ha xut khu. Qua 5 nm thc hin chng trnh, ngh nui trng thy sn
t
c nhiu kt qu quan trng. Din tch nui trng (cha k din tch sng, h
cha,
mt nc bin s dng nui trng thy sn) t khong 902.000 ha, sn lng
nui
trng v khai thc thy sn ni a tng trung bnh 16,1%/nm. Kim ngch xut
khu
thy sn tng nhanh chng t 900 triu USD nm 1999 ln n 2,5 t USD vo
nm 2005
(ngun B Thy sn), gp phn tng trng kinh t t nc. Nui trng thy sn
gp
phn quan trng trong chuyn dch c cu kinh t, m bo an ton thc phm,
to cng
n vic lm, xa i gim ngho v gp phn a ngnh thy sn thc s tr thnh
mt
trong nhng ngnh kinh t mi nhn ca nc ta.
Vit Nam c 708 th bao gm 5 thnh ph trc thuc Trung ng, 86 thnh ph
v th
x thuc tnh, 617 th trn vi 21,59 triu ngi (chim 26,3% dn s tan
quc). Hin
c trn 240 nh my cp nc th vi tng cng sut thit k l 3,42 triu
m3/ngy.
Trong 92 nh my s dng ngun nc mt vi tng cng sut khang 1,95
triu
m3/ngy v 148 nh my s dng ngun nc di t vi tng cng sut khong
1,47
triu m3/ ngy. Mt s a phng khai thc 100% nc di t cung cp cho
sinh
hot sn xut nh H Ni, H Ty, Hng Yn, Vnh Phc, Qung Ngi, Bnh nh,
Sc
Trng, Ph Yn, Bch Liu...; cc tnh thnh Hi PHng, H Nam, Nam nh, Thi
Bnh,
H Tnh, Qung Bnh, KonTum, Gia Lai... khai thc 100% t ngun nc mt;
nhiu a
phng s dng c 2 ngun nc mt v nc di t. Tng cng sut hin c ca cc
nh my cp nc m bo cho mi ngi dn th khong 150 lt nc sch mi
ngy.
Tuy nhin do c s h tn h thng cp nc ti nhiu khu th lc hu, thiu ng
b
nn h thng cp nc khu th cha pht huy ht cng sut, t l tht thot nc
sch
khc cao (c ni t l tht thot ti 40%). Chnh v vy trn thc t nhiu th
cung cp
nc ch t khong 40-50 lt/ngi/ngy.
i vi khu vc nng thn Vit Nam c khong 36,7 triu ngi dn c cp nc
sch
(trn tng s ngi dn 60,44 triu). C 7.257 cng trnh cp nc tp trung
cp nc
sinh hot cho 6,13 triu ngi v trn 2,6 triu cng trnh cp nc nh l
khc. T l dn
s nng thn c cp nc sinh hot ln nht vng Nam B chim 66,7%; ng
bng
sng Hng 65,1%; ng bng sng Cu Long 62,1%.
Ti thnh ph H Ni, tng lng nc di t c khai thc l
1.100.000m3/ngy
m, trong , pha Nam sng Hng khai thc vi lu lng 700.000m3/ngy m.
Trn
a bn H Ni hin nay khong trn 100.000 ging khoan khai thc nc kiu
UNICEF
ca cc h gia nh, hn 200 ging khoan ca cng ty nc sch thnh ph qun l
v
500 ging khoan khai thc nc ca cc trm cp nc sch nng thn.
Cc tnh ven bin min Ty nam B nh Kin Giang, Tr Vinh, Bn Tre, Long
An do
ngun nc ngt trn cc sng rch, ao h khng phc v cho nhu cu ca i
sng
v sn xut v vy ngun nc cung cp ch yu c khai thc t ngun nc di
t.
Khong 80% dn s 4 tnh Tr Vinh, Sc Trng, Bc Liu v C Mau ang s dng
nc
ngm mi ngy. Ti tnh Tr Vinh hin c khong 41.512 ging khoan; TP Ca
Mau hn
90% ngi dn trong x khoan v s dng nc ngm. Vic khai thc nc ngm
q
mc lm tng nc ngm tt gim t 12 n 15m khu vc ny; gip cho tnh Tr
Vinh gn hn vi mt nc bin khong 2-2,5m.
Nc trong sng s dng trong cng nghip yu cu in hnh yu cu cung cp
lng
nc rt ln nhng n khng c tiu th nhiu.
Cc hot ng ca con ngi c th tc ng ln hoc i khi ph v cc yu t ny.
Con ngi thng tng kh nng tr nc bng cch xy dng cc b cha v gim tr nc
bng cch tho kh cc vng t ngp nc. Con ngi cng lm tng lu lng v vn tc
ca dng chy mt cc khu vc lt ng v dn nc bng cc knh.
Tng lng nc ti mt thi im l vn cn quan tm. Mt s i tng s dng nc c
nhu cu nc theo v. V d, trong ma h cn rt nhiu nc phc v cho nng nghip
hoc pht in nhng trong ma ma th khng cn nc, v vy cung cp nc tt cho
ma h th cn mt h thng tr nc trong sut nm v x nc trong mt khong thi
gian ngn. Cc i tng s dng nc khc c nhu cu dng nc thng xuyn nh nh my
in cn ngun nc lm lnh. cung cp nc cho cc nh my in, h thng nc mt ch
cn trong cc b cha khi dng chy trung bnh nh hn nhu cu nc ca nh
my.
Nc mt t nhin c th c tng cng thng qua vic cung cp t cc ngun nc mt
khc bi cc knh hoc ng ng dn nc. Cng c th b cp nhn to t cc ngun khc c
lit k y, tuy nhin, s lng khng ng k. Con ngi c th lm cho ngun nc cn
kit (vi ngha khng th s dng) bi nhim.
Brazil c nh gi l quc gia c ngun cung cp nc ngt ln nht th gii,
sau l Nga v Canada.[4]
Cn kit v nhim ngun nc.Nh trn nu, s gia tng dn s v cc hot ng ca
con ngi s ngy cng tc ng mnh m n mi trng t nhin ni chung v mi trng
nc ni ring. Nhng hot ng t pht, khng c quy hoch ca con ngi nh cht ph
rng ba bi, canh tc nng lm nghip khng hp l v thi cht thi ba bi vo cc
thu vc... v s gy nn nhng hu qu rt nghim trng, lm cho ngun nc b cn
kit, b nhim, hn hn c kh nng cng khc lit. Nguy c thiu nc sch cng trm
trng, nht l vo ma cn cc vng ma t.Tc ng ca bin i kh hu ton cuS bin i
ca kh hu ton cu , ang v s tc ng mnh m n ti nguyn nc. Theo nh gi bc
u, vo khong nm 2070, vi kch bn nhit khng kh tng thm 2,5 - 4,50C,
lng dng chy sng ngi cng s bin i tu theo mc bin i ca lng ma, nu lng
ma gim 10% th dng chy nm c th gim 17 - 53% i vi kch bn nhit khng kh
tng 2,50C v gim 26 - 90% vi kch bn nhit khng kh tng 4,50C. Mc bin i
mnh nht xy ra Nam Trung B v ng Nam B.Ngoi ra, tri t nng ln s lm cho
nc bin c th dng cao thm 0,3 - 1,0 m v do nhiu vng thp ng bng sng Cu
Long, vng ng bng chu th Bc B v ven bin Trung B s b ngp chm trong nc
bin. Nu nc bin dng 1 m, din tch ngp lt l 40.000 km2, ch yu ng bng
sng Cu Long, 1700 km2 vng t ngp nc cng b e do v 17 triu ngi s chu
hu qu ca l lt.Cui cng, s cn kit, nhim ngun nc cng nh s khan him
ngun nc s cng trm trng nu khng c cc bin php qun l tt ti nguyn nc.
