1

TI NGUYN V TR LNG NC DI T

Bin son: PGS TS on Vn Cnh

1. Tng quan v nc di t

Tng lng nc c trn tri t l bao nhiu? Theo tnh ton ca cc nh a

cht M ton tri t c khong 1357,5 triu km3 nc, th ch c 3% l nc nht

(ngt), phn cn li (97%) l nc mn trong cc i dng. Trong s 3% tng nc

ngt trn tri t th c ti 77% nm vng ng bng vnh cu (cc khi bng vng

bc cc, nam cc), cn li ch 1% nc cha trong sng, h trn khp cc chu lc v

11% nc di t su t 800m tr li c th khai thc s dng c, cn 11%

nc di t su t 800m tr xung khng th khai thc s dng trong iu kin

k thut hin nay.

Hnh 1. Phn b nc trn tri t

Th nhng, th gii hin nay khai thc s dng nc di t mnh m nh th

no? Cc nc trn th gii khai thc s dng nc di t khng ng u. Ton

th gii, hng nm khai thc khong 800 km3

(2.191.781.000,0 m3/ngy) t nc di

t . Trong Chu Phi l 35 km3/nm (95.890.411 m3/ngy); Bc v Trung M: 150

(410.959.000); Nam M: 25; Chu : 500; Chu u: 80; Chu c v Chu i Dng:

10 km3/nm.

C 10 nc khai thc nc di t ln nht (chim 74% tr lng nc di

t khai thc trn ton th gii) l n : 190 km3/nm; M: 115; Trung Quc: 97;

Pakistan: 55; Iran: 53; Mexico: 25; Arabia Saudi: 21; Nht Bn: 13,2; Indonesia: 12,5

v Nga: 11,6 (Theo Exploitation and Utilization of Groundwater around the World.

Jean Margat. UNESCO. 10/2000 [4]).

Nc di t M c khai thc t cc tng cha nc trong 6 thnh to

cha nc c bn l thnh to b ri, thnh to ct-bt kt, thnh to carbonat, thnh

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to lc nguyn-carbonat, thnh to phun tro-bin cht v nc trong cc loi thnh

to khc (US Geological Survey).

Nga, khai thc s dng nc di t gn 15 triu m3/ngy. cc thnh ph

ln (hn 100 ngn dn) t trng nc di t ch chim 29%, thm ch cc thnh ph

ln nh Matxcova, San Peterburg, Roctop Na on, Vladivostok.. hon ton s dng

nc mt. T trng s dng nc di t nng thn chim ti 85%.

Nu ly ch s l t s gia tng lng khai thc so vi tr lng nc di t

c th c ti sinh (renewal resources) th sao? Bn do cc nh CTV H Lan

thuc t chc IAH thnh lp nm 2006 gy cho ta nhng n tng su sc v s liu

trn ton th gii [5]. Ch s c gi tr < 20% cho bit lnh th cn d dt nc

di t v c th khai thc bn vng. Nhng nc c ch s 100% v ln hn nm

Trung cn ng v Bc Phi, nc di t ang b cn kit dn. Nhng nc c ch s

t 20% n 100% l nhng nc m y vic khai thc nc di t ch c th bn

vng nu kim sot cht ch vic khai thc nc v c k hoch b sung nhn to

nc di t. Vit Nam nm trong nhng nc c ch s trung bnh.

Hnh 2. Bn ch s nc di t ton cu

Tuy nhin, nhng khu vc c ti nguyn nc di t n nh trn th gii

ang tng ngy thu nh li. C 3 vn chnh nh hng n vic s dng nc di

t: nc di t cn kit do s dng qu mc, do quy hoch khai thc khng ng

v do b ngp ng, nc di t b nhim mn do vic khai thc nc cha hp l v

vic s dng lin tc khng c hiu qu, v nc di t b nhim do cc hot ng

nng nghip, cng nghip v cc hot ng khc ca con ngi gy ra [5].

Vit Nam, ti nguyn d bo nc di t trong cc thnh to cha nc

chnh (thnh to b ri, vi, lc nguyn, bazan) c tnh khong 172,6 triu

m3/ngy, trong khi t trng s dng nc di t cha nhiu. (ngun [3] theo ti

liu iu tra thng k ca Cc Qun l ti nguyn nc, lin on QH v T TNN

min Bc, min Nam. 2013).

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Mt trong nhng ch tiu nh gi s n nh ca ngun nc l thi hn

phc hi ngun nc, ngha l thi gian cn thit nc vn ng t min hnh thnh

n min ph hy. i vi dng chy trn mt tnh trung bnh cho ton a cu, thi

gian c khong 16 ngy m, cn i vi dng ngm - 1,5 ngn nm. Tt nhin bn

c c th hoi nghi s chnh xc ca con s v dng ngm, nhng con s so

snh vi dng chy trn mt.

Do gii hn v phc hi ngun nc cho nn phi c bit ch n bo v

tng cha nc khi b cn kit v nhim.

T y ny sinh mt vn quan trng nht ca CTV khu vc l nh

gi ti nguyn v tr lng nc di dt.

Nn phn bit hai hnh thc nh gi ti nguyn v tr lng khai thc nc

di t, mi mt hnh thc nh gi c nhng tiu ch khc nhau.

nh gi ti nguyn d bo nc di t khu vc bit c tim nng

nc di t mt lnh th nghin cu ( mt vng thm d, mt cu trc a cht cha

nc, mt lu vc sng). Vic nh gi ny khng phi thc hin thng xuyn m

ch tin hnh theo n t hng ca cc t chc quy hoch v qun l lnh th bit

c tim nng ti nguyn nc di t lnh th nghin cu.

Ti nguyn d bo l lng nc c cht lng v gi tr xc nh c th nhn

c trong gii hn mt cu trc a cht thy vn, mt lu vc sng hay mt vng

lnh th c tim nng khai thc s dng sau ny.

i tng nh gi ti nguyn d bo nc di t l cc tng cha nc

trong gii hn mt cu trc a cht thy vn hay trong mt thung lng sng theo kt

qu m hnh ha iu kin a cht thy vn khu vc, bng phng php tnh ton cn

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bng, tnh ton thy ng lc hoc c th bng phng php tng t a cht thy

vn. (Khi nim Ti nguyn d bo nc di t thay cho Tr lng khai thc tim

nng nc di t hin nay ang s dng)

Ti nguyn d bo nc di t th hin bng khi lng (m3, km

3) hoc lu

lng (km3/nm, m

3/ngy) c th nhn c t tng cha nc bng th tch nc tr

trong , hoc bng cc cng trnh khai thc quy c trong gii hn mt cu trc cha

nc, hay trong mt thung lng sng, mt a gii hnh chnh xc nh.

nh gi tr lng nc di t (tr lng khai thc nc di t) c

tin hnh theo cng sut ca cng trnh khai thc c th do t chc yu cu v nc

t hng, trn c s lp lun v s b tr cng trnh khai thc, c s tha thun vi

c quan phng h v snh, bo v mi trng.

Tr lng khai thc nc di t l g? Chng khng phi l khi lng, trng

lng nh khong sn rn, m l lu lng, ngha l lng nc c th ly c theo

thi gian bng cc cng trnh khai thc.

nh ngha c in : Tr lng khai thc nc di t l lu lng cng trnh

khai thc hp l v mt kinh t k thut tun th iu kin khai thc theo t hng.

nh ngha y : Tr lng nc di t (tr lng khai thc nc di

t) l lng nc c th nhn c t m nc hay mt phn m nc bi cc cng

trnh khai thc nc hp l v mt a cht, kinh t k thut trong iu kin v ch

khai thc cho vi cht lng nc tha mn yu cu s dng trong sut thi gian

khai thc, khng gy tc ng mi trng

Tr lng nc di t c tnh ton theo kt qu cng tc thm d a cht

thy vn cng nh theo ti liu khai thc nc di t trong din tch m nc. i

tng tnh ton tr lng nc di t l m nc di t dng cho n ung sinh

hot, k thut v m nc khong.

tnh ton tr lng khai thc cng trnh, khi tm kim thm d phi xc

nh:

S lng l khoan

V tr phn b cng trnh

Cu trc ca cng trnh

Kch thc i phng h v sinh

Khi cn phi chng minh c cng trnh lm vic vi :

ng s lng ging khoan nh th

ng cu trc nh th

Phn b vi s nh th

Lm vic n nh trong thi gian tnh ton

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Trong iu kin nh th mc nc h thp khng vt qu gii hn cho php,

cht lng m bo theo yu cu, khng c tc ng xu n mi trng.