Cng v l m ngi ta cho rng, khng hong nc hin nay khng ch do nc qu t
khng tho mn nhu cu ca con ngi m cn do s qun l ngun nc qu km gy nn
hng t ngi v mi trng gnh chu hu qu.Theo bo co ca Lin Hip Quc cng b
ngy 5/3/2003 c tho lun ti din n th gii ln th 3 v nc, t chc ti Kyoto
(Nht Bn) t ngy 16-23/3/2003 cho thy, ngun nc sch ton cu ang cn kit
mt cch ng lo ngi do s bng n dn s, tnh trng nhim mi trng cng vi nhit
tri t nng ln s lm mt i khong 1/3 ngun nc s dng trong 20 nm ti. Hin
nay c khong 12.000 km3 nc sch trn th gii b nhim, hng nm c hn 2,2
triu ngi cht do cc cn bnh c lin quan n ngun nc b nhim v iu kin v
sinh ngho nn.Tm li, khan him v thiu nc l mi e do rt nghim trng i vi
s tn ti ca con ngi trong tng lai. V l , cn c cc gii php qun l, khai
thc v bo v tt ti nguyn nc. Trc ht, cn phi cng c, b sung mng li iu
tra quan trc ti nguyn nc, bao gm c nc mt v nc di t, c lng v cht,
hnh thnh mng li quan trc iu tra ti nguyn nc thng nht trong phm vi c
nc, tin hnh kim k nh gi ti nguyn nc trong cc lu vc sng, cc vng v
ton lnh th. Trn c s kim k nh gi ti nguyn nc v cn bng kinh t nc m xy
dng chin lc, chnh sch pht trin bn vng ti nguyn nc quc gia ni chung
v cho cc lu vc ni ring. Cn thc hin nghim chnh Lut Ti nguyn Nc v y
mnh hot ng ca Hi ng Ti nguyn Nc Quc gia v Ban qun l lu vc cc
sng.
Qun l hiu qu ti nguyn nc
trnh nguy c thiu nc, phi xt n nhng li ch ton cc, qun l tng hp ti
nguyn nc. Cc cp ngnh cn phi hp ng b trong iu tit ngun nc hp l, khng
nn v cc li ch cc b trc mt. Bn cnh , h thng php lut v bo v ti nguyn
nc nc ta cn b lc nhng hn ch, cn phi c sa i, b sung cho ph hp vi yu
cu qun l. Xy dng cc chng trnh, k hoch hnh ng quc gia v qun l, bo v
ti nguyn nc nhm phc v cc yu cu pht trin kinh t, x hi ca t nc.
ng L Vn Ch, Gim c Trung tm nghin cu thu vn v ti nguyn nc cho
rng: Cn c cc h cha nc iu ho dng chy v tch lu nc hiu qu. Ch trng vic
trng rng nhm lu gi ngun nc trn thng lu. Bn cnh , tng cng cng tc
tuyn truyn cho ngi dn s dng tit kim nc. B tr thi v gieo trng hp l.
ng thi c cc gii php nng cao cht lng, bo v ngun nc sch khng b nhim,
cn kit.
Vit Nam c thin nhin u i mt ngun nc mt kh phong ph, nhng v ang i
mt vi nhng thch thc to ln: Nguy c cn kit, nhim ngun nc dn n khan
him nc. Nguy c s cng trm trng nu khng c cc bin php qun l tt.
1. NHIM NC MT:
0. Hin trng nhim nc mt Vit Nam:
Nc mt l ngun ti nguyn quan trng, nc mt c s dng trong hu ht cc
hot ng cng nng - ng nghip, trong sinh hot Vit Nam c h thng sng ngi
dy c vi 2.372 con sng vi chiu di hn 10km, trong c 109 sng chnh v 26
phn lu ca cc sng ln. Trong c 9 con sng (sng Hng, sng Thi Bnh, sng
Bng Giang K Cng, sng M, sng C, sng Vu Gia Thu Bn, sng ng Nai v sng
Cu Long) v 4 nhnh sng (sng , sng L, sng S-San, sng Sre-Pok) c din
tch lu vc ln hn 10.000km2. Ni chung lng nc ca nc ta kh phong ph tuy
nhin mi trng nc ang b nhim do tc ng ca phn ln l con ngi. Nguyn nhn
ch yu l do nc thi ca cc c s sn xut, kinh doanh, cc khu cng nghip,
nc thi sinh hot cha qua x l thi trc tip ra cc dng sng. Do nhim nn
cht lng nc cc con sng ny suy gim mnh, nhiu ch tiu quan trng nh BOD,
COD, DO, NH4, P vt mc tiu chun cho php nhiu ln.
Mc nhim mt s sng ln:
Sng
DO (mg/l)
BOD5 (mg/l)
S. ng Nai (on t h Tr An n hp lu S. Si Gn)
4 6
4 8
S. Si Gn
1,5 5,5
10 30
S. Cu (on nh my giy Hong Vn Th n cu Gia By)
0,4 1,5
>1000
S. y
4,5 6,5
5 6
Bng 1. Mc nhim nc trn mt s sng ln Vit Nam
Qua kt qu iu tra, phn tch v nh gi ca Cc Qun l Ti nguyn Nc, c
5/16 lu vc sng nc ta xp vo loi km nht (b nhim nghim trng, c mu );
nm lu vc sng loi kh v c mu xanh; cn li l trung bnh c mu trng. iu
quan trng l cht lng nc cc lu vc sng ang b suy thoi v tr nn nghim
trng mt s im.
Cc lu vc sng b nhim nghim trng xp theo th t l lu vc ng bng sng
Cu Long, sng Hng - sng Thi Bnh, sng ng Nai, sng Vu Gia - Thu Bn v
lu vc sng C. Cc lu vc sng b nhim nghim trng, c nhiu im nng l sng ng
Nai-Th Vi, sng Tr Khc, sng Hng (c c sng Cu, sng Nhu- sng y).
Hin nay, tnh trng nhim nc ti cc th c biu hin r nht. c bit l H Ni
v thnh ph H Ch Minh. Hu ht hai thnh ph ny cha c h thng x l nc thi
tp trung m trc tip x ra cc ngun tip nhn l sng, h, knh Mt khc, cn rt
nhiu c s sn xut khng x l nc thi, mt s bnh vin v c s y t cha c h
thng x l nc thi; thm vo mt lng rc thi rn ln trong thnh ph, khu th
khng thu gom ht c l nhng ngun quan trng gy ra nhim nc. Hin nay, mc
nhim trong cc knh, sng, h cc thnh ph ln l rt nng. Khng ch H Ni,
thnh ph H Ch Minh m cc th khc nh Hi Phng, Hu, Nng, Nam nh, Hi Dng
nc thi sinh hot cng khng c x l, nhim ngun nc ni tip nhn nc thi u vt
qu tiu chun cho php (TCCP), cc thng s cht l lng (SS), BOD, COD, oxy
ho tan (DO) u vt t 5-10 ln, thm ch c ni vt qu 20 ln TCCP.