2. L thuyt c bn v ti nguyn v tr lng

Trc khi khai thc : nh gi cn bng trung bnh nhiu nm ca tng cha

nc : Tng n c hnh thnh t tt c cc ngun cung cp bng tng i c hnh

thnh t cc thnh phn thot (ph hy) :

phcc QQ

Trong qu trnh khai thc : Cng trnh khai thc c xem nh mt thnh

phn thot ca cu trc cn bng. V th, khi cng trnh i vo hot ng s xut hin

mt thnh phn cn bng mi lm thay i v cht ca cu trc cn bng. S thay i

th hin :

Lm gim th tch nc trong tng cha nc mt lng bng V

Lm tng tng lng cung cp n i lng bng cccc QQ

Lm gim tng lng ph hy n i lng bng phph QQ

Ti sao cung cp li tng v ph hy li gim ? C th gii thch nh sau :

- Nu s cung cp c tnh cht tim nng, th do chnh lch p lc m c th

din ra qu trnh thm xuyn t cc tng cha nc khc, li ko nc t sng

- Nu cung cp c tnh cht thm, th khi h thp mc nc khng p, s thm

cng gia tng do gim thot do bay hi.

- Nu ph hy t nhin din ra vi s chnh p lc no y trn ranh gii ph

hy (thot nc vo sng, ao h, mch l) th khi khai thc s lm cho s thot y

gim dn v i n ngng thot

- Nu s thot l do bc hi th khi khai thc do h thp mc nc m s bc

hi cng gim, n mt su no y th bc hi ngng hn.

Qu trnh lm gim s thot t nhin khi khai thc c gi l qu trnh nghch

o.

Nh vy phng trnh cn bng tng cha nc khi cng trnh khai thc lm

vic v nguyn tc c vit nh sau :

ktktktphphktcccc tQtQQtQQV )()(

Nu tnh n Qcc = Qph

Th phng trnh c bn cn bng tr lng khai thc c dng:

ccph

kt

kt QQt

VQ

V nguyn tc mi mt i lng trong phng trnh cn bng TLKT c xc

nh ty thuc vo iu kin TL c th, ngha l ph thuc vo thng s, iu kin

bin, thi gian tnh ton, s b tr cng trnh...

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Phng trnh cn bng n gin trong trng hp tng cha nc di dng

bnh nc nh sau [6].

Hnh 3

1. Tng cha nc ch c th tch ; cung cp,

dng chy v ph hy khng c (hnh 3)

- Ch vn ng lun lun khng n nh

- lu lng khai thc ch tn ti mt thi gian

ngn ktQ

Vt

Hnh 4

2. Lu lng cung cp Qcc khng ph thuc vo

v tr mc nc (hnh 4)

- Vn l lu lng thot Qph ph thuc vo ci

g ?

Cc phng n quan h gia lu lng khai thc

v s cung cp:

a) Qkt Qcc ng thi mc nc s

lun lun khng n nh v s thot nc hon

ton o ngc. Khai thc nc vi lu lng

nh th ch c bo m (din ra) trong khong

thi gian cckt QQ

Vt

, sau lu lng khai thc

s gim dn. Phng trnh cn bng nc tr

lng khai thc sau khi o ngc s ph hy c

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dng t

VQQ phkt

Hnh 5

3. Lu lng cung cp Qcc ph thuc vo v tr

mc nc.

S ha c ch cung cp nh th bng cch

thm mt bnh nc c mc nc cao hn (tng

t nh c mt tng cha nc bn cnh). S cung

cp din ra do s chnh mc nc - trong iu

kin khng b ph hy khi tnH i lng cung

cp 0ccQ (hnh 5).

Cc kiu quan h gia lu lng khai thc v

lng cung cp c th :

a) 0cckt QQ

- ng thi mc nc khi khai thc s nh th

no? n nh.

- Mc nc s phn b u? Cao hn mc nc

vng thot (nhng cao hn kiu II. V sao?)

- Cn cn cn bng nc s thay i nh th no ?

Lng thot s gim i mt i lng phQ (thot

ngc mt phn). Ngoi ra, cng cung cp s

tng ln mt i lng phQ , bi v c s gia tng

chnh mc nc ktH .

- Phng trnh cn bng tr lng khai thc c

dng chung nh sau :

)(0 phphktcccc QQQQQ , hoc

ccphkt QQQ

b) 0cckt QQ . Vn ng n nh, nhng mc nc

s phn b cao hn mc nc min thot, ngha l

s thot nc s khng nghch o hon ton.

Dng c bn ca phng trnh cn bng c bo

tn : ccphkt QQQ

c) Cui cng, thm ch trong trng hp lng

khai thc ( mc no y) ln hn lng cung

cp 0cckt QQ cng c th din ra vn ng n

nh. Phng trnh cn bng c dng nh trng

hp trc : ccphkt QQQ

C th bn c s hi ti sao mc nc trong bnh bn cnh trng thi n

nh? Thc ra bc tranh trn hnh 5 khng cha ng thng tin v c ch cung cp ca

bnh hai. Nhng c ch no c th din ra.

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- Nu khng c cung cp th trong iu kin t nhin khng th tn ti hiu s

mc nc tnH , cn khi khai thc mc nc trong c hai bnh tng ng nhau.

- Cn nu c cung cp t nhin, th c ch nh th no?

Nh vy, ng thi thm n nh khi cng trnh lm vic, ch c th c xc

lp trong trng hp nu trong min nh hng ca khai thc c bin gii cung cp v

(hay) bin gii thot nc, m trn bin din ra s thay i tng cng gi tr cung

cp t nhin (hay ph hy t nhin) bng vi gi tr khai thc : bphcckt QQQQ ,

y tnbkt

bb QQQ - tng thay i lu lng qua tt c cc bin.

Trong thc t tnh ton cn lu du ca lu lng : cung cp : mang du (+),

ph hy : mang du (-). khng nhm ln v ni chung khng phi ngh v du th

trong cc cng thc thy ng lc lun lun t mc nc trn bin Hb:

/)( tnbtn

b HHQ /)( kttnb HHQ

/)( tnbkt

b HHQ (lun lun ln hn khng)

Trong cc cng thc trn Htn, Hkt mc nc trn bin ca lp, l sc cn

thm no ca bin.

Chng ta quay li phng trnh cn bng chung tr lng khai thc:

Qkt = V/tkt + Qb + Qcc

Tr lng tnh t nhin Qttn s lng nc trong lp (v nguyn tc th l

trng lng, nhng i vi nc nht l khi lng). C ph thuc vo vn ng hay

khng? i lng Qttn ph thuc vo kch thc ca thnh to cha nc (din tch,

chiu dy) v cc thng s cha ( nh nc). Ty thuc vo t m nh nc

c phn ra lm nh nc dung tch v nh nc n hi. n v o l khi

lng, nhng trong phng trnh c xc nh nh lu lng (ly ra theo thi gian

khai thc).

Tr lng ng t nhin - tng i lng cung cp ca tng cha nc trong

iu kin t nhin (d nhin c i lng thot t nhin). Cn lu l trong phng

trnh cn bng tr lng khai thc, khng phi l tng tr lng ng t nhin c

hnh thnh t din tch thu nc no ca cng trnh, m ch l s thay i lu lng

thot, ngha l ch mt phn i lng tr lng ng t nhin m cng trnh khai thc

thu hi c do phu h thp p lc lan n min thot t nhin.

Tr lng khai thc Tr lng tnh t

nhin

S cung cp t

nhin

Tr lng cun

theo

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Tr lng cun theo mt thnh phn trong cn bng tr lng pht sinh trong

qu trnh khai thc cng trnh. l tng lu lng cung cp b sung cho tng cha

nc khai thc (b sung ti bao nhiu? ti gi tr cng b sung t nhin). C hai

kh nng pht sinh ngun tr lng cun theo.

- Trong min cung cp t nhin - c tng cng do h thp mc nc khai

thc (v d nh trnh by trn, tng cng thm xuyn, tng cng thm thng

ng);

- Trong min thot nc t nhin - thu hi dn phn thot ca nc di t t

cc mch l, thot do bay hi.

Mt vn quan trng cn lu l, cc thnh phn tham gia vo phng trnh

cn bng tr lng khai thc c th thay i theo thi gian ty thuc vo khong cch

t cng trnh khai thc n cc ranh gii t nhin.