V tnh trng nhim nc nng thn v khu vc sn xut nng nghip, hin nay
Vit Nam c gn 70,4% dn s ang sinh sng nng thn l ni c s h tng cn lc
hu, phn ln cc cht thi ca con ngi v gia sc khng c x l nn thm xung t
hoc b ra tri, lm cho tnh trng nhim ngun nc v mt hu c v vi sinh vt
ngy cng cao (theo kt qu tng iu tra dn s nm 2009).
Trong sn xut nng nghip, do lm dng cc loi thuc bo v thc vt, cc
ngun nc sng, h, knh, mng b nhim, nh hng ln n mi trng nc v sc kho
ngi dn. S dng nc cho mc ch sn xut nng nghip i hi mt lng nc ngy cng
tng nguyn nhn l do thm canh, tng v.
Trong nui trng thy sn, do nui trng t, thiu quy hoch, khng tun
theo quy trnh k thut nn gy nhiu tc ng tiu cc ti mi trng nc. Cng vi
vic s dng nhiu v khng ng cch, cc loi ho cht trong nui trng thu sn,
th cc thc n d lng xung y ao, h, lng sng lm cho mi trng nc b nhim cc
cht hu c, lm pht trin mt s loi sinh vt gy bnh v xut hin mt s to c;
thm ch c du hiu xut hin thu triu mt s vng ven bin Vit Nam.
0. Nguyn nhn nhim nc mt Vit Nam:
- Do s gia tng dn s qu nhanh.
- Do khai thc qu mc ti nguyn nc (TNN) v cc ti nguyn lin quan n
nc nh t, rng khin TNN b suy kit.
- Xy dng cc h cha nc: cc h thu in ln khi vn hnh ch nhm phc v cho
pht in cng gy cn kit dng chy cho h lu. Mc nc ca mt s sng, nh sng
Hng nhng nm gn dy xung thp ngoi nguyn nhn suy gim lng ma cn do vic
vn hnh ca cc h Ho Bnh v cc h loi va v ln thng ngun thuc t Trung
Quc.
Vic Trung Quc v s xy dng cc p ln trn thng ngun sng nh p Long M
cao 140m, p Japudu cao 95m, p Gelanta cao 113m vi mc ch chnh l pht
in th ngay c thu in Sn La v Ho Bnh cng b nh hng do ch vn hnh ca cc
h ny v cc p thng ngun sng Cu Long, s gy nh hng ti ch thu vn, cng nh
s bi lng ca ng bng sng Cu Long khng ch gy nh hng ln ti iu kin t
nhin m cn nh hng ti cc mt kinh t - x hi.
- Do cha kim sot c cc ngun thi v cha quan tm u t tho ng cho cc h
thng thu gom, x l cc cht thi lng, thi rn. Tc th ho, cng nghip ho,
lng ngh th cng ngy cng m rng, lng cht thi rn, thi lng cha kim sot c
thi vo ngun nc s gy nhim suy thoi nhanh cc ngun nc mt, nc di t, lm
gia tng tnh trng thiu nc v nhim nc, nht l v ma kh, in hnh nht l sng
Nhu, sng Th Vi
- Do tc ng ca bin i kh hu ton cu. Kh hu ton cu ang nng ln v s tc
ng nhiu n ti nguyn nc. Nhiu d bo trn th gii v trong nc cho thy khi
nhit khng kh tng bnh qun 1,5o th tng lng dng chy c th gim khong 5%.
Ngoi ra, khi tri t nng ln, bng tan nhiu hn s lm nc bin dng cao, mn
s xm nhp su hn nhng vng ng bng thp khin ngun nc ngt phn b trn cc
sng chy ra bin s b thu hp li. Tt c nhng iu s lm suy thoi thm ngun
nc khin khng c ngun nc ngt phc v cho sn xut v sinh hot.
- Do nhng nguyn nhn v qun l:
V t chc: nguyn nhn khch quan l do cn gp nhiu kh khn v t chc qun
l ti nguyn nc, qun l lu vc sng cp B v t chc c hiu lc cp lu vc sng
qun l ti nguyn nc.
V quy hoch: trong thi gian va qua, Nh nc u t nhiu kinh ph cho cc
B, ngnh lm quy hoch. Nhng do ni dung lp quy hoch v s phi hp gia cc
ngnh trn lu vc sng cha gn b, nn quy hoch ca cc ngnh cn nng v khai
thc phc v ring cho chuyn ngnh ca mnh, do vy cn thit cn c quy hoch
tng hp lu vc sng trong c quy hoch bo v ti nguyn nc, quy hoch thot v
x l nc thi, cc cht thi rn cho cc th, khu cng nghip, lng ngh th cng
lm c s cho vic qun l v a quy hoch bo v ny vo k hoch thc hin hng nm
nh l thc hin quy hoch pht trin thu li, thu in, cp nc th, cng
nghip.
Do hot ng sinh hot ca con ngi: n ung, tm ra cc cht thi cha qua x
l c dthi thng ra sng lm nhim ngun nc mt nghim trng.
Do sn xut nng nghip: cc ho cht s dng trong nng nghip nh: phn bn,
thuc tr su c nng dn thi trc tip ra sng lm nhim nc mt.
Do sn xut cng nghip: ha cht, du m cng nghipl nhng cht c, kh phn
hy thi vo sng, h, knh rch lm nhim trc tip ngun nc mt.
Chn nui, thy sn:Cc cht thi chn nui, thc n thacng lm nhim nc
mt.
Do giao thng ng thu, du lch: khi s c trn du, du r r xung sng...
lm nhim bn ngun nc.
Do vi sinh vt: sinh vt c mt trong mi trng nc nhiu dng khc nhau.
Bn cnh cc sinh vt c ch c nhiu nhm sinh vt gy bnh hoc truyn bnh cho
ngi v sinh vt. Trong s ny, ng ch l cc loi vi khun, siu vi khun v k
sinh trng gy bnh nh cc loi k sinh trng bnh t, l, thng hn, st rt,
siu vi khun vim gan B, siu vi khun vim no Nht bn, giun , trng giun
v.v...
Ngun gy nhim sinh hc cho mi trng nc ch yu l rc thi, nc thi sinh
hot, xc cht sinh vt, nc thi cc bnh vin v.v...
0. Hu qu ca nhim nc mt:
Tc hi ca cht hu c:
Lng cht hu c trong nc qu cao s dn n suy gim nng oxy ha tan trong
nc do vi sinh vt s dng oxy ha tan phn hy cc cht hu c. Nng oxy ha
tan thp c kh nng gy nh hng ti s pht trin ca cc sinh vt trong nc,
ngoi ra cn lm gim kh nng t lm sch ca nc.
Tc hi ca cht rn l lng:
Cc cht rn l lng hn ch nh sng chiu ti cc tng nc pha di, gy nh hng
ti qu trnh quang hp ca to, rong ru do cng l tc nhn gy nh hng tiu cc
ti ti nguyn thy sinh.
Cht rn l lng lm tng c ca ngun nc, bi lng dng knh, gy tt cng, nh
hng tiu cc n ti nguyn thy sinh, gy tc hi v mt cm quan.
Tc hi ca cc cht dinh dng (N, P):
S d tha cc chtdinh dng c th dn n s pht trin bng n ca cc loi to,
sau s phn hy cc to li hp th nhiu oxy. Thiu oxy, nhiu thnh phn trong
nc ln men v thi. Ngoi ra, cc loi to ni ln mt nc to thnh lp mng khin
cho bn di thiu nh sng lm cho s quang hp ca cc thc vt tng di b ngng
tr. Nu nng N cao hn 1,0 mg/l v P cao hn 0,01mg/l ti cc dng sng chy
chm l iu kin gy nn hin tng ph dng, gy tc ng xu ti cht lng nc
Tc hi ca kim loi nng:
Kim loi nng l nguyn t c hi i vi cy trng, c kh nng nh hng ti cht
lng nc. Cc kim loi nng khi thi ra mi trng s tch t thng qua chui thc
n, nh hng gin tip ti sc khe con ngi. Kim loi nng khi thi vo cc sng
rch gy nhim ngun nc cp cho sinh hot.
Tc hi ca du m:
Du t nhin liu v du m t ty ra kim loi, sinh hot, khi thi vo ngun
nc s loang trn mt nc to thnh mng du gy cn kit oxy ca nc, mt phn nh
ha tan trong nc hoc tn ti trong nc di dng nh tng.
nhim du dn n kh nng t lm sch ca ngun nc b gim do git cht cc sinh
vt phiu sinh, sinh vt y tham gia vo qu trnh t lm sch. Ngoi ra du
trong nc c tc ng tiu cc n i sng thy sinh v nh hng ti mc ch cp nc
sinh hot, sn xut
Tc hi ca axit:
Nc b nhim axit c th gy tc ng xu n cht lng ngun nc v thy sinh. Nu
nc cha axit chy trn ra xung quanh s nh hng n thc vt nh ho, rng l,
khng pht trin v cht. Ngoi ra, ngun nc b axit ha s gy cn kit ngun
thy sinh, gy n mn cc cng trnh xy dng.
Nhng thch thc trong tng lai
Ti nguyn nc Vit Nam cn c xu th suy thoi do khai thc v s dng thiu
bn vng, chng hn bt ca cc phn lu khai thc cc bi sng trong s dng cho
mc ch nng nghip. Ca sng C L - phn lu t nhin ca sng Hng, b bt kn v
con sng nh tr thnh mt nhnh ca sng Cu, chuyn cha nc ma, nc thi nhim
cc cht hu c, du m. Cc sng nh trong ni ca cc thnh ph b nhim nng do
nc thi sinh hot, cng nghip. Xy dng qu nhiu p dng thy li v s dng ht
lng nc c bn, to ra khc sng kh di p. Cc p thu in to ra khc sng cht
di h lu p, tn ph mi trng thy sinh.S gia tng dn s v s pht trin kinh
t x hi trong th k 21 s lm gia tng mnh nhu cu dng nc v ng thi tc ng
mnh m n ti nguyn nc. Ti nguyn nc (xt c v lng v cht) liu c m bo cho
s pht trin bn vng kinh t x hi trong hin ti v tng lai ca nc ta hay
khng? y l mt vn ln cn c quan tm. Di y xin nu mt s thch thc ch
yu.Trc ht, s gia tng dn s s ko theo s gia tng v nhu cu nc sch cho n
ung v lng nc cn dng cho sn xut. ng thi, tc ng ca con ngi n mi trng
t nhin ni chung v ti nguyn nc ni ring s ngy cng mnh m, c th dn n
nhng hu qu rt nghim trng. nc ta, mc bo m nc trung bnh cho mt ngi
trong mt nm t 12.800 m3/ngi vo nm 1990, gim cn 10.900 m3/ngi vo nm
2000 v c kh nng ch cn khong 8500 m3/ngi vo khong nm 2020. Tuy mc bo
m nc ni trn ca nc ta hin nay ln hn 2,7 ln so vi Chu (3970 m3/ngi) v
1,4 ln so vi th gii (7650 m3/ngi), nhng ngun nc li phn b khng u gia
cc vng. Do , mc bo m nc hin nay ca mt s h thng sng kh nh: 5000
m3/ngi i vi cc h thng sng Hng, Thi Bnh, M v ch t 2980 m3/ngi h thng
sng ng Nai. Theo Hi Nc Quc t (IWRA), nc no c mc bo m nc cho mt ngi
trong mt nm di 4000 m3/ngi th nc thuc loi thiu nc v nu nh hn 2000
m3/ngi th thuc loi him nc. Theo tiu ch ny, nu xt chung cho c nc th
nc ta khng thuc loi thiu nc, nhng khng t vng v lu vc sng hin nay
thuc loi thiu nc v him nc, nh vng ven bin Ninh Thun - Bnh Thun, h
lu sng ng Nai. l cha xt n kh nng mt phn ng k lng nc c hnh thnh nc
ngoi s b s dng v tiu hao ng k trong phn lnh th .Hn na, ngun nc sng
t nhin trong ma cn li kh nh ch chim khong 10 - 40% tng lng nc ton
nm, thm ch b cn kit v nhim, nn mc bo m nc trong ma cn nh hn nhiu so
vi mc bo m nc trung bnh ton nm.
Cn kit v nhim ngun nc.Nh trn nu, s gia tng dn s v cc hot ng ca
con ngi s ngy cng tc ng mnh m n mi trng t nhin ni chung v mi trng
nc ni ring. Nhng hot ng t pht, khng c quy hoch ca con ngi nh cht ph
rng ba bi, canh tc nng lm nghip khng hp l v thi cht thi ba bi vo cc
thu vc... v s gy nn nhng hu qu rt nghim trng, lm cho ngun nc b cn
kit, b nhim, hn hn c kh nng cng khc lit. Nguy c thiu nc sch cng trm
trng, nht l vo ma cn cc vng ma t.Tc ng ca bin i kh hu ton cuS bin i
ca kh hu ton cu , ang v s tc ng mnh m n ti nguyn nc. Theo nh gi bc
u, vo khong nm 2070, vi kch bn nhit khng kh tng thm 2,5 - 4,50C,
lng dng chy sng ngi cng s bin i tu theo mc bin i ca lng ma, nu lng
ma gim 10% th dng chy nm c th gim 17 - 53% i vi kch bn nhit khng kh
tng 2,50C v gim 26 - 90% vi kch bn nhit khng kh tng 4,50C. Mc bin i
mnh nht xy ra Nam Trung B v ng Nam B.Ngoi ra, tri t nng ln s lm cho
nc bin c th dng cao thm 0,3 - 1,0 m v do nhiu vng thp ng bng sng Cu
Long, vng ng bng chu th Bc B v ven bin Trung B s b ngp chm trong nc
bin. Nu nc bin dng 1 m, din tch ngp lt l 40.000 km2, ch yu ng bng
sng Cu Long, 1700 km2 vng t ngp nc cng b e do v 17 triu ngi s chu
hu qu ca l lt.Cui cng, s cn kit, nhim ngun nc cng nh s khan him
ngun nc s cng trm trng nu khng c cc bin php qun l tt ti nguyn nc.