3. Tiu ch v qun l lu vc

3.1. Khi nim v ti nguyn v tr lng nc di t

Nc di t l loi khong sn lu ng, khc vi khong sn rn s ht dn

i trong qu trnh khai thc, nc di t c th s khng bao gi ht nu bit khai

thc hp l. Hn na, tr lng nc di t c th tng thm khi bit cch khai

thc. i vi nc di t c cc loi ti nguyn v tr lng sau y:

Ti nguyn v tr lng tnh l lng nc c thng xuyn trong cc tng

cha nc. Ti nguyn v tr lng tnh ca nc di t tng t vi ti nguyn v

tr lng ca khong sn rn.

Tr lng ng l lng nc lu thng trong t , lng nc chy qua tit

din dng thm trong 1 n v thi gian hay lng nc c cung cp hng nm ca

tng cha nc. V d nh nc ma hay nc mt ngm xung b sung cho nc

di t. Ngoi ra, cho nc di t c th lu thng c ngoi ngun b sung

cn c min thot. Nc thot i thng chm hn so vi ngun b sung, lng nc

thot i khng kp s nng cao mc nc ca tng cha nc. Ngc li, khi ngun b

sung ngng, qu trnh thot nc s lm cho mc nc ca tng cha nc thp dn

xung. Do lng nc lu thng trong tng cha nc lun lun thay i theo thi

gian.

Tr lng cun theo: Khi thai thc, mc nc ca tng cha nc h thp

xung c th li cun ngun nc khc vo trong tng cha nc v tham gia vo

lng nc khai thc. Lng nc b li cun vo do qu trnh khai thc gy ra, gi l

tr lng cun theo. Trong thc t bao gi cng mong mun cht lng nc cun

theo phi tt khng nh hng ti cht lng nc khai thc. Nhiu khi tr lng

cun theo ny v cng quan trng, n lm tng ng k lng nc khai thc. Tt

nhin lm c nh vy th cc l khoan khai thc nc phi b tr gn sng, nu

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b tr trong khu vc dn c, nc cun theo t cc lp cha nc nm nng s khng

m bo cht lng v lp nc nm nng thng d b nhim.

Lng nc di t c th khai thc c t l khoan ph thuc vo cc

ngun hnh thnh tr lng. Cn trit tn dng tr lng ng v nu khng khai

thc ht n s chuyn thnh dng mt v mt i khng th li dng c. Mun tn

dng tr lng ng phi b tr cc cm khai thc trn tuyn thng gc vi hng

nc chy. Ngoi ra, tng tr lng khai thc cn c gng to ra v tng tr lng

cun theo c cht lng tt, c bit l s dng dng nc mt t sng sui, khi

cn b tr cc l khoan ven theo b sng, sui. V d, H Ni nu khng c lng

nc cun theo t sng Hng vo th ton b khu vc ni thnh ch c th khai thc

vi trm nghn mt khi mt ngy, nhng nh c lng nc cun theo m c th khai

thc hn mt triu mt khi trong mt ngy. Nu tr lng cun theo l nc thm

xuyn t tng cha nc ny sang tng cha nc khc th cn b tr cm l khoan

khai thc lm sao gy ra s chnh p ng k gia hai tng cha nc kch thch

thm xuyn. Cui cng, l xt n ngun ti nguyn v tr lng tnh. Khng nn xm

phm vo ti nguyn nc tnh. Nu v l do no phi khai thc vo ngun ti

nguyn v tr lng tnh th cn tnh ton lng khai thc cho hp l n c thi

gian phc hi, nu khng n s hao ht dn v c th dn n cn kit.