Cng v l m ngi ta cho rng, khng hong nc hin nay khng ch do nc qu t
khng tho mn nhu cu ca con ngi m cn do s qun l ngun nc qu km gy nn
hng t ngi v mi trng gnh chu hu qu.Theo bo co ca Lin Hip Quc cng b
ngy 5/3/2003 c tho lun ti din n th gii ln th 3 v nc, t chc ti Kyoto
(Nht Bn) t ngy 16-23/3/2003 cho thy, ngun nc sch ton cu ang cn kit
mt cch ng lo ngi do s bng n dn s, tnh trng nhim mi trng cng vi nhit
tri t nng ln s lm mt i khong 1/3 ngun nc s dng trong 20 nm ti. Hin
nay c khong 12.000 km3 nc sch trn th gii b nhim, hng nm c hn 2,2
triu ngi cht do cc cn bnh c lin quan n ngun nc b nhim v iu kin v
sinh ngho nn.Tm li, khan him v thiu nc l mi e do rt nghim trng i vi
s tn ti ca con ngi trong tng lai. V l , cn c cc gii php qun l, khai
thc v bo v tt ti nguyn nc. Trc ht, cn phi cng c, b sung mng li iu
tra quan trc ti nguyn nc, bao gm c nc mt v nc di t, c lng v cht,
hnh thnh mng li quan trc iu tra ti nguyn nc thng nht trong phm vi c
nc, tin hnh kim k nh gi ti nguyn nc trong cc lu vc sng, cc vng v
ton lnh th. Trn c s kim k nh gi ti nguyn nc v cn bng kinh t nc m xy
dng chin lc, chnh sch pht trin bn vng ti nguyn nc quc gia ni chung
v cho cc lu vc ni ring. Cn thc hin nghim chnh Lut Ti nguyn Nc v y
mnh hot ng ca Hi ng Ti nguyn Nc Quc gia v Ban qun l lu vc cc
sng.
Nguy c thiu ti nguyn nc mt Vit Nam
S qun l km dn n hng triu ngi phi chu ng thiu nc...
Nguy c thiu ti nguyn nc mt
Cng vi s gia tng dn s v pht trin kinh t x hi, lng nc cn dng cho
cc nhu cu
tng mnh trong tt c cc vng.
Nhn chung, nc ta khng thiu nc, nhng khng t vng v lu vc sng ang
thiu nc v him nc, nh vng duyn hi cc Nam Trung B, h lu sng ng Nai...
S gia tng dn s v cc hot ng ca con ngi s ngy cng tc ng mnh n mi trng
t nhin ni chung v mi trng nc ni ring (dn s tng ln 1 ln, nhu cu nc
tng ln 3 ln). Nhng hot ng ca con ngi nh cht ph rng, canh tc nng lm
nghip khng hp l v x cht thi ba bi vo cc thu vc... gy nn nhng hu qu
rt nghim trng, lm cho ngun nc b cn kit, nhim. Nguy c thiu nc sch
ngy cng trm trng, nht l vo ma cn cc vng ma t gy hn hn khc lit. Theo
nghin cu ca Vin Khoa hc- kh tng thy vn v mi trng, nu cht ph 30% rng
trn lu vc, ngun nc ma cn gim i khong 2-3%.
Lng nc mt t ngoi lnh th chy vo nc ta chim khong 60% tng lng nc
ca cc h thng sng ngi. Do vy, chng ta s chu tc ng mnh m v s gp kh
khn khi cc nc c chung dng sng s dng nc nhiu hoc gy nhim nc u ngun
hay khi iu tit dng chy.
Ti nguyn nc li phn b rt khng u gia cc vng. Trn 60% ngun nc sng
tp trung khu vc BSCL, trong khi ton phn lnh th cn li ch c gn 40%
lng nc nhng li chim ti gn 80% dn s c nc v trn 90% khi lng hot ng sn
xut kinh doanh, dch v. c bit ng Nam B v lu vc ng Nai- Si Gn, lng nc
bnh qun u ngi ch t khong 2.900 m3/ngi/nm, bng 28% so vi mc trung
bnh ca c nc.
Tc tng trng kinh t cao khng i i vi lm tt cng tc bo v mi trng gy
ra nhng nh hng tiu cc ti ti nguyn nc. Hin ti, ngun nc sng ang b
nhim, nht l on chy qua cc th khu cng nghip tp trung, nh sng Cu
Long, sng Hng, Th Vi, sng Si Gn, sng Cm... Bn cnh , hin tng xm nhp
mn t bin vo t lin theo cc dng sng cng ngy cng su, c ni ti 10 n 20
km. Nhng khc sng ni lin vi bin khng cn nc ngt, mn ha ngy mt tng lm
nh hng n sn xutv sinh hot ca c dn quanh vng.
Thc trng khai thc ti nguyn nc Vit Nam08-07-2010
Nc l ti nguyn c bit quan trng, l thnh phn thit yu ca s sng v
mi
trng. Nc khng th thiu cho s tn ti v pht trin ca th gii sinh vt v
nhn
li trn tri t. Nc quyt nh s tn ti, pht trin bn vng ca t nc; mt
khc
nc cng c th gy ra tai ha cho con ngi v mi trng. Ti nguyn nc l
ngun
ti nguyn va hu hn, va v hn.
Hin nay, s suy thoi cc lu vc sng cng vi s gia tng nhim nc khin
cho
ngun nc sch ang ngy mt gim st rt nhanh chng ti nhiu ni. Nc l mt
ti
nguyn c th ti to nhng d b tn thng nu khai thc s dng khng hp l.
v
nc l mt ti nguyn c gi tr kinh t v trong s dng phi ci trng gi tr
kinh t
ca ti nguyn nc.
Tm tt: Ti nguyn nc ca Vit Nam kh ln: lng nc mt sn sinh ni lnh th
l 32,5 t m3 /nm, nu k c lng nc chy t cc quc gia ln cn vo t 889 t
m3/nm, tr lng tim nng nc di t l 48 t m3/nm. Tuy nhin, do nhu cu nc
ca Vit Nam tng mnh t 79,61 t m3/nm vo nm 2000 c th ln n vi trm t
m3/nm vo nhng thp nin u ca th k 21, v nguy c thiu nc biu hin nhiu
vng, k c chu th sng Hng. Trn c s phn tch cc ti liu hin c, cc tc gi
xut hng iu tra, khai thc s dng v bo v ti nguyn nc di t
PHT TRIN V S DNG HP L NGUN TI NGUYN NC.
GSTS Ng nh Tun, Trng i hc Thu li
I. Vit Nam l mt nc c ngun Ti nguyn nc vo loi trung bnh trn th
gii c nhiu yu t khng bn vng.
1. Nc ta c khong 830 t m3 nc mt trong ch c 310 t m3 c to ra do
ma ri trong lnh th Vit Nam chim 37% cn 63% do lng ma ngoi lnh th
chy vo. Tng tr lng tim tng kh nng khai thc nc di t cha k phn hi o c
tnh khong 60 t m3/nm. Tr lng nc giai on tm kim thm d s b mi t khong
8 t m3/nm (khong 13% tng tr lng).
Nu k c nc mt v nc di t trn phm vi lnh th th bnh qun u ngi t 4400
m3/ngi, nm (Th gii 7400m3/ngi, nm). Theo ch tiu nh gi ca Hi Ti
nguyn nc Quc t IWRA th quc gia no di 4000m3/ngi, nm l quc gia thiu
nc. Nh vy, nc ta l mt trong nhng nc ang v s thiu nc trong mt tng
lai rt gn (Thc t nu k c lng nc t cc lnh th nc ngoi chy vo th Vit
Nam trung bnh t khong 10.600m3/ngi, nm).
2. Cc yu t khng bn vng ca Ti nguyn nc Vit Nam.
1) Lng nc sn sinh t ngoi lnh th chim xp x 2/3 tng lng nc c c, rt
kh ch ng, thm ch khng s dng c.
2) S phn b ca c nc mt ln nc di t rt khng u. Theo khng gian, ni c
lng ma nht l Bch M 8000mm/nm, Bc Quang, B N t khong 5000mm/nm,
trong khi Ca Phan R ch t xp x 400mm/nm. Theo thi gian, ma l ch ko
di t 3- 5 thng nhng chim ti 70- 85% lng nc c nm. Ma l, lng ma mt
ngy ln nht t trn 1500mm/ngy song ma cn tn ti hng nhiu thng khng c
git ma no. Ma, l t k lc trong vng ng Nam l ven bin Min Trung. Hn hn
xy ra nghim trng. iu cn phi tch nc trong ma l iu tit b sung ma cn l
gii php tch cc nht, quan trng nht.
3) S khng thun li ca Ti nguyn nc trong s dng v khai thc.
- Nc ta c khong 2360 con sng c chiu di ln hn 10 km. Trong s 13
lu vc sng chnh v nhnh c din tch ln hn 10.000 km2 th c n 10/13 sng c
quan h vi cc nc lng ging, trong c 3/13 sng thng ngun Vit Nam, h
ngun chy sang nc lng ging, 7 sng thng ngun nc lng ging, h ngun Vit
Nam. iu ny Vit Nam khng nhng b rng buc ngun li v nc ca quc gia th
hai, th ba chia s, ng thun.
- Tng lng nc nm ng vi p = 75% khong 720 t m3, tng lng nc ma cn c
khong 170 t m3 (k c 30 t m3 iu tit t cc h cha tnh n nm 2010). Tng
nhu cu nc nm 2010 l 110 t m3, trong ma cn khong 85 t m3 (cha k n lu
lng nc m bo mi trng sinh thi h lu). Nu qun l khng tt th n nm 2010
kh nng thiu nc r rng vo tng ni, tng thi k, c bit l cc vng Ninh
Thun, Bnh Thun, Daklak, Daknng, BSCL, Trung du S. Thi Bnh v sng Hng
v di ven bin.
4) S cn kit ti nguyn nc ngy cng tng.
- Dn s tng, ch s lng nc trn u ngi gim. Nm 1943 l 16.641 m3/ngi,
nu dn s nc ta tng ln 150 triu ngi th ch cn t 2467 m3/ngi, nm xp x
vi nhng quc gia him nc.
- Do cc Quc gia thng ngun khai thc nc cc sng ngy cng nhiu v c
chiu hng bt li. V d: Trung Quc v ang xy dng hn 10 h cha ln trn sng
Mekong, sng Nguyn; Lo v ang xy dng 35 cng trnh thu li- thy in trong
c 27 h cha trn sng nhnh v 8 p dng trn sng chnh. Thi Lan, c 10 h cha
va v ln v ang c k hoch xy thm. Campuchia c d kin gi mc nc Bin H vi
mt cao trnh nht nh pht trin ti
- Nn ph rng ngy mt tng cao trng cph ( khi c gi), ph rng ly g, ly
ci, ly t lm nng ry kh kim sot lm ngun nc v ma cn nhiu sng sui, kh
kit, v ma l lm tng tc xi mn t, tng tnh trm trng ca l lt l cha k hu
qu gy gim st ng k v a dng sinh hc.
- nhim nc ngy mt trm trng do tc th ho, cng nghip ho, hin i ho
ngy mt tng nhanh trong khi nc thi, rc thi cha c kim sot cht ch. l
cha k nhim do s dng ho cht bo v thc vt, phn bn ho hc ngy mt tng kh
kim sot, nhim nc do nc thi, cht thi ca cc ao nui thu sn x trc tip
khng qua x l vo ngun nc.
II. Ti nguyn nc Vit Nam c xu th suy thoi do tc ng ca bin i kh hu
ton cu.
1. Nhit khng kh c xu th ngy mt tng ln c khng nh. Kch bn c th chp
nhn l n nm 2070, cc vng ven bin c kh nng tng thm +1,5oC, vng ni a
+2,5oC. Chng ko theo lng tng bc thot hi ln khong 7,7 8,4%, nhu cu
nc ti tng ln, lng dng chy nc mt s gim i tng ng khi lng ma khng
i.
2. Bo. ElNino v LaNina lm tng thm tnh cc oan ca thi tit. Hu qu
lm tng thm tnh cc oan ca lng dng chy trong nm trn cc dng sng.
1) Vo cc nm LaNina, s lng bo v ATN nh hng n thi tit nc ta nhiu
hn r rt so vi cc nm ElNino. Nu km theo nh hng khng kh lnh th cc nm
ny thng xy ra nhng trn lt ln ko di, din rng.
2) Vo cc nm ElNino, s lng bo v ATN nh hng n nc ta t song cng c
nhng cn c cng rt mnh gy thit hi rt nghim trng.
3) Ni chung Vit Nam bo c xu th ngy cng tng c cng ln tn s. Tn sut
bo b vo vng ven bin pha Bc v ven bin Trung b c xu hng chuyn dch ln
nhau theo tng thi k. Trong nhng nm gn y bo c xu th b vo vng ven bin
Min Trung nhiu hn c bit l vng ven bin Cc Nam Trung B.
3. Hn. ElNino gn lin vi vic gy hn hn rt nng n nc ta. Nhng nm c
ElNino, lng ma v lng dng chy trong sng c bit l trong ma cn thng b
gim mnh, thm ch khng c dng chy nh sng Lng Sng, S. Ly(Bnh Thun), sng
LrongBuk (Daklak), sng H Thanh (Bnh nh) Hn n ni ngay c sc vt cng
khng th sng c, ngi dn phi di chuyn chng n vng khc. Hng chc ngn ha
cy trng b cht do thiu nc.
III. Ti nguyn nc Vit Nam c xu th suy thoi do pht trin v s dng
thiu hp l, thiu ng b.
1. Cc pht trin KTXH c lin quan n pht trin nh knh.
a. S pht trin dn s ko theo s pht trin din tch trng la v sn lng
thc.
Nm 2000 so vi nm 1900: Dn s Vit Nam tng gp 1,6 ln Fla tng gp
2,56 ln, sn lng thc tng 8,2 ln.
b. Ph v trng rng. Nm 1943 che ph l 43%, n nay che ph rng cn t
khong 35% song cht lng rng b gim nng n phn ln l rng th sinh, rng
thoi ho, rng trng.
c. Xy dng h cha thu li, thu in trc nm 1994 c tng dung tch khong
20 t m3 nc, tng dung tch hiu ch khong 16 t m3.
d. S dng nng lng bng than, kh, qu trnh cng nghip, cht thi pht
thi kh nh knh mt t trng ng k.