3.2. Qun l lu vc bng vic s dng lun phin ngun nc

Trong cc lu vc, pht trin ton din ngun nc th s dng lun phin

ngun nc l cch s dng nc ti u v c li nht. N bao gm c s dng ngun

nc mt v nc di t nhm p ng yu cu, trong mt chng mc no , nh

vy cc ngun nc s c bo ton. S khc nhau c bn gia vic m rng thng

xuyn ngun nc mt hay ngun nc di t vi vic kt hp m rng v s dng

lun phin c hai ngun ny l ch: nhng tr lng bn vng ring r s c thay

th bng tr lng chung rng ln hn v kinh t hn. C s m bo cho vic s

dng lun phin ngun nc mt v ngun nc di t l da vo cc h cha nc

mt, ni tp chung nc t cc sng sui sau nc s c chuyn vi tr lng

ti a vo cc kho cha di t. Vo nhng nm lng ma t di trung bnh th

lng nc tr trong cc h cha l ngun cung cp chnh do yu cu nc hng nm,

khi nc di t c gi li ch phc v cho vng tun hon ca kho nc di

t m thi. Thc vy, mc nc di t s dao ng v b h thp xung trong sut

chu k ca vng tun hon vo nhng nm t ma v sau li c nng ln vo thi

k ma nhiu tip theo. iu ny c th hin trong hnh 6 di y. Trong giai on

m lng nc ma di trung bnh hng nm th nc mt c tn dng trong phm

vi ln nht c th v l ngun b sung nhn to cung cp thm vo kho cha

nc di t cng nh lm tng mc nc di t. Ngc li, vo ma hn hn khi

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ngun nc mt b hn ch th n li c b sung bi ngun nc di t t cc

ging khoan v lm cho mc nc di t li h thp xung. Tnh kh thi s dng

lun phin ngun nc ph thuc vo s hot ng ca lu vc nc di t nhiu

hn l vo s dao ng ca mc nc di t, ngha l cn c th tch ln cha

nc khi c b sung c th ht khi cn thit.

Hnh 6. Thay i ca mc nc di t khi s dng lun phin ngun

nc, tng ng vi lng ma nm

Qun l nc di t bng cch s dng lun phin ngun nc i hi c cc

iu kin t nhin thun li cho vic phn b nc, b sung nhn to ngun nc v

ht nc. N i hi c k hoch cn thn, chnh xc s dng hiu qu cc ngun

nc mt v nc di t. Qu trnh hot ng ny c th l tp hp ca nhiu b

phn khc nhau vi cc ng dng k thut cao. N i hi nhng nhn vin gii, c

kin thc su v a cht thy vn lu vc. Ngoi ra cn phi lun ghi li tr lng

nc ht ln v lng nc b sung vo lu vc, thng xuyn cp nht thng tin v

mc nc di t v cht lng nc. S v cch tip cn h thng khi phn tch

s dng lun phin ngun nc c thc hin trong hnh 7 v 8.

nghin cu s dng lun phin ngun nc cn thu thp cc d liu v

ngun nc mt v nc di t, cc iu kin a cht, cc d liu v h thng phn

b nc v s dng nc, cc ti liu v tiu thot nc thi. Trn hnh 7 m t s

gm nhiu pha khc nhau v cc bc trong qun l lu vc, c nghin cu th

nghim California. C th thy rng cc m hnh tnh ton thng c s dng kt

hp vi nhau trong nghin cu. M hnh lu vc m phng s bin i ca mt lu

vc theo s thay i ca cc ngun b sung t nhin, b sung nhn to v ht nc t

cc ging. Nh m hnh c th tin hnh c cc hot ng hiu qu nht trong qun

l lu vc. ng dng m hnh vo thc t s gp phn ti u ha vic cp v ht nc

t cc lu vc.

12

Bng 1. So sng u nhc im khi s dng lun phin ngun nc vi khi ch

s dng ngun nc mt cho mc ch ti l chnh.

TT u im Nhc im

1 Bo tn nc nhiu hn Tim nng thy in gim

xung

2 D tr nc mt nh hn Tiu th nng lng ln

hn

3 H thng phn phi nc mt nh hn Hiu sut ht nc gim

4 H thng thot nc nh hn Nhim mn nc di t

tng ln

5 Lp bo v mi knh gim xung K hoch hot ng phc

hp nhiu hn

6 Tng kh nng kim sot l i hi ngun b sung

nhn to

7 C th hp nht cc hng pht trin hin c Gy nguy him do ln st

mt t

8 Cc giai on pht trin tr nn d dng hn Kh khn cho vic phn

b vn

9 Tn tht nc do bc hi nh hn

10 Kim sot tt hn lng nc chy i mt

11 Ci thin h s s dng trm bm v cng

sut my bm

12 Gim bt nguy him t s chp v, ghp ni

cc im thiu ht

13 Gim bt nhng im phn phi yu km

14 iu ha thi gian phn phi nc tt hn

Tng lng nc cung cp c th c tng ln nu xc nh ng c im,

kh nng ca cc ngun nc mt v nc di t. Mt phng n ti u c th lm

cho gi thnh cp nc v phn phi nc gim xung thp nht. Cc yu cu c bn

v lu vc nc di t c th qun l ti u ngun nc gm c:

1. Kh nng cha nc ca cc khi nc mt v cc tng cha nc di t

cn phi kt hp vi nhau t c tnh s dng kinh t nht ca ngun nc ti

ch v c c tr lng ti u m bo cho kh nng bo tn ngun nc.