2. Cc pht trin v s dng Ti nguyn nc thiu hp l, thiu ng b.
a. Bt ca cc phn lu khai thc cc bi sng trong s dng cho mc ch nng
nghip. V d:
1) Nm 1900, bt ca sng C L l phn lu t nhin ca sng Hng- sng C L tr
thnh mt nhnh ca sng Cu- sng cha nc ma, nc thi nhim cc cht hu c, du
m.
2) Nm 1937 bt sng y bng p y, sng y tr thnh khc sng cht (t p y n
Ba Th). Nm 1967, bt ca y bng cng Vn Cc v Ca Ht khai thc bng h t Vn
Cc- p y. Hin nay sng y- sng Nhu tr thnh con sng tiu nc thi, nc bn t
cc th ln H Ni, H Ty, ang ku cu.
b. Cc sng nh trong ni ca cc Thnh ph b nhim nng do nc thi sinh
hot, cng nghip.
1) Sui Phng Hong chy trong Thnh ph Thi Nguyn, b nhim cht hu c
nghim trng do nc thi ca nh my sn xut Giy thi trc tip.
2) Cc sng T Lch, sng St, Kim Ngu chy trong ni thnh H Ni b nhim
rt nghim trng trc tip vo sng Nhu.
3) Cc knh nhiu Lc- Th Ngh knh Tu H, knh Tn Ho- L Gm, Knh Tham
Lng, Knh i- T v cc knh rch khc chy trong ni Thnh ph H Ch Minh trc
tip vo sng Si Gn gy nhim nghim trng.
c. Cc sng ni chung c th phn on nhim khi sng chy qua cc khu th,
khu cng nghip, lng ngh, hay hot ng nng nghip
d. Xy dng p dng s dng ht lng nc c bn to ra khc sng kh di p.
1) Cc p dng thu li nh p Thch Nham trn sng Tr Khc, p Li Giang trn
sng i Giang, p ng Cam trn sng Rng, p Nha Trinh- Lm Cm trn sng Ci
Nha Trang 30 nm trc y v ma kh vn c nc trn qua p. Vi chc nm gn y do
tng din tch ti, tng lng nc cp cho sinh hot, cng nghip, mt khc do
rng u ngun b ph nng n nn ma kh l h lu ht nc c nm ko di vi ba thng
nu khng c ma- vng h lu cc p dng ny nhiu c dn sinh sng ven sng v trn
sng, tc ng ny l rt ng k.
2) Cc p dng thu in:
- To ra khc sng cht on gia h lu p v nh my. Tuy dn c vng ny tha
tht song i vi a dng sinh hc, h sinh thi thu sinh, s tn tht khng th
khng xt n.
- Do iu tit ngy m to ra na ngy h lu khng c nc x. nh hng ny l ng
k khng nhng n hot ng kinh t x hi lin quan n ng thu m ngay c i vi cc
hot ng ca ng vt, thc vt c lin quan n nc.
e. Trong qui hoch, thit k cc h cha nc, trong mt thi gian di khng
quan tm n hoc quan tm khng y n dng chy mi trng pha h lu p nn gy
nhng khiu t ca ngi dn, nhiu a phng khng ng c.
g. Khai thc nc qu mc, thiu qui hoch, k hoch ng b.
1) Khai thc nc ngm qu mc gy nhim trm trng Daklak, Ninh Thun v
Bnh Thun, i hi phi c bin php b cp.
2) Theo qui hoch v ngun nc, n nm 2010 p ng yu cu cp nc ti cho 5
tnh Ty Nguyn l 80.000 ha cph. n nm 2000 ring tnh Daklak (c) trng c
260.000 ha cph. Hu qu l khng nc ti hng chc ngn ha cph b cht.
h. Qun l ti nguyn nc b phn tn, tnh rng buc khng cht ch, thiu
thng nht nn xy ra tnh trng:
- Thiu nc nhn to do khng c qui trnh vn hnh h v ma cn (nc sng Hng
khng p ng yu cu mc nc cn thit trong cc thng II, III hng nm).
- Thiu tp trung, thiu nghim lnh, nhiu c quan ban hnh nhng khng c
c quan no quyt nh. V d: Trn sng Krong Ana on cu Giang Sn, Trm Thu
vn Giang Sn c 3 qui nh ca 3 B: B giao thng, B Ti nguyn v Mi trng, B
Nng nghip v Pht trin Nng thn vi ba bin cm cng c 1 iu cm: Cm ly ct
trn on sng. Thc t khng c chp hnh: Trc cu vn b xi, tu thuyn vn u kn
khai thc ct gy xi l b sng, lm sai lch s liu quan trc thu vn.
IV. Cc gii php pht trin v s dng hp l ngun Ti nguyn nc Vit Nam
hay Cc gii php pht trin bn vng Ti nguyn nc Vit Nam.
c. Ci thin, nng cp v m rng cc h thng thot l, tiu ng.
1) Nng cp cc h thng c.
2) Qui hoch xy dng b sung h thng mi, c lp vi ti, cp nc.
3) Thc hin nghim chnh cc Lut Ti nguyn nc, Bo v mi trng, iubo m
thot l, bo v b sng, chnh tr lng sng, ca sng thng thot l
d. Nng cp bin, ca sng.
e. Cng c bi trc sng m bo an ton vi mc nc thit k qui nh.
g. Khai thc hp l t ai cha s dng.
h. Thc hin c ch sn xut sch.
2. Hn ch v gim thiu suy thoi Ti nguyn nc do Pht trin, s dng Ti
nguyn nc khng hp l.
a. Gim nhu cu nc.
1) Ti tit kim nc.
2) Gim tn tht nc:
- Cng ho knh mng
- Nng cp cng trnh u mi
- Nng cao hiu qu qun l
* Qun l theo nhu cu dng nc khng phi qun l theo kh nng cng
trnh.
* To iu kin thun li cho s tham gia qun l ca x hi, cng dn v cng
ng.
* Tng cng nng lc qun l.
3) Chuyn i c cu cy trng vt nui c nhu cu s dng nc thp.
4) Phng chng nhim nc.
b. Cng nghip.
1) Nng cao hiu qu ti s dng nc.
2) Xy dng h thng x l nc thi.
3) Phng chng nhim ngun nc.
c. Du lch- Dch v- Sinh hot.
1) S dng nc tit kim chng lng ph.
2) Gim nhu cu nc mt cch hp l, ci tin thit b s dng nc.
3) Phng chng nhim ngun nc.
d. Khai thc s dng ngun nc i i vi bo v ngun nc, bo m duy tr dng
chy mi trng cho con sng kho mnh bo v v pht trin h sinh thi thu
sinh. Php l ho ni dung m bo dng chy mi trng trong qui hoch, thit k
vn hnh cc h cha nc thu li, thu in v p dng. C k hoch bin php b cp nc
ngm nhng vng khai thc qu mc, phng chng hoang mc ho.
e. u t nghin cu kim k nh gi v qui hoch d bo di hn Ti nguyn nc. D
bo theo ma, nm v nhiu nm v ngun nc, thin tai l lt, hn hn i km vi
hin tng LaNina, ElNino c k hoch s dng hp l v an ton ngun nc.
g. Qun l tng hp Ti nguyn nc. T chc Lu vc sng c c ch qun l thch
hp, hiu qu.
h. Bo v mi trng nc, phng chng v gim thiu nhim nc, thc hin ng cc
Lut v cc vn bn di Lut c lin quan.
1) Hiu v thc hin y Lut Bo v mi trng, Lut Ti nguyn nc, Lut iu,
Chin lc quc gia v Ti nguyn nc n nm 2020 v cc Ngh nh, Qui nh ca Chnh
ph c lin quan.
2) Thc hin ngi gy nhim phi tr ph.
3) To iu kin thun li cho x hi cng ng tham gia qun l v bo v mi
trng nc.
4) Ci to, ci thin khi phc c kim sot cc dng sng b nhim, b t nh
sng y, sng Nhu, sng Cu, sng Si Gn v cc sng, knh ni .
3. Hn ch v gim thiu suy thoi Ti nguyn nc do Qun l, T chc v Lut
php.
1) Nh nc sm ban hnh y ng b nhng vn bn di Lut hng dn thi hnh Lut
Bo v mi trng v cc Lut c lin quan n Ti nguyn nc.
2) Nh nc sm sa i Lut Ti nguyn nc cho ph hp vi iu kin pht trin
kinh t x hi hin nay ( bc l mt s iu bt cp) v cc vn bn di Lut.
3) Nh nc sm tp trung thng nht c quan qun l Ti nguyn nc thng sut
t Trung ng n a phng v sm thnh lp cc T chc qun l lu vc sng thch hp
vi nhim v chc nng r rng, hot ng c hiu qu thc s do ngi trong lu vc
sng t qun l c s h tr ca Trung ng (ch khng phi ch dng li qun l qui
hoch, m thc cht qui hoch cha c. Lnh o qun l ch yu l ngi ca Trung ng
nn hot ng km hiu qu, hnh thc).
4) Nh nc nn c c ch, chnh sch ngi dn, cc t chc cng ng tham gia
thc s bo v Ti nguyn nc, bo v mi trng nc, to iu kin cho ngi dn tham
gia ngay t khi lp qui hoch xy dng n khai thc s dng v bo v.
5) Nh nc sm ban hnh vn bn qui nh tng bc m bo dng chy mi trng cho
cc con sng con sng thc s c sng, kho v lnh mnh lm c s cho pht trin
bn vng Ti nguyn nc.
MT S BIN PHP X L NC N GIN
1. i vi nc nhim st, phn:i vi nc nhim phn, ta x l nhim bng vi
sng. Ly 10g vi sng cho vo 140l nc, sau nc lng xung, gn ly nc
trong.Nc nhiu st thng c mu vng, mi tanh. Cch n gin lm sch nc nhim
st l nc vo thng, khong ln nhiu ln ri lng, cht ly nc trong.C th dng
phn chua x l nc nhim phn st. Phn chua gi nh (na tha cho 25 lt nc)
vo thng quy nhiu ln st v phn kt ta lng dn xung y.Ngoi ra c th x l
bng phng php sc kh, qua gin ma v bn lng, lc kh st. Lm gin ma bng ng
nha, khoan 150 - 200 l c ng knh t 1,5mm n 2 mm ty theo cng sut my
bm ang s dng. Di cng ca b lc l lp si dy khong 1 gang, trn lp si l
lp ct dy khong 2,5 - 3 gang. Phng php ny c th kt hp x l c mt s cht
khc vi hm lng thp nh: Hydrogen sulfite H2S, Amoniac, Asen.2. X l
Hydrogen sulfite H2S:Nc cha H2S thng khng gy tc hi cho sc kho, nhng
n lm cho nc c mi v v ca trng thi. Nc cp c cha hm lng H2S thp khong
1,0 ppm c c tnh n mn, lm xn mu cc dng bng bc hay ng, lm cho qun o v
gm c vt en.Nc c cha hm lng H2S thp c th c x l bng cch cho lc qua
than. H2S c hp ph trn b mt ca cc ht than. Chng ta phi nh k thay cc
ht than trong b lc (ty thuc vo kh nng hp ph ca than v hm lng H2S
trong nc).3. X l nc cng:Nc cng l thut ng dng ch nc c cha hm lng ln
cc ion nh Ca2+, Mg2+; loi nc ny thng nh hng n tui th cc thit b s
dng nc hng ngy. Cc cch x l n gin: Cch 1: un si nc s lm cc ion ny kt
ta. Cch 2: Dng thit b c ngn cha cc ht lc cationit. Theo qu trnh
trao i ion, ht cationit tch in m s ht cc thnh phn vi trong nc, lm
sch nc.4. Kh trng nc sinh hat: t tiu chun ca B Y t, nc sinh hot bt
buc phi c kh trng. Phng php kh thi r tin l dng nc Javen
(hypochlorit natri ho hc). Cch x l khc l sc clo kh hoc pha ch bt
Clorine vo nc. Cng c th kh trng nc bng ozone hay tia cc tm, nhng
khng ph hp vi vic nc sau kh trng phi tip tc lu chuyn trong ng ng v
b cha.
III. NH NC V NHN DN CNG NU CAO TINH THN TRCH NHIM TRONG S NGHIP
BO V TI NGUYN NCA. Trch nhim ca nh nc v chnh quyn a phng:1. Xy dng
v ph bin cc vn bn Lut, Ngh nh, Quy nh v s dng v bo v Ti nguyn nc.*
Mt s vn bn Lut c ban hnh rng ri:- Lut Ti nguyn nc v thng t hng dn
thc hin;- Cc vn bn x l x pht vi phm hnh chnh trong lnh vc Ti nguyn
v Mi trng* Cc vn bn ang son tho:- Chnh sch tnh thu Ti nguyn nc, thu
ph v l ph nhm gii hn mc s dng v nng cao thc tit kim trong vn s dng
v bo v ngun ti nguyn nc.- Chng trnh gio dc nng cao nhn thc cng ng v
tm quan trng ca vic s dng tit kim v bo v Ti nguyn nc. Chnh sch khen
thng, khuyn khch cc cng trnh nghin cu s dng tit kim nc.2. Hng dn cc
hnh thc khai thc v s dng ngun ti nguyn nc ng k thut bo v Ti nguyn
nc.3. iu tra, kho st nh gi ngun ti nguyn v lp k hach phn vng khai
thc hp l. iu tra nh gi nhng tc ng gy nh hng n Ti nguyn nc.4. Tuyn
truyn vn ng v t chc nhiu cuc thi v thc s dng tit kim v bo v Ti
nguyn nc trong nhn dn t cp qun n cp phng x.
B. Trch nhim ca ngi dn:1. Nu cao thc s dng tit kim v bo v Ti
nguyn nc:Ngi dn phi nhn thc c s nghip bo v Ti nguyn nc khng ch cho
hin ti m cn v th h tng lai, do phi tm hiu v nm vng cc quy nh php
lut v bo v Ti nguyn nc thng qua bo, i pht thanh, truyn hnh... v tch
cc pht huy hng ngy thc s dng tit kim v bo v Ti nguyn nc.2. Nu cao
tinh thn t gic:T gic chp hnh nghim chnh cc quy nh php lut ca nh nc
v bo v Ti nguyn v mi trng3. Quyt tm phi hp vi Nh nc trong cng tc bo
v Ti nguyn nc- Pht hin v mnh dng t co cc hnh vi vi phm php lut ca
nh nc trong s dng v bo v Ti nguyn v Mi trng, khng bao che c tnh lm
tri;- Tham gia cc phong tro ku gi hnh ng v mc ch bo v Ti nguyn v Mi
trng.