2. H thng phn phi nc mt cn phi kt hp c vi cc c tnh truyn

dn ca lu vc nc di t nhm to ra gi r nht cho h thng phn phi.

3. Cc c quan iu hnh phi c y quyn lc trong vic qun l cc

ngun nc mt, cc ngun cp b sung cho nc di t, cc h thng phn phi

nc mt v khai thc nc di t.

C s pht trin vic s dng lun phin ngun nc trong lu vc l s

nh gi cc thnh phn khc nhau trong vic cung cp v phn phi nc. Vic s

13

dng ti u cc ngun nc mt v nc di t thng c xem xt theo nhng

iu kin bt li, xy ra vo nhng thi k hn hn nng n nht quan trc c.

Hnh 7. S cch tip cn h thng nghin cu vn s dng lun phin

ngun nc

Xc nh bi ton t nhin

Xc nh mc yu

cu ca bi ton

Xc nh cc thng s

vt l, kinh t v x hi

Xc nh tm quan trng

ca cc nhn t trong h

thng

Xc nh mc tiu

H thng cn bng

ng; m hnh ton

Kim tra m hnh

S dng m hnh

Chnh sch ti u

S dng cc chnh sch ti

u

S liu

Hc tp a ra cc

quyt nh

Kt

thc

Kt thc

Cc tiu

chun bao

gm c yu t

x hi

14

Phn tch hot

ng kinh t

Cc

phn

tch a

cht

thu vn

Pht trin

s b

mng li

ng ng

trong m

hnh

Cc phn

tch s b

mng li

ng ng

nh gi

cng

sut v

v tr ca

thit b

hin c S lng

thit b v

cht lng

nc cung

cp ca

mi h

thng hot

ng

Lch s

cp

nc, s

dng v

cung cp

Nhu cu

nc

trong

tng lai

v ngun

cung cp

Phng

trnh cho

cc k

hoch la

chn ca

hot ng

M phng

cch iu

hnh hot

ng ca cc

h thng trn

mt v gn

mt t

Cc

phn

tch v

a

cht

Pht trin

v th

nghim

cc m

hnh ton

ca lu

vc nc

ngm

Phn tch v

cc k

hoch khai

thc trn m

hnh ton

lu vc

nc ngm

Phn tch

n gi ca

cc thit b,

nng lng,

ngun cp

nc

Gi thit

b nng

lng,

ngun cp

nc ca

mi nh

my khai

thc

So snh

gi ca

cc

phng n

Hnh 8. S cc bc nghin cu qun l lu vc nc di t

15

TI LIU THAM KHO

1. on Vn Cnh, Nguyn Th Thanh Thy. Thu gom nc ma a vo lng t.

B sung nhn to nc di t v chng ng ngp thnh ph. Nh Xut bn khoa hc v k

thut. Nm 2008. 108 trang.

2. on Vn Cnh v nnk. Bo co tng k ti KC.08.06/11-15

3. Nguyn Thu Hin, H Vit Hng, Trnh Minh Th. Gio trnh Pht trin v qun l

ti nguyn nc di t. D n tng cng nng lc o to cho Trng i hc Thy li

ca Chnh ph an Mch - Danida. Wru/Scb. Nh xut bn Gio dc. Thng 12 nm 2007.

255 trang .

4. Jean Margat. Exploitation and Utilization of Groundwater around the World. Co-

published by UNESCO et BRGH. Paris, 2007.

5. Managed Aquifer Recharge and Storage: Making better use of ours largest

reservoir. Netherlands National Committee of the Dutch Chapter of the IAH. IAH-UNESCO,

2006.

6.

, ,

30 2007 . 195.

7. ... (

.

..). ( , 2014)

.